Fingerprint sensor

Abstract

The present disclosure provides a fingerprint sensor. The fingerprint sensor includes a first line, a second line, and a third line, and a unit sensor connected to the first line, the second line, and the third line. The unit sensor includes: a pixel electrode connected between the first line and the second line; a first capacitor connected between the first line and the pixel electrode; a second capacitor connected between the second line and the pixel electrode; a switch element connected between the first line, the second line, the first line of the adjacent unit sensor, and the second line of the adjacent unit sensor and the pixel electrode, and including a control electrode connected to the third line; and a third capacitor connected between the third line and the pixel electrode, wherein at least one of the first capacitor and the second capacitor includes a variable capacitor.

Description

Technical Field

[0001] Exemplary embodiments of the present invention generally relate to a fingerprint sensor, and more particularly, to a display device including the fingerprint sensor. Background Art

[0002] Recently, display devices such as smartphones and tablet PCs are used for various purposes. For example, display devices in electronic financial transactions are widely used to implement an authentication method using biometric information of a user. An authentication method using a user's fingerprint may be the most common method among various biometric authentication methods. Thus, demand for fingerprint sensors and display devices including the same is growing rapidly.

[0003] The above information disclosed in this Background section is only for understanding the background of the present inventive concept and therefore it may contain information that does not constitute prior art. Summary of the invention

[0004] Exemplary embodiments of the present invention provide a fingerprint sensor having high sensitivity and a display device including the fingerprint sensor.

[0005] Additional features of the inventive concept will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the inventive concept.

[0006] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

[0007] A fingerprint sensor according to an exemplary embodiment includes a first line, a second line, and a third line, and a unit sensor connected to the first line, the second line, and the third line. The unit sensor includes: a pixel electrode connected between the first line and the second line; a first capacitive element connected between the first line and the pixel electrode; a second capacitive element connected between the second line and the pixel electrode; a switch element connected between the first line, the second line, one of the first line of the adjacent unit sensor and the second line of the adjacent unit sensor and the pixel electrode, and including a control electrode connected to the third line; and a third capacitive element connected between the third line and the pixel electrode, wherein at least one of the first capacitive element and the second capacitive element includes a variable capacitive element.

[0008] The fingerprint sensor may further include a fourth line disposed around the unit sensor and configured to form a parasitic capacitance between the fourth line and the pixel electrode.

[0009] The fourth line may surround the pixel electrode.

[0010] The first and second lines may extend in different directions to cross each other, and the pixel electrode may be disposed in a unit region defined by the first and second lines.

[0011] The pixel electrode may have a circular shape.

[0012] At least one of the first capacitive element and the second capacitive element may include a metal insulator semiconductor (MIS) or a metal insulator semiconductor metal (MISM) capacitive element.

[0013] The first line may be provided in plural, the second line may be provided in plural, the unit sensor may be provided in plural, and the plurality of unit sensors may be disposed in respective unit regions corresponding to intersections between the first and second lines.

[0014] The fingerprint sensor may further include a fourth line disposed between the plurality of unit sensors and configured to form a parasitic capacitance between the fourth line and a pixel electrode of each unit sensor.

[0015] During the initialization period, the plurality of unit sensors may be simultaneously provided with an initialization signal through the third line, and during the period in which the initialization signal is provided, lines of the first and second lines coupled to the switching elements may be simultaneously provided with a reset voltage.

[0016] During a period in which the initialization signal is supplied, the fourth line may be supplied with a reset voltage.

[0017] During a sensing period after the initialization period, the first lines may be sequentially provided with driving signals, and during the sensing period, sensing signals may be output through the second lines.

[0018] The pixel electrode of each unit sensor may be disposed in a region between the first line and the second line.

[0019] The pixel electrode of each unit sensor may be disposed above a crossing point between the first line and the second line such that the pixel electrode overlaps any one of the first line and the second line.

[0020] A display device according to an exemplary embodiment includes a display panel and a fingerprint sensor, the display panel including display pixels arranged in a display area. The fingerprint sensor includes a plurality of first lines, a plurality of second lines, and at least one third line arranged in a fingerprint sensing area overlapping the display area, and a plurality of unit sensors connected to the first line, the second line, and the third line. At least one of the plurality of unit sensors includes: a pixel electrode connected between a predetermined first line and a second line among the plurality of first lines and the plurality of second lines; a first capacitor connected between the predetermined first line and the pixel electrode; a second capacitor connected between the predetermined second line and the pixel electrode; a switch element connected between the predetermined first line, the predetermined second line, one of the first line of the adjacent unit sensor, and the second line of the adjacent unit sensor and the pixel electrode, and including a control electrode connected to the third line; and a third capacitor connected between the third line and the pixel electrode, wherein at least one of the first capacitor and the second capacitor includes a variable capacitor.

[0021] The entire display area may be set to correspond to the fingerprint sensing area.

[0022] A portion of the display area may be set to correspond to the fingerprint sensing area, and another portion of the display area may be set to correspond to the touch sensing area.

[0023] The fingerprint sensing area and the touch sensing area may include pixel electrodes and touch electrodes disposed on the same sensor substrate.

[0024] The display device may further include: a touch sensor provided around the fingerprint sensor and configured to overlap with the display area; a sensor driving circuit configured to drive the touch sensor and the fingerprint sensor; and a selection circuit configured to selectively connect the touch sensor or the fingerprint sensor to the sensor driving circuit.

[0025] The selection circuit can be configured to simultaneously connect the input / output lines of the touch sensor to the sensor driving circuit in response to a first mode, and to divide the first and second lines into multiple groups and alternately connect the first and second lines in each group to the sensor driving circuit in response to a second mode.

[0026] The display device may further include a fourth line disposed between the plurality of unit sensors and configured to form a parasitic capacitance between the fourth line and a pixel electrode of each unit sensor.

[0027] During the initialization period, the plurality of unit sensors may be simultaneously provided with an initialization signal through the third line, and during the period in which the initialization signal is provided, lines of the first and second lines coupled to the switching elements may be simultaneously provided with a reset voltage.

[0028] During a period in which the initialization signal is supplied, the fourth line may be supplied with a reset voltage.

[0029] During a sensing period after the initialization period, the first lines may be sequentially provided with driving signals, and during the sensing period, sensing signals may be output through the second lines.

[0030] The pixel electrode of each unit sensor may have a circular shape, and the fourth line may be spaced apart from the pixel electrode of each unit sensor by a predetermined distance and have a mesh shape in a region between the plurality of unit sensors.

[0031] The pixel electrode of each unit sensor may be disposed in a region between the first line and the second line.

[0032] The pixel electrode of each unit sensor may be disposed above a crossing point between the first line and the second line such that the pixel electrode overlaps any one of the first line and the second line. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings illustrate exemplary embodiments of the present invention and together with the description serve to explain the inventive concept. The accompanying drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification.

[0034] Figure 1 is an exploded view of a display device according to an exemplary embodiment of the present invention.

[0035] Figure 2 is an exploded view of a display device according to an exemplary embodiment of the present invention.

[0036] Figure 3 is an exploded view of a display device according to an exemplary embodiment of the present invention.

[0037] Figure 4 is a schematic diagram illustrating the principle of a fingerprint sensor according to an exemplary embodiment of the present invention.

[0038] Figure 5 is a diagram illustrating a fingerprint sensing area of ​​a sensor unit according to an exemplary embodiment of the present invention.

[0039] Figure 6 is a diagram illustrating a sensor unit and a sensor circuit unit according to an exemplary embodiment of the present invention.

[0040] Fig. 7A and Figure 7B is a diagram illustrating a unit sensor according to an exemplary embodiment of the present invention.

[0041] Figure 8 is a diagram illustrating a unit sensor according to an exemplary embodiment of the present invention.

[0042] Fig. 9 is a diagram illustrating a unit sensor according to an exemplary embodiment of the present invention.

[0043] Fig.10 is a diagram illustrating a unit sensor according to an exemplary embodiment of the present invention.

[0044] Fig.11A and Fig. 11B is a diagram illustrating a unit sensor according to an exemplary embodiment of the present invention.

[0045] Fig.12 is a diagram illustrating a unit sensor according to an exemplary embodiment of the present invention.

[0046] Fig.13 is a diagram illustrating a unit sensor according to an exemplary embodiment of the present invention.

[0047] Fig.14 is a diagram illustrating a driving timing of a unit sensor according to an exemplary embodiment of the present invention.

[0048] Fig.15A , Fig. 15B and Fig. 15C is a diagram illustrating an operation process of a unit sensor according to an exemplary embodiment of the present invention.

[0049] Fig.16A , Fig. 16B and Fig. 16C is a diagram illustrating an operation process of a fingerprint sensor according to an exemplary embodiment of the present invention.

[0050] Fig.17 is a diagram showing the difference in blurring occurrence between coupling methods.

[0051] Fig.18A and Fig.18B The electric fields formed between the fingerprint sensor and the user's finger during the individual coupling operation and the simultaneous coupling operation of the unit sensors are respectively shown.

[0052] Fig.19A and Fig.19B The amounts of charge detected from the unit sensors according to an exemplary embodiment of the present invention and a comparative embodiment are respectively shown.

[0053] Fig. 20 is a diagram illustrating a layout of a unit sensor according to an exemplary embodiment of the present invention.

[0054] Fig.21is a cross-sectional view of a unit sensor according to an exemplary embodiment of the present invention.

[0055] Fig. 22 is a diagram illustrating a layout of a unit sensor according to an exemplary embodiment of the present invention.

[0056] Fig.23 is a diagram illustrating a layout of a unit sensor according to an exemplary embodiment of the present invention.

