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US 5,686,979 AGranted
Optical panel capable of switching between reflective and transmissive states
AssigneeMinnesota Mining and Manufacturing Company
InventorsMichael F. Weber, Andrew J. Ouderkirk, David J. W. Aastuen
Life of this patent
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Abstract
A device, comprising a switchable optical panel and means for switching the panel between a reflecting state and a transmitting state. The switchable optical panel includes a transparent optically active layer having a first and a second major surface, a first reflective polarizer disposed on the first major surface and a second reflective polarizer disposed on the second major surface. The optically active layer preferably comprises a liquid crystal device and the switching means preferably comprises a system of drying electronics for applying voltage across the liquid crystal device. The invention also includes a switchable window and a transflective optical display.
Claims72
A switchable optical device, comprising:
- a switchable optical panel, comprising:
- a transparent optically active layer having a first and a second major surface;
- a first reflective polarizer disposed on the first major surface of the optically active layer;
- and
- a second reflective polarizer disposed on the second major surface of the optically active layer;
- and
- means for switching the panel between a reflecting state and a transmitting state,
- wherein the first and second reflective polarizers each comprise a multilayered stack of pairs of adjacent material layers, each of the layer pairs exhibiting a refractive index difference between the adjacent layers in a first direction in the plane of the polarizer and exhibiting essentially no refractive index difference between adjacent layers in a second direction in the plane of the polarizer and orthogonal to the first direction.
5 more elements
A device, comprising:
- a switchable optical panel, comprising:
- a twisted nematic liquid crystal device comprising first and second transparent substrates in parallel register defining a cavity therebetween, each substrate having an outer surface and an inner surface facing the cavity, and a liquid crystal material confined in the cavity;
- continuous transparent conductive layers disposed on the inner surfaces of the substrates;
- a first reflective polarizer disposed on the outer surface of the first substrate;
- and
- a second reflective polarizer disposed on the outer surface of the second substrate;
- and
- a system of driving electronics connected to the conductive layers;
- wherein the first and second reflective polarizers each comprise a stack of at least 100 layer pairs, wherein each layer pair comprises a first positive birefringent layer adjacent to a second layer, wherein each layer pair has a thickness in the range from 100 to 500 nm, wherein the stack is uniaxially stretched at a ratio in the range of 4:1 to 7:1 and wherein each positive birefringent layer has an index of refraction in the stretch direction that is between 0.1 and 0.3 greater than the index of refraction in the transverse direction, so that the panel is electronically switchable between a reflecting state and a transmitting state.
6 more elements
A switchable optical device, comprising:
- a switchable optical panel, comprising:
- a liquid crystal device, comprising:
- a pair of reflective polarizers in parallel register defining a cavity therebetween, the reflective polarizers each having an inner surface facing the cavity and an outer surface;
- a liquid crystal material confined in the cavity;
- and
- transparent conductive layers on the inner surfaces of the reflective polarizers;
- and
- a system of driving electronics connected to the conductive layers, so that the panel is electronically switchable between a reflecting state and a transmitting state,
- wherein the reflective polarizers each comprise a multilayered stack of pairs of adjacent material layers, each of the layer pairs exhibiting a refractive index difference between the adjacent layers in a first direction in the plane of the polarizer and exhibiting essentially no refractive index difference between adjacent layers in a second direction in the plane of the polarizer and orthogonal to the first direction.
6 more elements
A switchable window, comprising:
- a switchable optical panel, comprising:
- a liquid crystal device comprising first and second transparent planar substrates in parallel register defining a cavity therebetween, each substrate having an outer surface and an inner surface facing the cavity, and a liquid crystal material confined in the cavity;
- a first reflective polarizer disposed on the outer surface of the first substrate of the liquid crystal;
- and
- a second reflective polarizer disposed on the outer surface of the second substrate of the liquid crystal;
- and
- means for electronically switching the panel between an open state and a closed state,
- wherein the first and second reflective polarizers each comprise a multilayered stack of pairs of adjacent material layers each of the layers exhibiting a refractive index difference between the adjacent layers in a first direction in the plane of the polarizer and exhibiting essentially no refractive index difference between adjacent layers in a second direction in the plane of the polarizer and orthogonal the first direction.
5 more elements
A switchable window, comprising:
- a first transparent pane having first and second major surfaces;
- a first reflective polarizer disposed on the first transparent pane;
- at least one shutter comprising a second transparent pane, a second reflective polarizer disposed on the second transparent pane, and a birefringent layer disposed on a side of the second transparent pane opposite the second reflective polarizer;
- and
- means for rotating the shutter to position either the birefringent layer or the second reflective polarizer adjacent and parallel to the first reflective polarizer, so that the window is mechanically switchable between an open and a closed state,
- wherein the reflective polarizer comprises a multilayered stack of pairs of adjacent material layers, each of the layer pairs exhibiting a refractive index difference between the adjacent layers in a first direction in the plane of the polarizer and exhibiting essentially no refractive index difference between adjacent layers in a second direction in the plane of the polarizer and orthogonal to the first direction.
3 more elements
A transflective optical display, comprising:
- a liquid crystal display device comprising a front absorptive polarizer, a rear absorptive polarizer and a pixellated liquid crystal display device located therebetween;
- a backlight for illuminating the liquid crystal display device;
- an optical diffuser located between the liquid crystal display device and the backlight;
- and
- a switchable transflector located between the optical diffuser and the backlight, the switchable transflector comprising:
- a non-pixellated liquid crystal device, comprising:
- a front substrate, facing the optical diffuser, and a rear substrate in parallel register and defining a cavity therebetween, each of the substrates having an inner surface facing the cavity and an outer surface;
- a conductive material on the inner surface of each substrate;
- and
- a liquid crystal material confined in the cavity;
- the non-pixellated liquid crystal device having a front alignment direction associated with the front substrate and a rear alignment direction associated with the rear substrate;
- a reflective polarizer disposed on the rear substrate of the non-pixellated liquid crystal display device and proximate to the backlight;
- and
- means for electronically switching the transflector between a reflecting state and a transmitting state, wherein the polarization orientation of the rear absorptive polarizer is parallel to the front alignment direction of the non-pixellated liquid crystal device.
11 more elements
A switchable optical device, comprising:
- a switchable optical panel, comprising:
- a transparent optically active layer having a first and a second major surface;
- a first reflective polarizer disposed on the first major surface of the optically active layer;
- and
- a second reflective polarizer disposed on the second major surface of the optically active layer;
- and
- means for switching the panel between a reflecting state and a transmitting state,
- wherein the first and second reflective polarizers each comprise a multilayered stack of pairs of adjacent material layers, and each of the layer pairs exhibits a refractive index difference between the adjacent layers in a first direction in the plane of the polarizer which is greater than a refractive index difference between adjacent layers in a second direction in the plane of the polarizer and orthogonal to the first direction.
5 more elements
A device, comprising:
- a switchable optical panel, comprising:
- a twisted nematic liquid crystal device comprising first and second transparent substrates in parallel register defining a cavity therebetween, each substrate having an outer surface and an inner surface facing the cavity, and a liquid crystal material confined in the cavity;
- continuous transparent conductive layers disposed on the inner surfaces of the substrates;
- a first reflective polarizer disposed on the outer surface of the first substrate;
- and
- a second reflective polarizer disposed on the outer surface of the second substrate;
- and
- a system of driving electronics connected to the conductive layers;
- wherein the first and second reflective polarizers each comprise a multilayered stack of pairs of adjacent material layers, and each of the layer pairs exhibits a refractive index difference between the adjacent layers in a first direction in the plane of the polarizer which is greater than a refractive index difference between adjacent layers in a second direction in the plane of the polarizer and orthogonal to the first direction.
6 more elements
A switchable optical device, comprising:
- a switchable optical panel, comprising:
- a liquid crystal device, comprising:
- a pair of reflective polarizers in parallel register defining a cavity therebetween, the reflective polarizers each having an inner surface facing the cavity and an outer surface;
- a liquid crystal material confined in the cavity;
- and transparent conductive layers on the inner surfaces of the reflective polarizers;
- and
- a system of driving electronics connected to the conductive layers, so that the panel is electronically switchable between a reflecting state and a transmitting state;
- and
- wherein the reflective polarizers each comprise a multilayered stack of pairs of adjacent material layers, and each of the layer pairs exhibits a refractive index difference between the adjacent layers in a first direction in the plane of the polarizer which is greater than a refractive index difference between adjacent layers in a second direction in the plane of the polarizer and orthogonal to the first direction.
6 more elements
A switchable window, comprising:
- a switchable optical panel, comprising:
- a liquid crystal device comprising first and second transparent planar substrates in parallel register defining a cavity therebetween, each substrate having an outer surface and an inner surface facing the cavity, and a liquid crystal material confined in the cavity;
- a first reflective polarizer disposed on the outer surface of the first substrate of the liquid crystal;
- and
- a second reflective polarizer disposed on the outer surface of the second substrate of the liquid crystal;
- and
- means for electronically switching the panel between an open state and a closed state;
- and
- wherein the first and second reflective polarizers each comprise a multilayered stack of pairs of adjacent material layers, and each of the layer pairs exhibits a refractive index difference between the adjacent layers in a first direction in the plane of the polarizer which is greater than a refractive index difference between adjacent layers in a second direction in the plane of the polarizer and orthogonal to the first direction.
6 more elements
A switchable window, comprising:
- a first transparent pane having first and second major surfaces;
- a first reflective polarizer disposed on the first transparent pane;
- at least one shutter comprising a second transparent pane, a second reflective polarizer disposed on the second transparent pane, and a birefringent layer disposed on a side of the second transparent pane opposite the second reflective polarizer;
- and
- means for rotating the shutter to position either the birefringent layer or the second reflective polarizer adjacent and parallel to the first reflective polarizer, so that the window is mechanically switchable between an open and a closed state;
- and
- wherein the first and second reflective polarizers each comprise a multilayered stack of pairs of adjacent material layers, and each of the layer pairs exhibits a refractive index difference between the adjacent layers in a first direction in the plane of the polarizer which is greater than a refractive index difference between adjacent layers in a second direction in the plane of the polarizer and orthogonal to the first direction.
4 more elements
Dependencies are inferred from the claim text.