KR20190112624A - Display panel for providing sensing light to optical fingerprint sensor and fingerprint sensing system comprising thereof - Google Patents

Abstract

Provided are a display panel for providing sensing light to an optical fingerprint sensor and a fingerprint sensing system providing the same. According to an embodiment of the present disclosure, the display panel comprises: a window glass; a retarder disposed under the window glass and retarding a phase of the light; a polarizing plate disposed under the retarder; a pixel layer disposed under the polarizing plate and forming a plurality of pixels each emitting light; and a substrate disposed under the pixel layer and transmitting the sensing light generated by light emitted from at least some of the plurality of pixels scattered by a fingerprint on the window glass.

Description

Display panel for providing sensing light to optical fingerprint sensor and fingerprint sensing system comprising

The technical idea of the present disclosure relates to a display panel, and more particularly, to a structure of a display panel that provides sensing light to an optical fingerprint sensor disposed below the display panel.

Recently, as wired / wireless communication technology and smart device related technology have been rapidly developed, a method of using a fingerprint of a user to perform user authentication, which is one of security methods that can safely use it, is increasing. In order to optimize the convenience and size of a mobile device such as a smart phone, a tablet PC, etc., an on-display fingerprint sensor having a fingerprint sensor mounted on a touch screen (or display) is required. An example of an on-screen fingerprint sensor is an optical fingerprint sensor provided under the display panel. The OLED (Organic Light-Emitting Diode) in the display panel operates as a light source, and the optical fingerprint sensor reads the light generated by the light emitted from the OLED light source to the fingerprint through the optical sensor such as a photodiode. Can be generated.

Problems to be solved by the technical idea of the present disclosure, a display panel structure for providing an optical signal that allows the optical fingerprint sensor to generate a fingerprint image free from distortion and damage, and fingerprint sensing to generate a fingerprint image free from distortion and damage To provide a system.

According to an aspect of the present disclosure, a display panel for providing sensing light to an optical fingerprint sensor according to an embodiment of the present disclosure includes a window glass and a retarder disposed under the window glass and retarding a phase of the light. A polarizer disposed below the retarder, a pixel layer disposed below the polarizer, and each pixel emitting light is formed, and disposed below the pixel layer and irradiated from at least some of the plurality of pixels. The light may include a substrate that transmits the sensing light generated by scattering by a fingerprint on the window glass.

The display panel according to the embodiment of the present disclosure for solving the technical problem, is disposed on a substrate, a pixel layer including a plurality of pixels, a polarization layer disposed on the pixel layer, is disposed on the polarization layer A window glass interposed between the polarizing layer and the window glass, the light emitted from at least some of the plurality of pixels and irradiated in the window glass direction to block the interface reflected light reflected from one surface of the window glass; It may include a filter.

Fingerprint sensing system according to an embodiment of the present disclosure for solving the above technical problem, a fingerprint sensor for generating a fingerprint image based on the sensing light generated by the scattered and reflected light from the display panel and the fingerprint panel; The display panel includes: a pixel layer including a plurality of pixels emitting light, a polarizer disposed on the pixel layer, a retarder disposed on the polarizer and delaying a phase of light by 45 degrees, and the retarder. It may include a window glass disposed on the further.

According to the display panel according to the embodiment of the present disclosure, interfacial reflection light whose light amount changes according to the state of the finger is blocked from being incident to the optical fingerprint sensor provided below the display panel, and scattered by scattering by hitting the valley or ridge of the fingerprint Reflected light may be incident on the fingerprint sensor. Accordingly, the fingerprint sensing system including the display panel according to the exemplary embodiment of the present disclosure may generate the fingerprint image without distortion damage regardless of the state of the finger in contact with the display panel by generating the fingerprint image based on the scattered reflected light. .

1 is a structural diagram illustrating an example of a fingerprint sensing system including a display panel according to an exemplary embodiment of the present disclosure.
2 is an example of a vertical cross-sectional view of a display panel according to an exemplary embodiment of the present disclosure.
3A illustrates a path through which interfacial reflected light is removed in a display panel according to an exemplary embodiment of the present disclosure, and FIG. 3B illustrates a path through which scattered reflected light is incident on a fingerprint sensor in a display panel according to an exemplary embodiment of the present disclosure.
4 illustrates an example of a fingerprint sensor according to an exemplary embodiment of the present disclosure.
5A and 5B illustrate a change in an optical fingerprint image according to a finger state in a fingerprint sensing system to which a display panel according to a comparative example of a display panel according to an exemplary embodiment of the present disclosure is applied.
6 is a diagram illustrating a comparison between a fingerprint image generated in a fingerprint sensing system to which a display panel is applied according to an embodiment of the present disclosure and a fingerprint image generated from a fingerprint sensing system to which a display panel is applied according to a comparative example.
7A to 7C are vertical cross-sectional views illustrating a structure of a display panel according to embodiments of the present disclosure.
8 is a diagram illustrating an electronic device including a display panel according to an exemplary embodiment of the present disclosure.
9 is a diagram illustrating a smartphone according to an embodiment of the present disclosure.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

