CN209762867U - Lighting apparatus - Google Patents

Abstract

A lighting fixture includes a light source and a light guide plate (22) for lighting that guides light from the light source and emits the light. The light guide plate (22) has a plurality of microscopic optical structures on at least the 1 st surface (A1) of both side surfaces in the thickness direction, and the microscopic optical structures are arranged in a dispersed manner in at least a partial region of the 1 st surface (A1) by an FM screen method.

Description

Lighting apparatus

Technical Field

The present application relates to a lighting device using a light guide plate.

Background

Japanese patent application laid-open No. 2013-101858 describes a lighting device using a light guide plate. The light guide plate includes an incident portion into which light from the light emitting element is incident, an exit portion from which light incident on the incident portion is emitted, and a light guide portion formed between the incident portion and the exit portion. The light guide portion extends from the incident portion to the emission portion while being curved. The light incident on the light guide unit from the light incident unit is reflected on the outer peripheral surface of the light guide unit on the side where the light guide unit protrudes, and is guided to the light emitting unit. The light-scattering pattern for scattering light is formed in the emission portion, and includes a concave-convex shape having fine recesses and protrusions.

Japanese patent No. 4243633 discloses that a light guide plate used in a liquid crystal display device is patterned to have a plurality of minute dots scattered thereon, and that an fm (frequency modulated) screen (screen) method is used to represent the gradation of an image by a binarization method using the density of the minute dots.

In the lighting apparatus described in japanese patent application laid-open No. 2013-101858, when a person observes the light guide plate, the light guide plate is formed with the concave-convex shape, and when the regularity of the arrangement of the concave-convex shape is deviated from other positions, the person may easily feel that a pattern based on a local brightness difference is formed. Further, when the density of the uneven shape is locally or entirely increased, a flat portion effective for controlling the light distribution in the light guide plate is reduced, and therefore it is difficult to maintain high light distribution controllability. The structure described in japanese patent No. 4243633 is a structure in which a plurality of fine dots are scattered is formed on a light guide plate for a liquid crystal display device, and is premised on use as a backlight (light) for illuminating from the back side of a display portion, and therefore the light guide plate is not directly used as a product surface. In the case of a backlight, the uneven shape is premised on changing the density from the light incident surface, and in japanese patent No. 4243633, it is important to improve the unevenness of the luminance generated in a part of the density gradient and the luminance gradient of the entire light emitting surface. Japanese patent No. 4243633 does not disclose a method of suppressing a feeling of a pattern based on a luminance difference when a plurality of minute optical structures are arranged assuming that a light guide plate is used as a product surface when used in a lighting fixture.

SUMMERY OF THE UTILITY MODEL

An object of the present invention is to provide a lighting fixture that can simultaneously achieve a pattern based on a luminance difference that is less likely to be perceived by a person observing a light guide plate, and maintain high light distribution controllability.

The lighting device according to one aspect of the present application includes a light source and a light guide plate for illumination that guides light from the light source and emits the light, the light guide plate having a plurality of microscopic optical structures on at least the 1 st surface of both side surfaces in a thickness direction, the plurality of microscopic optical structures being arranged in a dispersed manner in at least a partial region of the 1 st surface based on an FM screen method.

According to the lighting fixture of the aspect of the present application, it is possible to simultaneously achieve a situation where a person is less likely to feel a pattern due to a difference in luminance when viewing the light guide plate and a situation where high light distribution controllability is maintained.

the FM screen method may be an ordered dither method, an error diffusion method, or a blue noise mask method.

The light guide plate may include a mounting substrate on which a light emitting element as the light source is mounted, and the light guide plate may include: an incident portion on which light from the light emitting element is incident; an exit portion from which light incident on the entrance portion is supplied; a light guide portion formed between the incident portion and the light emitting portion, extending from the incident portion to the light emitting portion while being curved, having a1 st reflection surface and a2 nd reflection surface on an inner peripheral surface for guiding light incident on the incident portion toward the light emitting portion while reflecting the light, the 1 st reflection surface forming a parabola having a focal point on a cross section when the light guide portion is cut by a virtual plane, the 2 nd reflection surface being disposed on a side closer to the light emitting portion than the 1 st reflection surface on the cross section and being disposed at a position intersecting with a virtual straight line passing through the 1 st reflection surface and the focal point, and the light emitting portion having the 1 st surface on which the plurality of microscopic optical structures are disposed.

The 1 st aspect may include: a1 st region which is arranged on a side close to the light guide portion and does not have a microscopic optical structure; and a2 nd region arranged on a side of the light guide portion farther from the light guide portion than the 1 st region, the plurality of microscopic optical structures being arranged.

The arrangement of the plurality of minute optical structures in the 2 nd region may not have a density gradient.

The plurality of minute optical structures may be concave prisms or reflectors of reflected light formed by printing, respectively.

The plurality of minute optical structures may be prisms each having a concave shape with a diameter of 50 μm to 500 μm.

The light guide plate may have an annular shape and may have an incident surface on which light from the light emitting element is incident.

the 1 st aspect may include: a1 st region which is arranged on a side close to the light emitting element and does not have a microscopic optical structure; and a2 nd region which is disposed on a side farther from the light-emitting element than the 1 st region and in which the plurality of microscopic optical structures are disposed.

The arrangement of the plurality of minute optical structures in the 2 nd region may not have a density gradient.

The plurality of minute optical structures may be formed by screen printing, inkjet printing, or gravure printing, respectively.

Drawings

Fig. 1 is a perspective view showing an appearance of a floor surface side of a lighting fixture according to an embodiment.

Fig. 2 is a perspective view showing an appearance of the lighting apparatus according to the embodiment on the ceiling side.

fig. 3 is an exploded perspective view of the lighting apparatus according to the embodiment, showing a state in which the diffusion cover is removed.

Fig. 4 is an exploded perspective view of the lighting fixture according to the embodiment, showing a state in which the decorative cover, the light guide plate, and the reflecting member are removed.

Fig. 5 is an exploded perspective view of the lighting fixture according to the embodiment.

Fig. 6 is a sectional view a-a of fig. 1.

Fig. 7 is an enlarged cross-sectional view of the left side portion of fig. 6.

Fig. 8 is a plan view of the lighting fixture according to the embodiment, in which the decorative cover, the light guide plate, the reflecting member, and the diffusion cover are omitted.

Fig. 9 is a plan view of the lighting fixture according to the embodiment, showing a state in which the lens cover is further omitted from fig. 8.

Fig. 10 is a view showing the light guide plate taken out of fig. 1, fig. 10 (a) is a perspective view showing the light guide plate, and fig. 10 (B) is a sectional perspective view taken along line B-B of fig. 10 (a).

fig. 11 is a C-C sectional view of fig. 10 (a).

Fig. 12 is a cross-sectional perspective view showing an enlarged view of an incident portion of the light guide plate according to the embodiment.

Fig. 13 is an enlarged view of a portion D of the light guide plate of fig. 7.

Fig. 14 is a view showing a part of the circumferential direction of the 2 nd region of the light emitting portion of the light guide plate of fig. 7 when viewed from the 2 nd surface side.

Fig. 15 (a) corresponds to an enlarged view of the portion F in fig. 7 of the light guide plate in the embodiment, fig. 15 (b) corresponds to an enlarged view of the portion F in fig. 7 of the light guide plate in comparative example 1, and fig. 15 (c) corresponds to an enlarged view of the portion F in fig. 7 of the light guide plate in comparative example 2.

Fig. 16 is a block diagram showing a calculation method used in the error diffusion method for determining the arrangement of the microscopic optical structures on the 1 st surface of the light guide plate in the embodiment.

Fig. 17 is a diagram showing a case where errors generated by comparing the gradation in the brightness of one unit region of an input image with a threshold value are dispersed in neighboring unit regions in the error diffusion method.

Fig. 18 is a diagram showing diffusion coefficients used in the error diffusion method according to the embodiment.

Fig. 19 is a view showing a radial average spectrum of the arrangement of the microscopic optical structures on the 1 st surface of the light guide plate in the embodiment.

Fig. 20 (a) is a view showing a pattern based on a luminance difference generated in the light guide plate in example 1 of the comparative example or example 2, as viewed from the outside of the 2 nd surface of the light guide plate, and fig. 20 (b) is an enlarged view of the portion G of fig. 20 (a).

Fig. 21 (a) is a perspective view showing a2 nd surface of a light guide plate in a2 nd example of a pattern based on a luminance difference generated in the light guide plate in the 1 st or 2 nd example of the comparative example, and fig. 21 (b) is an enlarged view of a portion H of fig. 21 (a).

Fig. 22 is a diagram showing diffusion coefficients used in the error diffusion method in example 1 of another example of the embodiment.

Fig. 23 is a view showing a radial average spectrum of the arrangement of the microscopic optical structures on the 1 st surface of the light guide plate in example 1 of the other example of the embodiment.

Fig. 24 is a view corresponding to fig. 14 in example 1 of another embodiment.

Fig. 25 is a perspective view showing an appearance of a floor surface side in the lighting fixture of example 2 of the other example of the embodiment.

