TWI688811B - Flexible display device - Google Patents

Abstract

The present disclosure provides a flexible display device comprising: at least a pixel; a separator having at least a groove formed thereon, wherein the groove is adjacent to the pixel in a first direction and extends along a second direction different from the first direction; and a conducting layer positioned over the first pixel and the separator and extending into the groove.

Description

Flexible display device

The present invention relates generally to display devices; in particular, the present invention relates to flexible display devices.

In recent years, flexible display devices have become increasingly popular, and currently developed flexible display devices generally use active matrix organic light emitting diode (AMOLED) display panels to improve folding The possibility of obtaining better image quality at the same time.

According to the prior art, the bendability of the flexible display device can only reach a curvature of 2 mm at most, and can only achieve a single dimension of folding. In addition, after the flexible display device has been bent many times, the local top electrode may be deformed or even cracked, resulting in a broken circuit, thereby limiting the possibility of application of the electronic device.

Therefore, there is an urgent need for a flexible display device that can be folded in half arbitrarily without being easily cracked.

In order to solve the problems in the prior art, the inventor of the present invention has put forward an appropriate inventive concept, which is embodied by many different embodiments described below.

An embodiment of the present invention is a flexible display device including at least one light-emitting pixel; a spacer with at least one groove formed on the spacer, the groove being adjacent to the light-emitting pixel along a first direction And extend in a second direction that is different from the first direction; and a conductive layer is provided on the light-emitting pixel and the spacer, and extends into the groove.

In one embodiment, the groove has a side wall and a bottom surface, and the conductive layer extends from the light-emitting pixel to the side wall and the bottom surface.

In one embodiment, the flexible display device further includes a second conductive layer disposed on the bottom surface and electrically connected to the first conductive layer.

In one embodiment, the flexible display device further includes an electrode disposed on the other side of the light-emitting pixel opposite to the first conductive layer, and corresponding to the light-emitting pixel.

In one embodiment, the electrode and the second conductive layer are coplanar in the second direction.

In one embodiment, the flexible display device further includes a thin film transistor layer disposed on the other side of the electrode relative to the light-emitting pixel, wherein the groove extends into the thin film transistor layer, the second The conductive layer is coplanar with an electrode plate of a drain electrode, a source electrode or a capacitor in the thin film transistor layer.

In one embodiment, two spacers and a recessed portion are formed on the spacer, the recessed portion is between the two recesses, and the light-emitting pixel is located in the recessed portion.

In one embodiment, the depth-to-width ratio of each of the grooves is greater than the depth-to-width ratio of the recessed portion.

In one embodiment, the flexible display device includes two light-emitting pixels, wherein one of the grooves is between two light-emitting pixels in the first direction.

In one embodiment, the first conductive layer extends from one of the light-emitting pixels to the other light-emitting pixel, and covers two of the light-emitting pixels.

Referring to FIG. 1, FIG. 1 is a top view for showing a part of a flexible display device 10 according to the present invention. The part is a part of a light-emitting layer. For ease of explanation, the rest of the layers such as packaging and touch are temporarily shown in this figure. Omitted. The flexible display device 10 includes an array mainly composed of a plurality of light emitting pixels (pixels) 12a, 12b, 12c, and 12d, arranged in a regular or irregular manner. Among them, the sizes of the plurality of light-emitting pixels 12a, 12b, 12c, and 12d may be the same as or different from each other. And, these light-emitting pixels can be designed to emit the same or different spectrum of colors. The remaining unlabeled light-emitting pixels are a combination of light-emitting pixels 12a, 12b, 12c, 12d, etc. In this disclosure, the four pixels will be used as examples for illustration.

With continued reference to FIG. 1, the flexible display device 10 further includes a spacer 14. In some embodiments, the spacer 14 may be a photosensitive material, which may be coated on a substrate (not labeled) of the flexible display device 10 in a first direction D1 (eg, horizontal direction) by coating , And through exposure, development and other steps to produce a continuous grid-like structure, and a certain thickness in a second direction D2 (for example, a direction substantially perpendicular to the first direction) different from the first direction D1 , The grid structure is formed on the spacer 14 with a plurality of recesses (or meshes) recessed on the surface of the spacer 14. One of the purposes of the spacer 14 is to limit the scattered light generated by the plurality of light-emitting pixels 12a, 12b, 12c, and 12d in the first direction D1 in the light-emitting pixel array to be located in the corresponding meshes while being separated from each other So that a single light-emitting pixel and other surrounding light-emitting pixels do not interfere with each other. Therefore, in some embodiments, the spacer 14 is also referred to as a pixel define layer. At the same time, the spacer 14 can also be used to separate the light-emitting pixels from surrounding objects (such as electronic components).

