HK1097921B - Display screens - Google Patents

Description

Display screen

Technical Field

The present invention relates to a display screen.

Background

A three-dimensional (3D) image may be viewed, for example, with a projection screen by projecting onto the screen two images employing light having different polarizations, each of which represents a scene viewed from one of the left and right eyes of a viewer in front of an imaginary screen. A polarizing eyepiece worn by a viewer in front of the projection screen allows only one of the two images to pass through to each eye. This allows the left and right eyes of the viewer to view the scene from different perspective angles, creating the illusion of a 3D scene.

In a typical screen, the projected light is scattered back into the viewing space and is visible from a range of viewing angles.

Disclosure of Invention

In general, in one aspect, the invention features an assembly for use in a projection screen, the assembly including: a metallic reflective surface; and a layer on the metallic reflective surface for reducing an amount of difference in reflectivity of the metallic reflective surface for incident light polarized in two different directions.

Implementations may include one or more of the following features. The layer reduces the amount of difference in reflectivity of the assembly for both polarizations of light. The layer on the metallic reflective surface has a nominal thickness between 50 and 200 nm. The layer on the metallic reflective surface has a nominal thickness of between 60 and 75nm or between 170 and 190 nm. The layer on the metallic reflective surface comprises at least one of an oxide, silicon dioxide, or titanium dioxide. The layer includes a protective layer that is harder than the metallic reflective surface. The assembly has a hardness greater than HB on the pencil hardness scale, as measured from a side of the assembly proximate the protective layer. The metallic reflective surface has a thickness of less than 200 nm. The metallic reflective surface comprises at least one of aluminum, silver, titanium, and niobium. The metallic reflective surface covers at least a portion of the assembly that receives a projected image when applied in a projection screen. The layer on the metal surface covers more than 50% of the metal reflective surface. The assembly also includes a substrate supporting the metallic reflective surface. The substrate has surface characteristics such that, when the surface angle of the substrate surface is measured in a specified direction, the percentage of the surface angle in the range of-40 to-20 degrees together with the surface angle in the range of 20 to 40 degrees is greater than 5%. The surface features have a size in the range of 0.5 to 500 μm. The surface features have a size in the range of 1 to 100 μm. The percentage of surface angles in the range of-90 to-40 degrees together with surface angles in the range of 40 to 90 degrees is less than 5%. The surface features have a size in the range of 1 to 100 μm. The layer on the metallic reflective surface comprises a plurality of sub-layers. The assembly further comprises another layer that improves stain resistance. The layer that improves stain resistance includes at least one of silicone and fluorocarbon.

In general, in another aspect, the invention features an assembly for use in a projection screen, including: a metallic reflective surface; a protective layer on the metallic reflective surface, the protective layer comprising a material and thickness that reduces depolarization of light reflected from the metallic reflective surface; and a substrate supporting the metallic reflective surface, the metallic reflective surface having surface features such that, when the surface angle of the metallic reflective surface is measured in a specified direction, a percentage of surface angles in a range of-40 to-20 degrees together with surface angles in a range of 20 to 40 degrees is greater than 5%, the surface features having dimensions in a range of 1 to 100 μm.

Implementations may include one or more of the following features. The combination of the substrate, the metallic reflective surface, and the protective layer has a hardness, as measured from the surface of the protective layer, greater than HB on the pencil hardness scale.

In general, in another aspect, the invention features an apparatus for use in a projection screen, the apparatus including: a surface having surface features such that, when the surface angle of the surface is measured in a specified direction, the percentage of surface angles in the range of-40 to-20 degrees together with surface angles in the range of 20 to 40 degrees is greater than 5%, the percentage of surface angles in the range of-90 to-40 degrees together with surface angles in the range of 40 to 90 degrees is less than 5%, the surface having a reflectance of greater than 70% for light having a wavelength between 400nm and 700nm, the surface features having a dimension of less than 1mm, and a substrate supporting the surface.

