Patent Application
20110254932
Embodiments of the present invention relate generally to stereoscopic imaging, and more specifically, to stereoscopic video displays for use in conjunction with specialized eyewear.
The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:
Embodiments of the present invention are not limited in their application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. Embodiments of the present invention are capable of other embodiments and of being practiced or of being carried out in various ways. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” “having,” “containing,” “involving,” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.
Stereoscopic (three-dimensional or “3D”) images are produced in pairs, each image of the pair representing a scene presented at slightly different angles that correspond to the angles of vision of each human eye. For displaying stereoscopic images, various techniques involving simultaneous or synchronous projection of left and right field of view images have been developed. In one technique, different images, one for each field of view, are rapidly displayed in alternating succession in conjunction with specialized eyewear to be worn by a viewer. The eyewear may be active eyewear having, for example, LCD shutter lenses. The eyewear is coupled to the television system, and each lens is alternately switched between clear (e.g., “open”) and opaque (e.g., “closed”) in synchronization with the frames of a movie, video, or other 3D image that is displayed using the alternating field of view technique. Accordingly, the left lens is open and the right lens is closed while a left eye field of view image is displayed, and the right lens is open and the left lens is closed while a right eye field of view image is displayed. This permits the displayed image to be seen by only one eye at a time.
Embodiments of the present invention are generally directed to systems and methods for displaying and viewing stereoscopic images with active eyewear. With the advent of home theater systems, it is appreciated that consumers may enjoy viewing 3D movies using television systems adapted for such use. According to various embodiments of the invention, liquid crystal display (LCD) televisions, for example, are one popular type of television that may be so adapted. As used herein, “LCD” refers to the underlying screen of a display, for example, thin film transistor LCD (TFT-LCD). It should be understood, however, that various embodiments of the present disclosure may be implemented on other types of transmissive or emissive displays, including, but not limited to, TFT-LCD, Organic Light Emitting Diode (OLED), devices incorporating certain microelectromechanical systems (MEMS), plasma display panels (PDP), and the like.
According to one aspect of the present invention, a series of stereoscopic images are presented on a television display in a field sequential manner. One field provides the viewing perspective of the left eye, and another field provides the perspective of the right eye. For instance, successive frames of the image series may comprise alternating left and right fields of view for generating an illusion of depth in conjunction with specialized eyewear, such as the shutter lenses described above. A viewer wears the eyewear which alternately transmits and blocks light going to each eye. Each displayed image is steered to the correct eye by synchronizing the eyewear lenses with the display. For example, when a left field of view image is displayed, the left lens is unblocked and the right lens is blocked to steer the displayed image to the viewer's left eye only. Furthermore, when a right field of view image is displayed, the right lens is unblocked and the left lens is blocked to steer the displayed image to the viewer's right eye only.
According to various embodiments, a television using progressive or non-interlaced scanning is configured for displaying 3D programs and movies. Such a television includes a display having a plurality of picture elements (also referred to herein as pixels) that are sequentially updated, for example, in a raster or other sequential scanning pattern, such as row-by-row beginning at the top-left corner of the display and ending at the bottom-right corner. In a progressive scan television, an update of the entire image (or field of view) occurs over a non-zero time interval (e.g., about 8 ms for a 120 Hz LCD TV) because each pixel of the display is updated sequentially, rather than simultaneously. As a result, at certain times during the course of an image update, one region of the TV screen may display a portion of the previous image while the other, most recently updated region, simultaneously displays a portion of the current image. This causes crosstalk between the left and right eyes when using an alternate-frame display sequence because the viewer may simultaneously observe portions of both the left and right fields of view with the same eye. These visual artifacts are disconcerting to the viewer, and also detract from the 3D effect.
One technique for reducing the effect caused by the artifacts includes only opening the shutter lens during a blanking (e.g., non-update) interval that occurs between each full-frame update so that the viewer does not see a partially updated image. The blanking interval may be, for example, as long as the scan time, or full-frame update time, of the display, or less. In an alternate technique, a television light source is dimmed, lessened or extinguished (e.g., the light level is decreased or reduced) during the update scan to obscure the artifacts from the viewer, and the display is illuminated only during the blanking interval. These techniques may cause undesirable flickering and/or may reduce the effective brightness of the display, particularly in a display having a 120 Hz update rate, because the viewer is only able to see the image for a brief period of time after each update is completed. The flickering may be reduced and/or the brightness increased by increasing the rate at which the display is updated, for example, to 240 Hz or greater. However, televisions with faster update rates are more expensive to produce.
