JP2019510996A - Method and system for using a refractive beam mapper having a rectangular element profile to reduce Moire interference in a display system comprising a plurality of displays - Google Patents

Abstract

A multi-display system (e.g. a display comprising a plurality of display panels) comprises at least a first and a second display arranged substantially parallel to one another for displaying three-dimensional (3D) features to the viewer. For example, a display panel or a display layer is included. At least an optical element such as a refracted beam mapper (RBM) is utilized to reduce Moire interference. [Selected figure] Figure 5

Description

  This application is a continuation-in-part (CIP) of US patent application Ser. No. 15 / 283,621, filed Oct. 3, 2016. This application is a U.S. Provisional Patent Application, filed 62 Jan. 28, 2016, and filed 62 Jan. 2016, filed Jan. 20, 2016. 993 (Accession No. 6468-17), and 62 / 236,776 (Accession No. 6468-8) submitted on October 2, 2015, each of which is related to and claims priority to them All of which are incorporated herein by reference in their entirety.

  According to the present invention, at least first and second displays (eg, display panels or display layers) are arranged substantially parallel to each other to display three-dimensional (3D) features to an observer. Multi-display system (e.g., a display including multiple display panels / display layers). Accordingly, the present invention relates generally to displays, and more particularly to display systems and methods for displaying three dimensional features.

  Traditionally, displays present information in two dimensions. The image displayed by such a display is a planar image lacking depth information. As people view the world in three dimensions, efforts have been made to provide displays that can display objects in three dimensions. For example, a stereo display conveys depth information by displaying offset images that are displayed separately for the left and right eyes. When the viewer views these planar images, they are combined in the brain to give a perception of depth. However, such systems are complex and require increased resolution and processor computing power to provide realistic perception of displayed objects.

  [004] A multi-component display including multiple display screens arranged in a stack has been developed to display realistic depth. Each display screen can display its own image to provide visual depth due to physical displacement of the display screen. For example, multi-display systems are disclosed in US Patent Publication Nos. 2015/0323805 and 2016/0012630, both of which disclosures are incorporated herein by reference.

  [005] Moire interference occurs when the first and second displays or display layers are stacked on one another in a conventional manner in a multi-display system. Moire interference is caused by the interaction between color filters in a layer when projected onto the viewer's retina. For example, when the green color filters overlap, light is transmitted to create relatively bright sections. If the green filter is on top of the red filter, less light will be transmitted to create dark areas. Since the back and front displays or display layers have a slightly different size when projected onto the retina, the pixels will slowly change from in phase to out of phase. This has the effect of producing bright and dark bands, also known as moire interference.

  [006] Certain exemplary embodiments of the present invention provide a solution to eliminate or substantially eliminate Moire interference in MLD systems, but without significantly sacrificing the resolution and contrast of the back display. In one exemplary embodiment of the present invention, an MLD system includes first and second displays. A refracted beam mapper (RBM) can be used to reduce or eliminate Moire interference. It has been found that a rectangular profile diffuser element improves image quality in such MLD systems.

  In an exemplary embodiment of the present invention, a first display in a first plane for displaying a first image and a second display in a second plane for displaying a second image A display, wherein the first and second planes are disposed substantially parallel to each other, and disposed between the second display and the first and second displays, the light beam output from the second display being the first A beam mapping element comprising a plurality of microlenses configured to be directed towards a viewer through sub-pixels of a display, each of said microlenses being viewed from above to improve image quality And a beam mapping element having a substantially rectangular profile.

  In an exemplary embodiment of the present invention, a first display in a first plane for displaying a first image and a second display in a second plane for displaying a second image A display, wherein the first and second planes are substantially parallel to each other, disposed between the second display and the first and second displays, pseudo-randomly incident light from the second display A display device is provided, comprising: a beam mapping element (e.g. a refracted beam mapper) comprising a plurality of microlenses configured to be directed towards the viewer through the sub-pixels of the first display.

  [009] In an exemplary embodiment of the present invention, a first display in a first plane for displaying a first image, and a second display in a second plane for displaying a second image A second display, wherein the first and second planes are substantially parallel to each other, and disposed between the second display and the first and second displays, the light beam output from the second display being the second display A refractive beam mapper comprising an array of beam mapping elements configured to be directed towards a viewer through sub-pixels of one display, each of the beam mapping elements having a substantially rectangular profile And a refracted beam mapper.

  [0010] In various embodiments of the present invention, the refracted beam mapper is another method for reducing Moire interference (eg, color filter offsets or dissimilar color filter patterns on the respective displays, And / or may be used in combination with sub-pixel compression).

  [0011] The patent or application document contains at least one drawing executed in color. A copy with a color drawing of this patent or patent application publication will be provided by the Office upon request and payment of the necessary fee.

