JP6733317B2 - Window lighting equipment - Google Patents

Description

The present invention relates to a window lighting apparatus using a light guide ItaSo location emitted from the emitting surface propagates light incident inside from the end.

There is a phenomenon called total reflection in which incident light does not pass through a boundary surface and is reflected when light enters from a medium having a large refractive index to a medium having a small refractive index. The light guide plate utilizes this total reflection to propagate the light incident from the end of the light guide plate while totally internally reflecting it. The light guide plate device is configured to emit light propagating inside the light guide plate to the outside by providing a portion where light is not totally reflected on the boundary surface of the light guide plate as a light emitting portion. As an illuminating device using such a light guide plate device, for example, in Patent Document 1, a light emitting part is provided that allows light from a light source to enter the inside of the light guide plate from an end of the light guide plate device and emits the incident light to the outside. There is disclosed an illumination module which is arranged on both sides of a light guide plate and emits light from both sides of the light guide plate. This lighting module can also be used as a skylight that takes in outside light.

JP, 2014-107167, A

In the illumination device as described above, when light enters the light guide plate from the outside of the light guide plate, the incident light is transmitted from one surface of the light guide plate to the opposite surface, so that the light enters from the outside to each surface. The transmitted light can be transmitted to the opposite surface side to take in the light in both directions. However, when this lighting device is provided as a window and outside light is taken into the room during the daytime and used as a lighting device at night, only one side of the light guide plate, that is, light is used only indoors, and indoors outdoors. Although it is not necessary to transmit light, the light incident on the light guide plate from the room is transmitted to the opposing outer surface, so that the room light cannot be effectively utilized.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a window lighting device that can efficiently use light on the side that uses light in a room or the like.

The window lighting device according to the present invention has an incident surface on which light from the outside is incident, an emitting surface facing the incident surface, and an end surface on which light from the light source is incident, and the light incident from the end surface is incident on the incident surface. A light guide plate that reflects and guides light between the light emitting surface and a light emitting surface, a bonding surface that is bonded to the light emitting surface of the light guide plate, a light emitting surface that faces the bonding surface, and a side surface that connects the bonding surface and the light emitting surface. a light guide, a light guide plate apparatus provided with a light source, accommodated in the light guide plate unit and a light source, comprising: a housing body having an indoor side and the shop outside opened, and the side surface of the light guide body, the side surface The shape is such that the angle formed by the tangent plane and the joint surface that are in contact with each other is 90 degrees or less.

According to the present invention, the light guide body is provided on the light emitting surface of the light guide plate, and the side surface of the light guide body has a shape in which the angle formed by the tangent plane contacting the side surface and the joint surface is 90 degrees or less. Since the light traveling from the light exit surface side of the light plate device toward the light guide plate is reflected by the light guide body, it is possible to effectively use the room light.

FIG. 4 is an exploded perspective view of a lighting device using the light guide plate device according to the first embodiment. FIG. 3 is an enlarged cross-sectional view in which the vicinity of a point light source of an illumination device using the light guide plate device according to the first embodiment is enlarged. FIG. 3 is a cross-sectional view of a light guide body of the light guide plate device according to the first embodiment. FIG. 3 is a perspective view of a light guide body of the light guide plate device according to the first embodiment. FIG. 3 is an enlarged cross-sectional view showing a light propagation path of a light guide body of the light guide plate device according to the first embodiment. FIG. 5 is an explanatory diagram showing the light transmittance of the light guide plate device according to the first embodiment. It is explanatory drawing which shows the light transmittance of the skylight of a flat plate. It is a conceptual diagram when the light guide plate apparatus which concerns on Embodiment 1 is installed in a window. FIG. 4 is an explanatory diagram of a light distribution of a light guide body of the light guide plate device according to the first embodiment. FIG. 7 is an explanatory diagram of the method for manufacturing the light guide plate device according to the first embodiment. FIG. 6 is a cross-sectional view of a light guide body of the light guide plate device according to the second embodiment. FIG. 9 is an explanatory diagram of a light distribution of a light guide body of the light guide plate device according to the second embodiment. FIG. 9 is an exploded perspective view of a lighting device using the light guide plate device according to the third embodiment. FIG. 3 is a layout view of light guides of the light guide plate device according to the present invention.