In some embodiments, the spacer 14 may also be a dielectric material to provide electrical insulation of the light-emitting pixels adjacent to each other. In addition, the spacer 14 may also be a light absorbing material, which can absorb the incident light from the external environment to avoid the reflection of the incident light from interfering with the luminous efficiency of the light-emitting pixels, thereby enhancing the contrast.

Referring to FIG. 2, FIG. 2 is a cross-sectional view for showing the light-emitting pixel 12 b and a part of the spacer 14 taken along line AA′ of FIG. 1. In some embodiments, the light-emitting pixel 12b may include a plurality of organic material stacks, such as an electron injection layer (EIL), an electron tunneling layer (ETL), a light-emitting layer 26, and a tunneling layer (Hole Transport layer, HTL), hole injection layer (HIL) and other thin films stacked along the second direction D2. In some embodiments, the light-emitting pixel 12 b is the area covered by the light-emitting layer 26.

In some embodiments, the flexible display device 10 further includes a thin film transistor (TFT) layer 32, which is disposed under the light-emitting pixel 12b along the second direction D2, between the light-emitting pixel 12b and the substrate. The further description of the TFT layer 32 will be described as follows with reference to FIGS. 3 to 5.

At least one groove 20 is formed on the spacer 14. The groove 20 is similar to the aforementioned plurality of meshes, but it is not used to accommodate the light-emitting pixels, and its depth may be different from the aforementioned plurality of meshes. The groove 20 is adjacent to the light-emitting pixel 12b in the first direction D1. In some embodiments, the groove 20 is between the light-emitting pixel 12b and the light-emitting pixel 12c (as shown in FIG. 1).

In some embodiments, the groove 20 has a tapered cross-sectional shape. In some embodiments, when viewed from a top view, the groove 20 assumes a polygonal shape, or an oval shape, but is not limited thereto.

The spacer 14 of the flexible display device 10 may include other grooves, located between two light-emitting pixels, or adjacent to only one light-emitting pixel, or not adjacent to the light-emitting pixel. In this disclosure, the grooves taken along the lines AA' and BB' are taken as examples for explanation. The groove can be created in the spacer 14 by steps such as exposure, development or etching. In some embodiments, the plurality of grooves on the flexible display device 10 may have the same or different shapes and sizes from each other.

The groove 20 extends along the second direction D2, wherein one end of the groove 20 forms an opening on the surface of the spacer 14 and the other end extends to a layer (such as the TFT layer 32) below it, and exposes a portion of the upper surface of the layer . In some embodiments, the size of the inner diameter of the groove 20 tapers from the side adjacent to the surface of the spacer 14 toward the side adjacent to the underlying layer, for example, when viewed from the cross-sectional view as shown in FIG. 2 The narrower the width of 20 in the first direction D1 is to the lower layer. In addition, based on the depth in the second direction D2 and the width in the first direction D1, the groove 20 may have an aspect ratio, and the aspect ratio is between 3:1 and 60:1, for example 20:1.

In some embodiments, the groove 20 can be filled with material from subsequent processes, so no gaps as shown in FIG. 2 are seen. For example, the groove 20 may be filled with an organic material that can withstand tensile stress to protect the stack layer subsequently deposited in the groove 20 and to further prevent the flexible display device 10 from cracking due to bending.

With continued reference to FIG. 2, the flexible display device 10 further includes a first conductive layer 22 that can cover the light-emitting pixel array and the spacer 14 of FIG. 1. Therefore, the first conductive layer 22 can also be referred to as a common electrode. In some embodiments, the first conductive layer 22 may be a cathode and provide electrons to the light-emitting layer 26. The first conductive layer 22 may include metals such as magnesium (Mg), calcium (Ca), sodium (Na), potassium (K), aluminum (Al), silver (Ag) and other metals or alloys thereof, or other low work functions (work function) material, but not limited to this. The first conductive layer 22 may also include metal oxides, such as indium tin oxide (ITO), indium zinc oxide (IZO), and other transparent conductive materials, but is not limited thereto. The first conductive layer 22 may also include a stack composed of the above materials. The first conductive layer 22 can be deposited on the light-emitting pixel array and the spacer 14 by evaporation, DC magnetron sputtering or atomic layer deposition, etc., and penetrates into the groove 20.

