U.S. patent number 11,200,846 [Application Number 17/239,797] was granted by the patent office on 2021-12-14 for pixel circuit, silicon-based display panel, and display device.
This patent grant is currently assigned to SEEYA OPTRONICS CO., LTD.. The grantee listed for this patent is SEEYA OPTRONICS CO., LTD.. Invention is credited to Ping-lin Liu, Chang-ho Tseng, Tong Wu.
United States Patent |
11,200,846 |
Liu , et al. |
December 14, 2021 |
Pixel circuit, silicon-based display panel, and display device
Abstract
Provided are a pixel circuit, a silicon-based display panel, and
a display device. The pixel circuit includes a pixel drive circuit
and a pixel compensation circuit; the pixel drive circuit includes
a drive transistor and an organic light-emitting element; the drive
transistor includes an output terminal and a body terminal, where
the output terminal is connected to an anode of the organic
light-emitting element, and a cathode of the organic light-emitting
element is connected to a cathode signal input terminal and
configured to receive a cathode potential inputted from the cathode
signal input terminal, the cathode potential being fixed; the body
terminal is connected to the pixel compensation circuit at a first
node, and a potential of the first node is a body potential; and
the cathode potential V.sub.com, a crossover voltage V.sub.oled of
the organic light-emitting element, and the body potential
V.sub.body satisfy that V.sub.com+V.sub.oled>V.sub.body.
Inventors: |
Liu; Ping-lin (Shanghai,
CN), Tseng; Chang-ho (Shanghai, CN), Wu;
Tong (Shanghai, CN) |
Applicant: |
Name |
City |
State |
Country |
Type |
SEEYA OPTRONICS CO., LTD. |
Shanghai |
N/A |
CN |
|
|
Assignee: |
SEEYA OPTRONICS CO., LTD.
(Shanghai, CN)
|
Family
ID: |
1000005993343 |
Appl.
No.: |
17/239,797 |
Filed: |
April 26, 2021 |
Prior Publication Data
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|
|
Document
Identifier |
Publication Date |
|
US 20210335264 A1 |
Oct 28, 2021 |
|
Foreign Application Priority Data
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|
|
|
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Apr 26, 2020 [CN] |
|
|
202010338999.6 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G09G
3/3258 (20130101); G09G 3/3233 (20130101) |
Current International
Class: |
G09G
3/3258 (20160101); G09G 3/3233 (20160101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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101102113 |
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Jan 2008 |
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CN |
|
103093724 |
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May 2013 |
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CN |
|
104782048 |
|
Jul 2015 |
|
CN |
|
105654904 |
|
Jun 2016 |
|
CN |
|
Primary Examiner: Khoo; Stacy
Attorney, Agent or Firm: Duane Morris LLP
Claims
What is claimed is:
1. A pixel circuit, comprising a pixel drive circuit and a pixel
compensation circuit; wherein the pixel drive circuit comprises a
drive transistor and an organic light-emitting element; the drive
transistor comprises an output terminal and a body terminal,
wherein the output terminal is connected to an anode of the organic
light-emitting element, and a cathode of the organic light-emitting
element is connected to a cathode signal input terminal and
configured to receive a cathode potential inputted from the cathode
signal input terminal; the body terminal is connected to the pixel
compensation circuit at a first node, and a potential of the first
node is a body potential; and the cathode potential V.sub.com, a
crossover voltage V.sub.oled of the organic light-emitting element,
and the body potential V.sub.body satisfy that
V.sub.com+V.sub.oled>V.sub.body.
2. The pixel circuit according to claim 1, wherein the cathode
potential is adjustable.
3. The pixel circuit according to claim 1, wherein the cathode
potential is fixed.
4. The pixel circuit according to claim 2, wherein the pixel
compensation circuit comprises an operational amplifier circuit, a
first transistor, a first resistor, and a second resistor; wherein
the second resistor has adjustable resistance; the first transistor
comprises an input terminal connected to a first voltage signal
input terminal, an output terminal connected to a first terminal of
the second resistor, and a control terminal connected to an output
terminal of the operational amplifier circuit, the first resistor
comprises a first terminal connected to a second terminal of the
second resistor and a second terminal connected to a second voltage
signal input terminal, and the operational amplifier circuit
further comprises a forward input terminal connected to a second
node and an inverse input terminal connected to the cathode signal
input terminal, wherein the second node is disposed in series
between the second resistor and the first resistor; and the first
node is disposed in series between the first transistor and the
second resistor.
5. The pixel circuit according to claim 4, wherein the pixel
compensation circuit further comprises a voltage stabilizing
capacitor; wherein the voltage stabilizing capacitor comprises a
first terminal connected to the first node and a second terminal
grounded.
6. The pixel circuit according to claim 4, wherein the drive
transistor further comprises an input terminal and a control
terminal; wherein the input terminal of the first transistor is
disposed in a same layer as the input terminal of the drive
transistor; the output terminal of the first transistor is disposed
in a same layer as the output terminal of the drive transistor; and
the control terminal of the first transistor is disposed in a same
layer as the control terminal of the drive transistor.
7. The pixel circuit according to claim 1, wherein the cathode
potential V.sub.com, the crossover voltage V.sub.oled of the
organic light-emitting element, the body potential V.sub.body, and
a breakdown voltage V.sub.breakdown of the drive transistor satisfy
that V.sub.com+V.sub.oled-V.sub.body<V.sub.breakdown.
8. A silicon-based display panel, comprising a plurality of pixel
circuits; wherein the plurality of pixel circuits comprise a
plurality of pixel drive circuits and pixel compensation circuits,
and one of the plurality of pixel drive circuits corresponds to a
respective one of the plurality of pixel circuits and one of the
pixel compensation circuits corresponds to one or more pixel
circuits; each of the plurality of pixel drive circuits comprises a
drive transistor and an organic light-emitting element, the drive
transistor comprises an output terminal and a body terminal,
wherein the output terminal is connected to an anode of the organic
light-emitting element, and a cathode of the organic light-emitting
element is connected to a cathode signal input terminal and
configured to receive a cathode potential inputted from the cathode
signal input terminal; the body terminal is connected to the pixel
compensation circuit at a first node, and a potential of the first
node is a body potential; and the cathode potential V.sub.com, a
crossover voltage V.sub.oled of the organic light-emitting element,
and the body potential V.sub.body satisfy that
V.sub.com+V.sub.oled>V.sub.body.
