CN209928054U - Light guide plate, light guide plate assembly and lighting device - Google Patents

Abstract

A light guide plate, a light guide plate assembly and a lighting device are provided. The light guide plate (10) is provided with a plurality of long groove-shaped prisms (20) and a plurality of conical prisms (40). In a 1 st cross section of a plane orthogonal to the extending direction of the long groove prism (20), an angle formed by an inner surface (22) of the long groove prism (20) and an extension line (24) of an outer surface portion (23) connected with the inner surface is set to be theta 1, and in a 2 nd cross section of a plane including a central axis of the conical inner peripheral surface of the conical prism (40), an angle formed by an inner surface (43) of the hole (42) and an extension line (46) of an outer surface portion (45) connected with the inner surface is set to be theta 2, theta 1< theta 2 is satisfied.

Description

Light guide plate, light guide plate assembly and lighting device

Technical Field

The utility model relates to a light guide plate, light guide plate subassembly and lighting device.

Background

Conventionally, as an illumination device, there is an edge light (edgelight) described in japanese patent application laid-open No. 2003-262734. The sidelight fixture is provided with a substantially linear light source including a long substrate and a plurality of Light Emitting Diodes (LEDs) linearly mounted on a mounting surface thereof, and a flat light guide plate. The substantially linear light source is disposed along a side surface of the light guide plate, a width direction of the substrate coincides with a thickness direction of the light guide plate, and a length direction of the substrate coincides with an extending direction of the side surface. The optical axis of light emitted from a light emitting diode (hereinafter referred to as an LED) extends in the direction normal to the side surface. Further, the light guide plate has a plurality of prisms on one side surface in the thickness direction thereof. The prism directs light from the LED incident on the light guide plate to the other side in the thickness direction, reflects light in a direction corresponding to the prism shape, and also emits the light to the prism side. As a result, the light incident on the light guide plate is emitted as leak light from the prism on the prism side in the thickness direction, and is emitted as direction-controlled light by the prism on the other side in the thickness direction.

In a bar lamp which is disposed beside a passage for walking in a garden or the like and illuminates the foot side of a pedestrian, if light can be sufficiently distributed in a lamp width direction inclined toward the traveling direction side of the passage with respect to the front direction of the bar lamp, the traveling front side of the passage can be made bright, which is preferable. In addition, in such a pillar lamp, if light distribution can be made not only in the lamp width direction but also in the front direction, it is preferable that the road surface can be uniformly and brightly illuminated. Further, if such light distribution can be achieved, it is preferable to improve the appearance of the illumination light not only by the pillar lamp but also by a bracket lamp (blacket light) for irradiating the illumination light to the ceiling, a wall wash lamp for irradiating the illumination light to the side wall of the building, or the like. Further, according to the specification, such light distribution can improve the appearance effect of the illumination light also in other applications, for example, a dome lamp.

SUMMERY OF THE UTILITY MODEL

Therefore, an object of the present invention is to provide a light guide plate, a light guide plate assembly, and a lighting device that can irradiate light in a lamp width direction, control the balance between the lamp width direction light distribution and the front direction light distribution, and easily make the illuminance of an irradiation surface uniform.

In order to solve the above problem, the present invention provides a light guide plate having a plate-like shape including a 1 st plate surface located on one side in a thickness direction and a 2 nd plate surface located on the other side in the thickness direction, the light guide plate including: a light incident end surface provided with a plurality of grooves which are arranged adjacent to each other in a circumferential direction and extend in the thickness direction; a plurality of long groove prisms provided on at least one of the 1 st plate surface and the 2 nd plate surface at intervals; and a plurality of conical prisms provided on at least one of the 1 st plate surface and the 2 nd plate surface at intervals; the elongated groove prisms are formed by inner surfaces of elongated grooves, and extending directions of the elongated groove prisms are substantially the same; the conical prism is formed by the inner surface of a hole with the inner surface of a roughly conical inner surface on the opening side; in a 1 st cross section taken on a plane orthogonal to an extending direction of the long groove, an angle formed by an inner surface of the opening side of the long groove and an extension line of an outer surface portion continuous to the inner surface is θ 1, and in a 2 nd cross section taken on a plane including a center axis of the conical inner circumferential surface of the hole, an angle formed by an inner surface of the hole and an extension line of an outer surface portion continuous to the inner surface is θ 2, θ 1< θ 2 is satisfied.

According to the utility model discloses a light guide plate, light guide plate subassembly and lighting device can shine the light to the broad direction of lamp to control the balance of the broad direction grading of lamp and positive direction grading, make easily and shine the face illuminance homogenization.

Further, both ends of the opening of the long-groove prism in the extending direction may be bent lines protruding outward in the extending direction.

Further, the plurality of long groove prisms and the plurality of conical prisms may be provided on the 1 st plate surface.

Further, the plurality of long groove prisms may be provided on the 1 st plate surface, and the plurality of conical prisms may be provided on the 2 nd plate surface.

Further, the plurality of conical prisms may be provided in a region closer to the light entrance end surface than the plurality of elongated groove-shaped prisms.

Further, the plurality of conical prisms and the plurality of long groove prisms may be provided in a mixed state.

Further, the plurality of conical prisms may be arranged so that the arrangement density increases or is constant as the long groove prisms are separated from the light entrance end surface in a direction perpendicular to the extending direction of the long groove prisms, and the arrangement density increases as the long groove prisms are separated from the light entrance end surface in the perpendicular direction; a rate of change in the arrangement density of the plurality of long groove-shaped prisms per unit length in the orthogonal direction is larger than a rate of change in the arrangement density of the plurality of conical prisms per unit length in the orthogonal direction.

Further, a light absorbing portion having a property of absorbing light may be provided at an end portion facing the light entrance end face.

The refractive index of the light absorbing portion may be 0.86 times or more and 1.14 times or less of the refractive index of the light guide plate material in the portion other than the light absorbing portion.

Further, the plate thickness may become gradually thinner as the distance from the light incident end surface increases.

Further, θ 2 may be 30 ° or more and 50 ° or less.

Further, a condensing lens may be provided at an end portion on the light entrance end surface side.

Further, at least one of the 1 st plate surface and the 2 nd plate surface may be inclined in a direction in which the plate thickness becomes thinner toward the outside in the extending direction of the elongated groove-shaped prism.

Furthermore, the utility model discloses a light guide plate subassembly possesses: the light guide plate; and a reflection plate including a reflection surface facing the 1 st plate surface or the 2 nd plate surface of the light guide plate in the thickness direction.

The reflecting surface may have a property of reflecting light specularly.

Further, the reflecting surface may have irregularities.

Furthermore, the utility model discloses a light guide plate subassembly possesses: the light guide plate; and a pair of reflecting plates, the reflecting surface having a property of causing light to undergo specular reflection; the light guide plate includes a pair of side end surfaces; the pair of reflection plates are disposed outside the pair of side end surfaces so that the reflection surfaces face the side end surfaces.

Furthermore, the utility model discloses a lighting device possesses: a light source; and the light guide plate is used for at least one part of the light emitted from the light source to enter the light.

Furthermore, the utility model discloses a lighting device possesses: a light source; and the light guide plate assembly; at least a part of the light emitted from the light source enters the light guide plate of the light guide plate assembly.

Drawings

Fig. 1 is a perspective view of a lighting device according to an embodiment of the present invention.

Fig. 2 is a schematic configuration diagram of a light source device of the lighting device.

Fig. 3 is a schematic configuration diagram corresponding to fig. 2 of an illumination device of a reference example in which only a light guide plate is different in comparison with the above-described illumination device.

Fig. 4 is a schematic view of a light distribution emitted from the illumination device of the above-described reference example.

Fig. 5 is a schematic view of a light distribution corresponding to fig. 3 of the illumination device shown in fig. 2.

Fig. 6 is a front view of the lighting device according to the modification corresponding to fig. 2 (a).

Fig. 7 is a cross-sectional view of the lighting device according to the modification corresponding to fig. 2 (b).

Fig. 8 is a cross-sectional view of the lighting device according to another modification corresponding to fig. 2 (b).

Fig. 9 is a front view of the lighting device according to another modification corresponding to fig. 2 (a).

Fig. 10 is a front view of the lighting device according to another modification corresponding to fig. 2 (a).

Fig. 11 is a front view of the lighting device according to another modification corresponding to fig. 2 (a).

Fig. 12 is a cross-sectional view showing a part of an illumination device according to another modification.

Fig. 13 is a schematic cross-sectional view of the vicinity of the reflection surface of the reflection plate of the illumination device according to the modification shown in fig. 12.

Fig. 14 is a cross-sectional view of the lighting device according to another modification corresponding to fig. 2 (b).

Fig. 15 is a cross-sectional view of the lighting device according to another modification corresponding to fig. 2 (b).

Fig. 16 is a perspective view of a peripheral region of a light entrance end surface of the illumination device according to the modification shown in fig. 15.

Fig. 17 is a perspective view of a light guide plate according to another modification.

Description of the reference numerals

1. 101, 201, 301, 401, 501, 601, 701, 801 lighting device

10. 110, 210, 310, 410, 510, 710, 810, 910 light guide plate

11 upper side (incident light end)

12. 812, 912 groove

16 LED

17. 117, 217, 317, 417, 517, 617, 717, 917 No. 1 plate surface

20. 120 long groove prism

21 long groove

22 inner surface of the elongated slot

23 outer surface portion

24 extension line

40. 740 conical prism

41 inner peripheral surface

42 holes

43 inner surface

45 outer surface portion

46 extension line

155 bending line

218. 618, 718 2 nd plate surface

685 light guide plate assembly

690 reflecting plate

690a reflecting surface

711. 911 incidence end face

877 condensing lens

Root angle of theta 1 long groove prism

Root angle of theta 2 conical prism

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Further, although 1 embodiment and a plurality of modifications will be described below, it is needless to say that a new embodiment may be constructed by appropriately combining the features thereof. In the following embodiments, the same components are denoted by the same reference numerals in the drawings, and redundant description thereof is omitted. In addition, the drawings include schematic drawings, and the dimensional ratios of the vertical, horizontal, and vertical parts are not necessarily uniform between different drawings. In the present embodiment, a case where the lighting device 1 is a pillar lamp that illuminates the lower side of the passage (the foot side of the passer-by) will be described as an example. However, the technical idea of the present invention can be applied to any lighting device other than the pillar lamp, for example, a ceiling washer (ceiling washer) that illuminates a ceiling or a side wall, a lighting device used in a bracket lamp, a ceiling lamp, or the like. In the description of the drawings and the embodiments, the X direction represents the thickness direction of the light guide plate, the Y direction represents the width direction of the light guide plate, and the Z direction represents the height direction of the light guide plate. The X direction, the Y direction and the Z direction are orthogonal to each other. Among the constituent elements described below, those not recited in the independent claims indicating the uppermost concept are arbitrary constituent elements and not essential constituent elements. In the present specification, the word "substantially" means the same meaning as the word "substantially", and the requirement of "substantially" is satisfied as long as a person substantially looks like it.

Fig. 1 is a perspective view of a lighting device 1 according to an embodiment of the present invention. The lighting device 1 is a so-called pillar lamp (pole light) having a shape of a quadrangular prism having a high height. The lighting device 1 includes a light emitting section 3 on the upper side in the height direction (in the Z direction) of one side surface 2 in the depth direction (in the X direction), the light emitting section 3 having a light emitting surface 3a formed of a substantially rectangular plane, the light emitting surface 3a being formed of a surface of a transparent cover or the like.

The illumination device 1 is disposed outside a passage (not shown) formed by field lanes or the like, for example, such that the light emitting section 3 faces the passage and the width direction (which coincides with the Y direction) of the illumination device 1 substantially coincides with the extending direction of the passage formed by field lanes or the like. The irradiation light from the light emitting section 3 travels along a front lower direction (F direction) inclined downward with respect to the normal direction of the light emitting section 3 and a lamp width direction (W direction) inclined downward with respect to the Y direction toward the extending direction side of the passage. By illuminating the forward traveling direction of the passage with such light distribution, a passer-by can easily confirm the extending direction of the passage.

Fig. 2 is a schematic configuration diagram of the light source device 5 of the lighting device 1. As shown in the front view of fig. 2 (a), the light source device 5 includes an LED substrate 6 and a light guide plate 10. The LED substrate 6 and the light guide plate 10 are fixed to the housing 4 (see fig. 1) of the lighting device 1 via a holder (not shown), and are stationary with respect to the housing 4. The light guide plate 10 is made of an acrylic resin such as PC (polycarbonate) or PMMA (polymethyl methacrylate) resin, or a transparent material such as glass. As shown in fig. 2 (a), the light guide plate 10 has a substantially rectangular plate shape in front view. Referring to fig. 1 and 2 (a), when viewed from the X direction, substantially the entire light-emitting region of the light guide plate 10 overlaps substantially the entire light-emitting surface 3 a. As shown in fig. 2 (a), a plurality of grooves 12 are provided on the upper side surface 11 of the light guide plate 10 on the light source side. The plurality of grooves 12 are arranged adjacent to each other in the Y direction that coincides with the circumferential direction, and each groove 12 extends in the X direction. The upper side 11 constitutes a light entrance end surface. In the example shown in fig. 2 (a), the groove 12 has a V-shape in a YZ cross section including the Y direction and the Z direction, and has a shape of an isosceles triangle or a regular triangle in which the height direction coincides with the Z direction. However, the shape of the groove in the YZ cross section is not limited to the V shape, and may be any shape, for example, a semicircular shape or an isosceles trapezoid shape.

The LED substrate 6 includes a substrate 15 and a plurality of LEDs 16 as a light source. The substrate 15 is formed of, for example, a printed circuit board. The substrate 15 may have any hardness, and may be formed of any one of a rigid substrate, a flexible substrate, and a rigid-flexible bonded substrate. The substrate 15 may have any composition, and may be formed of, for example, a paper phenol substrate, a paper epoxy substrate, a glass composite substrate, a glass epoxy substrate, a teflon (registered trademark) substrate, an alumina (ceramic) substrate, an aluminum substrate, a composite substrate, or the like.

The substrate 15 has an elongated shape and extends along the upper side surface 11 of the light guide plate 10. The substrate 15 is disposed to face the upper side surface 11 in the Z direction in a state where the thickness direction coincides with the Z direction and the longitudinal direction coincides with the Y direction. In the example shown in fig. 2 (b), i.e., the cross-sectional view taken along line a-a of fig. 2 (a), the width direction of the substrate 15 is slightly longer than the thickness direction of the light guide plate 10, and the center position of the substrate 15 in the width direction substantially coincides with the center position of the light guide plate 10 in the thickness direction.

As shown in fig. 2 (a), the plurality of LEDs 16 are mounted on the mounting surface 15a located on the lower side in the Z direction on the substrate 15. The LEDs 16 are arranged at intervals in the Y direction. As shown in fig. 2 (b), all of the LEDs 16 overlap the light guide plate 10 when viewed from the Z direction.

Although not described in detail, the lighting device 1 includes a converter circuit provided on a power supply board (not shown) in the housing 4 (see fig. 1), and converts an external ac power into a dc power by the converter circuit. The converted direct current is supplied to the LED substrate 6. The substrate 15 has, for example, a pair of electrode terminals, and an LED driving circuit formed in a predetermined pattern. The LED driving circuit is a circuit for driving the LEDs 16, and electrically connects the LEDs 16 to each other. When the dc power is supplied to the LED driving circuit via the pair of electrode terminals, a current flows through the LED driving circuit, and the LEDs 16 emit light.

As shown in fig. 2 a and 2 b, the light guide plate 10 includes a 1 st plate surface 17 positioned on one side in the X direction and a 2 nd plate surface (not shown) positioned on the other side in the X direction, and the 1 st plate surface 17 is positioned on the opposite side of the light emitting surface 3a (see fig. 1) of the light guide plate 10. The 1 st plate surface 17 is provided with a plurality of elongated groove prisms 20 and a plurality of conical prisms 40.

The elongated groove prisms 20 are formed by the inner surfaces 22 of the elongated grooves 21, and the extending direction of the plurality of elongated groove prisms 20 substantially coincides with the Y direction. As shown in fig. 2 (a) and 2 (b), the conical prism 40 is formed by an inner peripheral surface 41 on the opening side and an inner surface 43 of a hole 42 formed by a substantially conical inner peripheral surface. As shown in fig. 2 b, in the 1 st cross section of the long groove 21 taken on the XZ plane orthogonal to the extending direction, an angle formed by the inner surface 22 on the opening side of the long groove 21 and an extension 24 of the outer surface portion 23 continuous to the inner surface 22 (hereinafter referred to as a root angle of the elongated groove prism) is θ 1. In the 2 nd cross section of the hole 42 taken on a plane including the center axis of the conical inner peripheral surface, an angle formed by the inner surface 43 of the hole 42 and an extension 46 of the outer surface portion 45 continuous with the inner surface 43 (hereinafter referred to as a root angle of the conical prism) is θ 2. In this case, θ 1< θ 2 holds.

In the embodiment shown in fig. 2 (b), the shape of the hole 42 constituting the conical prism 40 is a conical shape as shown in fig. 2 (c), but the shape of the hole constituting the conical prism may be a truncated conical shape as shown in fig. 2 (d) or a bell-shaped shape as shown in fig. 2 (e). The hole constituting the conical prism may have any shape as long as it has a substantially conical inner peripheral surface on the opening side.

The opening of the long groove constituting the long groove prism 20 may have a racetrack shape as shown in fig. 2 (f), or may have a shape obtained by half-cutting a lemon as shown in fig. 2 (g). As shown in fig. 2 (h), the long groove 21 constituting the long groove prism 20 may be formed by continuously forming a plurality of holes in one direction so that a part of adjacent holes overlaps. The bottom 28 of the long groove may have a sharp shape as shown in fig. 2 (b) or a curved shape. The long groove 21 constituting the long groove prism 20 may have any shape as long as it extends in one direction, which is a linear extending direction.

In the above configuration, if the LED16 emits light, the light emitted from the LED16 toward the Z direction lower side reaches the groove 12 having a V-shaped cross section, is reflected or refracted by the groove 12, and travels in the light guide plate 10 toward the Z direction lower side so as to spread in the Y direction. Further, if the light expanded in the Y direction reaches the long groove prism 20, the light not only has a characteristic of traveling downward in the Z direction so as to be expanded in the Y direction, but also is reflected by the long groove prism 20 toward the 2 nd plate surface side in the thickness direction. As a result, the light reflected by the long groove prism 20 can travel in the lamp width direction indicated by the 2 nd plate surface in the W direction in fig. 1, and light having sufficient brightness can be emitted in the lamp width direction.

As described above, in the illumination device 1, θ 1< θ 2 holds for the root angle θ 1 of the long groove prism 20 and the root angle θ 2 of the conical prism. Further, since the root angle θ 1 of the conical prism 40 is large, the conical prism 40 can reflect the light that has spread in the Y direction and reached in a direction having a small inclination angle (including 0 °) with respect to the X direction. Therefore, the light reaching the conical prism 40 can be made to travel downward in the front direction indicated by the direction F in fig. 1 with high accuracy. This makes it possible to emit the light emitted from the light guide plate 10 to the front lower side of the illumination device 1 where the light reflected by the elongated groove prism 20 does not easily reach.

As a result, the illumination device 1 can irradiate light in the width direction, and can realize illumination light in which the light distribution in the width direction and the light distribution in the front direction are easily made uniform. Further, since the light emitted in the width direction and the light emitted downward from the front surface among the light guided in the light guide plate 10 can be appropriately distributed, the luminance (glare) viewed from the sight position in the width direction can be suppressed, and the downward front surface, which is conventionally easily darkened, can be brightly illuminated with the wide light distribution.

Fig. 3 is a schematic configuration diagram corresponding to fig. 2 of an illumination device 1001 of a reference example different from the illumination device 1 only in the light guide plate 1010, and fig. 4 is a schematic diagram of a light distribution emitted from the illumination device 1001 of the reference example. Fig. 5 is a schematic view of a light distribution of the lighting device 1 corresponding to fig. 4. The light guide plate 1010 of the reference example is similar to the light guide plate 10 in that no prism is provided on the 2 nd plate surface, but is different from the light guide plate 10 in that only a plurality of elongated groove-shaped prisms 1020 are provided on the 1 st plate surface 1017, and no conical prism is provided on the 1 st plate surface 1017.

As shown in a schematic diagram (fig. 4) of the light distribution in the XY cross section shown in fig. 3 (a), in the illumination device 1001 of the reference example, light La in the lamp width direction is emitted with respect to light irradiated from the 2 nd plate surface of the light guide plate toward the passage side, and only light Lb of a small light flux is emitted in the front direction, so that the front direction tends to become dark.

More specifically, in the lighting device of the reference example, the light distribution in the front direction shown in fig. 4 (b), i.e., the sectional view taken along the line H-H in fig. 4 (a), is greatly different from the light distribution in the width direction shown in fig. 4 (c), i.e., the sectional view taken along the line H-K in fig. 4 (a). Specifically, as shown in fig. 4 (c), light Lc traveling upward exists in the light irradiated in the lamp width direction, while as shown in fig. 4 (b), such light Lc traveling upward does not exist in the light irradiated in the front direction. Therefore, in the lighting device of the reference example, a passerby is likely to feel dazzling when seeing the lighting device from the lamp width direction.

In contrast, in the lighting device 1 of the present invention, as shown in fig. 5 (a), light Ld of a large luminous flux is emitted in the front direction, and the luminance of the light Ld emitted in the front direction has the same luminance as the luminance of the light Le emitted in the lamp width direction.

As shown in fig. 4 (c) and 5 (c), in the lighting device 1, the light emitted in the lamp width direction is reduced in the amount of light traveling upward as compared with the lighting device 1001 of the reference example. To describe in more detail, as shown in fig. 5 (b) and 5 (c), in the lighting device 1, the light emitted in the front direction and the light emitted in the width direction have similar light distributions. Therefore, the lighting device 1 can suppress glare when viewed from the lamp width direction and brightly illuminate the front lower side which is easily darkened in the related art, as compared with the lighting device 1001 of the reference example, that is, the lighting device 1001 including the light guide plate 1010 having only the long groove prisms 1020.

Hereinafter, the structure and the operational effects of the light guide plate of the illumination device according to the modified example, which are different from those of the above-described embodiment, will be described. In each modification, the same operational effects as those of the above embodiment will not be described.

Fig. 6 is a front view of the lighting device 101 according to the modification corresponding to fig. 2 (a). In addition to this, the present invention is,

fig. 7 is a cross-sectional view of the lighting device 101 of the modification corresponding to fig. 2 (b). In the lighting device 1, as shown in fig. 2 (a), both ends 55 in the extending direction of the opening of the long groove prism 20 provided in the light guide plate 10 are straight lines extending in the Z direction, and both end surfaces in the extending direction of the long groove prism 20 are flat surfaces. In contrast, as shown in fig. 6, in the lighting device 101, both ends 121 in the extending direction of the opening of the long-groove-shaped prism 120 provided in the light guide plate 110 are curved lines 155 that are convex outward in the extending direction, and both end surfaces in the extending direction of the long-groove-shaped prism 120 are curved surfaces.

If both ends of the elongated-groove-shaped prism 20 in the extending direction of the opening are flat, the accuracy of control for reflecting light in the lamp width direction can be improved, and on the other hand, luminance unevenness such as a stripe pattern may occur. In contrast, according to the present modification, since both end surfaces of the elongated groove-shaped prism 120 in the extending direction are curved surfaces, the light reaching the curved surfaces can be diffused by the curved surfaces. This can suppress the occurrence of luminance unevenness such as a stripe pattern.

As shown in fig. 7, in the light guide plate 110, the plurality of elongated groove prisms 120 and the plurality of conical prisms 40 are provided only on the 1 st plate surface 117. Therefore, the prisms 120 and 40 may be formed only on one surface of the light guide plate 110, and thus the processing of the light guide plate 110 can be easily performed.

Fig. 8 is a cross-sectional view of the lighting device 201 according to another modification corresponding to fig. 2 (b). As shown in fig. 8, in the lighting device 201, the plurality of long groove prisms 20 are provided on the 1 st plate surface 217 of the light guide plate 210, and the plurality of conical prisms 40 are provided on the 2 nd plate surface 218 of the light guide plate 210. The light guided in the light guide plate 210 includes light reflected by the elongated groove prisms 20 and emitted in the lamp width direction. This modification is preferably employed when the light reflected by the long-groove prism 20 travels in the light direction to be controlled. Further, according to the present modification, since the prisms having different processing methods are provided on different surfaces, the prisms 20 and 40 provided on the surfaces 217 and 218 are the same, and the prisms 20 and 40 can be easily formed.

Fig. 9 is a front view of an illumination device 301 according to another modification corresponding to fig. 2 (a). As shown in fig. 9, in the illumination device 301, the plurality of conical prisms 40 are provided in a region closer to the upper side surface (light entrance end surface) 11 than the plurality of long groove-shaped prisms 120 with respect to the 1 st plate surface 317 of the light guide plate 310.

With respect to the region closer to the LED16, the light quantity of light guided in the light guide plate 310 is large. Further, the long groove prism 120 has good controllability of light in the lamp width direction. Therefore, if the elongated groove prism 120 is disposed in a region closer to the upper side surface 11 where the amount of light guided is large, light having excessively high brightness tends to be emitted in the width direction of the lamp, and a person tends to feel dazzling. In contrast, since the conical prism 40 reflects light toward a narrow region in the front direction, a person is less likely to feel glare even when the conical prism is disposed in a region closer to the upper side surface 11 where the amount of light guided is large. Thus, with this configuration, the light distribution in the width direction can be reduced, the glare when the light emitting surface of the illumination device 301 is viewed from the width direction can be suppressed, and soft and comfortable wide light can be easily realized.

Fig. 10 is a front view of an illumination device 401 according to another modification corresponding to fig. 2 (a). As shown in fig. 10, in the lighting device 401, the plurality of conical prisms 40 and the plurality of long groove prisms 120 are provided in a mixed state on the 1 st plate surface 417 of the light guide plate 410.

Since the light guide plate 410 is transparent, when a person views the light emitting surface of the lighting device 401, the conical prism 40 and the long groove prism 120 can be recognized, and the difference between these prisms 40 and 120 can be recognized. Therefore, when the plurality of conical prisms 40 and the plurality of elongated groove prisms 120 are provided in different regions, a person may recognize the difference between the regions of the light-emitting surface and feel a discrepancy.

In contrast, according to the present modification, since the plurality of conical prisms 40 and the plurality of long groove-shaped prisms 120 are provided in a mixed state, when a person sees the light emitting surface, the person does not feel the region division due to the difference in prism shape. This can improve the appearance of the lighting device 401.

Fig. 11 is a front view of an illumination device 501 according to another modification corresponding to fig. 2 (a). As shown in fig. 11, in the illumination device 501, the plurality of conical prisms 40 are provided in a region closer to the upper side surface (light entrance end surface) 11 than the plurality of elongated groove-shaped prisms 120 with respect to the 1 st plate surface 517 of the light guide plate 510. In the orthogonal direction orthogonal to the extending direction of the long groove-shaped prisms 120, the plurality of conical prisms 40 are arranged so that the arrangement density increases or becomes uniform as they are separated from the upper side surface (light entrance end surface) 11. The extending direction coincides with the Y direction, and the orthogonal direction coincides with the Z direction. In the orthogonal direction, the plurality of long groove prisms 120 are arranged so that the arrangement density increases as the distance from the upper side surface 11 increases. The rate of change in the arrangement density of the plurality of long groove prisms 120 per unit length in the orthogonal direction is greater than the rate of change in the arrangement density of the plurality of conical prisms 40 per unit length in the orthogonal direction.

According to the present modification, since the plurality of conical prisms 40 are provided in the region closer to the upper side surface (light entrance end surface) 11 than the plurality of elongated groove-shaped prisms 120, the glare when the light emitting surface of the illumination device 501 is viewed from the width direction can be reduced as described above.

Further, the light quantity of the light guided to the Z direction lower side in the light guide plate 510 decreases from the upper side surface 11 toward the Z direction lower side. In such a background, the plurality of long groove prisms 120 are arranged so that the arrangement density increases with distance from the upper side surface 11 with respect to the orthogonal direction, and the rate of change per unit length of the long groove prisms 120 is larger than the rate of change per unit length of the conical prism 40. Therefore, the density of the long groove prisms 120 increases as the light quantity decreases, and therefore, the light quantity of the broad light emitted from the unit area on the 2 nd plate surface of the light guide plate 510 is easily made to be close to the same value regardless of the height position of the emission position. This makes it easy to reduce local variations in luminance on the light emitting surface and to suppress luminance unevenness.

Fig. 12 is an XZ cross-sectional view showing a part of an illumination device 601 according to another modification. As shown in fig. 12, the illumination device 601 may include a light guide plate assembly 685, the light guide plate assembly 685 may include a light guide plate 110 and a reflection plate 690, and the reflection plate 690 may include a reflection surface 690a facing the 1 st plate surface 617 or the 2 nd plate surface of the light guide plate 110 in the X direction.

With this configuration, the amount of light emitted from the 2 nd plate surface 618 on the opposite side of the side facing the reflection surface 690a in the light guide plate 110 can be made about 2 times. This enables bright light to be emitted from the illumination device 601. In the light guide plate of the present invention, the light distribution of the light emitted from the back surface (the surface on which the irradiation of the light is not assumed) is similar to the light distribution of the light emitted from the front surface (the surface on which the irradiation of the light is assumed). Thus, by reflecting the light emitted from the rear surface, the light distribution of the light emitted from the front surface can be emphasized and made conspicuous.

In the configuration shown in fig. 12, the reflecting surface 690a of the reflecting plate 690 may have a property of specularly reflecting light.

When the reflecting surface of the reflector is a reflecting surface having a property of diffusing light, the light reflected by the reflecting surface may act to cancel out a desired light distribution of the control light emitted from the surface of the light guide plate. In contrast, according to the above configuration, since the reflecting surface 690a of the reflector 690 has a property of reflecting light from the mirror surface, the distribution of light emitted from the surface can be made more conspicuous with higher emphasis.

In the configuration shown in fig. 12, the reflection surface 690a of the reflection plate 690 may have irregularities. Specifically, referring to fig. 13, which is a schematic cross-sectional view of the XY cross-section near the reflecting surface of the reflector 690, the inclination angle α is defined as an angle formed by a direction orthogonal to the central axis of the recess 695 and a side surface portion on the opening side of the recess 695 in a cross-section including the central axis of the recess 695. In this case, it is preferable that the concave portions 695 and the convex portions 696 having an inclination angle α of about 10 ° to 20 ° be provided on the reflecting surface 690a of the reflecting plate 690.

Since the light guide plate 110 is transparent, if the reflection plate 690 is disposed parallel to the light guide plate 110, a part of a human body or the like is likely to be reflected on the reflection surface 690a, which is not preferable. According to this configuration, since the reflection surface 690a of the reflection plate 690 has irregularities, such reflection can be prevented. Such reflection can be reliably prevented if the inclination angle α is 10 ° or more, and light distribution controllability is not impaired if the inclination angle α is 20 ° or less. Accordingly, if the inclination angle α is 10 ° to 20 °, the appearance quality of the light emitting surface 3a (see fig. 1) can be improved without impairing the light distribution controllability.

Although not shown, the light guide plate unit of the illumination device of the present invention may include a light guide plate and a pair of reflection plates having a reflection surface with a property of reflecting light from the light mirror surface. The light guide plate may include a pair of side end surfaces (a pair of side end surfaces corresponding to the pair of side end surfaces indicated by 70a and 70b in fig. 2 a) extending substantially in parallel to a direction orthogonal to the extending direction of the elongated groove-shaped prism. The pair of reflection plates may be disposed outside the pair of side end surfaces such that the reflection surfaces face the side end surfaces in the extending direction.

According to this configuration, the light leaking from the side end surface can be returned into the light guide plate without losing the light distribution property at the time of leakage. Therefore, diffuse reflection of light re-incident from the side end surface can be reduced to improve light extraction efficiency, and light distribution controllability can be improved.

Although not shown, the light guide plate may include a light absorbing portion having a property of absorbing light at an end portion facing a light entrance end surface through which light from the light source enters.

Such a light guide plate can be formed by integrally molding a light-transmitting resin material made of only a material other than the light absorbing portion of the light guide plate and a resin material obtained by mixing a black paint into the resin material by two-color molding of injection molding, for example. Alternatively, such a light guide plate can be formed by bonding a material having a refractive index close to that of a portion of the light guide plate other than the light absorbing portion and having a property of absorbing light to the light absorbing portion in an optically close state. The optical close contact means close contact without an air layer therebetween. Alternatively, the end portion facing the light incident end face may be coated with black, and the black-coated portion may be used as the light absorbing portion.

For example, when a light guide plate is mounted on a pillar lamp that illuminates the foot of a person, if light entering from a light entrance end surface on the upper side of the lighting device reaches an end surface on the opposite side of the light guide direction and is reflected at the end surface, the light is guided to the upper side in the light guide plate, and thus, irradiation light based on the light is emitted obliquely upward. However, such light is a cause of dazzling, and therefore must be prevented.

In contrast, according to the present structure, the light absorbing portion absorbs light that enters from the light entrance end face and reaches the end face on the opposite side. This can suppress reflection of light incident from the light incident end surface and reaching the end surface on the opposite side toward the opposite side, and can suppress light from being emitted obliquely upward.

The refractive index of the light absorbing portion may be smaller than 0.86 times or larger than 1.14 times the refractive index of the light guide material in the portion other than the light absorbing portion. However, the refractive index of the light absorbing portion is preferably 0.86 times or more and 1.14 times or less the refractive index of the light guide material in the portion other than the light absorbing portion. If the refractive index of the light absorbing portion is significantly different from that of the light guide plate, light is reflected at the interface between the light guide material portion other than the light absorbing portion in the light guide plate and the light absorbing portion, and the light absorbing portion cannot efficiently absorb light. According to this configuration, since the refractive index of the light absorbing portion is 0.86 times or more and 1.14 times or less the refractive index of the portion of the light guide material other than the light absorbing portion, the light absorbing portion for light reaching the opposite side to the light incident end face can be efficiently absorbed.

Fig. 14 is a cross-sectional view of an illumination device 701 according to another modification corresponding to fig. 2 (b). In fig. 14, reference numeral 740 denotes a conical prism. As shown in fig. 14, the thickness of the light guide plate 710 gradually becomes thinner as it is farther from the light entrance end surface 711. More specifically, the thickness of the light guide plate 710 gradually decreases as the light entrance end surface 711, which enters light from the LED16, moves away in the direction (Z direction) perpendicular to the extending direction (Y direction) of the elongated groove-shaped prism 720.

If the 1 st and 2 nd plate surfaces 717 and 718 of the light guide plate 710 are inclined at the inclination angle β with respect to the light guiding direction, the light guided in the light guide plate 710 is emitted from the 1 st and 2 nd plate surfaces 717 and 718. According to the above configuration, the light extraction efficiency can be improved. Further, light reaching the end face 794 on the opposite side to the light entrance end face 711 can be reduced, and light emitted obliquely upward, which is a cause of glare, can be reduced.

Fig. 15 is a cross-sectional view of the illumination device 801 according to another modification corresponding to fig. 2 (b), and fig. 16 is a perspective view of a peripheral region of the light entrance end face 811. As shown in fig. 16, the light guide plate 810 may be provided with a condensing lens 877 at an end 888 on the light entrance end surface side. More specifically, the pair of condensing lenses 877 may be provided on both sides of the groove 812 in the X direction at the end 888 on the light entrance end surface side. Alternatively, although not shown, the condenser lens may be provided only on one side in the X direction of the groove at the end on the light entrance end surface side.

In a light guide plate without a condenser lens, light emitted from an LED in a direction inclined at a large angle with respect to the light guiding direction of the light guide plate enters from an end portion on the light entrance end surface side of the light guide plate, and is guided in the light guide plate with a large inclination angle in the thickness direction of the light guide plate. Such light is likely to cause glare. According to this configuration, the traveling direction of light emitted in a direction having a large inclination angle in the thickness direction with respect to the light guiding direction of the light guide plate 810 can be changed to a traveling direction having a small inclination angle in the thickness direction with respect to the light guiding direction by the condenser lens 877. Therefore, the upward traveling light causing glare can be reduced without impairing the controllability of the light distribution in the lamp width direction.

Fig. 17 is a perspective view of a light guide plate 910 according to another modification. In fig. 17, reference numeral 911 denotes a light entrance end surface, and 912 denotes a groove provided at the light entrance end surface. As shown in fig. 17, the 1 st plate surface 917 of the light guide plate 910 is inclined in a direction in which the plate thickness becomes thinner toward the outside in the extending direction of the elongated groove-shaped prisms. Alternatively, although not shown, at least one of the 1 st and 2 nd plate surfaces of the light guide plate may be inclined in a direction in which the plate thickness becomes thinner toward the outside in the extending direction of the elongated groove-shaped prisms.

As described above, the light is emitted from the light guide plate surface in a direction in which the thickness thereof becomes smaller according to the inclination angle with respect to the outer surface of the 1 st plate surface 917 of the light guide plate 910. Therefore, in the light guide plate 910, light tends to leak in the lamp width direction shown by the arrows B and C and close to the light guide plate 910. Thus, if the light guide plate 910 is used, the light distribution in the lamp width direction can be enhanced.

In the light guide plate of the present invention, the root angle θ 2 of the conical prism may be any angle larger than 0 ° and smaller than 90 °. However, if the root angle θ 2 of the conical prism is set to 30 ° or more and 50 ° or less, the light can be reflected more accurately downward toward the front by the conical prism. Therefore, the conical prism for light distribution in the light distribution region that cannot be controlled by the elongated groove-shaped prism can be efficiently controlled, and the complementarity of the light distribution by the conical prism can be improved.

In the light guide plate of the present invention, the 1 st plate surface may be provided with only a plurality of long groove prisms extending in the same direction, and the 2 nd plate surface may be provided with a plurality of long groove prisms extending in the same direction and a plurality of conical prisms. In addition, only a plurality of conical prisms may be provided on the 1 st plate surface, and a plurality of long groove prisms extending in the same direction may be provided on the 2 nd plate surface to provide a plurality of conical prisms. Further, a plurality of long groove prisms extending in the same direction and a plurality of conical prisms may be provided on each of the 1 st plate surface and the 2 nd plate surface.

Further, a plurality of conical prisms including 2 or more conical prisms having different sizes or shapes may be provided on the 1 st plate surface. Alternatively, the 1 st plate surface may be provided with a plurality of long groove prisms including 2 or more long groove prisms having different sizes or shapes.

The 1 st plate surface may be a surface (front surface) on which irradiation light is supposed to be emitted, or a surface (back surface) on which irradiation light is not supposed to be emitted. The 2 nd plate surface may be a surface (front surface) on which irradiation light is supposed to be emitted, or a surface (back surface) on which irradiation light is not supposed to be emitted. For example, when a bar lamp is provided to a separation zone of 2 paths and 2 paths are simultaneously illuminated by the bar lamp, both the 1 st plate surface and the 2 nd plate surface become surfaces (surfaces) where irradiation light is supposed to be emitted.

Claims (19)

1. A light guide plate having a plate-like shape including a 1 st plate surface located on one side in a thickness direction and a 2 nd plate surface located on the other side in the thickness direction,

the disclosed device is provided with:

a light incident end surface provided with a plurality of grooves which are arranged adjacent to each other in a circumferential direction and extend in the thickness direction;

a plurality of long groove prisms provided on at least one of the 1 st plate surface and the 2 nd plate surface at intervals; and

a plurality of conical prisms provided on at least one of the 1 st plate surface and the 2 nd plate surface at intervals;

the elongated groove prisms are formed by inner surfaces of elongated grooves, and extending directions of the elongated groove prisms are substantially the same;

the conical prism is formed by the inner surface of a hole with the inner surface of a roughly conical inner surface on the opening side;

in a 1 st cross section taken on a plane orthogonal to an extending direction of the long groove, an angle formed by an inner surface of the opening side of the long groove and an extension line of an outer surface portion continuous to the inner surface is θ 1, and in a 2 nd cross section taken on a plane including a center axis of the conical inner circumferential surface of the hole, an angle formed by an inner surface of the hole and an extension line of an outer surface portion continuous to the inner surface is θ 2, θ 1< θ 2 is satisfied.

2. The light guide plate according to claim 1,

both ends of the opening of the long-groove prism in the extending direction are bent lines protruding outward in the extending direction.

3. The light guide plate according to claim 1,

the plurality of long groove prisms and the plurality of conical prisms are provided on the 1 st plate surface.

4. The light guide plate according to claim 1,

the plurality of long groove prisms are provided on the 1 st plate surface, and the plurality of conical prisms are provided on the 2 nd plate surface.

5. The light guide plate according to claim 3,

the plurality of conical prisms are provided in a region closer to the light entrance end surface than the plurality of elongated groove-shaped prisms.

6. The light guide plate according to claim 3,

the plurality of conical prisms and the plurality of long groove prisms are provided in a mixed state.

7. The light guide plate according to claim 5,

the plurality of conical prisms are arranged so that the arrangement density increases or is constant as the long groove prisms are separated from the light entrance end surface in a direction perpendicular to the extending direction of the long groove prisms, and the arrangement density increases as the long groove prisms are separated from the light entrance end surface in the perpendicular direction;

a rate of change in the arrangement density of the plurality of long groove-shaped prisms per unit length in the orthogonal direction is larger than a rate of change in the arrangement density of the plurality of conical prisms per unit length in the orthogonal direction.

8. The light guide plate according to claim 1,

a light absorbing portion having a property of absorbing light is provided at an end portion facing the light entrance end surface.

9. The light guide plate according to claim 8,

the refractive index of the light absorbing section is 0.86 times or more and 1.14 times or less of the refractive index of the light guide plate material in the portion other than the light absorbing section.

10. The light guide plate according to claim 1,

the plate thickness becomes gradually thinner as the distance from the light incident end surface becomes larger.

11. The light guide plate according to claim 1,

the above θ 2 is 30 ° or more and 50 ° or less.

12. The light guide plate according to claim 1,

a condensing lens is provided at an end portion on the light entrance end surface side.

13. The light guide plate according to claim 1,

at least one of the 1 st plate surface and the 2 nd plate surface is inclined in a direction in which the plate thickness becomes thinner toward the outside in the extending direction of the elongated groove-shaped prism.

14. A light guide plate assembly, characterized in that,

the disclosed device is provided with:

the light guide plate of claim 1; and

and a reflection plate including a reflection surface facing the 1 st plate surface or the 2 nd plate surface of the light guide plate in the thickness direction.

15. The light guide plate assembly of claim 14,

the reflecting surface has a property of reflecting light specularly.

16. The light guide plate assembly according to claim 15,

the reflection surface has irregularities.

17. A light guide plate assembly, characterized in that,

the disclosed device is provided with:

the light guide plate of claim 1; and

a pair of reflecting plates, the reflecting surfaces having a property of causing light to undergo specular reflection;

the light guide plate includes a pair of side end surfaces;

the pair of reflection plates are disposed outside the pair of side end surfaces so that the reflection surfaces face the side end surfaces.

18. A lighting device is characterized in that a lamp body is provided,

the disclosed device is provided with:

a light source; and

the light guide plate according to claim 1, wherein at least a part of the light emitted from the light source enters the light guide plate.

19. A lighting device is characterized in that a lamp body is provided,

the disclosed device is provided with:

a light source; and

a light guide plate assembly as claimed in any one of claims 14 to 17;

at least a part of the light emitted from the light source enters the light guide plate of the light guide plate assembly.

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