Detailed Description

Hereinafter, embodiments of the present application will be described with reference to the drawings. The shapes, numerical values, materials, constituent elements, and arrangement positions and connection forms of the constituent elements described below are examples for description, and can be appropriately changed according to the specification of the lighting fixture. Hereinafter, the same elements will be described with the same reference numerals throughout the drawings. In the description in the text, the reference numerals described above are used as necessary.

The following describes a lighting fixture according to an embodiment.

[1. construction of Lighting apparatus ]

[ 1-1. integral constitution of Lighting apparatus ]

The overall configuration of the lighting apparatus 2 according to the embodiment will be described with reference to fig. 1 to 5. Fig. 1 is a perspective view showing an appearance of a lighting fixture 2 according to an embodiment on a floor surface side. Fig. 2 is a perspective view showing an appearance of the lighting fixture 2 on the ceiling 4 side. Fig. 3 is an exploded perspective view showing the lighting fixture 2 in a state where the diffusion cover (cover)26 is removed. Fig. 4 is an exploded perspective view showing the lighting fixture 2 in a state where the decorative cover 20, the light guide plate 22, and the reflection member 24 are removed. Fig. 5 is an exploded perspective view of the lighting fixture 2.

the lighting fixture 2 is, for example, a ceiling lamp (ceiling light) that is installed on a ceiling 4 (see fig. 5) of a building such as a house and illuminates a space 6 (see fig. 6 described later) inside the building. As shown in fig. 5, the lighting fixture 2 includes a fixture body 8, a fixture mounting member 10, a power supply unit 12, a reflection cover 14, a light emitting module 16, a lens cover 18, a decorative cover 20, a light guide plate 22, a reflection member 24, and a diffusion cover 26.

Hereinafter, each constituent element of the lighting fixture 2 will be described in detail with reference to fig. 1 to 12. In fig. 1 to 12, the negative side of the Z axis indicates the ceiling 4 side, and the positive side of the Z axis indicates the floor surface (not shown) side. For convenience of explanation, the lighting fixture 2 is illustrated in fig. 1 and 3 to 7 in a posture vertically reversed from the posture in normal use.

[ 1-2. apparatus body ]

the device main body 8 will be described with reference to fig. 2, 5, 6, and 7. Fig. 6 is a sectional view a-a of fig. 1. Fig. 7 is a cross-sectional view showing a left-side portion of fig. 6 in an enlarged manner.

The device main body 8 is a casing for supporting the power supply unit 12 and the reflection cover 14. As shown in fig. 6, the device main body 8 is formed in an annular shape having a circular opening 8a at a central portion. As shown in fig. 5 and 7, a flange 8b for supporting the reflection cover 14 is formed on the outer peripheral portion of the device body 8. The tool body 8 is formed into the above-described shape by press working a metal plate such as an aluminum plate or a steel plate.

As shown in fig. 6, a support portion 28 for attaching the device main body 8 to the device attachment member 10 described later is fixed to the peripheral edge portion of the opening portion 8a of the device main body 8. The support portion 28 extends from the peripheral edge portion of the opening 8a of the device body 8 toward the floor surface side (upper side in fig. 6). As will be described later, the instrument attachment member 10 is detachably fitted in the support portion 28.

as shown in fig. 5 and 6, an insulating case (case)30 for supporting the reflection cover 14 is fixed to one surface (a surface on the floor surface side) of the apparatus main body 8. The insulating case 30 is formed in a substantially rectangular tubular shape in cross section, and the insulating case 30 is disposed at a position surrounding the support portion 28. The insulating case 30 is formed of an insulating material such as resin.

As shown in fig. 2 and 6, a plurality of cushion (cushion) members 32 made of urethane or the like, for example, are attached to the other surface (the surface on the ceiling 4 side) of the device body 8. The plurality of cushioning members 32 are arranged at equal intervals in the circumferential direction of the device main body 8. As described later, when the lighting fixture 2 is installed on the ceiling 4, the plurality of cushioning members 32 are sandwiched between the fixture body 8 and the ceiling 4, and the rattling of the fixture body 8 is suppressed.

[ 1-3. appliance mounting Member ]

Next, the instrument attachment member 10 will be described with reference to fig. 2, 5, and 6. The appliance attachment member 10 is an adapter (adapter) for detachably attaching the appliance main body 8 to a ceiling-mounted hanger main body 34 (see fig. 5) provided on the ceiling 4.

As shown in fig. 2, 5, and 6, the instrument attachment member 10 is formed in a substantially cylindrical shape, and is detachably fitted into the support portion 28 of the instrument main body 8. The tool attachment member 10 is detachably attached to the ceiling-mounted hanger body 34.

When the lighting device 2 is installed on the ceiling 4, the user first attaches the device attachment member 10 to the ceiling-mounted hanger body 34. Thereafter, the user inserts the appliance attachment member 10 into the support portion 28 of the appliance main body 8, presses the appliance main body 8 toward the ceiling 4, and fits the support portion 28 to the appliance attachment member 10. Thus, the fixture body 8 is attached to the ceiling 4 via the fixture attachment member 10 and the ceiling-suspended body 34, and the lighting fixture 2 is installed on the ceiling 4.

The ceiling hanger body 34 is electrically connected to a commercial power supply (not shown) disposed inside the ceiling 4 via an electric wire (not shown). When the lighting fixture 2 is installed on the ceiling 4, ac power from a commercial power supply is supplied to the lighting fixture 2 via the electric wire and the ceiling hanger body 34.

[ 1-4. Power supply Unit ]

Next, the power supply unit 12 will be explained with reference to fig. 5. The power supply unit 12 is a unit for generating power for lighting the light emitting module 16. As shown in fig. 5, the power supply unit 12 includes a substrate 36 and a plurality of circuit components 38 mounted on the substrate 36.

The substrate 36 is a printed wiring substrate for mounting a plurality of circuit components 38, and is formed in a substantially L-shape. The substrate 36 is attached to one surface of the device body 8 so that the plurality of circuit components 38 face the floor surface side.

each of the plurality of circuit components 38 is a power supply circuit component constituting a power supply circuit that generates power for causing the light emitting module 16 to emit light. The plurality of circuit components 38 include, for example, a) a capacitive element such as an electrolytic capacitor or a ceramic capacitor, b) a resistive element such as a resistor, c) a rectifier circuit element, d) a coil element, e) a choke coil (choke transformer), f) a noise filter, g) a semiconductor element such as a diode or an integrated circuit element, and the like.

The plurality of circuit members 38 convert ac power supplied from the commercial power supply via the electric wire into dc power. The direct current generated at the plurality of circuit parts 38 is supplied to the light emitting module 16, so that the light emitting module 16 emits light.

the plurality of circuit components 38 may include circuit components constituting other circuits in addition to the power supply circuit components described above. For example, the plurality of circuit components 38 may include a driving circuit component constituting a dimming circuit, a boosting circuit, or the like, or may include a communication circuit component (communication module) constituting a communication circuit, or the like.

[ 1-5. reflection case ]

next, the reflection cover 14 will be described with reference to fig. 4 to 7. The reflection cover 14 is a cover for reflecting light from the light emitting module 16. The reflection cover 14 also functions as a heat sink (heat sink) for dissipating heat from the light emitting module 16.

As shown in fig. 4 to 6, the reflection cover 14 is formed in an annular shape having a substantially rectangular opening 14a at a central portion thereof. As shown in fig. 7, a flange portion 14b is formed on the outer peripheral portion of the reflection cover 14.

The reflection cover 14 is formed into the above-described shape by press working a metal plate such as an aluminum plate or a steel plate. In order to improve the light extraction efficiency by enhancing the reflectivity, a white paint is applied to one surface (surface on the floor surface side) of the reflection cover 14 or a reflective metal material is vapor-deposited.

as shown in fig. 6 and 7, the reflection cover 14 is disposed so as to cover one surface of the device body 8. Flange portion 14b of reflection cover 14 is attached to flange portion 8b of device body 8 by a plurality of screws 40. The peripheral edge of the opening 14a of the reflection cover 14 is supported by the front end of the insulating case 30.

[ 1-6. light-emitting Module ]

Next, the light emitting module 16 will be described with reference to fig. 4 to 9. Fig. 8 is a plan view of the lighting fixture 2 in which the decorative cover 20, the light guide plate 22, the reflective member 24, and the diffusion cover 26 are omitted. Fig. 9 is a plan view of the lighting fixture 2 in a state where the lens cover 18 is further omitted from fig. 8.

The light emitting module 16 is a light source for generating white light, for example. As shown in fig. 4 to 9, the light emitting module 16 includes a plurality of substrates 42, and a plurality of 1 st light emitting elements 44 and a plurality of 2 nd light emitting elements 46 (an example of a light emitting element) mounted on the plurality of substrates 42, respectively.

