Reduced bezel display

Abstract

An LCD display includes an active display area, a backlight source that illuminates the active display area, and an LCD display stack. The LCD display stack may include a substrate, a liquid crystal layer above the substrate, and a liquid crystal cover layer. The substrate, the liquid crystal layer, and the liquid crystal cover layer define a liquid crystal cell. The LCD display stack has an edge seal extending between the substrate and the liquid cover layer and extending across the active display area and beyond the active display area to curve around an edge of the backlight source so that the edge seal is located outside the active display area.

Description

Technical Field

[0001] The present invention generally relates to bezel reduction techniques for liquid crystal display (LCD) displays, particularly flexible LCD displays, and techniques for implementing curved LCD displays. Background Art

[0002] Displays typically include an active area on which information can be displayed, surrounded by a passive border or bezel that is not available for information display. Displays with reduced borders / bezels and curved displays are a general trend and market pull. However, this presents challenges in manufacturing, yield, and reliability. Summary of the invention

[0003] Reduced bezel display

[0004] Thus, in one aspect, an LCD (liquid crystal display) display is provided, comprising an active display area, a backlight source for illuminating the active display area, and an LCD display stack. The LCD display stack may comprise a substrate, a liquid crystal layer above the substrate, and a liquid crystal cover layer. The substrate, the liquid crystal layer, and the liquid crystal cover layer define a liquid crystal cell. In an embodiment, the LCD display stack has an edge seal extending between the substrate and the liquid cover layer.

[0005] In an embodiment, the LCD display stack extends across the active display area and beyond the active display area to curve around the edge of the backlight so that the edge seal is located outside the active display area.

[0006] That is, in embodiments, the liquid crystal cell (ie, a region of the LCD display stackup where liquid crystal (LC) material is present between the substrate and cover layer and / or edge seal) is curved around the edge of the backlight.

[0007] Surprisingly, as described in more detail later, it has been found to be advantageous to curve the entire LCD display stack around the edge of the backlight rather than reducing the number of layers to a minimum (ie to just the substrate).

[0008] In some embodiments, the LCD cell is curved around the edge of the backlight. This allows the cover layer and substrate to move laterally relative to each other (in the surface of the display) because of the presence of LC material between these layers. For similar reasons, in some embodiments, an edge seal is located behind the backlight.

[0009] As described later, in some embodiments, the LCD display stack can be bent 180 degrees and, for example, secured to the rear of the backlight or the rear of the backlight support / tray. In some other embodiments, the LCD display stack can be bent at an angle less than 180 degrees, such as 130-170 degrees, to reduce stress within the stack. Nevertheless, in such embodiments, some of the display stack is still located behind the backlight.

[0010] Positioning the edge seal behind the backlight also helps pull the display stack out to a small radius and hold the stack securely, as this helps securely attach the display stack. Thus, in an embodiment, the LCD display stack is attached to the rear of the backlight (or the other back side of the display) via an adhesive layer and the edge seal and adhesive layer overlap laterally.

[0011] Some embodiments of displays may include integrated gate drive (IGD) circuitry. Broadly speaking, this is circuitry, such as memory or shift register circuitry, that facilitates addressing pixels of a display with a reduced number of lines (electrical connections). For example, such an IGD circuit may be located on a substrate adjacent to an edge of an active area of ​​the display and may have multiple row or column lines (electrode connections) leading to the pixels of the display for driving the display. The IGD circuitry may have a smaller number of lines (e.g., one or more serial data connections) for receiving data for driving the display pixels. Thus, such an IGD circuit may significantly reduce the number of external connections required for external drive / control circuitry and may also facilitate coarser spacing of such external connections.

[0012] Although the generic term for such circuits is integrated gate driver (IGD) circuits, the term is used broadly to cover other types of circuits that may be used in a similar manner, such as any type of circuit on one or more integrated circuit dies, which is typically located near the edge of the active display area. For example, when formed by a GIP approach in which a gate driver integrated circuit is provided directly on a display panel, an integrated gate driver circuit may sometimes be referred to as a GIP (Gate in Panel) circuit.

[0013] In some embodiments, the IGD circuit is mounted on the substrate, but moved away from the edge of the active display area and around the bend to a substantially planar area of ​​the substrate (i.e., the display stack), thereby extending the connection between the display pixels and the IGD circuit. For example, in some embodiments, the edge seal, adhesive layer, and IGD circuit are all overlapped. This is not required, but can reduce the risk of device failure and therefore can improve reliability and yield.

[0014] Therefore, in some embodiments, the IGD circuit is located away from the active display area.

[0015] The electrical connection between the IGD circuit and the active display area (display pixel) may include a stack of conductive layers, the conductive layers including at least a first compliant layer of a first metal and a second protective layer of a second metal. For example, the electrical connection may have a sandwich structure, wherein the first metal layer is sandwiched between the second metal layers. In an embodiment, the compliance of the first metal is greater than the compliance of the second metal. For example, the first metal may include aluminum or gold. In an embodiment, the oxidation resistance of the second metal is greater than the oxidation resistance of the first metal. For example, the second metal may include molybdenum.

[0016] Additionally or alternatively, the electrical connections between the IGD circuitry and the active display area (display pixels) may fan out at a bend into multiple connections (and then fan back into a single connection).

[0017] Both methods can increase the flexibility of the connection.

[0018] In an embodiment, one or more encapsulation layers encapsulate the liquid crystal cell extending over the active display area, for example, below the substrate and above the cover layer. However, one or both of these may extend across the active display area and beyond the active display area to bend around the edge of the backlight. This can simplify manufacturing and improve protection of the LC cell. Additionally or alternatively, the LCD display stack can be embedded in an encapsulation material such as epoxy, wherein the LCD display stack is bent around the edge of the backlight, and optionally up to or beyond where the edge seal begins.

[0019] Typically, the backlight is attached to the display stack with a thin strip of adhesive around the edge of the backlight. However, this can obscure light from the backlight, so a small passive bezel for the active display area may be required. Some embodiments may omit the adhesive strip along the edge of the backlight near the bend. However, due to light leakage, this can result in a bright line along the edge of the active display area. Light may also leak from the bend in the display stack.