Implementations may include one or more of the following features. The surface features have a size in the range of 1 to 100 μm. There is also a substrate supporting the surface. The substrate comprises plastic or a polymer coating on plastic. The surface comprises a metallic reflective surface. The percentage of surface angles in the range of-40 to-20 degrees together with surface angles in the range of 20 to 40 degrees is greater than 10%. The percentage of surface angles in the range of-90 to-40 degrees together with surface angles in the range of 40 to 90 degrees is less than 2.5%. The percentage of surface angles in the range of-90 to-50 degrees together with surface angles in the range of 50 to 90 degrees is less than 3%. The reflectivity of the device is greater than 50% for viewing angles between-32 and 32 degrees.

In general, in another aspect, the invention features an apparatus that includes: a projection screen having a metallic reflective surface and a protective layer of silicon oxide on the reflective surface.

Implementations may include one or more of the following features. The protective layer of silicon oxide has a nominal thickness in the range of 50 to 200 nm.

In general, in another aspect, the invention features a method of making an assembly for use in a projection screen, including: providing a metallic reflective surface; and providing a layer on the metal reflective surface for reducing the amount of difference in reflectivity of the assembly for the two modes of polarized light.

Implementations may include one or more of the following features. The two modes of polarized light include a first mode in which light is linearly polarized in a first direction and a second mode in which light is linearly polarized in a second direction, the second direction being perpendicular to the first direction. The layer on the metallic reflective surface comprises a protective layer that is harder than the metallic reflective surface component. Another layer for improving antifouling property is arranged on the protective layer. The additional layer also improves the resistance to cleaning solvents. Projecting an image on a projection screen having surface features and coatings configured such that the surface of the projection screen has a reflectance greater than 50% and a depolarization of less than 1% at a horizontal viewing angle between-32 and 32 degrees compared to a reflectance at zero degrees. The surface features are configured such that, when the surface angle of the surface is measured in a given direction, the percentage of surface angles in the range of-40 to-20 degrees together with surface angles in the range of 20 to 40 degrees is greater than 5%, and the percentage of surface angles in the range of-90 to-40 degrees together with surface angles in the range of 40 to 90 degrees is less than 5%. The surface features have a size in the range of 1 to 100 μm.

Other features and advantages of the invention will be apparent from the description and from the claims.

Drawings

Fig. 1 shows a projection screen for use in a room.

Fig. 2 shows a schematic side view of the screen.

Fig. 3, 6 and 8 are micrographs.

Fig. 4 shows the surface relief.

Fig. 5, 7 and 9 show probability density curves.

Fig. 10 and 12 show light reflected from a surface.

Fig. 11 and 13 show the reflectivities of s-polarized light and p-polarized light.

Fig. 14 is a schematic side view of a screen.

Fig. 15 and 16 show spectral curves.

FIG. 17 shows polarization splitting (polarization splitting) curves.

Detailed Description

As shown in fig. 1, the projection screen 100 is suitable for viewing 2D and 3D images (or video as a series of images). To view the 3D image, the projector 102 projects an image for the left eye design using light polarized in a first direction (e.g., the polarization vector may be tilted 45 degrees counterclockwise from vertical) and projects an associated image for the right eye design using light polarized in a second direction (e.g., the polarization vector may be tilted 45 degrees clockwise from vertical). A viewer 104 sitting in front of the screen 100 wears goggles 106 having polarizing eyepieces 110, the polarizing eyepieces 110 allowing the left and right eyes of the viewer to see images designed for the left and right eyes, respectively, but not images designed for the right and left eyes, respectively. A set of front speakers 108 and back surround speakers (not shown) provide a surround sound effect. The projection screen 100 has surface features (described below) that enable the screen to achieve both a wide viewing angle and accurate 3D images.