  [0012] These and other features and advantages can be more fully understood and appreciated by reference to the following detailed description of illustrative embodiments in connection with the drawings.

FIG. 1 is a plan view of a color filter of a liquid crystal display (LCD) in which the pixels are the same color in each column (or row). FIG. 2 is a plan view of another liquid crystal display (LCD) color filter in which the pixels are the same color in each column (or row). FIG. 3 is a plan view of the MLD system resulting from the combination of the LCDs of FIGS. 1 and 2, where the LCDs of FIGS. 1 and 2 are stacked on top of each other in a stacked relationship, resulting in Moire interference. FIG. 4 is a schematic diagram showing pseudo-random mapping of pixels of the back display of the MLD system to pixels of the front display. FIG. 5 is a schematic diagram showing a mapping element that can be used in conjunction with the pseudo-random mapping of FIG. 4 to reduce Moire interference (this is an implementation of sub-pixel compression in various embodiments of the invention) It may or may not be used in combination with the embodiment). FIG. 6 is a schematic side sectional view of an MLD according to an exemplary embodiment of the present invention that can be used with any of the embodiments of the figures herein. FIG. 7 shows a bandwidth limited implementation of an RBM with refractive optics. FIG. 8 is an intensity profile exhibiting improved super-Lorentzian characteristics over a range of p = 40 angles and lens feature sizes of 160 microns or less. FIG. 9 is a graph showing that larger microlenses will typically have better anti-Moire diffuser profile. FIG. 10 is a schematic diagram illustrating an exemplary manufacturing process of RBM that can be used in various embodiments of the present invention. FIG. 11 shows a microlens according to an exemplary embodiment of the present invention. FIG. 12 is a graph of incident angle versus transmission coefficient showing curves depicting transmission coefficients of S and P waves versus angle of incidence. FIG. 13 is a graph showing the contrast (θi, n1, n2, N) which is the contrast of the system. Where θ i is the angle of incidence, n 1 is the refractive index of the material between the LCDs, n 2 is the refractive index of the glass, and N is the number of boundaries. FIG. 14 is a side cross-sectional view of an MLD system according to an embodiment of the present invention in which a moiré reducing element (eg RBM) is placed at various positions of the stack in the MLD system according to various embodiments of the present invention May or may not be used in combination with sub-pixel compression in various embodiments of the invention). FIG. 15 is a side cross-sectional view of an MLD system according to an embodiment of the present invention in which a moiré reducing element (eg RBM) is placed at various positions of the stack in the MLD system according to various embodiments of the present invention May or may not be used in combination with sub-pixel compression in various embodiments of the invention). FIG. 16 is a side cross-sectional view of an MLD system according to an embodiment of the present invention in which a moiré reducing element (eg RBM) is placed at various positions of the stack in the MLD system according to various embodiments of the present invention May or may not be used in combination with sub-pixel compression in various embodiments of the invention). FIG. 17 is a plan view of a diffuser plate including a rectangular profile microlens that can be used as a moiré reduction element (eg, RBM) in any of the embodiments herein, eg, FIGS. 4-7, 14-16. FIG. FIG. 18 is a plan view showing a complete circular filter kernel. FIG. 19 changes the radius of the circular kernel with respect to image quality. FIG. 20 is a graph comparing the comparison of rectangular and circular kernels (for microlens profiles) for image quality.

  According to the present invention, at least first and second displays (eg, display panels or display layers) are arranged substantially parallel to each other to display three-dimensional (3D) features to an observer. Multi-display system (e.g., a display including a plurality of display panels). The display may be flat or curved in various embodiments. Accordingly, embodiments of the present invention relate generally to displays, and more particularly to display systems and methods for displaying three-dimensional features. An MLD according to an exemplary embodiment of the present invention may, for example, be used as a display in a vehicle instrument panel to provide 3D images (e.g. to a speedometer, vehicle instrumentation, vehicle navigation display, etc.) it can.

  [0032] The problem of color moiré interference is caused, for example, by the pattern regularity of the color filter arrays of both liquid crystal displays (LCDs) such that RGB pixels are arranged in RGB columns in both displays of the MLD system. Color moire interference is widely recognized in the horizontal direction.

