JP2005057649A - Electromagnetic wave converging device made of shape storage polymeric material,its mirror plane ramification and the profile retain method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for making a reflector itself with super light weight and its support/development structure to be super light weight and realizing a development function by low power and a developed mirror surface curve maintenance function and to provide an electromagnetic wave converging device provided with such functions. <P>SOLUTION: In this electromagnetic wave converging device, polymeric materials having a shape storage function are adopted as its materials, and a designated shape is a thin plate in shape with a metal film applied to the surface of the thin plate. The electromagnetic wave focusing device maintains its folded state in a low temperature state and becomes its developed state in a high temperature state. The reflector factor of the surface of the electromagnetic wave converging device and the radiation rate of a rear surface are adjusted by coating to maintain the proper temperature of the electromagnetic wave converging device. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electromagnetic wave focusing device, in particular, an electromagnetic wave focusing device used as a condensing device for utilizing solar energy or an electromagnetic wave transmitting / receiving device for communication for transmission / reception, and a mirror surface development / shape maintaining method of the reflecting mirror.

  Conventional reflecting mirrors are generally used in which a light-weight and rigid resin such as CFRP (carbon fiber reinforced plastic) is applied to an electromagnetic wave reflecting surface formed of a metal thin film or net in a parabolic shape. It is difficult to achieve high accuracy, light weight, and low price at the same time. Higher accuracy generally involves an increase in weight, and in particular, it does not satisfy the revolutionary weight reduction required for space electromagnetic wave focusing devices. In addition, many of the conventional methods for deploying reflectors of electromagnetic wave focusing devices use electric motors and mechanical devices (gears, latches, springs, etc.), so there are limits to weight reduction and power consumption. Not a few.

  For space applications, gas expansion reflectors (including support structures) are mainly studied in the United States for ultra-lightweight and space deployment, and the mirror surface and its support structure in space can be achieved with ultra-light weight. There are advantages. (Refer to Non-Patent Document 1 and Non-Patent Document 2) However, it is extremely difficult to form a specified shape such as the rotary part surface shape with sufficient accuracy in this method. Moreover, in order to enclose gas, it is necessary to install a transparent film in front of the reflecting surface, and electromagnetic waves pass through this layer twice. The transparency is not enough, and the loss of transparency is inevitable because the deterioration of transparency due to radiation in outer space cannot be avoided. In the case of space use, it is assumed that space debris collides with the film, and gas flows out from the hole generated by the collision, thereby causing a pressure drop and maintaining an axially symmetric paraboloid shape. It becomes difficult. At the same time, the outflow of gas continues to disturb the attitude of the spacecraft carrying the reflector, so it is necessary to operate the propulsion device (small rocket) continuously to correct this, and a large amount of propellant is required. It becomes a big burden.

  In addition, regarding the weight reduction, Non-Patent Document 3 and Non-Patent Document 4 introduce prototypes of polymer film focusing mirrors aimed at reducing the weight of the focusing mirror. In such a situation, the National Institute of Aerospace Technology recently conducted research on an ultralight electromagnetic wave focusing device including a solar focusing mirror made of a film material. Japanese Patent Application No. 2002-302695 “Thin Film Expanded Structure, Thin Film for It Deploying method and thin film unfolding unit and thin film unfolding system ", Japanese Patent Application No. 2003-62584" Solar Thermal Propulsion System, and Method for Voluntary Disposal of Used Artificial Satellites Using It ", Japanese Patent Application No. 2002-239694" Ultralight Electromagnetic Wave " Patent Document 1 relating to focusing by two orthogonal line-focus reflectors and “focusing device and manufacturing method thereof” have already been filed. What is an electromagnetic wave focusing device constructed in space as an extension of the technology? It has led to the study of the problem of whether it is transported to outer space in a lightweight and compact form and can be easily constructed in outer space. .

JP 2003-124741 A “Variable Focal Length Electromagnetic Focusing Device” Published on April 25, 2003 P. E. Frye, J. A. McClanahan, “Solar Thermal Propulsion Transfer Stage for the First Pluto Mission,” AIAA-93-2601, 29th Joint Propulsion Conference & Exhibit, 1993. David Lichodziejewski, Costas Cassapakis, “Inflatable Power Antenna Technology,” AIAA-99-1074, 1999. Yasuharu Sakashita, Hironori Sahara, Morio Shimizu, Yoshihiro Nakamura, “Prototype of Ultralight Condenser in Solar Thermal Propulsion System,” 43rd Space Science and Technology Union Lecture, 2000. Yasuhiro Matsui, Hironori Sahara, Morio Shimizu, Yoshihiro Nakamura, “Solar Thermal Propulsion System for Ultra-Small Satellites-Ultralight Solar Condenser,” 2001 Space Transportation Symposium, 2002.