According to one embodiment of the invention, an electronic visual display system for displaying stereoscopic images includes a display screen for displaying an image. In one non-limiting example, the display screen may be sequentially updatable. The display screen is partitioned into at least two contiguous regions having substantially equal areas. For instance, a television screen may be divided into a top half (e.g., a first region) and a bottom half (e.g., a second region). It will be understood that regions of differing locations and areas may be used according to a particular application (e.g., a left half and a right half, or a top third, middle third, and bottom third, etc.). Each region is separately and independently illuminated by one or more light sources. For example, the first region may be illuminated by a first light source and the second region may be illuminated by a second light source. Alternatively, a single light source may be configured to illuminate the first region and the second region separately, using, for example, light shutters or other light blocking devices. In certain embodiments, light guides may be used to transmit the light emanating from the single light source or from each light source to a respective region of the display. Optionally, an opaque light barrier may be positioned between each of the light guides to inhibit light leakage from one region of the display to another.
According to another embodiment, the illumination of each region of the display is controlled with respect to an update of an image on the display. In an exemplary display, the image is updated, or scanned, across the display from top to bottom in, for example, a raster pattern, although other sequential scanning patterns may be used. Accordingly, the top half (or first region) of the display is updated first. As the top half of the display is updating, the corresponding light source is dimmed or lessened so as to obscure any portion of the image within this region from view, in particular, to reduce or eliminate visual artifacts, as discussed above. After the top half of the display has been updated, the top half is illuminated, making the top half of the image visible to the viewer. The bottom half (or second region) of the display is updated next, and the light source corresponding to this region of the display is dimmed or lessened to obscure any portion of the image within this region from view. After the bottom half of the display has been updated, the bottom half is illuminated, displaying the bottom half of the image to the viewer. There may be, optionally, a blanking interval between the completion of one update and the beginning of the next update during which no update occurs. During the blanking interval, either or both regions of the display may be illuminated for at least a portion of the blanking interval. The above sequence is repeated as each successive image in the series is updated on the display. An exemplary timing sequence for illuminating the display is illustrated in
According to yet another embodiment, where a 3D movie or video or other type of 3D image is being displayed, each displayed image contains either a left eye field of view or a right eye field of view. The display system is coupled to eyewear having two independently controllable shutter lenses, such as described above. Each of the lenses is controlled in synchronization with the displayed image to ensure that it is steered to the correct eye of the viewer for producing the 3D effect. Accordingly, the left shutter lens is open (or unblocked) and the right shutter lens is closed (or blocked) when a left eye field of view is displayed, and the right shutter lens is open and the left shutter lens is closed when a right eye field of view is displayed.
In another embodiment, the illumination control sequence and shutter lens control sequence described above are used in combination. When a left eye field of view is displayed by either or both halves of the display, the eyewear permits the viewer to see the image with her left eye only, and similarly the eyewear permits the viewer to see the image with her right eye only when a right eye field of view is displayed by either or both halves of the display. Further, when an update is occurring in the top half of the display, that region is dimmed, or the light level lessened, to obscure the corresponding portion of the image from view, and similarly when an update is occurring in the bottom half, that region is dimmed If no update is occurring, the corresponding region may be illuminated for at least a period of time as necessary to display the image with sufficient brightness, which may be less than the total amount of time that the image is actually present on the display.
Referring to
According to one embodiment, display device controller 108 receives a video signal from video source 104. The video signal may include 2D and/or 3D images, and frame synchronization information. Display device controller 108 uses the video signal to update each of the picture elements of display screen 114. Display device controller 108 may also use the synchronization information to synchronize the illumination provided by first light source 110 and second light source 112 with an update scan of display screen 114 such that each region is illuminated when no update is occurring in the corresponding region, and each region is dimmed, or the light level lessened, when an update is occurring in the corresponding region. Display device controller 108 may further use the synchronization information to synchronize the operation of each shutter lens of eyewear 106 with the image (or portion of each image) of the video displayed by display screen 114, such that the image or portion of the image is steered by the eyewear to the correct eye of the viewer.
