# Patent

## Title
Array substrate of organic light-emitting diodes and method for packaging the same

## Abstract

A single display panel and an electronic device are provided. The single display panel comprises an upper substrate; a lower substrate including a display area and a stepped area; and a frame adhesive disposed between the upper substrate and the to a substrate, and surrounding the display area, wherein there is no blank area around the display panel. The single display panel is obtained from an array substrate comprising OLED display panels to be separated from each other through a cutting, wherein the display panel includes a display area, at least two adjacent display panels are connected through the frame adhesive disposed at an edge frame surrounding the display area but not covering the display area, and there is no cutting headroom between at least one side of the at least two adjacent display panels.

## Background
CROSS-REFERENCES TO RELATED APPLICATIONS
This application is a continuation-in-part (CIP) application of U.S. patent application Ser. No. 14/667,621, filed on Mar. 24, 2015 which claims the priority to Chinese Patent Application No. 201410822726.3, entitled “ARRAY SUBSTRATE OF ORGANIC LIGHT-EMITTING DIODES AND METHOD FOR PACKAGING THE SAME”, and filed with the State Intellectual Property Office of People's Republic of China oil Dec. 22, 2014, the content of all of which is incorporated herein by reference in its entirety.


TECHNICAL FIELD
The present disclosure relates to the field of display and packaging technologies, and particularly to an array substrate of organic light-emitting diodes and a method for packaging the same.
BACKGROUND OF THE INVENTION
As illustrated in FIG. 1 an array substrate 10 of Organic Light-Emitting Diodes (OLEDs) in the prior art includes a plurality of display panels 11 arranged in an array, and each display panel 11 includes a display area 12, a frame adhesive 13 with a width of 0.7 mm at an edge frame of the display area 12, and a stepped area 14 which is an area in the display panel where an integrated circuit is fabricated. There is a cutting headroom between every two display panels 11, the cutting headroom is an area without frame adhesive 13 at the locations where the array substrate 10 is cut into a single display panel 11. In FIG. 1, there are a width B of a cutting headroom between two adjacent display panels 11 in the horizontal direction, and a width A of a cutting headroom between two adjacent display panels 11 in the vertical direction, and in order to prevent damage to the display panels being cut, the width A or B of the cutting headroom in a practical production process is preset to 600 to 800 micrometers.
In FIG. 1, due to the cutting headroom between every two display panels, each display panel needs to be packaged by coating the frame adhesive thereto separately and laser curing the coated frame adhesive separately. FIG. 2 illustrates a structural diagram of a single packaged display panel in a sectional view, the frame adhesive 13 is disposed between an upper substrate 21 and a lower substrate 20 and laser cured by disposing a reflection layer 22 on the lower substrate 20, to thereby better reflect a laser beam so as to make the laser beam more uniform.
In summary, the width A or B of the frame adhesive in the prior art is preset to 600 to 800 micrometers, so that the edge frame of the display panel may become large instead of being narrowed. Moreover, it may take a long period of time to perform the packaging process in the prior art due to the separate adhesive coating process and the separate laser curing process, and each display panel has to he packaged by coating the frame adhesive thereto separately, and laser curing the coated frame adhesive separately, so that there may be wastes of time and materials, and the substrates may be underutilized. Moreover, it may take a long period of time to cure the adhesive by using laser, thus resulting in inefficiency.
BRIEF SUMMARY OF THE INVENTION
One aspect of the present disclosure provides a single display panel. The single display panel comprises an upper substrate; a lower substrate including a display area and a stepped area adjacent to the display area; and a frame adhesive disposed between the upper substrate and the lower substrate, and surrounding the display area, wherein: the upper substrate and the lower substrate are coupled to each other by the frame adhesive, there is no blank area around the display panel, a blank area of the single display panel being an area of the upper substrate and lower substrate and disposed surrounding the frame adhesive, and the single display panel is obtained from an array substrate comprising a plurality of packaged organic light-emitting diode (OLED) display panels arranged in an array of rows and columns and to be separated from each other through a cutting, wherein the display panel includes a display area, at least two adjacent display panels are connected through the frame adhesive disposed at an edge frame surrounding the display area but not covering the display area, and there is no cutting headroom between at least one side of the at least two adjacent display panels.