[0057] Fig.24A , Fig. 24B , Fig.24C and Fig.24D is a schematic cross-sectional view of a variable capacitance element according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0058] In the following description, for the purpose of explanation, many specific details are set forth to provide a comprehensive understanding of various exemplary embodiments or embodiments of the present invention. When used herein, "embodiment" and "embodiment" are interchangeable words, which are non-limiting examples of devices or methods using one or more inventive concepts disclosed herein. However, it is obvious that various exemplary embodiments can be put into practice without these specific details or by one or more equivalent arrangements. In other cases, known structures and devices are shown in block diagram form to avoid unnecessary ambiguity of various exemplary embodiments. In addition, various exemplary embodiments can be different, but do not have to be exclusive. For example, the specific shape, configuration and characteristics of an exemplary embodiment can be used or implemented in another exemplary embodiment without departing from the inventive concept.

[0059] Unless otherwise specified, the exemplary embodiments shown will be understood as providing exemplary features of different details of some ways in which the inventive concept can be implemented in practice. Therefore, unless otherwise specified, the features, components, modules, layers, films, panels, regions and / or aspects, etc. (hereinafter, individually or collectively referred to as "elements") of various embodiments can be further combined, separated, interchanged and / or rearranged without departing from the inventive concept.

[0060] The use of cross hatching and / or shading in the accompanying drawings is generally provided to clarify the boundaries between adjacent elements. Therefore, the presence or absence of cross hatching or shading does not convey or indicate any preference or requirement for the specific materials, material properties, sizes, ratios, commonalities and / or any other characteristics, attributes, properties, etc. of the elements shown, unless otherwise specified. In addition, in the accompanying drawings, the sizes and relative sizes of the elements may be exaggerated for the purpose of clarity and / or description. When an exemplary embodiment can be implemented differently, a specific process sequence can be performed differently from the described sequence. For example, two processes described in succession can be performed substantially simultaneously or in an order opposite to the described sequence. In addition, the same reference numerals represent the same elements.

[0061] When an element, such as a layer, is referred to as being "on", or "connected to" or "coupled to" another element or layer, it may be directly on, or directly connected to, or coupled to, the other element or layer, or there may be intervening elements or layers. However, when an element or layer is referred to as being "directly on", or "directly connected to" or "directly coupled to" another element or layer, there are no intervening elements or layers. For this purpose, the term "connected" may refer to a physical connection, an electrical connection, and / or a fluid connection, with or without intervening elements. In addition, the D1 axis, the D2 axis, and the D3 axis are not limited to three axes of a rectangular coordinate system, such as an x-axis, a y-axis, and a z-axis, and may be interpreted in a broader sense. For example, the D1 axis, the D2 axis, and the D3 axis may be perpendicular to each other, or may represent different directions that are not perpendicular to each other. For the purpose of this disclosure, "at least one of X, Y, and Z" and "at least one selected from the group consisting of X, Y, and Z" may be interpreted as only X, only Y, only Z, or any combination of two or more of X, Y, and Z, such as, for example, XYZ, XYY, YZ, and ZZ. When used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0062] Although the terms "first", "second", etc. may be used herein to describe various types of elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another element. Therefore, the first element discussed below may be referred to as the second element without departing from the teachings of the present disclosure.

[0063] For descriptive purposes, spatial relational terms such as "under," "below," "below," "down," "over," "up," "above," "higher," "side" (e.g., as in "sidewall"), etc., may be used herein to describe the relationship of one element to another element(s) as shown in the accompanying drawings. In addition to the orientations depicted in the accompanying drawings, spatial relational terms are intended to encompass different orientations of the device in use, operation, and / or manufacture. For example, if the device in the accompanying drawings is flipped, an element described as "under" or "beneath" another element or feature will be oriented "over" the other element or feature. Thus, the exemplary term "under" is able to encompass both above and below orientations. Furthermore, the device may be otherwise oriented (e.g., rotated 90 degrees or in another orientation), and thus, the spatial relational descriptors used herein are interpreted accordingly.

[0064] The terms used herein are only for the purpose of describing specific embodiments and are not intended to be limiting. When used here, the singular forms "one", "an" and "the" are intended to also include plural forms, unless the context clearly indicates otherwise. In addition, when used in this specification, the terms "include" and / or "comprise" specify the presence of the features, integral bodies, steps, operations, elements, parts and / or its groups, but do not exclude the presence or addition of one or more other features, integral bodies, steps, operations, elements, parts and / or its groups. It should also be noted that when used here, the terms "substantially", "about" and similar terms are used as approximate terms and not as terms of degree, thus, for illustrating the inherent deviations in measured values, calculated values ​​and / or provided values, as will be recognized by those of ordinary skill in the art.

[0065] Various exemplary embodiments are described herein with reference to cross-sectional views and / or exploded views, which are schematic diagrams of idealized exemplary embodiments and / or intermediate structures. Thus, variations in the illustrated shapes due to, for example, manufacturing techniques and / or tolerances will be expected. Therefore, the exemplary embodiments disclosed herein should not necessarily be interpreted as being limited to the specific illustrated shapes of the regions, but will include shape deviations, for example, caused by manufacturing. In this way, the regions shown in the drawings may be schematic in nature, and the shapes of these regions may not reflect the actual shapes of the regions of the device, and thus are not necessarily intended to be limiting.

[0066] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure is a part. Terms such as those defined in general dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and should not be interpreted as an idealized or overly formal meaning, unless expressly so defined herein.

[0067] Figure 1 is an exploded view of a display device 100 according to an exemplary embodiment of the present invention.

[0068] Reference Figure 1 , the display device 100 includes a display panel 110 and a sensor unit 140 disposed on one surface of the display panel 110. Figure 1 The display panel 110 and the sensor unit 140 are shown to be separately provided, but the inventive concept is not limited thereto. For example, according to an exemplary embodiment, the sensor unit 140 may be integrally formed with the display panel 110. Figure 1 The sensor unit 140 is shown to be disposed above the display panel 110 (eg, between the display panel 110 and the window 160 ), but the inventive concept is not limited thereto, and the position of the sensor unit 140 may be changed, such as below the display panel 110 .

[0069] The display device 100 may further include a polarizing layer 120 and a window 160 disposed on the image display surface (e.g., front surface) side of the display panel 110. For example, the polarizing layer 120 may be disposed between the display panel 110 and the sensor unit 140, and the window 160 may be the uppermost layer of the display device 100. In an exemplary embodiment, at least one of the polarizing layer 120 and the window 160 may be omitted or formed integrally with the display panel 110 and / or the sensor unit 140.

[0070] The display device 100 may further include a first adhesive layer 130 disposed between the display panel 110 and the sensor unit 140 and a second adhesive layer 150 disposed between the sensor unit 140 and the window 160. The first adhesive layer 130 and the second adhesive layer 150 may be substantially transparent to allow light to pass therethrough, and the materials thereof are not particularly limited. In an exemplary embodiment, at least one of the first adhesive layer 130 and the second adhesive layer 150 may be omitted. For example, when the sensor unit 140 is integrally formed with the display panel 110, the polarizing layer 120 and / or the window 160, at least one of the first adhesive layer 130 and the second adhesive layer 150 may be omitted.

[0071] The display panel 110 includes a plurality of display pixels 112 disposed in the display area DA. The display panel 110 may be coupled to and driven by a display driver. The display panel 110 may have various structures and may be driven in various methods known in the art.

[0072] The sensor unit 140 may include a fingerprint sensing area FSA. In an exemplary embodiment, the fingerprint sensing area FSA may overlap with the display area DA. For example, a portion of the display area DA may be set to correspond to the fingerprint sensing area FSA.

[0073] The sensor unit 140 may further include a plurality of unit sensors 142 disposed in the fingerprint sensing area FSA. A group of unit sensors 142 forms a fingerprint sensor (eg, a sensor unit of a fingerprint sensor). The unit sensor 142 may be an image pixel of the fingerprint sensor for reading an image.

[0074] The shape, size, number, resolution and / or arrangement structure of the unit sensors 142 provided in the fingerprint sensing area FSA are not limited. However, the unit sensors 142 may be distributed in the fingerprint sensing area FSA and have a fine size and high resolution to sense the user's fingerprint. In addition, the unit sensors 142 may be regularly arranged in the fingerprint sensing area FSA, but the inventive concept is not limited thereto. In one embodiment, the unit sensors 142 may be irregularly arranged on the fingerprint sensing area FSA. Alternatively, the fingerprint sensing area FSA may be divided into a plurality of areas, and the unit sensors 142 may be arranged on the divided areas at different densities.

[0075] The display device 100 according to an exemplary embodiment may sense the fingerprint of the user in the fingerprint sensing area FSA using a fingerprint sensor formed by the unit sensors 142. For example, each unit sensor 142 may include a pixel electrode configured to form a contact capacitance with a contact means (such as a user's finger) in response to a touch event. Using the unit sensor 142, the display device 100 may sense the shape of the fingerprint by sensing the capacitance between the pixel electrode and the finger, which may vary depending on the shape of the fingerprint (e.g., a pattern formed by ridges and valleys of the fingerprint).

[0076] Figure 2 and Figure 3 is an exploded view of a display device according to an exemplary embodiment. Figure 2 and Figure 3 In the drawings, the same reference numerals are used to denote Figure 1 The elements are the same or similar elements in the description, and therefore, repeated description thereof will be omitted to avoid redundancy.

[0077] Reference Figure 2, the entire display area DA may be set to correspond to the fingerprint sensing area FSA. For example, the display area DA and the fingerprint sensing area FSA may have substantially the same size (or area) and completely overlap each other. In this case, the unit sensors 142 may be distributed over the entire surface of the display area DA.

[0078] Reference Figure 3 , a portion of the display area DA may be set to correspond to the fingerprint sensing area FSA, and another portion of the display area DA may be set to correspond to the touch sensing area TSA. For example, the entire display area DA except for the portion corresponding to the fingerprint sensing area FSA may be set to correspond to the touch sensing area TSA. Alternatively, the touch sensing area TSA and the fingerprint sensing area FSA may overlap each other. In this case, the sensor unit 140 may be formed of a fingerprint and touch sensor unit capable of sensing both a fingerprint and a touch. The sensing area SA of the sensor unit 140 may include a fingerprint sensing area FSA and a touch sensing area TSA.

