Artificial Skylight Device

Abstract

A lighting device (1) is provided. The lighting device (1) includes a cavity (10). The cavity (10) extends along a longitudinal axis (L) of the lighting device (1). The cavity (10) is further defined by an inner surface (11) configured to reflect light impinging on the inner surface (11) of the cavity (10). The cavity (10) has an opening (12) that allows light within the cavity (10) to exit the cavity (10). The lighting device (1) further includes an optical module (20). The optical module (20) is disposed within or at the opening (12) of the cavity (10) and is configured to transmit light impinging on a surface (21) of the optical module (20) through the optical module (20). The light transmitted through the optical module (20) is emitted from the lighting device (1). The lighting device (1) further includes a plurality of light-emitting elements (31). The light-emitting elements (31) are arranged consecutively along the longitudinal axis (L) of the lighting device (1), are disposed within the cavity (10), and are configured to emit a first light (41). The first light (41) strikes the surface (21) of the optical module (20) without first striking the inner surface (11) of the cavity (10). The light-emitting elements (31) are further configured to emit a second light (42). The second light (42) strikes the inner surface (11) of the cavity (10). The optical module (20) is configured to collimate the first light (41) in a transverse plane perpendicular to the longitudinal axis (L) of the lighting device (1). Furthermore, the optical module (20) is configured to generate collimated light so as to increase the degree of collimation of the light in a cross section transmitted from the optical module (20) compared to the first light (41) before transmitting through the optical module (20). At least one of the inner surface (11) of the cavity (10), the plurality of light-emitting elements (31), and the optical module (20) is configured so that the second light (42) reflected by the inner surface (11) of the cavity (10), then impinging on the surface (21) of the optical module (20) and transmitted from the optical module (20) is light having a wavelength in the range of 400 to 470 nm, at least 3% of the total luminous flux.

Description

[Technical Field]

[0001] The present invention relates to a lighting device for obtaining an artificial skylight / daylight or natural window appearance. [Background technology]

[0002] Receiving daylight is of interest to people because it is important for their health and well-being. However, people tend to spend most of the day indoors, which can remove people from natural daylight. Therefore, there is interest in creating artificial light that can simulate the appearance and light of natural windows or skylights. To more closely emulate daylight and skylights, it is necessary to emulate sunlight. This has primarily been done by providing artificial daylight or skylights that emit blue light (i.e., clear sky) when viewed from an angle, while providing a predominantly white light beam that is directed substantially perpendicular to the daylight or skylight's exit window. An example of a lighting system that simulates natural lighting is shown in US2014133125. The lighting system shown includes a bright light hidden in the space above a drop ceiling, which emits a directional light beam that shines through an exit window containing scattering nanoparticles. The disadvantage of such a system is that the light source must be much smaller than the exit window to create a sharply defined beam of artificial sunlight, but at the same time, the light source must produce a very high flux to create a convincing sunlight beam effect. Thus, a very compact and extremely bright light source is required, which is very costly. Summary of the Invention [Problem to be solved by the invention]

[0003] In view of the above, it is a concern of the present invention to provide a lighting device that can provide a convincing sunlight beam effect without using a very compact and extremely bright light source. Furthermore, it is a concern of the present invention to provide a lighting device that can imitate a skylight or natural window while providing a compact installation and / or may involve a reduced need for a false ceiling / wall. [Means for solving the problem]

[0004] In order to address at least one of these and other concerns, a lighting device according to the independent claims is provided. Preferred embodiments are defined by the dependent claims.

[0005] According to a first aspect of the present invention, there is provided a lighting device. The lighting device has a length, a width, and a longitudinal axis. The longitudinal axis is an axis oriented along the length of the lighting device. The aspect ratio of the length to the width (i.e., the length divided by the width) is at least 2, such as at least 5, or at least 10, or at least 50, or at least 100. Because of the aspect ratio, the lighting device is sometimes referred to as a "linear" lighting device.

[0006] The lighting device may include a cavity. The cavity may extend along a longitudinal axis of the lighting device. The cavity may be defined by an inner surface configured to reflect light impinging on the inner surface of the cavity and may have an opening that allows light within the cavity to exit the cavity. The lighting device may also include an optical module. The optical module may be disposed within or at the opening of the cavity. The optical module may be configured to transmit light impinging on a surface of the optical module through the optical module. The light transmitted through the optical module may be emitted from the lighting device. The lighting device may include a plurality of light emitting elements disposed in succession along the longitudinal axis of the lighting device and within the cavity. The plurality of light emitting elements may be configured to emit a first light that impinges on a surface of the optical module without first impinging on the inner surface of the cavity, and a second light that impinges on the inner surface of the cavity. The optical module may be configured to collimate the first light in a transverse cross-section, the transverse cross-section being perpendicular to the longitudinal axis of the lighting device. The optical module may be configured to generate collimated light in a cross-section such that the degree of collimation of the light transmitted from the optical module is increased compared to the first light prior to transmission through the optical module. At least one of the inner surface of the cavity, the plurality of light emitting elements, and the optical module may be configured such that the second light reflected by the inner surface of the cavity, then striking a surface of the optical module, and transmitted from the optical module has at least 3% of its total luminous flux within a wavelength range of 400-470 nm.

