CN111308768B

CN111308768B - Display panel and display device

Info

Publication number: CN111308768B
Application number: CN201911198580.9A
Authority: CN
Inventors: 张桂洋
Original assignee: Wuhan China Star Optoelectronics Technology Co Ltd
Current assignee: Wuhan China Star Optoelectronics Technology Co Ltd
Priority date: 2019-11-29
Filing date: 2019-11-29
Publication date: 2023-02-07
Anticipated expiration: 2039-11-29
Also published as: CN111308768A

Abstract

The application discloses display panel and display device, display panel includes: the liquid crystal display panel comprises a substrate, a first color film substrate, a second color film substrate, a photosensitive sensor, an array substrate and liquid crystal, wherein the thickness of the substrate is 100-300 mu m. The invention has the technical effects of reducing the influence of interference light signals, forming light beam collimation, and improving the signal-to-noise ratio of fingerprint signals so as to meet the requirement of a liquid crystal display panel on the identification of fingerprints under a screen.

Description

Display panel and display device

Technical Field

The present invention relates to the field of display, and in particular, to a display panel and a display device.

Background

The fingerprint identification technology is mainly used for mobile phone unlocking, convenient payment, secret login-free and the like, and is a necessary technology of smart phones. The early fingerprint identification mostly utilizes a capacitive identification scheme, the working principle is that a capacitive sensor is added below a Home key or at the bottom of a mobile phone, different-size electrical signals are generated when ridges and valleys contact the sensor, the electrical signals are converted into a gray-scale image after being processed and amplified, and the fingerprint identification is realized. However, the Home key needs to sacrifice a certain display area to place the capacitive sensor, which results in a screen occupation ratio of less than 80%, and the way of identifying the back of the mobile phone has many inconveniences. Thus, with the advent and growing market acceptance of the "full screen" concept, such capacitive fingerprinting schemes have suffered from devastating attacks.

The optical fingerprint identification technology and the ultrasonic fingerprint identification technology are under-screen identification technologies, the effect of a 'full-screen' can be achieved, and the screen occupation ratio can be improved to more than 90%. Ultrasonic fingerprint identification technology utilizes the ultrasonic wave can pierce through by materials such as glass, aluminium, stainless steel, sapphire, plastics, does not receive greasy dirt on the finger, sweat stain, skin care products's influence, and different media are different to ultrasonic absorption, penetration and reflection effect, distinguishes fingerprint information to the different reflection effect of ultrasonic wave through the air of the cortex of finger ridge position and millet position, and its discernment precision is high, the recognition speed is fast. But the ultrasonic fingerprint identification scheme is relatively high in cost, and the ultrasonic identification effect is not good when the finger is relatively dry.

Because a longer light path and a larger size are needed, the optical fingerprint identification technology is mostly used for unlocking or identifying large-size equipment, such as a door lock, a fingerprint card punch and the like, and the identification precision is high and the cost is low. The current application of optical fingerprint identification in smart phones or tablet computers is not wide. Optical fingerprinting technology has been applied first in OLED display devices in recent two years because OLEDs are active light emitting displays and there are inherent advantages to using optical fingerprinting. The light that OLED pixel sent shines on the finger, and the light that reflects from the finger passes through the space between the OLED pixel, and on collimation or spotlight module arrival sensitization sensor through pixel plane below realized fingerprint identification. However, the LCD device is a passive light emitting display, the interference of the film layer and the pixel opening area inside the LCD device to the fingerprint signal is large, and the fingerprint signal is often submerged by these noise signals, so the LCD-based optical fingerprint identification technology is still under the exploration stage, and no more mature scheme is available at present.

As shown in fig. 1, the conventional display panel includes a substrate 100, a color filter substrate 200, an array substrate 300 and a liquid crystal 400, and adopts a structure of a single-layer color filter substrate, so that most of large-angle interference light cannot be blocked, which greatly reduces the signal-to-noise ratio of a fingerprint signal and seriously affects the display effect of the display panel.

Disclosure of Invention

The invention aims to solve the technical problem of low signal-to-noise ratio of a fingerprint signal in the prior art of identifying the fingerprint under a screen of an LCD display device.

