U.S. patent application number 16/431411 was filed with the patent office on 2019-09-19 for microled display panel.
The applicant listed for this patent is Prilit Optronics, Inc.. Invention is credited to Fa-Ming Chen, Biing-Seng Wu.
Application Number | 20190289687 16/431411 |
Document ID | / |
Family ID | 61687038 |
Filed Date | 2019-09-19 |
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United States Patent
Application |
20190289687 |
Kind Code |
A1 |
Wu; Biing-Seng ; et
al. |
September 19, 2019 |
MICROLED DISPLAY PANEL
Abstract
A microLED display panel includes a substrate being divided into
a plurality of sub-regions for supporting microLEDs, and a
plurality of drivers being correspondingly disposed on surfaces of
the sub-regions respectively. The driver includes a low-dropout
(LDO) regulator and a drive circuit. The LDO regulator receives a
system power, according to which a regulated power is generated and
provided for the drive circuit.
Inventors: |
Wu; Biing-Seng; (Tainan
City, TW) ; Chen; Fa-Ming; (Tainan City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Prilit Optronics, Inc. |
Tainan City |
|
TW |
|
|
Family ID: |
61687038 |
Appl. No.: |
16/431411 |
Filed: |
June 4, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15703458 |
Sep 13, 2017 |
10356858 |
|
|
16431411 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G09F 9/33 20130101; H01L
25/167 20130101; G09F 1/00 20130101; H05K 1/0306 20130101; H05K
2201/10053 20130101; H05B 45/37 20200101; H01L 25/0753 20130101;
H05K 2201/10106 20130101 |
International
Class: |
H05B 33/08 20060101
H05B033/08; G09F 9/33 20060101 G09F009/33; G09F 1/00 20060101
G09F001/00; H01L 25/075 20060101 H01L025/075 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 26, 2016 |
TW |
105131054 |
Jun 7, 2017 |
TW |
106118892 |
Claims
1. A micro light-emitting diode (microLED) display panel,
comprising: a plurality of microLEDs; a substrate for supporting
the microLEDs, the substrate being divided into a plurality of
sub-regions; and a plurality of drivers being correspondingly
disposed on surfaces of the sub-regions respectively; wherein each
of the drivers comprises a low-dropout (LDO) regulator and a drive
circuit, the LDO regulator receiving a system power, according to
which a regulated power is generated and provided to the drive
circuit.
2. The microLED display panel of claim 1, wherein the substrate
comprises an insulating material.
3. The microLED display panel of claim 2, wherein the substrate
comprises glass.
4. The microLED display panel of claim 1, wherein each said driver
is disposed in a center of the surface of the corresponding
sub-region.
5. The microLED display panel of claim 1, wherein the drivers are
bonded on the surfaces of the sub-regions by chip-on-glass (COG)
technology.
6. The microLED display panel of claim 1, wherein the drivers and
the microLEDs are disposed on a same surface of the substrate.
7. The microLED display panel of claim 1, further comprising a
plurality of timing controllers, which are electrically connected
with the substrate, which is then electrically connected with the
corresponding drivers.
8. The microLED display panel of claim 7, wherein each said timing
controller is electrically connected with at least two said
drivers.
9. The microLED display panel of claim 1, wherein the microLEDs are
driven by a passive driving method.
10. The microLED display panel of claim 9, wherein the drive
circuit comprises: a column drive circuit, which transmits column
drive signals to first electrodes of the microLEDs on same columns
via column conductive wires; and a row drive circuit, which
transmits row drive signals to second electrodes of the microLEDs
on same rows via row conductive wires.
11. The microLED display panel of claim 1, wherein the microLEDs
and the drivers are disposed on a top surface of the substrate.
12. The microLED display panel of claim 11, further comprising a
light guide layer disposed above the microLEDs.
13. The microLED display panel of claim 11, further comprising a
cover plate disposed on a bottom surface of the substrate such that
light generated by the microLEDs primarily emits upward from the
top surface of the substrate.
14. The microLED display panel of claim 13, further comprising: a
trace layer disposed on the top surface of the substrate; and a
light blocking layer disposed above the trace layer.