As an electromagnetic wave focusing device for space, it is not only necessary to reduce the weight of the reflector itself with high accuracy, but it is also necessary to develop a mechanism for maintaining the shape of the specified shape such as the deployment of the reflector and the paraboloid in space. Weight reduction is also an important matter that is strongly demanded in order to reduce launch costs in terms of total weight. In particular, in the development and maintenance of the shape described above, when a mechanism such as a drive unit such as a motor or a mechanism or mechanical part such as a latch is used, not only an increase in weight but also an increase in necessary power that is a very valuable problem in space is brought about. Become. Therefore, there is a strong demand to solve the problems of ultra-lightweight reflecting mirror itself and its supporting and unfolding structure, ultra-light weight, realization of unfolding function at low power, and mirror surface maintenance function after unfolding. Yes.
The problem to be solved by the present invention is to obtain a mirror surface development and shape maintaining method of an ultralight / low power reflecting mirror of an electromagnetic wave focusing device that can meet these requirements.

In order to solve the above problems, in the electromagnetic wave focusing device of the present invention, a polymer material having a shape memory function is adopted as the material, and the specified shape is a thin plate shape, and a metal film is applied to the thin plate surface. It is assumed that the folded state is maintained in the low temperature state and the unfolded shape is obtained in the high temperature state.
In the case where the electromagnetic wave focusing device is an axisymmetric rotating parabolic reflector, a small hole is provided in the central portion of the reflector.
As a different form, the electromagnetic wave focusing device of the present invention is an axisymmetric rotary parabolic reflector, which employs a plastic material as its material and has a thin plate shape and a metal film applied to the thin plate surface. It is assumed that a support structure made of a shape memory material is attached to the circular frame, and the folded state is maintained in a low temperature state and is expanded in a high temperature state.
In addition, the electromagnetic wave focusing device of the present invention is housed in a small state in a small container having a temperature control function, and when heated by the temperature control function, it jumps out of the small container and becomes an unfolded shape.

The electromagnetic wave focusing device of the present invention is a flexible / extended support made of a material having a shape memory function, in which a reflecting mirror made of a polymer material having a shape memory function is mounted on an artificial satellite in a low temperature state. It is assumed that it is fixedly housed in the satellite body through the structure, and in a high temperature state, the bending / extension-type support structure extends to deploy the reflector outside the satellite body, and the reflector is rotated axisymmetrically. It shall be a parabolic shape.
In the electromagnetic wave focusing device of the present invention, a method of adjusting the reflectance of the front surface and the emissivity of the back surface by coating to maintain an appropriate temperature of the electromagnetic wave focusing device is adopted.
In the electromagnetic wave focusing device of the present invention, a polymer material having a shape memory function is adopted as the material, and the shape is a thin plate shape, and a metal film is applied to the surface of the thin plate, which is transported to outer space. For the period, we adopted a deployment and shape maintenance method for the electromagnetic wave focusing device that keeps the folded state and heats it in outer space to form a deployed shape.

The electromagnetic wave focusing device of the present invention employs a polymer material having a shape memory function as its material, and the specified shape is a thin plate shape and a metal film is applied to the surface of the thin plate. The weight can be reduced and the structure is developed by the shape memory function of the structure material, so that no separate equipment or power source is required as a deployment mechanism. That is, the effect of weight reduction and low power becomes remarkable.
In addition, as the electromagnetic wave focusing device of the present invention, an axisymmetric rotating paraboloidal reflecting mirror having a small hole in the central portion of the reflecting mirror can be folded without causing plastic deformation at the stage before deployment. Can take shape.
The electromagnetic wave focusing device of the present invention is an axisymmetric rotational paraboloid reflecting mirror, and adopts a plastic material as its material, and the shape is a thin plate, and the surface of the thin plate is provided with a metal film, The circular frame can take a form in which a support structure made of a shape memory material is attached. In this case as well, the weight of the reflector itself can be reduced and the shape of the material of the support structure Since the structure is deployed by the memory function, no separate equipment or power source is required as a deployment mechanism.

