OLED display panel

Abstract

The present application discloses an OLED display panel, wherein the OLED display panel includes: a planarization layer; a pixel definition layer provided on the planarization layer, and the pixel definition layer is provided with pixel openings; wherein, a part of the planarization layer located within the pixel openings includes at least a pair of edge portions and a middle portion, the edge portions are adjacent to the inner walls of the pixel openings, the middle portion is located between a pair of the edge portions, and the edge portions protrude upward relative to the middle portion. In the present application, the edge portions protrude upward relative to the middle portion. When using ink to print the organic light-emitting layer, the ink will flow from the edge portions to the middle portion under the action of gravity, avoiding the accumulation of ink at the edges of the pixel openings. In this way, it can form a counteraction with the "Coffee Ring" effect. Therefore, the thickness of the organic light-emitting layer can have better uniformity, thereby improving the problem of obvious decline in the efficiency of the organic light-emitting device.

Description

Technical Field

[0001] This application relates to the field of display technologies, and particularly to an OLED display panel. Background Art

[0002] Organic Light-Emitting Diode (OLED) devices have the characteristics of self-luminescence, wide viewing angle, high contrast ratio, fast response speed, light weight and thinness, and have become the main trend of display technologies. Compared with the production of OLED devices using a Fine Metal Mask (FMM) and vacuum evaporation, the inkjet printing technology has attracted much attention because of its precise alignment, no need for a high-precision metal mask, and its material utilization rate can reach 100%, and has become the mainstream trend for the production of large-size OLED devices in the future.

[0003] The inkjet-printed organic light-emitting layer forms the organic light-emitting layer by printing organic light-emitting ink onto specific positions through nozzles. After the ink is printed into the designated area within the pixel opening, even if the printed area within the pixel opening is flat, due to the influence of micro-hydrodynamics on the ink, the ink will form a solute accumulation at the edge of the pixel opening, thereby causing an increase in the film thickness at the edge of the pixel opening, that is, there will be a situation where the thickness of the organic light-emitting layer is large near the edge of the pixel opening and small at the non-edge part far from the pixel opening. This situation is often referred to as the "Coffee Ring" effect.

[0004] The light emission intensity of an organic light-emitting device is strongly related to the microcavity length of the pixel opening (i.e., the distance between the anode and cathode of the organic light-emitting device). That is, if the microcavity length is too large or too small, the efficiency of the organic light-emitting device will be significantly reduced. When the thickness of the organic light-emitting layer of an organic light-emitting device is uneven, it will cause the microcavity length of the pixel opening to be too large or too small. Therefore, the "Coffee Ring" effect will cause a significant reduction in the efficiency of the organic light-emitting device. Summary of the Invention

[0005] This application provides an OLED display panel to improve the problem of a significant reduction in the efficiency of an organic light-emitting device.

[0006] This application provides an OLED display panel, which includes:

[0007] A planarization layer;

[0008] A pixel definition layer, which is disposed on the planarization layer and has pixel openings;

[0009] Among them, the part of the flat layer located within the pixel opening includes at least a pair of edge portions and a middle portion. The edge portions are adjacent to the inner wall of the pixel opening, the middle portion is located between a pair of the edge portions, and the edge portions protrude upward relative to the middle portion.

[0010] Optionally, in some embodiments of the present application, the part of the flat layer located within the pixel opening includes a pair of edge portions, and the pair of edge portions are arranged along the length direction of the pixel opening.

[0011] Optionally, in some embodiments of the present application, the part of the flat layer located within the pixel opening includes two pairs of edge portions, and the two pairs of edge portions are arranged around the middle portion.

[0012] Optionally, in some embodiments of the present application, a connecting ramp is provided between the edge portion and the middle portion.

[0013] Optionally, in some embodiments of the present application, the total length of the edge portion and the connecting ramp in the width direction of the pixel opening is less than or equal to 5 micrometers.

[0014] Optionally, in some embodiments of the present application, the thickness of the edge portion is greater than the thickness of the middle portion.

