Autostereoscopic display apparatus and method

An autostereoscopic display apparatus is provided for three-dimensional (3D) display. The autostereoscopic display apparatus includes a display panel having a plurality of display elements arranged in a two-dimensional array. The autostereoscopic display apparatus also includes a grating device coupled to the display device and having a plurality of grating elements to guide lights associated with 3D display into predetermined viewing directions. Further, the plurality of grating elements cover the plurality of display elements and are tilted such that a tilted direction of the plurality of grating elements form a non-zero angle with respect to a diagonal direction of the plurality display elements.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the priority of Chinese patent application no. 201010511742.2 filed on Oct. 19, 2010, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention generally relates to autostereoscopic display technologies and, more particularly, to methods and systems for reducing or removing Moire pattern in autostereoscopic display apparatus.

BACKGROUND

Nowadays, autostereoscopic display technologies are rapidly developing and there are increasingly demands on high performance autostereoscopic display devices. Autostereoscopic display devices do not require viewers to wear glasses with special lenses to achieve three dimensional (3D) perceptions.

FIG. 1illustrates a conventional autostereoscopic display apparatus1. Display apparatus1comprises a lenticular sheet12coupled to a pixel matrix-based display panel11. Lenticular sheet12comprises a plurality of vertical lenticular elements aligned in parallel in the horizontal direction of display panel11.

FIG. 2illustrates another conventional autostereoscopic display apparatus2. Display apparatus2comprises a parallax barrier13coupled to a pixel matrix-based display panel11. Parallax barrier13comprises a plurality of vertical slits aligned in parallel in the horizontal direction of display panel11.

However, such conventional autostereoscopic display apparatus often has Moire patterns, as a Moire pattern is a natural interference phenomenon that occurs when two separate periodically repetitive structures are overlapped with each other. In a conventional autostereoscopic display apparatus, Moire patterns appear because the regularly spaced grating elements interfere with the underlying display panel which has a grid structure. Moire pattern manifests itself as dark bands passing across the screen. This phenomenon renders 3D viewing experience uncomfortable and less pleasant to the viewer.

The disclosed methods and apparatus are directed to solve one or more problems set forth above and other problems.

BRIEF SUMMARY OF THE DISCLOSURE

One aspect of the present disclosure includes an autostereoscopic display apparatus. The autostereoscopic display apparatus includes a display panel having a plurality of display elements arranged in a two-dimensional array. The autostereoscopic display apparatus also includes a grating device coupled to the display device and having a plurality of grating elements to guide lights associated with three-dimensional (3D) display into predetermined viewing directions. Further, the plurality of grating elements cover the plurality of display elements and are tilted such that a tilted direction of the plurality of grating elements form a non-zero angle with respect to a diagonal direction of the plurality display elements.

Another aspect of the present disclosure includes a grating for use in an autostereoscopic display apparatus. The autostereoscopic display apparatus includes a display panel having a plurality of display elements arranged in a two-dimensional array. The grating includes a plurality of grating elements configured to cover the plurality of display elements to guide lights associated with three-dimensional (3D) display into predetermined viewing directions. Further, the plurality of grating elements are tilted such that a tilted direction of the plurality of grating elements form a non-zero angle with respect to a diagonal direction of the plurality display elements.

Another aspect of the present disclosure includes a method for use in an autostereoscopic display apparatus. The autostereoscopic display apparatus includes a display panel having a plurality of display elements arranged in a two-dimensional array. The method includes covering the plurality of display elements using a plurality of grating elements of a grating. The method also includes configuring the plurality of grating elements to be tilted such that a tilted direction of the plurality of grating elements form a non-zero angle with respect to a diagonal direction of the plurality display elements. Further, the method includes guiding lights associated with three-dimensional (3D) display into predetermined viewing directions by the plurality of grating elements.

DETAILED DESCRIPTION

FIG. 3illustrates an exemplary autostereoscopic display apparatus consistent with the disclosed embodiment. As shown inFIG. 3, autostereoscopic display apparatus50comprises a display panel51, a grating52, and a backlight panel53. Grating52is positioned parallel to display panel51or closely coupled to display panel51.

