Fingerprint sensing unit and display device including the same

Abstract

The present disclosure provides a fingerprint sensing unit and a display device including the same. The fingerprint sensing unit includes: a substrate; a buffer layer disposed on the substrate; a thin film transistor disposed on the buffer layer; an insulating layer disposed on the buffer layer and having an opening exposing at least a portion of the buffer layer; and a sensing electrode disposed on the at least a portion of the buffer layer exposed by the opening, wherein the sensing electrode is connected to the thin film transistor. A display device including the fingerprint sensing unit can reduce internal reflection of external light.

Description

[0001] This application claims priority to and the benefit of Korean Patent Application No. 10-2018-0014185 filed on February 5, 2018, in the Korean Intellectual Property Office (KIPO), the contents of which are incorporated herein by reference in their entirety. Technical Field

[0002] Embodiments of the present disclosure relate to a fingerprint sensing unit and a display device including the fingerprint sensing unit. Background Art

[0003] Display devices may be classified into liquid crystal display ("LCD") devices, organic light emitting diode ("OLED") display devices, plasma display panel ("PDP") display devices, or electrophoretic display devices based on their light emitting schemes.

[0004] Recently, various functions have been added to display devices in addition to the function of displaying images. For example, a display device may have a touch sensing function or a fingerprint recognition function.

[0005] Fingerprint sensing can be classified into capacitive, optical, thermal, or ultrasonic types, for example. Among them, the capacitive type uses sensing electrodes to identify fingerprints by sensing capacitance differences based on the distance between ridges and valleys of the fingerprint.

[0006] The fingerprint sensing unit has a multi-layer structure with multiple insulating layers. Each layer can be made of different materials and have different refractive indices. When each layer has a different refractive index, light reflection or total internal reflection can occur at the interface between the layers. Specifically, when external light reflection occurs in the fingerprint sensing unit, the display quality of the display device may deteriorate. Summary of the Invention

[0007] Embodiments of the present disclosure provide a fingerprint sensing unit capable of reducing reflection of external light to improve display quality, and a display device including the fingerprint sensing unit.

[0008] According to an embodiment, a fingerprint sensing unit includes: a substrate; a buffer layer provided on the substrate; a thin film transistor provided on the buffer layer; an insulating layer provided on the buffer layer and having an opening exposing at least a portion of the buffer layer; and a sensing electrode provided on the at least a portion of the buffer layer exposed by the opening, wherein the sensing electrode is connected to the thin film transistor.

[0009] The sensing electrode may directly contact the buffer layer.

[0010] Only the buffer layer may be disposed between at least a portion of the sensing electrode and the substrate.

[0011] The area of ​​the opening may range from about 50% to about 80% of the planar area of ​​the substrate.

[0012] The area of ​​the insulating layer may range from about 20% to about 50% of the planar area of ​​the substrate.

[0013] The edge of the opening may form a closed loop on a plane, and the closed loop has one of a circular shape, a polygonal shape, and an irregular shape.

[0014] The buffer layer may include silicon nitride (SiN x ), silicon oxide (SiO2) and silicon oxynitride (SiO x N y )

[0015] The insulating layer may include a first insulating layer, a second insulating layer, and a third insulating layer.

[0016] The thin film transistor may include an active layer disposed between the buffer layer and the first insulating layer; a gate electrode disposed between the first insulating layer and the second insulating layer; and a source electrode and a drain electrode disposed between the second insulating layer and the third insulating layer.

[0017] According to an embodiment, a fingerprint sensing unit includes: a substrate; a thin film transistor disposed on the substrate; a first insulating layer disposed on the substrate; a second insulating layer disposed on the first insulating layer and having an opening exposing at least a portion of the first insulating layer; and a sensing electrode disposed on the at least a portion of the first insulating layer exposed by the opening, wherein the sensing electrode is connected to the thin film transistor.

[0018] The sensing electrode may directly contact the first insulating layer.

[0019] Only the first insulating layer may be disposed between at least a portion of the sensing electrode and the substrate.

[0020] The area of ​​the opening may range from about 50% to about 80% of the planar area of ​​the substrate.

[0021] The first insulating layer may include silicon nitride (SiN x ), silicon oxide (SiO2) and silicon oxynitride (SiO x N y )

[0022] The fingerprint sensing unit may further include a third insulating layer disposed on the second insulating layer. The second insulating layer and the third insulating layer may have an opening exposing the at least a portion of the first insulating layer.

[0023] According to an embodiment, a display device includes: a display unit; and a fingerprint sensing unit disposed on the display unit. The display unit includes: a base substrate; and an organic light-emitting element disposed on the base substrate. The fingerprint sensing unit includes: a buffer layer disposed on the display unit; a thin film transistor disposed on the buffer layer; an insulating layer disposed on the buffer layer and having an opening exposing at least a portion of the buffer layer; and a sensing electrode disposed on the at least a portion of the buffer layer exposed by the opening, wherein the sensing electrode is connected to the thin film transistor.

[0024] The organic light emitting element may include: a first electrode; an organic light emitting layer disposed on the first electrode; and a second electrode disposed on the organic light emitting layer.

[0025] The sensing electrode may overlap the first electrode and directly contact the buffer layer.

[0026] The display device may further include a pixel defining layer disposed on the base substrate and having a pixel opening exposing at least a portion of the first electrode.

[0027] The opening may overlap with the pixel opening. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a circuit diagram of a fingerprint sensing unit according to an embodiment of the present disclosure.

[0029] Figure 2 is a plan view of a portion of a fingerprint sensing unit according to an embodiment of the present disclosure.

[0030] Figure 3 It is along Figure 2 A cross-sectional view taken along line II'.

[0031] Figure 4 It is along Figure 2 A cross-sectional view taken along line II-II'.

[0032] Figure 5 yes Figure 3 An enlarged cross-sectional view of portion A.

[0033] Figure 6A yes Figure 3 An enlarged cross-sectional view of portion B.

[0034] Figure 6B yes Figure 4 An enlarged cross-sectional view of portion C.

[0035] Figure 7 is a graph showing reflectivity of a fingerprint sensing unit as a function of wavelength according to an embodiment of the present disclosure.

[0036] Figure 8 is a plan view of a fingerprint sensing unit according to an embodiment of the present disclosure.

[0037] Figure 9 is a cross-sectional view of a fingerprint sensing unit according to an embodiment of the present disclosure.

[0038] Figure 10 is a perspective view of a display device including a fingerprint sensing unit according to an embodiment of the present disclosure.