Embodiment 1.
Hereinafter, a window lighting device using the light guide plate device according to the first embodiment of the present invention will be described. FIG. 1 is an exploded perspective view of a window lighting device using the light guide plate device 1 according to the first embodiment.
The window illuminating device includes a light guide plate 11 and a plurality of light guides 12 arranged on the light guide plate 11, a light guide plate device 1, point light sources 2, reflectors 31 and 32, a housing body 41, a housing lid. It is composed of 42. The entrance surface 11a of the light guide plate 11 is installed outdoors and the exit surface 11b is installed inside the window frame.
2 is an enlarged cross-sectional view in which the vicinity of the point light source 2 of the window lighting device using the light guide plate device 1 is enlarged.

The light guide plate device 1 includes a light guide plate 11 and a light guide body 12.
The light guide plate 11 is a thin rectangular parallelepiped formed of a resin having a high light-transmitting property. The light guide plate 11 includes an incident surface 11 a on which light from the outside (outdoors) is incident, an emission surface 11 b facing the incident surface 11 a and arranged on the indoor side, and a point light source 2 installed on one of the reflecting plates 31. Has an end face 11c on which the light is incident, and the light incident from the end face 11c is reflected and guided between the incident face 11a and the emission face 11b. The light guide plate 11 is made of a material and a shape in which, when light is incident on the light guide plate 11 through the end face 11c, the light propagates in the light guide plate 11 and the propagated light causes total reflection on the incident face 11a and the emission face 11b. If Total reflection is a phenomenon that occurs when light enters a medium with a large refractive index into a medium with a small refractive index. Therefore, the material of the light guide plate 11 is preferably a material having a high light-transmitting property, which has a large difference in refractive index from the outside of the light guide plate device 1. For example, when used in the air, it is a resin having a larger refractive index than in the air. Methacrylic resin, acrylic resin, polycarbonate resin, vinyl chloride resin, glass and the like can be used. Further, the shape of the light guide plate 11 is not limited to the above-mentioned shape, and may be a shape having a curved surface.

The light guide 12 installed on the emission surface 11b of the light guide plate 11 is made of the same material as the light guide plate 11 and is formed in a truncated cone shape. By using the same material as that of the light guide plate 11, the light guide body 12 can take in light from the light guide plate 11 without substantially reflecting it. Further, the light guide body 12 is formed in the shape of a support and emits light from the upper surface.

The point light source 2 is a light source when it is used as a lighting device, and is composed of, for example, an LED light source. The point light source 2 is provided facing the end surface 11c of the light guide plate 11 so that the illumination light emitted from the point light source 2 enters the light guide plate 11 from the end surface 11c of the light guide plate 11. The point light source 2 may be turned on and off by switching power supply from a power supply device (not shown) to the point light source 2 by a wall switch or remote control switch (not shown), or an adapter with a motion sensor. The module may be configured to be automatically switched by notifying a power supply device (not shown) of instructions for turning on and off.

The reflectors 31 and 32 are mirrors for reflecting the light propagating in the light guide plate 11. By providing the reflectors 31 and 32, the optical loss of the light propagating in the light guide plate 11 is suppressed and the light is guided. This is for effectively utilizing the light emitted from the light body 12.
Note that FIG. 1 illustrates a state in which the reflection plates 31 and 32 are provided on the arrangement surface of the point light source 2 and the surface opposite thereto, but the reflection plates 31 and 32 are arranged so as to cover the end faces orthogonal to these. Although not shown, a reflector is also provided, and the reflector covers all the end faces of the light guide plate 11.

The light guide plate device 1, the point light source 2, and the reflection plates 31 and 32 are housed in a case body 41 and a case lid 42. The housing main body 41 and the housing lid 42 are both cut out in a rectangular shape at the center of the surface so that the entrance surface 11a and the exit surface 11b of the light guide plate 11 are visible from the outside.

