JP5313181B2 - Lighting device - Google Patents

Description

  The present invention relates to an illumination device that illuminates a predetermined irradiation area by collecting light emitted from a light emitting unit with a lens.

  Conventionally, there is an illumination device having a light emitting diode (LED) as a light emitting unit. Lighting devices having LEDs include those that diffuse and illuminate light emitted from the light emitting part such as ceiling lights and base lights, those that condense and illuminate light such as downlights and spotlights, landscape lighting, There are street lights that illuminate using both diffusion and light collection. As shown in FIGS. 14A, 14B, and 14C, an illuminating device 101 that uses both diffusion and condensing includes a light emitting unit 103 and a rectangular lens 104 in plan view. In the width direction (short side direction) of the lens 104, the light emitted from the light emitting unit 103 is collected by the lens 104, and in the longitudinal direction (long side direction) of the lens 104, the light emitted from the light emitting unit 103 is The light is diffused without being condensed by 104. In the figure, the direction in which the light is collected is the x direction, the direction in which the light is diffused is the y direction, and the direction of the optical axis 131 is the z direction (the same applies to the following drawings). Since the longitudinal direction (y direction) of the lens 104 is linear with a finite length, as shown in FIG. 15, the light distribution characteristic of the illumination device 101 has a narrow angle in the diffusion direction (y direction).

  As an illumination device having a light distribution characteristic in which the angle in the diffusion direction is enlarged, as shown in FIGS. 16A, 16B, and 16C, the shape of the lens 114 is a semicircle centered on the light emitting unit 103 on the yz plane. There is an illuminating device 111 having an arc shape. As shown in FIG. 17, the light distribution characteristic of the illumination device 111 has a relatively wide angle in the diffusion direction (y direction). However, the illumination device 111 as described above decreases in luminous intensity when the angle θ (hereinafter referred to as a viewing angle) from the optical axis 131 in the diffusion direction increases. When such an illuminating device 111 is used for a landscape illuminating device, it is difficult to see the lighting of the illuminating device 111 when the viewing angle increases. In addition, when the lighting device 111 is used for a street lamp, the illumination intensity on the ground is low because the viewing angle is large at a location far from the lighting device 111.

  An illumination optical system that includes a condensing lens and a diffusing lens and has a high luminous intensity in a region with a large viewing angle is known (for example, see Patent Document 1). However, when a lighting device having such an illumination optical system is used for a landscape lighting fixture, the luminous intensity is high in a region with a large viewing angle, the luminous intensity is low in a region with a small viewing angle, and the luminous intensity changes depending on the viewing angle. The beauty is impaired.

  As shown in FIGS. 18 to 20, when the illumination device 121 having such an illumination optical system is used for a street lamp, the illumination device 121 is arranged at a position higher than the head of the person H, Illuminate the irradiation region that is long in the direction along the passage (y direction). When the illuminating device 121 is looked up from directly below, the viewing angle θ is 0, and the viewing angle θ increases as the distance from the bottom to the y direction increases along the sidewalk and the like. The irradiation distance from the illumination device 121 to the irradiation surface is farther from the far end region of the irradiation region. Further, the beam angle α with respect to the irradiation surface with a large viewing angle θ (θ = θ3) is comparable or less than the beam angle with respect to the irradiation surface with a small viewing angle θ (θ = θ4). For this reason, in the irradiation region, the width W3 in the light collecting direction (x direction) of the region with a large viewing angle θ is wider than the width W4 of the region with a small viewing angle θ, and illuminates a sidewalk or the like with a constant width. I can't.

JP 2009-99493 A

  The present invention solves the above-described problem, and an object of the present invention is to prevent the luminous intensity from decreasing as the viewing angle increases in an illumination device.

