CN111653685A

CN111653685A - Display back plate, display panel and display device

Info

Publication number: CN111653685A
Application number: CN202010558401.4A
Authority: CN
Inventors: 贾文斌; 袁粲
Original assignee: BOE Technology Group Co Ltd; Hefei BOE Zhuoyin Technology Co Ltd
Current assignee: BOE Technology Group Co Ltd; Hefei BOE Zhuoyin Technology Co Ltd
Priority date: 2020-06-18
Filing date: 2020-06-18
Publication date: 2020-09-11

Abstract

The invention provides a display back plate, a display panel and a display device. The display backplane includes: a substrate; a pixel defining layer disposed at one side of the substrate and having a plurality of first openings and a plurality of second openings; an anode layer disposed in the first opening; an auxiliary cathode disposed in the second opening; the light-emitting layer covers the pixel defining layer and the anode and is provided with a plurality of laser openings, and the orthographic projections of the laser openings on the substrate are overlapped with the orthographic projections of the auxiliary cathode on the substrate; the distance between two adjacent laser holes along the second direction is gradually reduced along the first direction, and the second direction and the first direction are arranged in a crossed mode. According to the display back plate provided by the invention, the plurality of laser holes for connecting the auxiliary cathode and the cathode on the light emitting layer are gradually increased in longitudinal density, so that the punching time of laser punching can be reduced, the yield can be improved, and the brightness uniformity and the display quality of the display back plate can be improved.

Description

Display back plate, display panel and display device

Technical Field

The invention relates to the technical field of display, in particular to a display back plate, a display panel and a display device.

Background

Existing Organic Light Emitting Diode (OLED) devices generally consist of an anode layer, a light emitting layer and a cathode layer, and are classified into bottom emission and top emission according to the difference of light emitting surfaces, wherein the top emission device has a larger aperture ratio, and thus has been a research focus in recent years. However, the transparent cathode with the thickness of 1-12 nm has a large sheet resistance, which leads to a serious increase in voltage Drop (IR Drop), so that the voltage Drop at a position farther from a power supply point is more obvious, and the OLED device has an obvious uneven light emission phenomenon.

At present, most of schemes for forming an auxiliary cathode of a White Organic Light Emitting Diode (WOLED) by evaporation adopt a laser drilling mode to remove a light emitting layer of an auxiliary cathode contact hole, and then connect a cathode and the auxiliary cathode in parallel through a laser hole, so that IR Drop can be reduced. However, in the design requiring more than 500 ten thousand laser drilling, the drilling efficiency is still relatively low, so the drilling Time (tacttime) required for drilling is relatively long, and referring to fig. 8, even if the laser drilling is performed in a Face down (Face down) manner, dust pollution still occurs and the yield is lowered, so how to ensure high drilling efficiency and high yield in the pressure drop difference (Spec) at the same Time is important.

Disclosure of Invention

The present invention has been completed based on the following findings of the inventors:

in the research process, the inventor designs a structural design of a display back plate, a pixel defining layer, an anode layer, an auxiliary cathode and a light emitting layer are formed on a substrate, and laser drilling is carried out on a specific position on the light emitting layer, so that the transverse density of formed laser drilling holes can be gradually increased, the longitudinal density of the laser drilling holes can be gradually increased, the drilling time of the laser drilling holes is shortened, the yield is improved, and meanwhile, the brightness uniformity and the display quality of a WOLED top emission panel are met.

In a first aspect of the invention, a display backplane is presented.

According to an embodiment of the invention, the display backplane comprises: a substrate; a pixel defining layer disposed at one side of the substrate and having a plurality of first openings and a plurality of second openings; an anode layer disposed in the first opening; an auxiliary cathode disposed in the second opening; a light emitting layer covering the pixel defining layer and the anode layer and having a plurality of laser openings whose orthographic projections on the substrate are partially overlapped with the orthographic projections of the auxiliary cathodes on the substrate; the distance between two adjacent laser holes along a second direction is gradually reduced along a first direction, and the second direction and the first direction are arranged in a crossed mode.