Next, details of the light guide 12 will be described. FIG. 3 is a cross-sectional view of the light guide body 12 of the light guide plate device 1 according to the first embodiment. The light guide 12 has a circular joint surface 121 that is joined to the emission surface 11 b of the light guide plate 11, and a circular light emitting surface 122 that faces the joint surface 121. Further, the light guide 12 has a side surface 123 that connects the joining surface 121 and the light emitting surface 122. The side surface 123 of the light guide 12 has an angle between the tangent plane and the joint surface 121 at an arbitrary position of the side surface 123 of 90 degrees or less, and a plurality of angles at which the tangent plane and the joint surface 121 form different angles. The angle formed by the tangent plane and the joint surface 121 in the surface farther from the joint surface 121 among the plurality of surfaces 123a to 123c is closer to the joint surface 121 among the plurality of surfaces. The shape is larger than the angle formed by the tangent plane on one surface and the joint surface 121.
Here, the tangential plane is a plane in contact with the side surface 123 of the light guide 12. For example, a plane that includes a cutting line when each of the surfaces 123a to 123c is cut along the cutting surface of FIG. 2 and is perpendicular to the cutting surface is a tangent plane. When the side surface of the light guide 12 has a shape having a curved line on the cut surface, a plane that includes a tangent line that is in contact with the curved line and is perpendicular to the cut surface is the tangent plane. Although defined by the tangential plane, it can be defined by the side surface 123 of the light guide 12 itself.
More specifically, the light guide 12 has a shape having a joint surface 121, a light emitting surface 122, and a side surface 123 including a first surface 123a, a second surface 123b, and a third surface 123c. The joint surface 121 of the light guide 12 is a circle having a diameter of a. The light emitting surface 122 has the same central axis as the central axis of the joining surface 121, and has a circular shape with a diameter of b. The height of the light guide 12 is c, and the height of each of the first surface 123a, the second surface 123b, and the third surface 123c is a width h in the height direction obtained by dividing the height c into three equal parts. =c/3. Further, the angle formed between the tangent plane that is in contact with each of the surfaces 123a to 123c and the joint surface 121 is 90 degrees or less, and assuming that the angles are α, β, and γ from the side closer to the joint surface 121, the angles increase in this order. Has become.
As shown in FIG. 3, on the side surface 123 of the light guide body 12, the light entering the light guide body 12 from the light guide plate 11 through the joint surface 121 and reflected by the side surface 123 is emitted from the upper part of the light guide body 12. It may be configured so as to be inclined outward with respect to the joint surface 121 so as to be emitted from the surface 122.

4 shows a perspective view of the light guide 12 of the light guide plate device 1 according to the first embodiment on the left side of FIG. 4, and includes the first surface 123a, the second surface 123b, and the third surface included in the side surface 123. 123c is formed by a continuous surface formed by a part of the surface of a cone having different vertex angles. Note that the side surface 123 may be formed by connecting a part of the surfaces of polygonal pyramids having different vertex angles as shown on the right side of FIG. 4, instead of being formed by such a surface.

Next, the operation of the window lighting device using the light guide plate device 1 according to the present embodiment will be described. The window lighting device emits the light of the point light source 2 from the exit surface 11b of the light guide body 12 which is an indoor side by supplying direct current power to the point light source 2 from a power supply device (not shown) and lighting the same. Is. Hereinafter, the propagation path when the light of the point light source 2 is incident from the end surface 11c of the light guide plate 11 will be described.
In FIG. 2, arrows indicate two propagation paths through which the light of the point light source 2 enters and propagates from the end surface 11c of the light guide plate 11 when the point light source 2 is turned on.
Of the light entering the inside of the light guide plate 11 from the end surface 11c of the light guide plate 11, the light that is directed to the exit surface 11b side of the light guide plate 11 is totally reflected on the exit surface 11b and then again on the entrance surface 11a. There is. In this way, the light propagates inside the light guide plate 11 by totally reflecting the incident surface 11a and the emitting surface 11b. At the part of the entrance surface 11a and the exit surface 11b where the light guide 12 is not installed, since the refractive index is largely different from that of air, total reflection can be performed.
On the other hand, of the light entering the inside of the light guide plate 11 from the end surface 11c of the light guide plate 11, the light that is directed toward the entrance surface 11a side of the light guide plate 11 is reflected by the entrance surface 11a. Then, when the light enters the portion where the emission surface 11b of the light guide plate 11 and the joint surface 121 of the light guide 12 are joined, the light is not reflected at that portion but is transmitted and enters the inside of the light guide 12. Since the light guide 12 is made of the same material as the light guide plate 11, the refractive index as seen with air is present at the portion where the exit surface 11b and the joint surface 121 of the light guide 12 are joined. There are no very different boundaries. Therefore, the light goes straight from the emission surface 11b of the light guide plate 11 to the joint surface 121 of the light guide 12 without causing the phenomenon of total reflection. The light that has entered the inside of the light guide body 12 is reflected by the side surface of the light guide body 12 and then emitted from the light emitting surface 122 of the light guide body 12 to the outside.
FIG. 5 is an enlarged cross-sectional view showing the propagation path of light that has entered the light guide body 12 of the light guide plate device 1 according to the first embodiment. In FIG. 5, three arrows show three propagation paths of the light inside the light guide plate 11 that is incident on the portion where the exit surface 11b of the light guide plate 11 and the joint surface 121 of the light guide 12 are joined. Is. As shown in FIG. 5, when the light in the light guide plate 11 enters the light guide 12 from the joint surface 121, the first surface 123a, the second surface 123b, and the first surface 123a are input depending on the incident position and angle. It corresponds to the third surface 123c. At this time, the incident angle of the light incident on the respective surfaces from the bonding surface 121 becomes larger than the critical angle, so that the light is totally reflected. The totally reflected light is incident on the light emitting surface 122, but since the incident angle of the incident light on the light emitting surface 122 is smaller than the critical angle, the light is transmitted without being totally reflected. Therefore, the light of the point light source 2 is emitted from the light emitting surface 122.

