Patent Grant
11237417
This disclosure generally relates to illumination from light modulation devices, and more specifically relates to optical stacks for providing control of illumination for use in display including privacy display and night-time display.
Privacy displays provide image visibility to a primary user that is typically in an on-axis position and reduced visibility of image content to a snooper, that is typically in an off-axis position. A privacy function may be provided by micro-louvre optical films that transmit some light from a display in an on-axis direction with low luminance in off-axis positions. However such films have high losses for head-on illumination and the micro-louvres may cause Moiré artefacts due to beating with the pixels of the spatial light modulator. The pitch of the micro-louvre may need selection for panel resolution, increasing inventory and cost.
Switchable privacy displays may be provided by control of the off-axis optical output.
Control may be provided by means of luminance reduction, for example by means of switchable backlights for a liquid crystal display (LCD) spatial light modulator. Display backlights in general employ waveguides and edge emitting sources. Certain imaging directional backlights have the additional capability of directing the illumination through a display panel into viewing windows. An imaging system may be formed between multiple sources and the respective window images. One example of an imaging directional backlight is an optical valve that may employ a folded optical system and hence may also be an example of a folded imaging directional backlight. Light may propagate substantially without loss in one direction through the optical valve while counter-propagating light may be extracted by reflection off tilted facets as described in U.S. Pat. No. 9,519,153, which is herein incorporated by reference in its entirety.
According to a first aspect of the present disclosure there is provided a display device comprising a backlight arranged to output light; a transmissive spatial light modulator arranged to receive output light from the backlight; a display polariser arranged on a side of the spatial light modulator, the display polariser being a linear polariser; a first additional polariser arranged on the same side of the spatial light modulator as the display polariser, the first additional polariser being a linear polariser; at least one first polar control retarder arranged between the first additional polariser and the display polariser, a second additional polariser, the second additional polariser being a linear polariser; and at least one second polar control retarder, wherein either: the second additional polariser is arranged on the same side of the spatial light modulator as the first additional polariser outside the first additional polariser, and the at least one second polar control retarder is arranged between the first additional polariser and the second additional polariser; or said display polariser is an input display polariser arranged on the input side of the spatial light modulator, and the display device further comprises an output display polariser arranged on the output side of the spatial light modulator, the second additional polariser is arranged on the output side of the spatial light modulator, and the at least one second polar control retarder is arranged between the second additional polariser and the output display polariser, wherein: each of the at least one first polar control retarder and the at least one second polar control retarder comprises a respective switchable liquid crystal retarder comprising a layer of liquid crystal material and two surface alignment layers disposed adjacent to the layer of liquid crystal material and on opposite sides thereof, in respect of one of the at least one first polar control retarder and the at least one second polar control retarder, both of the surface alignment layers are arranged to provide homogenous alignment in the adjacent liquid crystal material, and in respect of the other of the at least one first polar control retarder and the at least one second polar control retarder, both of the surface alignment layers are arranged to provide homeotropic alignment in the adjacent liquid crystal material, and the switchable liquid crystal retarder of said one of the at least one first polar control retarder and the at least one second polar control retarder has a retardance for light of a wavelength of 550 nm having a first retardance value and the switchable liquid crystal retarder of said other of the at least one first polar control retarder and the at least one second polar control retarder has a retardance for light of a wavelength of 550 nm has a second retardance value, the first retardance value and the second retardance value being different, the magnitude of the difference between the first retardance value and the second retardance value being at least 10% of the average of the first retardance value and the second retardance value. The magnitude of the difference between the first retardance value and the second retardance value may be at least 25% of the average of the first retardance value and the second retardance value.
A switchable display device may be provided that may provide switching of luminance profile over a large polar region. The display device may for example provide switching between illumination of a passenger, and illumination of a driver and passenger for a switchable privacy display in an automotive application. In other applications switching between a primary display user and a snooper may be provided.
The first retardance value may be greater than the second retardance value. The first retardance value may be in a range from 500 nm to 2000 nm, preferably in a range from 700 nm to 1500 nm, and the second retardance value may be in a range from 350 nm to 900 nm, preferably in a range from 500 nm to 850 nm. Advantageously colour variation with polar angle may be reduced in share mode of operation for the driver.
The first retardance value may be less than the second retardance value. The first retardance value may be in a range from 350 nm to 1000 nm, preferably in a range from 500 nm to 900 nm, and the second retardance value may be in a range from 650 nm to 2800 nm, preferably in a range from 1000 nm to 2000 nm. Advantageously colour variation with polar angle may be reduced in privacy mode of operation for the passenger.
Said one of the at least one first polar control retarder and the at least one second polar control retarder may further comprise at least one passive compensation retarder. Advantageously the size of the polar region over which luminance is reduced in privacy mode may be increased.
The at least one passive compensation retarder of said one of the at least one first polar control retarder and the at least one second polar control retarder may comprise a pair of passive uniaxial retarders having optical axes in the plane of the retarders that are crossed. The first retardance value may be greater than the second retardance value, and the pair of passive uniaxial retarders having optical axes in the plane of the retarders that are crossed may each have a retardance for light of a wavelength of 550 nm in a range from 300 nm to 1500 nm, preferably in a range from 500 nm to 1200 nm. The first retardance value may be less than the second retardance value, and the pair of passive uniaxial retarders having optical axes in the plane of the retarders that are crossed may each have a retardance for light of a wavelength of 550 nm in a range from 300 nm to 900 nm, preferably in a range from 400 nm to 800 nm. Advantageously increased security factor may be achieved for the driver leaning towards the display.
The at least one passive compensation retarder of said other of the at least one first polar control retarder and the at least one second polar control retarder may comprise a passive uniaxial retarder having its optical axis perpendicular to the plane of the retarder. The first retardance value may be greater than the second retardance value, and the passive uniaxial retarder having its optical axis perpendicular to the plane of the retarder has a retardance for light of a wavelength of 550 nm in a range from −300 nm to −1700 nm, preferably in a range from −500 nm to −1200 nm. The first retardance value may be less than the second retardance value, and the passive uniaxial retarder having its optical axis perpendicular to the plane of the retarder has a retardance for light of a wavelength of 550 nm in a range from −250 nm to −800 nm, preferably in a range from −300 nm to −700 nm. Advantageously reduced colour variation may be seen by the driver in share mode of operation.
Said other of the at least one first polar control retarder and the at least one second polar control retarder may further comprise at least one passive compensation retarder. The at least one passive compensation retarder of said other of the at least one first polar control retarder and the at least one second polar control retarder may comprise a passive uniaxial retarder having its optical axis perpendicular to the plane of the retarder. The first retardance value may be greater than the second retardance value, and the passive uniaxial retarder having its optical axis perpendicular to the plane of the retarder has a retardance for light of a wavelength of 550 nm in a range from −250 nm to −850 nm, preferably in a range from −400 nm to −800 nm. The first retardance value may be less than the second retardance value, and the passive uniaxial retarder having its optical axis perpendicular to the plane of the retarder has a retardance for light of a wavelength of 550 nm in a range from −400 nm to −2400 nm, preferably in a range from −700 nm to −1700 nm. Advantageously increased size of the polar regions for which security factor is achieved.
The display device may further comprise a reflective polariser, the reflective polariser being a linear polariser, and either: said display polariser may be an output display polariser arranged on the output side of the spatial light modulator, the second additional polariser may be arranged on the same side of the spatial light modulator as the first additional polariser outside the first additional polariser, the at least one second polar control retarder may be arranged between the first additional polariser and the second additional polariser, and the reflective polariser may be arranged between the first additional polariser and the at least one second polar control retarder; or said display polariser may be an input display polariser arranged on the input side of the spatial light modulator, and the display device may further comprise an output display polariser arranged on the output side of the spatial light modulator, the second additional polariser may be arranged on the output side of the spatial light modulator, the at least one second polar control retarder may be arranged between the second additional polariser and the output display polariser, and the reflective polariser may be arranged between the output display polariser and at least one second polar control retarder. Said one of the at least one first polar control retarder and the at least one second polar control retarder may be the at least one second polar control retarder and said other of the at least one first polar control retarder and the at least one second polar control retarder may be the at least one first polar control retarder. Advantageously the reflectivity of the display device may be increased in privacy mode of operation. Security factor may be increased. In an automotive application the freedom of driver location for high security factor may be increased.
Said surface alignment layers of the at least one first polar control retarder may have pretilts having pretilt directions with components in the plane of the layer of liquid crystal material in a first pair of anti-parallel directions. Said surface alignment layers of said second polar control retarder have pretilts having pretilt directions with components in the plane of the layer of liquid crystal material in a second pair of anti-parallel directions. Advantageously high transmission efficiency is achieved. The first pair of anti-parallel directions may be parallel or orthogonal to the electric vector transmission direction of the first additional polariser. The second pair of anti-parallel directions may be parallel or orthogonal to the electric vector transmission direction of second additional polariser. Advantageously complexity and cost of manufacture may be increased. Head-on luminance may be increased.
The first pair of anti-parallel directions may be angularly offset from being parallel or orthogonal to the electric vector transmission direction of said first additional polariser by an amount having a magnitude of at most 20°. The second pair of anti-parallel directions may be angularly offset from being parallel or orthogonal to the electric vector transmission direction of said second additional polariser by an amount having a magnitude of at most 20°. Advantageously in an automotive application the freedom of driver location for high security factor may be increased.
The backlight in at least a first mode of operation may have a first luminance distribution having an output luminance profile having a full width half maximum that may be at most 40 degrees, preferably at most 30 degrees and most preferably at most 20 degrees. Advantageously reduced luminance in privacy mode of operation may be provided to achieve high security factor over a wide polar region while achieving high image luminance to a passenger.
The backlight in a second mode of operation may have a second luminance distribution having an output luminance profile having first and second maxima in luminance at first and second different polar locations with a minimum in luminance therebetween. The luminance of the minimum may be at most 25% of the luminance of the first and second maxima. Advantageously high power efficiency and image luminance may be achieved for illumination of both a passenger and a driver.
The backlight may comprise: at least one first light source arranged to provide input light; at least one second light source arranged to provide input light in an opposite direction from the at least one first light source; a waveguide arrangement comprising at least one waveguide, the waveguide arrangement being arranged to receive the input light from the at least one first light source and the at least one second light source and to cause light from the at least one first light source and the at least one second light source to exit from the waveguide arrangement by breaking total internal reflection; and an optical turning film component comprising: an input surface arranged to receive the light exiting from the waveguide arrangement through a light guiding surface of the at least one waveguide of the waveguide arrangement by breaking total internal reflection, the input surface extending across the plane; and an output surface facing the input surface, wherein the input surface may comprise an array of elongate prismatic elements. The prismatic elements each comprise a pair of elongate facets defining a ridge therebetween. Advantageously a backlight may be provided that is capable of switching illumination between a driver and passenger. In a privacy mode of operation light is directed substantially towards the passenger and substantially not to the driver. High efficiency may be achieved.
The waveguide arrangement may comprise: a waveguide extending across a plane and comprising: first and second opposed light guiding surfaces arranged to guide light along the waveguide, the second light guiding surface being arranged to guide light by total internal reflection, and first and second input ends arranged between the first and second light guiding surfaces and extending in a lateral direction between the first and second light guiding surfaces; wherein the at least one first light source may be arranged to input light into the waveguide through the first input end and the at least one second light source may be arranged to input light into the waveguide through the second input end, and the waveguide may be arranged to cause light from the at least one first light source and the at least one second light source to exit from the waveguide through one of the first and second light guiding surfaces by breaking total internal reflection. Advantageously high luminance uniformity may be achieved across each waveguide and switching between passenger and driver illumination may be achieved.
The waveguide arrangement may comprise: a first waveguide extending across a plane and comprising first and second opposed light guiding surfaces arranged to guide light along the first waveguide, the second light guiding surface being arranged to guide light by total internal reflection; and a first input end arranged between the first and second light guiding surfaces of the first waveguide and extending in a lateral direction between the first and second light guiding surfaces; wherein the at least one first light source may be arranged to input light into the first waveguide through the first input end, and the first waveguide may be arranged to cause light from the at least one first light source to exit from the first waveguide through one of the first and second light guiding surfaces by breaking total internal reflection; a second waveguide extending across the plane arranged in series with the first waveguide and comprising first and second opposed light guiding surfaces arranged to guide light along the second waveguide, the second light guiding surface being arranged to guide light by total internal reflection, and a second input end arranged between the first and second light guiding surfaces of the second waveguide and extending in a lateral direction between the first and second light guiding surfaces; wherein the at least one second light source may be arranged to input light into the second waveguide through the second input end, and the second waveguide may be arranged to cause light from the at least one second light source to exit from the second waveguide through one of the first and second light guiding surfaces by breaking total internal reflection, and wherein the first and second waveguides are oriented so that at least one first light source and at least one second light source input light into the first and second waveguides in opposite directions. Advantageously the thickness and cost of the waveguide assembly may be reduced.
