TWI656452B - Display device - Google Patents

Abstract

The present invention discloses a display device comprising: a display panel disposed to be positioned under a transparent substrate and displaying an image on a display area toward the transparent substrate; a fingerprint sensor located below the display panel for detecting a fingerprint in contact with the transparent substrate; and a driving integrated circuit (drive IC) configured to drive the display panel.

Description

 Display device  

Embodiments of the present invention relate to a display device having a fingerprint sensor on a screen.

With advances in computer technology, computer-based systems for various purposes such as notebook computers, tablet computers, smart phones, personal digital assistants, automated teller machines, search and guidance systems have been developed. These systems typically store large amounts of confidential information, such as business information or trade secrets, as well as personal information about an individual's private life, and there is a need to enhance security.

For this reason, in the conventional technology, a method of enhancing security by using a sensor for sensing biological information has been proposed. One known example is a fingerprint sensor that can be enhanced by a fingerprint registration or authentication system. A fingerprint sensor is a sensor that detects human fingerprints. The fingerprint sensor can be divided into an optical fingerprint sensor, a capacitive fingerprint sensor, an ultrasonic sensor, and the like.

Typically, the fingerprint sensor is placed in a specific area outside the screen, such as a main screen button. The fingerprint sensor can be placed in the bezel area outside the screen, in which case the bezel area is wider. The structure of the display panel can be altered to place a fingerprint sensor on the display panel.

The fingerprint sensor can be placed on a liquid crystal display (LCD). When located between the display panel and the backlight unit (BLU), the fingerprint sensor is visible in the screen area. The cymbal in the backlight unit BLU has a plurality of air gaps due to its structure, which makes it difficult to place a fingerprint sensor, in particular an ultrasonic fingerprint sensor, under the display panel.

Accordingly, the present invention is directed to a display device having a fingerprint sensor capable of detecting a fingerprint on a screen without increasing the size of the bezel or changing the structure of the display panel.

An exemplary embodiment of the present invention provides a display device including: a transparent substrate; a display panel configured to be positioned under the transparent substrate and display an image on a display area toward the transparent substrate; a fingerprint sensor located below the display panel for detecting a fingerprint in contact with the transparent substrate, and a driving integrated circuit (drive IC) configured to drive the display panel.

11‧‧‧Transparent substrate

12‧‧‧Decorative film

13‧‧‧Binder

14‧‧‧ polarizing film

15‧‧‧Touch sensor array

16‧‧‧Pixel Array

17‧‧‧Organic film

18‧‧‧ mandrel

19‧‧‧ Backboard

20‧‧‧foam pad

21‧‧‧metal layer

22‧‧‧Binder

23‧‧‧Finger sensor

23a‧‧ lens

23b‧‧‧Receiving Department

23c‧‧‧ Sidewall

24‧‧‧First flexible substrate

24a‧‧‧ first side

24b‧‧‧ second side

24c‧‧‧Metal filler

24d‧‧‧Wiring

25‧‧‧Drive integrated circuit (drive IC)

26‧‧‧Second flexible substrate

27‧‧‧Intermediate framework

28‧‧‧Binder

29‧‧‧ gap

30‧‧‧ hole

31‧‧‧Light incident components

32‧‧‧Light emitting components

33‧‧‧Light source

40‧‧‧Double-sided tape

50‧‧‧Non-transparent film

111‧‧‧ Location of the fingerprint sensor on the screen

112‧‧‧ Display the location of the fingerprint sensor on the screen

113‧‧‧The vicinity of the fingerprint sensor

100‧‧‧Injected beam

150‧‧‧Media

152‧‧‧ air layer

200‧‧‧Traveling beam

300‧‧‧shot beam

400‧‧‧Detection beam (or sensing beam)

