Display device

The embodiment of the present application discloses a display device, including a display panel and an ultrasonic fingerprint sensor. The display panel includes a substrate and a thin film transistor arranged on the substrate, and the substrate is provided with a via hole; the ultrasonic fingerprint sensor is fabricated on a side of the substrate away from the thin film transistor to reduce the thickness of the display device.

FIELD OF THE INVENTION

The present application relates to a display technology field, and more particularly to a display device.

BACKGROUND OF THE INVENTION

Ultrasonic fingerprint recognition is to scan the finger with a specific frequency ultrasonic wave emitted by the fingerprint module. Since ultrasonic waves are absorbed, penetrated, and reflected differently when they reach the surface of different materials, the difference in acoustic impedance between skin and air or different skin layers can be used to identify the location of the crest & valley of the fingerprint. Ultrasonic fingerprint recognition possesses the following advantages: it possesses stronger penetrability, and can perform deep subcutaneous fingerprint recognition and can identify living bodies, so the security of the program is higher; it is not easily interfered by oil stains, water stains and strong light.

In research and practice of the prior art, the inventor of the present application found that the known ultrasonic fingerprint recognition integrated solution is to stick the ultrasonic fingerprint module outside the display screen, which will increase the cost, increase the thickness of the screen, and reduce the comfort of use.

SUMMARY OF THE INVENTION

The embodiment of the present application provides a display device to reduce the thickness of the display device.

The embodiment of the present application provides a display device, comprising:a display panel, wherein the display panel comprises a substrate and a thin film transistor arranged on the substrate, and the substrate is provided with a via hole; andan ultrasonic fingerprint sensor, wherein the ultrasonic fingerprint sensor comprises:a first electrode, wherein the first electrode is arranged on a side of the substrate away from the thin film transistor; the first electrode is electrically connected to the thin film transistor through the via hole;a first insulating layer, wherein the first insulating layer is arranged on a side of the first electrode away from the thin film transistor;a piezoelectric layer, wherein the piezoelectric layer is arranged on a side of the first insulating layer away from the thin film transistor;a second electrode, wherein the second electrode is arranged on a side of the piezoelectric layer away from the thin film transistor; anda protective layer, wherein the protective layer is arranged on a side of the second electrode away from the thin film transistor;the thin film transistor comprises a first thin film transistor and a second thin film transistor insulated from each other, and the display panel further comprises a light emitting device provided on the first thin film transistor, and the light emitting device is electrically connected to the first thin film transistor, and the first electrode is electrically connected to the second thin film transistor;there are a plurality of first electrodes, and the second electrode is a surface electrode, and the plurality of first electrodes overlaps one of the second electrodes.

Optionally, in some embodiments of the present application, the display device comprises a first flexible circuit board and a second flexible circuit board;the first flexible circuit board is bonded on the substrate, and the second flexible circuit board is bonded on the side of the substrate away from the thin film transistor; the first flexible circuit board is electrically connected to the first thin film transistor and the second thin film transistor, and the second flexible circuit board is electrically connected to the second electrode.

Optionally, in some embodiments of the present application, the substrate is provided with a first bonding pad, a second bonding pad and a third bonding pad, and the first bonding pad is connected to the first thin film transistor, and the second bonding pad is connected to the second thin film transistor;the display panel further comprise a lead, and the lead is arranged on a side surface of the substrate, and the third bonding pad is connected to the second electrode through the lead;the display device further comprises a flexible circuit board, and the flexible circuit board is bonded and connected to the first bonding pad, the second bonding pad and the third bonding pad, respectively.

Optionally, in some embodiments of the present application, the first electrode is respectively overlapped with the first thin film transistor and the second thin film transistor, and the first electrode is a light-shielding electrode.

