U.S. patent application number 17/464742 was filed with the patent office on 2022-04-14 for display device and image sensing method thereof.
The applicant listed for this patent is Guangzhou Tyrafos Semiconductor Technologies Co., Ltd.. Invention is credited to Jun-Wen CHUNG, Hsu-Wen Fu.
Application Number | 20220115443 17/464742 |
Document ID | / |
Family ID | |
Filed Date | 2022-04-14 |
United States Patent
Application |
20220115443 |
Kind Code |
A1 |
CHUNG; Jun-Wen ; et
al. |
April 14, 2022 |
DISPLAY DEVICE AND IMAGE SENSING METHOD THEREOF
Abstract
The invention relates to a display device, applicable to
fingerprint image recognition. The display device includes: a
substrate, a cover panel, and unit pixels. First, the unit pixels
on the display device emit light alternately. When a part of the
unit pixels emit light, defined as in a light-emitting state, and
when another part of the unit pixels do not emit light, defined as
in a sensing state; then, the unit pixels in the light-emitting
state are used as the light-emitting area; the unit pixels in the
sensing state are used as the sensing area; the unit pixels in the
light-emitting area emit incident light to and reflected by a test
object; the unit pixels in the sensing area sense the reflected
light, and generates an image electrical signal. Therefore, the
display device can be used as both a light-emitting element and a
sensing element for fingerprint image recognition.
Inventors: |
CHUNG; Jun-Wen; (Tainan
City, TW) ; Fu; Hsu-Wen; (Kaohsiung City,
TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Guangzhou Tyrafos Semiconductor Technologies Co., Ltd. |
Guangzhou |
|
CN |
|
|
Appl. No.: |
17/464742 |
Filed: |
September 2, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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63089055 |
Oct 8, 2020 |
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International
Class: |
H01L 27/28 20060101
H01L027/28; H04N 5/378 20060101 H04N005/378; G06K 9/00 20060101
G06K009/00; G06K 9/20 20060101 G06K009/20 |
Claims
1. A display device, applicable to an environment for sensing
fingerprint images, comprising: a substrate, having an upper
surface and a lower surface; a cover panel, disposed on the upper
surface of the substrate; and a plurality of unit pixels, disposed
on the substrate, the unit pixels comprising a plurality of red
unit pixels, a plurality of green unit pixels, and a plurality of
blue unit pixels, wherein the red unit pixels emitting a red
incident light, the green unit pixels emitting a green incident
light, and the blue unit pixels emitting a blue incident light;
wherein, the unit pixels on the display device emitting light
alternately; and when a part of the unit pixels emitting light,
defined as in a light-emitting state, when the other part of the
unit pixels not emitting light, defined as in a sensing state, the
unit pixels in the light-emitting state being regarded as a
light-emitting area, and the unit pixels in the sensing state being
regarded as a sensing area, a part of the unit pixels in the
light-emitting area emitting an incident light to a test object,
the test object reflecting the incident light to generate a
reflected light, and a part of the unit pixels in the sensing area
receiving the reflected light to generate an image electrical
signal.
2. The display device according to claim 1, wherein the display
device is an organic light-emitting diode display device.
3. The display device according to claim 1, wherein the
light-emitting area comprises only the blue unit pixels of the
plurality of unit pixels.
4. The display device according to claim 1, wherein the sensing
area comprises one or a combination of the red unit pixels and the
green unit pixels of the plurality of unit pixels.
5. The display device according to claim 1, wherein the plurality
of unit pixels are disposed between the upper surface of the
substrate and the cover panel.
6. The display device according to claim 1, wherein the plurality
of unit pixels are disposed on the lower surface of the
substrate.
7. The display device according to claim 1, wherein the display
device further comprises a readout circuit coupled to each of the
unit pixels, and the readout circuit receives the image electrical
signal to generate a corresponding image information.
8. An image sensing method, comprising the following steps of: a
definition step: a plurality of unit pixels on a display device
emitting light alternately; when a part of the unit pixels emitting
light, these unit pixels being defined as in a light-emitting
state, and when another part of the unit pixels not emitting light,
these unit pixels being defined as in a sensing state; a
light-emitting area step: the unit pixels in the light-emitting
state being used as a light-emitting area; a sensing area step: the
unit pixels in the sensing state being used as a sensing area; an
emission step: a part of the unit pixels in the light-emitting area
emitting an incident light to a test object, and the incident light
emitted to the test object being reflected to generate a reflected
light; a sensing step: a part of the unit pixels in the sensing
area sensing the reflected light, and the sensing area generating a
corresponding image electrical signal.
