Display device and mobile terminal device including the same

Abstract

The present invention relates to a display device and a mobile terminal including the same, comprising a display area in which a plurality of pixels are arranged, and a display panel including a sensing area in which a plurality of photo sensors and a plurality of pixels are arranged. The pixels of the display area (DA) and the pixels of the first sensing area emit light when supplied with a data voltage of an input image in display mode. At least some of the pixels of the sensing area (DA) emit light in fingerprint recognition mode.

Description

Technology Field

[0001] The present invention relates to a display device having a fingerprint sensor and a mobile terminal including the same. Background Technology

[0002] Electroluminescent display devices are broadly classified into inorganic light-emitting displays and organic light-emitting displays based on the material of the light-emitting layer. Active matrix type organic light-emitting displays include self-emissive Organic Light Emitting Diodes (OLEDs) and offer the advantages of fast response speed, high luminous efficiency, brightness, and high viewing angles. In organic light-emitting displays, OLEDs are formed in each pixel. Organic light-emitting displays not only offer fast response speeds and excellent luminous efficiency, brightness, and viewing angles, but also superior contrast ratio and color reproduction because they can express black gradations as perfect black.

[0003] Recently, there has been a growing trend of applying organic light-emitting diodes (OLEDs) to the displays of mobile devices. Biometric technology is also being applied to user authentication in mobile devices. As an example of biometric technology, fingerprint sensors are widely used in smartphones because they provide both security and convenience during the user authentication process. Fingerprint sensors applied to smartphones sense the user's fingerprint when screen unlocking or user authentication is required.

[0004] Fingerprint sensors have imposed many limitations on smartphone screen design. For example, conventional button-type fingerprint sensors are placed beneath the display screen, acting as an obstacle that prevents the implementation of a full-screen display by increasing screen size. To enable full-screen displays, Fingerprint Recognition on Display (FOD) technology is being developed, which places the fingerprint sensor beneath the screen and senses fingerprints on the screen. However, because the camera must be placed beneath the screen to implement FOD, the thickness of the display increases, and the addition of assembly processes for the display panel and camera leads to reduced yield and increased manufacturing costs. The problem to be solved

[0005] The present invention aims to solve the aforementioned necessities and / or problems.

[0006] In particular, the present invention provides a display device that eliminates the need for an assembly process of a display panel and a fingerprint sensor module and can improve the image quality of the fingerprint sensing area and the fingerprint sensing performance, and a mobile terminal including the same.

[0007] The problems of the present invention are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0008] A display device according to one embodiment of the present invention includes a display panel (100) comprising a display area (DA) in which a plurality of pixels are arranged, and a sensing area (SA) in which a plurality of photo sensors and a plurality of pixels are arranged. The pixels of the display area (DA) and the pixels of the first sensing area emit light when supplied with a data voltage of an input image in display mode. At least some of the pixels of the sensing area (DA) emit light in fingerprint recognition mode.

[0009] A mobile terminal according to one embodiment of the present invention includes the display device. Effects of the invention

[0010] In this invention, photosensors for fingerprint sensing are embedded in a display panel along with pixels. This invention simplifies the structure of the display panel by sharing power and signal wiring between the pixel driving circuit and the photosensor driving circuit, and by placing the electrodes of the light-emitting element and the photodiode on the same layer. Furthermore, this invention additionally arranges light sources to obtain good fingerprint images in a sensing area with a low PPI (Pixels Per Inch). As a result, this invention eliminates the need for an assembly process between the display panel and the fingerprint sensor module, and can improve the image quality and fingerprint sensing performance of the fingerprint sensing area. The lower the PPI of the sensing area, the greater the number of light sources placed in the sensing area.

[0011] The present invention can improve the accuracy of fingerprint recognition by repeatedly sensing fingerprint patterns while varying the brightness of a light source in a sensing area, and processing fingerprint authentication based on a fingerprint pattern image with high clarity among the fingerprint pattern images.

[0012] The present invention can compensate for the decrease in brightness of the sensing area by controlling the brightness of pixels used as light sources in a sensing area with low PPI to be higher than the pixel brightness of the display area.

[0013] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims. Brief explanation of the drawing

[0014] FIGS. 1 and 2 are schematic drawings illustrating a display device according to an embodiment of the present invention. FIG. 3 is a flowchart showing a method of driving a first sensing area in a fingerprint recognition mode according to an embodiment of the present invention. FIG. 4 is a drawing showing an example of pixel arrangement in a display area according to an embodiment of the present invention. FIG. 5 is a drawing showing a pixel, a photosensor, and a light source of a first sensing area according to an embodiment of the present invention. FIG. 6 is a drawing showing the arrangement of pixels and light-emitting parts of a second sensing area according to an embodiment of the present invention. FIG. 7 is a diagram showing the cross-sectional structure of an organic photodiode and a pixel according to one embodiment of the present invention. FIG. 8 is a diagram showing the cross-sectional structure of an inorganic photodiode and a pixel according to one embodiment of the present invention. FIG. 9 is a diagram showing in detail the arrangement of a light source for fingerprint sensing in the first sensing area illustrated in FIG. 5. FIGS. 10a to 10d are drawings showing the operation of the first sensing area illustrated in FIG. 9. FIG. 11 is a drawing showing an example of the arrangement of pixels, photosensors, and light sources in a first sensing area according to another embodiment of the present invention. FIGS. 12 and FIGS. 13 are drawings showing a pixel, a photosensor, and a light source of a first sensing area according to another embodiment of the present invention. FIG. 14 is a flowchart showing an example of a fingerprint authentication method that selects a high-clarity fingerprint pattern image while changing the number of light sources illuminated in the fingerprint recognition mode. FIG. 15 is a block diagram showing a display panel and a display panel driving unit according to an embodiment of the present invention. Figure 16 is a block diagram schematically showing the drive IC configuration. Figure 17 is a circuit diagram showing an example of a pixel circuit. Figure 18 is a circuit diagram showing another example of a pixel circuit. FIG. 19 is a diagram showing a driving method of the pixel circuit illustrated in FIG. 17 and FIG. 18. FIG. 20 is a cross-sectional view showing in detail the cross-sectional structure of a display panel according to one embodiment of the present invention. FIGS. 21 and 22 are equivalent circuit diagrams showing a wiring sharing structure between a pixel circuit and a photosensor driving circuit according to an embodiment of the present invention. Figure 23 is a diagram showing the metal layers of the pixel circuit and the photosensor driving circuit. FIG. 24 is a plan view showing the layout of the pixel circuit and the photosensor driving circuit in detail. FIGS. 25a to 25 are plan views showing the pattern shape of each layer by separating the main layers in the layout of the pixel circuit and photosensor driving circuit shown in FIG. 24. FIG. 26 is a circuit diagram showing a gamma reference voltage section according to one embodiment of the present invention. FIG. 27 is a diagram showing the data voltage applied to the pixels of the display area and the data voltage applied to the pixels of the sensing area. Specific details for implementing the invention

[0015] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims.

[0016] The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for explaining embodiments of the present invention are exemplary, and therefore the present invention is not limited to the depicted details. Throughout the specification, the same reference numerals refer to the same components. Furthermore, in describing the present invention, if it is determined that a detailed description of related known technology may unnecessarily obscure the essence of the present invention, such detailed description is omitted.

[0017] Where terms such as 'includes,' 'have,' 'consists of,' etc. are used in this specification, other parts may be added unless 'only' is used. Where a component is expressed in the singular, it includes cases where it includes the plural unless specifically stated otherwise.

[0018] In interpreting the components, they are interpreted to include a margin of error even in the absence of a separate explicit statement.

[0019] In the case of describing a positional relationship, for example, when the positional relationship between two parts is described using expressions such as 'on top of,' 'above,' 'below,' or 'next to,' one or more other parts may be located between the two parts unless 'immediately' or 'directly' is used.

[0020] In the description of the embodiments, terms such as "first," "second," etc. are used to describe various components, but these components are not limited by these terms. These terms are used merely to distinguish one component from another. Accordingly, the first component mentioned below may be the second component within the technical scope of the present invention.

[0021] Throughout the specification, the same reference numerals refer to the same components.

[0022] The features of various embodiments may be combined or combined with one another, either partially or wholly, and technically various interlocking and operation are possible. Each embodiment may be implemented independently of one another or together in an associated relationship.

[0023] Hereinafter, various embodiments of the present invention will be described in detail with reference to the attached drawings.

[0024] Referring to FIGS. 1 and 2, the screen of the display panel (100) includes a display area (DA), a first sensing area (SA), and a second sensing area (CA). The display panel (100) includes a pixel array in which pixels of the display area (DA), the first sensing area (SA), and the second sensing area (CA) are arranged. The number of pixels per unit area, i.e., PPI (Pixels Per Inch), of the first and second sensing areas (SA, CA) is lower than the PPI of the display area (DA) in order to secure the transmittance of the second sensing area (CA) in the imaging mode.

[0025] delete

[0026] The input image is reproduced on sensing areas (SA, CA) and a display area (DA). Each pixel includes subpixels of different colors to realize the color of the image. The subpixels include a red subpixel (Red, hereinafter referred to as "R subpixel"), a green subpixel (Green, hereinafter referred to as "G subpixel"), and a blue subpixel (Blue, hereinafter referred to as "B subpixel"). Although not illustrated, each pixel (P) may further include a white subpixel (White, hereinafter referred to as "W subpixel"). Each subpixel includes a pixel circuit and a light-emitting element (OLED). In the following drawings, R represents the R subpixel, G represents the G subpixel, and B represents the B subpixel.

[0027] The first sensing area (SA) includes photosensors (S) and pixels (R, G, B). The photosensors (S) of the first sensing area (CA) may be formed on the same plane as the pixels (R, G, B) without overlapping with them. The pixels of the first sensing area (SA) display an input image by writing pixel data in display mode. The photosensors (S) of the first sensing area (SA) are operated in fingerprint recognition mode to sense a fingerprint pattern by converting light reflected from a user's fingerprint in contact with the cover glass (20) into an electric current. The output of the photosensors is converted into fingerprint pattern image data used for user fingerprint authentication.

[0028] At least one of the pixels of the first sensing area (CA) can be driven by a light source in fingerprint recognition mode.

[0029] The second sensing area (CA) includes pixels and a camera module positioned below the screen of the display panel (100). The pixels of the second sensing area (CA) display an input image by writing pixel data in display mode. The camera module captures an external image in imaging mode and outputs photo or video image data. The lens of the camera module faces the second sensing area (CA). External light is incident on the lens (30) of the camera module through the second sensing area (CA), and the lens (30) collects light onto an image sensor, which is omitted from the drawing.

[0030] The PPI (Pixels Per Inch) of the first and second sensing areas (SA, CA) is lower than the PPI of the display area (DA). The PPI of the first sensing area (SA) may be equal to the PPI of the second sensing area (CA). An image quality compensation algorithm may be applied to compensate for the luminance and color coordinates of pixels in the first and second sensing areas (SA, CA) due to pixels removed in the first and second sensing areas (SA, CA).

[0031] The present invention enables the implementation of a full-screen display by displaying images in a display area (DA), a first sensing area (SA), and a second sensing area (CA). Since the present invention does not attach a separate fingerprint sensor module to the display panel, there is no reduction in yield caused by the assembly process of the display panel and the camera, and manufacturing costs can be lowered.

[0032] The first sensing area (SA) may lack a light source due to low PPI. The lower the PPI of the first sensing area (SA), the more light sources are required for sensing. The present invention utilizes display pixels as light sources in a fingerprint recognition mode and may also additionally place a separate light source for sensing in the sensing area (SA).

[0033] As illustrated in FIGS. 1 and 2, the display panel (100) has a width in the X-axis direction, a length in the Y-axis direction, and a thickness in the Z-axis direction. The display panel (100) includes a circuit layer (12) disposed on a substrate and a light-emitting element and sensor layer (14) disposed on the circuit layer (12). A polarizer (18) may be disposed on the light-emitting element and sensor layer (14), and a cover glass (20) may be disposed on the polarizer (18).