  [0033] Figures 1-3 show a configuration in an MLD system that experiences moire interference. FIG. 1 is a plan view of color filters / pixels of a first liquid crystal display (LCD) in which the pixels or sub-pixels are the same color in each column. In particular, FIG. 1 shows an LCD with a conventional red-green-blue (R-G-B) repeating pattern or arrangement in which the pixels or sub-pixels are the same color in each column. Starting from the left side of FIG. 1, the stripes of color filters are arranged in vertical lines in the order of BGR, and this BGR order is repeated many times from left to right across the display of FIG. Thus, the pattern in the display or display layer of FIG. 1 includes blue columns, green columns, and red columns. The green (G) columns are located between the blue (B) and red (R) colored columns. Sub-pixels can be considered as the area of a given pixel electrode in the area of a particular color filter. For example, R, G, and B sub-pixels can constitute a pixel. Alternatively, the sub-pixels can be considered to be pixels. FIG. 1 is shown without rotation of the color mask. Conventionally, both panels of a multi-layer display (MLD) can likewise be constituted by such R-G-B arrangements. The repeating pattern may be R-G-B, R-B-G, or any other combination.

  [0034] Similarly, FIG. 2 is a plan view of color filters / pixels / sub-pixels of the second LCD in which the pixels or sub-pixels are also the same color in each column. Starting from the left side of FIG. 2, the stripes of color filters are arranged in vertical lines in RGB order, and this order is repeated many times from left to right across FIG. The repeating pattern may be R-G-B, R-B-G, or any other combination with these colors. As shown in FIG. 2, as in FIG. 1, the green (G) columns are disposed between the blue (B) and red (R) colored columns.

  [0035] FIG. 3 is a plan view of the MLD system obtained from the combination of the LCDs of FIGS. 1 and 2 with one on top of the other in stacked and overlapping relationship in the MLD system. FIG. 3 shows a mixture of the color filters and pixel / subpixel patterns shown in FIGS. In particular, FIG. 3 shows the appearance of Moire interference given the illustration that both LCDs whose pixels are the same color in each column have a similar arrangement of R-G-B columns. For example, if the pattern of FIG. 2 overlaps the pattern of FIG. 1 in an MLD system, the green filter lines overlap (see, eg, the left portion of FIG. 3) and light in the overlapping area of the green filter lines passes through the MLD system. Create a relatively bright green area. If the green filter overlaps, for example, the red filter (or the blue filter is on top of the red filter), less light will be transmitted to create a dark area (eg, the green strip at the left end of FIG. 3) See the surrounding dark area). Since the back and front displays or display layers have a slightly different size when projected onto the retina, the pixels will slowly change from in phase to out of phase. This has the effect of producing bright and dark bands, also known as moire interference.

  An embodiment of the present invention addresses, reduces or solves this problem of Moire interference. One exemplary embodiment of the present invention provides a solution to eliminate or substantially eliminate Moire interference in MLD systems without significantly compromising the resolution and contrast of the back display.

  In one embodiment of the present invention, a beam mapping element such as a diffractive optical element (DOE) or a refractive beam mapper (RBM) composed of a large number of micro lenses reduces Moire interference. Can be used to If an RBM is used, pseudo-random mapping can be provided to avoid introducing extra moiré effects. In one exemplary embodiment, the degree of opening of the individual beams is limited such that any point on the rear LCD is not deviated from the straight line by more than one pixel distance by the time the beams reach the front LCD. Can. In one exemplary embodiment, such beam mapping elements can be laminated to the front display and the medium between the two LCDs can be optically matched with non-birefringent material, such an embodiment being It may or may not be used in combination with the subpixel compression techniques discussed in the specification.

  [0038] The displays or display layers in the present specification (see, for example, the front display 1 and the back display 2 in FIG. 6, or the corresponding displays in FIGS. 4, 5, 7, 14-16) are LCD, OLED, etc. May be there. A Twisted Nematic (TN) LCD may follow a very general pixel layout, such as a square divided into three parts horizontally (or vertically) aligned by red, green and blue sub-pixels . Sub-pixels can be separated by a black mask in horizontal and vertical directions. At the corners of the sub-pixels there are often rectangular protrusions covering the drive transistor. There are several different pixel technologies that enable the wide screen view and temporal performance required of modern desktop monitors and televisions. Embodiments of the present invention are compatible with all of these LCDs as the backplane is configured to follow the basic RGB stripe pixel layout. Thus, the required backplane layout for each pixel need not be changed. For example, pixel type displays by manufacturers are: Panasonic (IPS Pro), LG Display (H-IPS and P-IPS), Hannstar (S-IPS), AU Optronics (A-MVA), Samsung (AFFS), S-LCD (S-PVA) and Sharp (ASV and MVA). In one embodiment, both displays or display layers may be OLEDs, or one display may be an OLED and the other an LCD. Note that in OLEDs, each sub-pixel or pixel will be filled with red, green and blue materials as color filter materials (as opposed to having an LCD type color filter) I want to be