  In order to achieve the above object, the invention of claim 1 is provided with a mounting substrate, a light emitting portion attached to the mounting substrate and having an optical axis substantially orthogonal to the mounting substrate, and light emitted from the light emitting portion. A lens for controlling light, wherein the lens has a cross-sectional shape on a plane including the optical axis, and a plane obtained by rotating the plane around a viewpoint axis by an arbitrary viewing angle. The convex lens shape has a continuously changing cross-sectional shape, and the lens diameter of the convex lens shape increases as the viewing angle increases.

According to a second aspect of the present invention, in the illumination device according to the first aspect, the viewing angle is θ, the lens diameter of the convex lens shape at the viewing angle θ is d (θ), the focal length is f (θ), and k is positive. The above convex lens shape satisfies the following formula.

  According to a third aspect of the present invention, in the illumination device according to the first aspect, when the viewing angle is smaller than a predetermined angle, the focal length of the convex lens shape is different from the distance from the light emitting unit to the lens, and the The lens diameter of the convex lens shape is set so that a desired light beam can be obtained.

  According to the first aspect of the present invention, even if the luminous intensity of the light emitted from the light emitting portion decreases as the viewing angle increases, the decrease in luminous intensity is compensated by the increase in the lens diameter of the convex lens shape. It is possible to prevent the brightness of the emitted light from decreasing.

  According to the second aspect of the present invention, since the light beam incident on the lens is constant regardless of the viewing angle, the luminous intensity of the light emitted from the illumination device is constant regardless of the viewing angle.

  According to the invention of claim 3, since the condensing action by the lens is weak when the viewing angle is small, the width of the condensing direction of the region with a small viewing angle is widened in the irradiation region, and the width of the region with a large viewing angle is Can be reduced.

The perspective view of the illuminating device which concerns on the 1st Embodiment of this invention. (A) is sectional drawing of the lens in the illumination device, (b) is sectional drawing in another cross section of the lens. (A) is a plan view of the lens, (b) is a side view of the lens, (c) is a front view of the lens, and (d) is a rear view of the lens. (A) is the figure showing the light distribution characteristic in the space of the light emission part in the said illuminating device, (b) is the figure which planarly viewed the light distribution characteristic, (c) was planarly viewed from another direction. Figure. The figure which shows the angle dependence of the luminous intensity of the light emission part. Sectional drawing in the viewing angle with the said lens. The figure showing the light distribution characteristic of the said illuminating device. Sectional drawing of the lens in the small viewing angle in the illuminating device which concerns on the 2nd Embodiment of this invention. Sectional drawing in a small viewing angle in the modification of the lens. Sectional drawing of the lens in the big viewing angle in the said illuminating device. The figure which shows the light distribution characteristic of the illuminating device. The figure explaining the beam angle of the light irradiated from the illumination device. The perspective view of the street lamp using the illumination device. (A) is a perspective view of the conventional illuminating device, (b) is sectional drawing of the illuminating device, (c) is sectional drawing in another cross section of the illuminating device. The figure showing the light distribution characteristic of the illuminating device. (A) is a perspective view of another conventional illumination device, (b) is a sectional view of the illumination device, and (c) is a sectional view of another illumination device. The figure showing the light distribution characteristic of the illuminating device. The perspective view of the street lamp using another conventional illuminating device. The figure showing the light distribution characteristic of the illuminating device. The figure explaining the beam angle of the light irradiated from the illumination device.