Optionally, in some embodiments of the present application, the thin film transistor comprises a buffer layer, an active layer, a second insulating layer, a first metal layer, a third insulating layer, a second metal layer, a fourth insulating layer, a third metal layer and planarization layer, which are sequentially arranged on substrate;the via hole further penetrates the buffer layer, the second insulating layer, the third insulating layer and the fourth insulating layer;the active layer comprises a first active part and a second active part, the first metal layer comprises a first gate and a second gate, and the third metal layer comprises a first source, a second source, a first drain and a second drain;the first active part, the first gate, the first source and the first drain form the first thin film transistor; the second active part, the second gate, the second source and the second drain form the second thin film transistor, and the second drain is connected to the first electrode through the via hole.

Optionally, in some embodiments of the present application, a plurality of the first electrodes are arranged in rows and columns, and at least one row or at least one column of the first electrodes is connected to one of the second thin film transistors.

Optionally, in some embodiments of the present application, the display panel further comprises an encapsulation layer sequentially arranged on the thin film transistor, and the encapsulation layer covers the light emitting device.

Optionally, in some embodiments of the present application, a hole structure is arranged in the protective layer.

The embodiment of the present application further provides a display device, comprising:a display panel, wherein the display panel comprises a substrate and a thin film transistor arranged on the substrate, and the substrate is provided with a via hole; andan ultrasonic fingerprint sensor, wherein the ultrasonic fingerprint sensor comprises:a first electrode, wherein the first electrode is arranged on a side of the substrate away from the thin film transistor; the first electrode is connected to the thin film transistor through the via hole;a first insulating layer, wherein the first insulating layer is arranged on a side of the first electrode away from the thin film transistor;a piezoelectric layer, wherein the piezoelectric layer is arranged on a side of the first insulating layer away from the thin film transistor;a second electrode, wherein the second electrode is arranged on a side of the piezoelectric layer away from the thin film transistor; anda protective layer, wherein the protective layer is arranged on a side of the second electrode away from the thin film transistor.

Optionally, in some embodiments of the present application, the thin film transistor comprises a first thin film transistor and a second thin film transistor insulated from each other, and the display panel further comprises a light emitting device provided on the first thin film transistor, and the light emitting device is electrically connected to the first thin film transistor, and the first electrode is electrically connected to the second thin film transistor.

Optionally, in some embodiments of the present application, the display device comprises a first flexible circuit board and a second flexible circuit board;the first flexible circuit board is bonded on the substrate, and the second flexible circuit board is bonded on the side of the substrate away from the thin film transistor; the first flexible circuit board is electrically connected to the first thin film transistor and the second thin film transistor, and the second flexible circuit board is electrically connected to the second electrode.

Optionally, in some embodiments of the present application, the substrate is provided with a first bonding pad, a second bonding pad and a third bonding pad, and the first bonding pad is connected to the first thin film transistor, and the second bonding pad is connected to the second thin film transistor;the display panel further comprise a lead, and the lead is arranged on a side surface of the substrate, and the third bonding pad is connected to the second electrode through the lead;the display device further comprises a flexible circuit board, and the flexible circuit board is bonded and connected to the first bonding pad, the second bonding pad and the third bonding pad, respectively.

Optionally, in some embodiments of the present application, the first electrode is respectively overlapped with the first thin film transistor and the second thin film transistor, and the first electrode is a light-shielding electrode.

Optionally, in some embodiments of the present application, the thin film transistor comprises a buffer layer, an active layer, a second insulating layer, a first metal layer, a third insulating layer, a second metal layer, a fourth insulating layer, a third metal layer and planarization layer, which are sequentially arranged on substrate;the via hole further penetrates the buffer layer, the second insulating layer, the third insulating layer and the fourth insulating layer;the active layer comprises a first active part and a second active part, the first metal layer comprises a first gate and a second gate, and the third metal layer comprises a first source, a second source, a first drain and a second drain;the first active part, the first gate, the first source and the first drain form the first thin film transistor; the second active part, the second gate, the second source and the second drain form the second thin film transistor, and the second drain is connected to the first electrode through the via hole.

