JP2013200993A - Light guide plate, lighting device, and light stand - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light guide plate, optimal for a lighting fixture, capable of effectively reducing luminance unevenness caused by an arrangement pitch of light sources and efficiently performing orientational control over the whole area of the light guide plate, in one used for a light device in which a plurality of point light sources are discretely arranged, as well as the light device using the light guide plate.SOLUTION: Luminance unevenness on a first primary surface 11 caused by an arrangement pitch of LEDs 2 can be reduced by making a first inclined surface V1A set as an anisotropic diffusion surface wherein a diffusion angle σy is larger than a diffusion angle σx.

Description

  The present invention relates to a light guide plate, an illumination device, and an illumination stand, and more particularly, to a light guide plate, an illumination device, and an illumination stand that can reduce luminance unevenness.

  2. Description of the Related Art Conventionally, a light guide that guides light emitted from a light source to a liquid crystal display panel and a backlight device that illuminates the liquid crystal display panel from the back are provided for a liquid crystal display panel such as a cellular phone. Yes. In Patent Document 1, the exit surface facing the reflection surface provided with the reflection groove is an anisotropic diffusion transmission surface, thereby increasing the light extraction efficiency to the outside of the light guide plate in the light guide process. The resulting backlight device is disclosed.

  Here, when the exit surface facing the reflection surface provided with the reflection groove is a mirror surface, the light incident from the end surface into the light guide plate is totally reflected between the opposing surfaces and spreads throughout the light guide plate, Due to the reflection groove, only the light deviating from the total reflection condition is emitted outside the light guide plate. The reflection groove mainly has a function of making the incident angle of light guided in a direction perpendicular to the light source arrangement direction smaller than the total reflection angle, and reflecting and deflecting the light from the opposite exit surface. At this time, the function of deflecting the light guide light in a direction parallel to the arrangement direction of the light sources is small, and it is difficult to efficiently emit the light outside the light guide plate. In Patent Document 1, the exit surface facing the reflective surface provided with the reflective grooves has a larger diffusivity in the direction parallel to the incident surface, that is, the light source arrangement direction, so that the light incident into the light guide plate is incident on the incident surface. A high-efficiency surface light source device is realized by emitting the light to the outside of the light guide plate before reaching the end surface facing the surface. In addition, when the point light sources are discretely arranged, the light guide plate having a large diffusivity in a direction parallel to the light source arrangement direction has an effect of reducing luminance unevenness due to the arrangement pitch of the light sources.

JP 2009-170430 A

  However, according to the technique of Patent Document 1, by providing diffusion characteristics to the plane on the exit surface side that should function as a total reflection surface, the light that is totally reflected and guided through the light guide plate is also diffused, and the light is guided. Since the light beam gradually loses its directivity, there is a problem that the control efficiency of the alignment characteristics of the emitted light decreases as the distance from the light source increases.

  The present invention has been made in view of the above circumstances, and is a light guide plate used in an illuminating device in which a plurality of point light sources are discretely arranged, and effectively prevents luminance unevenness due to the arrangement pitch of the light sources. It is an object of the present invention to provide a light guide plate that is optimal for a lighting fixture, and an illuminating device using such a light guide plate, which enables highly efficient orientation control over the entire area of the light guide plate.

The light guide plate according to claim 1 includes a plurality of light sources arranged at intervals, a reflective surface and an output surface that are substantially parallel to each other, and transmits light from the light source to the reflective surface or the output surface. On the other hand, a light guide plate used in an illumination device having a light guide plate that repeatedly guides and reflects at an angle including total reflection and emits illumination light from the exit surface,
The light guide plate is formed of a medium material having a refractive index greater than 1.4,
At least one of the reflecting surface and the emitting surface is provided with at least one light extraction means having an inclined surface inclined with respect to the reflecting surface or the emitting surface,
The light from the light source enters the light guide plate, then enters the reflection surface or the exit surface at an angle including a total reflection angle, enters the inclined surface, and then exits from the exit surface. And
At least the inclined surface of the light extraction means closest to the light source has a diffusion angle σy in a direction parallel to the arrangement direction of the plurality of light sources (however, the full width at half maximum of the intensity is the same hereinafter) σy is perpendicular to the arrangement direction It is characterized by having an anisotropic diffusion surface larger than the diffusion angle σx in any direction.

  According to the present invention, at least the inclined surface closest to the light source is an anisotropic diffusion surface in which the diffusion angle σy is larger than the diffusion angle σx, so that the emission surface is caused by the arrangement pitch of the light sources. Brightness unevenness can be reduced. At the same time, the reflection surface other than the light extraction means is a mirror surface, so that the orientation angle of the emitted light can be controlled over the entire light guide plate, and an illumination device in which the orientation is controlled with high accuracy is realized. Therefore, a light guide plate can be provided. The “mirror surface” means a surface having an average arithmetic roughness Ra of 0.2 μm or less. An anisotropic diffusion surface can be realized by combining a surface relief hologram (see paragraph [0011] of JP-A-2009-170430) or an isotropic scattering structure for hairline with a blast surface having isotropic scattering. .

  The light guide plate according to claim 2 is the invention according to claim 1, wherein the distance along the light guide direction from the light source in the reflection surface or the emission surface is L1, and the arrangement pitch of the light sources is LP. The inclined surface in a region satisfying at least LP> L1 has the anisotropic diffusion surface.

  Thereby, it is possible to realize an illumination device whose orientation is controlled with high accuracy without diffusing light more than necessary in the light source arrangement direction.

