TWM595251U - Backlight module applied to display panel - Google Patents

Abstract

A backlight module applied to a display panel includes a light guide plate and a visible light source. The light guide plate generates infrared light in conjunction with an infrared light source. The visible light source disposed on one side of the light guide plate emits light rays entering the light guide plate to generate visible light. Thus, light rays for information display and biometrics sensing can be provided.

Description

Backlight module applied to display panel

The present invention relates to an electronic device with an under-screen infrared biosensor, and particularly relates to an electronic device with an under-screen infrared biosensor that can be applied to liquid crystal displays (LCD) and OLED Electronic equipment and backlight module applied to display panel.

Today's mobile electronic devices (such as mobile phones, tablets, laptops, etc.) are usually equipped with user biometric systems, including different technologies such as fingerprints, face shapes, irises, etc., to protect personal data security, which is used in mobile phones, for example Mobile devices such as smart watches or smart watches also have the function of mobile payment, which becomes a standard function for user biometrics, and the development of mobile devices such as mobile phones is toward full screen (or ultra-narrow bezel) The trend of making traditional capacitive fingerprint buttons (such as the buttons of iphone 5 to iphone 8) can no longer be used, and has evolved new miniaturized optical imaging devices (much like traditional camera modules, with complementary metal oxide Semiconductor (Complementary Metal-Oxide Semiconductor (CMOS) Image Sensor (referred to as CIS) sensing element and optical lens module). The miniaturized optical imaging device is placed under the screen (may be called under the screen), partially transparent through the screen (especially organic light emitting diode (Organic Light Emitting Diode, OLED) screen), you can capture and press the top of the screen The image of the object, especially the fingerprint image, can be called Fingerprint On Display (FOD).

Existing optical biosensors (such as fingerprint sensors) include at least one optical module. The optical module has a CMOS image sensor (CMOS Image Sensor, CIS) chip or module, and a lens array module (Lens array) module), these components or modules are mainly placed under the OLED display. Because the OLED display itself transmits light, there is no problem in implementation.

However, in addition to OLED screens (or screens), many products also use LCD screens, and OLED screens are also evolving, such as the development of low-penetration screens (penetration rate from 3% to 1%), these require new screens Under the optical fingerprint scheme. The problem to be solved in this case is how to design an infrared optical sensing module under the liquid crystal display (Liquid Crystal Display, LCD), or low-transmission OLED, or a different screen in the future. This requires many challenges. For example, the LCD has components such as a backlight module, a light-enhancing film, and a light guide plate. RGB visible light comes in from the side, and then diffuses out from the light guide plate and the light-enhancing film to uniformize or blur the light. There are many zigzag structures on the light guide plate and the light enhancement film, which scatter the light in various directions. If the CIS module is placed under the light enhancement film and light guide plate of the backlight module, the backlight module has an anti-reflection coating (ARC) to allow total reflection of visible light, so the visible light reflected from the finger Unable to penetrate and reach the CIS module, causing image sensing problems.

Another problem to be solved in this case is, for example, the OLED display, whose resolution is getting higher and higher, and the visible light FOD is limited by the lower and lower visible light transmittance of the display (the resolution is getting higher and higher), which makes the sensor visible light Signal-to-noise ratio (SNR) is getting lower and lower, so the FOD solution of IR can also solve this problem. Of course, other display technologies, such as Micro Light Emitting Diode (uLED) displays, etc., are also applicable to this solution.

Therefore, an object of the embodiment of the present invention is to provide a screen The electronic device of the following infrared biosensor and the backlight module applied to the display panel. The electronic device has functions of information display and biosensing.

To achieve the above purpose, embodiments of the present invention provide an electronic device, at least including a backlight module, a display panel, a light-transmitting protection plate, an optical sensor, and an infrared light source. The backlight module provides visible light to travel upward, and has a reflective layer to block visible light from traveling downward. The display panel is arranged above the backlight module and displays information according to visible light. The light-transmitting protection plate is arranged above the display panel and allows information to penetrate. The optical sensor is arranged below the backlight module. The infrared light source provides infrared light to a living body on or above the light-transmitting protective plate. The biological body reflects infrared light to generate reflected infrared light. The reflected infrared light is received by the optical sensor through the light-transmitting protection plate, the display panel and the backlight module, so that the optical sensor obtains an image representing the biological body An image signal to realize the under-screen image sensing function.