(First embodiment)
A lighting apparatus according to a first embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 1 to 3A, 3B, 3C, and 3D, the illumination device 1 according to this embodiment includes a mounting substrate 2, a light emitting unit 3 mounted on the mounting substrate 2, and a lens. 4. The light emitting unit 3 has an optical axis 31 that is substantially orthogonal to the mounting substrate. The lens 4 controls the light distribution of the light emitted from the light emitting unit 3. This lens 4 has a cross-sectional shape at the surface S (0) including the optical axis 31 and a cross-section at the surface S (θ) obtained by rotating the surface S (0) about the viewpoint axis 32 by an arbitrary viewing angle θ. This is a convex lens shape 41 whose shape changes continuously. The lens diameter d (θ) of the convex lens shape 41 increases as the viewing angle θ increases. The viewpoint axis 32 is orthogonal to the optical axis 31 and is in contact with the light emitting surface 33 of the light emitting unit 3. In the figure, the direction of the optical axis 31 is the z direction, the direction of the viewpoint axis 32 is the x direction, and the direction orthogonal thereto is the y direction. The lens 4 is plane-symmetric with respect to a plane including the optical axis 31 and the viewpoint axis 32. In addition, since the illuminating device 1 radiates | emits light to the space (z> 0) ahead of the light emission part 3, viewing angle (theta) does not exceed 90 degrees.

  The attachment substrate 2 is a substrate for attaching the light emitting unit 3, is connected to a power source outside the lighting device 1, and supplies power to the light emitting unit 3. The light emitting unit 3 preferably emits light with a light emitting surface 33 having a completely diffusing surface and a size close to a high-luminance point, for example, a light emitting diode. The organic EL emits light on the completely diffusing surface, but is not suitable for the light emitting part 3 because the area of the light emitting part is large.

  The lens 4 is formed by molding a plastic such as acrylic or polycarbonate, or a transparent material such as general optical glass. Although the convex lens shape 41 of the lens 4 is shown as a single convex, it may be biconvex. The incident surface 42 on which light is incident on the lens 4 has an arc shape with a radius R centered on the light emitting surface 33 of the light emitting unit 3 in plan view (yz surface). For example, the lens 4 is formed by injection molding using a mold.

  The mounting substrate 2, the light emitting unit 3, and the lens 4 are fixed by an appropriate configuration. The lighting device 1 includes, for example, a bottomed and uncovered casing (not shown), the mounting substrate 2 and the light emitting unit 3 are disposed at the bottom of the casing, and the lens 4 is provided at the opening of the casing. The illuminating device 1 is evaluated by performing light distribution measurement by changing the viewing angle θ and comparing the luminous intensity values at the respective viewing angles θ.

  In the illumination device 1 configured as described above, light emitted from the light emitting unit 3 enters the lens 4. The light incident on the lens 4 is collected by the convex lens shape 41 in the direction of the viewpoint axis 32 (x direction), and is not collected in the direction (y direction) orthogonal to the optical axis 31 and the viewpoint axis 32. Spread as it is. The light emitted from the light emitting unit 3 and entering the lens 4 decreases as the viewing angle θ increases. In the lens 4, the convex lens shape 41 on the surface S (θ) intersecting the surface S (0) including the optical axis at a viewing angle θ increases the lens diameter d (θ) as the viewing angle θ increases. To do. For this reason, even if the viewing angle θ increases, the decrease in luminous intensity from the light emitting unit 3 is compensated for by increasing the lens diameter d (θ), and the viewing angle θ increases without reducing the light flux incident on the lens 4. As it becomes, it can prevent that the luminous intensity of the light radiate | emitted from the illuminating device 1 falls.

The compensation for the decrease in luminous intensity by the lens 4 will be described in detail. 4A, 4B, and 4C show the light distribution characteristics of the light emitting unit 3 alone, where FIG. 4A shows the light distribution characteristics in the xyz space, FIG. 4B shows the light distribution characteristics of the yz plane, and FIG. Represents the light distribution characteristic of the zx plane. If the angle formed by the light emission direction indicated by the arrow L and the optical axis 31 is the viewing angle θ on the yz plane and the angle φ on the zx plane, the luminous intensity I (θ, φ) in the emission direction (the size of the arrow L) ) Is expressed by the following equation according to Lambert's cosine law.
I (θ, φ) = I cos θ cos φ
As shown in FIG. 5, I cos θ cos φ is a value at an angle φ of a cosine curve whose maximum value is I cos θ.
Light having this luminous intensity I (θ, φ) is emitted from the light emitting unit 3 and is incident on the lens 4.