[0007] The lighting device may include a luminaire. The term "luminaire" refers to, for example, a fixture, a light-fitting, or a light armature. The luminaire may include an interior surface. The opening of the cavity may extend along the longitudinal axis of the lighting device. An optical module may be disposed within or at the opening of the cavity such that light within the cavity must be transmitted by the optical module to exit the cavity. The term "light emitting elements" refers to a light emitting diode (LED), a plurality of LEDs, and / or a plurality of LEDs arranged in a linear array. Furthermore, the term "light emitting element" refers to dense packing of LEDs. The dense packing of LEDs may be along the longitudinal axis of the lighting device. Each or any of the LEDs may include inorganic LED(s) and / or organic LED(s) (OLED(s)). Although the light-emitting elements are referred to herein as including LEDs, it should be understood that each or any of the light-emitting elements may include another or other type of light source, such as another or other type of solid-state light emitter, instead of or in addition to an LED. The light-emitting elements may be disposed along substantially the entire longitudinal length of the cavity of the lighting device. The terms "collimated light" and "collimation," in the context of this application, mean making some of the light beams parallel to each other and / or reducing the mutual angle between some of the light beams. Increasing the degree of collimation may also mean narrowing the beam of light.Warm white light has about 1% of light within the wavelength range of 400-470 nm (or lower), while cool white light has about 2-3% of blue light within the wavelength range of 400-470 nm (about 3% at a correlated color temperature of 6500 K, which can be considered "daylight"). Light with at least 3% of its total luminous flux within the wavelength range of 400-470 nm can represent sky color (bluish white to blue tints). Thus, light with at least 3% of its total luminous flux within the wavelength range of 400-470 nm can appear blue to a viewer viewing the lighting device from a distance. The term "white light" refers to light that is a mixture of substantially all wavelengths in the visible spectrum.

[0008] At least one of the plurality of light-emitting elements may be arranged such that the second light emitted by the plurality of light-emitting elements has at least 3% of its total luminous flux within the wavelength range of 400 to 470 nm. Light having at least 3% of its total luminous flux within the wavelength range of 400 to 470 nm may be described as white light having a correlated color temperature (CCT) of about 10,000 K to 20,000 K (about 3.8% to about 4.6% blue flux), and may represent a blue sky or clouds.

[0009] This may increase the similarity between the light emitted by the lighting device and the light of a natural window or skylight.At least one of the plurality of light-emitting elements may be configured to emit light having at least 3% of its total luminous flux in the wavelength range of 400-470 nm.The plurality of light-emitting elements not configured to emit light having at least 3% of its total luminous flux in the wavelength range of 400-470 nm may be configured to emit light having less than 3% of its total luminous flux in the wavelength range of 400-470 nm, or white light.

[0010] The plurality of light-emitting elements may be configured such that at least one of the plurality of light-emitting elements is arranged such that the second light emitted by the plurality of light-emitting elements has at least 3% of its total luminous flux within the wavelength range of 400 to 470 nm, and the second light that is reflected by the inner surface of the cavity, then strikes the surface of the optical module and is transmitted through the optical module has at least 3% of its total luminous flux within the wavelength range of 400 to 470 nm.

[0011] At least one of the plurality of light emitting elements may be arranged such that the first light emitted by the plurality of light emitting elements is light with less than 3% of its total luminous flux in the wavelength range 400-470 nm, or white light. Light with less than 3% of its total luminous flux in the wavelength range 400-470 nm may represent direct sunlight with a CCT of about 3000-5500 K, i.e., about 1-2.5% blue light.

[0012] This may increase the similarity between the light emitted by the lighting device and the light of natural window or skylight and beams of sunlight.At least one of the plurality of light-emitting elements may be configured to emit light having less than 3% of its total luminous flux in the wavelength range 400-470 nm, or white light.A plurality of light-emitting elements not configured to emit light having less than 3% of its total luminous flux in the wavelength range 400-470 nm, or white light, may be configured to emit light having at least 3% of its total luminous flux in the wavelength range 400-470 nm.

[0013] The inner surface of the cavity may have a reflectance of 80% or more for light in the wavelength range of 400 to 470 nm, and a reflectance of less than 80% for light at other wavelengths.

[0014] This may increase the similarity of the lighting device to natural light or skylight.The inner surface may be configured to absorb substantially all light outside the wavelength range of 400-470 nm.

[0015] The inner surface of the cavity may be configured to have a reflectivity of 80% or more for light in the wavelength range of 400 to 470 nm and a reflectivity of less than 80% for light at other wavelengths, so that the second light reflected by the inner surface of the cavity, then impinging on the surface of the optical module and transmitted through the optical module has at least 3% of its total luminous flux in the wavelength range of 400 to 470 nm, thereby allowing less than 3% of "blue" light to have 3% or more blue light after reflecting off the inner surface of the cavity.

[0016] However, the concept of the present invention is not limited to the above-mentioned reflectance, and the inner surface of the cavity may have, for example, a reflectance of 70% or more for light in the wavelength range of 400 to 470 nm, and a reflectance of less than 70% for light at other wavelengths.

[0017] The interior surface of the cavity may, for example, comprise paint. The paint may be configured to scatter and / or reflect light within the wavelength range of 400-470 nm and absorb light outside the wavelength range of 400-470 nm. The interior surface of the cavity may comprise scattering nanoparticles. The interior surface of the cavity may be configured for Rayleigh scattering. The scattering nanoparticles may be configured for Rayleigh scattering. The nanoparticles may be configured to scatter and / or reflect light within the wavelength range of 400-470 nm and absorb light outside the wavelength range of 400-470 nm.

[0018] The optical module may include a linear collimator configured to collimate at least the first light in a cross-section, and the linear collimator may be configured to generate collimated light to increase the degree of collimation of the light in the cross-section transmitted from the optical module compared to the first light before transmitting through the optical module.

[0019] This can increase the similarity of the appearance of the first light to that of a sunlight beam. The linear collimator may be configured to collimate only the first light. The linear collimator may be configured to generate collimated light such that the degree of collimation of the first light transmitted from the optical module is increased compared to the first light before transmitting through the optical module.

[0020] The plurality of light emitting elements and / or the inner surface of the cavity may be configured such that substantially only the first light is incident on the linear collimator of the optical module. In other words, the plurality of light emitting elements and / or the inner surface of the cavity may be configured such that substantially no second light is incident on the linear collimator of the optical module. The optical module may include a plurality of linear collimators. At least one of the plurality of linear collimators may be configured to collimate at least the first light.