To achieve the above object, the present invention provides a display panel including: a substrate; the first color film substrate is arranged on the surface of one side of the substrate; the second color film substrate is arranged on the surface of one side of the substrate, which is far away from the first color film substrate; the photosensitive sensor is arranged on one side, away from the substrate, of the first color film substrate or the second color film substrate; the array substrate is arranged on one side, away from the substrate, of the second color film substrate; the liquid crystal is arranged between the second color film substrate and the array substrate; wherein the thickness of the substrate is 100-300 μm.

Furthermore, the photosensitive sensor is arranged on the surface of the array substrate close to one side of the liquid crystal.

Further, the second color film substrate comprises a pixel unit; each pixel unit comprises a red sub-pixel, a green sub-pixel and a blue sub-pixel.

Further, in the same pixel unit, the projection of the photosensor on the second color film substrate is located on the same line as the red subpixel, the green subpixel and the blue subpixel, or forms an array.

Furthermore, the photosensitive sensor is arranged on the surface of the first color film substrate on the side far away from the substrate.

Further, the first color film substrate comprises a pixel unit; each pixel unit comprises a photosensitive sensor, a red sub-pixel, a green sub-pixel and a blue sub-pixel.

Further, in the same pixel unit, the photosensitive sensor and the red, green and blue sub-pixels are located on the same line, or form an array.

Further, the first polarizer is arranged on the surface of one side, far away from the substrate, of the first color film substrate; the adhesive layer is arranged on the surface of one side of the first polarizer, which is far away from the first color film substrate; the cover plate is arranged on the surface of one side of the adhesive layer, which is far away from the first polaroid; and the protective layer is arranged on the surface of one side of the cover plate, which is far away from the glue layer.

Furthermore, the sum of the thicknesses of the first polarizer, the adhesive layer, the cover plate and the protective layer is 0.8-1.1 mm.

In order to achieve the above object, the present invention further provides a display device including the above display panel.

The invention has the technical effects that the double-layer color film substrate is adopted, the color film substrate on the upper layer of the substrate can block most of strong noise fingerprint signals to form light beam collimation, so that most of the fingerprint signals received by the photosensitive sensor are ideal fingerprint signals or weak noise fingerprint signals, the signal-to-noise ratio of the fingerprint signals can be improved, and the requirement of fingerprint identification under the liquid crystal display panel stack screen is met. When the thickness of the substrate is 100 μm to 300 μm, the fingerprint recognition contrast of the fingerprint recognition signal increases and then decreases as the thickness of the substrate increases, and when the thickness of the substrate is 200 μm, the fingerprint recognition effect is the best.

Drawings

The technical solution and other advantages of the present application will become apparent from the detailed description of the embodiments of the present application with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a display panel in the prior art;

fig. 2 is a schematic structural diagram of a display panel according to embodiment 1 of the present invention;

fig. 3 is a schematic diagram of fingerprint recognition according to embodiment 1 or 2 of the present invention;

fig. 4 is a simulation diagram of the detection light test fingerprint identification according to embodiment 1 or 2 of the present invention;

fig. 5 is a schematic structural diagram of a display panel according to embodiment 2 of the present invention.

Some of the components are identified as follows:

100. a substrate; 200. a color film substrate; 300. an array substrate; 400. a liquid crystal;

1. a substrate; 2. a first color film substrate; 3. a second color film substrate; 4. an array substrate; 5. a liquid crystal; 6. a light-sensitive sensor; 7. a polarizer; 8. a glue layer; 9. a cover plate; 10. a protective layer;

21. a red sub-pixel; 22. a green sub-pixel; 23. a blue sub-pixel;

31. a red sub-pixel; 32. a green sub-pixel; 33. a blue sub-pixel;

801. a main signal region; 802. a first interference region; 803. a second interference region.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In the description of the present application, it is to be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present application and for simplicity in description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed in a particular orientation, and be operated in a particular manner, and are not to be construed as limiting the present application. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to implicitly indicate the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; may be mechanically connected, may be electrically connected or may be in communication with each other; they may be directly connected or indirectly connected through intervening media, or may be connected through the use of two elements or the interaction of two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

