ACTIVE PUBLIC/PRIVACY DISPLAY PANELS

A display panel includes a first polarizer, two twisted nematic cells, a second polarizer, and a display. The first twisted nematic cell transfers light in response to a first control signal. In an off state, a polarity of the light is rotated in a first twist. In an on state, the polarity of the light is maintained. The second twisted nematic cell transfers the light in response to a second control signal. In the off state, a polarity of the light is rotated in a second twist. In the on state, the polarity of the light is maintained. The display generates an image in the light in response to a display signal. While the twisted nematic cells are in the off state, the image is viewable in a public viewing angle. While the twisted nematic cells are in the on state, the image is viewable in a private viewing angle.

TECHNICAL FIELD

The present disclosure generally relates to visibility of electronic displays, and in particular to display panels with an active public mode and a privacy mode.

BACKGROUND

Console-based display panels are becoming more popular in automobiles. The display panels are commonly intended for use by a driver of the automobile and a passenger sitting next to the driver. With an availability of video sources and Internet content within the automobiles, conflicts have been created between the drivers and the passengers for what content to present on the display panels.

SUMMARY

A display panel is provided herein. The display panel includes a first polarizer, a first twisted nematic cell, a second twisted nematic cell, a second polarizer, and a display. The first polarizer is configured to transfer a light to have a polarity. The first twisted nematic cell is mounted adjacent to the first polarizer. The first twisted nematic cell transfers the light received from the first polarizer in response to a first control signal. The first control signal is switchable between a first off state and a first on state. The first off state rotates the polarity of the light in a first twist. The first on state maintains the polarity of the light in an angular range. The second twisted nematic cell is mounted adjacent to the first twisted nematic cell. The second twisted nematic cell transfers the light received from the first twisted nematic cell in response to a second control signal. The second control signal is switchable between a second off state and a second on state. The second off state rotates the polarity in a second twist. The second on state maintains the polarity of the light in the angular range. The second twist is in an opposite direction as the first twist.

The second polarizer is mounted adjacent to the second twisted nematic cell and configured to polarize the light received from the second twisted nematic cell. The display is mounted adjacent to one of the first polarizer or the second polarizer and configured to generate an image in the light in response to a display signal. While the first twisted nematic cell is in the first off state and the second twisted nematic cell is in the second off state, the image is viewable in a public viewing angle. While the first twisted nematic cell is in the first on state and the second twisted nematic cell is in the second on state, the image is viewable in a private viewing angle. The private viewing angle is narrower than the public viewing angle.

In one or more embodiments of the display panel, the display is a thin-film transistor display mounted adjacent to the second polarizer.

In one or more embodiments, the display panel includes a backlight source mounted adjacent to the first polarizer.

In one or more embodiments, the display panel includes a dual brightness enhancement film mounted between the backlight source and the first polarizer.

In one or more embodiments of the display panel, the display is an organic light-emitting diode display mounted adjacent to the first polarizer, and the first polarizer is oriented in response to a polarization input for the first twisted nematic cell.

In one or more embodiments, the display panel includes a quarter-wave plate mounted adjacent to the display and oriented to one of 135 degrees or 45 degrees.

In one or more embodiments, the display panel includes a third polarizer mounted between the first twisted nematic cell and the second twisted nematic cell.

In one or more embodiments, the display panel includes a compensated half-wave plate mounted between the second twisted nematic cell and the second polarizer.

In one or more embodiments, the display panel includes a first compensation stack mounted between the first twisted nematic cell and the second twisted nematic cell.

In one or more embodiments, the display panel includes a second compensation stack mounted between the second twisted nematic cell and the second polarizer.

A display panel is provided herein. The display panel includes a first polarizer, a first twisted nematic cell, a second twisted nematic cell, and a display. The first polarizer is configured to transfer a light to have a polarity. The first twisted nematic cell is mounted adjacent to the first polarizer. The first twisted nematic cell has a first cell gap that results in a first color shift. The first twisted nematic cell transfers the light received from the first polarizer in response to a first control signal. The first control signal is switchable between a first off state and a first on state. The second twisted nematic cell is mounted adjacent to the first twisted nematic cell. The second twisted nematic cell has a second cell gap that results in a second color shift. The second color shift compensates for the first color shift. The second twisted nematic cell transfers the light received from the first twisted nematic cell in response to a second control signal. The second control signal is switchable between a second off state and a second on state.

The second polarizer is mounted adjacent to the second twisted nematic cell and configured to polarize the light received from the second twisted nematic cell. The display is mounted adjacent to one of the first polarizer or the second polarizer and configured to generate an image in the light in response to a display signal. While the first twisted nematic cell is in the first off state and the second twisted nematic cell is in the second off state, the image is viewable in a public viewing angle. While the first twisted nematic cell is in the first on state and the second twisted nematic cell is in the second on state, the image is viewable in a private viewing angle. The private viewing angle is narrower than the public viewing angle.

In one or more embodiments of the display panel, the display is a thin-film transistor display mounted adjacent to the second polarizer.

In one or more embodiments, the display panel further includes a backlight source mounted adjacent to the first polarizer.

In one or more embodiments, the display panel further includes comprising a third polarizer mounted between the first twisted nematic cell and the second twisted nematic cell.

In one or more embodiments, the display panel further includes a compensated half-wave plate mounted between the second twisted nematic cell and the second polarizer.

A display panel is provided herein. The display panel includes a first polarizer, a first twisted nematic cell, a second polarizer, and a display. The first polarizer is configured to transfer a light to have a polarity. The first twisted nematic cell is mounted adjacent to the first polarizer. The first twisted nematic cell transfers the light received from the first polarizer in response to a first control signal. The first control signal is switchable between a first off state and a first on state. The first off state rotates the polarity of the light in a first twist. The first on state maintains the polarity of the light in an angular range.

The second polarizer is mounted adjacent to the first twisted nematic cell and configured to polarize the light received from the first twisted nematic cell. The display is mounted adjacent to the second polarizer and configured to generate an image in the light in response to a display signal. While the first twisted nematic cell is in the first off state, the image is viewable in a public viewing angle. While the first twisted nematic cell is in the first on state, the image is viewable in a private viewing angle. The private viewing angle is narrower than the public viewing angle.

In one or more embodiments of the display panel, the display is a thin-film transistor display.

In one or more embodiments, the display panel further includes a backlight source mounted adjacent to the first polarizer.

In one or more embodiments, the display panel further includes a compensation stack mounted between the first twisted nematic cell and the second polarizer.

