TW202206997A - 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.

A conventional display device 200 with an under-screen fingerprint identification function, as shown in (a) and (b) of FIG. 4 , includes a display panel 210 , a support substrate 220 , a fingerprint identification element 240 and a circuit board 250. Wherein, the support substrate 220 is located on the side of the display panel 210 away from the display surface thereof, and the support substrate 220 defines an opening 226 extending through two opposite surfaces thereof. The fingerprint identification element 240 is located within 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 further disposed between the display panel 210 and the fingerprint identification element 240 . The electromagnetic shielding layer 234 is located in the opening 226 of the support 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 wire of the circuit board 250 by the conductive glue 260 to Perform grounding treatment.

However, due to the requirement of electrical conductivity, the area of the conductive adhesive 260 needs to be large enough, so that the area of the area where the electromagnetic shielding layer 234 and the conductive adhesive 260 are connected must also be large enough. Moreover, in this structure, in 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 element; a circuit board, electrically connected to the fingerprint identification element, the circuit board defines a through hole penetrating through two opposite surfaces thereof, the circuit board includes bare copper, and the bare copper is located at the periphery of the through hole; an adhesive layer, the adhesive layer includes a first adhesive layer, an electromagnetic shielding layer and a second adhesive layer that are stacked in sequence, and the second adhesive layer exposes a part of the electromagnetic shielding layer to form a grounding area; a display panel, electrically connected to the circuit board, the display panel has a display surface and a back surface opposite to the display surface, the back surface is bonded to the fingerprint identification element by the bonding layer; and a support substrate, located on the back of the display panel, the support substrate defines an opening through two opposite surfaces thereof, 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 grounding area, and the grounding area is filled in the through hole and covers the bare copper by a conductive glue, so as to realize grounding .

In the display device, the circuit board is provided with a through hole aligned with the grounding region of the electromagnetic shielding layer, and the circuit board and the electromagnetic shielding layer are electrically connected by conductive glue filled in the through hole to realize the grounding treatment. Since the grounding regions of the circuit board and the electromagnetic shielding layer are arranged to overlap up and down, the area of the electromagnetic shielding layer can be reduced, and the size of the opening of the supporting substrate can also be correspondingly reduced, thereby improving the assembly space of other components of the display device. In addition, in the display device, it is possible to choose whether to attach the electromagnetic shielding layer to the display panel first or to the fingerprint identification element first according to the needs in the manufacturing process, 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 off-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 view taken along section line II-II of FIG. 1 . As shown in FIG. 2 , the display device 100 includes a display panel 10 , a support substrate 20 , a fingerprint identification element 40 , a bonding layer 30 , a circuit board 50 and a conductive adhesive 60 . The fingerprint identification element 40 and the adhering layer 30 are both disposed corresponding to the fingerprint detection area FA. The area of the fingerprint detection area FA may be larger than that of the fingerprint identification element 40 , or approximately equal to 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 support substrate 20 is located on the side of the display panel 10 away from the display surface 10a. That is, the support substrate 20 is located on the back surface 10 b of the display panel 10 . The support substrate 20 is used for supporting the display panel 10 . The support substrate 20 defines openings 26 through two opposite surfaces thereof. The bonding layer 30 and the fingerprint identification element 40 are located in the opening 26 .

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

The circuit board 50 is located on the 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 defines through holes 58 through two opposite surfaces thereof. The through holes 58 are aligned with the electromagnetic shielding layer 34 along the thickness direction of the display device 100 . The second adhesive layer 36 exposes a portion of the electromagnetic shielding layer 34 to form a grounding area.

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

In the display device 100 , the grounding area of the electromagnetic shielding layer 34 and the circuit board 50 are overlapped up and down, and the circuit board 50 is provided with through holes 58 aligned with the electromagnetic shielding layer 34 . The circuit board 50 and the electromagnetic shielding layer 34 are filled with The conductive adhesive 60 in the through hole 58 is electrically connected, thereby realizing the grounding process. Therefore, compared with the structure of the display device 200 shown in (b) of FIG. 4 , the area of the electromagnetic shielding layer 34 of the display device 100 according to 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 improves the assembly space of other components of the display device 100 . In addition, in the manufacturing process, the electromagnetic shielding layer 34 can be selected to be attached 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 requirements, thereby reducing the manufacturing process required by the customer.

In the display device 100 , by disposing 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 to the fingerprint identification element 40 can be avoided, so that the fingerprint identification element The fingerprint recognition sensitivity of the fingerprint recognition element 40 is reduced; on the other hand, the electromagnetic interference of the fingerprint recognition element 40 to the display panel 10 can be avoided, so that the image quality of the display panel 10 is deteriorated. 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 simultaneously improved.