In this application, unless expressly stated or limited otherwise, the recitation of a first feature "on" or "under" a second feature may include the recitation of the first and second features being in direct contact, and may also include the recitation of the first and second features not being in direct contact, but being in contact with another feature between them. Also, the first feature "on," "above" and "over" the second feature may include the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

The following disclosure provides many different embodiments or examples for implementing different features of the application. In order to simplify the disclosure of the present application, specific example components and arrangements are described below. Of course, they are merely examples and are not intended to limit the present application. Moreover, the present application may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, examples of various specific processes and materials are provided herein, but one of ordinary skill in the art may recognize applications of other processes and/or use of other materials.

Example 1

The embodiment provides a display device, which includes a display panel as shown in fig. 2, and the display panel includes a substrate 1, a first color film substrate 2, a second color film substrate 3, an array substrate 4, a liquid crystal 5, a photosensor 6, a polarizer 7, an adhesive layer 8, a cover plate 9, and a protective layer 10.

The substrate 1 is a transparent glass substrate, so that light rays can conveniently pass through the substrate, and meanwhile, the hard substrate can serve as a substrate layer of the whole display panel to play a supporting role.

As shown in fig. 3, the fingerprint reflection light signal collected by the photosensor 6 includes a main signal area 801, a first interference area 802 and a second interference area 803, in fig. 3, a dotted line S1 is a noise signal, and a solid line S2 is a useful signal, for example, when the detected light wave is blue light, light transmitted by θ 3- θ 6 is a large-angle interference light signal. Considering that the size of the photosensor 6 is not changed, the thicker the substrate 1 is, the smaller the angle θ 3- θ 6 is. The signal collected by the light sensor 6 will contain more noise, which eventually results in no fingerprint signal being recognized. However, the too low thickness of the substrate 1 may cause the light-shielding distance formed between the first color film substrate 2 and the second color film substrate 3 to be too short, and the color film substrate cannot filter the interference light. In order to verify the validity of the fingerprint light path provided by the text, the fingerprint identification effect of a group of conventional liquid crystal display panels is simulated.

Experiment results show that the effective energy utilization rate (the ratio of energy received by the photosensitive sensor 6 to fingerprint reflection energy) and the fingerprint ridge and valley contrast (the energy ratio corresponding to the fingerprint ridge and valley) of a fingerprint light path can be changed along with the difference of the thickness of the substrate 1 and the fingerprint identification effect. The thickness of the substrate 1 is 100-300 μm, and the effective energy utilization rate of the fingerprint light path is reduced along with the thickening of the substrate 1. With the increase of the thickness of the substrate 1, the fingerprint contrast parameter of the fingerprint identification effect is increased and then reduced, when the thickness of the substrate 1 is increased to 300 μm, fingerprint information cannot be distinguished, at the moment, a fingerprint light path fails, and the influence of large-angle interference light cannot be eliminated. Simulation results show that when the thickness of the substrate 1 is 200 μm, the energy ratio of the substrate is very close to 150 μm, and the fingerprint identification effect is better.

The simulation result proves the effectiveness of the fingerprint light path, and the fingerprint light path principle is also suitable for liquid crystal display panels of other specifications.

The first color film substrate 2 is arranged on the upper surface of the substrate 1 and plays a role in filtering light. The first color film substrate 2 includes a red sub-pixel, a green sub-pixel and a blue sub-pixel, wherein the red sub-pixel can filter out a red light signal, the green sub-pixel can filter out a green light signal, and the blue sub-pixel can filter out a blue light signal.

The second color film substrate 3 is arranged on the lower surface of the substrate 1 and plays a role in filtering light. The second color filter substrate 3 includes a pixel unit 301, and the pixel unit 301 includes: the pixel structure comprises a red sub-pixel, a green sub-pixel and a blue sub-pixel, wherein the red sub-pixel can filter out a red light signal, the green sub-pixel can filter out a green light signal, and the blue sub-pixel can filter out a blue light signal.

