A display panel

Abstract

An embodiment of the present invention provides a display panel comprising a display substrate and an encapsulation substrate for encapsulating the display substrate. The display substrate includes a light-emitting element layer and a photosensitive element layer, the photosensitive element layer including multiple photosensitive elements. The display panel also includes a collimating layer located on the side of the display substrate facing the encapsulation substrate. The collimating layer includes multiple colored light-shielding blocks, and the positions of the photosensitive elements correspond to the positions of the colored light-shielding blocks. The display panel provided by the embodiment of the present invention can effectively improve checkerboard effect and blurred fingerprint imaging.

Description

Technical Field

[0001] The present invention relates to the field of fingerprint unlocking technology, and in particular to a display panel. Background Art

[0002] Fingerprint recognition is an important mobile terminal user authentication method. By detecting the user's fingerprint, it can be used to identify whether the current user is the owner of the mobile terminal, so that the owner of the mobile terminal can unlock the mobile terminal's protection lock by simply pressing a finger without entering a password.

[0003] Currently, based on optical fingerprint recognition technology, the existing art has proposed an in-screen fingerprint recognition solution. By manufacturing the display layer and the photosensitive PIN diode (a diode with a PIN structure composed of a thin layer of low-doped intrinsic semiconductor layer added between P and N semiconductor materials) used for fingerprint collection on the same substrate, the overall thickness of the fingerprint detection screen is reduced, while the process manufacturing cost is reduced, making full-screen fingerprint recognition and folding screen fingerprint recognition possible. It also has the characteristics of short optical path and high transmittance compared to under-screen fingerprint recognition. In the in-screen fingerprint recognition technology, the COE (Color filter On Encapsulation) + UTG (ultra-thin glass) solution is used. The use of ultra-thin glass enables this technology to eliminate the need for polarizers, reduce the thickness above the screen, and can be applied to folding screens.

[0004] However, in the current structural design, a micro-collimation effect is achieved by opening a BM (a light-absorbing black organic material) above the PIN and using the PIN and BM. However, there are also some problems. For example, fingerprint imaging blur and checkerboard phenomenon are generated under ambient light. Under display light, although the checkerboard and imaging blur are less obvious, the reflection of each film layer in the screen causes the fingerprint valley ridge signal to account for a low proportion in the read signal. Summary of the Invention

[0005] An embodiment of the present invention provides a display panel.

[0006] As a first aspect of the present invention, a display panel is provided, comprising a display substrate and a packaging substrate for packaging the display substrate, wherein the display substrate comprises a light-emitting element layer and a photosensitive element layer, wherein the photosensitive element layer comprises a plurality of photosensitive elements, and wherein the display panel comprises a collimating layer, wherein the collimating layer is located on a side of the display substrate facing the packaging substrate, wherein the collimating layer comprises a plurality of colored shading blocks, and positions of the photosensitive elements correspond to positions of the colored shading blocks.

[0007] In some embodiments, the light-emitting element layer includes a plurality of light-emitting elements, and the position of the photosensitive element corresponds to the interval between two adjacent light-emitting elements.

[0008] In some embodiments, the collimating layer also includes a main black matrix, on which a light-shielding block opening and a filter opening are formed. The position of the filter opening corresponds to the position of the light-emitting element, and the position of the color light-shielding block corresponds to the position of the light-shielding block opening.

[0009] In some embodiments, the alignment layer further includes a buffer light-transmitting layer located between the main black matrix and the color light-shielding blocks.

[0010] In some embodiments, the colored light-shielding block is located in the light-shielding block opening.

[0011] In some embodiments, the display substrate further includes an auxiliary dimming layer, which is arranged on the side of the light-emitting element layer facing the packaging substrate, and the auxiliary dimming layer includes a shading portion and a through hole formed on the shading portion, the position of the through hole corresponds to the position of the opening of the shading block, and the position of the shading portion corresponds to the portion of the black matrix where no opening is set.