9. The silicon-based display panel according to claim 8, further
comprising a silicon substrate and an N-type potential well layer
disposed on one side of the silicon substrate, wherein the N-type
potential well layer comprises a first surface facing towards the
side of the silicon substrate and a second surface facing away from
the side of the silicon substrate, the first surface has a first
ion doping concentration N1, and the second surface has a second
ion doping concentration N2, and |N1-N2|/N1.ltoreq.10%; wherein the
plurality of pixel drive circuits are disposed in the N-type
potential well layer.
10. The silicon-based display panel according to claim 8, wherein
the plurality of pixel drive circuits are arranged in an array; and
the silicon-based display panel comprises a plurality of pixel
compensation circuits arranged in an array, wherein each of the
plurality of pixel compensation circuits corresponds to a
respective one of the plurality of pixel drive circuits; or the
silicon-based display panel comprises a plurality of pixel
compensation circuits arranged in a same column, wherein pixel
drive circuits in a same row correspond to a same pixel
compensation circuit; or the silicon-based display panel comprises
a plurality of pixel compensation circuits arranged in a same row,
wherein pixel drive circuits in a same column correspond to a same
pixel compensation circuit; or the silicon-based display panel
comprises one pixel compensation circuit, wherein the plurality of
pixel drive circuits arranged in the array correspond to the one
pixel compensation circuit.
11. The silicon-based display panel according to claim 10, further
comprising a display region and a non-display region surrounding
the display region; wherein the plurality of pixel drive circuits
are disposed in the display region; when each of the plurality of
pixel compensation circuits corresponds to a respective one of the
plurality of pixel drive circuits, the plurality of pixel
compensation circuits are disposed in the display region; or when
the pixel drive circuits in the same row correspond to the same
pixel compensation circuit, the pixel drive circuits in the same
column correspond to the same pixel compensation circuit, or the
plurality of pixel drive circuits arranged in the array correspond
to the one pixel compensation circuit, the at least one pixel
compensation circuit is disposed in the non-display region.
12. A display device, comprising a silicon-based display panel,
wherein the silicon-based display panel comprises a plurality of
pixel circuits; wherein the plurality of pixel circuits comprise a
plurality of pixel drive circuits and pixel compensation circuits,
and one of the plurality of pixel drive circuits corresponds to a
respective one of the plurality of pixel circuits and one of the
pixel compensation circuits corresponds to one or more pixel
circuits; each of the plurality of pixel drive circuits comprises a
drive transistor and an organic light-emitting element, the drive
transistor comprises an output terminal and a body terminal,
wherein the output terminal is connected to an anode of the organic
light-emitting element, and a cathode of the organic light-emitting
element is connected to a cathode signal input terminal and
configured to receive a cathode potential inputted from the cathode
signal input terminal; the body terminal is connected to the pixel
compensation circuit at a first node, and a potential of the first
node is a body potential; and the cathode potential V.sub.com, a
crossover voltage V.sub.oled of the organic light-emitting element,
and the body potential V.sub.body satisfy that
V.sub.com+V.sub.oled>V.sub.body.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
This application claims the priority to a Chinese patent
application No. CN 202010338999.6 filed at the CNIPA on Apr. 26,
2020, disclosure of which is incorporated herein by reference in
its entirety.
TECHNICAL FIELD
The present disclosure relates to the field of display technologies
and, in particular, to a pixel circuit, a silicon-based display
panel, and a display device.
BACKGROUND
In an existing pixel drive circuit, as a drive current for a load
gradually increases, a gain between an output and an input
approaches 1. With an increase of the gain, a small signal is
amplified to a greater degree. Therefore, a random offset caused by
individual differences of different drive circuits is significantly
amplified, resulting in poor uniformity and display mura of a
display panel.
SUMMARY
In view of this, embodiments of the present disclosure provide a
pixel circuit, a silicon-based display panel, and a display device,
to solve the technical problem in the related art of poor display
uniformity of a display panel due to individual differences of
drive circuits.
In a first aspect, the embodiments of the present disclosure
provide a pixel circuit. The pixel circuit includes a pixel drive
circuit and a pixel compensation circuit.
The pixel drive circuit includes a drive transistor and an organic
light-emitting element.
The drive transistor includes an output terminal and a body
terminal, where the output terminal is connected to an anode of the
organic light-emitting element, and a cathode of the organic
light-emitting element is connected to a cathode signal input
terminal and configured to receive a cathode potential inputted
from the cathode signal input terminal. The cathode potential is
fixed.
The body terminal is connected to the pixel compensation circuit at
a first node, and a potential of the first node is a body
potential.
The cathode potential V.sub.com, a crossover voltage V.sub.oled of
the organic light-emitting element, and the body potential
V.sub.body satisfy that V.sub.com+V.sub.oled>V.sub.body.
Optionally, the cathode potential is adjustable.
Optionally, the pixel compensation circuit includes an operational
amplifier circuit, a first transistor, a first resistor, and a
second resistor. Where the second resistor has adjustable
resistance.
The first transistor includes an input terminal connected to a
first voltage signal input terminal, an output terminal connected
to a first terminal of the second resistor, and a control terminal
connected to an output terminal of the operational amplifier
circuit, the first resistor includes a first terminal connected to
a second terminal of the second resistor and a second terminal
connected to a second voltage signal input terminal, and the
operational amplifier circuit further includes a forward input
terminal connected to a second node and an inverse input terminal
connected to the cathode signal input terminal, where the second
node is disposed in series between the second resistor and the
first resistor.
The first node is disposed in series between the first transistor
and the second resistor.
Optionally, the pixel compensation circuit further includes a
voltage stabilizing capacitor.