Another aspect of the present disclosure provides an electronic device comprising the single display panel.
Other aspects of the present disclosure can he understood by those skilled in the art in light of the description, the claims, and the drawings of the present disclosure.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a top plan of an array substrate of organic light-emitting diodes in the prior art;
FIG. 2 illustrates a cross-sectional view of a display panel in the array substrate of organic light-emitting diodes in the prior art;
FIG. 3 illustrates a flow chart of a method for packaging an array substrate of organic light-emitting diodes according to an embodiment of the present disclosure;
FIG. 4 illustrates a top plan view of an array substrate of organic light-emitting diodes according to a first embodiment of the present disclosure;
FIG. 5a and FIG. 5b illustrate top plan views of an array substrate of organic light-emitting diodes according to a second embodiment of the present disclosure;
FIG. 6 illustrates across-sectional view of a part of an area of the array substrate of organic light-emitting diodes according to the first embodiment and the second embodiment of the present disclosure;
FIG. 7 illustrates a plan view of a single display panel as a result of cutting in the prior art;
FIG. 8 illustrates a plan view of a single display panel as a result of cutting according to the first embodiment and the second embodiment of the present disclosure;
FIG. 9 illustrates a C-C′ sectional view of a single display panel in FIG. 7 as a result of cutting in the prior art;
FIG. 10a illustrates an A-A′ sectional view of a single display panel in FIG. 8 as a result of cutting according to the first embodiment and the second embodiment of the present disclosure;
FIG. 10b illustrates a B-B′ sectional view of a single display panel in FIG. 8 as a result of cutting according to the first embodiment and the second embodiment of the present disclosure;
FIG. 11 illustrates a cross-sectional view of another exemplary single display panel according to the embodiments of the present disclosure; and
FIG. 12 illustrates an exemplary electronic device according to the embodiments of the present disclosure.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments of the present disclosure provide an array substrate of organic light-emitting diodes and a method for fabricating the same, so as to narrow an edge frame of the product of organic light-emitting diodes, to shorten the package process time, to improve the substrate utilization and to improve the production efficiency.
In order to make the objects, technical solutions and advantages of the present disclosure more apparent, the present disclosure will be described below in further details with reference to the drawings, and evidently the embodiments described here are merely a part but not all of the embodiments. All the other embodiments which can occur to those ordinarily skilled in the art from embodiments here of the present disclosure without any inventive effort shall fall into the scope of the present disclosure.
The technical solutions according to embodiments of the present disclosure will be described below in details.
As illustrated in FIG. 3, a method for packaging an array substrate of organic light-emitting diodes according to an embodiment of the present disclosure includes the following operations:
S301: coat a frame adhesive to at least two adjacent display panels, so that there is no cutting headroom between at least one side of the at least two adjacent display panels;
S302: cure the frame adhesive using a first laser beam;
S303: ablate the frame adhesive using a second laser beam at the location where cutting is needed, so that a broken area is generated on the surface of the frame adhesive at the cut locations, herein the power of the first laser bean n is higher than the power of the second laser beam; and
S304: cut the array substrate, at the cut locations, into single display panels.
An embodiment of the present disclosure further provides an array substrate of organic light-emitting diodes, the array substrate including a plurality of display panels disposed in, an array, herein at least two adjacent display panels are connected through a frame adhesive, and there is no cutting headroom, between at least one side of the at least two adjacent display panels.
The array substrate of organic light emitting diodes according to an embodiment of the present disclosure will be described below in details with reference to FIG. 4, FIG. 5a and FIG. 5b. 
First Embodiment
As illustrated in FIG. 4, a first embodiment of the present disclosure provides an array substrate 40 of organic light-emitting diodes, the array substrate including a plurality of display panels 41 disposed in an array, herein at least two adjacent display panels 41 are connected through a frame adhesive 13, and there is no cutting headroom (spacing) between at least one sides of at least two adjacent display panels. There is no stepped area disposed in the display panels 41 according to the first embodiment of the present disclosure, and optionally there is no cutting headroom in any two adjacent display panels 41.
