TWI746123B - Display device - Google Patents

Abstract

An embodiment of the present invention provides a display device. The display device includes a fingerprint recognition element, a circuit board, a bonding layer, a display panel, and a support substrate. The circuit board is electrically connected to the fingerprint recognition element and the display panel. The circuit board defines a through hole and includes bare copper around the through hole. The bonding layer includes a first adhesive layer, an electromagnetic shielding layer and a second adhesive layer stacked in said sequence. The second adhesive layer exposes a part of the electromagnetic shielding layer to form a grounding area. The display panel is bonded to the fingerprint recognition element through the bonding layer. The support substrate is on the back of the display panel and defines an opening. The fingerprint recognition element is accommodated in the opening. In a thickness direction of the display panel, the through hole is aligned with the grounding area, and is filled with a conductive adhesive. The conductive adhesive coveres the bare copper to achieve grounding.

Description

Display device

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

The conventional display device 200 with an under-screen fingerprint recognition function, as shown in FIG. 4(a) and FIG. 4(b), includes a display panel 210, a supporting substrate 220, a fingerprint recognition element 240, and a circuit板250. Wherein, the support substrate 220 is located on a side of the display panel 210 away from the display surface thereof, and the support substrate 220 defines openings 226 penetrating two opposite surfaces of the support substrate 220. The fingerprint recognition element 240 is located in the opening 226. The circuit board 250 is electrically connected to the fingerprint identification element 240. In addition, in order to avoid mutual interference of signals between the display panel 210 and the fingerprint identification element 240, an electromagnetic shielding layer 234 is also provided between the display panel 210 and the fingerprint identification element 240. Wherein, the electromagnetic shielding layer 234 is located in the opening 226 of the supporting substrate 220, and has an area extending beyond the fingerprint identification element 240. In this area, the electromagnetic shielding layer 234 is connected to the ground of the circuit board 250 by conductive glue 260. Perform grounding treatment.

However, due to the requirement of electrical conductivity, the area of the conductive adhesive 260 needs to be large enough, resulting in the area where the electromagnetic shielding layer 234 is connected to the conductive adhesive 260 is also large enough. Moreover, with this structure, during the manufacturing process, the electromagnetic shielding layer 234 needs to be attached to the display panel 210 first, and then the fingerprint identification element 240 is attached, which limits the flexibility of the manufacturing process.

An embodiment of the present invention provides a display device, which includes: Fingerprint identification components; A circuit board electrically connected to the fingerprint identification element, the circuit board is defined with a through hole penetrating two opposite surfaces thereof, the circuit board includes bare copper, and the bare copper is located on the periphery of the through hole; A bonding layer, the bonding layer includes a first bonding layer, an electromagnetic shielding layer, and a second bonding layer stacked in sequence, and the second bonding layer exposes a part of the electromagnetic shielding layer to form a bonding area; A display panel electrically connected to the circuit board, the display panel having a display surface and a back surface opposite to the display surface, the back surface being bonded to the fingerprint identification element through the bonding layer; and A support substrate located on the back surface of the display panel, the support substrate defines an opening penetrating two opposite surfaces of the support substrate, and the fingerprint identification element is accommodated in the opening; Wherein, along the thickness direction of the display panel, the through hole is aligned with the ground area, and the ground area is filled in the through hole with a conductive glue and covers the bare copper to achieve grounding .

In the display device, the circuit board is provided with a through hole aligned with the ground area of the electromagnetic shielding layer, and the circuit board and the electromagnetic shielding layer are electrically connected by filling the through hole with conductive glue to achieve grounding treatment. Since the contact area between the circuit board and the electromagnetic shielding layer is overlapped up and down, the area of the electromagnetic shielding layer can be reduced, and the size of the opening of the supporting substrate can be correspondingly reduced, thereby increasing the assembly space of other components of the display device. In addition, in the display device, during the manufacturing process, it is possible to choose whether to attach the electromagnetic shielding layer to the display panel first or attach it to the fingerprint identification element first, which increases the flexibility of the manufacturing process.

FIG. 1 is a schematic plan view of a display device 100 according to an embodiment of the present invention. The display device 100 is a display device with an under-screen fingerprint recognition function, which may be a mobile phone, a tablet computer, or the like.

As shown in FIG. 1, the display device 100 defines a display area AA for displaying images and a non-display area NA located around the display area AA. The display area AA includes the fingerprint detection area FA. When the fingerprint of the user's finger touches the fingerprint detection area FA, the area can identify or detect the fingerprint of the user's finger.