The voltage stabilizing capacitor includes a first terminal
connected to the first node and a second terminal grounded.
Optionally, the drive transistor further includes an input terminal
and a control terminal.
The input terminal of the first transistor is disposed in a same
layer as the input terminal of the drive transistor; the output
terminal of the first transistor is disposed in a same layer as the
output terminal of the drive transistor; and the control terminal
of the first transistor is disposed in a same layer as the control
terminal of the drive transistor.
Optionally, the cathode potential V.sub.com, the crossover voltage
V.sub.oled of the organic light-emitting element, the body
potential V.sub.body, and a breakdown voltage V.sub.breakdown of
the drive transistor satisfy that
V.sub.com+V.sub.oled-V.sub.body<V.sub.breakdown.
In a second aspect, the embodiments of the present disclosure
further provide a silicon-based display panel. The silicon-based
display panel includes a plurality of pixel circuits described in
the first aspect of the embodiments of the present disclosure.
The plurality of pixel circuits include a plurality of pixel drive
circuits and pixel compensation circuits, and one of the plurality
of pixel drive circuits corresponds to a respective one of the
plurality of pixel circuits and one of the pixel compensation
circuits corresponds to one or more pixel circuits.
Optionally, the silicon-based display panel further includes a
silicon substrate and an N-type potential well layer disposed on
one side of the silicon substrate, where the N-type potential well
layer includes a first surface facing towards the side of the
silicon substrate and a second surface facing away from the side of
the silicon substrate, the first surface has a first ion doping
concentration N1, and the second surface has a second ion doping
concentration N2, and |N1-N2|/N1.ltoreq.10%.
The plurality of pixel drive circuits are disposed in the N-type
potential well layer.
Optionally, the plurality of pixel drive circuits are arranged in
an array.
The silicon-based display panel includes a plurality of pixel
compensation circuits arranged in an array, where each of the
plurality of pixel compensation circuits corresponds to a
respective one of the plurality of pixel drive circuits; or the
silicon-based display panel includes a plurality of pixel
compensation circuits arranged in a same column, where pixel drive
circuits in a same row correspond to a same pixel compensation
circuit; or the silicon-based display panel includes a plurality of
pixel compensation circuits arranged in a same row, where pixel
drive circuits in a same column correspond to a same pixel
compensation circuit; or the silicon-based display panel includes
one pixel compensation circuit, where the plurality of pixel drive
circuits arranged in the array correspond to the one pixel
compensation circuit.
Optionally, the silicon-based display panel further includes a
display region and a non-display region surrounding the display
region.
The plurality of pixel drive circuits are disposed in the display
region.
When each of the plurality of pixel compensation circuits
corresponds to a respective one of the plurality of pixel drive
circuits, the plurality of pixel compensation circuits are disposed
in the display region.
When the pixel drive circuits in the same row correspond to the
same pixel compensation circuit, the pixel drive circuits in the
same column correspond to the same pixel compensation circuit, or
the plurality of pixel drive circuits arranged in the array
correspond to the one pixel compensation circuit, the at least one
pixel compensation circuit is disposed in the non-display
region.
In a third aspect, the embodiments of the present disclosure
further provide a display device. The display device includes the
silicon-based display panel described in the second aspect of the
embodiments of the present disclosure.
In the pixel circuit, the silicon-based display panel, and the
display device provided by the embodiments of the present
disclosure, the pixel circuit includes the pixel drive circuit and
the pixel compensation circuit, where the output terminal of the
drive transistor is connected to the anode of the organic
light-emitting element, the cathode of the organic light-emitting
element receives the fixed cathode potential, and the body terminal
of the drive transistor is connected to the pixel compensation
circuit at the first node. The potential of the first node is
reasonably set, so as to ensure that a sum of the cathode potential
and the crossover voltage of the organic light-emitting element,
that is, the voltage of the output terminal of the drive
transistor, is greater than the body potential. This is different
from the solution in the related art in which the voltage of the
output terminal is the same as the body potential and ensures that
the source-substrate voltage potential of the drive transistor can
be increased so that the voltage corresponding to the body effect
of the drive transistor is increased, the threshold voltage of the
drive transistor is increased, the proportion of the random offset
caused by the individual differences of drive circuits in the
threshold voltage is decreased, the effect of the random offset on
a drive current is reduced, and the uniformity of a display effect
is improved.
BRIEF DESCRIPTION OF DRAWINGS
Other features, objects, and advantages of the present disclosure
will become more apparent from a detailed description of
non-restrictive embodiments with reference to the drawings
described below.
FIG. 1 shows a structure diagram of a pixel drive circuit in the
related art.
FIG. 2 is a diagram showing a correspondence between a gain and a
drive current of a pixel drive circuit.
FIG. 3 is a diagram showing a correspondence between a current
change due to a random offset and a drive current of a pixel drive
circuit.
FIG. 4 is a diagram showing a correspondence between a current
change due to a random offset and a body potential of a pixel drive
circuit.
FIG. 5 shows a structure diagram of a pixel drive circuit according
to embodiments of the present disclosure.
FIG. 6 is a diagram showing an equivalent small signal film of a
pixel drive circuit according to embodiments of the present
disclosure.
FIG. 7 shows a structure diagram of a pixel circuit according to
embodiments of the present disclosure.
FIG. 8 shows a structure diagram of a silicon-based display panel
according to embodiments of the present disclosure.
FIG. 9 shows a structure diagram of another silicon-based display
panel according to embodiments of the present disclosure.
FIG. 10 shows a structure diagram of another silicon-based display
panel according to embodiments of the present disclosure.
FIG. 11 shows a structure diagram of another silicon-based display
panel according to embodiments of the present disclosure.
DETAILED DESCRIPTION
To make the objects, technical solutions, and advantages of the
present disclosure clearer, the technical solutions of the present
disclosure will be described completely below in conjunction with
the drawings in the embodiments of the present disclosure and
specific implementations. Apparently, the embodiments described
herein are part, not all, of the embodiments of the present
disclosure. Based on the embodiments of the present disclosure, all
other embodiments obtained by those of ordinary skill in the art on
the premise that no creative work is done are within the scope of
the present disclosure.