A display panel is provided herein. The display panel includes a first polarizer, a first twisted nematic cell, a second twisted nematic cell, a second polarizer, and a display. The first polarizer is configured to transfer a light to have a polarity. The first twisted nematic cell is mounted adjacent to the first polarizer. The first twisted nematic cell transfers the light received from the first polarizer in response to a first control signal. The first control signal is switchable between a first white state and a first black state. The first white state rotates the polarity of the light in an angular range. The first black state maintains the polarity of the light. The second twisted nematic cell is mounted adjacent to the first twisted nematic cell. The second twisted nematic cell transfers the light received from the first twisted nematic cell in response to a second control signal. The second control signal is switchable between an intermediate state and a second white state. The second white state does not rotate the polarity of the light. The intermediate state maintains the polarity of the light in the angular range.

The second polarizer is mounted adjacent to the second twisted nematic cell and is configured to polarize the light received from the second twisted nematic cell. The display is mounted adjacent to one of the first polarizer or the second polarizer and is configured to generate an image in the light in response to a display signal. The first twisted nematic cell and the second twisted nematic cell are controlled to present the image switchable between a public viewing angle and a private viewing angle. The private viewing angle is narrower than the public viewing angle.

An instrument panel is provided herein. The instrument panel includes a control unit, a first polarizer, a first twisted nematic cell, a second twisted nematic cell, a second polarizer, and a display. The control unit is configured to generate a first control signal, a second control signal, and a display signal. The first polarizer is configured to transfer a light to have a polarity. The first twisted nematic cell is mounted adjacent to the first polarizer. The first twisted nematic cell transfers the light received from the first polarizer in response to the first control signal. The first control signal is switchable between a first off state and a first on state. The first off state rotates the polarity of the light in a first twist. The first on state maintains the polarity of the light in an angular range. The second twisted nematic cell is mounted adjacent to the first twisted nematic cell. The second twisted nematic cell transfers the light received from the first twisted nematic cell in response to the second control signal. The second control signal is switchable between a second off state and a second on state. The second off state rotates the polarity in a second twist. The second on state maintains the polarity of the light in the angular range. The second twist is in an opposite direction as the first twist.

The second polarizer is mounted adjacent to the second twisted nematic cell and configured to polarize the light received from the second twisted nematic cell. The display is mounted adjacent to one of the first polarizer or the second polarizer and configured to generate an image in the light in response to the display signal. While the first twisted nematic cell is in the first off state and the second twisted nematic cell is in the second off state, the image is viewable in a public viewing angle. While the first twisted nematic cell is in the first on state and the second twisted nematic cell is in the second on state, the image is viewable in a private viewing angle. The private viewing angle is narrower than the public viewing angle.

In one or more embodiments of the instrument panel, the display is a thin-film transistor display mounted adjacent to the second polarizer.

In one or more embodiments, the instrument panel includes a backlight source mounted adjacent to the first polarizer.

In one or more embodiments, the instrument panel includes a dual brightness enhancement film mounted between the backlight source and the first polarizer.

In one or more embodiments of the instrument panel, the display is an organic light-emitting diode display mounted adjacent to the first polarizer, and the first polarizer is oriented in response to a polarization input for the first twisted nematic cell.

In one or more embodiments, the instrument panel includes a quarter-wave plate mounted adjacent to the display and oriented to one of 135 degrees or 45 degrees.

In one or more embodiments, the instrument panel includes a third polarizer mounted between the first twisted nematic cell and the second twisted nematic cell.

In one or more embodiments, the instrument panel includes a compensated half-wave plate mounted between the second twisted nematic cell and the second polarizer.

In one or more embodiments, the instrument panel includes a first compensation stack mounted between the first twisted nematic cell and the second twisted nematic cell, and a second compensation stack mounted between the second twisted nematic cell and the second polarizer.

A non-transitory computer readable medium on which is recorded instructions, executable by a processor, for control of a display panel is provided herein. Execution of the instructions causes the processor to generate a first control signal transferred to the display panel, generate a second control signal transferred to the display panel, and generate a display signal transferred to the display panel.

The display panel includes a first polarizer, a first twisted nematic cell, a second twisted nematic cell, a second polarizer, and a display. The first polarizer is configured to transfer a light to have a polarity. The first twisted nematic cell is mounted adjacent to the first polarizer. The first twisted nematic cell transfers the light received from the first polarizer in response to the first control signal. The first control signal is switchable between a first off state and a first on state. The first off state rotates the polarity of the light in a first twist. The first on state maintains the polarity of the light in an angular range. The second twisted nematic cell is mounted adjacent to the first twisted nematic cell. The second twisted nematic cell transfers the light received from the first twisted nematic cell in response to the second control signal. The second control signal is switchable between a second off state and a second on state. The second off state rotates the polarity in a second twist. The second on state maintains the polarity of the light in the angular range. The second twist is in an opposite direction as the first twist;

The second polarizer is mounted adjacent to the second twisted nematic cell and configured to polarize the light received from the second twisted nematic cell. The display is mounted adjacent to one of the first polarizer or the second polarizer and configured to generate an image in the light in response to the display signal. While the first twisted nematic cell is in the first off state and the second twisted nematic cell is in the second off state, the image is viewable in a public viewing angle. While the first twisted nematic cell is in the first on state and the second twisted nematic cell is in the second on state, the image is viewable in a private viewing angle. The private viewing angle is narrower than the public viewing angle.

The present disclosure may have various modifications and alternative forms, and some representative embodiments are shown by way of example in the drawings and will be described in detail herein. Novel aspects of this disclosure are not limited to the particular forms illustrated in the above-enumerated drawings. Rather, the disclosure is to cover modifications, equivalents, and combinations falling within the scope of the disclosure as encompassed by the appended claims.

DETAILED DESCRIPTION

Embodiments of the disclosure generally provide for a display panel configured to generate an optical signal conveying a plurality of images. The optical signal may be transitioned between a private viewing angle (or mode) of operation and a public viewing angle (or mode) of operation. In various embodiments, the transition may be a discrete step between the private viewing angle and the public viewing angle. In other embodiments, the transition may be continuous between the private viewing angle and the public viewing angle. While in the private viewing angle of operation, the optical signal may have a narrow viewing range limited to a few tens of degrees (e.g., ±25 degrees) from a normal line incident to a surface of the display panel. While in the public viewing angle of operation, the optical signal may have a wide viewing range (e.g., ±60 degrees) about the normal line incident to the surface of the display panel.

In various embodiments, the display panel implements a thin-film transistor (TFT) display with a separate backlight source (either edge or matrix backlighting) to create the light. In other embodiments, the display panel implements an organic light-emitting diode (OLED) display that generates and presents the light used to create the optical signal. A pair of electrically switchable twisted nematic cells with opposite liquid crystal (LC) twist directions are disposed in the path of the light. The opposite liquid crystal twist directions provide self-compensation for color shifting and allow a reduction in color variations in transmittance changes between zero degrees (e.g., normal to a plane of the display panel) and approximately 45 degrees viewing angles.