The light from the first light source exits the backlight with a first angular distribution and the light from the second light source exits the backlight with a second angular distribution different from the first angular distribution. Advantageously illumination of a driver and passenger or between a snooper and user may be independently controlled. Efficiency may be improved. Security factor of privacy mode and image visibility in share mode may be improved.
The first angular distribution may be symmetrical about an axis of symmetry of the backlight and the second angular distribution may be asymmetrical about the same axis of symmetry of the backlight. Advantageously the uniformity of the display to a passenger may be increased and luminance to a driver may be increased.
The asymmetrical distribution may be to either the left or the right of an axis of symmetry of the backlight. Advantageously the display may be arranged for operation with a left hand drive or right hand drive vehicle respectively.
Said other of the at least one first polar control retarder and the at least one second polar control retarder is between the backlight and the transmissive spatial light modulator or said one of the at least one first polar control retarder and the at least one second polar control retarder is on the output side of said other of the at least one first polar control retarder and the at least one second polar control retarder. Advantageously flow artefacts may be reduced through mechanical reduction of compression of the liquid crystal retarder 301 that comprises two homeotropic layer. Further scatter at low polar angles may be reduced wherein the liquid crystal retarder with high retardance is on the output side of the liquid crystal retarder with lower retardance.
Any of the aspects of the present disclosure may be applied in any combination.
Embodiments of the present disclosure may be used in a variety of optical systems. The embodiments may include or work with a variety of projectors, projection systems, optical components, displays, microdisplays, computer systems, processors, self-contained projector systems, visual and/or audio-visual systems and electrical and/or optical devices. Aspects of the present disclosure may be used with practically any apparatus related to optical and electrical devices, optical systems, presentation systems or any apparatus that may contain any type of optical system. Accordingly, embodiments of the present disclosure may be employed in optical systems, devices used in visual and/or optical presentations, visual peripherals and so on and in a number of computing environments and automotive environments.
Before proceeding to the disclosed embodiments in detail, it should be understood that the disclosure is not limited in its application or creation to the details of the particular arrangements shown, because the disclosure is capable of other embodiments. Moreover, aspects of the disclosure may be set forth in different combinations and arrangements to define embodiments unique in their own right. Also, the terminology used herein is for the purpose of description and not of limitation.
These and other advantages and features of the present disclosure will become apparent to those of ordinary skill in the art upon reading this disclosure in its entirety.
Embodiments are illustrated by way of example in the accompanying FIGURES, in which like reference numbers indicate similar parts, and in which:
Terms related to optical retarders for the purposes of the present disclosure will now be described.
In a layer comprising a uniaxial birefringent material there is a direction governing the optical anisotropy whereas all directions perpendicular to it (or at a given angle to it) have equivalent birefringence.
The optical axis of an optical retarder refers to the direction of propagation of a light ray in the uniaxial birefringent material in which no birefringence is experienced. This is different from the optical axis of an optical system which may for example be parallel to a line of symmetry or normal to a display surface along which a principal ray propagates.
For light propagating in a direction orthogonal to the optical axis, the optical axis is the slow axis when linearly polarized light with an electric vector direction parallel to the slow axis travels at the slowest speed. The slow axis direction is the direction with the highest refractive index at the design wavelength. Similarly the fast axis direction is the direction with the lowest refractive index at the design wavelength.
For positive dielectric anisotropy uniaxial birefringent materials the slow axis direction is the extraordinary axis of the birefringent material. For negative dielectric anisotropy uniaxial birefringent materials the fast axis direction is the extraordinary axis of the birefringent material.
The terms half a wavelength and quarter a wavelength refer to the operation of a retarder for a design wavelength λ0 that may typically be between 500 nm and 570 nm. In the present illustrative embodiments exemplary retardance values are provided for a wavelength of 550 nm unless otherwise specified.
The retarder provides a phase shift between two perpendicular polarization components of the light wave incident thereon and is characterized by the amount of relative phase, Γ, that it imparts on the two polarization components; which is related to the birefringence Δn and the thickness d of the retarder by
Γ=2·π·Δn·d/λ0 eqn. 1
In eqn. 1, Δn is defined as the difference between the extraordinary and the ordinary index of refraction, i.e.
Δn=ne−no eqn. 2
For a half-wave retarder, the relationship between d, Δn, and λ0 is chosen so that the phase shift between polarization components is Γ=7. For a quarter-wave retarder, the relationship between d, Δn, and λ0 is chosen so that the phase shift between polarization components is Γ=π/2.
The term half-wave retarder herein typically refers to light propagating normal to the retarder and normal to the spatial light modulator.
Some aspects of the propagation of light rays through a transparent retarder between a pair of polarisers will now be described.
The state of polarisation (SOP) of a light ray is described by the relative amplitude and phase shift between any two orthogonal polarization components. Transparent retarders do not alter the relative amplitudes of these orthogonal polarisation components but act only on their relative phase. Providing a net phase shift between the orthogonal polarisation components alters the SOP whereas maintaining net relative phase preserves the SOP. In the current description, the SOP may be termed the polarisation state.
A linear SOP has a polarisation component with a non-zero amplitude and an orthogonal polarisation component which has zero amplitude.
A linear polariser transmits a unique linear SOP that has a linear polarisation component parallel to the electric vector transmission direction of the linear polariser and attenuates light with a different SOP. The term “electric vector transmission direction” refers to a non-directional axis of the polariser parallel to which the electric vector of incident light is transmitted, even though the transmitted “electric vector” always has an instantaneous direction. The term “direction” is commonly used to describe this axis.
Absorbing polarisers are polarisers that absorb one polarisation component of incident light and transmit a second orthogonal polarisation component. Examples of absorbing linear polarisers are dichroic polarisers.
Reflective polarisers are polarisers that reflect one polarisation component of incident light and transmit a second orthogonal polarisation component. Examples of reflective polarisers that are linear polarisers are multilayer polymeric film stacks such as DBEF™ or APF™ from 3M Corporation, or wire grid polarisers such as ProFlux™ from Moxtek. Reflective linear polarisers may further comprise cholesteric reflective materials and a quarter waveplate arranged in series.
A retarder arranged between a linear polariser and a parallel linear analysing polariser that introduces no relative net phase shift provides full transmission of the light other than residual absorption within the linear polariser.
A retarder that provides a relative net phase shift between orthogonal polarisation components changes the SOP and provides attenuation at the analysing polariser.
In the present disclosure an ‘A-plate’ refers to an optical retarder utilizing a layer of birefringent material with its optical axis parallel to the plane of the layer.
A ‘positive A-plate’ refers to positively birefringent A-plates, i.e. A-plates with a positive Δn.
In the present disclosure a ‘C-plate’ refers to an optical retarder utilizing a layer of birefringent material with its optical axis perpendicular to the plane of the layer. A ‘positive C-plate’ refers to positively birefringent C-plate, i.e. a C-plate with a positive Δn. A ‘negative C-plate’ refers to a negatively birefringent C-plate, i.e. a C-plate with a negative Δn.
‘O-plate’ refers to an optical retarder utilizing a layer of birefringent material with its optical axis having a component parallel to the plane of the layer and a component perpendicular to the plane of the layer. A ‘positive O-plate’ refers to positively birefringent O-plates, i.e. O-plates with a positive Δn.
Achromatic retarders may be provided wherein the material of the retarder is provided with a retardance Δn·d that varies with wavelength λ as
Δn·d/λ=κ eqn. 3
where K is substantially a constant.
Examples of suitable materials include modified polycarbonates from Teijin Films. Achromatic retarders may be provided in the present embodiments to advantageously minimise colour changes between polar angular viewing directions which have low luminance reduction and polar angular viewing directions which have increased luminance reductions as will be described below.
Various other terms used in the present disclosure related to retarders and to liquid crystals will now be described.
A liquid crystal cell has a retardance given by Δn·d where Δn is the birefringence of the liquid crystal material in the liquid crystal cell and d is the thickness of the liquid crystal cell, independent of the alignment of the liquid crystal material in the liquid crystal cell.
Homogeneous alignment refers to the alignment of liquid crystals in switchable liquid crystal displays where molecules align substantially parallel to a substrate. Homogeneous alignment is sometimes referred to as planar alignment. Homogeneous alignment may typically be provided with a small pre-tilt such as 2 degrees, so that the molecules at the surfaces of the alignment layers of the liquid crystal cell are slightly inclined as will be described below. Pretilt is arranged to minimise degeneracies in switching of cells.
In the present disclosure, homeotropic alignment is the state in which rod-like liquid crystalline molecules align substantially perpendicularly to the substrate. In discotic liquid crystals homeotropic alignment is defined as the state in which an axis of the column structure, which is formed by disc-like liquid crystalline molecules, aligns perpendicularly to a surface. In homeotropic alignment, pretilt is the tilt angle of the molecules that are close to the alignment layer and is typically close to 90 degrees and for example may be 88 degrees.
In a twisted liquid crystal layer, a twisted configuration (also known as a helical structure or helix) of nematic liquid crystal molecules is provided. The twist may be achieved by means of a non-parallel alignment of alignment layers. Further, cholesteric dopants may be added to the liquid crystal material to break degeneracy of the twist direction (clockwise or anti-clockwise) and to further control the pitch of the twist in the relaxed (typically undriven) state. A supertwisted liquid crystal layer has a twist of greater than 180 degrees. A twisted nematic layer used in spatial light modulators typically has a twist of 90 degrees.
Liquid crystal molecules with positive dielectric anisotropy are switched from a homogeneous alignment (such as an A-plate retarder orientation) to a homeotropic alignment (such as a C-plate or O-plate retarder orientation) by means of an applied electric field.
Liquid crystal molecules with negative dielectric anisotropy are switched from a homeotropic alignment (such as a C-plate or O-plate retarder orientation) to a homogeneous alignment (such as an A-plate retarder orientation) by means of an applied electric field.
Rod-like molecules have a positive birefringence so that ne>no as described in eqn. 2. Discotic molecules have negative birefringence so that ne<no.
Positive retarders such as A-plates, positive O-plates and positive C-plates may typically be provided by stretched films or rod-like liquid crystal molecules. Negative retarders such as negative C-plates may be provided by stretched films or discotic like liquid crystal molecules.
Parallel liquid crystal cell alignment refers to the alignment direction of homogeneous alignment layers being parallel or more typically antiparallel. In the case of pre-tilted homeotropic alignment, the alignment layers may have components that are substantially parallel or antiparallel. Hybrid aligned liquid crystal cells may have one homogeneous alignment layer and one homeotropic alignment layer. Twisted liquid crystal cells may be provided by alignment layers that do not have parallel alignment, for example oriented at 90 degrees to each other.
Transmissive spatial light modulators may further comprise retarders between the input display polariser and the output display polariser for example as disclosed in U.S. Pat. No. 8,237,876, which is herein incorporated by reference in its entirety. Such retarders (not shown) are in a different place to the passive retarders of the present embodiments. Such retarders compensate for contrast degradations for off-axis viewing locations, which is a different effect to the luminance reduction for off-axis viewing positions of the present embodiments.
A private mode of operation of a display is one in which an observer sees a low contrast sensitivity such that an image is not clearly visible. Contrast sensitivity is a measure of the ability to discern between luminances of different levels in a static image. Inverse contrast sensitivity may be used as a measure of visual security, in that a high visual security level (VSL) corresponds to low image visibility.
For a privacy display providing an image to an observer, visual security may be given as:
V=(Y+R)/(Y−K) eqn. 4
where V is the visual security level (VSL), Y is the luminance of the white state of the display at a snooper viewing angle, K is the luminance of the black state of the display at the snooper viewing angle and R is the luminance of reflected light from the display.
Panel contrast ratio is given as:
C=Y/K eqn. 5
so the visual security level may be further given as:
V=(P·Ymax+I·ρ/π)/(P·(Ymax−Ymax/C)) eqn. 6
where: Ymax is the maximum luminance of the display; P is the off-axis relative luminance typically defined as the ratio of luminance at the snooper angle to the maximum luminance Ymax; C is the image contrast ratio; ρ is the surface reflectivity; and I is the illuminance. The units of Ymax are the units of I divided by solid angle in units of steradian.
The luminance of a display varies with angle and so the maximum luminance of the display Ymax occurs at a particular angle that depends on the configuration of the display.
In many displays, the maximum luminance Ymax occurs head-on, i.e. normal to the display. Any display device disclosed herein may be arranged to have a maximum luminance Ymax that occurs head-on, in which case references to the maximum luminance of the display device Ymax may be replaced by references to the luminance normal to the display device.