Fig. 2 is a schematic diagram of Fig. 1 taken along the section line II-II. As shown in FIG. 2, the display device 100 includes a display panel 10, a supporting substrate 20, a fingerprint recognition element 40, a bonding layer 30, a circuit board 50 and a conductive adhesive 60. Both the fingerprint identification element 40 and the bonding layer 30 are arranged corresponding to the fingerprint detection area FA. The area of the fingerprint detection area FA may be larger than the area of the fingerprint identification element 40, or approximately the same as the area of the fingerprint identification element 40.

The display panel 10 has a display surface 10a and a back surface 10b opposite to the display surface 10a. The supporting substrate 20 is located on a side of the display panel 10 away from the display surface 10 a. That is, the support substrate 20 is located on the back surface 10b of the display panel 10. The supporting substrate 20 is used to support the display panel 10. The supporting substrate 20 defines an opening 26 penetrating two opposite surfaces thereof. The bonding layer 30 and the fingerprint identification element 40 are located in the opening 26.

The bonding layer 30 is located between the display panel 10 and the fingerprint identification element 40. The bonding layer 30 includes a first bonding layer 32, an electromagnetic shielding layer 34 and a second bonding layer 36 which are stacked. The display panel 10 and the electromagnetic shielding layer 34 are bonded by a first bonding layer 32 located between them. The electromagnetic shielding layer 34 and the fingerprint identification element 40 are bonded by a second adhesive layer 36 located between them.

The circuit board 50 is located on a side of the electromagnetic shielding layer 34 away from the display panel 10 and is electrically connected to the fingerprint identification element 40. The circuit board 50 is defined with through holes 58 penetrating through two opposite surfaces thereof, and in the thickness direction of the display device 100, the through holes 58 are aligned with the electromagnetic shielding layer 34. The second adhesive layer 36 exposes a part of the electromagnetic shielding layer 34 to form a connecting area.

The conductive adhesive 60 is in contact with and electrically connected to the area (ie, the grounding area) of the electromagnetic shielding layer 34 not covered by the second adhesive layer 36. The electromagnetic shielding layer 34 is electrically connected to the circuit board 50 through the conductive glue 60 filled in the through hole 58 to realize grounding treatment.

In the display device 100, the contact area of the electromagnetic shielding layer 34 overlaps with the circuit board 50. The circuit board 50 is provided with a through hole 58 aligned with the electromagnetic shielding layer 34. The circuit board 50 and the electromagnetic shielding layer 34 are filled in The conductive adhesive 60 in the through hole 58 is electrically connected, thereby realizing the grounding treatment. Thereby, compared with the structure of the display device 200 shown in FIG. 4(b), the area of the electromagnetic shielding layer 34 of the display device 100 of the embodiment of the present invention can be reduced, thereby making the opening 26 of the support substrate 20 smaller. The size can also be reduced accordingly, which increases the assembly space of other components of the display device 100. In addition, during the manufacturing process, it is possible to choose whether to attach the electromagnetic shielding layer 34 to the display panel 10 first or to the fingerprint identification element 40 first, which increases the flexibility of the manufacturing process. In addition, products with or without the electromagnetic shielding layer 34 can also be provided according to customer needs, thereby reducing the manufacturing process required by the customer.

In the display device 100, by arranging the electromagnetic shielding layer 34 between the display panel 10 and the fingerprint identification element 40, on the one hand, electromagnetic interference of the scan pulse and data signal of the display panel 10 can be avoided, so that the fingerprint identification element 40 The fingerprint recognition sensitivity of 40 is reduced; on the other hand, electromagnetic interference of the fingerprint recognition element 40 to the display panel 10 can also be avoided, which makes the image quality of the display panel 10 worse. That is, by shielding the electromagnetic interference generated between the display panel 10 and the fingerprint identification element 40 by the electromagnetic shielding layer 34, the image quality of the display panel 10 and the fingerprint sensing performance of the fingerprint identification element 40 can be improved at the same time.

In one embodiment, the fingerprint identification element 40 is an ultrasonic fingerprint identification element 40. The fingerprint identification element 40 can generate ultrasonic waves and the generated ultrasonic waves can be transmitted to the display panel 10. The fingerprint identification element 40 can also detect ultrasonic waves transmitted through the display panel 10, reflected by a finger, and then received by the fingerprint identification element 40. The fingerprint identification element 40 can also analyze the sensed ultrasonic signal to generate an ultrasonic image to perform fingerprint identification.

As shown in FIG. 2, the fingerprint recognition element 40 includes a circuit substrate 42, a piezoelectric layer 44 and an electrode layer 46 stacked in this order. The piezoelectric layer 44 and the electrode layer 46 are both located on the side of the circuit substrate 42 away from the display panel 10. The circuit board 50 is electrically connected to the circuit substrate 42 and the electrode layer 46 to provide voltage signals to the circuit substrate 42 and the electrode layer 46.