[0079] In an exemplary embodiment, a plurality of touch electrodes 144 may be disposed in the touch sensing area TSA. A group of touch electrodes 144 may form a touch sensor (e.g., a sensor unit of a touch sensor). The touch sensor may have various structures and may be driven in various methods known in the art. For example, the touch sensor may be a self-capacitance sensor or a mutual capacitance sensor. More specifically, the touch electrode 144 may be formed by a self-capacitance electrode (which forms a capacitance with a contact means (such as a user's finger) in response to a touch event), or by a drive electrode and a sensing electrode extending in different directions and / or connected to each other to form a mutual capacitance.

[0080] The shape, size, number, resolution and / or arrangement structure of the touch electrodes 144 provided in the touch sensing area TSA are not particularly limited. However, the touch electrodes 144 distributed in the touch sensing area TSA may have a size and resolution capable of sensing a touch input. For example, the touch electrodes 144 distributed in the touch sensing area TSA may each have a size larger than that of a single unit sensor 142 of the fingerprint sensor, and may have a resolution lower than that of the unit sensor 142.

[0081] Figure 4 is a schematic diagram illustrating the principle of a fingerprint sensor according to an exemplary embodiment of the present invention.

[0082] Reference Figure 4 , the sensor unit 140 may include a sensor substrate 141 and a plurality of pixel electrodes PX provided on the sensor substrate 141. Each pixel electrode PX may be disposed in a corresponding unit sensor region 142.

[0083] In an exemplary embodiment, the sensor substrate 141 may be substantially transparent. For example, when the sensor unit 140 is disposed on the front surface of the display panel 110 (on the image display surface side), the sensor substrate 141 may include a transparent or translucent material having a predetermined light transmittance range. In an exemplary embodiment, the sensor substrate 141 may be a film substrate including a material such as glass or plastic, however, its material or thickness range is not limited. For example, the sensor substrate 141 may include various materials, such as a transparent film substrate made of plastic (such as polyethylene terephthalate (PET)), a transparent or colored polyimide (PI) substrate, and a glass substrate.

[0084] In an exemplary embodiment, the sensor substrate 141 may be provided separately from the display panel 110, or may be at least one substrate and / or insulating layer of the display panel 110. For example, the sensor substrate 141 may be a substrate that is separate from the display panel 110 and provided with a sensor, or may be an upper substrate or a thin film encapsulation layer of the display panel 110.

[0085] In an exemplary embodiment, the pixel electrode PX may be substantially transparent. For example, the pixel electrode PX may include a transparent or semi-transparent material having a predetermined light transmittance range, or have a structure capable of having a light transmittance condition.

[0086] For example, the pixel electrode PX may include at least one of a metal, a transparent conductive material, and other various conductive materials, and thus have a predetermined conductivity. When the pixel electrode PX includes an opaque material, the thickness of the pixel electrode PX may be limited, or the pixel electrode PX may be formed in a grid shape to ensure its transmittance. In addition, each pixel electrode PX may have a single-layer structure or a multi-layer structure. For example, each pixel electrode PX may have a double-layer structure including a planar electrode formed of a transparent material and a metal electrode in a grid shape overlapping the planar electrode. As described above, the material, thickness, structure, etc. of the pixel electrode PX may be modified differently.

[0087] The pixel electrode PX may include at least one of various metals (including gold (Au), silver (Ag), aluminum (Al), molybdenum (Mo), chromium (Cr), titanium (Ti), nickel (Ni), neodymium (Nd), copper (Cu), platinum (Pt), etc.), or an alloy thereof. Alternatively, the pixel electrode PX may include a transparent conductive material such as silver nanowire (AgNW), indium tin oxide (ITO), indium zinc oxide (IZO), antimony zinc oxide (AZO), indium tin zinc oxide (ITZO), zinc oxide (ZnO), tin oxide (SnO 2), carbon nanotubes, graphene, etc. In addition, the pixel electrode PX may include at least one of various conductive materials.

[0088] When the user's finger (particularly, the fingerprint area) contacts the fingerprint sensing area FSA of the sensor unit 140, each pixel electrode PX in the corresponding area forms capacitances Cr1, Cv, Cr2 with the finger. The capacitances Cr1, Cv, and Cr2 may be formed between the pixel electrode PX and the finger, and the sizes of the capacitances Cr1, Cv, and Cr2 may be different from each other depending on the shape (or pattern) of the user's fingerprint.

[0089] Specifically, when the ridge of the fingerprint contacts the fingerprint sensing area FSA, the distance between the pixel electrode PX and the finger is relatively small compared to when the valley of the fingerprint contacts the fingerprint sensing area FSA. Therefore, in the area corresponding to the valley and ridge of the fingerprint, capacitors Cr1, Cv and Cr2 with different sizes are formed between the pixel electrode PX and the finger. For example, the size of the capacitor Cr1 or Cr2 formed between the pixel electrode PX and the ridge of the fingerprint may be greater than the size of the capacitor Cv formed between the pixel electrode PX and the valley of the fingerprint. Thus, the shape of the fingerprint can be sensed by determining the deviation between the capacitors Cr1, Cv and Cr2.

[0090] In order to detect the deviation between the capacitances Cr1, Cv and Cr2, a current sensing type fingerprint sensor may be generally used, which includes a transistor coupled to each pixel electrode PX and configured to send a current corresponding to the level of the voltage applied to the pixel electrode PX, thereby using the IV (current-voltage) characteristics of the transistor. For example, the deviation between the capacitances Cr1, Cv and Cr2 formed on the corresponding unit sensor 142 may be determined by sensing the driving current flowing through the transistor and calculating the voltage corresponding to the driving current.

[0091] However, in the conventional current sensing scheme, current deviation may be generated depending on characteristic deviation of the transistor. The characteristics of the transistor may vary depending on temperature, external light and / or degradation, which may reduce the reliability of the fingerprint sensor.

[0092] A fingerprint sensor according to an exemplary embodiment of the present invention may have an improved structure and use a scheme capable of sensing the shape of a fingerprint using a CV (capacitance-voltage) characteristic based on the deviation between the capacitances Cr1, Cv, and Cr2 formed between the pixel electrode PX and the finger. By using the CV characteristic, changes in transistor characteristics that depend on characteristic deviations, temperature, and / or external light can be significantly reduced. For example, even when environmental conditions such as temperature or external light change, the values ​​of the minimum capacitance Cmin and the maximum capacitance Cmax can remain constant, and only the inclination and / or shape of the curve in the transition portion can change. Thus, the reliability of the fingerprint sensor can be improved. The structure of the fingerprint sensor according to the exemplary embodiment and the method of driving the fingerprint sensor will be described in detail.

[0093] Figure 5 is a diagram illustrating a fingerprint sensing area FSA of the sensor unit 140 according to an exemplary embodiment of the present invention.

[0094] Reference Figure 5 , a plurality of driving lines (first lines) Tx1 to TxN (N is a natural number of 2 or more), sensing lines (second lines) Rx1 to RxM (M is a natural number of 2 or more), and at least one initialization signal line (third line) VINIT may be provided in the fingerprint sensing area FSA. The unit sensor 142 may be provided in a corresponding unit area corresponding to the intersection between the driving lines Tx1 to TxN and the sensing lines Rx1 to RxM. For example, the unit sensor 142 coupled to the driving lines Tx1 to TxN, the sensing lines Rx1 to RxM, and the initialization signal line VINIT may be provided in a corresponding unit area defined by the driving lines Tx1 to TxN and the sensing lines Rx1 to RxM. The driving lines Tx1 to TxN, the sensing lines Rx1 to RxM, the initialization signal line VINIT, and the unit sensor 142 may form a sensor unit (e.g., fingerprint sensing area FSA) of a fingerprint sensor.

[0095] The driving lines Tx1 to TxN may be disposed on the fingerprint sensing area FSA and extend in the first direction. For example, the driving lines Tx1 to TxN may be disposed on corresponding rows and extend in the X-axis direction. During a predetermined sensing period, the driving lines Tx1 to TxN may sequentially receive driving signals from the sensor driving circuit and sequentially transmit the driving signals to the unit sensors 142 provided on the corresponding rows.

[0096] The sensing lines Rx1 to RxM may be disposed on the fingerprint sensing area FSA and intersect the driving lines Tx1 to TxN, respectively. For example, the sensing lines Rx1 to RxM may be disposed on corresponding columns and extend in a second direction (e.g., a Y-axis direction) intersecting the first direction. During a predetermined sensing period, the sensing lines Rx1 to RxM may receive a sensing signal corresponding to the driving signal from the unit sensor 142 and transmit the sensing signal to the sensor driving circuit. In response to receiving the sensing signal, the sensor driving circuit may sense the shape of the fingerprint based on the sensing signal.

[0097] In an exemplary embodiment, during a predetermined initialization period, the driving lines Tx1 to TxN or the sensing lines Rx1 to RxM may simultaneously receive a reset voltage and transmit the reset voltage to the unit sensor 142. For example, the driving lines Tx1 to TxN or the sensing lines Rx1 to RxM may be coupled to a switching element of the unit sensor 142 to transmit the reset voltage to the switching element during the initialization period, wherein the switching element is turned on.

[0098] The initialization signal line VINIT may provide an initialization signal to the unit sensor 142 during a predetermined initialization period. Figure 5 A plurality of initialization signal lines VINIT (corresponding to each horizontal row of fingerprint sensors) disposed on the fingerprint sensing area FSA are shown, but the inventive concept is not limited thereto. For example, the initialization signal line VINIT may simultaneously provide an initialization signal to the unit sensors 142 during a predetermined initialization period and may be integrated into a single line inside and / or outside the fingerprint sensing area FSA. In this case, the initialization signal line VINIT may be formed as a single grid line.

