ES1068666U - Rear projection screen for television plate (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Rear projection screen (1) for television sets, comprising a rear projection film (2) adhered to a transparent support (3) by a smooth face (4) of the latter, characterized by the fact that said support has a thickness comprised between 5 and 10 mm, whose free face (5) has a roughness comprised between 2.1 μm and 3.9 μm, said back-projection film (2) comprising a layer of glass diffraction microspheres (6). ) attached to a non-reflective acrylic surface (7) in which the spaces (8) comprised between said infringing glass microspheres (4) and said acrylic surface (7) are occupied by a material that absorbs ambient light. (Machine-translation by Google Translate, not legally binding)

Description

Rear projection screen for sets of television.

The present invention relates to a screen Rear projection for TV sets that improves quality of the images shot on the set with a view to its diffusion.

Background of the invention

The use of screens is known overhead projection to generate images on television sets intended to be captured by cameras for dissemination.

In this area, the use of overhead projection screens is already known, and especially for its advantages over other systems, such as LED screens or video wall screens.

However, when using the screens of overhead projection as an alternative to the two techniques mentioned not it has been imposed even massively because the solutions currently available do not solve some very serious inconveniences since the point of view of the rear projection of images for your Relay via cameras, since they are not designed specifically for use on television, namely:

- the so-called hot spot or "hot spot",  produced by the projector lens, which concentrates higher brightness in the center of the screen. Most of the overhead projection screens are based on clear materials, that allow a high gain, but that multiply this effect of hot spot.

- for the same reason, being materials  clear, the images obtained are of very low contrast, with very little saturated colors, "washed", never getting the black color

- poor angular vision, because such screens do not redistribute the light they receive from the projector, and also encourage hot spotlight, as already indicated, this "persecute" the viewer (or the camera, in this case), producing a lot of light intensity difference in the different areas of the screen, at the time that said viewer or camera moves to the sides.

- Need for a black box, since the systems based on these screens always need a box black that protects the system from ambient light, because they support very bad light pollution, due to reflections, and very especially in television sets where the foci of high intensity lighting. This results in structures bulky and bulky.

- Most rear projection screens  they have bright finishes, which makes them reflect lights and objects, as with the mentioned video wall.

Therefore, the need for have a rear projection screen that, taking advantage of obvious advantages of overhead projection over other systems, solve the inconveniences of the state of the art mentioned.

Description of the invention

For this, the present invention proposes a rear projection screen for television sets, comprising a rear projection film adhered to a transparent support by a smooth face of the latter, which is characterized by the fact that said support has a thickness between 5 and 10 mm, whose free face has a roughness comprised between 2.1 µm and 3.9 µm, said rear projection film comprising a layer of glass diffraction microspheres attached to a non-reflective acrylic surface in which the spaces comprised between said glass diffraction microspheres and said acrylic surface are occupied by a material that absorbs ambient light
such.

Preferably, the transparent support is of methacrylate or acrylic material.

Advantageously, the rear projection screen It has measures up to 3 X 2 m.

With the combination of features claimed, the inconveniences of the state of the technique, since:

1.- an optimal gain is achieved that makes it possible to obtain images with a contrast and a saturation well above those of other retro systems projection.

2.- the microspheres of the rear projection film  Redistribute the light, reducing the hot spot effect.

3.- When combined with a support with the mentioned features of roughness by the free face is achieved optimal behavior to make reflexes disappear without significantly affect the sharpness and image quality resulting. Specifically, an optimal compromise between the reflective capacity and blurring of the image that adapts especially when the screen is used to rearrange images on television sets.

4. - The thickness of the transparent support gives a large self-supporting capacity that allows large One-piece screens, as acrylic sheets are they can produce in sizes up to 6 m 2, so up to This measurement can be made in one piece. On the other hand solves the problem of blurring the image that has the most of the anti-glare treatments used in others retro projection systems, it is intense enough not to reflect, but not light enough blur the image, allowing it to be focused with great precision. Also, the nature of the material allows a screen of 3x2 meters, with a thickness of only 8 mm, do not weigh much more than about 60 Kg, so it can even be hung with steel cable of only 2 mm, which allows a light installation aesthetically speaking, structures not being necessary complex.