[0034] The circuit layer (12) may include a pixel circuit connected to data lines, gate lines, and power lines, a gate driver connected to the gate lines, a photosensor driving circuit, etc. The circuit layer (12) may include circuit elements such as a transistor implemented as a TFT (Thin Film Transistor) and a capacitor.

[0035] The light-emitting element and sensor layer (14) may include a light-emitting element driven by a pixel circuit. The light-emitting element may be implemented as an OLED. The OLED includes an organic compound layer formed between an anode and a cathode. The organic compound layer may include, but is not limited to, a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), and an electron injection layer (EIL). When voltage is applied to the anode and cathode of the OLED, holes passing through the hole transport layer (HTL) and electrons passing through the electron transport layer (ETL) move to the emission layer (EML) to form excitons, and as a result, visible light is emitted from the emission layer (EML). The light-emitting element and sensor layer (14) may further include a color filter array disposed on pixels that selectively transmit red, green, and blue wavelengths.

[0036] The light-emitting element and sensor layer (14) include a photosensor (S) formed on the same layer as the light-emitting elements. The photosensor (S) can be implemented as an organic / inorganic photodiode with a PN junction diode structure.

[0037] The light-emitting element and sensor layer (14) may be covered by a protective film, and the protective film may be covered by an encapsulation layer. The protective layer and the encapsulation layer may have a structure in which an organic film and an inorganic film are alternately stacked. The inorganic film blocks the penetration of moisture or oxygen. The organic film flattens the surface of the inorganic film. When the organic film and the inorganic film are stacked in multiple layers, the path of movement of moisture or oxygen is longer compared to a single layer, so the penetration of moisture / oxygen affecting the light-emitting element and sensor layer (14) can be effectively blocked.

[0038] A polarizing plate (18) may be bonded to the encapsulation layer. The polarizing plate (18) improves the outdoor visibility of the display device. The polarizing plate (18) reduces light reflected from the surface of the display panel (100) and blocks light reflected from the metal of the circuit layer (12), thereby improving the brightness of the pixels. The polarizing plate (18) may be implemented as a polarizing plate or a circular polarizing plate in which a linear polarizing plate and a phase delay film are bonded.

[0039] FIG. 3 is a flowchart showing a method of driving a first sensing area (SA) in a fingerprint recognition mode according to an embodiment of the present invention.

[0040] Referring to FIG. 3, when a fingerprint sensing event occurs, the first sensing area (SA) begins to operate in fingerprint recognition mode. A host system, which is omitted from the drawing, is connected to a display device and generates a fingerprint sensing event in an application requiring user authentication, receives fingerprint pattern image data from the display device, and processes fingerprint authentication.

[0041] The display device can indicate the fingerprint sensing location by displaying the first sensing area (SA) when the fingerprint recognition mode starts (S01, S02). The host system detects a finger placed in the first sensing area (SA) according to the output signal of the touch sensor or pressure sensor (S03). In response to a command from the host system, the display device drives the light sources and photosensors (S) in the first sensing area (SA) to sense the fingerprint (S04 and S05). The photosensors (S) convert light reflected from the user's fingerprint into photoelectric power in the fingerprint recognition mode. A fingerprint recognition processor, omitted from the drawing, converts the output of the photosensors (S) into digital data to generate fingerprint pattern image data and transmits this data to the host system. The host system processes fingerprint authentication by comparing the fingerprint pattern image data with the user's pre-set fingerprint pattern data.

[0042] FIG. 4 is a diagram showing an example of pixel arrangement in a display area (DA). FIG. 5 is a diagram showing an example of pixel, photosensor, and light source arrangement in a first sensing area (SA). FIG. 6 is a diagram showing an example of pixel and light-emitting unit arrangement in a second sensing area (CA). In FIG. 4 through 6, wiring connected to pixels and wiring connected to photosensors are omitted.

[0043] Referring to FIG. 4, the display area (DA) includes pixels (PIX1, PIX2) arranged in a matrix form. The pixels can be implemented as real color pixels composed of R, G, and B subpixels of the three primary colors. Additionally, the pixels can be composed of two subpixels as one pixel using a subpixel rendering algorithm. For example, the first pixel (PIX1) can be composed of R and G subpixels, and the second pixel (PIX2) can be composed of B and G subpixels. The lack of color representation in each of the pixels (PIX1, PIX2) can be compensated by the average value of the corresponding color data between neighboring pixels.

[0044] Referring to FIG. 5, the first sensing area (CA) includes a pixel group (PG) spaced apart by a predetermined distance (D0), photosensors (S) spaced apart at equal intervals between adjacent pixel groups, and light sources (SL) spaced apart at equal intervals between adjacent pixel groups. A subpixel (G) used as a light source (SL) can operate as a sensing light source that emits light in fingerprint recognition mode, while being off in display mode.

[0045] A pixel group (PG) may contain one or two pixels. Each pixel in a pixel group may contain two to four subpixels. For example, one pixel within a pixel group may contain R, G, and B subpixels, or contain two subpixels and further include a W subpixel. A first pixel (PIX1) may be composed of R and G subpixels, and a second pixel (PIX2) may be composed of B and G subpixels. Each of the photosensors (S) includes an organic / inorganic photodiode. The distance (D1) between adjacent photosensors (S) in each of the four directions (X, Y, Θx, and Θy) is substantially the same. The X-axis and Y-axis represent orthogonal two-axis directions. Θx and Θy represent oblique axis directions shifted 45° from the X-axis and Y-axis, respectively. The distance (D2) between neighboring light sources (SL) in each of the four directions (X, Y, Θx and Θy) is substantially the same. The light sources (SL) are illuminated in fingerprint recognition mode and can be implemented as subpixels of a specific color, preferably G subpixels. In FIG. 5, the distance (D1) between neighboring photosensors (S) and the distance (D2) between neighboring light sources (SL) can be set so that D1=D2, that is, they are equal to each other. The shortest distance between a neighboring pixel group (PG) and a photosensor (S) and the shortest distance between a neighboring pixel group (PG) and a light source (SL) can be set so that they are substantially the same. The distance (D0) between neighboring pixel groups can be greater than D1=D2.

[0046] Referring to FIG. 6, the second sensing area (CA) includes a pixel group (PG) spaced apart by a predetermined distance (D0) and light-emitting units (AG) spaced apart at equal intervals (L4) between adjacent pixel groups. External light is received by the lens of the camera module through the light-emitting units (AG). The pixel group (PG) may include one or two pixels. For example, one pixel within the pixel group may include R, G, and B subpixels, or two subpixels each composed of two subpixels may be arranged. The first pixel (PIX1) may be composed of R and G subpixels, and the second pixel (PIX2) may be composed of B and G subpixels. The light-emitting units (AG) may be composed solely of transparent media so that light can be incident on the camera module with minimal light loss. In other words, the light-emitting units (AG) may be made of transparent insulating materials without including metal wiring or pixels. The distance (D4) between neighboring light emitters (AG) in each of the four directions (X, Y, Θx and Θy) is the same. Also, the distance (D0) between neighboring pixel groups (PG) in each of the four directions (X, Y, Θx and Θy) is the same.

[0047] In fingerprint recognition mode, it is effective to use G subpixels and B subpixels as the light source for the first sensing service. Among R, G, and B subpixels, the G subpixel has the highest luminous efficiency. Therefore, the G subpixel can emit light at a brightness suitable for fingerprint sensing even at a low driving current. Meanwhile, since human skin transmits long-wavelength light, such as infrared and red light, well, using an R subpixel as the light source for fingerprint recognition mode causes long-wavelength light from sunlight passing through the finger or strong external light to significantly increase noise in the photosensor signal. In contrast, if green or blue light is used as the sensing light (effective light source) in fingerprint recognition mode, the finger blocks long-wavelength light, thereby reducing noise caused by external light in the photosensor. Therefore, as the light source for fingerprint recognition mode, a G subpixel or a cyan pixel composed of a combination of G and B subpixels is preferred.

[0048] FIG. 7 is a diagram showing the cross-sectional structure of an organic photodiode and a pixel according to one embodiment of the present invention.

[0049] Referring to FIG. 7, the photosensor (S) of the first sensing region (SA) can be implemented as an organic photodiode (OPD). The organic photodiode (OPD) can be implemented with a cross-sectional structure substantially identical to that of an OLED of RGB subpixels.

[0050] RGB subpixels can be implemented as a combination of a white OLED and a color filter, or as red, green, and blue OLEDs in which the dopants added to the host material of the emissive layer differ by color. Each of the RGB subpixel OLEDs includes an anode electrode (AND), a hole injection layer (HIL), a hole transport layer (HTL), an emissive layer (EML), an electron transport layer (ETL), an electron injection layer (EIL), and a cathode electrode (CAT) stacked on a pixel circuit (CPIX). The hole injection layer (HID) is in contact with the anode electrode (AND) of the RGB subpixels, and the electron injection layer (EIL) is in contact with the cathode electrode (CAT).

[0051] An organic photodiode (OPD) comprises an anode electrode (AND), a hole injection layer (HIL), a hole transport layer (HTL), an active layer (ACT-OPD), an electron transport layer (ETL), an electron injection layer (EIL), and a cathode electrode (CAT) stacked on a photosensor driving circuit (COPD). The active layer (ACT-OPD) of the organic photodiode comprises a known organic semiconductor material.

[0052] The active layer (ACT-OPD) of an organic photodiode (OPD) may be an organic semiconductor material that can be coated by a solution process, such as P3HT:PC61BM, Squaraine:PC61BM, C60, PBDTTT-C:PC71BM, PDPP3T:PC71BM, PCDTBT:PC61BM, PVK:PC71BM, PCDTBT:PC71BM, ZnO:F8T2, PBDT-TFTTE:PC71BM, P3HT:PC61BM, TAPC:C60, P3HT:PC60BM, PFBT2OBT:PC71BM, PIDT-TPD:PC61BM, P3HT:PC71BM, PV-D4650:PC61BM, P3HT:O-IDTBR, 2,9-dimethylquinacridone (2,9-DMQA), or a compound of one or more organic materials, but is not limited thereto. Organic semiconductor materials can be processed using solution processes at relatively lower temperatures compared to inorganic semiconductor materials formed through high-temperature deposition processes, which can reduce manufacturing costs and enable their application in flexible displays.

[0053] As can be seen in FIG. 7, the organic photodiode (OPD) has substantially the same cross-sectional structure as the RGB subpixels, and most of its layers can be formed from the same material as the RGB subpixels. Therefore, OLEDs of organic photodiodes (OPDs) and RGB subpixels can be formed in the same manufacturing process, and since they have the same cross-sectional structure, most circuit components can be shared, which can simplify the structure of the display panel.

[0054] FIG. 8 is a diagram showing the cross-sectional structure of an inorganic photodiode and a pixel according to one embodiment of the present invention. In FIG. 8, the electron injection layer (EIL) and the hole injection layer (HIL) are omitted.

[0055] Referring to FIG. 8, the photosensor of the first sensing area (SA) can be implemented as an inorganic photodiode (PD).

[0056] The active layer (PIN) of the inorganic photodiode (PD) has a PIN junction structure in which an undoped semiconductor layer exists between the ion-doped P region and the N region. Amorphous silicon (a-Si) can be used as the semiconductor material for the inorganic photodiode (PD). Since the P region has a high light absorption rate, the photoelectric conversion efficiency of the inorganic photodiode (PD) is high when the P region is located on the incident side of the light. RGB subpixels can be implemented as front-emitting type OLEDs through which light passes via a cathode electrode, which is a semi-transparent electrode. In this case, the electrodes of the RGB subpixels of the inorganic photodiode (PD) can be reversed. For example, a metal layer in contact with the circuit layer can be patterned as the anode electrode (AND) of the RGB subpixels, and a portion of it can be patterned as the cathode electrode (CATPD) of the inorganic photodiode (PD). The cathode electrode (CAT) of the RGB subpixels and the anode electrode (ANDPD) of the inorganic photodiode (PD) are electrically isolated. In this case, an insulating layer (INS) and an electron transport layer (ETL) may be placed between the cathode electrodes (CAT) of the RGB subpixels and the anode electrodes (ANDPD) of the inorganic photodiode (PD).