As shown in fig. 9, the substrate 42 is a printed wiring substrate for mounting the 1 st light emitting element 44 and the 2 nd light emitting element 46, and is formed in an arc shape. The plurality of substrates 42 are attached to one surface of the reflection cover 14 by screws 48, surrounding the opening 14a of the reflection cover 14. Thus, the plurality of substrates 42 are arranged in a ring shape along the circumferential direction of the light guide plate 22 described later.

As shown in fig. 9, a pair of connectors (connectors) 50 are mounted on both ends of the substrate 42 in the circumferential direction. The opposing connectors 50 of the adjacent pair of substrates 42 are electrically connected to each other via a lead 52. The pair of connectors 50 facing each other of the other adjacent pair of substrates 42 is electrically connected to the substrate 36 of the power supply unit 12 via a lead 54.

As the substrate 42, for example, a resin substrate, a metal-based substrate, a ceramic substrate, a glass substrate, or the like can be used. The substrate 42 is not limited to a rigid (rigid) substrate, and may be a flexible (flexible) substrate.

The 1 st light emitting elements 44 are mounted on the inner peripheral portion of the substrate 42. Specifically, the 1 st light emitting elements 44 are arranged in, for example, 3 rows in the radial direction of the substrate 42 in the inner peripheral portion of the substrate 42. In each row, the 1 st light emitting elements 44 are arranged at intervals in the circumferential direction of the substrate 42. Thus, the plurality of 1 st light emitting elements 44 are arranged in a ring shape as the whole light emitting module 16.

The plurality of 2 nd light emitting elements 46 are mounted on the outer peripheral portion of the substrate 42. Specifically, the plurality of 2 nd light emitting elements 46 are arranged in, for example, only 1 row at intervals in the circumferential direction of the substrate 42 in the outer peripheral portion of the substrate 42. Thus, the plurality of 2 nd light emitting elements 46 are arranged in a ring shape as the whole light emitting module 16.

The 1 st light Emitting element 44 and the 2 nd light Emitting element 46 are, for example, Surface Mount Device (SMD) type white led (light Emitting diode) elements that are integrated by being put in a container. That is, the 1 st light emitting element 44 and the 2 nd light emitting element 46 each have: the LED package includes a container made of white resin having a recess, an LED chip (chip) mounted on a bottom surface of the recess of the container at a time, and a sealing member sealed in the recess of the container. The LED chip is, for example, a blue LED chip that generates blue light. The sealing member contains a yellow phosphor such as YAG (yttrium aluminum garnet) that emits fluorescence using blue light from the blue LED chip as excitation light.

in this way, the 1 st light emitting element 44 and the 2 nd light emitting element 46 are B-Y type white LED elements each composed of a blue LED chip and a yellow phosphor. Specifically, the yellow phosphor contained in the sealing member absorbs a part of the blue light from the blue LED chip to be excited, thereby emitting yellow. The emitted yellow light is mixed with blue light that is not absorbed by the yellow phosphor, thereby generating white light. Thus, white light is emitted from the 1 st light emitting element 44 and the 2 nd light emitting element 46.

In the present embodiment, the 1 st light emitting element 44 and the 2 nd light emitting element 46 are both configured to generate white light, but may be configured to generate light of different colors (wavelengths) from each other. For example, the 1 st light emitting element 44 may emit white light, and the 2 nd light emitting element 46 may generate incandescent light.

[ 1-7. lens cover ]

Next, the lens cover 18 will be described with reference to fig. 3 to 8. The lens cover 18 is an optical member for enlarging the light distribution angle of light from each of the plurality of 1 st light emitting elements 44.

As shown in fig. 3 to 8, the lens cover 18 is formed in an annular shape and is made of a material having light transmittance (for example, transparent acrylic resin or the like). As shown in fig. 8, the lens cover 18 covers the inner peripheral portion of each of the plurality of substrates 42, and is attached to one surface of the reflection cover 14 by screws 56. At this time, the lens cover 18 covers the 1 st light emitting elements 44 in the plurality of substrates 42, but does not cover the 2 nd light emitting elements 46 in the plurality of substrates 42.

A plurality of lens portions 18a are formed on the lens cover 18 so as to correspond to the plurality of 1 st light emitting elements 44. The light from each of the 1 st light emitting elements 44 is transmitted through the corresponding lens portion 18 a. At this time, the plurality of lens portions 18a respectively enlarge the distribution angle of the transmitted light.

[ 1-8. decorative cover ]

Next, the trim cover 20 will be described with reference to fig. 5 to 7. The decorative cover 20 is a cover for covering the reflection cover 14 and the appliance main body 8 from the side and decorating them.

as shown in fig. 5 to 7, the trim cover 20 is formed in a ring shape. Specifically, the decorative cover 20 is arranged so as to extend in a horn shape of the musical instrument from one end portion (end portion on the floor surface side) toward the other end portion (end portion on the ceiling 4 side) and cover the reflection cover 14 and the appliance main body 8 from the side. The decorative cover 20 is made of, for example, white polystyrene resin.

As shown in fig. 6 and 7, an annular support portion 20a that extends while bending toward the inside in the radial direction of the trim cover 20 and the other end portion of the trim cover 20 is formed at one end portion of the trim cover 20. The support portion 20a supports an outer peripheral surface of a light guide portion 22b of the light guide plate 22, which will be described later.

An annular protrusion 20b extending over the entire circumference of the trim cover 20 is formed on the inner surface of the trim cover 20. The projection 20b contacts the flange 14b of the reflection cover 14. Thereby, the trim cover 20 is positioned relative to the reflection cover 14.

[ 1-9. basic constitution of light guide plate ]

Next, the basic structure of the light guide plate 22 will be described with reference to fig. 1 to 7 and 10 to 13. Fig. 10 is a view showing the light guide plate 22 taken out of fig. 1. Fig. 10 (a) is a perspective view showing the light guide plate 22, and fig. 10 (B) is a perspective view of a section B-B of fig. 10 (a). Fig. 11 is a C-C sectional view of fig. 10 (a). Fig. 12 is a cross-sectional perspective view showing the incident portion 22c of the light guide plate 22 in an enlarged manner. Fig. 13 is an enlarged view of a portion D of the light guide plate 22 of fig. 7. For convenience of explanation, hatching showing the cross section is omitted in fig. 11 and 13.

The light guide plate 22 is an optical member for illumination for guiding and emitting light from each of the plurality of 2 nd light emitting elements 46 that has entered the light guide plate in a predetermined direction (a direction toward the space 6 (fig. 7)). A surface (light emitting surface or the like) of an emission portion 22d (described later) of the light guide plate 22 is exposed to the outside as a product surface. As shown in fig. 1 to 7 and fig. 10 (a), the entire light guide plate 22 is formed in an annular shape having a substantially circular opening 22a at the center. The light guide plate 22 includes a light guide portion 22b, an incident portion 22c, an emitting portion 22d, and a plurality of branched light guide portions 22 e. The light guide plate 22 is made of a material having light transmittance (for example, a resin material such as a transparent acrylic resin).

The injection portion 22d is a disk-shaped portion, and a1 st region C1 (fig. 7 and 13) is disposed radially inward of a predetermined radial position shown by a broken line in fig. 10 (a) on the 1 st surface a1 on both sides in the thickness direction. Further, in the 1 st surface a1, a2 nd region C2 (fig. 7 and 13) is disposed radially outward of the predetermined position in the radial direction. The 1 st region C1 is disposed on a side close to the light guide portion 22b described later, and does not have a microscopic optical structure such as a microprism (prism) described later. The 2 nd region C2 is disposed on a side farther from the light guide portion 22b than the 1 st region C1, and includes a plurality of microprisms 60 (see fig. 15 (a) described later) as a microscopic optical structure. Hereinafter, the microprisms are referred to as prisms.

The prism 60 has a concave shape of a minute conical shape. A plurality of prisms 60 are arranged in the 2 nd area C2. The prisms 60 are each in the form of a recess having a diameter of, for example, 50 to 500 μm. The shape of the prism is not limited to the concave shape, and may be a convex shape. At least one flat or curved surface of the prism of the 2 nd region C2 is formed of a prism surface of a concave shape or a convex shape that transmits and reflects light. The shape of the prism is not limited to a conical shape in any of the recessed shape and the protruding shape, and may be, for example, a quadrangular pyramid shape, or a shape having an asymmetric recessed portion, such as a conical shape, a quadrangular pyramid shape, or a circular ring shape, in which a part of the inclined surface has a function of transmitting and reflecting. In addition, as the microscopic optical structure, a reflector formed by printing or the like using a screen (screen) printing of fine particles having scattering properties or ink (ink) containing a pigment and reflecting light may be disposed instead of the prism. Hereinafter, as shown in fig. 15 (a), a case where the prism 60 has a concave shape of a conical shape will be described. In the embodiment, in the 2 nd area C2, the plurality of prisms 60 may be arranged in a dispersed manner by the FM screen method. Which will be described in detail later.

as shown in fig. 6 and 7, the light guide portion 22b is formed between the incident portion 22c and the exit portion 22d, and flares from one end portion (end portion on the ceiling 4 side) toward the other end portion (end portion on the floor surface side). That is, the opening 22a is formed radially inward of the light guide portion 22b, and the 1 st light-emitting element 44 and the lens cover 18 are disposed at positions facing the opening 22 a. The light guide portion 22b guides light from one end portion toward the other end portion. The outer peripheral surface (concave surface) of light guide 22b is supported by support portion 20a of decorative cover 20. The inner peripheral surface (convex surface) of light guide 22b is covered with a later-described reflection portion 24a of reflection member 24. Thus, the light guide 22b is sandwiched between the support portion 20a of the decorative cover 20 and the reflection portion 24a of the reflection member 24.