15. The microLED display panel of claim 14, wherein the light
blocking layer is disposed between adjacent pixels composed of the
microLEDs.
16. The microLED display panel of claim 14, wherein the light
blocking layer is disposed among a red microLED, a green microLED
and a blue microLED of a pixel.
17. The microLED display panel of claim 11, further comprising a
cover plate disposed above the microLEDs and the drivers such that
light generated by the microLEDs primarily emits downward from the
top surface of the substrate.
18. The microLED display panel of claim 17, further comprising: a
light blocking layer disposed on the top surface of the substrate;
and a trace layer disposed above the light blocking layer.
19. The microLED display panel of claim 18, wherein the light
blocking layer is further disposed between adjacent pixels composed
of the microLEDs.
20. The microLED display panel of claim 18, wherein the light
blocking layer is disposed among a red microLED, a green microLED
and a blue microLED of a pixel.
21. The microLED display panel of claim 1, further comprising a
smoothing capacitor interposed between the regulated power and
earth.
22. The microLED display panel of claim 1, wherein the LDO
regulator is made by high-voltage metal-oxide-semiconductor (MOS)
process, and the drive circuit is made by low-voltage MOS process.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application under 35 U.S.C.
120 of U.S. application Ser. No. 15/703,458, filed on Sep. 13,
2017, which, in turn, claims priority to Taiwan Application No.
105131054, filed on Sep. 26, 2016, and Taiwan Application No.
106118892, filed on Jun. 7, 2017. The entire contents of all of the
foregoing applications are herein expressly incorporated by
reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The present invention generally relates to a display panel,
and more particularly to a microLED display panel.
2. Description of Related Art
[0003] A micro light-emitting diode (microLED, mLED or .mu. LED)
display panel is one of flat display panels, which is composed of
microscopic microLEDs each of a size of 1-10 micrometers. Compared
to conventional liquid crystal display panels, the microLED display
panels offer better contrast, response times and energy efficiency.
Although both organic light-emitting diodes (OLEDs) and microLEDs
possess good energy efficiency, the microLEDs, based on group III/V
(e.g., GaN) LED technology, offer higher brightness, higher
luminous efficacy and longer lifespan than the OLEDs.
[0004] Active matrix using thin-film transistors (TFT) may be used
in companion with microLEDs to drive a display panel. However,
microLED is made by flip chip technology, while TFT is made by
complementary metal-oxide-semiconductor (CMOS) process which is
more complex than flip chip technology. These two distinct
technologies may cause thermal mismatch. A drive current of the
microLED is small in gray display, which may be significantly
affected by leakage current.
[0005] Passive matrix is another driving method performed by a row
drive circuit and a column drive circuit, which are disposed on the
periphery of a display panel. When the size or the resolution of
the display panel increases, output loading and delay of the drive
circuits increase accordingly, causing the display panel to
malfunction. Therefore, passive matrix is not suitable for
large-size microLED display panels.
[0006] A need has thus arisen to propose a novel microLED display
panel, particularly a large-size or high-resolution display panel,
which is capable of maintaining advantages of microLEDs and
overcoming disadvantages of driving schemes.
SUMMARY OF THE INVENTION
[0007] In view of the foregoing, it is an object of the embodiment
of the present invention to provide a microLED display panel
capable of effectively reducing loading of drivers, thereby making
whole large-size high-resolution microLED display panel feasible.
Passive driving scheme is adopted in one embodiment to simplify the
process of making display panels, reduce turn-on time of the
microLEDs, increase drive current, and effectively minimize effect
on gray display due to leakage current.
[0008] According to one embodiment, a microLED display panel
includes a plurality of microLEDs, a substrate and a plurality of
drivers. The substrate is utilized for supporting the microLEDs,
and the substrate is divided into a plurality of sub-regions. The
drivers are correspondingly disposed on surfaces of the sub-regions
respectively. In one embodiment, the microLEDs are driven by a
passive driving method. The driver includes a column drive circuit,
which transmits column drive signals to first electrodes of the
microLEDs on same columns via column conductive wires; and a row
drive circuit, which transmits row drive signals to second
electrodes of the microLEDs on same rows via row conductive wires.