SLS‧‧‧Directional light source unit

CHOE‧‧‧light injection components

IP‧‧‧ entry point

LS‧‧‧ light source

CP‧‧‧Transparent substrate

DP‧‧‧ display panel

VHOE‧‧‧ light emitting components

LR‧‧‧low refractive index layer

P1‧‧‧ endpoint

P2‧‧‧ endpoint

LIN‧‧‧Light Input Department

LOT‧‧‧Light Output Department

IM‧‧‧ fingerprint

AIR‧‧‧air

Φ‧‧‧ divergence angle

Θ‧‧‧incident angle

‧‧‧‧reflection angle

The accompanying drawings illustrate the embodiments of the invention, and, in the 1 is a cross-sectional view of a display device according to a first exemplary embodiment of the present invention; FIG. 2 is a cross-sectional view of a display device according to a second exemplary embodiment of the present invention; and FIG. 3 is a through hole formed in FIGS. 1 and 2. FIG. 4 is a cross-sectional view of a display device according to a third exemplary embodiment of the present invention; FIG. 5 is a cross-sectional view of a display device according to a fourth exemplary embodiment of the present invention; 6 is a cross-sectional view of a display device according to a fifth exemplary embodiment of the present invention; FIG. 7 is a cross-sectional view of a display device according to a sixth exemplary embodiment of the present invention; and FIG. 8 is a display device according to a seventh exemplary embodiment of the present invention. FIG. 9 is a cross-sectional view of a display device according to an eighth exemplary embodiment of the present invention; FIG. 10 is a view showing the first flexible substrate shown in FIGS. 8 and 9 connected to none according to the first exemplary embodiment of the present invention; through A cross-sectional view of an example of a motherboard of a host system; FIG. 11 is a plan view of a smartphone screen showing an example of a fingerprint sensor on a screen and a position for indicating a fingerprint sensor, in accordance with an exemplary embodiment of the present invention; An example of a user interface method; FIG. 12 is a cross-sectional view and a plan view illustrating a directional light source device according to an exemplary embodiment of the present invention; and FIG. 13 is a light in the transparent substrate shown in FIG. 12 according to an exemplary embodiment of the present invention. FIG. 14 is a cross-sectional view and a plan view illustrating a directional light source device on a display panel according to an exemplary embodiment of the present invention; FIG. 15 is a view of an ultrasonic path according to an exemplary embodiment of the present invention, the ultrasonic path Depending on the presence or absence of an air layer between the medium and the ultrasonic fingerprint sensor; FIG. 16 is a view of a lens for improving light receiving efficiency of an optical fingerprint sensor, according to an exemplary embodiment of the present invention; 17 is a view of a light path according to an exemplary embodiment of the present invention, which is based on a transparent substrate medium and optical fingerprint sensing in a directional light source device A schematic diagram of the presence or absence of an air layer between the devices; and Figures 18 through 21 are views of the non-transparent film.

A display device according to an exemplary embodiment of the present invention may be implemented based on a self-illuminating device such as an electroluminescent display. Electroluminescent light displays can be broadly classified into inorganic light emitting displays and organic light emitting displays. The pixel of the active matrix type organic light emitting display emits light using an organic light emitting diode (hereinafter referred to as "OLED").

The various aspects and features of the present invention, as well as the implementation thereof, may be more readily understood by reference to the detailed description and the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the illustrative embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

The shapes, dimensions, proportions, angles, numbers, and the like shown in the drawings for describing the exemplary embodiments of the present invention are merely examples, and are not limited to those shown in the drawings. Throughout the specification, the same reference numerals denote the same elements. In describing the present invention, a detailed description of the related art will be omitted to avoid unnecessarily obscuring the present invention. When the terms "comprising", "having", "consisting of", etc. are used, other portions may be added as long as the term "only" is not used. A singular form may be interpreted as a plural unless explicitly stated otherwise.

Even if not explicitly indicated herein, an element can be understood to include an error limit.

When terms such as "upper", "above", "below" and "adjacent" are used to describe a positional relationship between two components, one or more components may be disposed between the two components, as long as Use the terms "immediately" or "directly."

It should be understood that although the terms first, second, etc. may be used to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Therefore, the first requirement discussed below may be referred to as a second requirement without departing from the technical spirit of the present invention.

The same reference numerals are used throughout the specification to refer to the same elements.

Features of various example embodiments of the invention may be combined in part or in whole, and may interact or function together in a technically distinct manner. Example embodiments may be performed independently or in combination with one another.

Hereinafter, various exemplary embodiments of the present invention will be described in detail with reference to the drawings. In the following exemplary embodiments, an organic light emitting display as an example of an electroluminescent display will be described. However, it should be noted that the technical spirit of the present invention is not limited to an organic light emitting display, but can be applied to an inorganic light emitting display including an inorganic light emitting material.

1 is a cross-sectional view of a display device in accordance with a first exemplary embodiment of the present invention. All of the components of the display device in accordance with all embodiments of the present invention are operatively coupled and configured.

Referring to FIG. 1, a display device according to the present embodiment includes: a display panel (including components 14, 15, 16, 17, and 19) for displaying an image on a display area; a fingerprint sensor 23 located below the display panel, A fingerprint on the sensing display area; and a driving integrated circuit (hereinafter referred to as "IC") 25 for driving the display panel. A transparent substrate 11 covering the display area in contact with the fingerprint is disposed on the display panel. A fingerprint sensor 23 is disposed on the display area to detect a fingerprint pattern on the display area.

The fingerprint sensor 23 is located opposite the display panel. The fingerprint sensor 23 is disposed on a display panel in a side opposite to a contact position between the fingerprint of the user and the substrate.

The display panel can be, but is not limited to, a flexible display panel such as a flexible display device of a plastic OLED display. In a plastic OLED display, the display panel includes: a back sheet 19, an organic film 17 bonded to the back sheet 19, a display area formed on the organic film 17, a touch sensor array 15 disposed on the display area, and The polarizing film 14 is bonded to the touch sensor array 15. The display area is a screen containing a pixel array 16 that displays images.

The polarizing film 14 improves the outdoor definition by preventing external light reflection on the display panel. The polarizing film 14 may contain a circular polarizer (or a λ/4 plate). The polarizing film 14 is adhered to the transparent substrate 11 through a binder 13 (for example, an optically transparent adhesive OCA).

The back sheet 19 may be a polyethylene terephthalate (PET) substrate. The back sheet 19 prevents moisture from penetrating to keep the pixel array 16 from being exposed to moisture and supports the pixel array 16, and the organic film 17 may be a thin polyimide (PI) film substrate. A plurality of buffer layers as an insulating material may be formed on the organic film 17, which are not shown in the drawing. A wiring for supplying power or signals applied to the pixel array 16 and the touch sensor array 15 may be formed on the organic thin film 17.

