JP2018087899A - Louver film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a louver film with which, when being installed at a light-transmissive window, ghost images as viewing objects, viewed through the light-transmissive window become invisible, that cannot prevent transmission of light entering from a specific direction to the light-transmissive window, and that can prevent the transmission of light entering from parts other than the specific direction to the light-transmissive window.SOLUTION: [1] A louver film 1 including a louver layer 10 in which light transmission bands 11 and light shielding bands 12 are alternately arranged, the louver film 1 is characterized in that a pitch of the light shielding bands 12 is not less than 300 μm and not more than 1100 μm. [2] The louver film as set forth in [1] is characterized in that an aperture ratio represented by {the width of the light transmission band/((the width of the light transmission band)+(the width of the light shielding band))}×100%, is not less than 90% and not more than 99.9%. [3] The louver film as set forth in [1] or [2] is characterized in that the thickness of the louver layer 10 is not less than 350 μm and not more than 3000 μm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a louver film which is applied to, for example, a window of a building, a light transmission window such as an automobile windshield and a head-up display, and prevents a part of light incident on the light transmission window from being transmitted.

  Conventionally, a blind in which metal slats are arranged on the indoor side of a window glass is installed to adjust the amount of light incident from the outside. While there is an advantage that the amount of light can be easily adjusted by adjusting the louver angle of the blind, the thickness of the blind is generally thicker than that of the window glass, which sometimes gives a feeling of pressure to the indoor space. Further, when the light transmission window is curved or inclined, it is difficult to install a conventional blind along the state of the light transmission window.

  Therefore, the present inventor thinks that if a transparent film that can be brought into close contact with the light transmission window has a blind function, it can be applied to a place where it is difficult to install a conventional blind, and is pasted on a conventional liquid crystal display screen. The application of a light emission direction control sheet (for example, see Patent Document 1) used for prevention of viewing was examined.

JP 2006-337837 A

  However, when a conventional light emission direction control film is attached to a light transmission window and an external landscape is viewed from the indoor side, there is a problem that a ghost image in which a plurality of objects to be viewed are overlapped is seen. Further examination by the present inventor has revealed that this phenomenon is not a physiological phenomenon of the observer but a physical phenomenon caused by the function of the light emission direction control film as a diffraction grating.

  The present invention has been made in view of the above circumstances, and when installed on a light transmission window, a ghost image of a visual object viewed through the light transmission window is not visible, and the light transmission window is viewed from a specific direction. Provided is a louver film that does not prevent transmission of incident light and prevents transmission of light incident on a light transmission window from a direction other than the specific direction.

[1] A louver film comprising a louver layer in which light transmission bands and light shielding bands are alternately arranged, wherein the pitch of the light shielding bands is 300 μm or more and 1100 μm or less.
[2] The aperture ratio represented by {width of the light transmission band / (width of the light transmission band + width of the light shielding band)} × 100% is 90% or more and 99.9% or less. The louver film according to [1].
[3] The louver film according to [1] or [2], wherein the louver layer has a thickness of 350 μm or more and 3000 μm or less.

  According to the louver film of the present invention, when installed on the light transmission window, the ghost image of the visual object viewed through the light transmission window is not seen, and the transmission of light incident on the light transmission window from a specific direction is prevented. However, it is possible to suppress transmission of light incident on the light transmission window from other than the specific direction. This allows you to adjust the amount of light incident from the light transmission window, prevent peeping indoors from the outside, and view the display from a display installed at a position away from the light transmission window from a predetermined direction. It can be difficult.

1 is a perspective view showing a first embodiment of the present invention. It is sectional drawing which follows the II-II line | wire in FIG. It is an example of the utilization method of the louver film which concerns on this invention. It is another example of the usage method of the louver film which concerns on this invention.