[0057] The cathode electrode of an inorganic photodiode (OPD) can be connected to a photosensor driving circuit (CPD). The cathode electrode (CATPD) of the inorganic photodiode (PD) can be formed on the same layer as the anode electrode (AND) of the RGB subpixels, but the two are electrically isolated. The cathode electrode (CATPD) of the inorganic photodiode (PD) can be formed on the same layer as the hole transport layer (HTL) of the RGB subpixels, but the two are electrically isolated. In the active layer (PIN) of the inorganic photodiode (PD), the P region can be in contact with the anode electrode (ANDPD), and the N region can be in contact with the cathode electrode (CATPD).

[0058] The inorganic photodiode (PD) is completely electrically isolated from the light-emitting elements (OLEDs) of the pixels. The anode electrode (ANDPD) of the inorganic photodiode (PD) must be electrically and reliably isolated from the organic compound layer and cathode electrode (CAT) of the adjacent light-emitting element (OLED) by an insulating layer (INS). Additionally, the cathode electrode (CATPD) of the inorganic photodiode (PD) must also be electrically and reliably isolated from the organic compound layer and anode electrode (AND) of the adjacent light-emitting element (OLED).

[0059] FIG. 9 is a diagram showing in more detail the arrangement of a light source for fingerprint sensing in the first sensing area (SA) illustrated in FIG. 5.

[0060] Referring to FIG. 9, the light source for fingerprint sensing in the first sensing area (SA) can be implemented as a G subpixel having substantially the same structure as the G subpixel of the pixel group (PG). The G subpixel used as the light source for fingerprint sensing is connected to a data driver (306) via a data line, just like the subpixels for display driving. Accordingly, the light source for fingerprint sensing can emit light according to the light source driving voltage supplied from the data driver (306).

[0061] A light source for fingerprint sensing emits light only in fingerprint recognition mode and does not emit light in display mode. At least one of the subpixels of a pixel group (PG) may be used as a light source for fingerprint sensing by emitting light in fingerprint recognition mode as needed, for example, depending on the user's fingerprint state and external environment.

[0062] Each pixel group (PG) may contain one R subpixel, one B subpixel, and two G subpixels. Within a pixel group, subpixels may be arranged in a diamond shape or a cross shape. Neighboring pixel groups (PG) may be arranged in a diamond shape as indicated by the dotted lines, and may also be arranged in a zigzag shape. One or more photosensors (S) and one or more light sources (SL) are placed between neighboring pixel groups (PG) in each of the four directions (X, Y, Θx, and Θy).

[0063] Two or more photosensors are placed between adjacent pixel groups (PG) in the horizontal direction (X), and two or more photosensors are also placed between adjacent pixel groups (PG) in the vertical direction.

[0064] A light source for fingerprint sensing can be positioned adjacent to each of the photosensors (S). The light source for fingerprint sensing can be divided into a first light source group (SLG1) positioned above the pixel group (PG) in the vertical direction (Y), a second light source group (SLG2) positioned below the pixel group (PG) in the vertical direction (Y), third and fourth light source groups (SLG3, SGL4) positioned to the left of the pixel group (PG) in the horizontal direction (X), and fifth and sixth light source groups (SLG5, SGL6) positioned to the right of the pixel group (PG) in the horizontal direction (X). Each of the light source groups (SLG1 to SLG6) may include two or more photosensors (S).

[0065] A row of photosensors (S) arranged in a line is placed between the first light source group (SLG1) and the pixel group (PG) below it. A row of photosensors (S) arranged in a line is placed between the second light source group (SLG1) and the pixel group (PG) above it. For example, in the first sensing area (SA), the 4k (k is a natural number)-1st pixel line (L3, L7, L11) may have photosensors (S) arranged in a line without subpixels (RGB) of the light source (SL) and the pixel group (PG).

[0066] One or more photosensors (S) may be placed between the third light source group (SLG3) and the fourth light source group (SLG4). One or more photosensors (S) may be placed between the third light source group (SL3) and the pixel group above it, and one or more photosensors (S) may be placed between the fourth light source group (SLG4) and the pixel group below it. One or more photosensors (S) may be placed between the fifth light source group (SLG5) and the sixth light source group (SLG6). One or more photosensors (S) may be placed between the fifth light source group (SLG5) and the pixel group (PG) above it, and one or more photosensors (S) may be placed between the sixth light source group (SLG6) and the pixel group below it.

[0067] If a virtual line passing through the center of each of the first to sixth light source groups (SLG1 to SLG6) adjacent to the pixel group (PG) is connected, these light source groups (SLG1 to SLG6) can be arranged in a hexagonal shape centered around one pixel group (PG).

[0068] FIGS. 10a to 10d are drawings showing the operation of the first sensing area illustrated in FIG. 9.

[0069] Referring to FIG. 10a, the pixels of the first sensing area (SA) may be in a non-driving state during a non-driving frame period in a power-off state, standby mode, or low-speed driving state. In the non-driving state, the pixels do not emit light. In order to reduce power consumption in the non-driving state, the photosensors (S) may not be driven.

[0070] Referring to FIG. 10b, the pixels of the first sensing area (SA) can charge the data voltage of the pixel data in display mode and emit light with brightness according to the grayscale value of the pixel data. Accordingly, the first sensing area (SA) can display an input image in display mode.

[0071] In the first sensing area (SA), one or more subpixels in each pixel group (PG) and a sensing light source (SL) may be illuminated in fingerprint recognition mode. For example, in fingerprint sensing mode, only the sensing light source (SL) may be illuminated, or, as shown in FIGS. 10c and 10d, the G subpixel or the G and B subpixels in the pixel group (PG) may be illuminated together with the sensing light source (SL). In fingerprint recognition mode, light-emitting elements (OLEDs) emit light from the subpixels that emit light.

[0072] FIGS. 10c and FIGS. 10d are drawings showing examples of subpixels that light up in fingerprint recognition mode.

[0073] As illustrated in FIG. 10c, all subpixels (RGB) of the first sensing area (SA), including subpixels (G) used as a light source (SL) for sensing, can be illuminated in fingerprint recognition mode. As another example, as illustrated in FIG. 10d, all G and B subpixels (GB) of the first sensing area (SA), including subpixels (G) used as a light source (SL) for sensing, can be illuminated in fingerprint recognition mode.

[0074] FIG. 11 is a drawing showing a pixel, a photosensor, and a light source of a first sensing area according to another embodiment of the present invention.

[0075] Referring to FIG. 11, the light source for fingerprint sensing in the first sensing area (SA) can be implemented as a G subpixel having substantially the same structure as the G subpixel of the pixel group (PG).

[0076] A light source for fingerprint sensing emits light only in fingerprint recognition mode and does not emit light in display mode. At least one of the subpixels of a pixel group (PG) may be used as a light source for fingerprint sensing by emitting light in fingerprint recognition mode as needed, for example, depending on the user's fingerprint state and external environment.

[0077] Each pixel group (PG) may contain one R subpixel, one B subpixel, and two G subpixels. Within a pixel group, subpixels may be arranged in a zigzag or parallelogram shape. Neighboring pixel groups (PG) may be arranged in a diamond shape as indicated by the dotted lines, and may also be arranged in a zigzag shape. One or more photosensors (S) and one or more light sources (SL) are placed between neighboring pixel groups (PG) in each of the four directions (X, Y, Θx, and Θy).

[0078] Two or more photosensors are placed between adjacent pixel groups (PG) in the horizontal direction (X), and two or more photosensors are also placed between adjacent pixel groups (PG) in the vertical direction.

[0079] A light source for fingerprint sensing can be positioned adjacent to each of the photosensors (S). The light source for fingerprint sensing can be divided into a first light source group (SLG21) positioned above the pixel group (PG) in the vertical direction (Y), a second light source group (SLG22) positioned below the pixel group (PG) in the vertical direction (Y), a third light source group (SLG23) positioned to the left of the pixel group (PG) in the horizontal direction (X), and a fourth light source group (SLG24) positioned to the right of the pixel group (PG) in the horizontal direction (X). Each of the light source groups (SLG21 to SLG24) may include two or more photosensors (S).

[0080] Each of the first and second light source groups (SLG21, SLG22) may include a row of light sources in which the sensing light sources (SL) are arranged in a row along the horizontal direction (X). For example, in the first sensing area (SA), the 4k-th (k is a natural number) pixel line (L4, L8, L12) may have the sensing light sources (SL) arranged in a row without the light sources (SL) and the subpixels (RGB) of the pixel group (PG).

[0081] A row of photosensors (S) arranged in a line along the horizontal direction (X) is placed above each of the first and second light source groups (SLG21, SLG22). For example, in the first sensing area (SA), the 4k (k is a natural number)-1st pixel line (L3, L7, L11) may have photosensors (S) arranged in a line without the light source (SL) for sensing and the subpixels (RGB) of the pixel group (PG).

[0082] One or more photosensors (S) may be placed between the first light source group (SLG21) and the third light source group (SL23). One or more photosensors (S) may be placed between the second light source group (SLG22) and the third light source group (SL23). One or more photosensors (S) may be placed between the first light source group (SLG21) and the fourth light source group (SL24). One or more photosensors (S) may be placed between the second light source group (SLG22) and the fourth light source group (SL24).

[0083] In the first sensing area (SA) illustrated in FIG. 11, only the sensing light source (SL) may be illuminated in fingerprint recognition mode as described above, or the G subpixel or the G and B subpixels in the pixel group (PG) may be illuminated together with the sensing light source (SL) as in FIG. 10c and FIG. 10d.

[0084] FIGS. 12 and FIGS. 13 are drawings showing a pixel, a photosensor, and a light source of a first sensing area according to another embodiment of the present invention.

[0085] Referring to FIGS. 12 and 13, the resolution of the fingerprint recognition sensor can be increased by increasing the spacing between pixel groups (PG) in the first sensing area (SA) and placing more photosensors between them. As the PPI of the first sensing area (SA) decreases, the present invention requires more sensing light sources (SL) to secure the minimum luminous brightness for fingerprint recognition; therefore, the lower the PPI, the more subpixels used as sensing light sources are placed in the first sensing area (SA). Here, to increase the accuracy of fingerprint recognition, it is preferable that the sensing light sources (SL) and photosensors (S) used as sensing light sources (SL) and photosensors are placed at equal intervals and uniformly throughout the first sensing area (SA), as shown in FIGS. 9 to 13.

[0086] The clarity of the fingerprint pattern image obtained from the photosensors (S) may vary depending on the fingerprint condition and surrounding environment. If the clarity of the fingerprint pattern image is low, the fingerprint recognition rate is low. The clarity of the fingerprint pattern image can be determined by the ridge-valley contrast of the fingerprint in the fingerprint pattern image. In order to obtain an optimal fingerprint pattern image in various fingerprint conditions and external environments, the present invention obtains multiple fingerprint pattern images by changing the number of light sources illuminated in the fingerprint recognition mode as shown in FIG. 14, and performs fingerprint authentication based on the fingerprint pattern image with the highest clarity among them.

[0087] FIG. 14 is a flowchart showing an example of a fingerprint authentication method that selects a high-clarity fingerprint pattern image while changing the number of light sources illuminated in the fingerprint recognition mode.

[0088] Referring to FIG. 14, when the fingerprint recognition mode starts and the user's finger is sensed in the first sensing area (SA), the fingerprint recognition processor lights up the light sources of the first sensing area (SA) (S11). After the light sources are lit up, the photosensors (S) are activated to sense the user's fingerprint (S12). The fingerprint recognition processor converts the output of the photosensors (S) into digital data to generate fingerprint pattern image data and stores it in memory (S13).

[0089] Next, the fingerprint recognition processor controls the brightness of the sensing light source by changing the number of illuminated light sources (S14). At this time, the on / off of the illuminated light sources can be controlled by increasing or decreasing the number of illuminated light sources, increasing the number of illuminated light sources and then decreasing, or conversely. Whenever the number of illuminated light sources changes, the photosensors (S) are activated to sense the user's fingerprint (S15). The fingerprint recognition processor converts the output of the photosensors (S) into digital data to generate fingerprint pattern image data and stores it in memory (S16). Fingerprint sensing can be repeated as the number of illuminated light sources changes for a preset number of repetitions.

