DISPLAY DEVICE

Abstract

A display device (10) with pixel structures (PX) is provided. Each of the pixel structures (PX) has pad groups (120), light-emitting elements (130), a first metal element (162), and a second metal element (164). Each of the pad groups (120) has a pad (122). The light-emitting elements (130) are each connected to the pad groups (120). The first metal element (162) and the second metal element (164) are located outside the pad groups (120) and offset from each other. A line width (W162) of the first metal element (162) is greater than a line width (W164) of the second metal element (164). The first metal element (162) extends in a first direction (d1), and a long side (122L) of the pad (122) intersects the first direction (d1).

Description

BACKGROUND Technical field The disclosure concerns a display device. Description of the state of the art An LED display panel features an active element substrate and numerous LED elements deposited onto it. Inheriting the properties of LEDs, the LED display panel offers advantages such as energy savings, high efficiency, high brightness, and fast response time. Furthermore, compared to organic LED display panels, LED displays offer additional benefits like easy color matching, long LED lifespan, and no image shadowing. Therefore, LED displays are considered the next generation of display technology. However, when a laser bonding process is used to connect the LED and the active element substrate, uneven bond strength between the pad and the solder often arises due to variations in the distribution of a metal layer near the pad. SUMMARY The disclosure relates to a display device for improving the problem of uneven bond strength between pads and solder. According to one embodiment of the disclosure, a display device comprises a substrate and a plurality of pixel structures. The plurality of pixel structures is arranged on the substrate. Each of the plurality of pixel structures comprises a plurality of pad groups, a plurality of light-emitting elements, a first metal element, and a second metal element. Each of the plurality of pad groups comprises at least one pad or contact surface. The multiple light-emitting elements are each connected to the multiple pad groups by a connection. The first metal element and the second metal element are arranged outside the multiple pad groups and offset from each other. The line width of the first metal element is greater than the line width of the second metal element. The first metal element extends in a first direction, and a longitudinal side of the at least one contact or pad intersects the first direction. According to one embodiment of the disclosure, a display device comprises a substrate and multiple pixel structures. The multiple pixel structures are arranged on the substrate. Each of the multiple pixel structures comprises multiple pad groups, multiple light-emitting elements, a first metal element, and a second metal element. Each of the multiple pad groups comprises a first pad and a second pad. The multiple light-emitting elements are each associated with the multiple pad groups. The first metal element and the second metal element are arranged outside the multiple pad groups and offset from each other. A line width of the first metal element is greater than a line width of the second metal element. The second metal element extends in a second direction. The first direction intersects the second direction. A geometric center point of the first pad has a first distance from the first metal element in the second direction.The geometric center of the second pad has a second distance from the first metal element in the second direction. The difference between the first distance and the second distance is less than the width of the first pad in the first direction. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic top view of a display device according to one embodiment of the disclosure. Fig. 2 is a schematic cross-sectional view of the display device according to one embodiment of the disclosure. Fig. 3 is an enlarged schematic top view of a first metal element, a second metal element, and a pad group of a pixel structure according to one embodiment of the disclosure. DESCRIPTION OF THE EXECUTION FORMS Detailed reference is now made to the exemplary embodiments of the disclosure, examples of which are shown in the accompanying drawings. Wherever possible, the same reference numerals are used in the drawings and the description to refer to identical or similar parts. It is understood that when an element such as a layer, film, area, or substrate is described as "on" or "connected to" another element, it may lie directly on top of or be connected to that other element, or there may be intermediate elements. Conversely, when an element is described as "directly on" or "directly connected to" another element, there are no intermediate elements. As used here, "connection" can refer to a physical and / or electrical connection. Furthermore, "electrical connection" or "coupling" can mean that there are other elements between two elements. As used here, "approximately," "about," or "essentially" indicate that the stated value and the average value are within the acceptable range of deviation of the specific value as determined by a person with average technical knowledge, taking into account the measurement in question and a certain amount of measurement-related error (i.e., the limitations of the measuring system). For example, "approximately" may be within one or more standard deviations of the stated value, or within ±30%, ±20%, ±10%, or ±5%. Furthermore, "approximately," "about," or "essentially," as used here, may be based on optical properties, etching properties, or other characteristics to select a more acceptable range of deviation or standard deviation, and a single standard deviation cannot be applied to all properties. Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as generally understood by those skilled in the art in the field to which the disclosure belongs. It is further understood that terms as defined in commonly used dictionaries should be interpreted in a manner consistent with the relevant prior art and the background or context of the disclosure, and should not be interpreted in an idealized or overly formal manner, unless otherwise defined in the embodiments of the disclosure. Fig. 1 is a schematic top view of a display device according to one embodiment of the disclosure. Fig. 2 is a schematic cross-sectional view of the display device according to one embodiment of the disclosure. Fig. 2 corresponds to section line II' in Fig. 1. With reference to Fig. 1 and Fig. 2, a display device 10 comprises a substrate 110 and a plurality of pixel structures PX arranged on the substrate 110. The substrate 110 has a support base 112 and a control circuit layer 114 arranged on the support base 112, and the multiple pixel structures PX are electrically connected to the control circuit layer 114 of the substrate 110. Each of the pixel structures PX has a plurality of pad groups 120, each pad group 120 having at least one pad 122. In some embodiments, each pad group 120 can have a plurality of pads 122 that are structurally separated from one another, with one pad 122 being electrically connected to a subpixel drive circuit (not shown) of the drive circuit layer 114 and another pad 122 being electrically connected to a common electrode VSS of the display device 10; however, the disclosure is not limited thereto. In some embodiments, the pad 122 material can be a metal, an alloy, or a combination thereof; however, the disclosure is not limited thereto. Each of the pixel structures PX further comprises a plurality of light-emitting elements 130, each of which is connected to a plurality of pad groups 120. In some embodiments, each of the light-emitting elements 130 comprises a plurality of electrodes (not shown). The multiple electrodes (not shown) of each of the light-emitting elements 130 are each electrically connected to the multiple pads 122 of a corresponding pad group 120. In particular, in some embodiments, the pixel structure PX further comprises an insulating layer 140 arranged on the pads 122. The insulating layer 140 has a plurality of openings 142, each overlapping the plurality of pads 122. The multiple electrodes (not shown) of the light-emitting elements 130 can each be electrically connected to the multiple pads 122 via multiple solder joints 152 (for example, but not limited to, tin) in the multiple openings 142. In some embodiments, a laser bonding process can be used to connect the light-emitting elements 130 and the pad groups 120. In some embodiments, the insulating layer 140 can be made of an inorganic material (e.g., silicon oxide, silicon nitride, silicon oxynitride, or a stacked layer of at least two of the above-mentioned materials), an organic material, or a combination thereof. For example, in some embodiments, the multiple light-emitting elements 130 of the pixel structure PX can comprise a first light-emitting element 130R, a second light-emitting element 130G, and a third light-emitting element 130B, wherein the first light-emitting element 130R, the second light-emitting element 130G, and the third light-emitting element 130B are each used to emit a first color light, a second color light, and a third color light that are distinct from one another. In some embodiments, the first color light, the second color light, and the third color light are, for example, red light, green light, and blue light, but the disclosure is not limited thereto. In one embodiment, a light-emitting element 130 is, for example, a micro-light-emitting diode (µLED), but the disclosure is not limited thereto. Each of the pixel structures PX further comprises a first metal element 162 and a second metal element 164. The line width W162 of the first metal element 162 is greater than the line width W164 of the second metal element 164. The first metal element 162 and the second metal element 164 are arranged outside the multiple pad groups 120 and are offset from each other. The first metal element 162 extends in a first direction d1. The second metal element 164 extends in a second direction d2. The first direction d1 and the second direction d2 intersect. In some embodiments, the first direction d1 and the second direction d2 may optionally be perpendicular to each other, but the disclosure is not limited to this. In some embodiments, the first metal element 162 and the second metal element 164 are arranged on the substrate 110. The pixel structure PX further comprises