The pixel array 16 includes a data line, a gate line crossing the data line, and pixels arranged in a matrix to form a screen for reproducing the input image. Each pixel contains a light emitting element. In one example, each pixel can include an OLED and circuitry for driving the OLED. The data lines on the pixel array 16 are connected to the drive IC 25 and receive data signals from the drive IC 25. The touch sensor array 15 is driven by the touch sensor driver to detect the touch input and transmit the coordinates and the identification code (ID) of each touch input to the host system.

The fingerprint sensor 23 is mounted on the first flexible substrate 24. The fingerprint sensor 23 can be implemented as an optical fingerprint sensor that detects a fingerprint pattern by using a difference in the amount of light reflected from the finger relief and the intaglio. The optical fingerprint sensor may include an image sensor such as a CCD (Charge Coupled Device) or a CIS (CMOS Image Sensor). When in the fingerprint recognition mode, the optical fingerprint sensor can detect the fingerprint pattern using light generated by the pixel array 16 that is projected toward the transparent substrate 11 and reflected from the fingerprint. The optical fingerprint sensor can detect a fingerprint pattern by using light received from a directional light source device SLS including the transparent substrate 11, instead of using a pixel as a light source.

The fingerprint sensor 23 can detect the fingerprint pattern by using an ultrasonic fingerprint sensor. The ultrasonic fingerprint sensor can detect the fingerprint pattern by transmitting an ultrasonic wave to the transparent substrate 11 using an ultrasonic transmitter and analyzing the ultrasonic waves reflected from the relief and the concave of the fingerprint.

Such a fingerprint sensor 23 is capable of detecting a fingerprint pattern without affecting the size of the bezel because it is located below the pixel array 16 without changing the structure of the display panel.

The receiving portion of the fingerprint sensor 23 is located opposite the display panel to face the transparent substrate 11. The receiving portion includes a detector plane that detects a fingerprint pattern. The fingerprint sensor 23 is bonded to the display panel such that the receiving portion of the fingerprint sensor 23 faces the transparent substrate 11. The presence of an air gap between the fingerprint sensor 23 and the display panel may significantly degrade sensor performance or disable fingerprint sensing. Therefore, the receiving portion of the fingerprint sensor 23 is bonded to the back sheet 19 of the display panel with the adhesive 22. The adhesive 22 may be an optically clear adhesive (OCA), a pressure sensitive adhesive (PSA), or the like.

The foam pad 20 and the metal layer 21 may be stacked on the back plate 19 of the display panel. The foam pad 20 is made of a foamed resin to absorb vibration or impact. The metal layer 21 is a metal layer that blocks electromagnetic interference (EMI), such as Cu.

A hole 30 exposing the backing plate 19 is formed in the foam pad 20 and the metal layer 21 such that the fingerprint sensor 23 is bonded to the backing plate 19. The fingerprint sensor 23 is placed within the aperture 30 with the receiving portion bonded to the backing plate 19. The intermediate frame 27 may have a hole that exposes the fingerprint sensor 23 inserted therein.

Since the fingerprint sensor 23 is buried in the holes 30 formed in the foam pad 20 and the metal layer 21, the distance between the fingerprint on the transparent substrate 11 and the fingerprint sensor 23 can be reduced. The buried structure of the fingerprint sensor 23 can improve the efficiency of ultrasonic or light reception, thereby improving fingerprint sensing performance.

The driver IC 25 drives the pixels by converting the data of the input image into data signals and outputting them to the data lines on the pixel array. The driver IC 25 can include a touch sensor driver. The drive IC 25 is mounted on the second flexible substrate 26.

One end of the first flexible substrate 24 is attached to the fingerprint sensor 23 on the inner side of the bottom of the intermediate frame 27. The other end of the first flexible substrate 24 is exposed to the outside of the bottom of the intermediate frame 27 through the first hole of the intermediate frame 27. The other end of the first flexible substrate 24 is connected to the second flexible substrate 26. Each of the first flexible substrate 24 and the second flexible substrate 26 may be implemented as an FPCB (Flexible Printed Circuit Board). As shown in FIGS. 8 and 9, if the first flexible substrate 24 and the second flexible substrate 26 do not need to be synchronized or aligned, they may be separated from each other.

The intermediate frame 27 may be made of a resin such as plastic. The intermediate frame 27 houses a display panel, a fingerprint sensor 23, a drive IC 25, and the like. The top of the side wall of the intermediate frame 27 may be bonded to the transparent substrate 11 with a double-sided tape 40. The decorative film 12 can be bonded to the transparent substrate 11. Images, logos, characters, and the like can be printed on the decorative film 12.

One end of the organic film 17 is bent toward the rear side of the display panel and connected to one end of the second flexible substrate 26. The mandrel 18 is bonded to the side of the rear plate 19 and the foam pad 20 and supports the bent portion of the organic film 17.

The other end of the second flexible substrate 26 is exposed to the outside of the bottom of the intermediate frame 27 through the second hole of the intermediate frame 27 and to the other end of the first flexible substrate 24. The driver IC 25 is mounted on the second flexible substrate 26, which is exposed through the bottom of the intermediate frame 27.

