Electronic display device with anti-aliasing

Abstract

A method for displaying a digital raster image comprising controlling groups of three colored elements, each element being a different color, each group forming an elementary element of a color image, and anti-aliasing the display. Each colored element is a plano-convex array of several light-emitting diodes (LEDs), each of said elements in a group being covered by a plate common to said LEDs and diffusing the colored light associated with said element. Anti-aliasing is achieved by applying commands of different light intensities to the LEDs within the same element. Figure for the abstract: FIGURE 3

Description

Title of the invention: Electronic display device with anti-aliasing. Field of the invention

[0001] The invention relates to the field of display screens, particularly for aeronautics, but also for other applications. State of the art

[0002] In the field of aeronautics, display screens can be placed in the cockpit of an aircraft—airplane or helicopter—civilian or military. These screens can be used for navigation, mapping, visualization of the artificial horizon, or ground handling, among other things, but other applications exist and are conceivable. Outside of aeronautics, these screens can be used for mobile phones, tablets, computers, televisions, or even as display screens in public places.

[0003] These screens are often designed using LCD (liquid crystal display) technology. Backlighting is maintained continuously, recently using white LEDs (light-emitting diodes), and depending on the orientation of the liquid crystals, light is transmitted or not transmitted at specific points. Thus, the liquid crystals define the pixels. To obtain color, three liquid crystal cells per pixel are used, each equipped, parallel to the liquid crystal, with a red, green, or blue colored filter. By activating one or more of these filters, the desired color can be obtained. The backlighting LEDs, which can be 2 to 3 mm wide, are commonly placed on the side (in a configuration known as "edge-lit"), with a planar waveguide, for example, made of PMMA (polymethyl methacrylate acrylic or plexiglass), filled throughout its volume to diffuse light onto the surface.The backlight LEDs are always on.

[0004] LCD liquid crystal display technologies, based on the transmission and blocking of light permanently present in the background, are being challenged by technologies in which colored light is emitted by LEDs, which are switched on and off to produce the image—these are known as self-emissive pixels. Thus, for example, OLED displays, without liquid crystals and without permanent backlighting, are successful in the consumer market, for example in smartphones—the pixels can be 150 µm, for example. OLEDs or organic LEDs, whose dimensions are on the order of the pixel size, are formed by superimposing several organic semiconductor layers. Micro-LEDs are somewhat smaller (down to as little as 50 µm wide, or even less), and constructed using an inorganic material, primarily gallium nitride. Three OLEDs or three micro-LEDs, one of each of the primary colors, red (approximately 630 nm), green (approximately 570 nm) and blue (approximately 450 nm) are often used to form a pixel.

[0005] OLEDs or micro-LEDs are controlled by silicon CMOS circuits or by TFT thin-film transistors. A current command is transmitted to them via these control circuits.

[0006] Micro-LEDs are envisaged that are natively of different colors, by adjusting the nature and / or thickness of the inorganic semiconductor layers of the stack. Natively blue micro-LEDs and OLEDs are also known, which are energy efficient, with a colored filter placed above the diode, possibly of the quantum dot or phosphor type, to modify the color, to generate, from the blue, either green or red depending on the size of the quantum dot, in both cases with a linewidth also quite small, at mid-peak of 20 to 30 nm.

[0007] Anti-aliasing is a set of methods used to avoid the noticeable angular shape of pixels. Pixels with varying degrees of gray or color intensity can be positioned to create smooth transitions for the eye. The position, brightness, and color of these pixels can be determined by interpolation or smoothing.

[0008] A new anti-aliasing method is proposed here, aimed at obtaining a smooth image by taking advantage of the micro-LED substrates that are now available. These are obtained by transferring micro-LEDs from a manufacturing support to a glass substrate dedicated to the screen, and only the micro-LEDs that are to be transferred are arranged on the screen substrate, with the spacing between the micro-LEDs that is desired for the screen design.

[0009] To improve existing anti-aliasing techniques, a method for displaying a matrix digital image is proposed, comprising on the one hand the control of groups of three colored elements, each element being of a different color, each group forming an elementary element or pixel of a color image, and the method comprising on the other hand an anti-aliasing treatment of the display.