9. The image sensing method according to claim 8, wherein the
display device is one of an organic light-emitting diode display
device and a micro light-emitting diode display device.
10. The image sensing method according to claim 8, wherein the
light-emitting area comprises only a plurality of blue unit pixels
of the plurality of unit pixels.
11. The image sensing method according to claim 8, wherein the
sensing area comprises one or a combination of a plurality of red
unit pixels and a plurality of green unit pixels of the plurality
of unit pixels.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the priority of U.S. provisional
patent application No. 63/089,055, filed on Oct. 8, 2020, which is
incorporated herewith by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The present invention relates generally to a display device,
and more particularly to a display device and an image sensing
method applicable to fingerprint image recognition.
2. The Prior Arts
[0003] With the development of mobile phone technology and the
continuous growing demands from mobile phone users, the display
screen of the smart phone has been developed towards a full-screen
design for a better user experience, wherein, to provide unlock
recognition, under-screen optical fingerprint recognition is
currently a common solution on the market, which is not only used
in smart phones, but also building fingerprint recognition systems,
corporate attendance fingerprint recognition systems, and so
on.
[0004] There are currently three development directions for
under-screen fingerprint recognition using Organic Light-Emitting
Diode (OLED) screens: (1) arranging at least one thin complementary
metal oxide semiconductor (CMOS) sensor directly below the screen
to be flatly attached to the bottom of the screen, and the gap
between the sub-pixels of the OLED allowing light to pass through,
thereby identifying fingerprints. The above technical features are
similar to one-piece on glass solution (OGS) or one-piece touch on
lens (TOL) of a capacitive touch panel, which can also become a
miniature sensor chip and used an imaging lens set to make a
lens-based sensor module to be assembled under the display screen;
(2) using a thin film transistor process, and using the sensitivity
to visible light of amorphous silicon (a-Si:H) and polysilicon
(poly-Si) to produce light sensitive elements on a glass substrate
or a flexible substrate (such as polyimide film), and mounted under
the OLED screen, which can also be used as a sealing glass to seal
with the OLED panel to sense fingerprint information. The above
technical features are similar to capacitive touch panels, also
known as on-cells by those with ordinary knowledge in the art; (3)
inserting image sensors between the pixels of OLEDs, an organic
photodiode (OPD) being disposed on the thin-film transistor (TFT)
substrate, in addition to each set of pixels (R/GB), as a sensing
element. The above technical features are similar to capacitive
touch panels, also known as in-cell by those with ordinary
knowledge in the art.
[0005] However, the problem of using the aforementioned solution
(1) is that as users pursue the image quality of display devices,
and the design and process technology of OLED display devices
mature, the unit pixels on OLED panels are increasing, making the
gap between the sub-pixels of the OLED gradually decreasing, and
more difficult for the under-screen fingerprint recognition
technology to allow the light penetrate through the gaps between
the sub-pixels of the OLED, which makes the implementation of the
aforementioned solution (1) less feasible. In addition, the problem
of using the aforementioned solution (2) is the same as those of
the aforementioned solution (1), which makes the implementation of
the aforementioned solution (2) more difficult. The problem of
using the aforementioned solution (3) is that the technical
solution of shrinking the image sensor and inserting it between the
pixels of the OLED causes the number of the unit pixels on the OLED
panel to decrease, thereby reducing the resolution of the OLED
panel.
[0006] Therefore, to address the above-mentioned deficiencies, the
inventors disclosed the present invention.
SUMMARY OF THE INVENTION
[0007] A primary objective of the present invention is to provide a
display device having a plurality of unit pixels, the unit pixels
emit light alternately, and when a part of the unit pixels emit
light, the unit pixels are defined as in a light-emitting state,
and the other part of the unit pixels not emitting light are
defined as in a sensing state. By using the unit pixels in the
light-emitting state as the light-emitter for under-screen
fingerprint recognition, and the unit pixels in the sensing state
as the sensor for under-screen fingerprint recognition, the present
invention provides a high-performance image recognition without
affecting the panel pixels.