<First embodiment>
1 and 2 show a first embodiment of the louver film of the present invention, FIG. 1 is a perspective view, and FIG. 2 is a cross-sectional view taken along line II-II in FIG. The drawing schematically shows an enlarged part of the louver film.
The louver film 1 of the present embodiment includes a louver layer 10 in which light transmission bands 11 and light shielding bands 12 are alternately arranged, a first transparent protective layer 13 provided on the entire surface of the louver layer 10, And a second transparent protective layer 14 provided on the entire back surface of the louver layer 10.

  The overall planar shape of the louver film 1 is a rectangle, but the planar shape is not limited to a rectangle, and can be appropriately changed according to the shape of the light transmission window to be applied. Here, the “light transmission window” means a finite two-dimensional region in an arbitrary space through which light can be transmitted. This two-dimensional region may be a flat surface or an arbitrary curved surface. In the two-dimensional region, a physical window base material such as glass or plastic that can transmit light may or may not be installed. When the window base material is not installed, it is preferable that the louver film retains its own shape as a self-supporting film. When the window base material is installed, the window base material can support the shape of the louver film by bringing the louver film into close contact with the window base material.

In this embodiment, the thickness direction of the louver layer 10 is the Z direction, and the direction in which the light transmission band 11 and the light shielding band 12 extend is in the X direction and both the X direction and the Z direction in the plane perpendicular to the Z direction. The vertical direction is the Y direction. The light transmission band 11 and the light shielding band 12 constituting the louver layer 10 are both strips extending in the X direction, and a plurality of light transmission bands 11 and a plurality of light shielding bands 12 are alternately arranged in the Y direction. . The width W1 in the Y direction of the plurality of light transmission bands 11 is uniform and constant in the X direction. The width W2 in the Y direction of the plurality of light shielding bands 12 is also uniform and constant in the X direction.
In the present embodiment, the pitch P of the light shielding band 12 is a total value of the width W1 of the light transmission band 11 and the width W2 of the light shielding band 12 in the Y direction.

  As the material of the light transmission band 11, a resin material that transmits the wavelength of the target visible light is used. The wavelength of light transmitted through the light transmission band 11 may be 380 nm or more and 830 nm or less of the entire visible light range, or may be a part thereof. A resin material having high transparency such that the light transmittance when light is incident only on the light transmission band 11 along the Z direction in the drawing is 75% or more, preferably 85% or more is preferable. Specifically, thermoplastic resins and thermosetting resins having high transparency can be exemplified. For example, cellulose resin, polyolefin resin, polyester resin, silicone resin, polystyrene resin, polyvinyl chloride resin, acrylic resin, polycarbonate Examples thereof include resins. Of these, silicone resins are preferable, and silicone rubber is particularly preferable in terms of heat resistance and transparency.

The value of the "light transmittance" in the present invention, using a D ₆₅ as defined in JIS Z 8720 as a light source, in the apparatus for measuring the intensity of the inspection light emitted from the light source by the light receiving sensor, an optical path of the inspection light A is the output value of the light receiving sensor when there is no object to be measured, and the output value when the measured object is set on the optical path of the inspection light and the transmitted light transmitted through the object is received by the light receiving sensor. Where B is the light transmittance = (B / A) × 100 (unit:%).

As the material of the light-shielding band 12, a colored resin obtained by using the above-described resin as the material of the light-transmitting band 11 as a base material and adding a colorant such as a pigment or a dye thereto is suitably used.
In the louver layer 10, the resin material forming the light transmission band 11 and the resin material as the base material of the light shielding band 12 may be the same or different. From the point of adhesiveness to 12, it is preferable that both are the same.

The color tone of the light-shielding band 12 is not particularly limited as long as a preferable light-shielding property in the light-shielding band 12 can be obtained. The color tone of the shading band 12 can be adjusted by the type and amount of the colorant. Specifically, it is preferable that the light transmittance is 40% or less, preferably 10% or less when light is incident only on the light shielding band 12 along the Y direction in the figure. .
The gloss value on the surface perpendicular to the Y direction of the light shielding band 12 can be evaluated as a value at an incident angle of 60 ° in JIS Z 8741. Usually, the lower the gloss value, the more the light reflection by the light shielding band 12 tends to decrease.
Since the color tone of the light shielding band 12 constitutes the color tone recognized when the louver layer 10 (louver film 1) is viewed, it is preferable to design in consideration of design.

