Display device

Abstract

A display device comprises a driving circuit substrate, a light-emitting element, a first packaging layer and a second packaging layer. The light-emitting element is arranged on the driving circuit substrate and is electrically connected with the driving circuit substrate; the first packaging layer is arranged on the driving circuit substrate and is provided with a plurality of reflection particles; the first packaging layer comprises a first part and a second part; the first part is arranged on the driving circuit substrate and extends outwards from the light-emitting element; the second part is arranged on the first part and covers the side wall of the light-emitting element; the density of the reflective particles of the second part is greater than that of the reflective particles of the first part; the second packaging layer is arranged on the first packaging layer and can absorb light.

Description

Technical Field

[0001] The present invention relates to an optoelectronic device, and more particularly to a display device. Background Art

[0002] A light-emitting diode display panel includes a driving circuit board and a plurality of light-emitting diode elements disposed on the driving circuit board. Inheriting the characteristics of light-emitting diodes, the light-emitting diode display panel has advantages such as power saving, high efficiency, high brightness, and fast response time. In addition, compared with an organic light-emitting diode display panel, the light-emitting diode display panel also has advantages such as easy color calibration, long luminous life, and no image burn-in. Therefore, the light-emitting diode display panel is regarded as the next-generation display technology.

[0003] Generally speaking, in order to increase the light extraction efficiency of the light-emitting diode elements, a reflective adhesive layer can be formed on the driving circuit board so that the light beams emitted from the side of the light-emitting diode elements can be reflected and then extracted. In order to enable the reflective adhesive layer to fully reflect the light beams emitted by the light-emitting diode elements, the reflective adhesive layer needs to have a certain thickness. However, on the other hand, the reflective adhesive layer should not be too thick to exceed the top surface of the light-emitting diode elements and affect light extraction. That is to say, the requirement for the thickness uniformity of the reflective adhesive layer is quite high, resulting in a low etching process margin for forming the reflective adhesive layer, which is not conducive to mass production. Summary of the Invention

[0004] An embodiment of the present invention provides a display device with a large process margin for the first encapsulation layer.

[0005] The display device of the present invention includes a driving circuit board, a light-emitting element, a first encapsulation layer, and a second encapsulation layer; the light-emitting element is disposed on the driving circuit board and electrically connected to the driving circuit board; the first encapsulation layer is disposed on the driving circuit board and has a plurality of reflective particles; the first encapsulation layer includes a first part and a second part; the first part is disposed on the driving circuit board and extends outward from the light-emitting element; the second part is disposed on the first part and covers the sidewall of the light-emitting element; the density of the reflective particles in the second part is greater than the density of the reflective particles in the first part; the second encapsulation layer is disposed on the first encapsulation layer and can absorb light.

[0006] In an embodiment of the display device of the present invention described above, the density of the plurality of reflective particles in the second part is greater than 40%, and the density of the plurality of reflective particles in the first part is less than 40%.

[0007] In an embodiment of the display device of the present invention described above, the surface roughness of a surface of the first encapsulation layer is greater than the surface roughness of a surface of the second encapsulation layer.

[0008] In an embodiment of the display device of the present invention described above, the second part of the first encapsulation layer protrudes from the second encapsulation layer.

[0009] In an embodiment of the foregoing display device of the present invention, it further includes:

[0010] A light-transmissive encapsulation layer covering the second encapsulation layer and the light-emitting element and contacting the second part of the first encapsulation layer.

[0011] In an embodiment of the foregoing display device of the present invention, the height difference of the uneven rough surface of the first encapsulation layer falls within the range of ±2 μm.

[0012] In an embodiment of the foregoing display device of the present invention, the height difference of the uneven rough surface of the second encapsulation layer falls within the range of ±0.5 μm.

[0013] In an embodiment of the foregoing display device of the present invention, it further includes a light-transmissive encapsulation layer covering the second encapsulation layer and the light-emitting element.

[0014] In an embodiment of the foregoing display device of the present invention, the second part of the first encapsulation layer protrudes from the second encapsulation layer, and the light-transmissive encapsulation layer contacts the second part of the first encapsulation layer.

[0015] In an embodiment of the foregoing display device of the present invention, the second part of the first encapsulation layer is higher than the light-emitting layer of the light-emitting element. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic cross-sectional view of a display device according to an embodiment of the present invention.

