JP2014186794A - Illumination cover, and illumination device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination cover and an illumination device in which cleaning is easy, manufacturing cost is low and efficiency is high.SOLUTION: An illumination device includes: a light source 3; and an illumination cover 2 arranged facing the light source and becoming a light emitting surface. The illumination cover has: an inner surface 2a facing the light source; an outer surface 2b facing outside; and a plurality of prisms 10 formed on the outer surface. The prism has at least one inclined surface which inclines with respect to the inner surface, the angle of inclination of the inclined surface of the prism is at least 12 to 42 degrees on average, and when an angle formed with a normal line direction of the illumination cover 2 is defined as θ, the ratio of light intensity in the direction of θ=60-90 degrees with respect to the light intensity in the direction of θ=0 degree is equal to or less than 20%.

Description

  Embodiments described herein relate generally to a lighting cover and a lighting device using the same.

  The lighting device illuminates the living space with appropriate illuminance so that humans can work comfortably, but it is necessary to prevent the lighting device itself from being dazzling.

  Such a dazzling phenomenon is hereinafter referred to as glare. The definition and recommended environment of glare are defined in JIS, Z9110-2010, JCIE-002 indoor workplace lighting standard design guide, Japan Lighting Equipment Manufacturers Association UGR guide guide 131 and the like.

  In order to prevent this glare, it is necessary to reduce the luminance of the illumination device when viewed from an oblique direction that is easy to enter the visual field. Specifically, it is necessary to lower the luminance within a range of 60 to 90 degrees with respect to the normal direction of the ceiling, and this angle range is out of the range of the floor or desk that the lighting device should originally irradiate, as described above. By easily entering the horizontal field of view. Therefore, it is necessary to reduce the luminance of the lighting device when viewed from the range of 60 to 90 degrees, while maintaining the illuminance in the direction directly below the lighting device by some means.

  As a general prior art, there is a technique in which a plurality of reflectors parallel to the ceiling normal direction, for example, reflectors called louvers, baffles, and galleys are arranged on the light emitting opening side of the lighting device. This is because a plurality of reflectors are arranged in parallel with the normal direction of the ceiling so that light in the direction directly below the lighting device is not shielded, but when viewed from an angle, the light source is shielded by the plate plate of the reflector, In the range of the above-mentioned angle of 60 to 90 degrees, the light source is completely shielded by the plurality of reflecting plates.

Japanese Patent Laid-Open No. 04-87204

  However, since the shape of such a reflector is complicated, it takes time for cleaning and the manufacturing cost is high. Furthermore, light absorption by the reflector causes a reduction in the efficiency of the lighting device.

  The present invention has been made in view of the above points, and an object thereof is to provide a lighting cover and a lighting device that are easy to clean, low in manufacturing cost, and high in efficiency.

  According to the embodiment, the illumination cover of the illumination device includes an inner surface facing the light source, an outer surface facing outward, and a plurality of prisms formed on the outer surface. The prism has at least one inclined surface inclined with respect to the inner surface, and the inclination angle of the inclined surface of the prism is at least 12 to 42 degrees on average, and an angle formed with the normal direction of the inner surface is θ. In this case, the ratio of the luminous intensity in the direction of θ = 60 to 90 degrees to the luminous intensity in the direction of θ = 0 degrees is 20% or less.

