WO2019127808A1

WO2019127808A1 - Flexible display device and method for obtaining bending state information of flexible display panel

Info

Publication number: WO2019127808A1
Application number: PCT/CN2018/074290
Authority: WO
Inventors: 邹新
Original assignee: 武汉华星光电半导体显示技术有限公司
Priority date: 2017-12-27
Filing date: 2018-01-26
Publication date: 2019-07-04
Also published as: CN108225207A

Abstract

A flexible display device comprises: a flexible display panel (100); and optical fiber grating sensors (201-209) provided at a boundary region and/or a central region of the flexible display panel (100), wherein the optical fiber grating sensors (201-209) emit incident light waves and receive reflected light waves, the reflected light waves are incident light waves that are returned after being reflected, and the optical fiber grating sensors (201-209) determine bending state information of the flexible display panel (100) according to an elasto-optical coefficient of an optical fiber and a wavelength shift of the incident light wave. The invention uses the optical fiber grating sensors (201-209) to obtain the bending state information of the flexible display panel (100), and the optical fiber grating sensors (201-209) have high resistance to external electromagnetic interference, such that the obtained bending state information of the flexible display panel (100) is accurate.

Description

Method for obtaining bending state quantity of flexible display device and flexible display panel

Technical field

The present invention relates to the field of flexible display technologies, and in particular to a flexible display device and a method for acquiring a bending state quantity of a flexible display panel.

Background technique

In recent years, display technologies for flexible displays, such as flexible OLED displays, have developed rapidly. Compared with conventional rigid displays, flexible displays have a series of advantages such as impact resistance, shock resistance, light weight, small size, and even wearability. Widely welcomed by the market.

Flexible displays currently widely used are flexible film display substrates, which have good bending properties. In addition to curved display, the use of screen bending as an input is also an inevitable development direction. The amount of state during the bending process includes the displacement of each point on the screen, the amount of bending, the direction of bending, and the like. They are expected to operate on the display screen as an input. How to effectively measure the amount of bending state of the flexible display during bending is one of the key technologies.

Summary of the invention

In order to solve the above problems in the prior art, it is an object of the present invention to provide a flexible display device capable of effectively detecting the amount of bending state of a flexible display during bending and a method of acquiring a bending state amount of the flexible display panel.

According to an aspect of the present invention, a flexible display device includes: a flexible display panel; a fiber grating sensor for emitting incident light waves and receiving reflected light waves, and according to an elastic coefficient of the optical fiber and a wavelength of the incident light wave Drifting to determine an amount of bending state of the flexible display panel; wherein the reflected light wave is an incident light wave that returns after being reflected.

Further, the amount of bending state of the flexible display panel includes a bending direction and a bending amount of the flexible display panel.

Further, the FBG sensor emits the incident light wave to a protruding unit of the flexible display panel; the FBG sensor calculates the wavelength based on a center wavelength of the incident light wave and a center wavelength of the reflected light wave Drift, the reflected light wave is an incident light wave that is reflected back at the protruding unit.

Further, the fiber Bragg grating sensor calculates the elastic coefficient of the fiber by using the optical stress tensor of the fiber.

Further, the fiber grating sensor comprises one of a Bragg fiber grating sensor, a long period fiber grating sensor, a chirped fiber grating sensor, and a blazed fiber grating sensor.

Further, the fiber grating sensor is disposed on a surface of the flexible display panel, or the fiber grating sensor is integrated in the flexible display panel.

According to another aspect of the present invention, a method for acquiring a bending state quantity of a flexible display panel, further comprising the steps of: a fiber grating sensor emitting an incident light wave; the fiber grating sensor receiving a reflected light wave, wherein the reflected light wave is An incident light wave returned after being reflected; the fiber grating sensor determines a bending state amount of the flexible display panel according to an elastic coefficient of the optical fiber and a wavelength shift of the incident light wave.