  The condition that the luminous intensity of the light emitted from the illumination device 1 is constant regardless of the viewing angle θ is that the light beam emitted from the light emitting unit 3 and incident on the lens 4 is constant regardless of the viewing angle θ. A luminous flux is a radiant flux that passes through a certain area. On the incident surface of the lens 4, the area between viewing angles θ to θ + Δθ (Δθ is a minute increment) is proportional to the lens diameter d (θ) at the viewing angle θ, and is d (θ) × Δθ. The luminous flux passing through this area is the area of luminous intensity I (θ, φ) in the area d (θ) × Δθ. The condition under which the luminous flux incident on the lens 4 is constant regardless of the viewing angle θ is that Δθ is very small. Therefore, the integrated value obtained by integrating the luminous intensity I (θ, φ) at the viewing angle θ in the direction of the lens diameter d (θ). Is approximated to be constant.

FIG. 6 shows the geometry of the lens 4 at the viewing angle θ = θa. At the viewing angle θ = θa, the lens diameter of the convex lens shape 41 is d (θ = θa), and the focal length is f (θ = θa). The angles at which the incident surface 42 of the lens 4 faces from the light emitting unit 3 are + φa and −φa. The luminous intensity I (θ = θa, φ) of the light incident on the lens 4 at the viewing angle θ = θa is expressed by the following equation.
I (θ = θa, φ) = Icos θacosφ

The integrated value of the luminous intensity I (θ = θa, φ) within the incident angle [−φa, + φa] of the lens 4 at the viewing angle θ = θa is obtained as follows.

Therefore, the condition that the integrated value of the luminous intensity I (θ = θa, φ) is constant regardless of the viewing angle θ is expressed by the following equation, where k is a positive constant.

Here, sinφ is expressed by the following equation using the focal length f (θ) and the lens diameter d (θ).

レンズ４は、視野角θにおける凸レンズ形状４１が上記式（数５）を満たすように形成される。これにより、レンズ４に入射する光束が視野角θによらず一定となり、図７に示されるように、照明装置１から出射される光の光度が視野角θによらず略一定となる。なお、レンズ４は、同式を満たせば、視野角θによって焦点距離ｆ（θ）が変化するように形成してもよい。焦点距離ｆ（θ）は、レンズ４の断面形状が球面レンズの場合、屈折率、曲率半径、及び厚みから算出される。 When the above two formulas are developed to eliminate sinφ and the lens diameter d (θ) is obtained, the following formula is obtained.

The lens 4 is formed so that the convex lens shape 41 at the viewing angle θ satisfies the above formula (Equation 5). Thereby, the light beam incident on the lens 4 becomes constant regardless of the viewing angle θ, and as shown in FIG. 7, the luminous intensity of the light emitted from the illumination device 1 becomes substantially constant regardless of the viewing angle θ. The lens 4 may be formed so that the focal length f (θ) varies depending on the viewing angle θ as long as the same equation is satisfied. The focal length f (θ) is calculated from the refractive index, the radius of curvature, and the thickness when the cross-sectional shape of the lens 4 is a spherical lens.

(Second Embodiment)
A lighting device 1 according to a second embodiment of the present invention will be described with reference to FIGS. The illumination device 1 of the present embodiment has the same configuration as that of the first embodiment, and when the viewing angle θ is smaller than a predetermined angle, the focal length of the convex lens shape 41 is shown in FIGS. 8 and 9. f (θ) is made different from the distance R from the light emitting portion 3 to the lens 4 (f (θ)> R or f (θ) <R), and the lens diameter d (θ) of the convex lens shape 41 is set to a desired light flux. Was set to be obtained. When the viewing angle θ is equal to or greater than a predetermined angle, as shown in FIG. 10, the focal length f (θ) of the convex lens shape 41 is set to be the same as the distance R from the light emitting unit 3 to the lens 4 (f (Θ) = R). The predetermined angle is appropriately determined according to the installation status of the lighting device 1 and the like. 8 and 9 show the case where the focal length f (θ) is changed. However, even if the focal length f (θ) is made different from the distance R by changing the distance R from the light emitting unit 3 to the lens 4. Good. The lens diameter d (θ) is set so that, for example, the light beam incident on the lens 4 is constant regardless of the viewing angle θ, as in the first embodiment.