According to the display back plate provided by the embodiment of the invention, the plurality of laser holes for connecting the auxiliary cathode and the cathode on the light emitting layer are gradually increased in longitudinal density, so that the punching time of laser punching can be reduced, the yield can be improved, and the brightness uniformity and the display quality of the display back plate can be improved.

In addition, the display back plate according to the above embodiment of the present invention may further have the following additional technical features:

according to the embodiment of the invention, the distance between two adjacent laser holes along the first direction is gradually reduced along the second direction.

According to the embodiment of the invention, the areas of the laser openings in the first direction are the same.

According to the embodiment of the present invention, the areas of the plurality of laser openings in the second direction are the same.

According to an embodiment of the present invention, an area of the laser opening is gradually increased in the first direction.

According to an embodiment of the present invention, the display backplane further comprises: a cathode layer covering the light emitting layer, and the cathode layer is in contact with the auxiliary cathode through the laser opening.

According to an embodiment of the present invention, the display backplane further comprises: a signal terminal electrically connected to the cathode layer and disposed at an end of the substrate opposite to the first direction from the plurality of laser openings.

According to an embodiment of the invention, the anode layer is arranged in a layer with at least part of the auxiliary cathode.

In a second aspect of the invention, a display panel is presented.

According to an embodiment of the invention, the display panel comprises the display back panel.

According to the display panel provided by the embodiment of the invention, the manufacturing period of the display back plate is shorter, the yield is higher, and the brightness uniformity of the display back plate is better, so that the display image quality of the display panel is better. It will be understood by those skilled in the art that the features and advantages described above for the display backplane are still applicable to the display panel and will not be described herein again.

In a third aspect of the invention, a display device is presented.

According to an embodiment of the present invention, the display device includes the display panel described above.

According to the display device provided by the embodiment of the invention, the display quality of the display panel is better, and the manufacturing yield is higher, so that the market competitiveness of the display device is higher. It will be understood by those skilled in the art that the features and advantages described above for the display backplane and the display panel are still applicable to the display device and will not be described herein again.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The foregoing aspects of the invention are explained in the description of the embodiments with reference to the following drawings, in which:

FIG. 1 is a schematic top view of a display backplane according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a longitudinal cross-sectional structure of a display back plate at different positions along a second direction according to an embodiment of the present invention;

FIG. 3 is a schematic top view of a conventional display panel;

FIG. 4 is a schematic top view of a display backplane according to another embodiment of the present invention;

FIG. 5 is a schematic cross-sectional view of another embodiment of the present invention showing a back plate in a first direction;

FIG. 6 is a schematic top view of a display backplane according to another embodiment of the present invention;

FIG. 7 is a diagram illustrating the gradual decrease of ELVDD with the increase of the number of rows;

FIG. 8 is a schematic diagram of the Face down laser printing mode.

Reference numerals

100 substrate

200 pixel defining layer

201 first opening

202 second opening

300 anode layer

400 auxiliary cathode

500 light emitting layer

501 laser drilling

600 cathode layer

700 signal terminal

Detailed Description

The following examples of the present invention are described in detail, and it will be understood by those skilled in the art that the following examples are intended to illustrate the present invention, but should not be construed as limiting the present invention. Unless otherwise indicated, specific techniques or conditions are not explicitly described in the following examples, and those skilled in the art may follow techniques or conditions commonly employed in the art or in accordance with the product specifications.

In one aspect of the invention, a display backplane is presented. It should be noted that only 3 rows of laser openings are shown in fig. 1, 3, 4 and 6 as an illustration, and in actual practice, there may be hundreds of rows and columns of laser openings in the light emitting layer.