[0012] In some embodiments, the collimating layer further includes a color filter block, and the color filter block is disposed in the filter opening.

[0013] In some embodiments, the photosensitive element includes a photodiode and a storage capacitor connected in parallel with the photodiode.

[0014] In some embodiments, the shape of the light shielding block opening is axisymmetric.

[0015] In some embodiments, the packaging substrate further includes an optical cover layer, and the optical cover layer is disposed on a side of the collimating layer facing away from the display substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention.

[0017] Figure 1a A schematic diagram of the membrane structure of the current in-screen fingerprint recognition solution;

[0018] Figure 1b A schematic diagram of the PIN shape for the current in-screen fingerprint recognition solution;

[0019] Figure 1c Schematic diagram of the angle of light received by two PINs with different shapes;

[0020] Figure 1d Schematic diagram of the angle at which the PIN receives light;

[0021] Figure 1e A schematic diagram showing the ratio of fingerprint valley and ridge signals in the current in-screen fingerprint recognition solution.

[0022] Figure 1f A schematic diagram of the current in-display fingerprint recognition solution showing how display light is reflected between the various film layers within the display.

[0023] Figure 2 A schematic cross-sectional view of a display panel provided by an embodiment of the present invention;

[0024] Figure 3 A schematic cross-sectional view of another display panel provided by an embodiment of the present invention;

[0025] Figure 4 A schematic cross-sectional view of another display panel provided by an embodiment of the present invention;

[0026] Figure 5 A schematic diagram of a parallel connection of a photodiode and a storage capacitor provided by an embodiment of the present invention.

[0027] Description of reference numerals:

[0028] 1. PIN 2. BM 3. CF

[0029] 4. BM opening 5. Light shielding block opening 6. Filter block opening

[0030] 7. Color PDL 8. Light shielding 9. Through hole

[0031] 10. Storage capacitor 11. P-type region 12. PN junction

[0032] 12. N-type region 101, Cover & OCA 102, BM / CF

[0033] 103, FMLOC 104, Buffer 105, TFE

[0034] 106, EL 107, PIN 108, TFT BP

[0035] 109. Glass DETAILED DESCRIPTION

[0036] Unless otherwise defined, the technical or scientific terms used in this disclosure should have the usual meanings understood by people with ordinary skills in the field to which this disclosure belongs. The words "first", "second" and similar words used in this disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one", "an" or "the" do not indicate a quantity limitation, but rather indicate the existence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0037] The current in-screen fingerprint recognition solution uses TFE packaging above the original in-screen PIN and display module, and then adds a COE structure consisting of BM and CF. A BM opening is used above the PIN, allowing the PIN to receive light from ambient light or light carrying information after being reflected from the cover surface, and achieves a micro-collimation effect through the size ratio of the BM and PIN.

[0038] like Figure 1a As shown in the figure, it is a schematic diagram of the film layer structure of the current in-screen fingerprint recognition solution, including Cover&OCA (optical cover layer) 101, BM / CF (Color Filter, such as R resin, G resin, B resin, etc.) 102, FMLOC103, Buffer (buffer layer) 104, TFE (Thin Film Encapsulation) 105, EL (display module) 106, PIN 107, TFT BP 108, and Glass 109. It can be seen that after TFE is used for encapsulation above the PIN SENSOR 1 and the display module, BM 2 and CF 3 are added to form a COE structure. By forming a BM opening 4 above the PIN SENSOR 1, the PIN SENSOR 1 can receive ambient light or display light carrying information after being reflected by the surface of the optical cover layer (the arrow line in the figure indicates the light). In addition, by controlling the size ratio of BM 2 and PIN SENSOR 1, a micro-collimation effect is also achieved.