[0015] Optionally, in some embodiments of the present application, the OLED display panel further includes:

[0016] A substrate;

[0017] A first metal layer, the first metal layer is provided on the substrate, the flat layer is provided on the first metal layer, and the first metal layer includes signal traces;

[0018] Among them, the first metal layer is provided with a first recess, and the orthographic projection of the middle portion on the substrate is located within the orthographic projection of the contour of the first recess on the substrate.

[0019] Optionally, in some embodiments of the present application, the OLED display panel further includes:

[0020] A second metal layer, the second metal layer is provided on the substrate, the flat layer is provided on the first metal layer and the second metal layer, and the second metal layer includes a gate;

[0021] Among them, the second metal layer is provided with a second recess, and the orthographic projection of the middle portion on the substrate is located within the orthographic projection of the contour of the second recess on the substrate.

[0022] Optionally, in some embodiments of the present application, the OLED display panel further includes:

[0023] Substrate;

[0024] A third metal layer is provided on the substrate, and a planarization layer is provided on the third metal layer. The third metal layer includes a source electrode and a drain electrode;

[0025] Wherein, the third metal layer is provided with a third recess, and the orthographic projection of the middle portion on the substrate is located within the orthographic projection of the contour of the third recess on the substrate.

[0026] Optionally, in some embodiments of the present application, the OLED display panel further includes:

[0027] A fourth metal layer is provided on the substrate, and the planarization layer is provided on the third metal layer and the fourth metal layer. The fourth metal layer includes a gate electrode;

[0028] Wherein, the fourth metal layer is provided with a fourth recess, and the orthographic projection of the middle portion on the substrate is located within the orthographic projection of the contour of the fourth recess on the substrate.

[0029] The present application provides an OLED display panel, wherein the OLED display panel includes: a planarization layer; a pixel definition layer provided on the planarization layer, and the pixel definition layer is provided with a pixel opening; wherein, the portion of the planarization layer located within the pixel opening includes at least a pair of edge portions and a middle portion, the edge portions are adjacent to the inner wall of the pixel opening, the middle portion is located between a pair of the edge portions, and the edge portions protrude upward relative to the middle portion. In the present application, the edge portions protrude upward relative to the middle portion. When using ink to print the organic light-emitting layer, the ink will flow from the edge portions to the middle portion under the action of gravity, avoiding ink accumulation at the edges of the pixel opening. In this way, it can form a counteraction with the "Coffee Ring" effect, so that the thickness of the organic light-emitting layer can have better uniformity, thereby improving the problem of obvious decline in the efficiency of the organic light-emitting device. Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0031] Figure 1 It is a first schematic structural diagram of the OLED display panel provided by the present application;

[0032] Figure 2 is Figure 1 A cross-sectional view taken along the A-A section in

[0033] Figure 3 is the second structural schematic diagram of the OLED display panel provided by the present application;

[0034] Figure 4 is the third structural schematic diagram of the OLED display panel provided by the present application;

[0035] Figure 5 is the fourth structural schematic diagram of the OLED display panel provided by the present application;

[0036] Figure 6 is the fifth structural schematic diagram of the OLED display panel provided by the present application;

[0037] Figure 7 is the sixth structural schematic diagram of the OLED display panel provided by the present application;

[0038] Figure 8 is the seventh structural schematic diagram of the OLED display panel 100 provided by the present application. Detailed implementation manners

[0039] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present application.

[0040] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present application, "a plurality" means two or more, unless otherwise specifically defined.

[0041] The present application provides an OLED display panel, which will be described in detail below. It should be noted that the description order of the following embodiments does not limit the preferred order of the embodiments of the present application.

[0042] Please refer to Figure 1 and Figure 2 ,Figure 1 This is the first schematic structural diagram of the OLED display panel 100 provided by the present application. Figure 2 It is Figure 1 a cross-sectional view of the A-A section in

[0043] The pixel definition layer 20 is disposed on the flat layer 10, and the pixel definition layer 20 is provided with a pixel opening 21.