[0021] The linear collimator may be constituted by or may include, for example, a linear lens.

[0022] Therefore, the appearance of the first light can be more closely resembling the appearance of a solar beam. The optical module may include a diffuser. The diffuser may be configured to diffuse the appearance of the linear collimator to an observer viewing the lighting device from a distance. Furthermore, the diffuser may be configured to diffuse substantially only the appearance of the linear collimator to an observer viewing the lighting device from a distance. The linear collimator may be disposed between the light-emitting element and the diffuser. The linear collimator may be configured by a reflector, a lens, an optical element based on total internal reflection (TIR), and / or a diffractive element, or may include a reflector, a lens, an optical element based on total internal reflection (TIR), and / or a diffractive element. The linear collimator may be configured as a linear refractive lens. The linear collimator may be a linear Fresnel lens. The linear Fresnel lens may include a refractive segment. However, the linear Fresnel lens may include a refractive segment and a TIR segment.

[0023] The lighting device may further include a plurality of light-emitting elements disposed within the cavity and arranged consecutively along a longitudinal axis of the lighting device. The plurality of light-emitting elements may be configured to emit a third light that strikes a surface of the optical module without first striking an interior surface of the cavity. The optical module may further be configured to collimate the third light in a cross-section and to generate collimated light such that the light transmitted from the optical module has an increased degree of collimation in a cross-section compared to the third light prior to transmission through the optical module. The optical module and at least one of the plurality of light-emitting elements configured to emit the third light may be configured such that the third light transmitted from the optical module has a direction different from the direction of the first light transmitted by the optical module.

[0024] Thus, an illumination device configured to emit a third light can enhance the illumination device's resemblance to a natural window or skylight. The optical module may include a lens configured to collimate at least the first light and another lens configured to collimate at least the third light. In other words, the optical module may include a lens configured to collimate substantially only the first light and another lens configured to collimate substantially only the third light. The different light-emitting elements may be differently positioned within the cavity such that each light-emitting element may emit light having different characteristics from light emitted by the other light-emitting elements, and the characteristics may include light color, light direction, light intensity, and / or degree of light collimation.

[0025] Furthermore, the lighting device may include a control unit coupled to and configured to selectively turn on or off the plurality of light-emitting elements configured to emit the first light and the plurality of light-emitting elements configured to emit the third light, respectively.

[0026] Thus, the degree of control over the light emitted by the lighting device can be increased. Increasing the degree of control over the light emitted by the lighting device can increase the similarity of the lighting device to a natural window or skylight. The control unit may be configured to control the direction of the light emitted by the lighting device. The direction of the light emitted by the lighting device may be controlled by the control unit by selectively turning on or off multiple light-emitting elements. Each of the multiple light-emitting elements may emit light having a direction. Further, the control unit may be configured to control the direction of the light emitted by the lighting device such that the direction of the light emitted by the lighting device is substantially the same as the direction of the sun with respect to the optical module. At least one of the multiple light-emitting elements configured to emit the first light and the multiple light-emitting elements configured to emit the third light may be configured to emit the second light. The control unit may be configured to selectively turn on or off at least one of the multiple light-emitting elements configured to emit the second light, the multiple light-emitting elements configured to emit the third light, and the multiple light-emitting elements configured to emit the first light. Thereby, the control unit may be configured to control the first light and / or the third light with respect to the second light. Further, at least one other of the plurality of light-emitting elements configured to emit the second light may be configured such that the second light reflected by an inner surface of the cavity and thereafter impinging on a surface of the optical module and transmitted from the optical module is white light.

[0027] The cavity may have a rectangular or curved shape, which may mean that the cross section of the cavity, for example in a plane perpendicular to the longitudinal axis, may have a rectangular or curved shape.

[0028] This allows the secondary light reflected by the inner surface of the cavity to be controlled by the shape of the cavity. Controlling the secondary light can enhance the similarity of the light emitted by the lighting device to the light of a natural window or skylight. This can also increase the intensity of the light emitted by the lighting device. The cross section of the cavity along the longitudinal direction of the lighting device can have a rectangular or curved shape. The concept of the present invention is not limited by the shape being rectangular or curved, and the shape can have virtually any geometric shape.

[0029] The inner surface may have a first inner surface and a second inner surface. The first inner surface may be configured so that the second light, which is reflected by the first inner surface of the cavity, then strikes the surface of the optical module and is transmitted through the optical module, has at least 3% of its total luminous flux within a wavelength range of 400 to 470 nm. The second inner surface may be configured so that the second light, which is reflected by the second inner surface of the cavity, then strikes the surface of the optical module and is transmitted through the optical module, has a higher proportion of its total luminous flux within the wavelength range of 400 to 470 nm than the proportion of its total luminous flux within the wavelength range of 400 to 470 nm of the second light reflected by the first inner surface. The second inner surface of the cavity may have at least one of a reflectance for light in the wavelength range of 400 to 470 nm that is higher than the reflectance for light in the wavelength range of 400 to 470 nm of the first inner surface, and a reflectance for light in the wavelength range of 470 to 650 nm that is lower than the reflectance for light in the wavelength range of 470 to 650 nm of the first inner surface.

[0030] Thus, the similarity between the light emitted by the lighting device and the light of a natural window or skylight can be enhanced, particularly with respect to the appearance of the lighting device as seen by an observer looking directly at the lighting device. The first inner surface may be configured to resemble clouds as seen by an observer viewing the lighting device from a distance. The second inner surface may be configured to resemble blue sky as seen by an observer viewing the lighting device from a distance. The inner surface may include a plurality of first inner surfaces. Further, the inner surface may include a plurality of second inner surfaces. The first inner surface(s) and the second inner surface(s) may be configured to create the appearance of a cloudy sky as seen by an observer viewing the lighting device from a distance. The first inner surface of the cavity may, for example, include a first paint. The first paint may be configured to reflect white light and / or blue light. The first paint may, for example, include a white paint, a blue paint, or a mixture of white paint and blue paint. The second inner surface of the cavity may, for example, include a second paint. The second paint may be configured to reflect blue light. The second paint may include blue paint. The second paint may be configured to reflect more blue light than the first paint. The first inner surface of the cavity may include scattering nanoparticles configured to scatter and / or reflect white light. The second inner surface of the cavity may include scattering nanoparticles configured to scatter and / or reflect blue light and absorb light of colors other than blue.