  [0039] FIG. 6 shows an MLD according to an exemplary embodiment of the present invention in which the stacked overlapping layers / displays of any of the figures herein can be provided and utilized. For example, the displays shown in any of FIGS. 4-5 and 14-16 may be front display 1 and rear display 2 in FIG. 6, respectively. The first display or display layer of the MLD may be element 1 (or 2) and the second display or display layer of the MLD may be element 2 (or 1). The display or display layer 2 is closest to the backlight of the MLD, and its backplane facing the backlight system enters the backlight through the row drivers, column drivers, transistors and storage capacitance lines It would be desirable to have them be reused. As shown in the figure, an arrangement of two polarizers can be used, including air or, if desired, a birefringent material designed to maintain the black state of the display. , Gap can be configured. The gap can include a material having a refractive index that is well matched to the glass or layers on either side to reduce internal reflection and / or depolarization effects. For the front display or display layer 1, the backplane can be oriented opposite to that of the display or display layer 2. In particular, for the front display 1, the backplane can be oriented to face the viewer to reduce internal reflection. Thus, in one exemplary embodiment, the color filter layers of each display 1 and 2 (each of which can be composed of one or more layers) face each other, whichever from any of the displays It can be understood in FIG. 6 that no liquid crystal layer is also disposed between the color filter layers of the first and second displays. In an exemplary embodiment, an anti-reflection system as shown in FIG. 6 comprising a quarter-wave retarder and an anti-reflection polarizer is provided on the front surface to reduce external reflection of ambient light. The ambient light, which is normally reflected, is subject to a quarter-wave rotation in the first pass through the AR polarizer, is reflected by the backplane element, and is It will receive a second rotation through the retarder. By the time the light experiences this second rotation, the light will be substantially orthogonal to the transmission axis of the AR polarizer and thus substantially absorbed. In addition, a black mask (BM) or other non-reflective material may be added behind the conductive traces of the display to reduce reflections. Furthermore, in an exemplary embodiment of the invention, an antireflective (AR) coating may be applied to the inner surface. The AR coating can operate, for example, in the visible range, and can be, for example, moth-eye, single-layer interference, multilayer interference, etc.

  [0040] With respect to Refractive Beam Mapper (RBM), such a beam mapping element consists of or includes a plurality of microlenses and as an independent element for reducing Moire interference via pseudo-random mapping It can be used (see, eg, FIGS. 4-6 and 14-16). In one exemplary pseudo-random mapping implementation (e.g., Figure 4-5), each of the refractive microlenses of the RBM is configured to reflect incident light rays from the rear LCD 2 and different sub-pixels of the front LCD 1 in accordance with the pseudo random mapping. It can be configured to direct to the observer on a defined path through. For example, FIG. 4 shows a pseudo-random mapping of the back sub-pixels or pixels of the back display 2 to sub-pixels or pixels in the front display 1 (the back display is the leftmost display in FIG. 4). Pseudo-random mapping is used to avoid introducing extra moiré effects, which can reduce moiré interference. In one exemplary embodiment, the degree of opening of these individual beams is such that light from any pixel or sub-pixel of the back LCD is not deviated more than a pixel or sub-pixel distance from the straight line on the front display. Limited As an option, RBM can be laminated to the top LCD 1 (see FIGS. 5, 14 and 16) and optionally optically match or substantially match the non-birefringent material to the medium between the two LCDs It can be done. However, in other embodiments, the refractive beam mapper can be located anywhere in the LCD stack. For example, FIG. 5 shows a beam mapping element (e.g., an RBM including a microlens array) located between the front LCD and the back LCD and stacked inside the front display.

  [0041] In an exemplary embodiment, RFM microlenses can be fabricated using grayscale lithography to create microlens-shaped arbitrary surface structures. Each lens element can be configured to direct light in a controlled direction, allowing for arbitrary and asymmetric diffusion angles as shown in FIGS. 4-5. It is possible to make a master to replicate RBMs, using various mass production processes and materials as in the replication of microlens functions, the tilt angle profile is more important than the height profile. FIGS. 4-5 show how, from the point of view of the observer, the refractive beam mapper superimposes the rays from the rear LCD 2 on the front LCD 1. The beam path is pseudo-randomly mapped to avoid introducing other image artifacts such as extra moiré. The underlying LCD structure 2 is randomized and therefore can not produce noticeable Moire interference with the upper LCD 1.

  Alternatively, a diffusion plate may be used instead to construct the moiré suppression element. Although the process can be adapted to make a refracted beam mapper, industrially manufactured diffusers can also be used as optimal diffuser elements for moiré reduction. Diffusers are less desirable than refracted beam elements.

  [0043] The refracted beam mapper can exhibit various features. For example, RBM can exhibit achromatic performance. In addition, RBM can exhibit arbitrary / asymmetric diffusion angles. Further, RBM can exhibit a controlled intensity distribution pattern (eg, circular, square, rectangular, elliptical, linear, ring, etc.). Also, RBM can indicate a controlled intensity profile (eg, flat top, Gaussian, bat wing, special design, etc.). RBM can also exhibit high optical transmission efficiency (eg, 90 percent). In addition, RBM can exhibit polarization preservation. The RBM can be comprised of or comprised of various materials, such as injection molded polymers, heat embossed polymers, polymer on glass parts, and the like.