The liquid crystal cells (or retarder cells) act as a switchable angular luminance shutter. Compensation layers and stack optimization layers may be included to improve angular performance and efficiency. Further reductions in the color shift may be achieved by use of wide angle type of compensated half-wave plate that may include additional compensation layers and/or alternating wave plate layers.

FIG.1illustrates a context of a platform90in accordance with one or more exemplary embodiments. The platform90generally includes an instrument panel92. The instrument panel92includes a control unit94and one or more display panels100a-100c. The instrument panel92may be implemented as part of a vehicle93. The vehicle93may include mobile vehicles such as automobiles, trucks, motorcycles, boats, trains and/or aircraft. In some embodiments, the instrument panel92may be part of a stationary object. The stationary objects may include, but are not limited to, billboards, kiosks, and/or marquees. Other types of platforms90may be implemented to meet the design criteria of a particular application.

The control unit94implements one or more display-drive circuits. The control unit94is generally operational to generate control signals that drive the display panels100a-100c. In various embodiments, the control signals may be configured to provide instrumentation (e.g., speed, tachometer, fuel, temperature, etc.) to at least one display panel100a-100c(e.g.,100a). In some embodiments, the control signals may also be configured to provide video (e.g., a rear-view camera video, a forward-view camera video, an onboard DVD player, etc.) to the display panels100a-100c. In other embodiments, the control signals may be further configured to provide alphanumeric information shown on one or more of the display panels100a-100c.

In various embodiments, the control unit94generally comprises at least one microcontroller. The at least one microcontroller may include one or more processors, each of which may be embodied as a separate processor, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or a dedicated electronic control unit.

The at least one microcontroller may be any sort of electronic processor (implemented in hardware, software executing on hardware, or a combination of both). The at least one microcontroller may also include tangible, non-transitory memory, (e.g., read-only memory in the form of optical, magnetic, and/or flash memory). For example, the at least one microcontroller may include application-suitable amounts of random-access memory, read-only memory, flash memory and other types of electrically-erasable programmable read-only memory, as well as accompanying hardware in the form of a high-speed clock or timer, analog-to-digital and digital-to-analog circuitry, and input/output circuitry and devices, as well as appropriate signal conditioning and buffer circuitry.

Computer-readable and executable instructions embodying the present method may be recorded (or stored) in the memory and executed as set forth herein. The executable instructions may be a series of instructions employed to run applications on the at least one microcontroller (either in the foreground or background). The at least one microcontroller may receive commands and information, in the form of one or more input signals from various controls or components in the platform90and communicate instructions to the display panels100a-100cthrough one or more control signals to control the displays panels100a-100c.

The display panels100a-100care generally mounted to the instrument panel92. In various embodiments, one or more of the display panels100a-100cmay be disposed inside the platform90(e.g., vehicle93). In other embodiments, one or more of the display panels100a-100cmay be disposed exterior to the platform90. One or more display panels100a-100cmay implement an active public/privacy viewing modes. One or more display panels100a-100cmay also implement the active privacy mode. As illustrated, the display panel100amay be a cluster display positioned for use by a driver. The display panel100bmay be a console display positioned for use by the driver and a passenger. The display panel100cmay be a passenger display positioned for use by the passenger and the driver.

FIG.2illustrates a schematic side view of an example implementation of a display panel100win accordance with one or more exemplary embodiments. The display panel100wmay be representative of one or more of the display panels100a-100c. The display panel100wgenerally includes a backlight source110, an optional dual brightness enhancement film (or filter)120, a bottom twisted nematic cell130, a top twisted nematic cell140, and a thin-film transistor display150.

A light160may be generated by the backlight source110in a direction normal to a face of the display panel100w. The light160is a backlight that generally illuminates the area of the dual brightness enhancement film120. The light160may or may not be polarized. An optical signal162is presented from the thin-film transistor display150. The optical signal162may be the light160spatially adjusted by the dual brightness enhancement film120, the bottom twisted nematic cell130, the top twisted nematic cell140, and the thin-film transistor display150. A first control signal170is received by the bottom twisted nematic cell130from the control unit94. The first control signal170is switchable between a first on state and a first off state. A second control signal172is received by the top twisted nematic cell140from the control unit94. The second control signal172is switchable between a second on state and a second off state. A display signal174is received by the thin-film transistor display150from the control unit94. The display signal174conveys a sequence of pictures used to modulate the light160to create the optical signal162.

The backlight source110implements an edge backlight source or a matrix backlight source. The backlight source110is operational to generate and present the light160to the bottom twisted nematic cell130.

The optional dual brightness enhancement film120(DBEF) implements a reflective polarizer used to recycle light and create brighter images in the optical signal162and wide angles. The dual brightness enhancement film120is mounted to the backlight source110and transfers the light160from the backlight source110to the bottom twisted nematic cell130. The dual brightness enhancement film120is available as 3M™ Dual Brightness Enhancement Film from THE 3M COMPANY, with headquarters located in Maplewood, MN.

The bottom twisted nematic (TN) cell130generally includes a first polarizer132, a first twisted nematic cell134, and an optional first optically clear adhesive layer136. The bottom twisted nematic cell130is adjacent to the dual brightness enhancement film120, where implemented, or the backlight source110. The bottom twisted nematic cell130is operational to switch between rotating a polarization of the light160received from the dual brightness enhancement film120/the backlight source110and passing the light160unrotated for the targeted viewing angles in response to the first control signal170.

The first polarizer132implements a linear polarizer. The first polarizer132is mounted to the optional dual brightness enhancement film120or to the backlight source110. The first polarizer132transfers the light160from the dual brightness enhancement film120or to the backlight source110to the first twisted nematic cell134. In various embodiments, the polarization of the first polarizer132may match the polarization of the backlight source110and/or the dual brightness enhancement film120.

The first twisted nematic (TN) cell134implements a liquid crystal twisted cell (or retarder cell) controlled by the first control signal170. The first twisted nematic cell134is mounted to the first polarizer132and transfers the light160from the first polarizer132to the first optically clear adhesive layer136or the top twisted nematic cell140. While the first control signal170is in a first off state (e.g., zero volts), the first twisted nematic cell134may spatially rotate the polarity of the light160received from the first polarizer132by approximately 90 degrees in a first direction (e.g., a right twist). While the first control signal170is in a first on state (e.g., one to several volts), the first twisted nematic cell134may pass the light160received from the first polarizer132without spatially altering (e.g., maintaining) the polarity at the off viewing privacy angle (e.g., the at the off viewing privacy angle the optical signal162is extinguished.