an insulating layer 170. The insulating layer 170 covers the first metal element 162, and the pad 122 is arranged on the insulating layer 170. In some embodiments, the insulating layer 170 may be made of an inorganic material (for example, silicon oxide, silicon nitride, silicon oxynitride, or a stacked layer of at least two of the above-mentioned materials), an organic material, or a combination thereof. In some embodiments, the first metal element 162 and the second metal element 164 can belong to at least one metal layer below the pad 122. In some embodiments, the first metal element 162 and the second metal element 164 are located outside the area occupied by the light-emitting element 130 and the pad 122 and are not covered by the light-emitting element 130 and the pad 122. If a laser bonding method is used to join the light-emitting element 130 and the pad 122, a laser L can be directly absorbed by the first metal element 162 and / or the second metal element 164. In some embodiments, the first metal element 162 and the second metal element 164 can optionally belong to the same metal layer 160. The first metal element 162 and the second metal element 164 can intersect and have the same potential.For example, in some embodiments, the first metal element 162 and the second metal element 164 can have the same common potential, and the first metal element 162 and the second metal element 164 can form a common electrode VSS. However, the disclosure is not limited to this. In other embodiments, the first metal element 162 and the second metal element 164 can optionally belong to different metal layers, and the first metal element 162 and the second metal element 164 do not necessarily have the same potential. In some embodiments, the first metal element 162 of each of the pixel structures PX can be connected to the first metal element 162 of an adjacent pixel structure PX. The second metal element 164 of each of the pixel structures PX can be connected to the second metal element 164 of an adjacent pixel structure PX. The plurality of first metal elements 162 and the plurality of second metal elements 164 of the plurality of adjacent pixel structures PX can enclose a region R. A region within the region R that is not occupied by the pad 122 and the light-emitting element 130 can form a penetration region of the display device 10. In some embodiments, the display device 10 can be a transparent display, but the disclosure is not limited thereto. A longitudinal side 122L of the pad 122 of each of the pad groups 120 intersects the first direction d1. In some embodiments, the longitudinal side 122L of the pad 122 may be substantially perpendicular to the first metal element 162, and the longitudinal side 122L of the pad 122 may be substantially parallel to the second metal element 164, but the disclosure is not limited thereto. In some embodiments, the multiple pads 122 of the multiple pad groups 120 may be arranged along an extension direction of the first metal element 162, i.e., the first direction d1. In some embodiments, the multiple longitudinal sides 122L of the multiple pads 122 of the multiple pad groups 120 may be substantially parallel, but the disclosure is not limited thereto. Fig. 3 is an enlarged schematic top view of a first metal element, a second metal element, and a pad group of a pixel structure according to one embodiment of the disclosure. Referring to Fig. 3, in some embodiments each of the pad groups 120 has a first contact surface or first pad 122a and a second contact surface or second pad 122b. A geometric center C1 of the first pad 122a has a first distance D1 from the first metal element 162 in the second direction d2. A geometric center C2 of the second pad 122b has a second distance D2 from the first metal element 162 in the second direction d2. A difference ΔD between the first distance D1 and the second distance D2 is less than a width W of the first pad 122a in the first direction d1.This means that the distances from the multiple pads 122, which are connected to an identical light-emitting element 130, to the thicker first metal element 162 are equal or nearly equal. When a light-emitting element 130 is connected to the multiple pads 122 using a laser bonding process, the influence of the thicker first metal element 162 on the multiple solder joints 152 on the multiple pads 122 can be equal or similar, thus improving the problem of uneven bond strength between the multiple pads 122 and the light-emitting element 130 of an identical pad group 120. According to a simulated structure, in a laser bonding process, the temperature difference of the multiple pads of an identical pad group in a conventional display device is 32 °C, whereas the temperature difference of the multiple pads 122 of an identical pad group 120 in the display device 10 of the present embodiment can be reduced to 3 °C. Referring to Fig. 1 and Fig. 2, in some embodiments the absorption rate of the second luminaire element 130G for a laser L is greater than the absorption rate of the first luminaire element 130R for the laser L, and the second light-emitting element 130G is located further from an intersection point X of the first metal element 162 and the second metal element 164 than the first light-emitting element 130R. In some embodiments the