In addition, the present invention also provides an electronic device, at least including: a display panel that provides visible light traveling upwards and displays information based on the visible light; a light-transmitting protective plate, which is provided above the display panel to allow information to penetrate; an optical sense The detector is arranged below the display panel; and an infrared light source, which provides infrared light to a living body located on or above the light-transmitting protection board. The living body reflects infrared light to generate reflected infrared light, and the reflected infrared light passes through the light The protection board and the display panel are received by the optical sensor, so that the optical sensor obtains an image signal representing an image of the living body.

The present invention further provides a backlight module applied to a display panel, which at least includes a light guide plate and a visible light source. The light guide plate cooperates with an infrared light source to generate an infrared light. The visible light source is arranged on one side of the light guide plate, and emits light to travel into the light guide plate to generate a visible light. This can provide the required light for information display and biological sensing.

With the above embodiment, using infrared light can enable the optical sensing module provided under the LCD to obtain a good biometric image without affecting the display function of the LCD. The reflective layer of the LCD has different characteristics for infrared light and visible light. The reflective layer that makes the visible light impenetrable can allow infrared light to pass through. The reflected infrared light from the finger can easily penetrate the reflective layer to reach the set reflection The optical sensor below the layer achieves the function of biometric sensing, and provides an optical biosensing solution for electronic devices equipped with LCD displays. In addition to being suitable for LCD displays, it is also suitable for optical biosensing occasions of other displays such as OLED displays.

In order to make the above-mentioned contents of the new model more obvious and understandable, the preferred embodiments are described in detail below in conjunction with the attached drawings, which are described in detail below.

F: Organism

FR: Peak

FT: Free end

FV: Tanibu

H: height

IR0: initial infrared light

IR1: infrared light

IR2: reflected infrared light

P: pitch

R: radius

VL: visible light

10: Backlight module

11: reflective layer

12: light guide plate

12A: Base

12B: Arc convex

12C: V-shaped cut

12D: Underside

12E: top surface

13: Visible light source

14: Visible light emitting diode

15: diffuse brightness enhancement layer

16: Diffusion layer

17: Brightening film

18: drive

20: Display panel

21: Rear polarizer

22: Rear alignment layer

23: Liquid crystal layer

24: front electrode

25: color filter layer

26: Front polarizer

30: Light-transmitting protection board

31: Anti-reflection layer

32: Optical transparent glue

40: Optical sensor

41: lens module

42: Sensing unit

50: Infrared light source

51: Light emitting unit

52: Specific curvature lens

53: Optical film

55: circuit board

56: light guide plate

90: battery

100: electronic equipment

[FIG. 1] A schematic diagram of an electronic device with an under-screen infrared biosensor according to a preferred embodiment of the present invention.

[FIG. 1A] A schematic diagram showing a modification of the electronic device of [FIG. 1].

[FIG. 2] A partial schematic diagram showing the electronic device of [FIG. 1].

[FIG. 2A] A schematic diagram showing a modified example of the electronic device of [FIG. 2].

[FIG. 3] A schematic diagram showing an example of the combined structure of the backlight module of [FIG. 1], a display panel, and a light-transmitting protective plate.

[FIG. 4] A partial schematic diagram showing an actual configuration example of [FIG. 1].

[FIG. 5] and [FIG. 6] are partial schematic diagrams showing two variation configuration examples of [FIG. 4].

[FIG. 7] to [FIG. 9] Schematic diagrams showing three configurations of the infrared light source relative to the light-transmitting protection plate.

[FIG. 10] to [FIG. 12] Schematic diagrams showing three variations of [FIG. 1].

[FIG. 13] A perspective schematic view of a backlight module corresponding to [FIG. 10].

[FIG. 14] shows a front view of the backlight module corresponding to [FIG. 13].

[FIG. 15 and [FIG. 16] are front views showing two variations of the backlight module corresponding to [FIG. 14].

[FIG. 17] A perspective schematic view showing a modification of the backlight module corresponding to [FIG. 10].

[FIG. 18] shows a partial schematic view of the backlight module corresponding to [FIG. 10].

[FIG. 19] shows a partial schematic view of the light guide plate corresponding to [FIG. 18].

[FIG. 20] A partial schematic view showing another example of the light guide plate corresponding to [FIG. 19].