The first optically clear adhesive layer136implements a transparent glue that couples the first twisted nematic cell134to the top twisted nematic cell140.

The top twisted nematic cell140generally includes an optional third polarizer142, a second twisted nematic cell144, a second polarizer146, an optional compensated half-wave plate148, and an optional second optically clear adhesive layer149. The top twisted nematic cell140is operational to switch between rotating the polarization of the light160received from the bottom twisted nematic cell130and passing the light160unrotated at the privacy angles in response to the second control signal172.

The optional third polarizer142implements a linear polarizer. The third polarizer142is mounted to the first twisted nematic cell134by the first optically clear adhesive layer136, where implemented, or the first twisted nematic cell134. A polarity of the third polarizer142may be orthogonally aligned with the polarity of the first polarizer132. The third polarizer142transfers the light160from the bottom twisted nematic cell130to the second twisted nematic cell144.

The second twisted nematic cell144implements another liquid crystal twisted cell (or retarder cell) controlled by the second control signal172. The second twisted nematic cell144is mounted to the optional third polarizer142, the optional first optically clear adhesive layer136, or on the first twisted nematic cell134. While the second control signal172is in a second off state (e.g., zero volts), the second twisted nematic cell144may spatially rotate the polarity of the light160received from the third polarizer142by approximately 90 degrees in a second direction (e.g., a left twist). The second direction twist of the second twisted nematic cell144is generally opposite the first direction twist of the first twisted nematic cell134. While the second control signal172is in a second on state (e.g., one to several volts), the second twisted nematic cell144may pass the light160received from the third polarizer142without spatially altering (e.g., maintaining) the polarity at the privacy angles.

The second polarizer146implements another linear polarizer. The second polarizer146is mounted on the second twisted nematic cell144. The second polarizer146transfers the light160from second twisted nematic cell144to the compensated half-wave plate148. In various embodiments, the polarization of the second polarizer146may match the polarization of the first polarizer132. In various embodiments, a power efficiency may be improved by use of a reflective input polarizer for the first polarizer132and removing the second polarizer146and/or the third polarizer142.

The compensated half-wave plate148is mounted to the second polarizer146. The half-wave plate148may be operational to adjust the output polarization of the light160to match the appropriate input polarization of the thin-film transistor display150. The compensated half-wave plate148may also improve power efficiency in the optical signal162. The compensated half-wave plate148may include, for instance, alternating negative and positive half-wave plate films or additional compensation layers (e.g., negative C plate or similar). A reduction in a color shift may be achieved by use of a wide angle type compensated half-wave plate148that may include additional compensation layers and/or alternating wave plate layers. The compensated half-wave plate148transfers the light160from the second polarizer146to the thin-film transistor display150.

The second optically clear adhesive layer149implements a transparent glue that couples the compensated half-wave plate148to the thin-film transistor display150.

The thin-film transistor display150implements a transmissive display. The thin-film transistor display150is mounted adjacent to the top twisted nematic cell140. The thin-film transistor display150is operational to modulate the light160as received from the top twisted nematic cell140. The modulation may be a change in opaqueness in different areas as controlled by the display signal174. The changes in opaqueness generally modulate the intensity and the color to generate the pictures in the optical signal162. The thin-film transistor display150may be a color display or a black-and-white display. Other transmissive display technologies may be implemented to meet the design criteria of a particular application.

Each of the bottom twisted nematic cell130and the top twisted nematic cell140is electrically controlled, allowing to change the state between wide-angle fully transmissive while no voltage is applied (e.g., the OFF state/public viewing mode) and restricted viewing angle range while voltages are applied (e.g., the ON state/private viewing mode). Each of the bottom twisted nematic cell130and the top twisted nematic cell140configurations have crossed input and output polarizers. At zero volts applied across the first twisted nematic cell134and zero volts applied across the second twisted nematic cell144, the polarization is rotated by 90 degrees and the light160is transmitted through at wide viewing angles. While a voltage is applied, the liquid crystals are rearranged and the polarization rotation occurs efficiently only in the limited incidence angle range, resulting in the light160being extinguished in some viewing angles. As the first twisted nematic cell134and the second twisted nematic cell144have the opposite twist angles, the input polarization and the output polarization between the two closely match and self-compensate in color shift variations as a function of viewing angle is achieved. In various embodiments, the first control signal170and the second control signal172may be the same where both the first twisted nematic cell134and the second twisted nematic cell144are controlled simultaneously. In other embodiments, the first control signal170and the second control signal172may be generated independent of each other.

FIG.3illustrates a plan schematic diagram of an example public viewing mode200in accordance with one or more exemplary embodiments. The example is illustrated using the display panel100b. While in the public viewing mode200, the display panel100bmay present the optical signal162in a public (wide) viewing angle206allowing both a driver202and a passenger204in the vehicle93(FIG.1) to view pictures on the display panel100b. Similar public viewing modes200may be applied to the display panels100aand100c.

FIG.4illustrates a plan schematic diagram of an example private viewing mode210in accordance with one or more exemplary embodiments. The example is illustrated using the display panel100b. While in the private viewing mode210, the display panel100bmay present the optical signal162within a private (limited) viewing angle212allowing the driver202to view pictures on the display panel100b. At the same time, the display panel100bmay extinguish the optical signal162within a restricted viewing angle214directed toward the passenger204. The restricted viewing angle214is narrower than the private viewing angle212. The private viewing angle212is narrower than the public viewing angle206. Similar private viewing modes210may be applied to the display panels100aand100c. In various embodiments, the positions of the driver202and the passenger204may be switched such that the passenger204is to the left of the driver202. In some embodiments, the direction of the limited viewing angle212and the restricted viewing angle214may be reversed such that the passenger204may see the optical signal162while the driver202does not.

FIG.5illustrates a graph220of example luminance amplitude profiles for both modes of operation in accordance with one or more exemplary embodiments. The graph220generally includes an X-axis222and a Y-axis224. The X-axis222indicates an angle offset from a center normal of a display panel100a-100c. The Y-axis224indicates a relative luminance percentage as a function of the angle.

A curve230illustrates the luminance in the private viewing mode210where the display panel100a-100cis implemented with a matrix-type backlight source110. A curve232illustrates the luminance in the public viewing mode200where the display panel100a-100cis implemented with the matrix-type backlight source110.

