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US 12,650,627 B2Granted
Marks for angular optical filters
AssigneeRealD Spark, LLC
InventorsJonathan Harrold, Graham J. Woodgate, Michael G Robinson, Robert Ramsey, Ben Ihas
Life of this patent
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Abstract
A privacy display comprises a spatial light modulator and a view angle control element that may comprise a first polariser that may be a reflective polariser, a liquid crystal retarder, a compensation retarder and an additional polariser. The layer of liquid crystal material is patterned with a mark. The display provides visibility of the mark in reflected light to an off-axis snooper but no visibility of the image on the spatial light modulator; and provides high visibility of an image with no visibility of the mark to an on-axis display user.
Claims40
A view angle control element for arrangement outside a first polariser that is a linear polariser, the view angle control element comprising:
- an additional polariser, the additional polariser being a linear polariser;
- and
- at least one polar control retarder for arrangement between the first polariser and the additional polariser, the at least one polar control retarder including a passive liquid crystal retarder comprising a layer of liquid crystal material, wherein the layer of liquid crystal material has at least one region in a shape of a mark for display to an observer arranged such that:
- along a predetermined viewing axis, relative phase shifts are introduced to orthogonal polarisation components of light that are sufficiently small in the at least one region and the remainder of the layer of liquid crystal material that the mark is not visible;
- and
- along a non-viewing axis at a different angle from the viewing axis, relative phase shifts are introduced to orthogonal polarisation components of light that are different in the at least one region and the remainder of the layer of liquid crystal material such that the mark is visible;
- wherein the layer of liquid crystal material has profiles of splay of the director directions across the thickness direction of the layer of liquid crystal material that are different in the at least one region and the remainder of the layer of liquid crystal material;
- wherein the layer of liquid crystal material has director directions at surfaces on opposite sides of the layer of liquid crystal material in the at least one region that are one of:
- (a) homogenous at both surfaces;
- (b) homogenous at one of the surfaces and homeotropic at the other of the surfaces;
- or (c) homeotropic at both surfaces;
- and
- the layer of liquid crystal material has director directions at surfaces on opposite sides of the layer of liquid crystal material in the remainder of the layer of liquid crystal material are one of:
- (a) homogenous at both surfaces;
- (b) homogenous at one of the surfaces and homeotropic at the other of the surfaces;
- or (c) homeotropic at both surfaces, that is different from the at least one region.
13 more elements
A view angle control element for arrangement outside a first polariser that is a linear polariser, the view angle control element comprising:
- an additional polariser, the additional polariser being a linear polariser;
- and
- at least one polar control retarder for arrangement between the first polariser and the additional polariser, the at least one polar control retarder including a passive liquid crystal retarder comprising a layer of liquid crystal material, wherein the layer of liquid crystal material has at least one region in a shape of a mark for display to an observer arranged such that:
- along a predetermined viewing axis, relative phase shifts are introduced to orthogonal polarisation components of light that are sufficiently small in the at least one region and the remainder of the layer of liquid crystal material that the mark is not visible;
- and
- along a non-viewing axis at a different angle from the viewing axis, relative phase shifts are introduced to orthogonal polarisation components of light that are different in the at least one region and the remainder of the layer of liquid crystal material such that the mark is visible;
- wherein the layer of liquid crystal material has profiles of splay of the director directions across the thickness direction of the layer of liquid crystal material that are different in the at least one region and the remainder of the layer of liquid crystal material;
- wherein the layer of liquid crystal material has director directions at surfaces on opposite sides of the layer of liquid crystal material that are different in the at least one region and the remainder of the layer of liquid crystal material.
5 more elements
A view angle control element for arrangement outside a first polariser that is a linear polariser, the view angle control element comprising:
- an additional polariser, the additional polariser being a linear polariser;
- and
- at least one polar control retarder for arrangement between the first polariser and the additional polariser, the at least one polar control retarder including a passive liquid crystal retarder comprising a layer of liquid crystal material, wherein the layer of liquid crystal material has at least one region in a shape of a mark for display to an observer arranged such that:
- along a predetermined viewing axis, relative phase shifts are introduced to orthogonal polarisation components of light that are sufficiently small in the at least one region and the remainder of the layer of liquid crystal material that the mark is not visible;
- and
- along a non-viewing axis at a different angle from the viewing axis, relative phase shifts are introduced to orthogonal polarisation components of light that are different in the at least one region and the remainder of the layer of liquid crystal material such that the mark is visible;
- and
- a further view angle control element for arrangement outside a further first polariser that is a linear polariser, the further view angle control element comprising:
- a further additional polariser, the further additional polariser being a linear polariser;
- and a further polar control retarder for arrangement between the further first polariser and the further additional polariser, the further polar control retarder including a further passive liquid crystal retarder comprising a further layer of liquid crystal material;
- wherein the further layer of liquid crystal material has director directions at surfaces disposed adjacent to the further layer of liquid crystal material and on opposite sides thereof that are homogenous at one of the surfaces and homeotropic at the other of the surfaces;
- and comprises no passive compensation retarder.
9 more elements
A display device comprising:
- a view angle control element for arrangement outside a first polariser that is a linear polariser, the view angle control element comprising:
- an additional polariser, the additional polariser being a linear polariser;
- and
- at least one polar control retarder for arrangement between the first polariser and the additional polariser, the at least one polar control retarder including a passive liquid crystal retarder comprising a layer of liquid crystal material, wherein the layer of liquid crystal material has at least one region in a shape of a mark for display to an observer arranged such that:
- along a predetermined viewing axis, relative phase shifts are introduced to orthogonal polarisation components of light that are sufficiently small in the at least one region and the remainder of the layer of liquid crystal material that the mark is not visible;
- and
- along a non-viewing axis at a different angle from the viewing axis, relative phase shifts are introduced to orthogonal polarisation components of light that are different in the at least one region and the remainder of the layer of liquid crystal material such that the mark is visible;
- a spatial light modulator arranged to output light;
- and
- a display polariser arranged on a side of the spatial light modulator, the display polariser being the first polariser;
- wherein the relative phase shifts introduced to orthogonal polarisation components of light along the non-viewing axis are sufficiently high that the operational image is not visible, when a security factor Sn defined at the angle in question is, for at least one of the at least one region of the layer of liquid crystal material and the remainder of the layer of liquid crystal material, at least 1.0, where the security factor Sn is given by the equation:
- S
- n
- =
- log
- 1
-
- 0
- [
- 1
- +
- ρ
- n
- ·
- α
- /
- (
- π
- ·
- P
- n
- )
- ]
- wherein:
- ρn is the reflectivity of the display device at the angle in question;
- Pn is the ratio of the luminance of the display device at the angle in question to the maximum luminance of the display device;
- π is a solid angle in units of steradians;
- and
- α is a factor having a value of 4.0 steradians.
36 more elements
Dependencies are inferred from the claim text.