The incident portion 22c is formed in a ring shape over the entire circumference of one end portion of the light guide portion 22b (lower end portion which is a ceiling-side end portion in fig. 6 and 7), and extends from the one end portion of the light guide portion 22b substantially parallel to a central axis 58 (fig. 10) of the opening 22a in the Z-axis direction. The incident portion 22c is disposed at a position facing and close to a substantially lower side (upper side in fig. 11) of the plurality of 2 nd light emitting elements 46.

The emission portion 22d extends annularly from the entire circumference of the other end portion (upper end portion as the floor surface side end portion in fig. 6 and 7) of the light guide portion 22b to the outside in the radial direction of the light guide plate 22. The emitting portion 22d projects outward in the radial direction of the light guide plate 22 than the one end portion of the trim cover 20, and is disposed in a substantially horizontal posture (i.e., a posture substantially parallel to the ceiling 4). The 2 nd surface a2 on the floor surface side of the both side surfaces in the thickness direction of the emitting portion 22d is a surface from which light is emitted. As shown in fig. 7, the plurality of prisms 60 described above are formed on the 1 st surface a1 on the ceiling 4 side of the two side surfaces in the thickness direction of the emitting portion 22d (see fig. 15 (a) described later).

As shown in fig. 5 to 7, the plurality of branched light guide portions 22e are branched and extended from the incident portion 22c toward the inside in the radial direction of the light guide plate 22 (i.e., in a direction different from the direction in which the light guide portions 22b extend). The plurality of branched light guide portions 22e are arranged at intervals in the circumferential direction of the incident portion 22c so as to correspond to the plurality of substrates 42. Each of the plurality of branched light guide portions 22e is attached to a predetermined region (a region between the plurality of 1 st light-emitting elements 44 and the plurality of 2 nd light-emitting elements 46) of the corresponding substrate 42 by a screw 48 (fig. 8).

As shown in fig. 11 and 12, the incident portion 22c has a prism structure 62 that converts a part of the divergent light from the 2 nd light emitting element 46 into light parallel to a predetermined direction. In a cross section (cross sections shown in fig. 11 and 12) obtained by cutting the light guide portion 22b with a virtual plane including the central axis 58 of the opening 22a, the central axis 64 of the prism structure 62 extends substantially parallel to the vertical direction (Z-axis direction).

As shown in fig. 12, the prism structure 62 is formed asymmetrically with respect to the central axis 64 in the cross section. That is, in the cross section, the curvature of the side surface 62a of the protruding portion on one side (outer peripheral side) of the central axis 64 of the prism structure 62 is different from the curvature of the side surface 62b of the protruding portion on the other side (inner peripheral side) of the central axis 64 of the prism structure 62.

As shown in fig. 11, light guide portion 22b includes inclined portion 66 and bent portion 68. As shown in fig. 11 and 12, the inclined portion 66 extends from the incident portion 22c obliquely in a direction approaching the emission portion 22d with respect to the central axis 64 of the prism structure 62. The inclination angle θ of the inclined portion 66 with respect to the central axis 64 is, for example, about 10 °.

As shown in fig. 11, the bent portion 68 extends from the inclined portion 66 to the injection portion 22d in a bent manner. A1 st reflecting surface 70, a2 nd reflecting surface 72, and a 3 rd reflecting surface 74 for reflecting and guiding light incident on the incident portion 22c toward the emitting portion 22d are formed on the inner peripheral surface of the bent portion 68 on the projecting side.

The 1 st reflecting surface 70 forms a parabola having a focal point F in the above cross section. The 1 st reflecting surface 70 is formed in a range from a boundary position between the curved portion 68 and the inclined portion 66 to a position closer to the incident portion 22c side than the focal point F.

The 2 nd reflecting surface 72 forms a curve such as a parabola or an arc in the cross section. The 2 nd reflecting surface 72 is formed in a range from a boundary position between the curved portion 68 and the emitting portion 22d to a position closer to the emitting portion 22d than the focal point F. Thus, the 2 nd reflecting surface 72 is disposed closer to the emitting portion 22d than the 1 st reflecting surface 70 in the cross section.

More specifically, the 2 nd reflecting surface 72 is disposed at a position intersecting a virtual straight line (indicated by a chain line in fig. 11) passing through the 1 st reflecting surface 70 and the focal point F in the cross section. In other words, the 2 nd reflecting surface 72 is formed in a region sandwiched by the virtual straight line 76 passing through one end of the 1 st reflecting surface 70 on the incident portion 22c side and the focal point F and the virtual straight line 78 passing through the other end of the 1 st reflecting surface 70 on the exit portion 22d side and the focal point F in the cross section.

As shown in fig. 10 (a) and (b), a rough surface 80 is formed on the projecting surface side of the 2 nd reflecting surface 72 by the concave-convex processing for forming the concave portion and the projecting portion. In this case, the rough surface 80 may be formed on the entire region of the 2 nd reflecting surface 72, or may be formed only on a part of the 2 nd reflecting surface 72. Instead of the above-described unevenness, the rough surface 80 may be formed by subjecting the 2 nd reflecting surface 72 to uneven surface roughening such as corrugation processing or sand blasting (blasting).

The 3 rd reflecting surface 74 forms a curve such as a parabola or an arc in the cross section. The 3 rd reflecting surface 74 is formed between the 1 st reflecting surface 70 and the 2 nd reflecting surface 72. The 1 st reflecting surface 70, the 2 nd reflecting surface 72, and the 3 rd reflecting surface 74 are formed as a smooth curve in the cross section.

As shown in fig. 11, a concave portion 82 is formed between light guide portion 22b and light emitting portion 22d on the outer peripheral surface side of light guide portion 22 b. Depressed portion 82 is formed in an annular shape over the entire circumference of the other end portion of light guide portion 22 b. The thickness (the size in the Z-axis direction) of the injection portion 22d in the region where the recessed portion 82 is formed is smaller than the thickness of the injection portion 22d in the region where the recessed portion 82 is not formed.

[ 1-10. reflecting Member ]

Next, the reflecting member 24 will be described with reference to fig. 4 to 7. The reflecting member 24 is a member for reflecting the light guided inside the light guide portion 22b of the light guide plate 22.

As shown in fig. 4 to 7, the reflecting member 24 is formed in a ring shape. Specifically, the reflecting member 24 includes a reflecting portion 24a and a pressing portion 24 b. The reflecting member 24 is formed of, for example, polycarbonate resin.

The reflection portion 24a flares from one end (end on the ceiling 4 side) toward the other end (end on the floor surface side). A reflection surface is formed on the concave surface side of the reflection portion 24 a. The concave side of the reflection portion 24a covers the inner peripheral surface of the light guide portion 22b of the light guide plate 22.

The pressing portion 24b extends annularly from the entire circumference of one end of the reflection portion 24a to the radially inner side of the reflection member 24. Pressing portion 24b is attached to a predetermined region of each of the plurality of substrates 42 by screws together with the plurality of branched light guide portions 22 e. As a result, as shown in fig. 6 and 7, the distal end portion of the pressing portion 24b presses the outer peripheral portion of the lens cover 18 against the plurality of substrates 42.

[ 1-11. diffusion cover ]

Next, the diffusion cover 26 will be described with reference to fig. 1 and 3 to 7. The diffusion cover 26 is a cover for diffusing light from each of the plurality of 1 st light emitting elements 44.

As shown in fig. 1 and 3 to 7, the diffusion cover 26 is detachably attached to the reflection member 24 and is disposed so as to cover the opening 22a of the light guide plate 22. As shown in fig. 3, when the diffusion cover 26 is removed from the reflection member 24, the lens cover 18 is exposed from the opening 22a of the light guide plate 22. As shown in fig. 6 and 7, the diffusion cover 26 includes a diffusion portion 26a and a mounting portion 26 b.

The diffuser 26a is formed in a disc shape and is disposed so as to cover the opening 22a of the light guide plate 22. The diffuser 26a is formed of a material having light transmittance (for example, milky acrylic resin).

The mounting portion 26b extends in a trumpet shape from the entire circumference of the outer peripheral portion of the diffuser portion 26a to the axial direction (Z-axis direction) of the diffuser portion 26 a. The mounting portion 26b is detachably mounted on the convex surface side of the reflection portion 24a of the reflection member 24.