[0090] The fingerprint recognition processor can compare the clarity of fingerprint pattern images stored in memory, select the fingerprint pattern image with the highest clarity, and transmit it to the host system (S17 and S18). The host system can perform fingerprint authentication by comparing the fingerprint pattern image received through the fingerprint recognition processor with user fingerprint data stored in advance (S19).

[0091] FIG. 15 is a block diagram showing a display panel and a display panel driving unit according to an embodiment of the present invention. FIG. 16 is a block diagram schematically showing the configuration of a drive IC.

[0092] Referring to FIGS. 15 and 16, the display device includes a display panel (100) on which a pixel array is arranged on a screen, and a display panel driving unit, etc.

[0093] The pixel array of the display panel (100) includes data lines (DL), gate lines (GL) intersecting the data lines (DL), and pixels (P) arranged in a matrix form defined by the data lines (DL) and the gate lines (GL). The pixel array further includes power lines such as the VDD line (PL1), Vini line (PL2), and VSS line (PL3) shown in FIG. 17.

[0094] As shown in FIG. 1, the pixel array may be divided into a circuit layer (12) and a light-emitting element layer (18). A touch sensor array may be placed on the light-emitting element layer (18). Each pixel of the pixel array may include two to four subpixels as described above. Each subpixel includes a pixel circuit placed on the circuit layer (12).

[0095] The screen on which the input image is reproduced in the display panel (100) includes a display area (DA), a first sensing area (SA), and a second sensing area (CA).

[0096] Each subpixel of the display area (DA), the first sensing area (SA), and the second sensing area (CA) includes a pixel circuit. The pixel circuit may include a driving element that supplies current to a light-emitting element (OLED), a plurality of switching elements that sample the threshold voltage of the driving element and switch the current path of the pixel circuit, a capacitor that maintains the gate voltage of the driving element, etc. The pixel circuit is positioned below the light-emitting element.

[0097] A first sensing area (SA) of a display panel (100) includes photosensors for fingerprint sensing between groups of pixels, a photosensor driving circuit for driving the photosensors, and light sources for sensing. The photosensors and light sources for sensing can be uniformly spaced at equal intervals within the first sensing area (SA). The photosensor driving circuit is positioned below the photosensors.

[0098] The second sensing area (CA) includes light emitters disposed between pixel groups and a camera module (400) disposed below the second sensing area (CA). In imaging mode, the camera module (400) converts light incident through the second sensing area (CA) into photoelectric power using an image sensor, and converts pixel data of an image output from the image sensor into digital data to output the captured image data.

[0099] The display panel driver writes pixel data of the input image to the pixels (P). The pixels (P) can be interpreted as a pixel group including multiple subpixels.

[0100] The display panel driver includes a data driver (306) that supplies a data voltage of pixel data to data lines (DL) and a gate driver (120) that sequentially supplies a gate pulse to gate lines (GL). The data driver (306) may be integrated into a drive IC (300). The display panel driver may further include a touch sensor driver that is omitted from the drawing.

[0101] The drive IC (300) can be attached to the display panel (100). The drive IC (300) receives pixel data and timing signals of an input image from the host system (200), supplies the data voltage of the pixel data to the pixels, and synchronizes the data driver (306) and the gate driver (120).

[0102] The drive IC (300) is connected to the data lines (DL) through data output channels and supplies the data voltage of the pixel data to the data lines (DL). The drive IC (300) can output a gate timing signal to control the gate driver (120) through gate timing signal output channels. The gate timing signal generated from the timing controller (303) may include a gate start pulse (VST), a gate shift clock (CLK), etc. The gate start pulse (VST) and the gate shift clock (CLK) swing between the gate on voltage (VGL) and the gate off voltage (VGH). The gate timing signals (VST, CLK) output from the level shifter (307) are applied to the gate driver (120) to control the shift operation of the gate driver (120).

[0103] The gate driver (120) may include a shift register formed in the circuit layer of the display panel (100) together with the pixel array. The shift register of the gate driver (120) sequentially supplies gate signals to gate lines (GL) under the control of the timing controller (30). The gate signals may include a scan pulse and an EM pulse of the light emission signal. The shift register may include a scan driver that outputs a scan pulse and an EM driver that outputs an EM pulse. In FIG. 16, GVST and GCLK are gate timing signals input to the scan driver. EVST and ECLK are gate timing signals input to the EM driver.

[0104] The drive IC (300) can be connected to a host system (200), a first memory (301), and a display panel (100). The drive IC (300) may include a data receiving and processing unit (308), a timing controller (303), a data driving unit (306), a gamma compensation voltage generating unit (305), a power supply unit (304), a second memory (302), etc.

[0105] The data reception and processing unit (308) includes a receiving unit that receives pixel data input as a digital signal from the host system (200) and a data processing unit that processes the pixel data input through the receiving unit to improve image quality. The data processing unit may include a data recovery unit that decodes and restores compressed pixel data, and an optical compensation unit that adds a preset optical compensation value to the pixel data. The optical compensation value may be set as a value for correcting the brightness of each pixel data based on the brightness of the screen measured based on a camera image captured during the manufacturing process.

[0106] The timing controller (303) provides pixel data of an input image received from the host system (200) to the data driver (306). The timing controller (303) generates a gate timing signal for controlling the gate driver (120) and a source timing signal for controlling the data driver (306) to control the operation timing of the gate driver (120) and the data driver (306).

[0107] The data driver (306) converts digital data, including pixel data received from the timing controller (303) through a digital-to-analog converter (DAC), into a gamma compensation voltage and outputs a data voltage. The data voltage output from the data driver (306) is supplied to the data lines (DL) of the pixel array through an output buffer connected to the data channel of the drive IC (300).

[0108] The gamma compensation voltage generator (305) generates a gamma compensation voltage for each grayscale by dividing the gamma reference voltage from the power supply unit (304) through a voltage divider circuit. The gamma compensation voltage is an analog voltage with a voltage set for each grayscale of the pixel data. The gamma compensation voltage output from the gamma compensation voltage generator (305) is provided to the data driving unit (306).

[0109] The power supply unit (304) generates power required to drive the pixel array of the display panel (100), the gate driver (120), and the drive IC (300) using a DC-DC converter. The DC-DC converter may include a charge pump, a regulator, a buck converter, a boost converter, etc. The power supply unit (304) can generate DC power such as a gamma reference voltage, a gate-on voltage (VGL), a gate-off voltage (VGH), a pixel driving voltage (VDD), a low-potential power supply voltage (VSS), and an initialization voltage (Vini) by adjusting the DC input voltage from the host system (200). The gamma reference voltage is supplied to the gamma compensation voltage generator (305). The gate-on voltage (VGL) and the gate-off voltage (VGH) are supplied to the level shifter (307) and the gate driver (120). Pixel power supplies, such as the pixel driving voltage (VDD), low potential power supply voltage (VSS), and initialization voltage (Vini), are supplied in common to the pixels (P). The initialization voltage (Vini) is set to a DC voltage that is lower than the pixel driving voltage (VDD) and lower than the threshold voltage of the light-emitting element (OLED), thereby initializing the main nodes of the pixel circuits and suppressing the light emission of the light-emitting element (OLED).

[0110] The second memory (302) stores compensation values, register setting data, etc. received from the first memory (301) when power is input to the drive IC (300). The compensation values ​​can be applied to various algorithms that improve image quality. The compensation values ​​may include optical compensation values. The register setting data defines the operation of the data driving unit (306), the timing controller (303), the gamma compensation voltage generator (305), etc. The first memory (301) may include a flash memory. The second memory (302) may include a static RAM.

[0111] The host system (200) can be implemented as an Application Processor (AP). The host system (200) can transmit pixel data of an input image to a drive IC (300) via a Mobile Industry Processor Interface (MIPI). The host system (200) can be connected to the drive IC (300) via a flexible printed circuit, for example, a Flexible Printed Circuit (FPC).

[0112] The present invention further includes a fingerprint recognition processor. The fingerprint recognition processor (500) is connected to photosensors (S) of a first sensing area (SA). The fingerprint recognition processor (500) amplifies the output voltage of the photosensors (S) and then converts it using an analog-to-digital converter (ADC) to generate fingerprint pattern image data. A host system (200) receives the fingerprint pattern image data from the fingerprint recognition processor (500) and processes fingerprint authentication.

[0113] Meanwhile, the display panel (600) can be implemented as a flexible panel applicable to a flexible display. The flexible display can vary the screen size by rolling, folding, or bending the flexible panel, and can be easily manufactured in various designs. The flexible display can be implemented as a rollable display, a foldable display, a bendable display, a sliderable display, etc. The flexible panel can be manufactured as a so-called "plastic OLED panel." The plastic OLED panel may include a back plate and a pixel array on an organic thin film attached to the back plate. A touch sensor array may be formed on the pixel array.

[0114] The back plate may be a PET (Polyethylene terephthalate) substrate. A pixel array and a touch sensor array may be formed on an organic thin film. The back plate may block moisture penetration toward the organic thin film so that the pixel array is not exposed to humidity. The organic thin film may be a PI (Polyimide) film substrate. A multilayer buffer film made of an insulating material not shown may be formed on the organic thin film. A circuit layer (12) and a light-emitting element layer (14) may be laminated on the organic thin film.

[0115] In the display device of the present invention, the pixel circuit, the photosensor driving circuit, and the gate driving unit disposed in the circuit layer (12) may include a plurality of transistors. The transistors may be implemented as an Oxide TFT (Thin Film Transistor) including an oxide semiconductor, an LTPS TFT including a Low Temperature Poly Silicon (LTPS), etc. Each of the transistors may be implemented as a p-channel TFT or an n-channel TFT. Although the embodiment is described with reference to an example in which the transistors of the pixel circuit are implemented as p-channel TFTs, the present invention is not limited thereto.

[0116] A transistor is a three-electrode device comprising a gate, a source, and a drain. The source is the electrode that supplies carriers to the transistor. Within the transistor, carriers begin to flow from the source. The drain is the electrode from which carriers exit the transistor. In a transistor, the flow of carriers is from the source to the drain. In the case of an n-channel transistor, since the carriers are electrons, the source voltage is lower than the drain voltage to allow electrons to flow from the source to the drain. In an n-channel transistor, the direction of current flows from the drain toward the source. In the case of a p-channel transistor (PMOS), since the carriers are holes, the source voltage is higher than the drain voltage to allow holes to flow from the source toward the drain. In a p-channel transistor, current flows from the source toward the drain because holes flow from the source toward the drain. It should be noted that the source and drain of a transistor are not fixed. For example, the source and drain can change depending on the applied voltage. Therefore, the invention is not limited by the source and drain of the transistor. In the following description, the source and drain of the transistor will be referred to as the first and second electrodes.

[0117] The gate pulse swings between the gate-on voltage and the gate-off voltage. The gate-on voltage is set to a voltage higher than the transistor's threshold voltage, and the gate-off voltage is set to a voltage lower than the transistor's threshold voltage. The transistor turns on in response to the gate-on voltage, while it turns off in response to the gate-off voltage. In the case of an n-channel transistor, the gate-on voltage can be the gate-high voltage (VGH), and the gate-off voltage can be the gate-low voltage (VGL). In the case of a p-channel transistor, the gate-on voltage can be the gate-low voltage (VGL), and the gate-off voltage can be the gate-high voltage (VGH).

[0118] The driving element of the pixel circuit can be implemented as a transistor. Although the electrical characteristics of the driving element must be uniform among all pixels, differences may exist between pixels due to process variations and variations in device characteristics, and these characteristics may change over time. To compensate for such variations in the electrical characteristics of the driving element, the display device may include an internal compensation circuit and an external compensation circuit. The internal compensation circuit is added to the pixel circuit at each subpixel to sample the threshold voltage (Vth) and / or mobility (μ) of the driving element, which vary according to the electrical characteristics of the driving element, and compensates for these changes in real time. The external compensation circuit transmits the sensed threshold voltage and / or mobility of the driving element to an external compensation unit via a sensing line connected to each subpixel. The compensation unit of the external compensation circuit compensates for changes in the electrical characteristics of the driving element by modulating the pixel data of the input image, reflecting the sensing results. The voltage of the pixel, which varies according to the electrical characteristics of the external compensation driving element, is sensed, and the external circuit modulates the data of the input image based on the sensed voltage to compensate for variations in the electrical characteristics of the driving element between pixels.