The electromagnetic wave focusing device according to the present invention adopting a configuration in which the reflecting mirror is housed in a small container having a temperature control function when the reflector is heated by the temperature control function. Since it pops out into a deployed shape, there is no need for a separate equipment or power source as a deployment mechanism, and the effects of weight reduction and low power consumption are remarkable.
In a low temperature state, the reflector made of a polymer material having a shape memory function has a circular plate shape, and is fixedly stored in the satellite body through a bending / extension support structure made of a material having a shape memory function. The electromagnetic wave focusing device of the present invention adopting the form can be stored compactly during transportation, and when heated in outer space, the bending / extension-type support structure automatically extends, and the reflecting mirror is placed outside the satellite body. Since the reflecting mirror has an axisymmetric rotational paraboloid shape, the weight of the reflecting mirror itself can be reduced, and the structure is supported and deployed by the shape memory function of the material of the structure. Therefore, no separate equipment or power source is required as a support / deployment mechanism, and the effects of weight reduction and low power consumption become remarkable.

In the present invention, since the method of adjusting the reflectance of the front surface and the emissivity of the back surface of the electromagnetic wave focusing device by coating and maintaining an appropriate temperature of the electromagnetic wave focusing device is adopted, the electromagnetic wave focusing device using the shape memory material The temperature state in each of the folded state, the unfolded state, and the shape maintenance of the structure can be reasonably maintained.
The method for maintaining and maintaining the shape of the electromagnetic wave focusing device of the present invention employs a polymer material having a shape memory function as the material of the electromagnetic wave focusing device having a specified shape, and the shape is a thin plate, and a metal film is formed on the surface of the thin plate. Therefore, during the transportation period to outer space, the folded state can be maintained in a stable and compact form, and it can be automatically expanded by heating to high temperature in outer space. That is, the reduction of the total weight of the apparatus brings about a reduction in launch costs, solves the problem of having a mirror surface shape maintenance function after deployment without requiring a special power source for deployment and low power.

In order to solve the above-described problems, in the electromagnetic wave focusing device of the present invention, a deployment function based on temperature control is realized by employing various polymer materials having a shape memory function as the mirror surface material. These shape memory materials change greatly in physical properties at a specific settable temperature (glass transition temperature), and have “shape fixability” and “shape recoverability” on the basis of the change. Therefore, it is possible to control the shape by controlling the temperature of the shape memory material. By adopting this on the mirror surface of the reflecting mirror, it is possible to provide a deployment function and to maintain a specified mirror surface shape such as a rotating paraboloid shape. Can be given.
In addition, by adopting a thin polymer shape memory material as the material for the mirror surface itself, it is possible to reduce the weight of the reflecting mirror. Furthermore, by adopting a shape memory polymer material as the material for the support structure of the reflector, the function of deploying the reflector of the flexible member by controlling the temperature of the support structure can be realized.

When storing the reflecting mirror, the reflecting mirror and its support / deployment mechanism are stored in a low temperature region with the shape fixed. In deploying the reflecting mirror, the shape required at the time of deployment is obtained by shifting the shape memory material member temperature of the reflecting mirror and the support / deployment mechanism to a high temperature region with an electric heater heat source or the like. After deployment to space, it is necessary to move to a low temperature region and obtain high rigidity, but the temperature drop may not be sufficient due to the shape memory material member hitting the sun, but with solar condensing mirrors etc. It is possible to lower the temperature to a low temperature region by coating the aluminum with a mirror-finished surface that is exposed to sunlight and applying a black paint on the back (side) surface thereof.
The developed shape memory reflecting mirror surface, especially in the case of solar orientation, needs to face the solar direction, so the area irradiated with sunlight is maximized and there is a concern about temperature rise. By adjusting the reflectance of 0.8 to 0.92 and the emissivity of the back surface to about 0.9 with black paint, the temperature reaches a low temperature close to minus 100 degrees Celsius in theory. It is well possible to fasten. Conversely, the mirror surface temperature can reach 120 degrees Celsius or more by reducing the emissivity to 0.05 by mirror finishing and aluminum coating on the back surface. The boundary temperature (glass transition temperature) between the high temperature region and the low temperature region of the shape memory material can be set to 30 to 100 degrees Celsius. Therefore, the ultra-lightweight membrane cover with a low emissivity such as the above-mentioned aluminum coating, or the ultra-lightweight membrane-like electric heater is deployed in outer space with the back surface of the reflector surface covered, and the reflector surface is moved to a high temperature. The specified mirror surface shape is obtained by restoring the shape. Thereafter, by removing this cover or heater, the reflecting mirror surface can be shifted to a low temperature region, and a highly rigid operation state can be obtained.
In the above, a solution when a shape memory polymer material is employed has been shown. However, as a material having a shape memory function, there is a shape memory alloy, which can be used in combination.