As described above, the light of the point light source 2 that is incident from the end surface 11 c of the light guide plate 11 propagates while being totally reflected on the incident surface 11 a and the emission surface 11 b in the light guide plate 11 and guided to the emission surface 11 b of the light guide plate 11. The structure is such that, when the light enters the portion where the joint surface 121 of the optical body 12 is joined, the light enters the inside of the light guide 12 and is emitted from the light emitting surface 122 of the light guide 12. Therefore, the light of the point light source 2 can be emitted only to the emission surface 11b side of the light guide plate device 1.

Further, outdoor light entering the incident surface 11a from outside (outdoor) of the light guide plate device 1 passes through the light guide plate device 1 and is emitted to the room from the emission face 11b. On the other hand, the room light from the side of the emission surface 11b enters the inside of the light guide body 12 through the light emitting surface 122 and the emission surface 11b where the light guide body 12 is not installed, and is taken into the light guide plate 11. The light is totally reflected inside 11, is guided again to the light guide 12, and is emitted from the light emitting surface 122. Therefore, the transmittance from the entrance surface 11a to the exit surface 11b is higher than the transmittance from the exit surface 11b to the entrance surface 11a.

That is, in the window lighting device according to the first embodiment, when the point light source 2 is turned on, the light from the point light source 2 is emitted to the emission surface 11b side. Further, the light that enters the incident surface 11a from the outside of the light guide plate device 1 passes through the light guide plate device 1 and is emitted to the room from the emission surface 11b, while the room light from the emission surface 11b side is partially guided by the light guide 12. The light is reflected inside the light guide 12 and returns to the indoor side. Therefore, it is possible to efficiently use the light on the side that uses light in the room or the like in the room.

Next, a simulation result regarding the light guide plate device 1 according to the first embodiment will be described. In this simulation, as an example of design, PMMA (polymethylmethacrylate resin) having a refractive index of 1.49 and a critical angle of 42.1° is used as a material, and the length and angle shown in FIG. 3 are a=1 and b= 2.5, c=1.7, α=47.5°, β=71.5°, and γ=85.2°.
First, a simulation result of the amount of light emitted from the incident surface 11a and the emission surface 11b when light is incident from the end surface 11c of the light guide plate device 1 will be described. In the light guide plate device 1, when the light source is incident from the end surface 11c, nearly 90% of the light source light amount is emitted from the emission surface 11b and 2.5% is emitted from the incidence surface 11a. The light slightly emitted from the incident surface 11 a is the interface reflected light generated when the light is transmitted through the light emitting surface 122.

Next, a simulation result when external light enters from the incident surface 11a and the exit surface 11b of the light guide plate device 1 will be described. FIG. 6 is a simulation result showing the transmittance from the entrance surface 11a side and the transmittance from the exit surface 11b side of the light guide plate device 1 according to the first embodiment. FIG. 6 shows the transmittance when the light perpendicular to the entrance surface 11a and the exit surface 11b of the light guide plate device 1 is set to 0 degree and light having a predetermined spread is made incident on the light guide plate device 1. The horizontal axis represents the spread angle of light and the vertical axis represents the transmittance.
A light with a divergence angle of 90 degrees is light that is diffused so that the amount of light is the same in any direction within the range of 90 degrees, and light with a divergence angle of 0 degrees is only light that goes in the vertical direction. Is. When light is incident from the incident surface 11a side, as shown by a black circle in FIG. 6, when vertical light having a divergence angle of 0 degree is incident, nearly 90% of the light is transmitted and the divergence angle is expanded to 40°. Even more than 70% of transmitted light is transmitted, and it can be seen that most of the outside light can be taken in. On the other hand, as shown by the white squares in FIG. 6, the transmittance when light is incident from the side of the exit surface 11b is in the range of 50% for light of any divergence angle, and almost half of the light is transmitted. You can see that it is reflected. That is, the light from the room is reflected to the room and can be effectively used.
As a comparative example, FIG. 7 shows the relationship between the transmittance of the skylight of the flat plate and the spread angle. In the case of a flat plate, the same divergence angle dependence of light is exhibited both outdoors and indoors, and indoors and outdoors, and the transmittance is as high as 85 to 90% for any divergence angle of light. On the other hand, in the light guide plate device 1 according to the first embodiment, the transmittance of light from the indoor side, that is, the emission surface 11b side is about 50% for light of almost any divergence angle, and the light from the room is not emitted. It can be seen that it can be effectively used in the room by reflecting it back to the room, that is, the emission surface 11b.

