JP2018077935A - Luminaire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a luminaire which has achieved uniformity in luminance and which has high luminance.SOLUTION: A luminaire includes: a Fresnel lens extending in a zx plane; a rod-like light guide body arranged by being separated in a y direction by a focal distance f of the Fresnel lens from the Fresnel lens, and extending in a z direction; and at least one light source arranged on one end of the light guide body. The light from the light source propagates in the z direction by the light guide body. A plurality of prisms formed at the light guide body controls the light distribution in the z direction of the light emitted from the light guide body, and a plurality of prisms formed at the Fresnel lens controls the light distribution in the x direction of the light emitted from the Fresnel lens.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lighting device, and more particularly to a high-luminance lighting device used for a head-up display.

In recent years, a head-up display (HUD) has been used as a means for providing image information in the forward field of view to a driver of an aircraft or a vehicle. It is said that a lighting device for a head-up display requires high luminance of 1 million cd / m ² or more.
For example, a conventional in-vehicle illumination device described in Patent Document 1 includes a surface light source in which a plurality of LEDs are arranged in a two-dimensional manner, and each LED in order to convert light from the surface light source into substantially parallel light. Condensing means comprising Fresnel lenses provided at corresponding positions, and light diffusing means in which Fresnel lenses having a smaller diameter than the Fresnel lens of the condensing means are arranged at a higher density than the condensing means. . This illuminating device can constitute a high-intensity light source unit suitable for a head-up display together with a liquid crystal panel.

JP 2007-87792 A

However, in the case of the direct illumination device described in Patent Document 1 described above, the high-brightness LEDs are arranged two-dimensionally, so that the center of each LED is bright and dark between adjacent LEDs. As a result, the brightness of the entire lighting device is uneven, and there is a problem that the appearance is poor.
Therefore, an object of the present invention is to solve the above-described problems, and to provide a high-luminance lighting device that has excellent luminance uniformity and high luminance.

The gist of the present invention is as follows.
The lighting device of the present invention is
a Fresnel lens extending in the zx plane;
A rod-shaped light guide that is disposed away from the Fresnel lens in the y direction by the focal length f of the Fresnel lens and extends in the z direction;
At least one light source disposed at one end of the light guide;
Have
The light from the light source propagates in the z direction by the light guide,
The plurality of prisms formed on the light guide body controls light distribution in the z direction of light emitted from the light guide body,
The plurality of prisms formed on the Fresnel lens controls light distribution in the x direction of light emitted from the Fresnel lens.
It is characterized by that.

The lighting device of the present invention is
The light guide has a wedge shape whose cross-sectional area decreases as the distance from the light source increases.
It is preferable.

The lighting device of the present invention is
Have two light sources,
The two light sources are disposed at both ends of the light guide,
It is preferable.

It is a figure which shows the illuminating device which concerns on 1st Embodiment of this invention. (A) shows the light distribution after passing through the light guide of the lighting device, and (b) shows the light distribution after passing through the Fresnel lens of the lighting device. It is a figure for demonstrating the output light distribution from a light guide. It is a figure which shows the various modifications of an optical path conversion means. It is a figure which shows the illuminating device which concerns on 2nd Embodiment of this invention.

Hereinafter, an illuminating device of the present invention will be described in detail with reference to the drawings, illustrating an embodiment thereof.
Fig.1 (a) is a perspective view of the illuminating device based on 1st Embodiment of this invention, FIG.1 (b) is a figure which shows a part of this illuminating device in yz plane, FIG.1 (c) ) Is a diagram showing an xy cross section of the illumination device.
The lighting device 10 includes a Fresnel lens 2, a rod-shaped light guide 4 (also referred to as a guide rod), and a spot-like light source 6 (for example, an LED) disposed at one end of the light guide 4.
The Fresnel lens 2 is a linear Fresnel lens in which a plurality of prisms extending in one direction (z-axis direction) are formed on the surface on the light guide 4 side, and extends in the zx plane. The light guide 4 is made of a transparent material, extends in the z direction, and is disposed at substantially the center of the Fresnel lens 2 in the zx plane. The light guide 4 is arranged away from the Fresnel lens 2 in the y direction by the focal length f of the Fresnel lens 2. The interval between the light guide 4 and the Fresnel lens 2 is not limited to the exact focal length f, but has a width of ± 20% of the focal length f.