Adopt the various membrane base plate of bilayer, the various membrane base plate on base plate upper strata can block most strong noise fingerprint signal, forms the light beam collimation for the fingerprint signal that the light sensor received is mostly ideal fingerprint signal or weak noise fingerprint signal, can improve the SNR of fingerprint signal, satisfies the requirement of fingerprint identification under the liquid crystal display panel pile screen.

The array substrate 4 is disposed below the second color filter substrate 3 and is disposed opposite to the second color filter substrate 3, and the array substrate 4 provides a circuit support for the display panel and serves as a switch of the display panel.

The liquid crystal 5 is disposed between the second color film substrate 3 and the array substrate 4, and the liquid crystal 5 can control the external light to enter. The working principle of the liquid crystal 5 is as follows: when the power of the array substrate 4 is turned on, the liquid crystal 5 is electrified, and under the action of an electric field, the liquid crystal 5 is arranged in order, so that light rays can easily pass through; when the array substrate 4 is in the off state, the liquid crystal 5 is in the non-energized state, and the arrangement of the liquid crystal 5 is disordered to prevent light from passing through, and fig. 2 shows the energized state of the liquid crystal 5.

The photosensor 6 is disposed on the upper surface of the array substrate 4, and is configured to receive and sense an optical signal, in this embodiment, a fingerprint optical signal, which needs to penetrate through the liquid crystal 5.

The polarizer 7 plays a role of polarization, and comprises a polarizer arranged on the lower surface of the array substrate 6, and another polarizer arranged on the upper surface of the second color film substrate 3.

The principle of optical fingerprint identification of a Liquid Crystal Display (LCD) is that light emitted by pixels is reflected by fingerprint skin, the refractive index of the finger surface is close to that of the display panel interface, the reflected light of the finger ridge is weak, and air exists between the finger valley and the display interface, so the reflection of the valley is strong. After the reflected light is received by the photosensitive sensor 6, the light signals with different intensities are converted into high and low current or voltage signals through photoelectric conversion, and then the high and low current or voltage signals are output and processed through an algorithm to obtain the fingerprint structure. Because the reflected light of the fingerprint is distributed in a certain angle range, the photosensitive sensor 6 can receive interference signals of large angles, such as a weak noise fingerprint signal and a strong noise fingerprint signal, besides a completely ideal fingerprint signal of small angles, and when the interference signals are strong, the photosensitive sensor 6 cannot identify the fingerprint information.

A Black Matrix (BM) or molybdenum oxide opening treatment may be disposed on the first color film substrate 2 directly above the photosensor 6, so that light can pass through the opening treatment. Only the upper surface of the photosensor 6 transmits light, and the back surface (i.e., the lower surface) thereof is a backlight, so that light cannot transmit therethrough.

The orthographic projection of the photosensitive sensor 6 on the second color film substrate 3 and the red sub-pixel, the green sub-pixel and the blue sub-pixel are positioned on the same straight line or form a matrix.

As shown in table 1, an orthogonal projection of the photosensor (S) on the second color film substrate 3, the red subpixel (R), the green subpixel (G), and the blue subpixel (B) form a matrix, in the first arrangement of the pixel unit and the photosensor, the photosensor is located on the other side of the pixel unit, and the sum of the widths of the red subpixel, the green subpixel, and the blue subpixel in the same pixel unit is equal to the width of the photosensor. The second arrangement of the pixel units and the photosensors is shown in bold in table 1.

The position where the photosensitive sensor 6 is placed is the gate circuit routing position, and in order to prevent the metal electrode from influencing the contrast of the liquid crystal display panel through light reflection inside the liquid crystal display panel, a light shielding layer, such as a black matrix or molybdenum oxide, needs to be added above the metal electrode. Since the light shielding layer is originally present at this position, placing the photosensor 6 at this position hardly affects the aperture ratio of the screen, and is a preferred placement method.