As shown in fig. 2, in some examples, the projection screen 100 includes a substrate 120 having a diffusing surface 122. In one example, substrate 120 is a commercially available product known as Rosco 116 or 3026 from Rosco Laboratories, Inc. of Stanford, Connecticut. For example, the substrate may be plastic or a polymer coating on plastic. An aluminum reflective layer 124 is sputtered on the substrate 120 to a thickness of about 50 nm. The metal may be sputtered on the entire surface of the substrate on which the screen is made or only on a portion of the substrate. Because the reflective layer 124 is thin, the surface 126 of the reflective layer 124 generally conforms to the surface 122 and has similar surface characteristics. In an example, the reflective layer 124 reflects more than 80% of incident light in the visible spectrum (substantially from 400nm to 700nm), with the remainder being absorbed. Alternatively, it is possible to form a reflective layer having desired surface features, rather than conforming to the surface of the substrate.

A protective layer 128 of silicon oxide having a nominal thickness of between about 50 and 200nm is deposited on the reflective layer 124. We denote by nominal thickness the thickness of the coating on a rough substrate while simultaneously coating on a smooth substrate. The actual thickness of the coating on the rough substrate may vary from location to location, and the average thickness on the rough substrate may be less than the nominal thickness. The protective layer 128 is harder than the reflective layer 124 and can reduce scratches on the reflective layer. For example, the hardness of the aluminum reflective layer on the Rosco 3026 substrate may be less than 6B (on a pencil hardness scale), while the hardness of the aluminum reflective layer with the protective layer on the Rosco 3026 substrate may be F. The hardness of the reflective layer and the protective layer in other examples may be different. The silicon oxide protective layer 128 also reduces depolarization, as described below, resulting in sharper 3D images.

The three-dimensional graph 130 shown in fig. 3 is generated from a surface scan of a portion of the projection screen 100 using an atomic force microscope (Digital Instruments Nanoscope). The z-axis 139 represents the height of a point on the surface 122 at a particular coordinate of the x-axis 136 and the y-axis 138. The scan area is 100 x 100 square microns and the number of measurement points is 512 in both the x and y directions. Surface 122 has "protrusions" 132 and "slits" 134 at different angles of the surface that cause diffuse reflection of light in different directions.

As shown in fig. 4, an example of a protrusion 132 located above a reference plane 140 of the substrate 120 (e.g., the reference plane may be at the bottom surface of the substrate) is shown. In use, as shown in FIG. 1, projection screen 100 may appear flat rather than rough, or, when used in a dome theater, it may be curved (and rough). The reference plane 140 represents the plane of the substrate 120 in a local area where the screen curvature is small. The surface angle at point P of surface 122 is defined as the angle θ between surface normal vector 136 and vector 138, which is normal to reference plane 140. In some examples, more than 5% of the surfaces 122 have surface angles with absolute values in the range of 20 to 40 degrees, and less than 5% of the surfaces 122 have surface angles with absolute values in the range of 40 to 90 degrees.

In fig. 5, a graph 150 shows the probability density of the surface angle measured on the surface 122. Graph 150 is derived from the atomic force microscopy scan shown in fig. 3. The horizontal axis 160 represents surface angle and the vertical axis 162 represents probability density per degree. Curves 152 and 154 represent the probability densities of surface angles measured in the x-direction and y-direction, respectively.

If the total area under curve 152 (or 154) is normalized to 1 for surface 122, then the area 156 under curve 152 (or 154) is greater than 0.05 for angles in the range of-40 to-20 degrees along with angles in the range of 20 to 40 degrees, and the area 158 under curve 152 (or 154) is less than 0.05 for angles in the range of-90 to-40 degrees along with angles in the range of 40 to 90 degrees. Since the amount of surface area having surface angles in the range of-40 to-20 degrees together with surface angles in the range of 20 to 40 degrees is greater than 5% of the total surface area, the projection screen 100 is able to achieve a wider viewing angle in which the light intensity is above a certain threshold (e.g., 50% of the intensity present at a viewing angle of 0 degrees).