FIG. 8 is a conceptual diagram when the window lighting device according to the first embodiment is installed as a window. The light guide plate device 1 is installed as a window so that the light guide 12 is arranged on the indoor side. In FIG. 8, arrows indicate light from the outside of the light guide plate device 1. Since the light that enters the entrance surface 11a from the outside is mainly straight-ahead sunlight, the angle of incidence on the light guide plate device 1 changes with time. On the other hand, the light in the room that enters the exit surface 11b from the room is considered to be diffused light that has been diffused to some extent.

When this window lighting device is used as a skylight, it is often installed so that sunlight is vertically incident on the skylight in the middle of the south. In this case, as in the above-described simulation result, almost 90% of the light that is incident from the incident surface 11a side, which is outdoors, is incident almost vertically, and therefore, it is possible to capture almost 90% of the sunlight. become. In addition, almost half of the light entering from the exit surface 11b, which is indoors, is reflected to the room at any divergence angle.
Therefore, when the window lighting device according to the present embodiment is used as a skylight, compared with a flat daylighting window, the lighting in the middle of the south has the same performance as the flat daylighting window, and at night, half of the indoor light is emitted. It is possible to keep the brightness of the room bright by reflecting it.

FIG. 9 is a simulation result of the light distribution distribution extracted from the light guide 12 of the light guide plate device 1 according to the first embodiment. FIG. 9 is a light distribution distribution when a light source having a peak of 30000 cd/m ² is used, and the absolute value of the luminance changes depending on the brightness of the light source. It can be seen that the angle at which the luminance drops to about half the luminance of the front is about 40°, which is a surface light source that spreads in the range of 40°.

Next, details of the shape of the light guide 12 of the light guide plate device 1 according to the first embodiment will be described. First, the relationship between the diameter a and the height c of the joint surface 121 of the light guide 12 will be described. The light emitted from the point light source 2 is repeatedly reflected between the incident surface 11a and the emission surface 11b of the light guide plate 11, and a part of the light is incident on the joint surface 121 of the light guide 12 and emitted from the light emitting surface 122. .. In order for light that enters the light guide 12 from the joining surface 121 at an angle larger than the critical angle to exit from the light emitting surface 122 of the light guide 12, it reflects at least once on the side surface of the light guide 12. When it is desired to reduce the thickness of the window lighting device, it is necessary to make the height c of the light guide 12 as low as possible. In order to keep the height c of the light guide 12 as low as possible, the light of the critical angle θc, which is the case where the angle of incidence on the light guide 12 from the joint surface 121 is the largest, is the third surface of the light guide 12. It suffices to hit the highest position of 123c. Therefore, the following equation is derived.

ここで、ｘ１、ｘ２、ｘ３はそれぞれ第一の面１２３ａ、第二の面１２３ｂ、第三の面１２３ｃの図３における横方向の幅である。また、上述したように第一の面１２３ａ、第二の面１２３ｂ、第三の面１２３ｃの高さ方向の幅ｈと導光体１２の高さｃとの関係はｃ＝３ｈであるので、以下の式が成り立つ。

Here, x1, x2, and x3 are the widths of the first surface 123a, the second surface 123b, and the third surface 123c in the horizontal direction in FIG. 3, respectively. Further, as described above, since the relationship between the height c of the light guide 12 and the width h in the height direction of the first surface 123a, the second surface 123b, and the third surface 123c is c=3h, The following formula holds.

これらを式（１）に代入すると、次の式が得られる。

By substituting these into the equation (1), the following equation is obtained.

従って、α、β及びγを前述の角度条件を満たす範囲より選択することにより、ｃ／ａが導かれる。このｃ／ａは、値が小さい方が、透明円錐体形状である導光体１２の成形が容易になるものである。

Therefore, c/a is derived by selecting α, β, and γ from the range satisfying the above-mentioned angle condition. The smaller the value of c/a, the easier the molding of the light guide 12 having a transparent conical shape.