As shown in FIG. 3, the first flexible substrate 24 may have a plurality of through holes. The fingerprint sensor 23 is mounted on the first side 24a of the first flexible substrate 24, and the wiring 24d connected to the motherboard of the drive IC 25 and/or the host system is formed on the second side opposite the first side 24a On 24b. The metal filler 24c filled in the through hole connects the fingerprint sensor 23 to the wiring 24d, thereby connecting the fingerprint sensor 23 to the motherboard of the host system and/or the driving IC 25, and the host system is flexible by the first The substrate 24 is coupled to the fingerprint sensor 23 such that data is exchanged with the fingerprint sensor 23 and the fingerprint sensor 23 is controlled.

The host system can be any of the following: a television system, a set-top box, a navigation system, a personal computer (PC), a home theater system, a mobile system, a wearable system, and a virtual reality system. The host system transmits the pixel data of the input image to the driver IC 25, the host system executes an application associated with the coordinates from the touch sensor driver, and performs user authentication based on the fingerprint information received from the fingerprint sensor 23. .

The display panel can be implemented as an OLED display formed on a glass substrate. In this case, the back sheet 19 and the organic film 17 can be replaced with a glass substrate.

The fingerprint sensor is bonded to the underside of the display panel without changing the display panel. The fingerprint sensor 23 is placed on the pixel array of the display panel. When the image is displayed, the user cannot see the fingerprint sensor 23 because the pixel array 16 displays the input image when the OLED is illuminated.

2 is a cross-sectional view of a display device in accordance with a second exemplary embodiment of the present invention. Elements substantially the same as those in the exemplary embodiment of FIG. 1 are denoted by the same reference numerals in FIG. 1, and a detailed description thereof will be omitted or may be briefly discussed.

Referring to FIG. 2, the display device of the present invention further includes: a directional light controller (including components 31, 32, and 33) disposed between the transparent substrate 11 and the display panel. The directional light controller includes a light source 33, a light incident element 31, and a light exiting element 32. The directional light controller can further comprise a low refractive index layer.

The light source 33 is disposed below one edge of the transparent substrate 11. The light incident element 31 and the light exiting element 32 are disposed between the transparent substrate 11 and the display panel. The light incident element 31 and the light exiting element 32 are bonded to the transparent substrate 11, and the polarizing film 14 of the display panel is bonded to the light emitting element 32.

The light from the light source 33 is refracted at a total reflection angle in the transparent substrate 11 and propagates in the transparent substrate 11. The light exiting element 32 adjusts the angle of the portion of the light that is totally reflected in the substrate. The light of the total reflection angle reduced by the light emitting element 32 can be reflected from the top of the transparent substrate 11, passes through the low refractive index layer, and is projected to the receiving portion of the optical fingerprint sensor. The light incident element 31 and the light exiting element 32 can be implemented as an optical device comprising a holographic pattern.

Other elements than the directional light controller are substantially the same as those of the aforementioned example embodiment of FIG.

4 is a cross-sectional view of a display device in accordance with a third exemplary embodiment of the present invention. Elements that are substantially the same as those in the exemplary embodiment of FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted or may be briefly discussed.

Referring to FIG. 4, the exemplary embodiment is substantially identical to the first exemplary embodiment described above except that the fingerprint sensor 23 is bonded to the foam pad 20. The metal layer 21 has holes for inserting the fingerprint sensor 23. The foam pad 20 has no holes for insertion into the fingerprint sensor.

Since the foam pad 20 is an organic material, when the fingerprint sensor 23 is implemented as an ultrasonic fingerprint sensor, it does not interfere with ultrasonic propagation. When the fingerprint sensor 23 is implemented as an ultrasonic fingerprint sensor, it is desirable to use an organic material having high transparency as the foam pad 20 to keep the foam pad 20 from absorbing light received by the fingerprint sensor 23.

Figure 5 is a cross-sectional view of a display device in accordance with a fourth exemplary embodiment of the present invention. Elements that are substantially the same as those in the exemplary embodiment of FIG. 4 are denoted by the same reference numerals, and detailed description thereof will be omitted or may be briefly discussed.

Referring to FIG. 5, the display device of the present invention further includes a directional light controller disposed between the transparent substrate 11 and the display panel. The directional light controller includes a light source 33, a light incident element 31, and a light exiting element 32. The directional light controller can further comprise a low refractive index layer. The directional light controller is substantially the same as that shown in FIG.

Figure 6 is a cross-sectional view of a display device in accordance with a fifth exemplary embodiment of the present invention. Elements that are substantially the same as those in the foregoing exemplary embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted or may be briefly discussed.

Referring to FIG. 6, this exemplary embodiment is substantially the same as the first exemplary embodiment described above except that a hole in the intermediate frame 27 that exposes the position where the fingerprint sensor 23 is located is formed. The metal layer 21 has holes for inserting the fingerprint sensor 23.

Figure 7 is a cross-sectional view of a display device in accordance with a sixth exemplary embodiment of the present invention. Elements that are substantially the same as those in the foregoing exemplary embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted or may be briefly discussed.

Referring to FIG. 7, the display device of the present invention further includes a directional light controller disposed between the transparent substrate 11 and the display panel. The directional light controller includes a light source 33, a light incident element 31, and a light exiting element 32. The directional light controller can further comprise a low refractive index layer. The directional light controller is basically the same as that shown in FIGS. 2 and 5.

Figure 8 is a cross-sectional view of a display device in accordance with a seventh exemplary embodiment of the present invention. Elements that are substantially the same as those in the foregoing embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted or may be briefly discussed.

