Light output device
A light output device comprises a first and a second substrate arrangement ( 1,2 ), the first substrate arrangement ( 1 ) comprising a light output surface of the device. An electrode arrangement ( 3 a, 3 b ) is sandwiched between the substrate arrangements and at least one light source ( 4 ) is connected to the electrode arrangement. The first substrate ( 1 ) arrangement comprises a light diffuser for changing the level of uniformity of the light output from the light source and the second substrate ( 2 ) arrangement comprises a light scattering or reflecting layer. This arrangement uses a scattering substrate arrangement for the substrate from which illumination is provided. In order to enhance the level of uniformity, the opposite substrate arrangement is also either scattering or reflecting.
1. A light output device having a laminated glass structure, the device comprising:
a first substrate arrangement comprising a first glass layer, a light output surface of the device and means for controlling the level of uniformity of the light output from the light output surface;
a second substrate arrangement comprising a second glass layer and light deflecting means;
an electrode arrangement provided between the first and the second substrate arrangement and comprising substantially transparent or translucent electrodes;
at least one light source provided between the first and the second substrate arrangement.
2. A device as claimed in claim 1 , wherein the first substrate arrangement is switchable between at least two states having different levels of uniformity of the light output from the light output surface.
3. A device as claimed in claim 1 , wherein the first substrate arrangement is switchable between a substantially transparent state and a state which provides an increased level of uniformity of the light output from the light output surface.
4. A light output device having a laminated glass structure, the device comprising:
a first substrate arrangement comprising a first glass layer, a light output surface of the device and means for controlling the level of uniformity of the light output from the light output surface;
a second substrate arrangement comprising a second glass layer and light deflecting means;
at least one light source having its output optically coupled to a space between the substrate arrangements,
wherein the first substrate arrangement is switchable between at least two states having different levels of uniformity of the light output from the light output surface.
5. A device as claimed in claim 4 , wherein the first substrate arrangement is switchable between a substantially transparent state and a state which provides an increased level of uniformity of the light output from the light output surface.
6. A device as claimed in claim 4 , further comprising an electrode arrangement disposed between the substrate arrangements, wherein the at least one light source is connected to the electrode arrangement.
7. A device as claimed in claim 6 , wherein the electrode arrangement comprises a substantially transparent conductive material.
8. A device as claimed in claim 4 , having a switchable first substrate arrangement comprising an liquid crystal (LC) layer disposed between the electrodes.
9. A device as claimed in claim 4 , wherein different regions of the first substrate arrangement are independently switchable.
10. A device as claimed in claim 9 , comprising a passive matrix conductor arrangement for controlling the switching.
11. A device as claimed in claim 4 , wherein the second substrate arrangement is switchable between a substantially transparent state and a reflecting state.
12. A device as claimed in claim 4 , wherein the second substrate arrangement is switchable between a substantially transparent state and a diffusive state.
13. A device as claimed in claim 4 , wherein the first substrate arrangement has a non-uniform thickness, having increased thickness at a region corresponding to the location of the light source, and a reduced thickness at a region remote from the light source.
14. A device as claimed in claim 4 , wherein the first substrate arrangement comprises a plurality of light scattering particles embedded in the glass layer with a non-uniform density, the scattering particles having increased density at a region corresponding to the location of the light source, and a reduced density at a region remote from the light source.
15. A device as claimed in claim 4 , wherein the light source comprises an LED device or a group of LED devices and is embedded in a thermoplastic or resin layer, wherein each of the first and second substrate arrangements comprises a glass layer having embedded scattering particles, and wherein the or each LED device comprises an inorganic LED, an organic LED (OLED), a polymer LED (polyLED) or a laser diode.
16. A device as claimed in claim 4 , further comprising means for controlling the level of uniformity by modulating the switching function.