Display device and mobile information terminal

Abstract

Display device and mobile information terminal. A display device and a mobile information terminal including the display device are disclosed. The display device includes: a display panel on which a fingerprint is touched; and a fingerprint sensor coupled to the display panel, the fingerprint sensor being configured to sense light reflected from the fingerprint on a display area of the display panel. The fingerprint sensor is attached to the display panel obliquely at a predetermined angle with respect to a reference line parallel to a major axis of the display panel.

Description

[0001] This application is a divisional application of the invention patent application with the application date of September 10, 2018, application number 201811050296.2, and invention title "display device and mobile information terminal including the same". Technical Field

[0002] The present disclosure relates to a display device that senses a fingerprint at a screen (i.e., a display area) of a displayed image, and a mobile information terminal including the display device. Background Art

[0003] According to the material of the light-emitting layer, electroluminescent displays are classified into inorganic electroluminescent displays and organic electroluminescent displays. An active matrix organic light-emitting diode (OLED) display includes a plurality of OLEDs capable of self-emitting light, and has advantages such as fast response time, high luminous efficiency, high brightness, and wide viewing angle.

[0004] An OLED includes an anode, a cathode, and an organic compound layer located between the anode and the cathode. The organic compound layer generally includes a hole injection layer (HIL), a hole transport layer (HTL), a light-emitting layer (EML), an electron transport layer (ETL), and an electron injection layer (EIL). When a power supply voltage is applied to the anode and the cathode, holes passing through the hole transport layer (HTL) and electrons passing through the electron transport layer (ETL) move to the light-emitting layer (EML) and combine, thereby forming excitons. As a result, the light-emitting layer (EML) generates visible light through the excitons.

[0005] A fingerprint sensor applied to a mobile information terminal is provided at a specific position outside the screen, such as a home button. The fingerprint sensor can be provided in a border area outside the screen, but this will cause an increase in the border area. The structure of the display panel can be changed such that the fingerprint sensor is provided on the display panel.

[0006] The fingerprint sensor can be provided on a liquid crystal display. When the fingerprint sensor is provided between the display panel and the backlight unit of the liquid crystal display, the fingerprint sensor is visible in the screen area. Due to its structure, the prism sheet of the backlight unit has many air gaps. Since the reception efficiency of the fingerprint sensor is reduced due to the air gaps, the fingerprint sensor cannot be provided below the screen area of the liquid crystal display. Summary of the Invention

[0007] The present disclosure provides a display device capable of sensing a fingerprint at a screen without moire interference, and a mobile information terminal including the display device.

[0008] In one aspect, a display device is provided, which includes: a display panel with a fingerprint touched thereon; and a fingerprint sensor coupled to the display panel, the fingerprint sensor being configured to sense light reflected from the fingerprint on the display area of the display panel. The light reflected from the fingerprint passes through the display panel and is incident on the fingerprint sensor. The fingerprint sensor is attached to the display panel obliquely at a predetermined angle with respect to a reference line parallel to the long axis of the display panel.

[0009] The predetermined angle is an angle of 20° to 45° with respect to the reference line parallel to the long axis of the display panel. The display device further includes a flexible circuit board, and the fingerprint sensor is mounted on the flexible circuit board.

[0010] The flexible circuit board includes: a sensor mounting portion on which the fingerprint sensor is mounted; and a tail portion that is connected to the sensor mounting portion and connected to the main board.

[0011] The attachment direction line of the fingerprint sensor passes through the center of the fingerprint sensor and the center in the width direction of the flexible circuit board and intersects with the reference line. The angle of the attachment direction line of the fingerprint sensor with respect to the reference line is 20° to 45°.

[0012] The tail portion of the flexible circuit board includes: a first tail portion located near the sensor mounting portion; and a second tail portion that is bent from the first tail portion at a predetermined angle.

[0013] The fingerprint sensor and the sensor mounting portion of the flexible circuit board are arranged at an angle of 20° to 45° with respect to the reference line. The first tail portion is connected to the sensor mounting portion and extends at an angle of 20° to 45° with respect to the reference line. The second tail portion is bent from the first tail portion at a small angle of 110° to 135°.

[0014] The fingerprint sensor and the sensor mounting portion of the flexible circuit board are arranged at an angle of 20° to 45° with respect to the reference line. The tail portion is connected to the sensor mounting portion and is bent from the sensor mounting portion at a small angle of 110° to 135°.

[0015] The fingerprint sensor and the sensor mounting portion of the flexible circuit board are arranged at an angle of 20° to 45° with respect to the reference line. The first tail portion extends parallel to the reference line. The second tail portion is bent from the first tail portion at a small angle of 90°.

[0016] The fingerprint sensor is disposed at an angle of 20° to 45° with respect to the reference line. One side of the sensor mounting portion of the flexible circuit board is parallel to the reference line. The major axis of the tail portion of the flexible circuit board is perpendicular to the reference line.

[0017] The pixels of the fingerprint sensor are unevenly arranged.

[0018] In another aspect, there is provided a mobile information terminal including: a display panel on which a fingerprint is touched; a fingerprint sensor coupled to the display panel, the fingerprint sensor being configured to sense light reflected from the fingerprint on a display area of the display panel; a main board connected to the fingerprint sensor; and a battery connected to the main board. The fingerprint sensor is attached to the display panel at a predetermined angle in an inclined manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings may be included to provide a further understanding of the present disclosure and are incorporated into and constitute a part of this specification. The drawings illustrate embodiments of the present disclosure and, together with the specification, are used to explain the various principles of the present disclosure.

[0020] Figure 1 is a cross-sectional view and a plan view illustrating a directional light source device according to an embodiment of the present disclosure.

[0021] Figure 2 illustrates Figure 1 a cross-sectional view of an optical path in the transparent substrate shown.

[0022] Figure 3 is a cross-sectional view illustrating a directional light source device disposed on a display panel.

[0023] Figure 4 illustrates a fingerprint sensing area.

[0024] Figure 5 is a cross-sectional view illustrating a fingerprint sensor attached to a display panel.

[0025] Figure 6 is a cross-sectional view illustrating an example in which pixels of a display panel operate as a fingerprint recognition light source.

[0026] Figure 7 and Figure 8 is a cross-sectional view illustrating an example in which a display panel and a fingerprint sensor according to an embodiment of the present disclosure are applied to a mobile information terminal.

[0027] Figure 9A illustrates an example in which the attachment angle of the fingerprint sensor to the display panel is 90°.

[0028] Figure 9B Illustrates moiré interference seen in the output image of the fingerprint sensor when the attachment angle is 90°.

[0029] Figure 10A Illustrates an example where the attachment angle between the fingerprint sensor and the display panel is 45°.

[0030] Figure 10B Illustrates the output image of the fingerprint sensor when the attachment angle is 45°.

[0031] Figure 11A Illustrates an example where the attachment angle between the fingerprint sensor and the display panel is 20°.