As shown in FIG. 1B, the light from the point light source 6 is incident on the light guide 4 and on the surface A on the Fresnel lens 2 side in the light guide 4 and the surface B facing the surface A. Reflected or reflected only on the surface B and emitted from the surface A in the y direction. Here, a plurality of prisms are formed on the surface B so that the light reflected on the surface B travels in the y direction. That is, the plurality of prisms are designed so that the light reflected on the surface B does not travel in a direction inclined in the y direction (z direction). The light emitted from the surface A in the direction inclined with respect to the y direction (z direction) is changed to the y direction using an optical path changing sheet (for example, a so-called downward prism sheet) arranged to face the surface A. You may make it progress to.
As shown in FIG. 1C, the light from the light guide 4 is refracted by a plurality of prisms provided in the Fresnel lens 2 and is emitted from the Fresnel lens 2 in the y direction. Here, the plurality of prisms are designed so that light refracted by the plurality of prisms does not travel in a direction inclined with respect to the y direction (x direction).
As is clear from FIGS. 1B and 1C, the light from the point light source 6 propagates in the z direction by the light guide 4 so that the light guide 4 emits light linearly. Further, light from the linear light guide 4 is incident on the Fresnel lens 2, so that the Fresnel lens 2 emits light in a planar shape. As a result, the illumination device 10 functions in the same manner as a planar light source. However, in this illuminating device 10, the light from the point light source 6 is not directly emitted from the illuminating device as in the conventional direct illumination device, but is spread on the zx plane by the light guide 4 and the Fresnel lens 2. Since the emitted light is emitted as substantially parallel light from the illumination device 10, it is possible to achieve uniform brightness and high brightness.

  2A shows the light distribution after passing through the light guide 4, and FIG. 2B shows the light distribution after passing through the Fresnel lens 2. FIG. 2A shows that the angular distribution of the luminous intensity in the z direction (solid line) is smaller than the luminous intensity in the x direction (broken line). That is, it can be seen that the light guide 4 narrows the light distribution in the z direction. FIG. 2B shows that the angular distribution of the luminous intensity in the x direction (broken line) is smaller than the luminous intensity in the z direction (solid line). That is, it can be seen that the Fresnel lens 2 restricts light distribution in the x direction. Thus, in the illumination device 10 of the present invention, the plurality of prisms formed on the light guide 4 controls the light distribution in the z direction of the light emitted from the light guide 4 (the light traveling in the z direction). The plurality of prisms formed on the Fresnel lens 2 controls the light distribution in the x direction of light emitted from the Fresnel lens 2 (reduces the component of light traveling in the x direction).

  As shown in FIG. 3A, the light output from the light guide 4 in the y direction decreases as the distance from the light source 6 increases (progresses in the z direction). Therefore, as shown in FIG. 3B, it is preferable to provide an optical path changing means on the surface B of the light guide 4 in order to obtain uniform output light in the z direction.

Various modified examples of the optical path changing means will be described with reference to FIG.
As shown in FIG. 4A, the optical path changing means 40 includes a light scattering portion 41 (black spot portion) that is partially roughened to form minute irregularities, and a flat portion that is not subjected to roughening. 42 (white portion). Since the light scattering portion 41 is formed with minute irregularities, the light scattering portion 41 reflects light from the light source 6 and enters the light guide 4 from one end 4t1 and is reflected by the surface B. Compared with the light beam reflected by the flat surface portion 42, the light beam transmitted through the surface A and consequently proceeds into the Fresnel lens 2 is increased.
The optical path conversion means 40 is formed so that the area of the light scattering portion 41 increases as the distance from the light source 6 increases. In this way, by forming the light scattering portion 41 in consideration of the balance between the distance from the light source 6 and the area of the light scattering portion 41 so that the amount of light passing through the surface A increases as the distance from the light source 6 increases. Even though the light source 6 is disposed at the one end 4t1, the light beam is uniformly emitted in the z direction on the surface A.

  As a roughening method for forming the light scattering portion 41, it is possible to directly process the surface B of the light guide 4 by sandblasting or the like, but the light guide 4 is made of a transparent resin material. In this case, a method of transferring the light scattering portion 41 at the same time as forming the light guide 4 by forming a fine uneven surface at a predetermined position of the mold by a method such as sandblasting or etching in advance. .

  Furthermore, a white (or milky white) paint can be applied to the light scattering portion 41 instead of roughening. The light scattering portion 41 to which the white paint is applied has a higher light beam reflectance than the flat portion 42. Therefore, the amount of light that passes through the surface A and proceeds into the Fresnel lens 2 when reflected by the light scattering portion 41. Will increase. As a method of applying the paint to the light scattering portion 41, a general coating method such as screen printing, other general printing, or spray coating can be applied.

  As shown in FIG. 4B, the shape of the light guide 4 may be formed in a wedge shape in which the cross-sectional area decreases as the distance from the light source 6 increases. That is, it is good also as a structure which arrange | positions the light source 6 in the direction of one end 4t1 with a large cross-sectional area among the both ends of the light guide 4. FIG. Such a light guide 4 can be reduced in weight because the volume of the light guide 4 can be reduced as much as the other end 4t2 side is formed thin. In such a configuration, since the surface B side is inclined with respect to the surface A, the reflection angle at the surface B of the light beam traveling inside the light guide 4 is different. That is, as the distance from the light source 6 increases, the light beam reflected by the surface B gradually proceeds in the vertical direction with respect to the opposing surface A. It is necessary to balance so as to radiate uniformly.