[0008] To achieve the foregoing objective, the present invention
provides a display device, applicable to an environment for sensing
fingerprint images. The display device comprises: a substrate,
having an upper surface and a lower surface; a plurality of unit
pixels, arranged on the substrate, the unit pixels comprising a
plurality of red unit pixels, a plurality of green unit pixels, and
a plurality of blue unit pixels, wherein the red unit pixels
emitting a red incident light, the green unit pixels emitting a
green incident light, and the blue unit pixels emitting a blue
incident light; wherein, the unit pixels on the display device
emitting light alternately; and when a part of the unit pixels
emitting light, defined as in a light-emitting state, when the
other part of the unit pixels not emitting light, defined as in a
sensing state, the unit pixels in the light-emitting state being
regarded as a light-emitting area, and the unit pixels in the
sensing state being regarded as a sensing area, a part of the unit
pixels in the light-emitting area emitting an incident light to a
test object, the test object reflecting the incident light to
generate a reflected light, and a part of the unit pixels in the
sensing area receiving the reflected light to generate an image
electrical signal.
[0009] Preferably, according to the display device of the present
invention, the display device is one of an organic light-emitting
diode display device and a micro light-emitting diode display
device, but the present invention is not limited hereto.
[0010] Preferably, according to the display device of the present
invention, the light-emitting area only includes the blue unit
pixels among the unit pixels, but the present invention is not
limited hereto.
[0011] Preferably, according to the display device of the present
invention, the sensing area only includes the red unit pixels among
the unit pixels, but the present invention is not limited
hereto.
[0012] Preferably, according to the display device of the present
invention, the sensing area includes one or a combination of the
red unit pixels and the green unit pixels among the unit pixels,
but the present invention is not limited hereto.
[0013] Preferably, according to the display device of the present
invention, the unit pixels are disposed between the upper surface
of the substrate and the cover panel, but the present invention is
not limited hereto.
[0014] Preferably, according to the display device of the present
invention, the unit pixels are disposed on the lower surface of the
substrate, but the present invention is not limited hereto.
[0015] Preferably, according to the display device of the present
invention, the thickness of the cover panel is 700 microns, but the
present invention is not limited hereto.
[0016] Preferably, according to the display device of the present
invention, the display device further comprises a readout circuit
coupled to each of the unit pixels, and the readout circuit
receives the image electrical signal and generates a corresponding
image information.
[0017] In addition, to achieve the foregoing objective, the present
invention, based on the aforementioned display device, further
provides an image sensing method, comprising: alternately
illuminating a plurality of unit pixels on a display device,
wherein, when a part of the unit pixels emitting light, defined as
in a light-emitting state, when the other part of the unit pixels
not emitting light, defined as in a sensing state, the unit pixels
in the light-emitting state being regarded as a light-emitting
area, and the unit pixels in the sensing state being regarded as a
sensing area, a part of the unit pixels in the light-emitting area
emitting an incident light to a test object, the test object
reflecting the incident light to generate a reflected light, and a
part of the unit pixels in the sensing area receiving the reflected
light to generate an image electrical signal.
[0018] Preferably, according to the image sensing method of the
present invention, the display device is one of an organic
light-emitting diode display device and a micro light-emitting
diode display device, but the present invention is not limited
hereto.
[0019] In summary, the display device and the image sensing method
provided by the present invention mainly rely on the unit pixels to
emit light alternately, wherein when a part of the unit pixels emit
light, defined as in a light-emitting state; when the other part is
not emitting light, defined as in a sensing state; by using the
unit pixels in the light-emitting state as the light-emitter for
under-screen fingerprint recognition, and the unit pixels in the
sensing state as the sensor for under-screen fingerprint
recognition, the present invention provides a high-performance
image recognition solution without affecting the panel pixels.
[0020] To enable those skilled in the art to understand the
purpose, features, and effects of the present invention, the
following specific embodiments and accompanying drawings are used
to explain the present invention in detail as follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The present invention will be apparent to those skilled in
the art by reading the following detailed description of a
preferred embodiment thereto, with reference to the attached
drawings, in which:
[0022] FIG. 1 is a schematic view of a display device according to
the present invention;
[0023] FIG. 2 is a schematic view of exemplary details of a display
device according to the present invention;
[0024] FIG. 3 illustrates the absorption spectrum and emission
spectrum of an exemplary host material of the display device
according to the present invention;
[0025] FIG. 4 is a schematic view illustrating that the
light-emitting area according to the present invention is reflected
to the sensing area after emitting light to the test object;
[0026] FIG. 5 is a flowchart illustrating the steps of the image
sensing method of the present invention;
[0027] FIG. 6A is a timing diagram illustrating the implementation
of the image sensing method of the present invention;
[0028] FIG. 6B is another timing diagram illustrating the
implementation of the image sensing method of the present
invention;
[0029] FIG. 7 is a schematic view of a display device according to
the first embodiment of the present invention;
[0030] FIG. 8 is a flowchart illustrating the steps of performing
the image sensing method according to the first embodiment of the
present invention
[0031] FIG. 9A is a timing diagram illustrating the implementation
of the image sensing method of the present invention;
[0032] FIG. 9B is another timing diagram illustrating the
implementation of the image sensing method of the present
invention; and
[0033] FIG. 10 is a schematic diagram of a display device according
to a second embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0034] The accompanying drawings are included to provide a further
understanding of the invention, and are incorporated in and
constitute a part of this specification. The drawings illustrate
embodiments of the invention and, together with the description,
serve to explain the principles of the invention.