  [0044] Moire interference in MLD is generally suppressed by adding a diffuser element (as opposed to a beam mapping element) between the rear LCD and the viewer so that the pixel structure of the rear LCD is blurred. The larger the spread of the diffuser, the smaller the moiré, but correspondingly the observed resolution of the rear LCD is reduced. This is an optimization problem and can be described as an image quality cost function IQC that can range from 0 to 4. Here, 0 is perfect and 4 is the worst for both moire and blur. Factors to consider include: Contrast = (max-min) / (max + min) (1 is best, 0 is worst); Crosstalk = 1-alternating black and white line contrast (range 0: 1); Moire = both LCDs The moiré contrast for the above white single color pattern (range 0: 1); IQC = moiré_X + moire_Y + crosstalk_X + crosstalk_Y (ie the range is 0: 4), the lower the value, the better. Usually, the cost function will have a realistic maximum of approximately 2, as shown by the following limits: no diffuser: Moire_X + Moire_Y = 2, Crosstalk_X + Crosstalk_Y = 0; Diffuser: Moiré_X + Moiré_Y = 0, Crosstalk_X + Crosstalk_Y = 2.

  [0045] FIG. 7 shows a bandwidth-limited implementation of RBM with specially designed refractive optics close to the flat top profile such that the far field image is as close as possible to the flat top profile. Prescriptions for the set of lenses that make up this distribution are defined, including feature sizes and tilt angles based on the diffusion requirements. These parameters can be defined in terms of a probability distribution function that specifies the likelihood that a lens will assume a particular prescription. The spatial distribution of the microlenses that shape the surface structure is designed to shape the surface structure according to the desired distribution function. It is understood that, in an exemplary embodiment, the periodicity inherent in the spatial distribution of microlenses can be eliminated. Also, lens misalignment that can lead to wide angle diffusion can be eliminated. Both of these improvements maximize the use of available light. FIG. 8 shows an intensity profile exhibiting an improved super Lorentzian behavior over an angle of p = 40 and a lens feature size ≦ 160 μm. Careful pseudorandomization of the surface structure also produces a diffuse distribution without image distortion and induced moiré. This may be important as regular patterns may introduce additional Moire interference.

  [0046] FIG. 9 shows that there is a trade-off between the size of the microlens and the induced image distortion. Larger microlenses will typically have better anti-Moire diffuser profile. If the microlens is of a size that is visible to the naked eye, extra image artifacts will be clearly visible. These include sparkles, pixel walking, and more interference between the pattern and one or both of the LCD. FIG. 9 shows PSFs for single microlenses of different diameter values (um). Minimizing feature size can also be utilized in the design of LCD moiré reduction elements. The feature size should ideally be smaller than the sub-pixel in order to remain substantially invisible to the naked eye as shown in FIG. In the case where the diffusion center is in the form of a micro lens, the feature size is given by the diameter of the micro lens. In particular, a compact refractive element is desired. If the microlens is of a size that is visible to the naked eye, extra image artifacts will be clearly visible. These include bright spots, pixel movement, and Moire interference between the pattern and one or both of the LCD. Bright spots are most often seen in anti-glare displays where the surface of the display is treated to produce a matte textured surface. These surface features may act as refractive or diffractive elements and focus or defocus individual pixel elements depending on the position of the viewer, resulting in intensity variations or bright spots. The movement of pixels is the result of the distortion of refraction that appears to move and deform the individual pixels and the movement of the viewer by the position. When the regular features in the array of microlenses "beat" with one or both of the LCDs, extra Moire interference is introduced. Randomizing and shrinking the lens size or diffuser and placement in the RBM reduces these extra moiré image distortions. There are two factors to consider in this regard. It is averaging with sag (sag). In order to ensure the best uniformity and moiré reduction, multiple diffuse centers should be illuminated within the area of each pixel as shown in FIG. At the same time, for a set of parameters (eg, divergence angle, refractive index, and conic constant), the lens depth decreases as the diameter of the microlens decreases. If the process continues, a diffractive area that only gives a small phase delay of 2π lens depth is finally achieved. In this regard, it is useful to define the number of phases in the following equation:

  In the above equation, y max represents the total sag of the lens, λ is the wavelength under consideration, and Δ n is equal to n (λ) 1 where n is the index of refraction at the wavelength λ for elements in air. The phase number basically represents the total sag in terms of phase cycles and defines the diffractive or refractive region in which the microlens operates: M = 1 means a diffractive element with a phase shift of exactly 2π. In one embodiment, in the case of microlenses operating in the refractive area, as is desirable for achromatic parts with high target efficiency, the phase number M should be as large as possible.