[FIG. 21] A schematic diagram showing the dimensions of each component of the light guide plate.

[FIG. 22A] to [FIG. 22F] display fingerprint images obtained by using six different sizes of light guide plates.

[FIG. 23] A schematic diagram of an electronic device with an under-screen infrared biosensor according to another embodiment of the present invention.

[FIG. 24] shows a variation of the electronic device of [FIG. 23].

[FIG. 25] A front view showing a variation of the optical sensor and infrared light source of [FIG. 23].

[FIG. 26] A plan view showing the optical sensor of [FIG. 25].

The creator of this case found that infrared (IR) can penetrate the above ARC. In this way, the IR was hit by a finger, and the finger reflected IR down through the cover glass, display panel and backlight module and received by the CIS module. Achieve fingerprint sensing. However, if you want to hit IR from the bottom of the backlight module to your finger, the IR will pass through the backlight module when traveling upward, and the IR will also pass through the backlight module when traveling downward. As a result, the outgoing IR is blurred, and the reflected IR is also blurred, making the sensed fingerprint image blurred. To send from the front Shooting IR to your finger, there will be many interference problems to be solved.

This case proposes four design architectures to achieve IR emission to the finger. The first is about side lighting, which emits IR from the side of the cover glass (cover glass), where ARC can be placed under the cover glass to keep the IR intensity of the incident cover glass at a high intensity. In this lighting method, Total Internal Reflection (TIR) can be used. The second is about changing the design of the backlight module. In the visible light (red, green and blue GB) LED array on the side of the backlight module, put some IR LEDs. The third is about using a linear array of RGB LEDs and another IR LEDs in parallel. The fourth is to modify the design of the light guide module. In this way, IR lighting can be set at all possible positions, including side lighting and down lighting.

FIG. 1 shows a schematic diagram of an electronic device 100 with an under-screen infrared biosensor according to a preferred embodiment of the present invention. FIG. 2 shows a partial schematic diagram of the electronic device 100 of FIG. 1. The electronic device 100 is, for example, a mobile phone, a tablet computer, a wearable device, an electronic device with a biometric sensing function, and the like. As shown in FIGS. 1 and 2, the electronic device 100 includes at least a backlight module 10, a display panel 20, a light-transmitting protection plate 30, an optical sensor 40 and an infrared light source 50. The electronic device 100 has a function of displaying information to interact with the user, and may also have a touch function to allow the user to input commands or data. For example, when the user uses the optical sensor 40 to sense biometrics, he can perform actions such as login and biometric comparison. If the biometric comparison passes, the central processing unit (not shown) of the electronic device 100 can unlock To allow users to perform advanced operations or conduct transactions.

The backlight module 10 provides visible light VL to travel upward, and the backlight module 10 has a reflective layer 11 to block the visible light VL from traveling downward (away from the display panel 20). The display panel 20 is disposed above the backlight module 10 and is used to display information according to the visible light VL. The application on mobile devices such as mobile phones may be a display cell (Display Cell), or It is a display unit with touch function. The light-transmitting protective plate 30 is disposed above the display panel 20 to allow information to pass through. The application on mobile devices such as mobile phones may be Cover Glass (CG). The optical sensor 40 is disposed below the backlight module 10. In one example, the optical sensor 40 is a lens-type optical sensor, which uses one lens or a combination of multiple lenses to achieve an image sensing function. In another example, the optical sensor 40 is an ultra-thin optical sensor , With a microlens collimator design.

The infrared light source 50 provides infrared light IR1 to a living body F located on or above the light-transmitting protection plate 30. In this embodiment, the infrared light source 50 is disposed above the reflective layer 11. For example, the biological body F of a finger reflects infrared light IR1 to generate reflected infrared light IR2. The reflected infrared light IR2 is received by the optical sensor 40 through the transparent protective plate 30, the display panel 20, and the backlight module 10, so that The optical sensor 40 obtains an image signal representing an image of the living body F. The image includes fingerprint images, blood vessel images, blood oxygen concentration images, etc. of biological organ information on the surface or subcutaneous layers of the skin. The above configuration structure can achieve the effect of the new type, and achieve the function of under-screen infrared bio-sensing. It is worth noting that the above-mentioned "reflection" may be that infrared light is reflected by the surface of the living body F, or it may be a phenomenon in which infrared light enters the living body F and is emitted from the living body F.