[0039] Figure 11 It is along Figure 10 A cross-sectional view taken along line III-III'. DETAILED DESCRIPTION

[0040] The exemplary embodiments will now be described more fully below with reference to the accompanying drawings. Although the disclosed exemplary embodiments can be modified in various ways and have several embodiments, the exemplary embodiments are shown in the drawings and will be primarily described in the specification. However, the scope of the disclosure is not limited to the exemplary embodiments and should be construed to include all modifications, equivalents, and alternatives included in the spirit and scope of the disclosure.

[0041] In the accompanying drawings, the thickness of multiple layers and regions may be exaggerated for clarity and ease of description. Throughout the specification, like reference numerals may refer to like elements. When a layer, region, or panel is referred to as being "on" another layer, region, or panel, the layer, region, or panel may be directly on the other layer, region, or panel, or there may be intervening layers, regions, or panels therebetween.

[0042] Throughout the specification, when an element is referred to as being “connected” to another element, the element is “directly connected” to the other element or “electrically connected” to the other element with one or more intervening elements interposed therebetween.

[0043] As used herein, "about" or "approximately" is inclusive of the stated value and means within an acceptable range of variation for the particular value, as determined by one of ordinary skill in the art, taking into account the measurements being made and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system).

[0044] In the following, reference will be made to Figures 1 to 7 Embodiments of the present disclosure are described.

[0045] Figure 1 is a circuit diagram of a fingerprint sensing unit according to an embodiment of the present disclosure.

[0046] Reference Figure 1The fingerprint sensing unit according to the embodiment of the present disclosure includes a plurality of thin film transistors T1, T2 and T3, a plurality of wirings SL selectively connected to the plurality of thin film transistors T1, T2 and T3, n-1 , SL n , PL and OL and reference capacitor C r .

[0047] According to an embodiment, the plurality of thin film transistors T1 , T2 , and T3 include a first thin film transistor T1 , a second thin film transistor T2 , and a third thin film transistor T3 .

[0048] According to an embodiment, the first gate electrode G1 of the first thin film transistor T1 is connected to the first scan line SL n-1 , a first source electrode S1 of the first thin film transistor T1 is connected to the common power line PL, and a first drain electrode D1 of the first thin film transistor T1 is connected to a third gate electrode G3 of the third thin film transistor T3 .

[0049] According to an embodiment, the second gate electrode G2 of the second thin film transistor T2 is connected to the second scan line SL n The second source electrode S2 of the second thin film transistor T2 is connected to the common power line PL, and the second drain electrode D2 of the second thin film transistor T2 is connected to the third source electrode S3 of the third thin film transistor T3.

[0050] According to an embodiment, the third gate electrode G3 of the third thin film transistor T3 is connected to the first drain electrode D1 of the first thin film transistor T1, the third source electrode S3 of the third thin film transistor T3 is connected to the second drain electrode D2 of the second thin film transistor T2, and the third drain electrode D3 of the third thin film transistor T3 is connected to the output line OL.

[0051] As described above, according to the embodiment, the fingerprint sensing unit includes the first scan line SL that transmits the first scan signal to the first gate electrode G1 of the first thin film transistor T1. n-1 , a second scan line SL transmitting a second scan signal to a second gate electrode G2 of the second thin film transistor T2 n , a common power line PL that transmits a driving voltage to the first source electrode S1 of the first thin film transistor T1 and the second source electrode S2 of the second thin film transistor T2, and transmits a driving current I flowing through the third thin film transistor T3 to the sensing driver. d The output line OL.

[0052] According to an embodiment, the reference capacitor C r including a second scanning line SL n and a first electrode CE1 connected to the first drain electrode D1 of the first thin film transistor T1 , the third gate electrode G3 of the third thin film transistor T3 , and the second electrode CE2 connected to the sensing electrode SE.

[0053] Hereinafter, driving of the fingerprint sensing unit according to the embodiment will be described by way of example.

[0054] First, according to the embodiment, when the first scan signal is transmitted to the first scan line SL n-1 When the driving voltage is transmitted to the common power line PL, the first thin film transistor T1 is turned on. The first scan signal is a pulse signal. For example, the first scan signal may correspond to a low voltage switching period of a signal maintained at a high voltage, or may correspond to a high voltage switching period of a signal maintained at a low voltage.

[0055] According to an embodiment, when the first thin film transistor T1 is turned on, the driving voltage of the common power line PL is transmitted to the third gate electrode G3 of the third thin film transistor T3 and the reference capacitor C through the first thin film transistor T1. r Therefore, the voltage is transmitted to the third gate electrode G3 of the third thin film transistor T3 and the reference capacitor C r The second electrode CE2 is turned on, and the third thin film transistor T3 is turned on.

[0056] Next, according to the embodiment, when the second scan signal is transmitted to the second scan line SL n When the driving voltage is transmitted to the common power line PL, the second thin film transistor T2 is turned on. Similar to the first scanning signal, the second scanning signal is a pulse signal.

[0057] According to an embodiment, when the second thin film transistor T2 is turned on and the gate voltage V g When the current is transmitted to the third gate electrode G3 of the third thin film transistor T3, the driving current I d Flows through the second thin film transistor T2 and the third thin film transistor T3. In such an embodiment, the gate voltage V g According to the fingerprint capacitor C formed when a touch or fingerprint contact is made f Specifically, the gate voltage V of the third gate electrode G3 changes with the fingerprint capacitance. g According to the fingerprint capacitor C f The fingerprint capacitance and reference capacitor C r In addition, the driving current I flowing through the second thin film transistor T2 and the third thin film transistor T3 changes with the capacitive coupling between the reference capacitors. d According to the gate voltage V of the third gate electrode G3 g And change.

[0058] According to an embodiment, the output line OL transmits a driving current I to the sensing driver. d The sensing driver can be based on the driving current I d The change amount of the touch input is used to detect whether a touch input occurs, the touch coordinates of the touch input, and the ridges and valleys of the touch fingerprint.

[0059] However, according to embodiments, the structure of the fingerprint sensing unit according to embodiments of the present disclosure is not limited thereto. The fingerprint sensing unit may include a plurality of thin film transistors, one or more capacitors, and wiring including one or more scan lines and one or more power lines.

[0060] Figure 2 is a plan view of a portion of a fingerprint sensing unit according to an embodiment of the present disclosure, Figure 3 It is along Figure 2 A cross-sectional view taken along line II' of Figure 4 It is along Figure 2 A cross-sectional view taken along line II-II'.