[0035] FIG. 1 is a schematic view of a display device according to
the present invention. As shown in FIG. 1, the display device 100
according to the present invention includes: a substrate 11, a
plurality of unit pixel 12, and a cover panel 13. The substrate 11
has an upper surface 111 and a lower surface 112. The cover panel
13 is disposed on the upper surface 111 of the substrate 11. The
unit pixels 12 are disposed on the substrate 11.
[0036] Refer to FIG. 2, which shows exemplary details of the
display device 100. Specifically, the substrate 11 may be, but is
not limited to, a glass substrate, a polyethylene terephthalate
(PET) substrate, a cycloolefin polymer (COP) substrate, a
transparent polyimide (CPI) substrate, a polyethylene naphthalate
(PET) substrate, a Diester (PEN) substrate, a polycarbonate (PC)
substrate, a polyether sulfide (PES) substrate, or a polarizing
film.
[0037] Specifically, the unit pixels 12 are disposed on the
substrate 11. The unit pixels 12 include a red unit pixel 121, a
green unit pixel 122, and a blue unit pixel 123, wherein the red
unit pixel 121 emits a red incident light R, the green unit pixel
122 emits a green incident light G, and the blue unit pixel 123
emits a blue incident light B.
[0038] Specifically, the wavelength of the red incident light R
according to the present invention may be between 620 nm and 750
nm, but the present invention is not limited hereto.
[0039] Specifically, the wavelength of the green incident light G
according to the present invention may be between 495 nm and 570
nm, but the present invention is not limited hereto.
[0040] Specifically, the wavelength of the blue incident light B
according to the present invention may be between 430 nm and 495
nm, but the present invention is not limited hereto.
[0041] Specifically, referring to FIG. 2, the display device 100
may be an organic light emitting diode display (OLED display). In
some embodiments, the unit pixel 12 includes an anode 21, a hole
transport layer 22, a light-emitting layer 23, an electron
transport layer 24, and a cathode 25. A pixel circuit 14 is
provided on the substrate 11, and is coupled to each of the unit
pixels 12 to control each of the unit pixels 12. A planarization
dielectric layer 15 is provided between the unit pixel 12 and the
pixel circuit 14. As shown in FIG. 2, the planarization dielectric
layer 15 is provided with barrier wells 16 (bank) fabricated in
advance by a yellow light etching process, and the anode 21 of the
unit pixel 12 is connected to the corresponding pixel circuit 14 by
passing through the via holes between the barrier wells 16.
According to some embodiments, the display device 100 further
includes an encapsulation layer 17 disposed between the unit pixel
12 and the cover panel 13. The encapsulation layer 17 may be a
single-layer of inorganic encapsulation materials, a multilayer
stack of inorganic encapsulation materials, or a stack of pairs of
inorganic packaging materials and organic packaging materials. The
inorganic packaging material used can be, for example, but not
limited to, silicon nitride (SiNx), silicon oxide (SiOx), silicon
oxynitride (SiONx), aluminum oxide (AlOx), or titanium oxide
(TiOx).
[0042] It is worth mentioning that, as shown in FIG. 2, a
light-shielding layer 14 may be provided on the substrate 11 and
the cover panel 13. The light-shielding layer 14 is used to isolate
the background light in the environment from sensing images of the
display device 100. In the present invention, the term "isolation"
covers both electrical isolation and physical isolation.
