lighting equipment

Abstract

To provide a lighting device which can be used as a blackboard lamp and has light diffusivity in a longitudinal direction and light gathering capability in a short side direction.SOLUTION: A lighting device includes: a light source unit; and a body which is attached to an attached part and to which the light source unit is attached. The light source unit has: a light source; a substrate mounted with the light source; and a cover which covers the light source and the substrate. The cover has an arc shaped cross section shape in a cross sectional view orthogonal to a longitudinal direction of the cover. The cover has: an incidence surface where light from the light source enters; and an emission surface from which the light entering the incidence surface is emitted. The emission surface of the cover has a first prism part and a second prism part. The first prism part has a first emission surface from which the light entering the incidence surface is refracted and deflected toward the first direction to be emitted. The second prism part has: a reflection surface on which the light entering the incidence surface is totally reflected; and a second emission surface from which the light totally reflected on the reflection surface is refracted and deflected toward the first direction to be emitted.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a lighting device that includes a light source unit having a cover and a main body to which the light source unit is attached, and that is intended to be usable as a blackboard lamp. [Background technology]

[0002] BACKGROUND ART Among long lighting devices that use an LED (Light Emitting Diode) as a light source, there is a type that focuses light directly below the lighting device (see, for example, Patent Document 1).

[0003] In the lighting device described in Patent Document 1, a plurality of prisms are formed on the surface of a trough-shaped cover, thereby improving the luminous intensity directly below the lighting device and improving the light diffusion properties of the cover.

[0004] The lighting device described in Patent Document 1 has light diffusibility in the longitudinal direction and the lateral direction of the lighting device. In the lighting device described in Patent Document 1, the cover has light diffusibility, thereby reducing glare. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6292509 Summary of the Invention [Problem to be solved by the invention]

[0006] Patent Document 1 does not intend to use the lighting device as a blackboard lamp for illuminating a blackboard.

[0007] If the lighting device described in Patent Document 1 is to be used as a blackboard lamp, the longitudinal direction of the lighting device is placed parallel to the blackboard surface, and the lighting device is rotated about 30° around the longitudinal direction of the lighting device as the axis of rotation to ensure the illuminance on the blackboard surface.

[0008] When the lighting device is used as a blackboard lamp, it is desirable to have light diffusing properties in the longitudinal direction and light collecting properties in the lateral direction, since it is desired to intensively illuminate the blackboard surface.

[0009] However, the lighting device described in Patent Document 1 has light diffusion properties in both the longitudinal and lateral directions, so there is a possibility that sufficient illuminance may not be obtained on the blackboard surface.

[0010] The present disclosure has been made to solve such problems, and aims to obtain a lighting device that has light diffusion in the longitudinal direction and light concentration in the lateral direction, with the assumption that it can also be used as a blackboard light. [Means for solving the problem]

[0011] The lighting device according to the present disclosure includes a light source unit and a main body portion that is attached to an attachment portion and to which the light source unit is attached, the light source unit including a light source, a board on which the light source is mounted, and a cover that covers the light source and the board, the cover having an arc-shaped cross section in a cross section perpendicular to a longitudinal direction of the cover, the cover having an incident surface into which light from the light source is incident and an exit surface from which the light that has been incident on the incident surface is emitted, the exit surface of the cover having a first prism portion and a second prism portion, the first prism portion refracting the light that has been incident on the incident surface , including the direction of the optical axis of the light from the light source the second prism portion has a first exit surface that deflects the light incident on the entrance surface and emits the light, and the second prism portion has a reflecting surface that totally reflects the light incident on the entrance surface and a second exit surface that refracts the light totally reflected by the reflecting surface, deflects the light in the first direction, and emits the light. In a cross-sectional view perpendicular to the longitudinal direction of the cover, the first prism portion is provided in a first region including the direction of the optical axis, and in the cross-sectional view perpendicular to the longitudinal direction of the cover, an inclination angle of the first emission surface, which is an angle between the first emission surface and a plane parallel to the substrate, monotonically increases with increasing distance from the optical axis, and in the first region, light emitted from the first prism portion assumes a shape that curves in a positive direction in a short-side direction perpendicular to the longitudinal direction as the angle in the long-side direction increases in a two-dimensional light distribution diagram. By utilizing this characteristic, light emitted from a plurality of first prism portions having different inclination angles of the first emission surface of each first prism portion is obtained, whereby a light distribution in which light is concentrated in the short-side direction and diffused in the long-side direction is obtained. It is something. Further, an illumination device according to the present disclosure includes a light source unit and a main body portion attached to an attachment portion and on which the light source unit is attached, the light source unit including a light source, a board on which the light source is mounted, and a cover covering the light source and the board, the cover having an arc-shaped cross section in a cross section perpendicular to a longitudinal direction of the cover, the cover having an incident surface into which light from the light source is incident and an exit surface from which the light incident on the incident surface is emitted, the exit surface of the cover having a first prism portion and a second prism portion, the first prism portion having a first exit surface that refracts the light incident on the incident surface and deflects the light toward a first direction including a direction of an optical axis of the light from the light source and emits the deflected light, the second prism portion having a reflective surface that totally reflects the light incident on the incident surface and refracts the light totally reflected on the reflective surface to emit the first prism portion, and a second exit surface that deflects the light toward a direction perpendicular to the longitudinal direction of the cover and exits it, and in a cross-sectional view perpendicular to the longitudinal direction of the cover, the second prism portion is provided in a second region formed outside the first region that includes the direction of the optical axis, and in a cross-sectional view perpendicular to the longitudinal direction of the cover, the inclination angle of the second exit surface, which is the angle between the second exit surface and a plane parallel to the substrate, monotonically decreases with increasing distance from the optical axis, and the light emitted from the second prism portion in the second region takes on a shape that curves in the negative direction of the short side, which is the direction perpendicular to the longitudinal direction, as the angle in the long side increases in a two-dimensional light distribution diagram. By utilizing this property, light emitted from a plurality of second prism portions that have different inclination angles of the second exit surface of the second prism portion is accumulated to obtain a light distribution that is focused in the short side direction and diffused in the long side direction. [Effects of the Invention]

[0012] The lighting device according to the present disclosure includes, with respect to the front surface of the light source unit, a first prism section having a first exit surface that refracts light incident on the entrance surface, deflects it in a first direction, and emits the light, and a second prism section having a second exit surface that refracts light totally reflected by the reflection surface, deflects it in the first direction, and emits the light. By using the first prism section and the second prism section in combination, a light distribution that diffuses light in the longitudinal direction and focuses light in the lateral direction can be obtained. Therefore, a lighting device that has light diffusion in the longitudinal direction and light focusing in the lateral direction can be obtained. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is an exploded perspective view of a lighting device according to a first embodiment. [Figure 2] 1 is a vertical cross-sectional view showing the configuration of a light source unit provided in the lighting device according to the first embodiment. [Figure 3] 2 is a vertical cross-sectional view showing a light source of a light source unit provided in the lighting device according to the first embodiment. FIG. [Figure 4] 4 is an explanatory diagram illustrating a radiation mechanism of a cover provided in the lighting device according to the first embodiment. FIG. [Figure 5] 3 is an explanatory diagram showing the prism shape of a first prism portion of the lighting device according to the first embodiment and the direction in which light travels. FIG. [Figure 6] 4 is a diagram showing a two-dimensional light distribution of light emitted from an exit surface on which first prism portions are formed in the lighting device according to the first embodiment. FIG. [Figure 7] 3 is an explanatory diagram showing the prism shape of a first prism portion of the lighting device according to the first embodiment and the direction in which light travels. FIG. [Figure 8] 3 is an explanatory diagram showing the prism shape of a first prism portion of the lighting device according to the first embodiment and the direction in which light travels. FIG. [Figure 9] 4 is a diagram showing a two-dimensional light distribution of light emitted from an exit surface on which a plurality of first prism portions are formed in the lighting device according to the first embodiment. FIG. [Figure 10]6 is a diagram showing the light distribution in the short-side direction A and the long-side direction B in the case of the first prism portion shown in FIG. 5. FIG. [Figure 11] 8 is a diagram showing the light distribution in the short-side direction A and the long-side direction B in the case of the first prism portion shown in FIG. 7. FIG. [Figure 12] 9 is a diagram showing the light distribution in the short-side direction A and the long-side direction B in the case of the first prism portion shown in FIG. 8. FIG. [Figure 13] 4 is an explanatory diagram showing the prism shape of a second prism portion of the lighting device according to the first embodiment and the direction in which light travels. FIG. [Figure 14] 5 is a diagram showing a two-dimensional light distribution of light emitted from an exit surface on which second prism portions of the lighting device according to the first embodiment are formed. FIG. [Figure 15] 4 is an explanatory diagram showing the prism shape of a second prism portion of the lighting device according to the first embodiment and the direction in which light travels. FIG. [Figure 16] 4 is an explanatory diagram showing the prism shape of a second prism portion of the lighting device according to the first embodiment and the direction in which light travels. FIG. [Figure 17] 5 is a diagram showing a two-dimensional light distribution of light emitted from an exit surface on which a plurality of second prism portions are formed in the lighting device according to the first embodiment. FIG. [Figure 18] 14 is a diagram showing the light distribution in the short-side direction A and the long-side direction B in the case of the second prism portion shown in FIG. 13. FIG. [Figure 19] 16 is a diagram showing the light distribution in the short-side direction A and the long-side direction B in the case of the second prism portion shown in FIG. 15. FIG. [Figure 20] 17 is a diagram showing the light distribution in the short-side direction A and the long-side direction B in the case of the second prism portion shown in FIG. 16. FIG. [Figure 21] 4 is a diagram showing the light distribution in a short-side direction A and a long-side direction B of light emitted from all first prism portions and second prism portions formed on the cover in the lighting device according to the first embodiment. FIG. [Figure 22] 1 is a layout diagram showing the layout when the lighting device according to the first embodiment is used as a blackboard lamp. [Figure 23]10 is an explanatory diagram showing the prism shape and the light traveling direction of a third prism portion of an illumination device according to Embodiment 2. FIG. [Figure 24] 24 is a diagram schematically illustrating the prism shape of the third prism portion shown in FIG. 23. FIG. [Figure 25] 24 is a diagram showing the light distribution in the short-side direction A and the long-side direction B in the case of the third prism portion shown in FIG. 23. FIG. [Figure 26] 10 is a vertical cross-sectional view showing the configuration of a light source unit provided in an illumination device according to a third embodiment. FIG. [Figure 27] 10 is an explanatory diagram showing the prism shape of a first prism portion of an illumination device according to a third embodiment and the direction in which light travels. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of a lighting device according to the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments, and various modifications are possible without departing from the spirit and scope of the present disclosure. Furthermore, the present disclosure includes all possible combinations of configurations shown in the following embodiments and their modifications. In addition, in each drawing, components with the same reference numerals are identical or equivalent, and this is common throughout the entire specification. Note that in each drawing, the relative dimensional relationships or shapes of each component may differ from those in reality.