The first conductive layer 22 covers the spacer 14 and further extends into the groove 20. When viewed from the cross-sectional view of FIG. 2, the groove 20 has side walls 20 a and 20 b and a bottom surface 20 c. In some embodiments, the first conductive layer 22 extends from the light-emitting pixel 12b to the sidewall 20a of the groove 20, or the sidewall 20b, or both. In some embodiments, the first conductive layer 22 covers the bottom surface 20c of the groove 20. In some embodiments, the first conductive layer 22 covers all surfaces of the groove 20. In some embodiments, a different layer is sandwiched between the first conductive layer 22 and the surface of the groove 20. In some embodiments, the first conductive layer 22 is in contact with at least one of the side wall 20a, the side wall 20b, the bottom surface 20c, and the light-emitting pixel 12b. In some embodiments, the first conductive layer 22 contacts the layer (eg, passivation layer) under the spacer 14 through the groove 20.

In some embodiments, the first conductive layer 22 contacts the light-emitting pixel 12b, and is connected to a voltage in the groove 20, which may also be referred to as a common voltage. In some embodiments, the common voltage is ground.

With continued reference to FIG. 2, in some embodiments, the flexible display device 10 further includes a second conductive layer 24 disposed on the bottom surface 20 c of the groove 20 and electrically connected to the first conductive layer 22. In some embodiments, the second conductive layer 24 has the same material as the first conductive layer 22.

In some embodiments, the flexible display device 10 further includes an electrode 30a disposed on the other side of the light-emitting pixel 12b relative to the first conductive layer 22, and corresponding to the light-emitting pixel 12b. The electrode 30a is located in the mesh below the light-emitting pixel 12b, so the electrode 30a may also be referred to as a pixel electrode. The light-emitting pixel 12b is interposed between the first conductive layer 22 and the electrode 30a. In some embodiments, the electrode 30a may be an anode, providing holes for the light emitting layer 26. In some embodiments, the electrode 30a may include metals such as vanadium (V), chromium (Cd), copper (Cu), or alloys thereof, or other high work function materials, but is not limited thereto. In some embodiments, the electrode 30a may also include a metal oxide, such as indium tin oxide (ITO), indium zinc oxide (IZO), and other transparent conductive materials, but is not limited thereto. In some embodiments, the electrode 30a contacts the light-emitting pixel 12b.

In some embodiments, the second conductive layer 24 may be coplanar with the electrode 30a, for example, located on the same surface or the same horizontal plane. In some embodiments, the second conductive layer 24 and the electrode 30a may be formed together in the same process step, for example, formed on the TFT layer 32 by using the same photomask in the same process step.

In some embodiments, the electrode 30a, the light-emitting pixel 12b and the first conductive layer 22 together form an organic light emitting diode (OLED).

The groove-shaped structural design of the present invention reserves space for bending, so the first conductive layer 22 in the groove 20 is less likely to break during the bending process, even if the first conductive layer 22 corresponding to the light-emitting pixel 12b breaks, The light-emitting pixel 12b can still form a path through the first conductive layer 22 and the second conductive layer 24 disposed in the groove 20, thereby avoiding the problem that a large-area light-emitting pixel array cannot emit light.

In some embodiments, the spacer 14 covers the area around the electrode 30a and exposes the central area of the electrode 30a, so the spacer 14 may be referred to as an edge cover or an edge insulator. In some embodiments, the light-emitting pixels 12b cover the central area of the electrode 30a to form the light-emitting pixel array as shown in FIG. In some embodiments, the light-emitting pixel 12b is in contact with the central area of the electrode 30a. In addition to separating the plurality of light-emitting pixels in the light-emitting pixel array one by one, the function of the spacer 14 further includes avoiding the short circuit between the electrode 30a and the first conductive layer 22, or avoiding the formation of pinhole defects due to the electrode 30a And affect the light-emitting performance of OLED.