TABLE 1 first arrangement of pixel cells and photosensors

As shown in table 2, the orthogonal projection of the photosensor 6 on the second color filter substrate 3 is aligned with the red sub-pixel, the green sub-pixel, and the blue sub-pixel, and the arrangement of the red sub-pixel (R), the green sub-pixel (G), the blue sub-pixel (B), and the photosensor (S) is not limited and can be adjusted as required, so there are 24 arrangement manners. The RGBS arrangement mode, the photosensitive sensor (S) occupies a display area, and the screen aperture ratio is reduced. This approach may reduce the aperture ratio of the screen to some extent, thereby affecting the brightness and the endurance of the liquid crystal display.

TABLE 2 second arrangement of pixel cells and photosensors

A

B

C

D

A

B

C

D

A

B

C

D

A

B

C

D

As shown in fig. 4, a monochrome or color image can be used for fingerprint identification, the intensity contrast between the valleys and the ridges is obvious, and a detection light source is used for fingerprint identification of the display panel, wherein the detection light is visible light, such as red light, green light, blue light, red light, green light, blue-green light or infrared light.

The scheme of fingerprint identification by adopting a single-color picture comprises the following steps:

for example, when fingerprint identification is performed by using red light, only the red sub-pixel can emit light, after the red light irradiates the fingerprint, the light reflected by the fingerprint can only penetrate through the opening above the photosensitive sensor 6 and the red sub-pixel to reach the photosensitive sensor 6, and the green sub-pixel and the blue sub-pixel on the upper layer of the substrate 1 can shield large-angle red interference light (light signals reflected by other fingerprints), so that the signal-to-noise ratio of the fingerprint signal corresponding to the photosensitive sensor 6 can be greatly improved. Green or blue light can also be used as detection light, the principle being consistent with red light detection. The above detection method needs to adopt a single-color picture to perform the identification of the fingerprint under the screen.

The scheme for fingerprint identification by adopting the color picture comprises the following steps:

in order to improve the fingerprint identification experience, a color screen protection picture can be displayed when a fingerprint is unlocked, a photosensitive wavelength range can be limited by coating a film on the surface of the photosensitive sensor 6, such as a monochromatic filter film or a vapor deposition color film mode or by designing the light-emitting energy level of the photosensitive sensor 6, so that the photosensitive sensor 6 has an optical wavelength selection function, at the moment, although red light, green light or blue light can reach the surface of the photosensitive sensor 6, only light meeting the conditions can enter the photosensitive sensor 6 through screening of the film on the surface of the photosensitive sensor 6 or the wavelength selectivity of the photosensitive sensor 6. If a blue filter film is added on the surface of the photosensitive sensor 6, a full-color light source is adopted for fingerprint identification, and although the R, G and B three color lights can reach the surface of the photosensitive sensor 6, only the blue light can pass through the blue filter film. Or the light-emitting energy band inside the photosensitive sensor 6 is only sensitive to the wavelength of blue light by adjusting the energy level structure, so that a filter film does not need to be added above the photosensitive sensor 6, and when the RGB light enters the photosensitive sensor 6, only the blue light wave band acts. The mode can ensure the fingerprint unlocking function under the color picture.

The cover plate 9 is attached to the upper surface of the first color film substrate 2 through an Adhesive layer 8, and the Adhesive layer 8 is an OCA (optical Clear Adhesive) optical Adhesive used as an Adhesive. The adhesive layer 8 is colorless transparent colloid, has light transmittance of over 90 percent and good adhesive strength, can be cured at room temperature or intermediate temperature, and has small curing shrinkage.

The cover plate 9 is a glass cover plate, the protective layer 10 is a screen protector, and the cover plate 9 and the protective layer 10 have the function of resisting external impact on the display panel and have good friction resistance.

The sum of the thicknesses of the polarizer, the adhesive layer 8, the cover plate 9 and the protective layer 10 arranged above the first color film substrate 2 is 0.8 mm-1.1 mm, when the sum of the thicknesses of the polarizer, the adhesive layer 8, the cover plate 9 and the protective layer 10 arranged above the first color film substrate 2 is 1.0mm, the thicknesses of the substrates 1 are different, and the effective energy utilization rate (the ratio of the energy received by the photosensitive sensor 6 to the fingerprint reflection energy) and the fingerprint ridge and valley contrast (the energy ratio corresponding to the fingerprint ridge and valley) of the fingerprint light path can be changed accordingly.