[0044] Among them, the part of the flat layer 10 located within the pixel opening 21 includes at least a pair of edge portions 11 and a middle portion 12. The edge portions 11 are adjacent to the inner wall of the pixel opening 21, the middle portion 12 is located between a pair of the edge portions 11, and the edge portions 11 protrude upward relative to the middle portion 12.

[0045] That is to say, the edge portions 11 and the middle portion 12 of the present application are not on the same horizontal plane, and the edge portions 11 protrude upward relative to the middle portion 12. When using ink to print the organic light-emitting layer 50, the ink will flow from the edge portions 11 to the middle portion 12 under the action of gravity, avoiding the accumulation of ink at the edge of the pixel opening 21. In this way, it can form a counteraction with the "Coffee Ring" effect, so that the thickness of the organic light-emitting layer 50 can have better uniformity, thereby improving the problem of obvious decline in the efficiency of the organic light-emitting device.

[0046] In some embodiments, the upper surface of the pixel opening 21 is a horizontal plane. At this time, the shortest distance in the thickness direction between the upper surface of the edge portion 11 and the upper edge of the pixel opening 21 is less than the shortest distance in the thickness direction between the upper surface of the middle portion 12 and the upper edge of the pixel opening 21.

[0047] Furthermore, the part of the flat layer 10 located within the pixel opening 21 includes a pair of edge portions 11, and the pair of edge portions 11 are arranged along the length direction of the pixel opening 21.

[0048] In this embodiment, since only a pair of edge portions 11 are provided, both ends of the middle portion 12 will be adjacent to the inside of the pixel opening 21, and the pair of edge portions 11 are arranged along the length direction of the pixel opening 21. Therefore, the ink can flow from the edge portions 11 to the middle portion 12 to the greatest extent.

[0049] Furthermore, a connecting slope 13 is provided between the edge portion 11 and the middle portion 12. By providing the connecting slope 13, the ink can flow from the edge portion 11 to the middle portion 12 more smoothly, and it is not easy to form a situation of flow dead ends.

[0050] In some embodiments, the total length W of the edge portion 11 and the connection ramp 13 in the width direction of the pixel opening 21 is less than or equal to 5 micrometers. Due to the limited space of the metal traces and metal layers in the conventional pixel design, the total width of the edge portion 11 and the connection ramp 13 needs to be controlled. Considering the coffee ring effect range at the edge of the pixel opening 21 and the limit line width of the metal layer, generally, the total width of the edge portion 11 and the connection ramp 13 is required to be less than or equal to 5 micrometers.

[0051] Specifically, in some embodiments, the thickness of the edge portion 11 is greater than the thickness of the middle portion 12. That is, in this embodiment, by setting the thickness of the edge portion 11 to be greater than the thickness of the middle portion 12, the edge portion 11 protrudes upward relative to the middle portion 12.

[0052] Please refer to Figure 3 , Figure 3 which is the second schematic structural diagram of the OLED display panel 100 provided by the present application. The difference between this embodiment and the Figure 1 OLED display panel 100 provided is that the OLED display panel 100 further includes:

[0053] a substrate 30, and the planar layer 10 is disposed on the substrate 30;

[0054] an anode 40, the anode 40 is disposed on the planar layer 10, the pixel definition layer 20 is disposed on the anode 40, and the anode 40 is located within the pixel opening 21;

[0055] an organic light-emitting layer 50, the organic light-emitting layer 50 is disposed on the anode 40 and is located within the pixel opening 21.

[0056] Please refer to Figure 4 , Figure 4 which is the third schematic structural diagram of the OLED display panel 100 provided by the present application. The difference between this embodiment and the Figure 1 OLED display panel 100 provided is that the part of the planar layer 10 located within the pixel opening 21 includes two pairs of edge portions 11, and the two pairs of edge portions 11 are arranged around the middle portion 12. The shape of the pixel opening 21 can be square, oval, or of course other shapes. One pair of edge portions 11 is arranged along the length direction of the pixel opening 21, and the other pair of edge portions 11 is arranged along the width direction of the pixel opening 21. The two pairs of edge portions 11 are connected end to end to form an annular structure, thereby surrounding the middle portion 12.