[0061] Reference Figure 2 、 Figure 3 and Figure 4 The fingerprint sensing unit 10 according to the embodiment of the present disclosure includes: a substrate 110; and a first thin film transistor T1, a second thin film transistor T2, a third thin film transistor T3, a first scan line SL disposed on the substrate 110. n-1 , the second scanning line SL n , common power line PL, output line OL, reference capacitor C r , sensing electrode SE, buffer layer 120, first insulating layer IL1, second insulating layer IL2, third insulating layer IL3 and protective layer 130. In such an embodiment, the first thin film transistor T1 includes a first gate electrode G1, a first source electrode S1, a first drain electrode D1 and a first active layer A1, the second thin film transistor T2 includes a second gate electrode G2, a second source electrode S2, a second drain electrode D2 and a second active layer A2, and the third thin film transistor T3 includes a third gate electrode G3, a third source electrode S3, a third drain electrode D3 and a third active layer A3. In addition, the reference capacitor C r The first electrode CE1 and the second electrode CE2 are included.

[0062] According to an embodiment, the substrate 110 is a flexible plastic film. For example, the substrate 110 includes polyimide. However, the embodiment is not limited thereto, and the substrate 110 may include an insulating material such as glass or quartz. The substrate 110 includes a material that is mechanically strong, thermally stable, transparent, has a smooth surface, is easy to handle, and is waterproof.

[0063] According to an embodiment, the buffer layer 120 is provided on the substrate 110. The buffer layer 120 can substantially prevent the penetration of impurities, flatten the surface, and include a material capable of performing such functions. For example, the buffer layer 120 includes silicon nitride (SiN x ), silicon oxide (SiO2) and silicon oxynitride (SiO x N y)

[0064] According to an embodiment, a first active layer A1, a second active layer A2, and a third active layer A3 are provided on the buffer layer 120. The first active layer A1, the second active layer A2, and the third active layer A3 include a semiconductor material. The first active layer A1 includes a first source area SA1, a first drain area DA1, and a first channel area CA1 between the first source area SA1 and the first drain area DA1. The second active layer A2 includes a second source area SA2, a second drain area DA2, and a second channel area CA2 between the second source area SA2 and the second drain area DA2. The third active layer A3 includes a third source area SA3, a third drain area DA3, and a third channel area CA3 between the third source area SA3 and the third drain area DA3.

[0065] According to an embodiment, the first active layer A1, the second active layer A2, and the third active layer A3 include amorphous silicon, polycrystalline silicon, an oxide semiconductor, etc. The oxide semiconductor includes at least one selected from oxides based on titanium (Ti), hafnium (Hf), zirconium (Zr), aluminum (Al), tantalum (Ta), germanium (Ge), zinc (Zn), gallium (Ga), tin (Sn), and indium (In), or oxides thereof such as indium-gallium-zinc oxide (InGaZnO4), indium-zinc oxide (Zn-In-O), zinc-tin oxide (Zn-Sn-O), indium-gallium oxide (In-Ga-O), indium-tin oxide (In-Sn-O), indium-zirconium oxide (In-Zr-O), indium-zirconium-zinc oxide (In-Zr-Zn-O), indium-zirconium-tin oxide (In-Zr-Sn-O), indium-zirconium-gallium oxide (In-Zr-Ga-O), indium-aluminum oxide (In-Al-O), indium- A composite oxide of zinc-aluminum oxide (In-Zn-Al-O), indium-tin-aluminum oxide (In-Sn-Al-O), indium-aluminum-gallium oxide (In-Al-Ga-O), indium-tantalum oxide (In-Ta-O), indium-tantalum-zinc oxide (In-Ta-Zn-O), indium-tantalum-tin oxide (In-Ta-Sn-O), indium-tantalum-gallium oxide (In-Ta-Ga-O), indium-germanium oxide (In-Ge-O), indium-germanium-zinc oxide (In-Ge-Zn-O), indium-germanium-tin oxide (In-Ge-Sn-O), indium-germanium-gallium oxide (In-Ge-Ga-O), titanium-indium-zinc oxide (Ti-In-Zn-O) or hafnium-indium-zinc oxide (Hf-In-Zn-O). If the first active layer A1, the second active layer A2, and the third active layer A3 include oxide semiconductors, a separate protective layer is additionally provided to protect the oxide semiconductors from external environmental factors such as high temperature.

[0066] According to an embodiment, the first source region SA1 is spaced apart from the first drain region DA1, and the first channel region CA1 is located between the first source region SA1 and the first drain region DA1, the second source region SA2 is spaced apart from the second drain region DA2, and the second channel region CA2 is located between the second source region SA2 and the second drain region DA2, and the third source region SA3 is spaced apart from the third drain region DA3, and the third channel region CA3 is located between the third source region SA3 and the third drain region DA3. For example, the first source region SA1, the second source region SA2, the third source region SA3, the first drain region DA1, the second drain region DA2, and the third drain region DA3 are formed by doping a semiconductor material with n-type impurities or p-type impurities.

[0067] According to the embodiment, the first insulating layer IL1 is disposed on the first active layer A1, the second active layer A2, and the third active layer A3. The first insulating layer IL1 is a gate insulating layer. The first insulating layer IL1 includes silicon nitride (SiN x ), silicon oxide (SiO2) and silicon oxynitride (SiO x N y )

[0068] According to the embodiment, the first gate electrode G1, the second gate electrode G2, and the third gate electrode G3 are disposed on the first insulating layer IL1. The first gate electrode G1, the second gate electrode G2, and the third gate electrode G3 overlap the first active layer A1, the second active layer A2, and the third active layer A3, respectively. Specifically, the first gate electrode G1, the second gate electrode G2, and the third gate electrode G3 overlap the first channel region CA1 of the first active layer A1, the second channel region CA2 of the second active layer A2, and the third channel region CA3 of the third active layer A3, respectively.

[0069] In addition, according to the embodiment, the first scan line SL n-1 , the second scanning line SL n The first electrode CE1 is disposed on the first insulating layer IL1 and is integrally formed with the second gate electrode G2.

[0070] According to an embodiment, the second insulating layer IL2 is disposed between the first gate electrode G1, the second gate electrode G2, the third gate electrode G3, the first scan line SL n-1 , the second scanning line SL n The second insulating layer IL2 may be an organic insulating layer or a layer including, for example, silicon nitride (SiN x ), silicon oxide (SiO2) or silicon oxynitride (SiO x N y ) of an inorganic insulating layer.