[0017] Figure 2 It is a photograph of a light-emitting element and a first encapsulation layer of a display device according to an embodiment of the present invention taken by an electron microscope.

[0018] Figure 3 It shows the undulating condition of the surface of the first encapsulation layer according to an embodiment of the present invention.

[0019] Figure 4 It shows the undulating condition of the surface of the second encapsulation layer according to an embodiment of the present invention.

[0020] Wherein, reference numerals:

[0021] 10: Display device

[0022] 110: Driving circuit substrate

[0023] 112: Pad

[0024] 120: Light-emitting element

[0025] 120a: Top surface

[0026] 120s: Side wall

[0027] 122: Light-emitting layer

[0028] 130: First encapsulation layer

[0029] 130a, 140a: Surfaces

[0030] 130g: First encapsulation material

[0031] 130p: Reflective particles

[0032] 132: First part

[0033] 134: Second part

[0034] 134a: Inclined surface

[0035] 140: Second encapsulation layer

[0036] 150: Translucent encapsulation layer

[0037] D1, D2: Distances

[0038] G112: Pad group

[0039] T132, T140, T150: Thicknesses

[0040] ΔH1, ΔH2: Height differences Detailed implementation manners

[0041] Reference will now be made in detail to the exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used in the drawings and the description to refer to the same or like parts.

[0042] It should be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" or "connected to" another element, it can be directly on or connected to the other element, or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or "directly connected to" another element, no intervening elements are present. As used herein, "connected" can refer to physical and / or electrical connection. Furthermore, "electrically connected" or "coupled" can mean that other elements exist between two elements.

[0043] As used herein, "about", "approximate", or "substantially" includes the stated value and the average value within an acceptable deviation range of a specific value determined by a person of ordinary skill in the art, taking into account the specific amount of the measurement being discussed and the error associated with the measurement (i.e., the limitations of the measurement system). For example, "about" may mean within one or more standard deviations of the stated value, or within ±30%, ±20%, ±10%, ±5%. Furthermore, "about", "approximate", or "substantially" as used herein may select a more acceptable deviation range or standard deviation depending on optical properties, etching properties, or other properties, rather than applying a single standard deviation to all properties.

[0044] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by a person of ordinary skill in the art to which this invention belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and this invention, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0045] Figure 1 It is a cross-sectional schematic diagram of a display device according to an embodiment of the present invention. Figure 2 It is a photograph of a light-emitting element and a first encapsulation layer of a display device according to an embodiment of the present invention taken by an electron microscope.

[0046] Please refer to Figure 1 , the display device 10 includes a driving circuit board 110 having a sub-pixel driving structure. In some embodiments, the sub-pixel driving structure may include a sub-pixel driving circuit (not shown) and a pad group G112 electrically connected to the sub-pixel driving circuit, where the pad group G112 includes at least one pad 112.

[0047] For example, in some embodiments, the sub-pixel driving circuit may include a first transistor (not shown), a second transistor (not shown), and a capacitor (not shown), where a first end of the first transistor is electrically connected to a corresponding data line (not shown), a control end of the first transistor is electrically connected to a corresponding scan line (not shown), a second end of the first transistor is electrically connected to a control end of the second transistor, a first end of the second transistor is electrically connected to a corresponding power line (not shown), the capacitor is electrically connected to the second end of the first transistor and the first end of the second transistor, a second end of the second transistor is electrically connected to a pad 112 of a corresponding pad group G112, and another pad 112 of the pad group G112 is electrically connected to a shared line. However, the present invention is not limited thereto, and in other embodiments, the sub-pixel driving circuit may also be other forms of circuits.

[0048] Please refer to Figure 1, the display device 10 further includes a light-emitting element 120, which is disposed on the driving circuit board 110 and electrically connected to the driving circuit board 110. Specifically, in some embodiments, the light-emitting element 120 is bonded to the pad group G112 of the driving circuit board 110 and electrically connected to the sub-pixel driving circuit (not shown) of the driving circuit board 110 through the pad group G112. The light-emitting element 120 has a light-emitting layer 122. For example, in some embodiments, the light-emitting element 120 may be a micro light-emitting diode (μLED), and the light-emitting layer 122 may be an active layer located between a first-type semiconductor layer (not labeled) and a second-type semiconductor layer (not labeled) of the micro light-emitting diode.