[0099] The driving lines Tx1 to TxN, the sensing lines Rx1 to RxM, the initialization signal line VINIT, and the unit sensor 142 may form a sensor unit 140 of a fingerprint sensor. In an exemplary embodiment, the sensor unit 140 may be disposed on the entire surface of the display area DA, thus forming a whole surface fingerprint sensor. In this case, a fingerprint may be sensed over the entire area of ​​the display area DA. In addition, a fingerprint sensor according to an exemplary embodiment may be configured to detect a difference in capacitance in response to a touch input. Therefore, the fingerprint sensor may be used as a touch sensor. Specifically, a touch input and / or a fingerprint may be detected over the entire area of ​​the display area DA.

[0100] Figure 6 1 is a diagram showing a sensor unit 140 and a sensor circuit unit according to an exemplary embodiment of the present invention. In an exemplary embodiment, Figure 6 The sensor unit 140 and the sensor circuit unit may be provided in the display device 100 .

[0101] Reference Figure 6 , the sensor unit 140 according to an exemplary embodiment may include a sensing area SA, and the sensing area SA includes a fingerprint sensing area FSA and a touch sensing area TSA. In an exemplary embodiment, the touch sensing area TSA may be arranged around the fingerprint sensing area FSA so that the touch sensing area TSA does not overlap with the fingerprint sensing area FSA. Specifically, the sensor unit 140 may include a fingerprint sensor provided in the fingerprint sensing area FSA and a touch sensor provided around the fingerprint sensor and configured to overlap with the display area DA. However, the inventive concept is not limited thereto, and the touch sensing area TSA and the fingerprint sensing area FSA may at least partially overlap with each other or be set to the same area.

[0102] The fingerprint sensing area FSA may include a plurality of unit sensors 142, each of which is coupled to a corresponding driving line TxI (I is a natural number of N or less), a corresponding sensing line RxJ (J is a natural number of M or less), and an initialization signal line VINIT. For example, a unit sensor 142 disposed on an I-th row and a J-th column in the fingerprint sensing area FSA may be coupled to at least an I-th driving line TxI, a J-th sensing line RxJ, and an initialization signal line VINIT.

[0103] The touch sensing area TSA may include a plurality of touch electrodes 144. For example, the touch sensing area TSA may include a plurality of first touch electrodes 144a extending in a first direction and a plurality of second touch electrodes 144b extending in a second direction. In an exemplary embodiment, the first touch electrodes 144a and the second touch electrodes 144b may be mutual capacitance drive electrodes and mutual capacitance sensing electrodes, respectively. For example, the first touch electrode 144a may be connected to a drive line T_Tx for touch sensing, and the second touch electrode 144b may be connected to a sensing line T_Rx for touch sensing. However, the inventive concept is not limited thereto, and the structure of the touch sensing area TSA may be changed in various ways.

[0104] In an exemplary embodiment, the unit sensor 142 for detecting a fingerprint and the touch electrode 144 for detecting a touch input may be formed on the same sensor substrate 141. For example, the touch electrode 144 and the pixel electrode PX of the unit sensor 142 may be formed on the same surface of the sensor substrate 141 and spaced apart from each other by the same process.

[0105] The sensor unit 140 may be coupled to the sensor circuit unit 170 through the driving lines T_Tx, Txo, and Txe and the sensing lines T_Rx, Rxo, and Rxe. The sensor circuit unit 170 may include at least a sensor driving circuit 172 and drive the sensor unit 140 using the sensor driving circuit 172. The initialization signal line VINIT may be directly or indirectly coupled to the sensor driving circuit 172, or coupled to another power supply circuit, etc.

[0106] In an exemplary embodiment, the touch sensor and the fingerprint sensor may be implemented by sensors operating in the same scheme and / or principle. For example, both the touch sensor and the fingerprint sensor may use a sensor configured to detect a touch input or a fingerprint in a mutual capacitance scheme during at least a sensing period.

[0107] In this case, a single sensor driving circuit 172 can be used to drive both the touch sensor and the fingerprint sensor. For example, the sensor driving circuit 172 may include a sensing circuit that can sense a change in capacitance using a voltage to be input to each Rx channel. As another example, the sensor driving circuit 172 may include a plurality of sensing channels (Rx channels), each of which includes an analog front end (AFE) configured by an integrator.

[0108] In an exemplary embodiment, the sensor circuit unit 170 may further include a selection circuit 174 coupled between the sensor unit 140 and the sensor driving circuit 172. The selection circuit 174 may selectively couple the touch sensor or the fingerprint sensor (e.g., the sensor unit of the touch sensor or the fingerprint sensor) to the sensor driving circuit 172 in response to the control signal CS. For example, the selection circuit 174 may couple the touch electrode 144 of the touch sensor to the sensor driving circuit 172 in response to receiving the control signal CS corresponding to the touch sensing mode (first mode), and couple the unit sensor 142 of the fingerprint sensor to the sensor driving circuit 172 in response to the control signal CS corresponding to the fingerprint sensing mode (second mode).

[0109] In an exemplary embodiment, between the selection circuit 174 and the sensor driving circuit 172, the sensor unit 140 may further include input / output channels corresponding to the number of input / output lines of any one of the touch sensor and the fingerprint sensor, the any one of the touch sensor and the fingerprint sensor having a smaller number of input / output lines (e.g., driving lines T_Tx, Txo, and Txe and sensing lines T_Rx, Rxo, and Rxe).

[0110] For example, when the touch sensor has P (P is a natural number) driving lines (input lines) T_Tx and Q (Q is a natural number) sensing lines (output lines) T_Rx, and the sensing sensor has N driving lines Tx1 to TxN (N is 2P) and M sensing lines Rx1 to RxM (M is 2Q) (the numbers of which correspond to 2P and 2Q, respectively), and when the control signal CS corresponding to the touch sensing mode is provided, the selection circuit 174 may simultaneously connect the driving lines T_Tx and the sensing lines T_Rx of the touch sensor to the sensor driving circuit 172. In addition, when the sensing signal CS corresponding to the fingerprint sensing mode is provided, the selection circuit 174 may divide the driving lines Txo and Txe and the sensing lines Rxo and Rxe of the fingerprint sensor into a plurality of groups, and alternately connect the driving lines Txo and Txe and the sensing lines Rxo and Rxe of each group to the sensor driving circuit 172.

[0111] For example, when the sensing signal CS corresponding to the fingerprint sensing mode is provided, the fingerprint sensor may be driven in a time-sharing scheme, in which the selection circuit 174 divides the driving lines Txo and Txe and the sensing lines Rxo and Rxe of the fingerprint sensor into a plurality of groups, and alternately couples the driving lines Txo and Txe and the sensing lines Rxo and Rxe of each group to the sensor driving circuit 172. For example, the selection circuit 174 may divide the driving lines Txo and Txe and the sensing lines Rxo and Rxe into groups of odd lines and even lines, and alternately couple their combinations (e.g., odd driving lines Txo and odd sensing lines Rxo, odd driving lines Txo and even sensing lines Rxe, even driving lines Txe and odd sensing lines Rxo, even driving lines Txe and even sensing lines Rxe) to the sensor driving circuit 172. In this case, the selection circuit 174 may be implemented as a 1:5 demultiplexer.

[0112] As described above, the touch drive circuit and the fingerprint drive circuit for driving the touch sensor and the fingerprint sensor, respectively, according to an exemplary embodiment can be formed as a single integrated sensor drive circuit 172. In addition, since the operation mode of the selection circuit 174 is controlled (or switched) using the control signal CS, the number of input / output channels of the sensor drive circuit 172 can be reduced, and the touch drive circuit can also be used as a fingerprint drive circuit. In addition, at least some of the unit sensors 142 of the fingerprint sensing area FSA can be operated even in the touch sensing mode, and therefore, touch input can also be sensed on the fingerprint sensing area FSA. Therefore, the existing touch drive circuit can also be used as a fingerprint drive circuit, so that the structure of the sensor circuit unit 170 can be simplified and the manufacturing cost can be reduced.

[0113] Fig. 7A , Figure 7B , Figure 8 and Fig. 9 1 is a diagram showing a unit sensor 142 according to an exemplary embodiment of the present invention. According to an exemplary embodiment, FIG. 7A to FIG. 9 The structure of each unit sensor 142 shown may be applied to at least one of the unit sensors 142 forming the fingerprint sensor. For example, the unit sensors 142 may have substantially the same structure.

[0114] Reference FIG. 7A to FIG. 9 , at least one driving line TxI, at least one sensing line RxJ, and an initialization signal line VINIT may be disposed around each unit sensor 142. Each unit sensor 142 may be coupled to a corresponding driving line TxI, a corresponding sensing line RxJ, and an initialization signal line VINIT. In an exemplary embodiment, FIG. 7B to FIG. 9 As shown, a common power line (fourth line) VCOM may be further provided around the unit sensor 142. The common power line VCOM may be an optional component. Fig. 7A As shown, the common power line VCOM may be omitted.

[0115] Each unit sensor 142 may include a pixel electrode PX, a switching element T1 , a first capacitive element C1 , a second capacitive element C2 , and a third capacitive element C3 .

[0116] The pixel electrode PX may be coupled between the corresponding driving line TxI and the corresponding sensing line RxJ. In response to contact by a contact means (such as a user's finger), the pixel electrode PX may form a contact capacitance Cf with the contact means. The size of the contact capacitance Cf may vary depending on the distance between the pixel electrode PX and the contact means.

[0117] The switching element T1 may be coupled between the driving line TxI and the pixel electrode PX. The control electrode of the switching element T1 may be coupled to the initialization signal line VINIT. For example, the switching element T1 may be coupled between the driving line TxI and the pixel electrode PX and may be implemented by a transistor element having a gate electrode coupled to the initialization signal line VINIT. The switching element T1 may be turned on in response to a gate-on voltage provided from the initialization signal line VINIT during a predetermined initialization period, and may transmit a reset voltage provided to the driving line TxI to the pixel electrode PX during the initialization period. During the remaining period other than the initialization period (for example, during the remaining period other than the initialization period of the period in which the touch sensing mode is performed), the switching element T1 may be turned off in response to a gate-off voltage provided from the initialization signal line VINIT. Thus, the pixel electrode PX may be floated during the remaining period other than the initialization period.