[0031] The inner surface may include a passive reflective display device, such that the second light may impinge on a surface of the passive reflective display device. The surface of the passive reflective display device may include a plurality of passive reflective display device sections. Further, the lighting device may include a control unit. The control unit may be coupled to the passive reflective display device and configured to supply a voltage to each passive reflective display device section. The passive reflective display device sections may be in a first state when a first voltage is applied to the passive reflective display device sections by the control unit. The passive reflective display device sections may be in a second state when a second voltage is applied to the passive reflective display device sections by the control unit. The first voltage may be different from the second voltage. The passive reflective display device section in the first state may be configured such that second light reflected by the passive reflective display device section in the first state, then impinging on a surface of the optical module and transmitted through the optical module has at least 3% of its total luminous flux being light within the wavelength range of 400 to 470 nm.The passive reflective display device section in the second state may be configured to have at least one of a reflectivity for light in the wavelength range of 400 to 470 nm that is higher than a reflectivity for light in the wavelength range of 400 to 470 nm of the passive reflective display device section in the first state, and a reflectivity for light in the wavelength range of 470 to 650 nm that is lower than a reflectivity for light in the wavelength range of 470 to 650 nm of the passive reflective display device section in the first state, so that the proportion of the total luminous flux of second light reflected by the passive reflective display device section in the second state, which then impinges on the surface of the optical module and is transmitted through the optical module is light whose proportion of the wavelength range of 400 to 470 nm is higher than the proportion of the total luminous flux of the second light reflected by the passive reflective display device section in the first state that is within the wavelength range of 400 to 470 nm.

[0032] A passive reflective display device may be, for example, but not limited to, formed by or include one or more electronic ink (e-ink) displays. The term "electronic ink display" means e-paper, electrophoretic display, e-ink, electrowetting display, or electrofluidic display.

[0033] The lighting device may further include a light-transmitting layer. The light-transmitting layer may be disposed within the cavity at a distance from the inner surface such that the light-transmitting layer and the inner surface enclose a space for containing a fluid. A first fluid and a second fluid may be provided within the space. The first fluid and the second fluid may have different optical properties with respect to at least one of reflectance, absorbance, transmittance, or scattering of light impinging on the first fluid and the second fluid, respectively. The light-transmitting layer may be disposed such that second light impinges on at least one of the first fluid and the second fluid.

[0034] The first fluid may be configured to transmit light impinging on the first fluid, and the second fluid may be configured to reflect white light impinging on the second fluid.

[0035] The first fluid may be configured to reflect blue light impinging on the second fluid, the second fluid may be configured to transmit light impinging on the second fluid, and the interior surface of the cavity may be configured to reflect white light.

[0036] The second fluid may be configured to absorb red and green light and transmit blue light, and the interior surface of the cavity may be configured to reflect light, such that light impinging on the light-transmitting layer may be transmitted by the first fluid or the second fluid.

[0037] Furthermore, the first fluid may be configured to reflect blue light impinging on the first fluid, and the second fluid may be configured to reflect white light impinging on the second fluid, such that substantially all light impinging on the light-transmitting layer may be reflected by the first fluid or the second fluid. The arrangement of the light-transmitting layer, the first fluid, and the second fluid may be understood as a reflective layer.

[0038] Therefore, the similarity of the lighting device to a natural window or skylight can be enhanced, particularly with respect to the appearance of the lighting device as seen by an observer looking directly at the lighting device. The space may be defined or delimited by substantially all (the entire) of the interior surface. The first fluid and the second fluid may be immiscible. In other words, the first fluid and the second fluid may be configured to not mix or blend. The density of the first fluid may be different from the density of the second fluid. The first fluid may be oil-based and the second fluid may be water-based. The first fluid and the second fluid may be configured to move within the space, which can enhance the similarity of the lighting device to a natural window or skylight.

[0039] The lighting device may be arranged, for example, on a wall or a ceiling.

[0040] The lighting device may be disposed, for example, at a corner separating a wall and a ceiling, thereby being disposed on both the wall and the ceiling. Furthermore, the lighting device may include a longitudinal extension and a transverse extension perpendicular to the longitudinal extension. The longitudinal extension of the lighting device may be larger than the transverse extension. For example, the longitudinal extension of the lighting device may be 10 times or more larger than the transverse extension of the lighting device. That is, the lighting device may be elongated. The lighting device may be disposed on a wall or ceiling from one side of a room to the other side of the room. In other words, the lighting device may be disposed along the entire wall or ceiling. This may make the lighting device appear even more similar to a skylight. A person viewing the lighting device from a distance may not notice that the light emitted by the lighting device is not collimated in a direction along the longitudinal extension of the lighting device.

[0041] According to a second aspect of the present invention there is provided a lamp, luminaire or lighting system comprising a lighting device according to the first aspect of the present invention. [Brief explanation of the drawings]

[0042] Exemplary embodiments of the present invention are described below with reference to the accompanying drawings. [Figure 1] 1 is a schematic diagram of a lighting device in accordance with one or more exemplary embodiments of the present invention. [Figure 2] 1 is a schematic diagram of a lighting device in accordance with one or more exemplary embodiments of the present invention. [Figure 3] 1 is a schematic diagram of a cross section of a lighting device perpendicular to a longitudinal axis of the lighting device, according to an exemplary embodiment of the present invention. [Figure 4] 1 is a schematic diagram of a cross section of a lighting device perpendicular to a longitudinal axis of the lighting device, according to an exemplary embodiment of the present invention. [Figure 5] 1 is a schematic diagram of a cross section of a lighting device perpendicular to a longitudinal axis of the lighting device, according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0043] All figures are schematic, not necessarily to scale, and generally show only those parts necessary to clarify embodiments of the invention; other parts may be omitted or merely suggested.