When the lighting fixture 2 described above is used for lighting, as will be described later, the direct current from the power supply unit 12 is supplied to the light emitting module 16, and the plurality of 1 st light emitting elements 44 and the plurality of 2 nd light emitting elements 46 emit light, respectively. At this time, when the light (divergent light) from each of the plurality of 2 nd light emitting elements 46 enters the incident portion 22c of the light guide plate 22, a part of the light is converted into light parallel to the light guiding direction by the prism structure 62. The parallel light entering the incident portion 22c is reflected by the 1 st reflecting surface 70, the 2 nd reflecting surface 72, and the 3 rd reflecting surface 74 (and is reflected by the reflecting portion 24a of the reflecting member 24) in the light guide portion 22b, and is guided from the incident portion 22c to the exit portion 22 d. The light guided inside the emitting section 22d is reflected by the 1 st surface a1 of the emitting section 22d, and is emitted from the 2 nd surface a2 of the emitting section 22 d.

[ 1-12. arrangement structure of prisms in light guide plate ]

Next, the arrangement and configuration of the plurality of prisms 60 (fig. 15 a) in the 2 nd region C2 of the 1 st surface a1 of the light guide plate 22 will be described in detail with reference to fig. 13 to 21. Fig. 14 is a view showing a part in the circumferential direction when the 2 nd region C2 of the emission part 22d of the light guide plate 22 is viewed from the 2 nd surface a2 side. Fig. 15 (a) corresponds to an enlarged view of a portion F of the light guide plate 22 in the embodiment shown in fig. 7. Fig. 15 (b) corresponds to an enlarged view of the portion F of fig. 7 of the light guide plate 84 in the 1 st example of the comparative example, and fig. 15 (c) corresponds to an enlarged view of the portion F of fig. 7 of the light guide plate 85 in the 2 nd example of the comparative example.

In the embodiment, the plurality of prisms 60 are provided to reflect at least a part of the light guided inside the emitting portion 22d and to emit the light from the emitting portion 22 d. The plurality of prisms 60 can efficiently emit light from the light emitting portion 22 d. Further, the plurality of prisms 60 are dispersedly disposed in the 2 nd region C2 of the 1 st surface a1 by the FM screen method. Specifically, in the FM screen, an error diffusion method is used. The "FM screen method" is a method used when an image including continuous gradations is expressed by a medium that can only perform binary expression as in the printing field such as ink-jet printing (ink-jet printing), and is a method of expressing shading by the density of a microscopic optical structure.

the "error diffusion method" is a method of converting an input image into a binary image by comparing a value based on gradation, which is brightness information, with a threshold value for each unit region defined by a unit area such as one pixel. In addition, when converting to a binary image, an error occurring between an output value and a value based on a gradation is weighted and diffused to a predetermined nearby unit region group. In this case, the unit area of the input image corresponds to the unit area to be output one-to-one. Thus, the arrangement of the plurality of prisms 60 in the 2 nd region C2 of the 1 st surface a1 of the emitting portion 22d does not have a density gradient.

In the embodiment, the arrangement of the plurality of prisms 60 in the 2 nd region C2 is determined based on the error diffusion method described above. Specifically, as the input image, a gray scale image in which only one color is colored by a predetermined gray scale among 256 gray scales which are brightness information is used. Then, an error diffusion method is applied to a plurality of unit regions defined by a unit area of the gradation image to obtain binary outputs, and the presence or absence of the prism 60 is determined based on the values of the binary outputs. Specifically, in the binary output, a value of 0 or 1 is set for each of the plurality of unit regions, and the binary output is applied to the 2 nd region C2. In this case, when the binary output region is 0, the prism is not arranged, and when the binary output region is 1, the prism 60 is arranged. Therefore, in the 2 nd area C2, the arrangement positions of the plurality of prisms 60 are determined with moderate unevenness, and the plurality of prisms 60 are formed based on the arrangement positions. Therefore, as shown in fig. 14, when a person views the 2 nd area C2 from the 2 nd surface a2 side, the person can be prevented from feeling a pattern feeling that there is a pattern due to a difference in luminance. The reason for this will be described later using the relationship between the embodiment shown in fig. 15 (a) and comparative examples 1 and 2 shown in fig. 15 (b) and (c).

In fig. 14, the white point is based on the light reflected by the prism 60 of the 1 st surface a1 and emitted from the 2 nd surface a2, and the black portion is a portion other than this where the luminance is low. Note that, in fig. 14, black lines visible at both ends in the circumferential direction (both upper and lower ends in fig. 14) are formed for convenience of explanation, and actually, white dots are arranged in the black matrix on both sides in the circumferential direction of the portion shown in fig. 14 based on the arrangement of the plurality of prisms.

Fig. 16 is a block diagram showing a calculation method used in the error diffusion method for determining the arrangement of the prisms 60 on the 1 st surface a1 of the light guide plate 22 in the embodiment. Fig. 17 is a diagram showing a case where errors generated by comparing the gradation in the brightness of one unit region of an input image with a threshold value are dispersed in neighboring unit regions in the error diffusion method. Fig. 18 is a diagram showing diffusion coefficients used in the error diffusion method according to the embodiment.

In fig. 16, Ix and y represent gradations in a unit region of interest of an input image. Qx, y denote binary outputs in the unit region of interest. D denotes an error diffusion filter. In the error diffusion method, for Ix and y, errors dispersed from binary outputs of previously determined neighbors are added to an adder 100, and thereby, gradations Px and y to which the errors are added are obtained. Then, the added gradations are compared with a preset threshold Th in the comparator 101, and when the gradations Px and y are equal to or larger than the threshold Th, 1 is output as binary outputs Qx and y, and when the gradations Px and y are smaller than the threshold Th, 0 is output as binary outputs Qx and y. Then, the subtractor 102 calculates errors (Px, y-Qx, y) between the gradations Px, y and the binary outputs Qx, y, and outputs the errors to the error diffusion filter D. The error diffusion filter D disperses errors in a preset adjacent unit area.

In fig. 17, the attention unit region is denoted by X. Regarding the error diffusion process, when a plurality of unit regions arranged in the circumferential direction and the radial direction in the 2 nd region C2 of the 1 st plane a1 are considered, the process is performed from the right to the left (one side in the circumferential direction) in fig. 17 from one unit region (initial position) in the 1 st row at one end in the radial direction. Then, when the unit region immediately before the circumferential position of the initial position is reached, the processing is performed from the same circumferential position as the initial position in the 2 nd row in the radial direction from the right to the left in fig. 17, and the processing is repeated in the unit regions of all the rows in the radial direction.

In this case, when the unit region of interest to be processed is X, the unit regions D1 to D4 adjacent to 4 units toward the right, diagonally downward left, diagonally downward bottom, and diagonally downward right disperse errors. The dispersed errors are added to the gradations Px and y in the unit regions D1 to D4. In the embodiment, the diffusion coefficient shown in fig. 18 is used as the error diffusion filter D. Fig. 18 corresponds to fig. 17. The error diffusion filter using the diffusion coefficients shown in fig. 18 is called a Floyd & Steinberg filter. The errors calculated in the unit region of interest X are dispersed in the neighboring unit regions D1 to D4 at a ratio shown by the diffusion coefficient in fig. 18.

fig. 19 shows the frequency characteristics in the binary output calculated by such a calculation method, and in the embodiment, shows the radial (radial) average power spectrum (power spectrum) of the prism arrangement in the 2 nd region C2 of the 1 st surface a1 of the light guide plate 22. The horizontal axis of fig. 19 represents a Radial Frequency (Radial Frequency). The radial frequency is a frequency of a power spectrum having a radius r equal to an original point when the two-dimensional power spectrum is converted into a one-dimensional power spectrum indicated by polar coordinates with respect to the radius r and the angle θ. The vertical axis of fig. 19 represents the Average Power (Average Power) corresponding to the response characteristic (VTF: visual transfer Function) of the visual system represented by the formula of Dooley. The average power is the power averaged over the radius r. The higher the VTF, the more the average power increases. In order to make the pattern less perceptible when a person observes the light guide plate, it is necessary to select a frequency at which the average power deviates from the maximum peak (peak) region. Further, it is preferable that the frequency at which the change in the radial frequency does not cause a large variation in the average power, i.e., the stable low frequency. In fig. 19, it is understood that such a stable low frequency region (the region indicated by arrow α in fig. 19) can be widely secured.

Fig. 14 shows a case where the prism coverage, which is a ratio of the area occupied by the entire prisms with respect to the area of the predetermined region, is 10% in the 2 nd region C2 of the light guide plate 22.

In fig. 17, the case where the processing is performed from the row at one end in the radial direction of the 2 nd region C2 to one side in the circumferential direction and the processing is repeated until the row at the other end in the radial direction is described, but the processing according to the embodiment is not limited to this. The processing may be performed from the row at the predetermined position in the circumferential direction of the 2 nd region C2 to one side in the radial direction, and the processing may be repeated to one side in the circumferential direction until the row is one row at the predetermined position in the circumferential direction. In this case, the vertical direction is the circumferential direction and the horizontal direction is the radial direction in fig. 17.