  [0048] Consider again the case of a microlens that diffuses the collimated beam with a 40 ° spread. As the diameter decreases, far-field diffusion exhibits coarser oscillations and more inclined falloff, changing to lower target efficiencies. A simple rule of thumb that helps to determine the minimum feature size or lens diameter to use is given by:

In the above equation, θ ₀ is the half width of the beam diffusion angle expressed in degrees (in air). To be good in the refractive region, M should be on the order of 8 or more. Assuming θ = 2 °, λ = 0.633 μm, and M = 8, the result D 582 582 μm is obtained, which is too large compared to a 200 um pixel and can be viewed just like the image Will degrade. Increasing diffusion to 20 degrees will reduce D by 10 to 58 μm. In the above equation, the closer the diffuser is to the back panel, the larger the FWHM angle θ ₀ . This equation also gives the rule of thumb of the microlens diameter for θ ₀ .

[0050] Embedding the refractor in a higher refractive index (RI) medium such as silicon OCA rather than air allows effective use of wider angle refractor. This is because higher RI reduces the refractive power of each microlens. If RI = 1.42, then θ ₀ equals the angle θ = ̃11 °, or according to the above equation, more acceptable D ≧ 105 μm. In one embodiment, embedding in high RI materials effectively reduces the diameter of the microlenses, resulting in less image distortion. In particular, replacing the air between the two panels with an index matching medium will also allow for a smaller divergence angle and thus smaller micro lens diameter than measured in air.

  [0051] FIG. 10 illustrates a process of manufacturing an RBM that includes the formation of microlenses on a wafer support, according to an embodiment of the present disclosure in the above regard. In order to improve the image contrast of MLD, RBM can be embedded in high RI materials to reduce Fresnel depolarization.

  [0052] FIG. 11 shows a microlens surface having a distribution of surface normals, typically between 0 degrees and approximately 20 degrees. Since the S and P polarizations are transmitted with different attenuations, the distribution of surface normals leads to a reduction in contrast. FIG. 12 shows a curve depicting transmission coefficients of S and P waves with respect to the incident angle, and FIG. 13 shows the contrast (θi, n1, n2, N) which is the contrast of the system. Where θ i is the angle of incidence, n 1 is the refractive index of the material between the LCDs, n 2 is the refractive index of the glass, and N is the number of boundaries. As shown, the rightmost lines with RI at 1.4 and 1.5 show the best contrast since Fresnel depolarization is minimal.

  [0053] Figures 14-16 illustrate various arrangements of moiré reduction elements (eg refractive elements such as RBM). For example, in FIGS. 14 and 16, the moiré reduction element is placed on the top surface of the front display 1 as a stackable film with the patterned surface down to reduce feature size as described above. Would be possible. These implementations may or may not be used in combination with sub-pixel compression techniques. In one embodiment, pointing the patterned surface upwards will also serve as an anti-glare mechanism. However, to achieve feature sizes smaller than 70 μm, it may be necessary to embed in an optical coupling adhesive (OCA) having a refractive index of approximately 1.5. Alternatively, as shown in FIG. 15, it is also possible to place a moiré reduction element between the two LCDs (eg laminated to the back display), the divergence is larger and therefore the feature size is smaller It will be. By index matching the internal gap with a material of RI greater than 1.4 (see OCA), Fresnel depolarization will be greatly reduced, thereby improving contrast and reducing reflection. Internal gaps, index matched with glass and OCA to reduce Fresnel polarization, also improve contrast and reduce reflection. In one embodiment, the FWHM width of this implementation has a rectangular profile and may be approximately 1.8 degrees.

  [0054] According to an embodiment of the present disclosure, the use of a rectangular diffuser profile (as viewed from above, for example) as shown in FIG. 17 is in relation to the refractive beam mapper described herein. It has surprisingly been found that they have an advantageous technical quality. In other words, in one exemplary embodiment of the present invention, a rectangular-profiled diffuser plate as shown in FIG. 17 can be used for any of the refractive beam mappers in this disclosure. A beam mapping element comprising an array of rectangular microlenses such as that shown in FIG. 17 can be made, for example, by projecting a shaped laser beam onto a photoresist, such that certain illustrative examples , Each micro lens is a duplicate of the former. The beam mapping element of FIG. 17 can be used in any of the embodiments herein, for example for the refracted beam mapper in any of FIGS. 4-7, 14-16.