[0032] Figure 11B Illustrates a captured image of moiré interference seen when the attachment angle is 20°.

[0033] Figure 12 Is a plan view schematically illustrating the structure of the fingerprint sensor.

[0034] Figure 13A and Figure 13B Is a plan view illustrating the structure of the first flexible circuit board.

[0035] Figure 14 and Figure 15 Schematically illustrates a mobile information terminal according to an embodiment of the present disclosure.

[0036] Figure 16 Is a plan view of the mobile information terminal when viewed from the rear surface of the mobile information terminal in a state where the rear cover of the mobile information terminal is separated.

[0037] Figure 17 Is a cross-sectional view illustrating the structure of a mobile information terminal according to an embodiment of the present disclosure.

[0038] Figure 18A 、 Figure 18B 、 Figure 19A 、 Figure 19B 、 Figure 20A 、 Figure 20B 、 Figure 21A and Figure 21B Illustrates various methods of setting the fingerprint sensor and the first flexible circuit board according to embodiments of the present disclosure.

[0039] Figure 22 Schematically illustrates the pixel array of the display panel and the pixel array of the fingerprint sensor according to an embodiment of the present disclosure. Detailed Description

[0040] Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and can be implemented in various forms. These embodiments are provided to more completely describe the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art to which the present disclosure pertains. The specific features of the present disclosure may be defined by the scope of the claims.

[0041] In the accompanying drawings used to describe the embodiments of the present disclosure, the shapes, sizes, ratios, angles, quantities, etc. illustrated are merely exemplary, but the present disclosure is not limited thereto, unless so specified. The same reference numerals always denote the same elements. In the following description, detailed descriptions of specific functions or configurations related to this document that may unnecessarily obscure the gist of the present invention have been omitted.

[0042] In the present disclosure, when using terms such as "comprising", "having", "consisting of", etc., other components may be added unless "only~" is used. Singular expressions may include plural expressions as long as they do not have an apparently different meaning in the context.

[0043] In the interpretation of components, even if not separately described, it is interpreted as including the boundaries or ranges of errors.

[0044] In the description of positional relationships, when a structure is described as "on or above" another structure, "under" another structure, "next to" another structure, this description should be interpreted as including the case where the structures are in direct contact with each other and the case where a third structure is provided between them.

[0045] Terms such as "first", "second", etc. may be used to describe various components, but the components are not limited by these terms. These terms are only for the purpose of distinguishing one component from other components. For example, without departing from the scope of the present disclosure, the first component may be designated as the second component, and vice versa.

[0046] The features of the embodiments of the present disclosure may be partially or fully combined with each other and can be interlocked and driven in various ways technically. The embodiments may be implemented independently or may be implemented in combination with each other.

[0047] A display device according to an embodiment of the present disclosure includes an optical fingerprint sensor that uses a light source and a fingerprint sensor. In the following embodiments, the display device according to an embodiment of the present disclosure is described focusing on an electroluminescent display. More specifically, an embodiment of the present disclosure focuses on an organic electroluminescent display, which is configured such that each pixel includes an organic light-emitting diode (OLED) serving as a self-luminous element, as an example of an electroluminescent display. However, it should be noted that the technical idea of the present disclosure is not limited to an organic electroluminescent display and can be applied to an inorganic electroluminescent display including an inorganic electroluminescent material. The display device according to an embodiment of the present disclosure can be applied to a mobile information terminal. The mobile information terminal includes a mobile phone, a smart phone, a tablet computer, a notebook computer, a wearable device, and the like.

[0048] The display device according to an embodiment of the present disclosure is configured such that Figures 1 to 5 the directional light source device SLS shown in is provided on the display panel and the fingerprint sensor is provided below or inside the display panel, so as to sense a fingerprint at the screen where a display input image is sensed. When a user's fingerprint touches the directional light source device SLS, the light reflected from the fingerprint is converted into an electrical signal by the fingerprint sensor and detected as a fingerprint pattern.

[0049] Referring to Figures 1 to 5 , the directional light source device SLS according to an embodiment of the present disclosure is a light source of a fingerprint sensor coupled to the display panel DPNL. The directional light source device SLS includes a transparent substrate CP, a light source LS, a light incident element CHOE, a light exit element VHOE, and a low refractive index layer LR. The transparent substrate CP may be a cover glass covering the display panel DPNL.

[0050] The directional light source device SLS is an optical device for scattering collimated light into a large area within the transparent substrate CP. Preferably but not necessarily, the light source LS provides collimated light. The light source LS irradiates a laser in an infrared band or a visible band onto the light incident element CHOE.

[0051] The light incident element CHOE is disposed between the light source LS and the transparent substrate CP, and refracts the light from the light source LS at an angle such that the light can be totally reflected within the transparent substrate CP. The light exit element VHOE is disposed on the screen AA of the display panel DPNL and between the display panel DPNL and the transparent substrate CP. The light exit element VHOE refracts a part of the light traveling within the transparent substrate CP such that a part of the light traveling within the transparent substrate CP can pass through the rear surface (or lower surface) of the transparent substrate CP and travel toward the display panel DPNL. The low refractive index layer LR is disposed between the light exit element VHOE and the display panel DPNL, and the refractive index of the low refractive index layer LR is less than the refractive index of the light exit element VHOE.

[0052] The light-emitting element VHOE and the light-incident element CHOE are attached to the rear surface of the transparent substrate CP. The light-emitting element VHOE is an optical element configured to provide emitted light 300. The screen AA of the display panel DPNL is disposed below the light-emitting element VHOE. The screen AA of the display panel DPNL is a display area including a pixel array for displaying an input image.

[0053] The light-incident element CHOE is an optical element configured to convert the light from the light source LS such that the light from the light source LS has collimation characteristics while being diffused into the transparent substrate CP. The light-incident element CHOE may be disposed at an edge of the display panel DPNL so as to face the light source LS.

[0054] The light-emitting element VHOE and the light-incident element CHOE may be disposed on the same plane. Considering the manufacturing process, preferably but not necessarily, the light-emitting element VHOE and the light-incident element CHOE are formed in different regions of a film. The light-emitting element VHOE and the light-incident element CHOE may be holographic optical elements. The light-emitting element VHOE and the light-incident element CHOE may be manufactured simultaneously during the holographic recording process. In a state where the main film having the pattern of the light-emitting element VHOE and the main film having the pattern of the light-incident element CHOE are disposed adjacent to each other, the holographic pattern for the light-emitting element and the holographic pattern for the light-incident element may be simultaneously recorded on a holographic film.

[0055] The holographic recording method can be classified into a transmission recording method and a reflection recording method. The transmission recording method irradiates reference light and object light onto one surface of the holographic film, and records an interference pattern on the recording surface of the holographic film. When the reference light is irradiated onto one surface of the holographic film on which information is recorded using the transmission recording method, the information of the object light is reconstructed using the +1st order diffracted light and the -1st order diffracted light transmitted through the holographic film.