[0071] According to the embodiment, a first source electrode S1, a second source electrode S2, a third source electrode S3, a first drain electrode D1, a second drain electrode D2, and a third drain electrode D3 are disposed on the second insulating layer IL2. The first source electrode S1 contacts the first source area SA1 of the first active layer A1 through a first contact hole CH1 in the first insulating layer IL1 and the second insulating layer IL2. The first drain electrode D1 contacts the first drain area DA1 of the first active layer A1 through a second contact hole CH2 in the first insulating layer IL1 and the second insulating layer IL2. The second source electrode S2 contacts the second source area SA2 of the second active layer A2 through a third contact hole CH3 in the first insulating layer IL1 and the second insulating layer IL2. The second drain electrode D2 contacts the second drain area DA2 of the second active layer A2 through a fourth contact hole CH4 in the first insulating layer IL1 and the second insulating layer IL2. The third source electrode S3 contacts the third source area SA3 of the third active layer A3 through a fifth contact hole CH5 in the first insulating layer IL1 and the second insulating layer IL2. The third drain electrode D3 contacts the third drain area DA3 of the third active layer A3 through a sixth contact hole CH6 in the first and second insulating layers IL1 and IL2.

[0072] In addition, according to the embodiment, the common power line PL, the output line OL, and the bridge electrode BE are disposed on the second insulating layer IL2. The bridge electrode BE contacts the third gate electrode G3 through the seventh contact hole CH7 in the second insulating layer IL2.

[0073] According to an embodiment, a third insulating layer IL3 is provided on the first source electrode S1, the second source electrode S2, the third source electrode S3, the first drain electrode D1, the second drain electrode D2, the third drain electrode D3, the common power line PL, the output line OL, and the bridge electrode BE. The third insulating layer IL3 protects the first thin film transistor T1, the second thin film transistor T2, and the third thin film transistor T3 and planarizes the upper surface thereof.

[0074] According to an embodiment, the third insulating layer IL3 may be an organic insulating layer or a layer including, for example, silicon nitride (SiN x ), silicon oxide (SiO2) or silicon oxynitride (SiO x N y For example, the third insulating layer IL3 includes a photosensitive polymer resin.

[0075] The first insulating layer IL1, the second insulating layer IL2, and the third insulating layer IL3 may be collectively referred to as an insulating layer. According to an embodiment, the first insulating layer IL1, the second insulating layer IL2, and the third insulating layer IL3 have openings 155. At least a portion of the buffer layer 120 is exposed through the openings 155 in the first insulating layer IL1, the second insulating layer IL2, and the third insulating layer IL3. The openings 155 are regions above the buffer layer 120 that do not overlap with the first insulating layer IL1, the second insulating layer IL2, and the third insulating layer IL3. Furthermore, within the openings 155, an edge 151 of the openings 155 serves as a boundary between the first insulating layer IL1 and the sensing electrode SE.

[0076] According to an embodiment, the edge 151 of the opening 155 forms a closed loop on a plane, and the closed loop has the following characteristics: Figure 2 However, the embodiment is not limited thereto, and the closed loop may have various shapes, such as a circular shape, a polygonal shape, or an irregular shape.

[0077] According to an embodiment, the sensing electrode SE is disposed on the third insulating layer IL3 and in the opening 155. The sensing electrode SE contacts the first drain electrode D1 of the first thin film transistor T1 through an eighth contact hole CH8 in the third insulating layer IL3, and contacts the bridge electrode BE connected to the third gate electrode G3 of the third thin film transistor T3 through a ninth contact hole CH9 in the third insulating layer IL3.

[0078] According to an embodiment, at least a portion of the sensing electrode SE is disposed in the opening 155 formed in the first, second, and third insulating layers IL1, IL2, and IL3. That is, at least a portion of the sensing electrode SE directly contacts the buffer layer 120 exposed through the opening 155. Since only the buffer layer 120 is disposed between the substrate 110 and the sensing electrode SE in the opening 155 without the first, second, and third insulating layers IL1, IL2, and IL3 disposed therebetween, reflection of external light is reduced in the fingerprint sensing unit 10, as will be described in detail below.

[0079] According to an embodiment, the reference capacitor C r The second electrode CE2 is disposed on the third insulating layer IL3. The second electrode CE2 is integrally formed with the sensing electrode SE. That is, the second electrode CE2 and the sensing electrode SE are formed using substantially the same material in substantially the same process.

[0080] According to an embodiment, the sensing electrode SE and the second electrode CE2 include a metal or a transparent conductive oxide (TCO). For example, the sensing electrode SE and the second electrode CE2 may include an aluminum-based metal (such as aluminum (Al) or an aluminum alloy), a silver-based metal (such as silver (Ag) or a silver alloy), a copper-based metal (such as copper (Cu) or a copper alloy), or a platinum-based metal (such as molybdenum (Mo) or a molybdenum alloy). In addition, the sensing electrode SE and the second electrode CE2 may include a transparent conductive oxide (TCO), for example, one of indium tin oxide (ITO), indium zinc oxide (IZO), and zinc oxide (ZnO). In addition, the sensing electrode SE and the reference capacitor C r The second electrode CE2 may include, for example, carbon nanotubes (CNTs) or graphene. In addition, the sensing electrode SE and the second electrode CE2 may have a multi-layer structure.

[0081] According to an embodiment, a protective layer 130 is provided on the sensing electrode SE and the second electrode CE2. The protective layer 130 includes at least one of an organic insulating layer and an inorganic insulating layer. The protective layer 130 protects the sensing electrode SE and the second electrode CE2 and flattens the upper surface thereof.

[0082] Figure 5 yes Figure 3 An enlarged cross-sectional view of portion A.

[0083] Reference Figure 5 According to an embodiment, fingerprint 170 includes ridges 171 and valleys 172, and ridges 171 and valleys 172 have a difference in distance from sensing electrode SE. That is, the distance between ridge 171 and sensing electrode SE is smaller than the distance between valley 172 and sensing electrode SE. Such a distance difference results in a fingerprint capacitance C between ridge 171 and sensing electrode SE. f_ridge The fingerprint capacitance C between the valley 172 and the sensing electrode SE f_valley The difference between.

[0084] As described above, according to the embodiment, the fingerprint capacitor C of the third gate electrode G3 f The fingerprint capacitance and reference capacitor C r The capacitive coupling between the reference capacitor and the gate voltage V g According to the fingerprint capacitor C f In addition, the driving current I flowing through the second thin film transistor T2 and the third thin film transistor T3 d According to the gate voltage V of the third gate electrode G3 g The sensing driver can be based on the driving current I d The change amount of the fingerprint is used to detect whether a touch input occurs, the touch coordinates of the touch input, and the ridges and valleys of the fingerprint.