According to the first embodiment of the present disclosure, a method for packaging the array substrate 40 of organic light-emitting diodes includes: coating a frame adhesive to all display panels 41 at a time, so that the all display panels 41 are connected through the frame adhesive 13 and there is, no cutting headroom between the display panels 41. Optionally the coated frame adhesive 13 is cured using a first laser beam which is an infrared laser beam at a wavelength of 788 to 828 nanometers, and a power of 1 to 10 watts. Particularly the first laser beam in the first embodiment of the present disclosure is at a wavelength of 808 nanometers (nm), a power of 5 watts (W), a speed of 5 millimeters per second (mm/s), a temperature of 350° C. and an energy penetration distance of 1.8 millimeters (mm).
Next the frame adhesive is ablated by using a second laser beam, which is an infrared, laser beam at a wavelength of 788 to 828 nanometers and a power of 5 to 15 watts, at the locations where cutting is needed, so that a broken area is generated on the surface of the frame adhesive 13 at the cut locations. Particularly the second laser beam in the first embodiment of the present disclosure is at a wavelength of 808 nm, a power of 10 W, a speed of 20 mm/s, a temperature of 500° C. and an energy penetration distance of 0.2 mm.
Finally the array substrate is cut, at the cut locations, into single display panels, the directed arrows 47, 48 in FIG. 4 represent the cut locations, and particularly the array substrate is cut at the cut locations (lines), according to the first embodiment of the present disclosure, by cutting the array substrate respectively at the cut locations in the broken area. Optionally according to the first embodiment of the present disclosure, the locations where cutting is needed are determined by using alignment cutting markers in an image controller, particularly alignment markers in Charge Coupled Devices (CCDs), i.e., CCD image sensors. The frame adhesive can be ablated, by using the second laser beam with an energy greater than the first laser beam, at the locations where cutting is needed according to the first embodiment or the present disclosure, so that the surface of the frame adhesive 13 can be broken as appropriate to facilitate separation, and subsequently the frame adhesive can be cut at the cut locations mechanically by using a knife wheel.
FIG. 6 illustrates a simplified cross-sectional view of an area 42 of the array substrate 40 of organic light-emitting diodes according to the first embodiment and the second embodiment of the present disclosure, where the area includes an upper substrate 61 and a lower substrate 60, and the frame adhesive 13 between the upper substrate 61 and the lower substrate 60, and the dotted lines represent the locations where the frame adhesive is ablated by using the second laser beam, and also the locations where the array substrate is subsequently cut mechanically by using a knife wheel.
Second Embodiment
As illustrated in FIG. 5a and FIG. 5b, a second embodiment of the present disclosure provides an array substrate of organic light-emitting diodes 50, the array substrate including a plurality of display panels 11 arranged in an array of rows and columns, herein at least two adjacent display panels 11 are connected, through a frame adhesive 13, and there is no cutting headroom between at least one side of the two adjacent display panels. There is a stepped area 14 disposed in the display panels 11 according to the second embodiment of the present disclosure, Each of the display panels 11 includes a display area 12, a frame adhesive 13 surrounding display area 12, and a stepped area 14 disposed at one side of frame adhesive 13.
Optionally in the second embodiment of the present disclosure, a display panel unit includes at least two display panels, and there is no cutting headroom between at least one side of two adjacent display panels other than the stepped area sides, as illustrated in FIG. 5a and FIG. 5b. In other words, at least one side between two adjacent display panels except the side of the stepped area has no cutting headroom.
As illustrated in FIG. 5a, in the second embodiment of the present disclosure, the display panel unit 51 includes each column of display panels 11, and the stepped area 14 of a column of display panels 11 is disposed on the left side or right side of the column of display panels 11. There is a cutting headroom disposed between every two adjacent sets of display panel units 51, and the width B of the cutting headroom in the second embodiment of the present disclosure is preset to 600 to 800 micrometers as in the prior art.
As illustrated in FIG. 5b, in the second embodiment of the present disclosure, the display panel unit 52 includes two or multiple pairs of adjacent columns of display panels 11, and the stepped area 14 of a pair of adjacent columns of display panels 11 is disposed on the left side of the column of display panels 11, whereas the stepped area 14 of the other column of display panels 11 is disposed on the right side of the column of display panels 11; and there is neither cutting headroom between sides of two adjacent display panels 11 in the row direction, nor cutting headroom between sides of two adjacent display panels 11 in the column direction. There is a cutting headroom disposed between every two adjacent sets (every pair of adjacent columns) of display panel units 52, and the width B of the cutting headroom, in the second embodiment of the present disclosure, is preset to 600 to 800 micrometers as in the prior art.