[0118] The first capacitive element C1 may be coupled between the driving line TxI and the pixel electrode PX. The second capacitive element C2 may be coupled between the sensing line RxJ and the pixel electrode PX. More specifically, the first capacitive element C1 and the second capacitive element C2 may be provided with the pixel electrode PX interposed therebetween, and coupled between the corresponding driving line TxI and the corresponding sensing line RxJ.

[0119] In an exemplary embodiment, at least one of the first capacitive element C1 and the second capacitive element C2 may include a variable capacitive element whose capacitance varies depending on a voltage applied thereto. For example, at least one of the first capacitive element C1 and the second capacitive element C2 may be a metal insulator semiconductor (MIS) or metal insulator semiconductor metal (MISM) capacitive element. Fig. 7A and Figure 7B As shown, both the first capacitive element C1 and the second capacitive element C2 may be formed by variable capacitive elements. Figure 8 As shown, only the first capacitive element C1 may be formed by a variable capacitive element. As another alternative, only the second capacitive element C2 may be formed by a variable capacitive element, such as Fig. 9 shown.

[0120] The third capacitive element C3 may be coupled between the initialization signal line VINIT and the pixel electrode PX. In an exemplary embodiment, the third capacitive element C3 may be formed by a fixed capacitive element having a constant capacitance regardless of the voltage applied thereto. In this case, due to the third capacitive element C3, a sufficient amount of voltage change in the pixel electrode PX during the coupling operation may be ensured.

[0121] The common power line VCOM may be disposed between the unit sensors 142 of the fingerprint sensing area FSA in the first direction and / or the second direction. Thus, a parasitic capacitance Cp may be formed between the pixel electrode PX of each unit sensor 142 and the common power line VCOM. A common voltage (e.g., a reset voltage) having a predetermined level may be supplied to the common power line VCOM during a predetermined initialization period in synchronization with an initialization signal to be supplied to the initialization signal line VINIT.

[0122] Fig.10 7 is a diagram showing a unit sensor 142 according to an exemplary embodiment of the present invention, which has a structure modified from that of FIG. 7 . Fig.10 7 , the same reference numerals are used to denote elements that are the same as or similar to those in FIG. 7 , and thus, repeated description thereof will be omitted to avoid redundancy.

[0123] Reference Fig.107, the orientations of the driving lines TxI and the sensing lines RxJ may be changed. For example, the driving lines TxI may be arranged in a column direction, and the sensing lines RxJ may be arranged in a row direction.

[0124] In an exemplary embodiment, the switching element T1 may be coupled between the corresponding sensing line RxJ and the pixel electrode PX. In this case, a reset voltage may be provided through the sensing line RxJ during a predetermined initialization period.

[0125] FIG. 11A to FIG. 13 is a diagram showing a unit sensor 142 according to an exemplary embodiment of the present invention. FIG. 11A to FIG. 13 In the description of the present invention, the same figure numbers are used to represent the same or similar elements as those of the aforementioned embodiment, and thus, repeated description thereof will be omitted to avoid redundancy.

[0126] Reference FIG. 11A to FIG. 13 , the first capacitive element C1 and the second capacitive element C2 may be provided with the pixel electrode PX interposed therebetween in the same manner as in the foregoing exemplary embodiment, and coupled between the corresponding driving line TxI and the corresponding sensing line RxJ. At least one of the first capacitive element C1 and the second capacitive element C2 may be a variable capacitive element.

[0127] The switching element T1 may be coupled between the corresponding pixel electrode PX and the driving line (e.g., TxI+1) or the sensing line (e.g., RxJ-1) of the adjacent unit sensor. For example, the switching element T1 may be coupled between the pixel electrode PX of the corresponding unit sensor 142 and the sensing line RxJ-1 disposed on the adjacent column.

[0128] In an exemplary embodiment, the control electrode of the switching element T1 may be coupled to any one of the initialization signal lines VINIT disposed around the switching element T1. In this case, the initialization signal lines VINIT may be disposed in one direction or in a grid shape on the fingerprint sensing area FSA and provided with the same signal at the same time. The initialization signal lines VINIT may be separated independently from each other. Alternatively, all the initialization signal lines VINIT may be electrically coupled to each other and formed as a single signal line or a substantially single signal line. Therefore, although FIG. 11A to FIG. 13 A plurality of initialization signal lines VINIT are shown, but the inventive concept is not limited thereto, and the initialization signal lines VINIT may be implemented as the same initialization signal lines VINIT or substantially the same initialization signal lines VINIT.

[0129] Furthermore, a common power line VCOM may be optionally provided around each unit sensor 142 .

[0130] In an exemplary embodiment, the switching element T1 may be turned on in response to a gate-on voltage supplied from the initialization signal line VINIT during a predetermined initialization period, and transmit a reset voltage supplied to the sensing line RxJ-1 disposed on an adjacent column to the pixel electrode PX during the initialization period. In an exemplary embodiment, the unit sensors 142 may be simultaneously operated during at least the initialization period. Therefore, during the initialization period, the same reset voltage may be simultaneously supplied to the sensing lines RxJ-1 and RxJ. Therefore, FIG. 11A to FIG. 13 The unit sensor 142 shown can be used with FIG. 7A to FIG. 10 The illustrated unit sensor 142 operates in substantially the same manner.

[0131] Fig.14 is a diagram illustrating a driving timing of the unit sensor 142 according to an exemplary embodiment. FIG. 15A to FIG. 15C is a diagram showing an operation process of the unit sensor 142 according to an exemplary embodiment. Figures 14 to 15C In the present invention, the unit sensor 142 and the driving method thereof will be described as having the structure of the unit sensor 142 of FIG. 11. However, the unit sensor 142 according to other exemplary embodiments described above may operate with substantially the same scheme and / or principle. Figures 14 to 15C In the example, it is assumed that the fingerprint area of ​​the finger contacts the corresponding unit sensor 142 and its surrounding area.

[0132] Reference Fig.14 and Fig.15A During the first period P1, an initialization signal having a gate-on voltage capable of turning on the switching element T1 may be provided to the initialization signal line VINIT, and a reset voltage Vrst may be simultaneously provided to the sensing lines Rx1 to RxM connected to the corresponding switching elements T1 of the unit sensor 142. The sensing lines Rx1 to RxM may be connected to a predetermined driving circuit or a reset voltage source (e.g., a predetermined driving circuit or a reset voltage source provided in the sensor circuit unit 170) for providing the reset voltage Vrst during the first period P1. Therefore, the sensing lines Rx1 to RxM may be provided with a predetermined reset voltage Vrst from a driving circuit, a reset voltage source, etc. When the switching element T1 of each unit sensor 142 is turned on as shown in FIGS. 7 to 8, the reset voltage Vrst may be provided to the sensing lines Rx1 to RxM. Fig. 9 When the reset voltage Vrst is coupled to any one of the driving lines Tx1 to TxN in the same manner as in the first period P1 , the reset voltage Vrst may be simultaneously supplied to the driving lines Tx1 to TxN during the first period P1 .

[0133] When an initialization signal having a gate-on voltage is supplied to the initialization signal line VINIT, the switching element T1 may be turned on so that the reset voltage Vrst is transmitted from the sensing lines Rx1 to RxM to the pixel electrode PX. In this way, each pixel electrode PX may be initialized to the reset voltage Vrst.

[0134] In addition, when the common power line VCOM is disposed around the unit sensor 142, the reset voltage Vrst may be provided to the common power line VCOM during the first period P1 for a subsequent coupling operation. In an exemplary embodiment, the initialization signal line VINIT, the common power line VCOM, the driving lines Tx1 to TxN, and / or the sensing lines Rx1 to RxM may be operated by the sensor circuit unit 170.

[0135] After the initialization signal and the reset voltage Vrst have been supplied for a predetermined time during the first period P1, the voltage of the initialization signal may be changed to the gate-off voltage. The voltage of the common power line VCOM may also be changed simultaneously with the voltage change of the initialization signal.

[0136] Therefore, if Fig. 15B As shown, the switch element T1 can be turned off so that when the pixel electrode PX floats, the coupling operation of the third capacitor element C3 can be generated, which can cause a change in the voltage in the pixel electrode PX. Due to the coupling effect caused by the coupling operation, information about the pattern (valley or ridge) of the fingerprint can be provided to the corresponding unit sensor 142. Thus, when the pixel electrode PX floats and the voltage of the initialization signal line VINIT also changes, the voltage change of the pixel electrode PX can be caused by the third capacitor element C3. The coupling operation of the first capacitor element C1 and the second capacitor element C2 and / or the parasitic capacitance Cp and the third capacitor element C3 may also affect the voltage change of the pixel electrode PX. In this case, the capacitance of each capacitor element (particularly the third capacitor element C3) can be set so that the voltage change amount in the pixel electrode PX can be guaranteed to be sufficient to identify the pattern of the fingerprint.

[0137] Specifically, when the voltage of the initialization signal changes to the gate-off voltage, the switch element T1 is turned off, which can make the pixel electrode PX float. In other words, the switch element T1 is provided so that the pixel electrode PX is maintained in a floating state when the pixel electrode PX is initialized and after the initialization of the pixel electrode PX has been completed. The switch element T1 can be designed by considering the leakage current characteristics (e.g., minimizing the leakage current).

[0138] Thus, when the pixel electrode PX floats and the voltage level of the initialization signal and the common voltage change, a coupling operation is generated. Due to the coupling effect caused by the coupling operation, a voltage (Vr or Vv) corresponding to the ridge or valley of the fingerprint may be applied to the corresponding pixel electrode PX. For example, when the ridge of the fingerprint is disposed on the pixel electrode PX, a voltage distribution corresponding to the size of the contact capacitance Cf formed between the pixel electrode PX and the finger is generated, and a voltage Vr corresponding to the ridge of the fingerprint is applied to the pixel electrode PX. On the other hand, when the valley of the fingerprint is disposed on the pixel electrode PX, a voltage Vv corresponding to the valley of the fingerprint is applied to the pixel electrode PX. In this case, if the unit sensor 142 of the fingerprint sensing area FSA is initialized and then a coupling operation is performed on the unit sensor 142 at the same time, the vertical electric field between the unit sensor 142 and the finger may be increased, thereby improving the signal-to-noise ratio (SNR).