[0039] In order to increase the valley-ridge difference signal during fingerprint collection, a larger PIN area is required to increase the charge storage capacity; in order to increase the proportion of fingerprint valley-ridge difference under the same charge amount and obtain clearer fingerprint details, a higher PPI of the PIN is required. However, due to the design of integrating display and collection in the screen, it is necessary to consider the parasitic capacitance between the collection module and the display module and the problem of the film layer blocking the PIN light collection during the design. In order not to affect the normal function of the display module, the size and placement of the PIN are limited. Therefore, if the PIN area is increased, it will cause the pixel circuit to appear as follows Figure 1b In the structure shown, the PIN has two shapes: a long strip and two spliced ​​strips. Although the effective area of ​​the two different PIN shapes is the same, after adding the BM opening, the light angles that the two different PIN shapes can receive are different, as shown in the figure. Figure 1c As shown in the figure, taking a 50 μm long strip PIN and a 13 μm height between the PIN and the BM as an example, the length of the two spliced ​​PINs is 25 μm. The long strip PIN can receive light within a range of 75° from above, and the angle range of the ambient light incident on the screen after passing through the finger is 0 to 75°. The two spliced ​​PINs can receive light within a range of 62° from above, and the angle range of the ambient light incident on the screen after passing through the finger is 0 to 62°. In other words, the two different PIN shapes can receive light at different angles, resulting in a checkerboard pattern of alternating light and dark in the readout image.

[0040] At the same time, due to the large light collection angle and the presence of other materials such as Cover and OCA (Optically Clear Adhesive) above the BM, the collimation effect is not ideal when the area is large. Figure 1d As shown in the figure, the thickness of the cover, OCA and other films above the BM in actual products is more than 200um. As a result, the PIN can not only receive ambient light from directly above, but also receive obliquely incident ambient light from the upper left and upper right within a range of 350um. According to the current PPI calculation of the PIN, the size of each pixel is 64um, resulting in a single pixel being affected by the ambient light within a range of 10 pixels to the upper left and upper right, resulting in blurred fingerprint imaging.

[0041] In view of this, an embodiment of the present invention proposes that a colored light-shielding block can be added above the PIN to remove interference from ambient light, so that the PIN can only receive display light and form an image only through display light, thereby solving the problems of checkerboard phenomenon and blurred fingerprint imaging.

[0042] Accordingly, an embodiment of the present invention provides a display panel, which may include a display substrate and a packaging substrate for packaging the display substrate, the display substrate including a light-emitting element layer and a photosensitive element layer, the photosensitive element layer including a plurality of photosensitive elements, and is characterized in that the display panel includes a collimating layer, the collimating layer is located on the side of the display substrate facing the packaging substrate, the collimating layer includes a plurality of colored shading blocks, and the positions of the photosensitive elements correspond to the positions of the colored shading blocks.

[0043] Among them, the light-emitting element layer is the display module EL, the photosensitive element is used to detect the light irradiated on the surface of the photosensitive element. The ambient light is mostly red light after passing through the finger. The color filter block can be the color PDL (pixel definition layer), and the color of the color shading block can be any color with low transmittance in the red light spectrum, such as cyan.

[0044] By setting a colored light-shielding block at a position corresponding to the position of the photosensitive element, the red light after the ambient light passes through the finger can be blocked by the colored filter block and will not irradiate the surface of the photosensitive element. The photosensitive element only forms an image based on the display light emitted by the light-emitting element, avoiding interference from ambient light and effectively improving the checkerboard phenomenon and blurred fingerprint imaging.

[0045] In some embodiments, the light-emitting element layer includes a plurality of light-emitting elements, and the position of the photosensitive element corresponds to the interval between two adjacent light-emitting elements.

[0046] The position of the photosensitive element corresponds to the interval between two adjacent light-emitting elements, so that the photosensitive element can detect the light emitted by the light-emitting element and then reflected and irradiated onto the surface of the photosensitive element.

[0047] In some embodiments, the collimating layer also includes a main black matrix, on which a light-shielding block opening and a filter opening are formed. The position of the filter opening corresponds to the position of the light-emitting element, and the position of the color light-shielding block corresponds to the position of the light-shielding block opening.

[0048] The light shielding block openings on the main black matrix BM are used for both the color light shielding blocks to absorb ambient light that passes through the finger and for transmitting useful light reflected from the display light inside the screen by the finger. The filter openings are used to transmit the display light.

[0049] In some embodiments, the alignment layer further includes a buffer light-transmitting layer located between the main black matrix and the color light-shielding blocks.

[0050] like Figure 2As shown, it is a cross-sectional schematic diagram of a display substrate provided by an embodiment of the present disclosure, wherein the display panel may further include TFT BP 108 and Glass 109, the packaging substrate further includes Cover&OCA 101, a buffer light-transmitting layer (FMLOC 103, Buffer 104 and TFE 105) is further provided on the side of the collimating layer facing the display substrate, the display substrate includes a light-emitting element layer 106 and a PIN SENSOR 107, the collimating layer includes BM / CF 102, a color PDL 7 and a buffer light-transmitting layer, a light-shielding block opening 5 and a filter block opening 6 are formed on the main black matrix BM 2, and the color PDL 7 is arranged on the side of the buffer light-transmitting layer facing the display substrate at a position corresponding to the position of the light-shielding block opening 5. The color PDL 7 can block ambient light (indicated by the arrow perpendicular to the direction of the color PDL 7 in the figure) and the red light passing through the finger, thereby removing interference from ambient light and effectively improving the checkerboard phenomenon and blurred fingerprint imaging.

[0051] In addition to placing the color light-shielding blocks on the side of the buffer light-transmitting layer facing the display substrate, the color filter blocks can also be directly placed in the light-shielding block openings of the main black matrix. Accordingly, in some embodiments, the color light-shielding blocks are located in the light-shielding block openings.

[0052] like Figure 3 As shown, it is a cross-sectional schematic diagram of another display substrate provided by an embodiment of the present disclosure, wherein the display panel may further include TFT BP 108 and Glass 109, the packaging substrate further includes Cover & OCA 101, a buffer light-transmitting layer (FMLOC 103, Buffer 104 and TFE 105) is further provided on the side of the alignment layer facing the display substrate, the display substrate includes a light-emitting element layer 106 and a PIN SENSOR 107, the alignment layer includes BM / CF 102, color PDL 7 and a buffer light-transmitting layer, and a light-shielding block opening 5 and a filter block opening 6 are formed on the main black matrix BM 2. However, unlike the embodiment of FIG. Figure 2 The difference is that the color PDL 7 is directly set in the light-shielding block opening 5 of the main black matrix BM 2. The color PDL 7 can block the ambient light (indicated by the arrow perpendicular to the direction of the color PDL 7 in the figure) and the red light passing through the finger, thereby removing the interference of the ambient light and effectively improving the checkerboard phenomenon and blurred fingerprint imaging.

[0053] The colored light-shielding block can be located in any layer above the photosensitive element, that is, in addition to being located in the light-shielding block opening of the BM and on the side of the buffer light-transmitting layer facing the display substrate, it can also be located in any other position that can absorb the ambient light at the light-shielding block opening of the BM.

[0054] In addition, if Figure 1e and Figure 1f As shown in the figure, in current in-display fingerprint recognition solutions, due to the reflection of display light between the various film layers within the display, the invalid signal caused by reflected light (hereinafter referred to as base) accounts for a large proportion of the readout signal. Experiments have shown that nearly 90% of the light received by the PIN sensor (shown as total output in the figure) comes from light reflected between the film layers within the display (shown as output of base in the figure), while less than 10% is light carrying information that is reflected back from the finger (shown as output of finger in the figure). In addition, the amount of charge stored in the PIN has an upper limit, so the proportion of fingerprint valley and ridge signals that can be obtained is relatively low. Figure 1f The light rays ② and ⑥ shown in the figure are the light carrying information reflected back from the light rays ① and ⑤ hitting the finger, and the light rays ④ and ⑧ are the light reflected from the light rays ③ and ⑦ between the film layers in the screen.