[0056] The reflection recording method irradiates reference light and object light onto the holographic film, with the holographic film interposed between the reference light and the object light. In the reflection recording method, the reference light is irradiated onto one surface of the holographic film, and the object light is irradiated onto the other surface opposite to the one surface of the holographic film. Therefore, the interference pattern of the reference light and the object light is recorded on the recording surface of the holographic film. When the reference light is irradiated onto one surface of the holographic film on which information is recorded using the reflection recording method, the information of the object light is reconstructed using the +1st order diffracted light and the -1st order diffracted light reflected from the holographic film.

[0057] A low refractive index layer LR is disposed between the element VHOE and the display panel DPNL, and between the element CHOE and the display panel DPNL. The refractive index of the low refractive index layer LR is less than the refractive index of the transparent substrate CP and the refractive index of the light emitting element VHOE.

[0058] The transparent substrate CP can be made of a transparent substrate with a refractive index of 1.5. Each of the light emitting element VHOE and the light incident element CHOE can be made of a transparent holographic film. The refractive index of the holographic film can be equal to or slightly greater than the refractive index of the transparent substrate CP. In the embodiments disclosed herein, for ease of explanation, it is assumed that the refractive index of each of the light emitting element VHOE and the light incident element CHOE is equal to the refractive index of the transparent substrate CP. Preferably but not necessarily, the refractive index of the low refractive index layer LR is similar to the refractive index of the fingerprint IM to be recognized (i.e., human skin). For example, the low refractive index layer LR can have a refractive index of about 1.4, which is close to the refractive index of human skin "1.39".

[0059] Preferably but not necessarily, the light source LS provides highly collimated light like a laser. The collimated light provided by the light source LS is the incident light 100, and the incident light 100 has a predetermined cross-sectional area and irradiates an incident point IP defined on the light incident element CHOE. The incident light 100 can be incident on the surface of the incident point IP along the normal direction. However, the embodiments are not limited thereto. For example, if necessary or desirable, the incident light 100 can be incident at an angle inclined with respect to the normal of the surface of the incident point IP.

[0060] The light incident element CHOE refracts the incident light 100 into the traveling light 200 at an incident angle and sends the traveling light 200 into the interior of the transparent substrate CP. Preferably but not necessarily, the incident angle is greater than the critical angle of total internal reflection inside the transparent substrate CP. As a result, the traveling light 200 travels along the X-axis direction corresponding to the length direction of the transparent substrate CP while undergoing total internal reflection inside the transparent substrate CP. Since the light from the light source LS undergoes total internal reflection inside the transparent substrate CP, even if the light is in the visible band, the light from the light source LS cannot be seen from the outside.

[0061] The light emitting element VHOE converts a part of the traveling light 200 into the outgoing light 300 and refracts the outgoing light 300 toward the front surface of the transparent substrate CP. The remaining part of the traveling light 200 undergoes total internal reflection and travels inside the transparent substrate CP. The outgoing light 300 undergoes total internal reflection at the front surface of the transparent substrate CP, but passes through the low refractive index layer LR at the rear surface of the transparent substrate CP. The detection light (or "sensing light") 400 passing through the rear surface of the transparent substrate CP travels toward the display panel DPNL.

[0062] The amount of the emitted light 300 is determined according to the light efficiency of the light-emitting element VHOE. For example, when the light efficiency of the light-emitting element VHOE is 3%, in the first light-emitting region where the traveling light 200 first contacts the light-emitting element VHOE, 3% of the incident light 100 is emitted as the emitted light 300. In addition, 97% of the incident light 100, which is the incident light of the traveling light 200, continues to be totally reflected and travels. After that, in the second light-emitting region, 2.91% of the incident light 100 (which is equal to 3% of the remaining 97% of the incident light 100) is emitted as the emitted light 300.

[0063] The emitted light 300 passes through the rear surface of the transparent substrate CP until the emitted light 300 reaches the far side of the transparent substrate CP opposite to the light source LS. In order to provide a predetermined amount of the emitted light 300 while the traveling light 200 travels within the transparent substrate CP, preferably but not necessarily, the light efficiency of the light-emitting element VHOE is specified to gradually increase exponentially.

[0064] When observed in the XZ plane (or referred to as the "vertical plane") including the longitudinal axis and the thickness direction axis, the traveling light 200 remains collimated when the incident light 100 has been collimated. On the other hand, preferably but not necessarily, the traveling light 200 has Figure 1 a diffusion angle φ in the XY plane (or referred to as the "horizontal plane") including the longitudinal axis and the width direction axis. This is to set the image detection region corresponding to the region of the transparent substrate CP. For example, preferably but not necessarily, if possible, the light-emitting element VHOE is set to correspond to the entire region of the light output part LOT. In addition, preferably but not necessarily, the diffusion angle φ is equal to or greater than the interior angle between two line segments connecting the incident point IP to the two end points P1 and P2 on the other side of the transparent substrate CP opposite to the light-incident element CHOE.

[0065] The region where the light-incident element CHOE is provided can be defined as the light input part LIN. The region where the light-emitting element VHOE is provided can be defined as the light output part LOT. The light output part LOT can also be defined as the light traveling part where the light travels.

[0066] When the cross-sectional area of the collimated light provided by the light source LS is about 0.5 mm × 0.5 mm, the light-incident element CHOE can have a length corresponding to the width of the transparent substrate CP and a width of about 3 mm to 5 mm. The light-incident element CHOE can be provided across the width of the transparent substrate CP.

[0067] The incident light 100 from the light source LS enters the surface of the incident point IP on the light-incident element CHOE along the normal direction. The light-incident element CHOE converts the incident light 100 into the traveling light 200 refracted to have an incident angle θ. The traveling light 200 propagates within the transparent substrate CP.

[0068] Preferably but not necessarily, the incident angle θ of the traveling light 200 is greater than the total reflection critical angle T at the interface between the light-emitting element VHOE and the low refractive index layer LR. VHOE_LR . For example, when the refractive indices of the transparent substrate CP and the light-emitting element VHOE are 1.5 and the refractive index of the low refractive index layer LR is 1.4, the total reflection critical angle T at the interface between the light-emitting element VHOE and the low refractive index layer LR VHOE_LR is about 69°. Therefore, preferably but not necessarily, the incident angle θ is greater than 69°. For example, the incident angle θ can be set between 70° and 75°.

[0069] Since the front surface of the transparent substrate CP is in contact with the air layer AIR, the traveling light 200 is totally reflected at the front surface of the transparent substrate CP. This is because the total reflection critical angle T at the interface between the transparent substrate CP and the air layer AIR CP_AIR is about 41.4°. That is, as long as the incident angle θ is greater than the total reflection critical angle T at the interface between the light-emitting element VHOE and the low refractive index layer LR VHOE_LR , the incident angle θ is always greater than the total reflection critical angle T at the interface between the transparent substrate CP and the air layer AIR CP_AIR .