[0139] While the voltage of the initialization signal is changed to the gate-off voltage, the voltage of each of the sensing lines Rx1 to RxM is changed to an initialization level voltage for a sensing operation.

[0140] After the voltages of the initialization signal line VINIT, the common power line VCOM, and the sensing lines Rx1 to RxM have been changed, the changed voltages are maintained during a predetermined period (e.g., a second period (determination period) P2). In an exemplary embodiment, it may be determined during the second period P2 whether a sensing operation of substantially detecting a fingerprint and / or a touch input is performed. For example, during the second period P2, a coupling current flowing through the entire sensor unit 140 is detected, and therefore, whether a touch of a finger has occurred may be determined depending on whether a coupling current has been detected or the magnitude of the coupling current.

[0141] When it is determined that the touch of the finger has occurred, during the third period (sensing period) P3, the driving signals are sequentially supplied to the driving lines Tx1 to TxN, and the sensing signals corresponding to the driving signals are detected from the sensing lines Rx1 to RxM and then supplied to the sensor circuit unit 170. Specifically, during the third period P3, as shown in FIG. Fig. 15C As shown, the fingerprint information stored in the unit sensor 142 is read out using the mutual capacitance formed between the driving line TxI and the sensing line RxJ of each unit sensor 142 .

[0142] More specifically, between each driving line (any one of Tx1 to TxN) and each sensing line (any one of Rx1 to RxM), the first capacitive element C1 and the second capacitive element C2 of the corresponding unit sensor 142 are coupled to each other via the pixel electrode PX. Thus, if the driving signal is successively provided to the driving lines Tx1 to TxN, the sensing signal that changes in the form corresponding to the driving signal is output from the corresponding sensing lines Rx1 to RxM. In addition, each sensing line (any one of Rx1 to RxM) intersects with a plurality of driving lines Tx1 to TxN. Therefore, during the period in which the driving signal is successively provided to the driving lines Tx1 to TxN, the sensing signal corresponding to the driving signal can be continuously output from each sensing line (any one of Rx1 to RxM). During the third period P3, the third capacitive element C3 together with the parasitic capacitance Cp can be used as a load. Therefore, the sensitivity of the fingerprint sensor can be adjusted, for example, by adjusting the capacitance ratio of the first to third capacitive elements C1, C2 and C3.

[0143] The fingerprint sensor may repeatedly perform the above operation in response to the fingerprint sensing mode and output a sensing signal corresponding to the shape of the fingerprint. In this case, during the third period P3, the sensor circuit unit 170 may detect the voltage input through each sensing channel in real time and accumulate (integrate) the voltage, thereby detecting the amount of charge corresponding to each unit sensor 142.

[0144] More specifically, according to an exemplary embodiment, since at least one of the first capacitive element C1 and the second capacitive element C2 is formed of a variable capacitive element, the amount of charge detected from the unit sensor 142 may differ depending on whether the unit sensor 142 contacts the ridge of the fingerprint or the valley of the fingerprint. Therefore, by synthesizing (e.g., comparing and analyzing) the amount of charge detected from the corresponding unit sensors 142, the shape of the fingerprint may be detected.

[0145] FIG. 16A to FIG. 16C is a diagram showing the operation process of a fingerprint sensor according to an exemplary embodiment. Specifically, FIG. 16A to FIG. 16C The entire operation process of the fingerprint sensor is schematically shown. FIG. 15A to FIG. 15C A detailed description of the operation process of the described unit sensor will be omitted to avoid redundancy.

[0146] like Fig.16A As shown, during a predetermined initialization period, an initialization signal having a gate-on voltage and a reset voltage Vrst are provided to the cell sensors 142. Thus, the cell sensors 142 are initialized at the same time.

[0147] Afterwards, if Fig. 16BAs shown, during a predetermined coupling period, a coupling operation is simultaneously performed on the unit sensors 142. During the coupling operation, fingerprint information (eg, a predetermined voltage Vr or Vv based on the shape of the fingerprint) is stored to each unit sensor 142.

[0148] Then, if Fig. 16C As shown, the driving lines Tx1, Tx2, ..., and TxN are sequentially operated, and the fingerprint information Vr and / or Vv is detected using the sensing signals output from the sensing lines Rx1, Rx2, ..., and RxM.

[0149] As described above, when the unit sensor 142 according to an exemplary embodiment is simultaneously operated during the initialization period and the coupling period before a sensing signal is detected, blurring may be reduced and a signal-to-noise ratio may be improved.

[0150] Fig.17 is a diagram showing the difference in blurring occurrence between coupling methods. Fig.18A and Fig.18B The electric fields formed between the fingerprint sensor and the user's finger during the individual coupling operation and the simultaneous coupling operation of the unit sensor 143 are respectively shown.

[0151] Reference Fig.17 , when the coupling operation is performed in a point scheme (or based on a point) (in which the coupling effect is generated only on a specific unit sensor 142a among the unit sensors 142 and the peripheral unit sensors 142b of the specific unit sensor 142a do not operate), an electric field is formed between the specific unit sensor 142a and the finger, as shown in FIG. Fig.18A As shown, this results in a relatively large blur.

[0152] On the other hand, when the coupling operation is performed on all the unit sensors 142 at the same time in a surface scheme (or surface-based) in which a coupling effect is generated on all the unit sensors 142, the vertical electric field formed between the unit sensor 142a and the finger is enhanced, and the spread electric field is weakened, as shown in FIG. Fig.18B As shown, this can result in relatively little blurring.

[0153] When a coupling operation is performed in a line scheme (or line-based) in which a coupling effect is generated on the unit sensor 142 based on a row or column, a moderate blur can be generated, which is smaller than the blur generated by a point scheme coupling operation and greater than the blur generated by a surface scheme coupling operation.

[0154] Since the unit sensor 142 according to an exemplary embodiment is simultaneously operated during a predetermined initialization period and a coupling period, a vertical electric field between the finger and the unit sensor 142 may be enhanced, which may reduce blur and improve a signal-to-noise ratio.

[0155] Fig.19A and Fig.19B 2 and 3 show the amount of charge detected from the unit sensor according to an exemplary embodiment and a comparative embodiment, respectively. Specifically, Fig.19A and Fig.19B A difference in the amount of charges detected during a sensing period between a unit sensor according to an exemplary embodiment and a unit sensor according to a comparative embodiment is shown, and a structure of each unit sensor is equally shown based on the sensing period.

[0156] Reference Fig.19A According to an exemplary embodiment, during the sensing period, a deviation between the charge amount Q1 of the first unit sensor 1421 and the charge amount Q2 of the second unit sensor 1422 is detected using a mutual capacitance between the driving line TxI and the sensing line RxJ. For example, during a coupling period before the sensing period, due to a difference in fingerprint patterns, it is assumed that a first voltage V1 is applied to the pixel electrode PX1 of the first unit sensor 1421, and a second voltage V2 different from the first voltage V1 is applied to the pixel electrode PX2 of the second unit sensor 1422. In this case, the CV characteristic curves of the first unit sensor 1421 and the second unit sensor 1422 are shifted to different degrees by the first voltage V1 and the second voltage V2.

[0157] More specifically, since the first capacitive element C1 and / or the second capacitive element C2 coupled to the driving line TxI and the sensing line RxJ are formed by a variable capacitive element, the mutual capacitance between the driving line TxI and the sensing line RxJ has a CV characteristic that varies depending on the voltage. In addition, according to an exemplary embodiment, the operating voltage range of the variable capacitive element may be set to include a Cmin / Cmax transition period of the CV characteristic curve.

[0158] Therefore, when the CV characteristic curves of the first unit sensor 1421 and the second unit sensor 1422 are shifted to different degrees by the deviation of the first voltage V1 and the second voltage V2, the charge amounts Q1 and Q2 detected from the first unit sensor 1421 and the second unit sensor 1422, respectively, during the sensing period may be different from each other. Therefore, the deviation between the first voltage V1 and the second voltage V2 may be detected by detecting the deviation between the charge amounts Q1 and Q2. In this way, the shape of the fingerprint may be detected.

[0159] On the other hand, according to Fig.19BAccording to the comparative embodiment, the unit sensors 1421' and 1422' are formed of fixed capacitive elements, in which the first capacitive element C1 and the second capacitive element C2 have constant capacitance regardless of the first voltage V1 and the second voltage V2 respectively applied to the pixel electrodes PX1 and PX2. Therefore, in the unit sensors 1421' and 1422' according to the comparative embodiment, the charge amounts Q1' and Q2' detected during the sensing period are substantially the same as each other regardless of the first voltage V1 and the second voltage V2 respectively applied to the pixel electrodes PX1 and PX2. Thus, the unit sensors 1421' and 1422' according to the comparative embodiment cannot detect the shape of a fingerprint.

[0160] Fig. 20 is a diagram illustrating a layout of a unit sensor according to an exemplary embodiment. Fig. 20 The layout of the unit sensor will be described as having Fig. 11B The layout of the unit sensor is shown. Fig.21 A cross-sectional view of a unit sensor according to an exemplary embodiment is shown, which illustrates a cross-sectional structure of a circuit element of the unit sensor.