Display panel51may include any appropriate display panel, such as a liquid crystal display (LCD) panel, a plasma display panel (PDP), a cathode ray tube (CRT) display, an organic light emitting diode(OLED), etc. Display panel51may include a plurality of individually addressable, regularly spaced, and substantially identical display elements511. Display elements511may be arranged in rows and columns. Further, display panel51may be illuminated by backlight panel53. Lights from backlight panel53are directed through display panel51with the display elements511individually addressed to produce a display output. In autostereoscopic display apparatus50, a three-dimensional (3D) image usually includes a multitude of views corresponding to different viewing angles. These views may be spliced into the 3D image (i.e., a 3D display image). For example, a stereo format 3D image may include two images, a left image to be viewed by a viewer's left eye and a right image to be viewed by the viewer's right eye. Horizontally adjacent display elements511may display image elements belong to different views.

Grating52may include any appropriate type of grating device, such as a lenticular lens screen or a slit grating device. Grating52may include a plurality of grating elements521(only shown partially), and the plurality of grating elements521may be arranged in parallel with a predetermined interval. Further, grating elements521may be aligned over display panel51such that a single grating element521may cover two or more display elements511.

Grating element521may include any appropriate optical element capable of separating adjacent views by directing lights from horizontally or vertically adjacent display elements511into different directions to be viewed by a viewer's left eye and right eye separately to achieve a 3D perception. In other words, grating52guides lights associated with 3D display into predetermined viewing directions to achieve 3D perception by the viewer. In certain embodiments, grating element521may include a lenticular lens or a parallax barrier (e.g., a slit).

FIG. 4illustrates a portion of display panel51. As explained, display panel51includes a plurality of display elements511. In certain embodiments, a display element511may include a pixel or a sub-pixel. That is, as shown inFIG. 4, display panel51may include a plurality of pixels20. Pixel20may include several sub-pixels, such as a red sub-pixel21, a green sub-pixel22, and a blue sub-pixel23. Other types of sub-pixels may also be included. Sub-pixels may be considered as basic display elements in display panel51. Further, black mask line24may be used to define the borders of each individual display element511. A plurality of rows and columns of black mask lines24form a grid with a plurality of points of intersection25. The plurality of display pixels20may form a two-dimensional matrix arranged vertically and horizontally. Sub-pixels may be substantially identical in size and may be in rectangular shapes.

Grating52may be coupled to display panel51such that grating elements521may cover corresponding display elements511of display panel51.FIG. 5illustrates various arrangements for grating elements521to cover display panel51.

As shown inFIG. 5, grating elements521may be arranged in a vertical direction with a pitch D1; in a horizontal direction with a pitch D2; in a diagonal direction tilted left with a pitch D3; or in a diagonal direction tilted right with a pitch D4. Because the regularity of arranged grating elements521and the regularity of display elements511of display panel51, Moire pattern may appear.

FIG. 6illustrates another exemplary arrangement of grating elements of grating52with respect to display panel51. Display panel51comprises a plurality of display element511which are separated by black mask lines24in both horizontal and vertical directions. Horizontal and vertical black mask lines24create a grid of display elements. For example, corner points25may be formed when creating the grid. A diagonal direction115may be referred to as the diagonal line connecting two opposing corner points in a same grid unit.

Display panel51or display elements511may also have a diagonal direction116, which may be referred as the diagonal line of an individual display element511and thus also as the diagonal line of all corresponding regularly arranged display elements511across display panel51.

Further, grating52is coupled to display panel51and includes a plurality of grating elements521. Only certain number grating elements are illustrated here, as grating ridge lines120, grating ridge lines121, and grating ridge lines122illustrate individual grating elements521at different locations. A ridge line may refer to a center line of a grating element521or a bottom border line of a grating element521used to indicate a position and a slant angle of the grating element521. Other lines may also be included to indicate positions and slant angles of plurality of grating elements521. Among ridge lines120,121, and122, ridge line120may be referred to as a reference ridge line, and ridge lines121and122are actual ridge lines of two different arrangements between grating52and display panel51. Ridge lines120,121, and122may be tilted (e.g., with a slant angle).

As shown inFIG. 6, reference ridge line120may be parallel to diagonal line116of display panel51, which may also be parallel to diagonal line115of black mask line grid. Although this arrangement may allow individual display elements511to be divided equally into two parts of same shape and same size to create desired 3D images, the substantial evenness and regularity provided by this arrangement may cause substantial Moire patterns.