3, FIG. 3 is a cross-sectional view for showing another embodiment of the groove 20. FIG. 3 has a similar structure to FIG. 2, and the same symbols represent similar elements, which will not be repeated here. As shown in FIG. 3, the TFT layer 32 is provided on the other side of the electrode 30a with respect to the light-emitting pixel 12b.

The TFT layer 32 includes a plurality of layers, for example, the lowest substrate layer 32a, a circuit layer provided on the substrate layer, and a passivation layer 32b covering the circuit layer. In some embodiments, the circuit layer includes a plurality of conductor layers at different horizontal planes. In some embodiments, the circuit layer includes a semiconductor, a gate electrode 33a, a drain electrode 33b, a source electrode 33c, and the like.

In some embodiments, the second conductive layer 24 is in the TFT layer 32. In some embodiments, the groove 20 extends into the TFT layer 32, and the second conductive layer 24 is coplanar with the drain electrode 33b or the source electrode 33c. In some embodiments, the second conductive layer 24, the source electrode 33c and the drain electrode 33b are formed together in the same process step.

In some embodiments, the first conductive layer 22 is connected to a ground voltage via the second conductive layer 24. For example, the first conductive layer 22 is electrically connected to the second conductive layer 24 through the groove 20, and the second conductive layer 24 is electrically connected to the ground voltage. In some embodiments, the circuit layer is electrically connected to the light-emitting pixel 12b via the electrode 30a. For example, as shown in FIG. 3, the drain electrode 33b is electrically connected to the electrode 30a, and the electrode 30a is electrically connected to the light-emitting pixel 12b.

In some embodiments, the second conductive layer 24 may be a conductor layer in the TFT layer 32. In some embodiments, the second conductive layer 24 is separated from other conductor layers in the TFT layer 32. For example, the second conductive layer 24 and the drain electrode 33b may be located on the surface of the insulating layer, and the two are not electrically connected.

Referring to FIG. 4, FIG. 4 is a cross-sectional view for showing another embodiment of the groove 20. FIG. 4 has a similar structure to FIG. 3, and the same symbols represent similar elements, which will not be repeated here. As shown in FIG. 4, the TFT layer 32 includes electrode plates 35a and 35b. In some embodiments, the electrode plates 35a and 35b serve as a capacitor upper and lower electrode plates.

In some embodiments, the second conductive layer 24 is in the TFT layer 32. In some embodiments, the groove 20 extends into the TFT layer 32, and the second conductive layer 24 is coplanar with the electrode plate 35a. In some embodiments, the second conductive layer 24 and the electrode plate 35a are formed together in the same process step.

Referring to FIG. 5, FIG. 5 is a cross-sectional view for showing another embodiment of the groove 20. FIG. 5 has a similar structure to FIG. 4, and the same symbols represent similar elements, which will not be repeated here.

In some embodiments, the second conductive layer 24 is in the TFT layer 32. In some embodiments, the groove 20 extends into the TFT layer 32, and the second conductive layer 24 is coplanar with the electrode plate 35b. In some embodiments, the second conductive layer 24 and the electrode plate 35b are formed together in the same process step.

Referring to FIG. 6, FIG. 6 is a cross-sectional view showing the light-emitting pixels 12a, 12b, 12c and part of the spacer 14 taken along the line BB' of FIG. FIG. 6 has a similar structure to FIG. 2, and the same symbols represent similar elements, which will not be repeated here. Please refer to FIG. 2 for a detailed description of the light-emitting pixels 12a, 12c and other similar elements.

In some embodiments, the spacer 14 has a plurality of grooves 20, 34, and the depth or aspect ratio of these grooves 20, 34 may be the same or may be different. The groove 34 is adjacent to the light-emitting pixel 12b in the first direction D1, and the groove 34 and the groove 20 are respectively located on both sides of the light-emitting pixel 12b. In some embodiments, the groove 34 exposes a portion of the upper surface of the layer below it.

In some embodiments, the groove 34 has a tapered cross-sectional shape. In some embodiments, when viewed from a top view, the groove 34 assumes a polygonal shape, or an oval shape, but is not limited thereto. In some embodiments, the groove 34 and the groove 20 may have the same or different shapes and sizes from each other. In some embodiments, as with the groove 20, the groove 34 can be filled with the material of the subsequent process, so the gap as shown in FIG. 6 will not be seen.

