WO2021051752A1 - 应用于显示面板的背光模组 - Google Patents

应用于显示面板的背光模组 Download PDF

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Publication number
WO2021051752A1
WO2021051752A1 PCT/CN2020/078150 CN2020078150W WO2021051752A1 WO 2021051752 A1 WO2021051752 A1 WO 2021051752A1 CN 2020078150 W CN2020078150 W CN 2020078150W WO 2021051752 A1 WO2021051752 A1 WO 2021051752A1
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WO
WIPO (PCT)
Prior art keywords
light
backlight module
arc
infrared light
guide plate
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Application number
PCT/CN2020/078150
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English (en)
French (fr)
Inventor
傅同龙
王伟榕
周正三
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神盾股份有限公司
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Publication of WO2021051752A1 publication Critical patent/WO2021051752A1/zh

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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
    • G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
    • G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
    • G06V40/12—Fingerprints or palmprints
    • G06V40/13—Sensors therefor
    • G06V40/1318—Sensors therefor using electro-optical elements or layers, e.g. electroluminescent sensing
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • G06F3/042—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by opto-electronic means

Definitions

  • the present invention relates to an electronic device with an under-screen infrared biosensor, and in particular to an electronic device that can be applied to liquid crystal displays (Liquid Crystal Display, LCD) and OLEDs with under-screen infrared biosensors
  • liquid crystal displays Liquid Crystal Display, LCD
  • OLEDs with under-screen infrared biosensors
  • Today's mobile electronic devices (such as mobile phones, tablet computers, laptops, etc.) are usually equipped with user biometric systems, including different technologies such as fingerprints, face shapes, irises, etc., to protect personal data security, such as mobile phones Or smart watches and other portable devices, which also have the function of mobile payment.
  • biometric identification has become a standard function.
  • the development of portable devices such as mobile phones is even more towards full screen (or ultra-narrow).
  • CMOS Complementary Metal-Oxide Semiconductor
  • CIS complementary Metal-Oxide Semiconductor
  • sensing components and optical lens modules The miniaturized optical imaging device is placed at the bottom of the screen (can be called under the screen), through the screen part of the light (especially organic light emitting diode (Organic Light Emitting Diode, OLED) screen), can capture the object pressed on the top of the screen
  • OLED Organic Light Emitting Diode
  • optical biosensors such as fingerprint sensors
  • the optical module contains a 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.
  • CIS CMOS image sensor
  • Liens array module lens array module
  • an LCD has components such as a backlight module, a brightness enhancement film, and a light guide plate. RGB visible light enters from the side, and then diffuses out from the light guide plate and the brightness enhancement film to homogenize or obscure the light.
  • ARC anti-reflection coating
  • Another problem to be solved in this case is that, for example, the resolution of OLED displays 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’s visible light signal
  • SNR Signal-to-Noise Ratio
  • uLED Micro Light Emitting Diode
  • an object of the embodiments of the present invention is to provide an electronic device with an under-screen infrared biosensor and a backlight module applied to a display panel.
  • the electronic device has functions of information display and biosensing.
  • an embodiment of the present invention provides an electronic device, which at least includes 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 traveling upward, and has a reflective layer to block visible light traveling downward.
  • the display panel is arranged above the backlight module and displays information according to visible light.
  • the light-transmitting protection board is arranged above the display panel and allows information to pass through.
  • the optical sensor is arranged under the backlight module.
  • the infrared light source provides infrared light to life objects located on or above the light-transmitting protective plate.
  • the biological body reflects infrared light and generates reflected infrared light. The reflected infrared light is received by the optical sensor through the light-transmitting protective 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.
  • the present invention also provides an electronic device, which at least includes: a display panel that provides visible light traveling upward and displays information according to the visible light; a light-transmitting protective plate arranged above the display panel to allow information to pass through; and an optical
  • the sensor is arranged under the display panel; and an infrared light source, which provides infrared light to the living objects on or above the light-transmitting protective plate.