[0044] The present invention will now be described below with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments of the invention set forth herein; rather, these embodiments of the invention are provided as examples so that this disclosure will convey the scope of the technology to those skilled in the art. In the drawings, the same reference numerals, unless otherwise specified, indicate the same or similar components having the same or similar function.

[0045] FIG. 1 is a schematic diagram of a lighting device 1 in accordance with one or more exemplary embodiments of the present invention. FIG. 1 illustrates the lighting device 1 from a perspective view. The illustrated lighting device 1 includes a rectangular body defined by an inner surface 11 and an optical module 20. The inner surface 11 defines a cavity 10 extending along a longitudinal axis L of the lighting device 1. The inner surface 11 is configured to reflect light impinging on the inner surface 11 of the cavity 10. The cavity 10 has an opening 12 that allows light within the cavity 10 to exit the cavity 10. The opening 12 extends along the longitudinal axis L of the lighting device 1. The inner surface 10 may be viewed as three sides of the body of the lighting device 1, and the opening 12 may be viewed as a fourth side of the body of the lighting device 1. The three sides of the body of the lighting device 1 defined by the inner surface 10 may be viewed as a left side, a right side, and a top. However, the concept of the present invention is not limited to the rectangular shape of the cavity 10 shown in FIG. 1. The cavity 10 may have any geometric shape, such as a curved shape or a shape including any number of sides, such as three, four, five, six, seven, eight, or more. The optical module 20 is disposed in the opening 12 of the cavity 10. The illustrated optical module 20 completely covers the opening 12. However, a portion of the fourth side of the body of the lighting device 1 may be formed by the inner surface 11. The optical module 20 may be configured to transmit light impinging on the surface 21 of the optical module 20 through the optical module 20. The light transmitted through the optical module 20 is emitted from the lighting device 1. FIG. 1 illustrates a plurality of light-emitting elements 31 disposed within the cavity 10 and arranged consecutively along the longitudinal axis L of the lighting device 1. It should be understood that the plurality of light-emitting elements 31 is illustrated schematically in FIG. 1. The plurality of light-emitting elements 31 may include, for example, LEDs that are relatively closely packed consecutively along the longitudinal axis L (i.e., arranged with a relatively small distance between any adjacent LEDs). The illustrated plurality of light emitting elements 31 are arranged at a distance from the center of the cavity 10 with respect to the width of the lighting device 1. However, the plurality of light emitting elements 31 may also be arranged in the center of the cavity 10 with respect to the width of the lighting device 1.The plurality of light-emitting elements 31 shown in FIG. 1 are arranged farther from the surface 21 of the optical module 20 than the inner surface 11 opposite the surface 21 of the optical module 20 (i.e., the top surface of the main body of the lighting device 1). The concept of the present invention is not limited to the arrangement of the plurality of light-emitting elements 31 as shown in FIG. 1. The plurality of light-emitting elements 31 may be arranged at any position within the cavity 10 and may extend along the longitudinal axis L of the lighting device 1. Furthermore, the plurality of light-emitting elements 31 may be arranged on the surface 21 and / or the inner surface 21 of the optical module 20. The plurality of light-emitting elements 31 may extend along the longitudinal axis L of the lighting device 1 and be arranged obliquely with respect to the longitudinal axis L. The plurality of light-emitting elements 31 are configured to emit a first light 41 (not shown, see FIGS. 3 and 4) that hits the surface 21 of the optical module 20 without first hitting the inner surface 11 of the cavity 10, and a second light 42 (not shown, see FIGS. 3 and 4) that hits the inner surface 11 of the cavity 10. The illustrated optical module 20 is configured to collimate the first light 41 in a cross-section. The cross-section is a plane perpendicular to the longitudinal axis L of the lighting device 1. Furthermore, the optical module 20 is configured to generate collimated light such that the degree of collimation of the light in the cross-section transmitted from the optical module 20 is increased compared to the first light 41 before passing through the optical module 20. At least one of the inner surface 11 of the cavity 10, the plurality of light-emitting elements 31, and the optical module 20 is configured such that the second light 42 reflected by the inner surface 11 of the cavity 10, then impinging on the surface 21 of the optical module 20 and transmitted from the optical module 20 is light having a wavelength in the range of 400 to 470 nm, with at least 3% of the total luminous flux being light.

[0046] Figure 2 is a schematic diagram of a lighting device 1 according to one or more exemplary embodiments of the present invention. It should be noted that Figure 2 includes the features, elements and / or functions shown in Figure 1 and described in the associated text. Therefore, for a better understanding, reference is also made to that figure and the associated description.

[0047] 2 includes a first inner surface 11a and a second inner surface 11b. The illustrated second inner surface 11b is shown as a number of geometric shapes on the inner surface 11. The second inner surface 11b may have any geometric shape, such as an oval, a rectangle, or a cloud. The second inner surfaces 11b may be interspersed with the first inner surface 11a.

[0048] According to an exemplary embodiment, the first inner surface 11a is configured such that the second light 42 that is reflected by the first inner surface 11a of the cavity 10, then strikes the surface 21 of the optical module 20, and is transmitted through the optical module 20 is light having at least 3% of its total luminous flux within the wavelength range of 400 to 470 nm. Furthermore, according to an exemplary embodiment, the second inner surface 11b of the cavity has at least one of a reflectivity for light in the wavelength range of 400 to 470 nm that is higher than the reflectivity for light in the wavelength range of 400 to 470 nm of the first inner surface, and a reflectivity for light in the wavelength range of 470 to 650 nm that is lower than the reflectivity for light in the wavelength range of 470 to 650 nm of the first inner surface, so that the second light 42 that is reflected by the second inner surface 11b of the cavity 10, then impinges on the surface 21 of the optical module 20, and is transmitted through the optical module 20 has a higher proportion of the total luminous flux within the wavelength range of 400 to 470 nm than the proportion of the total luminous flux of the second light reflected by the first inner surface 11a within the wavelength range of 400 to 470 nm.