Before a detailed description of the solutions in the embodiments
of the present disclosure, the principles of the embodiments of the
present disclosure are described.
FIG. 1 shows a structure diagram of a pixel drive circuit in the
related art. FIG. 2 is a diagram showing a correspondence between a
gain and a drive current of a pixel drive circuit. FIG. 3 is a
diagram showing a correspondence between a current change due to a
random offset and a drive current of a pixel drive circuit. As
shown in FIG. 1, in the related art, a source follower circuit is
applied to the pixel drive circuit as a voltage buffer, and a
signal is received through a gate (G) for a source (S) to drive a
load (an organic light-emitting element). Source potential energy
"follows" a gate voltage, thereby providing a stable drive voltage
for the load.
In the pixel drive circuit shown in FIG. 1, a gain A.sub.V, channel
transconductance g.sub.m, and a threshold voltage V.sub.TH of the
pixel drive circuit are expressed by the following formulas:
.differential..differential..mu..times..times..times..times..times..times-
..+-..DELTA..times..times..gamma..function..times..PHI..times..PHI.
##EQU00001##
where g.sub.m denotes the channel transconductance, g.sub.mb
denotes the transconductance of a body effect (as shown in FIG. 6,
an equivalent small signal model of a pixel circuit), I.sub.D
denotes a drive current, V.sub.GS denotes a gate-source voltage
difference of a drive transistor, V.sub.TH denotes the threshold
voltage, .mu. denotes the carrier mobility of the pixel drive
circuit, C.sub.OX denotes the capacitance of a gate oxide layer in
a unit area of the pixel drive circuit, W and L denote a channel
width and a channel length of the pixel drive circuit,
respectively, V.sub.THO denotes an intrinsic threshold voltage,
.DELTA.V denotes the random offset of the pixel drive circuit,
which exists in the threshold voltage, .gamma. denotes a
coefficient of the body effect, and .phi..sub.F denotes a flat-band
barrier. .phi..sub.F=(.kappa.T/q)In(N.sub.sub/n.sub.i), where K
denotes a Boltzmann constant, T denotes an absolute temperature, q
denotes electron charges, N.sub.sub denotes a substrate
concentration, n.sub.i denotes an intrinsic doping concentration,
and |V.sub.SB| denotes a source-substrate voltage potential.
As can be seen from formulas (1) and (2), as the drive current
I.sub.D gradually increases, g.sub.m is multiplied, and when
g.sub.m approaches infinity, the gain approaches 1, as shown in
FIG. 2. The larger the gain, the stronger the capability to amplify
a small signal. Therefore, the random offset generated at an input
terminal and caused by individual differences of pixel drive
circuits is significantly amplified with an increase of g.sub.m,
that is, the random offset of the pixel drive circuit has a greater
effect. As shown in FIG. 3, the larger the current, the greater the
random offset of the pixel drive circuit.
To conclude, in the pixel drive circuit using the source follower
circuit, the larger gain the pixel drive circuit has, the greater
effect the random error has; moreover, the random offset is
irrelevant to a frequency and has a relatively great effect within
any frequency range. A pixel circuit operating within a
low-frequency range is also affected. Therefore, the random offset
of the pixel drive circuit is one of main reasons for poor display
uniformity.
In a silicon-based organic light-emitting display apparatus, the
effect of the random offset can be reduced by decreasing the
current. However, the display apparatus cannot only operate at low
gray scales, and the current display apparatus has increasingly
high requirements on brightness. Thus, the applications of
conventional voltage drive circuits are greatly limited.
To solve the above-mentioned technical problem, the inventive
concept of the embodiments of the present disclosure is proposed,
in which the effect of the random offset on pixel display is
effectively reduced without decreasing the drive current. The
inventive concept of the embodiments of the present disclosure is
described in detail below.
As the drive current is decreased, the gain is reduced, so that the
random offset .DELTA.V is amplified less greatly, thereby reducing
the effect of the random offset. Then, an input voltage is
appropriately increased according to a correspondence between an
input and an output to compensate for the drive current.
Specifically, as can be seen from formula (3), the threshold
voltage of the pixel drive circuit is relevant to the intrinsic
threshold voltage, the random offset due to the input, and the body
effect of the pixel drive circuit, and the random offset due to the
input is directly embodied in the threshold voltage of the pixel
drive circuit. To reduce the effect of .DELTA.V on V.sub.TH, the
body effect of the pixel drive circuit can be artificially
increased, thereby reducing the effect of the random offset due to
the input on the threshold voltage.
Further, the drive current of the organic light-emitting element
and the input and the output of the pixel drive circuit satisfy the
following requirements:
.beta..times..times..beta..times..times..times..times..+-..DELTA..times..-
times..gamma..function..times..PHI..times..PHI..times..+-..DELTA..times..t-
imes. ##EQU00002##
The drive current of the organic light-emitting element is
expressed by formula (4). Formula (5) is obtained with formula (3)
being substituted into formula (4). It can be seen from formula (5)
that as the body effect increases, a squared term in the drive
current decreases correspondingly and that the drive current V
decreases by a squared multiple with an increase of |V.sub.SB|.
Therefore, |V.sub.SB| provides negative feedback for the drive
current, that is, with an increase of |V.sub.SB|, the drive current
decreases, the gain decreases, and the effect of the random offset
is reduced. FIG. 4 is a diagram showing a correspondence between a
current change due to a random offset and a body potential of a
pixel drive circuit. FIG. 5 shows a structure diagram of a pixel
drive circuit according to embodiments of the present disclosure.