  • the biological body reflects the infrared light to generate reflected infrared light, and the reflected infrared light passes through the transparent protective plate.
  • the light protection plate and the display panel are received by the optical sensor, so that the optical sensor obtains an image signal representing an image of the biological 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 into the light guide plate to travel to generate a visible light. In this way, the required light for information display and biological sensing can be provided.
  • the use of infrared light can allow the optical sensing module disposed under the LCD to obtain a good biometric image without affecting the display function of the LCD, and the reflective layer of the LCD has different characteristics for infrared light and visible light.
  • the reflective layer that makes visible light impenetrable can allow infrared light to penetrate, and the reflected infrared light from the finger can easily penetrate the reflective layer to reach the optical sensor disposed under the reflective layer, achieving biometric sensing Function to provide an optical biosensing solution for electronic devices equipped with LCD displays.
  • it is also suitable for optical biosensing applications such as OLED displays and other displays.
  • FIG. 1 shows a schematic diagram of an electronic device with an under-screen infrared biosensor according to a preferred embodiment of the present invention.
  • FIG. 1A shows a schematic diagram of a modification of the electronic device of FIG. 1.
  • Fig. 2 shows a partial schematic diagram of the electronic device of Fig. 1.
  • FIG. 2A shows a schematic diagram of a modification of the electronic device of FIG. 2.
  • FIG. 3 shows a schematic diagram of an example of the combined structure of the backlight module, the display panel, and the light-transmitting protective plate of FIG. 1.
  • Fig. 4 shows a partial schematic diagram of an actual configuration example of Fig. 1.
  • Fig. 5 and Fig. 6 show partial schematic diagrams of two modified configuration examples of Fig. 4.
  • Figures 7 to 9 show schematic diagrams of three configurations of the infrared light source relative to the light-transmitting protective plate.
  • Fig. 10 to Fig. 12 show schematic diagrams of three variation examples of Fig. 1.
  • FIG. 13 shows a three-dimensional schematic diagram of the backlight module corresponding to FIG. 10.
  • FIG. 14 shows a front view of the backlight module corresponding to FIG. 13.
  • 15 and 16 show front views of two modification examples of the backlight module corresponding to FIG. 14.
  • FIG. 17 shows a three-dimensional schematic diagram of a variation of the backlight module corresponding to FIG. 10.
  • FIG. 18 shows a partial schematic diagram of the backlight module corresponding to FIG. 10.
  • FIG. 19 shows a partial schematic diagram of the light guide plate corresponding to FIG. 18.
  • FIG. 20 shows a partial schematic diagram of another example of the light guide plate corresponding to FIG. 19.
  • Figure 21 shows a schematic diagram of the dimensions of the various components of the light guide plate.
  • Figures 22A to 22F show fingerprint images obtained by using six different sizes of light guide plates.
  • FIG. 23 shows a schematic diagram of an electronic device with an under-screen infrared biosensor according to another embodiment of the invention.
  • Fig. 24 shows a modified example of the electronic device of Fig. 23.
  • FIG. 25 shows a front view of a modification example of the optical sensor and infrared light source of FIG. 23.
  • FIG. 26 shows a top view of the optical sensor of FIG. 25.
  • IR1 infrared light
  • IR2 reflected infrared light
  • VL Visible light
  • infrared can penetrate the above-mentioned ARC.
  • the IR is put on the finger, and the finger reflects the IR downward through the cover glass, the display panel and the backlight module and is received by the CIS module.
  • the CIS module receives the CIS module.
  • the outgoing IR is blurred, and the reflected IR is also blurred, making the image of the sensed fingerprint blurred. If you want to transmit IR from the front to your finger, there will be many interference problems that need to be solved.
  • This case proposes four design architectures to achieve IR emission to the finger.
  • the first is related to lateral lighting. IR is emitted from one side of the protective glass (cover glass), where an ARC can be set under the protective glass to keep the IR intensity of the incident protective glass at a high intensity.