Thus, actual ridge lines121and122are formed based on reference ridge line120to reduce or remove Moire patterns. As shown inFIG. 6, in certain embodiments, actual ridge line121is used to arrange grating elements521with respect to display panel51; while in certain other embodiments, actual ridge line122is used to arrange grating elements521with respect to display panel51. Further, any lines between actual ridge lines120and121may be used as an actual ridge line for grating elements521.

Actual ridge line121is formed by rotating reference ridge line120clockwise by a certain degree (a positive degree), and actual ridge line122is formed by rotating reference ridge line120counter-clockwise by a certain degree (a negative degree). The rotation pivotal point may be any end point of reference ridge line120(e.g., the upper end of reference ridge line120) or an intersection point between actual ridge line120and a diagonal direction of display elements511. Such positive and negative adjustment to reference ridge line120may create arrangements with substantially less Moire pattern than reference ridge line120.

Further, any appropriate degrees of adjustment angle (i.e., the angle between a ridge line and the diagonal direction of display elements511) may be used to adjust reference ridge line120. For example, an adjustment range may be set to between −5 to +10 degrees, with the diagonal direction as reference. In certain embodiments, the adjustment range may be set to between −2 to +7 degrees. Within this adjustment ranges, any angle may be used based on particular applications. Different angles within the adjustment range may also be tested to choose a desired angle such that a pitch of Moire pattern is so small that the Moire pattern cannot be distinguished by human eyes. Further, the slant angle of grating elements521may also be adjusted to accommodate various display panels for removing Moire patterns from autostereoscopic display screens.

As explained previously, grating52may include any appropriate grating devices, such as a lenticular lens screen or a slit grating.FIG. 7illustrates an exemplary arrangement of a lenticular lens screen with respect to display panel51. As shown inFIG. 7, lenticular lens screen or lenticular sheet130comprises a plurality of lenticular lenses or elements131,132, and133. A cross-section direction134of lenticular sheet130aligns with the horizontal direction of display panel51. A diagonal direction135of display panel51may form an angle θd1with respect to cross-section direction134or the horizontal direction.

Lenticular elements131,132, and133are individual lenticular elements listed for illustrative purposes. Any lenticular element may be used. As shown inFIG. 7, lenticular element131has a pitch d1and an angle θ1with respect to cross-section direction134or the horizontal direction. Lenticular element132has a pitch d2and an angle θ2with respect to cross-section direction134or the horizontal direction. Further, lenticular element133has a pitch d3and an angle θ3with respect to cross-section direction134or the horizontal direction.

Lenticular elements131,132, and133are arranged un-parallel to diagonal direction135of display panel51. In other words, angles θ1, θ2and θ3are different from θd1. The difference between θd1and any of angles θ1, θ2and θ3may be the adjustment angle explained with respect toFIG. 6. Such arrangement may reduce Moire pattern to certain level beyond recognition of human eyes. Further, lenticular elements131,132and133may extend or arranged in parallel with one another, which means angles θ1, θ2and θ3have the same value. Further, pitches d1, d2and d3may also be of the same value.

FIG. 8illustrates an exemplary arrangement of a parallax barrier with respect to display panel51. As shown inFIG. 8, parallax barrier140includes a plurality of parallax barrier elements141,142, and143. Parallax barrier element141includes a barrier portion1411and a slit portion1412. Similarly, parallax barrier element142includes a barrier portion1421and a slit portion1422, and parallax barrier element143includes a barrier portion1431and a slit portion1432. A cross-section direction144of parallax barrier140aligns with the horizontal direction of display panel51. A diagonal direction145of display panel51may form an angle θd2with respect to cross-section direction144or the horizontal direction.

Parallax barrier elements141,142, and143are individual parallax barrier elements shown for illustrative purposes. Any parallax barrier element may be used. As shown inFIG. 8, parallax barrier element141has a pitch d4(barrier portion1411has a pitch d41, and slit portion has a pitch d42, d4=d41+d42) and an angle θ4with respect to cross-section direction144or the horizontal direction. Parallax barrier element142has a pitch d5(barrier portion1421has a pitch d51, and slit portion has a pitch d52, d5=d51+d52) and an angle θ5with respect to cross-section direction144or the horizontal direction. Further, parallax barrier element143has a pitch d6(barrier portion1431has a pitch d61, and slit portion1432has a pitch d62, d6=d61+d62) and an angle θ6with respect to cross-section direction144or the horizontal direction.