  The light guide plate according to claim 3 is the invention according to claim 1 or 2, wherein the distance along the light guide direction from the light source in the reflection surface or the emission surface is L1, and the arrangement pitch of the light sources is LP. In this case, only the inclined surface in the region satisfying LP> L1 has the anisotropic diffusion surface.

  By making the inclined surface of the region satisfying LP> L1 as the anisotropic diffusion surface, the inclined surface farther from the light source than that is an isotropic diffusion surface, so that it is more than necessary in the light source arrangement direction. It is possible to realize an illuminating device whose orientation is controlled with higher accuracy without diffusing light. The “isotropic diffusion surface” is a surface where the diffusion angle σy and the diffusion angle σx are substantially equal to each other.

  The light guide plate according to a fourth aspect of the present invention is the light-guide plate according to any one of the first to third aspects, wherein the diffusion angle σy of the anisotropic diffusion surface for each of the light extraction means decreases as the distance from the light source increases. It is characterized by that.

  As the distance from the light source increases, the luminance unevenness due to the light source pitch on the inclined surface becomes smaller. Therefore, even if the diffusion angle σy of the anisotropic diffusion surface is gradually reduced, the luminance unevenness due to the light source pitch can be sufficiently improved. . Furthermore, by not diffusing more than necessary, it is possible to realize illumination whose orientation is controlled with higher accuracy.

  The light guide plate according to claim 5 is the invention according to any one of claims 1 to 3, wherein the diffusion angle σy and the diffusion angle σx are the same in the anisotropic diffusion surfaces in all the inclined surfaces. It is characterized by being.

  By making the diffusivity of the anisotropic diffusion surface constant, the manufacturing process of the mold for forming the light guide plate is simplified.

A light guide plate according to a sixth aspect of the invention is characterized in that, in the invention according to any one of the first to fifth aspects, the following expression is satisfied.
3 <σy / σx <17 and 5 ° <σy (1)

  If the ratio (σy / σx) of the diffusion angle exceeds the lower limit value of the equation (1), the degree of diffusion in the light source arrangement direction becomes sufficient, and the luminance unevenness can be sufficiently reduced. If the diffusion angle ratio (σy / σx) is less than the upper limit of the equation (1), the balance between the diffusion of the light sources in the arrangement direction and the control of the alignment light in the vertical direction can be improved. On the other hand, if σy is larger than 5 °, the effect of diffusion as the anisotropic diffusion surface is sufficient, and the luminance unevenness can be sufficiently reduced.

  A light guide plate according to a seventh aspect of the present invention is the light-guide plate according to any one of the first to sixth aspects, wherein the light extraction means includes the inclined surface formed on the reflective surface and inclined with respect to the reflective surface. It has at least two inclined surfaces, and the light reflected by the inclined surface is incident on the exit surface at an angle smaller than the total reflection angle.

  Since the light that has been guided is reflected and deflected by the inclined surface formed on the reflective surface, the incident angle control of the light incident on the output surface is easy, and the light distribution control of the output light can be effectively performed. The light can be reliably guided in the desired illumination direction.

  According to an eighth aspect of the present invention, in the light guide plate according to the seventh aspect of the invention, the light extraction means is a V groove formed on the reflecting surface, and the slope of the V groove is the inclined surface. Features.

  By providing the V-groove in this way, illumination light can be distributed with high efficiency within a range of about θmax <30 °, where θmax is the angle of the maximum intensity peak of the emitted light with respect to the normal direction of the emission surface. Light control.

  The light guide plate according to a ninth aspect includes the light guide plate according to any one of the first to sixth aspects, wherein the light extraction unit includes the inclined surface formed on the emission surface and inclined with respect to the emission surface. It has at least two slopes.

  By providing the inclined surface on the exit surface, it is easy to control the incident angle of the light incident on the exit surface, the light distribution control of the exit light can be performed effectively, and the light can be reliably emitted in a desired illumination direction. Further, since the light is refracted by the inclined surface provided on the emission surface, the Fresnel reflection on the inclined surface is reduced, and the light can be emitted with high efficiency in a direction greatly inclined from the normal direction of the emission surface.

  The light guide plate according to claim 10 is the invention according to claim 9, wherein the light extraction means is a convex portion formed on the emission surface, and the inclined surface of the V groove is the inclined surface. Features.

  By providing the convex portions in this way, illumination light is distributed with high efficiency within a range of about θmax> 30 °, where θmax is the angle of the maximum intensity peak of the emitted light with respect to the normal direction of the emission surface. Light control is possible.

  A light guide plate according to an eleventh aspect is the light-guide plate according to any one of the first to tenth aspects, wherein light emitted from the emission surface is predetermined in a direction away from the light source with respect to a normal line of the emission surface. It travels in an inclined state.

  Even if the lighting device is not arranged directly above the desired range, it is possible to provide a lighting device with a high degree of freedom of arrangement that can be uniformly irradiated.

  The illuminating device of Claim 12 has the light-guide plate in any one of Claims 1-11, It is characterized by the above-mentioned.

  Accordingly, it is possible to provide an illuminating device that can perform light distribution control with high efficiency, has little luminance unevenness (glare) when observed with the user's line of sight, and can illuminate an oblique direction.

  The illuminating device according to a thirteenth aspect of the invention of the twelfth aspect includes a plurality of point light sources arranged at predetermined intervals along an end surface intersecting the reflection surface and the emission surface. Features.

