Patent Application
20160327853
Embodiments of the subject matter described herein relate generally to active window display systems and, more particularly, to an active window display system that is not visible from outside a vehicle.
Active window display systems (AWDs) are of interest for a variety of aerospace, military, automotive, industrial and consumer applications. An AWD system generates, on a window, a display or image that is essentially transparent, having a see-through attribute. The AWD system is mounted or laminated on a vehicle window and the display or image may be, for example, the mission information for a military ground vehicle, an aircraft or an automobile.
In many such applications, there is a need for the AWD system to not only display an image that is see-through to the crew viewing it from inside a vehicle, but to provide additional features, such as control and security over the displayed image with respect to the outside of a vehicle, or backside of the display. For example, it is desirable for the image view inside the vehicle to be wide-angle, for cross-cockpit viewing, and to be readable even against sunlight illumination. Additionally, it is desirable for the displayed image to not be visible from outside the vehicle (i.e., the backside of the AWD). It would be further desirable for the AWD system to capably switch from being transparent to being opaque, to block the optical emissions from escaping the vehicle.
The desired AWD features would enable increased situational awareness and safety for a crew. The present invention provides the desired features.
This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description section. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
A display system is provided. The display system comprises a projector configured to project a first wavelength of light, and a transparent screen assembly having a first surface and a second surface. The transparent screen assembly is configured to, in response to receiving the first wavelength on the first surface, emit a second wavelength from the first surface and block transmission of the first wavelength and second wavelength from the second surface.
Another display system is provided. The display system comprises a projector configured to project at least one excitation wavelength to create at least one of a (i) red light emission wavelength, (ii) green light emission wavelength and (iii) blue light emission wavelength on a first surface of a transparent screen assembly. The display system also comprises a transparent screen assembly comprising a first surface and a second surface, the transparent screen assembly is configured to, in response to receiving the excitation wavelength, emit a respective second wavelength comprising at least one of a (i) red light emission wavelength, (ii) green light emission wavelength, and (iii) blue light emission wavelength on the first surface, and block transmission of the respective second wavelength and the corresponding excitation wavelength from the second surface while allowing other wavelengths of light to pass through the transparent screen assembly.
Yet another display system is provided. The display system comprises a projector configured to project polarized light with a first output polarization, and a partially transparent screen assembly. The partially transparent screen assembly comprises a scattering polarizer defining a first surface, and an absorbing polarizer defining a second surface and coupled to the scattering polarizer. A rejection axis of the scattering polarizer and a rejection axis of the absorbing polarizer are parallel to each other and perpendicular to a rejection axis associated with the first output polarization. The transparent screen assembly is configured to, in response to receiving the polarized light with the first output polarization on the first surface, (i) backscatter the polarized light with the first output polarization from the first surface, and (ii) block the polarized light with the first output polarization from the from the second surface.
Other desirable features will become apparent from the following detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.
A more complete understanding of the subject matter may be derived by referring to the following Detailed Description and Claims when considered in conjunction with the following figures, wherein like reference numerals refer to similar elements throughout the figures, and wherein:
The following Detailed Description is merely exemplary in nature and is not intended to limit the embodiments of the subject matter or the application and uses of such embodiments. As used herein, the word “exemplary” means “serving as an example, instance, or illustration.” Any implementation described herein as exemplary is not necessarily to be construed as preferred or advantageous over any other implementations. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding Technical Field, Background, Brief Summary or the following Detailed Description.
For the sake of brevity, conventional techniques related to known graphics and image processing, sensors, and other functional aspects of certain systems and subsystems (and the individual operating components thereof) may not be described in detail herein. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in an embodiment of the subject matter.
Techniques and technologies may be described herein in terms of functional and/or logical block components and with reference to symbolic representations of operations, processing tasks, and functions that may be performed by various computing components or devices. Mechanisms to control features such as the projector 102 and/or an electro-optic shutter 206 such as an electro-chromic window film, or a liquid crystal optical shutter/light valve may utilize processors and memory. Such operations, tasks, and functions are sometimes referred to as being processor-executed, computer-executed, computerized, software-implemented, or computer-implemented. In practice, one or more processor devices can carry out the described operations, tasks, and functions by manipulating electrical signals representing data bits at memory locations in the processor electronics of the display system, as well as other processing of signals. The memory locations where data bits are maintained are physical locations that have particular electrical, magnetic, optical, or organic properties corresponding to the data bits. It should be appreciated that the various block components shown in the figures may be realized by any number of hardware, software, and/or firmware components configured to perform the specified functions. For example, an embodiment of a system or a component may employ various integrated circuit components, e.g., memory elements, digital signal processing elements, logic elements, look-up tables, or the like, which may carry out a variety of functions under the control of one or more microprocessors or other control devices.
The following descriptions may refer to elements or nodes or features being “coupled” together. As used herein, and consistent with the discussion hereinabove, unless expressly stated otherwise, “coupled” means that one element/node/feature is directly or indirectly joined to (or directly or indirectly communicates with) another element/node/feature, and not necessarily mechanically. Thus, although the drawings may depict one exemplary arrangement of elements, additional intervening elements, devices, features, or components may be present in an embodiment of the depicted subject matter. In addition, certain terminology may also be used in the following description for the purpose of reference only, and thus are not intended to be limiting.