1 is a structural diagram illustrating an example of a fingerprint sensing system including a display panel according to an exemplary embodiment of the present disclosure.

The fingerprint sensing system 10 may include a smart phone, a laptop computer, a tablet PC, a personal digital assistant, an enterprise digital assistant, and a digital still camera. still camera, digital video camera, portable multimedia player (PMP), portable navigation device (PND), smart security device, door lock, smart home appliance, wearable device, internet of things (IoT) ) May be mounted on an electronic device such as a device, an internet of everything (IoE) device, a drone, or an e-book. However, the present invention is not limited thereto, and the fingerprint sensing system 10 may be mounted on various types of electronic devices having a display function and a fingerprint recognition function.

Referring to FIG. 1, the fingerprint sensing system 10 may include a display panel 100 and a fingerprint sensor 200. The display panel 100 may be disposed above the fingerprint sensor 200. The fingerprint sensor 200 is an optical fingerprint sensor that generates a fingerprint image by sensing received light through the image sensor. The fingerprint sensor 200 senses the light emitted from the display panel 100 reflected by the valley between the ridge and the ridge of the fingerprint, reconstructs the sensing signal, and generates a fingerprint image. Can be generated. Such an optical fingerprint sensor may be referred to as a camera fingerprint sensor.

As the display panel 100, various types of display panels may be applied. In one embodiment, the display panel 100 may be an OLED display panel including an OLED layer formed with an organic light-emitting diode (OLED) emitting light having one or a plurality of colors. However, embodiments of the present disclosure need not be limited thereto, and the fingerprint sensing system 10 according to an embodiment of the present disclosure may include a light emitting diode (LED) display panel, an active-matrix OLED (AMOLED) display panel, or a general The display panel may correspond to various types of display panels such as a liquid crystal display (LCD) panel that performs a display operation using a backlight or an OLED. Alternatively, in addition to the display panels described above, when the light from the light source of the display panel is reflected by the fingerprint and transmitted to the back plane direction (or the fingerprint sensor 120 direction) of the display panel, the display panel is It may be applied to the display panel 100 according to an exemplary embodiment of the present disclosure.

The display panel 100 according to the exemplary embodiment of the present disclosure may include a window glass 110, a phase delay layer 120, a polarization layer 130, a pixel layer 140, and a substrate 150. In addition, the display panel 100 may further include other layers interposed between the components. For example, the display panel 100 may further include a touch electrode layer, a force electrode layer, and the like.

The display panel 100 may have a structure in which the pixel layer 140, the polarization layer 130, the phase delay layer 130, and the window glass 110 are stacked on the substrate 150. The polarization layer 130 (also called a polarizer) is defined as one of the components of incident light, e.g., light emitted from the pixel layer 140 or incident light emitted from the phase delay layer 120 (or phase delay). The incident light can be polarized by transmitting only components that vibrate only in the phase axis (for example, the 90 degree direction). The polarization layer 130 may constitute a linear polarizer or a linear polarizer and a phase retarder.

The phase retardation layer 120 shifts the phase of incident light, for example, the light irradiated from the polarization layer 140 or the light irradiated from the window glass 110 with λ * (N / 4) (where N is 1, 3, 5, 7). ) Can be delayed. For example, the phase delay layer 120 may delay the phase of incident light by 45 degrees (ie, [lambda] / 4). Since the phase retardation layer 120 is interposed between the polarization layer 130 and the window glass 110, the interfacial reflection light generated by interfacial reflection of the light emitted from the pixel layer 140 on the upper surface of the window glass 110 is generated. The incident light in the direction of 150 may be blocked, and only scattered reflected light generated by the light emitted from the pixel layer 140 hitting the valley or the ridge of the fingerprint may be incident toward the substrate 150. This will be described later in more detail with reference to FIGS. 3A and 3B.