[0020] Thus, in some embodiments, the LCD display stack has a light shielding layer that is substantially continuous over the area of ​​the LCD display stack where the LCD display stack is bent around the edge of the backlight to prevent light leakage from the backlight. The light shielding layer can be formed from the same material layer used to form the color filters in a color LCD display, such as a black (i.e., light absorbing) resist layer.

[0021] In some embodiments, a backlight tray is provided to hold the backlight. In some embodiments, the backlight tray can be integrally formed with the backlight.

[0022] In some embodiments, the LCD display stack is bent around and abuts the curved edge of the backlight tray and can be adhesively bonded to the curved edge. This can help impart stability and robustness to the display.

[0023] In some embodiments, the backlight tray is configured to absorb light from the backlight at the edge of the backlight tray, for example by adding a light absorbing (black) material that suppresses the display from having bright edges. Additionally or alternatively, the refractive index of the backlight tray can be matched to the backlight and / or the interface between the backlight tray and the backlight can include a refractive index material. Both of these techniques can reduce stray light emissions from the display. This is particularly true in the case where the display stack / LC cell blocks light from passing through the stack in the curved area, for example because it includes a light blocking layer.

[0024] In some embodiments, the backlight is an edge-lit backlight and includes a light guide to distribute light from the edge of the light guide over the active display area. The light guide and backlight tray can then be integrally formed, for example, from a polymer such as poly(methyl methacrylate) (PMMA).

[0025] In some embodiments, the radius of the bend decreases around the bend from the active display area toward the back of the display. For example, the display stack may be gently curved to the back of the display and then sharply curved to, for example, attach to the back of a backlight (or another back side of a display). The edge of the backlight or the edge of the backlight tray (if present) can then conform to the bend. That is, the edge of the backlight or backlight tray can be shaped to define the shape of the display stack around the bend (while still acting as a backlight). This helps control the shape of the edge of the display while also increasing robustness and manufacturability.

[0026] In some embodiments, the LCD display is rectangular and the LCD display stack is curved around at least two adjacent lateral edges of the backlight / rectangle. The LCD display stack can be necked or notched at the corners (i.e., at one or more corners defined by at least two adjacent lateral edges of the rectangle).

[0027] Zero border display

[0028] Therefore, in one aspect, a zero-border LCD display is provided, i.e., configured to provide a planar display area in which all display edges are borderless, so that the displayed information can extend over all (i.e., each) display edges. An LCD (liquid crystal display) display may include a flexible active matrix LCD display stack. The display stack may include a flexible substrate carrying an active matrix circuit, the active matrix circuit including a TFT (thin film transistor) array for controlling display pixels. The display stack may also include a liquid crystal layer located above the substrate. The display stack may also include a liquid crystal cover layer. The flexible substrate, the liquid crystal layer, and the liquid crystal cover layer may define a liquid crystal cell. The flexible active matrix LCD display stack may define an active display area. The LCD display may also include a backlight source located behind the flexible active matrix LCD display stack to illuminate the active display area. In an embodiment, the flexible substrate of the flexible active matrix LCD display stack (including the substrate) has a notch at each corner of the planar display area and is folded (i.e., bent) around each edge of the planar display area so that the active display area extends around each edge of the planar display area of ​​the zero-border LCD display.

[0029] In this way, an "infinite" display can be produced where the displayed information extends around each edge of the display.

[0030] In an embodiment, the display area is rectangular (including square here) with four orthogonal display edges. Therefore, the backlight source may also be rectangular.

[0031] In an embodiment, the notch at each corner may be defined by a concave profile or curve in the flexible substrate (and optionally the rest of the display stack) at the corner. When configured as a zero bezel LCD display, this profile may define a concave profile at each corner of the active display area. In an embodiment, when configured as a zero bezel LCD display, the notch at each corner may be defined by a straight line passing through the corner.

[0032] In an embodiment, the notches in the flexible substrate at the corners of the planar display area define a profile (e.g., a concave profile) that cuts each corner of the planar display area. The edge of the active display area at each corner may then define a convex curve on the planar display area that is displaced away from the concave profile at the closest point of the concave profile and the convex curve. The active display area may be defined, for example, by a display stack or a portion thereof (e.g., a TFT array).

[0033] This can facilitate manufacturing and improve yields since there is a single point of closest approach for curves of opposite significance, which can facilitate tolerance and manufacturing control, thereby also facilitating bringing the two curves close to each other.

[0034] In an embodiment, the LCD display stack extends over and beyond the active display area to bend around the edge of the backlight. The flexible active matrix LCD display stack may have an edge seal extending between the substrate and the liquid cover layer. The edge seal may be located outside the active display area. That is, in an embodiment, the liquid crystal cell (i.e., the area of ​​the LCD display stack where liquid crystal (LC) material is present between the substrate and the cover layer and / or the edge seal) bends around the edge of the backlight.

[0035] Surprisingly, as described in more detail later, in some embodiments it has been found to be advantageous to curve the entire LCD display stack around the edge of the backlight rather than reducing the number of layers to a minimum (ie, to just the substrate).

[0036] In some embodiments, the LCD cell is curved around the edge of the backlight. This allows the cover layer and substrate to move laterally relative to each other (in the surface of the display) because of the presence of LC material between these layers. For similar reasons, in some embodiments, an edge seal is located behind the backlight.

[0037] As described later, in some embodiments, the LCD display stack can be bent 180 degrees and, for example, secured to the rear of the backlight or the rear of the backlight support / tray. In some other embodiments, the LCD display stack can be bent at an angle less than 180 degrees, such as 130-170 degrees, to reduce stress within the stack. Nevertheless, in such embodiments, some of the display stack is still located behind the backlight.

[0038] Positioning the edge seal behind the backlight also helps pull the display stack out to a small radius and hold the stack securely, as this helps securely attach the display stack. Thus, in an embodiment, the LCD display stack is attached to the rear of the backlight (or the other back side of the display) via an adhesive layer and the edge seal and adhesive layer overlap laterally.

[0039] Some embodiments of displays may include integrated gate drive (IGD) circuitry. Broadly speaking, this is circuitry, such as memory or shift register circuitry, that facilitates addressing pixels of a display with a reduced number of lines (electrical connections). For example, such an IGD circuit may be located on a substrate adjacent to an edge of an active area of ​​the display and may have multiple row or column lines (electrode connections) leading to the pixels of the display for driving the display. The IGD circuitry may have a smaller number of lines (e.g., one or more serial data connections) for receiving data for driving the display pixels. Thus, such an IGD circuit may significantly reduce the number of external connections required for external drive / control circuitry and may also facilitate coarser spacing of such external connections.