Referring to FIG. 8, this exemplary embodiment is substantially the same as the above-described third exemplary embodiment except that the first flexible substrate 24 and the second flexible substrate 26 are separated.

The fingerprint sensor 23 does not need to be connected to the drive IC 25. In this case, the first flexible substrate 24 on which the fingerprint sensor 23 is mounted may be connected to the motherboard of the host system without the through hole as in FIG.

Figure 9 is a cross-sectional view of a display device in accordance with an eighth exemplary embodiment of the present invention. Elements that are substantially the same as those in the foregoing exemplary embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted or may be briefly discussed.

Referring to FIG. 9, the display device of the present invention further includes a directional light controller disposed between the transparent substrate 11 and the display panel. The directional light controller includes a light source 33, a light incident element 31, and a light exiting element 32. The directional light controller can further comprise a low refractive index layer. The directional light controller is basically the same as that shown in FIGS. 2 and 5.

11 is a plan view of a smartphone screen showing an example of a fingerprint sensor located on the screen and an example of a user interface method for indicating the location of the fingerprint sensor.

Referring to Figure 11, in the display device of the present invention, the fingerprint sensor 23 is located below the pixel array 16 displaying the input image. In (a) of Fig. 11, a broken line 111 indicates the position of the fingerprint sensor on the screen. When the user attempts to unlock the smart phone through fingerprint recognition, the display device displays the position of the fingerprint sensor on the screen as indicated by reference numeral "112" in (b) of FIG. When the user touches the vicinity 113 of the fingerprint sensor 23, the display device can display an image indicating the position 112 of the fingerprint sensor to allow the user to touch the screen on the fingerprint sensor, as shown in FIG. 11 ( c) shown.

12 to 14 are views showing in detail the operation of the directional light source device applied in Figs. 2, 5, 7, and 9.

Figure 12 is a cross-sectional view and a plan view showing a directional light source device SLS according to an embodiment of the present invention. Figure 13 is a plan view showing the light path in the transparent substrate CP shown in Figure 12 . Figure 14 is a cross-sectional view and a plan view showing a directional light source device SLS located on the display panel DP.

Referring to FIG. 12, the directional light source device SLS includes a transparent substrate CP and a directional light controller (including elements LS, CHOE, and VHOE) that projects directional light onto the transparent substrate CP. The transparent substrate CP may be the transparent substrate 11 in the above exemplary embodiment, but is not limited thereto. In the foregoing embodiments, the directional light controller may be implemented as, but not limited to, the light source 33, the incident light element 31, and the light exiting element 32. The directional light controller may further comprise a low refractive index layer LR.

The directional light controller is an optical device that disperses collimated light over a large area within the transparent substrate CP. It is desirable for the source LS to provide collimated light.

The light emitting element VHOE and the light incident element CHOE are bonded to the lower surface of the transparent substrate CP. The light exiting element VHOE is an optical device that provides an outgoing beam 300. The receiving portion (or light receiving portion) of the optical fingerprint sensor is located below the light emitting element VHOE.

The light incident element CHOE is an optical device that causes collimated light from the light source LS to propagate in the transparent substrate CP while having directivity. The light incident element CHOE can be located on the edge of the display panel because it is not directly associated with image recognition. The light incident element CHOE must face the light source LS.

The light exiting element VHOE and the light incident element CHOE are on the same plane. In order to consider the process, it is desirable to form the light exiting element VHOE and the light incident element CHOE in individual regions on a single film. The light exiting element VHOE and the light incident element CHOE may be holographic elements of a holographic pattern. In this case, the main film having the pattern of the light exiting element VHOE and the main film having the pattern of the light incident element CHOE may be disposed adjacent to each other, and then the two hologram patterns may be simultaneously copied in one hologram recording. On the membrane.

The low refractive index layer LR is located between the elements VHOE and CHOE and the display panel. The low refractive index layer LR has a lower refractive index than the transparent substrate CP and the light emitting element VHOE.

The transparent substrate CP may be made of a transparent substrate having a refractive index of 1.5. The light emitting element VHOE and the light incident element CHOE are transparent hologram recording films whose refractive index may be equal to or slightly higher than the refractive index of the transparent substrate CP. Here, for convenience of explanation, it is assumed that the refractive index 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 target fingerprint IM. For example, the low refractive index layer LR may have a refractive index of about 1.4, which is close to the refractive index of human skin of 1.39.

The light source LS is disposed opposite to the light incident element CHOE. It is desirable for the light source LS to provide highly collimated light like a laser. When applied to a display device with built-in fingerprint recognition, the light source LS can provide an infrared laser beam that is invisible to the user.

The incident beam 100 of collimated light from the source LS has a given cross-sectional area and is provided to an entry point IP defined on the light incident element CHOE. The incident beam 100 preferably enters a direction perpendicular to the IP surface of the entry point. However, the present invention is not limited thereto, and if necessary, the incident beam 100 may be incident at an oblique angle from a direction perpendicular to the surface of the incident point IP.

The light incident element CHOE converts the incident light beam 100 into a traveling light beam 200 having an incident angle and transmits it to the inside of the transparent substrate CP. Here, it is desirable that the incident angle is larger than the internal total reflection critical angle of the transparent substrate CP. As a result, the traveling light beam 200 is totally reflected in the transparent substrate CP and travels along the X axis corresponding to the length of the transparent substrate CP.