Optionally, in some embodiments of the present application, there are a plurality of first electrodes, and the second electrode is a surface electrode, and the plurality of first electrodes overlaps one of the second electrodes.

Optionally, in some embodiments of the present application, a plurality of the first electrodes are arranged in rows and columns, and at least one row or at least one column of the first electrodes is connected to one of the second thin film transistors.

Optionally, in some embodiments of the present application, the display panel further comprises an encapsulation layer sequentially arranged on the thin film transistor, and the encapsulation layer covers the light emitting device.

Optionally, in some embodiments of the present application, the display panel further comprises an array substrate, a liquid crystal layer and an opposite substrate, and the array substrate comprises the substrate, the thin film transistor and a pixel electrode arranged on the thin film transistor.

Optionally, in some embodiments of the present application, the first insulating layer is doped with conductive particles. The conductive particles can be metal particles, for instance, one or more of nickel, gold and silver can coexist. In addition, graphite particles with excellent conductivity can also be employed instead of metal particles. The first insulating layer is doped with conductive particles to enhance the conductivity of the first electrode, thereby improving the performance of the ultrasonic fingerprint sensor.

Optionally, in some embodiments of the present application, a hole structure is arranged in the protective layer to shield external interference sound and absorb external impact.

The display device of the embodiment of the present application comprises a display panel and an ultrasonic fingerprint sensor. The display panel includes a substrate and a thin film transistor arranged on the substrate, and the substrate is provided with a via hole; the ultrasonic fingerprint sensor is fabricated on a side of the substrate away from the thin film transistor to reduce the thickness of the display device.

Besides, the ultrasonic fingerprint sensor comprises a first electrode, a first insulating layer, a piezoelectric layer, a second electrode and a protective layer; the first electrode is arranged on a side of the substrate away from the thin film transistor; the first electrode is connected to the thin film transistor through the via hole; the first insulating layer is arranged on a side of the first electrode away from the thin film transistor; the piezoelectric layer is arranged on a side of the first insulating layer away from the thin film transistor; the second electrode is arranged on a side of the piezoelectric layer away from the thin film transistor; the protective layer is arranged on a side of the second electrode away from the thin film transistor to protect the ultrasonic fingerprint sensor.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Embodiments of the present application are described in detail with the technical matters, structural features, achieved objects, and effects with reference to the accompanying drawings as follows. It is clear that the described embodiments are part of embodiments of the present application, but not all embodiments. Based on the embodiments of the present application, all other embodiments to those of skilled in the premise of no creative efforts obtained, should be considered within the scope of protection of the present application. Besides, it should be understood that the specific embodiments described herein are merely for illustrating and explaining the present application and are not intended to limit the present application. In this application, if no explanation is made to the contrary, the orientation words used such as “upper” and “lower” usually refer to the upper and lower of the device in actual use or working state, which specifically are the directions of the drawing in the figures; and “inner” and “outer” refer to the outline of the device.

The embodiment of the present application provides a display panel. The detail descriptions are introduced below. It should be noted that the order of description in the following embodiments is not meant to limit the preferred order of the embodiments.

Please refer toFIG.1. The embodiment of the present application provides a display device100, comprising a display panel10and an ultrasonic fingerprint sensor20.

The display panel10comprises a substrate11and a thin film transistor12arranged on the substrate11. The substrate11is provided with a via hole111.

The ultrasonic fingerprint sensor20is fabricated on a side of the substrate11away from the thin film transistor12. The ultrasonic fingerprint sensor20is connected to the thin film transistor12through the via hole111.

In the display device100of the embodiment of the present application, the ultrasonic fingerprint sensor20is fabricated on a side of the substrate11away from the thin film transistor12to reduce the thickness of the display device100.

Optionally, the ultrasonic fingerprint sensor20comprises a first electrode21, a first insulating layer22, a piezoelectric layer23, a second electrode24and a protective layer25.