[0040] Although the generic term for such circuits is integrated gate driver (IGD) circuits, the term is used broadly to cover other types of circuits that may be used in a similar manner, such as any type of circuit on one or more integrated circuit dies, which is typically located near the edge of the active display area. For example, when formed by a GIP approach in which a gate driver integrated circuit is provided directly on a display panel, an integrated gate driver circuit may sometimes be referred to as a GIP (Gate in Panel) circuit.

[0041] In some embodiments, the IGD circuit is mounted on the substrate, but moved away from the edge of the active display area and around the bend to a substantially planar area of ​​the substrate (i.e., the display stack), thereby extending the connection between the display pixels and the IGD circuit. For example, in some embodiments, the edge seal, adhesive layer, and IGD circuit are all overlapped. This is not required, but can reduce the risk of device failure and therefore can improve reliability and yield.

[0042] Thus, in some embodiments, the IGD circuit is remote from the active display area. For example, the flexible substrate may extend laterally beyond the flexible active matrix LCD display stack to define one or more tabs at each of two (e.g., orthogonal) edges of a planar (e.g., rectangular) display area. The IGD circuit may then be mounted on each of the one or more tabs. In an embodiment, each of the one or more tabs is connected to an area of ​​the flexible substrate in (below) the active display area via a necked-down area where the lateral width of the tab is reduced.

[0043] The electrical connection between the IGD circuit and the active display area (display pixel) may include a stack of conductive layers, the conductive layers including at least a first compliant layer of a first metal and a second protective layer of a second metal. For example, the electrical connection may have a sandwich structure, wherein the first metal layer is sandwiched between the second metal layers. In an embodiment, the compliance of the first metal is greater than the compliance of the second metal. For example, the first metal may include aluminum or gold. In an embodiment, the oxidation resistance of the second metal is greater than the oxidation resistance of the first metal. For example, the second metal may include molybdenum.

[0044] Additionally or alternatively, the electrical connections between the IGD circuitry and the active display area (display pixels) may fan out at a bend into multiple connections (and then fan back into a single connection).

[0045] Both methods can increase the flexibility of the connection.

[0046] In an embodiment, one or more encapsulation layers encapsulate the liquid crystal cell extending over the active display area, for example, below the substrate and above the cover layer. However, one or both of these may extend across the active display area and beyond the active display area to bend around the edge of the backlight. This can simplify manufacturing and improve protection of the LC cell. Additionally or alternatively, the LCD display stack can be embedded in an encapsulation material such as epoxy, wherein the LCD display stack is bent around the edge of the backlight, and optionally up to or beyond where the edge seal begins.

[0047] Typically, the backlight is connected to the display stack with a thin strip of adhesive around the edge of the backlight. However, this can block light from the backlight, so a small passive bezel for the active display area may be required. Some embodiments may omit the adhesive strip along the edge of the backlight near the bend. However, due to light leakage, this can result in a bright line along the edge of the active display area. Light may also leak from the bend in the display stack.

[0048] Thus, in some embodiments, the LCD display stack has a light shielding layer that is substantially continuous over the area of ​​the LCD display stack where the LCD display stack is bent around the edge of the backlight to prevent light leakage from the backlight. The light shielding layer can be formed from the same material layer used to form the color filters in a color LCD display, such as a black (i.e., light absorbing) resist layer.

[0049] In some embodiments, a backlight tray is provided to hold the backlight. In some embodiments, the backlight tray can be integrally formed with the backlight.

[0050] In some embodiments, the LCD display stack is bent around and abuts the curved edge of the backlight tray and can be adhesively bonded to the curved edge. This can help impart stability and robustness to the display.

[0051] In some embodiments, the backlight tray is configured to absorb light from the backlight at the edge of the backlight tray, for example by adding a light absorbing (black) material that suppresses the display from having bright edges. Additionally or alternatively, the refractive index of the backlight tray can be matched to the backlight and / or the interface between the backlight tray and the backlight can include a refractive index material. Both of these techniques can reduce stray light emissions from the display. This is particularly true in the case where the display stack / LC cell blocks light from passing through the stack in the curved area, for example because it includes a light blocking layer.

[0052] In some embodiments, the backlight is an edge-lit backlight and includes a light guide to distribute light from an edge of the light guide over the active display area.The light guide and the backlight tray can then be integrally formed, for example, from a polymer such as PMMA.

[0053] In some embodiments, the radius of the bend decreases around the bend from the active display area toward the back of the display. For example, the display stack may be gently curved to the back of the display and then bend sharply to, for example, connect to the back of the backlight (or another back side of the display). The edge of the backlight or the edge of the backlight tray (if present) can then conform to the bend. That is, the edge of the backlight or backlight tray can be shaped to define the shape of the display stack around the bend (while still serving as a backlight). This helps control the shape of the edge of the display while also increasing robustness and manufacturability.

[0054] The methods described herein can be used with either direct-lit or edge-lit backlights.

[0055] The above described "zero bezel display" embodiments may be combined with the above described "reduced bezel display" embodiments.

[0056] Curved monitor

[0057] Thus, in one aspect, a flexible LCD (liquid crystal display) display is provided to provide a curved display area. The curved display area has a display edge and can be bent around one, two or more axes. The flexible LCD display may include a flexible active matrix LCD display stack. The flexible active matrix LCD display stack may include a flexible substrate carrying an active matrix circuit, the active matrix circuit including a TFT (thin film transistor) array for controlling display pixels. The flexible active matrix LCD display stack may also include a liquid crystal layer and a liquid crystal cover layer above the substrate. The flexible substrate, the liquid crystal layer and the liquid crystal cover layer may define a liquid crystal cell. The flexible active matrix LCD display stack may have an edge seal extending between the substrate and the liquid cover layer. The flexible active matrix LCD display stack may define an active display area.

[0058] The flexible LCD display may also include a drive circuit (e.g., an IGD (integrated gate drive) circuit) for driving the active matrix circuit. The flexible substrate may extend laterally beyond the flexible active matrix LCD display stack to define one or more tabs at each of two adjacent (e.g., orthogonal) edges of the curved display area, and the drive circuit may be mounted on each of the one or more tabs. Each of the one or more tabs may be connected to an area of ​​the flexible substrate in (i.e., below) the active display area via a necked region where the lateral width of the tab is reduced.