Further, the calculation method of the wavelength shift of the incident light wave includes: the FBG sensor emits the incident light wave to a protruding unit of the flexible display panel; the FBG sensor is based on a center wavelength of the incident light wave The wavelength shift of the reflected light wave is calculated, and the reflected light wave is an incident light wave that is reflected back at the protruding unit.

Further, the calculation method of the elastic coefficient of the optical fiber includes: the FBG sensor calculates an elastic coefficient of the optical fiber by using an optical stress tensor of the optical fiber.

The invention has the beneficial effects that the invention can effectively detect the bending state of the flexible display panel by using the fiber grating sensor, and the fiber grating sensor is strong against external electromagnetic interference, and the detected bending state of the flexible display panel is more accurate.

DRAWINGS

The above and other aspects, features and advantages of the embodiments of the present invention will become more apparent from

1 is a top plan view of a flexible display device in accordance with an embodiment of the present invention;

2 is a side view of a flexible display device in accordance with an embodiment of the present invention;

3 is a schematic diagram of the principle of a fiber grating sensor according to an embodiment of the present invention;

4 is a state diagram of a flexible display panel folded in accordance with an embodiment of the present invention;

FIG. 5 is a state diagram of a flexible display panel folded outward according to an embodiment of the present invention; FIG.

6 is a state diagram of a flexible display panel bent in an "S" shape according to an embodiment of the present invention;

7 is a flow chart of a method of acquiring a bending state amount of a flexible display panel according to an embodiment of the present invention.

Detailed ways

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the invention may be embodied in many different forms and the invention should not be construed as being limited to the specific embodiments set forth herein. Rather, these embodiments are provided to explain the principles of the invention and the application of the invention, and the various embodiments of the invention can be understood.

In the drawings, the thickness of layers and regions are exaggerated for clarity. The same reference numerals are used throughout the drawings and the drawings.

1 is a top plan view of a flexible display device in accordance with an embodiment of the present invention. 2 is a side view of a flexible display device in accordance with an embodiment of the present invention.

Referring to FIGS. 1 and 2, the flexible display device 10 includes a flexible display panel 100 and first to ninth

fiber grating sensors

201, 202, 203, 204, 205, 206, 207, 208, 209.

The first to eighth

fiber grating sensors

201, 202, 203, 204, 205, 206, 207, 208 are disposed at a boundary region of the flexible display panel 100, and the ninth fiber grating sensor 209 is disposed on the flexible display panel 100. The central area is, but the invention is not limited thereto. For example, the FBG sensor may be disposed only at the boundary region of the flexible display panel 100, or the FBG sensor may be disposed only at the central portion of the flexible display panel 100. In addition, the number of FBG sensors is not limited to that shown, and any number of FBG sensors can be disposed at the boundary area and/or at the central area of the flexible display panel 100 according to actual needs.

The flexible display panel 100 may be an organic light emitting diode display panel or a liquid crystal display panel.

The first to ninth

fiber grating sensors

201, 202, 203, 204, 205, 206, 207, 208, 209 are used to detect the amount of bending state of the flexible display panel 100, respectively. In the present embodiment, the amount of bending state of the flexible display panel 100 may include a bending amount (or bending angle) and a bending direction, and may also include other parameter amounts.

The first to ninth

fiber grating sensors

201, 202, 203, 204, 205, 206, 207, 208, 209 respectively emit incident light waves toward the flexible display panel 100 and receive and use reflected light waves, which are displayed in a flexible manner The incident light wave returned after the panel 100 reflects, the first to ninth

fiber grating sensors

201, 202, 203, 204, 205, 206, 207, 208, 209 are respectively according to the optical fiber coefficient of the optical fiber and the wavelength drift of the incident light wave. The amount of bending state of the flexible display panel 100 is determined.

The principle of how the FBG sensor determines the amount of bending state of the flexible display panel 100 will be described below. A fiber Bragg grating sensor is used as an example of a Bragg fiber grating sensor.

3 is a schematic diagram of the principle of a fiber Bragg grating sensor in accordance with an embodiment of the present invention.

