Patent Grant
7828018
The present invention relates to a light diffusing yarn and a surface-form structure, in particular, a light diffusing yarn and a surface-form structure that are superior in light diffusion characteristics.
As shown in
Further, Patent Documents 1 through 3, based on patent applications filed by the present applicant, disclose a light distribution control device using a “structure having a number of ridges arranged parallel to and sufficiently close to each other, wherein the section taken in a direction orthogonal to the longitudinal direction of each of the ridges substantially constitutes a part of a circle, and wherein the surfaces of the ridges are substantially mirror surfaces.” Further, Patent Document 3 discloses the provision of a “light diffusion characteristic” in which “light incident on a row of such ridges is diffused in a conical-surface-like fashion in the case of a light transmitting body and in a semi-conical-surface-like fashion in the case of a light reflecting body around a line passing the incident point and parallel to the ridges, with the diffused light density distribution tending to become uniform as the ridge width decreases”.
Further, Patent Documents 1 and 2 disclose a transparent body including a fabric into which a large number of mono filaments are woven.
Patent Document 1: JP 2000-17760 A
Patent Document 2: JP 2002-81275 A
Patent Document 3: JP 2006-73366 A
Both the mono filaments and the ridges used in the above-mentioned curtain material and the cloth disclosed in Patent Documents 1 and 2 are linearly extended, and hence the distribution of incident sunlight in the room greatly depends on the position of the sun at a given point in time, with the light distribution in the room greatly varying with the daily movement of the position of the sun.
Further, the above-mentioned curtain material and the cloth disclosed in Patent Documents 1 and 2 use the above-mentioned strips or bundles of mono filaments as the warps and wefts, with each weft alternately passing the front and back sides of the warps warp by warp, and each warp alternately passing the front and back sides of the wefts weft by weft. In this mode of weaving, the interval between the adjacent warps and the interval between the adjacent wefts are rather large, with clearances being easily formed at the weaving meshes.
Thus, when a fabric woven in this manner is used as the curtain to introduce light, the amount of direct sunlight entering the room through the clearances at the weaving meshes is rather large, resulting in a dazzling sunbeam being introduced into the room.
The present invention has been made with a view toward solving the above problem in the prior art. It is an object of the present invention to provide a surface-form structure capable of realizing uniform light distribution even if the incident angle varies.
Another object of the present invention is to provide a light diffusing yarn applicable to such a surface-form structure.
Still another object of the present invention is to provide a surface-form structure capable of reducing glare while effecting light distribution.
The present light diffusing yarn having a predetermined diameter or width and exhibiting light transmission property or light reflection property, wherein the light diffusing yarn has on its surface a plurality of ridges arranged substantially in parallel and close to each other, wherein each ridge has a cross section constituting at least a part of a circle and has a surface substantially including a mirror surface, and wherein twisting is imparted to the light diffusing yarn at a frequency of more than one time in a length of five times as long as the predetermined diameter or width.
In this case, the expression: “substantially including a mirror surface” can be defined as follows.
As is known, incident light on a predetermined structure surface whose surface asperity is sufficiently smaller than the wavelength of light undergoes mirror reflection, whereas it undergoes diffused reflection when the surface asperity is substantially equal to or larger than the wavelength of light. A surface causing mirror reflection is generally referred to as a “mirror surface”.
In the case in which most of a surface of an object is formed by a “mirror surface” or “mirror surfaces” dispersed substantially uniformly, a surface is defined as a “substantial mirror surface” when the ratio of the total area of the mirror surface portions with respect to the area of a predetermined surface (referred to as mirror surface ratio) is to be regarded within a reasonable range for the intended use of the surface. For example, from the viewpoint of the function required thereof, a mirror must cause the major portion of incident light to undergo mirror surface reflection. In this case, the mirror surface ratio will be 0.9 or more.
The ridges may be formed by mono filaments exhibiting light transmission property or light reflection property and having a substantially circular cross section.
A plurality of mono filaments may form a flat yarn arranged in a single layer or a plurality of layers and in parallel and fixed to each other, and the flat yarn may be twisted. Furthermore, a plurality of flat yarns may be twisted together.
Also, a plurality of mono filaments may be twisted together in a bundled state or knitted together.
In a first surface-form structure according to the present invention, the above-mentioned light diffusing yarns are woven or knitted thereinto as at least one of the warps and the wefts.
In a second surface-form structure according to the present invention, the above-mentioned light diffusing yarns are sewn, woven, or embroidered into a surface-form support member.
In a third surface-form structure according to the present invention, a large number of light diffusing yarns as described above are held substantially in parallel and close to each other. In this case, the large number of light diffusing yarns may be arranged on and fixed to a surface-form support member.