[0059] In some embodiments, the flexible substrate defines a plurality of protrusions at a first of two adjacent edges. The first edge is curved, and the flexible active matrix LCD display stack is bent about an axis that can be parallel to a second edge of the two adjacent edges. In an embodiment, at least for the protrusions at the first edge of the two adjacent edges, the necking region includes a compliant structure (e.g., a folded portion) and has a notch at the corner where the necking region connects to the flexible substrate. In some embodiments, the flexible active matrix LCD display stack is bent to define a cylindrical display, which has, for example, the shape of a cylinder or an elliptical cylinder. Taken together, these features facilitate the manufacture of curved (e.g., cylindrical) displays with higher reliability and manufacturing yield.

[0060] In some embodiments, the active display area is rectangular, having four orthogonal edges. However, the active display area can have other shapes, such as triangular, octagonal, or other polygonal shapes. In embodiments, the above features allow the active display area to be formed into complex convex and / or concave shapes, optionally with multiple curves, such as curving around multiple different axes.

[0061] A flexible active matrix LCD display stack may be curved so that two opposing edges (typically straight edges) of the active display area abut along a line (i.e., a connecting line), particularly where the active display area is rectangular. The LCD display stack (including the substrate) may have a notch at each end of one or both of the two opposing edges (i.e., at the corners) and be folded around one or both of the two opposing edges, respectively, to reduce the inactive area of ​​the cylindrical display in a strip along the connecting line. In particular, the LCD display stack may have a notch at each end of the two opposing edges and be folded around both of the two opposing edges so that the active display area abuts along opposite (e.g., straight) edges (which may be parallel to the axis of the cylinder) to define a substantially continuous active display area extending around the circumference of the cylindrical display.

[0062] Some embodiments of the display may include an integrated gate drive (IGD) circuit. Broadly speaking, this is a circuit that facilitates addressing the pixels of the display with a reduced number of lines (electrical connections), such as a memory or shift register circuit. For example, such an IGD circuit may be located on a substrate adjacent to the edge of the active area of ​​the display and may have multiple row or column lines (electrode connections) leading to the pixels of the display for driving the display. The IGD circuit may have a smaller number of lines (e.g., one or more serial data connections) for receiving data for driving the pixels of the display. Thus, such an IGD circuit may significantly reduce the number of external connections required for the external drive / control circuitry and may also facilitate a coarser pitch for such external connections. This in turn may facilitate curved LCD displays.

[0063] Although the generic term for such circuits is integrated gate driver (IGD) circuits, the term is broadly used to include other types of circuits that may be used in a similar manner, such as any type of circuit on one or more integrated circuit dies, which is typically located near the edge of the active display area. For example, when formed by a GIP approach in which a gate driver integrated circuit is provided directly on a display panel, an integrated gate driver circuit may sometimes be referred to as a GIP (Gate in Panel) circuit.

[0064] In some embodiments, the drive circuit includes one or more integrated circuits, namely IGD integrated circuits. The flexible LCD display may also include a rigid interconnect structure (i.e., harder than the flexible substrate) mounted on each tab carrying the one or more integrated circuits and optionally having an edge connector for external electrical connection to the LCD display. In certain arrangements, such as where the curved display is bent around a very tight curve, continuous interconnect structures may alternate above and below adjacent interconnect structures along the curve. In some other arrangements, multiple interconnect structures may define a plane and be connected to a common interconnect PCB (printed circuit board). In some embodiments, the IGD integrated circuit may be mounted directly on the flexible substrate rather than on the interconnect structure.

[0065] In embodiments, the IGD circuit is mounted on the substrate, but moved away from the edge of the active display area and around the bend to a generally flat area of ​​the underlying substrate, thereby extending the connection between the display pixels and the IGD circuit. For example, in some embodiments, the edge seal, adhesive layer, and IGD circuit all overlap. This reduces the risk of device failure, and therefore can improve reliability and yield.

[0066] The electrical connection between the IGD circuit and the active display area (display pixel) may include a stack of conductive layers, the conductive layers including at least a first compliant layer of a first metal and a second protective layer of a second metal. For example, the electrical connection may have a sandwich structure, wherein the first metal layer is sandwiched between the second metal layers. In an embodiment, the compliance of the first metal is greater than the compliance of the second metal. For example, the first metal may include aluminum or gold. In an embodiment, the oxidation resistance of the second metal is greater than the oxidation resistance of the first metal. For example, the second metal may include molybdenum. This may increase the flexibility of the connection.

[0067] Additionally or alternatively, the electrical connections between the IGD circuit and the active display area (display pixels) may fan out into multiple connections in the necking region (ie at the bend) and then may fan back into a single connection. This may also increase the flexibility of the connections.

[0068] In some embodiments, the flexible active matrix LCD display stack is bent around an axis. The flexible LCD display may also include a backlight source located behind the flexible active matrix LCD display stack to illuminate the active display area. The backlight source may be bent to confirm the curvature of the flexible active matrix LCD display stack.

[0069] Surprisingly, as described in more detail later, in some embodiments it has been found to be advantageous to curve the entire LCD display stack around the edge of the backlight rather than reducing the number of layers to a minimum (ie, to just the substrate).

[0070] In some embodiments, the LCD cell is curved around the edge of the backlight. This allows the cover layer and substrate to move laterally relative to each other (in the surface of the display) because of the presence of LC material between these layers. For similar reasons, in some embodiments, an edge seal is located behind the backlight.

[0071] As described later, in some embodiments, the LCD display stack can be bent 180 degrees and, for example, secured to the rear of the backlight or the rear of the backlight support / tray. In some other embodiments, the LCD display stack can be bent at an angle less than 180 degrees, such as 130-170 degrees, to reduce stress within the stack. Nevertheless, in such embodiments, some of the display stack is still located behind the backlight.

[0072] Positioning the edge seal behind the backlight also helps pull the display stack out to a small radius and hold the stack securely, as this helps securely attach the display stack. Thus, in an embodiment, the LCD display stack is attached to the rear of the backlight (or the other back side of the display) via an adhesive layer and the edge seal and adhesive layer overlap laterally.