At the same time, the amount of surface area having surface angles in the range of-90 to-40 degrees along with surface angles in the range of 40 to 90 degrees is kept below 5% of the total surface area for surface 122 to reduce the amount of depolarization. Depolarization occurs when the s-polarized incident beam contains a p-polarized component after reflection (or when the p-polarized incident beam contains an s-polarized component after reflection). s-polarized light refers to light polarized in a direction perpendicular to an incident plane (plane of incidence), and p-polarized light refers to light polarized in a direction parallel to the incident plane. An entrance face is defined as a plane that includes both incoming and reflected light rays. Surface regions having surface angles in the range of-90 to-40 degrees or in the range of 40 to 90 degrees tend to induce depolarization due to the large difference in reflectance for s-polarized light and p-polarized light. Although in this example we refer to s-polarized light and p-polarized light, in other examples the polarization may be different.

When projector 102 projects an image with light polarized in a particular direction (e.g., with a polarization vector that is 45 degrees clockwise from vertical), the light incident on the convex inclined surface of screen 100 may have both an s-polarized component and a p-polarized component (because the light is not perfectly parallel or perpendicular to the plane of incidence) relative to the surface at the point of incidence. If the reflectivities for s-polarized light and p-polarized light are the same, the combination of the s-polarized component and the p-polarized component of the reflected light will produce reflected light having the same polarization vector as the incoming light. However, if the reflectivities for s-polarized light and p-polarized light are different, then the combination of the s-polarized component and the p-polarized component of the reflected light will produce reflected light having a different polarization vector than the incoming light.

The surface 122 has surface features with dimensions mostly in the range of 1 micrometer (μm) to 100 μm to produce diffuse reflection without scattering, and thus a large viewing angle without significant depolarization. Assuming that the surface 122 is horizontally disposed, the size of the surface features refers to the size of the protrusions (or gaps) represented by the horizontal distance "p" between the peaks of adjacent protrusions (as shown in FIG. 14). Surface features are mostly smaller than 100 μm and thus there are no (or only a negligible amount of) visible points on the screen. Surface features are mostly larger than 1 μm (which is larger than the wavelength of visible light) to prevent optical scattering, which tends to cause depolarization. The surface 122 also has peaks and a vertical distance "a" (see fig. 14) between adjacent slits in the range of 1 to 100 μm. Intaglio printing may be used to produce a diffusing surface with surface features in the range of 1 to 100 μm. Abrasion can also be used to make a diffusing surface, but abrasion tends to produce a large percentage of small surface features (less than 1 μm) that cause optical scattering.

Depolarization affects the sharpness of the 3D image because the image intended for the left eye can be partially seen by the right eye and vice versa, thus resulting in a ghost image. Keeping the amount of surface area having surface angles in the range of-90 to-40 degrees, together with surface angles in the range of 40 to 90 degrees, below 5% of the total surface area reduces ghost images to a level that is not readily perceived by the viewer 104.

The trade-off between reduced depolarization and wider viewing angles can be broken by different selected percentages of surface angles in the above ranges. The surface 122 may be configured in various ways to meet the selected percentage. Although a particular substrate material is used in this example, other substrate materials may utilize other surface irregularities and irregularity distributions to achieve the selected percentage.

However, a projection screen surface having at least some attributes different from surface 122 of projection screen 100 may not achieve all of the benefits of screen 100.

For example, fig. 6 and 7 show graphs derived from measurements of a screen surface having a larger surface area with larger surface angles than surface 122. In contrast, fig. 8 and 9 also show graphs derived from measurements of a screen surface having a smaller surface area with large surface angles than surface 122.

The graph 170 of fig. 6 (generated from an atomic force microscopy surface scan) represents a surface 172 in which the amount of surface area having surface angles in the range of-90 to-40 degrees, along with surface angles in the range of 40 to 90 degrees, is greater than the corresponding amount of the surface 122 of the projection screen 100. In fig. 7, a graph 180 illustrates the probability density of surface angles measured across the surface 172 (fig. 6). Curves 182 and 184 represent the probability densities of surface angles measured in the x-direction and y-direction, respectively. Comparison of the curves 182 and 184 with the curves 152 and 154 (fig. 3) shows that the surface area of the surface 172 (represented by the area 186 below the curve 182 or 184) is a greater percentage (in this example, about 10 percent) than the screens of fig. 4 and 5 with surface angles in the range of-90 to-40 degrees or 40 to 90 degrees. Although it produces a better viewing angle (because more light is diffused to a wider angle), the amount of depolarization is also greater, resulting in ghost images that degrade the 3D effect of the screen.