A curve234illustrates the luminance in the private viewing mode210where the display panel100a-100cis implemented with an edge-type backlight source110. A curve236illustrates the luminance in the public viewing mode200where the display panel100a-100cis implemented with the edge-type backlight source110. A positive offset angle of the peaks of the private viewing mode curves230and234from the zero angle may be due to a liquid crystal birefringent characteristic. The birefringent characteristic means that the liquid crystal has two different indices of refraction. One index of refraction corresponds to light polarized along a director of the liquid crystal, and the other is for light polarized perpendicular to the director. In some embodiments, the offset may be moved to a negative angle by mechanically rotating the first twisted nematic cell134and the second twisted nematic cell144by 180 degrees.

FIG.6illustrates a diagram240of an example spatial luminance profile in the public viewing mode200in accordance with one or more exemplary embodiments. The diagram240illustrates a brightest luminance at a center of the profile (e.g., zero degrees). The luminance decreases spatially at greater angles in each direction. The oval shape of the profile is generally due to the rectangular shape of the display panels100a-100c.

FIG.7illustrates a diagram250of an example spatial luminance profile in the private viewing mode210in accordance with one or more exemplary embodiments. The diagram250illustrates a brightest luminance at a center of the profile (e.g., zero degrees). The luminance decreases spatially at a higher rate to one side of the center than the other side. The darker side illustrates the restricted viewing angle214(FIG.4) while the brighter side illustrates the limited viewing angle212(FIG.4).

FIG.8illustrates a graph260of an example color shift due to two twisted nematic cells with the same twist in accordance with one or more exemplary embodiments. The graph260has an X-axis262and a Y-axis264. The X-axis262indicates an angle offset from a center normal of a display panel100a-100c. The Y-axis264indicates a relative transmittance as a function of the angle. A curve266illustrates a response of blue light as a function of the angle. A curve268illustrates a response to green light as a function of the angle. A curve270illustrates a response of red light as a function of the angle. At zero degrees, a difference in the response of the red-light curve270relative to the blue-light curve266is shown by reference number272. At −45 degrees, the difference between red-light curve270relative to the blue-light curve266is shown by reference number274. In the example, the difference274is noticeably greater than the difference272.

FIG.9illustrates a graph280of an example color shift due to two twisted nematic cells with opposite twists in accordance with one or more exemplary embodiments. The graph280has the X-axis262and the Y-axis264. The X-axis262indicates an angle offset from a center normal of a display panel100a-100c. The Y-axis264indicates a relative transmittance as a function of the angle. A curve286illustrates a response of blue light as a function of the angle. A curve288illustrates a response to green light as a function of the angle. A curve290illustrates a response of red light as a function of the angle. At zero degrees, a difference in the response of the red-light curve290relative to the blue-light curve286is shown by reference number292. At −45 degrees, the difference between red-light curve290relative to the blue-light curve286is shown by reference number294. In the example, a change from the difference292to the difference294is less than the change from the difference272to the difference274shown inFIG.8.

FIG.10illustrates a schematic side view of an example implementation of a display panel100xin accordance with one or more exemplary embodiments. The display panel100xmay be a variation of the display panel100w. The display panel100xmay be representative of one or more of the display panels100a-100c. The display panel100xgenerally includes the backlight source110, a bottom twisted nematic cell130a, a top twisted nematic cell140a, and the thin-film transistor display150. The bottom twisted nematic cell130amay be a variation of the bottom twisted nematic cell130. The top twisted nematic cell140amay be a variation of the top twisted nematic cell140.

The bottom twisted nematic (TN) cell130agenerally includes the first polarizer132, the first twisted nematic cell134, a first compensation stack135, and the optional first optically clear adhesive layer136. The bottom twisted nematic cell130ais mounted to the backlight source110. The bottom twisted nematic cell130ais operational to switch between rotating a polarization of the light160received from the backlight source110and passing the light160unrotated for the targeted viewing angles in response to the first control signal170.

The first compensation stack135may include two or more layers including uniaxial positive A and positive C plates or positive and negative biaxial (B plates). The first compensation stack135is mounted adjacent to the first twisted nematic cell134. The first compensation stack135transfers the light160from the layer below to the layer above. The first compensation stack135may improve active privacy performance by reducing the transmittance at higher viewing angles.

The top twisted nematic cell140generally includes the optional third polarizer142, the second twisted nematic cell144, a second compensation stack145, the second polarizer146, the optional compensated half-wave plate148, and the optional second optically clear adhesive layer149. The top twisted nematic cell140ais operational to switch between rotating the polarization of the light160received from the bottom twisted nematic cell130aand passing the light160unrotated at the privacy angles in response to the second control signal172.

The second compensation stack145may include two or more layers including uniaxial positive A and positive C plates or positive and negative biaxial (B plates). The second compensation stack145is mounted adjacent to the second twisted nematic cell144. The second compensation stack145transfers the light160from the layer below to the layer above. The second compensation stack145may improve active privacy performance by reducing the transmittance at higher viewing angles.

The thin-film transistor display150is disposed adjacent the compensated half-wave plate148or the second optically clear adhesive layer149. The display signal174is received by the thin-film transistor display150from the control unit94. The display signal174conveys a sequence of pictures used to modulate the light160to create the optical signal162.

Each of the bottom twisted nematic cell130aand the top twisted nematic cell140ais electrically controlled, allowing to change the state between wide-angle highly transmissive state while no voltage is applied (e.g., the OFF state/public viewing mode) and restricted viewing angle state while voltages are applied (e.g., the ON state/private viewing mode). Each of the bottom twisted nematic cell130aand the top twisted nematic cell140aconfigurations have crossed input and output polarizers. At zero volts applied across the first twisted nematic cell134and zero volts applied across the second twisted nematic cell144, the polarization is rotated by 90 degrees and the light160is transmitted through at wide viewing angles. When voltage is applied, the liquid crystals are rearranged and the polarization rotation occurs efficiently only in the limited incidence angle range, resulting in the light160being extinguished in some viewing angles. As the first twisted nematic cell134and the second twisted nematic cell144have the opposite twist angles, the input polarization and the output polarization between the two closely matched and self-compensated color shift variations as a function of the viewing angle is achieved. In various embodiments, the first control signal170and the second control signal172may be the same where both the first twisted nematic cell134and the second twisted nematic cell144are controlled simultaneously. In other embodiments, the first control signal170and the second control signal172may be generated independent of each other.

FIG.11illustrates a graph300of an example improvement of the privacy viewing mode caused by the compensation stacks in accordance with one or more exemplary embodiments. The graph300includes the X-axis262and the Y-axis264.

