摘要:
A lighted sign housing is provided with a diffuse reflective film that is selected based on its reflectivity and luminance uniformity in order to reduce power consumption required for a given luminance while also increasing luminance uniformity. A method of using such film is also provided.
摘要:
An illuminated sign system provides uniform illumination over the lamp face by using partially transmissive lamp masks located between the lamps and the sign face. The sign face itself also diffusely reflects at least a majority of light incident on its second surface back towards the interior of the sign. The lamp spacing ratio in the illuminated signs can be increased, e.g., to a ratio of 3:1 or more, and, possibly, to a ratio of 4:1 or more.
摘要:
A low-loss, diffuser film is provided for translucent surface(s) of lighted signage. The film has little absorptivity and has partial transmissivity and partial reflectivity. Luminance efficiency and brightness are significantly improved over conventional films used in backlit signage. A luminance efficiency prediction equation is also provided to aid in selection of diffuser films and interior surfaces of the lighted sign cavity. A combination of effects of diffuser films and a diffuse reflective films lining the interior surfaces of the lighted sign cavity is unexpectedly greater than their sum of effects operating alone.
摘要:
A backlight that includes a front reflector and a back reflector that form a hollow light recycling cavity including an output surface is disclosed. The backlight further includes one or more light sources disposed to emit light into the light recycling cavity. The front reflector includes an on-axis average reflectivity of at least 90% for visible light polarized in a first plane, and an on-axis average reflectivity of at least 25% but less than 90% for visible light polarized in a second plane perpendicular to the first plane.
摘要:
A backlight unit (10) has a hollow cavity (16) instead of employing a light guide. One or more light sources (24a-c), such as LEDs, are arranged to emit light into the cavity, which is formed by a front (12) and a back reflector (14). The backlight is typically of the edge-lit type. The backlight can have a large area, is thin and consists of fewer components than conventional devices. Its design permits light recycling. The unit emits light of a predefined polarisation and can be arranged to have desired horizontal/vertical viewing angle properties. Light is uniformly distributed within the guide and the light output (20b, 2Od) is substantially collimated. Such backlights occupy a specific region in a parameter space defined by two parameters: first, the ratio of the output emission area to the total source emission area should lie in the range 0.0001 to 0.1; and second, the ratio of the SEP to the height of the cavity (H) should be in the range 3 to 10, where the SEP is an average plan view source separation, a special measure of the average spacing of light sources in the plane of the unit. There is also a discussion on the required number of light sources N, their arrangement near the periphery of the cavity, as well as the shape and size of the output emission area. A required minimum brightness uniformity (VESA) value to be maintained, when a subset of Madjacent sources is switched off (where M is at least 0.1 N or M>2 or both), is also disclosed. The backlight can be used for a display or for general lighting purposes.
摘要:
An edge-lit backlight comprises a front and back reflector forming a hollow light recycling cavity having a cavity depth H and an output region of area Aout, and one or more light sources disposed proximate a periphery of the backlight to emit light into the light recycling cavity. The light sources have an average plan view source separation of SEP collectively having an active emitting area Aemit, wherein a first parameter equals Aemit/Aout and a second parameter equals SEP/H. The first parameter is in a range from 0.0001 to 0.1, and by the second parameter is in a range from 3 to 10. The front reflector has a hemispherical reflectivity for unpolarized visible light of Rfhemi, and the back reflector has a hemispherical reflectivity for unpolarized visible light of Rbhemi, and Rfhemi*Rbhemi is at least 0.70.
摘要:
A backlight that includes a front reflector and a back reflector that form a hollow light recycling cavity including an output surface is disclosed. The backlight further includes one or more light sources disposed to emit light into the light recycling cavity. The front reflector includes an on-axis average reflectivity of at least 90% for visible light polarized in a first plane, and an on-axis average reflectivity of at least 25% but less than 90% for visible light polarized in a second plane perpendicular to the first plane.
摘要:
A hollow light-recycling backlight has a “semi-specular” component providing a balance of specularly and diffusely reflected light improving the uniformity of the light output. The component may be arranged on the reflectors (1021), (1014) or inside the cavity (1016). This balance is achieved by designing the component's “transport ratio” defined by (F−B)/(F+B), (F and B are the amounts of incident light scattered forwards and backwards respectively by the component in the plane of the cavity) to lie in a certain range. Furthermore, the product of the front and back reflector “hemispherical” reflectivities should also lie in a given range. Alternatively, the “cavity transport value”, a measure of how well the cavity can spread injected light from the injection point to distant points in the cavity should lie in a further range and the “hemispherical” reflectivity of the back reflector should be >0.7.
摘要:
A hollow light-recycling backlight has a “semi-specular” component providing a balance of specularly and diffusely reflected light improving the uniformity of the light output. The component may be arranged on the reflectors (1021), (1014) or inside the cavity (1016). This balance is achieved by designing the component's “transport ratio” defined by (F−B)/(F+B), (F and B are the amounts of incident light scattered forwards and backwards respectively by the component in the plane of the cavity) to lie in a certain range. Furthermore, the product of the front and back reflector “hemispherical” reflectivities should also lie in a given range. Alternatively, the “cavity transport value”, a measure of how well the cavity can spread injected light from the injection point to distant points in the cavity should lie in a further range and the “hemispherical” reflectivity of the back reflector should be >0.7.
摘要:
The disclosure generally relates to concentrating daylight collectors, and in particular to concentrating daylight collectors useful for interior lighting of a building. The concentrating daylight collectors generally include a plurality of moveable reflective vanes and a Cassegrain-type concentrator section.