FIG. 1 is a diagram illustrating a lighting device according to the first embodiment and a use environment thereof. FIG. 2 is a perspective view showing the lighting device. FIG. 3 is a longitudinal sectional view of the lighting device. FIG. 3 is a cross-sectional view of the lighting device. FIG. 5 is a view showing a light distribution in the longitudinal direction of the illumination device. FIG. 6 is a diagram illustrating a function of a lighting cover of the lighting device. FIG. 7 is a diagram illustrating the function of the lighting cover. FIG. 8 is a diagram illustrating an optimum range of the lighting cover. FIG. 9 is a diagram illustrating an optimum range of the lighting cover. FIG. 10 is a diagram illustrating an optimum range of the lighting cover. FIG. 11 is a diagram illustrating an optimum range of the lighting cover. FIG. 12 is a diagram showing the relationship between the ratio of the area of the outer surface of the illumination cover and the area of the prism region where the prism is formed, the luminous intensity ratio, and the efficiency. FIG. 13 is a perspective view schematically showing a lighting cover of a lighting device according to a first modification. FIG. 14 is a perspective view schematically showing a lighting cover of a lighting device according to a second modification. FIG. 15 is a perspective view schematically showing a lighting cover of a lighting device according to a third modification. FIG. 16 is a perspective view schematically showing a lighting cover of a lighting device according to a fourth modification. FIG. 17 is a perspective view schematically showing a lighting cover of a lighting device according to a fifth modification. FIG. 18 is a perspective view schematically showing a lighting cover of a lighting device according to a sixth modification.

  Hereinafter, the illumination device according to the embodiment will be described in detail with reference to the drawings.

  In addition, although embodiment is an illuminating device, generally the illumination cover for the purpose of light-shielding may be sold as an accessory component separately from an illuminating device. The subject of the present invention includes a lighting cover alone, but in the embodiment, only a lighting device incorporating the lighting cover will be described.

(First embodiment)
FIG. 1 is a diagram schematically illustrating a lighting device and a use environment thereof according to the first embodiment, and FIGS. 2, 3, and 4 are a perspective view, a longitudinal sectional view, and a transverse sectional view of the lighting device.

  As shown in FIGS. 1 to 4, the lighting device 1 is provided in a linear light source 3 made of, for example, a fluorescent lamp, a substantially rectangular box-shaped casing 4 surrounding the light source 3, and a lower opening of the casing 4. And an illumination cover 2 serving as a light emitting surface and a drive circuit (not shown) for driving the light source 3. A plurality of lighting devices 1 are installed on the ceiling of an office or the like so as to be embedded in the ceiling 12.

  The housing 4 has a rectangular lower opening 4a, and the light source 3 is mounted in the housing 4, extends along the longitudinal direction of the housing, and faces the lower opening 4a. The light source 3 is provided at substantially the center in the width direction of the housing 4 and further extends horizontally, here in parallel with the ceiling 12.

  The illumination cover 2 is formed in a rectangular plate shape, is disposed in the lower opening 4 a of the housing 4, closes the lower opening, and faces the light source 3. The illumination cover 2 has a flat inner surface 2a facing the light source 3 and a rectangular outer surface 2b facing outward. The inner surface 2a is positioned substantially horizontally, here parallel to the ceiling 12. The outer surface 2 b of the illumination cover 2 has a zigzag shape and a concavo-convex shape in which peaks and valleys extend in a direction orthogonal to the longitudinal direction of the light source 3.

  The illumination cover 2 is, for example, a plate-like shape having a thickness of about 2 mm formed of a transparent polycarbonate resin, and has an inclination angle of 20 mm on the outer surface 2b with a pitch P = 8 mm and a ripple T = 1.5 mm with respect to the longitudinal direction. A plurality of 6-degree zigzag prisms 10 are provided. Each prism 10 extends in the width direction of the illumination cover 2, that is, in a direction orthogonal to the longitudinal direction of the light source 3, and the plurality of prisms 10 are formed side by side in the longitudinal direction of the illumination cover. . In the present embodiment, the plurality of prisms 10 are provided over the entire outer surface 2b.