[0049] According to another exemplary embodiment, the inner surface 11 includes a passive reflective display device, e.g., configured by or including an electronic ink (e-ink) display, such that the second light impinges on the surface of the passive reflective display device. Reference is made below to an example of a passive reflective display device in the form of an e-ink display, but it should be understood that a passive reflective display device other than or of another type than an e-ink display may alternatively or additionally be employed similarly or equivalently to an e-ink display as described below. The surface of the e-ink display includes a plurality of e-ink sections. The e-ink display includes a control unit 50 (not shown, see FIG. 5 ) coupled to the e-ink display and configured to supply a voltage to each e-ink section. The e-ink sections are in a first state when a first voltage is applied to the e-ink sections by the control unit, and the e-ink sections are in a second state when a second voltage is applied to the e-ink sections by the control unit. The first voltage is different from the second voltage. The electronic ink section in the first state 11b is configured such that the second light that is reflected by the electronic ink section in the first state, then strikes the surface of the optical module, and is transmitted through the optical module has at least 3% of the total luminous flux being light within the wavelength range of 400 to 470 nm.The electronic ink section in the second state 11a has at least one of a reflectivity for light in the wavelength range 400-470 nm that is higher than the reflectivity for light in the wavelength range 400-470 nm of the electronic ink section in the first state and a reflectivity for light in the wavelength range 470-650 nm that is lower than the reflectivity for light in the wavelength range 470-650 nm of the electronic ink section in the first state, so that the proportion of the total luminous flux of the second light reflected by the electronic ink section in the second state, which then strikes the surface of the optical module and is transmitted through the optical module is higher than the proportion of the total luminous flux of the second light reflected by the electronic ink section in the first state 11b that is within the wavelength range 400-470 nm. The exemplary embodiment shown in FIG. 2 includes three clusters of electronic ink sections in the first state 11b. Each of the three clusters of electronic ink sections in the first state 11b has a geometric shape, which may be viewed as an oval or a cloud. All other electronic ink sections are electronic ink sections in the second state 11a. The electronic ink sections in the first state 11b may be viewed as being interspersed among the electronic ink sections in the second state 11a.

[0050] Figure 3 is a schematic diagram of a cross section of a lighting device 1 perpendicular to the longitudinal axis of the lighting device, according to an exemplary embodiment of the present invention. It should be noted that Figure 3 includes features, elements and / or functions shown in Figure 1 and described in the associated text. Therefore, for a better understanding, reference is also made to that figure and the associated description.

[0051] The lighting device 1 shown in FIG. 3 includes an inner surface 11 having three sides. The three sides of the inner surface 11 are arranged in an inverted U-shape (which may be viewed as a Pi-shape). Two corners of the inner surface that separate the three sides are right-angled. However, the corners may be rounded or curved. The inner surface 11 defines a cavity 10. The cavity 10 includes an opening 12. The opening 12 is defined by the ends of the two sides of the inner surface 11. An optical module 20 is disposed at the opening 12 of the cavity 10. The optical module 20 has a surface 21 facing the cavity 10. Furthermore, the lighting device 1 includes a plurality of light-emitting elements 31 arranged relative to the cavity 10, similar to that shown in FIG. 1. The plurality of light-emitting elements 31 are shown emitting a first light 41. The first light impinges on the surface 21 of the optical module 20 without first impinging on the inner surface 11 of the cavity 10. The optical module 20 collimates the first light 41 in a cross-section perpendicular to the longitudinal axis L (not shown, see FIG. 1) of the lighting device 1. As a result, the optical module 20 generates collimated light that has a higher degree of collimation in the cross-section after being transmitted from the optical module 20 compared to the first light 41 before passing through the optical module 20. FIG. 3 shows the collimated first light transmitted from the optical module 20 as a defined beam. The direction of the beam in the cross-section is exemplary and may be any direction in the cross-section. For example, the beam direction may be at any angle between -90 and 90 degrees with respect to the normal of the surface of the optical module 20 facing outward from the cavity 10 (i.e., the surface opposite the surface 21 of the optical module 20) in the cross-section. Additionally, the plurality of light emitting elements 31 are shown emitting a second light 42. The second light 42 strikes the inner surface 11 of the cavity 10. It should be understood that the second light 42 reflects from the inner surface 11 and strikes the surface 21 of the optical module 20, or strikes the inner surface 11 again. When the second light 42 strikes the surface 21 of the optical module 20, it either reflects back to strike the inner surface 11, or is transmitted through the optical module 20.

[0052] Figure 4 is a schematic diagram of a cross section of a lighting device perpendicular to the longitudinal axis of the lighting device, according to an exemplary embodiment of the present invention. It should be noted that Figure 4 includes the features, elements and / or functions shown in Figure 3 and described in the associated text. Therefore, for a better understanding, reference is also made to that figure and the associated description.

[0053] The difference between the exemplary embodiment shown in FIG. 3 and the exemplary embodiment shown in FIG. 4 is that the lighting device 1 shown in FIG. 4 includes an additional plurality of light-emitting elements 32. The additional plurality of light-emitting elements 32 are arranged consecutively along the longitudinal axis L of the lighting device 1 and disposed within the cavity 10. The additional plurality of light-emitting elements 32 emit a third light 43. The third light 43 strikes the surface 21 of the optical module 20 without first striking the inner surface 11 of the cavity 10. Furthermore, the optical module 20 is configured to collimate the third light 43 in a cross-section and to generate collimated light such that the degree of collimation of the light in a cross-section transmitted from the optical module 20 is increased compared to the third light 43 before transmitting through the optical module 20. The optical module 20 and at least one of the plurality of light-emitting elements 32 configured to emit the third light 43 are configured such that the third light 43 transmitted from the optical module 20 has a direction different from the direction of the first light 41 transmitted from the optical module 20. The arrangement of the plurality of light-emitting elements 31 and the additional plurality of light-emitting elements 32 shown in FIG. 4 is exemplary. The plurality of light-emitting elements 31 and the additional plurality of light-emitting elements 32 may be disposed at substantially any position within the cavity 10. For example, the additional plurality of light-emitting elements 32 may be disposed between the surface 21 of the optical module 20 and the plurality of light-emitting elements 31. Furthermore, the concept of the present invention is not limited to one additional plurality of light-emitting elements, but may include any number of additional plurality of light-emitting elements, such as two, three, four, five, six, or more. It should be understood that the plurality of light-emitting elements 31 and the additional plurality of light-emitting elements 32 are configured to emit a second light 42 (not shown; see FIG. 3 ). The second light 42 emitted by the plurality of light-emitting elements 31 and the additional plurality of light-emitting elements 32 is omitted for ease of illustration only. Therefore, the concept of the present invention is not limited by the omission of the second light in FIG. 4 .

[0054]

[0023] Figure 5 is a schematic diagram of a cross section of a lighting device perpendicular to the longitudinal axis of the lighting device, according to an exemplary embodiment of the present invention. It should be noted that Figure 5 includes features, elements and / or functions shown in Figures 1-4 and described in the associated text. Accordingly, reference is made to such figures and their associated descriptions for a better understanding.

[0055] The difference between the exemplary embodiment shown in FIG. 5 and the exemplary embodiments shown in FIGS. 3 and 4 is that the lighting device 1 shown in FIG. 5 further includes a control unit 50. The control unit 50 in FIG. 5 is coupled to the plurality of light-emitting elements 31 via a cable. Furthermore, the lighting device 1 shown in FIG. 5 includes a light-transmitting layer 60. The light-transmitting layer 60 is disposed in the cavity 10 at a distance from the inner surface 11 such that the light-transmitting layer 60 and the inner surface 11 enclose a space for containing a fluid. A first fluid and a second fluid are provided in the space. The first fluid is configured to transmit light impinging on the first fluid. The second fluid is configured to reflect white light impinging on the second fluid. The light-transmitting layer 60 is disposed such that second light 42 (not shown, see FIG. 3) impinges on at least one of the first fluid and the second fluid. The control unit 50 may include a pump, which is coupled to the space and configured to move the first fluid and the second fluid within the space.

[0056] An exemplary embodiment is a lighting device 1 that includes an additional plurality of light emitting elements 32 (not shown, see FIG. 4 ) and a control unit 50. The control unit 50 is coupled to and configured to selectively turn on or off the plurality of light emitting elements 31, 32 configured to emit a first light 41 and the plurality of light emitting elements configured to emit a third light 43, respectively.

[0057] In conclusion, a lighting device is provided. The lighting device includes a cavity. The cavity extends along a longitudinal axis of the lighting device. The cavity is further defined by an inner surface configured to reflect light impinging on the inner surface of the cavity. The cavity has an opening that allows light within the cavity to exit the cavity. The lighting device further includes an optical module. The optical module is disposed within or at the opening of the cavity and configured to transmit light impinging on a surface of the optical module through the optical module. The light transmitted through the optical module is emitted from the lighting device. The lighting device further includes a plurality of light-emitting elements. The light-emitting elements are arranged consecutively along the longitudinal axis of the lighting device, disposed within the cavity, and configured to emit a first light. The first light impinges on a surface of the optical module without first impinging on the inner surface of the cavity. The light-emitting elements are further configured to emit a second light. The second light impinges on the inner surface of the cavity. The optical module is configured to collimate the first light in a transverse cross section. The cross-section is perpendicular to the longitudinal axis of the lighting device. Furthermore, the optical module is configured to generate collimated light such that the degree of collimation of the light in the cross-section transmitted from the optical module is increased compared to the first light before transmitting through the optical module. At least one of the inner surface of the cavity (11), the plurality of light-emitting elements, and the optical module is configured such that the second light reflected by the inner surface of the cavity, then striking a surface of the optical module, and transmitted from the optical module has at least 3% of its total luminous flux within the wavelength range of 400-470 nm.

[0058] While the invention has been described in the accompanying drawings and in the foregoing description, such description is to be considered illustrative and exemplary and not restrictive, and the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments will be apparent to those skilled in the art from a study of the drawings, the disclosure, and the appended claims, and can be implemented in practicing the claimed invention. In the appended claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims are not to be interpreted as limiting the scope.

Claims

1. 1. A linear lighting device having a length, a width, and a longitudinal axis, wherein the length and the width have an aspect ratio of at least 2, the linear lighting device comprising: a cavity extending along the longitudinal axis, the cavity being defined by an inner surface configured to reflect light impinging on the inner surface of the cavity, the cavity having an opening that allows light within the cavity to exit the cavity; an optical module disposed within or at the opening of the cavity, the optical module configured to transmit light impinging on a surface of the optical module through the optical module, the light transmitted through the optical module being emitted from the linear illumination device; and a plurality of light emitting elements arranged consecutively along the longitudinal axis of the linear lighting device, the light emitting elements being disposed within the cavity and configured to emit a first light that strikes the surface of the optical module without first striking the inner surface of the cavity, and a second light that strikes the inner surface of the cavity; Including, the optical module includes a linear collimator configured to collimate the first light in a cross-section perpendicular to the longitudinal axis of the linear lighting device and to produce collimated light that has been transmitted from the optical module to increase the degree of collimation of the light in the cross-section compared to the first light before transmitting through the optical module; at least one of the plurality of light-emitting elements is arranged such that the first light emitted by the plurality of light-emitting elements has less than 3% of a total luminous flux of light within a wavelength range of 400 to 470 nm; at least one of the inner surface of the cavity, the plurality of light-emitting elements, and the optical module is configured such that the second light reflected by the inner surface of the cavity and then impinging on the surface of the optical module and transmitted from the optical module is light having at least 3% of its total luminous flux within a wavelength range of 400 to 470 nm.