[0043] Specifically, refer to FIG. 3, which illustrates the
absorption spectrum and the emission spectrum of the host material
of the display device according to a preferred embodiment of the
present invention. In some embodiments, as shown in FIG. 3, the
display device 100 according to the present invention is an organic
light-emitting diode display device, but currently the conventional
organic light-emitting diode display devices generally use
fluorescent materials or phosphorescent materials as the host
material for light-emitting layer. The main characteristic of the
organic material is that when the molecules inside the material
absorb radiant energy higher than its own energy, the electrons are
excited from the ground state to an excited state with higher
energy, and then the electrons in the excited state decays to the
ground state to generate light. It can be understood that the
display device 100 according to the present invention can also
generate a corresponding image electrical signal by absorbing
radiant energy higher than its own energy.
[0044] Specifically, the unit pixels 12 are disposed on the
substrate 11. In some embodiments, as shown in FIG. 1, the
substrate 11 has an upper surface 111 and a lower surface 112, and
the unit pixels 12 are disposed between the upper surface 111 of
the substrate 11 and the cover panel 13. In other embodiments, the
unit pixels 12 may be disposed on the lower surface 112 of the
substrate 11.
[0045] Specifically, please refer to FIG. 4, which is a schematic
view illustrating that light emitted from the light-emitting area
is reflected to the sensing area after irradiating onto the test
object to be measured. The unit pixels 12 on the display device 100
emit light alternately. When a part of the unit pixels 12 emit
light, the unit pixels are said to be in a light-emitting state
(not shown). At the same time, when another part of the unit pixels
12 do not emit light, the unit pixels are said to be in a sensing
state. As shown in FIG. 4, in some embodiments, the blue unit
pixels 123 in the light-emitting state are used as the
light-emitting area 31, and the red unit pixels 121 in the sensing
state are used as the sensing area 32. A part of the blue unit
pixels 123 of the light-emitting area 31 emit an incident light
R.sub.1 to the test object 200, the incident light R.sub.1 emitted
to the test object 200 is reflected to generate a reflected light
R.sub.2. A part of the red light unit 121 in the sensing area 32
receives the reflected light R.sub.2 and generates a corresponding
image electrical signal. It is understandable that, according to
the above absorption spectrum and emission spectrum, the reason for
using blue unit pixel 123 as the light-emitting area 31 is to
ensure that the molecules inside the organic material of the
sensing area 32 absorb radiant energy higher than their own energy
to generate the corresponding image electrical signal, but the
invention is not limited hereto.
[0046] Refer to FIG. 5, which is a flowchart illustrating the steps
of performing the image sensing method of the present invention. As
shown in FIG. 5, the present invention further provides an image
sensing method, applicable to the aforementioned display device
100, and the image sensing method includes the following steps:
[0047] Definition step S.sub.1: the unit pixels 12 on the display
device 100 emit light alternately. When a part of the unit pixels
12 emit light, these unit pixels are defined as in a light-emitting
state, and when another part of the unit pixels 12 do not emit
light, these unit pixels are defined as in a sensing state; and
proceed to light-emitting area step S.sub.2.
[0048] Light-emitting area step S.sub.2: the unit pixels 12 in the
light-emitting state are used as a light-emitting area 31; and
proceed to sensing area step S.sub.3.
[0049] Sensing area step S.sub.3: the unit pixels 12 in the sensing
state are used as a sensing area 32; and proceed to emission step
S.sub.4.
[0050] Emission step S.sub.4: a part of the unit pixels 12 in the
light-emitting area 31 emit an incident light R.sub.1 to the test
object 200, and the incident light R.sub.1 emitted to the test
object 200 is reflected to generate a reflected light R.sub.2, and
proceed to sensing step S.sub.5.
[0051] Sensing step S.sub.5: a part of the unit pixels 12 in the
sensing area 32 sense the reflected light R.sub.2, and the sensing
area 32 generates a corresponding image electrical signal.
[0052] It should be further noted that in some embodiments, the
image sensing method provided by the present invention can
repeatedly execute the aforementioned emission step S.sub.4 and
sensing step S.sub.5, and the method and principle are the same as
those described above, and will not be repeated here. Moreover, the
sensing method of the present invention can also perform the
emission step S.sub.4 and the sensing step S.sub.5 only once, but
the present invention is not limited hereto.