In one embodiment, the fingerprint identification element 40 is an ultrasonic fingerprint identification element 40 . The fingerprint recognition 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 the finger, and then received by the fingerprint identification element 40 . The fingerprint recognition element 40 can also analyze the sensed ultrasonic signals to generate ultrasonic images for fingerprint recognition.

As shown in FIG. 2 , the fingerprint identification element 40 includes a circuit substrate 42 , a piezoelectric layer 44 and an electrode layer 46 that are stacked in sequence. Both the piezoelectric layer 44 and the electrode layer 46 are 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 is pressed to the fingerprint detection area FA of the display panel 10, the operation of the fingerprint identification element 40 may include a transmission stage and a reception stage. In the transmitting stage, the circuit board 50 simultaneously gives different voltage signals to the electrode layer 46 and the circuit substrate 42, so that a potential difference is formed on both sides of the piezoelectric layer 44, thereby generating mechanical vibrations to emit ultrasonic waves. In the receiving stage, the piezoelectric layer 44 receives the reflected ultrasonic wave and generates induced charges, and the electrode layer 46 couples the induced charges of the piezoelectric layer 44 to the circuit substrate 42 , and the circuit substrate 42 collects and analyzes the coupled current, and then uses the circuit board 50 It is transmitted to the control circuit to realize the fingerprint identification function.

In one embodiment, the adhesive layer 30 may be adhesive tape or water glue. If the adhesive layer 30 is an adhesive tape, the electromagnetic shielding layer 34 can be a copper layer or other conductive material layers. In addition, in order to reduce the influence of the bonding layer 30 on the transmission and reception of ultrasonic waves, the bonding layer 30 is made of a material with high acoustic impedance, and the material may include Silicon, Epoxide, Acrylic, At least one type of viscose in polyurethane. In addition, increasing the Young's modulus of the bonding layer 30 and reducing the thickness of the bonding layer 30 is 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, where 1 μm≦A≦50 μm. Thereby, by adjusting the Young's modulus and thickness of the bonding layer 30 , the ultrasonic transmission and reception can 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, an alignment layer, and the like. When the finger presses 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, and the light is reflected on the surface of the finger to form reflected light or passes through the interior of the finger Scattered to form scattered light. Since the ridges and valleys of the fingerprint have different reflection capabilities for light, the reflected light from the fingerprint ridge and the emitted light from the fingerprint valleys have different light intensities, and the reflected light is blocked by the photodiode in the fingerprint identification element 40. The array receives and converts 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 the optical fingerprint identification 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 an optical signal 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 in layers. The support substrate 20 includes a stacked 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 10a. The conductive layer 24 is located on the side of the buffer layer 22 away from the display panel 10 .

The cover plate 12 serves to protect the components located below it. The cover plate 12 can be made of glass, such as soda glass, aluminosilicate glass, alkali-free glass, and the like. The cover plate 12 and the touch module 14 and between the touch module 14 and the display module 16 may be bonded by transparent optical glue (not shown).

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) touches the cover plate 12, the capacitive sensing signal in this area is different, and the capacitive 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 (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 layer to display the drive array layer (not shown) and so on. 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 disposing the support substrate 20 under the display module, the display module 16 can be supported to prevent the display module 16 from being deformed, thereby preventing the display module 16 from being deformed. The appearance and image display quality of the display device 100 are guaranteed.

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

The conductive layer 24 can be grounded by wires or electrically connected with other grounding components to form an electrostatic discharge path, thereby preventing electrostatic damage to the display device 100 . The conductive layer 24 may be metal, for example it may be copper.

FIG. 3 is a bottom view of the display device 100 of FIG. 2 . As shown in FIG. 3 , the circuit board 50 includes a base material 52 , and a surface of the base material 52 defines a binding area 50 a. A plurality of pins 54 arranged at intervals are provided in the binding area 50a. The circuit board 50 is electrically connected to the fingerprint identification element 40 through pins 54 . The surface of the base material 52 away from the electromagnetic shielding layer 34 is further provided with bare copper 56 . Bare copper 56 is located around the perimeter of the through hole 58 . The conductive adhesive 60 covers and is electrically connected to the bare copper 56 , fills the through holes 58 of the circuit board 50 , and is in contact with 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 adhesive 60 , the bare copper 56 and the ground wire of the circuit board 50 .