According to an embodiment of the present invention, referring to fig. 2, the display backplane comprises a substrate 100, a pixel defining layer 200, an anode layer 300, an auxiliary cathode 400, a light emitting layer 500; wherein the pixel defining layer 200 is disposed on one side of the substrate 100, and the pixel defining layer 200 has a plurality of first electrodesThe first openings 201 and the second openings 202, specifically, the first openings 201 and the second openings 202 may be arranged in an array and arranged at intervals along a first direction; the anode layer 300 is disposed in the first opening 201; the auxiliary cathode 400 is disposed in the second opening 202; the light emitting layer 500 covers the pixel defining layer 200 and the anode layer 300, and the light emitting layer 500 has a plurality of laser openings 501, for example, the radius of the laser openings 501 may be 5 ± 1 micron, and the orthographic projection of the plurality of laser openings 501 on the substrate 100 is partially overlapped with the orthographic projection of the auxiliary cathode 400 on the substrate 100; wherein, referring to fig. 1, the pitch of two laser openings 501 adjacent in the second direction gradually decreases in the first direction, e.g., d in fig. 1₁>d₂>d₃>…, wherein the second direction is crossed with the first direction, and the second direction and the first direction may be perpendicular to each other. It should be noted that the pitch of two adjacent laser holes 501 specifically refers to the distance between the center lines of two laser holes 501.

The inventor of the present invention found that In the conventional display backplane design, referring to fig. 3, the density of the laser openings 501 contacting the auxiliary cathode 400 is consistent, that is, the data line resistance Rs is affected by the distance L (Rs ═ R × W/L, where R is the square resistance of the data line, W is the width of the data line, and L is the length of the data line) between the End (Source In) close to the signal terminal 700 and the End (Source End) far from the signal terminal 700 along the first direction, and the IR Drop occurs_In＜IR Drop_EndThat is, the farther the distance from the signal terminal 700, the larger the voltage drop, resulting in a larger difference in the brightness of the display backplane along the first direction, thereby causing a problem of uniform contact hole density but non-uniform display brightness.

Therefore, referring to fig. 2, the inventors adjust the longitudinal density of the plurality of laser openings 501 on the light emitting layer 500 to be gradually increased, specifically, for example, the pitch between two adjacent laser openings 501 in the first row may be the total width of 8 sub-pixel units, and the pitch between two adjacent laser openings 501 in the last row may be the width of 1 sub-pixel unit. So, can reduce the IR Drop difference between two lines effectively to the luminance homogeneity and the display quality that make the display backplate are all better, and, can also reduce the total number of laser trompil effectively, thereby reduce laser beam drilling's punching time and improve the yields.

In some embodiments of the present invention, referring to fig. 1, the spacing D of two laser openings 501 adjacent in the first direction may be equal in the second direction, such that only the longitudinal density of the plurality of laser openings 501 needs to be changed. In other embodiments of the present invention, referring to fig. 4, the spacing between two adjacent laser holes 501 along the first direction may also be gradually decreased along the second direction, for example, D1> D2> … in fig. 4, and further, the first direction may be a transverse direction and the second direction may be a longitudinal direction, so that the longitudinal density and the transverse density of the plurality of laser holes 501 are simultaneously changed, thereby improving the brightness uniformity of the display backplane more significantly.

In some embodiments of the present invention, referring to fig. 1 or fig. 4, the areas of the plurality of laser openings 501 in the first direction may be the same, thereby facilitating the simplification of the process design in the laser drilling process. In some embodiments of the present invention, referring to fig. 1 or fig. 4, the areas of the plurality of laser openings 501 in the second direction may be the same, thereby also facilitating the simplification of the process design in the laser drilling process. In other embodiments of the present invention, referring to fig. 6, the areas of the plurality of laser openings 501 in the first direction may also be gradually increased, so that the voltage Drop may be further reduced by enlarging the contact area between the auxiliary cathode 400 and the cathode, thereby further reducing the IR Drop difference in the longitudinal direction.