FIG. 5 shows the light distribution of the illuminating device 1 in the longitudinal direction. The angle of the radar chart indicates the direction in which the illuminating device 1 irradiates, and the vertical axis indicates the luminous intensity in that direction.
In the light distribution in the longitudinal direction of the lighting device 1, θ is 60 to 90 degrees due to the action of the prism 10 of the lighting cover 2 when the angle formed with the ceiling normal direction (the normal direction of the lighting cover 2) is θ. In this range, the light is shielded so that the light intensity ratio with respect to the light intensity (100%) where θ is 0 degrees is 10% or less. Moreover, in the range where θ, which is indispensable for irradiation by the illumination device 1, is in the range of 0 to 45 degrees, the luminous intensity ratio is almost uniform with 60 to 100%.
As shown in FIG. 4, the light distribution in the width direction of the illuminating device 1 is designed so that a part of the light emitted from the light source 3 is shielded by the side wall of the housing 4. It is possible to realize a light distribution in which θ is approximately 60 to 90 degrees and the luminous intensity ratio is 10% or less, θ is 0 to 45 degrees, and the luminous intensity ratio is 60 to 100%.

  FIG. 6 shows the light distribution distribution control action in the longitudinal direction by the illumination cover 2. That is, FIG. 6 is a diagram schematically showing an enlarged portion of the prism 10 of the illumination cover 2. In FIG. 6, of the light rays (arrows) incident on the illumination cover 2 from the lower left side, the light exiting from the left half surface of the prism 10 is more than the inclination angle α of the exit surface of the prism 10 due to the total reflection of the exit interface. The light blocking function is demonstrated by the fact that almost no horizontal rays are emitted. The totally reflected light is reflected to the light source 3 side. Of the light rays incident from the lower left side, the light emitted from the right half surface of the prism 10 is generated in the vertical direction (normal direction) by a predetermined angle due to the prism refraction action corresponding to the inclination angle α formed by the incident surface and the exit surface. Is emitted.

  FIG. 7 shows the relationship between the maximum angle of light emitted from the right half surface of the prism 10 and the inclination angle α. In the case of the illumination cover 2 made of polycarbonate, it is understood that the inclination angle α of the prism 10 should be 10 degrees in order to make the maximum angle β of the emitted light 60 degrees or less.

  Even in the case of materials other than polycarbonate, the inclination angle α of the prism which makes the maximum angle β of the light emitted by the prism refraction action not more than 60 degrees does not exceed 20 degrees as long as it is a general transparent resin or glass. Simply, considering the above-described total reflection action, the inclination angle α may be set to 30 degrees or more. However, in practice, there is a mode in which the totally reflected light is multiple-reflected inside the illumination cover 2 and emitted again, and as the inclination angle α of the prism 10 increases, the amount of totally reflected light increases rapidly. For this reason, the inclination angle α is not preferably 30 degrees or more.

Next, the angle range of the prism 10 that can be used as the illumination cover 2 in consideration of the above influence will be described.
8, the horizontal axis represents the prism inclination angle α of the illumination cover 2, the left vertical axis represents the luminous intensity ratio obtained by normalizing the luminous intensity at a predetermined angle with the normal direction luminous intensity, and the right vertical axis represents illumination with or without the illumination cover 2. The ratio of the total emitted light quantity of the apparatus 1 is shown as efficiency. The luminous intensity ratios of 60, 70, and 80 degrees are not related to the illuminance of the work environment and are unnecessary angles that mainly cause glare, and are desirably low. The luminous intensity ratio of 45 degrees is an edge of an effective illuminance range to be irradiated by the lighting device 1, and is preferably close to 100% from the viewpoint of uniform irradiation, and is at least 50% or more, at most 200% or less, that is, effective irradiation. In the range of θ: −45 to +45 degrees, which is the range, it is necessary that the light intensity unevenness does not exceed 1: 2. Higher efficiency is desirable. The distribution of light distribution at each inclination angle is appended around the graph. FIGS. 9, 10, and 11 show the ray trajectory and light distribution at three typical inclination angles α.

  As shown in FIG. 8 and FIG. 9, the inclination angle α of the prism 10 is 0 degree, that is, the light shielding action described above does not occur with a simple transparent flat plate, so the light incident on the illumination cover 2 at θ60 to 90 degrees is The light is emitted at the same angle, and the luminous intensity ratio reaches 60%, and glare is felt.