[0057] At this time, the edge portion 11 covers all the edges of the pixel opening 21, so that the ink at all the edges of the pixel opening 21 will flow from the edge portion 11 to the middle portion 12 under the action of gravity, avoiding the accumulation of ink at the edges of the pixel opening 21, and maximizing the thickness uniformity of the organic light-emitting layer 50.

[0058] Please refer to Figure 5 , Figure 5 which is the fourth structural schematic diagram of the OLED display panel 100 provided by this application. The difference between this embodiment and the Figure 2 OLED display panel 100 provided is that the OLED display panel 100 further includes:

[0059] a substrate 30;

[0060] a first metal layer 60, the first metal layer 60 is provided on the substrate 30, the flat layer 10 is provided on the first metal layer 60, and the first metal layer 60 includes signal traces; wherein the signal traces include data signal lines, common electrode lines, etc.;

[0061] Wherein, the first metal layer 60 is provided with a first recess 61, and the orthographic projection of the middle portion 12 on the substrate 30 is located within the orthographic projection of the contour of the first recess 61 on the substrate 30.

[0062] In this application, by providing a first recess 61 on the first metal layer 60 and making the orthographic projection of the middle portion 12 on the substrate 30 located within the orthographic projection of the contour of the first recess 61 on the substrate 30, since a step is formed between the position of the first metal layer 60 where there is no first recess 61 and the position of the first recess 61, and the middle portion 12 is formed at the position corresponding to the first recess 61, the edge portion 11 can be made to protrude upward relative to the middle portion 12 by using the step on the first metal layer 60 without increasing the thickness of the flat layer 10, thereby reducing the material cost.

[0063] Furthermore, the orthographic projection of the edge portion 11 on the substrate 30 is staggered from the orthographic projection of the contour of the first recess 61 on the substrate 30. This can avoid the need to increase the thickness of the edge portion 11 to make the edge portion 11 protrude upward relative to the middle portion 12.

[0064] Furthermore, the first recess 61 can be a groove or a through hole. When the first recess 61 is a through hole, this can make the step on the first metal layer 60 have the largest height difference, thereby maximizing the protrusion of the edge portion 11 relative to the middle portion 12.

[0065] Please refer to Figure 6 ,Figure 6 This is a fifth structural diagram of the OLED display panel 100 provided in this application. Figure 5 The OLED display panel 100 provided is different in that the OLED display panel 100 further includes:

[0066] A second metal layer 70, wherein the second metal layer 70 is disposed on the substrate 30, the planar layer 10 is disposed on the first metal layer 60 and the second metal layer 70, and the second metal layer 70 includes a gate;

[0067] The second metal layer 70 is provided with a second recessed portion 71 , and the orthographic projection of the middle portion 12 on the substrate 30 is located within the orthographic projection of the second recessed portion 71 on the substrate 30 .

[0068] In addition, a first insulating layer 80 is provided between the first metal layer 60 and the second metal layer 70. Specifically, the first metal layer 60 is provided on the substrate 30, the first insulating layer 80 is provided on the first metal layer 60, the second metal layer 70 is provided on the first insulating layer 80, and the planar layer 10 is provided on the second metal layer 70.

[0069] In the present application, a second recessed portion 71 is provided on the second metal layer 70, and the orthographic projection of the middle portion 12 on the substrate 30 is located within the orthographic projection of the second recessed portion 71. Since the second metal layer 70 forms a step between the position other than the second recessed portion 71 and the position of the second recessed portion 71, the middle portion 12 is formed at a position corresponding to the second recessed portion 71. In other words, by providing recessed portions on both the first metal layer 60 and the second metal layer 70, the height difference of the step can be increased, thereby further improving the height difference between the edge portion 11 and the middle portion 12, thereby improving the thickness uniformity of the organic light-emitting layer 50.

[0070] Moreover, in the existing array substrate 30, the thickness of the metal layer including the gate is usually relatively thin. Therefore, the present application provides recessed portions in both the first metal layer 60 and the second metal layer 70, which can fully utilize the existing metal layers to set the recessed portions while also preventing the depth of the recessed portions from being too deep.