Referring to Figure 3, the grating 10 of the Bragg fiber grating sensor has a period of less than 1 μm, for example 500 nm.

For a Bragg fiber grating sensor, the wavelength λ _B is the center wavelength of the light wave reflected back through the grating 10 of the Bragg fiber grating sensor (ie, the incident light wave emitted by the Bragg fiber grating sensor).

λ _B =2n _eff Λ (1)

Where Λ is the period length of the grating 10 and n _eff is the refractive index of the fiber to the center wavelength of the free space, which is a fixed value. Here, the propagation of light can be calibrated in time and space. Free space can be understood here as vacuum. For example, the refractive index of light in vacuum is 1.0, and the refractive index in optical fiber is 1.5. The Bragg fiber grating sensor is used for strain measurement. The relationship between the wavelength shift Δλ _BS of the light wave reflected back through the grating 10 of the Bragg fiber grating sensor and the longitudinal strain Δε it receives is:

Δλ _BS =λ _B (1-ρ _a )Δε (2)

Where ρ _a is the elastic coefficient of the fiber, ρ ₁₁ and ρ ₁₂ are the two components of the optical stress tensor of the fiber, and υ is the Poisson coefficient. By bending a particular Bragg fiber grating sensor in a particular direction, i.e., ρ ₁₁ and ρ ₁₂ , the optical coefficient ρ _{a of the} fiber can be solved, and the wavelength shift Δλ _BS and the longitudinal strain Δ ε are linear. In the present embodiment, the wavelength drift Δλ _BS refers to the center wavelength of the light wave reflected by the grating 10 of the Bragg fiber grating sensor (ie, the incident light wave emitted by the Bragg fiber grating sensor) and the light wave incident on the Bragg fiber grating sensor. The difference between the center wavelengths of the incident light waves returned after being reflected by the flexible display panel 100. After the wavelength drift Δλ _{BS is} determined, the longitudinal strain Δε can be determined, so that the determination of the amount of bending state of the flexible display panel 100 can be achieved.

Furthermore, as other embodiments of the present invention, the first to ninth

fiber grating sensors

201, 202, 203, 204, 205, 206, 207, 208, 209 of the present embodiment may also be long period gratings (Long Period Fiber Grating) , LPG) sensors, Chirped Fiber Grating sensors, Blazed Fiber Grating sensors, etc.

In addition, it should be noted that although the first to ninth

fiber grating sensors

201, 202, 203, 204, 205, 206, 207, 208, 209 are disposed on the surface of the flexible display panel 100 in the present embodiment, The invention is not limited thereto, and for example, the first to ninth

fiber grating sensors

201, 202, 203, 204, 205, 206, 207, 208, 209 may also be integrated in the flexible display panel 100.

4 is a state diagram of the flexible display panel folded inwardly according to an embodiment of the present invention. FIG. 5 is a state diagram of a flexible display panel folded outward according to an embodiment of the present invention. 6 is a view showing a state in which the flexible display panel is bent in an "S" shape according to an embodiment of the present invention.

Referring to FIGS. 4 through 6, the first to third

fiber grating sensors

201, 202, 203 respectively emit incident light waves to the protruding unit of the flexible display panel 100. The "projecting unit" may be a structure formed to generate a reflected wave (not shown), or may be a convex portion formed by bending of the flexible display panel 100.

The first to third

fiber grating sensors

201, 202, 203 are respectively based on the center wavelength and the reflected light wave of the incident light wave (i.e., the light wave reflected back through the gratings of the first to third

fiber grating sensors

201, 202, 203, respectively). The wavelength of the reflected light wave is calculated by the center wavelength of the light waves incident on the first to third

fiber grating sensors

201, 202, and 203, respectively (that is, the difference between the center wavelength of the incident light wave and the center wavelength of the reflected light wave), and the reflected light wave is A returning incident light wave that is reflected at the convex unit.

After the bending state of the flexible display panel 100 is determined, the optical stress tensor of the optical fiber is determined, and the first to third

fiber grating sensors

201, 202, and 203 respectively calculate the optical fiber by using the optical stress tensor of the optical fiber by the above formula 3. Bomb coefficient.