In some embodiments, a recess (ie, the aforementioned mesh) is formed between the recess 34 and the recess 20, and the light-emitting pixel 12b may be located in the recess. In the first direction D1, the groove 34 and the groove 20 are located on both sides of the recess. In some embodiments, the aspect ratio (d1/w1) of the groove 20 may be greater than the aspect ratio (d2/w2) of the recess, but is not limited thereto.

In some embodiments, the first conductive layer 22 extends into the groove 34. In some embodiments, the groove 34 has substantially the same cross-sectional shape as the groove 20, and also has side walls and a bottom surface. In some embodiments, the first conductive layer 22 covers the sidewall of the groove 34. In some embodiments, the first conductive layer 22 covers the bottom surface of the groove 34. In some embodiments, a different layer is further sandwiched between the first conductive layer 22 and the sidewall or bottom surface of the groove 34. In some embodiments, the first conductive layer 22 is in contact with at least the sidewall or bottom surface of the groove 34. The first conductive layer 22 is in contact with the layer below the spacer 14 through the groove 34. In some embodiments, the first conductive layer 22 is connected to a ground voltage within the groove 34.

6, in some embodiments, the flexible display device 10 further includes a second conductive layer 36 disposed on the bottom surface of the groove 34 and electrically connected to the first conductive layer 22. In some embodiments, the second conductive layer 36 may be coplanar with the electrode 30a. In some embodiments, the second conductive layer 36 may be formed together with the electrode 30a in the same process step.

In some embodiments, the second conductive layer 36 may be located in the TFT layer 32. In some embodiments, the second conductive layer 36 may be coplanar with one of the source electrode, the drain electrode, the electrode plate above the capacitor, or the electrode plate below the capacitor. Although FIG. 6 depicts that the second conductive layers 24, 36 are all coplanar with the electrode 30a, it is not limited thereto. In some embodiments, the second conductive layer 36 is located in the TFT layer 32 and is coplanar with any conductor layer in the TFT layer 32; the second conductive layer 24 is located on the TFT layer 32 and is coplanar with the electrode 30a.

The groove 20 is interposed between the light-emitting pixel 12b and the light-emitting pixel 12c in the first direction D1. The first conductive layer 22 extends from the light-emitting pixel 12b to the light-emitting pixel 12c, and covers the light-emitting pixel 12b and the light-emitting pixel 12c. In some embodiments, the first conductive layer 22 serves as a common electrode to make the light-emitting pixels 12b and the light-emitting pixels 12c have the same potential.

In some embodiments, the flexible display device 10 further includes an electrode 30b. The light-emitting pixel 12c is interposed between the first conductive layer 22 and the electrode 30b. In some embodiments, the electrode 30b is coplanar with the second conductive layer 24. In some embodiments, the electrode 30b serves as an anode to provide holes for the light-emitting pixels 12c. In some embodiments, the electrode 30b contacts the light-emitting pixel 12c. In some embodiments, the electrode 30b is electrically connected to the circuit layer in the TFT layer 32. In some embodiments, the electrode 30b, the light-emitting pixel 12c, and the first conductive layer 22 together form an OLED.

In some embodiments, the spacer 14 covers the surrounding area of the electrode 30b and exposes the central area of the electrode 30b. In some embodiments, the light-emitting pixels 12c cover the central area of the electrode 30b to form the light-emitting pixel array as shown in FIG. In some embodiments, the light-emitting pixel 12c is in contact with the central area of the electrode 30b.

Referring to FIG. 7, FIG. 7 is a perspective view illustrating a bent state of the flexible display device 10 according to an embodiment of the present invention. The flexible display device 10 has a bendable direction, wherein the bendable direction is the same as the extending direction D2 of the groove. When the flexible display device 10 is bent, the groove-shaped structure design reserves space for bending, so that even if the flexible display device 10 is bent multiple times, the first conductive layer 22 is not easily cracked, and The phenomenon of partial cathode disconnection.

This description and its abstract section merely describe one or more embodiments of the invention that the inventors intend, and not exhaustive of all embodiments. This specification and its abstract should not be used to limit the scope of patents applied by applicants.