FIG. 4 shows the effect of the body effect on the random offset,
where curve 1 shows the effect of the random offset in the
conventional pixel drive circuit and curve 2 shows the effect of
the random offset in the pixel circuit with new architecture shown
in FIG. 5. As can be seen from FIG. 4, the effect of the random
offset on the current of the conventional pixel drive circuit
exceeds 5%. To prevent gray scale transition, the lowest
requirement in optical display is a current difference not higher
than 2.5%. Therefore, the conventional pixel drive circuit cannot
satisfy this requirement, resulting in serious display mura. In the
pixel drive circuit shown in FIG. 5, a body potential and a source
voltage in the pixel drive circuit are configured to be different
and |V.sub.SB| is continuously increased, so as to ensure that the
body effect continuously increases and V.sub.TH is reduced so that
the random offset has an increasingly small effect on the current.
As can be seen from curve 2 in FIG. 4, the effect on the current is
not higher than 2.5%, which perfectly satisfies the optical
requirement.
Further, the current decreases with an increase of the body effect
and formula (1) is rewritten as formula (6). Since g.sub.n
decreases with an increase of the body effect, the coefficient
term
< ##EQU00003## and .DELTA.V is infinitely weakened, further
verifying that the random offset is suppressed. Meanwhile, the
input voltage V.sub.gamma is also weakened with
##EQU00004## To ensure that the display apparatus is still applied
within a high-brightness range, the input voltage may be increased,
and the written voltage V.sub.IN may be configured to be
.times. ##EQU00005## Thus, formula (6) is rewritten as formula
(7):
.times..+-..DELTA..times..times..times..+-..times..DELTA..times..times..a-
pprxeq. ##EQU00006##
As can be seen from formula (7), the pixel drive circuit shown in
FIG. 5 copies the input voltage to the output, that is, the voltage
for driving the organic light-emitting element is stable and
controllable.
Therefore, the pixel drive circuit shown in FIG. 5, provided by the
embodiments of the present disclosure, effectively reduces the
effect of the random offset on the display while ensuring constant
brightness, significantly alleviating the display mura and ensuring
good display uniformity.
The basic inventive concept of the embodiments of the present
disclosure is described in detail above. Based on the basic
inventive concept described above, the technical solutions of the
embodiments of the present disclosure are described in detail
below.
FIG. 7 shows a structure diagram of a pixel circuit according to
embodiments of the present disclosure. As shown in FIG. 7, the
pixel circuit 10 according to the embodiments of the present
disclosure includes a pixel drive circuit 11 and a pixel
compensation circuit 12; where the pixel drive circuit 11 includes
a drive transistor 111 and an organic light-emitting element 112;
the drive transistor 111 includes an output terminal 1111 and a
body terminal 1112, where the output terminal 1111 is connected to
an anode 1121 of the organic light-emitting element 112, and a
cathode 1122 of the organic light-emitting element 112 is connected
to a cathode signal input terminal 21 and configured to receive a
cathode potential inputted from the cathode signal input terminal
21. The cathode potential is fixed; the body terminal 1112 is
connected to the pixel compensation circuit 12 at a first node N1,
and a potential of the first node N1 is a body potential; and the
cathode potential V.sub.com, a crossover voltage V.sub.oled of the
organic light-emitting element, and the body potential V.sub.body
satisfy that V.sub.com+V.sub.oled>V.sub.body.
Exemplarily, as shown in FIG. 7, the embodiments of the present
disclosure provide the pixel circuit 10 including the pixel drive
circuit 11 and the pixel compensation circuit 12, where the pixel
drive circuit 11 further includes the drive transistor 111 and the
organic light-emitting element 112, the drive transistor 111 may be
a metal-oxide-semiconductor field-effect transistor (MOSFET), and
the output terminal 1111 (that is, a source terminal) and the body
terminal 1112 of the drive transistor 111 are provided with
different voltages, respectively. In this manner, the
source-substrate voltage potential of the drive transistor 111 is
not equal to 0 so that the voltage corresponding to the body effect
of the drive transistor 111 can be increased, the threshold voltage
of the drive transistor 111 is further increased, the proportion of
the voltage corresponding to the body effect in the threshold
voltage of the drive transistor 111 is increased, the proportion of
the voltage corresponding to the random offset of the drive
transistor 111 in the threshold voltage of the drive transistor 111
is decreased, the gain of the drive transistor 111 is decreased,
the effect of the random offset on the display mura is reduced, and
the display uniformity is improved.
Specifically, the output terminal 1111 (that is, the source
terminal) and the body terminal 1112 are provided with different
voltages, respectively, which may be set in a manner described
below. The output terminal 1111 is connected to the anode 1121 of
the organic light-emitting element 112, and the cathode 1122 of the
organic light-emitting element 112 is connected to the cathode
signal input terminal 21 and configured to receive a fixed voltage
signal Vann inputted from the cathode signal input terminal 21.
Considering the crossover voltage V.sub.oled of the organic
light-emitting element, it is known that the voltage of the output
terminal 1111 (that is, the source terminal) is
V.sub.com+V.sub.oled. Further, the body terminal 1112 is connected
to the pixel compensation circuit 12 at the first node N1, the
potential of the first node N1 is the body potential V.sub.body,
and the cathode potential Vann, the crossover voltage V.sub.oled of
the organic light-emitting element and the body potential
V.sub.body are configured to satisfy that
V.sub.com+V.sub.oled>V.sub.body. On the one hand, it is ensured
that the source voltage and the body potential of the drive
transistor 111 are different and the voltage corresponding to the
body effect of the drive transistor 111 can be increased. On the
other hand, it is ensured that the body potential V.sub.body is not
too high, avoiding the problem in which a backflow current is
formed between the body terminal and the source terminal since the
body potential is higher than the source voltage, resulting in an
uncontrollable drive current of the organic light-emitting element
112.