[0015] Embodiment 1 FIG. 1 is an exploded perspective view showing the configuration of a lighting device according to embodiment 1. FIG. 2 is a longitudinal cross-sectional view showing the configuration of a light source unit provided in the lighting device according to embodiment 1. In each of the drawings, including FIG. 1 and FIG. 2, for convenience of explanation, the short-side direction of the lighting device 1 is designated as direction A, the long-side direction of the lighting device 1 is designated as direction B, and the direction perpendicular to directions A and B is designated as direction C. When the lighting device 1 is attached to a ceiling, direction C is the up-down direction. In this case, direction C is, for example, the vertical direction. In this case, in direction C, direction C1 is the up-down direction and direction C2 is the down-down direction. In FIG. 1 and FIG. 2, the up-down direction is reversed. That is, in FIG. 1, direction C2 is downward on the paper surface, while in FIG. 2, direction C2 is upward on the paper surface. In the following description, for ease of understanding, direction C is designated as the up-down direction.

[0016] (Lighting device 1) As shown in FIG. 1 , the lighting device 1 according to the first embodiment is an elongated type extending in a longitudinal direction B, and has an overall outer structure in the shape of a long, narrow, approximately rectangular block. The lighting device 1 is attached to a mounting portion 100 such as a ceiling or a wall, and irradiates light onto an object to be illuminated. The object to be illuminated by the lighting device 1 according to the first embodiment may be not only an illumination space such as an indoor space, but also an object such as a blackboard fixed to a wall. In this way, the lighting device 1 according to the first embodiment is premised on being usable as a blackboard lamp for illuminating a blackboard.

[0017] The lighting device 1 comprises a long light source unit 2 that irradiates light onto an object to be illuminated, and a long main body 3 that is attached and fixed to an attachment portion 100 such as a ceiling or a wall, and to which the light source unit 2 is detachably attached.

[0018] (Main body 3) The main body 3 is formed in the shape of a long, narrow, approximately rectangular block box with a bottom. Therefore, the main body 3 has a recessed interior formed in a concave shape. In the example of FIG. 1, the main body 3 is a direct-mount fixture. The upper surface 3a of the main body 3 is closed and is attached to the attachment portion 100 with connecting members such as a hanging bolt or a screw. The entire lower surface 3b of the main body 3 is open toward the C2 direction. The C2 direction corresponds to the front direction of the lighting device 1. The light source unit 2 is inserted and attached into the recessed interior of the main body 3 from the lower surface 3b side of the main body 3. A holder 3c is provided inside the recessed interior of the main body 3. The holder 3c is provided to engage with a connector (not shown) provided on the light source unit 2 to attach the light source unit 2 to the main body 3. The holder 3c is formed of an elastic material, such as stainless steel, and is a leaf spring formed by bending a strip-shaped plate. The main body 3 also houses a lighting device (not shown). The lighting device is connected to fixed wiring (not shown) installed in a building or the like, receives power from a commercial power source, and generates direct current. The lighting device is connected to a power supply section (not shown) installed in the light source unit 2, and supplies power to the power supply section. The power supply section functions as a power source that supplies power to a light source section 20 (described later) installed in the light source unit 2.

[0019] (Light source unit 2) The vertical cross-sectional view in Fig. 2 shows a cross-section of the light source unit 2 when cut along an imaginary plane that is perpendicular to the longitudinal direction of the lighting device 1 and includes the optical axis H. As shown in Fig. 2, the light source unit 2 has a light source section 20, a frame 23, a cover 24, and a reflector 25. As described above, the up-down direction is reversed in Fig. 1 and Fig. 2. That is, the up-down direction is reversed in Fig. 2 compared to when the lighting device 1 is attached to the ceiling.

[0020] As shown in FIG. 1, the light source unit 2 is attached to the main body 3 of the lighting device 1 so as to cover the open bottom surface 3b of the main body 3, and lights the light source 21 of the light source section 20 using power supplied from a commercial power source via the lighting device and the power supply section.

[0021] FIG. 3 is a longitudinal cross-sectional view showing a light source of the light source unit provided in the lighting device according to embodiment 1. The longitudinal cross-sectional view of FIG. 3 shows a cross section of the light source unit 2 taken along an imaginary plane that is along the longitudinal direction of the lighting device 1 and includes the optical axis H. FIG. 3 shows only the light source section 20 and the cover 24 of the light source unit 2. Note that the up-down direction is reversed between FIG. 1 and FIG. 3. That is, in FIG. 3, the up-down direction is reversed compared to when the lighting device 1 is attached to the ceiling, as in FIG. 2. As shown in FIGS. 2 and 3, the light source section 20 includes a plurality of light sources 21 and a board 22 on which the light sources 21 are mounted. The board 22 is an elongated, flat member extending along the longitudinal direction B of the light source unit 2. The bottom surface 22a of the board 22 serves as a mounting surface. The light source 21 is a light-emitting element mounted on the bottom surface 22a of the board 22. The light source 21 is, for example, an LED light source. The multiple light sources 21 are arranged in a row at intervals along the longitudinal direction B of the light source unit 2. The light source 21 has an optical axis H in a direction perpendicular to the substrate 22. The light source section 20 receives power from a power supply section built into the frame 23, causing the light source 21 to emit light. The light source 21 emits light in the C2 direction. Therefore, the C2 direction is sometimes referred to as the illumination side.

[0022] Returning to the explanation of FIG. 2, the reflector 25 reflects the light emitted from the light source 21. The light reflected by the reflector 25 travels toward the irradiation side. The reflector 25 is made of a diffusing material, and the light emitted from the light source 21 becomes diffused light and is emitted toward the irradiation side. As shown in FIG. 2, the reflectors 25 are provided on both sides of the substrate 22. The reflectors 25 are long, plate-like members extending along the longitudinal direction B of the light source unit 2. The inclined surfaces 25a of each of the reflectors 25 are inclined in a direction toward the optical axis H with respect to the main surface of the substrate 22. That is, one of the inclined surfaces 25a is inclined toward the positive side (clockwise direction) with respect to the lower surface 22a of the substrate 22, and the other inclined surface 25a is inclined toward the negative side (counterclockwise direction) with respect to the lower surface 22a of the substrate 22. 2, one and the other of the inclined surfaces 25a are formed to be symmetrical with respect to the optical axis H in a cross section perpendicular to the longitudinal direction of the cover 24. The reflector 25 is not necessarily provided, and may be provided as needed.

[0023] The frame 23 constitutes the main body of the light source unit 2. The frame 23 is formed of, for example, sheet metal. The frame 23 is a long, flat member extending along the longitudinal direction B of the light source unit 2. The substrate 22 and the reflector 25 are attached to the frame 23 and support them. The frame 23 is detachably attached to the main body 3. The frame 23 is further provided with the above-mentioned connector (not shown). The connector engages with the holder 3c of the main body 3 shown in FIG. 1 to attach the light source unit 2 to the main body 3.

[0024] As shown in FIG. 1, the cover 24 is provided on the underside of the light source unit 2, which is the illumination side. The cover 24 is made of a light-transmitting material and is a member that covers the periphery of the light source 21 and the substrate 22 of the light source section 20. The cover 24 is a long, trough-shaped member that extends along the longitudinal direction B of the light source unit 2. The cover 24 is attached to the frame 23. As shown in FIG. 2, the cover 24 has an incident surface 24a onto which light from the light source 21 is incident and an exit surface 24b from which the light that is incident on the incident surface 24a is emitted. The light emitted from the light source 21 is incident on the incident surface 24a of the cover 24, passes through the cover 24, exits from the exit surface 24b, and is irradiated onto the target object. Examples of the light-transmitting material for the cover 24 include synthetic resins such as acrylic and polycarbonate, and glass. It is also possible to use a resin plate containing scattering particles at an appropriate density as the transparent material for the cover 24. The cover 24 is formed by injection molding, extrusion molding, three-dimensional additive manufacturing, or the like, depending on the material used.