  One example of the method for developing and maintaining the shape of the reflecting mirror of the electromagnetic wave focusing apparatus of the present invention will be described with reference to the drawings. FIG. 1A shows an axisymmetric rotating parabolic reflector as an example of the present invention. In the figure, reference numeral 1 denotes a reflecting mirror 1, and a paraboloid is formed with rotational symmetry with respect to an axis 2. Reference numeral 3 denotes an outer peripheral edge of the reflecting mirror, and 4 denotes an outer peripheral portion support structure 4. This figure shows a shape after development. FIG. 1B shows that the projected figure from the axial direction of the reflecting mirror is circular. Further, when the shape before deployment is a circular flat plate that can be easily folded for storage, the shape is also shown in FIG. Moreover, since this circular flat plate is also a compact form, it can also be stored and accommodated in this form. In the figure, 5 at the center is a small hole, which has the effect of avoiding plastic deformation when folded. In addition, when folding, it is necessary to make it fold in a bent state so as not to crease.

  As one method for accommodating the disk-shaped reflector in a small volume, it is proposed to provide a small hole 5 at the center of the disk. As a result, the circular plate can be folded in two as shown in FIG. 1C, folded in four as shown in FIG. Due to the presence of the small holes 5, it is possible to fold without causing plastic deformation near the center of the circular plate. Of course, in the folding described above, the fold line 6 shown in FIGS. 1C and 1D has a considerably large radius of curvature so as not to cause plastic deformation. Further, in this folding, there is also a method in which the final shape is made into a cone by rounding off from the folding line 6 after the second folding or the fourth folding. Further, instead of rounding, a method of folding the fan in the same manner as the method of folding the fan can be adopted. However, it is necessary not to make a crease at that time. The small hole 5 at the center is not useful for electromagnetic wave focusing. However, in the case of an axisymmetric rotating parabolic reflector, the small hole 5 is behind the transmission / reception unit of the electromagnetic wave focusing device installed at the focal point. The provision does not cause a decrease in focusing efficiency.

  As shown in FIG. 2 (A), the condenser reflector 8 folded in a small volume as described above is housed in a small container 9 with a temperature control function in the artificial satellite body 7, and the shape memory material is cooled at a low temperature. Store at the temperature conditions of the area. The small container 9 is made of, for example, a film-like electric heater material, so that it is not necessary to install a special heating means and can be reduced in weight. When the reflecting mirror is deployed outside the artificial satellite, the temperature of the small container 9 is entered to enter a high temperature region, and the reflecting mirror is deployed in a designated shape as shown in FIG. It is preferable that the side surface of the small container 9 is tapered so that the condensing mirror 8 is folded in a conical shape so that the condensing mirror 8 is surely jumped out of the small container 9 and unfolded. After that, even under the condition of irradiating with sunlight, it is possible to put the temperature of the reflecting mirror in a low temperature region by appropriately setting the reflectance and radiation rate of the front and back surfaces of the reflecting mirror.

  Further, as shown in FIG. 2C, a plane can be selected as the shape of the circular plate reflecting mirror during storage in a low temperature region. In that case, the volume it occupies is never large. Therefore, if the circular flat plate can be properly stored in the satellite body 7 with a small volume, it can be stored in the low temperature region in that state and transferred to the high temperature region by temperature control with a heater or the like during deployment. Get the specified specular shape. Since it enters into a low temperature region by exposing it to outer space as it is, it can reach a specular shape such as a rotating paraboloid as shown in FIG.