  The illuminating device 1 configured as described above has a weak condensing action by the lens 4 when the viewing angle is small. For this reason, as compared with the light distribution characteristic of the conventional illumination device (see FIG. 19), the illumination device 1 has a larger beam angle when the viewing angle is small and spreads in the x direction as shown in FIG. Have good light distribution characteristics. As shown in FIG. 12, the beam angle α1 with respect to the irradiation surface with a small viewing angle θ (θ = θ1) is larger than the beam angle α2 with respect to the irradiation surface with a large viewing angle θ (θ = θ2) (α1>). α2). For this reason, in the irradiation region, the width W1 in the condensing direction (x direction) of the region where the viewing angle θ is small can be widened, and the difference from the width W2 of the region where the viewing angle θ is large can be reduced. It is desirable for the lens 4 to set the focal length f (θ) so that the width of the irradiation region in the light collecting direction is constant regardless of the viewing angle θ. The illuminating device 1 measures, for example, the illuminance distribution on the irradiated surface, and is evaluated by its shape and uniformity.

  When this illuminating device 1 is used for a street lamp, for example, as shown in FIG. 13, in the irradiation region 11, the width W1 in the light condensing direction of the region where the viewing angle θ is small (θ = θ1) and the viewing angle θ are A difference with the width W2 of the large (θ = θ2) region is reduced, and the sidewalk or the like can be illuminated with a substantially constant width. The lens 4 sets the focal length f (θ) so that the width of the irradiation region 11 in the condensing direction is constant regardless of the viewing angle θ, and the shape of the irradiation region 11, that is, the illuminance distribution shape is a rectangle. Is desirable. Thereby, in the irradiation region 11, the width W2 of the region having a large viewing angle θ is not wider than the width W1 of the region having a small viewing angle θ, and light can be irradiated only in a necessary range.

  In addition, this invention is not restricted to the structure of said embodiment, A various deformation | transformation is possible in the range which does not change the summary of invention. For example, you may use the illuminating device 1 of 1st Embodiment for a landscape lighting fixture, and this prevents that a luminous intensity changes with a viewing angle.

DESCRIPTION OF SYMBOLS 1 Illuminating device 2 Mounting board 3 Light emission part 31 Optical axis 32 View axis 4 Lens 41 Convex lens shape d Lens diameter f Focal length k Constant S Surface (theta) Viewing angle

Claims (3)

An illumination device comprising: a mounting substrate; a light emitting unit attached to the mounting substrate and having an optical axis substantially orthogonal to the mounting substrate; and a lens for controlling light distribution of light emitted from the light emitting unit. ,
The lens is a convex lens shape in which a cross-sectional shape on a surface including the optical axis, and a cross-sectional shape on a surface obtained by rotating the surface by an arbitrary viewing angle around a viewpoint axis, continuously change, and The illumination device characterized in that the lens diameter of the convex lens shape increases as the viewing angle increases. When the viewing angle is θ, the lens diameter of the convex lens shape at the viewing angle θ is d (θ), the focal length is f (θ), and k is a positive constant,
The illumination device according to claim 1, wherein the convex lens shape satisfies the following formula.

  When the viewing angle is smaller than a predetermined angle, the focal length of the convex lens shape is made different from the distance from the light emitting unit to the lens, and the lens diameter of the convex lens shape is set so that a desired luminous flux can be obtained. The lighting device according to claim 1.

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