U.S. patent application number 16/651853 was filed with the patent office on 2021-12-30 for display panel and display device.
The applicant listed for this patent is WUHAN CHINA STAR OPTOELECTRONICS TECHNOLOGY CO.,LTD.. Invention is credited to Yong YANG, Guowei ZHA, Guiyang ZHANG.
Application Number | 20210405423 16/651853 |
Document ID | / |
Family ID | 1000005894336 |
Filed Date | 2021-12-30 |
United States Patent
Application |
20210405423 |
Kind Code |
A1 |
YANG; Yong ; et al. |
December 30, 2021 |
DISPLAY PANEL AND DISPLAY DEVICE
Abstract
A display panel and a display device are provided. The display
panel includes a backlight module, a light-control liquid crystal
cell, a collimating film layer, and a display liquid crystal cell
stacked from bottom to top. The collimating film layer is
configured to limit transmission of scattered light beams with
large angle. The display device includes the abovementioned display
panel.
Inventors: |
YANG; Yong; (Wuhan, Hubei,
CN) ; ZHA; Guowei; (Wuhan, Hubei, CN) ; ZHANG;
Guiyang; (Wuhan, Hubei, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
WUHAN CHINA STAR OPTOELECTRONICS TECHNOLOGY CO.,LTD. |
Wuhan, Hubei |
|
CN |
|
|
Family ID: |
1000005894336 |
Appl. No.: |
16/651853 |
Filed: |
November 12, 2019 |
PCT Filed: |
November 12, 2019 |
PCT NO: |
PCT/CN2019/117471 |
371 Date: |
March 27, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02F 1/13476 20130101;
G02F 1/133562 20210101; G02F 1/13345 20210101; G02F 1/133567
20210101 |
International
Class: |
G02F 1/1347 20060101
G02F001/1347; G02F 1/1334 20060101 G02F001/1334; G02F 1/1335
20060101 G02F001/1335 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 10, 2019 |
CN |
201910852973.0 |
Claims
1. A display panel, comprising: a backlight module; a light-control
liquid crystal cell disposed on the backlight module; a collimating
film layer disposed on the light-control liquid crystal cell, and
configured to limit transmission of scattered light beams with
large angle; and a display liquid crystal cell disposed on the
collimating film layer; wherein the light-control liquid crystal
cell comprises a light-control upper substrate, a light-control
lower substrate, and a polymer dispersed liquid crystal layer
disposed between the light-control upper substrate and the
light-control lower substrate; and wherein the display liquid
crystal cell comprises a display upper substrate, a display lower
substrate, and a liquid crystal layer disposed between the display
upper substrate and the display lower substrate.
2. The display panel according to claim 1, further comprising: a
lower polarizer disposed under the display liquid crystal cell; and
an upper polarizer disposed on the display liquid crystal cell.
3. The display panel according to claim 1, further comprising: a
cover disposed on the display liquid crystal cell.
4. The display panel according to claim 1, wherein the collimating
film layer is a film layer with alternately stacked silicon nitride
and silicon oxide.
5. The display panel according to claim 1, wherein a number of film
layers of the collimating film layer ranges from 10 layers to 50
layers.
6. The display panel according to claim 1, wherein a thickness of
the collimating film layer ranges from 100 nm to 1000 nm.
7. The display panel according to claim 1, wherein the backlight
module comprises one of a blue-light backlight plate, a
side-emitting backlight module, or a mini-LED backlight module.
8. The display panel according to claim 1, wherein a material of
the liquid crystal layer comprises thermotropic liquid crystal or
lyotropic liquid crystal, and a material of the liquid crystal
comprises biphenyl liquid crystal, phenylcyclohexane liquid crystal
or ester liquid crystal.
9. The display panel according to claim 1, wherein a material of
the polymer dispersed liquid crystal layer comprises a scattering
liquid crystal, and the scattering liquid crystal comprises a
plurality of liquid crystal molecules and a network polymer.
10. A display device comprising the display panel according to
claim 1.
Description
FIELD
[0001] The present disclosure relates to display technologies, and
more particularly, to a display panel and a display device.