[0053] Refer to FIGS. 6A and 6B. FIG. 6A is a timing diagram
illustrating the implementation of the image sensing method of the
present invention; FIG. 6B is another timing diagram illustrating
the implementation of the image sensing method of the present
invention. Referring to Table 1 below, in some embodiments, the
blue unit pixel 123 in the light-emitting state is used as the
light-emitting area 31, and the red unit pixel 121 in the sensing
state is used as the sensing area 32. Also, in some embodiments,
referring to FIG. 6A, first, the definition step S.sub.1 is
performed, and the unit pixels 12 on the display device 100
alternately emit light, wherein when a part of the unit pixels 12
emit light, defined as in a light-emitting state; when another part
of the unit pixels 12 do not emit light, defined as in the sensing
state. Then, the light-emitting area step S.sub.2 is executed, and
the blue unit pixel 123 in the light-emitting state is used as the
light-emitting area 31; followed by the sensing area step S.sub.3,
wherein the red unit pixel 121 in the sensing state is used as the
sensing area 32. Next, the emission step S.sub.4 is performed to
drive a part of the blue unit pixels 123 in the light-emitting area
31 to emit an incident light R.sub.1 to the test object 200, and
the incident light R.sub.1 is reflected by the test object 200 to
generate a reflected light R.sub.2. Then, the sensing step S.sub.5
is performed to drive a portion of the red unit pixels 121 in the
sensing area 32 to sense the reflected light R.sub.2, and the
sensing area 32 generates a corresponding image electrical signal.
Finally, the aforementioned emission step S.sub.4 and sensing step
S.sub.5 are repeated.
TABLE-US-00001 TABLE 1 Drive FIG. 6A FIG. 6B Light-emitting area
Blue unit pixels ON ON Sensing area Red unit pixels ON ON Green
unit pixels OFF OFF
[0054] It should be further noted that, in order to avoid the
interference of noise, the implementation in an ideal state is as
follows: First, a part of the blue unit pixels 123 in the
light-emitting area 31 are driven to emit the incident light
R.sub.1 to the test object 200, Next, while turning off the
light-emitting area 31, a part of the red unit pixels 121 in the
sensing area 32 are driven to sense the reflected light R.sub.2. As
a result, the interference of the noise, such as background light,
can be effectively reduced to affect the red unit pixels 121 in the
sensing area 32; however, as the thickness of the display device
gradually decreases, the path of the reflected light R.sub.2
generated after the incident light R.sub.1 is emitted to the test
object 200 is reduced, resulting in a significant decrease in the
response time. Therefore, as shown in FIG. 6B, another embodiment
according to the present invention is described as follows: First,
a part of the blue unit pixels 123 in the light-emitting area 31
are driven to emit the incident light R.sub.1 to the test object
200, and the incident light R.sub.1 emitted to the test object 200
is reflected to generate a reflected light R.sub.2. When a part of
the blue unit pixels 123 in the light-emitting area 31 is not
turned off, a part of the red light unit pixels 121 in the sensing
area 32 is driven to sense the reflected light R.sub.2, and the
sensing area 32 generates a corresponding image electrical signal.
However, the present invention is not limited hereto.
[0055] Accordingly, based on the display device 100 according to
the present invention, and in conjunction with the image sensing
method provided by the present invention, the unit pixels 12 in the
light-emitting state are used as the light-emitter for under-screen
fingerprint recognition, The unit pixels 12 in the sensing state
are used as the sensor for under-screen fingerprint recognition,
and the present invention provides a high-performance image
recognition without affecting the pixels of the panel.
First Embodiment
[0056] Hereinafter, an embodiment of the first embodiment of the
display device 100 of the present invention will be described with
reference to the drawings.
[0057] Refer to FIG. 7, which is a schematic view of a display
device according to the first embodiment of the present invention.
As shown in FIG. 7, the display device 100 according to the first
embodiment of the present invention is applied to a fingerprint
sensing system. The display device 100 includes a substrate 11, a
plurality of unit pixels 12, a cover panel 13, and a readout
circuit 18.
[0058] Specifically, referring to FIG. 7, the substrate 11
according to the first embodiment of the present invention has an
upper surface 111 and a lower surface 112, and the unit pixels 12
are disposed between the upper surface 111 of the substrate 11 and
the cover panels 13, in addition, the thickness of the cover panels
13 is about 700 microns, but the present invention is not limited
hereto.
[0059] Specifically, the unit pixels 12 according to the first
embodiment of the present invention include red unit pixels 121,
green unit pixels 122, and blue unit pixels 123, but the present
invention is not limited hereto.