[0010] This process is particular because each coloured element is a plano-convex assembly of several light-emitting diodes, each of said elements in a group being covered with a plate common to said diodes of said element and diffusing the coloured light associated with said element, the anti-aliasing treatment being carried out by applying commands of different light intensities to the diodes inside the same element.

[0011] Thanks to this technique, anti-aliasing is implemented inside the pixels. This is particularly useful for displaying video footage recorded at a given resolution on a micro-LED screen with a pixel pitch finer than the recording resolution allows. This avoids consuming significant computing power, while anti-aliasing still provides a smooth image where pixel corners are not visible. This is achieved through local dimming within individual pixels and within groups of a given color. This is very useful for drawing fine symbols. The sharpness of the anti-aliasing is improved without increasing the resolution and therefore the computational cost.

[0012] According to optional and advantageous features,

[0013] - the different light intensities inside an element constitute a intensity gradient.

[0014] - the plano-convex set is a rectangle, and that the different intensities read Miners are controlled by gradients on the first side and on the second side of the rectangle.

[0015] - light-emitting diodes are gallium nitride-based diodes, known as micro-LEDs.

[0016] - the light-emitting diodes are blue diodes, the common plates being green, red, and lightly colored.

[0017] - the common plates comprise quantum dots of different sizes to give different colors.

[0018] - the colored elements are elongated and arranged parallel to each other according to a direction transverse to the direction of elongation.

[0019] Also proposed is a device for displaying a matrix digital image comprising means for controlling groups of three colored elements of the device, each element being of a different color, each group forming an elementary element of a color image, and a means for anti-aliasing the display.

[0020] This display device is special because each coloured element is a plano-convex set of several light-emitting diodes, each of said elements in a group being covered with a plate common to said diodes of said element and diffusing the coloured light associated with said element, the anti-aliasing processing means applying commands of different light intensities to the diodes inside the same element. Brief description of the drawings

[0021] The invention will be better understood and other advantages will become apparent upon reading the following description, given by way of non-limiting example, and with reference to the accompanying figures. including:

[0022] Fig. 1 is a view of an initial arrangement of micro-LEDs according to one embodiment of the invention.

[0023] Fig. 2 is a diagram representing a method according to the invention.

[0024] Fig. 3 shows views of a display according to the invention. Detailed description of the drawings

[0025] [Fig. 1] [Fig. 1] shows a support 100, which is a rigid or semi-rigid, flat, two-sided object of constant thickness, carrying micro-LEDs 101, ... lOn arranged in a rectangular mesh or checkerboard pattern on one of its faces. The micro-LEDs 101, ... lOn are square in geometry when viewed from above. They are separated from each other by a distance of the same order of magnitude as their dimensions. In the figure, the micro-LEDs 101, ... lOn number 11 by 6, or 66 micro-LEDs. These are blue micro-LEDs, known for their high energy efficiency.

[0026] Fig. 1 proposes two ways of using the support 100, by depositing on the face which carries the micro-LEDs, plates allowing light to pass through.

[0027] In a first embodiment, shown in the upper right part of the figure, rectangular plates 201, 202 and 203 are chosen to cover 3x6 micro-LEDs and they are placed on the support 100, one next to the other, separated by a deposit of high optical density material (called black matrix). Two rows of 6 micro-LEDs are incidentally covered by the high optical density material.

[0028] Plate 201 is a red color filter based on a quantum dot (although less sophisticated solutions are possible), plate 202 is a green color filter also based on a quantum dot, and plate 203 is a passive diffusing material chosen so that the angular scattering of the three plates 201, 202, and 203 is the same. It therefore provides blue light, similar to the underlying micro-LEDs.

[0029] The set of three plates 201-203 and the micro-LEDs they cover constitutes a pixel, since the three colors formed allow by combination to obtain all the colors of the visible, and the 66 micro-LEDs are therefore controlled in such a way as to provide the color and brightness required for a pixel of this size, which corresponds to a suboptimal resolution given the small size of the micro-LEDs, but which can be quite similar to the resolution obtained with older technologies, such as LCD screens and backlighting.