[0070] The light-emitting element VHOE converts a predetermined amount of the traveling light 200 into the outgoing light 300 having a reflection angle α and sends the outgoing light 300 back into the transparent substrate CP. The outgoing light 300 is the light for identifying the pattern of the fingerprint IM on the front (or upper) surface of the touch transparent substrate CP. When there is no fingerprint on the surface of the transparent substrate CP, the outgoing light 300 must be totally reflected at the front surface of the transparent substrate CP and propagate to the fingerprint sensor ISS provided below the directional light source device SLS. After the outgoing light 300 is totally reflected at the front surface of the transparent substrate CP, the outgoing light 300 serves as the detection light 400 and propagates below the directional light source device SLS. As Figure 2 shown, T CP_AIR < α < T VHOE_LR < θ. For example, the reflection angle α can be set between 45° and 55°, and the incident angle θ can be set between 70° and 75°.

[0071] As Figure 3As shown, the display panel DPNL can be disposed below the directional light source device SLS. The fingerprint sensor ISS can be attached to the rear surface of the display panel DPNL at a predetermined angle in an inclined manner. The predetermined angle can be appropriately set in consideration of the setting state of peripheral components. The fingerprint sensor ISS converts the light incident through the display panel DPNL into an electrical signal and outputs a fingerprint pattern image to the transparent substrate CP. The pixel array of the fingerprint sensor ISS includes light sensor pixels. The light sensor pixels include light detection elements such as photodiodes or phototransistors. The fingerprint sensor ISS can be attached to the display panel DPNL using an adhesive such as an optically clear adhesive (OCA), a pressure-sensitive adhesive (PSA), etc. However, the embodiment is not limited thereto.

[0072] The incident light 100 is converted into the traveling light 200 by the light incident element CHOE. The traveling light 200 is converted in such a manner that it has a diffusion angle φ in the XY plane which is a horizontal plane including the X axis as the longitudinal axis and the Y axis as the width direction axis. The traveling light 200 also maintains the original collimated state (where the incident light 100 has been collimated) in the XZ plane which is a vertical plane including the X axis as the longitudinal direction axis and the Z axis as the thickness direction axis.

[0073] Preferably but not necessarily, the diffusion angle φ is equal to or greater than the interior angle between two line segments connecting the incident point IP to two end points on the other side of the transparent substrate CP opposite to the light incident element CHOE. In this case, the traveling light 200 propagates within the transparent substrate CP while diffusing in a triangular shape having the diffusion angle φ. The outgoing light 300 is also set within the same range as the traveling light 200. As a result, the fingerprint sensing area SA can be selected within a triangular area that expands from the incident point IP at the diffusion angle φ. Figure 4 The circular shaded portion can be designated as the fingerprint sensing area SA. However, the embodiment is not limited thereto.

[0074] When the fingerprint sensing area SA is formed in the central portion of the display panel DPNL or in a part of the upper side of the display panel DPNL opposite to the light incident element CHOE, preferably but not necessarily, the amount of the outgoing light 300 has a maximum value in the fingerprint sensing area SA. For this purpose, the light efficiency of the light outgoing element VHOE can be designed as a function of position such that it has a maximum value in the portion corresponding to the fingerprint sensing area SA and a minimum value or a value close to zero in other portions.

[0075] When the fingerprint IM touches the transparent substrate CP, light is reflected from the front surface of the transparent substrate CP at the position of the valleys V of the fingerprint IM, passes through the light-emitting element VHOE and the low-refractive-index layer LR, and travels toward the display panel DPNL. Thus, the light can reach the fingerprint sensor ISS. On the other hand, since the light at the ridges R of the fingerprint IM touching the transparent substrate CP propagates through the human skin and goes to the outside, the light cannot reach the fingerprint sensor ISS.

[0076] The fingerprint sensor ISS converts the light reflected from the fingerprint IM into an electrical signal and detects the fingerprint pattern. The fingerprint sensor ISS amplifies the voltage output from each light sensor pixel and converts the amplified voltage into digital data. The fingerprint sensor ISS can convert the ridges R of the fingerprint IM into data with a white gray level and the valleys V of the fingerprint IM into data with a black gray level. Conversely, the fingerprint sensor ISS can convert the ridges R of the fingerprint IM into data with a black gray level and the valleys V of the fingerprint IM into data with a white gray level. A fingerprint recognition processor (not shown) executes a predetermined fingerprint authentication algorithm and compares the fingerprint pattern data detected in real time by the fingerprint sensor ISS with the previously stored user fingerprint pattern to authenticate the fingerprint.

[0077] The fingerprint sensor ISS is arranged such that the light-receiving surface of the fingerprint sensor ISS points to the fingerprint sensing area SA. The display device according to an embodiment of the present disclosure can display an image indicating the position of the fingerprint sensing area SA on the screen AA, so that the user can easily know the position of the fingerprint sensing area SA when fingerprint recognition is required.

[0078] The light-emitting element VHOE and the low-refractive-index layer LR are provided on the display panel DPNL. The low-refractive-index layer LR can be attached to the display panel DPNL using an optically transparent adhesive. The light sensor pixels of the fingerprint sensor ISS are located opposite to the transparent substrate CP, the light-emitting element VHOE, and the low-refractive-index layer LR of the directional light source device SLS.

[0079] As Figure 6 shown, an embodiment of the present disclosure can use the pixels of the display panel DPNL as the fingerprint sensing light source. An embodiment of the present disclosure can implement a fingerprint sensor integrated with the display panel DPNL without the above-mentioned directional light source device SLS.

[0080] Referring to Figure 6 , the front surface of the display panel DPNL can be covered with the transparent substrate CP. The user's fingerprint can touch the transparent substrate CP on the screen AA of the display panel DPNL.

[0081] The pixel array of the display panel DPNL includes a plurality of data lines, a plurality of gate lines intersecting the data lines, and display pixels PIX arranged in a matrix. Each display pixel PIX may include a red sub-pixel, a green sub-pixel, and a blue sub-pixel for color implementation. Each display pixel PIX may also include a white sub-pixel. Each sub-pixel may include a light-emitting element such as an organic light-emitting diode (OLED).

[0082] The fingerprint sensor ISS is attached to the rear surface of the display panel DPNL at a position overlapping the fingerprint sensing area SA, such that the fingerprint sensor ISS faces the fingerprint sensing area SA on the screen AA of the display panel DPNL. A foam pad and a metal layer may be attached to the rear surface of the display panel DPNL. In order to increase the light reception efficiency of the fingerprint sensor ISS and reduce the thickness of the display device, the fingerprint sensor ISS may be directly attached to the rear surface of the display panel DPNL exposed by the holes of the foam pad and the metal layer.