[0073] In an embodiment, one or more encapsulation layers encapsulate the liquid crystal cell extending over the active display area, for example, below the substrate and above the cover layer. However, one or both of these may extend across the active display area and beyond the active display area to bend around the edge of the backlight. This can simplify manufacturing and improve protection of the LC cell. Additionally or alternatively, the LCD display stack can be embedded in an encapsulation material such as epoxy, wherein the LCD display stack is bent around the edge of the backlight, and optionally up to or beyond where the edge seal begins.

[0074] Typically, the backlight is connected to the display stack with a thin strip of adhesive around the edge of the backlight. However, this can obscure light from the backlight, so a small passive bezel for the active display area may be required. Some embodiments may omit the adhesive strip along the edge of the backlight near the bend. However, due to light leakage, this can result in a bright line along the edge of the active display area. Light may also leak from the bend in the display stack.

[0075] Thus, in some embodiments, the LCD display stack has a light shielding layer that is substantially continuous over the area of ​​the LCD display stack where the LCD display stack is bent around the edge of the backlight to prevent light leakage from the backlight. The light shielding layer can be formed from the same material layer used to form the color filters in a color LCD display, such as a black (i.e., light absorbing) resist layer.

[0076] In some embodiments, a backlight tray is provided to hold the backlight. In some embodiments, the backlight tray can be integrally formed with the backlight.

[0077] In some embodiments, the LCD display stack is bent around and abuts the curved edge of the backlight tray and can be adhesively bonded to the curved edge. This can help impart stability and robustness to the display.

[0078] In some embodiments, the backlight tray is configured to absorb light from the backlight at the edge of the backlight tray, for example by adding a light absorbing (black) material that suppresses the display from having bright edges. Additionally or alternatively, the refractive index of the backlight tray can be matched to the backlight and / or the interface between the backlight tray and the backlight can include a refractive index material. Both of these techniques can reduce stray light emissions from the display. This is particularly true in the case where the display stack / LC cell blocks light from passing through the stack in the curved area, for example because it includes a light blocking layer.

[0079] In some embodiments, the backlight is an edge-lit backlight and includes a light guide to distribute light from an edge of the light guide over the active display area.The light guide and the backlight tray can then be integrally formed, for example, from a polymer such as PMMA.

[0080] In some embodiments, the radius of the bend decreases around the bend from the active display area toward the back of the display. For example, the display stack may be gently curved to the back of the display and then bend sharply to, for example, connect to the back of the backlight (or another back side of the display). The edge of the backlight or the edge of the backlight tray (if present) can then conform to the bend. That is, the edge of the backlight or backlight tray can be shaped to define the shape of the display stack around the bend (while still serving as a backlight). This helps control the shape of the edge of the display while also increasing robustness and manufacturability.

[0081] In some embodiments, the LCD display is rectangular and the LCD display stack is curved around at least two adjacent lateral edges of the backlight / rectangle. The LCD display stack can be necked or notched at the corners (i.e., at one or more corners defined by at least two adjacent lateral edges of the rectangle).

[0082] The above described "curved display" embodiment may be combined with the above described "reduced bezel display" embodiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Embodiments of the present invention will now be described by way of example and with reference to the accompanying drawings, in which:

[0084] Figure 1 An exemplary LCD display stackup is shown.

[0085] Figure 2a and Figure 2b A display assembly for a display is shown separately, as well as details of an LCD display that is bent at two adjacent edges.

[0086] Figure 3a and Figure 3b A schematic cross-sectional view of a first display with a reduced outer frame and a schematic cross-sectional view of a display with a reduced outer frame according to an embodiment are respectively shown.

[0087] Figure 4a and Figure 4b A close-up view of the connection between the pixel and the IDG circuit, and a cross-sectional view through the connection structure are shown respectively.

[0088] Figure 5 An example of a display with a varying bend radius is shown.

[0089] Figure 6 A flexible active matrix LCD display stackup is shown.

[0090] Figure 7a and Figure 7bA zero bezel LCD display is shown, along with exemplary configurations of the corners of the active area of ​​the LCD display.

[0091] Figure 8a and Figure 8b An example of a manufactured flat LCD display with bezel-less edges and an example of a zero-bezel LCD display with bezel-less edges on all edges are shown respectively.

[0092] Figures 9a to 9c A first example, a second example, and a third example of a curved LCD display are shown.

[0093] In the drawings, like elements are denoted by like reference numerals. DETAILED DESCRIPTION

[0094] Figure 1 A schematic cross-sectional view of an exemplary LCD (liquid crystal display) display stackup 100 is shown. In the exemplary display, a stacked liquid crystal (LC) material 130 is disposed between a substrate 120 and a liquid crystal (LC) cover layer 135. The substrate layer 120 may also carry electrical connections (e.g., rows and columns of the display and interconnects), and control circuitry (not shown) for pixels of the display, such as thin film transistors (TFTs). In some embodiments, such as for flexible displays, the TFTs may be organic.

[0095] Each of the substrate 120 and LC cover layer 135 may be provided with a respective encapsulation layer 115, 140. An edge seal 125 is provided between the substrate and LC cover layer 120, 135 (in the example shown on each edge of the LC material 130) to seal and protect the liquid crystal material.

[0096] A piece of an LCD display stack including the substrate, LC cover layer and LC material may be referred to as an LC cell; as described herein, the LCD display stack extends beyond the edges of the LC cell and includes an edge seal.

[0097] LCD display stacks typically include one or more polarizing layers. Figure 1 In the structure of the present invention, the first light polarizing layer 110 is arranged below the substrate 120, and the second light polarizing layer 145 is arranged above the LC cover layer 135. In some embodiments, the encapsulation layer or each encapsulation layer can be combined with a respective light polarizing layer. In the following description, explicit reference to the polarizing layer is sometimes omitted.

[0098] The backlight layer 105 is disposed below the first light polarizing layer 110. The backlight layer 105 is a substantially separate part from the LCD display stack; the polarizer may be built into the backlight. In an embodiment, the backlight incorporates a light guide, such as a light guide made of PMMA. For example, this may allow the display to be edge-lit, such as by one or more LEDs. The backlight may also include a diffuser, such as a layer of light diffusing film, on the light guide (i.e., between the light guide and the LCD display stack). The light guide may have a back reflector.