[0161] Reference Fig. 20 and Fig.21 , the driving lines TxI and TxI+1 and the sensing lines RxJ-1 and RxJ extend in the first direction and the second direction respectively crossing each other. The pixel electrode PX is disposed in a corresponding region defined between the driving lines TxI and TxI+1 and the sensing lines RxJ-1 and RxJ. In addition, the initialization signal line VINIT and the common power line VCOM are further disposed around the unit sensor 142. As described above, the common power line VCOM may be omitted in some exemplary embodiments. For example, when the layout of the unit sensor according to an exemplary embodiment does not include the following Fig.11A The common power line VCOM shown in the figure can also be Fig. 20 and Fig.21 is omitted.

[0162] According to an exemplary embodiment, a plurality of initialization signal lines VINIT may extend in the first direction and be disposed adjacent to the corresponding driving lines TxI and TxI+1, but the inventive concept is not limited thereto. Specifically, the initialization signal line VINIT may extend in the first direction or the second direction or be formed in a grid shape and disposed around the unit sensor 142.

[0163] According to an exemplary embodiment, the common power line VCOM may be formed to have a grid shape surrounding the pixel electrode PX at a position spaced apart from the corresponding pixel electrode PX. For example, the common power line VCOM may have an opening corresponding to the corresponding pixel electrode PX and be arranged to overlap with the drive lines TxI and TxI+1, the sensing lines RxJ-1 and RxJ, and the initialization signal line VINIT. In addition, the common power line VCOM may be arranged on a different layer from the drive lines TxI and TxI+1, the sensing lines RxJ-1 and RxJ, and the initialization signal line VINIT, and be spaced apart from them. For example, the common power line VCOM may be arranged on the same layer as the pixel electrode PX and be spaced apart from the pixel electrode PX by a predetermined distance.

[0164] According to an exemplary embodiment, the drain electrode DE and the gate electrode GE of each switching element T1 may be formed by a portion of the sensing line RxJ-1 protruding from an adjacent unit sensor disposed on a previous column and a portion of the initialization signal line VINIT protruding therefrom and crossing the sensing line RxJ-1, respectively. The active layer ACT may be disposed to overlap the drain electrode DE and the gate electrode GE. A portion of the active layer ACT may be coupled to the drain electrode DE, and another portion of the active layer ACT may be coupled to the pixel electrode PX of the corresponding unit sensor 142 via the source electrode SE.

[0165] According to an exemplary embodiment, the switching element T1 may have a bottom gate structure. For example, the switching element T1 may include a gate electrode GE disposed on the sensor substrate 141, an active layer ACT disposed on the gate electrode GE (with the first insulating layer INS1 interposed between the gate electrode GE and the active layer ACT), and a drain electrode DE and a source electrode SE disposed on respective opposite ends of the active layer ACT. In this case, the initialization signal line VINIT may be provided integrally with the gate electrode GE of the switching element T1 and disposed in the gate layer on the sensor substrate 141.

[0166] The active layer ACT of the switching element T1 may be disposed on the first insulating layer INS1 as a semiconductor layer. In an exemplary embodiment, the active layer ACT may be formed of, for example, an oxide semiconductor. The material of the active layer ACT is not limited thereto, and the active layer ACT may be formed of various known semiconductor materials.

[0167] The drain electrode DE and the source electrode SE of the switching element T1 may be disposed in a source-drain layer above the semiconductor layer and electrically coupled to respective different ends of the active layer ACT. In this case, the sensing lines RxJ-1 and RxJ may be integrally provided with the drain electrode DE of the switching element T1 and disposed in the source-drain layer.

[0168] The structure of the switching element T1 is not limited to Fig. 20 and Fig.21 For example, the switching element T1 may have various known transistor structures.

[0169] The second and third insulating layers INS2 and INS3 may be disposed on the switching element T1. The pixel electrode PX may be disposed on the second and third insulating layers INS2 and INS3. The pixel electrode PX may be electrically coupled to the switching element T1 through a first via hole VH1 passing through the second and third insulating layers INS2 and INS3. Fig.21 It is shown that both the second insulating layer INS2 and the third insulating layer INS3 are provided between the switching element T1 and the pixel electrode PX, but the present inventive concept is not limited thereto. For example, at least one of the second insulating layer INS2 and the third insulating layer INS3 may be provided between the switching element T1 and the pixel electrode PX. As another example, any one of the second insulating layer INS2 and the third insulating layer INS3 may be omitted, or the second insulating layer INS2 and the third insulating layer INS3 may be integrated into a single insulating layer. According to an exemplary embodiment, only the third insulating layer INS3 may be provided between the switching element T1 and the pixel electrode PX.

[0170] In an exemplary embodiment, the first capacitive element C1 may include a first electrode CET11 having a first conductive pattern and a second electrode CET12 having a stacked structure including a semiconductor pattern SEM and a second conductive pattern CON. In other words, the first capacitive element C1 may be formed of a variable capacitive element such as a metal insulator semiconductor (MIS) or a metal insulator semiconductor metal (MISM) capacitor. In an exemplary embodiment, the semiconductor pattern SEM may be formed of, for example, an oxide semiconductor, but the inventive concept is not limited thereto. The first electrode CET11 and the second conductive pattern CON may be formed of various conductive materials known in the art, such as metal.

[0171] In an exemplary embodiment, the first electrode CET11 of the first capacitive element C1 may be formed by a portion of the corresponding driving line TxI protruding therefrom and disposed in the gate layer together with the driving line TxI. In an exemplary embodiment, the semiconductor pattern SEM and the second conductive pattern CON of the first capacitive element C1 may overlap the first electrode CET11 and the pixel electrode PX. For example, the semiconductor pattern SEM may be disposed on the same layer as the active layer ACT of the switching element T1 and overlap the first electrode CET11 and the pixel electrode PX. The second conductive pattern CON may be disposed on the same layer as the drain electrode DE and the source electrode SE of the switching element T1 and overlap the semiconductor pattern SEM. The second electrode CET12 of the first capacitive element C1 may be formed by electrically connecting the semiconductor pattern SEM and the second conductive pattern CON to each other via direct / indirect contact connection. The second electrode CET12 may be electrically connected to the pixel electrode PX by passing through the second via hole VH2 of the second insulating layer INS2 and the third insulating layer INS3.

[0172] In an exemplary embodiment, the second capacitive element C2 may include a first electrode CET21 and a second electrode CET22, each of which is formed of a conductor. In an exemplary embodiment, the first electrode CET21 of the second capacitive element C2 may protrude from a portion of the corresponding sensing line RxJ and be integrally disposed with the sensing line RxJ in the source / drain layer. The first electrode CET21 may protrude from the sensing line RxJ and overlap the corresponding pixel electrode PX, so that the second capacitive element C2 is formed between the first electrode CET21 and the pixel electrode PX. More specifically, according to an exemplary embodiment, the second electrode CET22 of the second capacitive element C2 may be integrally formed with the pixel electrode PX.

[0173] In an exemplary embodiment, the third capacitive element C3 may include a first electrode CET31 and a second electrode CET32, each of which is formed of a conductor. In an exemplary embodiment, the first electrode CET31 of the third capacitive element C3 may protrude from a portion of the initialization signal line VINIT and be integrally disposed in the gate layer with the initialization signal line VINIT. The first electrode CET31 of the third capacitive element C3 may protrude from the initialization signal line VINIT and overlap the corresponding pixel electrode PX, so that the third capacitive element C3 is formed between the first electrode CET31 and the pixel electrode PX. More specifically, according to an exemplary embodiment, the second electrode CET32 of the third capacitive element C3 may be integrally formed with the pixel electrode PX.

[0174] In an exemplary embodiment, a black matrix 180 for preventing external light reflection may be further disposed on a portion of the pixel electrode PX. For example, the black matrix 180 may be disposed to overlap the second capacitive element C2 and the third capacitive element C3.

[0175] The unit sensor 142 may be formed by a plurality of mask processes. For example, the unit sensor 142 may be formed by the following mask processes: a first mask process for patterning the lines and / or circuit elements of the gate layer, a second mask process for patterning the semiconductor elements of the semiconductor layer, a third mask process for patterning the lines and / or circuit elements of the source and drain layers, a fourth mask process for forming the first via hole VH1 and the second via hole VH2, a fifth mask process for patterning the pixel electrode PX, and a sixth mask process for patterning the black matrix 180. In an exemplary embodiment, some mask processes may be integrated to reduce the number of mask processes. For example, the lines and / or circuit elements disposed on two consecutive layers may be patterned simultaneously using a halftone mask or the like. In addition, by integrating the second mask process and the third mask process or the fifth mask process and the sixth mask process, the process of manufacturing the unit sensor 142 may be simplified.

[0176] Fig. 22 and Fig.23 shows the layout of a unit sensor according to an exemplary embodiment, and more specifically, shows Fig. 20 The layout shown is modified accordingly. Fig. 22 and Fig.23 In the drawings, the same reference numerals are used to denote Fig. 20 The elements in the drawings are the same or similar elements, and therefore, repeated descriptions thereof will be omitted to avoid redundancy.

[0177] Reference Fig. 22 , the pixel electrode PX of each unit sensor 142 can be arranged above the intersection between the corresponding driving line TxI and the corresponding sensing line RxJ, so that the pixel electrode PX overlaps the driving line TxI and the sensing line RxJ. In this case, the switching element T1 can be connected between the corresponding sensing line RxJ and the pixel electrode PX. The circuit elements of each unit sensor 142 (such as the switching element T1 and the first to third capacitive elements C1, C2 and C3) can be densely arranged with each other under the corresponding pixel electrode PX.

[0178] In this way, each pixel electrode PX can be designed to have a reduced size (surface area), which can reduce the blurring effect. In addition, the capacitive elements (e.g., the first to third capacitive elements C1, C2, and C3) of each unit sensor 142 can be configured using parasitic capacitance formed between the corresponding pixel electrode PX and the line (e.g., the corresponding drive line TxI, the corresponding sensing line RxJ, and the initialization signal line VINIT). Thus, the transmittance of the fingerprint sensing area FSA can be improved, and the image quality can be prevented from being degraded due to the moire phenomenon.