[0083] When an event requiring fingerprint recognition occurs, the pixels PIX of the fingerprint sensing area SA emit light. The light from the pixels PIX is reflected from the ridges R of the touch transparent substrate CP of the fingerprint IM and received by the light sensor pixels of the fingerprint sensor ISS. On the other hand, the light from the pixels PIX passes through the valleys V of the fingerprint IM and is difficult to be reflected. Each light sensor pixel of the fingerprint sensor ISS uses a light sensor that converts light into an electrical signal to convert the light reflected from the valleys V of the fingerprint IM into a voltage, amplifies the voltage, and converts the amplified voltage into digital data. The fingerprint recognition processor executes a predetermined fingerprint authentication algorithm and compares the fingerprint pattern data detected in real time by the fingerprint sensor ISS with the previously stored user fingerprint pattern, thereby authenticating the fingerprint.

[0084] Figure 5 and Figure 6 The display panel DPNL and the fingerprint sensor ISS shown in Figure 7 or 8 may have the structure in a mobile information terminal

[0085] Referring to Figure 7 , a mobile information terminal according to an embodiment of the present disclosure includes a display panel DPNL for displaying an image on a display screen AA, a fingerprint sensor ISS attached to the display panel DPNL, and a driver integrated circuit (IC) 25 for driving the display panel DPNL. A transparent substrate CP is disposed on the display panel DPNL.

[0086] The fingerprint of a user can touch the front surface of the transparent substrate CP. The fingerprint sensor ISS is coupled to the display panel DPNL to sense light reflected from a fingerprint on the display area of the display panel DPNL. The light reflected from the fingerprint is incident on the fingerprint sensor ISS through the display panel DPNL. The fingerprint sensor ISS is disposed opposite to the fingerprint touch surface (i.e., the front surface of the transparent substrate CP), and the display panel DPNL is interposed between the fingerprint sensor ISS and the fingerprint touch surface. The fingerprint sensor ISS detects the light reflected from the fingerprint of the user and outputs a fingerprint pattern image. Thus, the fingerprint touch operation and the fingerprint pattern detection operation are performed on opposite sides of the display panel DPNL.

[0087] The display panel DPNL may be a flexible display panel of a flexible display device such as a plastic OLED display. However, the embodiment is not limited thereto. In the case of a plastic OLED display, the display panel DPNL includes a backplane 19, an organic thin film 17 attached to the backplane 19, a display area 16 formed on the organic thin film 17, a touch sensor array 15 disposed on the display area 16, and a polarizing film 14 attached to the touch sensor array 15. The display area 16 includes a pixel array for displaying an image.

[0088] The polarizing film 14 blocks external light from being reflected at the display panel DPNL and improves outdoor visibility. The polarizing film 14 may include a circular polarizer (or λ / 4 plate). The polarizing film 14 is attached to the transparent substrate CP by an adhesive 13 (e.g., an optically clear adhesive (OCA)).

[0089] The backplane 19 may be a polyethylene terephthalate (PET) substrate. However, the embodiment is not limited thereto. The backplane 19 prevents the display area 16 from being exposed to moisture or humidity and supports the display area 16. The organic thin film 17 may be a thin polyimide (PI) film substrate. A multilayer buffer layer (not shown) made of an insulating material may be formed on the organic thin film 17. A plurality of lines for supplying power or signals to the display area 16 and the touch sensor array 15 may be formed on the organic thin film 17.

[0090] The display area 16 includes data lines, gate lines intersecting the data lines, and pixels arranged in a matrix. The display area 16 is a screen for displaying an input image. Each pixel includes a light-emitting element. For example, each pixel may include an OLED and a driving circuit of the OLED. The data lines of the display area 16 are connected to a driver IC 25 and receive data signals from the driver IC 25. The touch sensor array 15 is driven by a touch sensor driver to sense touch inputs. The touch sensor array 15 sends the coordinates and identification (ID) codes of each touch input to a host system.

[0091] The fingerprint sensor ISS is mounted on the first flexible printed circuit board FPCB1. Since the fingerprint sensor ISS is disposed below the display area 16, the fingerprint sensor ISS does not affect the size of the bezel of the display device without changing the structure of the display panel DPNL and can sense fingerprint patterns. Each of the first flexible printed circuit board FPCB1 and the second flexible printed circuit board FPCB2 can be selected from a flexible printed circuit board (FPCB), a flexible flat cable (FFC), and a flexible printed circuit (FPC).

[0092] The driver IC 25 can be mounted on the second flexible printed circuit board FPCB2. The driver IC25 in the mobile information terminal includes a data driver for providing a data signal to the data lines of the display panel DPNL, a gate driver for providing a gate signal (or a scan signal) to the gate lines (or called "scan lines") of the display panel DPNL, and a timing controller for controlling the operation timing of the data driver and the gate driver. The driver IC 25 writes the data of the input image received from the host system into the pixels of the display panel DPNL. The host system is connected to the fingerprint sensor ISS via the first flexible printed circuit board FPCB1 and to the display panel driving circuit via the second flexible printed circuit board FPCB2. The host system can be an application processor (AP) in the mobile information terminal. However, the embodiments are not limited thereto.

[0093] The foam pad 20 and the metal layer 21 can be laminated on the back plate 19 of the display panel DPNL. The foam pad 20 can be made of a foam resin and absorb vibration or shock. The metal layer 21 can be made of a metal (e.g., copper (Cu)) that shields electromagnetic interference (EMI).

[0094] Each of the foam pad 20 and the metal layer 21 has a hole 30 that exposes the back plate 19, so that the fingerprint sensor ISS is attached to the back plate 19. The fingerprint sensor ISS is disposed in the hole 30. The light receiving portion of the fingerprint sensor module is adhered to the back plate 19 with an adhesive 22. The adhesive 22 can be an optically clear adhesive (OCA), a pressure sensitive adhesive (PSA), etc. The middle frame 27 can have a hole for exposing the hole into which the fingerprint sensor ISS is inserted.

[0095] Since the fingerprint sensor ISS is embedded in the holes of the foam pad 20 and the metal layer 21, the distance between the fingerprint on the transparent substrate CP and the fingerprint sensor ISS can be reduced. The structure in which the fingerprint sensor ISS is embedded can improve the light receiving efficiency of the fingerprint sensor ISS and improve the fingerprint sensing performance.

[0096] The middle frame 27 houses the display panel DPNL, the fingerprint sensor ISS, the driver IC 25, etc. The upper sidewall of the middle frame 27 can be attached to the transparent substrate CP using double-sided tape 28. The decorative film 12 can be attached to the transparent substrate CP. Pictures, texts, etc. can be printed on the decorative film 12. One side of the organic film 17 is bent to the rear surface of the display panel DPNL and connected to one end of the second flexible circuit board FPCB2. The mandrel 18 is attached to the side surface of the backplate 19 and the side surface of the foam pad 20 and supports the bent portion of the organic film 17.

[0097] The display panel DPNL can be implemented as an OLED display panel provided on a glass substrate. In this case, the backplate 19 and the organic film 17 can be replaced by a single glass substrate.