The fingerprint sensor 200 may be implemented as a semiconductor chip or a semiconductor package and attached to one surface of the display panel 10. The fingerprint sensor 200 may be implemented as an image sensor such as a CMOS image sensor (CIS) or a charge coupled device (CCD), and includes a pixel array 210 including a plurality of sensing pixels PXS (ie, light receiving pixels). It may include. The pixel array 210 may be implemented as a semiconductor layer or a semiconductor chip in which a plurality of photoelectric conversion elements (eg, photodiodes, phototransistors, photogates, and pinned photodiodes) are formed. In the following description, it is assumed that the photoelectric conversion element in the sensing pixel PXS is implemented with a photodiode.

The fingerprint sensor 200 senses a fingerprint in contact with or near the display panel 100. In a device equipped with the fingerprint sensing system 10 according to the exemplary embodiments of the present disclosure, when a fingerprint is contacted (or approached) on the display panel 10 without a separate button for fingerprint recognition, the fingerprint is detected. Can be recognized. For example, when the user's fingerprint is placed on the window glass 110 of the display panel 100, the light from the OLED in the display panel 100 becomes a light source and is transmitted and scattered and reflected to the user's fingerprint, and the scattered reflected light The light may pass through the substrate 150 of the display panel 100 and be transferred to the pixel array 210 of the fingerprint sensor 200.

The sensing pixel PXS senses light scattered and reflected by different areas of the fingerprint and generates an electrical signal corresponding to the sensed light. Each sensing pixel PXS may generate an electrical signal corresponding to scattered and reflected light on a ridge of a fingerprint, or generate an electrical signal corresponding to scattered and reflected light on a valley between the ridges. The amount of light sensed by the photodiode may vary according to the shape of the fingerprint on which light is reflected, and electrical signals having different levels may be generated according to the amount of light sensed. That is, the electrical signals from the plurality of sensing pixels PXS may include contrast information (or image information), respectively, and regions corresponding to the sensing pixels PXS are ridged through processing of the electrical signals. Recognition or valleys can be determined and the overall fingerprint image can be constructed by combining the determined information.

Meanwhile, in FIG. 1, the pixel array 210 of the fingerprint sensor 200 corresponds to the entire area of the display panel 100, but embodiments of the present disclosure need not be limited thereto. As an example, the pixel array 210 may correspond only to a portion of the display panel 100. Accordingly, when the fingerprint of the user is located in a specific region of the display panel 100, the fingerprint may be sensed. .

2 is an example of a vertical cross-sectional view of a display panel according to an exemplary embodiment of the present disclosure. An OLED display panel will be described as an example.

Referring to FIG. 2, the display panel 100a has a structure in which a substrate 150, an OLED pixel layer 140a, a polarization layer 130a, a phase delay layer 120, and a window glass 110 are stacked. However, the present invention is not limited thereto, and other layers may be interposed between the components in a range in which the stacking order of the components is maintained.

In the display panel 100a according to the present exemplary embodiment, the phase delay layer 120 may be stacked on the polarization layer 130a and the lower portion of the window glass 110, and the phase delay layer 120 may be formed of a first adhesive layer. The display panel 100a may be attached to the display panel 100a by the layer 11 and the second adhesive layer 12. For example, the first adhesive layer 11 and the second adhesive layer 12 may be formed of a transparent optical adhesive material such as optical clear resin (OCR), optically clear adhesive (OCA), or the like.

The substrate 150 may be formed of a transparent insulating material such as glass, quartz, ceramic, and plastic. In an embodiment, the substrate 150 may be formed of a material having solubility. A thin film transistor (TFT) backplane may be formed on one surface 151 of the substrate 150 to apply signals to the pixels. The OLED pixel layer 140a may be formed on the substrate 150, and the OLED pixel layer 140a may include electrodes and organic layers constituting the OLED.

The polarization layer 130a may be formed on the OLED pixel layer 140a, and the polarization layer 130a may include a linear polarizer 131 and a retarder 132. The retarder 132 may delay the phase of incident light by 45 degrees. The linear polarizer 131 may linearly polarize the incident light by transmitting only components that vibrate only in one direction, for example, a 90 degree direction, among the components of the incident light. As such, the polarization layer 130a composed of the linear polarizer 131 and the retarder 132 delaying the phase by 45 degrees may be referred to as a circular polarizer.

The phase delay layer 120 may be formed on the polarization layer 130a, and the polarization layer 130a may be a retarder that delays the phase of incident light by 45 degrees. The window glass 110 may be disposed on the polarization layer 130a to protect the display panel 100a from the outside.

In the optical configuration of the display panel 100a of FIG. 2, the linear polarizer 131 of the polarization layer 130a is interposed between the retarder 132 and the phase delay layer 120 and the phase delay layer 120. Is interposed between the linear polarizer 131 and the window glass 110. In this structure, the phase delay layer 120 may function as a filter for removing the interface reflected light reflected from the light emitted from the OLED pixel layer 140a at the interface between one surface of the window glass 110 and the external air layer. .

3A illustrates a path through which interfacial reflected light is removed in a display panel according to an exemplary embodiment of the present disclosure, and FIG. 3B illustrates a path through which scattered reflected light is incident on a fingerprint sensor in a display panel according to an exemplary embodiment of the present disclosure.

Referring to FIG. 3A, the emission light EL emitted from at least some of the plurality of pixels of the pixel layer 140 may pass through the retarder 132 of the polarization layer 130 and may be delayed in phase. . For example, the retarder 132 may delay the phase of the emission light EL by 45 degrees.

The light EL1 output from the retarder 132 may be incident to the linear polarizer 131. The linear polarizer 131 may transmit only a component vibrating in the 90 degree direction of the phase axis among the components of the light EL1. Accordingly, the light EL2 output from the linear flat light 131 may vibrate in the 90 degree direction.

The phase retardation layer 120, that is, the retarder for delaying the phase of light by 45 degrees may delay the polarization state of the light EL2 having the linear polarization of 90 degrees by 45 degrees. Accordingly, the light EL3 having circular polarization of 135 degrees may be output from the phase delay layer 120.

The light EL3 output from the phase delay layer 120 may be interfacially reflected by a sharp refractive index between the one surface 111 of the window glass 110 and the air layer, that is, the refractive index of the interface. The interfacial reflected light RL may have a phase of 135 degrees. The interfacial reflection light RL may be incident to the phase retardation layer 120, and the retardation layer 120 may retard the phase of the interfacial reflection light RL by 45 degrees. Accordingly, light RL1 having a linear polarization of 180 degrees may be output from the phase delay layer 120.

Light RL1 output from the phase delay layer 1230 may be incident to the linear polarizer 131. However, the linear polarizer 131 may transmit only incident light, that is, components that vibrate in the 90 degree direction of the phase axis of the light RL1. However, since the light RL1 oscillates in the 180 degree direction, the light RL1 cannot transmit the linear polarizer 131. According to the optical mechanism, the reflected light RL interfacially reflected in the display panel 100 according to the exemplary embodiment of the present disclosure may be blocked.

Referring to FIG. 3B, the emission light EL emitted from at least some of the plurality of pixels of the pixel layer 140 may be the polarization layer 130 and the phase delay layer 120, as described with reference to FIG. 3A. Can penetrate. The light EL3 output from the phase delay layer 120 penetrates a surface between the one surface 111 of the window glass 110 and the air layer, that is, an interface, and strikes a valley or ridge of the fingerprint FP, and thus scatters. Can be reflected. The scattered reflected light SL may vibrate not only in a specific direction but also in all directions, such as the light EL3 output from the phase delay layer 120.

The scattered reflected light SL is incident on the window glass 110, and the light SL1 incident on the window glass 110 may be delayed by 45 degrees while passing through the phase delay layer 120.

Light SL2 output from the phase delay layer 120 may be incident to the linear polarizer 131. The linear polarizer 131 may transmit only a component vibrating in the 90 degree direction of the phase axis among the components of the light SL2. Accordingly, the light SL3 output from the linear flat light 131 may vibrate in the 90 degree direction.

The light SL3 output from the linear flattener 131 is incident on the retarder 131, and the retarder 131 may delay the polarization state of the light SL3 having the linear polarization of 90 degrees by 45 degrees. Accordingly, the light SL4 having a circular polarization of 135 degrees may be output from the retarder 131.

The light SL4 output from the polarization layer 140 may pass through the pixel layer 140 through slits between the pixels PX and then pass through the substrate 150 of FIG. 1. Light SL5 transmitted through the substrate may be provided to the fingerprint sensor 200. In an exemplary embodiment, a light collecting part collecting light may be positioned on the fingerprint sensor 200. The pixel array 210 of the fingerprint sensor 200 may receive the light SL5, that is, the sensing light, and generate an electrical signal corresponding to the sensing light. The read circuit 220 may receive sensing signals from the pixel array 210 and generate a fingerprint image based on the sensing signals.

3A and 3B, the polarization layer 130 includes a linear polarizer 131 and a retarder 132. However, this is merely an example, and the polarization layer 130 may include only the linear polarizer 131 or may further include other phase converters in addition to the linear polarizer 131 and the retarder 132.

4 illustrates an example of a fingerprint sensor according to an exemplary embodiment of the present disclosure.

Referring to FIG. 4, the fingerprint sensor 200 may include a pixel array 210, a read circuit 220, and a light condenser 230.

The condenser 230 may collect or receive the sensing light L, for example, the scattered reflected light (SL of FIG. 3B), which is incident on the fingerprint sensor 200. The sensing light L may pass through the condenser 230 and be incident to the pixel array 210. The light collecting unit 230 may be implemented as a pinhole mask, an ultra-thin lens, and the like, including a plurality of pinholes.

The pixel array 210 may include a plurality of sensing pixels (ie, light receiving pixels), and each of the plurality of sensing pixels senses sensing light, eg, scattered reflected light RL, and corresponds to the sensed light. It can generate an electrical signal, i.e. a sensing signal.

The read circuit 220 may receive sensing signals provided from the plurality of sensing pixels of the pixel array 210 and generate a fingerprint image FPI through a processing operation on the sensing signals.

The read circuit 220 may include a sensing circuit 221, a controller 222, a signal processor 223, a buffer 224, and an interface 225.

The sensing circuit 221 may receive sensing signals from the pixel array 210 and convert the received sensing signals into digital sensing signals. The sensing circuit 221 may include a signal amplifier, and the signal amplifier may increase the range of sensing signals received from the pixel array 210. In addition, the sensing circuit 221 may include a plurality of analog-to-digital converters, and each of the plurality of analog-to-digital converters may include a sensing signal provided from a corresponding channel among respective channels connected to the pixel array 210. Can be converted to The converted sensing signal may be provided to the signal processor 223 or may be temporarily stored in the buffer 234 and then provided to the signal processor 223.

The buffer 224 may temporarily store the converted sensing signal provided from the sensing circuit 221. The buffer 224 may also store various kinds of setting values, algorithms, and the like set for the operation of the fingerprint sensor 200. The buffer 224 may be implemented as at least one of volatile memory or nonvolatile memory. Nonvolatile memory includes Read Only Memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable and Programmable ROM (EEPROM), Flash memory, Phase-change RAM (PRAM), Magnetic RAM (MRAM), Resistive RAM (RRAM), ferroelectric RAM (FRAM), and the like. Volatile memory can include DRAM (Dynamic RAM), SRAM (Static RAM), SDRAM (Synchronous DRAM), PRAM (Phase-change RAM), MRAM (Magnetic RAM), RRAM (Resistive RAM), FeRAM (Ferroelectric RAM), etc. Can be.

The signal processor 223 may generate a fingerprint image FPI based on the converted sensing signals. The signal processor 223 may generate a fingerprint image FPI by performing image processing on the converted sensing signals based on various image processing techniques.

The controller 222 may control the overall operation of the fingerprint sensor 200. The controller 222 may control driving timing of the sensing circuit 221. In an embodiment, the fingerprint sensor 200 may operate in synchronization with display drive circuitry for driving the display panel, and the controller 222 may timing from a host (eg, an application processor) or display drive circuitry via the interface 225. Signals for control can be received. The controller 222 can transmit the fingerprint image (FPI) to the host via the interface 225.

The interface 225 may include an RGB interface, a CPU interface, a serial interface, a mobile display digital interface (MDDI), an inter integrated circuit (I2C) interface, a serial pheripheral interface (SPI), a micro controller unit (MCU) interface, and a MIPI interface. Include one of a mobile industry processor interface (eDP), an embedded displayport (eDP) interface, a D-subminiature (D-sub), an optical interface, a D-subminiature (D-sub), or a high definition multimedia interface (HDMI). can do. Additionally or alternatively, the interface 225 may include, for example, a mobile high-definition link (MHL) interface, a secure digital (SD) card, a multi-media card (MMC) interface, or an infrared data association (IrDA) compliant interface. can do. The interface 225 may further include various serial or parallel interfaces.

5A and 5B illustrate a change in an optical fingerprint image according to a finger state in a fingerprint sensing system to which a display panel according to a comparative example of a display panel according to an exemplary embodiment of the present disclosure is applied.

As described above with reference to FIGS. 1 to 3B, in the display panels 100 and 100a according to the exemplary embodiment, a phase delay layer 120 is interposed between the window glass 110 and the polarization layer 130. Due to this optical structure, interfacial reflected light generated by reflecting light emitted from the pixels at the interface between the window glass and the air layer can be prevented from entering the fingerprint sensor. However, the display panel according to the comparative example does not include the phase delay layer 120, and accordingly, the fingerprint sensor may receive interfacial reflected light and generate a fingerprint image based on the interfacial reflected light.

Referring to FIG. 5A, the light EL emitted from the pixel layer is interfacially reflected by a sharp change in refractive index at the interface between the window glass 110 ′ and the air layer, and the interface reflected light RL is inside the window glass 110 ′. It may be incident to. When the finger in the normal state contacts the window glass 110 ′, a buffer layer BL may be formed to reinforce the contact surface of the ridge by the sweat secreted through the pores of the ridge. Therefore, in the ridge portion, the amount of the interfacial reflection light RL is very small, and a considerable amount of the light TL transmitted through the window glass 110 'can be absorbed by the epidermal layer. On the other hand, the amount of the interfacial reflected light RL may be relatively high in the bone portion. Thus, a fingerprint image (FPI) with dark ridges and light valleys may be created.

Referring to FIG. 5B, when the dry finger contacts the window glass 110 ′, the secretion of sweat through the pores is less, and a buffer layer may not be formed at the ridge, and a large amount of interfacial light is emitted at the ridge. (RL) may be incident on the fingerprint sensor. Thus, portions of the ridges appear bright, which may cause the ridges to appear broken in the fingerprint image (FPI). As described above, in the fingerprint sensing system to which the display panel according to the comparative example is applied, the fingerprint image FPI may vary according to the condition of the finger such as the degree of moisture and the amount of oil, and the fingerprint image FPI may be distorted or damaged. Can be.

However, as described above, in the fingerprint sensing system (10 of FIG. 1) according to the embodiment of the present disclosure, the display panel 100 blocks the interfacial reflection light RL and transmits the scattered reflection light SL, thereby providing a fingerprint sensor. The 200 may generate an image based on the scattered reflected light SL. As shown in FIGS. 5A and 5B, some of the light transmitted through the window glass 110 ′ may be scattered by hitting the ridges and valleys, and the scattered reflected light SL may be incident. The amount of scattered reflected light SL may be determined by the distance from the window glass 110 to the point of scattering, for example, the ridge and the epidermis of the valley. Since the light amount of the scattered reflected light SL is less affected by the state of the finger, the sensor of the fingerprint sensor 200 may generate a fingerprint image of a predetermined level regardless of the state of the finger.

6 is a diagram illustrating a comparison between a fingerprint image generated in a fingerprint sensing system to which a display panel is applied according to an embodiment of the present disclosure and a fingerprint image generated from a fingerprint sensing system to which a display panel is applied according to a comparative example.

Case 1 represents a fingerprint image FP ′ generated in the fingerprint sensing system to which the display panel according to the comparative example is applied, and case 2 represents a fingerprint sensing system to which the display panel 100 of FIG. 1 is applied according to an embodiment of the present disclosure. Figure 1 shows the fingerprint image (FPI) generated in 10).

As shown in Case 1, the display panel according to the comparative example does not include a phase delay layer between the polarization layer 130 ′ and the window glass 110 ′. Accordingly, when sensing the object OBJ, ie, the fingerprint, the interface reflected light is not blocked, and the fingerprint image FPI 'may be generated based on the interface reflected light. Therefore, a fingerprint image FPI ′ having a bright bone VA and a dark ridge RD may be generated.

As shown in case 2, in the display panel according to the exemplary embodiment of the present disclosure, a phase delay layer 120 is interposed between the polarization layer 130 and the window glass 110. Accordingly, the fingerprint image FPI may be generated based on the scattered reflected light that is intercepted by the interfacial reflected light and is scattered and reflected upon the bone VA of the fingerprint and the skin of the ridge RD. The amount of scattered reflected light can be determined by the distance from the window glass 110 to the point where it is scattered, such as the ridge and the epidermis of the valley. Since the ridge RD is located closer to the window glass 110 than the valley VA, the amount of scattered reflected light of the ridge RD may be greater than the amount of scattered reflected light of the valley VA. Thus, a fingerprint image FPI with a bright ridge RD and a dark valley VA may be generated.

7A to 7C are vertical cross-sectional views illustrating a structure of a display panel according to embodiments of the present disclosure. 7A to 7C illustrate a display panel (or touch screen panel) structure including a touch electrode.

Referring to FIG. 7A, below the window glass WG, the touch electrode TE, the glass GL, the retarder RT, the polarizer PR, the upper glass TG, the pixel layer PL, and Lower glass BG may be stacked in sequence. The retarder RT, the polarizer PR, and the lower glass BG may correspond to the phase delay layer 120, the polarization layer 130, and the substrate 150 of FIG. 1, respectively. According to the present exemplary embodiment, the touch panel may be formed separately from the display panel, and the touch electrode TE may be patterned on the glass GL, that is, the dedicated substrate of the touch panel.

Referring to FIG. 7B, the retarder RT, the polarizer PR, the touch sensing electrode TE, the top glass TG, the pixel layer PL, and the lower glass BG are disposed below the window glass WG. Can be stacked in turn. According to the present exemplary embodiment, the display panel may be formed in an on-cell type in which the touch electrode TE is patterned on the top glass TG of the display panel.

Referring to FIG. 7C, the retarder RT, the polarizer PR, the top glass TG, the pixel layer PL, and the lower glass BG may be sequentially stacked below the window glass WG. The touch electrode TX may be formed in the pixel layer PL. According to the present exemplary embodiment, the display panel may be formed in an in-cell type in which the touch electrode TE is integrally formed with the pixel. In an embodiment, one of the electrodes constituting the pixel may be used as the touch electrode TE. For example, the common electrode of the pixel may be used as the touch electrode TE.

8 is a diagram illustrating an electronic device including a display panel according to an exemplary embodiment of the present disclosure.

Referring to FIG. 8, the electronic device 1000 may include a fingerprint sensing system including a display panel 100 ′ and a fingerprint sensor 200, a driving circuit 300 for driving the display panel, and a host 400. Can be. For example, the host 400 may be an application processor (AP).

The display panel 100 ′ may include a window glass 110, a phase delay layer 120, a polarization layer 130, a touch sensing layer 160 (or a touch panel), a pixel layer 140, and a substrate 150. It may include. The window glass 110, the phase delay layer 120, the polarization layer 130, the pixel layer 140, and the substrate 150 have been described with reference to FIG. 1, and thus redundant descriptions thereof will be omitted. Meanwhile, the display panel 100 ′ of FIG. 8 may include a touch sensing layer 160 in which a plurality of touch sensing electrodes are formed. In FIG. 8, the tummy sensing layer 160 is illustrated below the polarization layer 130, but is not limited thereto. As described above with reference to FIGS. 7A to 7C, the touch sensing layer 160 may be in phase. The upper layer may be formed on the delay layer 120 or may be integrally formed with the pixel layer 140. The touch sensing layer 160 is disposed to sense a user's touch operation. For example, the touch sensing layer 160 to which the capacitive touch sensing layer 160 is applied has a capacitance value based on a user's touch. The sensing units may be changed.

The fingerprint sensor 200 may be positioned below the display panel 100 ′, and the fingerprint sensor 200 is based on scattered reflected light generated by the light output from the pixel layer 140 hitting the fingerprint, as described above. The fingerprint image FPI may be generated, and the fingerprint image FPI may be provided to the host 400. The host 400 may perform functions such as user authentication and security authentication of the electronic device 1000 based on fingerprint authentication based on the fingerprint image FPI.

The driving circuit 300 may include a display driving circuit 310 and a touch controller 320. The display driving circuit 310 converts the image data IDAT provided from the host 400 into an image signal and provides the image signal to the display panel 100 'to display an image on the display panel 100'. Can be. The touch controller 320 may detect a change in capacitance of sensing units of the touch sensing layer 160 to generate a touch sensing result. As an example, the touch controller 320 may provide a driving signal for driving the touch sensing layer 160, and may receive and process an electrical signal according to a change in capacitance of the sensing units in the touch sensing layer 160. . The touch controller 321 may calculate touch coordinates Txy and provide the touch coordinates Txy to the host 400.

The host 400 controls the driving circuit 300 and the fingerprint sensor 200, and the data provided from the driving circuit 300 and the fingerprint sensor 200, for example, touch coordinates Txy and a fingerprint image FPI, may be provided. As a basis, the functions of the electronic apparatus 1000 may be performed.

In an embodiment, the display driving circuit 310, the touch controller 320, and the fingerprint sensor 200 may communicate with each other or through the host 400. For example, the display driving circuit 310 may provide a timing signal indicating a display driving time to the touch controller 320, and the touch controller 320 may perform touch sensing in a non-displayed time period based on the timing signal. Can be. The touch controller 320 may detect a touch input generated on the display panel 100 ′ and provide the touch input to the host 400, and the host 400 may generate a fingerprint sensor 200 based on the touch input. Fingerprint sensing may be performed, and the display driving circuit 310 may be controlled to drive the display panel 100 ′. As such, the display driving circuit 310, the touch controller 320, and the fingerprint sensor 200 may communicate with each other to perform a display driving operation, a touch sensing operation, and a fingerprint sensing operation.

In an embodiment, the driving circuit 300 may be implemented as one semiconductor chip. The display driving circuit 310 and the touch controller 320 may be integrated on one semiconductor substrate. In some embodiments, at least a portion of the readout circuit 210 of FIG. 4 may be integrated with the display driving circuit 310 or the touch controller 320 on one semiconductor substrate.

9 is a diagram illustrating a smartphone according to an embodiment of the present disclosure.

Referring to FIG. 9, the smartphone 2000 may include a display panel 2100, a housing 2100, and a sensor 2300. The sensor 2300 may be disposed under the display panel 2200 and in the housing 2100. The smartphone 2000 may also include an application processor for controlling the overall operation of the smartphone 2000 and a driving circuit for driving the display panel 2100, for example, a display driving circuit and a touch controller.

The housing 2100 may form an appearance of the smartphone 2000, and may protect components of the smartphone 2000, such as integrated circuits, a battery, an antenna, and the like, from an external shock or scratch.

The display panel 2200 may operate as an input / output device of the smartphone 2000 by performing display, touch sensing, and fingerprint sensing. The display panel described with reference to FIGS. 1 to 8 may be applied as the display panel 2200 of the present embodiment. As described above, the phase delay layer and the polarization layer may be stacked below the window glass 2210 of the display panel 2200.

The fingerprint sensor 2300 is an optical fingerprint sensor and is disposed below the display panel 2200, and the fingerprint image is based on scattered and scattered light by the light emitted from the pixel layer of the display panel 2200 hitting the ridges and valleys of the fingerprint. Can be generated. Since the area for fingerprint sensing overlaps with the display area, a separate space for the fingerprint sensor is not required in front of the smartphone 2000. Thus, the display panel 2200 may have a large area as much as possible at the front of the smartphone 2000.

In addition, as described above, the fingerprint sensor 2300 generates a fingerprint image based on scattered reflected light instead of interfacial reflected light, so that the fingerprint sensor 2300 may be distorted or damaged regardless of the environment using the smartphone 2000 or the state of the user's finger. Fingerprint images that are missing can be created. Therefore, the fingerprint authentication function of the smartphone 2000 may be improved.

As described above, exemplary embodiments of the present disclosure have been disclosed. Although the present disclosure has been described with reference to the embodiments illustrated in the drawings, these are merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible.

Claims (10)

A display panel for providing sensing light to an optical fingerprint sensor, comprising:
Window glass;
A retarder disposed below the window glass and retarding the phase of the light;
A polarizer disposed under the retarder;
A pixel layer disposed under the polarizer and having a plurality of pixels each emitting light; And
And a substrate disposed below the pixel layer, the substrate configured to transmit the sensing light generated by light emitted from at least some of the plurality of pixels scattered by a fingerprint on the window glass. The display panel of claim 1, wherein the retarder delays the phase of the light by 45 degrees. The display panel of claim 2, wherein the retarder blocks interface reflected light generated by the light output from at least some of the plurality of pixels reflected by the interface between the window glass and the air layer. The method of claim 1, wherein the polarizing plate,
A second retarder for retarding the phase of the light; And
And a linear polarizer for transmitting only components that vibrate according to a specified phase axis among the components of light. The method of claim 1,
And the light amount corresponding to the ridge of the fingerprint among the sensing light is greater than the light amount corresponding to the valley of the fingerprint. The optical fingerprint sensor of claim 1,
And a display panel disposed below the substrate. The method of claim 1, wherein each of the plurality of pixels,
A display panel comprising an organic light emitting diode. The method of claim 1,
And a touch sensing layer on which touch electrodes are formed. Display panel; And
And a fingerprint sensor configured to generate a fingerprint image based on the sensing light generated by the light emitted from the display panel by being scattered and reflected on the fingerprint.
The display panel,
A pixel layer comprising a plurality of pixels emitting light;
A polarizer disposed on the pixel layer;
A retarder disposed on the polarizer and retarding a phase of light by 45 degrees; And
And a window glass disposed on the retarder. 10. The fingerprint sensing system of claim 9, wherein the retarder blocks the incident light reflected by the interface between the window glass and the air layer from entering the fingerprint sensor.

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