[0179] Reference Fig.23 , the pixel electrode PX of each unit sensor 142 may be patterned into a circular shape. In an exemplary embodiment, the common power line VCOM may have a grid shape and be disposed in an area defined between the unit sensors 142 so that the common power line VCOM is spaced apart from each pixel electrode PX by a predetermined distance. In this case, the common power line VCOM may be provided in an area facing each pixel electrode PX and have a shape corresponding to the pixel electrode PX.

[0180] In this manner, since the pixel electrode PX has a circular shape, the fringe field can be minimized. Thus, the crosstalk between the unit sensors 142 can be minimized, and the reliability of the fingerprint sensor can be improved.

[0181] FIG. 24A to FIG. 24D is a cross-sectional view of a variable capacitance element 200 according to an exemplary embodiment.

[0182] Reference Fig.24A , the variable capacitance element 200 may include a first conductive pattern 210, a semiconductor pattern 220, an insulating layer 230, and a second conductive pattern 240 sequentially stacked on the sensor substrate 141. In an exemplary embodiment, the first conductive pattern 210 and the semiconductor pattern 220 may be electrically coupled to each other to form a first electrode of the variable capacitance element 200. The second conductive pattern 240 may be spaced apart from the first conductive pattern 210 and the semiconductor pattern 220 with the insulating layer 230 interposed therebetween, and may form a second electrode of the variable capacitance element 200.

[0183] The first conductive pattern 210 and the second conductive pattern 240 may be formed of various conductive materials, such as metals, alloys thereof, conductive polymers, and conductive metal oxides. In addition, the first conductive pattern 210 and the second conductive pattern 240 may each have a single-layer structure or a multi-layer structure, and may include the same conductive material or different conductive materials.

[0184] The semiconductor pattern 220 may be formed of an oxide semiconductor, such as ZnO, ZTO, ZIO, IZO, InO, TiO, IGZO, or IZTO, but is not limited thereto. For example, the semiconductor pattern 220 may be formed of at least one of various materials capable of forming an active layer of a known thin film transistor. In an exemplary embodiment, impurities may be doped into a portion of the semiconductor pattern 220 to form a contact or control a carrier concentration.

[0185] The insulating layer 230 may include at least one organic layer and / or inorganic layer and have a single layer structure or a multi-layer structure. In other words, the material and structure of the insulating layer 230 are not particularly limited.

[0186] Reference Fig. 24B , the positions of the semiconductor pattern 220 and the insulating layer 230 may be exchanged with each other. For example, the variable capacitance element 200 may include a first conductive pattern 210, an insulating layer 230, a semiconductor pattern 220, and a second conductive pattern 240 sequentially stacked on the sensor substrate 141. In this case, the first electrode of the variable capacitance element 200 may be formed by the first conductive pattern 210, and the second electrode of the variable capacitance element 200 may be formed by the semiconductor pattern 220 and the second conductive pattern 240.

[0187] Reference Fig.24C and Fig.24D , the variable capacitance element 200 may have a coplanar or anti-coplanar structure. For example, the first conductive pattern 210 and the second conductive pattern 240 may be disposed on substantially the same layer and formed by the same mask process. In addition, the first conductive pattern 210 and the semiconductor pattern 220 may be electrically coupled to each other through a predetermined region, thereby forming one electrode of the variable capacitance element 200.

[0188] According to an exemplary embodiment, at least one of the first capacitive element C1 and the second capacitive element C2 of the unit sensor 142 may include FIG. 24A to FIG. 24D For example, in the variable capacitance element 200 of any one of the structures shown in Fig.21 In the example, the first capacitive element C1 has Fig. 24B The structure shown, but the first capacitive element C1 may have Fig.24A , Fig.24C or Fig.24D In addition, as described above, the second capacitive element C2 may have a variable capacitance. For example, the second capacitive element C2 may have a FIG. 24A to FIG. 24D However, the structure of the first capacitive element C1 and / or the second capacitive element C2 is not limited to FIG. 24A to FIG. 24Dthose shown, and the structures of the first capacitive element C1 and / or the second capacitive element C2 may be changed in various ways.

[0189] Various exemplary embodiments of the present invention may provide a fingerprint sensor having high sensitivity and high reliability and a display device having the same.

[0190] Specifically, according to an exemplary embodiment, a self-capacitance pixel electrode PX may be formed in each unit sensor 142, and the self-capacitance pixel electrode PX forms a contact capacitance by contacting with a contact means. The pattern (ridge or valley) information of the fingerprint may be converted into a voltage to be applied to each corresponding pixel electrode PX through a coupling operation. According to an exemplary embodiment, at least one variable capacitance element 200 (e.g., a first capacitance element C1 and / or a second capacitance element C2) may be coupled between the driving lines Tx1 to TxN and the sensing lines Rx1 to RxM. During a predetermined sensing period, two adjacent unit sensors 142 (see Fig.19A The difference between the charge amounts Q1 and Q2 of 1421 and 1422) can be detected in a mutual capacitance scheme using a CV characteristic deviation of the variable capacitance element 200, thereby detecting the shape of the fingerprint.

[0191] According to an exemplary embodiment, the sensitivity of the fingerprint sensor can be improved to a degree similar to that of a self-capacitive touch or fingerprint sensor. In addition, the reliability of the fingerprint sensor can be improved by using a CV characteristic that does not vary significantly depending on the characteristic deviation of the transistor, temperature, and / or external light. In addition, the capacitance of the variable capacitance element 200 can be increased by adjusting the design value of the variable capacitance element 200. Therefore, the signal-to-noise ratio can be improved compared to a typical mutual capacitance touch / fingerprint sensor.

[0192] In addition, the difference between the charge amounts Q1 and Q2 of the two adjacent unit sensors 142 is detected in a mutual capacitance scheme during the sensing period. Therefore, for example, when a fingerprint sensor is provided in a display device together with a mutual capacitance type touch sensor, both the touch sensor and the fingerprint sensor can be driven using a single sensor driving circuit 172. In this way, the configuration of the sensor circuit unit 170 can be simplified and its manufacturing cost can be reduced. In addition, during the sensing period, since the difference between the charge amounts Q1 and Q2 of the two adjacent unit sensors 142 is detected in a mutual capacitance scheme, multi-touch and multi-channel can be sensed.

[0193] In addition, according to an exemplary embodiment, the switching element T1 can be used to initialize the pixel electrode PX or float the pixel electrode PX. The switching element T1 can be a transistor or the like. The switching element T1 can be provided to perform a simple switching operation, but unlike the sensor using the current sensing scheme, the switching element T1 is not used to generate a driving current. Therefore, compared with the transistor used in the current sensing scheme, the characteristic conditions required for the switching element T1 can be relatively easy to meet. Therefore, the switching element T1 can be formed by a high temperature process or a low temperature process. As a result, the process of forming the fingerprint sensor can be further facilitated and its manufacturing cost can be reduced.

[0194] Although certain exemplary embodiments and implementations have been described herein, other embodiments and modifications will become apparent from this description. Therefore, the inventive concept is not limited to such embodiments, but rather to the broader scope of the claims and various obvious modifications and equivalent arrangements (as will be apparent to those of ordinary skill in the art).

[0195] This application claims priority to and the benefit of Korean Patent Application No. 10-2017-0147916, filed on November 8, 2017, which is hereby incorporated by reference for all purposes as if fully set forth herein.

Claims

1. A fingerprint sensor, comprising: First, second, and third lines; as well as a unit sensor coupled to the first line, the second line, and the third line, The unit sensor comprises: a pixel electrode connected between the first line and the second line; A first capacitor element connected between the first line and the pixel electrode; A second capacitor element is connected between the second line and the pixel electrode; a switching element coupled between the first line, the second line, one of a first line of an adjacent unit sensor, and a second line of the adjacent unit sensor, and the pixel electrode, and including a gate electrode coupled to the third line; and a third capacitor element connected between the third line and the pixel electrode, and At least one of the first capacitive element and the second capacitive element includes a variable capacitive element. 2 . The fingerprint sensor according to claim 1 , further comprising a fourth line disposed around the unit sensor and configured to form a parasitic capacitance between the fourth line and the pixel electrode. The fingerprint sensor according to claim 2 , wherein the fourth line surrounds the pixel electrode.

4. The fingerprint sensor according to claim 1, wherein: The first line and the second line extend in different directions to cross each other; and The pixel electrode is disposed in a unit area defined by the first line and the second line. The fingerprint sensor according to claim 1 , wherein the pixel electrode has a circular shape. 6 . The fingerprint sensor of claim 1 , wherein at least one of the first capacitive element and the second capacitive element comprises a metal insulator semiconductor (MIS) or a metal insulator semiconductor metal (MISM) capacitive element.

7. The fingerprint sensor according to claim 1, wherein: The first line is provided in plurality; The second line is provided in plurality; and The unit sensor is provided in plural and the plurality of unit sensors are disposed in respective unit areas corresponding to intersections between the first line and the second line. 8 . The fingerprint sensor according to claim 7 , further comprising a fourth line disposed between the plurality of unit sensors and configured to form a parasitic capacitance between the fourth line and the pixel electrode of each of the unit sensors.

9. The fingerprint sensor according to claim 8, wherein: During an initialization period, the plurality of unit sensors are simultaneously provided with an initialization signal through the third line; and During a period in which the initialization signal is supplied, a line of the first line and the second line coupled to the switching element is simultaneously supplied with a reset voltage. 10 . The fingerprint sensor of claim 9 , wherein the fourth line is supplied with the reset voltage during the period in which the initialization signal is supplied.

11. The fingerprint sensor according to claim 9, wherein: During a sensing period after the initialization period, the first lines are sequentially provided with a driving signal; and During the sensing period, a sensing signal is output through the second line. 12 . The fingerprint sensor according to claim 7 , wherein the pixel electrode of each of the unit sensors is provided in a region between the first line and the second line.

13. The fingerprint sensor according to claim 7, wherein the pixel electrode of each of the unit sensors is disposed above a crossing point between the first line and the second line such that the pixel electrode overlaps any one of the first line and the second line.

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