[0099] The substrate 120 may be a glass substrate or may comprise TAC (triacetyl cellulose), for example in a flexible display. The LC cover layer 130 may comprise TAC or glass. In the case where the substrate and / or the LC cover layer comprise glass, a separate encapsulation layer may be omitted. In certain applications, the LCD display stack may be flexible, but the display as a whole may not be flexible.

[0100] The LCD display stack may include a color filter layer (not shown); this may be located on the LC cover layer 135 and may be made of a colored resist material. To reduce parallax, it helps if the color filter layer is close to the LC material layer.

[0101] Further details on suitable technologies can be found on the applicant's website and in the applicant's earlier published patent applications.

[0102] Merely by way of illustration, the total thickness of the LCD display stack may be less than 1 mm, e.g. a few hundred micrometers. The substrate and LC cover layer may each have a thickness of e.g. about 40-130 μm; the thickness of each encapsulation layer may be e.g. about 10 μm; the light polarizing layers may each have a thickness of e.g. about 50-60 μm.

[0103] Figure 2a A display assembly or panel 200 for a display is shown. The display assembly 200 includes an LCD display stackup 100 having an active (e.g. TFT addressable) area 150 of pixels for displaying information, and a set of one or more chip-on-film (COF) interconnect structures 210. In this example, each COF interconnect structure 210 includes one or more driver integrated circuits 212 and is connected to the LCD display stackup 100 via a connection area 214 and, in use, to a PTB (printed wiring board) module (not shown) or a PCB (printed circuit board) module (not shown).

[0104] More specifically, in an embodiment, the COF interconnect structure 210 may have a rigid substrate that mounts a driver integrated circuit 212 and is mechanically and electrically connected to the flexible substrate 120 via a connection area 214. The COF interconnect structure 210 may have an edge connector for connecting to additional electronic circuitry on a printed board, such as an MPWB (module printed wiring board) of a device for which an LCD display stack provides a display.

[0105] The driver integrated circuit provides row and / or column drive signals, such as gate and / or source drive signals, to the active area 150, directly or indirectly via the IGD circuit. The number of row / column lines depends on the resolution of the display; for example, for a color display with red, green, and blue sub-pixels, it may be on the order of >10 3 .

[0106] The display stack has non-actuated regions 220a-d surrounding the active area. Typically, there are connections to each lateral side of the active area 150 in regions 220b, c and at the bottom (i.e., toward the COF interconnect structure in region 220d). Connections may not be required in region 220a at the top of the active area, which may be narrow, such as having an edge seal width of <1 mm. Connections to each lateral side of the active area would cause congestion of connection lines, which can be reduced using IGD circuits.

[0107] To reduce the bezel size, the display stack can be folded along one or more of the lines 230a, b, c to move some of the passive / non-driven areas out of view, such as around the back of the display / backlight. Depending on what folds are made and where, the LCD display stack can be necked or notched 240 at two or more locations, such as at all four corners of the active area.

[0108] Figure 2b A display assembly or panel 250 is shown in which the innermost point of the neck / notch 240 defines the location of two vertical folds so that the display stack can be folded around two adjacent edges of the backlight, i.e., around adjacent lateral edges of the LCD display. The active area 150 can have rounded corners 252 to facilitate this. In an embodiment, the innermost point of the neck / notch 240 is located near the active area 150 of the display. The active area 150 can end where the curved edge begins, or can continue around one or two adjacent curved edges of the display. In an embodiment, the active area 150 surrounds at least 75 degrees or 90 degrees of the curvature radius of the backlight. In this way, in some embodiments, a rectangular display can have three or four curved edges to achieve a zero-frame display.

[0109] In the illustrated embodiment, the IDG circuitry (e.g., one or more driver integrated circuits 212) is disposed on the tabs 254 at each folded edge and may be located behind the display / backlight (at Figure 2b In an embodiment, the display panel 250 has a transparent protective layer 256 over the surface of the display, which can be bent around the edge of the display in a similar manner.

[0110] Figure 3a FIG. 4 shows a cross-sectional view of a first display 300 with a reduced border. Figure 3a In the example of FIG. 1 , the LCD display stack 100 is bent behind the display and backlight and is reduced to a minimum thickness in the area of ​​the bend 310 (i.e., the area where the substrate is non-planar). Thus, around the bend 310, the display stack is reduced to just the substrate 120 and the interconnects it carries. An edge seal 125 is located on the front of the display where the substrate is planar; the IGD circuitry can be located below the edge seal.

[0111] This has been manufactured but presents some problems in practice. For example, during manufacture, bending at the edge of the display may cause the edge seal to pull apart at location 312. Also encapsulation may be difficult if the LC cover layer 135 is not bent, the edge seal 12 must lie on the viewing surface and is therefore restricted to having some passive bezel.

[0112] Figure 3b A schematic cross-sectional view of a display 350 with reduced bezel according to an alternative approach is shown. Surprisingly, this solves the above problem by maintaining a complete liquid crystal cell (i.e., substrate 120, LC material 130, and LC cover layer 135 at least around bend 310 (i.e., where the substrate is non-planar). In some embodiments, the entire LCD display stack (without the light polarizing layer) is maintained around bend 310.

[0113] Thus, in the region of the bend, the substrate 120 and LC cover layer 135 are separated primarily by the LC material 130 (and possibly also spacers therebetween) and can therefore slide past each other. This also protects the substrate carrying interconnects and potentially other electrical features in the region of the bend.

[0114] In an embodiment, the edge seal 125 is located at the end of the liquid crystal cell, for example behind the display / backlight and / or where the substrate becomes flat again. This facilitates the substrate 120 and the LC cover layer 135 to move past each other at the bend. Placing the edge seal here also reduces the bending forces on the seal, thereby reducing the risk of the seal pulling apart and improving the reliability, robustness and yield of manufacturing displays.

[0115] In an embodiment, the backlight 105 is supported by a backlight tray 352. This may have curved or rounded edges or ends 352a to support and constrain the inner surface of the display stack around the curved portion 310. In an embodiment, the outer surface of the display stack may be protected by an encapsulation such as epoxy and / or metal such as an aluminum housing (not shown).

[0116] In embodiments, the IDG circuit 354 can be located behind the display / backlight and / or where the substrate becomes planar again, for example partially or completely overlapping the edge seal 125. This helps reduce stress on the TFTs and any vias. The connection between the IDG circuit 354 and the active area 150 of the display can be lengthened, such as Figure 4a shown.