[0025] The cover 24 has a light-transmitting portion 242 that transmits light from the light source 21, and an opening surface facing the light-transmitting portion 242. The cover 24 is formed in the shape of a long, bottomed box. Specifically, as shown in FIG. 1 , the cover 24 has a long, curved cover main body 240 and cover end portions 241 that close both end surfaces of the cover main body 240 in the longitudinal direction B. The cover main body 240 and the cover end portions 241 may be molded integrally, or may be formed separately and joined together with an adhesive or the like.

[0026] As shown in Figure 2, the cover main body 240 has a concave translucent portion 242 that transmits light emitted from the light source 20, and a pair of cover flat portions 243 formed from both end edges of the translucent portion 242 toward the inward side of the opening.

[0027] 2, the light-transmitting portion 242 has a substantially U-shaped cross section in a cross section perpendicular to the longitudinal direction B of the cover 24. As shown in Fig. 2, the light-transmitting portion 242 has an arc-shaped light-transmitting main portion 242a that faces the light source unit 20 and irradiates light emitted from the light source unit 20 in the C2 direction, and light-transmitting side portions 242b that extend in the C1 direction from both end edges of the light-transmitting main portion 242a in the short-side direction A.

[0028] (Cover 24 radiation mechanism) Next, the radiation mechanism of the cover 24 will be described. FIG. 4 is an explanatory diagram illustrating the radiation mechanism of the cover provided in the lighting device according to the first embodiment. As shown in FIG. 4, the cover 24 has a first region and a second region in a cross section perpendicular to the longitudinal direction of the cover 24. The angle formed between the optical axis H of the light source 21 and the light traveling direction P is defined as the "light emission angle θ." In this case, the optical axis H is positioned so that the light emission angle θ = 0°. In the plane of FIG. 4, the direction proceeding leftward from the optical axis H (counterclockwise direction) is defined as the negative direction, and the direction proceeding rightward from the optical axis H (clockwise direction) is defined as the positive direction. In this case, the central region including the optical axis H is defined as the first region, and the regions outside the first region are defined as the second region. For example, the first region is defined as a region where the light emission angle θ is in the range from 0° to ±60°, i.e., -60°<θ<60°. Furthermore, for example, the second region has a light emission angle θ in the range of ±60° to ±90°, i.e., -90°≦θ≦-60° and 60°≦θ≦90°. In the cover 24, different radiation mechanisms are used for the first region and the second region. Specifically, a first radiation mechanism is used in the first region of the cover 24, and a second radiation mechanism is used in the second region of the cover 24. These mechanisms will be described later.

[0029] As described with reference to FIG. 2, the cover 24 has an incident surface 24a through which light from the light source 21 is incident and an exit surface 24b through which the light incident on the incident surface 24a is emitted. A large number of rib-like prisms are formed on the exit surface 24b along the longitudinal direction B. These prisms may be provided over the entire light-transmitting portion 242 (see FIG. 2) of the cover 24, or may be provided only on the light-transmitting main portion 242a (see FIG. 2) of the light-transmitting portion 242 of the cover 24, and not on the light-transmitting side portion 242b (see FIG. 2). These prisms protrude from the exit surface 24b of the cover 24 toward the irradiation side. Furthermore, these prisms have a triangular cross-sectional shape in a cross section perpendicular to the longitudinal direction of the cover 24. Hereinafter, of these prisms, the prism provided in the first region of cover 24 will be referred to as first prism portion 400, and the prism provided in the second region of cover 24 will be referred to as second prism portion 401. In this manner, exit surface 24b of cover 24 has first prism portion 400 and second prism portion 401. Note that the vertical cross-sectional view of Figure 3 shows one of the multiple first prism portions 400.

[0030] (First prism part 400) First, the first prism unit 400 will be described. FIG. 5 is an explanatory diagram illustrating the prism shape and light traveling direction of the first prism unit of the lighting device according to the first embodiment. FIG. 5 is an enlarged view of the portion surrounded by the dashed line R1 in FIG. 4. That is, FIG. 5 illustrates the first prism unit 400 provided in the first region. Note that FIG. 5 illustrates the state of the first region at, for example, a point where θ=−30°. As shown in FIG. 5, the first prism unit 400 has a triangular cross-sectional shape in a cross section perpendicular to the longitudinal direction of the cover 24. The first prism unit 400 protrudes from the exit surface 24b of the cover 24 toward the irradiation side. The first prism units 400 are arranged side by side at regular intervals. As shown in FIG. 5, the first prism unit 400 has a first exit surface 400a that refracts light incident on the entrance surface 24a, deflects the light in a first direction D, and emits the light. The inclination angle θα of the first exit surface 400a is set so that light traveling in a direction inclined by θ° with respect to the optical axis H enters the incident surface 24a of the cover 24 and is deflected in a first direction D by passing through the first prism unit 400. The first direction D is the front direction (0° direction) of the lighting device 1 or a substantially front direction. In this way, the inclination angle θα of the first exit surface 400a is determined for each point on the cover 24 by the first direction D and the light exit angle θ°. The inclination angle θα will be described later. Note that the inclination angle θα of the first exit surface 400a is the angle formed between the first exit surface 400a and a plane E parallel to the substrate 22. The plane E parallel to the substrate 22 is, for example, a horizontal plane, but it does not necessarily have to be horizontal.

[0031] 4, first prism section 400 is divided into prism group 400-1, in which first exit surface 400a is inclined toward the negative side with respect to plane E parallel to substrate 22, and prism group 400-2, in which first exit surface 400a is inclined toward the positive side. Prism group 400-1 and prism group 400-2 are inverted with optical axis H as a boundary in a cross section perpendicular to the longitudinal direction of cover 24. In other words, prism group 400-1 and prism group 400-2 are formed so as to be symmetrical with respect to optical axis H in a cross section perpendicular to the longitudinal direction of cover 24.

[0032] Furthermore, in the vicinity of the optical axis H, the first exit surface 400a of the first prism portion 400 may be substantially parallel to the substrate 22. That is, in the vicinity of the optical axis H, the inclination angle θα of the first exit surface 400a may be substantially 0° (for example, ±0.5 or less). In this case, the light emitted from the light source 21 toward the vicinity of the optical axis H is emitted in the first direction D without being refracted much. On the other hand, in a region outside the vicinity of the optical axis H, the inclination angle θα of the first exit surface 400a monotonically increases with increasing distance from the optical axis H. That is, in a cross-sectional view perpendicular to the longitudinal direction of the cover 24, the inclination angle θα increases with increasing distance from the optical axis H.

[0033] 5, the cross-sectional shape of first prism portion 400 is not strictly triangular, but has rounded corners, due to consideration of the processing limits of mold processing. Therefore, first prism portion 400 may have a triangular shape with sharp corners, as long as the processing limits of mold processing allow. In this way, first prism portion 400 has a triangular or approximately triangular cross-sectional shape, and these will be collectively referred to as a "triangular shape."

[0034] FIG. 6 illustrates a two-dimensional luminous intensity distribution of light emitted from the exit surface on which the first prism portion is formed in the lighting device according to the first embodiment. FIG. 6 illustrates a two-dimensional luminous intensity distribution of light at, for example, a point at θ=−25° in the first region. That is, FIG. 6 illustrates a two-dimensional luminous intensity distribution obtained when, among a group of light rays having an angular spread of ±90° in the longitudinal direction B of the cover 24, light traveling in the direction of θ=−25° passes through the first prism portion 400 of FIG. 5. FIG. 6 is a polar coordinate graph centered on θ=0°, with the X axis corresponding to the short-side direction A and the Y axis corresponding to the longitudinal direction B. The concentric circles in FIG. 6 represent latitudes in 10-degree increments. The numbers in the boxes on the right side of FIG. 6 indicate the luminous intensity values ​​corresponding to each color shown in the two-dimensional luminous intensity distribution of FIG. 6. Note that the two-dimensional luminous intensity distribution diagram illustrated in FIG. 6 is intended to illustrate the angular direction of light emitted from the lighting device 1 and is different from real space coordinates.

[0035] As shown in FIG. 6, in the first region, the two-dimensional light distribution is curved into a thin crescent shape, with both ends gradually bending in the positive direction of the X-axis. Specifically, a group of light rays having a spread angle within ±20° in the longitudinal direction B (a group of light rays in range W1 in FIG. 6) exists on the Y-axis, and therefore travels in the direction of approximately 0° in the lateral direction A (a direction parallel to H in FIG. 4). On the other hand, a group of light rays having a spread angle of ±20° or more in the longitudinal direction B (a group of light rays in range W2 in FIG. 6) curves in the positive direction of the X-axis as the angle increases. Thus, as the angle in the longitudinal direction B increases, the lateral direction A shifts in the positive direction. That is, the light is bent to the right in the longitudinal cross-sectional views of FIGS. 2 and 4. Therefore, for a group of light rays in range W2 in the longitudinal direction B, the first prism portion 400 deflects the light that would otherwise be shifted in the negative direction in the positive direction.