[0055] In view of this, embodiments of the present invention propose that an auxiliary dimming layer can be provided within the screen to at least partially eliminate interference from light reflected between the various film layers within the screen. Accordingly, in some embodiments, the display substrate further includes an auxiliary dimming layer, which is provided on the side of the light-emitting element layer facing the packaging substrate. The auxiliary dimming layer includes a light-shielding portion and a through-hole formed in the light-shielding portion. The position of the through-hole corresponds to the position of the light-shielding block opening, and the position of the light-shielding portion corresponds to the portion of the black matrix where no opening is provided.

[0056] like Figure 4 As shown, it is a cross-sectional schematic diagram of another display substrate provided by an embodiment of the present disclosure, wherein the display panel may further include TFT BP 108 and Glass 109, the packaging substrate further includes Cover & OCA 101, a buffer light-transmitting layer (FMLOC 103, Buffer 104 and TFE 105) is further provided on the side of the alignment layer facing the display substrate, the display substrate includes a light-emitting element layer 106 and a PIN SENSOR 107, the alignment layer includes BM / CF 102, color PDL 7 and a buffer light-transmitting layer, and a light-shielding block opening 5 and a filter block opening 6 are formed on the main black matrix BM 2. Figure 3 The same as shown is that the color PDL 7 is directly set in the light shielding block opening 5 of the main black matrix BM 2. The color PDL 7 can block the ambient light (indicated by the arrow perpendicular to the direction of the color PDL 7 in the figure) and the red light passing through the finger, thereby removing the interference of the ambient light and effectively improving the checkerboard phenomenon and the fuzzy fingerprint imaging. Figure 3The difference shown is that the side of TFE 105 facing the display substrate is also provided with an auxiliary dimming layer. The auxiliary dimming layer includes a light shielding portion (black PDL) 8 and a through hole 9 formed in the light shielding portion. The position of the through hole corresponds to the position of the light shielding block opening 5 (i.e., the position of the color filter block), and the position of the light shielding portion 8 corresponds to the portion of the main black matrix BM 2 without an opening. Using BM 2 and light shielding portion 8 to form a collimating structure limits the angle of light that can reach the photosensitive element. This is equivalent to using black PDL to block light reflected between the various film layers within the screen, effectively reducing the base caused by reflected light in the light received by the photosensitive element, thereby increasing the proportion of useful light carrying information and optimizing the imaging effect.

[0057] It should be noted that if Figure 2 、 Figure 3 and Figure 4 As shown, the display light will also pass through the color PDL 7 and the shading portion 8. Since the light emitted by the light-emitting element contains red, green and blue, the red display light passing through the color PDL 7 will also be absorbed, and the light passing through the shading portion 8 will also be blocked. Although this will cause the light intensity to decrease, the display light can still be used for imaging by simply increasing the light intensity of the display light, and the problem of reduced light intensity is easily solved.

[0058] In some embodiments, the collimating layer further includes a color filter block, and the color filter block is disposed in the filter opening.

[0059] The color filter block is used to convert the light emitted by the light-emitting element into colored display light.

[0060] As previously mentioned, there is an upper limit to the amount of charge stored in a PIN, resulting in a lower proportion of fingerprint valley and ridge signals. Embodiments of the present invention propose that by increasing the upper limit of the PIN's charge storage, the proportion of fingerprint valley and ridge signals can also be effectively increased. Accordingly, in some embodiments, the photosensitive element includes a photodiode and a storage capacitor connected in parallel with the photodiode.

[0061] The photosensitive diode is a PIN. It should be understood that other elements capable of detecting light may also be used as photosensitive elements.