Next, the relationship between the diameter a of the joint surface 121 of the light guide 12 and the diameter b of the light emitting surface 122 will be described. As described above, since the light emitting surface 122 has a shape that reflects the light in the room, the shape of the light guide 12 is a conical shape in which the light emitting surface 122 spreads upward, and the light emitting surface 122 emits light. The surface 122 is designed to have a larger area. Here, the amount of light inside the light guide plate 11 extracted to the light guide 12 is determined by the area where the emission surface 11b of the light guide plate 11 and the joint surface 121 of the light guide 12 are joined. However, the interval at which the light guide 12 is arranged on the emission surface 11b of the light guide plate 11 is determined by the size of the light emitting surface 122. Therefore, even if the arrangement interval of the light guides 12 is narrowed in order to increase the light extraction amount in a predetermined area of the light guide plate 11, the arrangement interval is restricted by the size of the light emitting surface 122 of the light guide 12. Receive. In order to make this constraint as small as possible and widen the selection range of the light extraction amount when determining the arrangement of the light guide 12, the area ratio between the bonding surface 121 and the light emitting surface 122 of the light guide 12 is made small. Is good. If both the bonding surface 121 and the light emitting surface 122 are circular as in the present embodiment, the aperture ratio b/a using each diameter can be used as a value indicating the ratio of each area. By decreasing b/a, the selection range of the light extraction amount when deciding the arrangement of the light guides 12 can be widened. On the other hand, by increasing the aperture ratio by b/a, the number of light guides 12 per unit can be increased. It is possible to increase the reflectance of light that is incident on the emission surface 11b of the light guide plate device 1 from the outside. A proper light guide plate device can be obtained by selecting the aperture ratio b/a according to the usage form.

Next, a method of manufacturing the light guide plate device 1 according to the first embodiment will be described.
For example, the light guide plate 11 and the light guide body 12 of the light guide plate device 1 are integrally formed by high resolution printing using a 3D printer. In mass production, the light guide plate 11 and the light guide body 12 can be manufactured as a structure as shown in FIG. The light guide 12 is integrally formed on the surface of the light guide support plate 13 by injection molding or press molding. In this state, the light emitting surface 122 of the light guide 12 is joined to the light guide support plate 13. By joining this to the separately formed light guide plate 11, a structure having the light guide plate 11 and the light guide 12 can be manufactured. In the case of such a structure, since the light guide 12 is sandwiched between two flat plates, not only the light guide 12 is less likely to be broken, but also the heat insulating effect can be improved. Even when the above-mentioned aperture ratio b/a of the light guide 12 is large, press molding with a glass material is possible, and a material having higher light resistance can be used.

As described above, according to the window lighting device that uses the light guide plate device 1 according to the first embodiment, the light guide body 12 is provided on the emission surface 11b of the light guide plate, and the side surface of the light guide body 12 is in contact with the side surface. Since the angle formed by the tangent plane and the joint surface 121 is 90 degrees or less, the light traveling from the exit surface 11b side of the light guide plate device 1 toward the light guide plate 11 is reflected by the light guide body 12, so that the room light Can be used effectively.
Further, when the point light source 2 is turned on, the light of the point light source 2 that is incident from the end surface 11c of the light guide plate 11 propagates while totally reflecting the incident surface 11a and the emission surface 11b in the light guide plate 11, A structure in which, when the light enters a portion where the joint surface 121 of the light guide body 12 and the emission surface 11b of the light guide plate 11 are joined, the light enters the inside of the light guide body 12 and is emitted from the light emitting surface 122 of the light guide body 12. Therefore, the light from the point light source 2 can be emitted only to the light emitting surface 11b side of the light guide plate device 1.
That is, since the window lighting device according to the present invention takes in external light into the room during the daytime and illuminates only the indoor side at night, and does not transmit the indoor light to the outside, the light can be effectively used. ..