In another embodiment, eyewear 106 includes a left shutter lens and a right shutter lens. Each shutter lens is independently switched between a transparent state and an opaque state, for example, using a liquid crystal material, by applying a voltage to the respective shutter lens. Eyewear 106 is configured to receive synchronization information and, using the synchronization information, further configured to operate each of the left and right shutter lenses of the eyewear substantially in synchronization with each image (or portion of each image) to be displayed by display device 102. For example, at least one lens of eyewear 106 (e.g., left, right, or both) may be configured to block light in response to receiving the synchronization information. The synchronization information may include a signal that is provided by, for example, display device 102. The signal may be provided to eyewear 106 using any wired or wireless communication channel, interface, and/or protocol, for example, using an infrared (IR) sensor to receive an IR signal. The signal may be used by eyewear 106 to close the left shutter lens, the right lens, or both lenses.
According to one embodiment, display screen 114 is a sequentially addressable display screen, for example, a thin film transistor liquid crystal display (TFT LCD), an organic light emitting diode (OLED), other microelectromechanical systems (MEMS) devices, or a plasma display panel (PDP). It should be understood that the invention may also be implemented in other types of emissive displays. Display screen 114 includes a plurality of picture elements (also referred to herein as pixels), which may be divided in to multiple sub-pixels, for example, one for producing each of red, green, and blue light. The display screen 114 may be updated sequentially at, for example, 120 Hz, 240 Hz, or other rate which is fast enough such that each scan of the entire screen is undetectable to the human eye under normal viewing conditions.
Referring to
In one embodiment, display screen 202 includes a plurality of sequentially addressable picture elements (not shown) and may be controlled, for example, by a display device controller (also not shown), such as display device controller 108 described above with reference to
According to one embodiment, system 200 is configured such that light emanating from first light source 204 and second light source 206 propagates through the picture elements of display screen 202, and outwards towards the viewer. First light source 204 is configured to illuminate substantially all of first region 208 of display screen 202, and second light source 206 is configured to illuminate substantially all of second region 210. When first light source 204 or second light source 206 is turned off, dimmed, blocked, shuttered, decreased, or extinguished, the image displayed in the corresponding region of display screen 202 may become dim or obscured from view. First light source 204 and second light source 206 may each include one or more florescent lamps, one or more light emitting diodes (LEDs), such as white phosphor based LEDs, red-green-blue (RGB) LEDs, organic LEDs (OLEDs), or other electronic light sources. In one embodiment, as illustrated in
Referring to
Still referring to
According to one embodiment, the display screen is illuminated by at least two light sources, for example, a top light source 320 and a bottom light source 322. Top light source 320 and bottom light source 322 may each comprise one or more individual light sources, such as fluorescent lamps or other light emitters (e.g., light emitting diodes). The top light source 320 is configured to illuminate substantially the top region 308 of the display, and the bottom light source 322 is configured to illuminate substantially the bottom region 310 of the display, such as described above with reference to
First region update time period 324 may end, and first region display period 328 may begin, substantially simultaneously to the completion of the update of the top region 308, or after the update of the top region 308 has completed. Further, second region update time period 326 may end, and second region display period 330 may begin, substantially simultaneously to the completion of the update of the bottom region 310, or after the update of the bottom region 310 has completed. Each of these time periods may be adjusted to account for variances in the update rate of the display screen and/or the latent on-off transition times of the top light source 320 and bottom light source 322. Yet further, at least a portion of first region display period 328 and second region display period 330 may coincide with the blanking interval 312. In a preferred embodiment, first region display period 328 and second region display period 330 are of substantially the same duration. The sequence described above with respect to an update of the left image 304 is repeated for an update of the right image 306, as shown in
Still referring to
In another embodiment, the left lens 340 is controlled in combination with the top light source 320 and bottom light source 322, to permit the viewer to observe only the top region 308 of the display screen, the bottom region 310 of the display screen, or both while the left lens 340 is open and while the left image 304 is displayed. The right lens 342 is similarly controlled while the right image 306 is displayed, as illustrated in
Method 400 includes detecting an update of the first region of the display screen (ACT 402). While the first region is updating, a first portion of the image that is displayed within the first region is obscured from the viewer (ACT 404). The first portion of the image may be obscured by dimming or lessening a light source that illuminates the first region. The first portion of the image may, additionally or alternatively, be obscured by blocking one or both lenses of shutter glass eyewear worn by the viewer to prevent light from reaching the viewer's eye(s). Further, while the first region is updating, a second portion of the image that is displayed within the second region may be displayed to the viewer (ACT 406). In this manner, the viewer is permitted to see half of the screen, which may be the half that is not currently being updated, and may contain a portion of the previously presented image.