The present fourth surface-form structure is a surface-form structure into which yarns with light diffusion property having on their surfaces a plurality of ridges each of which has a cross section constituting at least a part of a circle and has a surface including a substantially mirror surface and which are arranged substantially in parallel and close to each other, are woven or knitted as at least one of warps and wefts, wherein each warp alternately passes the front and back sides of the wefts for each set of a plurality of wefts, and wherein each weft alternately passes the front and back sides of the warps for each set of a plurality of warps. The phase in which each weft alternately passes the front and back sides of the warps may be shifted by a predetermined number of warps for each set of adjacent wefts, or the phase in which each warp alternately passes the front and back sides of the wefts may be shifted by a predetermined number of wefts for each set of adjacent warps. In this case, the ridges of the yarns with light diffusion property may be formed by light transmitting or light reflecting mono filaments with a substantially circular cross section. A plurality of mono filaments may form flat yarns by arranging them in a single layer or a plurality of layers and in parallel and fixed to each other, or yarns twisting such arrangement of mono filaments may be used. The roles of wrap and weft may be changed. As a yarn with light diffusion property, a light diffusing yarn may be used.
The first to fourth surface-form structure may exhibit a cloth-like flexibility or a plate-like rigidity.
According to the present invention, it is possible to provide a light diffusing yarn superior in light diffusion characteristics, and by using this light diffusing yarn, it is possible to provide a surface-form structure capable of realizing uniform light distribution even if the incident angle varies.
Further, the yarns with light diffusion property are woven in or knitted in as at least one of the warps and the wefts such that each warp alternately passes the front and back sides of the wefts for each set of a plurality of wefts and that each weft alternately passes the front and back sides of the warps for each set of a plurality of warps, whereby the clearances at the weaving meshes or the knitting meshes are reduced, making it possible to reduce glare while effecting light distribution.
In the following, embodiments of the present invention are described with reference to the accompanying drawings.
The present inventor test-produced light diffusion structures with ridges by using optical fibers and round bars of various diameters to examine the light distribution of diffused light, from which it was discovered that when the curved edges of the section a large number of ridges arranged in parallel and sufficiently close to each other are arcs, and the surfaces of the ridges substantially include mirror surfaces, light A impinging on a certain point i on the surface of the structure, in both reflection and transmission, is diffused in the form of a conical surface whose apex is i due to the diffraction effect of the row of the above-mentioned ridges, and that, of this diffused light beam, the diffused reflection light beam expands in the form of a longitudinal half of the conical surface, with the diffused transmission light beam expanding in the form of the remaining longitudinal half of the conical surface.
Such a conical-surface-like diffusion further exhibits the following characteristics. First, as shown in
The light A advances in the plane P and impinges on the plane S at the point i. Assuming that the plane S is a mirror surface, the reflected light and the transmitted light cross the plane T at points a and a′, respectively, and the respective halves of the circle whose radius is the segment Oa, Oa′ connecting the points a and a′ with the origin O, are the sections of the diffused reflection light beam and the diffused transmission light beam of the light A taken along the plane T. In this case, as in the case of incident light B on the plane S of the structure, as the acute angle β, at which it crosses the XY-plane passing the incident point i, parallel to the ridges U, and orthogonal to the plane S, increases, the expansion of the diffused light beam increases.
Further, assuming that the plane S is a flat mirror surface, the luminance of the diffused light beam in the diffusing direction is maximum in the directions of the reflected light and the transmitted light. Further, as the maximum value directions are departed from, the luminance is reduced in a certain uniform relationship with the angle with respect to the maximum value directions. This luminance distribution in the diffusing direction of the diffused light beam (hereinafter referred to as the diffused light beam luminance distribution) can be turned into a more uniform distribution through appropriate selection of the angle of circumference and maximum diameter of the ridge sections and the proximity degree between the ridges.
As an example of such appropriate selection, the angle of circumference of the ridge sections and the interval between the ridges were varied in different ridges whose respective radiuses were 1 mm, 0.5 mm, and 0.125 mm, and the permissible range in terms of the performance of a light distribution control device in the application fields for the present invention described below was evaluated by a total of three persons: an engineer H1; a market developer H2; and a staff member H3 to be in charge of sales. The evaluation results are shown in Table 1. The evaluation was made in three levels: 1: applicable; 2: applicable depending on the use; and 3: difficult to apply.
The surface of each mono filament 2 substantially includes a mirror surface, and the four mono filaments 2 form the ridges of the present invention. The mono filaments 2 can be formed of thermoplastic polymer or the like.