Alternatively, any display described herein may be arranged to have a maximum luminance Ymax that occurs at a polar angle to the normal to the display device that is greater than 0°. By way of example, the maximum luminance Ymax may occur may at a non-zero polar angle and at an azimuth angle that has for example zero lateral angle so that the maximum luminance is for an on-axis user that is looking down on to the display device. The polar angle may for example be 10 degrees and the azimuthal angle may be the northerly direction (90 degrees anti-clockwise from easterly direction). The viewer may therefore desirably see a high luminance at typical non-normal viewing angles.
The off-axis relative luminance, P is sometimes referred to as the privacy level. However, such privacy level P describes relative luminance of a display at a given polar angle compared to head-on luminance, and in fact is not a measure of privacy appearance.
The illuminance, I is the luminous flux per unit area that is incident on the display and reflected from the display towards the observer location. For Lambertian illuminance, and for displays with a Lambertian front diffuser illuminance I is invariant with polar and azimuthal angles. For arrangements with a display with non-Lambertian front diffusion arranged in an environment with directional (non-Lambertian) ambient light, illuminance I varies with polar and azimuthal angle of observation.
Thus in a perfectly dark environment, a high contrast display has VSL of approximately 1.0. As ambient illuminance increases, the perceived image contrast degrades, VSL increases and a private image is perceived.
For typical liquid crystal displays the panel contrast C is above 100:1 for almost all viewing angles. allowing the visual security level to be approximated to:
V=1+I·ρ/(π·P·Ymax) eqn. 7
In the present embodiments, in addition to the exemplary definition of eqn. 4, other measurements of visual security level, V may be provided, for example to include the effect on image visibility to a snooper of snooper location, image contrast, image colour and white point and subtended image feature size. Thus the visual security level may be a measure of the degree of privacy of the display but may not be restricted to the parameter V.
The perceptual image security may be determined from the logarithmic response of the eye, such that
S=log10(V) eqn. 8
Desirable limits for S were determined in the following manner. In a first step a privacy display device was provided. Measurements of the variation of privacy level, P(θ) of the display device with polar viewing angle and variation of reflectivity ρ(θ) of the display device with polar viewing angle were made using photopic measurement equipment. A light source such as a substantially uniform luminance light box was arranged to provide illumination from an illuminated region that was arranged to illuminate the privacy display device along an incident direction for reflection to a viewer positions at a polar angle of greater than 0° to the normal to the display device. The variation I(θ) of illuminance of a substantially Lambertian emitting lightbox with polar viewing angle was determined by and measuring the variation of recorded reflective luminance with polar viewing angle taking into account the variation of reflectivity ρ(θ). The measurements of P(θ), r(θ) and I(θ) were used to determine the variation of Security Factor S(θ) with polar viewing angle along the zero elevation axis.
In a second step a series of high contrast images were provided on the privacy display including (i) small text images with maximum font height 3 mm, (ii) large text images with maximum font height 30 mm and (iii) moving images.
In a third step each observer (with eyesight correction for viewing at 1000 mm where appropriate) viewed each of the images from a distance of 1000 mm, and adjusted their polar angle of viewing at zero elevation until image invisibility was achieved for one eye from a position near on the display at or close to the centre-line of the display. The polar location of the observer's eye was recorded. From the relationship S(θ), the security factor at said polar location was determined. The measurement was repeated for the different images, for various display luminance Ymax, different lightbox illuminance I(θ=0), for different background lighting conditions and for different observers.
From the above measurements S<1.0 provides low or no visual security, 1.0≤S<1.5 provides visual security that is dependent on the contrast, spatial frequency and temporal frequency of image content, 1.5≤S<1.8 provides acceptable image invisibility (that is no image contrast is observable) for most images and most observers and S≥1.8 provides full image invisibility, independent of image content for all observers.
In practical display devices, this means that it is desirable to provide a value of S for an off-axis viewer who is a snooper that meets the relationship S≥Smin, where: Smin has a value of 1.0 or more to achieve the effect that the off-axis viewer cannot perceive the displayed image; Smin has a value of 1.5 or more to achieve the effect that the displayed image is invisible, i.e. the viewer cannot perceive even that an image is being displayed, for most images and most observers; or Smin has a value of 1.8 or more to achieve the effect that the displayed image is invisible independent of image content for all observers.
In comparison to privacy displays, desirably wide angle displays are easily observed in standard ambient illuminance conditions. One measure of image visibility is given by the contrast sensitivity such as the Michelson contrast which is given by:
M=(Imax−Imin)/(Imax+Imin) eqn. 9
and so:
M=((Y+R)−(K+R))/((Y+R)+(K+R))=(Y−K)/(Y+K+2·R) eqn. 10
Thus the visual security level (VSL), V is equivalent (but not identical to) 1/M. In the present discussion, for a given off-axis relative luminance, P the wide angle image visibility, W is approximated as
W=1/V=1/(1+I·ρ/(π·P·Ymax)) eqn. 11
The above discussion focusses on reducing visibility of the displayed image to an off-axis viewer who is a snooper, but similar considerations apply to visibility of the displayed image to the intended user of the display device who is typically on-axis. In this case, decrease of the level of the visual security level (VSL) V corresponds to an increase in the visibility of the image to the viewer. During observation S<0.1 may provide acceptable visibility of the displayed image. In practical display devices, this means that it is desirable to provide a value of S for an on-axis viewer who is the intended user of the display device that meets the relationship S≤Smax, where Smax has a value of 0.1.
In the present discussion the colour variation Δε of an output colour (uw′+Δu′, vw′+Δv′) from a desirable white point (uw′, vw′) may be determined by the CIELUV colour difference metric, assuming a typical display spectral illuminant and is given by:
Δε=(Δu′2+Δv′2)1/2 eqn. 12
The structure and operation of various directional display devices will now be described. In this description, common elements have common reference numerals. It is noted that the disclosure relating to any element applies to each device in which the same or corresponding element is provided. Accordingly, for brevity such disclosure is not repeated.
A switchable privacy display such as for a vehicle will now be described.
Display device 100 is arranged in a passenger information display (PID) location, (on the right hand side of the vehicle for Left Hand Drive), with light rays 445, 447 output to the user 45 and user 47 respectively.
In a first mode of operation that is the privacy mode the display device 100 is arranged for viewing by the front passenger 45 near to an on-axis 199 location, and to inhibit viewing by the driver 47.
It is desirable that the passenger 45 may view information such as entertainment without the image causing distraction to the driver 47, that is the privacy mode refers to a low driver distraction mode. This mode is in comparison with a mode in which the passenger display turns off when the vehicle is in motion to prevent driver distraction. More specifically to minimise the visibility to the driver 47 of distracting images at both the nominal driver position and when the driver leans across towards the display while driving, it is desirable to maximise the security factor S at angles α from the optical axis 199 of greater than 30° and preferably greater than 25° in the direction from the optical axis 199 towards the driver 47. Further it is desirable to achieve a high security factor, S for polar angles at least at angles R from the optical axis 199.
Further in a low stray light function of the privacy mode, it may be desirable to provide an image to the passenger 45 with desirable luminance while reducing the luminance to reflecting and scattering surfaces within the vehicle. Advantageously the brightness of internal surfaces of the vehicle 650 may be reduced during night time operation, reducing driver distraction. Further, increased area displays may be provided while maintaining desirably low levels of stray illumination within the vehicle 650 cabin.
In a second mode that is the share mode, the display device 100 is arranged for viewing by driver 47 in an off-axis location. Such use may be for occasions when viewing the display content is safe such as when the vehicle is stationary or the content is appropriate such as map or instrument data.
An illustrative structure that can achieve the desirable characteristics of the display device 100 of
The display device 100 comprises a backlight 20 arranged to output light 444, 446; a transmissive spatial light modulator 48 arranged to receive output light from the backlight 20; a display polariser 210 arranged on a side of the spatial light modulator 48, the display polariser 210 being a linear polariser.
A first additional polariser 318A is arranged on the same side of the spatial light modulator 48 as the display polariser 210, the first additional polariser 318A being a linear polariser; at least one first polar control retarder 300A arranged between the first additional polariser 318A and the display polariser 210, a second additional polariser 318B, the second additional polariser 318B being a linear polariser; and at least one second polar control retarder 300B.
In the embodiment of
In the embodiment of
In the present disclosure, the spatial light modulator 48 may comprise a liquid crystal display comprising substrates 212, 216, and liquid crystal layer 214 having red, green and blue pixels 220, 222, 224. The spatial light modulator 48 has an input display polariser 210 and an output display polariser 218 on opposite sides thereof. The output display polariser 218 is arranged to provide high extinction ratio for light from the pixels 220, 222, 224 of the spatial light modulator 48. Typical polarisers 210, 218 may be absorbing polarisers such as dichroic polarisers such as an iodine polariser on stretched PVA.
The backlight apparatus 20 comprises a rear reflector 3 and a waveguide arrangement comprising first and second waveguides 1A, 1B, and optical turning film component 50 and arranged to receive light exiting from the waveguides 1A, 1B and direct through the spatial light modulator 48.
The waveguides 1A, 1B each comprise input ends 2A, 2B arranged between first and second light guiding surfaces 6A, 8A and 6B, 8B respectively.
Light source arrays 15A, 15B are arranged to input input light into the input sides 2A, 2B of waveguides 1A, 1B respectively.
Optical stack 5 may comprise diffusers, and other known optical backlight structures such as recirculating polarisers (not shown). Asymmetric diffusers, that may comprise asymmetric surface relief features for example, may be provided in the optical stack 5 with increased diffusion in the elevation direction in comparison to the lateral direction may be provided. Advantageously image uniformity may be increased.
Display apparatus 100 further comprises additional polarisers 318A, 318B arranged between the spatial light modulator 48 and the input display polariser 210. Polarisers 318A, 318B, 318 may be absorbing dichroic polarisers such as an iodine polariser on stretched PVA.
The display input polariser 210 and the additional polarisers 318A, 318B have electric vector transmission directions 211, 319A, 319B respectively that are parallel, and orthogonal to the output polariser 218 transmission direction 219.
Polar control retarder 300A is arranged between the display polariser 210 and the first additional polariser 318A, the polar control retarder 300A including a switchable liquid crystal retarder 301A comprising a layer 214A of liquid crystal material. Each of the at least one first polar control retarder 300A and the at least one second polar control retarder 300B comprises a respective switchable liquid crystal retarder 301A, 301B comprising a layer 314A, 314B of liquid crystal material 414A, 414B and two surface alignment layers 417AA, 417AB and 417BA, 417BB disposed adjacent to the layer 314A, 314B of liquid crystal material 414A, 414B and on opposite sides thereof.
Polar control retarder 300B is arranged between the additional polarisers 318A, 318B, the polar control retarder 300B including a switchable liquid crystal retarder 301B comprising a layer 214B of liquid crystal material.
More generally polar control retarders 300A, 300B comprise: (i) a switchable liquid crystal retarder 301A, 301B comprising a layer 314A, 314B of liquid crystal material arranged between transparent support substrates 312A, 312B, 316A, 316B; and (ii) at least one passive compensation retarder 330A, 330B.
The backlight 20 comprises a pair of waveguides 1A, 1B and respective aligned light sources 15A, 15B that are arranged to provide output illumination into nominal directions 445, 447 respectively directed towards the passenger 45 and driver 47 respectively. The structure and operation of the backlight 20 will be described further with reference to
The polar distribution of the light output of rays 445, 447 towards passenger 45 and driver 47 respectively may be further modified by diffusers including diffuser 5 arranged after the turning film 50 of the backlight 20.
The structure of the display device 100 of
Alignment orientations of the optical stack of the privacy display device 100 of
For the light source inputs 15A, 15B of
The structure of liquid crystal retarders 301A, 301B will be described in further detail with respect to
In the illustrative embodiment of
Liquid crystal retarder 301B further comprises an alignment layer 417BB that provides homeotropic alignment in the adjacent liquid crystal material 414B with an alignment component 419BBp in the plane of the alignment layer 417BB that is inclined at an angle θBB that provides anti-parallel alignment of component 419BBp relative to the alignment component 419BAp.
Passive C-plate retarder 330B has an optical axis direction 331B that is out of the plane of the retarder 330B.
Additional polariser 318A has a horizontal polariser transmission direction 319B that is parallel to the direction 318B.
Liquid crystal retarder 301A comprises an alignment layer 417AA that provides homogenous alignment in the adjacent liquid crystal material 414A with an alignment component 419AAp in the plane of the alignment layer 417AA that is inclined at an angle of θAA to the horizontal direction (x-axis); and an alignment layer 417AB that provides homogeneous alignment in the adjacent liquid crystal material 414A with an alignment component 419ABp in the plane of the alignment layer 417AB that is inclined at an angle of θAA to the horizontal direction such that the component 419ABp is anti-parallel to the component 419AAp.