[0036] 7 and 8 are explanatory diagrams showing the prism shape of the first prism unit and the light traveling direction of the lighting device according to the first embodiment. FIGS. 7 and 8 show how the first prism unit 400 deflects light shifted in the negative direction to the positive direction in the first region using the first radiation mechanism. In FIG. 7 , the light is deflected in the −7° direction with respect to the first direction D, and in FIG. 8 , the light is deflected in the −13° direction with respect to the first direction D. Hereinafter, the angle formed between the first direction D and the light traveling direction P is referred to as the “light deflection angle θ1.” That is, FIG. 7 shows the case where θ1=−7°, and FIG. 8 shows the case where θ1=−13°. For comparison with FIG. 6 , FIGS. 7 and 8 also show the state of a point in the first region where θ=−25°, for example, as in FIG. 6 .

[0037] In Figure 7, the inclination angle θα of the first exit surface 400a is set so that light traveling in a direction inclined by θ° from the optical axis H is deflected in the negative direction by -7° from the first direction D by passing through the incident surface 24a of the cover 24 and the first prism section 400.

[0038] In Figure 8, the inclination angle θα of the first exit surface 400a is set so that light traveling in a direction inclined by θ° from the optical axis H is deflected in the negative direction by -13° from the first direction D by passing through the incident surface 24a of the cover 24 and the first prism section 400.

[0039] By gradually reducing the inclination angle θα of first exit surface 400a of first prism unit 400 with respect to plane E, the exit angle can be increased to 7° and then 13°. That is, the smaller the inclination angle θα, which is the angle formed by first exit surface 400a and plane E, the larger the absolute value of the deflection angle θ1 of light can be, and the more the light is diffused in a direction away from optical axis H. As described above, plane E is a plane parallel to substrate 22 shown in FIG. 1.

[0040] Here, a method of using first prism portion 400 to condense light in a short-side direction A and diffuse light in a long-side direction B in a first region of cover 24 will be described with reference to FIG. 9 . FIG. 9 is a diagram illustrating a two-dimensional light distribution of light emitted from an exit surface on which a plurality of first prism portions are formed in the lighting device according to embodiment 1. In FIG. 9 , solid line 90 represents the two-dimensional light distribution of light emitted from first prism portion 400 when θ1 = 0° (i.e., the case of FIG. 5 ). Therefore, solid line 90 is the same as the two-dimensional light distribution shown in FIG. 6 . Also, in FIG. 9 , dashed line 91 represents the two-dimensional light distribution of light emitted from first prism portion 400 when θ1 = -7° (i.e., the case of FIG. 7 ). Also, in FIG. 9 , dotted line 92 represents the two-dimensional light distribution of light emitted from first prism portion 400 when θ1 = -13° (i.e., the case of FIG. 8 ).

[0041] Here, the focus of attention is on the concentration on the X-axis and the diffusion on the Y-axis of the two-dimensional light distribution diagram. As described above with reference to Fig. 6, in the light extraction method of first prism unit 400 (i.e., the method of transmitting light from first emission surface 400a shown in Fig. 5), when the light is extracted in the front direction as viewed on the X-axis, a light distribution curved to the right is obtained, as shown by solid line 90 in the two-dimensional light distribution diagram of Fig. 9. With the same light extraction method, if the extraction angle is changed from θ1 = -7° shown in Fig. 7 (dashed line 91 in Fig. 9) to θ1 = -13° shown in Fig. 8 (dotted line 92 in Fig. 9), the two-dimensional light distribution diagram shifts to the left while maintaining its right-curved shape, as shown in Fig. 9.

[0042] When these three beams of light indicated by the solid line 90, dashed line 91, and dotted line 92 are integrated, the beam spreads only to approximately 0°, −7°, and −13° on the X axis, whereas the beams spread to ±20°, ±30° (excluding ±20°), and ±40° (excluding ±30°) on the Y axis, resulting in the sum of the beams. Therefore, when the three beams of light are integrated, the beam spreads to ±13° on the X axis (i.e., focused beam) and ±40° on the Y axis (i.e., diffused beam). While FIG. 9 shows the case where the beams emitted from three first prism portions 400 are integrated, three or more first prism portions 400 are formed on the cover 24. Therefore, the beam can be more precisely focused in the short-side direction A and diffused in the long-side direction B in the first region of the cover 24.

[0043] 10 to 12 show the light distribution on the X axis and the Y axis of each of the above-mentioned individual lights shown in FIG.

[0044] Fig. 10 is a diagram showing the light distribution in the short side direction A and the long side direction B in the case of the first prism portion shown in Fig. 5. Fig. 11 is a diagram showing the light distribution in the short side direction A and the long side direction B in the case of the first prism portion shown in Fig. 7. Fig. 12 is a diagram showing the light distribution in the short side direction A and the long side direction B in the case of the first prism portion shown in Fig. 8. That is, Fig. 10 shows the case when θ1=0°, Fig. 11 shows the case when θ1=-7°, and Fig. 12 shows the case when θ1=-13°.

[0045] 10 to 12, the horizontal axis represents the light emission angle θ (see FIGS. 5, 7, and 8), and the vertical axis represents the luminous intensity. In addition, in FIGS. 10 to 12, the thin lines represent the light distribution along the short direction A, and the thick lines represent the light distribution along the long direction B.

[0046] In the light distribution with a deflection angle θ1=0° shown in FIG. 10, the lateral direction A has a trapezoidal distribution shape with a width of ±4° centered at 0° and the longitudinal direction B has a trapezoidal distribution shape with a width of ±20° centered at 0°.

[0047] In the light distribution with a deflection angle θ1=−7° shown in FIG. 11, the width of the width direction A is ±4° with the center at −7°, and the width of the length direction B is ±30°.

[0048] In the light distribution with a deflection angle θ1=−13° shown in FIG. 12, the width in the lateral direction A is ±3° from the center of −13°, and the length direction B has a distribution shape with peaks at ±42°.

[0049] In this way, in the first region, the light distribution is adjusted by utilizing the characteristic that a group of light rays spreading in the longitudinal direction B assumes a curved shape in the two-dimensional light distribution diagram (see FIG. 6). Specifically, for a group of light rays having a spreading angle of ±20° or more in the longitudinal direction B (a group of light rays in range W2 in FIG. 6), a group of light rays tilted in the negative direction of the X axis from a deflection angle of 0° is added together. This results in a light distribution in which light is concentrated in the short direction and diffused in the long direction. To achieve this, in a cross-sectional view perpendicular to the longitudinal direction of the cover 24, the angle formed between the first exit surface 400a of the first prism unit 400 and a plane E parallel to the substrate 22 (i.e., the inclination angle θα of the first exit surface 400a) should monotonically increase with increasing distance from the optical axis H. In embodiment 1, the first prism portion 400 is formed in this manner, so that the first prism portion 400 can be used to concentrate light in the short direction A and diffuse light in the long direction B in the first region of the cover 24.

[0050] (Second prism part 401) Next, the second prism unit 401 will be described. FIG. 13 is an explanatory diagram showing the prism shape and light traveling direction of the second prism unit of the lighting device according to the first embodiment. FIG. 13 is an enlarged view of the portion surrounded by the dashed line R2 in FIG. 4. That is, FIG. 13 shows the second prism unit 401 provided in the second region. Note that FIG. 13 shows the state of the second region at, for example, θ=−75°. As shown in FIG. 13, the second prism unit 401 has a reflecting surface 401a that totally reflects light incident on the incident surface 24a, and a second exit surface 401b that refracts the light totally reflected by the reflecting surface 401a, deflects it toward the first direction D, and emits the light. The inclination angle of the reflecting surface 401a is set so that light traveling in a direction inclined by θ° from the optical axis H is totally reflected and enters the second exit surface 401b. That is, the reflecting surface 401a is disposed opposite the second exit surface 401b. The inclination angle of second exit surface 401b is set so that light totally reflected by reflecting surface 401a is deflected in first direction D as it passes through second prism portion 401. First direction D is the front direction (0° direction) or a substantially front direction. In this way, the inclination angle of second exit surface 401b is determined for each point on cover 24 by first direction D and light emission angle θ°. This will be explained in detail below.

[0051] 4, second prism unit 401 is divided into prism group 401-1, in which second exit surface 401b is inclined on the positive side with respect to plane E parallel to substrate 22, and prism group 401-2, inclined on the negative side. Prism group 401-1 and prism group 401-2 are inverted with optical axis H as a boundary in a cross section perpendicular to the longitudinal direction of cover 24. In other words, prism group 401-1 and prism group 401-2 are formed so as to be symmetrical with respect to optical axis H in a cross section perpendicular to the longitudinal direction of cover 24.

[0052] Furthermore, in the vicinity of both ends (±90°) of the second region, i.e., in the region near the light-transmitting side portions 242b of the light-transmitting main portion 242a (see FIG. 2), the second emission surface 401b of the second prism portion 401 may be substantially parallel to the substrate 22. That is, in the vicinity of both ends (±90°) of the second region, the inclination angle θγ of the second emission surface 401b is substantially 0° (for example, ±0.5 or less). Therefore, the light emitted from the light source 21 in a direction perpendicular to the optical axis H is reflected by the reflecting surface 401a, and then refracted in a direction of approximately 90° by the second emission surface 401b of the second prism portion 401, and is emitted in the first direction D. On the other hand, in regions other than the both ends of the second region, the inclination angle θγ of the second emission surface 401b monotonically decreases with increasing distance from the optical axis H. That is, in a cross-sectional view perpendicular to the longitudinal direction of the cover 24, the inclination angle θγ decreases as the distance from the optical axis H increases.

[0053] 13, second prism portion 401 has a triangular cross-sectional shape in a cross section perpendicular to the longitudinal direction of cover 24. Second prism portion 401 protrudes from exit surface 24b of cover 24 toward the irradiation side. Second prism portion 401 is arranged side by side at regular intervals.