In this embodiment, the infrared light source 50 is disposed below the light-transmitting protection plate 30 and is disposed on one side of the display panel 20. That is, the area of the transparent protective plate 30 is larger than the area of the display panel 20, and the infrared light source 50 is disposed in the redundant space formed by the transparent protective plate 30 and the display panel 20. The optical sensor 40 is disposed below the backlight module 10 and beside the battery 90 of the electronic device 100. In another embodiment, the optical sensor 40 (for example, having an ultra-thin microlens collimator design) may be disposed between the battery 90 and the backlight module 10, as shown in FIG. 1A.

As shown in FIG. 2, the infrared light IR1 passes through the anti-reflection of the transparent protective plate 30 The layer 31 and the anti-reflection layer 31 prevent the infrared light IR1 from being reflected by the light-transmitting protection plate 30 and failing to reach the living body F. As shown in FIG. 2A, the infrared light source 50 is located below the backlight module 10, and provides a downlighting method, which is also applicable to the above embodiment.

FIG. 3 is a schematic diagram showing an example of the combined structure of the backlight module 10, the display panel 20, and the light-transmitting protection plate 30 of FIG. As shown in FIG. 3, the backlight module 10 and the display panel 20 constitute a liquid crystal display (Liquid Crystal Display, LCD). In a non-limiting example, the backlight module 10 includes at least a reflective layer 11, a light guide plate (LGP) 12, a visible light source 13, and a diffuse brightness enhancement layer 15. The diffusion brightening layer 15 includes a diffusion layer (Diffuser, DIFF) 16 and a brightness enhancement film (Brightness Enhanced Film, BEF) 17. The reflective layer 11 is, for example, an enhanced specular reflector (ESR) produced by 3M. The display panel 20 includes a rear polarizer 21, a rear alignment layer 22, a liquid crystal layer 23, a front electrode 24, a color filter layer 25, and a front polarizer (Front Polarizer) 26 stacked sequentially from bottom to top, but This new type is not limited to this. In addition, the display panel 20 is adhered to the light-transmitting protection plate 30 through an optical clear adhesive (Optical Clear Adhesive, OCA) 32. It is worth noting that FIG. 3 shows only one example, and does not specifically limit the present invention to this. For visible light, the diffusion layer 16 and the brightness enhancement film 17 will blur the image, the light guide plate 12 will reduce the image quality, and the reflective layer 11 will reflect the visible light upward. However, the author of this case found that for infrared light, infrared light can penetrate the reflective layer 11 and is not greatly affected by the diffusion layer 16, the brightness enhancement film 17, and the light guide plate 12. Therefore, the configuration of the embodiment of the present invention is suitable for the application of the LCD, but it is not particularly limited thereto. Any display provided with a reflective layer that reflects visible light belongs to the application of the embodiment of the present invention.

FIG. 4 shows a partial schematic diagram of an actual configuration example of FIG. 1. As shown in FIG. 4, a driver 18 of the electronic device 100 controls the backlight module 10 and the display panel 20 Operate so that the electronic device 100 can display information to the user. As shown in FIG. 4, the infrared light IR1 penetrates the light-transmitting protection plate 30 and is irradiated on a peak FR of the organism F directly contacting the light-transmitting protection plate 30 to generate reflected infrared light IR2, and the reflected infrared light IR2 is coupled Into the light-transmitting protective plate 30, a part of the image corresponding to the peak FR appears bright. On the other hand, a valley FV of the living body F cannot reflect the infrared light IR1 penetrating the light-transmitting protective plate 30, so that a part of the image corresponding to the valley FV appears in a dark state. In an example, a distance between the infrared light source 50 and the living body F is between 10 mm and 30 mm or between 15 mm and 20 mm, or a distance between the sensing area of the living body F and the infrared light source 50 is between 10 mm Between 30mm or 15mm to 20mm. In the example shown in FIG. 4, a fairly uniform light field can be obtained to enhance the image sensing result.

