JPH04219720A - Magnetic optical element - Google Patents

Abstract

PURPOSE:To apply a magnetic optical element to an optical shutter or the like corresponding to the head of a laser printer and each picture element of a liquid crystal display or the like by executing the ON-OFF control of applying an electric current to a coil for the ON-OFF control of light. CONSTITUTION:In a magnetic optical element to change over the transmission and nontransmission of light by using the magnetic optical effect of magnetic fluid, one face side of a substrate having light transmitting ability is partially provided with a gap for forming a magnetic field, and many yoke cores wound with coils are arranged and fixed to this side, and magnetic fluid is sealed into a part corresponding to the gap of the yoke core on the substrate by means of a member having light transmitting ability to form a magnetic fluid thin film.

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 light transmission and non-transmission using the magneto-optic effect of a magnetic fluid.

0002

2. Description of the Related Art Conventionally, for example, in high-resolution projection displays, liquid crystal displays, or optical devices such as cameras and laser printers, light is turned on and off for each pixel, and optical shutters are used to Switching between light transmission and non-transmission is performed.

[0003] Conventionally, when performing such light switching, electro-optical elements such as LCD elements, ferroelectric LCD elements, or PLZT elements have been widely used.

[0004] Light transmission and non-transmission control is performed by driving the electro-optical element by controlling the energization of such an electro-optical element such as an LCD element.

[0005]

[Problem to be solved by the invention] However, the conventional L
In electro-optical devices such as CD devices and ferroelectric LCD devices, the response speed of ON and OFF operations to energization control is extremely slow, and the contrast ratio during ON and OFF operations is small, making it difficult to obtain appropriate resolution. It has the problem of being difficult.

[0006] In addition, in any of the above-mentioned electro-optical devices, the operation is only to turn on and off the light, and the amount of light transmitted cannot be adjusted. Furthermore, all of the electro-optical devices described above have the problem of high material costs and extremely high manufacturing costs.

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

[0008]

[Means for Solving the Problems] 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-optic effect of a magnetic fluid. A gap for forming a magnetic field is formed in a part of one side of a transparent substrate, and a large number of yoke cores around which coils are wound are arranged and fixed, and in the gap between the yoke cores of the substrate. The feature is that a magnetic fluid thin film is formed by sealing magnetic fluid in the corresponding portion with a transparent member.

[0009]

[Operation] According to the present invention, by energizing a coil corresponding to a desired yoke core based on a predetermined control signal, a magnetic field generated in a predetermined direction generated in the gap of the yoke core is applied to the magnetic fluid, thereby generating a magnetic field. It uses optical effects to control light transmission characteristics such as the amount of transmitted light and the intensity of transmitted light, and as a result, it is possible to turn on the current to the coil.
, 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. Furthermore, since a large number of yoke cores are arranged in an array on the substrate, it can be applied to optical shutters corresponding to each pixel of a laser printer head, a liquid crystal display, etc.

0010

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 shows an embodiment of the magneto-optical element according to the present invention. On one side of a long substrate 1 made of a transparent material such as glass, there are squares constituting magnetic field applying means. A large number of frame-shaped yoke cores 2, 2... are fixed, and a gap 3 is formed in a part of each yoke core 2. In each of the yoke cores 2, the gap 3 is linear at approximately the center of the substrate 1, and has a gap of about 50 μm, for example.
The lower end portions of each of these yoke cores 2 are projected to the outside of the substrate 1 to form a winding portion 4.

Further, on the surface of the substrate 1, a rectangular frame-shaped sealing dam 5 is formed along the longitudinal direction of the substrate 1 so that the gap 3 of the yoke core 2 is located inside the sealing dam 5. A magnetic fluid 6 is sealed inside the sealing dam 5 by a translucent cover glass 7 fixed to the surface side of the substrate 1 so as not to leak.

The magnetic fluid 6 is formed by mixing magnetic powder such as ferric oxide powder or magnetite with water or an organic solvent such as cyclohexane or ethanol. Note that the sealed weir 5 is
It may be formed on either the substrate 1 or the cover glass 7, or an adhesive for fixing the cover glass 7 to the substrate 1 may be used as the sealing dam 5. Furthermore, depending on the case, the sealing dam 5 may be omitted and the surface tension of the magnetic fluid 6 may be used for sealing.

The thickness of the yoke core 2 is, for example, 50 μm or less, preferably about 10 μm. As a result, a thin film of the magnetic fluid 6 is formed in the gap 3 of the yoke core 2 between the substrate 1 and the cover glass 7.