[0119] FIGS. 17 and 18 are circuit diagrams showing an example of a pixel circuit with an internal compensation circuit applied. FIG. 19 is a diagram showing a method of driving the pixel circuit illustrated in FIGS. 17 and 18. It should be noted that the pixel circuit of the present invention is not limited to FIGS. 17 through 19. The pixel circuit illustrated in FIGS. 17 and 18 can be equally applied to pixel circuits of a display area (DA), a first sensing area (SA), and a second sensing area (CA). A pixel circuit applicable to the present invention may be implemented as the circuit illustrated in FIGS. 17 and 18, but is not limited thereto.

[0120] Referring to FIGS. 17 to 19, the pixel circuit includes a light-emitting element (OLED), a driving element (DT) that supplies current to the light-emitting element (OLED), and an internal compensation circuit that samples the threshold voltage (Vth) of the driving element (DT) using a plurality of switching elements (M1 to M6) and compensates the gate voltage of the driving element (DT) by the threshold voltage (Vth) of the driving element (DT). Each of the driving element (DT) and the switching elements (M1 to M6) can be implemented as a p-channel TFT.

[0121] The driving period of the pixel circuit using an internal compensation circuit can be divided into an initialization period (Tini), a sampling period (Tsam), a data writing period (Twr), and a light emission period (Tem), as shown in FIG. 19.

[0122] During the initialization period (Tini), as shown in FIG. 19, the N-1 scan signal [SCAN(N-1)] is generated as a pulse of the gate-on voltage (VGL), and the voltages of the N-1 scan signal [SCAN(N)] and the light emission signal [EM(N)] are each the gate-off voltage (VGH). During the sampling period (Tsam), the N-1 scan signal [SCAN(N)] is generated as a pulse of the gate-on voltage (VGL), and the voltages of the N-1 scan signal [SCAN(N-1)] and the light emission signal [EM(N)] are each the gate-off voltage (VGH). During the data writing period (Twr), the voltages of the N-1 scan signal [SCAN(N-1)], the N-1 scan signal [SCAN(N)], and the light emission signal [EM(N)] are each the gate-off voltage (VGH). During at least a portion of the emission period (Tem), the emission signal [EM(N)] is generated as the gate-on voltage (VGL), and the voltages of the N-1 scan signal [SCAN(N-1)] and the N-th scan signal [SCAN(N)] are generated as the gate-off voltage (VGH).

[0123] During the initialization period (Tin), the fifth switch element (M5) is turned on according to the gate-on voltage (VGL) of the N-1 scan signal [SCAN(N-1)] to initialize the pixel circuit. During the sampling period (Tsam), the first and second switch elements (M1, M2) are turned on according to the gate-on voltage (VGL) of the N scan signal [SCAN(N)] so that the threshold voltage of the driving element (DT) is sampled and stored in the capacitor (Cst1). At the same time, the sixth switch element (M6) is turned on during the sampling period (Tsam) to lower the voltage of the fourth node (n4) to the reference voltage (Vref) to suppress the light emission of the light-emitting element (OLED). During the data writing period (Twr), the first to sixth switch elements (M1~M6) remain in an off state. During the light emission period (Tem), the third and fourth switch elements (M1, M2) are turned on so that the light-emitting element (OLED) emits light. In order to precisely express the low-gradation brightness as the duty ratio of the light emission signal [EM(N)] during the light emission period (Tem), the light emission signal [EM(N)] swings at a predetermined duty ratio between the gate-on low voltage (VGL) and the gate-off voltage (VGH), so that the third and fourth switch elements (M1, M2) can repeatedly turn on and off.

[0124] A light-emitting device (OLED) can be implemented using an organic light-emitting diode or an inorganic light-emitting diode. Below, we will describe an example in which a light-emitting device (OLED) is implemented using an organic light-emitting diode.

[0125] A light-emitting device (OLED) may include an organic compound layer formed between an anode and a cathode. The organic compound layer may include, but is not limited to, a hole injection layer (HIL), a hole transport layer (HTL), an emitting layer (EML), an electron transport layer (ETL), and an electron injection layer (EIL). When voltage is applied to the anode and cathode of the OLED, holes passing through the hole transport layer (HTL) and electrons passing through the electron transport layer (ETL) move to the emitting layer (EML), whereby excitons are formed, and visible light is emitted from the emitting layer (EML).

[0126] The anode of the light-emitting element (OLED) is connected to a fourth node (n4) between the fourth and sixth switch elements (M4, M6). The fourth node (n4) is connected to the anode of the light-emitting element (OLED), the second electrode of the fourth switch element (M4), and the second electrode of the sixth switch element (M6). The cathode of the light-emitting element (OLED) is connected to a VSS line (PL3) to which a low potential power supply voltage (VSS) is applied. The light-emitting element (OLED) emits light with a current (Ids) flowing according to the gate-source voltage (Vgs) of the driving element (DT). The current path of the light-emitting element (OLED) is switched by the third and fourth switch elements (M3, M4).

[0127] The storage capacitor (Cst1) is connected between the VDD line (PL1) and the first node (n1). The data voltage (Vdata), compensated by the threshold voltage (Vth) of the driving element (DT), is charged into the storage capacitor (Cst1). Since the data voltage (Vdata) at each subpixel is compensated by the threshold voltage (Vth) of the driving element (DT), the characteristic deviation of the driving element (DT) at the subpixels is compensated.

[0128] The first switch element (M1) is turned on in response to the gate-on voltage (VGL) of the Nth scan pulse [SCAN(N)] to connect the second node (n2) and the third node (n3). The second node (n2) is connected to the gate electrode of the driving element (DT), the first electrode of the storage capacitor (Cst1), and the first electrode of the first switch element (M1). The third node (n3) is connected to the second electrode of the driving element (DT), the second electrode of the first switch element (M1), and the first electrode of the fourth switch element (M4). The gate electrode of the first switch element (M1) is connected to the first gate line (GL1) to receive the Nth scan pulse [SCAN(N)]. The first electrode of the first switch element (M1) is connected to the second node (n2), and the second electrode of the first switch element (M1) is connected to the third node (n3).

[0129] Leakage current may occur in the off state of the first switch element (M1) because the first switch element (M1) is turned on only for a very short horizontal period (1H) during which the Nth scan signal [SCAN(N)] is generated at the gate-on voltage (VGL) during the frame period, and thus remains off for approximately the frame period. To suppress the leakage current of the first switch element (M1), the first switch element (M1) may be implemented as a dual-gate structure transistor in which two transistors (M1a, M1b) are connected in series, as shown in FIG. 18.

[0130] The second switch element (M2) is turned on in response to the gate-on voltage (VGL) of the Nth scan pulse [SCAN(N)] to supply a data voltage (Vdata) to the first node (n1). The gate electrode of the second switch element (M2) is connected to the first gate line (GL1) to receive the Nth scan pulse [SCAN(N)]. The first electrode of the second switch element (M2) is connected to the first node (n1). The second electrode of the second switch element (M2) is connected to the data line (DL) to which the data voltage (Vdata) is applied. The first node (n1) is connected to the first electrode of the second switch element (M2), the second electrode of the third switch element (M2), and the first electrode of the driving element (DT).

[0131] The third switch element (M3) is turned on in response to the gate-on voltage (VGL) of the light emission signal [EM(N)] and connects the VDD line (PL1) to the first node (n1). The gate electrode of the third switch element (M3) is connected to the third gate line (GL3) to receive the light emission signal [EM(N)]. The first electrode of the third switch element (M3) is connected to the VDD line (PL1). The second electrode of the third switch element (M3) is connected to the first node (n1).

[0132] The fourth switch element (M4) is turned on in response to the gate-on voltage (VGL) of the light emission signal [EM(N)] to connect the third node (n3) to the anode of the light emission element (OLED). The gate electrode of the fourth switch element (M4) is connected to the third gate line (GL3) to receive the light emission signal [EM(N)]. The first electrode of the fourth switch element (M4) is connected to the third node (n3), and the second electrode is connected to the fourth node (n4).

[0133] The fifth switch element (M5) is turned on in response to the gate-on voltage (VGL) of the N-1 scan pulse [SCAN(N-1)] to connect the second node (n2) to the Vini line (PL2). The gate electrode of the fifth switch element (M5) is connected to the second gate line (GL2) to receive the N-1 scan pulse [SCAN(N-1)]. The first electrode of the fifth switch element (M5) is connected to the second node (n2), and the second electrode is connected to the Vini line (PL2). To suppress leakage current of the fifth switch element (M5), the fifth switch element (M5) can be implemented as a dual-gate structure transistor in which two transistors (M5a, M5b) are connected in series, as shown in FIG. 18.

[0134] The sixth switch element (M6) is turned on in response to the gate-on voltage (VGL) of the Nth scan pulse [SCAN(N)] to connect the Vini line (PL2) to the fourth node (n4). The gate electrode of the sixth switch element (M6) is connected to the first gate line (GL1) to receive the Nth scan pulse [SCAN(N)]. The first electrode of the sixth switch element (M6) is connected to the Vini line (PL2), and the second electrode is connected to the fourth node (n4).

[0135] The driving element (DT) drives the light-emitting element (OLED) by controlling the current (Ids) flowing through the light-emitting element (OLED) according to the gate-source voltage (Vgs). The driving element (DT) includes a gate connected to a second node (n2), a first electrode connected to a first node (n1), and a second electrode connected to a third node (n3).

[0136] During the initialization period (Tini), the N-1st scan pulse [SCAN(N-1)] is generated at the gate-on voltage (VGL). The Nth scan pulse [SCAN(N)] and the light emission signal [EM(N)] maintain the gate-off voltage (VGH) during the initialization period (Tini). Thus, during the initialization period (Tini), the fifth switch element (M5) is turned on, and the second and fourth nodes (n2, n4) are initialized to Vini. A hold period (Th) may be set between the initialization period (Tini) and the sampling period (Tsam). During the hold period (Th), the gate pulses [SCAN(N-1), SCAN(N), EM(N)] maintain the previous state.

[0137] During the sampling period (Tsam), the Nth scan pulse [SCAN(N)] is generated at the gate-on voltage (VGL). The pulse of the Nth scan pulse [SCAN(N)] is synchronized with the data voltage (Vdata) of the Nth pixel line. The N-1st scan pulse [SCAN(N-1)] and the light emission signal [EM(N)] maintain the gate-off voltage (VGH) during the sampling period (Tsam). Thus, the first and second switch elements (M1, M2) are turned on during the sampling period (Tsam).

[0138] During the sampling period (Tsam), the gate voltage (DTG) of the driving element (DT) is raised by the current flowing through the first and second switch elements (M1, M2). When the driving element (DT) is turned off, the gate node voltage (DTG) is Vdata - |Vth|. At this time, the voltage of the first node (n) is also Vdata - |Vth|. During the sampling period (Tsam), the gate-source voltage (Vgs) of the driving element (DT) is |Vgs| = Vdata - (Vdata - |Vth|) = |Vth|.

[0139] During the data write period (Twr), the Nth scan pulse [SCAN(N)] is inverted to the gate off voltage (VGH). The N-1st scan pulse [SCAN(N-1)] and the light emission signal [EM(N)] maintain the gate off voltage (VGH) during the data write period (Twr). Therefore, all switch elements (M1~M6) remain in the off state during the data write period (Twr).

[0140] During the emission period (Tem), the emission signal [EM(N)] may be generated at the gate-on voltage (VGL). During the emission period (Tem), to improve low-gradation expression, the emission signal [EM(N)] may be switched on / off with a predetermined duty cycle and swing between the gate-on voltage (VGL) and the gate-off voltage (VGH). Accordingly, the emission signal [EM(N)] may be generated at the gate-on voltage (VGL) for at least a portion of the emission period (Tem).