The graph 190 of fig. 8 (generated from an atomic force microscopy surface scan) represents a surface 192 in which the percentage of surface area having surface angles in the range of-40 to-20 degrees, along with surface angles in the range of 20 to 40 degrees, is less than the corresponding percentage of the surface 122 of the projection screen 100. The graph 200 of fig. 9 shows the probability density of the surface angle measured across the surface 192. Curves 202 and 204 represent the probability density of surface angles measured in the x-direction and y-direction, respectively. Comparison of the curves 202 and 204 with the curves 152 and 154 (fig. 3) shows that the surface area of the surface 192 (represented by the area 206 below the curve 202 or 204) having a surface angle in the range of-40 to-20 degrees or 20 to 40 degrees is a smaller percentage (in this example, about 2 percent). This produces a smaller amount of depolarization (compared to surface 172) because the angle of incidence is smaller on average when the projected light is reflected from the surface. However, since a greater percentage of projected light is reflected within a narrower angle, the viewing angle is reduced, thereby limiting the range of positions at which a viewer can sufficiently view a 3D image uniformly illuminated on the screen. This can result in "hot spots" where the center of the image is very bright and the edges are relatively dark.

Referring to fig. 10, when incident light 222 having s-and p-polarized components is reflected from the surface of the aluminum layer 220, the reflectivity of the s-and p-polarized components may be different for different incident angles θ. The s-polarized component is represented by a dot and the p-polarized component is represented by a line. Referring to fig. 11, the graph 210 includes curves 212 and 214, which respectively represent a simulation of the reflectivity of s-polarized light and p-polarized light at different angles of incidence θ, when light is reflected from a smooth surface of the aluminum layer 220. Simulations were performed using TFCalc Software from Software Spectra, Inc. of Portland, Oregon. The light wavelength in the simulation was 550 nm. When the incident angle θ is small, the reflectivities of the s-and p-polarized components are similar. However, as the incident angle θ increases, the difference in reflectivity also increases. When the incident angle θ is about 80 degrees, the difference in reflectivity may be greater than 15%. This difference, known as polarization splitting, can cause depolarization, resulting in ghost images.

As shown in fig. 12, the difference in reflectivity of the s-polarized component and the p-polarized component may be reduced by coating the reflective aluminum layer 220 with a thin layer 226 of silicon oxide (SiO). SiO is effective because it has a refractive index (n ═ 1.55) that works well with aluminum to prevent polarization splitting. Referring to fig. 13, graph 232 includes curves 228 and 230, which represent simulations of the reflectivity of s-polarized light and p-polarized light, respectively, at different angles of incidence θ as the light is reflected off of the silicon oxide layer 226 and the aluminum layer 220. The wavelength of the light is 550nm, the thickness of the silicon oxide layer 226 is 67nm, and the thickness of the aluminum layer is more than about 50 nm. Curves 228 and 232 substantially overlap, indicating that depolarization is reduced even to a negligible point. Fig. 15 is a spectral plot of the same layer combination at zero degree angle of incidence.

In another simulation, a silicon oxide layer with a thickness of 180nm was also shown, which improves the reflection of visible light while reducing depolarization. FIG. 16 shows the spectral curve of 180nm silicon oxide on 50nm aluminum at zero degree angle of incidence. FIG. 17 shows polarization splitting curves for the layer combinations at a wavelength of 550 nm.

In fig. 12, light 222 is shown to be reflected off the surface of the silicon oxide layer. Since silicon oxide is transparent to visible light, light 222 actually interacts with both silicon oxide layer 226 and aluminum layer 220 before being reflected.