[0060] It should be further explained that the display device 100
according to the first embodiment of the present invention is an
organic light-emitting diode display device. The organic
light-emitting diode display device can use, but is not limited to,
fluorescent materials or phosphorescent materials as host material
of the light-emitting layer, wherein the host material in the red
unit pixel 121, the green unit pixel 122, and the blue unit pixel
123 can have different absorption spectra and light emission
spectra, respectively, wherein the host material of the blue unit
pixel 123 needs to absorb relatively stronger energy light to
generate the light emission spectrum; the host material of the red
unit pixel 121 can absorb relatively weaker energy light to
generate the light emission spectrum. It can be understood that the
display device 100 according to the first embodiment of the present
invention can generate corresponding image electrical signals by
absorbing light with energy higher than its own energy.
[0061] Specifically, the readout circuit 18 according to the first
embodiment of the present invention is coupled to each of the unit
pixels 12. In the present embodiment, the readout circuit 18
receives the image electrical signal and generates the
corresponding image information, but the invention is not limited
hereto.
[0062] Referring to FIG. 8, FIG. 8 is a flowchart illustrating the
steps of performing the image sensing method according to the first
embodiment of the present invention. As shown in FIG. 8, the
present invention further provides an image sensing method, which
can be applied to the display device 100 of the first embodiment,
and the image sensing method includes the following steps:
[0063] Definition step S.sub.1': the unit pixels 12 on the display
device 100 emit light alternately. When a part of the unit pixels
12 emit light, these unit pixels are defined as in a light-emitting
state, and when another part of the unit pixels 12 do not emit
light, these unit pixels are defined as in a sensing state; and
proceed to light-emitting area step S.sub.2'.
[0064] Light-emitting area step S.sub.2': the unit pixels 12 in the
light-emitting state are used as a light-emitting area 31; and
proceed to sensing area step S.sub.3'.
[0065] Sensing area step S.sub.3': the unit pixels 12 in the
sensing state are used as a sensing area 32; and proceed to
emission step S.sub.4'.
[0066] Emission step S.sub.4': a part of the unit pixels 12 in the
light-emitting area 31 emit an incident light R.sub.1 to the test
object 200, and the incident light R.sub.1 emitted to the test
object 200 is reflected to generate a reflected light R.sub.2, and
proceed to sensing step S.sub.5'.
[0067] Sensing step S.sub.5': a part of the unit pixels 12 in the
sensing area 32 sense the reflected light R.sub.2, and the sensing
area 32 generates a corresponding image electrical signal, and
proceed to outputting step S.sub.6'.
[0068] Output step S.sub.6': the readout circuit 18 receives the
image electrical signal to generate corresponding image
information.
[0069] Refer to FIGS. 9A and 9B. FIG. 9A is a timing diagram
illustrating the implementation of the image sensing method of the
present invention; FIG. 9B is another timing diagram illustrating
the implementation of the image sensing method of the present
invention. Referring to Table 2 below, in the first embodiment of
the present invention, the blue unit pixel 123 in the
light-emitting state is used as the light-emitting area 31, and the
red unit pixel 121 and the green unit pixel 122 in the sensing
state are used as the sensing area 32. For example, referring to
FIG. 9A, first, the definition step S.sub.1' is performed, and the
unit pixels 12 on the display device 100 alternately emit light,
wherein when a part of the unit pixels 12 emit light, defined as in
a light-emitting state; when another part of the unit pixels 12 do
not emit light, defined as in the sensing state. Then, the
light-emitting area step S.sub.2' is executed, and the blue unit
pixel 123 in the light-emitting state is used as the light-emitting
area 31; followed by the sensing area step S.sub.3', wherein the
red unit pixel 121 and the green unit pixel 122 in the sensing
state are used as the sensing area 32. Next, the emission step
S.sub.4' is performed to drive a part of the blue unit pixels 123
in the light-emitting area 31 to emit an incident light R.sub.1 to
the test object 200, and the incident light R.sub.1 is reflected by
the test object 200 to generate a reflected light R.sub.2. Then,
the sensing step S.sub.5' is performed to drive a portion of the
red unit pixels 121 in the sensing area 32 to sense the reflected
light R.sub.2, and the sensing area 32 generates a corresponding
image electrical signal. Finally, the outputting step S.sub.6' is
performed, and the readout circuit 18 receives the image electrical
signal to generate a corresponding image information.