[0117] In some embodiments, some electrical connections to the control circuitry (e.g., for pixels of the display) can be multiplexed to reduce the number of electrical connections required, thereby helping to reduce the bezel size of the active display area. For example, source lines carrying source drive signals can be multiplexed. In a similar manner, connections to an LCD display panel (e.g., source connections) can be multiplexed to reduce the number of connections required.

[0118] The display stack can be secured to the rear of the display, such as to the backlight 105 or backlight tray 352, for example, by an adhesive layer 356. This can also partially or completely overlap the edge seal 125. The adhesive layer can extend far enough along the rear of the display to resist the forces required to pull the display stack around the bend.

[0119] As shown, the bend is a 180 degree bend, but the bend could be shallower (eg, 150 degrees or less) to reduce stress on the LC cell.

[0120] Figure 4a A close-up view of a connection 362 between a pixel 360 in an active area 150 of a display and an IDG circuit 354 is shown, where the IDG circuit 354 is located below the edge seal 125 (having a border 125'). As shown, the connections fan out from the active area 150 and return to the IDG circuit so that each connection has multiple connections on the bend 310 to increase robustness and yield. The thickness of each connection can also be reduced. In addition or alternatively, the interconnect 362 can include one or more meanders.

[0121] Figure 4b A cross-sectional view through an exemplary connection structure is shown. This comprises a metal (eg aluminium) compliant layer 362a sandwiched between metal (eg molybdenum) protective layers 362b to resist oxidation and cracking.

[0122] Connection 362 may be fabricated by photolithography.

[0123] Reference again Figure 3b , light can leak from the end of the backlight 105 into the backlight tray 352. Therefore, in an embodiment, the LCD display stack can be configured to block light from passing through. The red, green, and blue filters (e.g., part of the color display stack) may be surrounded by a black area. The LCD display stack can be configured to block light using a color filter layer, for example, by extending the black area substantially continuously in the area of ​​the bend 310.

[0124] The backlight can be glued to the display stack with a thin strip of light-blocking adhesive (e.g., taped around the perimeter of the upper surface of the backlight). This can be omitted along the edge of the backlight 105 adjacent the bend 310, but this can lead to problems such as bright bands of light at the edge of the display. Therefore, the rounded edge 352a of the backlight tray can be configured to absorb light, such as by including a light-absorbing (black) material. For example, the opacity of the backlight tray can be adjusted to absorb enough light to maintain a consistent level of illumination in the area above the lightguide (i.e., to attenuate or remove the bright band), such as to make the edge of the display substantially no brighter than the central area of ​​the display. Alternatively, an absorbing band can be applied to the end of the waveguide.

[0125] Similarly or alternatively, the backlight tray or its rounded edge can be index matched to the refractive index of the backlight and / or the joint between the backlight tray or its rounded edge and the backlight can incorporate a refractive index matching material, such as an adhesive. The refractive index can be matched to better than 0.2, 0.1 or 0.05.

[0126] In an embodiment, the backlight (more specifically the light guide of the backlight) and the backlight tray can be formed integrally - in effect the light guide acts as the backlight tray. This can also reduce stray light leakage and can facilitate expansion of the active display area around the bend.

[0127] Regardless of whether the backlight tray and the backlight are integrally formed, in embodiments, the rounded edge 352a of the backlight tray may have a physical relief pattern (e.g., formed by micro-embossing) to evenly distribute light output at the bend. This may be used to illuminate the LCD display stack at the bend, for example, to expand the active display area around the bend; and / or this may be used to achieve more uniform illumination of the active display area, for example, by attenuating or removing the bright strips described above. In some embodiments, the backlight diffuser may extend partially or completely around the rounded edge; in other embodiments, the backlight diffuser may end where the rounded edge begins.

[0128] Figure 5One example of a display is shown where the radius of the bend 310 decreases around the bend from the active display area towards the rear of the display, eventually curving sharply so that it can be guided by the backlight / tray to attach to the rear of a backlight or backlight tray.

[0129] Figure 6 A flexible active matrix LCD display stack 600 for a zero bezel display is shown. The active area 150 defines a rectangular display area 602 and extends beyond each of the four fold lines 604a-d. As previously described, depending on the embodiment, the LCD display stack can extend beyond the active area on the flexible substrate 120. The flexible active matrix LCD display stack has a notch 620 at each corner of the flat rectangular display area. In the illustrated example, each notch defines a concave profile 622.

[0130] The substrate 120 defines a first set of one or more tabs 606 on a first lateral edge of the display area 602, and a second set of one or more tabs 608 on a second orthogonal lateral edge of the display area 602. Each tab is connected to a region of the flexible substrate 120 via a respective necking region 610, where the lateral width of the tab is reduced. The tabs 606, 608 may have a notch 612 where the necking region engages the flexible substrate. This is useful for stress relief, particularly when the display is bent.

[0131] In an embodiment, the tabs 608, 610 may mount driver circuits, such as IGD circuits (e.g., one or more driver integrated circuits 212). These may be mounted directly on the substrate, or may be mounted on a more rigid interconnect structure ( Figure 6 ), which may also be used to make external electrical connections to an LCD display (eg, via an edge connector).

[0132] Figure 7a A zero-frame LCD display 700 is shown having a flat rectangular display area, including Figure 6 Flexible active matrix LCD display stack 600. Tabs 606, 608 are folded behind the display, which incorporates a backlight (not shown). The inset shows a detail of the corner of the LCD display, illustrating how the active area extends from the front of the display to the back of the display, which repeats on all four edges to give the appearance of an "infinite" display.

[0133] Figure 7bAn example configuration of the corners of the active area 150 is shown. This shows a concave profile 622 defined by a notch, and in the illustrated example a further concave curve 624 defines the edge of the flexible active matrix LCD display stack. Convex curves 626 define the edge of the active display area at each corner; this may be defined, for example, by the edge of an active matrix TFT circuit. This configuration may also be used with the type of curved LCD display described later.

[0134] Figure 8a Shows that there is Figure 3b An example of a fabricated display of the structure shown. Figure 8a shows one edge of the display, but Figure 3b The structure can be replicated on more than one edge of the display. However, by using Figure 6 The flexible active matrix LCD display stack 600, as shown in reference Figure 7a and Figure 7b As described, a "zero bezel" display can be fabricated in which the active display area extends around, for example, each of the four edges of the display. Figure 8b By way of illustration incorporated into a laptop computer, as shown in reference Figure 7a and Figure 7b An example of such a zero bezel display is described.