In addition, although the case where the prism 60 is formed only on the 1 st surface a1 of the both side surfaces of the light emitting section 22d of the light guide plate 22 has been described above, a prism having a microscopic optical structure may be formed in a part of the 2 nd surface a2 together with the 1 st surface a 1. The prisms of the 2 nd surface a2 can be concave or convex. The prism of the 2 nd surface a2 can reflect or scatter light. In the above description, the case where the plurality of prisms 60 are arranged in a dispersed manner on the first surface a1 by the FM screen method has been described. On the other hand, as the plurality of minute optical structures, reflectors formed by the above-described printing may be arranged on the 1 st surface a1 in a dispersed manner by the FM screen method.

[ 1-13. illumination method ]

Next, a method of lighting the lighting fixture 2 will be described with reference to fig. 6, 7, and 11. The direct current from the power supply unit 12 is supplied to the light emitting module 16, so that the plurality of 1 st light emitting elements 44 and the plurality of 2 nd light emitting elements 46 emit light, respectively.

As shown in fig. 6 and 7, the light from each of the 1 st light emitting elements 44 passes through the corresponding lens portion 18a of the lens cover 18 and then enters the diffusion cover 26 through the opening 22a of the light guide plate 22. The light entering the diffusion cover 26 is diffused and emitted from the diffusion cover 26, and then irradiates the space 6. Thus, the light from each of the 1 st light emitting elements 44 is not incident on the light guide plate 22 but directly irradiates the space 6.

As shown in fig. 7, part of the light from each of the 1 st light emitting elements 44 is reflected by the reflecting member 24 and the like and then reflected on one surface of the reflection cover 14. The light thus multiply reflected is incident on the diffuser cover 26. This can improve the light extraction efficiency.

On the other hand, as shown in fig. 7 and 11, when light (divergent light) from each of the plurality of 2 nd light emitting elements 46 enters the entrance portion 22c of the light guide plate 22, a part of the light is converted into light parallel to the light guiding direction by the prism structure 62. The parallel light entering the incident portion 22c is reflected by the 1 st reflecting surface 70, the 2 nd reflecting surface 72, and the 3 rd reflecting surface 74 (and is reflected by the reflecting portion 24a of the reflecting member 24) in the light guide portion 22b, and is guided from the incident portion 22c to the exit portion 22 d.

As shown in fig. 11, light guided inside the light guide unit 22b first enters the concave side of the 1 st reflecting surface 70 at an angle of incidence larger than the critical angle, and is totally reflected by the 1 st reflecting surface 70. In this case, the 1 st reflecting surface 70 is preferably disposed in a region where most of the parallel light incident on the incident portion 22c can be totally reflected. The light totally reflected by the 1 st reflecting surface 70 travels inside the light guide unit 22b while converging toward the focal point F, and diverges at the focal point F and then enters the 2 nd reflecting surface 72.

The light from the 1 st reflecting surface 70 is incident toward the concave side of the 2 nd reflecting surface 72 at an incident angle larger than the critical angle, and is totally reflected at the 2 nd reflecting surface 72. The light totally reflected by the 2 nd reflecting surface 72 is guided inside the exit section 22d, reflected by the prism portion formed on the 1 st surface a1 of the exit section 22d, and exits from the 2 nd surface a2 of the exit section 22 d.

part of the light guided inside light guide unit 22b is reflected on the concave surface side of 3 rd reflecting surface 74, and then guided inside light emitting unit 22 d.

Further, a part of the light (return light) reflected by the prism portion of the 2 nd surface a 2a plurality of times tends to travel in a direction to return to the light guide portion 22 b. On the other hand, as shown in fig. 11, the return light is reflected by a concave portion 82 formed in the light guide plate 22, and is guided again into the emitting portion 22d without returning to the light guide portion 22 b.

As shown in fig. 11, a part of the light incident on the incident portion 22c of the light guide plate 22, which is not converted into parallel light by the prism structure 62, is incident on the branched light guide portion 22 e. At this time, for example, by forming the pressing portion 24b of the reflecting member 24 shown in fig. 7 with a transparent resin or the like, the light enters the light transmitting pressing portion 24b of the branched light guide portion 22e and enters the diffusion cover 26. Alternatively, the light incident on the branched light guide parts 22e can be made incident on the diffusion cover 26 by omitting the pressing parts 24b of the reflecting member 24. In addition, when the 2 nd reflecting surface 72 is subjected to a roughening treatment such as a corrugation process, for example, a part of the guided light can be made incident on the diffusion cover 26, and the diffusion cover 26 can uniformly emit light when emitting light, and in addition, the emission portion 22d also has an effect of uniformly emitting light, so that the quality of the appearance as illumination can be improved.

As described above, the space 6 can be illuminated with the light from the diffusion cover 26, and the space 6 can be illuminated with the light guided from the light emitting portion 22d of the light guide plate 22. Accordingly, the space 6 directly below the lighting device 2 is illuminated directly with light from the diffuser cover 26 in a relatively bright manner, and thus, for example, a desired illuminance can be ensured for reading or performing a manual operation. On the other hand, the space 6 around the lighting fixture 2 can illuminate the ceiling surface and the area above the wall surface, which are difficult to illuminate in a normal fixture, by the light from the emitting portion 22d of the light guide plate 22, and thus the entire room can be illuminated.

[2. Effect ]

The lighting fixture 2 of the present embodiment includes a2 nd light emitting element 46 as a light source, and a light guide plate 22 for illumination that guides light from the 2 nd light emitting element 46 in a predetermined direction and emits the light. The light guide plate 22 has prisms 60 or reflectors as a plurality of microscopic optical structures on at least the 1 st surface a1 of both side surfaces in the thickness direction, and the plurality of prisms 60 or reflectors are dispersedly arranged in a partial region of the 1 st surface a1 by the FM screen method.

This makes it possible to make the pattern based on the luminance difference less noticeable when a person observes the light guide plate 22. More specifically, when a person views the 1 st surface a1 of the light guide plate 22 from the 2 nd surface a2 side opposite to the 1 st surface a1, it is possible to simultaneously realize a pattern that is less likely to be perceived by a difference in luminance and maintain high light distribution controllability. The reason for this will be described using the relationship between the embodiment shown in fig. 15 (a) and comparative examples 1 and 2 shown in fig. 15 (b) and (c).

In the 1 st example of the comparative example shown in fig. 15 (b), prisms 60 are formed at equal intervals on the 1 st surface a1 in the thickness direction in the emission portion 84d of the light guide plate 84. Light entering the light emitting portion 84d from the light guide portion disposed on the left side of fig. 15 (b) is reflected by the prism 60 and emitted from the 2 nd surface a2 in the thickness direction. At this time, the light beam once reflected by the flat portions around the prism 60 of the 1 st surface a1 is reflected again by the prism 60, and is emitted from the 2 nd surface a2 as the emitted light parallel to the thickness direction of the emitting portion 84d (the vertical direction of fig. 15 (b)). The right-below illuminance can be improved by directing the 2 nd surface a2 to the floor surface.

On the other hand, as shown in the relationship between the light beam L1 and the prism 60 at the left end in fig. 15 (b), for example, the light directly entering the prism 60 from the light guide portion does not satisfy the total reflection condition, and is refracted and emitted in the direction of a 1. At this time, if the density of the prisms 60 in the 1 st plane a1 is locally or entirely increased, the prism interval becomes smaller. Accordingly, as in the light beam L2 of the comparative example shown in fig. 15 (c) described later, the light beam is not incident from the light guide portion to the portion other than the prism 60 of the 1 st surface a1, but is directly incident on the prism 60, is emitted from the 1 st surface a1 instead of the 2 nd surface a2, and cannot be used as a light beam for obtaining the right-below illuminance. Therefore, in the 1 st plane a1, since the flat portion effective for the control of the light distribution is reduced, it becomes difficult to maintain the high light distribution controllability. On the other hand, as shown in fig. 15 (b), even when the plurality of prisms 60 are uniformly arranged, the prism interval is increased as a whole, and the direct downward illuminance is ensured, and when a person observes the 1 st surface a1 from the 2 nd surface a2 side, the person easily feels that there is a pattern based on the luminance difference having regularity.

In the second example 2 of the comparative example shown in fig. 15 (c), a prism group 86 composed of a plurality of prisms 60 densely packed in a cluster is formed at a plurality of positions at equal intervals on the 1 st surface a1 in the thickness direction in the emission part 85d of the light guide plate 85. The light entering the light emitting portion 85d from the light guide portion is reflected by the prism 60 and emitted from the 2 nd surface a2 in the thickness direction. At this time, as the density of the prisms 60 in the 1 st surface a1 becomes higher, and the interval of the prism group 86 becomes smaller uniformly, the light is not incident from the light guide portion to the portion other than the prisms 60 of the 1 st surface a1 but directly incident on the prisms 60 as in the light beam L2 shown in fig. 15 (c), and the light emitted from the 1 st surface a1 is increased, not the 2 nd surface a 2. Therefore, when the lighting apparatus is configured using the light guide plate 85, it becomes difficult to obtain direct downward illuminance as compared with the case where the prisms are arranged at equal intervals. Therefore, in the case of fig. 15 (b) and 15 (c), the direct-under illuminance and the pattern feeling due to the luminance difference are all in a relationship of improving only one of them, and the performance and quality as a lighting fixture cannot be satisfied. On the other hand, in the embodiment, as described above, the plurality of prisms 60 are arranged in a dispersed manner by the FM screen method. This eliminates large density variations among the plurality of prisms 60, and reduces the number of prisms arranged uniformly. Therefore, it is possible to achieve both a pattern based on a difference in brightness that is less likely to be perceived by a person when viewing the light guide plate 22 and maintaining high light distribution controllability.