Passive A-plate retarder 330AB has an optical axis direction at 45° (measured anticlockwise from the horizontal direction) and passive A-plate retarder 330AA has an optical axis direction at 45°. Crossed A-plate retarders 330AA, 330AB provide an asymmetric transmission variation with lateral angle. Advantageously the sequence of the crossed A-plate retarders is provided to maximise off-axis luminance reduction in the direction towards the driver 47 of
In other embodiments (not illustrated) the A-plate passive retarders 330AA, 330AB may be rotated clockwise by the angle 90°−θA from the respective orientation 331AA, 331AB.
The display polariser comprises the input polariser 210 of the spatial light modulator 48 with electric vector transmission direction 211 that is parallel to the electric vector transmission direction of the additional polarisers 318A, 318B. Advantageously transmission efficiency is increased. The arrangement of
The spatial light modulator 48 further comprises a display output polariser 218. The output polarisation direction 219 of
Alternative arrangements of polariser 210, 218, 318A, 318B electric vector transmission directions 211, 219, 319A, 319B will now be described.
In the present embodiments the polarisers 318A, 318B may have electric vector transmission axes that are parallel to or orthogonal to the y-axis. Embodiments such as
In the illustrative example of
In alternative embodiments the electric vector transmission directions of one or more of the polarisers 210, 218, 318A, 318B may be provided at angles other than 0 degrees or 90 degrees wherein a further half waveplate 208 is arranged such that the combination of half waveplate and respective polariser provides maximum transmission through the optical stack of the display device 100.
The alternative embodiment of
A control system for the privacy display device 100 of
The display device 100 of
Control of the polar control retarders 300A, 300B is achieved by means of drivers 350A, 350B to change the operating voltage across the liquid crystal layers 314A, 314B. Controller 352 is provided to control the drivers 350A, 350B and controller 354 that further controls the driving of light sources 15, 17. In other words controller 352 is provided to control the drivers 350A, 350B that provide a controlled electric field across retarder 314A, 314B electrodes 413A, 415A and 413B, 415B respectively.
Controller 354 controls the driving of light sources 15A, 15B as described elsewhere herein.
Further sensors (not shown) may be provided and the privacy display control system of
The display device 100 is arranged to display an image and capable of operating in at least a share mode and a privacy mode, wherein in the privacy mode the privacy function is provided and the visibility of the image to an off-axis viewer is reduced compared to the share mode and the visibility of the image to the primary user in an on-axis position remains visible in both the privacy and share modes. The control system 350, 352, 354 selectively operates the display device 100 in the share mode or the privacy mode for at least one region of the displayed image, typically the entire displayed image. At least part of the electrodes 413A, 415A and 413B, 415B may be patterned so that some electrode pattern regions operate in privacy mode and other parts in share mode. Separate drivers 350 may be provided for each respective electrode patterned region.
Illustrative polar profiles of output from an illustrative backlight 20 of
As illustrated in
Advantageously most light is directed towards the passenger 45 in direction 445 and high suppression of luminance is achieved in the driver 47 in direction 447. High power efficiency for passenger 45 illumination is achieved. However, such an illumination profile is not sufficient to achieve desirable security factor, S as will be described further hereinbelow.
The backlight 20 in a second mode of operation has a second luminance distribution having an output luminance profile having first and second maxima 320, 322 in luminance at first and second different polar locations 445, 447 with a minimum 324 in luminance therebetween. The luminance of the minimum 324 is desirably at most 25% of the luminance of the first and second maxima.
The profile of
Advantageously a display device 100 that may be observed by both driver 47 and passenger 45 may be provided.
The embodiment of
The polar profile of output from an illustrative display device 100 of TABLE 1 and backlight 20 profile of
Considering TABLE 1 in respect of the second polar control retarder 300B, each of the surface alignment layers 417BA, 417BB is arranged to provide homeotropic alignment in the adjacent liquid crystal material 414B. In respect of the first polar control retarder 300A, both of the surface alignment layers 417AA, 417AB are arranged to provide homogenous alignment in the adjacent liquid crystal material 414A.
In an alternative embodiment as will be described further hereinbelow in respect of the first polar control retarder 300A, both of the surface alignment layers 417AA, 417AB are arranged to provide homeotropic alignment in the adjacent liquid crystal material 414A; and in respect of the second polar control retarder 300B, each of the surface alignment layers 417BA, 417BB is arranged to provide homogeneous alignment in the adjacent liquid crystal material 414B.
In other words, in respect of one of the at least one first polar control retarder 300A and the at least one second polar control retarder 300B, both of the surface alignment layers 417AA, 417AB or 417BA, 417BB respectively are arranged to provide homogenous alignment in the adjacent liquid crystal material. In respect of the other of the at least one first polar control retarder 300A and the at least one second polar control retarder 300B, both of the surface alignment layers 417AA, 417AB or 417BA, 417BB respectively are arranged to provide homeotropic alignment in the adjacent liquid crystal material.
The switchable liquid crystal retarder 301A, 301B of said one of the at least one first polar control retarder 300A and the at least one second polar control retarder 300B has a retardance for light of a wavelength of 550 nm having a first retardance value and the switchable liquid crystal retarder 301A, 301B of said other of the at least one first polar control retarder 300A and the at least one second polar control retarder 300B has a retardance for light of a wavelength of 550 nm has a second retardance value, the first retardance value and the second retardance value being different, the magnitude of the difference between the first retardance value and the second retardance value being at least 10% of the average of the first retardance value and the second retardance value.
In alternative embodiments, the magnitude of the difference between the first retardance value and the second retardance value is at least 25% of the average of the first retardance value and the second retardance value. Said other of the at least one first polar control retarder 300A and the at least one second polar control retarder 300B is between the backlight 20 and the transmissive spatial light modulator 48. Said one of the at least one first polar control retarder 300A and the at least one second polar control retarder 300B is on the output side of said other of the at least one first polar control retarder 300A and the at least one second polar control retarder 300B.
The properties of the first and second polar control retarders 300A, 300B of TABLE 1 will now be described further. The first retardance value for the layer 314A of liquid crystal material 414A is greater than the second retardance value for the layer 314B of liquid crystal material 414B wherein the first retardance value is in a range from 500 nm to 2000 nm, preferably in a range from 700 nm to 1500 nm, and the second retardance value is in a range from 350 nm to 900 nm, preferably in a range from 500 nm to 850 nm.
The first polar control retarder 300A further comprises a pair of passive uniaxial retarders 330A, 330B having optical axes 331A, 331B in the plane of the retarders 330A, 330B respectively that are crossed wherein each passive retarder 330AA, 330AB has a retardance for light of a wavelength of 550 nm in a range from 300 nm to 1500 nm, preferably in a range from 500 nm to 1200 nm.
The second polar control retarder 300B comprises a passive uniaxial retarder 330B having its optical axis 331B perpendicular to the plane of the retarder 330B and has a retardance for light of a wavelength of 550 nm in a range from −250 nm to −850 nm, preferably in a range from −400 nm to −800 nm.
The in plane alignment directions will now be considered. Said surface alignment layers 417AA, 417AB of the at least one first polar control retarder 300A has pretilts 419AA, 419AB having pretilt directions with components 419AAp, 419ABp in the plane of the layer 314A of liquid crystal material 414A in a first pair 420A of anti-parallel directions as described elsewhere herein and provided by angle θAA for 419AAp of 270° and angle θAB for 419ABp of 90°.
Considering
Considering
Said surface alignment layers 417BA, 417BB of the at least one second polar control retarder 300B has pretilts 419BA, 419BB having pretilt directions with components 419BAp, 419BBp in the plane of the layer 314B of liquid crystal material 414B in a second pair 420B of anti-parallel directions as described elsewhere herein and provided by angle θBA for 419BAp and angle θBB for 419BBp. The second pair 420B of anti-parallel directions is parallel or orthogonal to the electric vector transmission direction 319B of the second additional polariser 318B.
The retardance of the LC layer 314A of polar control retarder 300A is higher than the retardance of LC layer 314B of polar control retarder 300B to achieve the different polar location of transmission minima. The profile achieves high luminance extinction at higher viewing angles, however high transmission closer to the optical axis.
Thus, the multiplicative effect of the contributions from each of the components described in
Polar profiles for the polar control retarders 300A, 300B of TABLE 1 will now be described.
In most of the headbox (driver viewing) region 347, a desirably high security factor S is provided and low driver distraction is advantageously achieved. However in part of headbox region 347, particularly where the driver 47 leans towards the display device 100 and is close to the angle α of
In an alternative illustrative embodiment the first and second polar control retarders 300A, 300B are provided as described in TABLE 2. In comparison to TABLE 1 the polar control retarder 300A with homogeneous alignment layers 417AA, 417AB comprises a C-plate 330A rather than crossed A-plates 330AA, 330AB.
The properties of the first and second polar control retarders 300A, 300B of TABLE 2 will now be described further. The retardance properties of the first and second liquid crystal retarders 301A, 301B and of the second passive retarder 330B of TABLE 2 is the same as for TABLE 1. The passive retarder 330A comprises a passive uniaxial retarder with its optical axis perpendicular to the plane of the retarder 330A and has a retardance for light of a wavelength of 550 nm in a range from −300 nm to −1700 nm, preferably in a range from −500 nm to −1200 nm.
The thickness of the optical stack is advantageously reduced. As will be described further hereinbelow, in comparison to the illustrative embodiment of TABLE 1, the colour of the image provided to the driver in share mode may advantageously have less colour difference across the polar region than is achieved by the A-plate retarders 330AA, 330AB of TABLE 3.
It may be desirable to further increase the security factor S in the region 347 close to the angle α. In an alternative embodiment the first and second polar control retarders 300A, 300B are provided as described in TABLE 3.
The retardance of each of the polar control retarders 300A, 300B is the same as provided in TABLE 1. The in plane alignment directions of TABLE 3 will now be considered.
Said surface alignment layers 417AA, 417AB of the at least one first polar control retarder 300A has pretilts 419AA, 419AB having pretilt directions with components 419AAp, 419ABp in the plane of the layer 314A of liquid crystal material 414A in a first pair 420A of anti-parallel directions as described elsewhere herein and provided by angle θAA for 419AAp and angle θAB for 419ABp. The first pair 420A of anti-parallel directions is angularly offset by angle ϕA from being parallel or orthogonal to the electric vector transmission direction 319A of said first additional polariser 318A by an amount having a magnitude of at most 20°.
Said surface alignment layers 417BA, 417BB of the at least second polar control retarder 300B has pretilts 419BA, 419BB having pretilt directions with components 419BAp, 419BBp in the plane of the layer 314B of liquid crystal material 414B in a second pair 420B of anti-parallel directions as described elsewhere herein and provided by angle θBA for 419BAp and angle θBB for 419BBp. The second pair 420B of anti-parallel directions is angularly offset by angle ϕB from being parallel or orthogonal to the electric vector transmission direction 319B of said second additional polariser 318B by an amount having a magnitude of at most 20°.
In comparison to TABLE 1, TABLE 3, alignment layers 417AA, 417AB, 417BA, 417BB are arranged to provide alignment directions 419AAp, 419ABp at angles θA, θB respectively of 85° or 265° to the horizontal and are thus rotated in the plane of the respective alignment layers 417.
Illustrative performance in share mode will now be described.
It would be desirable to provide a share mode of operation with reduced colour variations and reduced power consumption. In an alternative illustrative embodiment the first and second polar control retarders 300A, 300B are provided as described in TABLE 4. In comparison to TABLE 3 the A-plate retarders 330AA, 330AB are replaced by a C-plate retarder 330A.
The properties of the first and second polar control retarders 300A, 300B of TABLE 4 will now be described further. The first retardance value for the layer 314A of liquid crystal material 414A is less than the second retardance value for the layer 314B of liquid crystal material 414B wherein the first retardance value is in a range from 350 nm to 1000 nm, preferably in a range from 500 nm to 900 nm, and the second retardance value is in a range from 650 nm to 2800 nm, preferably in a range from 1000 nm to 2000 nm. The passive retarder 330A has its optical axis perpendicular to the plane of the retarder 330A and has a retardance for light of a wavelength of 550 nm in a range from −250 nm to −800 nm, preferably in a range from −300 nm to −700 nm. The second polar control retarder 300B comprises a passive uniaxial retarder 330B having its optical axis perpendicular to the plane of the retarder and has a retardance for light of a wavelength of 550 nm in a range from −400 nm to −2400 nm, preferably in a range from −700 nm to −1700 nm.