BACKGROUND
[0002] Liquid crystal display (LCD) technologies have been
available for many years. Compared with the emerging organic light
emitting diode (OLED) display technologies, LCD has a disadvantage
in display contrast. In order to make up for this shortcoming, a
sub-millimeter light-emitting diode (Mini-LED) backlight technology
developed in recent years can achieve a dynamic high-contrast
display through partitioned backlight control to compete with a
contrast ratio of the OLED display technology, and can achieve high
brightness, which is favored by people. However, because Mini-LED
lamp board technologies use chip arrays mounted on FPC/PCB, and
most of them also use whole-face packaging. The cost of materials
such as substrates, chips, packaging adhesives, and membranes has
led to higher production costs for the Mini-LEDs. A current market
acceptance is not high.
[0003] As shown in FIG. 1, for a display with a low thickness
requirement, a dual-cell thick liquid crystal display technology
may be adopted. One layer of the liquid crystal cell is a
light-control liquid crystal cell 91, and the other layer of the
liquid crystal cell is a display liquid crystal cell 92. Among
them, light emitted by a backlight module 90 (indicated by an arrow
in FIG. 2) passes through the light-control liquid crystal cell 91
and the display liquid crystal cell 92 in sequence. Most of the
light-control liquid crystal cell 91 uses polymer dispersed liquid
crystal (PDLC), and the PDLC still has a high transmittance in a
dark state, which is not conducive to a control of light in the
dark state and is easy to leak light.
[0004] Therefore, how to improve light control characteristics of
the light-control liquid crystal cell in the dark state becomes the
key to improving the contrast of the dual-cell liquid crystal
display. Therefore, there is a need to solve the above issues.
SUMMARY
[0005] In view of the above, the present disclosure provides a
display panel and a display device to promote a transmission of a
light-control liquid crystal cell, to ensure a luminance in white
state of a duel-cell liquid crystal display device, and to realize
a high brightness and high contrast display by reduce light leakage
of a light-control liquid crystal cell in dark state.
[0006] In order to achieve above-mentioned object of the present
disclosure, one embodiment of the disclosure provides a display
panel including a backlight module, a light-control liquid crystal
cell, a collimating film layer, and a display liquid crystal cell
stacked from bottom to top. In detail, the light-control liquid
crystal cell is disposed on the backlight module. The collimating
film layer is disposed on the light-control liquid crystal cell,
and is configured to limit transmission of scattered light beams
with large angle. The display liquid crystal cell is disposed on
the collimating film layer. The light-control liquid crystal cell
includes a light-control upper substrate, a light-control lower
substrate, and a polymer dispersed liquid crystal layer disposed
between the light-control upper substrate and the light-control
lower substrate. The display liquid crystal cell includes a display
upper substrate, a display lower substrate, and a liquid crystal
layer disposed between the display upper substrate and the display
lower substrate.
[0007] In one embodiment of the disclosure, the display panel
further includes a lower polarizer disposed under the display
liquid crystal cell, and an upper polarizer disposed on the display
liquid crystal cell.
[0008] In one embodiment of the disclosure, the display panel
further includes a cover disposed on the display liquid crystal
cell.
[0009] In one embodiment of the disclosure, the collimating film
layer is a film layer with alternately stacked silicon nitride and
silicon oxide.
[0010] In one embodiment of the disclosure, a number of film layers
of the collimating film layer ranges from 10 layers to 50
layers.
[0011] In one embodiment of the disclosure, a thickness of the
collimating film layer ranges from 100 nm to 1000 nm.
[0012] In one embodiment of the disclosure, the backlight module
includes one of a blue-light backlight plate, a side-emitting
backlight module, or a mini-LED backlight module.
[0013] In one embodiment of the disclosure, a material of the
liquid crystal layer includes thermotropic liquid crystal or
lyotropic liquid crystal, and a material of the liquid crystal
includes biphenyl liquid crystal, phenylcyclohexane liquid crystal
or ester liquid crystal.
[0014] In one embodiment of the disclosure, a material of the
polymer dispersed liquid crystal layer includes a scattering liquid
crystal, and the scattering liquid crystal includes a plurality of
liquid crystal molecules and a network polymer.
[0015] Furthermore, another embodiment of the disclosure provides a
display device including the display panel abovementioned.
[0016] In comparison with prior art, the display panel and the
display device of the disclosure provides a dual-cell thick liquid
crystal display technology included a light-control liquid crystal
cell and a display liquid crystal cell to promote a transmission of
a light-control liquid crystal cell, to ensure a luminance in white
state of a duel-cell liquid crystal display device, and to realize
a high brightness and high contrast display by reduce light leakage
of a light-control liquid crystal cell in dark state. It
compensates a difference of contrast between LCD display
technologies and OLED display technologies and ensures an advantage
in cost of the LCD display technologies to the OLED display
technologies.