[0054] 13, the cross-sectional shape of second prism portion 401 is not strictly triangular but has rounded corners because of consideration of the processing limits of the mold. Therefore, second prism portion 401 may have a strictly triangular shape if the processing limits of the mold allow. In this way, second prism portion 401 has a triangular or approximately triangular cross-sectional shape, and these will be collectively referred to as a "triangular shape."

[0055] FIG. 14 illustrates a two-dimensional luminous intensity distribution of light emitted from the exit surface of the lighting device according to the first embodiment, on which the second prism portion is formed. FIG. 14 illustrates a two-dimensional luminous intensity distribution of light at, for example, θ=−75° in the second region. That is, FIG. 14 illustrates a two-dimensional luminous intensity distribution obtained when a group of light rays having an angular spread of ±90° in the longitudinal direction B of cover 24 travels in the direction of θ=−75° and transmits through second prism portion 401 of FIG. 13. Like FIG. 6, FIG. 14 is a polar coordinate graph centered on θ=0°, with the X axis corresponding to the short-side direction A and the Y axis corresponding to the longitudinal direction B. The concentric circles in FIG. 14 represent latitudes in 10-degree increments. The numbers in the boxes on the right side of FIG. 14 indicate the luminous intensity values ​​corresponding to the colors shown in the two-dimensional luminous intensity distribution of FIG. 14. Note that the two-dimensional luminous intensity distribution diagram illustrated in FIG. 14 is intended to illustrate the angular direction of light emitted from lighting device 1 and is different from real space coordinates.

[0056] As shown in FIG. 14 , in the second region, the two-dimensional light distribution is curved into a thin crescent shape, with both ends gradually bending in the negative direction of the X axis. Specifically, a group of light rays having a spread angle within ±20° in the longitudinal direction B (a group of light rays in range W1 in FIG. 14 ) exists on the Y axis, and therefore travels in the direction of approximately 0° in the lateral direction A. On the other hand, a group of light rays having a spread angle of ±20° or more in the longitudinal direction B (a group of light rays in range W2 in FIG. 14 ) curves in the negative direction of the X axis as the angle increases. In this way, as the angle in the longitudinal direction B increases, the lateral direction A shifts in the negative direction. That is, in the cross-sectional views of FIGS. 2 and 4 , the light is bent to the left. Therefore, for a group of light rays in range W2 in the longitudinal direction B, the second prism portion 401 deflects the light that would otherwise be shifted in the positive direction in the negative direction.

[0057] 15 and 16 are explanatory diagrams showing the prism shape of the second prism unit and the light traveling direction of the lighting device according to the first embodiment. FIGS. 15 and 16 show how, in the second region, the second prism unit 401 deflects light shifted in the positive direction in the negative direction using the second radiation mechanism. In FIG. 15, the light is deflected at an angle of 6° with respect to the first direction D, and in FIG. 16, the light is deflected at an angle of 15° with respect to the first direction D. Hereinafter, the angle formed between the first direction D and the light traveling direction P is referred to as the "light deflection angle θ2." That is, FIG. 15 shows the case where θ2 = 6°, and FIG. 16 shows the case where θ2 = 15°. For comparison with FIG. 13, FIGS. 15 and 16 also show the state of a point in the second region where θ = -75°, for example, as in FIG. 13.

[0058] In Figure 15, the inclination angle of the second exit surface 401b is set so that light traveling in a direction inclined by θ degrees from the optical axis H is totally reflected by the reflecting surface 401a and deflected in a positive direction by 6 degrees from the first direction D by passing through the second prism section 401.

[0059] In Figure 16, the inclination angle of the second exit surface 401b is set so that light traveling in a direction inclined by θ degrees from the optical axis H is totally reflected by the reflecting surface 401a and deflected in a positive direction by 15 degrees from the first direction D by passing through the second prism section 401.

[0060] By gradually increasing the inclination angles of reflecting surface 401a and second exit surface 401b of second prism portion 401 with respect to plane E and approaching perpendicular plane F, the exit angle can be increased to 6° and 15°. That is, the larger the angle formed by second exit surface 401b and plane E, the larger the absolute value of light deflection angle θ2 can be. Note that plane E is, for example, a plane parallel to substrate 22 shown in FIG. 1, and perpendicular plane F is a plane perpendicular to plane E.

[0061] Here, a method of using second prism portion 401 to condense light in short-side direction A and diffuse light in long-side direction B in the second region of cover 24 will be described with reference to FIG. 17 . FIG. 17 is a diagram illustrating a two-dimensional light distribution of light emitted from an exit surface on which a plurality of second prism portions are formed in the lighting device according to embodiment 1. In FIG. 17 , solid line 93 represents the two-dimensional light distribution of light emitted from second prism portion 401 when θ1 = 0° (i.e., the case of FIG. 13 ). Therefore, solid line 93 is the same as the two-dimensional light distribution shown in FIG. 14 . Also, in FIG. 17 , dashed line 94 represents the two-dimensional light distribution of light emitted from second prism portion 401 when θ1 = 6° (i.e., the case of FIG. 15 ). Also, in FIG. 9 , dotted line 95 represents the two-dimensional light distribution of light emitted from second prism portion 401 when θ1 = 15° (i.e., the case of FIG. 16 ).

[0062] The second prism portion 401 is also designed in the same way as the first prism portion 400. That is, the light concentration and diffusion that are considered here are the concentration on the X-axis and the diffusion on the Y-axis of the two-dimensional light distribution diagram. As described above with reference to FIG. 14, in the light extraction method of the second prism portion 401 (i.e., the method shown in FIG. 13 in which the light is reflected by the reflecting surface 401a and transmitted through the opposing second exit surface 401b), when the light is extracted in the front direction as viewed on the X-axis, a light distribution curved to the left is obtained, as indicated by the solid line 93 in the two-dimensional light distribution diagram of FIG. 17. With the same light extraction method, if the extraction angle is changed from θ2 = 6° shown in FIG. 15 (dashed line 94 in FIG. 17) to θ2 = 15° shown in FIG. 16 (dotted line 95 in FIG. 17), the two-dimensional light distribution diagram shifts to the right while maintaining its leftward curve, as shown in FIG. 17.

[0063] When these three beams of light indicated by solid line 93, dashed line 94, and dotted line 95 are integrated, the beam spreads only to approximately 0°, 6°, and 15° on the X axis, whereas the beam spreads to ±20°, ±32° (excluding ±20°), and ±46° (excluding ±32°) on the Y axis, resulting in the sum of the beams. Therefore, the total beam spread of the three beams is ±13° on the X axis (i.e., focused beam) and ±46° on the Y axis (i.e., diffused beam). While FIG. 17 shows the case where the beams emitted from three second prism portions 401 are integrated, three or more second prism portions 401 are formed on cover 24. Therefore, in the second region of cover 24, the beam can be more precisely focused in the short-side direction A and diffused in the long-side direction B.

[0064] 18 to 20 show the light distribution on the X axis and the Y axis of each of the above-mentioned individual lights shown in FIG.

[0065] Fig. 18 is a diagram showing the light distribution in the short side direction A and the long side direction B in the case of the second prism portion shown in Fig. 13. Fig. 19 is a diagram showing the light distribution in the short side direction A and the long side direction B in the case of the second prism portion shown in Fig. 15. Fig. 20 is a diagram showing the light distribution in the short side direction A and the long side direction B in the case of the second prism portion shown in Fig. 16. That is, Fig. 18 shows the case when θ2=0°, Fig. 19 shows the case when θ2=6°, and Fig. 20 shows the case when θ2=15°.

[0066] 18 to 20, the horizontal axis represents the light emission angle θ (see FIGS. 13, 15, and 16), and the vertical axis represents the luminous intensity. In addition, in FIGS. 18 to 20, the thin lines represent the light distribution along the short direction A, and the thick lines represent the light distribution along the long direction B.

[0067] In the light distribution with a deflection angle θ2=0° shown in FIG. 18, the lateral direction A has a trapezoidal distribution shape with a width of ±3° centered at 0° and the longitudinal direction B has a trapezoidal distribution shape with a width of ±20° centered at 0°.

[0068] In the light distribution with a deflection angle θ2=6° shown in FIG. 19, the width of the width direction A is ±2° around 6°, and the width of the length direction B is ±32°.

[0069] In the light distribution with a deflection angle θ2=15° shown in FIG. 20, the width of the lateral direction A is ±2° around 15°, and the longitudinal direction B has a distribution shape with peaks at ±45°.

[0070] In this way, in the second region, the light distribution is adjusted by utilizing the characteristic that a group of light rays spreading in the longitudinal direction B assumes a curved shape in the two-dimensional light distribution diagram (see FIG. 14). Specifically, for a group of light rays having a spreading angle of ±20° or more in the longitudinal direction B (a group of light rays in range W2 in FIG. 14), a group of light rays tilted in the positive direction of the X axis from a deflection angle of 0° is added together. This results in a light distribution in which light is concentrated in the short direction and diffused in the long direction. To achieve this, in a cross-sectional view perpendicular to the longitudinal direction of cover 24, the angle formed between second exit surface 401b of second prism portion 401 and plane E parallel to substrate 22 (i.e., inclination angle θγ of second exit surface 401b) should monotonically decrease with increasing distance from optical axis H. In embodiment 1, the second prism portion 401 is formed in this manner, so that the second prism portion 401 can be used to concentrate light in the short direction A and diffuse light in the long direction B in the second region of the cover 24.