[0141] When the light emission signal [EM(N)] is the gate-on voltage (VGL), current flows between VDD and the light-emitting element (OLED), allowing the light-emitting element (OLED) to emit light. During the light emission period (Tem), the N-1st and Nth scan pulses [SCAN(N-1), SCAN(N)] maintain the gate-off voltage (VGH). During the light emission period (Tem), the third and fourth switch elements (M3, M4) repeatedly turn on and off according to the voltage of the light emission signal (EM). When the light emission signal [EM(N)] is the gate-on voltage (VGL), the third and fourth switch elements (M3, M4) turn on, and current flows to the light-emitting element (OLED). At this time, Vgs of the driving element (DT) is |Vgs| = VDD - (Vdata - |Vth|), and the current flowing to the light-emitting element (OLED) is K(VDD - Vdata). 2 K is a constant value determined by the charge mobility, parasitic capacitance, and channel capacitance of the driving element (DT).

[0142] FIG. 20 is a cross-sectional view showing in detail the cross-sectional structure of a display panel according to one embodiment of the present invention. It should be noted that the cross-sectional structure of the display panel is not limited to FIG. 20.

[0143] Referring to FIG. 20, a circuit layer, a light-emitting element layer, an encapsulation layer, etc. can be laminated on a substrate (GLS).

[0144] A first buffer layer (BUF1) may be formed on a substrate (GLS). A first metal layer (M1) may be formed on the first buffer layer (BUF1), and a second buffer layer (BUF2) may be formed on the first metal layer (M1). The first metal layer is patterned in a photolithography process. The first metal layer may include a light shield pattern (BSM). The light shield pattern (BSM) blocks external light so that light is not irradiated onto the active layer of the TFT. Each of the first and second buffer layers (BUF1, BUF2) may be formed of an inorganic insulating material and may consist of one or more insulating layers.

[0145] The active layer (ACT) can be formed from a semiconductor material, for example, a-Si, and deposited on the second buffer layer (BUF2), and can be patterned by a photolithography process. The active layer (ACT) includes active patterns for each of the TFTs of the pixel circuit and the TFT of the gate driver. A portion of the active layer (ACT) may be metallized by ion doping. The metallized portion may be used as a jumper pattern connecting metal layers at some nodes of the pixel circuit to connect the components of the pixel circuit.

[0146] A gate insulating film (GI) may be formed on an active layer (ACT). The gate insulating film (GI) may be made of an inorganic insulating material. A second metal layer may be formed on the second gate insulating film (GI). The second metal layer may be patterned by a photolithography process. The second metal layer may include a gate line and a gate electrode pattern (GATE), a lower electrode of a storage capacitor (Cst1), a jumper pattern connecting the patterns of the first metal layer and the third metal layer, etc.

[0147] A first interlayer insulating film (ILD1) may cover a second metal layer (M2). A third metal layer may be formed on the first interlayer insulating film (ILD2), and the second interlayer insulating film (ILD2) may cover the third metal layer. The third metal layer may be patterned by a photolithography process. The third metal layer may include metal patterns (TM), such as the upper electrode of a storage capacitor (Cst1) and a third power line. The first and second interlayer insulating films (ILD1, ILD2) may include an inorganic insulating material.

[0148] A fourth metal layer may be formed on the second interlayer insulating film (ILD2), and an inorganic insulating film (PAS1) and a first flattening layer (PLN1) may be laminated thereon. A fifth metal layer may be formed on the first flattening layer (PLN1).

[0149] A portion of the pattern of the fourth metal layer may be connected to the third metal layer through a contact hole penetrating the first flattening layer (PLN1) and the inorganic insulating film (PAS1). The first and second flattening layers (PLN1, PLN2) may be made of an organic insulating material that flattens the surface.

[0150] The fourth metal layer may include first and second electrodes of a TFT connected to an active pattern of the TFT through a contact hole penetrating the second interlayer insulating film (ILD2). Data lines (DL) and power lines (PL1, PL2, PL3) may be implemented as a pattern (SD1) of the fourth metal layer or a pattern (SD2) of the fifth metal layer.

[0151] The anode electrode (AND) of the light-emitting element (OLED) can be formed on the second planarization layer (PLN2). The anode electrode (AND) can be connected to the electrode of a TFT used as a switch element or driving element through a contact hole penetrating the second planarization layer (PLN2). The anode electrode (AND) can be made of a transparent or translucent electrode material.

[0152] A pixel defining film (BNK) can cover the anode electrode (AND) of a light-emitting device (OLED). The pixel defining film (BNK) is formed in a pattern that defines a light-emitting region (or aperture region) through which light passes from each pixel to the outside. A spacer (SPC) can be formed on the pixel defining film (BNK). The pixel defining film (BNK) and the spacer (SPC) can be integrated with the same organic insulating material. The spacer (SPC) secures a gap between the Fine Metal Mask (FMM) and the anode electrode (AND) so that the FMM does not come into contact with the anode electrode (AND) during the deposition process of the organic compound (EL).

[0153] An organic compound (EL) is formed in the light-emitting region of each pixel defined by the pixel defining film (BNK). A cathode electrode (CAT) of the light-emitting element (OLED) is formed on the front of the display panel (100) to cover the pixel defining film (BNK), the spacer (SPC), and the organic compound (EL). The cathode electrode (CAT) can be connected to a VSS line (PL3) formed by any one of the metal layers below it. A capping layer (CPL) can cover the cathode electrode (CAT). The capping layer (CPL) protects the cathode electrode (CAT) by blocking the penetration of air and out-gassing of the organic insulating material applied on the capping layer (CPL). An inorganic insulating film (PAS2) covers the capping layer (CPL), and a planarization layer (PCL) can be formed on the inorganic insulating film (PAS2). The planarization layer (PCL) may include an organic insulating material. An inorganic insulating film (PAS3) of the encapsulation layer may be formed on the planarization layer (PCL).

[0154] In the first sensing region (SA), the active layer (ACT-OPD) of the organic photodiode (OPD) can be formed between the anode electrode (AND) and the cathode electrode (CAT) on the same plane as the organic compound layer (EL) of the subpixel.

[0155] The circuit layer of the first sensing region (SA) can be implemented with a structure similar to the pixel circuit shown in FIG. 20. Accordingly, the photosensor driving circuit can be implemented with a structure that shares at least some of the wiring with the pixel circuit, as shown in FIGs. 23 to 26g.

[0156] FIGS. 21 and 22 are equivalent circuit diagrams showing a wiring sharing structure between a pixel circuit (CPIX) of a first sensing area (SA) and a photosensor driving circuit (COPD, CPD) according to an embodiment of the present invention. In FIGS. 21 and 22, the pixel circuit is substantially identical to the pixel circuit shown in FIG. 17, so a detailed description thereof is omitted. The photosensor driving circuit may be implemented as the circuit shown in FIGS. 21 and 22, but is not limited thereto.

[0157] FIG. 21 shows an example in which a photosensor (S) is implemented as an organic photodiode (OPD) and the anode electrode, cathode electrode, gate line, and power wiring are shared between the pixel circuit and the photosensor driving circuit.

[0158] Referring to FIG. 21, the photosensor driving circuit (COPD) drives an organic photodiode (OPD) to output a signal (RX) that is photoelectrically converted by the organic photodiode (OPD). The signal (RX) that is photoelectrically converted by the organic photodiode (OPD) can be transmitted to a fingerprint recognition processor (500) through the RX line (RXL).

[0159] The photosensor driving circuit (COPD) is connected to the VDD line (PL1), VSS line (PL3), second to fourth gate lines (GL2~GL4), and RX line (RXL). The second to fourth gate lines (GL2~GL4) can be formed with parallel wiring on the pixel array. The RX line (RXL) can be formed with wiring parallel to the data line (DL) and the VDD line (PL1).

[0160] The photosensor driving circuit (COPD) includes first to third switching elements (M1S~M3S) and a capacitor (Cst2). The first to third switching elements (M1S~M3S) can be implemented as p-channel TFTs.

[0161] The organic photodiode (OPD) includes an anode electrode connected to a third-switching element (M3S), a cathode electrode to which a low-potential power supply voltage (VSS) is applied, and an active layer formed between the anode electrode and the cathode electrode. The active layer of the organic photodiode (OPD) comprises an organic semiconductor material. When a reverse bias voltage is applied, the organic photodiode (OPD) generates a current according to the received light to generate a photoelectric conversion signal (RX).

[0162] The capacitor (Cst2) is connected between the gate electrode of the second switch element (M2S) connected to the fifth node (n5) and the VDD line (PL1). When the third switch element (M3S) is turned on, the capacitor (Cst2) charges the charge from the organic photodiode (OPD) and stores the voltage of the photoelectrically converted signal. The exposure time of the photosensor (S) is determined by the pulse width of the exposure signal (TG) applied to the gate electrode of the third switch element (M3S). As the pulse width of the exposure signal (TG) becomes longer, the amount of charge in the capacitor (Cst2) by the photosensor (S) can increase.

[0163] The first switch element (M1S) is turned on in response to the gate-on voltage (VGL) of the N-1 scan pulse [SCAN(N-1)] to connect the fourth node (n2) to the RX line (RXL). The fourth node (n4) is connected to the second electrode of the first switch element (M1S) and the first electrode of the second switch element (M2S). The gate electrode of the first switch element (M1S) is connected to the second gate line (GL2) to receive the N-1 scan pulse [SCAN(N-1)]. The first electrode of the first switch element (M1S) is connected to the RX line (RXL), and the second electrode of the first switch element (M1S) is connected to the fourth node (n4).

[0164] The second switch element (M2S) controls the amount of current flowing through the RX line (RXL) between the VDD line (PL1) and the fourth node (n4) according to the gate voltage, that is, the voltage of the fifth node (n5). The second switch element (M2S) includes a gate electrode connected to the fifth node (n5), a first electrode connected to the fourth node (n4), and a second electrode connected to the VDD line (PL1). The fifth node (n5) is connected to the second electrode of the third switch element (M3S), a capacitor (Cst2), and the gate electrode of the second switch element (M2S).

[0165] The third-switching element (M3S) is turned on according to the gate-on voltage (VGL) of the exposure signal (TG) to connect the anode electrode of the organic photodiode (OPD) to the fifth node (n5). At this time, the charge from the organic photodiode (OPD) is charged into the capacitor (Cst2). The third-switching element (M3S) includes a gate electrode connected to the fourth gate line (GL4) to which the exposure signal (TG) is applied, a first electrode connected to the anode electrode of the organic photodiode (OPD), and a second electrode connected to the fifth node (n5).

[0166] As shown in FIG. 7, the anode electrodes of the organic photodiode (OPD) and the light-emitting element (OLED) can be formed on the same layer, and the cathode electrodes of the organic photodiode (OPD) and the light-emitting element (OLED) can be formed on the same layer. In this case, when connecting the anode electrode of the organic photodiode (OPD) to the third-s switch element (M3S), the organic photodiode (OPD) can be connected without additional wiring to the photosensor driving circuit (COPD), so the structure of the display panel (100) can be simplified.

[0167] FIG. 22 shows an example in which a photosensor (S) is implemented as an inorganic photodiode (PD) and the gate line and power wiring are shared between the pixel circuit and the photosensor driving circuit. Detailed descriptions of components in the circuit shown in FIG. 22 that are substantially the same as those in the circuit shown in FIG. 21 are omitted.

[0168] Referring to FIG. 22, the photosensor driving circuit (COPD) drives an inorganic photodiode (PD) to output a signal (RX) that is photoelectrically converted by the inorganic photodiode (PD). The signal (RX) that is photoelectrically converted by the inorganic photodiode (OPD) can be transmitted to a fingerprint recognition processor (500) through the RX line (RXL).

[0169] The inorganic photodiode (PD) includes an anode electrode connected to the VDD line (PL1), a cathode electrode connected to the third-s switch element (M3S), and an active layer formed between the anode electrode and the cathode electrode. The active layer of the inorganic photodiode (PD) includes an inorganic semiconductor material. When a reverse bias voltage is applied, the inorganic photodiode (PD) generates a current according to the received light to generate a photoelectric conversion signal (RX).