5 and 6 show partial schematic diagrams of two variation configuration examples of FIG. 4. As shown in FIG. 5, the infrared light IR1 penetrates the light-transmitting protective plate 30 and is irradiated on a free end FT of the living body F. The free end FT is coupled into the living body F to generate reflected infrared light IR2, or infrared The light IR1 is scattered in the living body F to generate reflected infrared light IR2. In this case, the peak FR of the biological body F directly contacting the light-transmitting protection plate 30 couples the reflected infrared light IR2 into the light-transmitting protection plate 30, so that a part of the image corresponding to the peak FR appears bright, and The valley part FV cannot couple the reflected infrared light IR2 into the living body F. In this example, the illumination received by the living body F is relatively uniform. Compared with the method of FIG. 6 described later, the change is relatively small, and there is no problem that the residue on the light-transmitting protective plate 30 affects the image sensing. The distance between the infrared light source 50 and the living body F is between 15 mm and 20 mm, or the distance between the sensing area of the living body F and the infrared light source 50 is between 15 mm and 20 mm. As shown in FIG. 6, the infrared light IR1 is totally reflected in the light-transmitting protection plate 30, and the peak FR of the biological body F directly contacting the light-transmitting protection plate 30 couples the infrared light IR1 into the biological body F to make the peak portion FR A part of the corresponding image appears dark, and the valley FV cannot couple infrared light IR1 into the living body In F, the corresponding part sensed by the optical sensor 40 appears bright. The advantage of using total reflection is that the distance between the infrared light source 50 and the organism F can be relatively long, and the light field will be relatively uniform, because the infrared light attenuation is not high to achieve a certain level of total reflection efficiency.

7 to 9 are schematic diagrams showing three configurations of the infrared light source relative to the transparent protective plate. These three configurations can each be applied to the structures of FIGS. 4 to 6. As shown in FIG. 7, the light field can be changed by rotating the arrangement angle of the light emitting unit of the infrared light source 50, so that the circuit board 55 mounted with the light emitting unit assumes a tilted non-horizontal state, which can provide a better light field to the living being In general, the frame of the current mobile device is about 1 mm to allow the rotation of the infrared light source 50, but the frame can also be enlarged to provide an appropriate rotation space. As shown in FIG. 8, the infrared light source 50 includes: a light emitting unit 51 that emits infrared light IR1; and a specific curvature lens 52 that covers the light emitting unit 51 to change the light divergence angle and light field of the infrared light IR1. The light-emitting unit 51 includes a light-emitting diode (LED) or a laser diode (LD), and the laser diode includes a vertical-cavity surface-emitting laser (Vertical-Cavity Surface-Emitting) Laser). In one example, the wavelength of light emitted by the LD is 940 nanometers (nm). In FIG. 8, the LED or LD package can be changed, and the special area ratio lens or structure can be used to change the light divergence angle and light field. With current technology, the 0402 LED package can be used.

As shown in FIG. 9, the infrared light source 50 includes: a light-emitting unit 51 that emits infrared light IR1; and an optical film 53 disposed on the light-emitting unit 51. The optical film 53 is attached to the light-transmitting protection plate 30 and covers the light-emitting unit 51, to change the light divergence angle and light field of infrared light IR1, the light emitting unit 51 includes a light emitting diode or a laser diode, and the optical film 53 includes a grating, Fresnel lens or element, or Diffraction elements. When designing, by selecting the diffraction item or level of the grating, the light angle can be controlled. The diffractive element is, for example, a Diffractive Optical Element (DOE). In the optical film, it is preferable to use With nearly parallel light output, it can be matched with LED or LD, using a collimator or collimating structure on the package to make a simple collimating effect, and then using these components to change and control the light angle and light field, you can make Design is easier. Alternatively, the optical film may integrate the functions of at least two of collimation, grating, Fresnel lens, and diffractive elements to generate a desired light field.

Therefore, in FIG. 9, the optical film can be attached to the side or bottom surface of the light-transmitting protective plate 30, and then the LED or LD can be attached to the optical film to change the light divergence angle and light field, and the mechanism is easy to assemble. There is no need to expand the bezel, only a small thickness needs to be added, and the increased thickness does not affect the entire LCD, so the cost can be reduced. For example, the nanoimprint method can be used to manufacture the optical film. In addition, because the LED and the optical film are in a bonded state, the design needs to consider the near field optics. With the above settings, the light field can be changed to match the biometric sensing function.