[0071] As described above, in the first region where the emission angle θ of light from light source 21 is in the range of 0° to ±60°, the first emission mechanism is used to deflect the light by first prism unit 400, which simply transmits the light. On the other hand, in the second region where the emission angle θ of light from light source 21 is in the range of ±60° to ±90°, the second emission mechanism is used to deflect the light by second prism unit 401, which totally reflects the light and then emits the light from the emission surface opposite the reflection surface. As a result, in a cross section perpendicular to longitudinal direction B of cover 24, a light distribution in which light is concentrated in the short direction and diffused in the long direction can be obtained in both the first region and the second region.

[0072] Furthermore, in the first region, the light emitted from the first prism portion 400 curves in the positive short-side direction as the angle in the long-side direction increases in a two-dimensional light distribution diagram (see FIG. 6), and this property is utilized to add up the light emitted from a plurality of first prism portions 400 having different inclination angles θα of the first exit surfaces 400a of the first prism portions 400. This makes it possible to add up a group of light rays whose deflection angle θ1 is tilted from 0° in the negative direction of the X axis, thereby obtaining a light distribution that is focused in the short-side direction and diffused in the long-side direction.

[0073] Similarly, in the second region, the light emitted from second prism portion 401 has a characteristic that, as the angle in the longitudinal direction increases, the light is curved in the negative direction in the lateral direction in a two-dimensional light distribution diagram (see FIG. 14), and this characteristic is utilized to add up the light emitted from multiple second prism portions 401 having different inclination angles θγ of second exit surfaces 401b of second prism portion 401. This makes it possible to add up a group of light rays whose deflection angle θ2 is tilted from 0° in the positive direction of the X axis, thereby obtaining a light distribution that is focused in the lateral direction and diffused in the longitudinal direction.

[0074] 21 is a diagram showing the light distribution in the short-side direction A and the long-side direction B of light emitted from all of the first prism portions and second prism portions formed on the cover in the lighting device according to embodiment 1. In FIG. 21, the horizontal axis represents the light emission angle θ, and the vertical axis represents luminous intensity. In FIG. 21, the thin line represents the light distribution along the short-side direction A, and the thick line represents the light distribution along the long-side direction B.

[0075] In the light distribution shown in FIG. 21, the width direction A is a trapezoidal distribution shape that extends over a width of ±10° with 0° as the center and the length direction B is a trapezoidal distribution shape that extends over a width of ±35° with 0° as the center.

[0076] FIG. 22 is a layout diagram showing an arrangement in which the lighting device according to the first embodiment is used as a blackboard lamp. In FIG. 22, the distance between the ceiling surface 4 and the floor surface 5 is 3000 mm. In this case, the lighting device 1 is attached to the ceiling surface 4, which is 1500 mm away from the wall surface 6 in the horizontal direction, and is arranged so that the lighting device 1 illuminates a blackboard 7 installed on the wall surface 6. That is, the longitudinal direction of the lighting device 1 is arranged parallel to the blackboard surface 7c. Furthermore, the lighting device 1 is rotated around the central axis extending in the longitudinal direction of the lighting device 1 as the axis of rotation so that the angle between the front direction of the light source unit 2 and the ceiling surface 4 is φ°, and the front of the lighting device 1 faces the blackboard surface 7c. The lower end 7a of the blackboard 7 is positioned 900 mm away from the floor surface 5 in the vertical direction, and the upper end 7b of the blackboard 7 is positioned 2100 mm away from the floor surface 5 in the vertical direction. 1. The position of the blackboard surface 7c of the blackboard 7 is from the position of the lower end 7a to the position of the upper end 7b. Note that the ceiling surface 4 is an example of the attachment portion 100 in FIG.

[0077] The lighting device 1 is disposed so that the front of the light source unit 2 faces the intersection line 50 between the floor surface 5 and the wall surface 6. Therefore, a direction 50a at an angle θa (=63.4°) from the floor surface 5, which is plane E, is the front direction of the light source unit 2. Furthermore, the lower end 7a of the blackboard 7 is angled at an angle θb (=54.5°) from the floor surface 5, which is plane E, and the upper end 7b of the blackboard 7 is angled at an angle θc (=31.0°) from the floor surface 5, which is plane E.

[0078] 22, the angle of light directed toward the bottom edge 7a of the blackboard 7 is 8.9°, which is obtained by subtracting the angle of 54.5° at the bottom edge 7a of the blackboard 7 from the angle of 63.4° at the front of the light source unit 2. Similarly, the angle of light directed toward the top edge 7b of the blackboard 7 is 32.4°, which is obtained by subtracting the angle of 31.0° at the top edge 7b of the blackboard 7 from the angle of 63.4° at the front of the light source unit 2.

[0079] Therefore, the angle of light emitted from the light source unit 2 toward the entire blackboard surface 7c of the blackboard 7 is in the range of 8.9° to 32.4°. In other words, light in the range of approximately 9° to 30° is emitted directly from the front of the light source unit 2 onto the blackboard surface 7c of the blackboard 7.

[0080] Furthermore, since the illuminance of blackboard surface 7c of blackboard 7 is inversely proportional to the square of the distance from light source 21, the light distribution of light source 21 must be designed so that the luminous intensity value does not decrease, particularly in the range of 10 to 20°. The light distribution in Fig. 19 almost satisfies the conditions for light distribution in short-side direction A.

[0081] The arrangement of the lighting device 1 is not limited to the example arrangement shown in Fig. 22. For example, the lighting device 1 may be arranged so that the front surface of the light source unit 2 faces the center of the height direction of the blackboard surface 7c of the blackboard 7, i.e., the center between the lower end 7a and the upper end 7b of the blackboard 7.

[0082] As described above, in the lighting device 1 according to the first embodiment, the cover 24 has the incident surface 24a and the exit surface 24b, the first prism portion 400 is provided in a first region of the exit surface 24b, and the second prism portion 401 is provided in a second region of the exit surface 24b. The first prism portion 400 has a first exit surface 400a that refracts light incident on the incident surface 24a, deflects the light in a first direction D, and emits the light. The second prism portion 401 has a reflecting surface 401a that totally reflects the light incident on the incident surface 24a, and a second exit surface 401b that refracts the light totally reflected by the reflecting surface 401a, deflects the light in the first direction D, and emits the light. This makes it possible to obtain a light distribution in which the light is concentrated in the short direction and diffused in the long direction in both the first and second regions in a cross section of the cover 24 that is perpendicular to the longitudinal direction B.

[0083] Furthermore, in the lighting device 1 according to embodiment 1, light is emitted in the front direction (first direction D) from almost the entire surface of the cover 24, so that the glare experienced when the user looks directly at the lighting device 1 can be reduced.

[0084] Embodiment 2 Fig. 23 is an explanatory diagram showing the prism shape of the third prism portion and the traveling direction of light of the lighting device according to embodiment 2. Fig. 23 shows third prism portion 402 provided in the first region (see Fig. 4) or the second region (see Fig. 4) of cover 24. Note that Fig. 23 shows the state of a point in the first region where θ = -30°, for example. Fig. 24 is a diagram schematically showing the prism shape of the third prism portion shown in Fig. 23.

[0085] The difference between the first and second embodiments is that the second embodiment has a trapezoidal third prism portion 402 instead of the triangular first prism portion 400 and second prism portion 401. The other configurations are the same as those of the first embodiment, and therefore will not be described here.

[0086] (Third prism portion 402 and third radiation mechanism) As shown in Figures 23 and 24, the third prism portion 402 is formed by integrating the first prism portion 400 and the second prism portion 401 into a trapezoidal shape. The third prism portion 402 has a trapezoidal cross-sectional shape in a cross-sectional view perpendicular to the longitudinal direction B of the cover 24. The third prism portion 402 emits light using a third emission mechanism. The third emission mechanism is a combination of the first emission mechanism and the second emission mechanism.

[0087] 23 and 24, third prism portion 402 has first exit surface 400a, second exit surface 401b, and reflecting surface 401a. First exit surface 400a and reflecting surface 401a are adjacent to and connected to each other. Furthermore, reflecting surface 401a and second exit surface 401b are arranged opposite each other with first exit surface 400a in between. First exit surface 400a and second exit surface 401b are adjacent to and connected to each other.

[0088] In FIG. 23, light rays 41 are a group of light rays emitted from first emission surface 400a, and light rays 42 are a group of light rays emitted from second emission surface 401b after being totally reflected by reflecting surface 401a.

[0089] The inclination angle θα of first exit surface 400a is set so that light traveling in a direction inclined by θ° from optical axis H passes through incident surface 24a of cover 24 and then passes through third prism portion 402, thereby being deflected in the direction in which light ray 41 travels. The direction in which light ray 41 travels is, for example, θ1 = -15°, but is not limited to this. In this way, the inclination angle θα of first exit surface 400a is determined for each point on cover 24 by the direction in which light ray 41 travels and the light emission angle θ°.

[0090] The inclination angle θβ of the reflecting surface 401a is set so that light traveling in a direction inclined by θ° from the optical axis H is totally reflected and enters the second exit surface 401b. The inclination angle θγ of the second exit surface 401b is set so that the light totally reflected by the reflecting surface 401a is deflected in the direction of the light ray 42 as it passes through the second prism unit 401. The direction of the light ray 42 is, for example, θ2 = 12°, but is not limited to this. Although the directions of the light ray 41 and the light ray 42 are different in this example, they may be the same and may be set appropriately depending on the application of the lighting device 1. Thus, the inclination angle θβ of the reflecting surface 401a and the inclination angle θγ of the second exit surface 401b are determined for each point on the cover 24 by the direction of the light ray 42 and the light emission angle θ°.

[0091] 23 and 24, third prism portion 402 has a trapezoidal or substantially trapezoidal cross-sectional shape in a cross section perpendicular to the longitudinal direction of cover 24. Third prism portion 402 protrudes from exit surface 24b of cover 24 toward the irradiation side. Third prism portion 402 is arranged side by side at regular intervals.

[0092] 23, the cross-sectional shape of third prism portion 402 is not a strict trapezoid but has rounded corners because of consideration of the processing limitations of the mold. Therefore, third prism portion 402 may have a trapezoidal shape with sharp corners if the processing limitations of the mold allow. Furthermore, while a trapezoidal shape generally has at least one pair of opposing sides parallel to each other, in the cross-sectional shape of third prism portion 402, first exit surface 400a and the side opposing first exit surface 400a do not have to be strictly parallel. Thus, third prism portion 402 has a trapezoidal or approximately trapezoidal cross-sectional shape, and these will be collectively referred to as a "trapezoidal shape."

[0093] As described above, in the second embodiment, third prism unit 402 emits light using a third emission mechanism that combines the first emission mechanism and the second emission mechanism. Specifically, first emission surface 400a uses the first emission mechanism to simply transmit light and deflect the light. Meanwhile, reflecting surface 401a and second emission surface 401b use the second emission mechanism to totally reflect the light and then emit it from the emission surface opposite the reflecting surface, thereby deflecting the light. This makes it possible to obtain a light distribution in both the first and second regions in a cross section perpendicular to longitudinal direction B of cover 24, where the light is concentrated in the short direction and diffused in the long direction.

[0094] In addition, the third prism portion 402 may be arranged in place of some of the first prism portions 400 or some of the second prism portions 401, and the first prism portions 400, second prism portions 401, and third prism portions 402 may be mixed throughout the cover 24.

[0095] As described above, third prism portion 402 of embodiment 2 is a trapezoidal prism, rather than a simple triangle like first prism portion 400 or second prism portion 401 of embodiment 1. As a result, third prism portion 402 of embodiment 2 can generate a group of light rays (light rays 41) that simply transmits and a group of light rays (light rays 42) that transmit after total reflection, as shown in Fig. 23 .

[0096] Fig. 25 is a diagram showing the light distribution in the short-side direction A and the long-side direction B for the third prism portion shown in Fig. 23. In Fig. 25, the horizontal axis represents the angle, and the vertical axis represents the luminous intensity. In Fig. 25, the thin line represents the light distribution along the short-side direction A, and the thick line represents the light distribution along the long-side direction B.

[0097] 25, light ray 41 is emitted at -15° and light ray 42 is emitted at 12° in the short-side direction A. On the other hand, in the long-side direction B, light ray 41 peaks at ±20° and light ray 42 peaks at ±37°.

[0098] In this way, in the second embodiment, the light is split into two beams, one in the positive direction and one in the negative direction of the short-side direction A, and emitted from the single third prism portion 402. This makes it possible to further reduce the glare experienced when the user looks up at the lighting device 1, compared to the first embodiment in which the light is output without being split.

[0099] In the above description, a trapezoidal third prism portion 402 is provided in place of the triangular first prism portion 400 and second prism portion 401 in the first or second region of the cover 24. However, this is not limited to this case. That is, in a portion of the first region, where the emission angle θ of light from the light source 21 is in the range of 0° to ±45°, i.e., in the range of -45°<θ<45°, the first radiation mechanism is used to deflect the light with the first prism portion 400, which simply transmits the light. In the third region, which includes the boundary between the first and second regions, the third radiation mechanism is used to deflect the light with the third prism portion 402. The third region is, for example, a region where the emission angle θ of light from the light source 21 is in the range of ±45° to ±65°, i.e., in the ranges of -65°≦θ≦-45° and 45°≦θ≦65°. In addition, in the remaining part of the second region, the light is deflected by the second prism unit 401, which uses the second radiation mechanism to totally reflect the light and then emits the light from the emission surface opposite the reflection surface. Note that the remaining part of the second region refers to the region where the emission angle θ of the light from the light source 21 is in the range of ±65° to ±90°, i.e., the ranges of -90°<θ<-65° and 65°<θ<90°.

[0100] As described above, in lighting device 1 according to embodiment 2, cover 24 uses trapezoidal third prism portion 402 in at least a portion of the first region and in at least a portion of the second region. Third prism portion 402 has first exit surface 400a having a function similar to first exit surface 400a of first prism portion 400, and reflecting surface 401a and second exit surface 401b having a function similar to reflecting surface 401a and second exit surface 401b of second prism portion 401. Therefore, as in embodiment 1, a light distribution in which light is concentrated in the short direction and diffused in the long direction can be obtained in both the first region and the second region in a cross section perpendicular to longitudinal direction B of cover 24.

[0101] Furthermore, in the second embodiment, at least a part of the first region and at least a part of the second region use third prism portion 402 that is trapezoidal, rather than a simple triangle like first prism portion 400 or second prism portion 401 in the first embodiment. As a result, third prism portion 402 in the second embodiment can generate, with a single prism, both a group of light rays that simply transmit (light rays 41) and a group of light rays that transmit after total reflection (light rays 42).

[0102] Furthermore, in the second embodiment, the light is split into two beams, one in the positive direction and one in the negative direction of the short-side direction A, and emitted from the single third prism portion 402. This makes it possible to further reduce the glare experienced when the user looks up at the lighting device 1, compared to the first embodiment in which the light is output without being split.

[0103] Embodiment 3 26 is a vertical cross-sectional view showing the configuration of a light source unit provided in an illumination device according to embodiment 3. In a light source unit 2A according to embodiment 3, the light source 21, the substrate 22, the frame 23, and the reflector 25 have the same configurations as those in embodiment 1, and only the shape of the light-transmitting cover 24A is different. Therefore, in embodiment 3, the cover 24A will be mainly described, and a description of the other configurations will be omitted.

[0104] In the above-described first embodiment, as shown in FIG. 2, the incident surface 24a of the cover 24 has an arc-shaped cross-section in a cross section perpendicular to the longitudinal direction of the cover 24. On the other hand, in the third embodiment, as shown in FIG. 26, the incident surface 24aA of the cover 24 has a straight portion 24aA-1 and a curved portion 24aA-2 in a cross section perpendicular to the longitudinal direction of the cover 24. The straight portion 24aA-1 is formed in a region near the optical axis H, including the optical axis H of the light from the light source 21. The curved portion 24aA-2 is formed in a region outside the straight portion 24aA-1. The straight portion 24aA-1 is a portion of the first region. The straight portion 24aA-1 has a straight shape in a cross section perpendicular to the longitudinal direction of the cover 24. The curved portion 24aA-2 has an arc-shaped cross-section in a cross section perpendicular to the longitudinal direction of the cover 24.

[0105] Fig. 27 is an explanatory diagram showing the prism shape and light traveling direction of the first prism portion of the lighting device according to embodiment 3. Fig. 27 is an enlarged view of the portion surrounded by dashed line R3 in Fig. 26. That is, Fig. 27 shows first prism portion 400A provided in the first region. Note that Fig. 27 shows the state of a point in the first region where θ = -30°, for example. As shown in Fig. 27, first prism portion 400A has a triangular cross-sectional shape in a cross section perpendicular to the longitudinal direction of cover 24.

[0106] First prism section 400A in the third embodiment differs from first prism section 400 in the first embodiment in the angle of the first exit surface. The dashed line in FIG. 27 indicates first exit surface 400a of first prism section 400 in FIG. 5. As can be seen from FIG. 27, first exit surface 400aA in the third embodiment has an inclination angle that is closer to parallel to plane E than first exit surface 400a in the first embodiment. That is, inclination angle θαA formed between first exit surface 400aA in the third embodiment and plane E is smaller than inclination angle θα formed between first exit surface 400a in the first embodiment and plane E.

[0107] The reason why the inclination angle θαA of the first emission surface 400aA in the third embodiment is smaller than the inclination angle θα of the first emission surface 400a in the first embodiment is as follows. The region where the first prism portion 400A in the third embodiment is provided is the linear portion 24aA-1 of the incident surface 24aA of the cover 24. Therefore, in this region, as shown in FIG. 27 , the incident surface 24aA is horizontal, and when light from the light source 21 enters the incident surface 24aA, the light is deflected in the first direction D in which it is desired to be emitted. In this way, in the third embodiment, the incident surface 24a changes the direction of the light to a certain extent, so that it is not necessary to deflect the light significantly at the first emission surface 400aA. Therefore, the inclination angle θαA of the first emission surface 400aA in the third embodiment is smaller than the inclination angle θα of the first emission surface 400a in the first embodiment.

[0108] On the other hand, in order to significantly deflect light at first light exit surface 400a, it is necessary to increase the inclination angle θα between the light ray and first light exit surface 400a. However, as the inclination angle θα increases, the amount of light that can be extracted at first light exit surface 400a decreases.

[0109] In contrast, in the third embodiment, the linear portion 24aA-1 of the cover 24A changes the traveling direction of light little by little on both the incident surface 24a and the first exit surface 400aA. Therefore, the amount of light that can be extracted can be increased compared to the first embodiment, in which the light is largely deflected by one surface (first exit surface 400a).

[0110] Note that the region where linear portion 24aA-1 is provided on incident surface 24aA of cover 24 is the first region, and therefore the operation of the second region is the same as in embodiment 1. That is, second prism portion 401 provided in the second region has the same configuration and operation as second prism portion 401 in embodiment 1, and therefore a description thereof will be omitted here.

[0111] As described above, in the lighting device 1 according to the third embodiment, the cover 24A has the first prism portion 400 and the second prism portion 401, similar to the first embodiment. Therefore, similar to the first embodiment, in a cross section perpendicular to the longitudinal direction B of the cover 24A, a light distribution in which light is concentrated in the short direction and diffused in the long direction can be obtained in both the first region and the second region.

[0112] Furthermore, in the third embodiment, incident surface 24aA of cover 24 has, in a cross section perpendicular to the longitudinal direction of cover 24, straight portion 24aA-1 formed in a region near optical axis H and curved portion 24aA-2 formed outside straight portion 24aA-1. Therefore, in straight portion 24aA-1, the traveling direction of light is changed slightly at both incident surface 24a and first exit surface 400aA. Therefore, the amount of extracted light can be increased compared to the first embodiment, in which light is largely deflected at one surface (first exit surface 400a). [Explanation of symbols]

[0113] 1 lighting device, 2 light source unit, 2A light source unit, 3 main body, 3a upper surface, 3b lower surface, 3c holder, 4 ceiling surface, 5 floor surface, 6 wall surface, 7 blackboard, 7a lower end, 7b upper end, 7c blackboard surface, 20 light source unit, 21 light source, 22 substrate, 22a lower surface, 23 frame, 24 cover, 24A cover, 24a incident surface, 24aA incident surface, 24aA-1 straight portion, 24aA-2 curved portion, 24b exit surface, 25 reflector, 25a inclined surface, 41 light ray, 42 light ray, 50 intersection line, 50a direction, 90 solid line, 91 dashed line, 92 dotted line, 93 solid line, 94 dashed line, 95 dotted line, 100 mounted portion, 240 Cover main body portion, 241 cover end portion, 242 light-transmitting portion, 242a light-transmitting main portion, 242b light-transmitting side portion, 243 cover flat portion, 400 first prism portion, 400-1 prism group, 400-2 prism group, 400A first prism portion, 400a first emission surface, 400aA first emission surface, 401 second prism portion, 401-1 prism group, 401-2 prism group, 401a reflection surface, 401b second emission surface, 402 third prism portion, A short-side direction, B long-side direction, D first direction, E plane, F vertical plane, H optical axis, P traveling direction, R1 dashed line, R2 dashed line, R3 dashed line, W1 range, W2 range, Y short-side direction, θ emission angle, θ1 Deflection angle, θ2 deflection angle, θa angle, θb angle, θc angle, θα tilt angle, θαA tilt angle, θβ tilt angle, θγ tilt angle.

Claims

1. A light source unit; a main body portion attached to a mounting portion and on which the light source unit is mounted; Equipped with The light source unit is A light source and a substrate on which the light source is mounted; a cover that covers the light source and the substrate; and the cover has an arc-shaped cross section in a cross section perpendicular to the longitudinal direction of the cover, the cover has an incident surface onto which light from the light source is incident and an exit surface from which the light incident on the incident surface is emitted, the exit surface of the cover has a first prism portion and a second prism portion; the first prism portion has a first exit surface that refracts the light incident on the entrance surface, deflects the light toward a first direction including the direction of an optical axis of the light from the light source, and emits the deflected light, the second prism portion has a reflecting surface that totally reflects the light incident on the incident surface, and a second exit surface that refracts the light totally reflected by the reflecting surface, deflects the light toward the first direction, and exits the light, In a cross-sectional view perpendicular to a longitudinal direction of the cover, the first prism portion is provided in a first region including a direction of the optical axis, In a cross-sectional view perpendicular to the longitudinal direction of the cover, an inclination angle of the first exit surface, which is an angle formed between the first exit surface and a plane parallel to the substrate, monotonically increases with increasing distance from the optical axis, In the first region, the light emitted from the first prism portion has a characteristic that, as the angle in the longitudinal direction increases, the light curves in a positive direction in the short-side direction, which is a direction perpendicular to the longitudinal direction, in a two-dimensional light distribution diagram. By utilizing this characteristic, light emitted from a plurality of first prism portions having different inclination angles of the first exit surfaces of the first prism portions is integrated to obtain a light distribution in which light is concentrated in the short-side direction and diffused in the longitudinal direction. Lighting equipment.

2. In a cross-sectional view perpendicular to the longitudinal direction of the cover, the second prism portion is provided in a second region formed outside the first region. The lighting device according to claim 1 .

3. In a cross-sectional view perpendicular to the longitudinal direction of the cover, an inclination angle of the second exit surface, which is an angle formed between the second exit surface and a plane parallel to the substrate, monotonically decreases with increasing distance from the optical axis.

3. The lighting device according to claim 1 or 2.

4. In a cross-sectional view perpendicular to the longitudinal direction of the cover, the second prism portion is provided in a second region formed outside the first region, In a cross-sectional view perpendicular to the longitudinal direction of the cover, an inclination angle of the second exit surface, which is an angle formed between the second exit surface and a plane parallel to the substrate, monotonically decreases with increasing distance from the optical axis, In the second region, by utilizing a characteristic that the light emitted from the second prism portion curves in a negative direction of a short side perpendicular to the long side as the angle of the long side increases in a two-dimensional light distribution diagram, light emitted from a plurality of second prism portions having different inclination angles of the second exit surfaces of the second prism portions is integrated, thereby obtaining a light distribution in which light is concentrated in the short side direction and diffused in the long side direction. The lighting device according to claim 1 .

5. A light source unit; a main body portion attached to a mounting portion and on which the light source unit is mounted; Equipped with The light source unit is A light source and a substrate on which the light source is mounted; a cover that covers the light source and the substrate; and the cover has an arc-shaped cross section in a cross section perpendicular to the longitudinal direction of the cover, the cover has an incident surface onto which light from the light source is incident and an exit surface from which the light incident on the incident surface is emitted, the exit surface of the cover has a first prism portion and a second prism portion; the first prism portion has a first exit surface that refracts the light incident on the entrance surface, deflects the light toward a first direction including the direction of an optical axis of the light from the light source, and emits the deflected light, the second prism portion has a reflecting surface that totally reflects the light incident on the incident surface, and a second exit surface that refracts the light totally reflected by the reflecting surface, deflects the light toward the first direction, and exits the light, In a cross-sectional view perpendicular to the longitudinal direction of the cover, the second prism portion is provided in a second region formed outside a first region including the direction of the optical axis, In a cross-sectional view perpendicular to the longitudinal direction of the cover, an inclination angle of the second exit surface, which is an angle formed between the second exit surface and a plane parallel to the substrate, monotonically decreases with increasing distance from the optical axis, In the second region, by utilizing a characteristic that the light emitted from the second prism portion curves in a negative direction of a short side perpendicular to the long side as the angle of the long side increases in a two-dimensional light distribution diagram, light emitted from a plurality of second prism portions having different inclination angles of the second exit surfaces of the second prism portions is integrated, thereby obtaining a light distribution in which light is concentrated in the short side direction and diffused in the long side direction. Lighting equipment.

6. In a cross-sectional view perpendicular to the longitudinal direction of the cover, the first prism portion is provided in the first region.

6. The lighting device according to claim 5.

7. In a cross-sectional view perpendicular to the longitudinal direction of the cover, an inclination angle of the first light exit surface, which is an angle formed between the first light exit surface and a plane parallel to the substrate, monotonically increases with increasing distance from the optical axis.

7. The lighting device according to claim 5 or 6.

8. the first direction is a front direction including the direction of the optical axis; The lighting device according to any one of claims 1 to 7.

9. In a cross-sectional view perpendicular to the longitudinal direction of the cover, the cross-sectional shape of the first prism portion is triangular. The lighting device according to any one of claims 1 to 8.

10. In a cross-sectional view perpendicular to the longitudinal direction of the cover, the cross-sectional shape of the second prism portion is triangular. The lighting device according to any one of claims 1 to 9.

11. a plurality of the first prism portions and a plurality of the second prism portions are provided, the at least one first prism portion and the at least one second prism portion are integrally configured to have a trapezoidal cross-sectional shape in a cross-sectional view perpendicular to the longitudinal direction of the cover, thereby forming a third prism portion; In the third prism portion, the first exit surface of the first prism portion and the reflecting surface of the second prism portion are adjacent to each other and connected to each other, and the reflecting surface of the second prism portion and the second exit surface are arranged opposite each other with the first exit surface of the first prism portion interposed therebetween. The lighting device according to any one of claims 1 to 10.

12. In a cross-sectional view perpendicular to a longitudinal direction of the cover, the third prism portion is provided in a third region including a boundary between the first region and a second region formed outside the first region, the third region is a region including a part of the first region and a part of the second region; 12. The lighting device according to claim 11.

13. The incident surface of the cover has, in a cross-sectional view perpendicular to the longitudinal direction of the cover, a straight portion formed in the vicinity of the optical axis and a curved portion formed outward from the straight portion. The lighting device according to any one of claims 1 to 12.

Images