[0170] The third-switching element (M3S) is turned on according to the gate-on voltage (VGL) of the exposure signal (TG) to connect the cathode electrode of the inorganic photodiode (PD) to the fifth node (n5). At this time, the charge from the inorganic photodiode (PD) is charged into the capacitor (Cst2). The third-switching element (M3S) includes a gate electrode connected to the fourth gate line (GL4), a first electrode connected to the cathode electrode of the inorganic photodiode (PD), and a second electrode connected to the fifth node (n5).

[0171] FIG. 23 is a diagram showing the metal layers of a pixel circuit (CPIX) and a photosensor driving circuit (COPD). In FIG. 23, the first metal layer is omitted. The cross-sectional structure of the pixel circuit (CPIX) and the photosensor driving circuit (COPD) is not limited to FIG. 23. In FIG. 23, GI, ILD1, ILD2, PAS, PLN1, and PLN2 are insulating layers that insulate between the semiconductor layer (ACT), the first metal layer (M02), and the metal layers.

[0172] Referring to FIG. 23, the active layer (ACT) includes a semiconductor pattern (ACTC) having a semiconductor pattern (ACTM) that is partially metallized by ion doping. The semiconductor pattern (ACTC) includes the active pattern of each TFT.

[0173] The second metal layer (M02) can be patterned into gate lines to which scan pulses and EM pulses are applied. The third metal layer (M03) can be patterned into a Vini line (PL3) to which Vini is applied and a gate line to which an exposure signal (TG) is applied. The fourth metal layer (M04) can be patterned into a VDD line (PL1) to which VDD is applied, a data line to which a data voltage (VDATA) is applied, etc. The fifth metal layer (MO4) can be patterned into a VDD line (PL1) to which VDD is applied and an RX line (RXL) to which a signal (RX) converted by an organic photodiode (OPD) is output. Wiring to which the same signal or power supply voltage is applied between the metals can be connected through a dot pattern and a contact hole.

[0174] The storage capacitor (Cst1) of the pixel circuit can be formed between one pattern of the second metal layer (M02) and one pattern of the third metal layer (M03) that overlap each other. The storage capacitor (Cst2) of the photosensor driving circuit can be formed between one pattern of the metallized semiconductor pattern (ACTM) and the third metal layer (M03) that overlap each other.

[0175] Pixel circuits are disposed in the display area (DA) and sensing areas (SA, CA), and a photosensor driving circuit (COPD) is further disposed in the first sensing area (SA). A fourth gate line (GL4) to which an exposure signal (TG) is applied can be connected to the photosensor driving circuit (COPD) across the display area (DA) and the first sensing area (SA). An RX line (RX) can be connected to the photosensor driving circuit (COPD) across the display area (DA) or across the display area (DA) and the second sensing area (CA).

[0176] The fourth gate line (GL4) to which the exposure signal is applied is shown in FIG. 23 as being formed as a pattern of the third metal layer (M02), but is not limited thereto. For example, the fourth gate line (GL4) may be formed as a pattern of the second metal layer (MO2) or the third metal layer (MO3).

[0177] An example of the RX line (RXL) being formed as a pattern of the fifth metal layer (M05) is shown in FIG. 23, but is not limited thereto. For example, the RX line (RXL) may be formed as a pattern of the fourth metal layer (MO4) or the fifth metal layer (MO5).

[0178] FIG. 24 is a plan view showing the layout of the pixel circuit and the photosensor driving circuit in detail. FIG. 25a to FIG. 25 are plan views showing the pattern shape of each layer by separating the main layers in the layout of the pixel circuit and the photosensor driving circuit shown in FIG. 24.

[0179] The first metal layer (MO1) can be patterned in the form shown in FIG. 25a. The first metal layer (M01) may include an optical shield pattern that overlaps with the active pattern of the TFT in the pixel circuit (CPIX). The active layer (ACT) can be patterned in the form shown in FIG. 25b. The active layer (ACT) includes the active patterns of each of the TFTs in the pixel circuit (CPIX) and the photosensor driving circuit (COPD), and a metallized pattern.

[0180] The second metal layer (M02) can be patterned in the form shown in FIG. 25c. The second metal layer (M02) may include gate lines (GL1, GL2, GL3) to which scan pulses and EM pulses are applied, gate electrodes of the TFT, lower electrodes (M02c) of the first storage capacitor (Cst1), jumper patterns (M02a, M02b, M02d), etc. The jumper patterns (M02a, M02b) are used to connect the metal layers through contact holds.

[0181] The third metal layer (M03) can be patterned in the form shown in FIG. 25d. The third metal layer (M03) may include a pattern (M031) in which the upper electrode of the first storage capacitor (Cst1) and the lower electrode of the second storage capacitor (Cst2) are integrated, a Vini line (PL3), a fourth gate line (GL4), jumper patterns (M03a, MO3b), etc.

[0182] The fourth metal layer (M04) can be patterned in the form shown in FIG. 25e. The fourth metal layer (M04) may include a VDD line (PL1), a data line (DL), jumper patterns (M04a to M04g), etc. The upper electrode of the second storage capacitor may be integrated with the VDD line (PL1) of the fourth metal layer (M04).

[0183] The fifth metal layer (M05) can be patterned in the form shown in FIG. 25f. The fifth metal layer (M02) may include VDD lines (P1), RX lines (RXL), jumper patterns (M05a, MO5b), etc. The anode electrodes (AND) of the pixel circuit (CPIX) and the photosensor driving circuit (COPD) can be patterned in the form shown in FIG. 25g. The anode electrode (AND) of the pixel circuit (CPIX) and the anode electrode (AND) of the photosensor driving circuit (COPD) are formed on the same plane.

[0184] As shown in FIGS. 23 to 25g, the pixel circuit (CPIX) and the photosensor driving circuit (COPD) share gate lines and power lines.

[0185] FIG. 26 is a circuit diagram showing a gamma reference voltage generating unit (305) according to one embodiment of the present invention.

[0186] Referring to FIG. 26, the gamma compensation voltage generator (305) receives a high potential input reference voltage (VRH) and a low potential input reference voltage (VRL) from the power supply unit (304) and outputs a gamma compensation voltage (or display driving voltage) for driving the display and a light source driving voltage. Since the amount of current increases as the gate voltage decreases when the driving element (DT) of the pixel circuit is driven by a p-channel TFT, the lower the gamma compensation voltage output from the gamma compensation voltage generator (305), the higher the brightness of the pixel and the light-emitting element (OLED) of the sensing light source.

[0187] The gamma compensation voltage generator (305) includes an input voltage selection unit, a gamma compensation voltage generator (700) that generates a gamma compensation voltage for display driving, and a light source driving voltage generator (600).

[0188] The gamma compensation voltage generator (305) includes a plurality of voltage divider circuits and a plurality of multiplexers. The voltage divider circuit uses resistors connected in series to divide the voltage between a high potential voltage and a low potential voltage, thereby outputting voltages with different voltage levels. Each multiplexer selects a voltage indicated by a register setting value from among the voltages divided by the voltage divider circuit. The timing controller (303) can adjust the voltage level of the output voltage (V0~V256) of the gamma compensation voltage generator (305) for each mode by inputting the register setting value set in each of the display mode, fingerprint recognition mode, and imaging mode to the control terminals of the multiplexers. The register setting value is defined by the register setting data stored in the memory (302) and can be updated.

[0189] The input voltage selection unit includes a voltage divider circuit (RS01), a multiplexer (MUX01) that selects the highest grayscale voltage (V255) according to the first register setting value, a multiplexer (MUX02) that selects the lower gamma compensation voltage according to the second register setting value, and a multiplexer (MUX03) that outputs the lowest gamma compensation voltage (V0) according to the third register setting value. The voltage (V255) output from the multiplexer (MUX01) is supplied to the voltage divider circuits of the gamma compensation voltage generator (700) and the light source driving voltage generator (600). The voltage output from the multiplexer (MUX01) is supplied to the voltage divider circuit of the gamma compensation voltage generator (700).

[0190] The light source driving voltage generation unit (600) includes a 10th voltage divider circuit (RS10) and multiplexers (MUX10, MUX20) connected between the VRL node and the V255 node. The voltage divider circuit (RS10) divides the voltage between the low potential input reference voltage (VRL) and the highest grayscale voltage (V255). The output voltages of the voltage divider circuit (RS10) are voltage levels of a higher grayscale than the highest grayscale voltage (V255). The multiplexer (MUX10) selects one of the voltages divided by the voltage divider circuit (RS10) according to the fourth register setting value and outputs a light source driving voltage (DBV-linked voltage) that varies according to the DBV. DBV (Display Brightness Value) is brightness setting data that varies brightness according to the illuminance sensor output signal of the host system (200) or the user's brightness input value. Depending on the DBV value, the register setting value for controlling each of the multiplexers individually can be varied. The output voltage of the multiplexer (MUX10) is selected from a grayscale voltage range higher than the highest grayscale voltage (V255). Therefore, since the voltage applied to the sensing light source (S) of the first sensing area in fingerprint recognition mode is a grayscale voltage higher than the highest grayscale of the display mode, the sensing light source (S) can emit light with a brightness higher than the maximum brightness of the display mode.

[0191] The multiplexer (MUX20) outputs a light source driving voltage (V256) by selecting either a separate reference voltage (DBV non-linked voltage) set independently of the DBV under the control of the host system (200) or the DBV linked voltage output from the multiplexer (MUX10). The DBV non-linked voltage is a voltage of a higher gradation than the highest gradation voltage (V255). The host system (200) can control the output voltage of the multiplexer (MUX20) using an enable signal (EN) in fingerprint recognition mode and imaging mode. Therefore, the DBF linked voltage or DBV non-linked voltage output from the multiplexer (MUX20) is a voltage (V256) that can obtain a brightness of a higher gradation than the highest gradation voltage (V255).

[0192] The gamma compensation voltage generation unit (700) includes a plurality of voltage divider circuits (RS11~RS18) and a plurality of multiplexers (MUX11~MUX18).

[0193] The first-1 voltage divider circuit (R11) divides the voltage between the output voltage of the first multiplexer (MUX01) and the output voltage of the second multiplexer (MUX02). The first-1 multiplexer (MUX11) selects one of the voltages divided by the voltage divider circuit (R11) according to the register setting value. The output voltage of the first-1 multiplexer (MUX11) is output through a buffer and may be a voltage (V191) of grayscale 191. The first-2 voltage divider circuit (R12) divides the voltage between the output voltage of the first-1 multiplexer (MUX11) and the output voltage of the second multiplexer (MUX02). The first-2 multiplexer (MUX12) selects one of the voltages divided by the voltage divider circuit (R12) according to the register setting value. The output voltage of the first-second multiplexer (MUX12) is output through a buffer and can be a voltage of gradation 127 (V127).

[0194] The first-3 voltage divider circuit (R13) divides the voltage between the output voltage of the first-2 multiplexer (MUX12) and the output voltage of the second multiplexer (MUX02). The first-3 multiplexer (MUX13) selects one of the voltages divided by the voltage divider circuit (R12) according to the register setting value. The output voltage of the first-3 multiplexer (MUX13) is output through a buffer and may be a voltage (V63) of grayscale 63. The first-4 voltage divider circuit (R14) divides the voltage between the output voltage of the first-3 multiplexer (MUX13) and the output voltage of the second multiplexer (MUX02). The first-4 multiplexer (MUX14) selects one of the voltages divided by the voltage divider circuit (R13) according to the register setting value. The output voltage of the 1st-4th multiplexer (MUX14) is output through a buffer and can be the voltage of gradation 31 (V31).

[0195] The first-fifth voltage divider circuit (R15) divides the voltage between the output voltage of the first-fourth multiplexer (MUX14) and the output voltage of the second multiplexer (MUX02). The first-fifth multiplexer (MUX15) selects one of the voltages divided by the voltage divider circuit (R15) according to the register setting value. The output voltage of the first-fifth multiplexer (MUX15) is output through a buffer and may be a voltage (V15) of grayscale 15. The first-sixth voltage divider circuit (R16) divides the voltage between the output voltage of the first-fifth multiplexer (MUX15) and the output voltage of the second multiplexer (MUX02). The first-sixth multiplexer (MUX16) selects one of the voltages divided by the voltage divider circuit (R16) according to the register setting value. The output voltage of the 1st-6th multiplexer (MUX16) is output through a buffer and can be the voltage of gradation 7 (V7).