[0071] Furthermore, the orthographic projection of the edge portion 11 on the substrate 30 is staggered with the orthographic projection of the outline of the second recessed portion 71 on the substrate 30. This avoids the need to increase the thickness of the edge portion 11 in order to make the edge portion 11 protrude upward relative to the middle portion 12.

[0072] Furthermore, the second recessed portion 71 may be a through hole or a groove. When the second recessed portion 71 is a through hole, the step on the second metal layer 70 may have a maximum height difference, thereby maximizing the upward protrusion of the edge portion 11 relative to the middle portion 12.

[0073] See also Figure 7 , Figure 7 This is a sixth structural diagram of the OLED display panel 100 provided in this application. Figure 2 The OLED display panel 100 provided is different in that the OLED display panel 100 further includes:

[0074] substrate 30;

[0075] A third metal layer 90, wherein the third metal layer 90 is provided on the substrate 30, and the planar layer 10 is provided on the first metal layer 60, and the third metal layer 90 includes a source electrode and a drain electrode;

[0076] The third metal layer 90 is provided with a third recessed portion 91 , and the orthographic projection of the middle portion 12 on the substrate 30 is located within the orthographic projection of the third recessed portion 91 on the substrate 30 .

[0077] In the present application, a third recessed portion 91 is provided on the third metal layer 90, and the orthographic projection of the middle portion 12 on the substrate 30 is located within the orthographic projection of the third recessed portion 91. Since the third metal layer 90 forms a step between the position of the non-third recessed portion 91 and the position of the third recessed portion 91, and the middle portion 12 is formed at the position corresponding to the third recessed portion 91, the step on the third metal layer 90 can be used to make the edge portion 11 protrude upward relative to the middle portion 12 without increasing the thickness of the flat layer 10, thereby reducing material costs.

[0078] Furthermore, the orthographic projection of the edge portion 11 on the substrate 30 is staggered with the orthographic projection of the outline of the third recessed portion 91 on the substrate 30. This avoids the need to increase the thickness of the edge portion 11 in order to make the edge portion 11 protrude upward relative to the middle portion 12.

[0079] Furthermore, the third recessed portion 91 may be a groove or a through hole. When the third recessed portion 91 is a through hole, the step on the third metal layer 90 can have a maximum height difference, thereby maximizing the upward protrusion of the edge portion 11 relative to the middle portion 12.

[0080] See also Figure 8 , Figure 8This is the seventh structural diagram of the OLED display panel 100 provided in this application. Figure 7 The OLED display panel 100 provided is different in that the OLED display panel 100 further includes:

[0081] a fourth metal layer 110 , wherein the fourth metal layer 110 is disposed on the substrate 30 , the planar layer 10 is disposed on the third metal layer 90 and the fourth metal layer 110 , and the fourth metal layer 110 includes a gate;

[0082] The fourth metal layer 110 is provided with a fourth recessed portion 111 , and the orthographic projection of the middle portion 12 on the substrate 30 is located within the orthographic projection of the outline of the fourth recessed portion 111 on the substrate 30 .

[0083] In addition, a second insulating layer 120 is provided between the third metal layer 90 and the fourth metal layer 110. Specifically, the fourth metal layer 110 is provided on the substrate 30, the second insulating layer 120 is provided on the fourth metal layer 110, the third metal layer 90 is provided on the second insulating layer 120, and the planarizing layer 10 is provided on the third metal layer 90.

[0084] In the present application, a fourth recessed portion 111 is provided on the fourth metal layer 110, and the orthographic projection of the middle portion 12 on the substrate 30 is located within the orthographic projection of the fourth recessed portion 111. Since the fourth metal layer 110 forms a step between the position other than the fourth recessed portion 111 and the position of the fourth recessed portion 111, the middle portion 12 is formed at a position corresponding to the fourth recessed portion 111. In other words, by providing recessed portions on both the third metal layer 90 and the fourth metal layer 110, the height difference of the step can be increased, thereby further increasing the height difference between the edge portion 11 and the middle portion 12, thereby improving the thickness uniformity of the organic light-emitting layer 50.