Using a single layer of silicon oxide with a particular thickness can effectively reduce the depolarization of light with a particular wavelength (or narrow range of wavelengths), but is less effective at other wavelengths. Multiple coatings can be used to reduce depolarization over a wider range of wavelengths.

Additional information regarding the coatings and layers of projection screens is set forth in U.S. patent application entitled "Selective reflection" filed on even date herewith, which is hereby incorporated by reference in its entirety.

Although the simulations shown in fig. 11 and 13 are based on smooth surfaces of the aluminum layer 220 and the silicon oxide layer 226, the difference in reflectance between the s-polarization component and the p-polarization component can be reduced by the silicon oxide layer 226 even if the surfaces are rough like the surface 122 shown in fig. 3. The calculations for a smooth surface can represent a small fraction of the bumps, as long as the bumps are fairly smooth on a much smaller scale.

For projection screens used in a typical living room, it is useful for the surface of the projection screen to have a hardness greater than "HB" (based on the pencil hardness scale) with the aim of reducing scratching. For example, the silicon oxide protective layer 128 achieves an "F" hardness.

For home theater applications, in order to obtain an acceptably wide viewing angle, the reflected light intensity at a viewing angle of-32 to 32 degrees in some embodiments is greater than 50% of the reflected light intensity at direct viewing (i.e., zero viewing angle). In some examples, the surface 122 can be designed such that the reflected light intensity at a 32-degree viewing angle is around 65% of the reflected light intensity when viewed directly.

Conversely, it is also useful to keep the amount of depolarization below 1%. Depolarization can be measured as described below. Light with vertical polarization is used to project an image on a screen. A vertically aligned linear polarizer was placed before the detector. The detector measures the intensity I of the reflected light through the vertically aligned polarizer₁. Then the wire is put inThe polarizer was rotated 90 degrees to align it horizontally. The detector measures the intensity I of the reflected light through the horizontally aligned polarizer₂。I₂/I₁The ratio of (a) represents the amount of depolarization. The configuration including the silicon oxide protective layer 128 on the aluminum reflective layer on the Rosco 3026 substrate can reduce the amount of depolarization to 0.79%. Depolarization is not a strong function of wavelength.

Table 1 summarizes the properties of three projection screens: projection screen 100, projection screen a, and projection screen B. Projection screens a and B are examples of commercially available screens designed for 3D images. For the projection screen 100, the reflective layer 124 has the surface profile shown in FIG. 3. The screen 100 includes a protective layer 128 of silicon oxide over the reflective layer. The silicon oxide protective layer 128 has a nominal thickness of 134nm, although the thickness may be smaller in regions with higher surface angles. Projection screen a has a metal-based reflective surface having the profile shown in fig. 8, with no protective coating on the reflective surface. Projection screen B has a metal-based reflective surface with no protective coating on the reflective surface.

TABLE 1

Projection screen	View angle (at% of 32 degrees)	Depolarization (%)	Hardness (Pencil hardness scale)
				Screen 100	65	0.79	F
Screen A	32	0.66	Less than 6B
				Screen B	33	2.35	2H

Table 1 illustrates that projection screen 100 has a wider viewing angle than projection screens A and B, and a depolarization that is not significantly higher than projection screens A and B. The screen 100 also has an acceptable F hardness.

A coating of silicone or fluorocarbon may be added over the protective layer 128 of the projection screen 100 to improve stain resistance. The coating may be a thin layer, for example having a thickness of about 1 to 5nm, so that it does not significantly affect the optical properties of the projection screen 100. The silicone or fluorocarbon layer prevents contaminants from entering the tiny pores of the coating and makes the surface of the projection screen 100 easier to clean.

Although some examples have been discussed above, other implementations and applications are within the scope of the claims.

More complex optical coatings can be designed to minimize S and P splitting within a defined visible wavelength range. For example, in the 500 to 600nm range, the following design achieves local minima for S and P splitting.