In one embodiment, the circuit board 50 is also electrically connected to a control circuit (not shown) for realizing signal transmission between the control circuit and the fingerprint identification element 40. The circuit substrate 42 is, for example, a thin film transistor (TFT) array substrate, which includes a plurality of TFT units, each TFT unit includes at least one electrode, and the plurality of electrodes are electrically connected to the circuit board 50. In FIG. 2, the circuit board 50 is electrically connected to the area of the circuit substrate 42 that is not covered by the piezoelectric layer 44.

When a finger presses the fingerprint detection area FA of the display panel 10, the operation of the fingerprint identification element 40 may include a transmitting phase and a receiving phase. In the transmitting stage, the circuit board 50 simultaneously gives the electrode layer 46 and the circuit substrate 42 different voltage signals, so that a potential difference is formed on both sides of the piezoelectric layer 44, and then mechanical vibration is generated to emit ultrasonic waves. In the receiving stage, the piezoelectric layer 44 receives the reflected ultrasonic waves and generates induced charges. The electrode layer 46 couples the induced charges of the piezoelectric layer 44 to the circuit board 42. The circuit board 42 collects and analyzes the coupling current, and then uses the circuit board 50 to collect and analyze the coupling current. It is transmitted to the control circuit to realize the fingerprint identification function.

In one embodiment, the bonding layer 30 may be tape or water glue. If the bonding layer 30 is an adhesive tape, the electromagnetic shielding layer 34 may be a copper layer or other conductive material layer. In addition, in order to reduce the impact of the bonding layer 30 on the transmission and reception of ultrasonic waves, the bonding layer 30 is a material with high acoustic impedance, and its material may include silicon, epoxy, acrylic, At least one glue in polyurethane. In addition, increasing the Young's modulus of the bonding layer 30 and reducing the thickness of the bonding layer 30 are beneficial to improve the sensitivity of ultrasonic transmission and reception.

In one embodiment, the Young's modulus of the bonding layer 30 is greater than 3Mpa. The thickness of the bonding layer 30 is defined as A, 1 μm≦A≦50 μm. Thereby, by adjusting the Young's modulus and thickness of the bonding layer 30, the ultrasonic transmission and reception have better sensitivity.

In another embodiment, the fingerprint identification element 40 may also be an optical fingerprint identification element, which may include a photodiode array, a collimation layer, and the like. When a finger is pressed to the fingerprint detection area FA of the display panel 10, the display panel 10 can emit a beam of light to the finger above the fingerprint detection area FA. The light is reflected on the surface of the finger to form reflected light or passes through the inside of the finger. Scattered to form scattered light. Since the ridge and valley of the fingerprint have different light reflectivity, the reflected light from the fingerprint ridge and the emitted light from the fingerprint valley have different light intensities, and the reflected light is reflected by the photodiode in the fingerprint identification element 40. The array received and converted into the corresponding electrical signal, that is, the fingerprint detection signal. Based on the fingerprint detection signal, fingerprint image data can be obtained, and fingerprint matching verification can be further performed, thereby realizing an optical fingerprint recognition function in the display device 100.

In other embodiments, the display device 100 may also use a built-in light source or an external light source to provide optical signals for fingerprint detection.

Please continue to refer to FIG. 2, the display panel 10 includes a cover plate 12, a touch module 14 and a display module 16 which are stacked. The supporting substrate 20 includes a layered buffer layer 22 and a conductive layer 24 for electrostatic protection. The buffer layer 22 is attached to the side of the display panel 10 away from the display surface 10 a. The conductive layer 24 is located on a side of the buffer layer 22 away from the display panel 10.

The cover plate 12 is used to protect the components located below it. The material of the cover plate 12 can be glass, such as soda glass, aluminosilicate glass, and alkali-free glass. Transparent optical glue (not shown) can be used for bonding between the cover 12 and the touch module 14 and between the touch module 14 and the display module 16.

The touch module 14 may include a self-capacitive touch sensing structure or a mutual-capacitive touch sensing structure. When a conductive object (such as a finger) is touched on the cover 12, the capacitance sensing signal in the area is different. The capacitance sensing signal is processed and converted to obtain the relative position of the touch point.

The display module 16 may be an Organic Light Emitting Diode (OLED) display module or a miniature light emitting diode display module. When the display module 16 is an OLED display module, it may include a growth substrate, an OLED light-emitting material layer (not shown) on the growth substrate, and electrically connected to the OLED light-emitting material layer and used to control the OLED light-emitting material The layer is a drive array layer (not shown) for screen display, etc. The driving array layer may be a thin film transistor array layer.