A curve302illustrates a dual-TN-cell display panel (e.g.,100w) without the compensation stacks135and145. A curve304illustrates the dual-TN-cell display panel with a first optional compensation. A curve306illustrates the dual-TN-cell display panel with a second optional compensation. A curve308illustrates the dual-TN-cell display panel (e.g.,100x) implementing the first compensation stack135and the second compensation stack145. By adding the compensation, the transmittance in the restricted viewing angle214decreases to nearly zero above an approximately 45-degree viewing angle. By increasing the compensation, the transmittance in the limited angle212generally increases.

FIG.12illustrates a schematic side view of an example implementation of a display panel100yin accordance with one or more exemplary embodiments. The display panel100ymay be a variation of the display panels100wand/or100x. The display panel100ymay be representative of one or more of the display panels100a-100c. The display panel100ygenerally includes a bottom twisted nematic cell130b, a top twisted nematic cell140b, and an organic light-emitting diode (OLED) display152. The bottom twisted nematic cell130bmay be a variation of the bottom twisted nematic cells130and/or130a. The top twisted nematic cell140bmay be a variation of the top twisted nematic cells140and/or140a.

The optical signal162may be generated by the organic light-emitting diode display152. The first control signal170is received by the bottom twisted nematic cell130bfrom the control unit94. The first control signal170is switchable between the first on state and the first off state. The second control signal172is received by the top twisted nematic cell140bfrom the control unit94. The second control signal172is switchable between the second on state and the second off state. The display signal174is received by the organic light-emitting diode display152from the control unit94. The display signal174conveys a sequence of pictures used to create the optical signal162.

The bottom twisted nematic (TN) cell130bgenerally includes the first twisted nematic cell134, an optional first optically clear adhesive layer136, and an optional third optically clear adhesive layer138. The bottom twisted nematic cell130bis mounted to the organic light-emitting diode display152. The bottom twisted nematic cell130bis operational to switch between rotating a polarization of the optical signal162received from the organic light-emitting diode display152and passing the optical signal162unrotated for the targeted viewing angles in response to the first control signal170.

The third optically clear adhesive layer138implements a transparent glue that couples the first twisted nematic cell134to the organic light-emitting diode display152.

The top twisted nematic cell140bgenerally includes the optional third polarizer142, the second twisted nematic cell144, the second polarizer146, and the optional compensated half-wave plate148. The top twisted nematic cell140bis operational to switch between rotating the polarization of the optical signal162received from the bottom twisted nematic cell130band passing the optical signal162unrotated at the privacy angles in response to the second control signal172.

The organic light-emitting diode display152generally include an active organic light-emitting diode array154, a quarter-wave plate (QWP)156, and the first polarizer132. The organic light-emitting diode display152is mounted adjacent to the bottom twisted nematic cell130b.

The active organic light-emitting diode array154implements a two-dimensional light-emitting display. The active organic light-emitting diode array154is operational to generate the optical signal162in response to the display signal174.

The quarter-wave plate156is mounted adjacent to the active organic light-emitting diode array154. A function of the quarter-wave plate156is to rotate the light incident on the display panel, such as sunlight, and rotate the reflected light from the organic light-emitting diode display152by 180 degrees (e.g., two 90 degree rotations) and cancel the reflected components. This is done because organic light-emitting diode displays are reflective by nature.

Each of the bottom twisted nematic cell130band the top twisted nematic cell140bis electrically controlled, allowing to change the state between wide-angle fully transmissive while no voltage is applied (e.g., the OFF state/public viewing mode) and restricted viewing angle range while voltages are applied (e.g., the ON state/private viewing mode). Each of the bottom twisted nematic cell130band the top twisted nematic cell140bconfigurations have crossed input and output polarizers. At zero volts applied across the first twisted nematic cell134and zero volts applied across the second twisted nematic cell144, the polarization is rotated by 90 degrees and the light160is transmitted through at wide viewing angles. While a voltage is applied, the liquid crystals are rearranged and the polarization rotation occurs efficiently only in the limited incidence angle range, resulting in the optical signal162being extinguished in some viewing angles. As the first twisted nematic cell134and the second twisted nematic cell144have the opposite twist angles, the input polarization and the output polarization between the two closely matched and self-compensated color shift variations as a function of viewing angle is achieved. In various embodiments, the first control signal170and the second control signal172may be the same where both the first twisted nematic cell134and the second twisted nematic cell144are controlled simultaneously. In other embodiments, the first control signal170and the second control signal172may be generated independent of each other.

To improve the efficiency, the first polarizer132may be modified to be aligned (or oriented) with twisted nematic stack (e.g.,130band140b) at various angles (e.g., 45 degrees or 135 degrees). If a vertical output is specified from the display panel100y(e.g., 45 degrees or 135 degrees is not permitted) a half wave plate may be added to the stack to achieve the intended output. Additional privacy performance improvements may be achieved by incorporating additional compensation stacks (e.g.,135and145inFIG.10).

FIG.13illustrates a schematic side view of an example implementation of a display panel100zin accordance with one or more exemplary embodiments. The display panel100zmay be a variation of the display panels100w,100xand/or100y. The display panel100zmay be representative of one or more of the display panels100a-100c. The display panel100zgenerally includes the backlight source110, a bottom twisted nematic cell130c, a top twisted nematic cell140c, the thin-film transistor display150, a fourth polarizer158, and a fifth polarizer159.

The bottom twisted nematic (TN) cell130cgenerally includes a first polarizer132a, a first twisted nematic cell134a, and the optional first optically clear adhesive layer136. The bottom twisted nematic cell130cis mounted to the backlight source110. The bottom twisted nematic cell130cis operational to switch between rotating a polarization of the light160received from the backlight source110and passing the light160unrotated for the targeted viewing angles in response to the first control signal170.

The first polarizer132aimplements a linear polarizer. The first polarizer132amay be a variation of the first polarizer132(FIG.2) The first polarizer132ais mounted to the backlight source110. The first polarizer132atransfers the light160from the backlight source110to the first twisted nematic cell134. In various embodiments, the polarization of the first polarizer132amay be rotated to a first angle (e.g., 135 degrees) relative to the polarization of the backlight source110.

The first twisted nematic (TN) cell134aimplements a liquid crystal twisted cell (or retarder cell) controlled by the first control signal170. The first twisted nematic cell134amay be a variation of the first twisted nematic cell134(FIG.2). The first twisted nematic cell134ais mounted to the first polarizer132aand transfers the light160from the first polarizer132ato the first optically clear adhesive layer136or the top twisted nematic cell140c. While the first control signal170is in a first white state (e.g., zero volts of a first off state), the first twisted nematic cell134amay spatially rotate the polarity of the light160received from the first polarizer132aby approximately 90 degrees in a third direction (e.g., a normally white direction or normally bright direction). While the first control signal170is in a first black state (e.g., one to several volts or a first on state), the first twisted nematic cell134amay pass the light160received from the first polarizer132awithout spatially altering (e.g., maintaining) the polarity (e.g., a black direction or dark direction).

