Display device with uniform off-axis luminance reduction

Patent metadata

Field	Value
Publication number	US-12587618-B2
Application number	US-202318104892-A
Country	US
Kind code	B2
Filing date	Feb 2, 2023
Priority date	Feb 9, 2022
Publication date	Mar 24, 2026
Grant date	Mar 24, 2026

Abstract

A display device comprising a spatial light modulator having a display polariser arranged on one side of the spatial light modulator is provided with an additional polariser arranged on the same side as the display polariser and a polar control retarder between the additional polariser and the display polariser. The polar control retarder includes a liquid crystal retarder having two surface alignment layers disposed adjacent to a layer of liquid crystal material on opposite sides. The surface alignment layers provide alignment in the adjacent liquid crystal material with a twist. The out-of-plane orientation of the twisted layer of liquid crystal material is modified across at least one region of the display device to provide a pupillated transmission function, achieving increased luminance uniformity to a display user and increased uniformity of security factor to an off-axis snooper, or reduced distraction across the display to the driver in an automotive application.

First claim

The invention claimed is:

1 . A display device comprising:
a spatial light modulator arranged to output spatially modulated light; a display polariser arranged on a side of the spatial light modulator, the display polariser being a linear polariser; and a view angle control arrangement comprising:
an additional polariser arranged on the same side of the spatial light modulator as the display polariser, the additional polariser being a linear polariser; and
at least one polar control retarder arranged between the display polariser and the additional polariser, wherein the at least one polar control retarder comprises a switchable liquid crystal retarder comprising a layer of liquid crystal material;
two surface alignment layers disposed adjacent to the layer of liquid crystal material and on opposite sides thereof, the surface alignment layers each being arranged to provide homogenous alignment in the adjacent liquid crystal material, the surface alignment layers having an in-plane component in the plane of the layer of liquid crystal material having an angle that changes monotonically along a predetermined axis across at least part of the display device, the liquid crystal material being provided with a twist; and
first and second electrode arrangements disposed on opposite sides of the layer of liquid crystal material,
wherein the first and second electrode arrangements are arranged to provide an electric field perpendicular to the layer of liquid crystal material, wherein the magnitude of the electric field changes monotonically along a predetermined axis across at least part of the display, and
wherein the first electrode arrangement comprises a continuous electrode, the continuous electrode having at least one contact disposed at each of opposite ends of the continuous electrode along the predetermined axis and arranged to supply respective voltages that create a voltage profile on the continuous electrode along the predetermined axis for providing the electric field perpendicular to the layer of liquid crystal material.

2 . A display device according to claim 1 , wherein components of the optical axis of the liquid crystal material in the plane of the layer of liquid crystal material have an average direction that is along a predetermined direction.

3 . A display device according to claim 1 , wherein the switchable liquid crystal retarder has a retardance for light of a wavelength of 550 nm in a range from 300 nm to 1500 nm.

4 . A display device according to claim 1 , wherein the twist is in a range from 60° to 120°.

5 . A display device according to claim 1 , wherein the electric vector transmission direction of the additional polariser is oriented at a non-zero angle with respect to the electric vector transmission direction of the display polariser.

6 . A display device according to claim 5 , wherein the non-zero angle is the same as the twist.

7 . A display device according to claim 1 , wherein the magnitude of the electric field changes monotonically along a predetermined axis across at least part of the display device so that directions of minimum light transmission of the view angle control arrangement from points of said at least part of the display device are directed towards a common off-axis point in front of the display device.

8 . A display device according to claim 1 , wherein
the surface alignment layer closest to the display polariser has a pretilt having a pretilt direction with a component in the plane of the layer of liquid crystal material that is parallel or perpendicular to an electric vector transmission direction of the display polarisers, and the surface alignment layer closest to the additional polariser has a pretilt having a pretilt direction with a component in the plane of the layer of liquid crystal material that is parallel or perpendicular to an electric vector transmission direction of the additional polariser.

9 . A display device according to claim 1 , wherein the continuous electrode extends over the entirety of the layer of liquid crystal material.

10 . A display device according to claim 9 , wherein at least one of the contacts comprises a conductive bar extending perpendicular to the predetermined axis.

11 . A display device according to claim 9 , wherein the second electrode arrangement is arranged to supply a common voltage.

12 . A display device according to claim 11 , wherein the second electrode arrangement comprises a continuous electrode extending over the entirety of the layer of liquid crystal material.

13 . A display device according to claim 1 , further comprising a control system arranged to control the spatial light modulator and to supply voltages to the first and second electrode arrangements for providing the electric field perpendicular to the layer of liquid crystal material.

14 . A display device according to claim 1 , wherein the at least one polar control retarder further comprises at least one passive retarder.

15 . A display device according to claim 14 , wherein the at least one passive retarder is an A-plate with a retardance for light of a wavelength of 550 nm in a range of 250 nm to 300 nm.

16 . A display device according to claim 1 , wherein the liquid crystal material has a positive dielectric anisotropy.

17 . A display device according to claim 1 , wherein the display device is curved with a concave curvature as viewed from an output side.

18 . A display device according to claim 1 , wherein said display polariser is an output display polariser arranged on an output side of the spatial light modulator.

19 . A display device according to claim 18 , wherein there is not a reflective polariser arranged between the output display polariser and the at least one polar control retarder.

20 . A display device according to claim 18 , further comprising a reflective polariser arranged between the output display polariser and the at least one polar control retarder, the reflective polariser being a linear polariser arranged to pass the same linearly polarised polarisation component as the output display polariser.

21 . A display device according to claim 18 , wherein the spatial light modulator comprises an emissive spatial light modulator arranged to emit the spatially modulated light.

22 . A display device according to claim 18 , wherein the spatial light modulator comprises a transmissive spatial light modulator and a backlight is arranged to illuminate the spatial light modulator.

23 . A display device according to claim 1 , wherein the spatial light modulator comprises a transmissive spatial light modulator, the display device further comprises a backlight arranged to illuminate the spatial light modulator, and said display polariser is an input display polariser arranged on an input side of the spatial light modulator.

24 . A display device according to claim 23 , further comprising:
an output display polariser arranged on an output side of the spatial light modulator; a further additional polariser arranged on the output side of the spatial light modulator, the further additional polariser being a linear polariser; and at least one further polar control retarder arranged between the further additional polariser and the output display polariser.

25 . A display device according to claim 24 , wherein
the at least one further polar control retarder comprises a switchable liquid crystal retarde

Assignees

• Reald Spark Llc

Inventors

• Robinson Michael G
• Harrold Jonathan
• Woodgate Graham J
• Ramsey Robert A

Classifications

• B60K35/81

  for controlling displays · CPC title

• B60K35/29

  Instruments characterised by the way in which information is handled, e.g. showing information on plural displays or prioritising information according to driving conditions · CPC title

• B60K35/223

  Flexible displays · CPC title

• G02F1/134363

  for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS] · CPC title

• G02F1/13336

  Combining plural substrates to produce large-area displays, e.g. tiled displays · CPC title