FIELD OF THE INVENTION

The present invention relates generally to inorganic light-emitting diode flat-panel displays.

BACKGROUND OF THE INVENTION

Flat-panel displays are widely used in conjunction with computing devices, in portable devices, and for entertainment devices such as televisions. Such displays typically employ an array of pixels distributed in rows and columns over a display substrate in a display area to display images, graphics, or text. In a color display, each pixel includes light emitters that emit light of different colors, such as red, green, and blue. For example, liquid crystal displays (LCDs) employ liquid crystals to block or transmit light from a backlight behind the liquid crystals and organic light-emitting diode (OLED) displays rely on passing current through a layer of organic material that glows in response to the current. Displays using inorganic light emitting diodes (LEDs) are also in widespread use for outdoor signage and have been demonstrated in a 55-inch television.

Pixels in a display are typically arranged in an array of rows and columns in a display area on a display substrate and controlled through a matrix-addressing scheme in which rows of pixels are connected to a common row-select line and columns of pixels are connected to a common column-data line. By enabling a row of pixels and concurrently providing data on all of the column-data lines, each pixel in the row receives data from a corresponding column at the same time. Each row of pixels is sequentially enabled to provide data to all of the display pixels. The row-select lines are typically controlled by a row controller and the column-data lines by a column controller.

In flat-panel display designs, the column-data lines extend past the bottom of the display area on the display substrate in a dense array where they are electrically connected to a display controller through an electrical bus such as a flex cable. The row-select lines extend into the bezel on either side of the display area and are then routed to the flex cable at the bottom of the display substrate. Generally, a bezel is the edge area of a display substrate that surrounds the display area in which the display pixels are disposed, for example the space or frame surrounding the display area. The bezel is often used for a frame to support the display substrate and to route power, ground, and control wires for the pixels in the display area of the display substrate. It is often desirable to minimize the bezel to reduce materials costs and the display size and for an improved appearance. It is also helpful for display tiles in a tiled display to have a small bezel to enable line-free tiling.

A variety of techniques are known to reduce the bezel size for displays. For example, U.S. Patent Publication No. 2015/0359065 discloses wrapping wires around an edge of the display substrate to connect them to electronic circuits on the back of the display substrate. This design requires non-standard processing methods that can be complex and difficult. U.S. Patent Publication Nos. 2002/0075440, 2008/0018583, and 2008/0012794 all disclose LCDs with row-select wires routed to the same side of the display as the column-data wires. However, since the light-controlling pixels are most effective with a large fill-factor and the wire routing and control take considerable space on the display substrate, the light controllers (e.g., liquid crystals) are provided in a separate layer disposed over the wiring and control circuit layer, increasing thickness and requiring additional structures.

Other techniques rely on obscuring the display bezel, for example U.S. Pat. No. 9,244,282 describes an optical structure with an array of prisms and U.S. Pat. No. 8,305,294 discloses display tiles with overlapping bezels. These designs increase the thickness of their respective displays.

Many large-format displays use inorganic light-emitting diodes (iLEDs) in the display pixels. However, such iLEDs are typically large (for example greater than one millimeter in diameter) and limit the display resolution. Micro-iLEDs are known that have an area less than 1 mm square, less than 100 microns square, or less than 50 microns square or have an area small enough that it is not visible to an unaided observer of the display at a designed viewing distance. U.S. Pat. No. 8,722,458 entitled Optical Systems Fabricated by Printing-Based Assembly teaches transferring light-emitting, light-sensing, or light-collecting semiconductor elements from a wafer substrate to a destination substrate such as a display substrate. However, micro-iLED displays do not, intrinsically, address issues regarding display bezels.

There is a need, therefore, for image display architectures that enable improved resolution with lower cost, and a reduced bezel size or no bezel in matrix-addressed systems.

SUMMARY OF THE INVENTION

According to certain embodiments of the present invention, a bezel-free display comprises a display substrate comprising a connection edge and one or more bezel edges, pixels individually disposed on the display substrate in rows and columns such that columns of the pixels are separated by a column distance, rows of the pixels are separated by a row distance. Each of the pixels comprises one or more inorganic micro-light-emitting diodes, each of the one or more inorganic micro-light-emitting diodes comprising a diode substrate independent, separate, and distinct from the display substrate. Column lines are disposed on the display substrate and extend toward the connection edge. Each of the column lines is electrically connected to each of the pixels in one of the columns of the pixels. A column driver is electrically connected to each of the column lines and each column driver is disposed on the display substrate. Row lines are disposed on the display substrate and each of the row lines is electrically connected to each of the pixels in one of the rows of the pixels. A row driver is electrically connected to each of the row lines and each row driver is disposed on the display substrate. One or more row-connection lines are disposed on the display substrate and each of the one or more row-connection lines is electrically connected to one of the row lines or one of the row drivers. At least one of the one or more row-connection lines is disposed at least partially between columns of the pixels. In certain embodiments, at least one row driver is spatially separated from the corresponding row by a distance less than at least one of the column distance and the row distance, at least one column driver is spatially separated from the corresponding column by a distance less than at least one of the row distance and the column distance, or both.