Brief description of the drawings

For a better understanding of how much has been exposed two drawings are accompanied in which, schematically and only to non-limiting example title, a case study of realization.

Figure 1 is a schematic section that illustrates the arrangement of the layers or sheets that constitute the overhead projection screen for television sets of the invention.

Figure 2 is a detailed section of the film of  Rear projection of the screen.

Description of a preferred embodiment

As illustrated in Figures 1 and 2, the rear projection screen 1 for television sets of the invention comprises a rear projection film 2 adhered to a transparent support 3 for a smooth face 4 of the latter.

Specifically, the invention consists in the next selection of parameters that make this screen perfectly adapted for use in television sets:

- the support, preferably methacrylate or Acrylic material, has a thickness between 5 and 10 mm

- the free face 5 has a roughness between 2.1 µm and 3.9 µm,

- the rear projection film 2 comprises a layer of glass diffraction microspheres 6 attached to a Acrylic surface 7 not reflective in which spaces 8 comprised between glass diffraction microspheres 4 and the Acrylic surface 7 are occupied by a material that absorbs the ambient light, as illustrated in detail in Figure 2.

Therefore, the invention consists of a film rear projection 2, especially low gain, with substrate dark in order to get a good color saturation and a good contrast. Said material contains micro spheres 6 which redistribute the light, making it spread across the screen more uniformly than in traditional retro systems projection.

Said retro projection material adheres to a methacrylate or acrylic 3 with an anti-reflective treatment that It makes the screen lacking reflections. This treatment consists basically that one of its faces, specifically the free face 5 (the outside, that is, the opposite of the one in which it adheres the rear projection film) is rough, with a roughness index of 3 micrometers, which has a variation of + -0.9 micrometers. This roughness index allows reflections to disappear without affect image quality in terms of sharpness, and encouraging contrast and saturation by removing reflections.

Other optical properties that make it optimal For the purpose pursued they are:

Its high transmittance in the visible field (380-780 35 nm), 92%.

A loss of reflection in the visible sector of  only 4%.

An absorption in the visible sector of less than 0.05%

An index of refraction of only 1,491 n 20 D.

As already indicated, the invention relates to to a rear projection screen for television, but there are other solutions, among which the following stand out;

1.- LED screens, which consist of cubes of  about 50-60 cm side, which can be stacked to Shape the size you want. The image is based on LEDs So the definition depends on the number of LEDs and their size. The smaller and smaller the LEDs, the greater the definition, but higher price too.

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The main problems of this system They are:

- The so-called "moire" effect that Produced by the numerous LEDs that form the screen. This effect occurs with all surfaces with complex patterns of stripes or dots, in fact it is usual to happen with certain clothing prints, and it is something that they care for a lot on television To avoid this moiré effect.

- Low definition in short planes. In the most of the cases, when short shots are made in which the LED screen is at the bottom, you can distinguish the LEDs with ease, which makes the image not visible clearly, but Just a series of points.

- The pixelated trimming of the contours. When the presenters are put in front of this type of screens, they produces a pixelated or saw cutout of its contour, something, like It is logical, undesirable.

- Fixed measurements of stackable modules, Limit the possibilities of creating different formats.

- If it's about creating a big screen format, you have to join many modules, which makes the result end is extremely heavy, being very necessary structures bulky to hold these screens.

- The high price of these systems.

2.- Video wall screens . These screens consist of several LCD monitors that join together forming a single image. As in the previous case, large formats are achieved by joining many monitors. This system has many drawbacks:

First, all monitors, be whatever they are, they have a frame, which makes the final image split by a grid formed by the united frames of the monitors

Extreme fragility of monitors in cases in which the frames have been minimized. In some cases the frames have been minimized, to the extent that make them only 2-3 mm, but that has done also said very fragile monitors, because any blow, for slight as it is, it is directly absorbed by the crystal itself, by which break easily. In these cases, despite reduce the frame, they still look, because between some boards and others lines of at least 6 mm thick are created, which continue to create a grid that split the image.