Parallax barrier elements141,142, and143are arranged un-parallel to diagonal direction145of display panel51. In other words, angles θ4, θ5and θ6are different from θd2. The difference between θd2and any of angles θ4, θ5and θ6may be the adjustment angle explained with respect toFIG. 6. Such arrangement may reduce Moire pattern to certain level beyond recognition of human eyes. Further, parallax barrier elements141,142and143may extend in parallel with one another, which means angles θ4, θ5and θ6are of the same value. In addition, pitches d4, d5and d6may also be of the same value. Barrier portion pitches d41, d51and d61and/or slit pitches d42, d52and d62may also be of the same values.

The gratings in the above examples are not limited to lenticular sheet gratings and parallax barrier gratings. Those skilled in the art understand many different types of gratings may be used. Further, the gratings can be of static or dynamic nature. For example, a slant angle, pitch, thickness, etc, of a lenticular sheet or a parallax barrier grating may be dynamically adjusted mechanically or by using piezoelectric or electro-optic devices.

FIG. 9illustrates another exemplary arrangement of grating52with respect to display panel51. This exemplary arrangement is similar to that described inFIG. 6, with a reference ridge line220and actual ridge lines221and222. The difference betweenFIG. 9andFIG. 6is that, in addition to rotation of the reference ridge220, actual ridge lines221and/or222may also have a shift along the horizontal direction. Both rotation and shifting may be more flexible than rotation only. Further, the angle adjustment for actual ridge lines221and222may be set to a range of −5 to 10 degrees.

FIG. 10illustrates yet another exemplary arrangement of grating52with respect to display panel51. This exemplary arrangement is similar to that described inFIG. 9. The difference is that, in this arrangement, reference ridge line320of grating52is aligned parallel to the other diagonal direction of display panel51(e.g., tilted right instead of left).

Moire pattern may be effectively removed by using the above-mentioned systems and methods. However, because the rotation and/or shifting, display elements may be unable to completely evenly and regularly align with grating elements. Lights from display elements may be processed by grating elements with irregularity. For example, display elements belong to one view may then be misdirected to adjacent views instead. Suitable image processing algorithms may be used to compensate the irregularity of intersection between the grating elements and display elements.

Autostereoscopic display apparatus50may also include a controller (not shown) for providing control and operation functions for autostereoscopic display apparatus50. For example, the controller may provide driving voltages to various components of autostereoscopic display apparatus50. The controller may also provide image processing functions during run-time to improve display quality of autostereoscopic display apparatus50.

The controller may include a processor such as a graphic processing unit (GPU), general purpose microprocessor, digital signal processor (DSP) or microcontroller, and application specific integrated circuit (ASIC). The controller may also include other devices such as memory devices, communication devices, input/output devices, driving circuitry, and storage devices, etc. The controller may also execute sequences of computer program instructions to perform various processes associated with autostereoscopic display apparatus50. For example, during operation, the controller may perform an image processing process to adjust display quality due to the irregularity of intersection between grating elements and display elements.

More particularly, the controller may re-calculate or adjust values of display elements511to compensate the irregularity. For example, because the irregularity may cause a first display element from a first view point being displayed together with a portion of a second and neighboring display element from a second view point and, if applicable, a portion of a third or more neighboring display element from a third or more view point, the controller may re-calculate or adjust the value for the first display element using the second display element or the second display element and the third or more display elements.

Further, the controller may use any appropriate type of algorithm to re-calculate or adjust values of each of display elements511. For example, the controller may use an interpolation algorithm to adjust values of each of display elements511based on corresponding neighboring display elements. Other algorithm, however, may also be used.FIG. 11illustrates another exemplary arrangement of grating52with respect to display panel51with display element adjustment ability.

As shown inFIG. 11, grating elements of grating52are arranged with a particular angle as explained previously. Irregularity may be introduced due to the relative arrangement of grating elements of grating52and display elements of display panel51. For illustrative purposes, display elements (e.g., sub-pixels) from one row of display panel51between two actual ridge lines are listed as elements411,412,413,414, and415. Each element may belong to an image of a different view point. For example, element411may belong to a first view point image, element412may belong to a second view point image, element413may belong to a third view point image, element414may belong to a fourth view point image, and element415may belong to a fifth view point image. Between neighboring elements or view point images, a certain parallax may be maintained for effecting 3D perception or 3D display. Other elements or viewpoints may also be used.