  As shown in FIGS. 8 and 10, in this embodiment (inclination angle α = 20.6 degrees), the luminous intensity ratio is reduced by 60 to 90 degrees by the action of the prism 10 described in FIG. Since the angle is small, the total reflected light amount is small, and there is almost no adverse effect caused by the total reflected light beam described later. Also, the luminous intensity ratio of 45 degrees, which is the edge of the effective irradiation range, is an ideal light distribution that maintains the luminous intensity ratio of 60%.

  As shown in FIGS. 8 and 11, when the inclination angle α is increased to 45 degrees, two adverse effects occur. One is re-emission of totally reflected light rays. This is because the light beam totally reflected on the exit surface of the prism 10 is reflected multiple times inside the illumination cover 2 and is emitted again on the right half surface of the prism, and is recognized when the tilt angle α exceeds 35 degrees, and the tilt angle 42 degrees. If it exceeds, the luminous intensity ratio of 60 to 90 degrees exceeds 20%. The other is excessive light collection. When the inclination angle α exceeds 20 to 25 degrees, the maximum angle β of the emitted light is less than 50 degrees due to the prism refraction action as shown in FIG. As a result, when the inclination angle is 27 degrees or more, the irradiation range that should be irradiated is excessively narrowed, resulting in a focused illumination range such as a spotlight. In the light distribution shown in FIG. 11, these appear in the protruding light intensity peak in the range of θ60 to 90 degrees and excessive condensing of the light intensity distribution in the range of θ0 to 45 degrees.

  From the above, in order to suppress glare to less than half (20% or less at a luminous intensity ratio of 60 to 90 degrees), the illumination cover 2 having an average inclination angle α of the prism 10 of about 12 to 42 degrees is desirable. In addition, in order to maintain the size and uniformity of the irradiation area as well as the glare relaxation (50% or more at a luminous intensity ratio of 45 degrees), the illumination cover 2 having an average inclination angle α of the prism of about 12 to 27 degrees is desirable.

  FIG. 12 shows the relationship between the ratio of the area of the prism region where the prism 10 is provided, the luminous intensity ratio, and the efficiency with respect to the entire area of the outer surface 2b of the illumination cover 2. That is, FIG. 12 shows the change in efficiency of the illumination device 1 when the area ratio of the prism region is 100% (when a plurality of prisms 10 are formed on the entire outer surface 2b), 90% to 0%, and Changes in the luminous intensity ratios of 60 degrees, 70 degrees, and 80 degrees are shown, respectively, and further, the light distribution of the lighting device 1 at each area ratio is shown.

  From FIG. 12, it can be seen that the area ratio of the prism 10 and the glare reduction effect are in a substantially linear relationship. Therefore, in order to suppress the glare to less than half (20% or less at a luminous intensity ratio of 60 to 80 degrees), the area of the prism region in the category of the optimum inclination angle is set to the area of the outer surface 2b of the illumination cover 2. And more than half (50% or more). Moreover, the efficiency of the illuminating device 1 can maintain 90% or more irrespective of the area ratio of a prism area.

  The lighting cover 2 is made of polycarbonate resin. However, the same material can be used as long as it is transparent and has a higher refractive index than air, such as acrylic resin or glass, and the total reflection action is mainly governed. Therefore, the tilt angle range is almost the same. Although a fluorescent lamp is used as the light source 3, another light source such as an LED or an incandescent bulb may be used, and a diffusion member may be interposed between the light source and the illumination cover. Moreover, the illumination cover 2 is good also as a curved surface shape instead of a flat plate.

  According to the illuminating device 1 configured as described above, the illumination cover having the prism can reduce light in the angle θ range of 60 to 90 degrees, and can greatly reduce glare. The lighting cover 2 can be easily and inexpensively manufactured with synthetic resin, glass, etc., and has a simple structure and is easily cleaned as compared with a reflector such as a louver, baffle, or louver. It is possible. The illuminating device 1 has little light absorption by the illumination cover and can maintain high illumination efficiency. As described above, an illumination device that is easy to clean, low in manufacturing cost, and high in efficiency can be obtained.