[0085] Figure 6A yes Figure 3 An enlarged cross-sectional view of portion B, Figure 6B yes Figure 4 An enlarged cross-sectional view of portion C.

[0086] Reference Figure 6A According to an embodiment, a buffer layer 120, a first insulating layer IL1, a second insulating layer IL2, and a third insulating layer IL3 are disposed between the substrate 110 and the sensing electrode SE in portion B. The buffer layer 120, the first insulating layer IL1, the second insulating layer IL2, and the third insulating layer IL3 are formed as separate layers, each having a different refractive index.

[0087] According to an embodiment, external light reflection may occur at the interface between layers having different refractive indices. Figure 6A As shown in FIG, when the second insulating layer IL2 is an inorganic insulating layer having a refractive index of approximately 1.75 and the third insulating layer IL3 is an organic insulating layer having a refractive index of approximately 1.5, external light L incident on the fingerprint sensing unit is reflected from the interface between the second insulating layer IL2 and the third insulating layer IL3 due to the difference in refractive index between the second insulating layer IL2 and the third insulating layer IL3, and thus may be recognized by the user. Thus, the display quality of the display device including the fingerprint sensing unit 10 may be degraded by the external light reflection occurring at the interlayer interface.

[0088] Reference Figure 6B According to an embodiment, in portion C, only the buffer layer 120 is provided between the substrate 110 and the sensing electrode SE, and the insulating layers IL1, IL2, and IL3 are not provided between the substrate 110 and the sensing electrode SE. That is, since the insulating layers IL1, IL2, and IL3 are not provided in the opening 155, external light reflection that would otherwise occur at the interface between layers having different refractive indices is substantially prevented. In such an embodiment, the buffer layer 120 provided between the substrate 110 and the sensing electrode SE substantially prevents impurity elements from diffusing from the substrate 110 into the fingerprint sensing unit 10 and flattens its surface. The thickness t of the buffer layer 120 is approximately to approximately For example, the buffer layer 120 has a range of about thickness.

[0089] According to an embodiment, the fingerprint sensing unit 10 according to an embodiment of the present disclosure includes a plurality of sensing electrodes SE, which are disposed on a substrate 110 and have a plurality of openings 155, each corresponding to the plurality of sensing electrodes SE. In such an embodiment, the total area of ​​the plurality of openings 155 ranges from approximately 50% to approximately 80% of the planar area of ​​the substrate 110. In other words, each edge 151 of the plurality of openings 155 forms a closed loop in a plane, and the total area enclosed by each closed loop ranges from approximately 50% to approximately 80% of the area of ​​the substrate 110. In other words, the total area of ​​each of the first insulating layer IL1, the second insulating layer IL2, and the third insulating layer IL3 according to an embodiment of the present disclosure ranges from approximately 20% to approximately 50% of the planar area of ​​the substrate 110. For example, after the first insulating layer IL1, the second insulating layer IL2, and the third insulating layer IL3 are formed on the entire surface of the substrate 110, approximately 50% to approximately 80% of the area of ​​the first insulating layer IL1, the second insulating layer IL2, and the third insulating layer IL3 on the substrate 110 is removed, and approximately 20% to approximately 50% of the area remains on the substrate 110.

[0090] In this way, according to an embodiment of the present disclosure, the plurality of insulating layers IL1, IL2, and IL3 are not provided on the entire surface of the substrate 110, and at least a portion of the plurality of insulating layers IL1, IL2, and IL3 is removed between the substrate 110 and the sensing electrode SE, and thus, external light reflection can be reduced and display quality can be improved.

[0091] Figure 7 is a graph showing the reflectivity of a fingerprint sensing unit as a function of wavelength according to an embodiment of the present disclosure. More specifically, Figure 7 The reference symbol “R1” in FIG. 1 represents the reflectivity of the fingerprint sensing unit according to an embodiment of the present disclosure, specifically, the reflectivity when the opening area is approximately 75% of the plane area of ​​the substrate. Figure 7 The reference symbol "R2" in FIG. 1 represents the reflectivity of a conventional fingerprint sensing unit having no opening. That is, Figure 7 Reference sign “R2” in refs. denotes a reflectivity of a conventional fingerprint sensing unit when the first insulating layer, the second insulating layer, and the third insulating layer are disposed on substantially the entire surface of the substrate (excluding the plurality of contact holes).

[0092] Reference Figure 7According to the embodiment, it can be understood that the reflectivity R1 of the fingerprint sensing unit 10 according to the embodiment of the present disclosure is generally reduced compared to the reflectivity R2 of the conventional fingerprint sensing unit. Specifically, when the area of ​​the opening 155 defined by the first insulating layer IL1, the second insulating layer IL2, and the third insulating layer IL3 is approximately 75% of the planar area of ​​the substrate 110, the reflectivity R1 of the fingerprint sensing unit 10 is reduced to approximately 3%, compared to the reflectivity R2 of the conventional fingerprint sensing unit without the opening 155.

[0093] Since the fingerprint sensing unit 10 according to an embodiment of the present disclosure has the openings 155 in the first, second, and third insulating layers IL1, IL2, and IL3 between the substrate 110 and the sensing electrode SE, external light reflection is reduced and display quality is improved.

[0094] In the following, reference will be made to Figure 8 For the sake of convenience, the embodiments of the present disclosure will be omitted. Figures 1 to 7 The configurations of the embodiments are basically the same as those described.

[0095] Figure 8 is a plan view of a fingerprint sensing unit according to an embodiment of the present disclosure.

[0096] Reference Figure 8 The fingerprint sensing unit 11 according to an embodiment of the present disclosure has an irregular opening 157 overlapping at least a portion of the sensing electrode SE. That is, the edge 152 of the opening 157 forms a closed loop on a plane, and the closed loop has an irregular shape.

[0097] For example, according to the embodiment, when the wiring portion is defined as a portion provided with the first thin film transistor T1, the second thin film transistor T2, the third thin film transistor T3, the first scan line SL n-1 , the second scanning line SL n , a portion of the common power line PL and the output line OL, the first insulating layer IL1, the second insulating layer IL2, and the third insulating layer IL3 are provided in a region overlapping the wiring portion.