Impossibility of color adjustments. The monitors of this type have a very limited range of color settings, and can never be adjusted to the standard color temperature of the television sets, which is 3200 ° K. This makes the images in this type of system always look bluish in screen.

Regarding color, it is very common that  each monitor has color differences with the rest, which creates an undesirable effect, because each grid of the total image It can have a different hue than the rest. This, In addition, it is accentuated with wear.

The possible formats are very limited, even more  that in the case of leds, because the monitors are usually in 16: 9 or 4: 3 format, so the formats that can be created uniting them, are those.

As in the case of LEDs, if it is create a large format screen, you have to join many monitors, which makes the end result incredibly heavy, being very bulky structures necessary to hold these screens

Due to the polished finish of everyone's glass LCD monitors, these reflect a lot of light and image, being almost a mirror, which is a big disadvantage in television, where they can reflect not only the spotlights, but also elements of the same. This is highly problematic on a set of television. On the other hand, the fact that it has reflections, makes the contrast and saturation of the contents reproduced in these are low, which results in a worse quality of image.

Finally, the price, while not as high Like that of the LEDs, it is still elevated.

Faced with these solutions, this invention, as discussed, proposes a solution based on the rear projection, which makes the inconveniences disappear raised.

With this screen the large formats are They can be made in one piece, because acrylic sheets are produced in sizes of 3x2 meters, so up to this measure They can make one piece. In cases where it is it is necessary to join several vinyls to cover a methacrylate, you can do, leaving a very slight superposition of the vinyls for assume the contraction of the rear projection vinyl that occurs over time. This meeting is only a few tenths of mm, so to the eye, at an average distance, and with image It is practically imperceptible, and on screen, being reduced Everything to scale is invisible. With this system it is solved, by so much, the problem of the unions that occurs in the cases in which The large format consists of several united elements. Even in cases where several methacrylate sheets were joined, the union would be "blood", so that union will be imperceptible on camera.

This system does not produce moire effects or cropping, as the image is produced by a projector, and not elements individual, as in the case of leds.

For the same reason, the definition is always the  same, regardless of how closed (close) the blueprints. Using professional projectors that allow definitions that today are considered means (1024x768, for example) sharp images are achieved.

The problem of the reflexes is solved with the specific anti-reflective treatment of the acrylic used, which has a roughness of about 3 micrometers, with a variation of + - 0.9. This roughness causes the screen to reflect the light dispersing it, so it does not have the mirror effect of video walls . On the other hand, it solves the problem of blurring of the image that most of the anti-reflective treatments used in other retro projection systems have, since it is intense enough not to reflect, but light enough to not blur the image, allowing it to focus on The perfection.

Regarding the possible formats, the overhead projection screen of the invention there are no limits, as it they can cut the screens with laser to size and shape that you want, not only square or rectangular, but with free forms of all.

When it comes to color adjustments, Professional projectors with DLP chip technology allow virtually infinite color adjustments, either by temperature color, by RGB channel settings, or by spectrum coordinates of color, which guarantees that the colors obtained in Camera are absolutely accurate and real.

Since the image is made with a single projector, there are no color differences in different areas of the image, as is the case with the video wall system . In cases where more than one projector is used, it is possible to do what is known as " color matching ", that is, adjust the colorimetry of each projector so that they have exactly the same color settings.

Claims (3)

1. Rear projection screen (1) for television sets, comprising a rear projection film (2) adhered to a transparent support (3) by a smooth face (4) of the latter, characterized by the fact that said support has a thickness between 5 and 10 mm, whose free face (5) has a roughness between 2.1 µm and 3.9 µm, said back projection film (2) comprising a layer of glass diffraction microspheres (6) attached to a non-reflective acrylic surface (7) in which the spaces (8) between said glass diffraction microspheres (4) and said acrylic surface (7) are occupied by a material that absorbs ambient light. 2. Rear projection screen according to claim 1, characterized in that said transparent support (3) is made of methacrylate or acrylic material. 3. Rear projection screen according to any of the preceding claims, characterized in that it has measures of 3 X 2 m.