To conclude, the pixel circuit provided by the embodiments of the
present disclosure includes the pixel drive circuit and the pixel
compensation circuit, where the output terminal of the pixel drive
circuit is connected to the cathode signal input terminal through
the organic light-emitting element to receive the fixed cathode
potential inputted from the cathode signal input terminal, and the
body terminal is connected to the pixel compensation circuit at the
first node. The potential of the first node is reasonably set, so
as to ensure that a sum of the cathode potential and the crossover
voltage of the organic light-emitting element, that is, the voltage
of the output terminal of the drive transistor, is greater than the
body potential. This is different from the solution in the related
art in which the voltage of the output terminal is the same as the
body potential and ensures that the source-substrate voltage
potential of the drive transistor can be increased so that the
voltage corresponding to the body effect of the drive transistor is
increased, the threshold voltage of the drive transistor is
increased, the proportion of the random offset caused by the
individual differences of drive circuits in the threshold voltage
is decreased, the effect of the random offset on the drive current
is reduced, and the uniformity of a display effect is improved.
Based on the preceding embodiments, the cathode potential Vann is
adjustable.
Exemplarily, the entire silicon-based display panel includes a
plurality of pixel drive circuits 11. To ensure that the pixel
circuit 10 provided by the embodiments of the present disclosure is
applicable to various pixel drive circuits 11 with different random
offsets, the cathode potential \icon, may be configured to be
adjustable, that is, the cathode potential \icon, received by the
cathode 1122 of the organic light-emitting element 112 is
configured to be adjustable. That is, the source voltage of the
drive transistor 111 is adjustable. Thus, for the pixel drive
circuits 11 with different random offsets, the body effects of
different pixel drive circuits 11 are different and the threshold
voltages of the drive transistors 111 are decreased to different
degrees, ensuring the display uniformity of the entire
silicon-based display panel and avoiding the display mura.
Further, in the case where the cathode potential \icon, is
adjustable, the body potential is also adjustable within a small
range, that is, the voltage at the node (the first node N1) at
which the body terminal 1112 of the drive transistor 111 is
connected to the pixel compensation circuit 12 is adjustable, so as
to ensure that the compensation voltage provided by the pixel
compensation circuit 12 is applicable to the various pixel drive
circuits 11 in the entire silicon-based display panel, ensure the
display uniformity of the entire silicon-based display panel, and
avoid the display mura.
How to implement the adjustable body potential V.sub.body through
the adjustable cathode potential V.sub.com is described in detail
below.
Specifically, with continued reference to FIG. 7, the pixel
compensation circuit 12 includes an operational amplifier circuit
121, a first transistor 122, a first resistor R1, and a second
resistor R2. The second resistor R2 has adjustable resistance, the
first transistor 122 has an input terminal connected to a first
voltage signal input terminal, an output terminal connected to a
first terminal of the second resistor R2, and a control terminal
connected to an output terminal of the operational amplifier
circuit 121. The first resistor R1 has a first terminal connected
to a second terminal of the second resistor R2 and a second
terminal connected to a second voltage signal input terminal, and
the operational amplifier circuit 121 further has a forward input
terminal connected to a second node N2 and an inverse input
terminal connected to the cathode signal input terminal 21. Where
the second node N2 is disposed in series between the second
resistor R2 and the first resistor R1, and the first node N1 is
disposed in series between the first transistor 122 and the second
resistor R2.
Exemplarily, as shown in FIG. 7, in the embodiments of the present
disclosure, the pixel compensation circuit 12 includes the second
resistor R2, the first node N1 is disposed in series between the
second resistor R2 and the first transistor 122, and the second
resistor R2 has adjustable resistance so that it is ensured that
the potential of the first node N1 is adjustable, that is, the body
potential V.sub.body is adjustable. Further, the inverse input
terminal of the operational amplifier circuit 121 is connected to
the cathode signal input terminal 21 so that V.sub.com is used as a
reference voltage for the voltage V.sub.body to be generated
between a voltage VSS at the first voltage signal input terminal
and a voltage AVEE at the second voltage signal input terminal,
such that a voltage difference is generated between V.sub.body and
V.sub.com. That is, the source-substrate voltage potential of each
drive transistor is increased, the voltage corresponding to the
body effect of the drive transistor is increased, the threshold
voltage of the drive transistor is increased, the proportion of the
random offset caused by the individual differences of drive
circuits in the threshold voltage is decreased, the effect of the
random offset on the drive current is reduced, and the uniformity
of the display effect is improved.
As shown in formula (8), the cathode potential V.sub.com is
adjustable and the resistance of the variable resistor R2 may be
further adjusted so that the magnitude of the body potential
V.sub.body can be changed, thereby selecting an appropriate value
of (V.sub.com-V.sub.body).
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magnitude of V.sub.body may be changed by adjusting the resistance
of the variable resistor R2, so as to select the appropriate value
of (V.sub.com-V.sub.body). After V.sub.com is determined, the
voltage Vsource may be determined and V.sub.body changes with
V.sub.com so that the corresponding source-substrate voltage of
each drive transistor is fixed, and the decreased threshold voltage
of the drive transistor 111 can be obtained, thereby suppressing
the random offset. Then, the input voltage Vgamma of the drive
transistor 111 is changed for brightness adjustment, thereby
achieving high-brightness display.
To conclude, according to the technical solutions provided by the
embodiments of the present disclosure, the cathode potential
V.sub.com is configured to be adjustable. For the pixel drive
circuits 11 with different random offsets, the body effects of the
different pixel drive circuits 11 are different and the threshold
voltages of the drive transistors 111 are decreased to different
degrees, ensuring the display uniformity of the entire
silicon-based display panel. Further, it is set that the pixel
compensation circuit includes the operational amplifier circuit
121, the first transistor 122, the first resistor R1, and the
second resistor R2, the second resistor R2 has adjustable
resistance, and the inverse input terminal of the operational
amplifier circuit 121 is connected to the cathode signal input
terminal 21, so that it is ensured that the pixel compensation
circuit can select an appropriate value of (V.sub.com-V.sub.body)
by simply adjusting the resistance of the second resistor R2
instead of adjusting V.sub.com and V.sub.body separately. The
compensation manner is simple. Meanwhile, the appropriate value of
(V.sub.com-V.sub.body) is selected so that the voltage
corresponding to the body effect can be appropriately increased and
the effect of the random offset of the drive transistor is
appropriately reduced. Therefore, the technical solutions provided
by the embodiments of the present disclosure can be better applied
to a display apparatus with the requirements for high brightness
and high uniformity.