[0098] According to an embodiment of the present disclosure, the plane area of ​​the opening 157 of the fingerprint sensing unit 11 is larger than the plane area of ​​the opening 155 of the fingerprint sensing unit 10 according to an embodiment of the present disclosure, and thus, external light reflection can be substantially minimized in the fingerprint sensing unit 11.

[0099] In the following, reference will be made to Figure 9 For the sake of convenience, the embodiments of the present disclosure will be omitted. Figures 1 to 8 The configurations of the embodiments are basically the same as those described.

[0100] Figure 9 is a cross-sectional view of a fingerprint sensing unit according to an embodiment of the present disclosure.

[0101] Reference Figure 9 The fingerprint sensing unit 12 according to the embodiment of the present disclosure does not include the buffer layer 120. The fingerprint sensing unit 12 according to the embodiment of the present disclosure includes: a substrate 110; and a first thin film transistor T1, a second thin film transistor T2, a third thin film transistor T3, a first scan line SL n-1 , the second scanning line SL n , a common power line PL, an output line OL, a sensing electrode SE, a first insulating layer IL1 , a second insulating layer IL2 , a third insulating layer IL3 and a protective layer 130 .

[0102] According to the embodiment, an opening 158 is formed in the second insulating layer IL2 and the third insulating layer IL3. At least a portion of the first insulating layer IL1 is exposed through the opening 158. The opening 158 is a region above the first insulating layer IL1 that does not overlap with the second insulating layer IL2 and the third insulating layer IL3. In addition, in the opening 158, the edge 153 of the opening 158 is a boundary between the second insulating layer IL2 and the sensing electrode SE.

[0103] According to an embodiment, the edge 153 of the opening 158 forms a closed ring on a plane, and the closed ring may have various shapes, such as a circular shape, a polygonal shape, or an irregular shape.

[0104] According to an embodiment, at least a portion of the sensing electrode SE is disposed in the opening 158 in the second insulating layer IL2 and the third insulating layer IL3. That is, at least a portion of the sensing electrode SE directly contacts the first insulating layer IL1 exposed through the opening 158. Since only the first insulating layer IL1 is disposed between the substrate 110 and the sensing electrode SE in the opening 158 without the second insulating layer IL2 and the third insulating layer IL3 disposed between the substrate 110 and the sensing electrode SE, external light reflection can be reduced in the fingerprint sensing unit 12.

[0105] In the following, reference will be made to Figure 10 and Figure 11 A display device including a fingerprint sensing unit according to an embodiment of the present disclosure is described. Figures 1 to 9 The configurations of the embodiments are basically the same as those described.

[0106] Figure 10 is a perspective view of a display device including a fingerprint sensing unit according to an embodiment of the present disclosure,

[0107] Figure 11 It is along Figure 10A cross-sectional view taken along line III-III'.

[0108] Reference Figure 10 According to an embodiment, the display device includes a fingerprint sensing unit 10 and a display unit 20. In this case, although the fingerprint sensing unit 10 and the display unit 20 are shown separately from each other for ease of description, the fingerprint sensing unit 10 and the display unit 20 may be formed integrally. Specifically, the display device will be described assuming that the fingerprint sensing unit 10 has an on-box structure directly provided on the display unit 20. However, the embodiment is not limited thereto, and the fingerprint sensing unit 10 may have an in-box structure formed in the display unit 20. In addition, it is assumed that the display device is an organic light emitting diode ("OLED") display device, but the embodiment is not limited thereto, and the display device may be a liquid crystal display ("LCD") device.

[0109] According to an embodiment, the display unit 20 is divided into a display area DA and a non-display area NDA. The display unit 20 includes a plurality of pixels PX arranged in a matrix in the display area DA. The plurality of pixels PX are shown as having a substantially diamond shape, but the embodiment is not limited thereto, and the plurality of pixels PX may have various other shapes, such as a substantially circular shape or a substantially polygonal shape.

[0110] According to an embodiment, the fingerprint sensing unit 10 is provided on the display unit 20. The fingerprint sensing unit 10 includes a plurality of sensing electrodes SE that detect whether a touch input occurs, the touch coordinates of the touch input, and the ridges and fingers of the fingerprint. Figure 10 As shown in FIG, the fingerprint sensing unit 10 includes a plurality of sensing electrodes SE provided on the entire surface of the substrate overlapping the display unit 20. Therefore, a touch or fingerprint can be sensed on the entire surface of the display device.

[0111] Reference Figure 11 According to an embodiment, the display unit 20 includes a base substrate 210 , a driving circuit unit 230 , a pixel defining layer 290 , an OLED (organic light emitting diode, as an example of an organic light emitting element) 310 , and a thin film encapsulation layer 320 .

[0112] According to an embodiment, the buffer layer 220 is provided on the base substrate 210. The buffer layer 220 can substantially prevent the diffusion of undesirable elements and flatten the surface thereunder, and includes a material that can perform such a role. For example, the buffer layer 220 may include silicon nitride (SiN x ), silicon oxide (SiO2) and silicon oxynitride (SiO x N y However, the buffer layer 220 is not always necessary and may be omitted.

[0113] According to an embodiment, the driving circuit unit 230 is disposed on the buffer layer 220. The driving circuit unit 230 includes a plurality of thin film transistors Tr and a capacitor Cp, and drives the OLED 310. In addition, the driving circuit unit 230 includes gate lines arranged along a first direction, and data lines 271 and a common power line 272 that are insulated from and intersect the gate lines. The OLED 310 emits light based on a driving signal received from the driving circuit unit 230 to display an image.

[0114] The display device according to an embodiment of the present disclosure may have a 2Tr-1Cap structure in which two thin film transistors Tr and one capacitor Cp are provided in one pixel PX or may have other structures including three or more thin film transistors Tr and two or more capacitors Cp in one pixel PX.

[0115] According to an embodiment, capacitor Cp includes a pair of capacitor plates 258 and 278, and insulating interlayer 245 is interposed between the pair of capacitor plates 258 and 278. In such an embodiment, insulating interlayer 245 is a dielectric element. The capacitance of capacitor Cp is determined by the charge accumulated in capacitor Cp and the voltage between the pair of capacitor plates 258 and 278.

[0116] According to an embodiment, the thin film transistor Tr includes a semiconductor layer 232, a gate electrode 255, a source electrode 276, and a drain electrode 277. The semiconductor layer 232 is insulated from the gate electrode 255 by the gate insulating layer 240. The thin film transistor Tr transmits driving power for the organic light emitting layer 312 of the OLED 310 in the selected pixel PX to emit light to the first electrode 311. In such an embodiment, the gate electrode 255 is connected to the first capacitor plate 258 of the capacitor Cp, the source electrode 276 and the second capacitor plate 278 of the capacitor Cp are each connected to the common power line 272, and the drain electrode 277 is connected to the first electrode 311 of the OLED 310 through a contact hole in the planarization layer 246.