During operation, to compensate for the irregularity, the controller (not shown) may adjust the value of a particular display element of a view point image based on one or more other display elements from different view point images. The value of the particular display element may include a gray scalar value, a color scalar value, or any other value of a display element such as a pixel or a sub-pixel. For example, the controller may re-calculate the value of element411of the first view point image based on the original value of element411and the value of element412of the second view point image. In a multi-view format, the controller may re-calculate the value of a display element based on multiple images corresponding to multiple view points.

A decimal format number x.y may be used to represent a relationship between display elements for calculating the value of a particular display element. For example, integer part x may refer to the number of original or a base view point image, and fraction part y may refer to a percentage of the value of the element of the neighboring view point image or another view point image along the forward direction of ridge lines to be used to adjust the value of the original display element. For example, the respective value relationships of elements411,412,413,414, and415are 0.1, 1.0, 1.9, 2.8, and 3.7.

More particularly, for example, element414has a decimal number 2.8, whose integer part 2 means the original or base element is from the third view point image (starting from 0), thus the neighboring view point image along the forward direction of ridge lines is the fourth view point image, and fraction part 0.8 means eighty (80) percentage of the element from fourth view point image should be counted to calculate the value of element414, while remaining twenty (20=100−80) percentage from the original or base view point image (i.e., the third view point image) should be counted. That is: current value (element414)=original value (element413)×20%+original value (element414)×80%.

Similarly, element411has a decimal number of 0.1, current value (element411)=original value (element411)×90%+original value (element412)×10%. Element412has a decimal number of 1.0, no recalculation is need since none of other view point image should be counted. Further, element413has a decimal number of 1.9, current value (element413)=original value (element412)×10%+original value (element413)×90%. Element415has a decimal number of 3.7, current value (element415)=original value (element414)×30%+original value (element415)×70%. The original value may include color, non-color, or other type of value of display elements. Other algorithms may also be used.

Thus, during operation, values of display elements of display panel51are re-calculated or adjusted before the values of display elements are displayed to reduce irregularities because of the particular angle of arrangement for grating52and display panel51. The re-calculated or adjusted values may then be displayed on display panel51. The set of adjustment numbers of all display elements of display panel51may be pre-determined or stored in a database or other storage medium, such as a hard disk, on display apparatus50. Further, more than one set of adjustment numbers of display elements of display panel51may be used, and a user of display apparatus50may select a particular set of adjustment numbers or may modify a particular set of adjustment numbers through certain user input devices.

FIG. 12illustrates another exemplary autostereoscopic display apparatus60consistent with the disclosed embodiment. As shown inFIG. 12, similar to autostereoscopic display apparatus50, autostereoscopic display apparatus60comprises a display panel61, a grating62, and a backlight panel63. Display panel61comprises a plurality of individually addressable, regularly spaced, and substantially identical display elements611. Display elements611may be arranged in rows and columns.

Further, different from autostreroscopic display apparatus50, grating62is positioned between backlight panel63and display panel61. Grating62is aligned substantially parallel to display panel61

Lights from backlight panel63may enter grating62first. Grating62may guide the lights from backlight panel63into different viewing directions to illuminate display panel61. Display elements611may further respectively receive the lights from different viewing directions and may also modulate the received lights to display 3D images.

FIG. 13illustrates another exemplary autostereoscopic display apparatus70consistent with the disclosed embodiment. As shown inFIG. 13, autostereoscopic display apparatus70comprises a display panel71and a grating72. Similar to autostereoscopic display apparatus50, grating72is aligned substantially parallel to display panel71or closely coupled to display panel71, and display panel71may include a plurality of individually addressable, regularly spaced, and substantially identical display elements711arranged in rows and columns. Different from autostereoscopic display apparatus50, however, display panel71may be a self-luminous or light-emitting display panel that actively emits lights without a need of a backlight panel. Thus, grating72and display panel71may be coupled to provide 3D display.

The disclosed systems and methods can effectively reduce or remove Moire pattern in 3D display and also improve display quality of the 3D display. The disclosed arrangements of gratings and display panels can achieve effects of even separation of display elements while maintain a large adjustment range to fit structures of most display elements of display panels in the market.