[0135] Figure 9a A first example of a flexible LCD display 900 having a curved display area is shown, comprising Figure 6 A flexible active matrix LCD display stack 600 is provided. In this example, the flexible LCD display stack 600 is bent about an axis parallel to the second lateral edge of the display. The necked region 610 of the tab 606 (which in this example also includes a compliant structure 611, such as a V-shaped or U-shaped fold) facilitates the bending of the display, and the notch 612 and the compliant structure (if present) relieve stress.

[0136] Figure 9b A second example of a flexible LCD display 950 having a curved display area is shown, comprising Figure 6 A flexible active matrix LCD display stack 600 is shown. In this example, the flexible LCD display stack 600 is bent about an axis parallel to a first lateral edge of the display.

[0137] The opposite edges of the display intersect at line 952. In an embodiment, the active display area is folded as previously described and extends around each of the two opposite edges. In this way, the two opposite edges of the active display area can be abutted along line 952 to produce a substantially seamless display. The use of multiple tabs 608, each with a corresponding necking region 610 (each including a compliant structure 611 in this example), helps achieve a sufficient bend radius for a cylindrical display.

[0138] The necked regions 610 carry interconnects for external electrical connections to the display; mounting the drive circuitry on the tabs reduces the number of connections carried by each necked region. External electrical connections to the drive circuitry on the tabs may be made in any convenient manner. For example, depending on the bend radius and the number of connections, each tab may directly or indirectly mount an edge connector to a common printed circuit board that may be centrally located at one end of the cylindrical LCD display.

[0139] Fig.9c Shown with Figure 9b Flexible LCD display 950 is similar to flexible LCD display 950, in which the driver circuit is mounted on a more rigid interconnect structure 210, which is itself mounted on tabs 606 and can each carry a corresponding edge connector.

[0140] Figure 9b and Fig.9c The arrangement in can, for example, be used for a display on a smart speaker.

[0141] In general, the zero bezel and curved LCD displays described herein may be used, for example, in any consumer electronic device or in a land, sea, or air vehicle, such as an automobile or any type of device.

[0142] No doubt many other effective alternatives will occur to the skilled person.It should be understood that the invention is not limited to the described embodiments and encompasses modifications obvious to those skilled in the art that fall within the spirit and scope of the appended claims.

Claims

1. An LCD display, comprising: Active display area; A backlight source for illuminating the active display area; an LCD display stack comprising a substrate, a liquid crystal layer over the substrate, and a liquid crystal cover layer, wherein the substrate, the liquid crystal layer and the liquid crystal cover layer define a liquid crystal cell, and wherein the LCD display stack has an edge seal extending between the substrate and the liquid crystal cover layer; wherein the LCD display stack extends across the active display area and beyond the active display area to curve around an edge of the backlight source; and wherein the edge seal is located outside the active display area, and wherein the edge seal is located behind the backlight, and wherein the LCD display stack is attached to the rear of the backlight by an adhesive layer, and The LCD display further comprises an integrated gate drive IGD circuit, wherein the IGD circuit is displayed away from the active display area, and wherein the IGD circuit is mounted in a planar region of the substrate, and wherein the edge seal, the adhesive layer, and the IGD circuit overlap.

2. The LCD display according to claim 1, wherein: The liquid crystal cell is bent around an edge of the backlight source.

3. The LCD display according to claim 1 or 2, wherein: The electrical connection between the IGD circuit and the active display area includes a stack of conductive layers, the stack of conductive layers including at least a first compliant layer of a first metal and a second protective layer of a second metal, wherein the compliance of the first metal is greater than the compliance of the second metal, and wherein the oxidation resistance of the second metal is greater than the oxidation resistance of the first metal.

4. An LCD display according to claim 1 or 2, wherein the LCD display has electrical connections between the IGD circuit and the active display area, each of the electrical connections being configured to fan out into a plurality of connections over an area in the LCD display stack that curves around an edge of the backlight source.

5. The LCD display according to claim 1 or 2, further comprising one or more encapsulation layers to encapsulate the liquid crystal unit, wherein: The one or more encapsulation layers extend over and beyond the active display area to curve around an edge of the backlight.

6. The LCD display according to claim 1 or 2, wherein: The LCD display stack is embedded in an encapsulation material, wherein the LCD display stack is bent around the edge of the backlight.

7. The LCD display according to claim 1 or 2, wherein: The LCD display stack has a light shielding layer that is continuous over a region of the LCD display stack to prevent light leakage from the backlight source, and the LCD display stack is bent around an edge of the backlight source in the region.

8. The LCD display according to claim 7, wherein: Along the area where the LCD display stack curves around the edge of the backlight, the backlight is not bonded to the LCD display stack.

9. The LCD display according to claim 1 or 2, further comprising a backlight tray for holding the backlight, wherein: The LCD display stack is bent around and abuts the edge of the backlight tray.

10. The LCD display according to claim 1 or 2, further comprising a backlight tray for holding the backlight, wherein: The LCD display stack is curved around an edge of the backlight tray, and wherein the backlight tray is configured to absorb light from the backlight at the edge of the backlight tray such that the LCD display lacks a bright edge.

11. The LCD display according to claim 1 or 2, further comprising a backlight tray for holding the backlight, wherein: The LCD display stack is bent around the edge of the backlight tray.

12. The LCD display according to claim 1 or 2, further comprising a backlight tray for holding the backlight, wherein: The LCD display stack is bent around an edge of the backlight tray, wherein the backlight is an edge-lit backlight and includes a light guide to distribute light from an edge of the light guide over the active display area, and wherein the light guide is integrally formed with the backlight tray.

13. The LCD display according to claim 1 or 2, wherein: The radius of a region in the LCD display stackup that curves around the edge of the backlight decreases around that region from the active display area towards the rear of the display.

14. The LCD display according to claim 1 or 2, wherein: The LCD display is rectangular, wherein the LCD display stack is curved about at least two adjacent lateral edges of the rectangle, and wherein the LCD display stack is notched at one or more corners defined by the at least two adjacent lateral edges of the rectangle.

Images