[0117] According to an embodiment, a planarization layer 246 is disposed on the insulating interlayer 245. The planarization layer 246 includes an insulating material and protects the driving circuit unit 230. The planarization layer 246 and the insulating interlayer 245 include substantially the same material.

[0118] According to an embodiment, the first electrode 311 is provided on the planarization layer 246. The first electrode 311 is a pixel electrode and may be an anode. The first electrode 311 is conductive and is one of a transmissive electrode, a transflective electrode, and a reflective electrode.

[0119] According to an embodiment, when the first electrode 311 is a transmissive electrode, the first electrode 311 includes a transparent conductive oxide (TCO). For example, at least one of indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), and indium tin zinc oxide (ITZO) can be used as the TCO. When the first electrode 311 is a transflective electrode or a reflective electrode, the first electrode 311 includes at least one of Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, and Cu.

[0120] According to an embodiment, a pixel defining layer 290 that defines a light-emitting region is disposed on the planarization layer 246. In such an embodiment, the light-emitting region is also referred to as a pixel region. The pixel defining layer 290 includes a polymer organic material. For example, the pixel defining layer 290 may include at least one of a polyimide (PI)-based resin, a polyacrylic resin, a polyethylene terephthalate (PET) resin, and a polyethylene naphthalate (PEN) resin.

[0121] According to an embodiment, the pixel defining layer 290 includes a pixel opening 295, and at least a portion of the first electrode 311 is exposed through the pixel opening 295. The first electrode 311 overlaps at least a portion of the pixel defining layer 290 outside the pixel opening 295 and does not overlap the pixel defining layer 290 in the pixel opening 295. The pixel opening 295 is an area above the first electrode 311 that does not overlap the pixel defining layer 290. In addition, the edge 291 of the pixel opening 295 is a boundary where the pixel defining layer 290 contacts the first electrode 311 at the pixel opening 295.

[0122] According to an embodiment, the organic light emitting layer 312 is disposed on the first electrode 311. Specifically, the organic light emitting layer 312 is disposed on the first electrode 311 in the pixel opening 295. The organic light emitting layer 312 is disposed on the sidewall of the pixel opening 295 in the pixel defining layer 290 and on the first electrode 311.

[0123] According to an embodiment, the organic light-emitting layer 312 includes a light-emitting material. In addition, the organic light-emitting layer 312 may include a host and a light-emitting dopant. The organic light-emitting layer 312 may be manufactured by a known method using known materials. For example, the organic light-emitting layer 312 may be formed by various methods such as vacuum deposition, spin coating, casting, Langmuir-Blodgett (LB) method, inkjet printing, laser printing, laser induced thermal imaging (LITI), etc.

[0124] According to an embodiment, the second electrode 313 is provided on the organic light emitting layer 312. The second electrode 313 is a common electrode and may be a cathode. The second electrode 313 may be a transmissive electrode, a transflective electrode, or a reflective electrode.

[0125] According to an embodiment, when the second electrode 313 is a transmissive electrode, the second electrode 313 includes at least one of Li, Ca, LiF / Ca, LiF / Al, Al, Mg, BaF, Ba, Ag, and Cu. For example, the second electrode 313 includes a mixture of Ag and Mg. When the second electrode 313 is a transflective electrode or a reflective electrode, the second electrode 313 includes at least one of Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF / Ca, LiF / Al, Mo, Ti, and Cu. In addition, in addition to the transflective electrode or the reflective electrode, the second electrode 313 may further include a transparent conductive layer, the transparent conductive layer including, for example, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), or indium zinc tin oxide (IZTO).

[0126] According to an embodiment, at least one of a hole injection layer (HIL) and a hole transport layer (HTL) is disposed between the first electrode 311 and the organic light emitting layer 312, and at least one of an electron transport layer (ETL) and an electron injection layer (EIL) is disposed between the organic light emitting layer 312 and the second electrode 313.

[0127] According to an embodiment, when the OLED 310 is a top emission type, the first electrode 311 is a reflective electrode, and the second electrode 313 is a transmissive electrode or a transflective electrode. When the OLED 310 is a bottom emission type, the first electrode 311 is a transmissive electrode or a transflective electrode, and the second electrode 313 is a reflective electrode. According to an embodiment, when the OLED 310 is a top emission type, the first electrode 311 is a reflective electrode, and the second electrode 313 is a transflective electrode.

[0128] According to an embodiment, a thin film encapsulation layer 320 is disposed on the second electrode 313 to protect the OLED 310. The thin film encapsulation layer 320 substantially prevents external air such as moisture or oxygen from penetrating into the OLED 310.

[0129] According to an embodiment, the thin film encapsulation layer 320 includes at least one inorganic layer 321 and 323 and at least one organic layer 322 alternately disposed with the at least one inorganic layer 321 and 323. Figure 11 As shown in FIG, the thin film encapsulation layer 320 includes two inorganic layers 321 and 323 and one organic layer 322, but the embodiment is not limited thereto.

[0130] According to an embodiment, the inorganic layers 321 and 323 include one or more inorganic materials selected from the group consisting of Al2O3, TiO2, ZrO, SiO2, AlON, AlN, SiON, Si3N4, ZnO, and Ta2O5. The inorganic layers 321 and 323 may be formed by a method such as chemical vapor deposition (CVD) or atomic layer deposition (ALD). However, the embodiment is not limited thereto, and the inorganic layers 321 and 323 may be formed by other methods known to those skilled in the art.

[0131] According to an embodiment, the organic layer 322 includes a polymer material. Examples of polymer materials include acrylic resin, epoxy resin, polyimide, or polyethylene. The organic layer 322 may be formed by a thermal deposition process. The thermal deposition process for forming the organic layer 322 is performed within a temperature range that does not damage the OLED 310. However, the embodiment is not limited thereto, and the organic layer 322 may be formed by other methods known to those skilled in the relevant art.

[0132] According to an embodiment, the inorganic layers 321 and 323 have a high-density thin film that can substantially prevent or effectively reduce the penetration of moisture or oxygen. The inorganic layers 321 and 323 can largely prevent moisture and oxygen from penetrating into the OLED 310.