Based on the preceding embodiments, the pixel compensation circuit
12 may further include a voltage stabilizing capacitor C; where the
voltage stabilizing capacitor C has a first terminal connected to
the first node N1 and a second terminal grounded. The voltage
stabilizing capacitor C is disposed, so as to ensure that the
cathode potential V.sub.com at the first node N1 is stable, the
voltage (V.sub.com-V.sub.body) is stable, and the voltage
corresponding to the body effect is stable, thereby ensuring the
stable compensation effect for the pixel drive circuit 11 and the
good and stable effect of improving the display mura.
Optionally, the drive transistor 111 may further include an input
terminal and a control terminal; where the input terminal of the
first transistor 122 is disposed in a same layer as the input
terminal of the drive transistor 111 (not shown in the figure); the
output terminal of the first transistor 122 is disposed in a same
layer as the output terminal of the drive transistor 111; and the
control terminal of the first transistor 122 is disposed in a same
layer as the control terminal of the drive transistor 111.
Exemplarily, the input terminal of the first transistor 122 is
disposed in the same layer as the input terminal of the drive
transistor 111, so as to ensure that the input terminal of the
first transistor 122 and the input terminal of the drive transistor
111 can be manufactured in the same process, thereby ensuring that
the pixel circuit is manufactured by a simple process on the basis
that the pixel circuit is ensured to have a simple film structure.
Similarly, the output terminal of the first transistor 122 is
disposed in the same layer as the output terminal of the drive
transistor 111, so as to ensure that the output terminal of the
first transistor 122 and the output terminal of the drive
transistor 111 can be manufactured in the same process, thereby
ensuring that the pixel circuit is manufactured by a simple process
on the basis that the pixel circuit is ensured to have a simple
film structure.
Similarly, the control terminal of the first transistor 122 is
disposed in the same layer as the control terminal of the drive
transistor 111, so as to ensure that the control terminal of the
first transistor 122 and the control terminal of the drive
transistor 111 can be manufactured in the same process, thereby
ensuring that the pixel circuit is manufactured by a simple process
on the basis that the pixel circuit is ensured to have a simple
film structure.
Optionally, the cathode potential V.sub.com, the crossover voltage
V.sub.oled of the organic light-emitting element, the body
potential V.sub.body, and a breakdown voltage V.sub.breakdown of
the drive transistor may also satisfy that
V.sub.com+V.sub.oled-V.sub.body<V.sub.breakdown, so as to avoid
that too low a body potential V.sub.body causes the drive
transistor 111 to be broken down since V.sub.BD exceeds an extreme
voltage and the display is abnormal. Therefore, it is set that
V.sub.com+V.sub.oled-V.sub.body<V.sub.breakdown to ensure that a
voltage difference between the source and body terminals of the
drive transistor is lower than the breakdown voltage of the drive
transistor, the drive transistor operates normally, the pixel
circuit operates normally, and the silicon-based display panel can
perform normal display.
Based on the same inventive concept, the embodiments of the present
disclosure further provide a silicon-based display panel including
a plurality of pixel circuits described in the preceding
embodiments of the present disclosure. The plurality of pixel
circuits include a plurality of pixel drive circuits and at least
one pixel compensation circuit, and each of the plurality of pixel
drive circuits corresponds to a respective one of the plurality of
pixel circuits.
Exemplarily, in the silicon-based display panel provided by the
embodiments of the present disclosure, the plurality of pixel
circuits may share the same pixel compensation circuit, thereby
ensuring a simple circuit arrangement. Alternatively, each pixel
circuit may correspond to one pixel compensation circuit, ensuring
that each pixel circuit is independently adjusted without affecting
other pixel circuits. Alternatively, part of the plurality of pixel
circuits may share the same pixel compensation circuit, ensuring
both the simple circuit arrangement and independent adjustment.
A plurality of arrangements are described below.
Optionally, the plurality of pixel drive circuits 11 are arranged
in an array; the silicon-based display panel 100 includes a
plurality of pixel compensation circuits 12 arranged in an array,
where each of the plurality of pixel compensation circuits 12
corresponds to a respective one of the plurality of pixel drive
circuits 11; or the silicon-based display panel 100 includes a
plurality of pixel compensation circuits 12 arranged in a same
column, where pixel drive circuits 11 in a same row correspond to a
same pixel compensation circuit 12; or the silicon-based display
panel 100 includes a plurality of pixel compensation circuits 12
arranged in a same row, where pixel drive circuits 11 in a same
column correspond to a same pixel compensation circuit 12; or the
silicon-based display panel 100 includes one pixel compensation
circuit 12, where the plurality of pixel drive circuits 11 arranged
in the array correspond to the one pixel compensation circuit
12.
Specifically, FIG. 8 is a structure diagram of a silicon-based
display panel according to the embodiments of the present
disclosure. FIG. 8 illustrates an example in which each pixel
compensation circuit 12 correspond to a respective one pixel drive
circuit 11. FIG. 9 is a structure diagram of another silicon-based
display panel according to the embodiments of the present
disclosure. FIG. 9 illustrates an example in which the pixel drive
circuits 11 in the same row correspond to the same pixel
compensation circuit 12. FIG. 10 is a structure diagram of another
silicon-based display panel according to the embodiments of the
present disclosure. FIG. 10 illustrates an example in which the
pixel drive circuits 11 in the same column correspond to the same
pixel compensation circuit 12. FIG. 11 is a structure diagram of
another silicon-based display panel according to the embodiments of
the present disclosure. FIG. 11 illustrates an example in which the
plurality of pixel drive circuits 11 arranged in the array
correspond to the same pixel compensation circuit 12.
