JPH0588129A - Magnetooptic element - Google Patents

Abstract

PURPOSE:To provide the magnetooptic element which has a high operation response speed and a large contrast ratio and is applicable to various equipments, simple in structure, and manufactured at low cost. CONSTITUTION:The magnetooptic element switches the transmission and nontransmission of light by using the magnetooptic effect of magnetic liquid 6; and a yoke core 1 which has a gap part 2 for magnetic field production formed partially and is wound with a coil 4 is arranged, and a magnetic liquid thin film formed by charging the magnetic liquid 6 between a couple of transparent substrates 5 is arranged at the gap part 2 of the yoke core 1.

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 gap for forming a magnetic field is formed in a part, and a yoke core around which a coil is wound is arranged.
A magnetic fluid thin film formed by enclosing a magnetic fluid between a pair of translucent substrates is disposed between the yoke core and the gap.

[0009]

According to the present invention, when a coil corresponding to a desired yoke core is energized on the basis of a predetermined control signal, a magnetic field in a predetermined direction generated in the gap of the yoke core is applied to the magnetic fluid. The optical effect is used to control the light transmission characteristics such as the amount of transmitted light and the intensity of transmitted light.
Light ON / OFF by controlling N / OFF
The control can be performed, and moreover, the halftone light can be transmitted by adjusting the current supplied to the coil. Further, the magnetic fluid thin film portion in which the magnetic fluid is sealed between the substrates and the magnetic field generating portion by the yoke core are separately configured, and the substrate in which the magnetic fluid is sealed is disposed between the yoke core gaps to provide a magneto-optical element. Since the magnetic fluid can be encapsulated independently, the magnetic fluid can be reliably and optimally encapsulated, and the shape of the yoke core can be freely designed. Therefore, the thickness of the yoke core can be freely set to appropriately set the magnetic field strength of the magnetic circuit.

[0010]

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

FIG. 1 shows an embodiment of a magneto-optical element according to the present invention. In this embodiment, a quadrangular frame-shaped yoke core 1 constituting a magnetic field applying means is provided.
A gap 2 is formed in a part of the yoke core 1. Furthermore, a portion of the yoke core 1 on the opposite side of the gap 2 is a winding portion 3, and the winding portion 3 of the yoke core 1 has a coil 4 wound around several hundreds of turns. Then, by energizing the coil 4,
A magnetic field can be generated in the gap portion 2 of the yoke core 1.

Further, in this embodiment, a pair of substrates 5 and 5 made of a transparent material such as glass is provided separately from the yoke core 1, and a magnetic fluid 6 is provided between the pair of substrates 5, for example. , So that the thickness dimension is 50 μm or less. The magnetic fluid 6 is formed, for example, by mixing magnetic powder such as ferric oxide powder or magnetite (magnetite) with water or an organic solvent such as cyclohexane or ethanol.

The substrate 5 thus filled with the magnetic fluid 6 is disposed between the gap portions 2 of the yoke core 1 such that the enclosed surface of the magnetic fluid 6 is parallel to the surface of the yoke core 1. In this way, a magneto-optical element is formed.

Next, the operation of this embodiment will be described.

In this embodiment, when a coil 4 corresponding to a desired yoke core 1 is energized based on a predetermined control signal, a magnetic field in a predetermined direction is generated in the gap 2 of the yoke core 1, and this magnetic field is magnetized. When added to the fluid 6, a magneto-optical effect is generated in the magnetic fluid 6. Then, using this magneto-optical effect, for example, the amount of transmitted light,
The light transmission characteristics such as 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 power supply to the coil 4, and the coil 4 can be controlled. The halftone light can be transmitted by adjusting the energizing current to.

The magneto-optical effect is a phenomenon that occurs when a magnetic field is applied in 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 parallel to the magnetic field and the direction perpendicular thereto, 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 4 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.

Then, on the upper surface and the lower surface of the substrate 5,
A polarizer and an analyzer (both not shown) are arranged, or each of the substrates 5 is formed so as to also serve as a polarizer and an analyzer, respectively. Only the linearly polarized light is transmitted through and enters the magnetic fluid 6.

In this case, when the coil 4 is not energized, the thin film of the magnetic fluid 6 has no birefringence, so that 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 4 is energized, birefringence occurs in the thin film of the magnetic fluid 6, so that when linearly polarized light that has passed 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:

[0022]

Since δ is a function of the magnetic field, I also changes with the magnetic field, that is, the current of the coil 4.

In this way, the energization of the coil 4 is turned on,
By performing the OFF control, the ON / OFF control of the light can be performed through the magnetic fluid 6, and by adjusting the current flowing to the coil 4, 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 the present embodiment, by controlling the energization of the coil 4, it is possible to apply a magnetic field to the magnetic fluid 6 to control the ON / OFF of light, so that the conventional electro-optical device can be controlled. 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, the magnetic fluid 6 thin film portion in which the magnetic fluid 6 is enclosed between the substrate 5 and the magnetic field generating portion by the yoke core 1 are separately formed, and the gap 2 between the yoke cores 1 is formed. Since the magneto-optical element is formed by disposing the substrate 5 in which the magnetic fluid 6 is enclosed, it is possible to independently perform a heat treatment suitable for processing the substrate 5 in which the magnetic fluid 6 is enclosed. Therefore, the magnetic fluid 6 can be reliably and optimally sealed. Moreover,
The shape of the yoke core 1 can be freely designed without being influenced by the configuration of the magnetic fluid 6. For example, by setting the thickness of the yoke core 1 freely, the strength of the magnetic field of the magnetic circuit can be adjusted appropriately. Can be set to. further,
By manufacturing the magnetic fluid 6 thin film portion and the magnetic field generating portion separately, they can be easily manufactured and the manufacturing efficiency can be remarkably enhanced.

