Visible light communication has received attention recently due to the growing application of solid state lighting devices, which makes them candidates for ubiquitous communication vehicles. On the other hand, the ubiquitous visual display devices, such as television and digital signage, are only communicative in the traditional sense by conveying visual imagery. Increasingly, these displays are adding other data or information overlaid on the main video content, such as Quick Response (QR) codes in addition to traditional overlaid information such as scrolling information bars. All of this additional data can be intrusive and space-consuming when combined with the video content. Accordingly, a need exists for ways to convey information via an electronic display in addition to displayed video or other content.
A system for augmenting displayed content, consistent with the present invention, includes a display module, first and second backlight modules, and a controller. The first backlight module provides visible light to the display module, and the second backlight module provides only invisible light to the display module. The controller provides first and second frames of content to the display module in a time sequential manner with the first frames of content backlit by the first backlight module and the second frames of content backlit by only the second backlight module.
A method for augmenting displayed content, consistent with the present invention, includes providing to a display module first frames of content backlit by a first backlight module, providing to the display module second frames of content backlit by only a second backlight module, and alternating the first and second frames of content provided to the display module in a time sequential manner. The first backlight module provides visible light to the display module, and the second backlight module provides only invisible light to the display module.
A first method for receiving augmented displayed content, consistent with the present invention, includes receiving first frames of visible content from a display module, receiving second frames of only invisible content from the display module and alternating with the first frames in a time sequential manner, and displaying the first frames of visible content. Information is retrieved based upon the second frames of invisible content, and the retrieved information is provided with the first frames of visible content.
A second method for receiving augmented displayed content, consistent with the present invention, includes receiving first frames of visible content from a display module, and receiving second frames of only invisible content from the display module and alternating with the first frames of visible content in a time sequential manner. The method also includes receiving a selection relating to the first and second frames of content and displaying, based upon the selection, either the first frames of visible content or the second frames of invisible content as visible content.
The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, explain the advantages and principles of the invention. In the drawings,
Embodiments of the present invention use field sequential backlights to implement temporal and spectral multiplex transmissions of invisible information, for example infrared, and visible information through an LCD module or other type of backlit display. The visible information, such as color video or images (RGB images), are displayed by the LCD module. The invisible information, encoded as infrared information for example, is provided by the LCD module by being backlit by only an infrared backlight. The visible and invisible information are provided in frames of content, alternating in a time sequential manner. While the invisible information is not visible to a viewer of the LCD module, the invisible information can be detected by an infrared camera, or other sensor, and used to augment the visible information. For example, the invisible information can include a link used to retrieve visual content to be displayed overlaid or along with the visible information, or a link to retrieve audio content to be provided along with the visible information. In this manner, the same display can be used to provide augmented information along with visible information.
The timing diagram illustrates switching of the backlights such that the odd frames (visible information) are only backlit by the RGB backlight, and the even frames (invisible information) are only backlit by the infrared backlit. Alternatively, since the infrared backlight emits light not within the visible spectrum, the infrared backlight can optionally be left on while the odd frames (visible information) are backlit by the RGB backlight with the RGB backlit being switched off while the even frames (invisible information) are backlit by the infrared backlight. The odd and even frames are switched at a sufficiently high rate such that the switching is not visibly perceptible to a viewer of the displayed visual content. The visible and invisible information are referred to as odd and even frames, respectively, for reference purposes only, and the visible information can be in even frames with the invisible information in odd frames, or the visible and invisible information can be within frames referred to as left and right frames. The term “frame” means a full frame of odd and even information or content for a particular display or any partial frame of the data on the display.
Visible information or content means information or content within the visible spectrum of light, and invisible information or content means information or content not within the visible spectrum of light. The visible and invisible frames are provided to the LCD module in a temporal manner, meaning one or more visible frames alternate with one or more invisible frames in a time sequential manner. For example, one invisible frame can alternate with one visible frame to provide the augmented information as a monochromatic image or video. Alternatively, three invisible frames corresponding with the red-green-blue components of the augmented information can alternate with one visible frame to reconstruct and provide the augmented information as a color image or video.
The backlights can be implemented with, for example, an edge-lit backlight having an RGB light source on one edge and the infrared light source on an opposing edge, or with a hybrid backlight having both RGB and infrared light sources together with the RGB and infrared light sources separately controlled by a backlight driver. Alternatively, the backlights can be any backlight capable of separately providing visible light and infrared (or other invisible) light. The RGB backlight can use, for example, red, green, and blue LEDs to provide a white backlight. The infrared backlight can use, for example, LEDs emitting infrared light and not emitting light within the visible spectrum. When an infrared backlight is used to provide the invisible information or content, the invisible information or content is primarily transmitted through the red sub-pixel (red color filter) within the LCD module, as illustrated in
More particularly, in typical LCD devices the red color filters have high transmittance in the near infrared spectral region and, as a result, data-modulated infrared light can pass through the red filter. Augmented information can thus be encoded with only the red component while maintaining both the green and blue components at constant level (for example zero), since any infrared light information carried by green and blue sub-pixels is blocked by their corresponding band-pass color filters.
One factor for encoding augmented information is the wavelength of the infrared LED, which can determine the optical characteristics of the infrared illuminated imagery through the light modulator portion of the LCD panel stack-up, including a pair of crossed linear polarizers and a layer of liquid crystal molecules. Although it is possible to devise components to match a particular wavelength, it is preferred that the wavelength is selected to work with LCD components, or other backlit displays, designed to work with visible light. Based upon the spectral absorption of an OCB (optically compensated bend) and a TN (twisted nematic) LCD panel, the wavelength range of 720 nm-760 nm provides a reasonable balance between good contrast ratio of infrared content and good rejection of visible light. Also, there is strong dioxygen (O2) absorption of solar radiance at 760 nm, which can help to reduce the interference from daylight in outdoor applications.
The augmented information in the invisible frames can include visual content such as images, video, or textual information, and metadata or links to information. The links can include, for example, a network address such as uniform resource locator (URL) or other network identifier used to electronically access remote information or content, for example content on a server accessed by a processor-based device via a network such as the Internet or other computer-based network. These links can be represented by, for example, codes such as a QR code or other indicia capable of being detected by an infrared camera or other sensor for obtaining the provided invisible information.
The augmented information can include descriptive metadata or links embedded as invisible information along with visual information. For example, the augmented data can include a menu, or link to a menu, embedded within a digital sign and to be displayed on a user's mobile device. When the main content is digital signage or advertising displaying electronic images or video, the augmented embedded information can include information related to the displayed information or to the advertised products or services. For example, the augmented embedded information in the digital signage can include a QR code with a link to a digital coupon or other information. As another example, the augmented embedded information can include the text displayed on the digital signage translated into another language. When the augmented embedded information includes a link to audio information, the audio can be used as an audio guide within a museum, for example, or other facility.
The user's mobile device has coordinates XMobile, YMobile, ZMobile. Augmented information display 116 provides embedded invisible positional information as a two-dimensional (2D) codes or markers, for example. Mobile device 118 can detect these codes using an infrared camera, for example, to determine the location of augmented information display 116. Once the 3D position vector of the camera in mobile device 118 relative to augmented information display 116 (PDcamera) is obtained, the 3D position of the camera in the local coordinate system (PLcamera), for example within a building, can be calculated based upon the position of augmented information display 116 (PLDisplay) and the position of the camera (PDcamera) according to the calculation PLCamera=PLDisplay PDCamera.
When a local or server-based map of a local environment is available, the position PLCamera can be used to position the mobile user within the map or be used as the calibration reference for further navigation. Optionally, the global position of the camera, for example using GPS, can also be calculated and used in the navigation. An example of a software application for determining pose estimation data of a camera based upon a captured fiduciary marker is the ARToolKit for use in developing augmented reality (AR) applications from ARToolworks, Inc. The invisible positional information provided by augmented information display 116 can include such a fiduciary marker.
Augmented information display and positioning and navigation system 90 can provide a way to embed navigational (or positioning) markers for marker-based indoor positioning and navigation, for example in locations where GPS does not work well. The invisible navigational information is used as a dynamic 2D marker capable of being electronically changed to indicate different positions. With augmented information display 116 having a known location, the invisible embedded markers can be used to calculate the relative position and angle (orientation) of the mobile device decoding the marker and provide, for example, information to the user for navigating an indoor space such as a shopping mall. The term “navigational information” means information relating to a user's position, and optionally orientation, relative to an augmented information display. The user's position is considered to be a position of a mobile device, or other device, detecting the invisible navigational information provided by the augmented information display.
System 136 includes a receiving and demodulation module 138 for receiving the transmitted combined content. A demultiplexer 140 separates the main content from the augmented content to provide main broadcast audio/video content 144 via an encoder 142 and augmented video content 148 via an encoder 146. An augmented information display system 150, which corresponds with system 10, displays main broadcast audio/video content 144 as visible frames and provides augmented video content 148 as invisible frames. A user interface 154 or other remote control device can allow a user via a user control module 152 to view the main broadcast audio/video content or the augmented video content.
Examples of communication aid information include sign language videos, subtitles shown as textual information, and audio information. Users desiring to receive the augmented communication information can have their own displays separate from the augmented information display providing the main content, instead of or in addition to overlaying sign language or subtitles on the displayed main content. The embedded augmented communication information can include a database of links to sign language videos for phrases displayed on the augmented information display, as represented in Table 1. The subtitles can include textual information in a variety of language relating to the displayed main content. The augmented audio information can be used, for example, in a setting where individual viewers of the displayed main content can receive the audio content associated with the main content without broadcasting the audio content to the entire audience.