  In the lighting device, an LED or the like that can save power can be used as the point light source, but the illuminance may be low if it is single. Therefore, it is possible to increase the illuminance by using a plurality of point light sources, and furthermore, by mixing the light emitted from the plurality of point light sources with the light guide plate, it is possible to emit illumination light with less illuminance unevenness. Further, the lighting device can be thinned by arranging the plurality of light sources along an end surface intersecting the reflection surface and the emission surface.

  According to a fourteenth aspect of the present invention, in the invention according to the twelfth or thirteenth aspect, a reflective plate is provided adjacent to the reflective surface of the light guide plate.

  Although a small amount of light may leak from the reflecting surface, the light is reflected from the reflecting plate to be emitted from the emitting surface, thereby providing an illumination device with higher light extraction efficiency. .

  The illuminating device according to claim 15 is characterized in that, in the invention according to any one of claims 12 to 14, a diffusion plate is provided adjacent to the emission surface of the light guide plate.

  By transmitting the light emitted from the emission surface through the diffusion plate, the emitted light can be appropriately spread and illuminated over a wide range, and luminance unevenness can be further reduced.

  A lighting stand according to a sixteenth aspect includes the lighting device according to any one of the twelfth to fifteenth aspects.

  Since it is possible to illuminate a direction that is greatly inclined from the normal direction of the emission surface, it is possible to provide an illumination stand that can illuminate the user's head brightly without getting in the way. However, you may use the illuminating device of this invention for step illumination. In such a case, since the floor direction greatly inclined from the wall surface can be illuminated, the feet are bright, the user standing on the floor is not dazzled, and the wall surface position can be recognized, which is preferable for night safety.

  According to the present invention, a light guide plate used in an illumination device in which a plurality of point light sources are arranged in a discrete manner, which effectively reduces luminance unevenness due to the arrangement pitch of the light sources, and at the same time, over the entire light guide plate. It is possible to provide a light guide plate that is most suitable for a lighting fixture and enables a highly efficient orientation control, and a lighting device using such a light guide plate.

It is a schematic sectional drawing which shows the outline | summary of the illuminating device which concerns on this invention. FIG. 3 is an explanatory enlarged sectional view showing only a part of the LED 2 and the light guide plate 1. FIG. 3 is an explanatory enlarged sectional view showing only a part of the LED 2 and the light guide plate 1. It is a schematic sectional drawing which shows the light-guide plate with which the illuminating device of FIG. 1 is provided. It is the figure which looked at the direction which cut | disconnected the structure of FIG. 1 by the VV line. It is the figure which calculated | required the brightness | luminance of the 1st main surface of a comparative example by simulation, and represents the maximum brightness | luminance in white and the minimum brightness | luminance in black. It is explanatory drawing which shows the direction of the maximum intensity illumination light of the illuminating device of a comparative example. It is a figure which shows typically the light diffused anisotropically by the light-guide plate. It is the figure which calculated | required the brightness | luminance of the 1st main surface of 1st embodiment by simulation, and represents the maximum brightness | luminance in white and the minimum brightness | luminance in black. It is explanatory drawing which shows the direction of the maximum intensity illumination light of the illuminating device of 1st embodiment. It is the figure which calculated | required the brightness | luminance of the 1st main surface of 2nd embodiment by simulation, and represents the maximum brightness | luminance with white and the minimum brightness | luminance. It is explanatory drawing which shows the direction of the maximum intensity illumination light of the illuminating device of 2nd embodiment. It is a schematic sectional drawing which shows the light-guide plate of 3rd embodiment. It is the figure which calculated | required the brightness | luminance of the 1st main surface of 3rd embodiment by simulation, and the maximum brightness | luminance is represented by white and the minimum brightness | luminance is represented by black. It is a figure which shows the angle characteristic of the illumination light intensity of the illuminating device of 3rd embodiment. 10 is a schematic cross-sectional view showing a light guide plate of Modification 1. FIG. 10 is a schematic cross-sectional view showing a light guide plate of Modification 2. FIG. It is a schematic sectional drawing which shows the outline | summary of the illuminating device using the light-guide plate of 4th embodiment. It is a schematic sectional drawing which shows the light-guide plate of 4th embodiment. It is the figure which calculated | required the brightness | luminance of the 1st main surface of 4th embodiment by simulation, and is a gray scale which represented the maximum luminance in white and the minimum luminance in black. It is a figure which shows the angle characteristic of the illumination light intensity of the illuminating device of 4th embodiment. It is sectional drawing which shows light-guide plate 1D concerning the modification 3 with LED2. It is a schematic explanatory drawing which shows the outline | summary of the illumination stand which concerns on this invention. It is a schematic plan view which shows the illumination intensity distribution of the to-be-irradiated surface by the illumination stand of FIG.

  Embodiments of the present invention will be described below with reference to the drawings. Moreover, the same code | symbol is used about the same structural member, and detailed description is abbreviate | omitted suitably.

  The illuminating device according to the present invention is an illuminating device U having an irradiation surface that emits surface light. For example, as shown in FIG. 1, a first main surface (outgoing surface) 11 that emits surface light, and the first The light guide plate 1 having a second main surface (reflective surface) 12 that faces the main surface and extends substantially in parallel, and extends in a direction intersecting the first main surface 11 and the second main surface 12. A plurality of light-emitting elements 2 disposed to face one side surface (an end face on the light source side) serving as the incident surface 13 of the light plate 1, and the light emitted from the light-emitting elements 2 is transmitted into the light guide plate 1. It is the illuminating device U for lighting fixtures light-guided to and inject | emitted from the 1st main surface 11. The first main surface (outgoing surface) 11 is preferably used substantially parallel to the second main surface (reflecting surface) 12, but the same effect can be obtained even when the first main surface (outgoing surface) 11 deviates from parallel by about 5 degrees. . In other words, “substantially parallel” in the claims includes a case where they are inclined to each other within 5 degrees.