By arranging a large number of yoke cores 1 in parallel so that a large number of the substrates 5 are arranged in an array, an optical shutter or the like corresponding to each pixel of a head of a laser printer, a liquid crystal display or the like. Can be applied to.

FIG. 2 shows another embodiment of the present invention. The yoke core 1 in which the gap portion 2 is formed has a large thickness, and the gap portion 2 of the yoke core 1 is formed. In between, a pair of substrates 5 in which the magnetic fluid 6 is sealed are arranged so that the surface filled with the magnetic fluid 6 is perpendicular to the surface of the yoke core 1. Further, a light transmission hole 7 is formed at an optical path position of the winding portion 3 of the yoke core 1 which transmits the substrate 5, and in the winding portion 3 of the yoke core 1, the coil 4 transmits the light. It is wound so as not to block the hole 7 portion.

Also in this embodiment, similar to the above embodiment,
By controlling ON / OFF of energization to the coil 4, it is possible to control ON / OFF of light via the magnetic fluid 6, and by adjusting the energization current to the coil 4, Since the degree of elliptically polarized light of the light emitted from the magnetic fluid 6 can be changed, ON, O
It is possible to transmit the intermediate gradation light having a light amount of about the middle of FF.

In this case, in this embodiment, the light transmitted through the magnetic fluid 6 is irradiated to the inner surface of the yoke core 1, but the light transmission hole 7 is formed at the optical path position of the yoke core 1. Therefore, the light transmitting hole 7 allows the light transmitted through the magnetic fluid 6 to pass through the yoke core 1 and be sent to a predetermined position.

Therefore, in this embodiment as well, as in the previous embodiment, by controlling the energization of the coil 4, it is possible to apply a magnetic field to the magnetic fluid 6 to control the ON / OFF of light. It can be applied to various optical devices, and the response speed of ON / OFF operation for energization control can be remarkably increased, and ON / O
It is possible to secure a large contrast ratio during the FF operation and further reduce the manufacturing cost.

Also in this embodiment, since the magnetic fluid 6 thin film portion in which the magnetic fluid 6 is enclosed between the substrate 5 and the magnetic field generating portion by the yoke core 1 are separately configured, they can be easily manufactured. Further, the magnetic fluid 6 can be surely and optimally sealed, and the shape of the yoke core 1 can be freely designed.

Further, in this embodiment, the substrate 5
Are arranged in a direction perpendicular to the surface of the yoke core 1, the light passing through the magnetic fluid 6 of the substrate 5 is applied to the winding portion 3 of the yoke core 1. Since the light transmitting hole 7 is arranged at the optical path position of 1, the light transmitted through the magnetic fluid 6 can be properly taken out of the yoke core 1.

It should be noted that a large number of yoke cores 1 are arranged in parallel and the substrates 5 are arranged in the gaps 2 of the yoke core 1 respectively, or a long shape is formed in the gaps 2 of the plurality of yoke cores 1 arranged in parallel. If one substrate 5 formed in the above is arranged 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, or the like. In this case, in this embodiment, since the yoke cores 1 can be arranged in the thickness direction, the space efficiency can be remarkably improved.

Further, since the yoke core 1 is formed to have a large thickness, the substrate 5 can be placed on the upper surface of the gap portion 2 of the yoke core 1.

The present invention is not limited to the above embodiment, but various modifications can be made as necessary.

[0037]

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 the magnetic fluid thin film portion enclosing the magnetic fluid and the magnetic field generating portion by the yoke core are separately configured, the magnetic fluid can be surely and optimally enclosed, and the shape of the yoke core is formed. It is possible to design freely regardless of the structure of the magnetic fluid. Furthermore, by separately manufacturing the magnetic fluid thin film portion and the magnetic field generating portion, the magnetic fluid thin film portion and the magnetic field generating portion can be manufactured very easily, the manufacturing efficiency can be remarkably improved, and the material cost of the magnetic fluid is extremely low. In addition, the manufacturing cost can be remarkably reduced.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing another embodiment of the present invention.

[Explanation of symbols]

 1 yoke core 2 gap part 3 winding part 4 coil 5 substrate 6 magnetic fluid 7 light transmission hole

Claims (1)

[Claims] 1. A magneto-optical element for switching between transmission and non-transmission of light using the magneto-optical effect of a magnetic fluid, in which a gap for forming a magnetic field is partially formed and a coil is wound. A magneto-optical element, wherein a yoke core is disposed, and a magnetic fluid thin film, in which a magnetic fluid is sealed between a pair of translucent substrates, is disposed between the yoke core and the gap portion.