The driver includes a low-dropout (LDO) regulator and a drive
circuit, the LDO regulator receiving a system power, according to
which a regulated power is generated and provided to the drive
circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1A shows a top view illustrated of a microLED display
panel according to one embodiment of the present invention;
[0010] FIG. 1B shows a side view illustrated of the microLED
display panel of FIG. 1A;
[0011] FIG. 2 shows a schematic diagram illustrated of passive
driving the microLED display panel;
[0012] FIG. 3 shows a cross-sectional view illustrated of a
frontside illuminating microLED display panel according to a first
specific embodiment of the present invention;
[0013] FIG. 4 shows a cross-sectional view illustrated of a
backside illuminating microLED display panel according to a second
specific embodiment of the present invention;
[0014] FIG. 5 shows an exemplary current-voltage curve of a
microLED; and
[0015] FIG. 6 shows a system block diagram illustrated of a driver
according to one embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0016] FIG. 1A shows a top view illustrated of a micro
light-emitting diode (microLED) display panel 100 according to one
embodiment of the present invention, and FIG. 1B shows a side view
illustrated of the microLED display panel 100 of FIG. 1A. The
microLED display panel of the embodiment is preferably adaptable to
a large-size and high-resolution (e.g., 3840RGB.times.2160) display
panel. In the specification, the size range of the microLED is
between 1 and 10 micrometers. However, the size of the microLED may
be even smaller due to specific applications or technological
advance. In the specification, "large-size" display panel is
currently and commonly referred to 10 inches or above display
panel. However, "large-size" display panel may be referred to other
display size due to specific applications or technological advance.
In the specification, "high-resolution" display panel is currently
and commonly referred to a display panel with 1080 or above scan
lines. However, "high-resolution" display panel may be referred to
other amount of scan lines due to specific applications or
technological advance.
[0017] In the embodiment, the microLED display panel 100 may
include a substrate 11 for supporting a plurality of microLEDs (now
shown). The substrate 11 may be preferably made of an insulating
material (e.g., glass or Acrylic) or other materials suitable for
supporting the microLEDs.
[0018] According to one aspect of the embodiment, a surface of the
substrate 11 is divided into a plurality of sub-regions 101. It is
noted that the divided sub-regions 101 are not physically cut
through, and the substrate 11 is not made by integrating the
sub-regions 101. In other words, the substrate 11 or the microLED
display panel 100 is a single or whole entity, or an uncut entity.
FIG. 1A shows a simplified example of how the substrate 11 is
divided into sub-regions 101. Take a microLED display panel 100
with resolution 3840RGB.times.2160 as an example, the substrate 11
may be divided into 80.times.54 sub-regions 101, each having
resolution 48RGB.times.40. Nevertheless, this microLED display
panel 100 may be divided into more or less sub-regions 101.
[0019] According to another aspect of the embodiment, the microLED
display panel 100 may include a plurality of drivers 12, which are
correspondingly disposed on (e.g., top) surfaces of the sub-regions
101 respectively. The driver 12 as exemplified in FIG. 1A may, but
not necessarily, be disposed in the center of the surface of
corresponding sub-region 101. Each sub-region 101 as exemplified in
FIG. 1A has one corresponding driver 12. However, in other
embodiments, each sub-region 101 may have plural corresponding
drivers 12. The driver 12 of the embodiment may be manufactured as
an integrated circuit or chip, which is then bonded on the surface
of the sub-region 101, for example, by surface-mount technology
(SMT) such as chip-on-glass (COG) or flip chip. In one example, the
drivers 12 and the microLEDs are disposed on the same surface of
the substrate 11.
[0020] The microLED display panel 100 of the embodiment may further
include a plurality of timing controllers (TCON) 13, which are
electrically connected with the substrate 11, for example, via a
flexible printed circuit board (FPCB), and are further electrically
connected with corresponding drivers 12, for example, via signal
traces (not shown) disposed on the substrate 11. In the embodiment,
one timing controller 13 may be electrically connected with at
least two drivers 12. In other words, the amount of the timing
controllers 13 may be less than the amount of the drivers 12. The
timing controller 13 may be electrically connected directly with
corresponding drivers 12 via signal traces. Alternatively, the
timing controller 13 may be electrically connected to one driver 12
via signal traces, and, after signal buffering, then be
electrically connected to another driver 12 via signal traces.
[0021] According to a further aspect of the embodiment, the
microLED display panel 100 may adopt passive driving method for
driving the microLEDs. FIG. 2 shows a schematic diagram illustrated
of passive driving the microLED display panel 100. The timing
controller 13 transmits timing control signals and data signals to
the driver 12. The driver 12 may include a column drive circuit 121
and a row (or scan) drive circuit 122. The column drive circuit 121
transmits column drive signals to first electrodes (e.g., anodes)
of the microLEDs 14 on the same columns via column conductive wires
1211, and the row drive circuit 122 transmits row drive signals to
second electrodes (e.g., cathodes) of the microLEDs 14 on the same
rows via row conductive wires 1221. In the embodiment, the column
drive circuit 121 and the row drive circuit 122 are made in a
single integrated circuit.
[0022] According to the embodiment discussed above, the substrate
11 of the microLED display panel 100 is divided into sub-regions
101, each of which has a corresponding driver 12. Therefore,
loading of the column drive circuit 121 and the row drive circuit
122 may be effectively reduced, thereby making whole large-size
high-resolution microLED display panel feasible. Moreover, the
microLED display panel 100 of the embodiment adopts a passive
driving method (instead of active driving method using thin-film
transistors) for driving the microLEDs 14, thereby simplifying the
process of making display panels, reducing turn-on time of the
microLEDs 14, increasing drive current, and effectively minimizing
effect on gray display due to leakage current.
[0023] FIG. 3 shows a cross-sectional view illustrated of a
frontside illuminating microLED display panel 300 according to a
first specific embodiment of the present invention. In the
embodiment, the microLEDs 14 and the driver 12 are disposed above a
top surface of the substrate 11. Light generated by the microLEDs
14 primarily emits upward (i.e., frontside illuminating) from the
top surface of the substrate 11 as indicated by arrows.
[0024] As exemplified in FIG. 3, each pixel may include a red
microLED 14R, a green microLED 14G and a blue microLED 14B. A trace
layer 15 is disposed between a (e.g., top) surface of the substrate
11 and the microLEDs 14 and the driver 12. The trace layer 15 is
configured to electrically connect the driver 12, the microLEDs 14
and the timing controller 13. A light blocking layer 16 is disposed
between adjacent pixels and above the trace layer 15. The light
blocking layer 16 of the embodiment may be made of black matrix
(BM) or other materials suitable for blocking light. In one
embodiment, the light blocking layer 16 may be optionally disposed
among the red microLED 14R, the green microLED 14G and the blue
microLED 14B of the same pixel.
[0025] A light guide layer 17 may be disposed above the red
microLED 14R, the green microLED 14G and the blue microLED 14B. The
frontside illuminating microLED display panel 300 of the embodiment
may further include a cover plate 18 disposed on a bottom surface
of the substrate 11. The cover plate 18 of the embodiment may be
made of an opaque material.
[0026] FIG. 4 shows a cross-sectional view illustrated of a
backside illuminating microLED display panel 400 according to a
second specific embodiment of the present invention. In the
embodiment, the microLEDs 14 and the driver 12 are disposed above a
top surface of the substrate 11. Light generated by the microLEDs
14 primarily emits downward (i.e., backside illuminating) from the
bottom surface of the substrate 11 as indicated by arrows.
[0027] As exemplified in FIG. 4, each pixel may include a red
microLED 14R, a green microLED 14G and a blue microLED 14B. A light
blocking layer 16 is disposed between adjacent pixels and above a
(e.g., top) surface of the substrate 11. The light blocking layer
16 of the embodiment may be made of black matrix (BM) or other
materials suitable for blocking light. A trace layer 15 is disposed
above the light blocking layer 16 for electrically connecting the
driver 12, the microLEDs 14 and the timing controller 13. In one
embodiment, the light blocking layer 16 may be optionally disposed
among the red microLED 14R, the green microLED 14G and the blue
microLED 14B of the same pixel.
[0028] A light guide layer 17 may be disposed above the red
microLED 14R, the green microLED 14G and the blue microLED 14B. The
backside illuminating microLED display panel 400 of the embodiment
may further include a cover plate 18 disposed above the driver 12,
the trace layer 15, the light blocking layer 16 and the light guide
layer 17. The cover plate 18 of the embodiment may be made of an
opaque material.
[0029] FIG. 5 shows an exemplary current-voltage curve of a
microLED 14. When an operating voltage is greater than a turn-on
voltage Vf (e.g., 3 volts), a current greater than a predetermined
value may be obtained to normally operate and turn on the micro-LED
14. For the microLED display panel 100 shown in FIG. 1A, a system
power for the drivers 12 is VDDA. However, a voltage drop .DELTA.V
exists in the center of the microLED display panel 100 due to
impedance in the conductive wire for transferring the power.
Accordingly, the drivers 12 disposed in the center of the microLED
display panel 100 in fact receive power of VDDA-.DELTA.V, although
the drivers 12 disposed on the periphery of the microLED display
panel 100 receive power of VDDA. For example, assume the voltage
drop .DELTA.V is 1 volt and the turn-on voltage Vf is 3 volts. The
condition under which the drivers 12 may be normally operated is
VDDA-1>3, that is, VDDA>4 (e.g., VDDA of 5 volts is
required). In this situation, the drivers 12 may be made by
low-voltage metal-oxide-semiconductor (MOS) process.
[0030] Nevertheless, as the amount of microLEDs 14 increases,
consumed current then increases and a voltage drop .DELTA.V
significantly increases accordingly (e.g., increases to 4 volts).
The condition under which the drivers 12 may be normally operated
is VDDA-4>3, that is, VDDA>7 (e.g., VDDA of 8 volts is
required). In this situation, the drivers 12 should be made by
high-voltage metal-oxide-semiconductor (MOS) process, which results
in larger circuit area that is unfavorable for making large-size
high-resolution (e.g., 3840RGB.times.2160) display panel. For
overcoming the problems, an architecture of a novel driver 12 is
proposed.
[0031] FIG. 6 shows a system block diagram illustrated of a driver
12 according to one embodiment of the present invention. In the
embodiment, the driver 12 may include a low-dropout (LDO) regulator
123 and a drive circuit 120. The LDO regulator 123 receives a
system power VDDA, according to which a regulated power VR (e.g., 5
volts) is generated and provided as a power for the drive circuit
120. The LDO regulator 123 of the embodiment may be implemented
according to circuit design of conventional LDO regulators, and
details of which are thus omitted for brevity. The drive circuit
120 of the embodiment may include a column drive circuit 121 and a
row drive circuit 122. The LDO regulator 123 is one of
direct-current (DC) linear regulators, which are configured to
generate a regulated power VR substantially equal to the system
power VDDA. Compared to a switching regulator, the LDO regulator
123 occupies less circuit area with simpler circuit design and
without switching noise. In the embodiment, a smoothing capacitor C
may be interposed between the regulated power VR and earth, thereby
filtering out high-frequency noise. The smoothing capacitor C may
be formed with a metal layer process (instead of extra process)
commonly used in display panel manufacturing.
[0032] According to the driver 12 of the embodiment as discussed
above, only the LDO regulator 123 should be made by high-voltage
(e.g., greater than 8 volts) MOS process, while the drive circuit
120 may be made by low-voltage (e.g., less than 8 volts) MOS
process. On the contrary, for a driver without LOD regulator 123,
entire driver 12 should be made by high-voltage MOS process. As a
result, the driver 12 of the embodiment may significant reduce
circuit area and facilitate making large-size or high-resolution
display panels.
[0033] Although specific embodiments have been illustrated and
described, it will be appreciated by those skilled in the art that
various modifications may be made without departing from the scope
of the present invention, which is intended to be limited solely by
the appended claims.
* * * * *