JP2012204219A - Lighting device and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a lighting device equipped with a light source with directivity at a rear-face side of a light-emitting face to uniformly emit light on nearly a whole area of the light-emitting face.SOLUTION: A dot pattern (a light-scattering part) is formed which makes part of scattered light emitted from a surface side of a light guide plate 13 and scatters part of light propagated in an in-face direction inside the light guide plate 13 so that a degree of scattering in a first region is to be smaller than that in a second region where a light guide volume is smaller than in the first region, out of regions in an in-face direction in the light guide plate 13.

Description

  The present invention relates to an illumination device that emits light from a light source in a planar shape by a light guide plate, and a method for manufacturing the same.

  In recent years, LEDs (Light Emitting Diodes) having characteristics of lower power consumption and longer life than conventional light sources such as incandescent bulbs and fluorescent lamps are used as light sources provided in lighting devices such as light bulbs and ceiling lights. It is used a lot.

  For example, Patent Literature 1 discloses a ceiling light in which LED light sources are arranged in substantially the entire light emitting surface. Patent Document 2 discloses a liquid crystal display device in which LED light sources serving as backlights are arranged over substantially the entire region that overlaps the display surface.

JP 2010-140797 A (published on June 24, 2010) JP 2006-49324 A (published February 16, 2006)

  However, in the techniques of Patent Documents 1 and 2, since the light emitted from the LED light source has strong directivity, the difference in the amount of light between the position where the LED light source is disposed and the position where it is not disposed becomes significant. There is a problem that light cannot be emitted uniformly over the entire light emitting surface.

  In the technique of Patent Document 2, a light reflection groove is provided in a light guide plate disposed immediately above the light emitting diode, and light from the light emitting diode is returned to the light guide plate by the light reflection groove to be supplied to the display device. The homogenized light is made uniform. However, in this configuration, it is difficult to accurately form the light reflection groove so that the light from the light emitting diode is totally reflected in the light guide plate, and thus the light supplied to the display device cannot be sufficiently uniformized. Further, in the technique of Patent Document 2, since it is necessary to provide the light reflection groove with high accuracy in the light guide plate, there is a problem that the manufacturing cost increases.

  Further, like a so-called side-edge type backlight used in the field of liquid crystal display devices, the LED light source is arranged at the periphery of the light emitting surface, and the light from the LED light source is arranged in parallel to the light emitting surface. It is conceivable to make the light emission amount uniform over the entire light emitting surface by making the light incident on the light guide plate to emit light. However, in this configuration, since it is necessary to arrange a light source at the peripheral portion of the light emitting surface, there is a problem that the size of the lighting device is increased. In particular, when it is necessary to consider the thermal expansion of the light guide plate, it is necessary to provide a clearance between the light guide plate and the light source in order to prevent contact between the light source and the light guide plate due to the thermal expansion of the light guide plate. As a result, the lighting device is further increased in size and the light utilization efficiency is reduced.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a lighting device including a light source that emits light having directivity on the back side of a light emitting surface. It is to emit light uniformly.

  In order to solve the above problems, a lighting device of the present invention includes a light source unit having a light source that emits light having directivity, and a flat light guide plate that propagates light incident from the light source unit in an in-plane direction. The illumination device performs illumination using light emitted from a flat plate surface that is one of the flat plate surfaces of the light guide plate, and the light guide plate transmits light in the in-plane direction. A plurality of light scattering portions for scattering a part of the light and emitting a part of the scattered light from the surface of the flat plate, and each of the light scattering portions is a first of the regions in the in-plane direction of the light guide plate. It is characterized by being arranged so that the degree of scattering in one area is smaller than the degree of scattering in the second area where the amount of light guided is smaller than that in the first area.

  According to the above configuration, the light guide plate includes a plurality of light scattering portions for scattering a part of the light propagating in the in-plane direction and emitting a part of the scattered light from the flat plate surface. The part is arranged so that the degree of scattering in the first area among the areas in the in-plane direction of the light guide plate is smaller than the degree of scattering in the second area where the amount of guided light is smaller than that of the first area. Thereby, the uniformity of the light quantity of the light radiate | emitted from each area | region in the in-plane direction of a light-guide plate can be improved.

  The light source unit includes a light coupling member for causing the light emitted from the light source to enter the light guide plate, and is a flat plate on the opposite side of the flat plate surface of the flat plate surface of the light guide plate. The light coupling member is arranged on the back surface side, and the light coupling member receives the light emitted from the light source from the back surface side of the flat plate of the light guide plate and totally reflects the light on the flat plate surface of the light guide plate. The light is incident on the light guide plate so as to propagate in the in-plane direction in the light plate, and each light scattering portion totally reflects the light propagating in the light guide plate among the end portions in the in-plane direction of the light guide plate. The degree of scattering in the first region, which is a region in the vicinity of the end portion to be performed, is the same as that in the first region in the second region, which is a region farther from the end portion that totally reflects than the first region. The degree of scattering when a large amount of light is propagated It may be configured to be arranged to be smaller than.

  According to the above configuration, the region where light from the light source unit to the end of the light guide plate and the light totally reflected at the end of the light guide plate propagate (or is totally reflected at the end. The degree of scattering in the region where the amount of light is large) is a region where only light from the light source unit to the end of the light guide plate propagates (or the amount of light totally reflected at the end is small) The degree of scattering in the region). Therefore, the uniformity of the amount of light emitted from each region in the in-plane direction of the light guide plate can be improved.

  The first area and the second area may have different area densities, which are ratios of areas occupied by the respective light scattering portions per unit area in the in-plane direction. For example, the size of at least a part of the light scattering portions arranged in the first area may be different from the size of at least a part of the light scattering parts arranged in the second region. Moreover, it is good also as a structure from which the arrangement pitch (space | interval of light scattering parts) of each light-scattering part arrange | positioned in the said 1st area | region differs from the arrangement pitch of each light-scattering part arrange | positioned in the said 2nd area | region.

  According to each of the above configurations, the degree of scattering can be made different between the first region and the second region, and the uniformity of the amount of light emitted from each region in the in-plane direction of the light guide plate is improved. Can do.

  Further, the light source unit has a strip shape extending in one direction, the light source is composed of a plurality of LEDs arranged in a line along the extending direction of the light source unit, and the light coupling member is Light emitted from each LED is reflected in a direction perpendicular to the extending direction of the light source unit and is incident on the light guide plate, and is positioned in a direction perpendicular to the extending direction of the light source unit in the light guide plate. The shape of at least a part of the end portions to be processed may be a shape that totally reflects light propagating in a direction perpendicular to the extending direction of the light source unit.

  According to said structure, the light which injects into a light-guide plate from a light source unit propagates in the direction perpendicular | vertical to the extending | stretching direction of a light source unit. Therefore, since the light propagation direction can be easily specified, the range of the end portion of the light guide plate where the light propagated in the light guide plate is totally reflected can be easily specified. Thereby, it is possible to easily set the degree of scattering in the region including the end portion where the light is totally reflected and the degree of scattering in the other regions.

  Further, each of the light scattering portions is configured such that the degree of scattering at each position in the direction perpendicular to the extending direction of the light source unit increases as the distance from the incident position where the light from the light coupling member is incident increases. The arrangement may be sufficient.

  The amount of light propagating through the light guide plate decreases as the distance from the light source unit increases due to diffusion by the light diffusion unit or the like. On the other hand, according to the above configuration, since the degree of scattering increases as the distance from the light source unit increases, the amount of light emitted from the flat plate surface of the light guide plate is made uniform. be able to.

  The light source unit has a strip shape extending in one direction, and the light source includes a first LED group including a plurality of LEDs arranged in a line along the extending direction of the light source unit, and a first LED. A second LED group composed of a plurality of LEDs arranged in parallel to the group, and the optical coupling member transmits light emitted from the LEDs included in the first LED group perpendicular to the extending direction of the light source unit. Second light is reflected in the first direction and incident on the light guide plate, and light emitted from the LEDs included in the second LED group is perpendicular to the extending direction of the light source unit and opposite to the first direction. It is good also as a structure which reflects in a direction and injects into the said light-guide plate.

  According to said structure, the light from a light source unit can be propagated to the area | region of a 1st direction with respect to the light source unit in a light-guide plate, and the area | region of a 2nd direction. Therefore, in the configuration in which the light source unit is disposed on the back surface (flat plate back surface) side of the light guide plate, light can be propagated to substantially the entire area of the light guide plate.

  The color of light emitted from the LEDs included in the first LED group may be different from the color of light emitted from the LEDs included in the second LED group.

  According to said structure, illumination of a different color can be performed by the area | region located in a 1st direction with respect to a light source unit, and the area | region located in a 2nd direction.

  Moreover, it is good also as a structure provided with two or more said light source units.

  According to said structure, the light quantity of the illumination light by an illuminating device can be increased by providing multiple light source units.

  The shape formed by the outer edge portion of the light guide plate when viewed from the normal direction of the flat plate surface is any one of a circle, an ellipse, a rectangle, a shape in which each corner of the rectangle is chamfered in a curved shape, and a rhombus It may be.

  According to said structure, the uniformity of the light quantity of the light radiate | emitted from each area | region in the in-plane direction of a light-guide plate can be improved in the illuminating device of each said shape.

  A method of manufacturing an illumination device according to the present invention includes a light source unit having a light source that emits light having directivity, and a flat light guide plate that propagates light incident from the light source unit in an in-plane direction. A method for manufacturing an illuminating device that performs illumination using light emitted from a flat plate surface that is one of flat plate surfaces of an optical plate, wherein a part of the light propagating in the in-plane direction to the light guide plate A light scattering part forming step of forming a plurality of light scattering parts for emitting a part of the scattered light from the flat plate surface, and in the light scattering part forming step, in the in-plane direction of the light guide plate The region is characterized in that the degree of scattering in the first region is smaller than the degree of scattering in the second region where the amount of guided light is smaller than that in the first region.

  According to said method, the uniformity of the light quantity of the light radiate | emitted from each area | region in the in-plane direction of a light-guide plate can be improved.

  As described above, in the illumination device and the method for manufacturing the illumination device of the present invention, the degree of scattering in the first region out of the region in the in-plane direction of the light guide plate is less than the first region. It arrange | positions so that it may become smaller than the degree of scattering in a 2nd area | region.

  Thereby, the uniformity of the light quantity of the light radiate | emitted from each area | region in the in-plane direction of a light-guide plate can be improved.

It is a schematic diagram which shows the structure of the part containing the light source unit in the illuminating device concerning one Embodiment of this invention. (A) is a perspective view which shows the external appearance of the surface side of the illuminating device shown in FIG. 1, (b) is a perspective view which shows the external appearance of the back side. It is a perspective view of the light source unit shown in FIG. (A) is sectional drawing of the optical coupling member with which the light source unit shown in FIG. 1 is equipped, (b) is an enlarged view of the A section shown in the figure of (a). (A) is sectional drawing of the modification of the optical coupling member with which the light source unit shown in FIG. 1 is equipped, (b) is an enlarged view of the B section shown in the figure of (a). (A) is explanatory drawing which shows the mode of the illumination by the illuminating device shown in FIG. 1, (b) is an enlarged view of the C section shown in the figure of (a). (A) is explanatory drawing which shows luminance distribution of the light radiate | emitted from the light-guide plate with which the illuminating device of FIG. 1 is equipped, (b) is a light source which passes along the point A and the point B which were shown in the figure of (a). 4 is a graph showing a luminance distribution at a position parallel to the extending direction of the unit 30. It is explanatory drawing which shows the area | region where the total reflection of the light which propagates the inside of a light guide plate arises in the edge part of the light guide plate with which the illuminating device shown in FIG. 1 is equipped. (A)-(d) is explanatory drawing which shows the modification of the illuminating device shown in FIG. It is explanatory drawing which shows the modification of the illuminating device shown in FIG. It is explanatory drawing which shows the modification of the illuminating device shown in FIG. (A) is explanatory drawing which shows the area | region of the surface direction of the light-guide plate with which the illuminating device shown in FIG. 1 is equipped, (b) is arrange | positioned on line segment A1 and line segment A2 which were shown to (a). It is explanatory drawing which shows an example of the size of each dot pattern to be performed.

  An embodiment of the present invention will be described. In addition, although this embodiment demonstrates the case where this invention is applied to a ceiling light (illuminating device attached to a ceiling), the application object of this invention is not limited to this.

(1-1. Overall configuration of ceiling light 1)
FIG. 2A is a perspective view showing the appearance of the surface side (light emitting surface side) of the ceiling light (illuminating device) 1 according to the present embodiment, and FIG. 2B shows the appearance of the back side of the ceiling light 1. It is a perspective view shown.

  As shown in FIG. 2A, the ceiling light 1 has a substantially disc shape, and is disposed in a frame 20 provided so as to surround the disc shape and a region surrounded by the frame 20. And a diffusion plate 11. Further, as shown in FIG. 2B, a light source unit 30 arranged to extend in the diameter direction of the disk shape and a light source unit 30 on the back side of the ceiling light 1 are provided on the back side of the ceiling light 1. A back chassis 15 provided so as to cover the removed portion and an attachment member 21 for attaching the ceiling light 1 provided on a part of the back chassis 15 to a ceiling or the like are provided.

  The size of the ceiling light 1 is not particularly limited. In the present embodiment, the ceiling light 1 having a diameter of 550 mm and a thickness of 10 mm at the thinnest portion is used.

  FIG. 1 is a schematic cross-sectional view illustrating a configuration of a portion including the light source unit 30 in the ceiling light 1. FIG. 3 is a perspective view of the light source unit 30 before being attached to the ceiling light 1 as seen from the light emitting surface side.

  As shown in FIG. 1, the ceiling light 1 includes a diffusion plate 11, a prism sheet 12, a light guide plate 13, and a light source unit 30 in order from the light emitting surface side. In addition, a reflector 14 and a back chassis 15 are provided in a portion where the light source unit 30 is not provided on the back side of the light guide plate 13.

  As shown in FIG. 1 and FIG. 3, the light source unit 30 is attached to a light source holder 31 having a concave portion having a substantially U-shaped cross section that extends in the diameter direction through the center of the ceiling light 1, and is attached to the bottom of the concave portion. The plate-shaped heat sink 32, the LED boards 33a and 33b provided on the heat sink 32, the LED groups 34a and 34b provided on the LED boards 33a and 33b, the LED groups 34a and 34b, and the light guide plate 13. And a coupling lens 35 provided therebetween. The heat sink 32, the LED substrates 33a and 33b, the LED groups 34a and 34b, and the coupling lens 35 are accommodated in the recess. Further, back chassis 15 are attached to both ends in a direction perpendicular to the extending direction of the light source holder 31 and substantially parallel to the light emitting surface.

  The LED group 34 a and the LED group 34 b are each composed of a plurality of LEDs arranged side by side in a direction parallel to the extending direction of the light source unit 30. In addition, although LED is used as a light source in this embodiment, it is not necessarily restricted to this, What is necessary is just a light source which radiate | emits the light which has directivity.

  The LED boards 33a and 33b control the amount of current supplied to each LED provided in the LED groups 34a and 34b, thereby controlling the light emission ON / OFF of each LED and the control circuit and wiring for controlling the light emission amount ( Neither is shown), and is arranged to extend in a direction parallel to the extending direction of the light source unit 30.

  The heat sink 32 is for absorbing heat from the LEDs or LED boards 33a and 33b provided in the LED groups 34a and 34b. The heat sink 32 covers the bottom surface of the concave portion of the light source unit 30. It arrange | positions along the extending | stretching direction. In addition, you may provide the mechanism (for example, heat dissipation fin, a fan, etc.) for dissipating the heat which the heat sink 32 absorbed to the exterior of the ceiling light 1. FIG.

  The coupling lens (light coupling member) 35 makes light emitted from each LED provided in the LED groups 34 a and 34 b incident on the light guide plate 13 from a predetermined angle range (from the back side of the light guide plate 13 (substrate back side)). Then, the light that has reached the light emitting surface side (substrate surface side) of the light guide plate 13 is guided to the inside of the light guide plate 13 so as to enter the light guide plate 13 in an angle range where the light is totally reflected on the light emitting surface side) It is arrange | positioned so that it may extend | stretch in the direction parallel to the extending | stretching direction of the light source unit 30. In the present embodiment, each LED provided in the LED groups 34a and 34b has a plane (light emission) in which the principal axis direction of light emitted from each LED (the direction in which the luminance distribution of emitted light is maximum) is formed. It is installed so that it may be in a direction substantially perpendicular to the surface. And the coupling lens 35 changes the advancing direction of the light radiate | emitted from each LED, and injects with respect to the light-guide plate 13 in the said predetermined angle range. In this embodiment, the clearance between each LED and the coupling lens 35 is set to a predetermined value of 0.5 mm or less. In the configuration in which the light source is arranged at the peripheral portion in the in-plane direction of the light guide plate, a large clearance is secured between the light guide plate and the light source in order to prevent contact between the light guide plate and the light source due to thermal expansion of the light guide plate. There was a need. On the other hand, in the present embodiment, the light source unit 30 is disposed on the back side of the light guide plate 13 and the thermal expansion in the direction perpendicular to the light emitting surface of the light guide plate 13 is slight. The clearance between the light plate 13 and the light source unit 30 (coupled lens 35) is set to be smaller than the configuration in which the light source is disposed in the in-plane peripheral portion of the light guide plate.

  The material of the coupling lens 35 is such that light can propagate through the coupling lens 35, and the light traveling direction is changed so that the light incident from the light source is incident on the light guide plate 13 within the predetermined angle range. Although it will not specifically limit if it can be made to use, For example, the resin material similar to the light-guide plate 13 can be used. Further, the coupling lens 35 may be provided separately from the light guide plate 13 or may be provided integrally with the light guide plate 13. When the coupling lens 35 is formed separately from the light guide plate 13, it is possible to easily process these two members and to obtain an effect that the light guide plate 13 can be thinned. In the present embodiment, the coupling lens 35 is made of an acrylic resin.

  FIG. 4A is an explanatory diagram illustrating a configuration of a cross section of the coupling lens 35 perpendicular to the extending direction. As shown in this figure, the cross section perpendicular to the extending direction of the coupling lens 35 has flat portions 35a, 35b obtained by cutting out a part of a substantially elliptical ring in a straight line, and the above-mentioned substantially elliptical outer periphery. It is the shape which has the flat part 35c obtained by notching a part of part with flat part 35a, 35b along a substantially parallel straight line. A hollow portion corresponding to the hollow portion of the ring is provided between the flat portions 35a and 35b. That is, the flat portion 35a and the flat portion 35b are connected by the inner peripheral surface 35f of the ring.

  That is, the cross-section perpendicular to the extending direction of the coupling lens 35 has strip-shaped flat portions (light source side flat portions) 35a and 35b provided so as to extend in a direction parallel to each other in the same plane, and the light source side flat portion 35a. , 35b and a strip-shaped flat part (light guide plate side flat part) 35c provided in a plane parallel to the surface 35b, between the flat part 35a and the flat part 35c on the outer peripheral side of the cross section perpendicular to the extending direction, Further, a curved surface (total reflection surfaces 35d and 35e) is formed between the flat portion 35a and the flat portion 35c.

  FIG. 4B is an enlarged view of part A shown in FIG. As shown in FIG. 4A and FIG. 4B, LEDs constituting the LED groups 34a and 34b are arranged at positions close to the flat portions 35a and 35b of the coupling lens 35. These LEDs face the outer peripheral surface side of the coupling lens 35 (the side closer to the total reflection surfaces 35d and 35e in the flat portions 35a and 35b) than the focal position F of the total reflection surfaces 35d and 35e shown in FIG. It is arranged at the position to do.

  As a result, as shown in FIGS. 4A and 4B, the light emitted from each LED is totally reflected (substantially totally reflected) by the total reflection surfaces 35d and 35e of the coupling lens 35, and the reflected light. Enters the light guide plate 13 through the flat portion 35c. Further, the shapes of the total reflection surfaces 35d and 35e are set so that incident light from each LED can be incident on the light guide plate 13 in the predetermined angle range.

  In addition, the shape of the total reflection surfaces 35d and 35e in the cross section perpendicular to the extending direction of the coupling lens 35 is not necessarily limited to the elliptical arc shape, and the light incident from each LED included in the LED groups 34a and 34b is used. Any shape that can be totally reflected (substantially totally reflected) by the total reflection surfaces 35 d and 35 e and incident on the light guide plate 13 within a predetermined angle range may be used. For example, the total reflection surfaces 35d and 35e may be curved shapes in which the shape of the cross section perpendicular to the extending direction of the coupling lens 35 is a circular arc shape, a bow shape, a parabolic shape, or the like, and the flat portions 35a, 35e, It may be a straight line inclined with respect to 35b and 35c.

  FIG. 5A is an explanatory view showing a modified example of the coupling lens 35, in the case where the shape of the cross section perpendicular to the extending direction of the coupling lens 35 on the total reflection surfaces 35d and 35e of the coupling lens 35 is a parabolic shape. An example is shown.

  In the present embodiment, the shape of the cross section perpendicular to the extending direction of the coupling lens 35 is a shape having a hollow portion (inner peripheral surface 35f) between the flat portion 35a and the flat portion 35b. However, the present invention is not limited to this, and a shape obtained by cutting out a part of a cylindrical shape may be used. That is, it is good also as a shape which does not have a hollow part between the flat part 35a and the flat part 35b, and these both flat parts are connected with linear form.

  Further, a reflection sheet (not shown) for returning light leaking from the coupling lens 35 to the outside into the coupling lens 35 may be provided around the total reflection surfaces 35d and 35e. Thereby, even when a part of the light emitted from the LED leaks from the total reflection surfaces 35d and 35e to the outside of the coupling lens 35, the light leaking to the outside of the coupling lens 35 is returned to the coupling lens 35, The light use efficiency can be further increased by increasing the amount of light incident on the light guide plate 13.

  The light guide plate 13 is a flat plate member made of a light guide material capable of transmitting light through the light guide plate 13. The material of the light guide plate 13 is not particularly limited as long as it has a light guide property. For example, a conventionally known resin material can be used. In the present embodiment, the light guide plate 13 made of acrylic resin is used.

  In addition, light propagating in the light guide plate 13 is scattered on at least one of the surface (back surface) on the side of the coupling lens 35 in the light guide plate 13 or the surface (front surface) opposite to the coupling lens 35. A large number of dot patterns (light scattering portions) for emitting light from the light emitting surface side of the light guide plate 13 are provided. The method for forming the dot pattern is not particularly limited, and can be formed by a conventionally known method. For example, the light-diffusing reflective material may be formed by printing on one or both surfaces of the light guide plate 13, or may be formed by processing a part of the light guide plate 13 by laser processing or the like. . In this embodiment, the dot pattern is formed as the light scattering portion. However, the present invention is not limited to this, and a part of the light propagating in the light guide plate 13 is scattered and emitted from the light emitting surface side of the light guide plate 13. Anything that can do. In the present embodiment, the light emitted from the light emitting surface of the ceiling light 1 is made uniform by devising the arrangement (size and arrangement pitch) of each dot pattern. The arrangement method of each dot pattern will be described later.

  The prism sheet 12 is for controlling the emission direction and distribution of light incident from the light guide plate 13. The diffusing plate 11 diffuses and emits light incident from the light guide plate 13 via the prism sheet 12. The structures of the prism sheet 12 and the diffusion plate 11 are not particularly limited, and conventionally known ones can be used. The prism sheet 12 and the diffusing plate 11 may be provided as necessary, and one or both of these members may be omitted.

  FIG. 6A is an explanatory view showing a state of illumination by the ceiling light 1, and FIG. 6B is an enlarged view of a portion C in FIG. 6A.

  As shown in FIG. 6B, the light emitted from the LED groups 34 a and 35 b is totally reflected by the coupling lens 35 and enters the light guide plate 13, and propagates through the light guide plate 13 while being totally reflected. Further, part of the light scattered in each dot pattern provided in the light guide plate 13 is emitted from the light guide plate 13 to the diffusion plate 11 side (light emitting surface side). The light emitted from the LED group 34a and the light emitted from the LED group 34b propagate in the light guide plate 13 in opposite directions. As a result, as shown in FIG. 6A, the light emitted from the light guide plate 13 is emitted from the light emitting surface side of the ceiling light 1 through the prism sheet 12 and the diffusion plate 11 with a substantially uniform light amount in the in-plane direction. Is done.

  The reflection plate 14 is provided in a region where the light source unit 30 is not provided in a region facing the back side of the light guide plate 13. Thereby, the light which leaks from the light guide plate 13 to the back side is returned to the light guide plate 13, and the light use efficiency is enhanced. The reflection plate 14 does not necessarily cover the entire area of the back surface of the light guide plate 13 where the light source unit 30 is not provided. For example, when it is desired to illuminate the ceiling light 1 (for example, part of the ceiling) or to illuminate the side of the ceiling light 1, an area of the back surface of the light guide plate 13 where the light source unit 30 is not provided. A non-reflective region that does not include the reflecting plate 14 may be provided on a part of the light (for example, a disc-shaped peripheral edge), and a part of the light emitted from the light guide plate 13 may be emitted from the non-reflecting part. In this case, a dot pattern (light scattering portion) for emitting light from the non-reflective region may be provided at a position corresponding to the non-reflective region in the light guide plate 13. In addition, an opening may be provided at a position corresponding to the non-reflective region in the back chassis 15, and a position corresponding to the non-reflective region in the back chassis 15 may be formed of a translucent member.

(1-2. Arrangement of Dot Pattern on Light Guide Plate 13)
Next, a method for arranging dot patterns on the light guide plate 13 will be described.

  FIG. 7A shows a ceiling light 1 when a light guide plate in which dot patterns of the same shape are uniformly arranged is used and the amount of current supplied to each LED provided in the LED groups 34a and 34b is constant. It is explanatory drawing which shows the luminance distribution of the light emission surface in. 7B passes through the point A in FIG. 7A and passes through the point B on the straight line parallel to the extending direction of the light source unit 30 (see the broken line portion in FIG. 7B). It is a graph which shows the luminance distribution in the position on the straight line parallel to the extending | stretching direction of the light source unit 30 (refer the broken-line part of FIG.7 (b)).

  As shown in FIG. 7B, the luminance distribution in the direction parallel to the extending direction of the light source unit 30 is darkest in the vicinity of the central portion in the extending direction, and the luminance is maximum at positions on both end sides of the central portion. become.

  The reason why such a luminance distribution occurs will be described with reference to FIG. As shown in FIG. 8, the light emitted from the light source unit 30 propagates in a direction substantially perpendicular to the extending direction of the light source unit 30 while totally reflecting the light emitting surface side and the back surface side of the light guide plate 13. Then, as shown in FIG. 8, the angle formed between the traveling direction P of the light incident on the light guide plate 13 from the light source unit 30 in the in-plane direction of the light guide plate 13 and the tangent line Q of the peripheral portion 13 a of the light guide plate 13. In the region where is more than the critical angle θ, the light reaching the peripheral portion 13a of the light guide plate 13 is totally reflected by the peripheral portion 13a and further propagates in the light guide plate 13. On the other hand, in the region less than the critical angle θ, the light that has reached the peripheral portion 13 a of the light guide plate 13 is emitted from the peripheral portion 13 a to the outside of the light guide plate 13.

The critical angle θ is expressed by sin θ = 1 / n, where n is the refractive index of light propagating through the light guide plate 13 on the surface of the light guide plate 13 (a contact surface with air). In this embodiment, the light guide plate 13 made of acrylic is used, and the refractive index n of acrylic is about 1.49, so that the critical angle θ = sin ⁻¹ (1 / n) ≈42.2 °. .

  Therefore, in the region where the total reflection is high in the peripheral portion of the light guide plate 13 (the region S2 corresponding to both ends in the extending direction of the light source unit 30 shown in FIG. 8), the region where the total reflection is low (the light source unit shown in FIG. 8). The amount of light propagating in the light guide plate 13 is larger than that in the region S1) corresponding to the central portion of the 30 extending directions.

  Further, the amount of light propagating in the light guide plate 13 decreases as the distance from the light source unit 30 increases due to scattering in the dot pattern.

In the present embodiment, in consideration of these points, the following rules (1) and (2) are set so that substantially uniform luminance (or luminance close to equality) can be obtained over the entire light emitting surface of the ceiling light 1. Based on this, the arrangement of the dot pattern is determined.
(1) About the direction perpendicular | vertical to the extending | stretching direction of the light source unit 30, it arrange | positions so that the area density (ratio of the area which the dot pattern per unit area occupies) becomes dense, so that it is far from the light source unit 30. That is, assuming that the same amount of light is supplied to each position in the direction perpendicular to the extending direction of the light source unit 30, the light scattering amount (emits from the light guide plate 13 to the light emitting surface side as the position is farther from the light source unit 30. The dot pattern is arranged so that the amount of light) increases.
(2) About the direction parallel to the extending direction of the light source unit 30, the light from the light source unit 30 traveling in the direction in the in-plane direction of the light guide plate 13 and the direction perpendicular to the extending direction of the light source unit 30 The dot patterns are arranged so that the area density of the dot pattern in the region near the total reflection end is sparser than the area density in the region farther from the total reflection end than the region. That is, assuming that the same amount of light is supplied to each position in the direction parallel to the extending direction of the light source unit 30, the amount of light scattering (conduction) is greater in the region where total reflection does not occur than in the region where total reflection occurs. The dot patterns are arranged so that the amount of light emitted from the light plate 13 toward the light emitting surface increases.

  When the area density of the dot pattern is changed in the direction parallel to the extending direction of the light source unit 30, the area density of the dot pattern does not change abruptly between the area where the total reflection occurs and the area where the total reflection does not occur. In addition, the area density of the dot pattern may be changed continuously or stepwise according to the position of the light source unit 30 in the direction parallel to the extending direction. Similarly, in the direction perpendicular to the extending direction of the light source unit 30, the area density of the dot pattern may be changed continuously or stepwise according to the position in the direction perpendicular to the extending direction of the light source unit 30.

  Therefore, in the example of FIG. 8, the area density of the dot pattern on an arbitrary straight line perpendicular to the extending direction of the light source unit 30 becomes denser as the position is farther from the light source unit 30 (the position closer to the outer edge of the light guide plate 13). Placed in. Further, the area density of the dot pattern on an arbitrary straight line parallel to the extending direction of the light source unit 30 is arranged so that the area density in the region S2 is sparser than the area density in the region S1.

  In this embodiment, the area density of the dot pattern is changed by making the arrangement pitch of the dot pattern constant and changing the size of the dot pattern. However, the present invention is not limited to this. For example, the area density of the dot pattern may be changed by making the size of each dot pattern constant and changing the arrangement pitch of the dot patterns. Further, the dot pattern area density may be changed by changing both the dot pattern arrangement pitch and the dot pattern size.

  Further, the size and arrangement of each dot pattern may be determined based on the result of calculating the amount of light propagating through each region in the light guide plate 13 by simulation or the result of detection by experiment.

  FIG. 12A is an explanatory diagram showing a region in the in-plane direction of the light guide plate 13, and FIG. 12B shows that the arrangement pitch of each dot pattern is constant, and the size of each dot pattern varies depending on the arrangement position. FIG. 12 shows an example of the size of each dot pattern arranged on the line segment A1 and the line segment A2 shown in FIG. In these drawings, the direction perpendicular to the extending direction of the light source unit 30 passing through the center of the disc-shaped light guide plate 13 is the x axis, and the direction passing through the center and parallel to the extending direction of the light source unit 30 is the y axis. It prescribes. The line segment A1 is a line segment in the range of y ≧ 0 passing through x = 10 (mm) and parallel to the y-axis, and the line segment A2 is y ≧ parallel to the y-axis passing through x = 200 (mm). A line segment in the range of zero. The numerical values shown in the table of FIG. 12B indicate the radius (mm) of each dot pattern. Here, the dot pattern arrangement in the first quadrant defined by the x axis and the y axis will be described. However, the arrangement of the dot patterns in the light guide plate 13 is line symmetric with respect to the x axis and the y axis. Is line symmetric.

  As shown in FIG. 12B, in this example, of the line segments A1 and A2, the dot pattern arranged on the line segment A1 that is closer to the light source unit 30 is arranged on the line segment A2. Is set smaller than the size of the dot pattern to be set. In addition, the dot patterns arranged on the same line segment are set so that the average size of the dot pattern is relatively smaller in the region where the y value is large than in the region where the y value is small.

  As described above, the ceiling light 1 according to the present embodiment includes the light beam unit 30 and the flat light guide plate 13 that propagates the light incident from the light source unit 30 in the in-plane direction. The light guide plate 13 has many dot patterns (light scattering portions) for scattering a part of light propagating in the in-plane direction through the light guide plate 13 and emitting a part of the scattered light from the light emitting surface side. Each dot pattern has an in-plane direction region of the light guide plate 13 in which the degree of scattering in the first region is higher than the first region in the amount of light guided (in the normal direction of the flat surface of the light guide plate 13). The amount of light passing through the cross section) is less than the degree of scattering in the second region.

  Thus, the degree of light scattering in each region in the in-plane direction of the light guide plate 13 by each dot pattern is set according to the amount of light propagating through each region (light guide light amount), and the in-plane direction of the light guide plate 13 The uniformity of the amount of light emitted from each region in can be improved.

  In the ceiling light 1 according to the present embodiment, the light emitted from the LED groups 34 a and 34 b is incident from the back side of the light guide plate 13, and is totally reflected on the light emitting surface side of the light guide plate 13. A coupling lens 35 that allows light emitted from the LED groups 34a and 34b to enter the light guide plate 13 is provided so as to propagate in the in-plane direction. In addition, each dot pattern has a degree of scattering in the first region, which is a region in the vicinity of the end portion where the light propagating in the light guide plate 13 is totally reflected among the end portions in the in-plane direction of the light guide plate 13. It is arranged to be smaller than the degree of scattering when the same amount of light is propagated to the second region, which is a region far from the total reflection end than the one region.

  As a result, a region (end edge) including an end portion where light from the coupling lens 35 to the light guide plate 13 and reaching the end portion of the light guide plate 13 and light totally reflected at the end portion of the light guide plate 13 propagates. The degree of scattering in the region where the amount of light totally reflected by the portion is relatively large) is compared mainly with the region where only the light incident on the light guide plate 13 from the coupling lens 35 propagates (the amount of light totally reflected by the end portion). Less than the degree of scattering in a small area). Therefore, the degree of light scattering in each region in the in-plane direction of the light guide plate 13 by each dot pattern is set according to the amount of light propagating through each region, and emitted from each region in the in-plane direction of the light guide plate 13. It is possible to improve the uniformity of the amount of light.

  In the present embodiment, the disc-shaped ceiling light 1 has been described. However, the shape of the lighting device of the present invention is not limited to this. For example, the present invention may be applied to a rectangular illumination device as shown in FIG. Further, as shown in FIG. 9B, the present invention may be applied to a lighting device having a shape in which each corner of a rectangular shape is chamfered in a curved shape. Moreover, you may apply to an elliptical illuminating device as shown in FIG.9 (c). Moreover, you may apply to a diamond-shaped illuminating device as shown in FIG.9 (d).

  In the case of the shape shown in FIG. 9A, in the direction perpendicular to the extending direction of the light source unit 30, the dot pattern provided on the light guide plate 13 is arranged so that the area density becomes denser as the distance from the light source unit 30 increases. The Further, in the direction horizontal to the extending direction of the light source unit 30, the dot pattern provided on the light guide plate 13 is arranged so that the area density is substantially constant regardless of the position. However, the light emitted from the light source unit 30 mainly travels in a direction perpendicular to the extending direction of the light source unit 30, but there is also a light component that travels in a direction inclined with respect to the direction. For this reason, in consideration of the light totally reflected at the peripheral portion of the light guide plate 13 in the direction parallel to the extending direction of the light source unit 30, the area of the dot pattern in the region near the peripheral portion in the direction horizontal to the extending direction of the light source unit 30 The density may be made sparser than other regions located in a direction horizontal to the extending direction of the light source unit 30 with respect to the region.

  In the example of FIG. 9B, the area density of the dot pattern on an arbitrary straight line perpendicular to the extending direction of the light source unit 30 becomes denser as the position is farther from the light source unit 30 (position closer to the outer edge of the light guide plate 13). Are arranged as follows. Further, the area density of the dot pattern on an arbitrary straight line parallel to the extending direction of the light source unit 30 is the region where the peripheral edge in the extending direction of the light source unit 30 is linear (region corresponding to a rectangular side). They are arranged so that the area density is substantially constant regardless of the position. On the other hand, for a region where the peripheral portion in the extending direction of the light source unit 30 is curved (region corresponding to the chamfered portion), both end portions in a direction horizontal to the extending direction of the light source unit 30 (perpendicular to the extending direction of the light source unit 30). The area where the total density of the area where the total reflection occurs in the peripheral part in the directional direction is a central part in the direction horizontal to the extending direction of the light source unit 30 (the area where the total reflection does not occur in the peripheral part in the direction perpendicular to the extending direction of the light source unit 30). ) Is set to be sparser than the area density.

  9C and FIG. 9D, the area density of the dot pattern on an arbitrary straight line perpendicular to the extending direction of the light source unit 30 is a position far from the light source unit 30 (close to the outer edge of the light guide plate 13). (Position) is arranged so as to be denser. Further, regarding the direction horizontal to the extending direction of the light source unit 30, the area density of both end portions in the horizontal direction (region where total reflection occurs in the peripheral portion in the direction perpendicular to the extending direction of the light source unit 30). It is set so as to be sparser than the area density of the central portion in the direction horizontal to the extending direction (region where total reflection does not occur in the peripheral portion in the direction perpendicular to the extending direction of the light source unit 30).

  Moreover, although this embodiment demonstrated the structure provided with only 1 row of light source units 30, it is good also as a structure provided with the light source unit 30 of 2 or more rows not only in this. Thereby, the light quantity of the light radiate | emitted from a light emission surface can be increased, and the brightness of the ceiling light 1 can be improved.

  In the present embodiment, the configuration in which the light source unit 30 includes the two rows of LED groups 34a and 34b has been described. However, the configuration is not limited thereto, and for example, the light source unit 30 may include only one row of LED groups. . In this case, the coupling lens 35 can make the light emitted from the LED group in one row incident on the light guide plate 13 at an inclination angle equal to or greater than a predetermined angle (an angle at which the light is totally reflected in the light guide plate 13). Any configuration may be used.

  Moreover, in this embodiment, although the color of the emitted light of LED contained in LED group 34a and the color of the emitted light of LED contained in LED group 34b are made the same color, the emitted light of LED contained in these both LED groups. The colors of may be different. For example, as shown in FIG. 11, two rows of strip-like light source units 30 are arranged in parallel to each other, and light is emitted to the other light source unit 30 side among the LED groups 34 a and 34 b provided in both the light source units 30. The color of the emitted light from the LED group 34a may be a light bulb color, and the color of the emitted light from the LED group 34a that emits light to the side opposite to the other light source unit 30 may be daylight white. Thereby, the area | region inside the light source unit 30 (area | region between light source units 30) is light-emitted in the light bulb color among the light emission surfaces of the ceiling light 1, and the area | region outside the light source unit 30 is light-emitted with daylight white. it can. Further, by controlling the light emission state of the LED groups 34a and 34b, (1) only the light bulb color is emitted, (2) only the neutral white color is emitted, (3) both the bulb color and the natural white color are emitted. Such dimming illumination can be performed.

  In the present embodiment, LEDs that emit light having a color temperature of 2000K to 6000K are used as the LEDs provided in the LED groups 34a and 34b. That is, an LED that emits light within a range including a color temperature of about 2000K corresponding to red light in the morning sun or sunset and a color temperature of about 5000K to 6000K corresponding to sunlight. However, the light emission color of each LED is not limited to this, and may be appropriately selected according to the application or design of the lighting device. For example, when the lighting device 1 is used as a backlight of a liquid crystal display device, an LED having a color temperature of 10,000 K to 20000 K may be used.

  In the present embodiment, the shape of the light source unit 30 is a strip shape extending in one direction, but the shape of the light source unit 30 is not limited to this. For example, as shown in FIG. 10, a ring-shaped light source unit 30 may be used. In this case as well, light is emitted by arranging the dot pattern so that the area density of the dot pattern in the region to which the light emitted from the light source unit 30 and totally reflected at the peripheral portion of the light guide plate 13 is supplied is sparse. The amount of light emitted from the surface can be made uniform.

  In addition, a reflection sheet for returning the light emitted from the peripheral edge to the outside of the light guide plate 13 in the in-plane peripheral edge portion of the light guide plate 13 or the position facing the peripheral edge portion is installed in the light guide plate 13. May be. Thereby, the light emitted from the peripheral portion of the light guide plate 13 to the side of the light guide plate 13 is returned to the light guide plate 13 and emitted from the light emitting surface side, and can be used for illumination on the light emitting surface side. Can be increased.

  Further, in the present embodiment, LEDs having substantially the same light emission intensity characteristics are used as the LEDs in the LED groups 34a and 34b of the light source unit 30, the arrangement pitch of these LEDs is constant, and the amount of current supplied to these LEDs However, it is not limited to this. For example, the light supply amount to the region near the end portion where the light emitted from the light source unit 30 in the directing plate 13 is totally reflected is supplied to the region farther from the end portion that totally reflects than the region. At least one of the light emission intensity characteristics of each LED, the arrangement pitch, and the amount of current supplied to each LED may be made different for each LED or for each group of LEDs so as to be smaller than the amount. .

  Moreover, although this embodiment demonstrated the case where this invention was applied to a ceiling light, the application object of this invention is not restricted to this. For example, a lighting device provided on a wall surface or a floor surface, a stand-type lighting device placed on a tabletop or a floor, a hanging type lighting device suspended from a ceiling, a lighting device provided on a desk, shelf, bed, etc. The present invention can be applied to various lighting devices such as lighting devices provided in various electric appliances such as liquid crystal display devices.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and the embodiments can be obtained by appropriately combining the technical means disclosed in the embodiments. The form is also included in the technical scope of the present invention.

  The present invention can be applied to an illumination device that emits light from a light source in a planar shape by a light guide plate.

1 Ceiling light (lighting device)
11 diffuser plate 12 prism sheet 13 light guide plate 14 reflector 15 back chassis 20 frame 30 light source unit 31 light source holder 32 heat sinks 33a and 33b LED substrates 34a and 34b LED group 35 coupling lens (optical coupling member)
35a, 35b Flat part (light source side flat part)
35c flat part (light guide plate side flat part)
35d, 35e Total reflection surface S1 region (second region)
S2 area (first area)

Claims (12)

A light source unit having a light source that emits light having directivity; and a flat light guide plate that propagates light incident from the light source unit in an in-plane direction, and one of the flat surfaces of the light guide plate An illumination device that performs illumination using light emitted from a flat plate surface,
The light guide plate includes a plurality of light scattering portions for scattering a part of the light propagating in the in-plane direction and emitting a part of the scattered light from the flat plate surface,
Each light scattering part is
Among the regions in the in-plane direction of the light guide plate, the degree of scattering in the first region is arranged to be smaller than the degree of scattering in the second region where the amount of guided light is less than that of the first region. A lighting device characterized by the above. The light source unit includes a light coupling member for allowing light emitted from the light source to enter the light guide plate, and a flat plate rear surface side that is a surface opposite to the flat plate surface of the flat plate surface of the light guide plate Are located in
The optical coupling member receives light emitted from the light source from the flat plate rear surface side of the light guide plate, and totally reflects on the flat plate surface of the light guide plate so that the inside of the light guide plate is directed in the in-plane direction. It is incident on the light guide plate so as to propagate,
Each light scattering part is
Of the end portions in the in-plane direction of the light guide plate, the degree of scattering in the first region, which is a region near the end portion that totally reflects the light propagating in the light guide plate, is higher than that in the first region. It is characterized in that it is arranged so as to be smaller than the degree of scattering when the same amount of light as that in the first region is propagated to the second region, which is a region far from the total reflection end. The lighting device according to claim 1.   The area density which is a ratio of the area which each said light-scattering part per unit area in the said in-plane direction differs in the said 1st area | region and the said 2nd area | region differs from Claim 1 or 2 characterized by the above-mentioned. Lighting device.   The size of at least a part of the light scattering portions arranged in the first area is different from the size of at least a part of the light scattering parts arranged in the second region. 3. The lighting device according to 3.   5. The illumination device according to claim 3, wherein an arrangement pitch of each light scattering portion arranged in the first region is different from an arrangement pitch of each light scattering portion arranged in the second region. . The light source unit has a strip shape extending in one direction,
The light source comprises a plurality of LEDs arranged in a row along the extending direction of the light source unit,
The light coupling member reflects light emitted from the LEDs in a direction perpendicular to the extending direction of the light source unit and enters the light guide plate.
At least a part of the end portion of the light guide plate positioned in the direction perpendicular to the extending direction of the light source unit is a shape that totally reflects light propagating in the direction perpendicular to the extending direction of the light source unit. The lighting device according to any one of claims 1 to 5, wherein   Each of the light scattering portions is arranged such that the degree of scattering at each position in the direction perpendicular to the extending direction of the light source unit increases as the distance from the incident position where the light from the light coupling member enters increases. The lighting device according to claim 6. The light source unit has a strip shape extending in one direction,
The light source includes a first LED group composed of a plurality of LEDs arranged in a line along the extending direction of the light source unit, and a second LED group composed of a plurality of LEDs arranged in parallel to the first LED group. ,
The light coupling member reflects light emitted from the LEDs included in the first LED group in a first direction perpendicular to the extending direction of the light source unit to enter the light guide plate, and is included in the second LED group. 8. The light emitted from the LED to be reflected is reflected in a second direction perpendicular to the extending direction of the light source unit and opposite to the first direction, and is incident on the light guide plate. The illumination device according to any one of the above.   9. The illumination device according to claim 8, wherein a color of light emitted from an LED included in the first LED group is different from a color of light emitted from an LED included in the second LED group.   The lighting device according to claim 1, comprising a plurality of the light source units.   The shape formed by the outer edge of the light guide plate when viewed from the normal direction of the flat plate surface is one of a circle, an ellipse, a rectangle, a shape in which each corner of the rectangle is chamfered in a curved shape, and a rhombus The lighting device according to any one of claims 1 to 10, wherein A light source unit having a light source that emits light having directivity; and a flat light guide plate that propagates light incident from the light source unit in an in-plane direction, and one of the flat surfaces of the light guide plate A method of manufacturing an illumination device that performs illumination using light emitted from a flat plate surface,
A light scattering part forming step of forming a plurality of light scattering parts for scattering a part of the light propagating in the in-plane direction on the light guide plate and emitting a part of the scattered light from the plate surface;
In the light scattering part forming step,
Each of the light scattering portions is configured such that the degree of scattering in the first area among the areas in the in-plane direction of the light guide plate is smaller than the degree of scattering in the second area where the amount of light guided is smaller than that of the first area. The manufacturing method of the illuminating device characterized by arrange | positioning.

Images