Furthermore, a coil 8 is wound around several hundred turns around the winding portion 4 of the yoke core 2, and by energizing the coil 8, 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 8 corresponding to a desired yoke core 2 based on a predetermined control signal, a magnetic field in a predetermined direction is generated in the gap 3 of the yoke core 2, and this magnetic field By being added to the fluid 6, a magneto-optical effect is generated in the magnetic fluid 6. and,
This magneto-optical 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 8, the light can be controlled. It is possible to perform ON/OFF control, and by adjusting the current applied to the coil 8, 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 travel of linearly polarized light.
A difference in refractive index between the magnetic field direction and the perpendicular direction, that is, birefringence, occurs. 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 δ, then δ can be expressed by the following equation.

δ=2π(np −nv)d/λwhere, np and nv 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 (the optical path length perpendicular to the magnetic fluid). , the thickness of the ferrofluid), and 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 energizing current to the coil 8 and applying an appropriate magnetic field to the magnetic fluid 6, it is possible to determine whether the light is ON or OFF or the intermediate gradation of the amount of transmitted light based on the phase difference or the magnitude of the change in optical output. It is also possible to control the

A polarizer and an analyzer (both not shown) are placed on the front surface of the substrate 1 and the rear surface of the cover glass 7.
Alternatively, if the substrate 1 and the cover glass 7 are formed to serve as a polarizer and an analyzer, respectively, and light is irradiated from the polarizer side, only linearly polarized light is transmitted through the polarizer. Then, the magnetic fluid is incident on the magnetic fluid 6.

In this case, when the coil 8 is not energized, the thin film of the magnetic fluid 6 does not exhibit birefringence, so the linearly polarized light enters the analyzer, and the polarization direction of the analyzer is determined. If placed 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 8 is energized, birefringence occurs in the thin film of the magnetic fluid 6, so when the linearly polarized light that has passed through the polarizer passes through the thin film of the magnetic fluid 6,
Polarized light becomes elliptically polarized light and passes through an analyzer having a polarization plane in a direction perpendicular to the polarization plane of the polarizer, and this polarized light is transmitted. In addition, the transmitted light intensity I is, with respect to the phase difference δ due to birefringence,

[0024]

Since δ is a function of the magnetic field, I also changes depending on the magnetic field, that is, the current in the coil 8.

In this way, when the coil 8 is turned on,
By performing OFF control, it is possible to perform ON/OFF control of the light via the magnetic fluid 6, and by adjusting the current applied to the coil 8, the ellipse of the light emitted from the magnetic fluid 6 can be changed. Since the degree of polarization can be changed, it is possible to transmit intermediate gradation light with an amount of light between ON and OFF.

Therefore, in this embodiment, by controlling the energization to the coil 8, a magnetic field can be applied to the magnetic fluid 6 to control the ON/OFF of light, which is different from the conventional electro-optical device. Instead, it can be applied to various optical instruments. Further, in this embodiment, the substrate 1
Since a large number of yoke cores 2 are arranged in an array on the top, it can be applied to a head of a laser printer, an optical shutter corresponding to each pixel of a liquid crystal display, etc. 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, ON/OF control for current control is
The response speed of F operation is extremely fast, and the ON/OFF
It is possible to ensure a large contrast ratio during operation,
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 6, which is the main driving material, is extremely low,
Manufacturing costs can be reduced.

Further, in this embodiment, the film thickness of the magnetic fluid 6 can be easily defined by the yoke core 2, and manufacturing efficiency can be significantly increased. Since the coil 8 protrudes from the substrate 1, the winding operation of the coil 8 can be performed extremely easily.

Furthermore, since the thin film of the magnetic fluid 6 and the large number of yoke cores 2, coils 8, etc., which are magnetic field applying means, are integrally formed on one substrate 1, the structure is simple, and the device can be made smaller and finer. It is easy to manufacture, and the manufacturing cost can be reduced.

[0030] Note that heat generation due to energization of the coil 8,
Alternatively, if the magnetic fluid 6 itself generates significant heat, an alumina substrate with a transparent light-transmitting portion may be used instead of glass as the material for forming the substrate 1, or an alumina substrate with a transparent light-transmitting portion may be used instead of glass. A metal thin film for heat dissipation having an opening formed therein may be attached.

Further, the yoke core 2 may be divided into two parts at the center of the winding portion 4. In this case, the ease of assembling the yoke core 2 can be significantly improved.

Furthermore, when the yoke core 2 is divided into two at the center of the winding portion 4, a bobbin (not shown) on which the coil 8 is pre-wound is attached to the divided yoke core 2. This makes it possible to wind the coil 8 much more easily than in the case where the coil 8 is wound with the yoke core 2 attached to the substrate 1, and the manufacturing efficiency can be significantly increased.