[0098] Except that the fingerprint sensor ISS is attached to the foam pad 20, Figure 8 the configuration is the same as Figure 7 that of Figure 8 In the configuration of

[0099] The pixel array of the display panel DPNL and the pixel array of the fingerprint sensor ISS each include a plurality of lines spaced at regular intervals. Therefore, when the display panel DPNL and the fingerprint sensor ISS overlap each other, due to the overlap of the periodic patterns, moiré fringe interference can be seen. For example, when the fingerprint sensor ISS is attached to the display panel DPNL at 90° as Figure 9A shown, due to the interference between the fingerprint sensor ISS and the display panel DPNL, moiré fringe interference that cannot be seen when only the fingerprint sensor ISS is present can appear in the form of stripes, as Figure 9B shown. When Figure 9B the moiré fringe interference shown covers the fingerprint pattern image output from the fingerprint sensor ISS, it is difficult to recognize the fingerprint pattern. This results in a reduction in the fingerprint recognition rate.

[0100] In Figure 9AIn this case, "REF" is a virtual attachment reference line parallel to the long axis X of the display panel DPNL. "Aiss" is a virtual sensor attachment direction line that passes through the center of the fingerprint sensor ISS and the center of the width W of the first flexible printed circuit board FPCB1 and intersects the virtual attachment reference line REF. Terminals on one side of the first flexible printed circuit board FPCB1 are connected to the terminals of the fingerprint sensor ISS, and terminals on the other side of the first flexible printed circuit board FPCB1 are connected to the terminals of a host system (not shown). The fingerprint sensor ISS is connected to the host system through the first flexible printed circuit board FPCB1. As described above, the first flexible printed circuit board FPCB1, which can be selected from among a flexible printed circuit board (FPCB), a flexible flat cable (FFC), and a flexible printed circuit (FPC), is a circuit component that electrically connects the fingerprint sensor ISS to the host system. In the embodiments disclosed herein, the first flexible printed circuit board FPCB1 is denoted by the reference numeral "FPCB", but is not limited to a flexible printed circuit board FPCB.

[0101] Embodiments of the present disclosure prevent moiré interference by setting the attachment angle of the fingerprint sensor ISS to the display panel DPNL to a predetermined angle. For example, the predetermined angle can be set to be about 20° to 45° with respect to a reference line REF parallel to the long axis of the display panel DPNL. The attachment angle indicates the angle between the fingerprint sensor ISS and the display panel DPNL when the display panel DPNL is set at 0° (i.e., when the attachment reference line REF is not tilted and is at 0°). For example, when the attachment reference line REF and the sensor attachment direction line Aiss coincide with each other, the attachment angle is 0°. That is, the attachment angle can be measured as the angle between the attachment reference line REF and the sensor attachment direction line Aiss.

[0102] Figure 10A An example in which the attachment angle of the fingerprint sensor ISS to the display panel DPNL is 45° is illustrated. Figure 10B An example of the output image of the fingerprint sensor ISS when the attachment angle is 45° is illustrated. Figure 11A An example in which the attachment angle of the fingerprint sensor ISS to the display panel DPNL is 20° is illustrated. Figure 11B An example of the output image of the fingerprint sensor ISS when the attachment angle is 20° is illustrated.

[0103] Referring to Figures 10A to 11B , when the attachment angle of the fingerprint sensor ISS to the display panel DPNL is 25° to 45°, an image without moiré interference can be obtained from the fingerprint sensor ISS. When the attachment angle of the fingerprint sensor ISS to the display panel DPNL is 45°, the clearest image without moiré interference can be obtained.

[0104] The length of the short direction Y occupied by the fingerprint sensor ISS and the first flexible printed circuit board FPCB1 at an attachment angle of 45° is longer than that at an attachment angle of 20°. Therefore, in the case of a mobile information terminal that needs to reduce the length of the display panel DPNL in the short direction Y, the attachment angle of the fingerprint sensor ISS to the display panel DPNL can be reduced to 20° or an angle close to 20°.

[0105] Figure 12 is a plan view schematically illustrating the structure of the fingerprint sensor ISS. Figure 13A and Figure 13B is a plan view illustrating the structure of the first flexible printed circuit board FPCB1.

[0106] Referring to Figures 12 to 13B , the fingerprint sensor ISS includes a semiconductor chip 232 formed with a photosensor pixel array 231 and a mold 233 that seals the semiconductor chip 232. The fingerprint sensor ISS can be implemented as a sensor package. Metal wires are disposed on the semiconductor chip 232 in a manner that connects the photosensor pixel array 231 to the terminals of the first flexible printed circuit board FPCB1.

[0107] The first flexible printed circuit board FPCB1 includes a sensor mounting portion 241 on which the fingerprint sensor ISS is mounted and a tail portion 242 that connects the sensor mounting portion 241 to Figure 14 and Figure 15 the main board shown in. The sensor mounting portion 241 can be formed in a rectangular shape, but is not limited thereto. The width of the tail portion 242 is smaller than the width of the sensor mounting portion 241. The tail portion 242 can be connected to one side of the sensor mounting portion 241, or can be connected to both sides of the sensor mounting portion 241, as shown in Figure 19A and Figure 19B . Both the sensor mounting portion 241 and the tail portion 242 include wires that connect the fingerprint sensor ISS to the main board. The tail portion 242 includes terminals of a connector that are connected to the main board at one end of the tail portion 242.

[0108] The tail portion 242 can be formed in a straight shape as shown in Figure 13A , or can be formed in a shape bent at a predetermined angle as shown in Figure 13B . When the tail portion 242 is bent at a predetermined angle, the tail portion 242 includes a first tail portion 242a located close to the sensor mounting portion 241 and a second tail portion 242b that is bent at a predetermined angle from the first tail portion 242a and is connected to the main board. The tail portion 242 can include N (N is a positive integer equal to or greater than 2) sub-tail portions that are connected to each other at arbitrary predetermined angles and are bent in various shapes in consideration of the arrangement of peripheral components.

[0109] Figure 14 andFigure 15 Schematically illustrates a mobile information terminal according to an embodiment of the present disclosure. More specifically, Figure 14 and Figure 15 Illustrates by way of example a mobile information terminal having a full touch screen structure. However, the embodiment is not limited thereto.

[0110] Referring to Figure 14 and Figure 15 , a mobile information terminal according to an embodiment of the present disclosure includes a display panel DPNL, a front cover 101, a rear cover 103, an intermediate frame 27, a main board 104, a battery 105, etc. In the embodiments disclosed herein, the "cover" may be expressed as a housing and a casing.

[0111] The front surface of the display panel DPNL may be covered by a transparent substrate CP. The transparent substrate CP may be implemented as tempered glass. The front cover 101 covers the edges of the display panel DPNL and the transparent substrate CP. A front camera and various sensors may be provided on the front surface of the mobile information terminal. A rear camera and various sensors may be provided on the rear surface of the mobile information terminal. The sensors include various sensors suitable for the mobile information terminal, such as a proximity sensor, a gyro sensor, a magnetic sensor, a motion sensor, an illuminance sensor, an RGB sensor, a Hall sensor, a temperature / humidity sensor, a heart rate sensor, a fingerprint scan sensor, etc.