BRIEF DESCRIPTION OF DRAWINGS
[0017] FIG. 1 is a schematic view of a principle of light leakage
of a display device according to prior art.
[0018] FIG. 2 is a schematic view of a structure of a display
device according to an embodiment of the present disclosure.
[0019] FIG. 3 is a schematic view of light beams of a light-control
liquid crystal cell in a scattered state according to an embodiment
of the present disclosure.
[0020] FIG. 4 is a schematic view of light beams of a light-control
liquid crystal cell in a transparent state according to an
embodiment of the present disclosure.
[0021] FIG. 5 is a schematic view of a principle of a collimating
film layer configured to limit transmission of scattered light
beams with large angle according to an embodiment of the present
disclosure.
[0022] FIG. 6 is a schematic view of a comparison between contrast
according to an embodiment of the present disclosure and contrast
according to prior art.
[0023] Reference numbers of the present disclosure are as follows:
[0024] 10: backlight module, 20: light-control liquid crystal cell,
21: light-control upper substrate, 22: polymer dispersed liquid
crystal layer, 23: light-control lower substrate, 30: collimating
film layer, 40: display liquid crystal cell, 41: display upper
substrate, 42: liquid crystal layer, 43: display lower substrate,
44: lower polarizer, 45: upper polarizer, 50: cover, 100: display
panel.
DETAILED DESCRIPTION
[0025] The following description of the embodiments is provided by
reference to the drawings and illustrates the specific embodiments
of the present disclosure. Directional terms mentioned in the
present disclosure, such as "up," "down," "top," "bottom,"
"forward," "backward," "left," "right," "inside," "outside,"
"side," "peripheral," "central," "horizontal," "peripheral,"
"vertical," "longitudinal," "axial," "radial," "uppermost" or
"lowermost," etc., are merely indicated the direction of the
drawings. Therefore, the directional terms are used for
illustrating and understanding of the application rather than
limiting thereof.
[0026] Referring to FIG. 2, one embodiment of the disclosure
provides a display panel 100 including a backlight module 10, a
light-control liquid crystal cell 20, a collimating film layer 30,
and a display liquid crystal cell 40 stacked from bottom to top. In
detail, the light-control liquid crystal cell 20 is disposed on the
backlight module 10. The collimating film layer 30 is disposed on
the light-control liquid crystal cell 20, and is configured to
limit transmission of scattered light beams with large angle. The
display liquid crystal cell 40 is disposed on the collimating film
layer 30. The light-control liquid crystal cell 20 includes a
light-control upper substrate 21, a light-control lower substrate
23, and a polymer dispersed liquid crystal layer 22 disposed
between the light-control upper substrate 21 and the light-control
lower substrate 23. The display liquid crystal cell 40 includes a
display upper substrate 41, a display lower substrate 43, and a
liquid crystal layer 42 disposed between the display upper
substrate 41 and the display lower substrate 43.
[0027] Referring to FIGS. 1, 2, 3, and 4, FIG. 3 shows that the
display panel 100 includes the collimating film layer 30, and the
collimating film layer 30 is configured to limit transmission of
scattered light beams (as shown in arrows in the figure) with large
angle to improve light leakage when the light-control liquid
crystal cell 20 is at a scattered state. FIG. 4 is a schematic view
of light beams of a light-control liquid crystal cell 20 in a
transparent state. The light-control liquid crystal cell 20 has
high transmission and the collimating film layer 30 do not limit
light beams with small angle, so that the luminance of the display
panel 100 won't be affected seriously.
[0028] The light-control liquid crystal cell 20 and the collimating
film layer 30 jointly implement a light-control function. The
display mode of the light-control liquid crystal cell 20 is TN
mode. A pixel electrode and a common electrode are respectively
located on the light-control upper substrate 21 and on the
light-control lower substrate 23. In order to increase the
transmittance of the light-control liquid crystal cell 20, it is
preferable that the light-control upper substrate 21 has no color
film photoresist and black matrix photoresist, and no upper and
lower polarizer structures. The light-control lower substrate 23
can control the liquid crystal rotation of the polymer dispersed
liquid crystal layer 22 to switch between a high-fog scattered
state and a transparent state. A driving voltage of the
light-control liquid crystal cell 20 is .+-.(5V to 7V).
[0029] In one embodiment of the disclosure, the collimating film
layer 30 is a film layer with alternately stacked silicon nitride
and silicon oxide. The collimating film layer 30 includes a silicon
oxide layer 31 and a silicon nitride layer 32.