Embodiment 2.
Next, the light guide plate device 1 according to the second embodiment will be described. In the second embodiment, the shape of the side surface of the light guide 12 is different from that of the first embodiment.
Details of the shape of the light guide 12 of the light guide plate device 1 according to the second embodiment will be described. FIG. 11 is a cross-sectional view of the light guide body 12 of the light guide plate device according to the second embodiment. The light guide 12 has a circular joint surface 121 that is joined to the emission surface 11b of the light guide plate 11 and a circular light emitting surface 122 that faces the joint surface 121. Further, the light guide 12 has a side surface 123 that connects the joining surface 121 and the light emitting surface 122. The side surface 123 of the light guide 12 has an angle of 90 degrees or less between the tangent plane and the joint surface 121 at an arbitrary position of the side surface 123, and the tangent plane and the joint surface 121 on the side closer to the joint surface 121. The shape is larger than the angle formed.

In FIG. 11, the side surface 123 has a side surface shape such that light incident from a point O which is one end of the joint surface 121 is totally reflected by the side surface 123 of the light guide body 12.
With reference to the point O, the coordinates (x, y) of the point on the side surface of the light guide in FIG. 11 are extended from the point O, which is the end of the joint surface, to the side surface 123, and this line. It is as follows when expressed using the angle θ formed by the joining surface 121.

この時のｒ及びθに対する位置変位は、次のようになる。

The positional displacement with respect to r and θ at this time is as follows.

点Ｏからの光が側面１２３において全反射するような導光体側面の形状であれば、接合面１２１のどの点から発せられる光に対しても全反射条件が成立することとなる。点Ｏからの光が側面１２３へ臨界角θ_Ｃで入射しているとすると、導光体１２の側面１２３の傾きはπ／２＋θ―θ_Ｃとなり、この傾きがほとんど変化しないとすると、次の式が成り立つ。

If the shape of the side surface of the light guide body is such that the light from the point O is totally reflected on the side surface 123, the total reflection condition is satisfied for the light emitted from any point on the joint surface 121. Assuming that the light from the point O is incident on the side surface 123 at the critical angle θ _C , the inclination of the side surface 123 of the light guide 12 is π/2+θ−θ _C , and assuming that this inclination hardly changes, The formula holds.

よって、式（５）と式（６）より、次の式が得られる。

Therefore, the following equation is obtained from the equations (5) and (6).

上式をΔθ、Δｒの項に分けると、次式のように変形できる。

If the above equation is divided into terms of Δθ and Δr, it can be transformed into the following equation.

この式を加法定理を用いて変形すると、以下のようになる。

When this equation is transformed using the addition theorem, it becomes as follows.

両辺を微分すると以下の式が得られる。

Differentiating both sides gives the following formula.

式（１０）は、接合面１２１の端部である点Ｏから側面１２３に伸ばした線の長さｒとこの線と接合面１２１との成す角度θとの関係を表したものであり、式（１０）を満たせば、導光体１２に入射した光が側面１２３において臨界角で全反射する。特に点Ｏから導光体１２側面への入射角度が、臨界角θcで入射されるような側面形状とすると、接合面１２１の直径ａと光放射面１２２の直径ｂとの比ｂ／ａを小さくできるばかりでなく、導光体１２の高さｃとの比ｃ／ａも小さくすることが可能となる。前者の比が小さくなると導光板装置１の単位長さ当たりの光取り出し効率が向上し、導光板装置１の長さや厚さとの範囲が広くなる。また後者の比が小さくなると、射出成形を用いた成形方法においては、離形性が良くなり、成形精度を向上させることができる。

Expression (10) represents the relationship between the length r of the line extending from the point O, which is the end of the joint surface 121, to the side surface 123 and the angle θ formed by this line and the joint surface 121. When (10) is satisfied, the light incident on the light guide 12 is totally reflected at the critical angle on the side surface 123. In particular, if the side surface is shaped so that the incident angle from the point O to the side surface of the light guide 12 is the critical angle θc, the ratio b/a between the diameter a of the joint surface 121 and the diameter b of the light emitting surface 122 is Not only can it be made smaller, but the ratio c/a to the height c of the light guide 12 can also be made smaller. When the former ratio is small, the light extraction efficiency per unit length of the light guide plate device 1 is improved, and the range of the length and thickness of the light guide plate device 1 is widened. Further, when the latter ratio becomes small, in the molding method using injection molding, the releasability is improved and the molding accuracy can be improved.

In the curved surface in which Const=0.5 and θ _C =42.1° in Expression (10), a=1.65, b=3.08, c=2.13, and b/a=1.9. , C/a=1.3. FIG. 12 shows a simulation result of a light distribution distributed from the light guide 12 of the light guide plate device 1 according to the second embodiment.