It can be seen from the above formula 2 that after the elastic coefficient of the optical fiber is determined, the wavelength drift and the longitudinal strain are linear. Therefore, the first to third

fiber grating sensors

201, 202, and 203 calculate the longitudinal strain of the optical fiber by the above formula 2, respectively, based on the above-described calculated optical fiber coefficient and wavelength drift of the optical fiber. The longitudinal strain of the optical fiber indicates the amount of bending state of the flexible display panel 100. Specifically, after the elastic coefficient of the optical fiber is determined, the wavelength drift and the longitudinal strain are linear, so that the longitudinal strain can be determined by the calculated wavelength drift, and the longitudinal strain represents the amount of the bending state of the flexible display panel 100. Thereby, the determination of the amount of bending state of the flexible display panel 100 can be achieved.

Here, the first to third

fiber grating sensors

201, 202, 203 are taken as an example to explain how to determine the amount of bending state of the flexible display panel 100, and the fourth to ninth

fiber grating sensors

204, 205, 206, 207, 208, The process of determining the amount of bending state of the flexible display panel 100 is consistent with the processes of the first to third

fiber grating sensors

201, 202, 203 as an example of how to determine the amount of bending state of the flexible display panel 100.

Referring to FIG. 7 , referring to FIG. 1 to FIG. 6 , a method for acquiring a bending state quantity of a flexible display panel according to an embodiment of the present invention includes:

Step S710: The first to ninth

fiber grating sensors

201, 202, 203, 204, 205, 206, 207, 208, 209 disposed at the boundary region and/or the central region of the flexible display panel 100 respectively emit incident light waves.

Step S720: The first to ninth

fiber grating sensors

201, 202, 203, 204, 205, 206, 207, 208, 209 respectively receive reflected light waves, which are incident light waves that are returned after being reflected.

Step S730: The first to ninth

fiber grating sensors

201, 202, 203, 204, 205, 206, 207, 208, 209 determine the flexible display panel 100 according to the elastic coefficient of the optical fiber and the wavelength shift of the incident light wave, respectively. The amount of bending state.

Further, in step S730, the calculation method of the wavelength drift of the incident light wave includes: the first to ninth

fiber grating sensors

201, 202, 203, 204, 205, 206, 207, 208, 209 respectively emit the incident Light waves to the protruding unit of the flexible display panel 100; the first to ninth

fiber grating sensors

201, 202, 203, 204, 205, 206, 207, 208, 209 are respectively calculated based on the center wavelength of the incident light wave and the center wavelength of the reflected light wave The wavelength drifts, and the reflected light wave is a return incident light wave that is reflected at the convex unit.

In addition, in step S730, the calculation method of the elastic coefficient of the optical fiber includes: the first to ninth

fiber grating sensors

201, 202, 203, 204, 205, 206, 207, 208, 209 respectively utilize the optical stress of the optical fiber The tensor is calculated by the above formula (3).

Further, further, in step S730, the first to ninth

fiber grating sensors

201, 202, 203, 204, 205, 206, 207, 208, 209 are respectively according to the calculated optical fiber coefficient and wavelength drift of the optical fiber. The longitudinal strain of the optical fiber was calculated by the above formula 2. The longitudinal strain of the optical fiber indicates the amount of bending state of the flexible display panel 100. Specifically, it can be seen from the above formula 2 that after the elastic coefficient of the optical fiber is determined, the wavelength drift and the longitudinal strain are linear, so that the longitudinal strain can be determined by the calculated wavelength shift, and the longitudinal strain indicates the bending of the flexible display panel 100. The amount of state, so that the determination of the amount of bending state of the flexible display panel 100 can be achieved.

In summary, according to the embodiment of the present invention, the amount of bending state of the flexible display panel can be effectively detected by using the fiber Bragg grating sensor, and the fiber grating sensor is strong against external electromagnetic interference, and the detected bending state of the flexible display panel is more accurate.