  • TIR Total Internal Reflection
  • the second is about changing the design of the backlight module, putting some IR LEDs in the visible light (red, green and blue GB) LED array on the side of the backlight module.
  • the third is about the use of a linear array of RGB LEDs and another linear array of IR LEDs arranged in parallel.
  • the fourth is to modify the design of the light guide module. In this way, IR lighting can be set in 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.
  • the electronic device 100 at least includes 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 instructions or data.
  • the central processing unit (not shown) of the electronic device 100 can be unlocked. In order to allow users to perform advanced operations, or conduct transactions, etc.
  • 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 (a direction away from the display panel 20).
  • the display panel 20 is disposed above the backlight module 10 for displaying information according to visible light VL.
  • the application on mobile devices such as mobile phones may be a display cell or a display unit with touch function.
  • the light-transmitting protective plate 30 is arranged 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 under the backlight module 10.
  • the optical sensor 40 is a lens-type optical sensor, which utilizes one lens or a combination of multiple lenses to achieve the image sensing function, and the optical sensor 40 in another example is an ultra-thin optical sensor. It has a micro lens collimator design.
  • the infrared light source 50 provides infrared light IR1 to a living object F located on or above the light-transmitting protective plate 30.
  • the infrared light source 50 is disposed above the reflective layer 11.
  • the biological body F of a finger reflects infrared light IR1 to generate reflected infrared light IR2, and the reflected infrared light IR2 is received by the optical sensor 40 through the light-transmitting protection 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 biological body F.
  • Images include fingerprint images, blood vessel images, blood oxygen concentration images, and other biological organ information on the skin surface or under the skin.
  • the above configuration structure can achieve the effect of the present invention, and achieve the function of under-screen infrared biosensing. It is worth noting that the above-mentioned “reflection” may be the reflection of infrared light by the surface of the biological body F, or the phenomenon that infrared light enters the biological body F and is emitted from the biological body F.
  • the infrared light source 50 is arranged under the light-transmitting protective plate 30 and arranged on one side of the display panel 20. That is, the area of the light-transmitting protection 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 light-transmitting protection plate 30 and the display panel 20.
  • the optical sensor 40 is arranged under the backlight module 10 and beside the battery 90 of the electronic device 100. In another embodiment, the optical sensor 40 (for example, with an ultra-thin microlens collimator design) may be disposed between the battery 90 and the backlight module 10, as shown in FIG. 1A.
  • the infrared light IR1 passes through an anti-reflection layer 31 of the light-transmitting protection plate 30, and the anti-reflection layer 31 prevents the infrared light IR1 from being reflected by the light-transmitting protection plate 30 and cannot reach the biological body F.
  • the infrared light source 50 is located under the backlight module 10, and provides a downward lighting method, which is also applicable to the above-mentioned embodiment.
  • FIG. 3 shows a schematic diagram of an example of the combined structure of the backlight module 10, the display panel 20 and the light-transmitting protective plate 30 of FIG. 1.
  • the backlight module 10 and the display panel 20 constitute a liquid crystal display (LCD).
  • the backlight module 10 at least includes a reflective layer 11, a light guide plate (LGP) 12, a visible light source 13, and a diffusing brightness enhancement layer 15.
  • the diffusion brightness enhancement 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 Company.
  • ESR enhanced specular reflector
  • 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 26 stacked sequentially from bottom to top.
  • OCA optical clear adhesive
  • the configuration of the embodiment of the present invention is suitable for the application of LCD, but 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.
  • a driver 18 of the electronic device 100 controls the operation of the backlight module 10 and the display panel 20, so that the electronic device 100 can display information to the user.
  • the infrared light IR1 penetrates the light-transmitting protective plate 30 and irradiates a peak FR of the biological body F directly in contact with the light-transmitting protective 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 is in a bright state.
  • a valley FV of the living body F cannot reflect the infrared light IR1 penetrating through the light-transmitting protective plate 30, so that a part of the image corresponding to the valley FV appears dark.