  Further, not only the mirror surface material of the reflecting mirror but also the shape of the support structure can be adopted, and its temperature can be controlled in the same manner as the film surface to contribute to the development. For example, when a very thin circular frame-like support structure 4 is attached to the outer peripheral part 3 of the reflector in FIG. 1, if this material is a shape memory material, it is folded in FIGS. 1D and 2A. In the unfolding operation of unfolding from the dead state, the unfolding is possible by temperature control. If necessary, a circular frame structure made of a shape memory material can also be attached to the small holes 5.

  In FIG. 2, when the reflecting mirror is stored, the bending / extending support / deployment structure 10 of FIG. 2C is folded and the reflecting mirror 11 is stored in the artificial satellite body 7. At the time of deployment, the support / deployment structure 10 is extended by temperature control, and the reflecting mirror 11 deformed into a circular flat plate shape is pushed out of the satellite and returned to the shape of the reflecting mirror. As a result, the shape is designated as in the reflecting mirror 1 of FIG. Since the support structure 4 in this case is extremely thin, it is included in the outer periphery 3 of the reflecting mirror. In this embodiment, the mirror material and the support structure material do not necessarily have to be the same material in order to set the deployment procedure, and the transition temperature of the mirror material and the support structure need to be the same. No. Since various shape memory materials can be adopted in the right place according to the characteristics of the reflector, the support structure and the deployment mechanism, the degree of freedom in design is great.

  The present invention is developed on the assumption of an electromagnetic wave focusing device that is transported to outer space by a rocket and used as a deployment structure in outer space, particularly a concentrating device for using solar energy, or an electromagnetic wave transmitting / receiving device for communication for transmission / reception. However, the present invention is not limited to this, and can also be used as an electromagnetic wave focusing device for ground installation.

It is explanatory drawing made into compact forms, such as folding the reflective mirror in this invention. It is a figure explaining the accommodation form and deployment form which loaded the electromagnetic wave focusing apparatus of this invention in the artificial satellite main body.

Explanation of symbols

1 Rotating parabolic reflector
2 Rotating shaft
3 Rotating parabolic reflector outer periphery 4 Circular frame-shaped support structure 5 Small hole in the center of the reflector 6 Folding line of the circular plate reflector 7 Satellite body (in this case, cubic shape)
8 Folding reflector 9 Small cylindrical container with temperature control function 10 Bending / extension-type support / deployment structure of reflecting mirror 11 Disc flat reflector in an unfolded state in an artificial satellite

Claims (7)

The electromagnetic wave focusing device having a specified shape employs a polymer material having a shape memory function as its material, and the shape is a thin plate with a metal film applied to the surface of the thin plate. An electromagnetic wave focusing device which maintains a state and becomes a developed shape in a high temperature state. The electromagnetic wave focusing device is an axisymmetric rotating paraboloid-shaped reflecting mirror, wherein a small hole is provided in a central portion of the reflecting mirror, and a folding shape can be taken without causing plastic deformation. The electromagnetic wave focusing apparatus as described. The electromagnetic wave focusing device is an axisymmetric rotating paraboloidal reflector, which uses a plastic material as its material, and is shaped like a thin plate with a metal film on the surface of the thin plate. Is an electromagnetic wave focusing device to which a support structure made of a shape memory material is attached, which maintains a folded state in a low temperature state and has a developed shape in a high temperature state. The container according to any one of claims 1 to 3, wherein the container is stored in a folded state in a small container having a temperature control function, and jumps out of the small container when heated by the temperature control function. The electromagnetic wave focusing apparatus as described. In a low temperature state, the reflector made of a polymer material having a shape memory function has a circular plate shape, and is fixedly stored in the satellite body through a bending / extension support structure made of a material having a shape memory function. In a high temperature state, the bending / extension-type support structure extends to expand the reflecting mirror outside the satellite body, and the reflecting mirror has an axisymmetric rotational paraboloid shape. Electromagnetic focusing device. A method for adjusting the reflectance of the front surface and the emissivity of the back surface of the electromagnetic wave focusing device according to any one of claims 2 to 5 by coating to maintain an appropriate temperature of the electromagnetic wave focusing device. The electromagnetic wave focusing device having a specified shape adopts a polymer material having a shape memory function as its material, and the shape is a thin plate with a metal film applied to the surface of the thin plate. A method for deploying and maintaining the shape of the electromagnetic wave focusing device that keeps the folded state during transportation and heats it in outer space to form a deployed shape.

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