10 to 12 show schematic diagrams of three variations of FIG. 1. FIG. 13 shows a perspective schematic view of the backlight module corresponding to FIG. 10. FIG. 14 shows a front view of the backlight module corresponding to FIG. 13. As shown in FIGS. 10, 13 and 14, the infrared light source 50 and the visible light source 13 of the backlight module 10 are disposed on the same side of the backlight module 10. In detail, the plurality of light emitting units 51 of the infrared light source 50 and the plurality of visible light emitting diodes 14 of the visible light source 13 of the backlight module 10 are disposed on the same side of the light guide plate 12 of the backlight module 10. Viewed from another angle, the light-emitting units 51 and the visible light-emitting diodes 14 are alternately arranged on the same side of the light guide plate 12 and arranged in a straight line. It is worth noting that although FIG. 14 takes 2 infrared light emitting diodes as an example for illustration, in another example, 4 infrared light emitting diodes are interposed between visible light emitting diodes 14 , You can also get a light field that can be used for image sensing.

15 and 16 show front views of two variations of the backlight module corresponding to FIG. 14. As shown in FIGS. 11 and 15, the light-emitting units 51 and the visible light emit light. The polar bodies 14 are arranged on the same side of the light guide plate 12 and are arranged in two straight lines. As shown in FIGS. 11 and 16, the light-emitting units 51 and the visible light-emitting diodes 14 are disposed on the same side of the light guide plate 12, and are arranged in two straight lines, and the distribution area of the light-emitting units 51 is smaller than the visible light The distribution area of the light-emitting diode 14.

As shown in FIG. 12, the plurality of light emitting units 51 of the infrared light source 50 and the plurality of visible light emitting diodes 14 of the visible light source 13 of the backlight module 10 are disposed on opposite sides of the light guide plate 12 of the backlight module 10.

FIG. 17 shows a perspective schematic view of a variation of the backlight module corresponding to FIG. 10. As shown in FIG. 17, the plurality of light emitting units 51 of the infrared light source 50 and the plurality of visible light emitting diodes 14 of the visible light source 13 of the backlight module 10 are disposed adjacent to the light guide plate 12 of the backlight module 10.

FIG. 18 shows a partial schematic view of the backlight module corresponding to FIG. 10. FIG. 19 shows a partial schematic view of the light guide plate corresponding to FIG. 18. As shown in FIGS. 18 and 19, the backlight module 10 is applied to or used in conjunction with the display panel 20, thereby providing light required for information display and bio-sensing. The light guide plate 12 of the backlight module 10 cooperates with the infrared light source 50 to generate infrared light IR1 (the light source 50 is not a necessary element here, because it can also be arranged on the side as shown in FIGS. 4 to 6, that is, infrared light is reflected from the fingerprint and transmitted The backlight module is detected by the optical sensor 40). The visible light source 13 is disposed on one side of the light guide plate 12 and emits light into the light guide plate 12 to travel to generate visible light VL. The light guide plate 12 includes at least a substrate 12A, a plurality of arc-shaped convex portions (Dot) 12B, and a plurality of V-cut portions (V-cut) 12C. The arc-shaped convex portion 12B is disposed on a bottom surface 12D of the base 12A, and is used to destroy the total reflection of light in the base 12A to generate visible light VL. The V-shaped cut portion 12C is disposed on a top surface 12E of the substrate 12A, and is used to destroy the total reflection of light in the substrate 12A to generate visible light VL. That is, without the arc-shaped convex portion 12B and the V-shaped cut portion 12C, the light from the light source 13 can be seen only in The substrate 12A is totally reflected, and the arc-shaped convex portion 12B and/or the V-shaped cut portion 12C guide light to generate visible light VL. The arc-shaped convex portion 12B and the V-shaped cut portion 12C will also affect the travel of infrared light, so without affecting the visible light VL, it is necessary to design a better arc-shaped convex portion 12B and the V-shaped cut portion 12C to obtain Acceptable fingerprint image.

FIG. 20 shows a partial schematic view of another example of the light guide plate corresponding to FIG. 19. As shown in FIG. 20, it is not necessary to provide the V-shaped cut portion 12C.

FIG. 21 shows a schematic diagram of dimensions of various components of the light guide plate. As shown in FIG. 21, the arc-shaped convex portion 12B has a radius R and a height H. The pitch of the distribution of these arc-shaped convex portions 12B is equal to the pitch P. 22A to 22F show fingerprint images obtained using six different sizes of light guide plates. In this disclosure, six different design parameters (as listed in Table 1) are used to obtain six fingerprint images (Figure 22A, Drawing 22F), and its modulation transfer function (Modulation Transfer Function) value MTF (representing image blur) Degree) is also listed in Table 1.