2. 2. The linear lighting device of claim 1, wherein at least one of the plurality of light emitting elements is arranged such that the second light emitted by the plurality of light emitting elements has at least 3% of its total luminous flux in the wavelength range of 400 to 470 nm.

3. 10. The linear lighting device of claim 1, wherein the inner surface of the cavity has a reflectivity of 80% or more for light in the wavelength range of 400-470 nm and a reflectivity of less than 80% for light at other wavelengths.

4. 4. The linear lighting device of claim 3, wherein the inner surface of the cavity is configured such that the inner surface of the cavity has a reflectivity of 80% or more for light within a wavelength range of 400 to 470 nm and a reflectivity of less than 80% for light at other wavelengths, such that the second light that is reflected by the inner surface of the cavity and then strikes the surface of the optical module and is transmitted through the optical module has at least 3% of its total luminous flux within the wavelength range of 400 to 470 nm.

5. 5. A linear illumination device according to claim 1, wherein the linear collimator is a linear lens.

6. The linear lighting device comprises: a plurality of light emitting elements arranged consecutively along the longitudinal axis of the linear lighting device, the light emitting elements being disposed within the cavity and configured to emit a third light that impinges on the surface of the optical module without first impinging on the inner surface of the cavity; Including, the optical module is configured to collimate the third light in the cross-section and to generate collimated light such that the degree of collimation of the light in the cross-section transmitted from the optical module is increased compared to the third light before transmitting through the optical module; 5. A linear lighting device according to claim 1, wherein the optical module and at least one of the plurality of light-emitting elements configured to emit the third light are configured such that the third light transmitted from the optical module has a direction different from the direction of the first light transmitted from the optical module.

7. The linear lighting device comprises:

7. The linear lighting device of claim 6, further comprising a control unit coupled to each of a plurality of light emitting elements configured to emit the first light and a plurality of light emitting elements configured to emit the third light, and configured to selectively turn on or off the light emitting elements.

8. 5. A linear lighting device according to any one of the preceding claims, wherein the cross section of the cavity has a rectangular or curved shape.

9. The inner surface is having a first inner surface and a second inner surface; the first inner surface is configured so that the second light reflected by the first inner surface of the cavity, then striking the surface of the optical module and transmitted through the optical module has at least 3% of its total luminous flux in a wavelength range of 400 to 470 nm; 5. The linear lighting device of claim 1, wherein the second inner surface of the cavity has at least one of a reflectivity for light in a wavelength range of 400 to 470 nm that is higher than a reflectivity for light in the wavelength range of 400 to 470 nm of the first inner surface and a reflectivity for light in a wavelength range of 470 to 650 nm that is lower than a reflectivity for light in the wavelength range of 470 to 650 nm of the first inner surface, so that the second light that is reflected by the second inner surface of the cavity and then impinges on the surface of the optical module and is transmitted through the optical module has a proportion of its total luminous flux that is within the wavelength range of 400 to 470 nm that is higher than a proportion of the total luminous flux of the second light that is within the wavelength range of 400 to 470 nm that is reflected by the first inner surface.

10. the inner surface includes a passive reflective display device such that the second light impinges on a surface of the passive reflective display device, the surface of the passive reflective display device including a plurality of passive reflective display device sections; the linear lighting device includes a control unit coupled to the passive reflective display device and configured to provide a voltage to each passive reflective display device section; the passive reflective display device section is in a first state when a first voltage is applied to the passive reflective display device section by the control unit, and the passive reflective display device section is in a second state when a second voltage is applied to the passive reflective display device section by the control unit, the first voltage being different from the second voltage; the passively reflective display device section in the first state is configured such that the second light reflected by the passively reflective display device section in the first state, thereafter striking the surface of the optical module and transmitted through the optical module has at least 3% of its total luminous flux in a wavelength range of 400 to 470 nm; 5. The linear illumination device of claim 1, wherein the passive reflective display device section in the second state has at least one of a reflectivity for light in a wavelength range of 400 to 470 nm that is higher than a reflectivity for light in the wavelength range of 400 to 470 nm of the passive reflective display device section in the first state and a reflectivity for light in a wavelength range of 470 to 650 nm that is lower than a reflectivity for light in the wavelength range of 470 to 650 nm of the passive reflective display device section in the first state, such that the proportion of the second light reflected by the passive reflective display device section in the second state, and subsequently impinging on the surface of the optical module and transmitted through the optical module is light whose proportion within the wavelength range of 400 to 470 nm in its total luminous flux is higher than a proportion within the wavelength range of 400 to 470 nm of the total luminous flux of the second light reflected by the passive reflective display device section in the first state.

11. The linear lighting device comprises: a light-transmitting layer disposed within the cavity at a distance from the inner surface such that the light-transmitting layer and the inner surface enclose a space for containing a fluid; a first fluid and a second fluid provided in the space, the first fluid and the second fluid having different optical properties with respect to at least one or more of reflectance, absorbance, transmittance, or scattering of light impinging on the first fluid and the second fluid, respectively; Including, 5. A linear lighting device according to claim 1, wherein the light transmitting layer is arranged such that the second light impinges on at least one of the first fluid and the second fluid.

12. 5. A linear lighting device according to any one of the preceding claims, wherein the linear lighting device is arranged on a wall or a ceiling.

13. 5. A lamp, luminaire or lighting system comprising a linear lighting device according to any one of claims 1 to 4.

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