Method 400 further includes detecting an update of the second region of the display screen (ACT 408). This may occur after the first region has completed updating, for example, as would occur during a raster scan update of the display screen. While the second region is updating, a second portion of the image that is displayed within the second region is obscured from the viewer (ACT 410). The second portion of the image may be obscured by dimming or lessening a light source that illuminates the second region. The second portion of the image may, additionally or alternatively, be obscured by blocking one or both lenses of shutter glass eyewear worn by the viewer to prevent light from reaching the viewer's eye(s). Further, while the second region is updating, the first portion of the image that is displayed within the first region may be displayed to the viewer (ACT 412). Method 400 may repeat indefinitely for each image that is subsequently displayed.
In some stereoscopic display techniques, the display may be dimmed, or the light source lessened, during the entire image update to obscure the artifacts associated with image-to-image transitions during, for example, an alternate frame sequence. Therefore, the amount of time that the image is ultimately displayed is typically limited to the relatively short display idle time or blanking interval, when no update is occurring. At certain update rates this results in a diminished brightness of the display, and thus a faster update rate is required to preserve the integrity of the viewing experience at acceptable brightness levels. For example, at 240 Hz, fifty percent of the total image time may be dedicated to updating the display while it is dimmed or obscured, and the remaining fifty percent of the time may be used for illuminating the display so that the viewer can see the image, resulting in a fifty percent overall decrease in brightness compared with non-stereoscopic modes of operation. At 480 Hz, only 25% of the total image time may be required for updating the display, allowing 75% of the time for viewing and a lesser decrease in brightness. It is appreciated that updating the display at a rate of 240 Hz or greater provides a picture that is acceptable to many consumers; however, the cost of producing displays having higher update rates is greater than the cost of producing displays that operate at, for example, 120 Hz.
It should be appreciated that by partitioning the display into two or more regions, and illuminating only those regions that are not being updated, while dimming, or lessening the light level of the region that is undergoing an update, the brightness of, for example, a display operating at 120 Hz is the same as the brightness of a non-partitioned display operating at 240 Hz, such as described above. This is because there is always at least one region or another of the display that is illuminated for approximately the same amount of time at 120 Hz as in the non-partitioned 240 Hz unit. For example, in a 120 Hz unit having two display regions of substantially the same area (e.g., a top half and a bottom half), the total amount of time that each display region is illuminated separately is about the same as the total amount of time that the entire display is illuminated in a non-partitioned 240 Hz unit (e.g., 50% of the total image time, or more). Thus, according to various aspects of the present invention, the ability to provide a display for viewing stereoscopic images at a lower update rate, and lower cost, but having the same brightness characteristics of a higher speed display can be achieved. Further, a partitioned display operating at, for example, 240 Hz, in accordance with various aspects, can provide the same, increased brightness characteristics of a faster display, at relatively little additional cost with respect to the faster unit.
Having thus described several aspects of at least one embodiment of this invention, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the scope of the invention. It should be appreciated that the video source may be projected in sequences other than an alternating-frame sequence, for example, with left and right fields of view projected simultaneously (or substantially simultaneously), or in a left-left-right-right sequence, or other combination of sequences. Furthermore, other techniques may be used to enhance the 3D effect of the displayed images, such as increasing the update rate of the display (e.g., 240 Hz or greater) and/or increasing the vertical blanking interval to enable the viewer to observe the image longer between image updates. Accordingly, the foregoing description and drawings are by way of example only.
This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 61/325,694 entitled “3D Display Using Alternate Half Screen Flashing and Synchronized Shutter Glass,” filed Apr. 19, 2010, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61325694 | Apr 2010 | US |