In the above six examples, the effect of the light guide plate 12 on the display function of all the examples is not much different, so by comparing the MTF value of the fingerprint image, it can be obtained which parameters are better parameters. It can be obtained from Table 1 and Figures 22A to 22F that the MTF value is related to P/H From the first and second examples, the radius R is the same, but the larger the value of P/H, the higher the MTF value. From the second example and the fourth and sixth examples, P/H is similar, but the larger the R value, the higher the MTF value, although the P/H value of the sixth example is slightly lower than the second and fourth examples, But the contribution of the R value can make the MTF value of the sixth example higher. However, there is no absolute linear relationship. When P/H is lower than a certain value, the MTF value will drop sharply, as can be seen from the fifth example. According to Figure 22C corresponding to the third example, although the MTF value is high, moiré patterns will be caused on the image. According to other experimental results, P is preferably not more than 100 microns, and more preferably Do not exceed 80 microns.

Therefore, according to the above and other experimental results, regarding the application of fingerprints, the unified design specifications are as follows. The pitch P of the distribution of these arc-shaped convex portions 12B is less than or equal to 150, 100, or 80 microns to avoid moiré. The radius of each arcuate convex portion 12B is between 10 and 300 microns (between 10 and 150 microns, or between 30 and 120 microns, and more preferably between 20 and 110 microns), and The ratio of the pitch P to the height H of each arcuate convex portion 12B is between 30 and 300 (between 20 and 150, between 30 and 120 or more preferably between 35 and 45) In a design example, P/H is equal to 40. As P/H increases, improved fingerprint image quality can be obtained. Therefore, the above design specifications can suppress moiré and increase the MTF value without affecting the display function. Of course, the content of this disclosure is not only applicable to side lighting, light guide plate lighting, but also to bottom lighting.

With the above-mentioned embodiments, the use of infrared light allows the optical sensing module provided under the LCD to obtain a good biometric image without affecting the display function of the LCD. The reflective layer of the LCD also has different infrared and visible light. The reflective layer that makes visible light impenetrable allows infrared light to pass through. The reflected infrared light from the finger can easily penetrate the reflective layer and reach the optical sensor under the reflective layer to achieve biometric sensing Function to provide an optical biosensing for electronic devices equipped with LCD displays Program.

In addition to being suitable for LCD displays, the above-mentioned design methods can also be appropriately changed to suit other displays, such as OLED displays or displays that may be developed in the future, such as uLEDs. FIG. 23 shows a schematic diagram of an electronic device with an under-screen infrared biosensor according to another embodiment of the present invention. As shown in FIG. 23, this embodiment provides an electronic device 100 that includes at least a display panel 20, a light-transmitting protection plate 30, an optical sensor 40 and an infrared light source 50. The display panel 20 provides visible light VL to travel upward, and displays information according to the visible light VL. The display panel 20 includes but is not limited to an organic light emitting diode (Organic Light Emitting Diode, OLED) display panel. The light-transmitting protection plate 30 is disposed above the display panel 20 to allow information to penetrate. The optical sensor 40 is disposed below the display panel 20. The infrared light source 50 provides infrared light IR1 to a living body F located on or above the light-transmitting protection plate 30. The infrared light IR1 is, for example, near infrared light (Near Infrared, NIR), and the wavelength is about 0.75 to 1.4 microns. The living body F reflects infrared light IR1 and generates reflected infrared light IR2. The reflected infrared light IR2 is received by the optical sensor 40 through the light-transmitting protective plate 30 and the display panel 20, so that the optical sensor 40 obtains an image signal representing an image of the living body F. In this example, the infrared light source 50 is located on the side of the display panel 20. With the above configuration, the function of under-screen infrared bio-sensing can also be achieved.

FIG. 24 shows a variation of the electronic device of FIG. 23. As shown in FIG. 24, the difference from FIG. 23 is that the infrared light source 50 is located below the display panel 20. The infrared light source 50 has one or more light-emitting units 51, such as light-emitting diodes. The light-emitting unit 51 can be disposed beside or around the optical sensor 40, and provides infrared light IR1 to penetrate the display panel 20 and the transparent protective plate 30 When reaching the biological body F, the under-screen infrared bio-sensing function can also be achieved.