[0133] According to embodiments, moisture and oxygen that have diffused through the inorganic layers 321 and 323 may be further blocked by the organic layer 322. Compared to the inorganic layers 321 and 323, the organic layer 322 has relatively low anti-permeation efficiency. However, in addition to preventing moisture permeation, the organic layer 322 may function as a buffer layer that reduces stress between the inorganic layers 321 and 323. Furthermore, since the organic layer 322 is planarized, the uppermost surface of the thin film encapsulation layer 320 may be planarized by the organic layer 322.

[0134] According to an embodiment, the fingerprint sensing unit 10 is provided on the display unit 20 including the base substrate 210, the driving circuit unit 230, the pixel defining layer 290, the OLED 310, and the thin film encapsulation layer 320. An adhesive member is further provided between the fingerprint sensing unit 10 and the display unit 20.

[0135] The fingerprint sensing unit 10 according to an embodiment of the present disclosure has an opening 155 in the first insulating layer IL1, the second insulating layer IL2, and the third insulating layer IL3. The opening 155 of the fingerprint sensing unit 10 overlaps with the pixel opening 295 of the display unit 20. Furthermore, the sensing electrode SE provided in the opening 155 corresponds to the OLED 310. That is, one sensing electrode SE overlaps one first electrode 311. However, the embodiment is not limited thereto, and one sensing electrode SE may correspond to a plurality of OLEDs 310.

[0136] According to the embodiment, since the fingerprint sensing unit 10 has the openings 155 in the first, second, and third insulating layers IL1, IL2, and IL3 between the substrate 110 and the sensing electrode SE, external light reflection may be reduced and display quality may be improved.

[0137] As described above, according to one or more embodiments, a fingerprint sensing unit and a display device including the fingerprint sensing unit have an opening in an insulating layer between a substrate and a sensing electrode, which can reduce external light reflection in the fingerprint sensing unit and improve display quality of the display device.

[0138] While embodiments of the present disclosure have been shown and described with reference to exemplary embodiments thereof, it will be apparent to those skilled in the art that various changes in form and details can be made therein without departing from the spirit and scope of the exemplary embodiments thereof.

Claims

1. A fingerprint sensing unit, comprising: substrate; a buffer layer, disposed on the substrate; a thin film transistor, disposed on the buffer layer; an insulating layer disposed on the buffer layer and having an opening exposing at least a portion of the buffer layer; as well as a sensing electrode disposed in the opening on the at least a portion of the buffer layer exposed by the opening, wherein the sensing electrode is connected to the thin film transistor; The fingerprint sensing unit is used in a display device including a display unit and is disposed on the display unit. The display unit includes: a base substrate; and an organic light emitting element disposed on the base substrate.

2. The fingerprint sensing unit according to claim 1, wherein: The sensing electrode directly contacts the buffer layer.

3. The fingerprint sensing unit according to claim 1, wherein: Only the buffer layer is disposed between at least a portion of the sensing electrode and the substrate.

4. The fingerprint sensing unit according to claim 1, wherein: The area of ​​the opening is in a range from 50% to 80% of the plane area of ​​the substrate.

5. The fingerprint sensing unit according to claim 1, wherein: The area of ​​the insulating layer is in a range of 20% to 50% of the plane area of ​​the substrate.

6. The fingerprint sensing unit according to claim 1, wherein: The edge of the opening forms a closed loop on a plane, and the closed loop has one of a circular shape, a polygonal shape, and an irregular shape.

7. The fingerprint sensing unit according to claim 1, wherein: The buffer layer includes one of silicon nitride, silicon oxide and silicon oxynitride.

8. The fingerprint sensing unit according to claim 1, wherein: The insulating layer includes a first insulating layer, a second insulating layer, and a third insulating layer stacked in sequence.

9. The fingerprint sensing unit according to claim 8, wherein: The thin film transistor includes: an active layer, disposed between the buffer layer and the first insulating layer; a gate electrode disposed between the first insulating layer and the second insulating layer; and The source electrode and the drain electrode are arranged between the second insulating layer and the third insulating layer.

10. A fingerprint sensing unit, comprising: substrate; a thin film transistor, disposed on the substrate; a first insulating layer, disposed on the substrate; a second insulating layer disposed on the first insulating layer and having an opening exposing at least a portion of the first insulating layer; as well as a sensing electrode disposed in the opening on the at least a portion of the first insulating layer exposed by the opening, wherein the sensing electrode is connected to the thin film transistor; The fingerprint sensing unit is used in a display device including a display unit and is disposed on the display unit. The display unit includes: a base substrate; and an organic light emitting element disposed on the base substrate.

11. The fingerprint sensing unit according to claim 10, wherein: The sensing electrode directly contacts the first insulating layer.

12. The fingerprint sensing unit according to claim 10, wherein: Only the first insulating layer is disposed between at least a portion of the sensing electrode and the substrate.

13. The fingerprint sensing unit according to claim 10, wherein: The area of ​​the opening is in a range from 50% to 80% of the plane area of ​​the substrate.

14. The fingerprint sensing unit according to claim 10, wherein: The first insulating layer includes one of silicon nitride, silicon oxide, and silicon oxynitride.

15. The fingerprint sensing unit according to claim 10, further comprising a third insulating layer disposed on the second insulating layer. in, The second insulating layer and the third insulating layer have the opening exposing the at least a portion of the first insulating layer.

16. A display device, comprising: Display unit; as well as a fingerprint sensing unit, disposed on the display unit, The display unit includes: a base substrate; and an organic light emitting element, which is arranged on the base substrate, and The fingerprint sensing unit includes: a substrate; a buffer layer disposed on the substrate; a thin film transistor disposed on the buffer layer; an insulating layer disposed on the buffer layer and having an opening exposing at least a portion of the buffer layer; and a sensing electrode disposed in the opening on at least a portion of the buffer layer exposed by the opening, wherein the sensing electrode is connected to the thin film transistor. The fingerprint sensing unit is used in a display device and is arranged on a display unit of the display device.

17. The display device according to claim 16, wherein: The organic light emitting element comprises: a first electrode; an organic light-emitting layer, disposed on the first electrode; and The second electrode is arranged on the organic light-emitting layer.

18. The display device according to claim 17, wherein: The sensing electrode overlaps the first electrode, and The sensing electrode directly contacts the buffer layer. 19 . The display device according to claim 17 , further comprising a pixel defining layer disposed on the base substrate and having a pixel opening exposing at least a portion of the first electrode.

20. The display device according to claim 19, wherein The opening overlaps the pixel opening.

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