  [0055] FIG. 18 represents, for the purpose of comparison, a perfect circular filter kernel, ie no energy outside the boundaries of a circle. This kernel is convoluted with an image of pixels-a single black pixel-to determine the point spread of the system's impulse response. In FIG. 19, the radius of the circle is varied and applied to the image to determine the optimum. The lower blue line represents the overall image quality, including blur and residual pixel moiré. Note that the minimum of this function is the optimal condition. As can be seen in the upper right pixel image of FIG. 19, the circular kernel never completely suppresses the sub-pixel structure. This will in turn cause some residual moiré in the MLD system.

  [0056] In contrast, the rectangular or substantially rectangular shape (see, eg, FIG. 17) will completely or substantially eliminate any residual moiré in the MLD system. FIG. 20 shows a comparison of a rectangular mean filter (eg, a line rising to the right) with a round disk filter. It should be noted that the pixels of the model are 150 microns high / low, so the optimal rectangular filter kernel has the same size and width as the pixels when viewed from above. It can be seen in FIG. 20 that the profile of the rectangular shaped diffuser has an improved image quality cost function compared to the circular shape. The far-field profile of the diffuser affects the cost function. A rectangular industrially produced diffuser is almost twice as good as a round diffuser. In FIG. 20, IQCs for round and rectangular profiles using pixels of 150 μm diameter (length and width) are shown. The cost is minimized if all pixels are covered (i.e., the radius of the rectangle = 75 [mu] m or the width = 150 [mu] m) for the rectangular case.

  [0057] In the embodiment of the rectangular lens profile, the microlenses are characterized by a phase number M of 8 or more, more preferably 16 or more, which has been found to improve the image quality.

  Although the above disclosure describes various implementations using specific block diagrams, flowcharts, and examples, each block diagram element described and / or illustrated herein, steps of the flowcharts, The operations and / or elements may be implemented individually and / or collectively using a wide range of hardware, software, or firmware (or any combination thereof) configurations. In addition, as many other designs can be implemented to achieve the same functionality, any disclosure of the components contained within the other components should be considered as an example. is there.

  [0059] The order of the processing parameters and steps described and / or illustrated herein is given by way of example only and can be varied as desired. For example, although the steps illustrated and / or described herein may be shown or discussed in a particular order, these steps need not necessarily be performed in the order illustrated or discussed. The various exemplary methods described and / or illustrated herein may omit one or more of the steps described or illustrated herein, or be additional to those disclosed. It can also include steps.

  [0060] While various embodiments are described and / or illustrated herein in the context of a fully functional computing system, one or more of these exemplary embodiments include a distribution. Regardless of the particular type of computer readable media that may be actually employed, it may be distributed as various types of program products. The embodiments disclosed herein can also be implemented using software modules that perform certain tasks. These software modules may include scripts, batches, or other executable files that may be stored on a computer readable storage medium or within a computing system. These software modules may configure the computing system to implement one or more of the exemplary embodiments disclosed herein. The various features disclosed herein may be provided through a remote desktop environment or any other cloud computing environment.

  [0061] The above description has been described with reference to specific embodiments for the purpose of illustration. However, the illustrative discussions above are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. The embodiments best explain the principles of the present invention and its practical applications, whereby various modifications will occur to those skilled in the art having various modifications that would be suitable for the present invention and the particular use envisaged. It has been chosen and described in order to be able to make best use of the embodiments.

  [0062] Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. Those skilled in the art will readily understand from the disclosure of the present invention that they perform substantially the same function as, or achieve substantially the same result as, the corresponding embodiments described herein. Processes, machines, articles of manufacture, compositions, means, methods or steps developed later may be utilized in accordance with the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

  In an exemplary embodiment of the present invention, a first display in a first plane for displaying a first image and a second display in a second plane for displaying a second image. A display, wherein the first and second planes are disposed substantially parallel to each other, and disposed between the second display and the first and second displays, the light beam output from the second display being the first A beam mapping element comprising a plurality of microlenses configured to be directed towards a viewer through sub-pixels of a display, each of said microlenses being viewed from above to improve image quality And a beam mapping element having a substantially rectangular profile.

  [0064] In the display device of the immediately preceding paragraph, the beam mapping element may comprise a refracted beam mapper.

  [0065] In the display device according to any of the preceding two paragraphs, the beam mapping element pseudo-randomly transmits the light beam output from the second display to the viewer through the sub-pixels of the first display. It may be configured to be headed.

  [0066] In the display device of any of the preceding three paragraphs, the beam mapping element may have an asymmetric diffusion angle.

  [0067] In the display apparatus of any of the preceding four paragraphs, the beam mapping element may substantially preserve polarization.

  [0068] In the display apparatus of any of the preceding five paragraphs, the beam mapping element is a refractive optics for realizing a substantially flat top profile so that a far-field image of the output approaches a flat top profile. It may have a system.