[0049] Please refer to Figure 1 and Figure 2 , the display device 10 further includes a first encapsulation layer 130, which is disposed on the driving circuit board 110 and has a plurality of reflective particles 130p. The first encapsulation layer 130 further has a first encapsulation material 130g, and the plurality of reflective particles 130p are distributed in the first encapsulation material 130g. In some embodiments, the reflective particles 130p are, for example, titanium dioxide (TiO2) particles, and the first encapsulation layer 130 is, for example, cured from white glue, but the present invention is not limited thereto.

[0050] The first encapsulation layer 130 includes a first part 132 and a second part 134. The first part 132 is disposed on the driving circuit board 110 and extends outward from the light-emitting element 120. The second part 134 is disposed on the first part 132 and covers the sidewall 120s of the light-emitting element 120. In some embodiments, the first part 132 of the first encapsulation layer 130 is generally located below the light-emitting layer 122 of the light-emitting element 120, and the second part 134 of the first encapsulation layer 130 is generally located beside and above the light-emitting layer 122, but the present invention is not limited thereto. In some embodiments, the first part 132 of the first encapsulation layer 130 generally fills the area of the driving circuit board 110 directly below the light-emitting element 120 and the area of the driving circuit board 110 not occupied by the light-emitting element 120, and the second part 134 of the first encapsulation layer 130 surrounds the light-emitting element 120 and covers the sidewall 120s of the light-emitting element 120. In some embodiments, the second part 134 may have an inclined surface 134a inclined with respect to the driving circuit board 110.

[0051] In some embodiments, the second part 134 of the first encapsulation layer 130 may be higher than the light-emitting layer 122 of the light-emitting element 120. In some embodiments, the light-emitting element 120 has a top surface 120a facing away from the driving circuit board 110, and the first encapsulation layer 130 does not cover the top surface 120a of the light-emitting element 120. That is, in some embodiments, the first encapsulation layer 130 does not cover the main light-emitting surface of the light-emitting element 120.

[0052] It should be noted that the density of the plurality of reflective particles 130p in the second part 134 of the first encapsulation layer 130 is greater than the density of the plurality of reflective particles 130p in the first part 132. For example, in some embodiments, the density of the plurality of reflective particles 130p in the second part 134 of the first encapsulation layer 130 is greater than 40%, and the density of the plurality of reflective particles 130p in the first part 132 of the first encapsulation layer 130 is less than 40%, but the present invention is not limited thereto. In some embodiments, the density of the plurality of reflective particles 130p in the first part 132 of the first encapsulation layer 130 may refer to: in the cross-section of the first encapsulation layer 130, the ratio of the sum of the areas of the plurality of reflective particles 130p located in the first part 132 to the area of the first part 132 of the first encapsulation layer 130 (including the first encapsulation material 130g and the plurality of reflective particles 130p); the density of the plurality of reflective particles 130p in the second part 134 of the first encapsulation layer 130 may refer to: in the cross-section of the first encapsulation layer 130, the ratio of the sum of the areas of the plurality of reflective particles 130p located in the second part 134 to the area of the second part 134 of the first encapsulation layer 130.

[0053] In some embodiments, the first encapsulation layer 130 with a special second part 134 can be formed by adjusting the etching process parameters. Adjusting the etching process parameters can cause the second part 134 of the first encapsulation layer 130 to cover the light-emitting element 120, and this method can increase the etching process margin for fabricating the first encapsulation layer 130.

[0054] Please refer to Figure 1 , in some embodiments, the distance D1 from the top surface 120a of the light-emitting element 120 to the light-emitting layer 122 of the light-emitting element 120 is, for example, 5 μm, the distance D2 from the top surface 120a of the light-emitting element 120 to the pad 112 is, for example, 7 μm, and the thickness T132 of the first part 132 of the first encapsulation layer 130 falls, for example, within the range of 1 μm to 3 μm, but the present invention is not limited thereto.