[0085] Moreover, in the existing array substrate 30, the thickness of the metal layer including the gate is usually thin. Therefore, the present application provides recessed portions in both the third metal layer 90 and the fourth metal layer 110, which can fully utilize the existing metal layers to set the recessed portions while also preventing the depth of the recessed portions from being too deep.

[0086] Furthermore, the orthographic projection of the edge portion 11 on the substrate 30 is staggered with the orthographic projection of the outline of the fourth recessed portion 111 on the substrate 30. This avoids the need to increase the thickness of the edge portion 11 in order to make the edge portion 11 protrude upward relative to the middle portion 12.

[0087] Further, the fourth recess 111 may be a through hole or a groove. When the fourth recess 111 is a through hole, the step on the fourth metal layer 110 can have the maximum height difference, so that the edge portion 11 protrudes upward relative to the middle portion 12 to the greatest extent.

[0088] The above has introduced in detail a display device provided by an embodiment of the present application. Specific examples are used herein to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. An OLED display panel, characterized in that, include: flat layer; a pixel definition layer, the pixel definition layer being disposed on the planar layer and having a pixel opening; substrate; a metal layer, the metal layer being disposed on the substrate, and the flat layer being disposed on the metal layer; The portion of the planar layer located within the pixel opening includes at least one pair of edge portions and a middle portion, the edge portions are adjacent to the inner wall of the pixel opening, the middle portion is located between the pair of edge portions, and the edge portions protrude upward relative to the middle portion; A connecting slope is provided between the edge portion and the middle portion; The metal layer is provided with a recessed portion, and the orthographic projection of the middle portion on the substrate is located within the orthographic projection of the recessed portion.

2. The OLED display panel according to claim 1, wherein, The portion of the planar layer located within the pixel opening includes a pair of edge portions, and the pair of edge portions are arranged along a length direction of the pixel opening.

3. The OLED display panel according to claim 1, wherein The portion of the planar layer located within the pixel opening includes two pairs of edge portions, and the two pairs of edge portions are arranged around the middle portion.

4. The OLED display panel according to claim 1, characterized in that, The total length of the edge portion and the connecting slope in the direction of the pixel opening width is less than or equal to 5 micrometers.

5. The OLED display panel according to claim 1, wherein The thickness of the edge portion is greater than the thickness of the middle portion.

6. The OLED display panel according to claim 1, wherein The metal layer comprises: a first metal layer, wherein the first metal layer is disposed on the substrate, the planar layer is disposed on the first metal layer, and the first metal layer includes a signal trace; The first metal layer is provided with a first recessed portion, and the orthographic projection of the middle portion on the substrate is located within the orthographic projection of the first recessed portion.

7. The OLED display panel according to claim 6, wherein, The OLED display panel further includes: a second metal layer, the second metal layer being disposed on the substrate, the planar layer being disposed on the first metal layer and the second metal layer, and the second metal layer comprising a gate; The second metal layer is provided with a second recessed portion, and the orthographic projection of the middle portion on the substrate is located within the orthographic projection of the second recessed portion.

8. The OLED display panel according to claim 1, characterized in that, The metal layer comprises: a third metal layer, the third metal layer being provided on the substrate, the planar layer being provided on the third metal layer, and the third metal layer comprising a source electrode and a drain electrode; The third metal layer is provided with a third recessed portion, and the orthographic projection of the middle portion on the substrate is located within the orthographic projection of the outline of the third recessed portion on the substrate.

9. The OLED display panel according to claim 8, wherein, The OLED display panel further includes: a fourth metal layer, the fourth metal layer being disposed on the substrate, the planar layer being disposed on the third metal layer and the fourth metal layer, and the fourth metal layer including a gate; The fourth metal layer is provided with a fourth recessed portion, and the orthographic projection of the middle portion on the substrate is located within the orthographic projection of the outline of the fourth recessed portion on the substrate.

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