The display device has the technical effects that the double-layer color film substrate is adopted, the color film substrate on the upper layer of the substrate can block most of strong noise fingerprint signals to form light beam collimation, so that the fingerprint signals received by the photosensitive sensor are mostly ideal fingerprint signals or weak noise fingerprint signals, the signal-to-noise ratio of the fingerprint signals can be improved, and the requirement of fingerprint identification under the liquid crystal display panel pile screen is met. When the thickness of the substrate is 100 to 300 μm, the fingerprint recognition contrast of the fingerprint recognition signal is increased and then decreased as the thickness of the substrate is increased, and when the thickness of the substrate is 200 μm, the fingerprint recognition effect is the best.

Example 2

The embodiment provides a display device, which includes a display panel as shown in fig. 5, where the display panel includes a substrate 1, a first color film substrate 2, a second color film substrate 3, an array substrate 4, a liquid crystal 5, a photosensor 6, a polarizer 7, an adhesive layer 8, a cover plate 9, and a protective layer 10.

As shown in fig. 3, the fingerprint reflected light signal collected by the photosensor 6 includes a main signal area 801, a first interference area 802 and a second interference area 803, a dotted line S1 in fig. 3 is a noise signal, a solid line S2 is a useful signal, and when the detected light wave is blue light, the light transmitted by θ 3- θ 6 is a large-angle interference light signal. Considering that the size of the photosensor 6 is not changed, the thicker the substrate 1 is, the smaller the angle θ 3- θ 6 is. The signal collected by the light sensor 6 will contain more noise, which eventually results in no fingerprint signal being recognized. However, the too low thickness of the substrate 1 may cause the light-shielding distance formed between the first color filter substrate 2 and the second color filter substrate 3 to be too short, and the color filter substrate cannot filter the interference light. In order to verify the validity of the fingerprint light path provided by the text, the fingerprint identification effect of a group of conventional liquid crystal display panels is simulated.

Experiment results show that the effective energy utilization rate (the ratio of energy received by the photosensitive sensor 6 to fingerprint reflection energy) and the fingerprint ridge and valley contrast (the energy ratio corresponding to the fingerprint ridge and valley) of a fingerprint light path can be changed along with the difference of the thickness of the substrate 1 and the fingerprint identification effect. The thickness of the substrate 1 is 100-300 μm, and the effective energy utilization rate of the fingerprint light path is reduced along with the thickening of the substrate 1. With the increase of the thickness of the substrate 1, the fingerprint contrast parameter of the fingerprint identification effect is increased and then reduced, when the thickness of the substrate 1 is increased to 300 μm, fingerprint information cannot be distinguished, at the moment, a fingerprint light path fails, and the influence of large-angle interference light cannot be eliminated. Simulation results show that when the thickness of the substrate 1 is 200 μm, the energy ratio is very close to that of a substrate with the thickness of 150 μm, and the fingerprint identification effect is better.

The simulation result proves the effectiveness of the fingerprint light path, and the principle of the fingerprint light path is also suitable for liquid crystal display panels of other specifications.

The array substrate 4 is disposed below the second color filter substrate 3 and disposed opposite to the second color filter substrate 3, and the array substrate 4 provides a circuit support for the display panel and serves as a switch of the display panel.

The liquid crystal 5 is arranged between the second color film substrate 3 and the array substrate 4, and the liquid crystal 5 can control the entrance of external light. The working principle of the liquid crystal 5 is as follows: when the power of the array substrate 4 is turned on, the liquid crystal 5 is electrified, and under the action of an electric field, the liquid crystal 5 is arranged in order, so that light rays can easily pass through; when the array substrate 4 is in the off state, the liquid crystal 5 is in the non-energized state, and at this time, the arrangement of the liquid crystal 5 is disordered to prevent light from passing through, and fig. 5 shows the energized state of the liquid crystal 5.