[0030] As shown in FIG. 5, the collimating film layer 30 is an
angle light-control film layer of multi-layer structure of the
silicon oxide layer 31 and the silicon nitride layer 32. Referring
to a light beam with a small angle such as a light ray B in FIG. 5,
a reflected light is refracted by two film layers to from a
reflected light 3 and a reflected light 4 on a surface. If the
phase difference between the reflected light 3 and the reflected
light 4 is a, a reflectance is 0 based on the principle of
destructive interference. In light energy conservation principle,
light is basically transmitted through the film layer, so
small-angle light can be transmitted. A light beam with a large
angle such as a light ray A in FIG. 5, will generate reflected
light 1 and reflected light 2, because an optical path difference
between the reflected light 1 and the reflected light 2 is
different from the reflected light 3 and the reflected light 4 and
does not satisfy destructive interference. If the reflected light
is reflected on the surface of the film layer, light of the light
ray A transmitted through the film layer is reduced. The optical
path difference is related to a thickness and refractive index of
the film layer. An appropriate designed film thickness can satisfy
that most of the light with large angle is reflected, and most of
the light with small angle can be emitted.
[0031] In one embodiment of the disclosure, a number of film layers
of the collimating film layer ranges from 10 layers to 50 layers.
In one embodiment of the disclosure, a thickness of the collimating
film layer ranges from 100 nm to 1000 nm. The collimating film
layer 30 can pass light in an angle range of 0.degree. to
40.degree. perpendicular to the plane where the collimating film
layer 30 is located, that is, the collimating film layer 30 can
pass light in an angle range within 40.degree..
[0032] As shown in the embodiment of FIG. 6, A BLU curve represents
a curve of the brightness of a polymer dispersed liquid crystal
layer (PDLC) of an existing display device as a function of angle
in a transparent state. A BLU+PDLC curve represents a curve of the
brightness of the light-control liquid crystal cell 20 as a
function of angle in the scattered state. Without the collimating
film layer 30, the average contrast ratio of full viewing angle can
be considered as a ratio between the area enclosed by the two
curves. Addition of the collimating film layer 30 extracts light
outside 40.degree., especially extracts light outside 30.degree.. A
removal proportion of the area of the BLU+PDLC curve is larger, and
the removal proportion of the area of the BLU curve is small. The
ratio of an area enclosed by the BLU curve to an area enclosed by
the BLU+PDLC curve will increase, and the average contrast ratio of
full viewing angle will increase.
[0033] In one embodiment of the disclosure, the liquid crystal
layer is a common liquid crystal. A material of the liquid crystal
layer 42 includes thermotropic liquid crystal or lyotropic liquid
crystal. A material of the liquid crystal includes biphenyl liquid
crystal, phenylcyclohexane liquid crystal or ester liquid crystal.
In one embodiment of the disclosure, a material of the polymer
dispersed liquid crystal layer 22 includes a scattering liquid
crystal, and the scattering liquid crystal includes a plurality of
liquid crystal molecules and a network polymer. It can switch
between transparent state and screen display state.
[0034] The liquid crystal layer 42, an ordinary liquid crystal,
undergoes rotation of liquid crystal molecules after a voltage is
applied to control light transmittance to achieve gray-scale
display. The polymer dispersed liquid crystal layer 22 adds certain
polymers with different refractive indices. The difference in
refractive index between the surface of the liquid crystal and the
network polymer is controlled by voltage, so that light is
transmitted or scattered on the surface of the two. A transparent
state or a scattered state can be achieved. In the transparent
state, light can be transmitted, and in the scattered state, light
can be scattered. It can be used for displaying images.
[0035] The detail work process of the polymer dispersed liquid
crystal layer 22 is as following: The liquid crystal and the
network polymer have the same anisotropic dielectric constant, and
both have a birefringence phenomenon. When an applied voltage is
higher than a threshold voltage, the liquid crystal molecules
rotate and their directions are aligned along a vertical direction,
which changes the anisotropy of the dielectric constant of the
liquid crystal. In the light vector direction, the refractive index
of the liquid crystal and the network polymer are equivalent. There
is no refractive index difference on the surface between the liquid
crystal and the network polymer, and light is not scattered here.
The light-control liquid crystal cell 20 is in the transparent
state. When no voltage is applied or the voltage is lower than the
threshold voltage, the liquid crystal molecules are aligned
horizontally, the refractive index of the liquid crystal and the
network polymer are greatly different in the light vector
direction, and light is scattered here. The light-control liquid
crystal cell 20 exhibits a scattered state.