FIG. 25 shows a front example of the variation of the optical sensor and infrared light source of FIG. 23 view. FIG. 26 shows a top view of the optical sensor of FIG. 25. As shown in FIGS. 25 and 26, the infrared light source 50 includes one or more light emitting units 51 and a light guide plate 56. The light emitting unit 51 provides initial infrared light IR0. The light guide plate 56 is located around the optical sensor 40, and guides the initial infrared light IR0 to generate infrared light IR1. In this example, the optical sensor 40 includes a sensing unit 42 and a lens module 41. The optical sensor may also be an ultra-thin optical sensor with a micro lens collimator design. The reflected infrared light IR2 passes through the lens module 41 and is focused on the sensing unit 42 to obtain a sensed image. The lens module 41 may be a single lens, multiple lenses, or multiple lenses arranged in a two-dimensional array. The light guide plate 56 may have a ring structure (such as a circular ring shape or a polygonal ring structure) arranged around the lens module 41, so that the light guide plate 56 can be used to process the light of the light emitting unit 51 into a uniform and traveling upward direction Infrared light IR1 can provide uniform infrared light to improve the sensing quality. The light emitting unit 51 may be arranged beside or below the light guide plate 56.

Therefore, the embodiments of the present invention can provide an optical bio-sensing solution for electronic devices equipped with LCD or OLED displays, including electronic devices with under-screen infrared bio-sensors and backlight modules applied to display panels.

The specific embodiments proposed in the detailed description of the preferred embodiments are only used to facilitate the description of the technical content of the present invention, rather than narrowly restricting the present invention to the above embodiments, without exceeding the spirit of the present invention and applying for patents below The scope of the situation, the various changes made and implemented, all belong to the scope of this new model.

IR1: infrared light

VL: visible light

10: Backlight module

11: reflective layer

12: light guide plate

12A: Base

12B: Arc convex

12C: V-shaped cut

12D: Underside

12E: top surface

13: Visible light source

16: Diffusion layer

17: Brightening film

20: Display panel

50: Infrared light source

Claims (14)

A backlight module applied to a display panel includes at least: A light guide plate that cooperates with an infrared light source to produce an infrared light; and A visible light source is disposed on one side of the light guide plate, and emits light into the light guide plate to travel to generate a visible light. The backlight module according to claim 1, wherein the light guide plate includes: A base; and A plurality of arc-shaped convex portions are provided on a bottom surface of the substrate, for destroying the total reflection of the light in the substrate to generate the visible light. The backlight module according to claim 2, wherein the light guide plate further includes: A plurality of V-shaped cut-outs are provided on a top surface of the substrate for destroying the total reflection of the light in the substrate to generate the visible light. The backlight module according to claim 2, wherein the pitch of the arcuate convex portions is less than or equal to 150 microns. The backlight module according to claim 2, wherein the radius of each arc-shaped convex portion is between 10 and 150 microns. The backlight module according to claim 2, wherein the ratio of the pitch of each arc-shaped convex portion to the height of each arc-shaped convex portion is between 20 and 150. The backlight module according to claim 2, wherein the pitch of the arc-shaped convex portions is less than or equal to 150 microns, and the radius of each arc-shaped convex portion It is between 10 and 150 microns, and the ratio of the pitch to the height of each arcuate convex portion is between 20 and 150. The backlight module according to claim 2, wherein the pitch of the arcuate convex portions is less than or equal to 80 microns. The backlight module according to claim 2, wherein the radius of the arc-shaped convex portions is between 20 and 110 microns. The backlight module according to claim 2, wherein the ratio of the pitch of each arc-shaped convex portion to the height of each arc-shaped convex portion is between 30 and 120. The backlight module according to claim 2, wherein the pitch of the arc-shaped convex portions is less than or equal to 80 microns, the radius of each arc-shaped convex portion is between 20 and 110 microns, and the pitch is equal to The ratio of the height of each arc-shaped convex portion is between 30 and 120. The backlight module according to claim 1, wherein the light guide plate includes: A base; and A plurality of V-shaped cut-outs are provided on a top surface of the substrate for destroying the total reflection of the light in the substrate to generate the visible light. The backlight module according to claim 1, wherein the display panel displays information according to the visible light. The backlight module according to claim 1, wherein the backlight module has a reflective layer that blocks the visible light from traveling away from the display panel.

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