In one embodiment, the growth substrate of the OLED display module is flexible. By arranging the support substrate 20 under the display module, the display module 16 can be supported to prevent the display module 16 from being deformed. Ensure the appearance and image display quality of the display device 100.

The buffer layer 22 has elasticity or is deformable, which can absorb shock and has better recovery ability. Therefore, when the display device 100 vibrates, the buffer layer 22 can absorb the vibration, thereby protecting the display module 16 from damage. The material of the buffer layer 22 may be foam, for example. In addition, when the buffer layer 22 is made of foam, since it contains a plurality of bubbles, it can also absorb unnecessary ultrasonic waves transmitted to areas other than the fingerprint detection area FA, thereby reducing unnecessary ultrasonic noise.

The conductive layer 24 may be grounded by a lead or electrically connected to other grounding components to form a static discharge path, thereby preventing the display device 100 from being damaged by static electricity. The conductive layer 24 may be metal, for example, it may be copper.

FIG. 3 is a bottom view of the display device 100 in FIG. 2. As shown in FIG. 3, the circuit board 50 includes a substrate 52, and a binding area 50a is defined on the surface of the substrate 52. A plurality of pins 54 arranged at intervals are provided in the bonding area 50a. The circuit board 50 is electrically connected to the fingerprint identification element 40 through the pins 54. The surface of the substrate 52 away from the electromagnetic shielding layer 34 is also provided with bare copper 56. The bare copper 56 is located on the periphery of the through hole 58. The conductive adhesive 60 covers and electrically connects the bare copper 56 and fills the through holes 58 of the circuit board 50, and contacts the electromagnetic shielding layer 34 to be electrically connected.

In one embodiment, the bare copper 56 is electrically connected to the ground wire (not shown) of the circuit board 50, so that the electromagnetic shielding layer 34 is grounded by the conductive glue 60, the bare copper 56, and the ground wire of the circuit board 50.

In one embodiment, the conductive adhesive 60 may be tape or liquid adhesive. The tape may be copper tape or the like, for example. The liquid glue can be, for example, silver paste, copper paste, conductive ink, and the like. In one embodiment, the thickness, width, and length of the conductive adhesive 60 are defined as B, C, and D, respectively, 1 μm≦B≦1000 μm, 0.1 mm≦C≦50mm, and 0.1mm≦D≦50mm. The surface resistance of the conductive adhesive 60 is less than 200 mΩ, so that it has better conductivity.

In one embodiment, the through hole 58 may be located in the middle position of the substrate 52 or a position close to the edge of the substrate 52. The shape of the through hole 58 is not limited. In FIG. 2, the through hole 58 is substantially rectangular. The width and length of the through hole 58 are defined as E and F respectively, 0.1mm≦E≦50mm, 0.1mm≦F≦50mm.

In one embodiment, the bare copper 56 has a ring shape surrounding the through hole 58. The bare copper 56 may also partially surround the through hole 58. The shape of the bare copper 56 is not limited. In FIG. 3, the bare copper 56 is a ring shape in which the inner and outer rings are both rectangular. Define the length and width of the rectangular outer ring of bare copper 56 as G, H, 0.1mm≦G≦50mm, 0.1mm≦H≦50mm.

In one embodiment, the width C of the conductive adhesive 60 is equal to the width H of the rectangular outer ring of the bare copper 56, and the length D of the conductive adhesive 60 is equal to the length G of the rectangular outer ring of the bare copper 56. That is, the conductive adhesive 60 can completely cover the surface of the bare copper 56.

In one embodiment, the circuit board 50 is a flexible circuit board. The substrate 52 is flexible, and its material is, for example, polyimide (PI) or polyethylene glycol terephthalate (PET).

In the display device 100, by opening a through hole 58 aligned with the electromagnetic shielding layer 34 in the circuit board 50, the circuit board 50 and the electromagnetic shielding layer 34 overlap up and down, and by filling in the through hole 58 The conductive adhesive 60 is electrically connected. In this way, the area of the electromagnetic shielding layer 34 can be reduced, so that the size of the opening 26 of the support substrate 20 can be reduced accordingly, thereby increasing the assembly space of other components in the display device 100.

In addition, during the manufacturing process, it is possible to choose whether to attach the electromagnetic shielding layer 34 to the display panel 10 first or to the fingerprint identification element 40 first, which increases the flexibility of the manufacturing process. Furthermore, it can also be based on customer needs. Providing the display panel 10 with or without the electromagnetic shielding layer 34 reduces the manufacturing process required by the client.