The first optically clear adhesive layer136implements a transparent glue that couples the first twisted nematic cell134to the top twisted nematic cell140.

The top twisted nematic cell140cgenerally includes a third polarizer142a, a second twisted nematic cell144a, a second polarizer146a, an optional compensated half-wave plate148a, and an optional second optically clear adhesive layer149. The top twisted nematic cell140cis operational to switch between rotating the polarization of the light160received from the bottom twisted nematic cell130cand passing the light160unrotated at the privacy angles in response to the second control signal172.

The third polarizer142aimplements a linear polarizer. The third polarizer142amay be a variation of the third polarizer142(FIG.2). The third polarizer142ais mounted to the first twisted nematic cell134aby the first optically clear adhesive layer136, where implemented, or directly the first twisted nematic cell134a. A polarity of the third polarizer142amay be rotated (or oriented) to a third angle (e.g., 45 degrees) relative to the polarization of the backlight source110. The third polarizer142atransfers the light160from the bottom twisted nematic cell130cto the second twisted nematic cell144a.

The second twisted nematic cell144aimplements another liquid crystal twisted cell (or retarder cell) controlled by the second control signal172. The second twisted nematic cell144amay be a variation of the second twisted nematic cell144(FIG.2). The second twisted nematic cell144ais mounted to the third polarizer142a. While the second control signal172is in a second white state (e.g., a second on state), the second twisted nematic cell144does not rotate the polarity of the light160received from the third polarizer142. While the second control signal172is in an intermediate state (e.g., partially transmitting of second off state), the second twisted nematic cell144amay pass the light160received from the third polarizer142without spatially altering (e.g., maintaining) the polarity in the angular range.

The second polarizer146aimplements another linear polarizer. The second polarizer146amay be a variation of the second polarizer146(FIG.2). The second polarizer146ais mounted on the second twisted nematic cell144a. The second polarizer146atransfers the light160from the second twisted nematic cell144ato the compensated half-wave plate148a. In various embodiments, the polarization of the second polarizer146amay have a second angle (e.g., 45 degrees) relative to the polarization of the backlight source110.

The compensated half-wave plate148ais mounted to the second polarizer146a. The compensated half-wave plate148amay be a variation of the compensated half-wave plate148(FIG.2). The compensated half-wave plate148amay be operational to adjust the output polarization of the light160to match the input polarization of the light160. A direction of polarization of the compensated half-wave plate148amay be at an angle (e.g., 22.5 degrees) relative to the polarization of the backlight source110. The compensated half-wave plate148amay also improve power efficiency in the optical signal162. The half-compensated wave plate148amay include, for instance, alternating negative and positive half-wave plate films or additional compensation layers (e.g., negative C plate or similar). A reduction in a color shift may be achieved by use of a wide angle compensated half-wave plate148athat may include additional compensation layers and/or alternating wave plate layers. The compensated half-wave plate148atransfers the light160from the second polarizer146ato the fourth polarizer158.

The second optically clear adhesive layer149implements a transparent glue that couples the compensated half-wave plate148ato the fourth polarizer158.

The thin-film transistor display150implements a transmissive display. The thin-film transistor display150is mounted adjacent to the top twisted nematic cell140. The thin-film transistor display150is operational to modulate the light160as received from the top twisted nematic cell140c. The modulation may be a change in opaqueness in different areas as controlled by the display signal174. The changes in opaqueness generally modulate the intensity and the color to generate the pictures in the optical signal162. The thin-film transistor display150may be a color display or a black-and-white display. Other transmissive display technologies may be implemented to meet the design criteria of a particular application.

The fourth polarizer158implements a linear polarizer. The fourth polarizer158is mounted to the second optically clear adhesive layer149. The fourth polarizer158transfers the light160from the second optically clear adhesive layer149to the thin-film transistor display150. In various embodiments, the polarization of the fourth polarizer158may be rotated to a fourth angle (e.g., 0 degrees) relative to the polarization of the backlight source110.

The fifth polarizer159implements a linear polarizer. The fifth polarizer159is mounted to the thin-film transistor display150. The fifth polarizer159transfers the optical signal162from the thin-film transistor display150to the driver and/or the passenger. In various embodiments, the polarization of the fifth polarizer159may be rotated to a fifth angle (e.g., 90 degrees) relative to the polarization of the backlight source110.

Each of the bottom twisted nematic cell130cand the top twisted nematic cell140cis electrically controlled, allowing to change the state between wide-angle fully transmissive viewing angle range (e.g., the public viewing mode) and restricted viewing angle range (e.g., the private viewing mode). Each of the bottom twisted nematic cell130cand the top twisted nematic cell140cconfigurations have crossed input and output polarizers. The bottom twisted nematic cell130cand the top twisted nematic cell140cmay have similar twists or opposite twists that are controlled in opposite modes of operation (e.g., normally black and normally white). The opposite modes and/or opposite twists combined together may compensate for the color shift. In addition to the opposite twists and/or opposite modes of operation, the twisted nematic cells may have different call gaps that contribute to the color compensation. In various embodiments, each of the first twisted nematic cell134/134aand the second twisted nematic cell144/144amay a single segment (e.g., full area) being in the ON state or the OFF state. In other embodiments, each of the first twisted nematic cell134/134aand the second twisted nematic cell144/144amay have multiple segments (or zones). The various segments generally allow selected areas of the thin-film transistor display150and/or the organic light-emitting diode display152to be controlled independently such that selected parts of the images may be displayed in the private mode and other parts of the images may be displayed in the public mode.

FIG.14illustrates a graph320of an example color improvement due to dual cells with different cell gaps in accordance with one or more exemplary embodiments. The graph320includes an X-axis322and a Y-axis324. The X-axis322illustrates the Gooch-Tarry condition (e.g., dn*d/lambda, where d is a cell gap (e.g., a thickness of a twisted nematic cell), do is an anisotropy of refractive index, and lambda is the wavelength of the radiation). The Y-axis324illustrates an intensity ratio.

A curve332illustrates the intensity ratio of radiation at a given twist angle as a function of the Gooch-Tarry condition. A twisted nematic liquid crystal retarder (TN1)334has a yellow color shift. In the example, the twisted nematic liquid crystal retarder334transmits red light338a, green light338b, and blue light338c. Another twisted nematic liquid crystal retarder (TN2)336has a blue color shift. The twisted nematic liquid crystal retarder336transmits red light340a, green light340b, and blue light340c.