In an alternative illustrative embodiment the first and second polar control retarders 300A, 300B are provided as described in TABLE 5. In comparison to TABLE 1 the polar control retarder 300A with homogeneous alignment layers 417AA, 417AB has a lower retardance than the polar control retarder 300B with homeotropic alignment layers 417BA, 417BB.
The properties of the first and second polar control retarders 300A, 300B of TABLE 5 will now be described further. The first retardance value for the layer 314A of liquid crystal material 414A is less than the second retardance value for the layer 314B of liquid crystal material 414B wherein the first retardance value is in a range from 350 nm to 1000 nm, preferably in a range from 500 nm to 900 nm, and the second retardance value is in a range from 650 nm to 2800 nm, preferably in a range from 1000 nm to 2000 nm.
The second polar control retarder 300B comprises a passive uniaxial retarder 330B having its optical axis perpendicular to the plane of the retarder and has a retardance for light of a wavelength of 550 nm in a range from −400 nm to −2400 nm, preferably in a range from −700 nm to −1700 nm.
The at least one passive compensation retarder of the first polar control retarder 300A comprises a pair of passive retarders 330A, 330B having optical axes 331A, 331B in the plane of the retarders 330A, 330B that are crossed and each have a retardance for light of a wavelength of 550 nm in a range from 300 nm to 900 nm, preferably in a range from 400 nm to 800 nm.
Arrangements of liquid crystal alignment for use in the retarders 300A, 300B of the embodiments described elsewhere herein will now be described in further detail.
Electrodes 413, 415 are arranged to apply a voltage from driver 350 across the liquid crystal material 414 in the layer 314. In a first driven state the liquid crystal molecules are arranged to provide no phase modification to input polarisation state in a normal direction to the polar control retarder and modified phase to an input polarisation state in directions at an angle to the normal direction to the polar control retarder 300. Such a driven state may be provided for privacy mode operation.
In a second driven state the liquid crystal molecules are arranged to provide no phase modification to input polarisation state in a normal direction to the polar control retarder and modified phase to an input polarisation state in directions at an angle to the normal direction to the polar control retarder 300. Such a driven state may be provided for public (or share) mode operation.
The pretilt directions 419A, 419B of the alignment layers have a component in the plane of the alignment layers 417A, 417B that are antiparallel. The pretilt directions 419A, 419B refer to the alignment of the liquid crystal molecules 421 that are adjacent to said layers. The components 419Ap and 419Bp are the in-plane components and are anti-parallel to each other. The pretilt angle is the angle between the directions 419A and 419Ap, and between directions 419B and 419Bp respectively.
The components 419Ap, 419Bp are oriented in a first direction in the plane of the alignment layers, that is parallel to the y-axis.
In the present disclosure crossed A-plates refers to a pair of passive uniaxial retarders having optical axes in the plane of the retarders that are crossed, as illustrated by retarders 330A, 330B in
In the present embodiments one of the polar control retarders 300A, 300B may comprise the polar control retarder 300 of
In respect of said other (with alignment layers that are of the same type) of the at least one first polar control retarder and the at least one second polar control retarder, both of the surface alignment layers may be arranged to provide homeotropic alignment in the adjacent liquid crystal material. Advantageously reduced voltage and power consumption may be provided in share mode in comparison to arrangements in which both alignment layers have homogeneous alignment.
In respect of said other (with alignment layers that are of the same type) of the at least one first polar control retarder and the at least one second polar control retarder, both of the surface alignment layers may be arranged to provide homogeneous alignment in the adjacent liquid crystal material. Advantageously the visibility of defects to applied pressure may be reduced in comparison to arrangements in which both alignment layers have homeotropic alignment.
Operation of polar control retarders between parallel polarisers is described further in U.S. Pat. No. 10,126,575 and in U.S. Patent Publ. No. 2019-0086706, both of which are herein incorporated by reference in their entireties. The operation of the plural polar control retarders of the present embodiments in a share mode of operation will now be described.
The structure of polar control retarders 300 with rotated alignment layers for improved security factor for a driver 47 leaning towards the privacy display device 100, such as illustrated with respect to
The other of the surface alignment layers 417BB is arranged to provide homogeneous alignment in the adjacent liquid crystal material 414B. The other of the surface alignment layers 417BB has said pretilt having a pretilt direction 419BB with a component 419BBp in the plane of the layer 314B of liquid crystal material 414B that is at a non-zero angle θBB to the electric vector transmission or absorption directions 319A, 319B of the additional polarisers 318A, 318B. Thus each of the surface alignment layers 417BA, 417BB have pretilts having pretilt directions 419BA, 419BB with components 419BAp, 419BBp in the plane of the layer 314 of liquid crystal material 414B that are at acute non-zero angles θBA, θBB to the electric vector transmission or absorption directions 319A, 319B of the additional polarisers 318A, 318B which are parallel.
The non-zero angles θB are from the vertical direction (y-axis) and are equivalent to the angles 90−θA, 90−θB measured from the horizontal direction (x-axis) and referred to elsewhere herein.
More generally, at least one of the alignment layers 417BA, 417BB may have pretilt directions 419BA, 419BB with components 419BAp, 419BBp in the plane of the layer 314B of liquid crystal material 414B that are at acute non-zero angles θBA, θBB to at least one of the electric vector transmission or absorption directions 319A, 319B of the additional polarisers 318A,318B.
In this example, the acute non-zero angles θB are present across the entirety of the display device 100. This is also the case in all embodiments where not otherwise specified. However, more generally the acute non-zero angles θB are present across any part of the display device 100, in which case the technical effects described hereinabove are achieved for that part.
In the present embodiments the polarisers 318A, 318B, 210 have transmission or absorption axes 319A, 319B, 211 that are parallel to or orthogonal to the y-axis. In embodiments which describe polarisers with horizontal electric vector transmission direction 319A, 319B, 211 then vertical transmission direction 319A, 319B, 211 may be assumed to have identical or similar performance, the selection depending on the desirable polariser direction for the spatial light modulator polariser 210, 218 electric vector transmission directions 211, 219.
Various alternatives for alignment directions of polarisers and liquid crystal alignment directions will now be illustrated.
In the embodiments of
Considering
Alignment layer 417BA has a pretilt direction 419BA that has a component direction 419BAp in the plane of the alignment layer 417BA that is a vector inclined at angle θBA anti-clockwise from the easterly direction (positive x direction). The component direction 419BAp is inclined at a rotation angle $ to the direction 319B.
Alignment layer 417BB has a pretilt direction 419BB that has a component direction 419BBp in the plane of the alignment layer 417BB that is a vector inclined at angle θBB anti-clockwise from the easterly direction that is anti-parallel to the component 419BAp. The component direction 419BBp is also inclined at the same rotation angle ϕ to the direction 319 as for the component 419BBp.
Considering
Alignment layer 417BA has a pretilt direction 419BA that has a component direction 419BAp in the plane of the alignment layer 417BA that is a vector inclined at angle θBA anti-clockwise from the easterly direction. The component direction 419BAp is inclined at a rotation angle ϕ to the direction 317B and a rotation angle 90−ϕ degrees to the direction 319B.
Alignment layer 417BB has a pretilt direction 419BB that has a component direction 419BBp in the plane of the alignment layer 417BB that is a vector inclined at angle θBB anti-clockwise from the easterly direction that is anti-parallel to the component 419BAp. The component direction 419BBp is also inclined at the same rotation angle ϕ to the direction 317B as for the component 419BBp.
More generally, said surface alignment layers 417AA, 417AB of the first polar control retarder 300A have pretilts 419AA, 419AB respectively having pretilt directions with components 419AAp, 419ABp in the plane of the layer of liquid crystal material 314A in a first pair 420A of anti-parallel directions. Said surface alignment layers 417BA, 417BB of the second polar control retarder 300B have pretilts 419BA, 419BB respectively having pretilt directions with components 419BAp, 419BBp in the plane of the layer of liquid crystal material 314B in a second pair 420B of anti-parallel directions.
Referring to the illustrative embodiment of
Rotated alignment orientations will now be described in further detail.
Referring to the embodiment of
Referring to the embodiment of
In comparison to the embodiments of
The structure and operation of various alternative backlights 20 that provide desirable illumination characteristics for the switchable privacy display device 100 of the present embodiments will now be described further.
The backlight 20 comprises: at least one first light source 15A arranged to provide input light 444A and at least one second light source 15B arranged to provide input light 444B in an opposite direction from the at least one first light source 15A. A waveguide arrangement 11 comprises waveguides 1A, 1B, the waveguide arrangement 11 being arranged to receive the input light 444A, 444B from the at least one first light source 15A and the at least one second light source 15B and to cause light 444A, 444B from the at least one first light source 15A and the at least one second light source 15B to exit from the waveguide arrangement 11 by breaking total internal reflection.
The waveguide arrangement 11 comprises: a first waveguide 1A extending across a plane and comprising first and second opposed light guiding surfaces 6A, 8A arranged to guide light along the first waveguide 1A, the second light guiding surface 8A being arranged to guide light by total internal reflection; and a first input end 2A arranged between the first and second light guiding surfaces 6A, 8A of the first waveguide 1A and extending in a lateral direction between the first and second light guiding surfaces 6A, 8A. The at least one first light source 15A is arranged to input light 444A into the first waveguide 1A through the first input end 2A, and the first waveguide 1A is arranged to cause light from the at least one first light source 15A to exit from the first waveguide 1A through one of the first and second light guiding surfaces 6A, 8A by breaking total internal reflection. A second waveguide 1B extending across the plane is arranged in series with the first waveguide 1A and comprises first and second opposed light guiding surfaces 6B, 8B arranged to guide light along the second waveguide 1B, the second light guiding surface 8B being arranged to guide light by total internal reflection, and a second input end 2B arranged between the first and second light guiding surfaces 6B, 8B of the second waveguide 1B and extending in a lateral direction between the first and second light guiding surfaces 6B, 8B. The at least one second light source 15B is arranged to input light into the second waveguide 1B through the second input end 2B, and the second waveguide 1B is arranged to cause light 444B from the at least one second light source 15B to exit from the second waveguide 1B through one of the first and second light guiding surfaces 6B, 8B by breaking total internal reflection, and wherein the first and second waveguides 1A, 1B are oriented so that at least one first light source 15A and at least one second light source 15B input light 444A, 444B into the first and second waveguides 1A, 1B in opposite directions.
An optical turning film component 50 comprises: an input surface 56 arranged to receive the light 444A, 444B exiting from the waveguide arrangement 11 through a light guiding surface of the at least one waveguide 1A, 1B of the waveguide arrangement by breaking total internal reflection, the input surface 56 extending across the plane; and an output surface 58 facing the input surface, wherein the input surface 56 comprises an array of elongate prismatic elements 52. The prismatic elements each comprise a pair of elongate facets 52 defining a ridge 54 therebetween.
The backlight 20 of
The operation of the backlight 20 of
Each waveguide 1A, 1B extends across a plane and comprises: first and second opposed light guiding surfaces 6A, 8A and 6B, 8B arranged to guide light along the respective optical waveguide 1A, 1B, being arranged to guide light by total internal reflection.
First and second input ends 2A, 4A and 2B, 4B are arranged between the first and second light guiding surfaces 6, 8 and extend in a lateral direction between the first and second light guiding surfaces 6, 8.
The light sources 15A, 15B are arranged to input light 445, 447 into the waveguide 1 through the first input end 2A, 2B.
Waveguides 1A, 1B comprise surface relief features that are arranged to leak some of the guiding light either towards the rear reflector 3 or towards the light turning film 50 that comprises an array of prisms 52 facing the output of the waveguides 1A, 1B. Each waveguide 1A,1B comprise a surface relief 30 arranged on the first side 6A, 6B that may comprise prism surfaces 32, 33. Further the second sides 8A, 8B may further comprise surface relief 31 that may comprise elongate features such as illustrated in
The waveguides 1A,1B are arranged to cause light 445, 447 from the light sources 15A, 15B to exit from the waveguides 1A, 1B through one of the first and second light guiding surfaces 6A,8A and 6B,8B respectively by breaking total internal reflection.
Referring also to
Light rays 444A are refracted at the first prism surface 53A and reflected at the second prism surface 53B of the respective prism 52 of the turning film component 50. By means of design of the surface profiles of light extraction features of the waveguide 1A and surface of the first and second prism surfaces 53A, 53B the nominal direction of output light 445 may be directed in directions near to the normal 199 of the display device 100 with polar luminance profile as will be described hereinbelow.
The luminous flux of the light sources 15A determine the luminance of the polar light output distribution of output light 445. Light sources 15A provide control of the luminance for passenger 45 illumination.