Specific examples of the colorant include general organic pigments or inorganic pigments such as carbon black, bengara, iron oxide, titanium oxide, yellow iron oxide, disazo yellow, and phthalocyanine blue. One colorant may be used, or two or more colorants may be used. When a black pigment is not used, it is preferable to use a white pigment in combination in order to obtain good light shielding properties.
The addition amount of the colorant to be added to the resin base material may be appropriately set in consideration that sufficient light shielding properties cannot be obtained when the amount is small, and that workability is significantly deteriorated when the amount is large.

As shown in FIG. 2, the pitch P of the light shielding band 12 of the louver layer 10 is represented by (width W1 of the light transmission band 11 + width W2 of the light shielding band 12). The pitch P of the light shielding band 12 is not less than 300 μm and not more than 1100 μm, preferably not less than 350 μm and not more than 900 μm, more preferably not less than 400 μm and not more than 750 μm.
The phenomenon which the ghost image of the visual recognition target object mentioned above can be fully prevented as it is more than the lower limit of the said range.
When the amount is not more than the upper limit of the above range, it is easy to adjust the amount of light transmitted through the louver film 1 and to adjust the light transmission angle (viewing angle) θ described later. Usually, as the pitch P becomes narrower, the amount of light transmitted through the louver film 1 decreases and the light transmission angle θ becomes narrower.

  The light transmittance in the Z direction of the louver film 1 is preferably from 50% to 90%, more preferably from 60% to 88%, and even more preferably from 65% to 85%, depending on the application.

  The aperture ratio represented by {width W1 / light transmission band 11 / width W1 + light shielding band 12 width W2) × 100% in the Y direction is a light beam along the Z direction incident on the louver layer 10. Affects the transmittance. From the viewpoint of increasing the transmittance, it is preferable that the width W2 of the light shielding band 12 is small, the width W1 of the light transmission band 11 is large, and the aperture ratio is large. On the other hand, from the viewpoint of reducing the light transmittance of the louver layer 10 and narrowing its light transmission angle, the width W2 of the light shielding band 12 is large, the width W1 of the light transmission band 11 is small, and the aperture ratio is small. Is preferred. From the viewpoint of balancing these viewpoints and further improving the visibility of the visual target through the light transmission window, the aperture ratio is preferably 90% or more and 99.9% or less, and 91% or more and 99% or less. Is more preferably 93% or more and 98% or less.

  In the louver layer 10, from the viewpoint of suppressing the reduction of light transmittance and expanding the light transmission angle θ, the width W1 of the light transmission band 11 in the Y direction is preferably 270 μm or more, more preferably 300 μm or more, and 400 μm or more. Is more preferable. By setting the width W1 of the light transmission band 11 in the above range, a good light transmittance and light transmission angle θ of light in the louver layer 10 can be obtained. For the purpose of reducing the light transmittance so as to function as a blind and narrowing the light transmission angle θ, the upper limit value of the width W1 of the light transmission band 11 can be said to be about 1098 μm, for example.

  In the louver layer 10, from the viewpoint of suppressing the reduction of light transmittance and expanding the light transmission angle θ, the width W2 of the light shielding band 12 in the Y direction is preferably 100 μm or less, more preferably 50 μm or less, and 30 μm. More preferred are: By setting the width W2 of the light-shielding band 12 in the above range, a good light transmittance and light transmission angle θ of light in the louver layer 10 can be obtained. The lower limit value of the width W2 of the light shielding band 12 can be said to be about 1 μm in consideration of manufacturing limitations.