While the invention has been shown and described with respect to the specific embodiments the embodiments of the invention Various changes in details.

Claims

A flexible display device, comprising:

Flexible display panel;

a fiber grating sensor disposed on the flexible display panel, the fiber grating sensor is configured to emit an incident light wave and receive the reflected light wave, and determine the flexible display panel according to an elastic coefficient of the optical fiber and a wavelength drift of the incident light wave The amount of bending state; wherein the reflected light wave is an incident light wave that returns after being reflected.
The flexible display device according to claim 1, wherein the amount of bending state of the flexible display panel includes a bending direction and a bending amount of the flexible display panel.
The flexible display device according to claim 1, wherein

The fiber Bragg grating sensor emits the incident light wave to a protruding unit of the flexible display panel;

The FBG sensor calculates the wavelength shift based on a center wavelength of the incident light wave and a center wavelength of the reflected light wave, and the reflected light wave is an incident light wave that is reflected back at the protruding unit.
The flexible display device according to claim 2, wherein

The fiber Bragg grating sensor emits the incident light wave to a protruding unit of the flexible display panel;

The FBG sensor calculates the wavelength shift based on a center wavelength of the incident light wave and a center wavelength of the reflected light wave, and the reflected light wave is an incident light wave that is reflected back at the protruding unit.
The flexible display device of claim 1, wherein the fiber grating sensor calculates an elastic coefficient of the optical fiber by using an optical stress tensor of the optical fiber.
The flexible display device of claim 2, wherein the FBG sensor calculates an optical coefficient of the optical fiber by utilizing an optical stress tensor of the optical fiber.
The flexible display device of claim 1, wherein the fiber grating sensor comprises one of a Bragg fiber grating sensor, a long period fiber grating sensor, a chirped fiber grating sensor, and a blazed fiber grating sensor.
The flexible display device of claim 1, wherein the FBG sensor is disposed on a surface of the flexible display panel, or the FBG sensor is integrated in the flexible display panel.
A method for obtaining a bending state quantity of a flexible display panel, comprising the steps of:

a fiber grating sensor disposed on the flexible display panel emits incident light waves;

The fiber grating sensor receives reflected light waves, the reflected light waves being incident light waves that are returned after being reflected;

The FBG sensor determines an amount of bending state of the flexible display panel according to an elastic coefficient of the optical fiber and a wavelength shift of the incident light wave.
The method of acquiring a bending state amount of a flexible display panel according to claim 9, wherein the bending state amount of the flexible display panel includes a bending direction and a bending amount of the flexible display panel.
The method for obtaining a bending state quantity of a flexible display panel according to claim 9, wherein the calculation method of the wavelength drift of the incident light wave comprises:

The fiber Bragg grating sensor emits the incident light wave to a protruding unit of the flexible display panel;

The FBG sensor calculates the wavelength shift based on a center wavelength of the incident light wave and a center wavelength of the reflected light wave, and the reflected light wave is an incident light wave that is reflected back at the protruding unit.
The method for obtaining a bending state quantity of a flexible display panel according to claim 10, wherein the calculating method of the wavelength drift of the incident light wave comprises:

The fiber Bragg grating sensor emits the incident light wave to a protruding unit of the flexible display panel;

The FBG sensor calculates the wavelength shift based on a center wavelength of the incident light wave and a center wavelength of the reflected light wave, the reflected light wave being an incident light wave reflected back at the protruding unit.
The method for obtaining a bending state quantity of a flexible display panel according to claim 9, wherein the calculation method of the elastic coefficient of the optical fiber comprises: the fiber grating sensor calculates a fiber bomb by using an optical stress tensor of the optical fiber Light coefficient.
The method for obtaining a bending state quantity of a flexible display panel according to claim 10, wherein the calculation method of the elastic coefficient of the optical fiber comprises: the fiber grating sensor calculates a fiber bomb by using an optical stress tensor of the optical fiber Light coefficient.