TABLE-US-00002 TABLE 2 Drive FIG. 9A FIG. 9B Light-emitting area
Blue unit pixels ON ON Sensing area Red unit pixels ON ON Green
unit pixels ON ON
[0070] It should be further noted that, according to the first
embodiment of the present invention, the red unit pixel 121 and the
green unit pixel 122 in the sensing state are used as the sensing
area 32 at the same time. The reason is that different readout
circuits 18 can be provided with the red unit pixel 121 the green
unit pixel 122 to respectively generate corresponding image
information. The multiple image information can be mutually
confirmed, which further improves the accuracy of image sensing by
the display device 100 according to the present invention. However,
the present invention is not limited hereto.
[0071] It should be further noted that, in order to avoid the
interference of noise, for the first embodiment of the present
invention, the implementation in an ideal state is as follows:
First, a part of the blue unit pixels 123 in the light-emitting
area 31 are driven to emit the incident light R.sub.1 to the test
object 200. Next, while turning off the light-emitting area 31, a
part of the red unit pixels 121 and a part of green unit pixels 122
in the sensing area 32 are driven to sense the reflected light
R.sub.2. As a result, the interference of the noise, such as
background light, can be effectively reduced to affect the red unit
pixels 121 and the green unit pixels 122 in the sensing area 32;
however, as the thickness of the display device gradually
decreases, the path of the reflected light R.sub.2 generated after
the incident light R.sub.1 is emitted to the test object 200 is
reduced, resulting in a significant decrease in the response time.
Therefore, as shown in FIG. 9B, another embodiment according to the
present invention is described as follows: First, a part of the
blue unit pixels 123 in the light-emitting area 31 are driven to
emit the incident light R.sub.1 to the test object 200, and the
incident light R.sub.1 emitted to the test object 200 is reflected
to generate a reflected light R.sub.2. When a part of the blue unit
pixels 123 in the light-emitting area 31 is not turned off, a part
of the red light unit pixels 121 and green unit pixels 122 in the
sensing area 32 is driven to sense the reflected light R.sub.2, and
the sensing area 32 generates a corresponding image electrical
signal. However, the present invention is not limited hereto.
[0072] As such, based on the display device 100 according to the
first embodiment of the present invention, and in conjunction with
the image sensing method provided by the present invention, the
unit pixels 12 in the light-emitting state are used as the
light-emitter for under-screen fingerprint recognition, The unit
pixels 12 in the sensing state are used as the sensor for
under-screen fingerprint recognition, and the present invention
provides a high-performance image recognition without affecting the
pixels of the panel.
[0073] The following provides other examples of the display device
100, so that a person with ordinary knowledge in the technical
field of the present invention can more clearly understand the
possible modifications. The elements indicated by the same element
symbols as in the above embodiment are substantially the same as
those described above with reference to FIGS. 1 and 2. The
elements, features, and advantages that are the same as those of
the display device 100 will not be repeated.
[0074] Refer to FIG. 10, which is a schematic view of a display
device 100 according to a second embodiment of the present
invention. Compared with the first embodiment, the main structural
difference of the second embodiment is that in the image sensor 100
of the second embodiment, the unit pixel 12 can be disposed on the
lower surface 112 of the substrate 11. The materials and other
characteristics used in the unit pixel 12 according to the second
embodiment of the present invention are similar to those of the
unit pixel 12 according to the first embodiment of the present
invention, and will not be repeated here.
[0075] It can be understood that a person with ordinary knowledge
in the technical field of the present invention can make various
changes and adjustments based on the above examples, which will not
be listed here.
[0076] Finally, the technical features of the present invention and
its achievable technical effects are summarized as follows:
[0077] First, based on the display device 100 of the present
invention, and in conjunction with the image sensing method
provided by the present invention, the image successfully provides
a high-performance image recognition without affecting the pixels
of the panel.
[0078] Second, based on the display device 100 of the present
invention, and in conjunction with the image sensing method
provided by the present invention, the issue of the decreasing gap
between the sub-pixels of the OLED is successfully resolved, and
the difficulty for under-screen fingerprint recognition technology
to use the gap between the sub-pixels of the OLED allows light to
pass is overcome, and the under screen fingerprint recognition
technology can still be implemented on the high-pixel OLED
panel.
[0079] Third, based on the display device 100 of the present
invention and in conjunction with the image sensing method provided
by the present invention, the display device 100 according to the
present invention not only serves as a light-emitting element, but
also can be used as a sensing element for fingerprint image
recognition, achieving the objectives of reducing costs and wide
applicability.
[0080] Although the present invention has been described with
reference to the preferred embodiments thereto, it is apparent to
those skilled in the art that a variety of modifications and
changes may be made without departing from the scope of the present
invention which is intended to be defined by the appended
claims.
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