[0036] A liquid crystal material of the polymer dispersed liquid
crystal layer 22 and a liquid crystal material of the liquid
crystal layer 42 is the same. Preferably, the polymer dispersed
liquid crystal layer 22 has a high polymer network content, and the
light-control liquid crystal cell 20 in the scattered state has
more scattered light at a large angle. The light leakage in the
dark state is more serious, and the light control effect is
limited. In the scattered state, the transmittance of the
light-control liquid crystal cell 20 is still more than 40%.
[0037] The collimating film layer 30 in this embodiment can
suppress scattered light at a large angle and pass light at a small
angle. The light-control effect is significantly improved, which
effectively reduces light leakage of the light-control liquid
crystal cell 20 in dark state. The transmittance of the
light-control liquid crystal cell 20 is improved to ensure a
luminance in white state of a duel-cell liquid crystal display
device, and to realize a high brightness and high contrast display
by reduce light leakage of a light-control liquid crystal cell in
dark state. It compensates a difference of contrast between LCD
display technologies and OLED display technologies and ensures an
advantage in cost of the LCD display technologies to the OLED
display technologies.
[0038] A cell thickness of the light-control liquid crystal cell 20
satisfies .DELTA.nd=.lamda./4, where .DELTA.n is the anisotropy of
the refractive index of the liquid crystal, d is the cell
thickness, .DELTA.nd is the optical path difference, .lamda. is a
wavelength, and .lamda. ranges from 380 nm to 780 nm. The .lamda.
value is preferably 500 nm, 550 nm, or 600 nm.
[0039] Continuing to refer to FIG. 2, in this embodiment, the
display panel 100 further includes: a lower polarizer 44 disposed
below the display liquid crystal cell 40 and an upper polarizer 45
disposed above the display liquid crystal cell 40. In detail, a
display mode of the display liquid crystal cell 40 is a TN mode, a
VA mode, or an IPS/FFS mode. The display upper substrate 41
includes a color film photoresist and a black matrix photoresist. A
driving voltage of the display liquid crystal cell 40 is .+-.(4V to
6V). Preferably, a green pixel and a red pixel of the color film
photoresist are made of a quantum dot color filter (QDCF) material.
A high color gamut display is realized when takes a blue light as
an excitation light.
[0040] The cell thickness of the light-control liquid crystal cell
20 satisfies .DELTA.nd=.lamda./4, where .DELTA.n is the anisotropy
of the refractive index of the liquid crystal, d is the cell
thickness, .DELTA.nd is the optical path difference, .lamda. is a
wavelength, and .lamda. ranges from 380 nm to 780 nm. The .lamda.
value is preferably 500 nm, 550 nm, or 600 nm.
[0041] In one embodiment of the disclosure, the display panel 100
further includes a cover 50 disposed on the display liquid crystal
cell 40 to protect the display panel 100.
[0042] In one embodiment of the disclosure, the backlight module 10
includes one of a blue-light backlight plate, a side-emitting
backlight module 10, or a mini-LED backlight module 10.
[0043] Furthermore, another embodiment of the disclosure provides a
display device including the display panel 100 abovementioned.
[0044] The display device of the present invention can be applied
to various occasions and can be combined with various devices and
structures. It can be a display panel or other equipment with a
display function, such as a tablet computer, a television, a
display window, and the like. It should be understood that, in
order to realize the function, the display device of the present
invention is provided with other devices, structures, etc., which
are not shown in this specification.
[0045] In comparison with prior art, the display panel and the
display device of the disclosure provides a dual-cell thick liquid
crystal display technology included a light-control liquid crystal
cell and a display liquid crystal cell to promote a transmission of
a light-control liquid crystal cell, to ensure a luminance in white
state of a duel-cell liquid crystal display device, and to realize
a high brightness and high contrast display by reduce light leakage
of a light-control liquid crystal cell in dark state. It
compensates a difference of contrast between LCD display
technologies and OLED display technologies and ensures an advantage
in cost of the LCD display technologies to the OLED display
technologies.
[0046] The present disclosure has been described by the above
embodiments, but the embodiments are merely examples for
implementing the present disclosure. It must be noted that the
embodiments do not limit the scope of the invention. In contrast,
modifications and equivalent arrangements are intended to be
included within the scope of the invention.
* * * * *