In one embodiment, the conductive adhesive 60 may be adhesive tape or liquid adhesive. The tape may be, for example, copper tape or the like. 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≦50 mm, and 0.1 mm≦D≦50 mm. The sheet 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 of the substrate 52 or near the edge of the substrate 52 . The shape of the through hole 58 is not limited. In FIG. 2, the through hole 58 has a substantially rectangular shape. The width and length of the through hole 58 are defined as E and F, respectively, 0.1mm≦E≦50mm, and 0.1mm≦F≦50mm.

In one embodiment, the bare copper 56 is a ring around the through hole 58 . Bare copper 56 may also partially surround via 58 . The shape of the bare copper 56 is not limited. In FIG. 3 , the bare copper 56 is an annular shape whose inner and outer rings are rectangular. The length and width of the rectangular outer ring of the bare copper 56 are defined as G and H, respectively, 0.1mm≦G≦50mm, and 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 paste 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 terephthalate (PET).

In the display device 100 , by opening the through holes 58 in the circuit board 50 that are aligned with the electromagnetic shielding layer 34 , the circuit board 50 and the grounding regions of the electromagnetic shielding layer 34 are overlapped up and down, and the through holes 58 are filled with the through holes 58 . The conductive glue 60 is electrically connected. Thereby, 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 correspondingly reduced, thereby increasing the installation space of other components in the display device 100 .

In addition, in the manufacturing process, the electromagnetic shielding layer 34 can be firstly attached to the display panel 10 or onto the fingerprint identification element 40 according to the needs, which increases the flexibility of the manufacturing process. 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 adhesive layer 30 is a composite layer including a first adhesive layer 32 , a first electromagnetic shielding layer 34 and a second adhesive layer 36 . It is possible to decide whether to attach the bonding layer 30 to the display panel 10 first or to the fingerprint identification element 40 first, and then the products provided to customers can be the display panel 10 that does not include the bonding layer 30 , or The display panel 10 may include the bonding 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 solutions 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: Lamination layer 32: The first adhesive layer 34, 234: Electromagnetic shielding layer 36: Second adhesive layer 40, 240: fingerprint identification components 42: circuit substrate 44: Piezoelectric layer 46: Electrode layer 50, 250: circuit board 52: Substrate 50a: Binding area 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 view taken along section line II-II of FIG. 1 .

FIG. 3 is a bottom view of the display device of FIG. 2 .

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

(b) of FIG. 4 is a bottom view after the electromagnetic shielding layer of the conventional display device is 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: Lamination layer

32: The first adhesive layer

34: Electromagnetic shielding layer

36: Second adhesive layer

40: Fingerprint identification components

42: circuit substrate

44: Piezoelectric layer

46: Electrode layer

50: circuit board

58: Through hole

60: Conductive glue

Claims (10)

A display device, which is improved by comprising: fingerprint identification element; a circuit board, electrically connected to the fingerprint identification element, the circuit board defines a through hole penetrating through two opposite surfaces thereof, the circuit board includes bare copper, and the bare copper is located at the periphery of the through hole; an adhesive layer, the adhesive layer includes a first adhesive layer, an electromagnetic shielding layer and a second adhesive layer that are stacked in sequence, and the second adhesive layer exposes a part of the electromagnetic shielding layer to form a grounding area; a display panel, electrically connected to the circuit board, the display panel has a display surface and a back surface opposite to the display surface, the back surface is bonded to the fingerprint identification element by the bonding layer; and a support substrate, located on the back of the display panel, the support substrate defines an opening through two opposite surfaces thereof, 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 grounding area, and the grounding area is filled in the through hole and covers the bare copper by a conductive glue, so as to realize grounding . The display device according to claim 1, wherein, along the thickness direction of the display panel, the projection of the grounding region completely falls within the projection range of the circuit board. The display device according to claim 1, wherein the Young's modulus of the adhering layer is greater than 3Mpa. The display device according to claim 1, wherein the surface resistance of the conductive adhesive 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, when the fingerprint identification element is an ultrasonic fingerprint identification element, the fingerprint identification element comprises a circuit substrate, a piezoelectric layer and an electrode layer that are stacked in sequence; Both the piezoelectric layer and the electrode layer are located on the side of the circuit substrate away from the display panel; The circuit board is electrically connected to the circuit substrate and the electrode layer, so as to provide a voltage signal to the circuit substrate and the electrode layer. The display device according to claim 6, wherein the display device defines a display area and a non-display area around the display area, and the fingerprint identification element is 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 set corresponding to the fingerprint detection area. The display device according to claim 7, wherein the support substrate comprises 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 layer The layer is located on a side of the buffer layer away from the display panel. The display device according to claim 9, wherein the display panel comprises 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 side of the group.

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