The embodiments described herein are merely examples and serve as guides for implementing the novel systems and methods on any window in any avionics, astronautics, terrestrial, or water application. As used herein, an “image” includes one to a plurality of wavelengths of light in a predetermined pattern. The image may include any combination of symbology, alphanumeric information, video, and/or figures. It is readily appreciated that the relevant windows are also designed to meet a plurality of environmental and safety standards beyond the scope of the examples presented below. As such, the examples presented herein are intended as non-limiting.
The projector 102 is a source that projects an image, as individual narrow wavelength bands of light (hereinafter, the individual narrow wavelength bands of light may be referred to as just “wavelengths”). The projector 102 may be under electronic and/or mechanical control and may employ various methods for projecting individual frames of an image. Accordingly the projector 102 may be responsible for creating an image, may be adjusted to have a brightness that maintains display visibility in the presence of sunlight or other ambient light, and may employ various synchronized shuttering techniques. In some embodiments, the projector 102 may employ a polarizer prior to projection, such that the projected image has an output polarization (
In response to reception of the first wavelength 106 at the first surface 108 of transparent screen assembly 104, a second wavelength 112 is emitted from the first surface 108. The second wavelength 112 may or may not be substantially the same as the first wavelength 106. Ambient wavelengths of ambient light 114, excluding the “target” first wavelength 106, pass through the transparent screen assembly 104. From the perspective of the second surface 110 of transparent screen assembly 104, which is often the “outside” of a vehicle or backside of a display, (excitation) first wavelength 106, and the (emission) second wavelength 112 are blocked and are therefore not passed through or transmitted.
The projection screen 202 provides color-compatible transparency from the perspective of the first surface 108 (i.e., viewing the first surface from, typically, the inside of a vehicle). In order to provide this color transparency, the projection screen 202 may comprise embedded particles 208. The embedded particles 208 are excited by a received wavelength (referred to herein as the first wavelength 106) and emit a wavelength in response, the emitted wavelength is referred to herein as the second wavelength 112. The embedded particles 208 may comprise fluorescent nanoparticles or molecules. In an alternative embodiment, embedded particles 208 comprise resonant scattering nanoparticles. In yet another embodiment the particles may comprise of quantum dots (QD) tuned for narrow band red, green and blue emissions. Although the emission of second wavelength 112 is shown as unidirectional, coming from the first surface, in practice, emission is typically two or three-dimensional, and the second surface may have a filter screen 204 to prohibit the emission of second wavelength 112 and/or the transmission of first wavelength 106 and second wavelength 112 from the second surface 110 (i.e., from the backside of the AWD or outside of the vehicle).
As mentioned above, while the discussion herein references spectral content such as first wavelength 106 as a singular wavelength, it is to be understood that a wavelength so described is the “individual narrow wavelength band of light” introduced earlier, which will typically involve a spectral band or wavelength range of finite bandwidth, as is well known in the art. The desired spectral bandwidth of each wavelength is application specific and may vary depending upon the properties of the involved projector and/or screen mechanism. In the embodiments described thus far, a relatively narrow spectral bandwidth is generally preferable.
A filter screen 204 may comprise any of several varieties of wide-field-of-view narrow band notch or multi-notch absorption or reflection filters. Wide-field-of-view narrow band multi-notch reflection filters are described in connection with
In various embodiments, the filter screen 204 comprises one of (i) absorbing and non-radiative nanoparticles tuned to the first (excitation wavelength) and second (emission) wavelength, (ii) absorbing and non-radiative Quantum Dot (QD) embedded film tuned to the first and second wavelengths, and (iii) film with photonic crystals tuned to the first and second wavelengths. Excitation wavelengths are predominantly in the long wavelength UV band (UVA), or just below blue wavelength band. The filter screen 204 is designed primarily to filter the emitted visible wavelength (red, green or blue), and the small fraction of the excitation wavelength that does not participate in the excitation (down-conversion) process. In some embodiments, such as those employing a resonant nanoparticle projection screen 202, the excitation (projected) wavelength and the scattered wavelength are same. The filter screen 204 is designed to selectively block the projected image wavelengths while allowing all the other wavelengths to pass through. The varieties of filter screens 204 described herein are tuned to one or more respective “target” wavelengths.
Wide-field-of-view narrow band multi-notch absorption filters include those that employ tuned, absorbing and non-radiative nanoparticles; tuned, absorbing and non-radiative Quantum Dot (QD) embedded films; films with meta-material devices such as photonic crystals; and narrow band dichroic or non-dichroic dyes. Spectral absorption properties of many of these examples can be further enhanced or modified by incorporating them within or in conjunction with tuned multi-layer dielectric structures. Although each of the narrow band multi-notch absorption filters operates slightly differently, each achieves substantially similar absorption objectives with regard to absorbing, or “blocking” one or more target wavelengths, as described in connection with
Optional electro-optic shutter 206 may be coupled to the first surface 108 or second surface 110 of the transparent screen assembly 104 in various embodiments of the active window display system 200. Electro-optic shutter 206 may be electro-chromic window film, known in the art to switch between the quality of being substantially opaque and the quality of being at least partially transparent, transmitting wavelengths of light, responsive to an applied voltage. In various embodiments, electro-optic shutter 206 may be used to adjust to day and/or night scenarios, for example by attenuating the apparent lighting levels of either side as seen from the opposite side, or to completely secure a window and prevent optical transmissions of an image viewable from the inside a vehicle to the outside of a vehicle (i.e., backside of a display). While known electro-chromic materials and devices are one exemplary approach for switchable opacity windows, the term “electro-chromic” films or layers as used herein is intended to include other compatible structures having electrically tunable transmittance, such as various types of liquid crystal (LC) light valves or similar. Similarly, the term “window film” is intended to be inclusive of thin layer structures which may require support substrates, such as certain types of LC light valves.
Although the electronic controls for the electro-optic shutter 206 are not the subject of the present invention, it is readily appreciated that an electro-optic shutter 206 may operate on a shutter speed, having a corresponding response time, and that such shuttering speed may be coordinated with a shuttering speed of projector 102, as is suitable for an intended application. In practice, the electro-optic shutter 206 may have a shutter speed in the millisecond or sub-millisecond range, as required to support field sequential operations and/or shuttering operations with a projector 102, as described in connection with
A reflective filter blocks transmission of a target wavelength by reflecting at the target wavelength (i.e., the reflective filter is tuned to the target wavelength). In the embodiment shown, the target wavelengths for reflectance are depicted along the x-axis 304. It is readily observable that reflectance 318 is aligned at wavelength 303, reflectance 320 is aligned at wavelength 305, and reflectance 322 is aligned at wavelength 307. As used herein, the filter is considered “tuned” to the target wavelength when a reflection filter wavelength is aligned with a target wavelength as shown. Although
An absorption filter blocks transmission of a wavelength by absorbing light at a “target” wavelength (i.e., the absorption filter is tuned to the target wavelength). In the embodiment shown, the target wavelengths for absorption are depicted along the x-axis 414. It is readily observable that absorption 402 is aligned at wavelength 303, absorption 404 is aligned at wavelength 305, and absorption 406 is aligned at wavelength 307. Although
In the
The scattering polarizer 502 scatters (or rejects) one polarization of the image along a rejection axis 504 but transmits another. By selectively polarizing the projector 102 to match the rejection axis 504 of the scattering polarizer 502, a portion of the transmitted image will be backscattered to a viewer viewing the first surface. An absorbing polarizer 510 is utilized as a second surface 110 of the scattering polarizer 502 to, upon receiving the polarized light from the projector 102, backscatter the light from the first surface 108 and absorb transmitted light from the second surface 110, thereby absorbing/blocking the projected and forward-scattered portion of the scattered polarization, preventing it from being viewed from the backside of the AWD, or the second surface 110. Ambient light 114, having wavelengths with an orthogonal polarization (orthogonal to the rejection axis 504, 508 of the absorbing polarizer 510 and scattering polarizer 502) are transmitted in both directions without being substantially scattered, blocked, or absorbed.
The scattering polarizer 502 in the
Additionally, optional variations are possible to improve properties such as transmittance efficiency, leakage of unwanted light, and the like. One skilled in the art will further recognize that various polarization manipulation techniques, such as the use of birefringent films and retarders to enable relative rotations of the polarizers, can be used without changing the intended functionality of the disclosed approach. For example, the polarization-based approach in
In another embodiment, instead of coupling the optional electro-optic shutter 206 to the second surface 110 of the transparent screen assembly 104, the electro-optic shutter 206 may be coupled to either side of an included filter screen 204. In yet another embodiment, a polarization rotating film may be used in place of or proximate optional reflective polarizer 506, between scattering polarizer 502 and absorbing polarizer 510, allowing the physical orientation of an axis 512 to be changed while still maintaining an effectively parallel relationship with axis 504.
Various embodiments may have temporal filtering aspects, as described in connection with
In an embodiment, subframe 812 is associated with blue light, subframe 810 is associated with green light, and subframe 808 is associated with red light. Each subframe 808, 810, and 812, may be cycled “on” for a respective duration of time 814, and “off” for duration of time 816. As in
Thus, an AWD system that provides more control and security over the displayed image with respect to the outside of a vehicle, or backside of the AWD is provided. The AWD system provides a wide-angle image for cross-cockpit viewing that is readable against sunlight illumination. The displayed image in the AWD is not visible from outside the vehicle (i.e., the backside of the AWD). The AWD further capably switches from transmitting wavelengths to being opaque, to block the optical emissions from escaping the vehicle.
While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or embodiments described herein are not intended to limit the scope, applicability, or configuration of the claimed subject matter in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the described embodiment or embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope defined by the claims, which includes known equivalents and foreseeable equivalents at the time of filing this patent application.