The light sensor 6 is disposed on the lower surface of the first color film substrate 2 and configured to receive and sense an optical signal, which is a fingerprint optical signal in this embodiment, compared with embodiment 1, in this embodiment, the fingerprint optical signal does not need to penetrate through the liquid crystal 5 and has no scattering effect of the liquid crystal, and the signal-to-noise ratio of the fingerprint optical signal is higher than that in embodiment 1.

The polarizer 7 plays a role of polarization, and comprises a polarizer arranged on the lower surface of the array substrate 6 and another polarizer arranged on the upper surface of the second color film substrate 3.

The principle of optical fingerprint identification of a Liquid Crystal Display (LCD) is that light emitted by pixels is reflected by fingerprint skin, the refractive index of the finger surface is close to that of the display panel interface, the reflected light of the finger ridge is weak, and air exists between the finger valley and the display interface, so the reflection of the valley is strong. After the reflected light is received by the photosensitive sensor 6, the light signals with different intensities are converted into high and low current or voltage signals through photoelectric conversion and output, and then the fingerprint structure is obtained through algorithm processing. Because the reflected light of the fingerprint is distributed in a certain angle range, the photosensitive sensor 6 can receive interference signals of large angles, such as a weak noise fingerprint signal and a strong noise fingerprint signal, besides a completely ideal fingerprint signal of small angles, and when the interference signals are strong, the photosensitive sensor 6 cannot identify the fingerprint information.

As shown in table 1, an orthographic projection of the photosensitive sensor (S) on the second color filter substrate 3 forms a matrix with the red sub-pixel (R), the green sub-pixel (G), and the blue sub-pixel (B), in the first arrangement of the pixel unit and the photosensitive sensor, the photosensitive sensor is located on the other side of the pixel unit, and the sum of the widths of the red sub-pixel, the green sub-pixel, and the blue sub-pixel in the same pixel unit is equal to the width of the photosensitive sensor. The second arrangement of the pixel units and the photosensors is shown in bold in table 1.

TABLE 1 first arrangement of pixel cells and photosensors

As shown in table 2, the orthographic projection of the photosensor 6 on the second color filter substrate 3 is located on the same line as the red sub-pixel, the green sub-pixel and the blue sub-pixel, and the arrangement of the red sub-pixel (R), the green sub-pixel (G), the blue sub-pixel (B) and the photosensor (S) is not limited and can be adjusted as required, so there are 24 arrangement. The RGBS arrangement mode, the photosensitive sensor (S) occupies a display area, and the screen aperture ratio is reduced. This approach may reduce the aperture ratio of the screen to some extent, thereby affecting the brightness and the endurance of the liquid crystal display.

TABLE 2 second arrangement of pixel cells and photosensors

A

B

C

D

A

B

C

D

A

B

C

D

A

B

C

D

As shown in fig. 4, the fingerprint identification can be performed by using a monochrome or color image, the intensity contrast between the valley and the ridge is relatively obvious, and the fingerprint identification is performed on the display panel by using a detection light source, wherein the detection light is visible light, such as red light, green light, blue light, red light, green light, blue-green light or infrared light.

for example, when a fingerprint is identified by using red light, only the red sub-pixel can emit light, after the red light irradiates the fingerprint, the light reflected by the fingerprint can only reach the photosensitive sensor 6 by penetrating through the opening above the photosensitive sensor 6 and the red sub-pixel, and the green sub-pixel and the blue sub-pixel on the upper layer of the substrate 1 can shield large-angle red interference light (light signals reflected by other fingerprints), so that the signal-to-noise ratio of the fingerprint signal corresponding to the photosensitive sensor 6 can be greatly improved. Green or blue light can also be used as detection light, the principle being consistent with red light detection. The above detection method needs to adopt a single-color picture to perform the identification of the fingerprint under the screen.