Light source 15B such as an array of LEDs is arranged to input light rays 444B into the waveguide 1B from an input side 2B that faces the input side 2A of the first waveguide 1A. Such light rays 444B are guided within the waveguide 1B and are extracted outside of the waveguide 1B by light extraction features on the surface of the waveguide 1B. Light rays 444B pass either by reflection at rear reflector 3, passing through waveguides 1B, 1A onto the prisms 52 of the light turning film 50, or are passed through waveguide 1A onto the prisms 52 of the light turning film 50.
Light rays 444B are refracted at the second prism surface 53B and reflected at the first prism surface 53A of the respective prism 52. By means of design of the surface profiles of light extraction features of the waveguide 1B and surface profiles of the first and second prism surfaces 53A, 53B the nominal direction of output light 447 may be directed in directions away from the normal 199 of the display device 100 towards the nominal driver location with polar luminance profile as will be described hereinbelow. The luminous flux of the light sources 15B determine the luminance of the polar light output distribution of output light 447.
The optical turning film component 50 will now be described in more detail.
The optical turning film component 50 comprises: an input surface 56 arranged to receive the light exiting from a waveguide 1 through a light guiding surface 6, 8 of the waveguide 1 by breaking total internal reflection, the input surface 56 extending across the plane; and an output surface 58 facing the input surface 56, wherein the input surface comprises an array of elongate prismatic elements 52 comprising ridges 54.
Angles ϕA, ϕB of prism surfaces 53A, 53B are provided to direct the nominal light output from waveguides 1A, 1B to directions 445, 447 by refraction and reflection at surfaces 53A, 53B. Advantageously desirable illumination directions such as illustrated in
Examples of waveguide structures for use in the waveguides 1A, 1B will now be described in further detail.
Surface relief features 30 are illustrated on both sides 6, 8 of the waveguide 1 such as illustrated in
In comparison to the waveguide 1 of
An alternative backlight 20 to the arrangements of
The backlight 20 comprises: at least one first light source 15A arranged to provide input light 444A and at least one second light source 15B arranged to provide input light 444B in an opposite direction from the at least one first light source 15A. The waveguide arrangement 11 comprises waveguide 1, the waveguide arrangement 11 being arranged to receive the input light 444A, 444B from the at least one first light source 15A and the at least one second light source 15B and to cause light 444A, 444B from the at least one first light source 15A and the at least one second light source 15B to exit from the waveguide arrangement 11 by breaking total internal reflection. In comparison to the waveguide arrangement 11 of
The operation of the backlight 20 of
The waveguide 1 extends across a plane and comprising: first and second opposed light guiding surfaces 6, 8 arranged to guide light along the optical waveguide 1, the second light guiding surface 8 being arranged to guide light by total internal reflection.
First and second input ends 2, 4 are arranged between the first and second light guiding surfaces 6, 8 and extend in a lateral direction between the first and second light guiding surfaces 6, 8.
The at least one first light source 15A is arranged to input light 445 into the waveguide 1 through the first input end 2 and the at least one second light source 15B is arranged to input light 447 into the waveguide 1 through the second input end 4.
The waveguide 1 is arranged to cause light 445, 447 from the at least one first light source 15A and the at least one second light source 15B to exit from the waveguide 1 through one of the first and second light guiding surfaces 6, 8 by breaking total internal reflection.
The optical turning film component 50 has a structure and operation similar to that described with reference to
The waveguide 1 is arranged to cause light 445, 447 from the at least one first light source 15 and the at least one second light source 15B to exit from the waveguide 1 with angular distributions 455, 457.
Waveguide 1 comprises arrays of inclined facets 32A, 32B that extend along the lateral (x-axis) direction. The waveguide 1 of
Switchable privacy display components will now be described.
It would be desirable to increase the security factor of a privacy display for at least the automotive application of
In the embodiment of
The display device 100 further comprises a reflective polariser 302, the reflective polariser 302 being a linear polariser, and said display polariser is an input display polariser 210 arranged on the input side of the spatial light modulator 48, and the display device 100 further comprises an output display polariser 218 arranged on the output side of the spatial light modulator 48, the second additional polariser 318B is arranged on the output side of the spatial light modulator 48, the at least one second polar control retarder 300B is arranged between the second additional polariser 318B and the output display polariser 218, and the reflective polariser 302 is arranged between the output display polariser 218 and at least one second polar control retarder 300B. In alternative embodiments said one of the at least one first polar control retarder 300A and the at least one second polar control retarder 300B is the at least one second polar control retarder 300B and said other of the at least one first polar control retarder 300A and the at least one second polar control retarder 300B is the at least one first polar control retarder 300A.
Increased reflectivity provides increased security factor and is advantageously provided in privacy mode of operation, while low reflectivity is provided in share mode of operation as described in
In the embodiment of
The display device 100 further comprises a reflective polariser 302, the reflective polariser 302 being a linear polariser, and said display polariser is an output display polariser 218 arranged on the output side of the spatial light modulator 48, the second additional polariser 318B is arranged on the same side of the spatial light modulator 48 as the first additional polariser 318A outside the first additional polariser 318A, the at least one second polar control retarder 300B is arranged between the first additional polariser 318A and the second additional polariser 318B, and the reflective polariser 302 is arranged between the first additional polariser 318A and the at least one second polar control retarder 300B. In alternative embodiments said one of the at least one first polar control retarder 300A and the at least one second polar control retarder 300B is the at least one second polar control retarder 300B and said other of the at least one first polar control retarder 300A and the at least one second polar control retarder 300B is the at least one first polar control retarder 300A.
Increased reflectivity and increased security factor is advantageously provided in privacy mode of operation, while low reflectivity is provided in share mode of operation.
Various alternative embodiments of privacy display device 100 will now be described.
In the alternatives of
For each polar control retarder 300A, 300B that comprises a liquid crystal retarder 314A, 314B with two homogeneous alignment layers 417A, 417B or two homeotropic alignment layers 417A, 417B then the respective passive retarder 330A, 330B or pair of crossed passive retarders 330AA, 330AB or 330BA, 330BB may be arranged to either receive light from the respective liquid crystal retarder 314A, 314B; or the liquid crystal retarder 314A, 314B may be arranged to receive light from the respective passive retarder 330A, 330B or pair of crossed passive retarders 330AA, 330AB or 330BA, 330BB. Advantageously the lamination of polarisers and passive retarders to the substrates 312A, 316A, 312B, 316B may be arranged to optimise the ruggedness and flatness of the respective polar control retarder 300A, 300B.
For each polar control retarder 300A, 300B that comprises a liquid crystal retarder 314A, 314B with one homogeneous alignment layer and one homeotropic alignment layer 417A, 417B then preferably the homeotropic alignment layer is arranged between the respective layer of liquid crystal material 414A, 414B and the respective passive retarder 330A, 330B. Advantageously the size of the polar region for reduced luminance in privacy mode is increased.
For the alternatives of
The size of the polar region for which high reflectivity is achieved in privacy mode may be adjusted by selection of the polar control retarder 300B. Polar control retarders 300B that comprise homeotropic alignment layer 417BA and homogeneous alignment layer 417BB advantageously increase the size of the polar region with high reflectivity. Polar control retarders 300B that comprise two homogeneous or two homeotropic alignment layers 417BA, 417BB increase the security factor close to angle α of
The operation of the polar control retarders for on-axis and off-axis light will now be described.
In share mode, rays 447 with a non-zero polar angle to the normal direction are also transmitted with the same polarisation state 360 that is substantially not modified by the polar control retarders 300A, 300B and polarisers 318A, 302 and 318B. The polar profile of luminance from the spatial light modulator may be substantially unmodified. Advantageously the display may be visible from a wide range of polar viewing positions and viewable by multiple display users.
The operation of the reflective polariser 302 will now be described.
By comparison light ray 406 undergoes a phase modulation at the polar control retarder 300B such that state 364 illuminates the reflective polariser. The resolved polarisation state 366 that is orthogonal to the electric vector transmission direction 303 of the reflective polariser 302 is reflected and is passed through the polar retarder such that polarisation state 368 is incident on to the second additional polariser. The component of the state 368 that is parallel to the electric vector transmission direction of the polariser 318B is thus transmitted. To an off-axis observer, the display appears to have increased reflectivity. Said increased reflectivity advantageously achieves increased security factor, S as described above.
The embodiments herein that are illustrated comprising a reflective polariser 302 may further be provided with no reflective polariser 302. Advantageously displays may be provided with low reflectivity in privacy mode of operation. For example displays for use in bright ambient environments such as for daytime operation in automotive vehicles may not provide a reflectivity enhancement in privacy mode.
As may be used herein, the terms “substantially” and “approximately” provide an industry-accepted tolerance for its corresponding term and/or relativity between items. Such an industry-accepted tolerance ranges from zero percent to ten percent and corresponds to, but is not limited to, component values, angles, et cetera. Such relativity between items ranges between approximately zero percent to ten percent.
While various embodiments in accordance with the principles disclosed herein have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of this disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with any claims and their equivalents issuing from this disclosure. Furthermore, the above advantages and features are provided in described embodiments, but shall not limit the application of such issued claims to processes and structures accomplishing any or all of the above advantages.