[0062] like Figure 5As shown in FIG. 1 , a schematic diagram of a parallel connection of a photodiode and a storage capacitor provided in an embodiment of the present invention is shown. The PIN and the storage capacitor 10 are connected in parallel. Specifically, one end of the storage capacitor 10 is electrically connected to the positive electrode of the PIN close to the P-type region, and the other end of the storage capacitor 10 is electrically connected to the negative electrode of the PIN close to the N-type region. This increases the upper limit of the amount of charge stored in the PIN, increases the charge carrying capacity of the PIN, and increases the upper limit of light reception, ensuring that fingerprint imaging can be used under strong light. It can also achieve the same purpose of increasing the valley-ridge difference as increasing the PIN area.

[0063] Furthermore, it should be noted that, in the embodiment of the present invention, the position of the photosensitive element corresponds to the position of the color light-shielding block, which in turn corresponds to the position of the light-shielding block opening (i.e., the opening of the main black matrix BM). In other words, the position of the photosensitive element PIN sensor also corresponds to the position of the light-shielding block opening. This is equivalent to the PIN sensor and the BM opening forming a collimating hole. While setting the storage capacitor, it is also necessary to ensure that the collimating hole is symmetrically designed (e.g., square, circular, etc.) to ensure that light irradiating the PIN sensor from all angles is evenly distributed, thereby avoiding the generation of a checkerboard effect or other uneven images.

[0064] Accordingly, in some embodiments, the shape of the light shielding block opening is axisymmetric.

[0065] In some embodiments, the packaging substrate further includes an optical cover layer, and the optical cover layer is disposed on a side of the collimating layer facing away from the display substrate.

[0066] Among them, the optical cover layer is as follows Figure 2 、 Figure 3 、 Figure 4 Sections of Cover&OCA 101 are shown in .

[0067] It will be understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present invention, and the present invention is not limited thereto. Those skilled in the art will appreciate that various modifications and improvements can be made without departing from the spirit and substance of the present invention, and such modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A display panel comprising a display substrate and a packaging substrate for packaging the display substrate, wherein the display substrate comprises a light-emitting element layer and a photosensitive element layer, wherein the photosensitive element layer comprises a plurality of photosensitive elements, wherein: The display panel includes a collimating layer, which is located on a side of the display substrate facing the packaging substrate, and includes a plurality of colored light-shielding blocks. The collimating layer also includes a main black matrix, on which light-shielding block openings and filter openings are formed. The positions of the filter openings correspond to the positions of the light-emitting elements, and the positions of the colored light-shielding blocks correspond one-to-one with the positions of the light-shielding block openings. The positions of the photosensitive elements correspond one-to-one with the positions of the colored light-shielding blocks. The collimating layer further includes a buffer light-transmitting layer located between the main black matrix and the color light-shielding block; The display substrate also includes an auxiliary dimming layer, which is arranged between the light-emitting element layer and the buffer light-transmitting layer. The auxiliary dimming layer includes a shading portion and a through hole formed on the shading portion. The position of the through hole corresponds to the position of the opening of the shading block, and the position of the shading portion corresponds to a portion of the black matrix where no opening is set.

2. The display panel according to claim 1, wherein: The light emitting element layer includes a plurality of light emitting elements, and the position of the photosensitive element corresponds to the interval between two adjacent light emitting elements.

3. The display panel according to claim 1, wherein: The colored light-shielding block is located in the light-shielding block opening.

4. The display panel according to claim 1, wherein: The collimating layer further includes a color filter block, and the color filter block is disposed in the filter opening.

5. The display panel according to any one of claims 1 to 4, wherein: The photosensitive element includes a photosensitive diode and a storage capacitor connected in parallel with the photosensitive diode.

6. The display panel according to claim 5, wherein: The shape of the light shielding block opening is axisymmetric.

7. The display panel according to claim 6, wherein: The packaging substrate further includes an optical cover layer, which is disposed on a side of the alignment layer facing away from the display substrate.

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