In some embodiments of the present invention, each pixel in one of the rows of the pixels closest to one of the one or more bezel edges is separated from the bezel edge by a distance less than or equal to the row distance. In certain embodiments, each pixel in one of the columns of the pixels closest to one of the one or more bezel edges is spatially separated from the bezel edge by a distance less than or equal to the column distance.

In some embodiments of the present invention, any combination of inorganic micro-light-emitting diodes, row drivers, or column drivers has at least one of (i) a width from 2 to no more than 5 μm, 5 to no more than 10 μm, 10 to no more than 20 μm, 20 to no more than 50 μm, or 50 to no more than 100 μm, (ii) a length from 2 to no more than 5 μm, 5 to no more than 10 μm, 10 to no more than 20 μm, 20 to no more than 50 μm, 50 to no more than 100 μm, 100 to no more than 250 μm, and (iii) a thickness from 2 to no more than 5 μm, 5 to no more than 10 μm, 10 to no more than 20 μm, or 20 to no more than 50 μm.

In some embodiments of the present invention, (i) each inorganic micro-light-emitting diode is a micro-transfer printed micro-light-emitting diode comprising a broken or separated tether, (ii) each row driver is a micro-transfer-printed micro-integrated circuit comprising a broken or separated tether, (iii) each column driver is a micro-transfer-printed micro-integrated circuit comprising a broken or separated tether, or (iv) any combination of (i), (ii), and (iii).

In some embodiments of the present invention, two or more or of the one or more row-connection lines are disposed at least partially between columns of the pixels. In some embodiments of the present invention, one of the one or more row-connection lines is disposed at least partially between one of the columns of the pixels and one of the one or more bezel edges.

In some embodiments of the present invention, a bezel-free display is a substantially single-layer display in which wires (e.g., row lines, column lines, power lines, and ground lines) and pixels are disposed substantially in a single layer on a display substrate.

In some embodiments of the present invention, a bezel-free display comprises a plurality of row drivers. Each row driver comprises a row-driver substrate separate, distinct, and independent of the display substrate and the row-driver substrate of any other row driver, and each row driver is electrically connected to one or more of the row lines. In certain embodiments, each of two or more of the plurality of row drivers is disposed between two or more of the pixels in one or two dimensions. One or more of the plurality of row drivers can be electrically connected to two row lines.

In some embodiments of the present invention, a bezel-free display comprises a plurality of column drivers. Each column driver comprises a column-driver substrate separate, distinct, and independent of the display substrate and the column-driver substrate of any other column driver, and each column driver is electrically connected to one or more of the column lines. In certain embodiments, each of two or more of a plurality of column drivers is disposed between two or more of the pixels in one or two dimensions. One or more of the plurality of column drivers can be electrically connected to two column lines.

In some embodiments of the present invention, one or more of the pixels each comprise a pixel substrate with the one or more inorganic light emitters of the pixel disposed on the pixel substrate. The pixel substrate can be micro-transfer printed onto the display substrate and the pixel substrate can comprise a broken or separated tether. The pixel substrate can have at least one of (i) an area of 10 to no more than 50 square microns, 50 to no more than 100 square microns, 100 to no more than 500 square microns, or 500 square microns to no more than 1 square mm and (ii) a thickness of 1 to no more than 5 microns, 5 to no more than 10 microns, 10 to no more than 20 microns, or 20 to no more than 50 microns.

In some embodiments of the present invention, a bezel-free display tile comprises a tile substrate comprising at least four bezel edges, two bezel edges of the at least four bezel edges are opposing row edges and two bezel edges of the at least four bezel edges are opposing column edges. Pixels are individually disposed on the tile substrate in rows and columns such that columns of the pixels are separated by a column distance, rows of the pixels are separated by a row distance, and each of the pixels comprises one or more inorganic micro-light-emitting diodes. Each of the one or more inorganic micro-light-emitting diodes comprises a diode substrate independent, separate, and distinct from the tile substrate. Column lines are disposed on the tile substrate and extend toward at least one of the two row edges. Each column line is electrically connected to each of the pixels in one of the columns of the pixels. Row lines dare disposed on the tile substrate and extend toward at least one of the two column edges. Each row line is electrically connected to each of the pixels in one of the rows of the pixels.

In some embodiments of the present invention, at least one of:a row driver is electrically connected to at least one of the row lines, the row driver disposed on the tile substrate within at least one of a column distance and a row distance of the at least one of the row lines, and(ii) a column driver is electrically connected to at least one of the column lines, the column driver disposed on the tile substrate within at least one of a row distance and a column distance of the at least one of the column lines.