The light exiting element VHOE converts some of the traveling beam 200 into an outgoing beam 300 and refracts it onto the upper surface of the transparent substrate CP. The remaining portion of the traveling beam 200 is totally reflected and travels within the transparent substrate CP. The outgoing beam 300 is totally reflected from the upper surface of the transparent substrate CP but passes through the low refractive index layer LR on the lower surface thereof. That is, the outgoing beam 300 serves as a detecting beam (or sensing beam) 400, which is totally reflected from the upper surface of the transparent substrate CP and passes through the lower surface thereof.

The emitted light beam 300 is gradually emitted by the light emitting element VHOE as it travels from the light incident element CHOE. In this case, the amount of light in the outgoing beam 300 is determined by the light extraction efficiency of the light exiting element VHOE. For example, if the light extraction efficiency of the light exiting element VHOE is 3%, 3% of the initial incident light beam 100 is extracted as the outgoing light beam 300 (in the first light emitting region where the traveling light beam 200 first contacts the light exiting element VHOE), At the same time, 97% of the initial incident beam as the traveling beam 200 continues to be totally reflected and traveled. Thereafter, in the second illuminating region, 2.91% of the initial incident beam 100, that is, equal to 3% of the remaining 97%, is extracted as the outgoing beam 300.

In this way, the outgoing beam 300 is extracted until it reaches the far edge of the transparent substrate CP. With this uniform light extraction efficiency, the amount of light extraction gradually decreases as the traveling beam 200 goes further and further. In order to keep the amount of light in the outgoing beam 300 constant while the traveling beam 200 is traveling, it is desirable that the light extraction efficiency of the light exiting element VHOE is designed to increase exponentially.

When viewed in an XZ plane (or "vertical plane") consisting of an axis along the length and thickness, the traveling beam 200 remains collimated as if it were an incoming beam 100. On the other hand, in order to provide an image detecting area corresponding to a region of the transparent substrate CP, the traveling light beam 200 preferably, but not necessarily, has a divergence angle on an XY plane (or "horizontal plane") formed along an axis of length and width ( φ). For example, if possible, the position of the light exiting element VHOE is expected to correspond to the entire area of the light output portion LOT. Moreover, the divergence angle φ is equal to or larger than the inner angle of the two line segments connecting the two end points P1 and P2 on the other side opposite to the light incident element CHOE from the incident point IP to the transparent substrate CP.

The area in which the light incident element CHOE is located may be defined as the light input portion LIN. The area in which the light exiting element VHOE is located may be defined as the light output part LOT. Further, the light output portion LOT may be a light traveling portion that travels along the light.

For example, if the cross-sectional area of the collimated light from the light source LS is 0.5 mm × 0.5 mm, the light incident element CHOE may 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 may be located over the entire width of the transparent substrate CP.

Referring to Fig. 13, a description will be made regarding a path along a direction in which a collimated infrared beam from a light source is converted into a directional infrared beam for image detection in a transparent substrate CP.

The incident light beam 100 from the light source LS is incident on the light incident element CHOE in a direction perpendicular to the surface of the incident point IP. The light incident element CHOE converts the incident light beam 100 into a traveling light beam 200 refracted at an incident angle (θ) and transmits it to the inside of the transparent substrate CP.

The angle of incidence (θ) of the traveling beam 200 is preferably, but not necessarily, greater than the total reflection critical angle TVHOE_LR at the interface between the light exiting element VHOE and the low refractive index layer LR. For example, if the refractive index of the transparent substrate CP and the light exiting element VHOE is 1.5, and the refractive index of the low refractive index layer LR is 1.4, the total reflection criticality at the interface between the light emitting element VHOE and the low refractive index layer LR The angle TVHOE_LR is approximately 69 degrees. Therefore, it is desirable that the incident angle (θ) is greater than 69 degrees. For example, the incident angle (θ) can be set to a range from 70 degrees to 75 degrees.

Since the upper surface of the transparent substrate CP is in contact with the air layer AIR, the traveling light beam 200 is totally reflected from the upper surface of the transparent substrate CP. This is because the total reflection critical angle TCP_AIR at the interface between the transparent substrate CP and the air layer AIR is about 41.4 degrees. That is, as long as the incident angle (θ) is greater than the total reflection critical angle TVHOE_LR at the interface between the light exiting element VHOE and the low refractive index layer LR, the incident angle (θ) is always greater than that in the transparent substrate CP and the air layer AIR The total reflection critical angle TCP_AIR at the interface between the two.

The light emitting element VHOE converts a certain amount of light in the traveling light beam 200 into an outgoing light beam 300 having a reflection angle (α) and transmits it back to the inside of the transparent substrate CP. The outgoing light beam 300 is a light beam for identifying a pattern of the fingerprint IM that is in contact with the upper surface of the transparent substrate CP. If there is no object on the surface of the transparent substrate CP, the outgoing beam 300 must be totally reflected and transmitted to the optical fingerprint sensor located below the directional light source device SLS. The emitted light beam 300 becomes a detection light beam 400 that propagates under the directional light source device SLS after being totally reflected from the upper surface of the transparent substrate CP.