absorption rate of the third light-emitting element 130B for the laser L is greater than the absorption rate of the second light-emitting element 130G for the laser L, and the third light-emitting element 130B is located further from the intersection point X of the first metal element 162 and the second metal element 164 than the second light-emitting element 130G.This means that in some embodiments, the higher the absorption rate of the light-emitting element 130 for the laser L, the further the light-emitting element 130 is from the intersection point X of the first metal element 162 and the second metal element 164. Accordingly, the problem of uneven bond strength between the multiple light-emitting elements 130 and the multiple pad groups 120 can be improved. According to a simulated structure, in a laser bonding process, the temperature difference of the multiple pad groups of the same pixel structure in a conventional display device is 45 °C, while the temperature difference of the multiple pad groups 120 of the same pixel structure PX in the display device 10 of the present embodiment can be reduced to 22 °C. The laser L refers to a laser beam used in a laser bonding process. In some embodiments, for example, the center wavelength of the laser L is 980 nm. The third illuminating element 130B, which has the highest absorption rate for the laser L, can be an illuminating element used to emit blue light. The second illuminating element 130G, which has a medium absorption rate for the laser L, can be an illuminating element used to emit green light. The first illuminating element 130R, which has the lowest absorption rate for the laser L, can be an illuminating element used to emit red light. However, the disclosure is not limited thereto. The center wavelength of the laser L can also have other wavelengths. The third illuminating element 130B with the highest absorption rate for the laser L, the second illuminating element 130G with the medium absorption rate for the laser L, and the first illuminating element 130R with the lowest absorption rate for the laser L can also be illuminating elements used to emit light of other colors. In another embodiment, the center wavelength of the laser L can also be 405 nm. The third illuminating element 130B with the highest absorption rate for the laser L can be an illuminating element used to emit red light. The second illuminating element 130G with the medium absorption rate for the laser L can be an illuminating element used to emit green light.The first light-emitting element 130R with the lowest absorption rate for the laser L can be a light-emitting element used for the emission of blue light. Referring to Fig. 2, in some embodiments the plurality of pixel structures PX can include a repaired pixel structure PXr. The plurality of light-emitting elements 130 of the repaired pixel structure PXr comprises a normal light-emitting element 130n and a repaired light-emitting element 130r. The distance D4 between the repaired light-emitting element 130r and the first metal element 162 is greater than the distance D3 between the normal light-emitting element 130n and the first metal element 162. That is, in a manufacturing process of the display device 10, when the multiple light-emitting elements 130 are first transferred, the light-emitting element 130 is arranged at an end of the pad group 120 that is closer to the first metal element 162. When the display device 10 is repaired, the repaired light-emitting element 130r is preferably arranged at another end of the pad group 120 that is farther away from the first metal element 162. DESCRIPTION OF REFERENCE NUMBERS: 10 Display device 110 Substrate 112 Carrier base 114 Control circuit layer 120 Pad group 122 Pad 122a First pad 122b Second pad 122L Long side 130 Light element 130B Third light element 130G Second light element 130R First light element 130n Normal light element 130r Repair light emission element 140, 170 Insulating layer 142 Opening 152 Solder 160 Metal layer 162 First metal element 164 Second metal element C1, C2 Geometric center D1 First distance D2 Second distance D3, D4 Distance d1 First direction d2 Second direction L Laser PX Pixel structure PXr Repaired pixel structure R Region VSS Common electrode W Width W162, W164 Line width X Intersection point II' Intersection line ΔD Difference value

Claims

A display device (10) comprising: a substrate (110); and a plurality of pixel structures (PX) arranged on the substrate (110), each of the plurality of pixel structures (PX) comprising: a plurality of pad groups (120), each of the plurality of pad groups (120) comprising at least one pad (122); a plurality of light-emitting elements (130), each of which is associated with the plurality of pad groups (120); and a first metal element (162) and a second metal element (164) arranged outside the multiple pad groups (120) and offset from each other, wherein a line width (W162) of the first metal element (162) is greater than a line width (W164) of the second metal element (164), the first metal element (162) extends in a first direction (d1) and a longitudinal side (122L) of the at least one pad (122) intersects the first direction (d1). The display device (10) according to claim 1, wherein the longitudinal side (122L) of the at least one pad (122) runs