Fig. 20 (a) is a view showing the light guide plates 84 and 85 as viewed from the outside of the 2 nd surface a2 in the 1 st example of the pattern based on the luminance difference generated in the light guide plates 84 and 85 in the 1 st or 2 nd example of the comparative example, and fig. 20 (b) is an enlarged view of the G portion of fig. 20 (a). Fig. 21 (a) is a perspective view showing a2 nd surface a2 of the light guide plates 84 and 85 of a2 nd example of a pattern based on a luminance difference generated in the light guide plates 84 and 85 in the 1 st or 2 nd example of the comparative example, and fig. 21 (b) is an enlarged view of a portion H of fig. 20 (a). In fig. 20 and 21, the light guide plate 84 or the light guide plate 85 is simply illustrated as an annular shape for ease of understanding.

First, the light guide plate 84 of example 1 of the comparative example will be described below. As shown in (a) and (b) of fig. 20, when the light guide plate 84 is viewed from the 2 nd surface a2 side, a pattern in which linear luminance differences are present in a plurality of circular arc shapes at a plurality of positions in the circumferential direction may be easily observed. At this time, the plurality of circular arc-shaped lines 87 as the pattern on the 2 nd surface a2 are easily formed at positions equally spaced in the circumferential direction and equally spaced in the radial direction.

As shown in fig. 21 (a) and (b), when the 2 nd surface a2 of the light guide plate 84 is viewed from an oblique direction, a pattern in which a plurality of circles 88 are arranged in a radial direction may be easily observed. In this case, due to a processing error of the prism shape at the time of forming the light guide plate 84, a pattern based on a luminance difference due to processing unevenness is also easily observed. As shown in fig. 20 and 21, the reason why the pattern is present is also that the plurality of prisms 60 are arranged at equal intervals on the 1 st surface a1 of the light guide plate 84 as described with reference to fig. 15 (b).

In the case of the light guide plate 85 according to comparative example 2, the prism groups are arranged at equal intervals on the 1 st surface a1 of the light guide plate 85, and thus the pattern may be easily observed as shown in fig. 20 and 21.

On the other hand, as in the light guide plate 22 of the embodiment shown in fig. 15 (a), when the plurality of prisms 60 are dispersedly arranged in the 2 nd area C2 of the 1 st surface a1 by the FM screen method, the light reflected by the prisms 60 in the 2 nd area C2 is less uniformly emitted from the 2 nd surface a 2. Thus, when a person views the 1 st surface a1 of the light guide plate 22 from the 2 nd surface a2 opposite to the 1 st surface a1, the person can hardly feel a pattern based on a difference in luminance as shown in fig. 14.

Further, the light guide plate 22 included in the lighting apparatus 2 of the embodiment includes the light guide portion 22b formed between the incident portion 22c and the emission portion 22 d. The light guide portion 22b extends from the incident portion 22c to the exit portion 22d while being curved, and has a1 st reflection surface 70 and a2 nd reflection surface 72 on the inner peripheral surface for guiding the light incident on the incident portion 22c to be reflected toward the exit portion 22 d. The 1 st reflecting surface 70 forms a parabola having a focal point F in a cross section when the light guide portion 22b is cut off from a virtual plane. The 2 nd reflecting surface 72 is disposed closer to the emitting portion 22d than the 1 st reflecting surface 70 in the cross section described above, and is disposed at a position intersecting with a virtual straight line passing through the 1 st reflecting surface 70 and the focal point F. The emitting portion 22d has the 1 st surface a1 on which the plurality of prisms 60 are arranged.

Accordingly, the 1 st reflecting surface 70 forms a parabola having the focal point F in the cross section, and therefore, of the light guided inside the light guide unit 22b, the light reflected by the 1 st reflecting surface 70 travels inside the light guide unit 22b while converging toward the focal point F, and diverges after converging at the focal point F and enters the 2 nd reflecting surface 72. The light reflected by the 2 nd reflecting surface 72 is guided inside the emitting portion 22d and emitted from the emitting portion 22d toward the space 6. Accordingly, since the light reflected by the 1 st reflecting surface 70 can be efficiently incident on the 2 nd reflecting surface 72, the occurrence of propagation loss of light in the light guide portion 22b can be suppressed, and the utilization efficiency of light from the 2 nd light emitting element 46 can be improved.

The 1 st surface a1 includes a1 st region C1 which is disposed on a side close to the light guide portion 22b and does not have a microscopic optical structure, and a2 nd region C2 which is disposed on a side farther from the light guide portion 22b than the 1 st region C1 and in which the plurality of prisms 60 are disposed.

Accordingly, since the plurality of prisms 60 are disposed in the portion of the 1 st surface a1 that needs to reflect light at a plurality of positions, that is, in the portion on the side away from the light guide portion 22b, light can be efficiently emitted from the 2 nd surface a2 of the emitting portion 22 d. Further, since the microscopic optical structure is not disposed on the side of the 1 st surface a1 closer to the light guide portion 22b than the 2 nd region C2, cost reduction can be achieved. At the same time, since it is not necessary to reflect light at a plurality of positions in the 1 st region C1, it is not necessary to form a complicated curved surface in order to diffuse light from the light guide portion 22b in a plurality of directions in the light emitting portion 22 d.

Further, the light guide plate 22 is formed in an annular shape. The light guide portion 22b flares from the incident portion 22c toward the emitting portion 22 d. The incident portion 22c extends from one end of the light guide portion 22b substantially parallel to the central axis 58 of the light guide plate. The light emitting portion 22d extends from the other end portion of the light guide portion 22b to the outside in the radial direction of the light guide portion 22 b. The virtual plane is a plane including the central axis 58 of the light guide plate.

Accordingly, by forming the light guide plate 22 into an annular shape, the lighting fixture 2 can be used as, for example, a circular ceiling lamp or the like.

(other example of embodiment)

fig. 22 is a diagram showing diffusion coefficients used in the error diffusion method in example 1 of another example of the embodiment. Fig. 23 is a view showing a radial average power spectrum of the prism arrangement of the 1 st surface a1 of the light guide plate 22 in example 1 of the other example of the embodiment.

In the case of this example, the diffusion coefficient shown in fig. 22 is used instead of the diffusion coefficient shown in fig. 18. Therefore, compared to the case shown in fig. 17, the error calculated by comparing the threshold Th (see fig. 16) with the target unit region X is distributed to the neighboring many unit regions. The error diffusion filter using the diffusion coefficient shown in fig. 22 is called a Jarvis, judiate & Ninkel filter. The error calculated in the unit region of interest X is dispersed to the neighboring unit regions at a ratio shown by the diffusion coefficient in fig. 22.

fig. 23 is a diagram corresponding to fig. 19, showing frequency characteristics in the binary output calculated by the calculation method using the diffusion coefficient shown in fig. 22. From the frequency characteristics of fig. 23, the arrangement of the prisms 60 or the reflectors in the 2 nd region C2 of the 1 st surface a1 of the light guide plate 22 is determined by selecting a high radial frequency at which the average power deviates from the maximum peak region. On the other hand, as is clear from comparing fig. 23 and fig. 19, in the case of the frequency characteristic of fig. 23, the average power greatly fluctuates due to the change in the radial frequency at a high frequency at which the average power deviates from the maximum peak region.

Fig. 24 is a view corresponding to fig. 14 in example 1 of another embodiment. As shown in fig. 24, also in the case of this example, similarly to the configurations of fig. 1 to 14, 15 (a), and 16 to 19, when a person views the 1 st surface a1 of the light guide plate 22 from the 2 nd surface a2 side opposite to the 1 st surface a1, it is possible to simultaneously realize a pattern that is less likely to be perceived by a luminance difference and maintain high light distribution controllability. In the case of fig. 24, similarly to the case of fig. 14, the case where the prism coverage is 10% in the 2 nd region C2 of the light guide plate 22 is also shown. In this example, the other configurations and operations are the same as those of fig. 1 to 14, (a) of fig. 15, and (16) to 19.

In the above description, the error diffusion method is used as the FM screen method in order to determine the arrangement of the prisms 60 or the reflectors in the 2 nd region C2, but the ordered Dither (Dither) method or the blue noise mask (blue noise mask) method may be used as the FM screen method.