According to the second embodiment of the present disclosure, a method for packaging the array substrate of organic light-emitting diodes 50 includes coating a frame adhesive respectively to the display panel units 51 or 52, that is, the frame adhesive in the display panel units 51 or 52 is coated at a time, so that the display panels 11 in the display panel units 51 or 52 are connected by the frame adhesive 13, and there is no cutting headroom between the display panels 11. In the second embodiment of the present disclosure, the coated frame adhesive 13 is cured by using a first laser beam which is substantially the same as the first laser beam in the first embodiment of the present disclosure, so that a repeated description thereof will be omitted here.
Next, the frame adhesive is ablated by using a second laser beam at the locations where cutting is needed, so that a broken area is generated on the surface of the frame adhesive 13 at the cut locations. The second laser beam in the second embodiment of the present disclosure is substantially the same as the second laser beam in the first embodiment of the present disclosure, so that a repeated description thereof will be omitted here.
Finally the array substrate is cut, at the cut locations, into single display panels. The directed arrows in FIG. 5a and FIG. 5b represent the cut locations. And particularly the array substrate is cut at the cut locations, according to the second embodiment of the present disclosure, by cutting the array substrate respectively at the cut locations in the cutting headroom disposed between two adjacent sets of display panel units, and the cut locations in the broken area. Optionally according to the second embodiment of the present disclosure, the locations where cutting is needed are determined by using alignment cutting markers in an image controller, particularly alignment markers in CCD image sensors. The frame adhesive can be ablated by using the second laser beam at an energy stronger than the first laser beam at the locations where cutting is needed according to the second embodiment of the present disclosure, so that the surface of the frame adhesive 13 can be broken as appropriate to facilitate cutting for separation, and subsequently the frame adhesive can be cut at the cut locations mechanically by using a knife wheel.
FIG. 6 illustrates a schematic structural diagram of an area 53 of the array substrate of organic light-emitting diodes 50 in FIG. 5a and an area 54 of the array substrate of organic light-emitting diodes 50 in FIG. 5b in a sectional view, the areas include an upper substrate 61 and a lower substrate 60. and the frame adhesive 13 between the upper substrate 61 and the lower substrate 60. The dotted lines represent the locations where the frame adhesive is ablated by using the second laser beam and also the locations where the array substrate is subsequently cut mechanically by using a knife wheel.
FIG. 7 illustrates a schematic structural diagram of a single display panel as a result of cutting in the prior art in a plan view, and FIG. 9 illustrates a C-C′ sectional view of a single display panel in FIG. 7 as a result of cutting in the prior art. As shown in FIG. 9, after the cutting, the single display panel has an upper substrate 21, a lower substrate 20, a display area 12 and a frame adhesive 13 disposed between the upper substrate 21 and the lower substrate 20. The frame adhesive 13, which is disposed surrounding the display area 12, seals the single display panel and, meanwhile, maintains a cell gap of the single display panel. The reflection layer 22 is disposed on the lower substrate 20 and facilitates the curing of the frame adhesive.
In addition, as shown in FIG. 7 and FIG. 9, there is, a blank area 70 around the single display panel in the prior art. The blank area 70 of the single display panel refers to an area of the upper substrate 21 and an area of the lower substrate 20, in which the area is disposed surrounding the frame adhesive 13. The blank area may not be disposed with any frame adhesive. The blank area 70 of the existing single display panel often has a width d of about 300 to 400 micrometers and, thus, the existing single display panel may be bulky, which requires a large space to fit into an electronic device.
FIG. 8 illustrates a schematic structural diagram of a single display panel as a result of cutting according to the embodiments of the present disclosure in a plan view. FIG. 10a illustrates an A-A′ sectional view of a single display panel in FIG. 8 as a result of cutting according to the first embodiment and the second embodiment of the present disclosure. FIG. 10b illustrates a B-B′ sectional view of a single display panel in FIG. 8 as a result of cutting according to the first embodiment and the second embodiment of the present disclosure.