  • a distance between the infrared light source 50 and the biological body F is between 10 mm and 30 mm or between 15 mm and 20 mm, or the distance between the sensing area of the biological body F and the infrared light source 50 is between 10 mm and 30 mm. Between 30mm or between 15mm and 20mm. In the example shown in FIG. 4, a fairly uniform light field can be obtained, which enhances the image sensing result.
  • Fig. 5 and Fig. 6 show partial schematic diagrams of two modified configuration examples of Fig. 4.
  • the infrared light IR1 penetrates the light-transmitting protective plate 30 and irradiates a free end FT of the biological body F.
  • the free end FT is coupled into the biological body F to generate reflected infrared light IR2, or infrared
  • the light IR1 is scattered in the biological body F to generate reflected infrared light IR2.
  • 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 The part FV cannot couple the reflected infrared light IR2 into the biological body F.
  • the illuminating light received by the organism F is relatively consistent. Compared with the method of FIG. 6 described later, the change is relatively small, and there is relatively 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 biological body F is between 15 mm and 20 mm, or the distance between the sensing area of the biological body F and the infrared light source 50 is between 15 mm and 20 mm.
  • the infrared light IR1 is totally reflected in the light-transmitting protective plate 30, and the peak FR of the biological body F that directly contacts the light-transmitting protective plate 30 couples the infrared light IR1 into the biological body F to make the peak FR A part of the corresponding image presents a dark state, and the valley FV cannot couple the infrared light IR1 into the biological body F, so that the corresponding part sensed by the optical sensor 40 presents a bright state.
  • the advantage of using total reflection is that the distance between the infrared light source 50 and the biological body F can be relatively long, and the light field will be relatively uniform, because the attenuation degree of infrared light is not high if the total reflection efficiency is to reach a certain level.
  • Figures 7 to 9 show schematic diagrams of three configurations of the infrared light source relative to the light-transmitting protective plate. These three configurations can each be applied to the structures of FIGS. 4 to 6.
  • the light field can be changed by rotating the configuration angle of the light-emitting unit of the infrared light source 50, so that the circuit board 55 on which the light-emitting unit is installed presents a tilted non-horizontal state, which can provide a better light field for living beings.
  • 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 a suitable space for rotation. As shown in FIG.
  • the infrared light source 50 includes: a light-emitting unit 51 that emits infrared light IR1; and a lens 52 with a specific curvature covering 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).
  • the wavelength of the light emitted by the LD is 940 nanometers (nm).
  • the packaging of LEDs or LDs can be changed, and special zone rate lenses or structures can be used to change the light divergence angle and light field. With current technology, 0402 LED packaging can be used.
  • 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, and the optical film 53 is attached to the light-transmitting protective plate 30 and covers the light-emitting unit 51.
  • the light-emitting unit 51 includes a light-emitting diode or a laser diode
  • the optical film 53 includes a grating, a Fresnel lens or element, or a diffractive element.
  • the diffractive element is, for example, a diffractive optical element (DOE).
  • DOE diffractive optical element
  • the optical film it is better to use nearly parallel light output, so it can be matched with LED or LD, and use collimator or collimating structure on the package to make a simple collimation effect, and then use these elements to make the light angle and light Field changes and control can make design easier.
  • the optical film may integrate the functions of at least two of collimation, grating, Fresnel lens, and diffractive element to generate the required light field.
  • 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.
  • the mechanism is easy to assemble and also There is no need to expand the frame, just add a little thickness, and the increased thickness does not affect the entire LCD, so the cost can be reduced, for example, the optical film can be manufactured by nano-imprinting.
  • the LED and the optical film are in a bonded state, the design needs to consider near-field optics. With the above settings, the light field can be changed to meet the function of biometric sensing.
  • FIG. 10 to Fig. 12 show schematic diagrams of three variation examples of Fig. 1.