[0196] The 1-7 voltage divider circuit (R17) divides the voltage between the output voltage of the 1-6 multiplexer (MUX16) and the output voltage of the 02 multiplexer (MUX02). The 1-7 multiplexer (MUX17) selects one of the voltages divided by the voltage divider circuit (R17) according to the register setting value. The output voltage of the 1-7 multiplexer (MUX17) is output through a buffer and may be the voltage (V4) of grayscale 4. The 1-8 voltage divider circuit (R18) divides the voltage between the highest grayscale voltage and the lowest grayscale voltage among the voltages divided by the 1-7 voltage divider circuit (R17). The 1-8 multiplexer (MUX18) selects one of the voltages divided by the voltage divider circuit (R18) according to the register setting value. The output voltage of the 1st-8th multiplexer (MUX18) is output through a buffer and can be the voltage of gradation 1 (V1).

[0197] The gamma compensation voltage generator (700) further includes a plurality of voltage divider circuits (RS21 to RS28). The 2-1 voltage divider circuit (R21) divides the voltage between the highest gamma compensation voltage (V255) and the 191 voltage (V191) to output a gamma compensation voltage between the highest gradation and the 191 voltage. The 2-2 voltage divider circuit (R22) divides the voltage between the 191 voltage (V191) and the 127 voltage (V127) to output a gamma compensation voltage between the 191 and 127 voltages. The 2-3 voltage divider circuit (R23) divides the voltage between the 127 voltage (V127) and the 63 voltage (V63) to output a gamma compensation voltage between the 127 and 63 voltages. The 2-4 voltage divider circuit (R24) divides the voltage between the 63rd level voltage (V63) and the 31st level voltage (V31) to output a gamma compensation voltage between the 63rd level and the 31st level. The 2-5 voltage divider circuit (R25) divides the voltage between the 31st level voltage (V31) and the 15th level voltage (V15) to output a gamma compensation voltage between the 31st level and the 15th level. The 2-6 voltage divider circuit (R26) divides the voltage between the 15th level voltage (V15) and the 7th level voltage (V7) to output a gamma compensation voltage between the 15th level and the 7th level. The 2-7 voltage divider circuit (R27) divides the voltage between the 7th level voltage (V7) and the 4th level voltage (V4) to output a gamma compensation voltage between the 7th level and the 4th level. The 2-8 voltage divider circuit (R28) divides the voltage between the gradation 4 voltage (V4) and the gradation 1 voltage (V1) to output a gamma compensation voltage between the gradation 4 and the gradation 1.

[0198] The gamma compensation voltage generator (305) may include an R gamma compensation voltage generator, a G gamma compensation voltage generator, and a B gamma compensation voltage generator so that the optimal gamma compensation voltage can be output for each RGB. In this case, the register setting value may be set to different voltages in the R gamma compensation voltage generator, the G gamma compensation voltage generator, and the B gamma compensation voltage generator. The gamma compensation voltage output from the R gamma compensation voltage generator is a voltage for each grayscale of the data voltage to be supplied to the R subpixel. The gamma compensation voltage (V0~V256) output from the G gamma compensation voltage generator is a voltage for each grayscale of the data voltage to be supplied to the G subpixel. The gamma compensation voltage output from the B gamma compensation voltage generator is a voltage for each grayscale of the data voltage to be supplied to the B subpixel.

[0199] The gamma compensation voltages (V0~V255) and light source driving voltages (V256) for each grayscale level are input to the DAC of the data driving unit (306). The DAC of the data driving unit (306) converts the pixel data received from the timing controller (303) into gamma compensation voltages with different voltages for each grayscale level to generate a data voltage (Vdata) for display driving. In fingerprint recognition mode, the data driving unit (306) converts the light source driving data received from the timing controller (303) into a light source driving voltage (V256) and supplies it to the subpixels of the sensing area used as a light source through the data line.

[0200] Since the PPI of the sensing areas (SA, CA) is lower than that of the display area (DA), if the pixels of the display area (DA) and the pixels of the sensing areas (SA, CA) are driven with the same data voltage at the same grayscale, the brightness of the sensing areas (SA, CA) may be lowered. The present invention can increase the brightness of the pixels in the sensing areas (SA, CA) by expanding the range of the data voltage applied to the pixels of the sensing areas in the fingerprint sensing mode or the imaging mode by changing the register setting value of the gamma compensation voltage generator (256) in the fingerprint sensing mode or the imaging mode.

[0201] FIG. 27 is a diagram showing the data voltage applied to the pixels of the display area and the data voltage applied to the pixels of the sensing area. In FIG. 27, "PGMA Range" indicates the output voltage range of the gamma compensation voltage generator (305).

[0202] Referring to FIG. 27, the data driving unit (306) expands the range of data voltage (Vdata) applied to the pixels of the sensing areas (SA, CA) more than the range of data voltage (Vdata) applied to the pixels of the display area (DC) because the PPI of the sensing areas (SA, CA) is low.

[0203] Since the contents of the specification described above regarding the problem to be solved, the means for solving the problem, and the effect do not specify the essential features of the claim, the scope of the claim is not limited by the matters described in the specification.

[0204] Although embodiments of the present invention have been described in more detail with reference to the attached drawings, the present invention is not necessarily limited to these embodiments and may be modified in various ways within the scope of the technical spirit of the present invention. Accordingly, the embodiments disclosed in the present invention are intended to explain, not limit, the technical spirit of the present invention, and the scope of the technical spirit of the present invention is not limited by these embodiments. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. The scope of protection of the present invention shall be interpreted by the claims, and all technical spirits within an equivalent scope shall be interpreted as being included within the scope of rights of the present invention. Explanation of the symbols

[0205] DA: Display area SA: First sensing area CA: Second sensing area S: Photosensor SL: Sensing light source SLG1~SLG6: Light source groups R, G, B: Subpixels

Claims

Claim 1 A display device comprising a display panel including a display area in which a plurality of pixels are arranged and a first sensing area in which a plurality of photo sensors and a plurality of pixels are arranged, wherein the pixels of the display area and the pixels of the first sensing area receive data voltage of an input image in a display mode and emit light, and some of the pixels of the first sensing area emit light in a fingerprint recognition mode, wherein the pixels of the first sensing area include a plurality of pixel groups each comprising one or two pixels, wherein a plurality of sensing light sources and a plurality of photo sensors spaced apart from the plurality of sensing light sources are arranged between adjacent pixel groups, and wherein each pixel of the pixel group includes 2 to 4 subpixels, and between a first pixel group and a second pixel group adjacent to each other in a first direction among the plurality of pixel groups, a first distance between two sensing light sources arranged adjacent to each other in the first direction and a second distance between two photo sensors arranged adjacent to each other in the first direction are the same. Claim 2 A display device according to claim 1, wherein the sensing light source emits light and is lit in the fingerprint recognition mode and includes a subpixel that is turned off in the display mode. Claim 3 In claim 2, a display device in which the third distance between adjacent pixel groups within the first sensing area is the same. Claim 4 In claim 2, the subpixel of the sensing light source is a green subpixel, and in the fingerprint recognition mode, the green subpixel of the sensing light source and all subpixels of the pixel groups are illuminated in a display device. Claim 5 In claim 2, the subpixel of the sensing light source is a green subpixel, and in the fingerprint recognition mode, the green subpixel of the sensing light source and the blue subpixel among the subpixels of the pixel groups are illuminated. Claim 6 In claim 2, the subpixel of the sensing light source is a green subpixel, and in the fingerprint recognition mode, only the green subpixel of the sensing light source is illuminated among the subpixels of the first sensing area. Claim 7 In claim 3, a display device in which the number of light sources for sensing increases as the PPI (Pixels Per Inch) of the first sensing area decreases. Claim 8 In claim 2, the light-emitting element of the pixel includes an organic light-emitting diode, the photosensor includes an organic photodiode, the anode electrode of the organic light-emitting diode and the anode electrode of the organic photodiode are disposed on the same plane, the cathode electrode of the organic light-emitting diode and the cathode electrode of the organic photodiode are disposed on the same plane, and at least one wiring is shared between a pixel driving circuit that drives the organic light-emitting diode and a photosensor driving circuit that drives the organic photodiode. Claim 9 A display device according to claim 2, wherein the light-emitting element of the pixel includes an organic light-emitting diode, the photosensor includes an inorganic photodiode, an insulating layer is disposed between the cathode electrode of the organic light-emitting diode and the anode electrode of the inorganic photodiode, and the organic light-emitting diode and the inorganic photodiode are electrically separated from each other. Claim 10 A display device according to claim 9, wherein the anode electrode of the organic light-emitting diode and the cathode electrode of the inorganic photodiode are disposed on the same plane. Claim 11 A display device according to claim 2, further comprising a fingerprint recognition processor that receives a signal converted by photoelectricity by the photo sensor and generates fingerprint pattern image data, wherein the fingerprint recognition processor stores a plurality of fingerprint pattern images while varying the number of sensing light sources illuminated in the fingerprint recognition mode, and selects the image with the highest clarity among the fingerprint pattern images as the image to be used for fingerprint authentication. Claim 12 In claim 2, a display device further comprising: a data driving unit that converts received digital data into a gamma compensation voltage using a digital-to-analog converter (DAC) and outputs a data voltage to be applied to the pixels; and a gamma compensation voltage generating unit that supplies the gamma compensation voltage to the digital-to-analog converter. Claim 13 In claim 12, the gamma compensation voltage generating unit outputs a gamma compensation voltage for each grayscale of the data voltage and outputs a voltage of a higher grayscale than the gamma compensation voltage for each grayscale as a light source driving voltage for driving the sensing light source, the data driving unit converts the light source driving data received in the fingerprint recognition mode into the light source driving voltage, and the light source driving voltage is supplied to a subpixel of the pixel group that is illuminated in the fingerprint recognition mode. Claim 14 A mobile terminal comprising: a display panel including a display area in which a plurality of pixels are arranged, and a first sensing area in which a plurality of photo sensors and a plurality of pixels are arranged; and a fingerprint recognition processor that generates fingerprint pattern image data from a signal photoelectrically converted by a photodiode of the first sensing area, wherein the pixels of the display area and the pixels of the first sensing area receive a data voltage of an input image in display mode and emit light, and some of the pixels of the first sensing area emit light in fingerprint recognition mode, and the pixels of the first sensing area include a plurality of pixel groups each including one or two pixels, and between adjacent pixel groups a plurality of sensing light sources and a plurality of photo sensors spaced apart from the plurality of sensing light sources, and each pixel of the pixel group includes 2 to 4 subpixels, and between a first pixel group and a second pixel group adjacent to each other in a first direction among the plurality of pixel groups, a first distance between two sensing light sources arranged adjacent to each other in the first direction and a second distance between two photo sensors arranged adjacent to each other in the first direction are the same. Claim 15 In claim 14, the mobile terminal comprising a subpixel that is illuminated by a sensing light source in the fingerprint recognition mode and turned off in the display mode. Claim 16 In claim 15, a mobile terminal in which the third distance between adjacent pixel groups within the first sensing area is the same. Claim 17 In claim 15, the fingerprint recognition processor stores a plurality of fingerprint pattern images while varying the number of sensing light sources illuminated in the fingerprint recognition mode, and selects the image with the highest clarity among the fingerprint pattern images as the image to be used for fingerprint authentication. Claim 18 A display device according to claim 1, wherein the display panel further comprises a plurality of pixel groups and a second sensing area comprising a plurality of light-emitting portions spaced apart from each other and disposed between adjacent pixel groups. Claim 19 A mobile terminal according to claim 14, wherein the display panel further comprises a second sensing area including a plurality of pixel groups and a plurality of light-emitting portions spaced apart from each other and disposed between adjacent pixel groups.

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