Embodiment 3.
Next, the light guide plate device 1 according to the third embodiment will be described. In the first embodiment, one light guide plate device 1 is used as the window lighting device, but in the third embodiment, two light guide plate devices 1 are combined to form the window lighting device.
FIG. 13 is an exploded perspective view of a window lighting device using the light guide plate device 1 according to the third embodiment. Two light guide plate devices 1, point light sources 2, and reflection plates 31 and 32 are housed in the housing body 41 and the housing lid 42.
The light guide plate device 1 is made of a glass resin having a high light-transmitting property, but slightly absorbs light, so that the light is attenuated when it propagates over a long distance. Therefore, in order to maintain high light utilization efficiency of the point light sources 2, it is preferable that the width of the light guide plate 11 orthogonal to the arrangement direction of the point light sources 2 is short, and for that purpose, it is divided into two as shown in FIG. The width can be shortened by dividing the width into several or more.
The width of the light guide plate device 1 orthogonal to the array direction of the point light sources 2 depends on the thickness of the light guide plate 11, and for example, in the case of the light guide plate 11 having a thickness of 2.5 mm, it may be set to 150 to 250 mm. .. When a surface light source exceeding this width is required, it is possible to increase the area by adding the light guide plate device 1, the point light source 2, and the reflection plates 31 and 32.

In any of the above-described embodiments, the light guides 12 are uniformly arranged on the emission surface 11b of the light guide plate 11, and the density thereof is determined as needed. The pattern for arranging the light guides 12 on the emission surface 11b of the light guide plate 11 is not limited to a uniform arrangement, and may be an arrangement according to a desired radiant light distribution. For example, as shown in FIG. It may be an array to be formed. If the light guides 12 are arranged so as to form a pattern or shape as shown in FIG. 14, it is possible to change the light distribution and change the design. The area of the light guide plate 11 where the light guide 12 is not arranged is a non-light emitting area for illumination and a dark-looking area for night illumination. On the other hand, in the daytime, the pattern can be made to appear to be raised due to the incident angle dependency of the light on the transmission characteristic of the outdoor light and the scattering characteristic of the light guide 12.

Further, when the light guides 12 are evenly arranged on one side of the light guide plate 11, the brightness distribution near the point light source 2 of the light guide plate 11 becomes bright and the amount of light is attenuated as it goes downstream. In this case, similar to a light guide plate used for a backlight of liquid crystal, the array interval of the light guides 12 is widened on the upstream side close to the point light source 2 and narrowed on the downstream side so that a uniform light emission amount is obtained as a surface light source. You can

1. Light guide plate device 11. Light guide plate 11a. Incident surface 11b. Emitting surface 12. Light guide 121. Bonding surface 122. Light emitting surface 123. Side 123a. First surface 123b. Second surface 123c. Third side 2. Point light source 31.32. Reflector 41. Case body 42. Case lid

Claims (4)

Incident surface which light from the outside is incident, output surface opposed to the entering elevation surface, and has an end face to which light is incident from the light source, the emission light incident from the front Symbol end surface and the incident surface a light guide plate which light guide is reflected between the surfaces, the bonding surface to be bonded to the exit surface, the light emitting surface as the previous SL bonding surface opposed to the light emitting surface, and pre-Symbol joint surfaces of the front Kishirube light plate light guide and the light guide plate unit having a having a side surface connecting the bets,
The light source,
A housing body that houses the light guide plate device and the light source, and is open on the indoor side and the outdoor side,
Equipped with
The side surface of the light guide is
A window illuminator in which an angle formed by a tangent plane contacting the side surface and the joint surface is 90 degrees or less. The side surface of the light guide is
An angle formed by the tangential plane and the joint surface in a surface farther from the joint surface among the plurality of surfaces, the plurality of surfaces having different angles formed by the tangent plane and the joint surface. 2. The window lighting device according to claim 1, wherein the one of the plurality of surfaces has a shape larger than an angle formed by the tangent plane and the joint surface on a surface closer to the joint surface. The side surface of the light guide is
When the critical angle of the light guide is θ _C ,
The length r of a line extending from the end of the joint surface to the side surface and an angle θ formed by the line and the joint surface satisfy ln(r)=θtan θ _C +Const. 1. The window lighting device according to 1 . The light guide plate is
The light incident from the incident surface is guided to the emission surface facing the incident surface and emitted from the emission surface,
The light incident from the emission surface is guided to the light emission surface of the light guide body and emitted from the emission surface,
The light guide is
Window lighting device according to any one of the three light incident to the bonding surface of the light guide from the exit surface of the light guide plate from claim 1 to be emitted from the light emitting surface.

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