  The light guide plate 1 has a flat plate shape whose longitudinal direction is perpendicular to the paper surface, and is configured to be integrally accommodated in the case 3 together with the light emitting element 2 so as to expose the first main surface 11.

  The light emitting elements 2 may be any light source that emits illumination light in the direction of the incident surface 13, and are arranged at a predetermined pitch LP in a row in the longitudinal direction of the incident surface 13 (the direction perpendicular to the paper in FIG. 1). A plurality of point light sources (LEDs) are used. Further, it is preferable to use an LED that emits white light with low power consumption and high emission intensity. Therefore, in the present embodiment, a white LED is used. Therefore, it replaces with the light emitting element 2, and demonstrates from now on as LED2. A plurality of LEDs 2 are arranged at substantially equal intervals (for example, LP = about 15 mm pitch) in the longitudinal direction (direction perpendicular to the paper surface) of the substrate 21 accommodated in the case 3.

  The LED 2 is a white LED, and emits white light by combining a blue LED and a phosphor (for example, a yellow phosphor) that is excited by light from the blue LED and emits excitation light having a predetermined wavelength. The white LED may be a high color rendering LED that is a combination of a red LED, a blue LED, and a green LED. By using the high color rendering LED, it is possible to realize an illumination device suitable for an application requiring high color reproducibility.

  For example, the substrate 21 has a length approximately equal to the entire width in the longitudinal direction of the incident surface 13, and a plurality of chip-type LEDs 2 are mounted on the substrate 21 at a predetermined pitch. Thus, although the board | substrate 21 is united in the longitudinal direction, it is good also as a structure which divides | segments into several board | substrates and each is electrically connected. The substrate 21 is connected to a power supply circuit (not shown) arranged outside the lighting device by a lead wire, and the brightness of the lighting device is adjusted by adjusting a current flowing through the LED by a brightness adjustment button provided in the electric circuit. The height can be adjusted.

  2 and 3 are enlarged sectional views for explanation showing only the LED 2 and a part of the light guide plate 1. In FIG. 2, the incident surface 13 has a V-shaped groove shape, and has a first deflection plane 13 a and a second deflection plane 13 b that are inclined so as to approach the outer peripheral side of the LED 2 with the center in the thickness direction of the light guide plate 1 as a boundary. Therefore, the light emitted from the upper half of the LED 2 is refracted by the first deflection plane 13a and travels toward the second main surface 12, and the light emitted from the lower half of the LED 2 is refracted by the second deflection plane 13b. Then, it is directed to the first main surface 11.

  Here, the inclination angle θ of the first deflection plane 13a and the second deflection plane 13b is desirably up to 20 degrees. When the inclination is greater than 20 degrees, the high intensity light emitted from the LED 2 does not become a total reflection component on the first main surface 11 and the second main surface 12 and is emitted at a position close to the LED 2. Light extraction efficiency deteriorates. In addition, by tilting the first deflection plane 13a and the second deflection plane 13b by 20 degrees, the low-intensity light emitted from the LED 2 at a radiation angle of 70 degrees (cosine 0.34) is incident and incident on the incident plane 13 Fresnel reflection is relatively small at an angle of 50 degrees.

  On the other hand, from another viewpoint, the inclination angle θ of the first deflection plane 13a and the second deflection plane 13b is preferably equal to or greater than an angle of atan (t / (2L)). Here, with reference to FIG. 5, the thickness of the light guide plate is t (mm), and the distance from the incident surface 13 to the end surface opposite to the incident surface of the light guide plate 1 is L (mm). When t = 3 and L = 55, by setting atan (t / (2L)) = 1.5 degrees or more, there is no guided light that directly reaches the end surface opposite to the incident surface 13, and high intensity light is emitted. Since the light can be extracted as far as possible by being guided to the light extraction means 15 as the light extraction means, it is possible to prevent loss due to light guide reciprocation and flare light.

  Furthermore, it is preferable that all light beams (excluding edge diffracted light) incident from the first deflection plane 13a and the second deflection plane 13b are incident on the first main surface 11 and the second main surface 12 that are incident first at a total reflection angle. . When the light guide plate 1 is formed of a material having a refractive index of 1.5, the refracted all incident light beams are refracted at the inclination angle θ of the first deflection plane 13a and the second deflection plane 13b of 6 ° or less and the first main surface 11 and the first deflection plane 13b. Two total reflections will occur at the main surface 12. However, as described above, it is desirable that the first deflection plane 13a and the second deflection plane 13b are inclined at an inclination angle θ = 1.5 degrees or more. The incident surface 13 may be a flat surface.

  The light emitted from the LED 2 enters from the incident surface 13 and is guided through the light guide plate 1. That is, light is guided between the lower surface (first main surface 11) and the upper surface (second main surface 12) of the light guide plate 1 while being totally reflected, enters the light extraction means 15, and deviates from the total reflection angle. The emitted light is emitted from the first main surface 11 to emit light.

  In this embodiment, the light extraction unit 15 emits strong light in an inclined direction different from the normal direction toward the main surface (first main surface 11) that emits the illumination light of the light guide plate 1 when performing surface emission. Is possible.