[0030] [Fig. 2] In [Fig. 2], the method according to the invention is shown. In step 1, the total brightness and color of a pixel are established, and then in step 2, the brightness of each micro-LED in the pixel is adjusted, taking into account the color associated with the pixel, to obtain a pixel assembly that has the correct color and brightness, but also guarantees the smoothness of the image, despite its pixelation.

[0031] In step 3, the appropriate display is carried out on the emissive pixel screen of [Fig.1].

[0032] [Fig.3] In [Fig.3], a display on the screen of [Fig.1] is shown, at the end of The method of [Fig. 2]. Four pixels are represented, namely pixels 301 and 302 in the first row and pixels 303 and 304 in the second row. Pixels 301 and 303 are in the first column and pixels 302 and 304 are in the second column. They are contiguous. Here, a symbol is displayed on pixel 304, which is fully illuminated with high luminance across all the micro-LEDs on its surface, in its three color elements defined by colored plates (referenced 202, 202, and 203 for pixel 302, each pixel being identical in this respect).

[0033] Micro-LEDs 401 are illuminated at high intensity, micro-LEDs 402 at medium intensity (medium-high), micro-LEDs 403 at medium intensity (medium-low), and micro-LEDs 404 at low intensity. The other micro-LEDs are not illuminated. Thus, all the micro-LEDs of pixel 304 are illuminated at high intensity, and a gradient along the column direction and another gradient along the row direction are calculated and implemented to illuminate some diodes of pixels 303 and 302 near their respective boundaries with pixel 304 at high intensity, then, moving away from pixel 304, at medium-high intensity, then at medium-low intensity, and finally at low intensity.

[0034] This allows for fine anti-aliasing, since it is based on attenuation within the pixels, or even within the basic color points. The computational cost is significantly reduced compared to techniques that would require managing a higher resolution, by defining the resolution at the level of individual micro-LEDs, rather than pixels 301-304.

Claims

Demands

1. A method for displaying a digital matrix image comprising the control of groups of three colored elements (201, 202, 2023), each colored element being of a different color, each group forming an elementary pixel (301-304) of a color image, the method further comprising an anti-aliasing treatment of the display, characterized in that each colored element (201-203) is a plano-convex assembly of several light-emitting diodes (101, ... 101), each of said elements in a group being covered with a plate common to said diodes of said element and diffusing the colored light associated with said element, the anti-aliasing treatment being carried out by applying commands of different light intensities to the light-emitting diodes within the same element.

2. A method for displaying a digital matrix image according to claim 1, characterized in that the different light intensities within an element constitute an intensity gradient.

3. A method for displaying a digital matrix image according to claim 1 or claim 2, characterized in that the plano-convex assembly is a rectangle, and that the different light intensities are controlled by gradients on the first side and on the second side of the rectangle.

4. Method for displaying a digital matrix image according to any one of claims 1 to 3, characterized in that the light-emitting diodes are gallium nitride-based diodes, known as micro-LEDs.

5. Method for displaying a digital matrix image according to any one of claims 1 to 4, characterized in that the light-emitting diodes are blue diodes, the common plates being green, red, and slightly colored.

6. Method of displaying a digital matrix image according to any one of claims 1 to 5, characterized in that the common plates comprise quantum dots of different sizes to give different colors.

7. A method for displaying a digital matrix image according to any one of claims 1 to 6, characterized in that the colored elements are elongated and arranged parallel to each other in a direction transverse to the direction of elongation.

8. A display device for a matrix digital image comprising means for controlling groups of three colored elements of the device, each element being of a different color, each group forming an elementary element of a color image, and an anti-aliasing processing means for the display, characterized in that each colored element is a plano-convex array of several light-emitting diodes, each of said elements in a group being covered with a plate common to said diodes of said element and diffusing the colored light associated with said element, the anti-aliasing processing means applying commands of different light intensities to the diodes within the same element.

Images