substantially parallel to the second metal element (164). Display device (10) according to claim 1, wherein the second metal element (164) extends in a second direction (d2), the first direction (d1) intersects the second direction (d2), the at least one pad (122) of each of the multiple pad groups (120) has a first pad (122a) and a second pad (122b), a geometric center (C1) of the first pad (122a) has a first distance (D1) from the first metal element (162) in the second direction (d2), a geometric center (C2) of the second pad (122b) has a second distance (D2) from the first metal element (162) in the second direction (d2), and a difference value (ΔD) between the first distance (D1) and the second distance (D2) is less than a width (W) of the first pad (122a) in the first direction (d1). The display device (10) according to claim 1, wherein the multiple light-emitting elements (130) comprise a first light-emitting element (130R) and a second light-emitting element (130G), wherein the absorption rate of the second light-emitting element (130G) for a laser (L) is greater than the absorption rate of the first light-emitting element (130R) for the laser (L) and the second light-emitting element (130G) is located further away from an intersection point (X) of the first metal element (162) and the second metal element (164) than the first light-emitting element (130R). The display device (10) according to claim 4, wherein the multiple light-emitting elements (130) further comprise a third light-emitting element (130B), wherein the absorption rate of the third light-emitting element (130B) for the laser (L) is greater than the absorption rate of the second light-emitting element (130G) for the laser (L) and the third light-emitting element (130B) is located further away from the intersection point (X) of the first metal element (162) and the second metal element (164) than the second light-emitting element (130G). The display device (10) according to claim 1, wherein the second metal element (164) extends in a second direction (d2), the first direction (d1) intersects the second direction (d2), the multiple pixel structures (PX) have a repaired pixel structure (PXr), multiple light-emitting elements (130) of the repaired pixel structure (PXr) have at least one normal light-emitting element (130n) and at least one repairing light-emitting element (130r), and a distance (D4) between the at least one repairing light-emitting element (130r) and the first metal element (162) is greater than a distance (D3) between the at least one normal light-emitting element (130n) and the first metal element (162). Display device (10) comprising: a substrate (110); and a plurality of pixel structures (PX) arranged on the substrate (110), each of the plurality of pixel structures (PX) comprising: a plurality of pad groups (120), each of the plurality of pad groups (120) comprising a first pad (122a) and a second pad (122b); a plurality of light-emitting elements (130) each associated with the plurality of pad groups (120);a first metal element (162) and a second metal element (164) arranged outside the multiple pad groups (120) and offset from each other, wherein a line width (W162) of the first metal element (162) is greater than a line width (W164) of the second metal element (164), the first metal element (162) extends in a first direction (d1), the second metal element (164) extends in a second direction (d2), the first direction (d1) intersects the second direction (d2), a geometric center (C1) of the first pad (122a) has a first distance (D1) from the first metal element (162) in the second direction (d2), a geometric center (C2) of the second pad (122b) has a second distance (D2) from the first metal element (162) in the second direction (d2), and a difference value (ΔD) between the first distance (D1) and the second Distance (D2) is smaller than a width (W) of the first pad (122a) in the first direction (d1).; The display device (10) according to claim 7, wherein the multiple light-emitting elements (130) comprise a first light-emitting element (130R) and a second light-emitting element (130G), wherein an absorption rate of the second light-emitting element (130G) for a laser (L) is greater than an absorption rate of the first light-emitting element (130R) for the laser (L) and the second light-emitting element (130G) is located further away from an intersection point (X) of the first metal element (162) and the second metal element (164) than the first light-emitting element (130R). The display device (10) according to claim 7, wherein the multiple pixel structures (PX) comprise a repaired pixel structure (PXr), multiple light-emitting elements (130) of the repaired pixel structure (PXr) comprise at least one normal light-emitting element (130n) and at least one repairing light-emitting element (130r), and a distance (D4) between the at least one repairing light-emitting element (130r) and the first metal element (162) is greater than a distance (D2) between the at least one normal light-emitting element (130n) and the first metal element (162). Display device (10) according to claim 7, wherein the longitudinal side (122L) of the first pad (122a) is substantially parallel to the second metal element (164).

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