The first electrode21is arranged on a side of the substrate11away from the thin film transistor12. The first electrode21is connected to the thin film transistor12through the via hole111. The first insulating layer22is arranged on a side of the first electrode21away from the thin film transistor12. The piezoelectric layer23is arranged on a side of the first insulating layer22away from the thin film transistor12. The second electrode24is arranged on a side of the piezoelectric layer23away from the thin film transistor12. The protective layer25is arranged on a side of the second electrode24away from the thin film transistor12to protect the ultrasonic fingerprint sensor.

In the display device100of this embodiment, the first electrode21, the first insulating layer22, the piezoelectric layer23, the second electrode24and the protective layer25are sequentially formed on the side of the substrate11away from the thin film transistor12, to avoid the use of external mounting method to arrange the ultrasonic fingerprint sensor20, thereby making the display device100thinner. In addition, the arrangement of the protective layer25reduces the risk of water and oxygen entering the inside of the ultrasonic fingerprint sensor20and reduces the risk of being scratched.

In some embodiments, the first electrode21can be formed on a side of the substrate11away from the thin film transistor12; the piezoelectric layer23, the second electrode24and the protective layer25can be adhered on the first electrode21. That is, the material of the first insulating layer22comprises insulating glue. Compared with the completely externally mounted method, this arrangement also achieves the effect of making the display device100thinner.

The display panel10further comprises a reading circuit. The process of fingerprint recognition in this embodiment is to provide the voltage to the first electrode21and the second electrode24, and the piezoelectric layer23converts electrical energy into mechanical energy due to the voltage difference between the first electrode21and the second electrode24, and emits the ultrasound. The finger receives the ultrasonic wave and reflects it back to the piezoelectric layer23. The piezoelectric layer23converts mechanical energy into electrical energy, and a voltage is formed at both ends of the piezoelectric layer23. Since the phases of the reflected ultrasonic waves from the finger crest and the finger valley are different, the first electrodes21in different regions correspondingly induce different induced charges, and the fingerprint image is recognized by the reading circuit.

Optionally, the ultrasonic fingerprint sensor20may be correspondingly arranged in a partial region of the display panel10to realize a partial fingerprint recognition; or it can also be correspondingly arranged in the display area of the entire display panel10to realize comprehensive fingerprint recognition.

Optionally, the display panel10may be a light emitting diode display panel, such as an organic light emitting diode display panel or a quantum dot light emitting diode display panel; or it can also be a liquid crystal display panel, a micro light emitting diode display panel, or a mini light emitting diode display panel.

In one embodiment of the present application, an organic light emitting diode display panel is illustrated for description, as shown inFIG.1, but is not limited thereto. Optionally, the thin film transistor12comprises a first thin film transistor T1and a second thin film transistor T2insulated from each other. The display panel10further comprises a light emitting device13provided on the first thin film transistor T1, and the light emitting device13is electrically connected to the first thin film transistor T1. The first electrode21is electrically connected to the second thin film transistor T2.

The display panel10further comprises an encapsulation layer14sequentially arranged on the thin film transistor12, and the encapsulation layer14covers the light emitting device13.

The light emitting device13comprises a pixel electrode131, an organic light emitting layer132and an opposite electrode133. The encapsulation layer14is arranged on the light emitting device13.

Optionally, the display panel10further comprises a touch layer15, and the touch layer15is arranged on the encapsulation layer14.

In some embodiments, please refer toFIG.2. Optionally, the display panel10is a liquid crystal display panel. The display panel10further comprises an array substrate Tc, a liquid crystal layer Qt and an opposite substrate Cf. The array substrate Tc comprises the substrate11, the thin film transistor12and a pixel electrode131arranged on the thin film transistor12.