According to an embodiment of the present invention, referring to fig. 5, the display backplane may further include a cathode layer 600, the cathode layer 600 covers the light emitting layer 500, and the cathode layer 600 contacts the auxiliary cathode 400 through the laser openings 501, such that the auxiliary cathode 400 and the cathode layer 600 may be connected in parallel through the laser openings 501, thereby simultaneously achieving high transparency and low impedance of the cathode layer 600, and further enabling better brightness uniformity of the display backplane.

According to an embodiment of the present invention, referring to fig. 4, the backplate may further include a signal terminal 700, and the signal terminal 700 is electrically connected to the cathode layer 600, and the signal terminal 700 is disposed at one end of the substrate 100 along the first direction opposite to the first direction from the plurality of laser openings 501. In this way, the voltage Drop difference (IR Drop Spec) between the End (Source End) far away from the signal terminal 700 and the End (Source in) near the signal terminal 700 is kept within 4.8V, so that the brightness uniformity and the display quality of the display backplane are better.

It should be noted that the above embodiments of the transverse and longitudinal auxiliary cathode arrangement density and the auxiliary cathode contact area may be used individually or alternatively, and it is preferable to adopt a scheme in which the transverse auxiliary cathode arrangement density is gradually increased.

In some embodiments of the invention, the anode layer 300 and at least part of the auxiliary cathode 400 may be arranged in the same layer, i.e. at least one sublayer in the auxiliary cathode 400 is made of the same material as the anode layer 300. In this way, at least one sub-layer of the auxiliary cathode 400 is formed at the same time as the anode layer 300 through one patterning process, so that the display backplane has fewer manufacturing steps and lower manufacturing cost.

TABLE 1.3 comparison of Voltage Drop (Vss IR Drop, in V) for sets of simulation tests

Line number	Mode 1	Mode 2	Mode 3
				0	0	0	0
1000	10.97	0.93	1.3
				2000	17.56	1.5	2.81
3000	19.76	1.68	2.98

Specifically, the inventors also performed 3 sets of simulation experiments, and the specific results thereof are shown in table 1. Wherein the 1 st group (Mode 1) does not perforate the light emitting layer at all, the 2 nd group (Mode 2) does laser perforation for each line on the light emitting layer the same time, and the 3 rd group (Mode 3) does not perforate the light emitting layer with laser at 0-1000 lines, perforates the light emitting layer with laser at every 1000-2000 lines, perforates the light emitting layer with laser at every 2000-3000 lines. In addition, the anode layers in the display back plate structures of the 3 groups all adopt magnesium and silver materials with the molar ratio of 2:8, the current of the anode layer is 150A, and the sheet resistance of the auxiliary electrode is 0.03 omega/sq; and the test conditions were that the total voltage (elvdd) was 24V, the efficiency (Cd) of the red subpixel (R, CIE (x, y) ═ 0.679,0.321)) was 24A, the efficiency (Cd) of the green subpixel (G, CIE (x, y) ═ 0.182,0.732)) was 60A, and the efficiency (Cd) of the blue subpixel (B, CIE (x, y) ═ 00.134,0.055)) was 60A, and the white light ratios of the red subpixel, the green subpixel, and the blue subpixel were 0.28, 0.29, and W255, respectively.

As can be seen from table 1, the voltage drop of the design without the auxiliary electrode in group 1 connected in parallel with the cathode through the laser opening cannot satisfy the requirement of not more than 4.8V; the auxiliary electrodes in each row in the group 2 are connected in parallel with the cathode through the laser openings, the voltage drop difference of the design is minimum, however, the laser drilling time is too long, and the yield is low; and the laser hole density in the row of the group 3 which is farther away from the signal end is higher, the voltage drop difference of the design is below 3V, and the number of contact holes is reduced by at least half, so that the laser punching time can be obviously reduced, and the yield can be improved.