Both the ordered dither method and the blue noise mask method are called mask methods, and are methods for binarizing an input image by comparing the input image with a predetermined threshold value of a matrix set in advance. For example, a value represented by a number called "Dither Matrix (Dither Matrix)" is compared with the gradation of a predetermined area of an input image, and the presence or absence of a prism or a reflector is determined based on the magnitude relationship. In this case, as in the case of the error diffusion method, a grayscale image colored with a predetermined grayscale by only one color is used for the input image. A binary output is obtained by applying a sequential dither method or a blue noise mask method to a plurality of unit regions defined by a unit area of a gradation image, and the presence or absence of a prism is determined based on the binary output.

In the "ordered dither method", 8 × 8 small matrices (dither matrices) in which integers of 1 to 64 are dispersed one by one are used. The arrangement of the prisms is determined by using the structure in which the small matrix is repeatedly arranged corresponding to the 2 nd region C2 of the light guide plate 22.

On the other hand, in the "blue noise mask method", a large matrix of 256 × 256 is used. The arrangement of the prisms is determined by using the structure in which the large matrix is repeatedly arranged corresponding to the 2 nd region C2 of the light guide plate 22.

As described above, even when the prism arrangement is determined by using either the order dither method or the blue noise mask method, a plurality of prisms or reflectors are dispersedly arranged in the 2 nd region C2. In this configuration, similarly to the case of using the error diffusion method described above, when a person views the 1 st surface a1 of the light guide plate 22 from the 2 nd surface a2 side, it is possible to simultaneously realize a pattern that is less likely to be perceived by a difference in brightness and maintain high light distribution controllability.

In the above examples, the case where the prism 60 or the reflector is disposed only in the 2 nd region C2 of the 1 st surface a1 of the emitting portion 22d of the light guide plate 22 has been described, but the prism or the reflector may be disposed as a whole including the end of the 1 st surface a1 on the light guide portion 22b side of the emitting portion 22 d.

Fig. 25 is a perspective view showing an appearance of a floor surface side in a lighting fixture 90 according to example 2 of another embodiment. The lighting apparatus 90 of this example includes a mounting substrate 92 on which a plurality of light emitting elements 91 serving as light sources are mounted, and a light guide plate 93. The light guide plate 93 is annular and has an inner peripheral surface that is an incident surface on which light from the light emitting element 91 is incident. The mounting substrate 92 is fixed to an instrument body (not shown) that supports the light guide plate 93. The plurality of light emitting elements 91 are arranged on the mounting substrate 92 at equally spaced positions in the circumferential direction of the inner circumferential surface of the light guide plate 93 so as to face each other in the radial direction.

The light guide plate 93 includes a ceiling-side 1 st surface a1 and a floor-side 2 nd surface a2 of both thickness-direction side surfaces. The 1 st surface a1 has a1 st region E1 and a2 nd region E2. The 1 st region E1 is a region of the 1 st surface a1 of the light guide plate 93 near the light emitting element 91, is arranged closer to the inner periphery of the light guide plate 93 than the broken line J in fig. 25, and does not have a microscopic optical structure. The 2 nd region E2 is located on the side farther from the light-emitting element 91 than the 1 st region E1, is located on the outer peripheral side of the light guide plate 93 than the broken line J in fig. 25, and has a plurality of microscopic optical structures. Each of the plurality of minute optical structures is a concave prism or a reflector of reflected light formed by printing. In the case where the microscopic optical structure is a reflector, the plurality of reflectors are formed by screen printing, ink jet printing, or gravure printing, respectively. The inkjet printing may be UV (ultraviolet) inkjet printing.

Further, the arrangement of the plurality of minute optical structures in the 2 nd region E2 has no density gradient.

in the case of the above-described configuration, as in the configurations of fig. 1 to 14, (a) of fig. 15, and (16) to 19, the plurality of microscopic optical structures are dispersedly arranged in the 2 nd region E2 by the FM screen method. In this case, the FM screen method is one of an error diffusion method, an order dither method, and a blue noise mask method.

With the configuration of this example, it is possible to achieve both a low possibility of feeling a pattern due to a difference in luminance and a high light distribution controllability when a person views the 1 st surface a1 of the light guide plate 93 from the 2 nd surface a2 side. In this example, the other configurations and operations are the same as those of fig. 1 to 14, (a) of fig. 15, and (16) to 19. In this example, the plurality of microscopic optical structures may be arranged on the entire 1 st surface a1 including the inner peripheral end of the light guide plate 93.

In the above-described embodiments, the lighting fixtures 2 and 90 are ceiling lamps, but the invention is not limited thereto, and for example, a chandelier, a ceiling lamp as a small lighting fixture attached from a ceiling, a wall lamp as a lighting fixture attached to a wall surface, a bathroom lamp as a lighting fixture installed in a bathroom, or a hall lamp as a lighting fixture installed in a restaurant may be used.

In the above-described configurations of fig. 1 to 14, 15 (a), and 16 to 19, the prism structure is a prism structure 62 that converts divergent light from the 2 nd light emitting element 46 into parallel light, but the present invention is not limited thereto, and for example, a condenser lens structure that converts divergent light from the 2 nd light emitting element 46 into convergent light may be used.

In the above embodiments, the light guide plates 22 and 93 are formed in an annular shape, but the present invention is not limited thereto, and may be formed in a rectangular shape, for example.

In the above-described configurations of fig. 1 to 14, 15 (a), and 16 to 19, the 2 nd reflecting surface 72 forms a curved line in the cross section, but the present invention is not limited thereto, and the 2 nd reflecting surface 72 may form a straight line in the cross section.

In the above embodiments, the mounting structures of the 1 st light-emitting element 44, the 2 nd light-emitting element 46, and the light-emitting element 91 are SMD structures, but the SMD structures are not limited thereto, and may be cob (chip On board) structures in which LED chips (chips) are directly mounted On the substrate 42, for example. In this case, the plurality of LED chips mounted on the substrate may be collectively sealed by the sealing member, or may be individually sealed. The sealing member may contain a wavelength conversion member such as the yellow phosphor.

In the above embodiments, the 1 st light-emitting element 44, the 2 nd light-emitting element 46, and the light-emitting element 91 are exemplified by LEDs, but the present invention is not limited thereto, and for example, semiconductor light-emitting elements such as semiconductor lasers, and other solid-state light-emitting elements such as organic EL (electro luminescence) or inorganic EL may be used.

In addition, the present invention includes a form realized by arbitrarily combining the components and functions in the respective embodiments without departing from the scope of the present invention.

Claims (11)

1. A lighting fixture is characterized by comprising:

A light source; and

A light guide plate for illumination, which guides and emits light from the light source,

The light guide plate has a plurality of minute optical structures on at least the 1 st surface of both side surfaces in the thickness direction,

The plurality of minute optical structures are dispersedly arranged on at least a partial region of the 1 st surface based on an FM screen method.

2. The lighting fixture of claim 1,

The FM screen method is an ordered dither method, an error diffusion method, or a blue noise mask method.

3. the lighting fixture of claim 1 or 2,

A mounting substrate on which a light emitting element as the light source is mounted,

The light guide plate has:

An incident portion on which light from the light emitting element is incident;

An exit portion from which light incident on the entrance portion is supplied;

A light guide portion formed between the incident portion and the emission portion, extending from the incident portion to the emission portion while being curved, and having a1 st reflection surface and a2 nd reflection surface on an inner peripheral surface thereof for guiding light incident on the incident portion toward the emission portion while reflecting the light,

The 1 st reflecting surface forms a parabola having a focal point on a cross section when the light guide part is cut by a virtual plane,

The 2 nd reflecting surface is disposed on a side closer to the emission portion than the 1 st reflecting surface in the cross section and at a position intersecting with a virtual straight line passing through the 1 st reflecting surface and the focal point,

The emission portion has the 1 st surface on which the plurality of microscopic optical structures are arranged.

4. The lighting fixture of claim 3,

The 1 st aspect includes: a1 st region which is arranged on a side close to the light guide portion and does not have a microscopic optical structure; and a2 nd region arranged on a side of the light guide portion farther from the light guide portion than the 1 st region, the plurality of microscopic optical structures being arranged.

5. The lighting fixture of claim 4,

The arrangement of the plurality of minute optical structures in the 2 nd region has no density gradient.

6. the lighting fixture of claim 1,

The plurality of minute optical structures are each a concave prism or a reflector of reflected light formed by printing.

7. The lighting fixture of claim 6,

The plurality of minute optical structures are each a prism having a concave shape with a diameter of 50 to 500 [ mu ] m.

8. The lighting fixture of claim 1 or 2,

A mounting substrate on which a light emitting element as the light source is mounted,

The light guide plate is annular and has an incident surface on which light from the light emitting element is incident.

9. The lighting fixture of claim 8,

The 1 st aspect includes: a1 st region which is arranged on a side close to the light emitting element and does not have a microscopic optical structure; and a2 nd region which is disposed on a side farther from the light-emitting element than the 1 st region and in which the plurality of microscopic optical structures are disposed.

10. The lighting fixture of claim 9,

The arrangement of the plurality of minute optical structures in the 2 nd region has no density gradient.

11. The lighting fixture of claim 8,

The plurality of minute optical structures are formed by screen printing, inkjet printing, or gravure printing, respectively.