The above uses blocks to describe different functions of different embodiments of the present invention. The boundary between the blocks is only for the convenience of description. As long as the specified functions and their relative relationships can be properly implemented, there is no need to rigidly abide by the boundaries defined in the above or drawings.

The description of specific embodiments in this specification can fully reveal the general nature of the present invention, so that a skilled person can make corresponding, appropriate, and non-existent responses to any embodiment for a specific application without departing from the general spirit of the present invention. Excessive modifications, these modifications still do not deviate from the scope of the present invention and its equivalent scope.

The scope of the patent applied for in the present invention is defined by the scope of the attached patent application and its equivalent scope, rather than being limited by the description, abstract and drawings.

10 flexible display device 12a pixel 12b pixel 12c pixel 12d pixel 20 recess 14 sidewall spacers 20a 20b 20c 26 side wall 22 of the first conductive layer of the light emitting layer 24 bottom surface of the second electrode conductive layer 30a 30b 32 a thin film electrode crystalline layer 32a of the substrate layer 32b a passivation layer gate electrode 33a 33b 33c drain electrode 34 source electrode groove 35a of the electrode plate 35b of the second conductive layer of the electrode plate 36 in the first direction D1 the second direction D2

FIG. 1 is a top view illustrating a part of a flexible display device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating a part taken along line AA′ of FIG. 1 according to an embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a part taken along line AA′ of FIG. 1 according to another embodiment of the present invention. FIG. 4 is a cross-sectional view illustrating a part taken along line AA′ of FIG. 1 according to another embodiment of the present invention. FIG. 5 is a cross-sectional view illustrating a part taken along line AA′ of FIG. 1 according to another embodiment of the present invention. FIG. 6 is a cross-sectional view illustrating a part taken along the line BB′ of FIG. 1 according to an embodiment of the present invention. FIG. 7 is a perspective view illustrating the bending state of the flexible display device according to an embodiment of the present invention. Note that each diagram is only for illustration, not for limiting the size, number, ratio or connection relationship.

20 recess 14 pixel 12b sidewall spacer 20a 20b 26 22 bottom surface of the light emitting layer side wall 20c of the first conductive layer 24, second conductive layer 30a 32 a first direction D1 crystal thin film electrode layer in the second direction D2

Claims (10)

A flexible display device includes: at least one light-emitting pixel; a spacer, two spacers and a recessed portion are formed on the spacer, the recessed portion is between the two recesses, the light-emitting pixel is located In the recessed portion, each of the grooves is adjacent to the light emitting pixel along a first direction and extends along a second direction different from the first direction; a first conductive layer is disposed on the light emitting pixel and the On the spacer and extending into the groove; and a second conductive layer disposed on the bottom surface and electrically connected to the first conductive layer; wherein each of the grooves has a side wall and a bottom surface, the The first conductive layer extends from the light-emitting pixel to the side wall and the bottom surface. The flexible display device of claim 1 further includes an electrode disposed on the other side of the light-emitting pixel opposite to the first conductive layer, and corresponding to the light-emitting pixel. The flexible display device of claim 2, wherein the electrode and the second conductive layer are coplanar in the second direction. The flexible display device of claim 1 further includes a thin film transistor layer disposed on the other side of the electrode opposite to the light-emitting pixel, wherein the groove extends into the thin film transistor layer and the second conductive The layer is coplanar with an electrode plate of a drain electrode, a source electrode or a capacitor in the thin film transistor layer. As in the flexible display device of claim 1, wherein the aspect ratio of each of the grooves is greater than the aspect ratio of the recessed portion. The flexible display device according to claim 1 includes two light-emitting pixels, one of which The groove is between the two light-emitting pixels in the first direction. The flexible display device of claim 6, wherein the first conductive layer extends from one of the light-emitting pixels to the other light-emitting pixel, and covers the two light-emitting pixels. The flexible display device of claim 2, wherein the electrode, the light-emitting pixel and the first conductive layer together form an organic light-emitting diode. The flexible display device of claim 1, wherein the first conductive layer is in contact with at least one of the side wall, the bottom surface, and the light-emitting pixel. The flexible display device of claim 1, wherein the first conductive layer is electrically connected to the second conductive layer through the groove.

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