The mechanism of the IR Drop affecting uniformity is further explained: ELVDD + VDS + ELVSS, which is gradually increased as the number of rows increases, an effective ELVDD drop (refer to fig. 7) causes VDS to drop, and an output curve of a Thin Film Transistor (TFT) is not flat in a saturation region, thereby causing a difference in IDS to cause a difference in luminance. Moreover, the effective compensation space of the current external compensation method is about 4.8V, so that the IR Drop is required to be ensured not to exceed 4.8V during device design.

In summary, according to the embodiments of the present invention, the present invention provides a display backplane, wherein the plurality of laser holes on the light emitting layer for connecting the auxiliary cathode and the cathode are gradually increased in longitudinal density, so that the laser hole punching time can be reduced, the yield can be improved, and the brightness uniformity and the display quality of the display backplane can be improved.

In another aspect of the present invention, a display panel is provided. According to an embodiment of the invention, the display panel comprises the display back panel. It should be noted that the display panel includes necessary components and structures besides the display panel described above, taking the OLED display panel as an example, specifically, such as a touch structure, an interlayer dielectric layer or an encapsulation layer, and the like, and those skilled in the art can perform corresponding supplement according to the functional design of the display panel, and details are not described herein.

In summary, according to the embodiments of the present invention, the present invention provides a display panel, which has a shorter manufacturing cycle of a display backplane, a higher yield, and a better brightness uniformity of the display backplane, so as to improve the display quality of the display panel. It will be understood by those skilled in the art that the features and advantages described above for the display backplane are still applicable to the display panel and will not be described herein again.

In another aspect of the invention, a display device is provided. According to an embodiment of the invention, the display device comprises the display panel.

According to the embodiment of the present invention, the specific type of the display device is not particularly limited, such as a display screen, a television, a mobile phone, a tablet computer, or a smart watch, and the like, and those skilled in the art can select the display device according to the actual use requirement of the display device, and details thereof are not repeated herein. It should be noted that the display device includes other necessary components and structures besides the display substrate, taking an OLED display screen as an example, specifically, such as a touch panel, a housing, a control circuit board or a power line, etc., and those skilled in the art can supplement the display device accordingly according to the functions of the display device, and details are not repeated herein.

In summary, according to the embodiments of the present invention, the present invention provides a display device, in which the display quality of the display panel is better and the manufacturing yield is higher, so that the market competitiveness of the display device is higher. It will be understood by those skilled in the art that the features and advantages described above for the display backplane and the display panel are still applicable to the display device and will not be described herein again.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims

1. A display backplane, comprising:

a substrate;

a pixel defining layer disposed at one side of the substrate and having a plurality of first openings and a plurality of second openings;

an anode layer disposed in the first opening;

an auxiliary cathode disposed in the second opening;

a light emitting layer covering the pixel defining layer and the anode layer and having a plurality of laser openings whose orthographic projections on the substrate are partially overlapped with the orthographic projections of the auxiliary cathodes on the substrate;

the distance between two adjacent laser holes along a second direction is gradually reduced along a first direction, and the second direction and the first direction are arranged in a crossed mode.

2. The display backplane of claim 1, wherein a pitch of two of the laser apertures adjacent in the first direction also gradually decreases in the second direction.

3. The display backplane of claim 1, wherein the laser apertures in the first direction are the same area.

4. The display backplane of claim 2, wherein the laser apertures in the second direction are the same area.

5. The display backplane of claim 1, wherein an area of the laser apertures increases gradually along the first direction.

6. The display backplane of claim 1, further comprising:

a cathode layer covering the light emitting layer, and the cathode layer is in contact with the auxiliary cathode through the laser opening.

7. The display backplane of claim 6, further comprising:

a signal terminal electrically connected to the cathode layer and disposed at an end of the substrate opposite to the first direction from the plurality of laser openings.

8. The display backplane of claim 1, wherein the anode layer is disposed in a same layer as at least a portion of the auxiliary cathode.

9. A display panel comprising the display backplane according to any one of claims 1 to 8.

10. A display device characterized by comprising the display panel according to claim 9.