  Next, lighting covers of lighting devices according to various modifications will be described. In the various modifications described below, the same parts as those in the first embodiment are denoted by the same reference numerals, detailed description thereof is omitted, and different parts are mainly described in detail.

  In the illumination device according to the first embodiment described above, the inclination angle α of the prism formed on the illumination cover is set uniformly at 20.6 degrees on the outer surface and the entire surface of the illumination cover. Therefore, as in the light distribution shown in FIG. 10, the luminous intensity changes abruptly around the angle θ40 degrees, and in some cases, the lighting device 1 may appear to be turned on / off around 40 degrees.

  As a means for moderating this sudden change in luminous intensity, the inclination angle α of the prism 10 may have a width in each region of the outer surface 2b of the illumination cover 2. Of course, it is desirable that the range having the width of the inclination angle α is within the above-described inclination angle range of about 12 to 42 degrees.

(First modification)
FIG. 13 shows the illumination cover 2 of the illumination device according to the first modification. The prism 10 provided on the outer surface 2b of the illumination cover 2 may not be a simple complete straight line pattern but may be a curve or zigzag with some undulations.

  As shown in FIG. 13, the plurality of prisms 10 provided on the outer surface of the illumination cover 2 are inclined by changing the height of the mountain (the height of the prism top) (swell) with a constant zigzag valley. The angle α is wide. That is, the height change (swell) of the peak of the prism 10 is configured to have the same phase as the height change of the adjacent prism peak.

(Second modification)
FIG. 14 shows the illumination cover 2 of the illumination device according to the second modification. The prism 10 provided on the outer surface 2b of the illumination cover 2 may not be a simple complete straight line pattern but may be a curve or zigzag with some undulations.

  As shown in FIG. 14, the plurality of prisms 10 provided on the outer surface 2b of the illumination cover 2 has a zigzag valley at a constant height, and changes (swells) the height of the mountain (the height of the prism top). The inclination angle α is wide. The height change (swell) of the peak of the prism 10 is configured to have an opposite phase to the height change of the adjacent prism peak. In addition, the phase of peaks or valleys may be changed more complicatedly.

(Third Modification)
FIG. 15 shows the illumination cover 2 of the illumination device according to the third modification. As shown in FIG. 15, the plurality of prisms 10 provided on the outer surface 2 b of the illumination cover 2 have a wide inclination angle by changing the depth of the valleys (swells) with a zigzag mountain as a constant height. The configuration is The change (swell) of the valley depth of the prism 10 is configured to be in phase with the change of the depth of the valley of the adjacent prism.

(Fourth modification)
FIG. 16 shows the illumination cover 2 of the illumination device according to the third modification. As shown in FIG. 16, the plurality of prisms 10 provided on the outer surface 2b of the lighting cover 2 have a zigzag peak as a constant height and change the depth of the valley (swell) so that the inclination angle has a width. The configuration is The change (swell) of the valley depth of the prism 10 is configured to have an opposite phase to the change of the depth of the valley of the adjacent prism.

  In addition, as the structure which produces the effect similar to the 1st-4th modification, the height of the peak and valley of the prism 10 is made constant, the peak or valley is waved rather than a straight line, that is, the tilt angle is changed by changing the bottom length of the tilt. May be scattered.

(5th modification)
FIG. 17 shows the illumination cover 2 of the illumination device according to the fifth modification. According to the fifth modification, the plurality of prisms 10 of the illumination cover 2 are two-dimensionally arranged.

  In the first embodiment described above, as shown in FIG. 4, the light emitted in the width direction of the fluorescent lamp 3 is shielded by the side wall of the housing 4 and the light distribution is controlled. For a light source capable of the above, it is desirable to block light of all longitude angles by the prism action of the illumination cover-2 itself. Therefore, according to the fifth modification, as shown in FIG. 17, the plurality of prisms 10 provided on the outer surface 2b of the illumination cover 2 are each formed in a pyramid shape having four inclined surfaces. . Each prism 10 has a surface center 102, a base 103, and a plurality of peaks 101.