The optical fingerprint sensor bonded to the lower side of the display panel can distinguish the fingerprint pattern image on the transparent substrate CP by receiving the detection beam 400.

As shown in FIG. 14, the display device according to the present invention includes a directional light source device SLS and a display panel DP located below the directional light source device SLS. Specifically, such a display device can be realized by the structures shown in Figs. 2, 5, 7, and 9.

Referring to Figure 14, the incident beam 100 is converted into a traveling beam 200 by a light incident element CHOE. The traveling beam 200 is converted to have a divergence angle (φ) on the XY plane, which is a horizontal plane composed of an X-axis along the length and a Y-axis along the width. Moreover, the traveling beam 200 remains parallel in the original manner in the XZ plane, which is a vertical plane formed by the X-axis along the length and the Y-axis along the thickness.

Preferably, but not necessarily, the divergence angle (φ) is equal to or greater than the inner angle of two line segments connected from the entry point IP to the two end points on the other side of the transparent substrate CP opposite the light incident element CHOE . In this case, the traveling beam 200 travels in a triangular divergence with the divergence angle (φ). As a result, the image sensing area may be within a triangle. Therefore, when applied to the fingerprint recognition device, a sensing area SA may correspond to a striped circle.

If the sensing area SA is formed at the center of the display panel DP or at the portion of the upper edge of the display panel DP opposite to the light incident element CHOE, it is desirable that the amount of light in the outgoing light beam 300 is the largest in the sensing area SA. To this end, the light extraction efficiency of the light exiting element VHOE can be designed as a function of position such that it is highest in the portion corresponding to the sensing area SA and lowest or close to zero in the other parts.

Figure 15 is a view of an ultrasonic path that varies according to the presence or absence of an air layer between the medium and the ultrasonic fingerprint sensor. The medium 150 in FIG. 15 includes a transparent substrate, a light emitting element, a low refractive index layer, and a display panel. If the air layer 152 is not present in the medium 150, as shown in (A) of FIG. Ultrasonic waves can pass through the medium 150 and be reflected by the fingerprint IM and received by the receiving portion of the ultrasonic fingerprint sensor. On the other hand, if there is an air layer 152 between the ultrasonic fingerprint sensor and the medium 150, as shown in (B) of FIG. 15, the ultrasonic wave from the ultrasonic fingerprint sensor cannot be transmitted to the range of the fingerprint IM. Instead, it is reflected from the surface of the medium 150, so the fingerprint pattern cannot be sensed.

Similarly, in the case of the optical fingerprint sensor 23, if there is an air layer between the optical fingerprint sensor 23 and the medium 150, the light receiving efficiency of the optical fingerprint sensor 23 is low, which reduces the sensing performance. Meanwhile, if the lens 23a is disposed in front of the receiving portion of the optical fingerprint sensor 23, as shown in (A) of FIG. 16, the lens 23a guides the light in parallel and guides the light to the receiving portion, so that even if there is an air layer in front of the receiving portion Fingerprint sensing is also possible. As shown in (B) of FIG. 16, the lens 23a may be positioned opposite to the receiving portion 23b in the space provided by the cylindrical side wall 23c in the optical fingerprint sensor 23. The top of the side wall 23a is bonded to the display panel with an adhesive 22.

17 is a view of a light path in a directional light source device that totally reflects light within a transparent substrate, the light path varying depending on whether an air layer is present between the transparent substrate medium and the optical fingerprint sensor. When light is totally reflected in the medium 150, as shown in (A) of FIG. 17, if there is an air layer 152 between the medium 150 and the optical fingerprint sensor 23, no light is guided to the optical fingerprint sensor. Therefore fingerprint sensing is impossible. Of course, by using the low refractive index layer described above, some light can be directed to the optical fingerprint sensor 23 due to the air layer, but the presence of the air layer can reduce the light receiving efficiency of the optical fingerprint sensor 23. When light is totally reflected in the medium 150, as shown in (B) of FIG. 17, if there is no air layer 152 between the medium 150 and the optical fingerprint sensor 23, the light is guided to the optical fingerprint sensor. Therefore fingerprint sensing is possible.

In the present invention, as shown in FIGS. 1 to 9, the fingerprint sensor 23 is bonded to the display panel without an air layer, and the fingerprint sensor 23 is buried in the foam pad 20 and/or the display panel. In the hole in the metal layer 21. Therefore, since there is no air layer between the fingerprint on the transparent substrate 11 and the fingerprint sensor 23, and the distance between them can be reduced, the present invention allows accurate fingerprint sensing using the fingerprint sensor 23.

In order to bury the fingerprint sensor 23 in the display panel, a gap 29 may be provided between the foam pad 20 and the metal layer 21 and the fingerprint sensor 23, as shown in FIG. Due to the process tolerances of the imprinted foam pad 20 and the metal layer 21, a gap 29 may be seen on the screen displaying the image. As shown in Figures 18-20, the non-transparent film 50 can cover the gaps 29 of the fingerprint sensor 23 and its surroundings to keep the gap 29 invisible. The non-transparent film 50 may be, but not limited to, a black or dark film coated with a binder on one side.

18 to 20 are diagrams showing the opaque film 50 covering the fingerprint sensor 23 and the gap 29 therearound in the buried structure of the fingerprint sensor 23 shown in Figs. 1 and 2. 21 is a view showing the opaque film 50 covering the fingerprint sensor 23 and the gap 29 around it in the buried structure of the fingerprint sensor 23 shown in FIGS. 4 and 5.