The thickness T of the louver layer 10 in the Z direction is not particularly limited, and is preferably 350 μm or more and 3000 μm or less, for example, from the viewpoint of narrowing the light transmission angle θ while suppressing reduction in light transmittance of the louver layer 10. 400 μm or more and 2000 μm or less is more preferable, and 500 μm or more and 1000 μm or less is more preferable.
If it is at least the lower limit of the above range, the light transmittance can be reduced so as to function as a blind, and the light transmission angle θ can be narrowed.
When it is below the upper limit of the above range, sufficient light transmittance and light transmission angle θ can be obtained. Moreover, the installation in the light transmission window becomes easier.

The light transmission angle θ of the louver film 1 in a plane perpendicular to the X direction (YZ plane, the paper surface in FIG. 2) is, as shown in FIG. 2, the single light transmission band 11 of the louver film 1 from the surface. This is the maximum value of the angle formed by the light rays transmitted through the back surface. The light transmission angle θ is determined by the thickness T of the louver layer 10 and the width W1 of the light transmission band 11 in the Y direction. The light transmission angle θ increases as the thickness T of the louver layer 10 decreases, and the light transmission angle θ increases as the width W1 of the light transmission band 11 increases.
Therefore, it is preferable that the thickness of the louver layer 10 is designed so as to obtain a desired light transmission angle θ in consideration of a preferable range of the pitch P of the light shielding band 12 and the width W2 of the light shielding band 12.
For example, when the pitch P of the light shielding bands 12 is 500 μm and the width W2 of the light shielding bands 12 is 20 μm, if the thickness T of the louver layer 10 is 740 μm, a light transmission angle θ of about 100 ° is obtained.
The lower limit value of the thickness T of the louver layer 10 is set in consideration of a preferable range of the light transmission angle θ.

  If the light transmission angle θ in the louver film is too small, it may be difficult to see the object on the opposite side through the light transmission window. On the other hand, if the light transmission angle θ is too large, it may be difficult to adjust the amount of light incident from the light transmission window or to suppress peeping indoors from the outside. Although the suitable light transmission angle θ may vary depending on the use of the louver film, it is preferably 30 ° or more and 150 ° or less, more preferably 45 ° or more and 140 ° or less, and further preferably 60 ° or more and 120 ° or less.

  The louver layer 10 described above can be manufactured, for example, by the following method. First, a plurality of sheets of the first sheet made of the constituent material of the light transmission band 11 and the thickness W1 and a plurality of sheets of the second sheet made of the constituent material of the light shielding band 12 and the thickness W2 Are alternately laminated, and heated and pressed to form a block body in which the plurality of sheets are integrated. Next, the louver layer 10 is obtained by slicing the block body with a cut surface perpendicular to the surface of each laminated sheet constituting the block body. The thickness (slice width) when slicing is the above T.

As materials for the first transparent protective layer 13 and the second transparent protective layer 14 provided on the front and back surfaces of the louver layer 10, for example, the resins listed above as the material of the light transmission band 11 can be used. The light transmittance when light is transmitted in the thickness direction of each layer (Z direction in the figure) for each of the first transparent protective layer 13 and the second transparent protective layer 14 is 75% or more. Is preferable, and 85% or more is more preferable.
In the louver film 1, the resin material forming each of the first transparent protective layer 13 and the second transparent protective layer 14 and the resin material forming the light transmission band 11 may be the same as each other. Well, each may be different. The materials of the first transparent protective layer 13 and the second transparent protective layer 14 are polycarbonate resin, polyester resin, acrylic resin, polyolefin resin (especially cycloolefin polymer), and cellulose based on transparency and heat resistance. Resins are preferred, and among them, polycarbonate and polyester resins are more preferred.
If the thickness of the first transparent protective layer 13 in the Z direction is too thin, a sufficient protective function cannot be obtained, and the light transmittance decreases as the thickness increases, so that the thickness is preferably about 0.01 to 0.5 mm. About 1 to 0.2 mm is more preferable.
If the thickness of the second transparent protective layer 14 in the Z direction is too thin, the handleability is poor, and a problem arises in workability at the time of manufacturing the louver film 1. Moreover, since light transmittance falls, so that it is thick, about 0.01-0.5 mm is preferable and about 0.1-0.2 mm is more preferable.