By optimizing cell gaps of the two retarders334and336, arranged in series with opposite color shifts, a total color shift may achieve a neutral color behavior. For example, a line326illustrates an average green transmittance through the two twisted nematic liquid crystal retarders334and336. A line328illustrates an average blue transmittance through the two twisted nematic liquid crystal retarders334and336. A line330illustrates an average red transmittance through the two twisted nematic liquid crystal retarders334and336. The self-compensation may be suitable for the public viewing mode and acceptable in the private viewing mode.

The self-compensation may be applied to the display panels100w,100x,100y, and/or100z. By way of example, the bottom twisted nematic cell130(FIG.2) may be implemented as the retarder334with a first cell gap. The top twisted nematic cell140(FIG.2) may be implemented as the retarder336with a second cell gap. The first cell gap may be different than the second cell gap to provide opposing color shift that offset each other.

FIG.15illustrates a schematic side view of an example implementation of a display panel100ein accordance with one or more exemplary embodiments. The display panel100emay be a variation of the display panels100w,100x,100y, and/or100z. The display panel100emay be representative of one or more of the display panels100a-100c. The display panel100egenerally includes the backlight source110, a bottom twisted nematic cell130d, and the thin-film transistor display150. The bottom twisted nematic cell130dmay be a variation of the bottom twisted nematic cell130.

The bottom twisted nematic cell130dis operational to switch between rotating the polarization of the light160received from the backlight source110and passing the light160unrotated for the targeted viewing angles in response to the first control signal170.

The first compensation stack135may include two or more layers including uniaxial positive A and positive C plates or positive and negative biaxial (B plates). The first compensation stack135is mounted adjacent to the first twisted nematic cell134. The first compensation stack135transfers the light160from the layer below to the layer above. The first compensation stack135may improve active privacy performance by reducing the transmittance at higher viewing angles.

The bottom twisted nematic cell130dis electrically controlled, allowing to change the state between wide-angle highly transmissive state while no voltage is applied (e.g., the OFF state/public viewing mode) and restricted viewing angle state while voltages are applied (e.g., the ON state/private viewing mode). The bottom twisted nematic cell130dhas crossed input and output polarizers132and146. At zero volts applied across the first twisted nematic cell134, the polarization is rotated by 90 degrees and the light160is transmitted through at wide viewing angles. When voltage is applied, the liquid crystals are rearranged and the polarization rotation occurs efficiently only in the limited incidence angle range, resulting in the light160being extinguished in some viewing angles.

The thin-film transistor display150is mounted adjacent to the compensated half-wave plate148. The display signal174is received by the thin-film transistor display150from the control unit94. The display signal174conveys a sequence of pictures used to modulate the light160to create the optical signal162.

FIG.16illustrates a graph350of an example privacy viewing mode caused by the single twisted nematic cell with the compensation stack in accordance with one or more exemplary embodiments. The graph350includes the X-axis262and the Y-axis264.

A curve352illustrates a public viewing mode for a single-TN-cell display panel (e.g.,100e) with the compensation stack135. A curve354illustrates a private viewing mode for the single-TN-cell display panel with the compensation stack135. The compensation stack135may include combination of uniaxial retardation plates. For instance, the plates may include, but are not limited to, +A/+C and +A/+C/+A, or biaxial material.

FIG.17illustrates a diagram360of an example spatial luminance profile in the private viewing mode in accordance with one or more exemplary embodiments. The diagram360illustrates uniform luminance visibility from all viewing angles.

FIG.18illustrates a graph370of an example privacy viewing mode caused by the single twisted nematic cells without the compensation stack in accordance with one or more exemplary embodiments. The graph370includes the X-axis262and the Y-axis264.

A curve372illustrates a public viewing mode for a single-TN-cell display panel (e.g.,100e) without the compensation stack135. A curve374illustrates a private viewing mode for the single-TN-cell display panel without the compensation stack135.

FIG.19illustrates a diagram380of an example spatial luminance profile in the private viewing mode in accordance with one or more exemplary embodiments. The diagram380illustrates a luminance visibility shift at some viewing angles.

One or more of the display panels100a-100cmay implement a switchable privacy solution for thin-film transistor displays (with edge and matrix backlight) and organic light-emitting diode displays. Active privacy is achieved via means of liquid crystal retarder stack having at least one electrically switchable liquid crystal layer. In various embodiments, two switchable twisted nematic liquid crystal retarders with opposite liquid crystal twist angles are implemented. A combination of two switchable twisted nematic liquid crystal retarders provide good privacy performance. The opposing twist directions reduce the variation in color of the display panels within viewing angles of interest. In addition, compensation layers and half-wave plates may be used to optimize the power efficiency and privacy performance allowing to achieve lower power consumption than commercially available solutions.

In various embodiments, each twisted nematic cell may be configured in a normal white configuration meaning that the associated polarizer transmission axes are orthogonal relative to one another. Since the polarizer above and below the twisted nematic cell are arranged in an orthogonal configuration, the light passes through the upper polarizer and presents the light in the public mode. When power is applied for the private mode the liquid crystal molecules in the twisted nematic cell start aligning vertically. The greater the voltage, the more vertical the molecules become aligned. Because the molecules are not totally vertically aligned (due to anchoring forces), the birefringence from the liquid crystal changes as a function of angle. So for the privacy angle on one side of the display panel, the birefringence of the liquid crystal does not rotate the light and is therefore extinguished. However, on the other side of the display panel the birefringence still rotates the light. Therefore, an extent of the tilt of the liquid crystal molecules controls the amount of birefringence at each angle. For example, if a small voltage is applied to the twisted nematic cells, the peak may move to one side, but the extinguishing on the other side may not be as significant.

The present disclosure may have various modifications and alternative forms, and some representative embodiments are shown by way of example in the drawings and will be described in detail herein. Novel aspects of this disclosure are not limited to the particular forms illustrated in the above-enumerated drawings. Rather, the disclosure is to cover modifications, equivalents, and combinations falling within the scope of the disclosure.

Those having ordinary skill in the art will recognize that terms such as “above,” “below,” “front,” “back,” “upward,” “downward,” “top,” “bottom,” etc., may be used descriptively herein without representing limitations on the scope of the disclosure. Furthermore, the present teachings may be described in terms of functional and/or logical block components and/or various processing steps. Such block components may be comprised of various hardware components, software components executing on hardware, and/or firmware components executing on hardware.

The foregoing detailed description and the drawings are supportive and descriptive of the disclosure, but the scope of the disclosure is defined solely by the claims. As will be appreciated by those of ordinary skill in the art, various alternative designs and embodiments may exist for practicing the disclosure defined in the appended claims.