[0055] Please refer to Figure 1 , the display device 10 further includes a second encapsulation layer 140, which is disposed on the first encapsulation layer 130 and can absorb light. The top surface 120a of the light-emitting element 120 is higher than the second encapsulation layer 140. In some embodiments, the second encapsulation layer 140 includes a second encapsulation material (not shown) and a plurality of light-absorbing particles (not shown) distributed in the second encapsulation material. In some embodiments, the light-absorbing particles are, for example, carbon black particles, and the second encapsulation layer 140 is, for example, formed by curing black glue, but the present invention is not limited thereto. In some embodiments, the thickness T140 of the second encapsulation layer 140 falls, for example, within the range of 2 μm to 4 μm, but the present invention is not limited thereto.

[0056] Figure 3Shows the undulating condition of the surface of the first encapsulation layer according to an embodiment of the present invention. Figure 4 Shows the undulating condition of the surface of the second encapsulation layer according to an embodiment of the present invention. Please refer to Figure 1 , Figure 3 and Figure 4 , in some embodiments, the surface roughness of the surface 130a of the first encapsulation layer 130 is greater than the surface roughness of the surface 140a of the second encapsulation layer 140. For example, in some embodiments, the surface 130a of the first encapsulation layer 130 may be a rough surface with irregularities, and the height difference ΔH1 of the rough surface with irregularities of the first encapsulation layer 130 may fall within the range of ±2 μm; the surface 140a of the second encapsulation layer 140 may be a rough surface with irregularities, and the height difference ΔH2 of the rough surface with irregularities of the second encapsulation layer 140 may fall within the range of ±0.5 μm, but the present invention is not limited thereto.

[0057] Please refer to Figure 1 , in some embodiments, the display device 10 further includes a light-transmissive encapsulation layer 150 covering the second encapsulation layer 140 and the light-emitting element 120. In some embodiments, the light-transmissive encapsulation layer 150 may be a transparent adhesive layer. The light-emitting element 120 is located between the light-transmissive encapsulation layer 150 and the first encapsulation layer 130. The second encapsulation layer 140 is located between the light-transmissive encapsulation layer 150 and the first encapsulation layer 130. In some embodiments, the second part 134 of the first encapsulation layer 130 may protrude from the second encapsulation layer 140, and the light-transmissive encapsulation layer 150 may contact the second part 134 of the first encapsulation layer 130, but the present invention is not limited thereto. In some embodiments, the thickness T150 of the light-transmissive encapsulation layer 150 is, for example, about 30 μm, but the present invention is not limited thereto.

Claims

1. A display device, characterized in that: include: a driving circuit substrate; a light emitting element, disposed on the driving circuit substrate and electrically connected to the driving circuit substrate; A first packaging layer is disposed on the driving circuit substrate and has a plurality of reflective particles, wherein the first packaging layer includes: A first portion is disposed on the driving circuit substrate and extends outward from the light emitting element; as well as a second portion disposed on the first portion and covering a side wall of the light-emitting element, wherein a density of the plurality of reflective particles in the second portion is greater than a density of the plurality of reflective particles in the first portion; and A second packaging layer is disposed on the first packaging layer and can absorb light.

2. The display device according to claim 1, characterized in that The density of the plurality of reflective particles in the second portion is greater than 40%, and the density of the plurality of reflective particles in the first portion is less than 40%.

3. The display device according to claim 1, characterized in that A surface roughness of the first packaging layer is greater than a surface roughness of the second packaging layer.

4. The display device according to claim 1, characterized in that The second portion of the first packaging layer protrudes from the second packaging layer.

5. The display device according to claim 4, characterized in that Also includes: A light-transmissive packaging layer covers the second packaging layer and the light-emitting element and contacts the second portion of the first packaging layer.

6. The display device according to claim 1, characterized in that The height difference of the uneven rough surface of the first encapsulation layer falls within the range of ±2 μm.

7. The display device according to claim 1, characterized in that The height difference of the uneven rough surface of the second encapsulation layer falls within the range of ±0.5 μm.

8. The display device according to claim 1, characterized in that It further includes a light-transmitting packaging layer covering the second packaging layer and the light-emitting element.

9. The display device according to claim 8, characterized in that The second portion of the first packaging layer protrudes from the second packaging layer, and the light-transmissive packaging layer contacts the second portion of the first packaging layer.

10. The display device according to claim 1, wherein: The second portion of the first encapsulation layer is higher than the light-emitting layer of the light-emitting element.

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