[0112] An audio video (AV) input unit, a user input unit, a speaker, a microphone, etc. are mounted on the front cover 101 and the rear cover 103. The AV input unit, the user input unit, the speaker, and the microphone are connected to the main board 104.

[0113] The display panel DPNL, the intermediate frame 27, the main board 104, the battery 105, etc. are disposed between the front cover 101 and the rear cover 103. The intermediate frame 27 supports the display panel DPNL and spatially separates the display panel DPNL and the main board 104. A driver IC 25 for driving the display panel DPNL is connected to a second flexible circuit board FPCB2. A fingerprint sensor ISS and a first flexible circuit board FPCB1 are disposed on the rear surface of the display panel DPNL. The first flexible circuit board FPCB1 and the second flexible circuit board FPCB2 are connected to the main board 104.

[0114] The main board 104 is connected to the driver IC 25 and the fingerprint sensor ISS through the first flexible printed circuit board FPCB1 and the second flexible printed circuit board FPCB2. Although not shown, the main board 104 may include a wireless communication module, a short-range communication module, a mobile communication module, a broadcast receiving module, an AV input unit, a global positioning system (GPS) module, a power circuit, etc. A user input unit, a speaker, a microphone, a battery 105, etc. are connected to the main board 104. The power circuit removes noise from the voltage of the battery 105 and appropriately adjusts the voltage of the battery 105 to generate power for driving the circuits on the main board 104, the driver IC 25, and the fingerprint sensor ISS. In the mobile information terminal, the main board 104 includes a host system as an application processor (AP). The application processor may send image data to the driver IC 25 via the Mobile Industry Processor Interface (MIPI).

[0115] As Figure 15 and Figure 16 shown, the main board 104 may be formed on a film substrate that does not overlap with the battery 105, but is not limited thereto. To reduce the thickness of the mobile information terminal, as Figure 16 and Figure 17 shown, the battery 105 may have a groove 106 that houses at least a part of the first flexible printed circuit board FPCB1 on which the fingerprint sensor ISS is mounted.

[0116] Figures 18A to 21B Illustrates various methods of setting the fingerprint sensor and the first flexible printed circuit board according to an embodiment of the present disclosure.

[0117] Referring to Figure 18A and Figure 18B , the attachment angle of each of the fingerprint sensor ISS and the sensor mounting portion 241 of the first flexible printed circuit board FPCB1 may be 20° to 45°. In this case, a second virtual attachment reference line REF2 parallel to the virtual attachment reference line REF is set at 0°, and the attachment angle of each of the fingerprint sensor ISS and the sensor mounting portion 241 of the first flexible printed circuit board FPCB1 with respect to the second attachment reference line REF2 is 20° to 45°. The second virtual attachment reference line REF2 may be substantially the same as the above-mentioned virtual attachment reference line REF.

[0118] The tail 242 of the first flexible printed circuit board FPCB1 includes a first tail 242a and a second tail 242b. The first tail 242a is connected to the sensor mounting portion 241 and extends from the sensor mounting portion 241 at an angle of 20° to 45° with respect to the second attachment reference line REF2. The second tail 242b is bent from the first tail 242a at a small angle of 110° to 135°. When the second attachment reference line REF2 is set at 0°, the direction of the long axis of the second tail 242b is perpendicular (i.e., 90°) to the second attachment reference line REF2.

[0119] Referring Figure 19A and Figure 19B , the attachment angle of each of the fingerprint sensor ISS and the sensor mounting portion 241 of the first flexible printed circuit board FPCB1 can be 20° to 45°. In this case, the second virtual attachment reference line REF2 parallel to the virtual attachment reference line REF is at 0°, and the connection angle of each of the fingerprint sensor ISS and the sensor mounting portion 241 of the first flexible printed circuit board FPCB1 with respect to the second attachment reference line REF2 is 20° to 45°.

[0120] The tail 242 of the first flexible printed circuit board FPCB1 is connected to the sensor mounting portion 241 and is bent from the sensor mounting portion 241 at a small angle of 110° to 135°. When the second attachment reference line REF2 is set at 0°, the direction of the long axis of the second tail 242b is perpendicular (i.e., 90°) to the second attachment reference line REF2.

[0121] Referring Figure 20A and Figure 20B , the attachment angle θ i of the fingerprint sensor ISS can be 20° to 45°. The attachment angle of the sensor mounting portion 241 of the first flexible printed circuit board FPCB1 is 0° parallel to the second virtual attachment reference line REF2. Therefore, the attachment angle θ i of the fingerprint sensor ISS on the sensor mounting portion 241 of the first flexible printed circuit board FPCB1 can be 20° to 45°.

[0122] The tail portion 242 of the first flexible printed circuit board FPCB1 includes a first tail portion 242a and a second tail portion 242b. The first tail portion 242a is connected to the sensor mounting portion 241 and is arranged parallel to the second attachment reference line REF2. The second tail portion 242b is bent from the first tail portion 242a at a small angle of 90°. The direction of the long axis of the second tail portion 242b is perpendicular (i.e., 90°) to the second attachment reference line REF2. The boundary line BL between the sensor mounting portion 241 and the first tail portion 242a is a dashed line perpendicular (i.e., 90°) to the second attachment reference line REF2. The fingerprint sensor ISS can be mounted on the sensor mounting portion 241 of the first flexible printed circuit board FPCB1 at an angle inclined by 20° to 45° with respect to the demarcation line BL.

[0123] Referring to Figure 21A and Figure 21B , the attachment angle θ of the fingerprint sensor ISS i can be 20° to 45°. One side of the sensor mounting portion 241 of the first flexible printed circuit board FPCB1 is set at 0° parallel to the second virtual attachment reference line REF2. Therefore, the attachment angle θ of the fingerprint sensor ISS on the sensor mounting portion 241 of the first flexible printed circuit board FPCB1 i can be 20° to 45°.

[0124] The tail portion 242 of the first flexible printed circuit board FPCB1 is connected to the sensor mounting portion 241 and extends at a right angle to the second attachment reference line REF2. The direction of the long axis of the tail portion 242 is perpendicular (i.e., 90°) to the second attachment reference line REF2. The boundary line BL between the sensor mounting portion 241 and the tail portion 242 is a dashed line parallel (i.e., 0°) to the second attachment reference line REF2.

[0125] The fingerprint sensor ISS can be mounted on the sensor mounting portion 241 at an angle inclined by 20° to 45° with respect to the sensor mounting portion 241.

[0126] Figure 22 Schematically illustrated is the pixel array of a display panel and the pixel array of a fingerprint sensor according to an embodiment of the present disclosure.