The method of providing the first transparent protective layer 13 and the second transparent protective layer 14 on the front and back surfaces of the louver layer 10 is not particularly limited, and a known method can be used as appropriate.
For example, a method may be used in which an adhesive is applied to the surface of the louver layer 10, a sheet made of the material of the first transparent protective layer 13 is bonded, and then the adhesive is cured. Similarly, the second transparent protective layer 14 can be bonded and integrated with the back surface of the louver layer 10.

The adhesive preferably has a high light transmittance after curing. Specifically, it is preferable that the light transmittance in the simple substance of the adhesive layer after curing is 65% or more, and more preferably 80% or more. Examples of the adhesive include thermosetting adhesives, multi-component reaction adhesives, and ultraviolet curable adhesives that have transparency after curing. Specifically, for example, epoxy adhesives, urethane adhesives, acrylic adhesives, melamine adhesives, polyester adhesives, silicone adhesives, and the like can be suitably used.
The louver film 1 is obtained by the method described above.

<Effect>
According to the louver film 1 of the present embodiment, for example, by installing it in a light transmissive window such as a building window, a windshield of a car, or a head-up display, the light transmissive angle out of the light incident on the light transmissive window. Only light having a specific incident angle within the range of θ can be transmitted. For example, as shown in FIG. 3, when the trees 3 that are objects to be viewed outdoors are viewed through the window glass of the building 2 to which the louver film 1 is attached, a vector connecting the indoor observer A and the trees 3. This direction is along the thickness direction (Z direction in FIG. 2) of the light transmission band 11 and the light shielding band 12 constituting the louver layer 10 of the louver film 1. That is, the vector of light rays from the trees 3 toward the viewer A is within the range of the light transmission angle θ of the louver film 1. For this reason, the observer A can visually recognize the trees 3 easily. At this time, since the pitch P of the louver layer is set to 300 μm or more, a ghost image of the trees 3 is not observed. On the other hand, since the angle of the vector connecting the passerby B who is outdoors and the observer A in the room is outside the range of the light transmission angle θ of the louver film 1, it is difficult for the passerby B to visually recognize the observer A. It has become. Similarly, the angle of the vector connecting the sun S and the louver film 1 is outside the range of the light transmission angle θ of the louver film 1, so that direct sunlight from the sun S is difficult to enter the room.

<Modification 1>
As a modification of the above embodiment, although not shown, an adhesive layer may be provided as the outermost layer on the opposite side of the first transparent protective layer 13. For example, an adhesive layer can be provided on the entire back surface of the louver layer 10 without providing the second transparent protective layer 14. Moreover, the structure which laminated | stacked the adhesion layer on the 2nd transparent protective layer 14 can also be illustrated.
As the material of the pressure-sensitive adhesive layer, a material having high transparency is preferable, and may have a pressure-sensitive adhesive strength that can be peeled off from a window substrate such as a window glass. You may do. A commercial item is applied as an adhesive which can form such an adhesion layer, for example, an acrylic adhesive, a urethane adhesive, a rubber adhesive, etc. are mentioned. Specific examples of the elastomer include silicone rubber, silicone gel, urethane rubber, and urethane gel. Among these, silicone rubber is particularly preferable from the viewpoint of little adhesive residue after peeling and high transparency. The formed adhesive layer may be mirror-finished.
According to the above-described modification, since the louver film can be attached to the surface of the window base material, compared to the configuration in which an air layer is interposed between the louver film and the window base material, the loss of transmitted light Becomes smaller.