More specifically, a light extraction means 15 is provided on either the first main surface 11 or the second main surface 12, and the light extraction means 15 is used to deflect a predetermined angle from the perpendicular direction of the first main surface 11. The illumination light is emitted. Referring to FIG. 3, the angle θ _MAX formed by the perpendicular of the first main surface 11 and the maximum intensity direction of the emitted light preferably satisfies 10 ° <θ _MAX <40 °, as will be described later. More preferably, 15 ° <θ _MAX <35 °.

  The light extraction means 15 shown in FIG. 3 employs a plurality of V grooves provided in the second main surface 12 and extending in the direction perpendicular to the paper surface. With this configuration, the light extraction means 15 is provided on the second main surface 12 opposite to the exit surface, so that the illuminance distribution can be made uniform and the illuminance distribution at the exit surface position can be made more uniform. Can be.

The V groove constituting the light extraction means 15 has a first inclined surface V1A (inclined surface) on the incident surface side and a second inclined surface (connecting surface) V2A that forms the V groove together with the first inclined surface V1A. By changing the inclination angle between the first slope V1A and the second slope V2A, the direction of the maximum peak intensity light of the illumination light deflected by a predetermined angle θ _MAX from the normal direction of the first main surface 11 is adjusted. Can do. In addition, the illumination light as used in this application means the light which is taken out of the illuminating device U and contributes to illumination. When the light emitted to the outside of the light guide plate is blocked by the case 3, the light is not illumination light.

  It is desirable to determine the positional relationship between the light extraction means 15 closest to the LED 2 and the case 3 so that the light emitted to the outside of the light guide plate by the light extraction means 15 closest to the LED 2 is not blocked by the case 3. This is because the light from the LED 2 is efficiently taken out without being blocked by the case 3. When the light extraction means 15 is provided at a position where light emitted from the light extraction means 15 to the outside of the light guide plate is blocked by a part of the case 3, such light extraction means 15 is used for illumination of the illumination device U. Does not contribute. Therefore, the light extraction means 15 described below in this application refers to what emits the light from the LED 2 so as not to be blocked by the case 3. For example, when there is a light extraction means 15 closest to the LED 2 and a light extraction means 15 closest to the second, and the light from the closest light extraction means 15 is blocked by the case 3, the light extraction means 15 closest to the LED 2 is The term above refers to the second light extraction means closest to the LED 2.

  Here, the light guide plate 1 is made of a transparent material that transmits visible light (for example, PMMA having a refractive index of about 1.5: acrylic), and is formed by additionally processing a V-groove-shaped light extraction means 15. Alternatively, it can be molded integrally. In addition, the light guide plate 1 may be a glass material, acrylic other than PMMA, polycarbonate, a silicon resin sheet having plasticity, or the like depending on applications.

  The reflecting plate 4 may be made of a resin plate having a mirror treatment or a mirror film attached to the inner surface thereof, an aluminum sheet metal having a reflecting surface subjected to white coating white reflection treatment or mirror treatment, or the like. Moreover, you may form the inner surface of case 3 which accommodates the light-guide plate 1 as a reflective surface which gave the white reflection process and the mirror process of the white coating to the aluminum sheet metal, for example, and a reflective film (for example, Kimoto company make) (Ref white) may be used.

  In addition, the diffusion plate 5 is disposed outside the first main surface 11. With this configuration, even if the light extraction means 15 is composed of a plurality of V grooves that are discretely arranged, the illuminance unevenness (luminance unevenness) of the illumination light on the exit surface (first main surface 11) is reduced. Thus, it is possible to realize a high-quality lighting device U that is uniform and easy on the eyes. The diffusion plate 5 may be a conventionally known resin diffusion plate or resin diffusion film having translucency.

  According to the present embodiment, the light beam emitted from the LED 2 is guided while being totally reflected between the first main surface 11 and the second main surface 12, reflected and diffused by the light extraction means 15, and the total reflection angle. The light beam deviated from the first main surface 11 is emitted as illumination light. Here, by disposing the reflection plate 4 outside the second main surface 12, the light deflected by the light extraction means 15 and leaked outside the second main surface 12 is reflected and again enters the light guide plate 1. The intensity of illumination light emitted from the first main surface 11 can be increased, and a highly efficient illumination device U can be realized.

  By the way, when the incident surface 13 is a mirror surface, the light emitted from the first inclined surface V1A provided within a range where the distance from the incident surface 13 is equal to or less than the arrangement pitch LP of the LEDs 2 is sufficiently uniformed in the arrangement direction. Therefore, the first main surface 11 may be observed as uneven brightness.

  Here, as a comparative example, the light emitting surface is observed from the front when the diffusion angles of the first inclined surface V1A of the V groove serving as the light extraction means all have isotropic diffusion characteristics of σx = 5 ° and σy = 5 °. FIG. 6 shows an image of the luminance distribution at the time. The luminance distribution image is expressed in gray scale with the maximum luminance being white and the luminance being 0 being black.

  The upper side of FIG. 6 is the incident surface 13, that is, the side on which the light sources are arranged. As shown in FIG. 6, the bright line resulting from the pitch LP of the light source is clearly confirmed. In addition, FIG. 7 shows angular intensity characteristics of the illumination device of this comparative example. RA is an angular intensity characteristic of a cross section perpendicular to the arrangement direction of the light sources, and RB is an angular intensity characteristic of a cross section parallel to the arrangement direction of the light sources. In the cross section indicated by RA, it can be seen that the orientation is controlled so as to have the maximum intensity in the direction of θmax = 22.5 °.