  [0069] In the display device according to any of the preceding six paragraphs, the beam mapping element is configured to transmit light from any point on the second display as the light beam travels through the first display. It may be limited to less than the distance of the pixel offset.

  [0070] In the display device of any of the preceding seven paragraphs, each of the microlenses may have a diameter not greater than the length and / or width of a sub-pixel in the second display.

  [0071] In the display device of any of the preceding eight paragraphs, the microlens may be characterized by a phase number M of 8 or more.

  [0072] In the display device of any of the preceding nine paragraphs, the microlens may have a distribution of surface normals between 0 degrees and approximately 20 degrees.

  [0073] In the display apparatus of any of the preceding ten paragraphs, the beam mapping element may be laminated to the second display.

  [0074] In the display apparatus of any of the preceding 11 paragraphs, the curved surface of the micro-lens contacts a refractive index material facing the viewer and / or having a refractive index of at least 1.4.

  [0075] In the display device according to any of the preceding 12 paragraphs, the second display may be a back display of the display device, and the first display may be a front display of the display device.

  [0076] In the display apparatus of any of the preceding 13 paragraphs, light from a given sub-pixel in the second display may be directed towards a plurality of different sub-pixels of the first display Light from multiple different sub-pixels of the second display may travel through a given sub-pixel of the first display.

[0077] The embodiments according to the present disclosure have thus been described. Although the present disclosure has been described in certain embodiments, it should be understood that the present disclosure should not be construed as limited by such embodiments.

Claims (19)

A first display in a first plane for displaying a first image;
A second display in a second plane for displaying a second image, wherein the first and second planes are substantially parallel to one another;
A plurality of microlenses disposed between the first and second displays and configured to direct the light beam output from the second display through the sub-pixels of the first display towards the viewer A beam mapping element, each of the microlenses having a substantially rectangular profile when viewed from above to improve image quality;
A display device comprising:   The display apparatus of claim 1, wherein the beam mapping element comprises a refractive beam mapper.   Any preceding claim, wherein the beam mapping element is configured to direct the light beam output from the second display pseudo-randomly towards the viewer through the sub-pixels of the first display. The display apparatus as described in.   A display device according to any preceding claim, wherein the beam mapping element has an asymmetrical diffusion angle.   A display apparatus according to any preceding claim, wherein the beam mapping element substantially preserves polarization.   Display apparatus according to any of the preceding claims, wherein the beam mapping element comprises refractive optics for realizing a substantially flat top profile, such that the far field image of the output is close to the flat top profile. .   The beam mapping element is any preceding which limits diffusion from any point on the second display to less than an offset distance of one pixel as the light beam travels through the first display. A display device as claimed in claim.   A display device according to any preceding claim, wherein each of the microlenses has a diameter not greater than the length and / or width of a sub-pixel in the second display.   A display device according to any preceding claim, wherein the microlenses are characterized by a phase number M of 8 or more.   A display apparatus according to any preceding claim, wherein the microlenses have a distribution of surface normals between 0 degrees and approximately 20 degrees.   A display apparatus according to any preceding claim, wherein the beam mapping element is stacked on the second display.   A display device according to any preceding claim, wherein the curved surface of the microlens contacts a refractive index material having a refractive index of at least 1.4.   A display device according to any preceding claim, wherein the second display is a back display of the display device and the first display is a front display of the display device.   Rays from a given sub-pixel in the second display are directed towards a plurality of different sub-pixels of the first display, and light rays from a plurality of different sub-pixels of the second display are in the first display A display apparatus according to any preceding claim, traveling through a given sub-pixel of. A method for displaying an image via a display device, the display device comprising: a first display panel in a first plane for displaying a first image; and a display device for displaying a second image. , And a second display panel in a second plane, wherein the first and second planes are substantially parallel to one another, and the method further comprises
Directing the light beam output from the second display towards the viewer through the sub-pixels of the first display by a plurality of microlenses having a substantially rectangular profile when viewed from the viewer's point of view The micro-lens is disposed between the first and second displays, comprising the steps of
Method.   The method of claim 15, wherein the microlenses are stacked on the second display.   The method according to any of claims 15-16, wherein the second display is a back display of the display device and the first display is a front display of the display device.   Rays from a given sub-pixel in the second display are directed towards a plurality of different sub-pixels of the first display, and light rays from a plurality of different sub-pixels of the second display are in the first display A method according to any of claims 15-17, proceeding through a given sub-pixel of. A first display in a first plane for displaying a first image;
A second display in a second plane for displaying a second image, wherein the first and second planes are substantially parallel to one another;
An array of beam mapping elements disposed between the first and second displays and configured to direct the light beam output from the second display towards the viewer through the sub-pixels of the first display A refracted beam mapper, each of the beam mapping elements having a substantially rectangular profile;
A display device comprising: