Audio encoding of control signals for displays

Synchronizing video content projected onto a transparent display with switching of pixels in the display. The transparent display has pixels capable of switching between a clear state to make portions of the display transparent and a hazy state to display the projected video. A decoder receives and decodes audio content associated with the video content in order to control the switching of the pixels in the display such that the video content is projected onto pixels in the hazy state.

BACKGROUND

A switchable transparent display screen is useful for attracting consumer attention and providing information to customers. While in its transparent state, it allows customers to see through the screen and view products behind it. One such type of screen uses Polymer Dispersed Liquid Crystal (PDLC), which is a mixture of liquid crystal in a cured polymer network and is switchable between light transmitting and light scattering states. PDLC displays can be divided into pixels, drawing more attention by displaying projected video content on light scattering pixels while allowing customers to view the product through light transmitting pixels. For a multi-pixel PDLC display to be functional, the pixels must be synchronized with video content such that the video content is projected onto light scattering pixels for display while the other pixels can be set to a clear state. As the video content changes, the pixels need to be reset so that the video content continues to be projected onto the light scattering pixels for display.

SUMMARY

A system for synchronizing projected video content with a transparent display, consistent with the present invention, includes a projector for projecting video content having associated audio content and a transparent display for receiving and displaying the projected video content. The transparent display has pixels capable of switching between a clear state to make portions of the display transparent and a hazy state to display the projected video. A decoder receives and decodes the audio content in order to control the switching of the pixels in the display with the projected video content such that the video content is projected onto pixels in the hazy state.

A method for synchronizing projected video content with a transparent display, consistent with the present invention, comprises projecting video content having associated audio content to a transparent display and displaying the projected video content on the transparent display. The method also includes decoding the audio content in order to control the switching of the pixels in the display between clear and hazy states such that the projected video content is projected onto pixels in the hazy state.

DETAILED DESCRIPTION

Embodiments of the present invention include a method of encoding a control signal using audio tones. This signal can be sine or square waves with the frequency of the waves determining the data set being sent. The frequency can be in the ultrasonic range to send data faster and free the audio line for traditional use of providing audio with video. This signal can also be a series of DTMF (dual-tone multi-frequency) tones. Each tone, or series of tones, can represent a different set of data. Using stereo audio allows for more data to be transmitted or for error correction to be performed. The control signal can be used to encode pixel data in segmented transparent displays.

An example of a transparent display is described in U.S. patent application Ser. No. 13/675,121, entitled “Switchable Transparent Display,” and filed Nov. 13, 2012, which is incorporated herein by reference as if fully set forth.

FIG. 1is a block diagram of a system10for audio encoding of data. System10includes a decoder12for decoding audio signals to provide a synchronization signal for a segmented transparent display. Decoder12includes a processor20, or controller or circuitry, for decoding signals. A memory21can store software instructions for execution by processor20. The audio signal can be square waves with the frequency of the waves determining the active pixels. The audio signal can also be a sine wave. Pixel information can be encoded in sine waves using several methods. Encoding can be done using a single frequency for each pixel arrangement. It can also be encoded using DTMF tones. Each DTMF tone, or series of tones, can represent one pixel state. Additionally, a series of tones can play at the beginning of a video and contain data for synchronized pixel switching for the duration of the video, enabling sound to be played with the corresponding video. A sine or square wave14is provided to a comparator16, which generates a corresponding digital square wave18.

Processor20received digital square wave18and decodes it to produce a pixel data output signal26. Alternatively or in addition, processor20receives DTMF tones24and decodes the tones to generate pixel data output signal26.

FIG. 2is a block diagram illustrating synchronizing a transparent display with video using audio encoding of data. A projector30projects content31for display on a transparent display32such as a PDLC display. A video and audio source34provides the video content with associated audio content to projector30for projection onto transparent display32. The audio content from video and audio source34is decoded to provide decoded audio36, corresponding with pixel data output26, which is used to synchronize transparent display32with the video content projected upon it. As used herein, “video content” includes still images as well as moving images.

PDLC displays have pixels that can be switched to transmit light in a clear state, or scatter light in a hazy state. In the clear state, the pixels are sufficiently transparent to permit a viewer to see through those pixels of the display. In the hazy state, the pixels are sufficiently opaque for a viewer to see the video content projected upon those pixels of the display. The term “pixel” includes any particular portion or segment of the display. The display may have one or more pixels.

The pixels of the PDLC display must match the video content so that the video content is projected onto pixels having the hazy state. When creating video content, the encoded pixel data is recorded on the audio track of the video in video and audio source34. When the video is played back with the video content projected onto transparent display32, the encoded data will be played as an audio track, and decoded audio36is used to control switching of pixels in transparent display32such that the projected video is displayed on pixels in the hazy state. Preferably, decoded audio36is also used to set the pixels not receiving the projected video to the clear state.

FIG. 3is a flow chart of a method40for audio encoding of data. Method40can be implemented in software, for example, for execution by processor20in system10. In method40, the system waits for audio input (step42), which the system receives from the audio content in video and audio source34. When receiving audio input, the system counts the number of rising edges of the signal over a short period of time (step44). As the frequency increases, the counts increase accordingly. Each count is correlated to a specific pixel pattern (step46). Based upon the correlated counts, a digital high signal is output to switch a particular pixel on in transparent display32, and a digital low signal is output to switch a particular pixel off in transparent display32(step48). The method repeats to continue decoding audio signals for synchronizing the projected video content from video and audio source34with the switching of pixels in transparent display32.

Table 1 illustrates correlating pixel counts with pixel patterns and the on and off states for the pixels in each pattern. This correlation can be stored in memory, such as memory21, for retrieving the corresponding pixel patterns to synchronize the display with video content. In the pixel states, the particular pixel patterns can specify the (x, y) positions of the pixels to turn on as represented by pixels(x, y) and the (x, y) positions of the pixels to turn off as represented by pixels(x′, y′). As the projected video is displayed on the transparent display, the pixel patterns can change, as determined by the counts, to continue to display the projected video onto pixels in the off (hazy) state.

FIG. 4is a diagram illustrating use of audio encoded data to control switching of pixels in a transparent display. A transparent display50is has pixels in a background portion52and a ring portion54both set to a hazy state to display video content, while pixels in ring portion53and center portion56are set to a clear state. As the video changes, pixels in background portion52are still set to the hazy state and pixels in53are still set to a clear state, but pixels in ring portion54are now set to a clear state while pixels in center portion56are set to a hazy state to display video content in center portion56instead of ring portion54. The configurations of pixels in clear and hazy states in the example ofFIG. 4can be stored as pixel patterns as illustrated in Table 1 and corresponding with particular counts.

Table 2 includes an example of BASIC code for implementing method40. For example, the code in Table 2 can be stored in a memory associated with decoder12, such as memory21, for execution by processor20.