As shown in FIGS. 8 and 10a-10b, after being cut from the array substrate, the single display panel may comprise an upper substrate 61, a lower substrate 60 including a display area 12 and a stepped area 14 adjacent to the display area 12; and a frame adhesive 13 disposed between the upper substrate 61 and the lower substrate 60, and surrounding the display area 12. The frame adhesive 13 may seal the single display panel and maintain a cell gap of the single display panel. The upper substrate 61 and the lower substrate 60 may be coupled to each other by the frame adhesive 13. The display area 12 may be disposed with a display element, and the stepped area 14 may be disposed with an integrated circuit for controlling the display panel.
Different from the existing single display shown in FIG. 7 and FIG. 9, in the single display shown in FIGS. 8 and 10a-10b, there is no blank area around the single display panel according to the embodiments of the present disclosure. That is, the single display panel may not have a blank area surrounding the frame adhesive 13. Thus, the entire frame of the single display panel may be reduced, while the display area of the single display panel may substantially remain the same. The core competitiveness of the product may be improved according to the present disclosure. For example, the disclosed single display panel without blank area may be highly desired in wearable electronic devices.
FIG. 11 illustrates a cross-sectional view of another exemplary single display panel according to the embodiments of the present disclosure. The similarities between FIG. 11 and FIG. 10b are not repeated here, while certain differences may be explained.
Different from the single display panel shown in FIGS. 10b, the single display panel shown in FIG. 11 may further include a reflection layer 22 disposed on the lower substrate 60. The reflection layer 22 may be sandwiched between the frame adhesive 13 and the lower substrate 60 (i.e., beneath the frame adhesive 13), and disposed surrounding the display area 12. The reflection layer 22 may include metals, which reflect a laser beam so as to make the laser beam more uniform. In particular, the reflection layer 22 may be formed on the lower substrate 60 before coating a frame adhesive to at least two adjacent display panels, when packaging an array substrate of organic light-emitting diodes. That is, referring to FIG. 3, the reflection layer 22 may be formed on the lower substrate before Step S301.
The present disclosure also provides an electronic device. FIG. 12 illustrates an exemplary electronic device according to the embodiments of the present disclosure. As shown in FIG. 12, the electronic device 1200 may include a display panel 1202, which may be any of the disclosed single display panels. The electronic device 1200 may be a smart wearable device, a tablet, a TV, a smartphone, a notebook, and, a digital frame, etc. Further, the electronic device 1200 may be any appropriate type of content-presentation devices.
Because the electronic device 1200 includes any of the disclosed single display panels, the disclosed electronic device may also exhibit the same advantages as the disclosed single display panels. That is, due the single display panel 1202 without blank area, the electronic device 1200 with a Shrunk border region, which may save precious space when the electronic device is further implemented into other devices. For example, a circular speedometer with a shrunk border region may save precious space in a vehicle's crowded dashboard, which alt requires room for car-navigation displays and other recent additions.
In summary, according to embodiments of the present disclosure, there is no cutting headroom disposed between a part of adjacent display panels or between every two adjacent display panels, so that the frame adhesive can be coated directly to the all display panels being packaged, to thereby extend the display area from the inside thereof and narrow the edge frame by approximately 500 micrometers, so as to narrow the edge frame and improve the competitiveness of the product while guaranteeing the width 0.7 mm of the package. Moreover, it will not be necessary to coat the frame adhesive respectively to each display panel being packaged, to shorten the process time, reduce the material cost and improve the production efficiency.
It is noted that the preferable embodiments and the applied technology principles of the present disclosure are merely described as above. It should be understood for those skilled in the art that the present disclosure is not limited to particular embodiments described herein. Various apparent changes, readjustment and alternative can be made by those skilled in the art without departing from the scope of protection of the present disclosure. Therefore, although the present disclosure is illustrated in detail through the above specific embodiments, the present disclosure is not limited to the above embodiments, and can further include more of other equivalent embodiments without departing concept of the present disclosure. The scope of the present disclosure is subject to the appended claims.