Thickness of layer material

1 aluminium 50.0

2 SiO₂ 107.1

3 TiO₂ 62.2

4 SiO₂ 101.7

The S and P splitting as a function of wavelength can be further improved with designs having more layers.

For example, silver, chromium, titanium, niobium, or other types of metals may be used instead of aluminum as the material of the reflective layer 124. The protective layer 124 may be a different material than silicon oxide, such as silicon dioxide (SiO)₂) And titanium dioxide (TiO)₂). When different types of oxides are used, the thickness of the protective layer 124 is adjusted accordingly to achieve a reduced amount of depolarization. Generally, the following is useful: the protective coating is transparent to visible light, has a pencil hardness of at least F when deposited on aluminum on a diffusing substrate such as Rosco 3026, and is water and other solvents resistant. The thickness must be greater for lower index materials and less for higher index materials. The thickness can be adjusted to maintain the highest reflection in the desired portion of the visible spectrum.

Projection screens having a surface profile similar to that shown in fig. 3 may be employed in large conventional theaters or dome theaters. In such large-site applications, the reflected light intensity at a 32-degree viewing angle (horizontal) is greater than 30% of the reflected light intensity when viewed directly by the design of the screen reflective surface. The amount of depolarization is less than 0.7% by the design of the surface profile and coating on the metal reflective surface.

Claims (20)

1. An assembly for use in a projection screen, the assembly comprising:

a metallic reflective surface; and

a layer on the metallic reflective surface to reduce an amount of difference in reflectivity of the metallic reflective surface for incident light polarized in two different directions.

2. The assembly of claim 1, wherein the layer reduces an amount of difference in reflectivity of the assembly for two polarizations of light.

3. The assembly of claim 1, wherein the layer on the metallic reflective surface has a nominal thickness between 50 and 200 nm.

4. The assembly of claim 1, wherein the layer on the metallic reflective surface has a nominal thickness of between 60 and 75nm or between 170 and 190 nm.

5. The assembly of claim 1, wherein the layer on the metallic reflective surface comprises an oxide.

6. The assembly of claim 5, wherein the oxide comprises at least one of silicon oxide, silicon dioxide, or titanium dioxide.

7. The assembly of claim 1, wherein the layer comprises a protective layer that is harder than the metallic reflective surface.

8. The assembly of claim 1, wherein the assembly has a hardness greater than HB on a pencil hardness scale, as measured from a side of the assembly proximate the protective layer.

9. The assembly of claim 1, wherein the metallic reflective surface has a thickness of 50 nm.

10. The assembly of claim 1, wherein the metallic reflective surface comprises at least one of aluminum, silver, titanium, and niobium.

11. The assembly of claim 1, wherein the metallic reflective surface covers at least a portion of the assembly that receives a projected image when applied in a projection screen.

12. The assembly of claim 11, wherein the layer on the metal surface covers more than 50% of the metal reflective surface.

13. The assembly of claim 1, further comprising a substrate supporting the metallic reflective surface.

14. The assembly of claim 13, wherein a percentage of surface angles in a range of-40 to-20 degrees along with surface angles in a range of 20 to 40 degrees is greater than 5% when the surface angles of the substrate surface are measured in a specified direction.

15. The assembly of claim 14, wherein the substrate surface has surface features comprising protrusions and gaps having a size in the range of 1 to 100 μ ι η.

16. The assembly of claim 14, wherein the percentage of surface angles in the range of-90 to-40 degrees along with surface angles in the range of 40 to 90 degrees is less than 5%.

17. The assembly of claim 16, wherein the substrate surface has surface features comprising protrusions and gaps having a size in the range of 1 to 100 μ ι η.

18. The assembly of claim 1, wherein the layer on the metallic reflective surface comprises a plurality of sub-layers.

19. The assembly of claim 1, further comprising another layer that improves stain resistance.

20. The assembly of claim 19, wherein the layer that improves stain resistance comprises at least one of silicone and fluorocarbon.