Additionally, the section headings herein are provided for consistency with the suggestions under 37 CFR 1.77 or otherwise to provide organizational cues. These headings shall not limit or characterize the embodiment(s) set out in any claims that may issue from this disclosure. Specifically and by way of example, although the headings refer to a “Technical Field,” the claims should not be limited by the language chosen under this heading to describe the so-called field. Further, a description of a technology in the “Background” is not to be construed as an admission that certain technology is prior art to any embodiment(s) in this disclosure. Neither is the “Summary” to be considered as a characterization of the embodiment(s) set forth in issued claims. Furthermore, any reference in this disclosure to “invention” in the singular should not be used to argue that there is only a single point of novelty in this disclosure. Multiple embodiments may be set forth according to the limitations of the multiple claims issuing from this disclosure, and such claims accordingly define the embodiment(s), and their equivalents, that are protected thereby. In all instances, the scope of such claims shall be considered on their own merits in light of this disclosure, but should not be constrained by the headings set forth herein.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3914022 | Kashnow | Oct 1975 | A |
| 4059916 | Tachihara et al. | Nov 1977 | A |
| 4621898 | Cohen | Nov 1986 | A |
| 4974941 | Gibbons et al. | Dec 1990 | A |
| 5005108 | Pristash et al. | Apr 1991 | A |
| 5035491 | Kawagishi et al. | Jul 1991 | A |
| 5126882 | Oe et al. | Jun 1992 | A |
| 5608550 | Epstein et al. | Mar 1997 | A |
| 5658490 | Sharp et al. | Aug 1997 | A |
| 5671994 | Tai et al. | Sep 1997 | A |
| 5715028 | Abileah et al. | Feb 1998 | A |
| 5779337 | Saito et al. | Jul 1998 | A |
| 5791757 | O'Neil et al. | Aug 1998 | A |
| 5808784 | Ando et al. | Sep 1998 | A |
| 5835166 | Hall et al. | Nov 1998 | A |
| 5854872 | Tai | Dec 1998 | A |
| 5894361 | Yamazaki et al. | Apr 1999 | A |
| 5914760 | Daiku | Jun 1999 | A |
| 5997148 | Ohkawa | Dec 1999 | A |
| 6055103 | Woodgate et al. | Apr 2000 | A |
| 6099758 | Verrall et al. | Aug 2000 | A |
| 6144433 | Tillin et al. | Nov 2000 | A |
| 6169589 | Kaneko | Jan 2001 | B1 |
| 6204904 | Tillin et al. | Mar 2001 | B1 |
| 6222672 | Towler et al. | Apr 2001 | B1 |
| 6280043 | Ohkawa | Aug 2001 | B1 |
| 6364497 | Park et al. | Apr 2002 | B1 |
| 6379016 | Boyd et al. | Apr 2002 | B1 |
| 6392727 | Larson et al. | May 2002 | B1 |
| 6437915 | Moseley et al. | Aug 2002 | B2 |
| 6731355 | Miyashita | May 2004 | B2 |
| 7067985 | Adachi | Jun 2006 | B2 |
| 7072096 | Holman et al. | Jul 2006 | B2 |
| 7163319 | Kuo et al. | Jan 2007 | B2 |
| 7227602 | Jeon et al. | Jun 2007 | B2 |
| 7366392 | Honma et al. | Apr 2008 | B2 |
| 7524542 | Kim et al. | Apr 2009 | B2 |
| 7528893 | Schultz et al. | May 2009 | B2 |
| 7528913 | Kobayashi | May 2009 | B2 |
| 7633586 | Winlow et al. | Dec 2009 | B2 |
| 7660047 | Travis et al. | Feb 2010 | B1 |
| 7766534 | Iwasaki | Aug 2010 | B2 |
| 7834834 | Takatani et al. | Nov 2010 | B2 |
| 7970246 | Travis et al. | Jun 2011 | B2 |
| 7991257 | Coleman | Aug 2011 | B1 |
| 8070346 | Maeda et al. | Dec 2011 | B2 |
| 8098350 | Sakai et al. | Jan 2012 | B2 |
| 8154686 | Mather et al. | Apr 2012 | B2 |
| 8237876 | Tan et al. | Aug 2012 | B2 |
| 8249408 | Coleman | Aug 2012 | B2 |
| 8262271 | Tillin et al. | Sep 2012 | B2 |
| 8469575 | Weber et al. | Jun 2013 | B2 |
| 8646931 | Choi et al. | Feb 2014 | B2 |
| 8801260 | Urano et al. | Aug 2014 | B2 |
| 8848132 | O'Neill et al. | Sep 2014 | B2 |
| 8939595 | Choi et al. | Jan 2015 | B2 |
| 8973149 | Buck | Mar 2015 | B2 |
| 9195087 | Terashima | Nov 2015 | B2 |
| 9274260 | Urano et al. | Mar 2016 | B2 |
| 9304241 | Wang et al. | Apr 2016 | B2 |
| 9324234 | Ricci et al. | Apr 2016 | B2 |
| 9448355 | Urano et al. | Sep 2016 | B2 |
| 9501036 | Kang et al. | Nov 2016 | B2 |
| 9519153 | Robinson et al. | Dec 2016 | B2 |
| 9541698 | Wheatley et al. | Jan 2017 | B2 |
| 10054732 | Robinson et al. | Aug 2018 | B2 |
| 10126575 | Robinson et al. | Nov 2018 | B1 |
| 10303030 | Robinson et al. | May 2019 | B2 |
| 10401638 | Robinson et al. | Sep 2019 | B2 |
| 10488705 | Xu et al. | Nov 2019 | B2 |
| 10527775 | Yang et al. | Jan 2020 | B2 |
| 10649248 | Jiang et al. | May 2020 | B1 |
| 10649259 | Lee et al. | May 2020 | B2 |
| 10935714 | Woodgate et al. | Mar 2021 | B2 |
| 11070791 | Woodgate et al. | Jul 2021 | B2 |
| 20010024561 | Cornelissen et al. | Sep 2001 | A1 |
| 20020015300 | Katsu et al. | Feb 2002 | A1 |
| 20020024529 | Miller et al. | Feb 2002 | A1 |
| 20020171793 | Sharp et al. | Nov 2002 | A1 |
| 20030058381 | Shinohara et al. | Mar 2003 | A1 |
| 20030089956 | Allen et al. | May 2003 | A1 |
| 20030107686 | Sato et al. | Jun 2003 | A1 |
| 20030117792 | Kunimochi et al. | Jun 2003 | A1 |
| 20030214615 | Colgan et al. | Nov 2003 | A1 |
| 20040015729 | Elms et al. | Jan 2004 | A1 |
| 20040100598 | Adachi et al. | May 2004 | A1 |
| 20040125430 | Kasajima et al. | Jul 2004 | A1 |
| 20040141107 | Jones | Jul 2004 | A1 |
| 20040145703 | O'Connor et al. | Jul 2004 | A1 |
| 20040240777 | Woodgate et al. | Dec 2004 | A1 |
| 20040264910 | Suzuki et al. | Dec 2004 | A1 |
| 20050002174 | Min et al. | Jan 2005 | A1 |
| 20050111100 | Mather et al. | May 2005 | A1 |
| 20050117186 | Li et al. | Jun 2005 | A1 |
| 20050135116 | Epstein et al. | Jun 2005 | A1 |
| 20050157225 | Toyooka et al. | Jul 2005 | A1 |
| 20050190326 | Jeon et al. | Sep 2005 | A1 |
| 20050190329 | Okumura | Sep 2005 | A1 |
| 20050213348 | Parikka et al. | Sep 2005 | A1 |
| 20050219693 | Hartkop et al. | Oct 2005 | A1 |
| 20050270798 | Lee et al. | Dec 2005 | A1 |
| 20060066785 | Moriya | Mar 2006 | A1 |
| 20060082702 | Jacobs et al. | Apr 2006 | A1 |
| 20060098296 | Woodgate et al. | May 2006 | A1 |
| 20060203162 | Ito et al. | Sep 2006 | A1 |
| 20060215244 | Yosha et al. | Sep 2006 | A1 |
| 20060244884 | Jeon et al. | Nov 2006 | A1 |
| 20060262258 | Wang et al. | Nov 2006 | A1 |
| 20060262558 | Cornelissen | Nov 2006 | A1 |
| 20060268207 | Tan et al. | Nov 2006 | A1 |
| 20060285040 | Kobayashi | Dec 2006 | A1 |
| 20070035964 | Olczak | Feb 2007 | A1 |
| 20070047254 | Schardt et al. | Mar 2007 | A1 |
| 20070064163 | Tan et al. | Mar 2007 | A1 |
| 20070139772 | Wang | Jun 2007 | A1 |
| 20070223251 | Liao | Sep 2007 | A1 |
| 20070285775 | Lesage et al. | Dec 2007 | A1 |
| 20080008434 | Lee et al. | Jan 2008 | A1 |
| 20080068329 | Shestak et al. | Mar 2008 | A1 |
| 20080068862 | Shimura | Mar 2008 | A1 |
| 20080129899 | Sharp | Jun 2008 | A1 |
| 20080158491 | Zhu et al. | Jul 2008 | A1 |
| 20080158912 | Chang et al. | Jul 2008 | A1 |
| 20080205066 | Ohta et al. | Aug 2008 | A1 |
| 20080285310 | Aylward et al. | Nov 2008 | A1 |
| 20080316198 | Fukushima et al. | Dec 2008 | A1 |
| 20090040426 | Mather et al. | Feb 2009 | A1 |
| 20090085894 | Gandhi et al. | Apr 2009 | A1 |
| 20090086509 | Omori et al. | Apr 2009 | A1 |
| 20090109703 | Chen et al. | Apr 2009 | A1 |
| 20090128735 | Larson et al. | May 2009 | A1 |
| 20090128746 | Kean et al. | May 2009 | A1 |
| 20090135623 | Kunimochi | May 2009 | A1 |
| 20090174843 | Sakai et al. | Jul 2009 | A1 |
| 20090213298 | Mimura et al. | Aug 2009 | A1 |
| 20090213305 | Ohmuro et al. | Aug 2009 | A1 |
| 20090244415 | Ide | Oct 2009 | A1 |
| 20100002296 | Choi et al. | Jan 2010 | A1 |
| 20100128200 | Morishita et al. | May 2010 | A1 |
| 20100149459 | Yabuta et al. | Jun 2010 | A1 |
| 20100177113 | Gay et al. | Jul 2010 | A1 |
| 20100205667 | Anderson et al. | Aug 2010 | A1 |
| 20100238376 | Sakai et al. | Sep 2010 | A1 |
| 20100283930 | Park et al. | Nov 2010 | A1 |
| 20100289989 | Adachi et al. | Nov 2010 | A1 |
| 20100295755 | Broughton et al. | Nov 2010 | A1 |
| 20100328438 | Ohyama et al. | Dec 2010 | A1 |
| 20110018860 | Parry-Jones et al. | Jan 2011 | A1 |
| 20110032483 | Hruska et al. | Feb 2011 | A1 |
| 20110176089 | Ishikawa et al. | Jul 2011 | A1 |
| 20110241983 | Chang | Oct 2011 | A1 |
| 20110255304 | Kinoshita | Oct 2011 | A1 |
| 20110286222 | Coleman | Nov 2011 | A1 |
| 20110321143 | Angaluri et al. | Dec 2011 | A1 |
| 20120002121 | Pirs et al. | Jan 2012 | A1 |
| 20120086875 | Yokota | Apr 2012 | A1 |
| 20120127573 | Robinson et al. | May 2012 | A1 |
| 20120147280 | Osterman et al. | Jun 2012 | A1 |
| 20120188792 | Matsumoto et al. | Jul 2012 | A1 |
| 20120212414 | Osterhout et al. | Aug 2012 | A1 |
| 20120235891 | Nishitani et al. | Sep 2012 | A1 |
| 20120294037 | Holman et al. | Nov 2012 | A1 |
| 20120299913 | Robinson et al. | Nov 2012 | A1 |
| 20120314145 | Robinson | Dec 2012 | A1 |
| 20120320311 | Gotou et al. | Dec 2012 | A1 |
| 20120327101 | Blixt et al. | Dec 2012 | A1 |
| 20130039062 | Vinther et al. | Feb 2013 | A1 |
| 20130057807 | Goto et al. | Mar 2013 | A1 |
| 20130100097 | Martin | Apr 2013 | A1 |
| 20130107174 | Yun et al. | May 2013 | A1 |
| 20130128165 | Lee et al. | May 2013 | A1 |
| 20130242231 | Kurata et al. | Sep 2013 | A1 |
| 20130242612 | Lee et al. | Sep 2013 | A1 |
| 20130278544 | Cok | Oct 2013 | A1 |
| 20130293793 | Lu | Nov 2013 | A1 |
| 20130300985 | Bulda | Nov 2013 | A1 |
| 20130307831 | Robinson et al. | Nov 2013 | A1 |
| 20130308339 | Woodgate et al. | Nov 2013 | A1 |
| 20130321340 | Seo et al. | Dec 2013 | A1 |
| 20130328866 | Woodgate et al. | Dec 2013 | A1 |
| 20140009508 | Woodgate et al. | Jan 2014 | A1 |
| 20140022619 | Woodgate et al. | Jan 2014 | A1 |
| 20140071382 | Scardato | Mar 2014 | A1 |
| 20140098418 | Lin | Apr 2014 | A1 |
| 20140098558 | Vasylyev | Apr 2014 | A1 |
| 20140111760 | Guo et al. | Apr 2014 | A1 |
| 20140132887 | Kurata | May 2014 | A1 |
| 20140133181 | Ishida et al. | May 2014 | A1 |
| 20140140091 | Vasylyev | May 2014 | A1 |
| 20140140095 | Yuki et al. | May 2014 | A1 |
| 20140176873 | Shinohara et al. | Jun 2014 | A1 |
| 20140201844 | Buck | Jul 2014 | A1 |
| 20140211125 | Kurata | Jul 2014 | A1 |
| 20140232960 | Schwartz et al. | Aug 2014 | A1 |
| 20140240344 | Tomono et al. | Aug 2014 | A1 |
| 20140240828 | Robinson et al. | Aug 2014 | A1 |
| 20140240839 | Yang et al. | Aug 2014 | A1 |
| 20140268358 | Kusaka et al. | Sep 2014 | A1 |
| 20140286043 | Sykora et al. | Sep 2014 | A1 |
| 20140286044 | Johnson et al. | Sep 2014 | A1 |
| 20140289835 | Varshavsky et al. | Sep 2014 | A1 |
| 20140340728 | Taheri | Nov 2014 | A1 |
| 20140361990 | Leister | Dec 2014 | A1 |
| 20140367873 | Yang et al. | Dec 2014 | A1 |
| 20150055366 | Chang et al. | Feb 2015 | A1 |
| 20150116212 | Freed et al. | Apr 2015 | A1 |
| 20150177447 | Woodgate et al. | Jun 2015 | A1 |
| 20150177563 | Cho et al. | Jun 2015 | A1 |
| 20150185398 | Chang et al. | Jul 2015 | A1 |
| 20150205157 | Sakai et al. | Jul 2015 | A1 |
| 20150268479 | Woodgate et al. | Sep 2015 | A1 |
| 20150286061 | Seo et al. | Oct 2015 | A1 |
| 20150286817 | Haddad et al. | Oct 2015 | A1 |
| 20150293289 | Shinohara et al. | Oct 2015 | A1 |
| 20150301400 | Kimura et al. | Oct 2015 | A1 |
| 20150338564 | Zhang et al. | Nov 2015 | A1 |
| 20150346417 | Powell | Dec 2015 | A1 |
| 20150346532 | Do et al. | Dec 2015 | A1 |
| 20150355490 | Kao et al. | Dec 2015 | A1 |
| 20150378085 | Robinson et al. | Dec 2015 | A1 |
| 20160054508 | Hirayama et al. | Feb 2016 | A1 |
| 20160103264 | Lee et al. | Apr 2016 | A1 |