## Claims

1. A single display panel, comprising:
an upper substrate;
a lower substrate including a display area and a stepped area adjacent to the display area; and
a frame adhesive disposed between the upper substrate and the lower substrate, and surrounding the display area,
wherein:
the upper substrate and the lower substrate are coupled to each other by the frame adhesive,
there is no blank area around the display panel, a blank area of the single display panel being an area of the upper substrate and lower substrate and disposed surrounding the frame adhesive, and
the single display panel is obtained from an array substrate comprising a plurality of packaged organic light emitting diode (OLED) display panels arranged in an array of rows and columns and to be separated from each other through a cutting, wherein the display panel includes a display area, at least two adjacent display panels are connected through the frame adhesive disposed at an edge frame surrounding the display area but not covering the display area, and there is no cutting headroom between at least one side of the at least two adjacent display panels.

2. The single display panel according to claim 1, wherein the single display panel comprises:
a cutting headroom is an area without the frame adhesive at locations where the array substrate is cut into a plurality of single display panels.

3. The single display panel according to claim 1, wherein:
the display area of the single display panel is disposed with a display element, and
the stepped area of the of the single display panel is disposed with an integrated circuit for controlling the single display panel.

4. The single display panel according to claim 1, further including:
a reflection layer disposed beneath the frame adhesive and surrounding the display area of the single display panel.

5. The single display panel according to claim 1 wherein:
there is no cutting headroom between every two adjacent display panels connected through the frame adhesive.

6. The single display panel according to claim 1, wherein:
a display panel unit comprises at least two display panels to be separated from each other through the cutting, in the display panel unit there is no cutting headroom between at least one side of two adjacent display panels other than stepped area sides, and the two adjacent display panels are connected through the frame adhesive.

7. The single display panel according to claim 6, wherein:
the display panel unit comprises a column of display panels.

8. The single display panel according to claim 6, wherein:
the display panel unit comprises two adjacent columns of display panels connected through the frame adhesive, each column of display panels includes at least two display panels connected through the frame adhesive, a first stepped area disposed and on the left side of the two adjacent columns of display panels, a second stepped area disposed on the right side of the two adjacent columns of display panels; there is no cutting headroom between the two adjacent columns of display panels in a row direction, and there is no cutting headroom between the two adjacent columns of display panels in a column direction.

9. The single display panel according to claim 6, wherein:
there is a cutting headroom disposed between every two display panel units.

10. An electronic device, comprising a single display panel, wherein:
the single display panel comprises,
an upper substrate;
a lower substrate including a display area and a stepped area adjacent to the display area; and
a frame adhesive disposed between the upper substrate and the lower substrate, and surrounding the display area,
wherein:
the tipper substrate and the lower substrate are coupled to each other by the frame adhesive,
there is no blank area around the display panel, a blank area of the single display panel being an area of the upper substrate and lower substrate and disposed surrounding the frame adhesive, and
the single display panel is obtained from an array substrate comprising a plurality of packaged organic light-emitting diode (OLED) display panels arranged in an array of rows and columns and to be separated from each other through a cutting, wherein the display panel includes a display area, at least two adjacent display panels are connected through the frame adhesive disposed at an edge frame surrounding the display area but not covering the display area, and there is no cutting headroom between at least one side of the at least two adjacent display panels.

11. The electronic device according to claim 10, wherein the single display panel comprises:
a cutting headroom is an area without the frame adhesive at locations where the array substrate is cut into a plurality of single display panels.

12. The electronic device according to claim 10, wherein:
the display area of the single display panel is disposed with a display element, and
the stepped area of the of the single display panel is disposed with an integrated circuit for controlling the single display panel.

13. The electronic device according to claim 10, wherein the single display panel further including:
a reflection layer disposed beneath the frame adhesive and surrounding the display area of the single display panel.

14. The electronic device according to claim 10, wherein:
there is no cutting headroom between every two adjacent display panels connected through the frame adhesive.

15. The electronic device according to claim 10, wherein:
a display panel unit comprises at least two display panels to be separated from each other through the cutting, in the display panel unit there is no cutting headroom between at least one side of two adjacent display panels other than stepped area sides, and the two adjacent display panels are connected through the frame adhesive.

16. The electronic device according to claim 15, wherein:
the display panel unit comprises a column of display panels.

17. The electronic device according to claim 15, wherein:
the display panel unit comprises, two adjacent columns of display panels connected through the frame adhesive, each column of display panels includes at least two display panels connected through the frame adhesive, a first stepped area disposed and on the left side of the two adjacent columns of display panels, a second stepped area disposed on the right side of the two adjacent columns of display panels; there is no cutting headroom between the two adjacent columns of display panels in a row direction, and there is no cutting headroom between the two adjacent columns of display panels in a column direction.

18. The electronic device according to claim 15, wherein:
there is a cutting headroom disposed between every two display panel units.