In one embodiment, the bonding layer 30 is a composite layer including a first bonding layer 32, a first electromagnetic shielding layer 34 and a second bonding layer 36. It can be determined according to needs to first attach the lamination layer 30 to the display panel 10 or attach it to the fingerprint identification element 40 first, and then the product provided to the customer can be the display panel 10 that does not include the lamination layer 30, or It can be the display panel 10 including the laminating layer 30, which increases the flexibility of the product.

The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced. Without departing from the spirit and scope of the technical solution of the present invention.

100, 200: display device AA: Display area NA: non-display area FA: Fingerprint detection area 10.210: display panel 10a: display surface 10b: back 12: Cover 14: Touch module 16: display module 20, 220: support substrate 22: Buffer layer 24: conductive layer 26, 226: opening 30: Laminated layer 32: The first adhesive layer 34, 234: electromagnetic shielding layer 36: The second adhesive layer 40, 240: Fingerprint identification components 42: Circuit board 44: Piezo layer 46: Electrode layer 50, 250: circuit board 52: Substrate 50a: binding zone 54: Pin 56: bare copper 58: Through hole 60, 260: conductive adhesive

FIG. 1 is a schematic plan view of a display device according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of Fig. 1 taken along the section line II-II.

Fig. 3 is a bottom view of the display device in Fig. 2.

Fig. 4(a) is a bottom view of the conventional display device before the electromagnetic shielding layer is connected to the circuit board.

Figure 4(b) is a bottom view of the electromagnetic shielding layer of the conventional display device after being connected to the circuit board.

100: display device

AA: Display area

FA: Fingerprint detection area

10: Display panel

10a: display surface

10b: back

12: Cover

14: Touch module

16: display module

20: Support substrate

22: Buffer layer

24: conductive layer

26: opening

30: Laminated layer

32: The first adhesive layer

34: Electromagnetic shielding layer

36: The second adhesive layer

40: Fingerprint identification components

42: Circuit board

44: Piezo layer

46: Electrode layer

50: circuit board

58: Through hole

60: conductive adhesive

Claims (10)

A display device is improved in that it includes: Fingerprint identification components; A circuit board electrically connected to the fingerprint identification element, the circuit board is defined with a through hole penetrating two opposite surfaces thereof, the circuit board includes bare copper, and the bare copper is located on the periphery of the through hole; A bonding layer, the bonding layer includes a first bonding layer, an electromagnetic shielding layer, and a second bonding layer stacked in sequence, and the second bonding layer exposes a part of the electromagnetic shielding layer to form a bonding area; A display panel electrically connected to the circuit board, the display panel having a display surface and a back surface opposite to the display surface, the back surface being bonded to the fingerprint identification element through the bonding layer; and A support substrate located on the back surface of the display panel, the support substrate defines an opening penetrating two opposite surfaces of the support substrate, and the fingerprint identification element is accommodated in the opening; Wherein, along the thickness direction of the display panel, the through hole is aligned with the ground area, and the ground area is filled in the through hole with a conductive glue and covers the bare copper to achieve grounding . The display device according to claim 1, wherein in the thickness direction of the display panel, the projection of the ground area completely falls within the projection range of the circuit board. The display device according to claim 1, wherein the Young's modulus of the bonding layer is greater than 3Mpa. The display device according to claim 1, wherein the sheet resistance of the conductive glue is less than 200 mΩ. The display device according to claim 1, wherein the fingerprint identification element is an ultrasonic fingerprint identification element or an optical fingerprint identification element. The display device according to claim 5, wherein, in a case where the fingerprint identification element is an ultrasonic fingerprint identification element, the fingerprint identification element includes a circuit substrate, a piezoelectric layer, and an electrode layer that are sequentially stacked; The piezoelectric layer and the electrode layer are both located on a side of the circuit substrate away from the display panel; The circuit board is electrically connected to the circuit substrate and the electrode layer to provide voltage signals to the circuit substrate and the electrode layer. The display device according to claim 6, wherein the display device is defined with a display area and a non-display area located at the periphery of the display area, and the fingerprint identification element is arranged to be aligned with the display area. The display device according to claim 7, wherein the display area includes a fingerprint detection area, and the bonding layer is provided corresponding to the fingerprint detection area. The display device according to claim 7, wherein the support substrate includes an elastic buffer layer and a conductive layer for electrostatic protection, the buffer layer is attached to the back surface of the display panel, and the conductive The layer is located on the side of the buffer layer away from the display panel. The display device according to claim 9, wherein the display panel includes a stacked touch module and an OLED display module, and the buffer layer is attached to the OLED display module away from the touch module One side of the group.

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