  On the other hand, in the present embodiment, as shown in FIG. 8, all the first slopes V1A of the V-groove serving as the light extraction means reflect the arrangement direction of the LEDs 2, that is, the light reflected from the first slope V1A. When the diffusion angle in the Y direction (full width at half maximum) σy parallel to the incident surface 13 is σy and the diffusion angle in the direction perpendicular to the incident surface 13 is σx, σy = 15 °, σx = 1 Has a diffusion angle of °. When the distance from the LED 2 in the light guide direction is L1 and the arrangement pitch of the LEDs 2 is LP, only the first slope V1A in the region satisfying LP> L1 may have an anisotropic diffusion surface. good.

  FIG. 9 shows a luminance distribution image on the first main surface 11 according to the present embodiment. Conditions other than the diffusion angle are the same as in the comparative example described above. It can be seen that even at a position close to the LED 2, luminance unevenness due to the arrangement pitch of the light sources is reduced, and a strong luminance peak disappears. Further, by eliminating the sharp luminance peak, the user does not feel strong glare even when the user directly observes the light emitting surface. Further, FIG. 10 shows angular luminance characteristics as the illumination device U when the light guide plate 1 is used. Although the luminance unevenness can be reduced, it can be confirmed that the orientation characteristics are sufficiently secured.

Next, a second embodiment will be described. In the present embodiment, when the distance between the incident surface 13 and the V groove is L1, and the arrangement pitch of the LEDs 2 is LP,
(1) The diffusion angle of the first slope V1A in the range of L1 <LP is σy = 15 °, σx = 1 °
(2) The diffusion angle of the first slope V1A with LP <L1 <2LP is σy = 10 °, σx = 5 °
(3) The diffusion angle of the first slope V1A in the range of L1> 2LP is σy = 5 °, σx = 5 °
It is said. Other configurations are the same as those of the above-described embodiment.

  FIG. 11 shows a luminance distribution image on the first main surface 11 according to the present embodiment. Further, FIG. 12 shows angular luminance characteristics as the illumination device U when the light guide plate 1 is used. By increasing the diffusivity in the light source array direction of the V-groove closer to the first entrance surface and gradually decreasing the diffusivity in the region where unevenness due to the LED array pitch is reduced, unnecessary diffused light is reduced. The orientation can be controlled efficiently. Moreover, it turns out that the brightness nonuniformity in the whole light emission surface can also be reduced compared with 1st embodiment. However, the diffusion angle σy may be changed for one or a plurality of the first inclined surfaces V1A. Further, 3 <σy / σx <17 and 5 ° <σy may be satisfied.

  Next, a third embodiment in which the density of V grooves provided on the second main surface of the light guide plate increases as the distance from the incident surface 13 increases will be described with reference to FIGS. The illumination device of the third embodiment is different in that the light guide plate 1A of the illumination device U of the first embodiment described above is replaced with a light guide plate 1B, and the other configurations are the same. Therefore, in FIG. 13, only the light guide plate 1B is displayed as the main configuration of the illumination device.

  As shown in FIG. 13, the light guide plate 1 </ b> B included in the illumination device of the third embodiment has an angle θv <b> 1 formed by the first inclined surface V <b> 1 and the perpendicular of the second main surface 12 of 60 °, and the second inclined surface V <b> 2 and the second inclined surface V <b> 2. There is provided light extraction means 15B composed of a V-groove having an angle θv2 formed with a perpendicular to the main surface 12 of 30 °. The shape of the V groove is the same throughout.

  That is, the V-groove provided on the second main surface 12 of the light guide plate 1B is asymmetric with respect to the normal of the second main surface 12, and the angle between the first inclined surface V1 and the second inclined surface V2 and θv1 + θv2 is 90 °. It is an example. In the present embodiment, the pitch of the V-groove decreases as the distance from the incident surface 13 increases. The diffusion angles of the V grooves are all σy = 15 ° and σx = 3 °. As can be seen from the luminance distribution image shown in FIG. 14, luminance unevenness in the direction perpendicular to the incident surface 13 can be reduced by gradually reducing the V groove pitch. In addition, as can be seen from the angular luminance characteristics shown in FIG. 15, the orientation is controlled efficiently.

  FIG. 16 is a view similar to FIG. 13 of the light guide plate 1B according to the first modification. According to this modification, the pitch of the V groove as the light extraction means 15B is constant as in the second embodiment, but the V groove shape is similar and gradually increases as the distance from the light source increases. The diffusion angles of the V grooves are all σy = 15 ° and σx = 3 °. If the density change per unit area of the V-groove is configured to be equivalent to that of the third embodiment, substantially the same effect can be obtained.

  FIG. 14 is a view similar to FIG. 13 of the light guide plate 1B according to the second modification. According to this modification, the pitch of the V-groove as the light extraction means 15B gradually decreases as the distance from the light source increases, and the V-groove shape gradually increases as the distance from the light source increases. . The diffusion angles of the V grooves are all σy = 15 ° and σx = 3 °. If the density change per unit area of the V-groove is configured to be equivalent to that of the third embodiment, substantially the same effect can be obtained.

  Next, although the pitch and size of the light extraction means 15D are fixed, a fourth embodiment provided on the first main surface of the light guide plate will be described with reference to FIGS. The illumination device U1 of the fourth embodiment is as shown in FIG. 18, and a description thereof is omitted using common reference numerals.

  FIG. 19 is a cross-sectional view showing the light guide plate 1 according to the fourth embodiment. In the present embodiment, a V-groove as the light extraction means 15D is provided on the first main surface 11 side. Referring to FIG. 19, the inclination angle θv1 ′ of the first inclined surface (inclined surface) V1B of the V-groove is 30 degrees, and the inclination angle θv2 ′ of the second inclined surface V2B is 60 degrees. Other configurations are the same as those of the above-described embodiment.

  In the present embodiment, the V grooves as the light extraction means 15D are arranged at an equal pitch from the incident surface 13 side. Also, σy = 15 ° and σx = 3 °. FIG. 20 shows a luminance distribution image on the first main surface 11 of the present embodiment. By arranging the V-groove as the light extraction means 15D near the diffusion plate 5 adjacent to the first main surface 11, the luminance unevenness due to the arrangement pitch of the LEDs 2 tends to increase, but as shown in FIG. In addition, it can be seen that the generation of sharp bright lines is suppressed by making the V groove surface an anisotropic diffusion surface. Further, as can be seen from the angle luminance characteristics shown in FIG. 21, the angle intensity characteristics are characteristic when the V-groove is arranged on the light emitting surface side, and the angles θmax = 22.5 ° and θmax ′ = 53 ° from the direct downward direction are characteristic. It can be seen that it has a double peak and is well controlled in orientation.

  The light emitted from the upper half of the LED 2 is refracted by the first deflection plane 13a toward the second main surface 12, and the light emitted from the lower half of the LED 2 is refracted by the second deflection plane 13b. After being guided through the light guide plate 1 so as to be directed to the first main surface 11, the total reflection is broken and transmitted by entering the first inclined surface V <b> 1 </ b> B, and emitted from the first main surface 11 as illumination light. .

  FIG. 22 is a cross-sectional view showing the light guide plate 1 </ b> D according to the modified example 3 together with the LEDs 2. In the present modification, a convex portion 15 </ b> D ′ as a light extraction unit is formed to protrude from the first main surface 11. The convex portion 15D 'includes a slope S1 on the light source side and a slope (inclined surface) S2 on the opposite side. The slope angle γ of the slope S2 is 30 degrees. Other configurations are the same as those of the above-described embodiment. Such a convex portion 15D 'can be transferred if a concave portion is formed in the mold, so that it can be easily manufactured and can be realized at low cost.

  In FIG. 22, the light emitted from the upper half of the LED 2 is refracted by the first deflection plane 13a toward the second main surface 12, and the light emitted from the lower half of the LED 2 is the second deflection plane 13b. After being guided through the light guide plate 1D so as to be refracted at the first principal surface 11 and then incident on the inclined surface S2, the light flux that is reflected and diffused and deviates from the total reflection angle is reflected on the first principal surface 11. Is emitted as illumination light. At this time, the light reflected by the second main surface 12 travels in the direction along the slope S1, so that it does not easily become a shadow, and the light extraction efficiency can be increased. In this modification, it is possible to emit high-intensity light having an intensity peak at an angle of θ = 53 degrees in a direction away from the light source with respect to the normal line of the first main surface 11.

  Table 1 summarizes the specifications of each embodiment and modification.

  The lighting devices U and U1 applied to the above-described embodiments can be suitably applied to lighting fixtures such as a lighting lamp for a sink and a lighting stand. Therefore, the illumination stand which is a lighting fixture provided with the illuminating device U of this 1st embodiment is demonstrated using FIGS. 23-24.

  A lighting stand ST1 shown in FIG. 23 is a lighting fixture using the lighting device U. Moreover, the base part 31 and the support | pillar 32 are provided, the illuminating device U is mounted | worn with the front end side of this support | pillar 32, and the 1st main surface 11 which light-emits the surface of this illuminating device U is substantially parallel to a to-be-illuminated surface (desk upper surface). It is installed in.

As described above, the illuminating device U shows the illumination light distribution in which the portion inclined by a predetermined angle toward the user side shows the maximum intensity, so that the user (observer 40) as shown by the angle θ _MAX in the figure. The maximum intensity illumination light is emitted in a direction inclined to the side. Further, the reflected light RF reflected from the desk surface 30 enters the eyes of the observer 40.

  FIG. 24 shows an image of the illuminance distribution on the desk top surface when the distance H between the first main surface 11 of the lighting device U and the desk top surface is 400 mm.

  As shown in FIG. 24 in which the degree of brightness is displayed in shades, the illuminance in the vicinity immediately below the illumination device U of the illumination stand ST1 is high. In addition, the front side (the + side of the x axis) has an asymmetric illumination distribution with higher illuminance than the back side of the desk (the − side of the x axis).

  That is, even if the illumination stand ST1 is arranged in the back of the desk, and the emission surface (first main surface 11) of the illumination device U is arranged in parallel to the desk surface, the maximum intensity illumination light is on the viewer 40 side. Because it is tilted to the side, you can illuminate your hand sufficiently brightly.

  The illuminance distribution of the illuminance Ry on the y-axis is substantially symmetric with respect to the origin, but the illuminance distribution of the illuminance Rx on the x-axis is asymmetric and is a positive (+) region, that is, on the observer side. It can be seen that the region is illuminated brighter than the negative (−) region of x, that is, the back side of the illumination stand ST1.

  Therefore, by using the illumination device according to the present embodiment, a highly efficient lighting apparatus that illuminates the illuminated area over a wide area and reduces unnecessary illumination light to an area that does not require illumination is realized. be able to.

  As described above, even if the illuminating devices U and U1 provided with the light extraction means 15 are used and the illuminating devices U and U1 are installed in the back of the illuminated region, the illuminated region on the near side is efficiently used. It is possible to obtain a luminaire that can illuminate well, that is, a luminaire that can efficiently illuminate a hand while having low power consumption.

  Further, an illumination stand having a configuration in which the illumination devices U and U1 according to the present embodiment are mounted and the first main surface 11 emitting surface light of the illumination device is installed in parallel with the surface to be illuminated is used. Even if the lighting device is installed in the back of the illuminated area and the first main surface is substantially parallel to the desk surface, the illuminated area on the near side of the user can be efficiently illuminated. That is, it is possible to obtain an illumination stand that can illuminate the hand efficiently while having low power consumption.

  As described above, since the illuminating device according to the present invention has the diffuser plate arranged outside the first main surface, the illuminance unevenness of the illumination light on the exit surface even if the light extraction means are discretely arranged. (Brightness unevenness) can be reduced, and a high-quality lighting device that is uniform and easy on the eyes can be realized. Further, since the light from the light emitting element (LED) is deflected by a predetermined angle through the light extraction means and irradiated as illumination light, the light is strong in a direction different from the direction of the main surface emitting the illumination light of the light guide plate. It has a light distribution characteristic capable of irradiating light. Therefore, by using the light guide plate, the lighting device is suitable for a lighting fixture and a lighting stand that can illuminate a hand efficiently while being thin and lightweight and having low power consumption.

  Therefore, the lighting device according to the present invention can be suitably applied to lighting fixtures, lighting stands, foot lighting, and the like that are required to efficiently illuminate a predetermined direction.

1-1D Light guide plate 2 Light emitting element (LED)
DESCRIPTION OF SYMBOLS 3 Case 4 Reflecting plate 5 Diffusing plate 11 1st main surface 12 2nd main surface 13 Incident surface 14 End surface 15-15D Light extraction means 16 Light beam branching part V1A 1st slope V2A 2nd slope U Lighting device ST1 Lighting stand (lighting fixture) )

Claims (16)

A plurality of light sources arranged at intervals, a reflective surface and an output surface that are substantially parallel to each other, and light from the light source is incident on the reflective surface or the output surface at an angle including total reflection. A light guide plate used in an illumination device having a light guide plate that guides light while repeating reflection and emits illumination light from the emission surface,
The light guide plate is formed of a medium material having a refractive index greater than 1.4,
At least one of the reflecting surface and the emitting surface is provided with at least one light extraction means having an inclined surface inclined with respect to the reflecting surface or the emitting surface,
The light from the light source enters the light guide plate, then enters the reflection surface or the exit surface at an angle including a total reflection angle, enters the inclined surface, and then exits from the exit surface. And
At least the inclined surface of the light extraction means closest to the light source has a diffusion angle σy in a direction parallel to the arrangement direction of the plurality of light sources (however, the full width at half maximum of intensity is the same hereinafter) σy is perpendicular to the arrangement direction A light guide plate having an anisotropic diffusion surface larger than a diffusion angle σx in any direction.   When the distance along the light guide direction from the light source in the reflection surface or the emission surface is L1, and the arrangement pitch of the light sources is LP, the inclined surface in a region satisfying at least LP> L1 is the anisotropic diffusion. The light guide plate according to claim 1, further comprising a surface.   3. The light guide plate according to claim 1, wherein only the inclined surface in a region satisfying LP> L <b> 1 has the anisotropic diffusion surface.   4. The light guide plate according to claim 1, wherein the diffusion angle σy of the anisotropic diffusion surface for each light extraction unit decreases as the distance from the light source increases.   The light guide plate according to claim 1, wherein the diffusion angle σy and the diffusion angle σx are the same in the anisotropic diffusion surfaces in all the inclined surfaces. The following formula is satisfy | filled, The light-guide plate in any one of Claims 1-5 characterized by the above-mentioned.
3 <σy / σx <17 and 5 ° <σy (1)   The light extraction means has at least two inclined surfaces including the inclined surface that is formed on the reflective surface and is inclined with respect to the reflective surface, and the light reflected by the inclined surface is less than a total reflection angle. The light guide plate according to claim 1, wherein the light guide plate is incident on the exit surface.   The light guide plate according to claim 7, wherein the light extraction unit is a V-groove formed on the reflection surface, and an inclined surface of the V-groove is the inclined surface.   7. The light guide according to claim 1, wherein the light extraction means has at least two inclined surfaces including the inclined surface formed on the emission surface and inclined with respect to the emission surface. Light board.   The light guide plate according to claim 9, wherein the light extraction unit is a convex portion formed on the emission surface, and an inclined surface of the V groove is the inclined surface.   11. The light according to claim 1, wherein the light emitted from the emission surface travels at a predetermined angle with respect to a normal line of the emission surface in a direction away from the light source. Light board.   An illuminating device comprising the light guide plate according to claim 1.   The lighting device according to claim 12, further comprising: a plurality of point light sources arranged at a predetermined arrangement pitch along an end surface intersecting the reflection surface and the emission surface.   The lighting device according to claim 12, wherein a reflecting plate is provided adjacent to the reflecting surface of the light guide plate.   The illuminating device according to claim 12, wherein a diffusion plate is provided adjacent to the emission surface of the light guide plate.   An illumination stand comprising the illumination device according to claim 12.