This twisting is imparted continuously over the entire length of the light diffusing yarn 1. The twisting cyclically reverses the front and back surfaces of the flat yarn 3 along the longitudinal direction of the light diffusing yarn 1. More specifically, the twisting reverses the front and back surfaces approximately one time in a length of four times as long as the width W of the flat yarn 3, with the longitudinal-axis direction of each mono filament 2 being continuously changed along the longitudinal direction of the light diffusing yarn 1. Thus, the direction of the center axis of the conical-surface-like diffused light due to each mono filament 2 described with reference to
As the degree of twisting imparted to the flat yarn 3 is enhanced, the longitudinal-axis direction of each mono filament 2 is more greatly changed along the longitudinal direction of the light diffusing yarn 1, and hence the diffused light is emitted over a wider range.
For example, when approximately one twist is imparted in a length of double the width W of the flat yarn 3, the directions of the mono filaments 2 at both ends in the width direction of the flat yarn 3 are substantially orthogonal to each other, and the light entering the light diffusing yarn 1 is diffused in substantially all the directions at one cycle of twisting.
The number of mono filaments 2 is not restricted to four, and the flat yarn 3 may be formed by arranging a plurality of mono filaments 2 in parallel. Further, instead of arranging a plurality of monofilaments 2 in a single layer, it is also possible, as shown in
Also in the light diffusing yarn 11, the longitudinal-axis direction of each mono filament 2 changes continuously and cyclically along the longitudinal direction of the light diffusing yarn 11, and the same effect as that of the light diffusing yarn 1 of Embodiment 1 is obtained.
The flat yarn 12 is not restricted to the construction in which two mono filaments 2 are arranged side by side. As shown in
Also in the light diffusing yarn 21, the longitudinal-axis direction of each mono filament 2 changes continuously and cyclically along the longitudinal direction of the light diffusing yarn 21, and the same effect as that of the light diffusing yarns 1 and 11 of Embodiments 1 and 2 is obtained.
It is also possible to bundle and twist together a plurality of flat yarns in each of which a plurality of single yarns 2 are arranged in parallel.
Through this braiding, twisting is imparted to each mono filament 2 at a frequency of more than one time in a length of five times as long as the diameter or width of the light diffusing yarn 31. When the light diffusing yarn 31 is bent or warped, there is scarcely any change in the relative positions of the three flat yarns 3. Further, by tightening the braiding, it is possible to maintain a satisfactory degree of proximity between the flat yarns 3.
Due to the braiding, the flat surface of each flat yarn 3 meanders along the longitudinal direction of the light diffusing yarn 31. When light enters the light diffusing yarn 31, the center axis of the conical-surface-like transmission diffusion is parallel to the tangential direction of the mono filaments 2 at the light incident portion, and hence the diffused light expands over a wide range.
When a laser beam was applied to the light diffusing yarn 31 by using a laser pointer, the diffused light expanded over a range of approximately 45 degrees.
It is also possible to form a light diffusing yarn 41 as shown in
The number of flat yarns braided together is not restricted to three. It is also possible to braid together two or four or more flat yarns.
Further, it is also possible to form a light diffusing yarn by braiding together, instead of flat yarns, a plurality of mono filaments 2.
As shown in
The flat yarn 5 can be produced by spinning out polyethylene terephthalate at a temperature, for example, of 300° C. from a mouth piece with a nozzle opening of the same configuration as the sectional configuration of the flat yarn 5 and expanding the same. It is also possible for the polyethylene terephthalate to contain approximately 3.5% by weight or less of delusterant.
It is possible to form a light diffusing yarn by using the flat yarn 5 instead of the flat yarn 3 of Embodiment 1, the flat yarn 12 of Embodiment 2, the mono filaments 2 of Embodiment 3, and the flat yarn 3 of Embodiment 4.
When applying the flat yarn 5 to Embodiment 1, it is also possible to impart twisting to the flat yarn 5 immediately after spinning it out of the mouth piece, curing it as it is through cooling.
It is possible to form a surface-form structure such as woven cloth or knitted cloth having light diffusing characteristics by weaving in or knitting in one of the light diffusing yarns 1, 11, 21, 31, and 41 of Embodiments 1 through 5 as at least one of warps and wefts.
There are no limitations regarding the weaving or knitting method.
In this regard, it is possible to use one of the light diffusing yarns 1, 11, 21, 31, and 41 as both warps and wefts, or to use two of the light diffusing yarns 1, 11, 21, 31, and 41 as warps and wefts, respectively. Further, it is possible to use any one of the light diffusing yarns 1, 11, 21, 31, and 41 as solely one of warps and wefts, using some other yarn than the light diffusing yarns 1, 11, 21, 31, and 41 (including yarns of the type having no light diffusion property) as the other.
In such a surface-form structure, the light diffusing yarns 1, 11, 21, 31, and 41 used as at least one of warps and wefts generate diffused light over a wide range, and hence, by applying sunlight to this surface-form structure, it is possible to effect uniform light distribution in the room without greatly depending on the position of the sun at a given point in time, that is, independently of the movement of the position of the sun.