(Sixth Modification)
FIG. 18 shows the illumination cover 2 of the illumination device according to the sixth modification. According to the sixth modification, the plurality of prisms 10 of the illumination cover 2 are two-dimensionally arranged.

  In the above-described fifth modification, the prism action is not exerted on the light rays along the region indicated by the thick line in FIG. 17, and the light shielding performance may be deteriorated particularly in a specific direction. This can also be seen from the fact that the inclination angle of the pyramid surface center 102 is steeper than the inclination angle of the pyramid ridge 101 in FIG. 17 and the inclination angle of the pyramid base 103 is 0 degree. Therefore, according to the sixth modification, as shown in FIG. 18, the center of the base of the pyramid prism 10 having the center 102, the base 103, and the plurality of peaks 101 is raised, that is, the pyramid base 103 is inclined. In addition, the inclination of the pyramid surface center 102 is relaxed, and the difference in the inclination angle depending on the direction generated in the fifth modification is reduced, so that the optimum prism action can be exhibited in any direction. Thereby, the illumination cover 2 can exhibit the light-shielding performance without unevenness in all directions.

  The prism 10 has a convex pyramid shape and arrangement with respect to the outer surface, but may be configured with a concave pyramid shape arrangement on the outer surface. Further, the prism 10 may be formed in another two-dimensional spread arrangement such as a hexagonal close-packed pattern.

The present invention is not limited to the above-described embodiments and modifications as they are, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.
For example, the light source is not limited to a fluorescent lamp, and a light source in which a plurality of LEDs are arranged linearly or planarly may be used.

DESCRIPTION OF SYMBOLS 1 ... Illuminating device, 2 ... Lighting cover, 2a ... Inner surface, 2b ... Outer surface, 3 ... Light source,
4 ... housing 4a ... lower opening 10 ... prism

Claims (9)

An inner surface facing the light source, an outer surface facing outward, and a plurality of prisms formed on the outer surface,
The prism has at least one inclined surface inclined with respect to the inner surface;
The inclination angle of the inclined surface of the prism is at least 12 to 42 degrees on average,
A lighting cover in which the ratio of the luminous intensity in the direction of θ = 60 to 90 degrees to the luminous intensity in the direction of θ = 0 degrees is 20% or less, where θ is an angle formed with the normal direction of the inner surface lighting cover.   The lighting cover according to claim 1, wherein an inclination angle of the inclined surface of the prism is 12 to 27 degrees on average.   The lighting cover according to claim 1 or 2, wherein the minimum value of the luminous intensity ratio in the direction of θ = 0 to 45 degrees is not less than 50% and not more than 200%.   4. The lighting cover according to claim 1, wherein a ratio of an area of the prism region in which the plurality of prisms is formed to a total area of an outer surface of the lighting cover is 50% or more. 5.   5. The illumination cover according to claim 1, wherein the inclined surface of the prism is a one-dimensionally arranged prism that is inclined with respect to a longitudinal direction of the light source and extends in a direction orthogonal to the longitudinal direction.   The lighting cover according to claim 5, wherein the plurality of prisms are formed so as to have different inclination angles of inclined surfaces in individual regions of the lighting cover.   The illumination cover according to any one of claims 1 to 4, wherein the plurality of prisms are two-dimensionally arranged prisms.   In the two-dimensional array of prisms, each side of the polygonal lattice constituting the prism is all inclined, and the difference in the maximum inclination angle of each side is smaller than the maximum inclination angle difference when not inclined. Item 8. The lighting cover according to Item 7. A light source;
An illumination device comprising: the illumination cover according to claim 1, wherein the illumination cover is disposed so as to face the light source and constitutes a light emitting surface.

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