Variable light attenuating devices and arrangements
A non-polarizer based variable light attenuating device includes a guest-host solution having a liquid crystal host and a guest dichroic dye disposed between first and second conducting layers provided on first and second transparent substrates. The guest-host solution has a low-haze while the guest dye orientation alters between a low light transmitting orientation and a high light transmitting orientation in response to a first voltage supplied to the first and second conducting layers. In response to a second voltage supplied to the first and second conducting layers, the guest-host solution changes to a focal conic light scattering orientation to achieve a high-haze translucent state.
1. A non-polarizer based variable light attenuating device comprising:
a non-polarization based liquid crystal cell comprising first and second transparent substrates having first and second conducting layers provided thereon; and
a guest-host solution comprising a liquid crystal and a dichroic dye disposed between the first and second conducting layers;
wherein the guest-host solution has a low-haze while the dye orientation alters between a low light transmitting orientation and a high light transmitting orientation in response to a first voltage supplied to the first and second conducting layers;
further wherein the guest-host solution is arranged in a droplet-sized light scattering orientation causing high-haze in response to a second voltage supplied to the first and second conducting layers and wherein the guest-host solution reverts to the low-haze state when no voltage is applied to the first and second conducting layers.
2. The device of claim 1 , wherein the dye is substantially perpendicular to the first and second substrates when no voltage is supplied to the conducting layers and substantially parallel to the first and second substrates when the first voltage is supplied to the conducting layers.
3. The device of claim 1 , wherein the dye is substantially parallel to the first and second substrates when no voltage is supplied to the conducting layers and substantially perpendicular to the first and second substrates when the first voltage is supplied to the conducting layers.
4. The device of claim 1 , further comprising a control circuit for supplying a variable voltage to the first and second conducting layers.
5. The device of claim 4 , further comprising a user interface to give a user complete or partial control over light transmittance through the device.
6. The device of claim 4 , further comprising a photovoltaic cell configured to generate a voltage in response to light detected by the photovoltaic cell.
7. The device of claim 4 , wherein the control circuit performs at least one of:
(a) control the first voltage to vary light transmission through the device automatically, in response to user manipulation of the control circuit, or a combination thereof;
(b) control the second voltage to vary light diffusion through the device automatically, in response to user manipulation of the control circuit, or a combination thereof;
(c) set a threshold level for supplying the first voltage automatically or as set by a user; and
(d) set a threshold level for supplying the second voltage automatically or as set by a user.
8. The device of claim 1 , wherein at least one transparent substrate further comprises a luminescent dye that absorbs light at a first wavelength and emits light at a second wavelength different than the first wavelength.
9. The device of claim 1 , wherein the guest-host solution further comprises a luminescent dye that absorbs light at a first wavelength and emits light at a second wavelength different than the first wavelength.
10. The device of claim 1 , wherein the guest-host mixture comprises a positive dielectric anisotropy chiral liquid crystal host, a dichroic dye guest having positive dichroism, a polymerizable material and an initiator; and wherein at least one of the transparent substrates comprises a planar alignment layer.
11. The device of claim 10 , wherein the chiral liquid crystal has a pitch longer than 850 nm.
12. The device of claim 1 , wherein the device has a low-haze value that is equal to or less than 15%.
13. The device of claim 1 , wherein the device has a high-haze value that is higher than 15%.
14. The device of claim 1 , wherein said device is used with windows, goggles, glasses, or protective eye shielding devices.
15. The device of claim 1 , wherein the chiral liquid crystal has a pitch between 2-5 μm.
16. A non-polarizer based variable light attenuating device comprising:
a non-polarization based liquid crystal cell comprising first and second conducting layers provided on first and second transparent substrates and a guest-host mixture disposed between said conducting layers,
wherein said guest-host mixture is in a low-haze low light-transmitting state when no voltage is applied to the cell; a low-haze high light-transmitting state when a first voltage is applied to the cell; and a focal conic light diffusing state to achieve high-haze when a second voltage is applied to the cell.
17. The device of claim 16 , wherein the guest-host mixture comprises a positive dielectric anisotropy chiral liquid crystal host, a dichroic dye guest having positive dichroism, a polymerizable material and an initiator; and wherein at least one of the transparent substrates comprises a planar alignment layer.
18. The device of claim 17 , wherein the chiral liquid crystal has a pitch longer than 850 nm.
19. The device of claim 16 , wherein the guest-host mixture in a low-haze state has a haze value equal to or less than 15%.
20. A non-polarizer based variable light attenuating device comprising:
a non-polarization based liquid crystal cell comprising a guest-host mixture disposed between first and second conducting layers provided on first and second transparent substrates;
wherein at least one transparent substrate comprises a planar alignment layer;
wherein the guest-host mixture comprises a positive dielectric anisotropy chiral liquid crystal host having a pitch longer than 850 nm, a dichroic dye guest having positive dichroism, a polymerizable material and an initiator;
wherein in the absence of a voltage the liquid crystal host has a planar-helical orientation with minimal light scattering and the cell is in a low-haze high light-absorption state,
wherein when a first voltage is applied to the cell the liquid crystal has a light scattering focal conic orientation and the cell is in a high-haze state,
wherein when a second voltage is applied to the cell the liquid crystal has a homeotropic orientation with minimal light scattering and the cell is in a low-haze low-light absorption state.
21. The device of claim 20 , further comprising a control circuit for supplying the first and second voltage to the liquid crystal cell.
22. The device of claim 20 , wherein the chiral liquid crystal has a pitch between 2-5 μm.