FIG. 2 shows another embodiment of the present invention, in which a large number of yoke cores 2, 2, etc. are formed on one side of a long substrate 1 made of a transparent material. For example, 50 μm or less, preferably 10 μm
A gap portion 3 is formed in a part of this yoke core 2, and a symmetrical side of the gap portion 3 of this yoke core 2 is a winding portion 4. In each of the yoke cores 2, the gap portions 3 are arranged in a straight line at approximately the center of the substrate 1 and at equal intervals.

Further, a magnetic fluid 6 is sealed in the gap 3 of the yoke core 2 on the surface of the substrate 1 by a rectangular frame-shaped sealing weir 5 and a cover glass 7 so as not to leak. A thin film of the magnetic fluid 6 is formed in the gap 3 of the yoke core 2 between the magnetic fluid 6 and the cover glass 7.

Furthermore, in this embodiment, a coil 8 is formed on the winding portion 4 of the yoke core 2 of the substrate by a thin film forming technique.

That is, in this coil 8, a lower coil 8a corresponding to the back side of the yoke core 2 is formed on the surface of the substrate 1, and after the yoke core 2 is formed on the surface of this lower coil 8a, the winding of this yoke core 2 is formed. upper coil 8b on the surface of the
is formed such that its lower end is connected to the lower end of the lower coil 8a, and its upper end is successively connected to the upper end of the adjacent lower coil 8a.

[0037] In this example as well, as in the previous example,
By controlling the energization to the coil 8, the magnetic fluid 6
Since the light can be turned on and off by applying a magnetic field to it, it can be applied to various optical devices. In addition, the response speed of ON/OFF operations to energization control can be significantly increased, a high contrast ratio can be ensured, and manufacturing costs can be reduced.

Furthermore, in this embodiment, since each of the yoke cores 2 and coils 8 is formed using thin film forming technology, it is possible to form the yoke cores 2 and coils 8 of very small dimensions with great ease. Manufacturing efficiency can be significantly increased.

FIG. 3 shows another embodiment of the present invention, in which two divided yoke cores 2 are formed on one side of a substrate 1 made of a transparent material by a thin film forming technique. Further, the winding portion 4 of the yoke core 2 of the substrate 1
A spiral coil 8 is formed using a thin film forming technique.

That is, the yoke core 2 and the coil 8 form one lower yoke core 2a located on the lower side on the surface of the substrate 1. After forming the spiral coil 8, the upper yoke core 2b is formed to be connected to the winding portion 4 of the lower yoke core 2a.

Other parts are the same as those of the embodiment shown in FIG. 2 above.

[0042] In this embodiment, as in the above-mentioned embodiments, the light can be turned on and off by controlling the energization to the coil 8, so it can be applied to various optical devices. , it is possible to significantly increase the response speed of the OFF operation, it is possible to ensure a large contrast ratio, and it is also possible to reduce manufacturing costs.

Furthermore, the yoke core 2 and the coil 8
Since these are each formed using thin film forming technology, the yoke core 2 and coil 8 of minute dimensions can be formed extremely easily, and manufacturing efficiency can be significantly improved.

The sealing weir 5 for sealing the magnetic fluid 6 may be formed of a thin film of SiO2, alumina, etc. using a thin film forming technique.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be modified in various ways as necessary.

[0046]

[Effects 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 to the coil. It can be applied to various optical devices instead of conventional electro-optical devices. In addition, compared to conventional electro-optical devices, the response speed of ON and OFF operations to energization control is extremely fast, and a high contrast ratio during ON and OFF operations can be ensured, making it suitable for applications such as displays. In addition, it becomes possible to obtain appropriate resolution such as intermediate gradation. Furthermore, since a large number of yoke cores are arranged in an array on the substrate, it can be applied to optical shutters that correspond to each pixel of laser printer heads and liquid crystal displays, etc., and the structure is simple. In addition to being compact, the material cost of the magnetic fluid, which is the main driving material, is extremely low, so manufacturing costs can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is a partial front view showing an embodiment of the present invention.

[Figure 2]
A partial front view showing another embodiment of the present invention

FIG. 3 is a partial front view showing another embodiment of the present invention.

[Explanation of symbols]

1 Board 2 Yoke core 3 Gap part 4 Winding section 5 Sealed weir 6 Magnetic fluid 7 Cover glass 8 Coil

Claims (1)

[Claims] Claim 1: A magneto-optical element for switching between transmission and non-transmission of light using the magneto-optic effect of a magnetic fluid, in which a gap for forming a magnetic field is provided on one side of a transparent substrate. A large number of yoke cores each having a section formed thereon and a coil wound thereon are arranged and fixed, and a magnetic fluid is sealed in a portion of the substrate corresponding to the gap between the yoke cores using a transparent member to form a magnetic fluid thin film. A magneto-optical element characterized by forming: