JP2020009556A - Planar lighting device - Google Patents

Abstract

To provide a planar lighting device capable of improving uniformity of luminance.SOLUTION: A planar lighting device includes a plurality of light sources, a light guide plate and an optical selection member. The light guide plate includes: an incident surface which is a main surface where an optical element is formed and where the light of the light source enters; and an emission surface which is a main surface on the opposite side from the incident surface, and which emits the light which has entered from the incident surface. The optical selection member is arranged in parallel on the emission surface side with respect to the light guide plate, and has angle dependence in which the reflectivity becomes lower as an incident angle of the light with respect to a light incident surface where the light emitted from the light guide plate enters is substantially further in parallel with the light incident surface.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a planar lighting device.

  2. Description of the Related Art Conventionally, a planar illumination device that is also called a backlight and illuminates a display panel of a liquid crystal display device from the back side has been known. As a planar lighting device as a backlight, for example, there is a direct-type planar lighting device in which a plurality of light sources are arranged immediately below a light guide plate (for example, see Patent Document 1).

JP 2012-138345 A

  However, in the conventional technology, the brightness of the light emitting surface immediately above the light source is higher than that of the area immediately above the light source.

  The present invention has been made in view of the above, and an object of the present invention is to provide a spread illuminating apparatus capable of improving the uniformity of luminance.

  In order to solve the above-described problem and achieve the object, a planar lighting device according to one embodiment of the present invention includes a plurality of light sources, a light guide plate, and a light selection member. The light guide plate is a main surface on which an optical element is formed, an incident surface on which light from the light source is incident, and a main surface opposite to the incident surface, and emits light incident from the incident surface. An emission surface. The light selection member is arranged in parallel with the light exit surface side with respect to the light guide plate, and an incident angle of the light with respect to a light entrance surface on which light emitted from the light guide plate enters is an angle substantially parallel to the light entrance surface. The lower the reflectance, the lower the angle dependency.

  According to one embodiment of the present invention, luminance uniformity can be improved.

FIG. 1 is a front view of the spread illuminating apparatus according to the first embodiment. FIG. 2 is an exploded perspective view of the planar lighting device according to the first embodiment. FIG. 3 is a cross-sectional view of the spread illuminating apparatus according to the first embodiment. FIG. 4 is a bottom view of the light guide plate according to the first embodiment. FIG. 5 is a cross-sectional view of the light guide plate according to the first embodiment. FIG. 6 is an exploded perspective view of a two-member optical member according to a modification. FIG. 7 is a cross-sectional view of the spread illuminating apparatus according to the second embodiment. FIG. 8 is a top view of the light selection member according to the second embodiment. FIG. 9 is a cross-sectional view of the light selection member according to the second embodiment. FIG. 10 is a top view of a light selection member and an optical member according to a modification of the second embodiment.

  Hereinafter, a planar lighting device according to an embodiment will be described with reference to the drawings. Note that the relationship between dimensions of each element in the drawings, the ratio of each element, and the like may be different from reality. Even in the drawings, there may be cases where portions having different dimensional relationships and ratios are included. In addition, in each drawing, a three-dimensional orthogonal coordinate system in which the light emission direction of the planar illumination device is set to the positive direction of the Z-axis may be illustrated for easy understanding.

  Hereinafter, the first embodiment and the second embodiment will be described. In the first embodiment, the light selecting member 9 is a sheet member formed of a dielectric multilayer film, and in the second embodiment, the case where the light selecting member 9 is a prism sheet will be described as an example.

  First, an outline of the spread illuminating apparatus according to the first embodiment will be described with reference to FIGS. FIG. 1 is a front view of the spread illuminating apparatus 1 according to the first embodiment. FIG. 2 is an exploded perspective view of the planar lighting device 1 according to the first embodiment. FIG. 3 is a cross-sectional view of the planar lighting device 1 according to the first embodiment.

  The spread illuminating device 1 shown in FIGS. 1 to 3 is used, for example, as a backlight of a liquid crystal display device. Such a liquid crystal display device is, for example, a vehicle-mounted device (a navigation device, a digital meter, an indicator, or the like), or a terminal device such as a smartphone.

  As shown in FIGS. 1 to 3, the spread illuminating apparatus 1 according to the first embodiment includes a light source 2, a substrate unit 3, a frame 4, a light guide plate 5, a wavelength conversion member 6, and a diffusion member. 7, an optical member 8 and a light selecting member 9. As shown in FIG. 1, the spread illuminating apparatus 1 according to the first embodiment has a light emitting region R surrounded by a frame 4 when viewed from above, and Z is an emission direction from the light emitting region R. By emitting light in the positive direction of the axis, it functions as a backlight of a liquid crystal display device (not shown).

  The light source 2 is, for example, an LED (Light Emitting Diode). The light source 2 as an LED emits light including a blue light wavelength band, for example. Alternatively, the light source 2 as an LED may be a light source that emits white light. Specifically, the light source 2 is composed of an LED that emits blue light and a phosphor that emits red light and green light using blue light as excitation light, and a pseudo white light including blue, red, and green wavelengths. Emits. The phosphor may be a phosphor that emits yellow light using blue light as excitation light, or a phosphor that emits light of another color.

  Further, as shown in FIGS. 1 to 3, the light source 2 is provided on the rear surface side of the light guide plate 5, which will be described later, that is, on the negative side of the Z-axis. It is coaxial with the emission direction (Z-axis positive direction). That is, the planar lighting device 1 according to the embodiment is a so-called direct type.

  In addition, as shown in FIG. 1, the plurality of light sources 2 are arranged in, for example, a lattice shape when viewed from the front in the Z-axis positive direction. Specifically, the plurality of light sources 2 are two-dimensionally arranged along each of the longitudinal direction (X-axis direction) and the lateral direction (Y-axis direction) of the planar lighting device 1 in a front view. Note that the plurality of light sources 2 is not limited to the case where they are arranged in a lattice, and may be in any arrangement. That is, the plurality of light sources 2 may be arranged other than a lattice having a certain regularity such as a lattice, or may be an irregular arrangement.

  The substrate unit 3 is a member on which the plurality of light sources 2 are provided, and is a member on which the substrate 3a and the reflecting member 3b are stacked. The substrate 3 a is, for example, a flexible substrate (FPC: Flexible Printed Circuit), and supplies power supplied from an external power supply (not shown) to the light source 2. The light source 2 is mounted on the substrate 3a on the one main surface 3a1 side which is the positive side in the Z axis direction. That is, the main surface 3a1 of the substrate 3a is a mounting surface on which the light source 2 is mounted (hereinafter, referred to as a mounting surface 3a1).

  The reflection member 3b is provided between the substrate 3a and the light source 2 so as to cover the mounting surface 3a1. The reflecting member 3b reflects light leaked from the light guide plate 5 described later to the side of the reflective member 3b which is the negative side of the Z-axis and returns the light to the light guide plate 5. For example, a white member can be adopted as the reflection member 3b.

  The frame 4 is, for example, a frame member made of resin or metal, and surrounds the reflection member 3b, the light guide plate 5, the wavelength conversion member 6, the diffusion member 7, the optical member 8, and the light selection member 9. In addition, the end of the frame 4 on the substrate 3a side, which is the Z-axis negative direction side, is provided on the substrate 3a via an insulating member (not shown). Specifically, the end of the frame 4 is provided at the peripheral end of the main surface of the substrate 3a on which the reflecting member 3b is provided.

  The light guide plate 5 is a plate-shaped member made of, for example, a transparent material (for example, polycarbonate resin), and is a member that takes in light emitted from the light source 2 and guides it, converts it into planar light, and emits light. . Specifically, the light guide plate 5 receives light from the light source 2 from one main surface 5a (hereinafter, referred to as an incident surface 5a) facing the mounting surface 3a1 of the substrate 3a, and is opposite to the main surface 5a. Light is emitted from the other main surface 5b on the side (hereinafter, referred to as an emission surface 5b).

  An optical element 5a1 is formed on the incident surface 5a of the light guide plate 5. The optical element 5a1 is, for example, a prism in the present embodiment, and divides light in a plurality of directions by refracting a part of the light when the light from the light source 2 is incident from the incident surface 5a. This makes it possible to suppress the luminance immediately above the light source 2 on the positive Z-axis direction, and to improve the uniformity of the luminance. The details of the optical element 5a1 will be described later.

  In addition, a projecting portion 5b1 (dot in the present embodiment) projecting from the emission surface 5b is formed on the emission surface 5b of the light guide plate 5. The protruding portions 5b1 are densely arranged away from the upper portion of the light source 2 in the Y-axis direction. Specifically, the distance between the protrusions 5b1 becomes smaller as the distance from the light source 2 in the surface direction (X-axis direction or Y-axis direction) of the emission surface 5b increases. That is, the protruding portion 5b1 is sparsely arranged closer to the upper portion of the light source 2. In addition, although the case where the protruding portion 5b1 is a portion that protrudes in the thickness direction of the light guide plate 5 is shown, the protruding portion 5b1 may be a portion that is recessed in the thickness direction of the light guide plate 5.

  The light selection member 9 is formed of, for example, a dielectric multilayer film, and is stacked in parallel with the light guide plate 5 on the emission surface 5b side that is the positive Z-axis direction side. The light selection member 9 has, for example, an angle dependence with respect to the light emitted from the light guide plate 5. The angle dependency will be described later.

  Here, a conventional planar lighting device will be described. In the conventional planar lighting device, when a light source is disposed immediately below a light guide plate, the luminance immediately above the light source (on the positive side in the Z-axis direction) is higher than that immediately around the light source, so that the uniformity of luminance is reduced. There was a fear.

  Therefore, the spread illuminating apparatus 1 according to the first embodiment includes the light selecting member 9 having an angle dependency. Specifically, the light-selecting member 9 has a lower angle-dependent reflectivity as the incident angle of the light with respect to the light incident surface 9a where the light enters is substantially parallel (Y-axis direction) to the light incident surface 9a. Having.

  In other words, due to the angle dependence of the light selection member 9, the light emitted from the light guide plate 5 has a relatively high reflectance when incident on the light incident surface 9a at an incident angle close to perpendicular. Therefore, the light is reflected and returns to the light guide plate 5. On the other hand, when the light emitted from the light guide plate 5 is incident on the light incident surface 9a at an incident angle close to being substantially parallel, the light selection member has a relatively low reflectance, that is, a high transmittance. 9 is transmitted.

  That is, the angle-dependent light selecting member 9 reflects the light traveling to the upper portion of the light source 2 and transmits the light traveling to the peripheral portion distant from directly above the light source 2. Thereby, the brightness can be suppressed immediately above the light source 2 and the brightness can be increased in the peripheral portion, so that the uniformity of the brightness can be improved as a whole.

  Here, the light selection member 9 will be further described with reference to FIG. FIG. 3 shows the optical paths of the light beams L1 and L2 emitted from the light source 2. Note that the light L1 is light emitted directly above the light source 2, and the light L2 is light emitted to the periphery of the light source 2.

  First, the light L1 will be described. As shown in FIG. 3, the light L1 emitted from the light source 2 is first incident on the light guide plate 5 via the optical element 5a1, and is emitted from the emission surface 5b.

  At this time, most of the light L1 emitted immediately above the light source 2 is emitted from the emission surface 5b where the protrusions 5b1 are sparsely arranged, and a part (not shown) of the light L1 is emitted by the emission surface 5b. The light is reflected and returns to the reflecting member 3b. Further, since the light L1 emitted from the emission surface 5b enters the light selection member 9 at a substantially perpendicular incident angle, the light L1 is reflected by the angle dependence of the light selection member 9 and returns to the light guide plate 5.

  Then, the light L1 returned to the light guide plate 5 is refracted by the optical element 5a1 when exiting from the incident surface 5a. Then, the light L1 emitted from the incident surface 5a of the light guide plate 5 is reflected by the reflecting member 3b of the substrate unit 3, and enters the light guide plate 5 from the incident surface 5a again via the optical element 5a1.

  Subsequently, when the light L1 is emitted again from the emission surface 5b, it is transmitted by the protruding portion 5b1. Then, the light L1 emitted from the emission surface 5b enters the light selection surface 9a of the light selection member 9 at an incidence angle close to an angle substantially parallel to the light incidence surface 9a, and thus passes through the light selection member 9.

  As described above, the light selection member 9 reflects the light L1 emitted from directly above the light source 2 and transmits the light L1 emitted from the vicinity immediately above the light source 2 in the light guide plate 5, so that the brightness just above the light source 2 is increased. Since the brightness is increased in the vicinity immediately above while suppressing the brightness, the uniformity of the brightness can be improved as a whole. That is, since the light L1 is reflected by the light selecting member 9, the incident angle when the light L1 is again incident on the light selecting member 9 can be increased, so that the amount of light emitted to the vicinity immediately above can be increased. Brightness uniformity can be improved.

  Next, the light L2 will be described. The light L2 emitted from the light source 2 is first refracted and incident on the light guide plate 5 via the optical element 5a1. Then, the light L2 incident on the light guide plate 5 is reflected by the emission surface 5b to guide the light inside the light guide plate 5. Specifically, the light L2 is reflected by the emission surface 5b of the light guide plate 5 toward the reflection member 3b.

  Then, while the light L2 is guided in a direction away from the light source 2, a part of the light L2 exits from the incident surface 5a. The light L2 emitted from the incident surface 5a is reflected by the reflecting member 3b, and again enters the light guide plate 5 from the incident surface 5a via the optical element 5a1. Then, the light L <b> 2 hits the protrusion 5 b 1, is transmitted by the protrusion 5 b 1, and is emitted from the light guide plate 5.

  Then, after the light L2 is emitted from the emission surface 5b of the light guide plate 5, it passes through the light selection member 9 and is emitted. As described above, the light L2 guided through the light guide plate 5 and emitted can improve the uniformity of luminance.

  In addition, a projecting portion 5b1 protruding from the light emitting surface 5b is formed on the light emitting surface 5b of the light guide plate 5, and the projecting portions 5b1 are densely arranged so as to be further away from a position directly above the light source 2 in the Y-axis direction. As a result, a part of the light L2 guided inside the light guide plate 5 hits the protruding portion 5b1 densely arranged right above the light source 2 and is transmitted to the vicinity right above the light source 2. Therefore, the uniformity of the luminance can be improved while suppressing the luminance immediately above the light source 2.

  Although FIG. 3 illustrates the case where the light source 2 emits blue light, the present invention is applicable to, for example, the case where the light source 2 emits white light. When the light source 2 emits white light, a wavelength conversion member 6 described later may be omitted.

  The wavelength conversion member 6 is a wavelength conversion member having a phosphor that emits red light and green light when excited by the light L (for example, blue light) of the light source 2. Specifically, the wavelength conversion member 6 emits pseudo white light including the wavelength of the blue light, which is the light L transmitted through the light selection member 9, and the red light and the green light excited by the blue light. . The wavelength conversion member 6 may be configured to excite yellow light by blue light and emit white light, or may be configured to emit light of another color. Further, the wavelength conversion member 6 may be made of quantum dots.

  The diffusion member 7 diffuses light emitted from the wavelength conversion member 6. The diffusing member 7 emits the diffused light to the optical member 8 on the positive side of the Z axis.

  The optical member 8 is a member that performs optical adjustment such as light distribution control such as uniformizing and condensing the light diffused by the diffusion member 7. Specifically, the optical member 8 is a prism sheet having a prism 81 on the main surface on the side opposite to the diffusion member 7. The prism 81 has a convex shape toward the light emission direction on the positive side of the Z axis, in other words, has a substantially triangular shape in a cross-sectional view, and reflects and refracts light incident from the diffusion member 7. , And the light concentrated within a predetermined range is emitted.

  The optical member 8 is not limited to a single prism sheet, but may be formed of two prism sheets in which the extending directions of the prisms 81 are different from each other. It will be described later.

  Next, the optical element 5a1 of the light guide plate 5 will be described in detail with reference to FIGS. FIG. 4 is a diagram showing a part of a bottom view of the light guide plate 5. FIG. 5 is a sectional view of the light guide plate 5. FIG. 5 is a cross-sectional view taken along line BB of FIG.

  As shown in FIG. 4, the plurality of optical elements 5a1 are arranged in a row direction and a column direction on the XY plane. Note that the arrangement method of the optical elements 5a1 is not limited to the matrix direction shown in FIG. 4, and may be any arrangement method such as a staggered arrangement.

  As shown in FIGS. 4 and 5, the optical element 5a1 is formed in a convex shape toward the light source 2 side which is the negative side of the Z-axis. Specifically, the optical element 5a1 is a quadrangular pyramid formed by four inclined surfaces 50a to 50d.

  More specifically, as shown in FIG. 5, two inclined surfaces 50a and 50b facing each other are orthogonal to each other at the apex of the quadrangular pyramid. Although not shown, the other two inclined surfaces 50c and 50d are also orthogonal at the vertices of the quadrangular pyramid. Thereby, most of the light L can be refracted to the wide-angle side when the light L of the light source 2 enters from the inclined surfaces 50a to 50d of the optical element 5a1. Further, by providing the optical element 5a1 on the incident surface 5a of the light guide plate 5, even if a position shift between the light source 2 and the light guide plate 5 occurs, such a position shift can be substantially nullified. It is possible to prevent the luminance uniformity from being reduced.

  The two inclined surfaces 50a and 50b (or inclined surfaces 50c and 50d) facing each other are not limited to the case where they are orthogonal to each other, and the two inclined surfaces 50a and 50b (or inclined surfaces 50c and 50d) are acute angles. Or they may cross at a wide angle.

  The optical element 5a1 is not limited to a quadrangular pyramid, but may be another polygonal pyramid or a cone. Further, the optical element 5a1 is not limited to a convex shape toward the light source 2 side, but may be a concave shape.

  Although FIG. 3 shows a case where the optical member 8 is formed of one prism sheet, for example, as shown in FIG. 6, the optical member 8 may be formed of two prism sheets. The case where the optical member 8 is composed of two prism sheets will be described with reference to FIG. FIG. 6 is an exploded perspective view of a two-member optical member 8 according to a modification. As shown in FIG. 6, the optical member 8 is configured by laminating a first prism sheet 8a and a second prism sheet 8b.

  As shown in FIG. 6, a first prism 81a is formed on the first prism sheet 8a, and a second prism 81b is formed on the second prism sheet 8b. Specifically, the first prisms 81a extend in a first extending direction that is the Y-axis direction, and are arranged in a first parallel direction that is the X-axis direction. The second prisms 81b extend in the second extending direction, which is the X-axis direction, and are arranged in the second parallel direction, which is the Y-axis direction.

  That is, the first extending direction of the first prism 81a and the second extending direction of the second prism 81b are orthogonal to each other. The first prism 81a condenses the emitted light in the X-axis direction. The second prism 81b collects light emitted from the first prism 81a in the Y-axis direction. That is, light emitted through the first prism 81a and the second prism 81b is collected in a specific direction.

  Next, a spread illuminating apparatus 1 according to a second embodiment will be described with reference to FIGS. The second embodiment differs from the first embodiment in that the light selection member 9 is a prism sheet (an example of an optical sheet). In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  FIG. 7 is a cross-sectional view of the planar lighting device 1 according to the second embodiment. As shown in FIG. 7, the spread illuminating apparatus 1 according to the second embodiment includes a light selecting member 9 configured as a prism sheet. Specifically, the light selection member 9 reflects light that intersects substantially perpendicularly with the light exit surface 9b from which light incident from the light incident surface 9a exits, and transmits light that intersects at an angle other than approximately perpendicular. Angle dependence.

  Further, as shown in FIG. 7, the arrangement of the light selection member 9 is different from that of the first embodiment. That is, the light selection member 9 is disposed on the side opposite to the light guide plate 5 with respect to the wavelength conversion member 6, and is disposed between the wavelength conversion member 6 and the diffusion member 7. Therefore, the light selection member 9 reflects or transmits the white light L1 emitted from the wavelength conversion member 6. Note that the light L2 is the same as in the first embodiment, and a description thereof will be omitted.

  Specifically, the light selection member 9 reflects or transmits white light L1 emitted from the wavelength conversion member 6 when the white light L1 enters the light entrance surface 9a and exits the light exit surface 9b (an example of an exit surface). I do. More specifically, the light selection member 9 reflects the light that intersects substantially perpendicularly and transmits the light that intersects at an angle other than substantially perpendicular by the prism 9b1 (an example of an optical element) formed on the light exit surface 9b. Angle dependence.

  In FIG. 7, the spread illuminating apparatus 1 according to the second embodiment includes the wavelength conversion member 6 because the light source 2 emits blue light. However, for example, the light source 2 emits white light. In the case of such a configuration, the wavelength conversion member 6 may be omitted.

  Next, the light selection member 9 as a prism sheet (an example of an optical sheet) will be described in detail with reference to FIGS. FIG. 8 is a top view of the light selection member 9 according to the second embodiment. FIG. 9 is a cross-sectional view of the light selection member 9 according to the second embodiment. FIG. 9 is a cross-sectional view taken along line CC of FIG.

  As shown in FIG. 8, the plurality of prisms 9b1 are arranged in the row direction and the column direction on the XY plane. Note that the arrangement method of the prisms 9b1 is not limited to the matrix direction shown in FIG. 8, but may be any arrangement method such as a staggered arrangement.

  As shown in FIGS. 8 and 9, the prism 9b1 is formed in a convex shape toward the diffusion member 7 (see FIG. 7) on the positive side of the Z axis. Specifically, the prism 9b1 is a quadrangular pyramid formed by four inclined surfaces 90a to 90d.

  More specifically, as shown in FIG. 9, two inclined surfaces 90a and 90b facing each other are orthogonal to each other at the apex of the quadrangular pyramid. Although not shown, the other two inclined surfaces 90c and 90d are also orthogonal at the vertices of the quadrangular pyramid.

  Here, FIG. 9 shows a normal line NL of the light exit surface 9b and an intersection angle α of the two lights L2 with respect to the normal line NL. In addition, the two lights L2 impinge on the inclined surfaces 90a and 90b, respectively. The light L1 is light that crosses the light exit surface 9b substantially perpendicularly. In addition, it can be said that the light L <b> 1 is mainly light emitted directly above the light source 2, and the light L <b> 2 is light emitted toward the peripheral portion distant from the immediately above light source 2.

  First, as shown in FIG. 9, since the light L1 of the light source 2 intersects the light exit surface 9b substantially perpendicularly, it intersects the inclined surface 90a at approximately 45 °. Therefore, the light L1 is reflected by the inclined surface 90a and strikes the inclined surface 90b. Since the light L1 intersects the inclined surface 90b at approximately 45 °, the light L1 hit by the inclined surface 90b is reflected and returns to the light selection member 9 side. Thus, the light selection member 9 reflects the light L1 that intersects the light exit surface 9b substantially perpendicularly.

  On the other hand, the light L2 (the light L2 on the left side) that intersects the light exit surface 9b at the predetermined intersection angle α intersects the inclined surface 90b at an angle that is almost a right angle. Therefore, the light L2 is refracted by the inclined surface 90b and transmitted. Also, the light L2 (light L2 on the right side) that hits the inclined surface 90a intersects the inclined surface 90a at a relatively wide angle, and is reflected toward the inclined surface 90b. Then, since the light intersects the inclined surface 90b at an angle close to a right angle, the light is refracted by the inclined surface 90b and transmitted. As described above, the light selection member 9 transmits the light L2 that intersects the light exit surface 9b at an angle other than substantially perpendicular (intersection angle α).

  As described above, the light L1 is light emitted directly above the light source 2, and the light L2 is light emitted near the upper portion of the light source 2. In other words, the light selection member 9 having the angle dependency due to the prism 9b1 can increase the luminance of the peripheral portion while suppressing the luminance immediately above the light source 2, and thus can improve the uniformity of the luminance as a whole. .

  In FIGS. 8 and 9, the two inclined surfaces 90a and 90b (or the inclined surfaces 90c and 90d) facing each other are not limited to the case where they are orthogonal to each other, and are not limited to the two inclined surfaces 90a and 90b (or the inclined surfaces 90a and 90b). The surfaces 90c, 90d) may intersect at an acute angle or a wide angle.

  Further, the prism 9b1 is not limited to a quadrangular pyramid, but may be another polygonal pyramid or a cone. Further, the prism 9b1 is not limited to a convex shape toward the positive Z-axis direction, and may be a concave shape.

  Although FIGS. 8 and 9 show a case where the light selection member 9 is configured as one prism sheet, the light selection member 9 may be configured as two prism sheets. This will be described with reference to FIG.

  FIG. 10 is a top view of a light selection member 9 and an optical member 8 according to a modification of the second embodiment. The upper part of FIG. 10 shows a state where the light selecting member 9 and the optical member 8 are separated, and the lower part shows a state where the light selecting member 9 and the optical member 8 are stacked.

  In the upper part of FIG. 10, the optical member 8 includes a first prism sheet 8a (negative Z-axis direction) and a second prism sheet 8b (positive Z-axis direction) superposed. On the first prism sheet 8a, for example, a first prism 81a extending in a first extending direction that is the Y-axis direction is formed.

  The second prism sheet 8b is provided with, for example, a second prism 81b extending in a second extending direction that is the X-axis direction. Then, as shown in FIG. 10, the first extending direction of the first prism 81a and the second extending direction of the second prism 81b are orthogonal to each other. Note that details of the shapes and the like of the first prism 81a and the second prism 81b are the same as those in FIG.

  In the light selection member 9, a first prism sheet 92a (negative Z-axis direction) and a second prism sheet 92b (positive Z-axis direction) are arranged so as to overlap with each other. On the first prism sheet 92a, for example, a first prism 91a extending in the third extending direction is formed. The second prism sheet 92b has, for example, a second prism 91b extending in the fourth extending direction. The first prism 91a and the second prism 91b have, for example, a convex shape toward the diffusion member 7 (see FIG. 7) on the positive side of the Z axis. Then, as shown in FIG. 10, the third extending direction of the first prism 91a and the fourth extending direction of the second prism 91b are orthogonal to each other.

  Then, as shown in the lower part of FIG. 10, when the light selecting member 9 (Z-axis negative direction side) and the optical member 8 (Z-axis positive direction side) are overlapped, the first prism 91a of the light selecting member 9 and the The extending directions of the two prisms 91b and the first prism 81a and the second prism 81b of the optical member 8 are different from each other.

  Specifically, the first prism 91a, the second prism 91b, the first prism 81a, and the second prism 81b extend in the XY plane while being shifted by 45 degrees in the rotation direction. That is, since each prism is not substantially parallel when viewed from above (view from the positive side of the Z axis), it is possible to suppress the occurrence of moire fringes in the emitted light. That is, the uniformity of luminance can be improved.

  FIG. 10 shows only an example of the extending direction of each of the first prism 91a, the second prism 91b, the first prism 81a, and the second prism 81b, and is arbitrary as long as the extending directions of the respective prisms are different. May be the extending direction.

  As described above, the planar lighting device 1 according to the first embodiment includes the plurality of light sources 2, the light guide plate 5, and the light selection member 9. The light guide plate 5 is a main surface on which the optical element 5a1 is formed. The light guide plate 5 is an incident surface 5a on which light from the light source 2 is incident, and a main surface opposite to the incident surface 5a. And an emission surface 5b for emitting light. The light selection member 9 is arranged in parallel with the light guide plate 5 on the emission surface 5b side, and the incident angle of the light with respect to the light entrance surface 9a on which the light emitted from the light guide plate 5 is incident is substantially parallel to the light entrance surface 9a. The lower the reflectance, the lower the angle dependency. Thereby, the uniformity of luminance can be improved.

  Further, as described above, the spread illuminating apparatus 1 according to the second embodiment includes the plurality of light sources 2, the light guide plate 5, and the light selection member 9. The light guide plate 5 is a main surface on which the optical element 5a1 is formed. The light guide plate 5 is an incident surface 5a on which light from the light source 2 is incident, and a main surface opposite to the incident surface 5a. And an emission surface 5b for emitting light. The light selecting member 9 is arranged in parallel with the light guide plate 5 on the side of the light exit surface 5b, reflects light that intersects substantially perpendicularly with the light exit surface 9b from which light enters, and intersects at an angle other than substantially perpendicular. Has the angle dependency of transmitting the passing light. Thereby, the uniformity of luminance can be improved.

  Further, the present invention is not limited by the above embodiments. The present invention also includes a configuration in which the above-described components are appropriately combined. Further, further effects and modified examples can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the above-described embodiments, and various modifications are possible.

    1 planar illumination device, 2 light sources, 3 substrate portions, 3a substrate, 4 frames, 5 light guide plates, 6 wavelength conversion members, 7 diffusion members, 8 optical members, 8a, 92a first prism sheet, 8b, 92b second Prism sheet, 9 light selection member, 9a1 optical element, 9b1, 81 prism

Claims (8)

Multiple light sources,
A main surface on which an optical element is formed, an incident surface on which light from the light source is incident, and a main surface on the opposite side to the incident surface, and having an exit surface for emitting light incident from the incident surface; A light guide plate,
The reflectivity is lower as the incident angle of the light with respect to the light incident surface on which the light emitted from the light guide plate is parallel is parallel to the light incident surface with respect to the light guide plate. A planar illumination device comprising: an angle-dependent light selection member. Further comprising a wavelength conversion member that emits light of a predetermined color when excited by the light of the light source,
The light selection member,
The spread illuminating device according to claim 1, which is arranged between the light guide plate and the wavelength conversion member. Multiple light sources,
A main surface on which an optical element is formed, an incident surface on which light from the light source is incident, and a main surface on the opposite side to the incident surface, and having an exit surface for emitting light incident from the incident surface; A light guide plate,
An angle dependency that reflects light that intersects the light guide plate at a substantially perpendicular angle to a light exit surface from which light is incident, and which is parallel to the light exit surface, and transmits light that intersects at an angle other than substantially perpendicular. A planar lighting device, comprising: The light selection member,
The spread illuminating device according to claim 3, wherein the optical sheet has the angle dependency due to an optical element formed on the light exit surface. Further provided is a wavelength conversion member that is provided on the emission surface side of the light guide plate and emits light of a predetermined color when excited by light from the light source,
The light selection member,
The planar illumination device according to claim 3, wherein the surface illumination device is disposed on a side opposite to the light guide plate with respect to the wavelength conversion member. The light selection member,
The planar illumination device according to claim 3, further comprising the optical element protruding in a direction away from the light guide plate. An optical member having an optical element provided on a side opposite to the light guide plate with respect to the light selection member and extending in a first extending direction and a second extending direction orthogonal to each other;
The light selection member,
7. An optical element that is orthogonal to each other and extends in a third extension direction and a fourth extension direction different from the first extension direction and the second extension direction. 8. A spread illuminating device according to claim 1. The light guide plate includes:
The planar lighting device according to any one of claims 1 to 6, further comprising a plurality of protruding portions that protrude from the emission surface and become closer to each other as the distance from the light source in the surface direction of the emission surface increases.

Images