It is possible to form a surface-form structure with light diffusion property by sewing, knitting, or embroidering any one of the light diffusing yarns 1, 11, 21, 31, and 41 of Embodiments 1 through 5 into a film-like or plate-like transparent surface-form support member or into a net-like surface-form support member.
Also in this surface-form structure, the light diffusing yarns 1, 11, 21, 31, and 41 generate diffused light over a wide range, and hence, as in Embodiment 6, it is possible to effect uniform light distribution in the room.
Also in this surface-form structure, the light diffusing yarns 1, 11, 21, 31, and 41 arranged and fixed generate diffused light over a wide range, and hence, as in Embodiments 6 and 7, it is possible to effect uniform light distribution in the room.
It is also possible for a large number of light diffusing yarns 1, 11, 21, 31, and 41 to be arranged and held between a pair of transparent surface-form support members 6.
That is, as shown in
In this regard, the phase in which each weft passes the front and back sides of the warps may be shifted in a fixed direction by a predetermined plurality of warps for each set of adjacent wefts.
Due to this method of weaving, in which the phase in which each weft passes the front and back sides of the warps is shifted in a fixed direction by one or a predetermined plurality of warps for each set of adjacent wefts, sets of adjacent two warps arranged in parallel close to each other and sets of adjacent two wefts arranged in parallel close to each other, are formed at many positions. That is, the degree of proximity between the adjacent yarns increases, and the region (area) where the adjacent yarns are close to each other increases in the surface-form structure as a whole.
For example, as shown in
In contrast, in the method of weaving in which, as in Embodiment 9, the phase in which each weft passes the front and back sides of the warps is shifted for each set of adjacent wefts, the horizontal interval between the warps D and E is small as shown in
In particular, in the case in which there are used flat yarns formed by mono filaments arranged side by side or formed of a highly elastic material with a row of ridges and in which they exhibit elasticity with respect to the “tightness” or “pressure” of the weaving, the portions other than the weaving meshes swell starting from the yarns, and the degree of proximity of the adjacent yarns and the area of the proximity regions increase further. This leads to an increase in the light diffraction grating effect as described with reference to
Further, as described above, in the surface-form structure of Embodiment 9, sets of two adjacent warps arranged in parallel close to each other and sets of two adjacent wefts arranged in parallel close to each other, are formed at many positions, and hence the clearances of the weaving meshes are reduced as compared with the ordinary interlacing weave. Thus, when light is introduced by using this surface-form structure, the amount of direct sunlight entering the room directly through the mesh clearances is reduced, making it possible to effect light distribution in the room while reducing glare.
While in
Further, instead of the flat yarns 3 each including four mono filaments 2, it is also possible to use flat yarns 12 each including two mono filaments 2, or flat yarns each including some other number of mono filaments 2 arranged side by side. Further, it is also possible to weave in any one of the light diffusing yarns 1, 11, 21, 31, and 41 of Embodiments 1 through 5 described above as at least one of the warps and the wefts.
Further, it is also possible to form a woven cloth by weaving in such yarns with light diffusion property as at least one of the warps and the wefts as shown in
While in the surface-form structures shown in
The surface-form structures of Embodiments 6 through 9 described above may also be formed so as to exhibit a cloth-like flexibility or a plate-like rigidity as a whole. It is possible to select between flexibility and rigidity according to the use of the surface-form structure.
While in Embodiments 1 through 9 described above there are used the mono filaments 2, and the flat yarns 3, 4, 5, and 12 having light transmission property are used, if the mono filaments and the flat yarns are formed of a light reflecting material, it is possible to obtain the same effects as those of Embodiments 1 through 9 except that the “conical-surface-like diffusion” is changed to a “semi-conical-surface-like diffusion”. In this case, instead of the transparent surface-form support member 6 used in Embodiment 8, it is also possible to use an opaque surface-form support member.
The surface-form structures of Embodiments 6 through 9 described above are applicable to various fields of light energy utilization, such as a lighting device, a partition, a tent cloth, the roof or wall surface of a greenhouse, illuminator, and a backlight diffusion member.
After various experiments, it was found out that, when there were produced light diffusing yarns whose ridge radius was r, whose ridge-peripheral-edge angle of circumference was θ, and whose inter-ridge interval was d and which satisfy the following conditions, it is possible to obtain a degree of diffusion effect (diffraction grating effect) allowing application to various purposes by surface-form structures produced by using the light diffusing yarns.
r≦0.0625mm
θ≧160 degrees
d≦5μm
When the mono filaments 2 are used as the ridges, the diameter D of the mono filaments 2 is in the following range:
D≦0.125mm
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-131517 | May 2006 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2007/059319 | 5/1/2007 | WO | 00 | 11/10/2008 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2007/129644 | 11/15/2007 | WO | A |
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