As shown in FIG. 8, the silicon-based display panel 100 includes
the plurality of pixel compensation circuits 12 arranged in the
array, and each pixel compensation circuit 12 corresponds to its
respective one pixel drive circuit 11 and configured to provide a
body potential V.sub.body for the pixel drive circuit 11
electrically connected to the pixel compensation circuit 12,
thereby ensuring the high positioning accuracy of the body
potential V.sub.body and the accurate compensation for the random
offset of each drive transistor. As shown in FIG. 9, the
silicon-based display panel 100 includes the plurality of pixel
compensation circuits 12 arranged in the same column, and the pixel
drive circuits 11 in the same row correspond to the same pixel
compensation circuit 12. In this manner, each pixel compensation
circuit 12 is configured to compensate for the pixel drive circuits
11 in the same row, thereby compensating for the random offset of
each drive transistor with relatively high accuracy and arranging
the pixel compensation circuits 12 in a simple manner. As shown in
FIG. 10, the silicon-based display panel 100 includes the plurality
of pixel compensation circuits 12 arranged in the same row, and the
pixel drive circuits 11 in the same column correspond to the same
pixel compensation circuit 12. In this manner, each pixel
compensation circuit 12 is configured to compensate for the pixel
drive circuits 11 in the same column, thereby compensating for the
random offset of each drive transistor with relatively high
accuracy and arranging the pixel compensation circuits 12 in a
simple manner. As shown in FIG. 11, the silicon-based display panel
100 includes one pixel compensation circuit 12, and the plurality
of pixel drive circuits 11 arranged in the array correspond to the
same pixel compensation circuit 12. In this manner, the pixel
compensation circuit 12 is configured to compensate for all the
pixel drive circuits 11 in the entire silicon-based display panel
100 and arranged in a simple manner.
Further, with continued reference to FIGS. 8 to 11, the
silicon-based display panel 100 may further include a display
region AA and a non-display region NAA surrounding the display
region AA, where the plurality of pixel drive circuits 11 are
disposed in the display region AA. When each of the plurality of
pixel compensation circuits 12 corresponds to a respective one of
the plurality of pixel drive circuits 11, the plurality of pixel
compensation circuits 12 are disposed in the display region, as
shown in FIG. 8; or when the pixel drive circuits 11 in the same
row correspond to the same pixel compensation circuit 12, the pixel
drive circuits 11 in the same column correspond to the same pixel
compensation circuit 12, or the plurality of pixel drive circuits
11 arranged in the array correspond to the same pixel compensation
circuit 12, the at least one pixel compensation circuit is disposed
in the non-display region, as shown in FIGS. 9, 10 and 11. The
specific correspondence between the pixel drive circuits 11 and the
at least one pixel compensation circuit 12 is not limited in the
embodiment of the present disclosure and can be comprehensively
considered according to the requirement on compensation accuracy
and the difficulty in arranging the pixel compensation circuit 12,
and the specific position of the pixel compensation circuit 12 is
not limited.
Optionally, the silicon-based display panel provided by the
embodiments of the present disclosure further includes a silicon
substrate and an N-type potential well layer (not shown in the
figures) disposed on one side of the silicon substrate. The N-type
potential well layer in the embodiments of the present disclosure
may be a deep N-type potential well layer. The deep N-type
potential well layer includes a first surface facing towards the
side of the silicon substrate and a second surface facing away from
the side of the silicon substrate, the first surface has a first
ion doping concentration N1, and the second surface has a second
ion doping concentration N2, where |N1-N2|/N1.ltoreq.10%. The
plurality of pixel drive circuits are disposed in the deep N-type
potential well layer.
Exemplarily, the drive transistor provided by the embodiments of
the present disclosure may be an N-type metal-oxide-semiconductor
(NMOS) transistor. In the related art, each NMOS transistor is
disposed in an independent N-type potential well and a distance
between adjacent two independent N-type potential wells is greater
than 6 .mu.m in an existing 0.11 .mu.m CMOS process. Thus, a single
pixel drive circuit occupies a very large area and cannot be
applied to a high-resolution display apparatus. In the embodiments
of the present disclosure, the plurality of pixel drive circuits in
the entire silicon-based display panel are arranged in the same
deep N-type potential well layer so that the area occupied by each
pixel drive circuit can be greatly reduced, the integration degree
of the pixel drive circuits in the entire silicon-based display
panel can be improved, and the high-resolution silicon-based
display panel can be achieved. Further, the deep N-type potential
well layer provided by the embodiments of the present disclosure
includes the first surface facing towards the side of the silicon
substrate and the second surface facing away from the side of the
silicon substrate (not shown in the figures), the first surface has
the first ion doping concentration N1, and the second surface has
the second ion doping concentration N2, where
|N1-N2|/N1.ltoreq.10%. Since the ion implantation of the deep
N-type potential well layer is implemented from one surface of the
potential well layer, the first ion doping concentration N1 of the
first surface and the second ion doping concentration N2 of the
second surface satisfy that |N1-N2|/N1.ltoreq.10%, thereby ensuring
the uniformity in the ion implantation concentration of the entire
deep N-type potential well layer and a good isolation and
protection effect on the drive transistor.
Based on the same inventive concept, the embodiments of the present
disclosure further provide a display device including the
silicon-based display panel according to any one of the embodiments
of the present disclosure. The display device provided by the
embodiments of the present disclosure may be an augmented reality
(AR) display apparatus or a virtual reality (VR) display apparatus
or another display device with a small size and a high integration
degree. The type of the display device is not limited in the
embodiments of the present disclosure.
It is to be noted that the above are merely preferred embodiments
of the present disclosure and the principles used therein. It is
understood by those skilled in the art that the present disclosure
is not limited to the embodiments described herein and that the
features in the various embodiments of the present disclosure may
be coupled or combined in part or in whole with each other and may
be collaborated with each other and technically driven in various
manners. Those skilled in the art can make various apparent
modifications, adaptations, combinations, and substitutions without
departing from the scope of the present disclosure. Therefore,
while the present disclosure has been described in detail through
the above-mentioned embodiments, the present disclosure is not
limited to the above-mentioned embodiments and may include more
other equivalent embodiments without departing from the concept of
the present disclosure. The scope of the present disclosure is
determined by the scope of the appended claims.
* * * * *