Referring to FIGS. 18-21, the non-transparent film 50 is adhered to the metal layer 21 and the fingerprint sensor 23 to cover the fingerprint sensor 23 and the gap 29 therearound. The non-transparent film 50 may be a black or dark adhesive film or a resin.

The adhesive 22 for bonding the fingerprint sensor 23 to the backing plate 19 may be a transparent adhesive or an opaque adhesive. The opaque adhesive can be a colored adhesive. An example of the transparent adhesive may be a transparent OCR, and examples of the colored adhesive may be a dark or black OCR, but the present invention is not limited to them. When an opaque adhesive is used as the adhesive 22, the non-transparent film 50 can be omitted, as shown in FIG. 19, because the opaque adhesive can replace the non-transparent film 50.

The foam pad 20 can be bonded to the backsheet 19 with an adhesive 28 such as OCA. The fingerprint sensor 23 can be bonded to the backing plate 19 using the same adhesive 28 as the foam pad 20, as shown in FIG. Instead of using a separate adhesive 22 .

An ultraviolet (UV) filter for blocking light of visible wavelengths and penetrating ultraviolet light (UV) can be mixed with binders 22 and 28, which are opposite the receiving portion of fingerprint sensor 23. In this case, it is not necessary to add a separate ultraviolet (UV) filter to the optical fingerprint sensor.

As described above, the display device according to the embodiment of the present invention can be used without placing the frame size or changing by placing the fingerprint sensor under the pixel array having the light emitting diode and bonding the fingerprint sensor to the display panel. The fingerprint on the screen is detected in the case of the display panel structure. Furthermore, the present invention can ensure ultrasonic or light between the fingerprint-contacting transparent substrate and the fingerprint sensor by forming a hole for blocking electromagnetic interference EMI in the metal layer and inserting the fingerprint sensor into the hole. path of.

While the embodiments have been described with reference to the embodiments of the embodiments of the present invention, it will be understood that many other modifications and embodiments are possible within the scope of the principles of the invention. More particularly, various variations and modifications can be made in the elements and/or arrangements of the combinations of the elements in the scope of the invention. Alternative uses will also be apparent to those skilled in the art, in addition to variations and modifications in the elements and/or arrangements.

The present application claims priority to Korean Patent Application No. 10-2016-0158471, filed on Nov. 25, 2016, and Korean Patent Application No. 10-2017-0053800, filed on April 26, 2017, for all Objects are incorporated herein by reference as if fully set forth herein.

Claims (17)

A display device includes: a transparent substrate; a display panel disposed to be positioned under the transparent substrate, and displaying an image on a display area toward the transparent substrate; a fingerprint sensor located below the display panel Detecting a fingerprint in contact with the transparent substrate; a driving integrated circuit configured to drive the display panel; a foam pad located below the display panel; and a metal layer under the foam pad, wherein The metal layer includes a hole that exposes the foam pad, and the fingerprint sensor is bonded to a surface of the foam pad in the hole. The display device of claim 1, further comprising: a non-transparent film disposed to be positioned under the fingerprint sensor. The display device of claim 1, wherein the fingerprint sensor is disposed on the display panel on an opposite side of a fingerprint contact position between the transparent substrate and the display panel. The display device of claim 1, wherein the fingerprint sensor comprises an ultrasonic fingerprint sensor or an optical fingerprint sensor. The display device of claim 2, wherein the non-transparent film is configured to cover the hole below the fingerprint sensor. The display device of claim 2, further comprising: a foam pad under the display panel; and a metal layer under the foam pad, wherein the foam pad and the metal layer comprise A hole of the display panel is exposed, and the fingerprint sensor is bonded to a surface of the display panel in the hole. The display device of claim 6, wherein the non-transparent film is configured to cover the hole below the fingerprint sensor. The display device of claim 1, further comprising: a light incident component positioned on an edge of the display panel; a light emitting component located in the display area of the display panel; and a A light source is disposed at a position opposite to the light incident element and projects light into the light incident element. The display device of claim 8, wherein each of the light incident element and the light exiting element comprises a hologram pattern. The display device of claim 1, wherein the display panel comprises: a pixel array disposed on an organic film and having a plurality of pixels respectively including a light emitting diode; and a touch sensor An array disposed on the pixel array; a polarizing film positioned on the touch sensor array; and a backing plate positioned below the organic film. The display device of claim 10, further comprising: a first flexible substrate disposed at a place where the fingerprint sensor is disposed; and a second flexible substrate disposed at the driving product The place where the body circuit is set. The display device of claim 11, further comprising a mandrel, wherein one end of the organic film has a bent portion bent and connected to the second flexible substrate, and the mandrel supports the organic film The bend. The display device of claim 1, wherein the position of the fingerprint sensor is displayed on a screen of the display panel. The display device of claim 1, further comprising a lens disposed in front of a receiving portion of the fingerprint sensor. The display device of claim 1, further comprising an intermediate frame configured to receive the display panel, the fingerprint sensor, and the driving integrated circuit, and having a sidewall adhered to the transparent substrate . The display device of claim 1, wherein the fingerprint sensor is bonded to a surface of the display panel through an adhesive. The display device of claim 16, wherein the adhesive is opaque.