  The light guide 4 shown in FIGS. 4A and 4B and the like is not limited to a quadrilateral xy cross-sectional shape. For example, as shown in FIG. You may use the light guide 4 whose shape is a circle.

  As shown in FIGS. 4D and 4E, the optical path changing means 40 ′ may be constituted by a groove portion 43 having a substantially triangular cross-sectional shape and a flat portion 42 formed between the groove portions 43. Good. When the light beam that travels inside the light guide 4 and is reflected by the surface B is reflected by the groove 43, it easily travels substantially perpendicular to the surface A by the inclined surface that forms the groove 43. Compared with the case of reflecting, the amount of light transmitted through the surface A and traveling into the Fresnel lens 2 is increased. Accordingly, the ratio of the width (occupied area) of the groove 43 to the width (occupied area) of the flat portion 42 is set to gradually increase as the distance from the one end 4t1 of the light guide 4 increases. At this time, by forming the balance between the distance from the light source 6 and the occupied area of the groove 43, the light beam is emitted uniformly on the surface A even though the light source 6 is disposed at the one end 4t1. .

  In the case of the optical path changing means 40 ′ shown in FIG. 4D in order to change the ratio of the occupied area of the groove 43 and the flat part 42 as described above, the width of the flat part 42 is made constant, The width and the cutting depth are set so as to gradually increase as the distance from the light source 6 increases. On the other hand, in the case of the optical path changing means 40 ′ shown in FIG. 4 (e), the width of the groove 43 and the depth of cut are made constant, and the width of the flat portion 42 is gradually reduced.

  The groove portion 43 constituting the optical path changing means 40 ′ has a substantially triangular cross-sectional shape, but is not particularly limited thereto, the cross-sectional shape may be a substantially rectangular shape, other polygons, You may comprise by the curved surface similar to the inclination of the plane which comprises the groove part 43. FIG. Further, as the optical path changing means 40 ″ shown in FIG. 4 (f), a configuration may be adopted in which a crest portion composed of two inclined surfaces having a substantially triangular cross section is continuously formed without providing a plane portion. Good. Also in this case, in order to realize uniform light emission on the surface A, it is necessary to form it in consideration of the inclination angle, size and interval.

FIG. 5A is a perspective view of an illuminating device according to the second embodiment of the present invention, and FIG. 5B is a diagram showing an optical path changing unit of the light guide.
In the lighting device 20, the light source 6 a is disposed at one end of the light guide 4, and the light source 6 b is disposed at the other end of the light guide 4. As described above, when the two light sources 6a and 6b are arranged at both ends of the light guide 4, the optical path conversion unit 40 maximizes the area of the light scattering portion 41 near the center of the light guide 4. The light scattering portion 41 is formed so that the area of the light scattering portion 41 gradually decreases toward both ends 4t1 and 4t2, and the radiation amount of light on the surface A is made uniform. Thus, when the two light sources 6a and 6b are arranged, the luminance of the output light from the light guide 4 is substantially doubled compared to the case shown in FIG.
In the illustrated example, the light sources 6, 6 a, and 6 b are disposed away from the light guide 4, but may be disposed in contact with the light guide 4.
Although not shown, the side surfaces in the longitudinal direction (three surfaces other than the surface A) of the light guide 4 may be covered with a light reflecting member in order to guide the light beam to the Fresnel lens 2 with high efficiency. preferable.

DESCRIPTION OF SYMBOLS 2 Fresnel lens 4 Light guide 6 Light source 6a Light source 6b Light source 10 Illuminating device 20 Illuminating device 40 Optical path converting means 40 'Optical path converting means 40''Optical path converting means 41 Light scattering part 42 Planar part 43 Groove part 4t1 One end 4t2 The other end A surface Side B

Claims (3)

a Fresnel lens extending in the zx plane;
A rod-shaped light guide that is disposed away from the Fresnel lens in the y direction by the focal length f of the Fresnel lens and extends in the z direction;
At least one light source disposed at one end of the light guide;
Have
The light from the light source propagates in the z direction by the light guide,
The plurality of prisms formed on the light guide body controls light distribution in the z direction of light emitted from the light guide body,
The plurality of prisms formed on the Fresnel lens controls light distribution in the x direction of light emitted from the Fresnel lens.
A lighting device characterized by that. The light guide has a wedge shape whose cross-sectional area decreases as the distance from the light source increases.
The lighting device according to claim 1. Have two light sources,
The two light sources are disposed at both ends of the light guide,
The illumination device according to claim 1 or 2.

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