Optionally, the material of the first electrode21can be oxides such as indium tin oxide, indium zinc oxide, etc.; it can also be various conductive metals, alloys, compounds and mixtures thereof, for instance, gold, silver, platinum, copper, tungsten, molybdenum, iron, aluminum, aluminum-silicon, aluminum-titanium, metal material nitrides, etc. can be adopted.

Optionally, the material of the first insulating layer22may be at least one of silicon nitride, silicon oxide and organic materials; for instance, transparent photoresist, epoxy resin, polyimide, polyvinyl alcohol, polymethyl methacrylate, polystyrene, etc.

Optionally, the material of the piezoelectric layer23may be polyvinylidene fluoride (PVDF) and its copolymers, polypropylene or piezoelectric crystals.

Optionally, the material of the second electrode24can be oxides such as indium tin oxide, indium zinc oxide, etc.; it can also be various conductive metals, alloys, compounds and mixtures thereof, for instance, gold, silver, platinum, copper, tungsten, molybdenum, iron, aluminum, aluminum-silicon, aluminum-titanium, metal material nitrides, etc. can be adopted.

Optionally, the material of the protective layer25may be an inorganic material, such as silicon nitride, silicon oxide, aluminum oxide or silicon oxynitride.

In some embodiments, the material of the first electrode21may be indium tin oxide to improve the uniformity, flatness and oxygen resistance of the first electrode21; in addition, since indium tin oxide does not react with polyvinylidene fluoride (PVDF), the stability of the ultrasonic fingerprint sensor20can be improved.

The material of the second electrode24may be silver. Since silver possesses a low resistivity and good uniformity, the conductivity and stability of the second electrode24can be improved.

Optionally, it needs to be explained that in the circuit structure, the reading circuit comprises the second thin film transistor T2.

Optionally, referring toFIG.3, there are a plurality of first electrodes21, and the second electrode24is a surface electrode. The plurality of first electrodes21overlaps one of the second electrodes24.

The arrangement that the plurality of first electrodes21correspond to one second electrode24simplifies the manufacturing process and the layout structure.

Specifically, the plurality of the first electrodes21are arranged in rows and columns, and at least one row or at least one column of the first electrodes21is connected to one of the second thin film transistors T2.

In some embodiments, it can be that one first electrode21is correspondingly connected to one second thin film transistor T2.

Optionally, the shape of the first electrode21may be a circle, a rhombus, a rectangle, a rounded rectangle, a regular pentagon, a regular hexagon or the like. In this embodiment, a rectangle is taken as an illustration, but it is not limited to this.

Optionally, in some embodiments of the present application, referring toFIG.4, the first insulating layer22is doped with conductive particles221. The conductive particles221can be metal particles, for instance, one or more of nickel, gold and silver can coexist. In addition, graphite particles with excellent conductivity can also be employed instead of metal particles. The first insulating layer22is doped with conductive particles to enhance the conductivity of the first electrode21, thereby improving the performance of the ultrasonic fingerprint sensor20.

Optionally, in some embodiments of the present application, referring toFIG.4, a hole structure251can be further arranged in the protective layer25to shield external interference sound and absorb external impact.

Optionally, referring toFIG.5andFIG.6, the display device100comprises a first flexible circuit board31and a second flexible circuit board32.

The first flexible circuit board31is bonded on the substrate11. The second flexible circuit board32is bonded to the side of the substrate11away from the thin film transistor12. The first flexible circuit board31is electrically connected to the first thin film transistor T1and the second thin film transistor T2. The second flexible circuit board32is electrically connected to the second electrode24.

The display device100of this embodiment adopts the first flexible circuit board31and the second flexible circuit board32to connect the display panel10and the ultrasonic fingerprint sensor20correspondingly, so as to reduce the loading.

Optionally, in some embodiments, the display device100of the embodiment of the present application may also employs a flexible circuit board30to electrically connect the display panel10and the ultrasonic fingerprint sensor20at the same time. Please refer toFIG.7andFIG.8. The substrate11is provided with a first bonding pad112, a second bonding pad113and a third bonding pad114. The first bonding pad112is connected to the first thin film transistor T1. The second bonding pad113is connected to the second thin film transistor T2. The first bonding pad112and the second bonding pad113are alternately arranged.