<Modification 2>
In the above embodiment, the direction of the light shielding band 12 in the cross section of FIG. 2 (the longitudinal direction of the long side of the light shielding band 12 in the cross section) is parallel to the thickness direction (Z direction) of the louver film 1. The direction of 12 may be inclined with respect to the Z direction. For example, as shown in FIG. 4, the direction of the light shielding band 12 of the louver film 1 installed on the window glass on the second floor of the building 2 is such that the indoor observer A looks down on the ground. The structure which inclined the said direction with respect to Z direction (thickness direction of a window glass) is mentioned. According to this configuration, it is easy for the observer A in the room to observe the visual object 3 on the ground, and direct sunlight from the sun S in the direction in which the observer A looks up can be suppressed. .

[Example 1]
A louver film 1 having the structure shown in FIGS.
First, a first sheet having a thickness of 480 μm made of transparent silicone rubber (trade name: KE153U, manufactured by Shin-Etsu Chemical Co., Ltd.) was prepared as the light transmission band 11.
Separately, a second sheet having a thickness of 20 μm made of a black material obtained by adding carbon black to transparent silicone rubber (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KE153U) was prepared as the light shielding band 12.
Next, after laminating a plurality of first sheets and a plurality of second sheets alternately, heat vulcanization and pressurization were performed to form a block body in which these sheets were integrated. The louver layer 10 was produced by slicing the block body to a thickness of 740 μm with a cut surface perpendicular to the sheet surface.
Subsequently, a polycarbonate sheet (first and second transparent protective layers 13, 100 μm) obtained by applying a thermosetting adhesive (trade name: KE1825, manufactured by Shin-Etsu Chemical Co., Ltd.) to both surfaces of the obtained louver layer 10. The louver film 1 was produced by bonding and thermosetting 14).

In the louver film 1 produced in this example, the pitch P of the light shielding band 12 is 500 μm, the width of the light shielding band 12 is 20 μm, and the thickness of the louver layer 10 is 740 μm.
With respect to the louver film 1 of this embodiment, while changing the measurement angle, that is, while changing the angle between the Z direction and the optical axis from the light source to the light receiver in the YZ plane of FIGS. The rate was measured. As a result, the light transmission angle θ of the louver film 1 of this example was 100 °, and the light transmittance in the Z direction was 80%. The light transmittance of light incident from an angle exceeding the light transmission angle θ was less than 5%.

Holding the louver film 1 of this example in the hand and holding the louver film in the direction of the line of sight with the arms extended, the following visual objects were observed through the louver film 1.
When viewing the horizontal red lines displayed on the outdoor buildings, outdoor signals, ceiling fluorescent lights, and PC liquid crystal screens as sighted objects, the ghost image is not seen and the sight is well visible. I was able to. At the time of observation, the light transmittance in the range exceeding the light transmission angle θ was low, and it was confirmed that the function as a blind was sufficiently exhibited.

[Comparative Example 1]
A louver film was produced in the same manner as in Example 1 except that the thickness of the first sheet in Example 1 was changed to 130 μm to form a louver layer. In the louver film of this comparative example, the pitch P of the light shielding band 12 is 150 μm, the width of the light shielding band is 20 μm, and the thickness of the louver layer is 200 μm. The light transmission angle θ of this louver film was about 100 °.
The same observation experiment as in Example 1 was performed using the louver film of the comparative example. The outline of the outdoor building group, the outdoor signal, the fluorescent lamp on the ceiling, and the horizontal red displayed on the liquid crystal screen of the PC. For both lines, a ghost image that appears double or triple blurred was generated.

  The louver film of the present invention can be widely used for building windows, automobile windshields, head-up displays, and the like.

1 louver film 10 louver layer 11 light transmission band 12 light shielding band

Claims (3)

  A louver film comprising a louver layer in which light transmission bands and light shielding bands are alternately arranged, wherein the pitch of the light shielding bands is 300 μm or more and 1100 μm or less.   The aperture ratio represented by {width of the light transmission band / (width of the light transmission band + width of the light shielding band)} × 100% is 90% or more and 99.9% or less. The louver film according to 1.   The louver film according to claim 1 or 2, wherein the louver layer has a thickness of 350 µm or more and 3000 µm or less.

Images