[0127] As Figure 22As shown, when the light sensor pixels PIX2 of the fingerprint sensor ISS are unevenly arranged, moiré interference can be prevented. When the display pixels PIX1 of the display panel DPNL and the light sensor pixels PIX2 of the fingerprint sensor ISS overlap each other periodically, moiré interference can be clearly seen. When the light sensor pixels PIX2 of the fingerprint sensor ISS are unevenly arranged, the metal lines of the pixel array of the fingerprint sensor ISS are unevenly arranged on the semiconductor chip. Therefore, even when the display pixels PIX1 of the display panel DPNL and the light sensor pixels PIX2 of the fingerprint sensor ISS overlap each other, the periodicity disappears. As a result, moiré interference is not seen. This embodiment can be applied to the above-described embodiments of the present disclosure.

[0128] As described above, the embodiments of the present disclosure detect a fingerprint pattern at the opposite side of the fingerprint touch surface that comes into contact with the user's fingerprint, and thus can sense the user's fingerprint on the screen of the displayed image. The embodiments of the present disclosure can prevent moiré interference by optimizing the attachment angle of the fingerprint sensor to the display panel.

[0129] Embodiments of the present invention form holes in the metal layer and the foam pad, and dispose the fingerprint sensor in the holes, thus ensuring an optical path between the transparent substrate in contact with the fingerprint and the fingerprint sensor and implementing a thin display device.

[0130] Although embodiments have been described with reference to a number of exemplary embodiments, it should be understood that those skilled in the art can design many other modifications and embodiments that fall within the scope of the principles of the present disclosure. More specifically, various changes and modifications can be made to the components and / or arrangements of the subject combination arrangement within the scope of the present disclosure, the drawings, and the appended claims. In addition to the changes and modifications to the components and / or arrangements, alternative uses will also be apparent to those skilled in the art.

[0131] This application claims the benefit of Korean Patent Application No. 10-2017-0115862, filed on September 11, 2017, the entire contents of which are incorporated herein by reference for all purposes as if fully set forth herein.

Claims

1. A display device, the display device comprises: a display panel configured to receive a touch of a user's finger on a display area of the display panel; a fingerprint sensor coupled to the display panel, the fingerprint sensor configured to sense light reflected from a fingerprint of the user's finger, wherein the light reflected from the fingerprint passes through the display panel and is incident on the fingerprint sensor; and a foam pad and a metal layer, the foam pad and the metal layer disposed on a rear surface of the display panel coupled to the fingerprint sensor, wherein the fingerprint sensor is disposed in a hole of the metal layer or the fingerprint sensor is disposed in holes of the metal layer and the foam pad, and wherein the fingerprint sensor is attached to the display panel obliquely at a predetermined angle with respect to a reference line parallel to a long axis of the display panel, wherein a screen of the display panel includes a plurality of display pixels, wherein the fingerprint sensor includes a plurality of light sensor pixels, wherein light from the display pixels is reflected from a fingerprint of the touch transparent substrate of the user's finger and received by the light sensor pixels of the fingerprint sensor.

2. The display device according to claim 1, wherein, the predetermined angle is an angle of 20° to 45° with respect to the reference line.

3. The display device according to claim 1, the display device further comprising a flexible circuit board, the fingerprint sensor being mounted on the flexible circuit board, wherein, the flexible circuit board includes: a sensor mounting portion on which the fingerprint sensor is mounted; and a tail connected to the sensor mounting portion.

4. The display device according to claim 3, wherein, an attachment direction line of the fingerprint sensor passes through a center of the fingerprint sensor and a center in a width direction of the flexible circuit board and intersects with the reference line, wherein an angle of the attachment direction line of the fingerprint sensor with respect to the reference line is 20° to 45°.

5. The display device according to claim 3, wherein, the tail of the flexible circuit board includes: a first tail located close to the sensor mounting portion; and a second tail bent from the first tail at a predetermined angle.

6. The display device according to claim 5, wherein, the sensor mounting portion of the flexible circuit board and the fingerprint sensor are disposed at an angle of 20° to 45° with respect to the reference line, wherein the first tail is connected to the sensor mounting portion and extends at an angle of 20° to 45° with respect to the reference line, wherein the second tail is bent from the first tail at an angle of 110° to 135°.

7. The display device according to claim 3, wherein, the sensor mounting portion of the flexible circuit board and the fingerprint sensor are disposed at an angle of 20° to 45° with respect to the reference line, wherein the tail is connected to the sensor mounting portion and is bent from the sensor mounting portion at an angle of 110° to 135°.

8. The display device according to claim 5, wherein, The sensor mounting portion of the flexible circuit board and the fingerprint sensor are disposed at an angle of 20° to 45° with respect to the reference line. Wherein, the first tail extends parallel to the reference line. Wherein, the second tail bends at an angle of 90° from the first tail.

9. The display device according to claim 3. Wherein, The fingerprint sensor is disposed at an angle of 20° to 45° with respect to the reference line. Wherein, one side of the sensor mounting portion of the flexible circuit board is parallel to the reference line. Wherein, the major axis of the tail of the flexible circuit board is perpendicular to the reference line.

10. The display device according to any one of claims 1 to 9. Wherein, The fingerprint sensor is attached to the rear surface of the display panel at a position overlapping with the fingerprint sensing area, such that the fingerprint sensor faces the fingerprint sensing area on the screen of the display panel. Wherein, when an event requiring fingerprint recognition occurs, the display pixels of the fingerprint sensing area emit light.

11. A mobile information terminal, the mobile information terminal comprising: A display panel configured to receive a touch of a user's finger on a display area of the display panel. A fingerprint sensor coupled to the display panel, the fingerprint sensor configured to sense light reflected from a fingerprint of the user's finger, wherein the light reflected from the fingerprint passes through the display panel and is incident on the fingerprint sensor. A foam pad and a metal layer, the foam pad and the metal layer being disposed on a rear surface of the display panel coupled to the fingerprint sensor. A main board connected to the fingerprint sensor; and A battery connected to the main board. Wherein, the fingerprint sensor is disposed in a hole of the metal layer or the fingerprint sensor is disposed in holes of the metal layer and the foam pad. Wherein, the fingerprint sensor is attached to the display panel obliquely at a predetermined angle with respect to a reference line parallel to the major axis of the display panel. Wherein, the screen of the display panel includes a plurality of display pixels. Wherein, the fingerprint sensor includes a plurality of light sensor pixels. Wherein, light from the display pixels is reflected from a fingerprint of the touch transparent substrate of the user's finger and received by the light sensor pixels of the fingerprint sensor.

12. The mobile information terminal according to claim 11. Wherein, The predetermined angle is an angle of 20° to 45° with respect to the reference line.

13. The mobile information terminal according to claim 11 or 12. Wherein, The fingerprint sensor is attached to the rear surface of the display panel at a position overlapping with the fingerprint sensing area, such that the fingerprint sensor faces the fingerprint sensing area on the screen of the display panel. Wherein, when an event requiring fingerprint recognition occurs, the display pixels of the fingerprint sensing area emit light.

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