The display panel10further comprises a lead16, and the lead16is arranged on a side surface of the substrate11. The third bonding pad114is connected to the second electrode24through the lead16.

The display device100further comprises a flexible circuit board30. The flexible circuit board30is bonded and connected to the first bonding pad112, the second bonding pad113and the third bonding pad114, respectively.

In this embodiment, the flexible circuit board30is employed to electrically connect the display panel10and the ultrasonic fingerprint sensor20at the same time, saving a flexible circuit board.

An option for the reading circuit, the first electrode21is overlapped with the first thin film transistor T1and the second thin film transistor T2, and the first electrode21is a light-shielding electrode.

The first electrode21is a light-shielding electrode, and the first electrode21is overlapped with the first thin film transistor T1and the second thin film transistor T2. It achieves the effect of employing the first electrode21to shield the first thin film transistor T1and the second thin film transistor T2, to avoid that light is irradiated to the first thin film transistor T1and the second thin film transistor T2, and the process of preparing the light-shielding layer of the display panel10is eliminated.

Optionally, the thin film transistor12comprises a buffer layer121, an active layer122, a second insulating layer123, a first metal layer124, a third insulating layer125, a second metal layer126, a fourth insulating layer127, a third metal layer128and planarization layer129, which are sequentially arranged on substrate11.

The via hole111further penetrates the buffer layer121, the second insulating layer123, the third insulating layer125and the fourth insulating layer127.

The active layer122comprises a first active part12aand a second active part12b. The first metal layer124comprises a first gate G1and a second gate G2. The third metal layer128comprises a first source S1, a second source S2, a first drain D1and a second drain D2.

The first active part12a, the first gate G1, the first source S1and the first drain D1form the first thin film transistor T1. The second active part12b, the second gate G2, the second source S2and the second drain D2form the second thin film transistor T2. The second drain D2is connected to the first electrode21through the via hole111.

It should be noted that although the embodiment of the present application only shows that the first thin film transistor T1and the second thin film transistor T2are top gate type, in some embodiments, the first thin film transistor T1and the second thin film transistor T2may also be bottom-gate or double-gate thin film transistors, which will not be repeated here.

Optionally, the material of the active layer122may be oxide semiconductor, polysilicon or amorphous silicon.

The display device100of the embodiment of the present application comprises a display panel10and an ultrasonic fingerprint sensor20. The display panel10comprises a substrate11and a thin film transistor12arranged on the substrate11, and the substrate11is provided with a via hole111; the ultrasonic fingerprint sensor20is fabricated on a side of the substrate11away from the thin film transistor12to reduce the thickness of the display device100.

Besides, the ultrasonic fingerprint sensor20comprises a first electrode21, a first insulating layer22, a piezoelectric layer23, a second electrode24and a protective layer25. The first electrode21is arranged on a side of the substrate11away from the thin film transistor12. The first electrode21is connected to the thin film transistor12through the via hole111. The first insulating layer22is arranged on a side of the first electrode21away from the thin film transistor12. The piezoelectric layer23is arranged on a side of the first insulating layer22away from the thin film transistor12. The second electrode24is arranged on a side of the piezoelectric layer23away from the thin film transistor12. The protective layer25is arranged on a side of the second electrode24away from the thin film transistor12to protect the ultrasonic fingerprint sensor20.

The display device provided by the embodiments of the present application are described in detail as aforementioned, and the principles and implementations of the present application have been described with reference to specific illustrations. The description of the foregoing embodiments is merely for helping to understand the technical solutions of the present application and the core ideas thereof; meanwhile, those skilled in the art will be able to change the specific embodiments and the scope of the application according to the idea of the present application. In conclusion, the content of the specification should not be construed as limiting the present application.