in order to improve the fingerprint identification experience, a color screen protection picture can be displayed when the fingerprint is unlocked, the photosensitive wavelength range can be limited by coating a film on the surface of the photosensitive sensor 6, such as a monochromatic filter film or a vapor deposition color film mode or by designing the luminous energy level of the photosensitive sensor 6, so that the photosensitive sensor 6 has the function of selecting the light wavelength, and at the moment, although red light, green light or blue light can reach the surface of the photosensitive sensor 6, only the light meeting the conditions can enter the photosensitive sensor 6 through the screening of the film on the surface of the photosensitive sensor 6 or the wavelength selectivity of the photosensitive sensor 6. If a blue filter is added on the surface of the light sensor 6 and a full-color light source is used for fingerprint identification, although the R, G and B lights can reach the surface of the light sensor 6, only the blue light can pass through the light sensor when the light is blocked by the blue filter. Or the light-emitting energy band inside the photosensitive sensor 6 is only sensitive to the wavelength of blue light by adjusting the energy level structure, so that a filter film does not need to be added above the photosensitive sensor 6, and when the RGB light enters the photosensitive sensor 6, only the blue light wave band acts. The mode can ensure the fingerprint unlocking function under the color picture.

The cover plate 9 is attached to the upper surface of the first color film substrate 2 through an Adhesive layer 8, and the Adhesive layer 8 is an OCA (optical Clear Adhesive) optical Adhesive used as an Adhesive. The adhesive layer 8 is colorless transparent colloid, has light transmittance of over 90 percent and good bonding strength, can be cured at room temperature or intermediate temperature, and has small curing shrinkage.

The display device has the technical effects that the double-layer color film substrate is adopted, the color film substrate on the upper layer of the substrate can block most of strong noise fingerprint signals to form light beam collimation, so that the fingerprint signals received by the photosensitive sensor are mostly ideal fingerprint signals or weak noise fingerprint signals, the signal-to-noise ratio of the fingerprint signals can be improved, and the requirement of fingerprint identification under the liquid crystal display panel pile screen is met. When the thickness of the substrate is 100 μm to 300 μm, the fingerprint recognition contrast of the fingerprint recognition signal increases and then decreases as the thickness of the substrate increases, and when the thickness of the substrate is 200 μm, the fingerprint recognition effect is the best.

In the foregoing embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.

The display panel and the display device provided by the embodiments of the present application are described in detail above, and the principle and the implementation of the present application are explained in the present application by applying specific examples, and the description of the embodiments above is only used to help understanding the technical solution and the core idea of the present application; those of ordinary skill in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications or substitutions do not depart from the spirit and scope of the present disclosure as defined by the appended claims.

Claims

1. A display panel, comprising:

a substrate;

the first color film substrate is arranged on the surface of one side of the substrate;

the second color film substrate is arranged on the surface of one side of the substrate, which is far away from the first color film substrate;

the photosensitive sensor is arranged on one side, away from the substrate, of the second color film substrate;

the array substrate is arranged on one side, away from the substrate, of the second color film substrate; and

the liquid crystal is arranged between the second color film substrate and the array substrate;

wherein the thickness of the substrate is 100-300 μm.

2. The display panel of claim 1,

the photosensitive sensor is arranged on the surface of one side, close to the liquid crystal, of the array substrate.

3. The display panel of claim 2,

the second color film substrate comprises a pixel unit;

each pixel unit comprises a red sub-pixel, a green sub-pixel and a blue sub-pixel.

4. The display panel of claim 3,

in the same pixel unit, the pixel unit is,

the projection of the photosensitive sensor on the second color film substrate and the red sub-pixel, the green sub-pixel and the blue sub-pixel are positioned on the same straight line, or an array is formed.

5. The display panel according to claim 1, further comprising:

the first polarizer is arranged on the surface of one side, far away from the substrate, of the first color film substrate;

the adhesive layer is arranged on the surface of one side of the first polarizer, which is far away from the first color film substrate;

the cover plate is arranged on the surface of one side of the glue layer, which is far away from the first polaroid; and

and the protective layer is arranged on the surface of one side of the cover plate, which is far away from the adhesive layer.

6. The display panel of claim 5,

the sum of the thicknesses of the first polaroid, the adhesive layer, the cover plate and the protective layer is 0.8-1.1 mm.

7. A display device comprising the display panel according to any one of claims 1 to 6.