In some embodiments, at least one of:(i) each pixel in one of the columns of the pixels closest to a column edge of the two opposing column edges is spatially separated from the column edge by a distance less than or equal to the column distance, and(ii) each pixel in one of the rows of the pixels closest to a row edge of the two opposing row edges is spatially separated from the row edge by a distance less than or equal to the row distance.

In some embodiments of the present invention, a row driver is disposed within at least one of a column distance and a row distance of a corresponding row line to which the row driver is electrically connected, and a column driver is disposed within at least one of a row distance and a column distance of a corresponding column line to which the column driver is electrically connected.

In some embodiments, (i) the one or more inorganic micro-light-emitting diodes are micro-transfer printed inorganic micro-light-emitting diodes each comprising a broken or separated tether, (ii) the row driver is a micro-transfer printed integrated circuit comprising a broken or separated tether, (iii) the column driver is a micro-transfer printed integrated circuit comprising a broken or separated tether, or (iv) any combination of (i), (ii), and (iii).

In some embodiments of the present invention, one or more of the pixels each comprise a pixel substrate with the one or more inorganic light emitters disposed on the pixel substrate. The pixel substrate can be micro-transfer printed onto the tile substrate, and the pixel substrate can comprise a broken or separated tether.

In some embodiments, the bezel-free display, bezel-free display tile, or bezel-free tiled display is a matrix-addressed display comprising inorganic micro-light-emitting-diodes (micro-iLEDs) and has row-select and column-data wires (row lines and column lines), as well as power and ground lines. Each micro-iLED is controlled by a row line in combination with a column line. The control can be passive-matrix control. In other embodiments, the bezel-free display is an active-matrix display and a micro-controller, for example a pixel controller, is disposed in, on, or over the display substrate in a display area in association with one or more micro-iLEDs in a pixel and is electrically connected to the one or more micro-iLEDs to control the one or more micro-iLEDs using select and data signals provided by the row lines and column lines, respectively.

In certain embodiments, micro-iLEDs are organized into pixels and a plurality of pixels forms a regular array on the display substrate in a display area or the pixels are irregularly or randomly arranged. Each pixel can comprise one or more micro-iLEDs. In certain embodiments, each pixel includes a single light emitter. In certain embodiments, each pixel includes at least three light emitters, each of the at least three light emitters emitting light of a different color, for example red, green, or blue.

In some embodiments, the one or more micro-iLEDs are disposed on a display substrate. In other embodiments, the one or more micro-iLEDs in a pixel are disposed on a pixel substrate separate and independent from the display substrate and each pixel substrate is disposed on or over the display substrate or a layer on the display substrate. A single micro-iLED, or multiple micro-iLEDs can be disposed on each pixel substrate. In other embodiments, multiple pixels share a common pixel substrate. In certain embodiments, each pixel includes a pixel controller and the pixel controller is electrically connected to the one or more micro-iLEDs in the pixel to emit light. In some embodiments, the pixel controller is located on the display substrate. In other embodiments, a pixel includes a pixel substrate separate from the display substrate and the pixel controller is located on the pixel substrate. Each pixel substrate can comprise a broken or separated tether as a consequence of micro-transfer printing the pixel substrate. In other configurations, each micro-iLED of the plurality of micro-iLEDs has a broken or separated tether as a consequence of micro-transfer printing the micro-iLEDs. Pixel controllers can be micro-transfer printed and have a broken or separated tether as a consequence of micro-transfer printing the pixel controller.

In certain embodiments, one or more electrical conductors such as row or column lines electrically connect two or more of the pixels in the display area. In certain embodiments, the one or more row or column lines conduct control signals for controlling the pixels. Power lines can conduct power to the pixels and ground lines can provide a ground reference voltage.

In certain embodiments, the display substrate or pixel substrate is at least one of plastic, glass, and sapphire. In certain embodiments, the display substrate or pixel substrate is transparent to visible light. In certain embodiments, the display substrate or pixel substrate is at least partially transparent to visible light. In certain embodiments, the display substrate or pixel substrate has no less than 30 percent transparency to visible light (e.g., no less than 30%, 50%, 70%, 80%, 90%, or 95% transparency to visible light). In certain embodiments, the pixel substrate is a semiconductor substrate, for example a silicon semiconductor.

Certain embodiments of the present invention provide bezel-free displays, bezel-free display tiles, or bezel-free tiled displays having a reduced bezel area or no bezel area, thereby reducing the size and improving the appearance of the bezel-free displays, bezel-free display tiles, or bezel-free tiled displays. In certain embodiments, a bezel-free display or bezel-free display tile is or is used in a transparent display.

