JPH04182618A - Magneto-optical element - Google Patents

Abstract

PURPOSE:To obtain the magneto-optical element which is high in operating response speed, is large in contrast ratio, is simple in construction and inexpensive by sealing magnetic fluid into the part corresponding to the spacing in a yoke core on which a coil is wound by a light transmissive member, thereby forming the thin film of the magnetic fluid. CONSTITUTION:The magnetic field in a prescribed direction is generated in the spacing part 3 of the yoke core 2 when the coil 7 is energized. A magneto- optical effect is then generated in the magnetic fluid 5 and controls the light transmission characteristics, such as transmitted light quantity and transmitted light intensity and, therefore, the on-off of light are controlled by on-off controlling the energization and de-energization of the coil 7. In addition, medium gradation light can be transmitted by regulating the current of the coil 7. The response speed of the on-off actions is extremely faster than the on-off actions of the conventional electrooptical elements and a high contrast ratio is assured. The correct resolution of the medium gradation, etc., is obtd. when this element is applied to a display, etc. Further, the material cost of the magnetic fluid 5 which is a main driving material is extremely low and, therefore, the cost of production is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magneto-optical element, and more particularly to a magneto-optical element for switching between light transmission and non-transmission using the magneto-optic effect of a magnetic fluid.

[Conventional technology]

Conventionally, for example, in high-resolution projection displays, liquid crystal displays, or optical devices such as cameras and laser printers, light has been turned on and off for each pixel.
Transmission and non-transmission of light is performed by switching FF or using an optical shutter.

Conventionally, when performing such light switching, electro-optical elements such as LCD elements, ferroelectric LCD elements, or PLZT elements have been widely used.

By controlling the energization of the electro-optical element such as the LCD element and driving the electro-optical element, light transmission or non-transmission control is performed.

[Problem to be solved by the invention]

However, in electro-optical devices such as the conventional LCD device and ferroelectric LCD device, ON for energization control,
The response speed of OFF operation is extremely slow, and it may be difficult to turn ON or OFF.
The problem is that the contrast ratio during FF operation is small and it is difficult to obtain appropriate resolution.

In addition, in any of the above electro-optical devices, light is turned on,
It is an OFF-only operation, and the amount of light transmitted cannot be adjusted, and it is possible to emit light with an intermediate gradation that semi-transmits the light from the light source. However, there are problems in that the material cost is high and the manufacturing cost is extremely high.

The present invention has been made in view of the above-mentioned points, and has a high operational response speed, a large contrast ratio, and can be applied to various optical devices.In addition, it has a simple structure and is inexpensive. The object of the present invention is to provide a magneto-optical element that can be manufactured in a number of steps.

[Means to solve the problem]

In order to achieve the above object, there is provided a magneto-optical element according to the present invention as set forth in claim 1, which is a magneto-optical element for switching between transmission and non-transmission of light using the magneto-optic effect of a magnetic fluid. The present invention is characterized in that a magnetic fluid thin film formed of a fluid in the form of a thin film and a magnetic field applying means for applying a magnetic field to the magnetic fluid thin film are integrally disposed on a light-transmitting substrate.

The magneto-optical element according to the present invention as set forth in claim 2 is a magneto-optical element for switching between light transmission and non-transmission using the magneto-optic effect of a magnetic fluid. A gap part for forming a magnetic field is formed in a part of one surface side, a yoke core around which a coil is wound is fixed, and a magnetic fluid is applied to a part of the substrate corresponding to the gap part of the yoke core in a translucent manner. It is characterized in that it is enclosed by a member to form a magnetic fluid thin film.

[For production]

According to the present invention as set forth in claims 1 and 2, by energizing the coil as the magnetic field applying means,
The magneto-optical effect generated when a magnetic field in a predetermined direction generated in the gap between the yoke cores is applied to the magnetic fluid is used to control light transmission characteristics such as the amount of transmitted light and the intensity of transmitted light. As a result, the coil is energized,
, OFF control, it is possible to perform ON/OFF control of light, and furthermore, by adjusting the current applied to the coil, it is possible to transmit intermediate gray scale light.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 6.

1 to 3 show an embodiment of the magneto-optical element according to the present invention, in which a rectangular frame shape constituting a magnetic field applying means is provided on one side of a substrate 1 made of a transparent material such as glass. A yoke core 2 is fixed to the substrate 1 with a gap 3 formed in a portion of the yoke core 2 located approximately in the center of the substrate 1, and a lower end portion of the yoke core 2 is protruded to the outside of the substrate 1. This is a winding part 4.

Further, the magnetic fluid 5 leaks into the gap portion 3 of the yoke core 2 due to a cover glass 6, which is an example of a transparent member fixed to the surface side of the yoke core 2, and a circularly formed sealing bottle 6a. The magnetic fluid 5 is formed by mixing magnetic powder such as ferric oxide powder or magnetite with water or an organic solvent such as cyclohexane or ethanol. It is something that will be done. The sealing bottle 6a may be formed on either the substrate 1 or the cover glass 6, or an adhesive for fixing the cover glass 6 to the substrate 1 may be used as the sealing bottle 6a. Good too. Further, depending on the case, the sealing bottle 6a may be omitted and the sealing may be performed by the surface tension of the magnetic fluid 5.

Further, the yoke core 2 is configured to function as a spacer for determining the film thickness of the magnetic fluid 5, and the thickness of the yoke core 2 is, for example, 50 μm or less, preferably about 10 μm. ing. As a result, a thin film of the magnetic fluid 5 is formed in the gap 3 of the yoke core 2 between the substrate 1 and the cover glass 6.

Further, a coil 7 is wound around several hundred turns around the winding portion 4 of the yoke core 2, and by energizing the coil 7, a magnetic field is generated in the gap 3 of the yoke core 2. It is something that can be done.

Next, the operation of this embodiment will be explained.

In this embodiment, by energizing the coil 7, a magnetic field in a predetermined direction is generated in the gap 3 of the yoke core 2, and when this magnetic field is applied to the magnetic fluid 5, the magneto-optical effect is exerted on the magnetic fluid 5. Occur. This magneto-optic effect is used to control the light transmission characteristics such as the amount of transmitted light and the intensity of transmitted light, and as a result, by controlling the ON/OFF of the current to the coil 7. , it is possible to perform ON/OFF control of light, and furthermore, by adjusting the current applied to the coil 7, it is possible to transmit intermediate gradation light.

The magneto-optic effect is a phenomenon that occurs when a magnetic field is applied in a direction perpendicular to the direction of force of linearly polarized light, resulting in a difference in refractive index between the direction of the magnetic field and the direction perpendicular, that is, birefringence. If the phase difference between the polarized light component perpendicular to the magnetic field and the polarized light component parallel to the magnetic field in this case is 6, then δ can be expressed by the following equation.

δ=2π(n//n)d/λ where n// and n are the refractive indices in the direction parallel and perpendicular to the magnetic field, respectively, and d is the optical path length in the magnetic fluid (perpendicular to the magnetic fluid). (thickness of the ferrofluid), λ is the wavelength.

Further, δ is also a function of H (magnetic field), and the transmittance of light in vertically polarized light and horizontally polarized light relative to the magnetic field also changes depending on the magnetic field. As a result, by controlling the current applied to the coil 7 and applying an appropriate magnetic field to the magnetic fluid 5, it is possible to
It is also possible to control the ON/OFF state of light and the intermediate gradation of the amount of transmitted light.

Then, a polarizer and an analyzer (both not shown) are arranged on the front surface of the substrate 1 and the rear surface of the cover glass 6, or the substrate 1 and the cover glass 6 are arranged to serve as a polarizer and an analyzer, respectively. When light is irradiated from the polarizer side, only linearly polarized light is transmitted through the polarizer and is incident on the magnetic fluid 5.

In this case, when the coil 7 is not energized,
Since the thin film of the magnetic fluid 5 does not exhibit birefringence,
If linearly polarized light is incident on an analyzer and the polarization direction of the analyzer 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 7 is energized, birefringence occurs in the thin film of the magnetic fluid 5, so when the linearly polarized light that has passed through the polarizer passes through the thin film of the magnetic fluid 5, it becomes elliptically polarized light, Polarized light is also generated that passes through the analyzer having a polarization plane in a direction perpendicular to the polarization plane, and this polarized light is transmitted. In addition, the transmitted light intensity I is the phase difference δ due to birefringence.
On the other hand, there is a relationship of Iocsin2 δ/2, and since δ is a function of the magnetic field, ■ also changes depending on the magnetic field, that is, the current of the coil 7.

By controlling ON/OFF of the current to the coil 7 in this way, light can be turned ON/OFF via the magnetic fluid 5.
By adjusting the current applied to the coil 7, the degree of elliptical polarization of the light emitted from the magnetic fluid 5 can be changed. It is capable of transmitting a certain amount of intermediate gradation light.

On the other hand, in this embodiment, by controlling the energization to the coil 7, a magnetic field can be applied to the magnetic fluid 5 and the light can be turned on and off. Instead, it can be applied to various optical instruments. For example, by arranging a large number of the yoke cores 2 in the magnetic fluid 5, or by arranging a large number of magneto-optical elements into an array, an optical shutter corresponding to each pixel of a laser printer head or a liquid crystal display, etc. It becomes possible to apply it to In this case, the width of the gap 3 of the yoke core 2 is preferably formed to be approximately equal to the diameter of the laser beam spot. In addition, compared to electro-optical devices such as conventional LCD devices and ferroelectric LCD devices, the response speed of 0NXOFF operation to energization control is extremely fast.
A large contrast ratio can be ensured during the 0N1OFF operation, and when applied to a display or the like, it becomes possible to obtain appropriate resolution such as intermediate gradation.

Furthermore, since the material cost of the magnetic fluid 5, which is the main driving material, is extremely low, manufacturing costs can be reduced.

Furthermore, in this embodiment, since the yoke core 2 functions as a spacer for the sealed portion of the magnetic fluid 5, the film thickness of the magnetic fluid 5 can be easily defined, and manufacturing efficiency can be significantly increased. Furthermore, since the winding portion 4 of the yoke core 2 protrudes from the substrate 1,
The winding work of the coil 7 can be performed extremely easily.

Furthermore, since the thin film of the magnetic fluid 5, the yoke core 2 serving as the magnetic field applying means, the coil 7, etc. are integrally formed on one substrate 1, the structure is simple and the device can be miniaturized and miniaturized. It is easy to manufacture, and the manufacturing cost can be reduced.

It should be noted that if the heat generated by energizing the coil 7 or the heat generated by the magnetic fluid 5 itself is significant, the substrate 1
Instead of glass, an alumina substrate with a transparent light-transmitting part may be used as the forming material, or a metal thin film for heat dissipation with an opening formed in the light-transmitting part may be attached. .

FIG. 4 shows another embodiment of the present invention, in which the yoke core 2 is divided into two at the center of the winding portion 4, and the other configuration is the same as that of the embodiment described above. It is similar to the example.

In this embodiment, as in the previous embodiment, by controlling the energization to the coil 7, a magnetic field can be applied to the magnetic fluid 5 to control the ON/OFF of the light.
It can be applied to various optical devices. Furthermore, the response speed of the ONXOFF operation to the energization control can be significantly increased, a high contrast ratio can be ensured, and the manufacturing cost can be reduced.

Furthermore, in this embodiment, since the yoke core 2 is divided, the ease of assembling the yoke core 2 can be significantly improved.

Furthermore, FIG. 5 shows another embodiment of the present invention,
Similar to the embodiment shown in FIG. 4, the yoke core 2 is divided into two parts at the center of the winding portion 4 thereof. In this embodiment, as shown in FIG. 6, a bobbin 8 for winding the coil 7 is provided separately from the yoke core 2.

This bobbin 8 is formed with a through hole 9 into which the tip of the yoke core 2 is inserted, and each of the yoke cores 2
, 2 to the substrate 1, the yoke core 2 is inserted into the through hole 9 of the bobbin 8 around which the coil 7 was wound in the separate process.
The bobbin 8 is attached to the yoke core 2 by fitting the tip of the bobbin 8 into the yoke core 2.

In this embodiment, as in the above-mentioned embodiments, the light can be turned on and off by controlling the power supply to the coil 7, so it can be applied to various optical devices, and the ON and OFF operations can be controlled. Not only can the response speed be significantly increased, but also a high contrast ratio can be ensured, and furthermore, manufacturing costs can be reduced.

Furthermore, in this embodiment, since the coil 7 is attached to the yoke core 2 by attaching the bobbin 8 on which the coil 7 is wound in advance to the split type yoke core 2, the yoke core 2 is attached to the board 1. in a state where
Compared to the case where the coil 7 is wound, the winding operation of the coil 7 can be performed extremely easily, and manufacturing efficiency can be significantly improved.

Note that the present invention is not limited to the above embodiments,
Various changes can be made as necessary.

〔Effect of the invention〕

As described above, the magneto-optical element according to the present invention can control the ON/OFF of light by applying a magnetic field to the magnetic fluid by controlling the energization of the coil. Instead, it can be applied to various optical instruments. In addition, compared to conventional electro-optical devices, the response speed of ON and OFF operations to energization control is extremely fast, and a large contrast ratio can be ensured during ON and OFF operations, making it ideal for applications such as displays. In addition, it is possible to obtain appropriate resolution such as intermediate gradation, and the structure is simple and compact.
Since the material cost of the magnetic fluid, which is the main driving material, is extremely low, manufacturing costs can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the present invention, and FIG. 2 is a perspective view showing one embodiment of the present invention.
3 is a side view of FIG. 1, FIG. 4 is a perspective view showing another embodiment of the invention, and FIG. 5 is a perspective view showing still another embodiment of the invention. FIG. 6 is a perspective view of the bobbin of FIG. 5. DESCRIPTION OF SYMBOLS 1... Board, 2... Yoke core, 3... Gap part,
4... Winding part, 5... Magnetic fluid, 6... Cover glass, 7... Coil, 8... Bobbin.

Claims (1)

[Scope of Claims] 1. A magneto-optical element for switching between transmission and non-transmission of light using the magneto-optic effect of a magnetic fluid, comprising: a magnetic fluid thin film in which the magnetic fluid is formed into a thin film; 1. A magneto-optical element, characterized in that a magnetic field applying means for applying a magnetic field to a thin film is integrally disposed on a transparent substrate. 2. In a magneto-optical element for switching between transmission and non-transmission of light using the magneto-optic effect of a magnetic fluid, a gap for forming a magnetic field is formed in a part of one surface side of a transparent substrate. In addition, a yoke core around which a coil is wound is fixed, and a magnetic fluid is sealed in a portion of the substrate corresponding to the gap between the yoke cores with a transparent member to form a magnetic fluid thin film. optical element.