| 20160132721 | Bostick et al. | May 2016 | A1 |
| 20160147074 | Kobayashi et al. | May 2016 | A1 |
| 20160154259 | Kim et al. | Jun 2016 | A1 |
| 20160216420 | Gaides et al. | Jul 2016 | A1 |
| 20160216540 | Cho et al. | Jul 2016 | A1 |
| 20160224106 | Liu | Aug 2016 | A1 |
| 20160238869 | Osterman et al. | Aug 2016 | A1 |
| 20160259115 | Kitano et al. | Sep 2016 | A1 |
| 20160334898 | Kwak et al. | Nov 2016 | A1 |
| 20160349444 | Robinson et al. | Dec 2016 | A1 |
| 20160356943 | Choi et al. | Dec 2016 | A1 |
| 20160357046 | Choi et al. | Dec 2016 | A1 |
| 20170003436 | Inoue et al. | Jan 2017 | A1 |
| 20170031206 | Smith et al. | Feb 2017 | A1 |
| 20170090103 | Holman | Mar 2017 | A1 |
| 20170092187 | Bergquist | Mar 2017 | A1 |
| 20170092229 | Greenebaum et al. | Mar 2017 | A1 |
| 20170115485 | Saito et al. | Apr 2017 | A1 |
| 20170123241 | Su et al. | May 2017 | A1 |
| 20170139110 | Woodgate et al. | May 2017 | A1 |
| 20170168633 | Kwak et al. | Jun 2017 | A1 |
| 20170205558 | Hirayama et al. | Jul 2017 | A1 |
| 20170236494 | Sommerlade et al. | Aug 2017 | A1 |
| 20170269283 | Wang et al. | Sep 2017 | A1 |
| 20170269285 | Hirayama et al. | Sep 2017 | A1 |
| 20170315423 | Serati et al. | Nov 2017 | A1 |
| 20170329399 | Azam et al. | Nov 2017 | A1 |
| 20170336661 | Harrold et al. | Nov 2017 | A1 |
| 20170339398 | Woodgate et al. | Nov 2017 | A1 |
| 20170343715 | Fang et al. | Nov 2017 | A1 |
| 20170363798 | Hirayama et al. | Dec 2017 | A1 |
| 20180014007 | Brown | Jan 2018 | A1 |
| 20180052346 | Sakai et al. | Feb 2018 | A1 |
| 20180082068 | Lancioni et al. | Mar 2018 | A1 |
| 20180095581 | Hwang et al. | Apr 2018 | A1 |
| 20180113334 | Fang et al. | Apr 2018 | A1 |
| 20180188576 | Xu et al. | Jul 2018 | A1 |
| 20180188603 | Fang et al. | Jul 2018 | A1 |
| 20180196275 | Robinson et al. | Jul 2018 | A1 |
| 20180210243 | Fang et al. | Jul 2018 | A1 |
| 20180231811 | Wu | Aug 2018 | A1 |
| 20180252949 | Klippstein et al. | Sep 2018 | A1 |
| 20180259799 | Kroon | Sep 2018 | A1 |
| 20180259812 | Goda et al. | Sep 2018 | A1 |
| 20180284341 | Woodgate et al. | Oct 2018 | A1 |
| 20180321523 | Robinson et al. | Nov 2018 | A1 |
| 20180321553 | Robinson et al. | Nov 2018 | A1 |
| 20180329245 | Robinson et al. | Nov 2018 | A1 |
| 20180364526 | Finnemeyer et al. | Dec 2018 | A1 |
| 20190086706 | Robinson et al. | Mar 2019 | A1 |
| 20190121173 | Robinson et al. | Apr 2019 | A1 |
| 20190154896 | Yanai | May 2019 | A1 |
| 20190196235 | Robinson et al. | Jun 2019 | A1 |
| 20190196236 | Chen et al. | Jun 2019 | A1 |
| 20190197928 | Schubert et al. | Jun 2019 | A1 |
| 20190215509 | Woodgate et al. | Jul 2019 | A1 |
| 20190227366 | Harrold et al. | Jul 2019 | A1 |
| 20190235304 | Tamada et al. | Aug 2019 | A1 |
| 20190250458 | Robinson | Aug 2019 | A1 |
| 20190278010 | Sakai et al. | Sep 2019 | A1 |
| 20190293858 | Woodgate et al. | Sep 2019 | A1 |
| 20190293983 | Robinson et al. | Sep 2019 | A1 |
| 20190353944 | Acreman et al. | Nov 2019 | A1 |
| 20190361165 | Chang et al. | Nov 2019 | A1 |
| 20200026125 | Robinson et al. | Jan 2020 | A1 |
| 20200159055 | Robinson et al. | May 2020 | A1 |
| 20200218101 | Ihas et al. | Jul 2020 | A1 |
| 20200225402 | Ihas et al. | Jul 2020 | A1 |
| 20200233142 | Liao et al. | Jul 2020 | A1 |
| 20210149233 | Robinson et al. | May 2021 | A1 |
| Number | Date | Country |
|---|---|---|
| 2222313 | Jun 1998 | CA |
| 1125943 | Oct 2003 | CN |
| 1776484 | May 2006 | CN |
| 101518095 | Aug 2009 | CN |
| 101681061 | Mar 2010 | CN |
| 103473494 | Dec 2013 | CN |
| 104133292 | Nov 2014 | CN |
| 104303085 | Jan 2015 | CN |
| 204740413 | Nov 2015 | CN |
| 106104372 | Nov 2016 | CN |
| 106415342 | Feb 2017 | CN |
| 209171779 | Jul 2019 | CN |
| 2418518 | Mar 2006 | GB |
| 2428100 | Jan 2007 | GB |
| 2482065 | Jan 2012 | GB |
| 2486935 | Sep 2013 | GB |
| H01130783 | Sep 1989 | JP |
| H11174489 | Jul 1999 | JP |
| 2007148279 | Jun 2007 | JP |
| 2007273288 | Oct 2007 | JP |
| 20120011228 | Feb 2012 | KR |
| 101990286 | Jun 2019 | KR |
| M537663 | Mar 2017 | TW |
| 1612360 | Jan 2018 | TW |
| 2005071449 | Aug 2005 | WO |
| 2010021926 | Feb 2010 | WO |
| 2014011328 | Jan 2014 | WO |
| 2015040776 | Mar 2015 | WO |
| 2015057625 | Apr 2015 | WO |
| 2015143227 | Sep 2015 | WO |
| 2015157184 | Oct 2015 | WO |
| 2015190311 | Dec 2015 | WO |
| 2015200814 | Dec 2015 | WO |
| 2016195786 | Dec 2016 | WO |
| 2017050631 | Mar 2017 | WO |
| 2018035492 | Feb 2018 | WO |
| 2018208618 | Nov 2018 | WO |
| 2019055755 | Mar 2019 | WO |
| 2019067846 | Apr 2019 | WO |
| 2019147762 | Aug 2019 | WO |
| Entry |
|---|
| Cheng, et al., “Fast-Response Liquid Crystal Variable Optical Retarder and Multilevel Attenuator,” Optical Engineering 52 (10), 107105 (Oct. 16, 2013). (Year: 2013). |
| PCT/US2021/029937 International search report and written opinion of the international searching authority dated Aug. 6, 2021. |
| PCT/US2021/029944 International search report and written opinion of the international searching authority dated Aug. 3, 2021. |
| PCT/US2021/029947 International search report and written opinion of the international searching authority dated Aug. 10, 2021. |
| PCT/US2021/029954 International search report and written opinion of the international searching authority dated Aug. 10, 2021. |
| PCT/US2021/029958 International search report and written opinion of the international searching authority dated Aug. 10, 2021. |
| Adachi, et al. “P-228L: Late-News Poster: Controllable Viewing-Angle Displays using a Hybrid Aligned Nematic Liquid Crystal Cell”, ISSN, SID 2006 Digest, pp. 705-708. |
| Brudy et al., “Is Anyone Looking? Mitigating Shoulder Surfing on Public Displays through Awareness and Protection”, Proceedings of the International Symposium on Persuasive Displays (Jun. 3, 2014), pp. 1-6. |
| CN201780030715.3 Notification of the First Office Action dated Jan. 21, 2020. |
| CN201880042320.X Notification of the First Office Action dated May 25, 2021. |
| EP-16860628.3 Extended European Search Report of European Patent Office dated Apr. 26, 2019. |
| EP-17799963.8 Extended European Search Report of European Patent Office dated Oct. 9, 2019. |
| EP-18855604.7 Extended European Search Report of European Patent Office dated Jun. 1, 2021. |
| EP-18857077.4 Extended European Search Report of European Patent Office dated Jun. 16, 2021. |
| Gass, et al. “Privacy LCD Technology for Cellular Phones”, Sharp Laboratories of Europe Ltd, Mobile LCD Group, Feb. 2007, pp. 45-49. |
| Ishikawa, T., “New Design for a Highly Collimating Turning Film”, SID 06 Digest, pp. 514-517. |
| Kalantar, et al. “Backlight Unit With Double Surface Light Emission,” J. Soc. Inf. Display, vol. 12, Issue 4, pp. 379-387 (Dec. 2004). |
| PCT/US2016/058695 International search report and written opinion of the international searching authority dated Feb. 28, 2017. |
| PCT/US2017/032734 International search report and written opinion of the international searching authority dated Jul. 27, 2017. |
| PCT/US2018/031206 International search report and written opinion of the international searching authority dated Jul. 20, 2018. |
| PCT/US2018/031218 International search report and written opinion of the international searching authority dated Jul. 19, 2018. |
| PCT/US2018/051021 International search report and written opinion of the international searching authority dated Nov. 21, 2018. |
| PCT/US2018/051027 International search report and written opinion of the international searching authority dated Nov. 30, 2018. |
| PCT/US2018/053328 International search report and written opinion of the international searching authority dated Nov. 30, 2018. |
| PCT/US2018/059249 International search report and written opinion of the international searching authority dated Jan. 3, 2019. |
| PCT/US2018/059256 International search report and written opinion of the international searching authority dated Jan. 3, 2019. |
| PCT/US2019/014889 International search report and written opinion of the international searching authority dated May 24, 2019. |
| PCT/US2019/014902 International search report and written opinion of the international searching authority dated Jun. 25, 2019. |
| PCT/US2019/023659 International search report and written opinion of the international searching authority dated Jun. 10, 2019. |
| PCT/US2019/038409 International search report and written opinion of the international searching authority dated Sep. 19, 2019. |
| PCT/US2019/038466 International search report and written opinion of the international searching authority dated Nov. 5, 2019. |
| PCT/US2019/042027 International search report and written opinion of the international searching authority dated Oct. 15, 2019. |
| PCT/US2019/054291 International search report and written opinion of the international searching authority dated Jan. 6, 2020. |
| PCT/US2019/059990 International search report and written opinion of the international searching authority dated Feb. 28, 2020. |
| PCT/US2019/066208 International search report and written opinion of the international searching authority dated Feb. 27, 2020. |
| PCT/US2020/017537 International search report and written opinion of the international searching authority dated Apr. 29, 2020. |
| PCT/US2020/040686 International search report and written opinion of the international searching authority dated Nov. 20, 2020. |
| PCT/US2020/044574 International search report and written opinion of the international searching authority dated Oct. 21, 2020. |
| PCT/US2020/053863 International search report and written opinion of the international searching authority dated Mar. 12, 2021. |
| PCT/US2020/060155 International search report and written opinion of the international searching authority dated Feb. 5, 2021. |
| PCT/US2020/060191 International search report and written opinion of the international searching authority dated Feb. 8, 2021. |
| PCT/US2020/063638 International search report and written opinion of the international searching authority dated Mar. 2, 2021. |
| PCT/US2020/064633 International search report and written opinion of the international searching authority dated Mar. 15, 2021. |
| Robson, et al. “Spatial and temporal contrast-sensitivity functions of the visual system”, J. Opt. Soc. Amer., vol. 56, pp. 1141-1142 (1966). |
| Simonyan et al., “Very Deep Convolutional Networks For Large-Scale Image Recognition”, ICLR 2015. |
| Weindorf et al., “Active Circular Polarizer OLED E-Mirror”, Proceedings of the Society for Information Display 25th Annual Symposium of Vehicle Displays, Livonia, MI, pp. 225-237, Sep. 25-26, 2018. |
| CN201680061632.6 Notification of the First Office Action dated Sep. 14, 2021. |
| EP-19743619.9 Extended European Search of European Patent Office dated Nov. 23, 2021. |
| EP-19743701.5 Extended European Search Report of European Patent Office dated Nov. 24, 2021. |
| EP19771688.9 Extended European Search Report of European Patent Office dated Dec. 2, 2021. |
| PCT/US2021/043435 International search report and written opinion of the international searching authority dated Nov. 1, 2021. |
| PCT/US2021/043444 International search report and written opinion of the international searching authority dated Nov. 1, 2021. |
| Number | Date | Country | |
|---|---|---|---|
| 20210341769 A1 | Nov 2021 | US |
| Number | Date | Country | |
|---|---|---|---|
| 63017721 | Apr 2020 | US |