  • FIG. 13 shows a three-dimensional schematic diagram of the backlight module corresponding to FIG. 10.
  • FIG. 14 shows a front view of the backlight module corresponding to FIG. 13.
  • the infrared light source 50 and the visible light source 13 of the backlight module 10 are arranged on the same side of the backlight module 10.
  • the multiple light emitting units 51 of the infrared light source 50 and the multiple visible light emitting diodes 14 of the visible light source 13 of the backlight module 10 are arranged on the same side of the light guide plate 12 of the backlight module 10.
  • 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 uses two infrared light emitting diodes as an example for illustration, in another example, four infrared light emitting diodes are interspersed between the visible light emitting diodes 14 to obtain The light field of image sensing.
  • FIGS. 11 and 16 show front views of two modification examples of the backlight module corresponding to FIG. 14.
  • the light-emitting units 51 and the visible light-emitting diodes 14 are arranged on the same side of the light guide plate 12 and arranged in two straight lines.
  • these light emitting units 51 and these visible light emitting diodes 14 are arranged on the same side of the light guide plate 12 and arranged in two straight lines, and the distribution area of these light emitting units 51 is smaller than that of these visible light emitting diodes. 14 distribution area.
  • the multiple light emitting units 51 of the infrared light source 50 and the multiple visible light emitting diodes 14 of the visible light source 13 of the backlight module 10 are arranged on the opposite side of the light guide plate 12 of the backlight module 10.
  • FIG. 17 shows a three-dimensional schematic diagram of a variation of the backlight module corresponding to FIG. 10. As shown in FIG. 17, the multiple light emitting units 51 of the infrared light source 50 and the multiple visible light emitting diodes 14 of the visible light source 13 of the backlight module 10 are arranged on the adjacent side of the light guide plate 12 of the backlight module 10.
  • FIG. 18 shows a partial schematic diagram of the backlight module corresponding to FIG. 10.
  • FIG. 19 shows a partial schematic diagram of the light guide plate corresponding to FIG. 18.
  • the backlight module 10 is applied to the display panel 20 or used in conjunction with the display panel 20, thereby providing light required for information display and biological 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 component here, because it can also be arranged on the side as shown in Figure 4 to Figure 6, that is, the infrared light is reflected from the fingerprint and penetrates.
  • the visible light source 13 is arranged 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 at least includes a base 12A, a plurality of arc-shaped protrusions (Dot) 12B, and a plurality of V-cuts (V-cut) 12C.
  • the arc-shaped convex portion 12B is disposed on a bottom surface 12D of the substrate 12A, and is used to destroy the total reflection of light in the substrate 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 protrusion 12B and the V-shaped cut portion 12C, the light from the visible light source 13 can only be totally reflected in the substrate 12A, and the arc-shaped protrusion 12B and/or the V-shaped cut portion 12C can be used to The light is guided out 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. Therefore, 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 diagram 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.
  • Figure 21 shows a schematic diagram of the dimensions of the various components of the light guide plate.
  • 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.
  • Figures 22A to 22F show fingerprint images obtained by 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 to Figure 22F), and the modulation transfer function (Modulation Transfer Function) value MTF (representing blurred image) Degree) is also listed in Table 1.
  • Modulation Transfer Function Modulation Transfer Function
  • the effect of the light guide plate 12 on the display function of all examples is not much different, so by comparing the MTF values of the fingerprint images, you can obtain which parameters are better.
  • Table 1 and Figures 22A to 22F it can be seen that the MTF value is correlated with P/H. From the first and second examples, the radius R is the same, but the larger the P/H value, the higher the MTF value. . Judging from the second case, the fourth case and the sixth case, the P/H is similar, but the larger the R value, the higher the MTF value. Although the P/H value of the sixth case is slightly lower than the second and fourth cases, However, the contribution of the R value can make the MTF value of the sixth case higher.
  • P is preferably not more than 100 microns, and more preferably not. More than 80 microns.
  • the integrated design specifications for fingerprint applications are as follows.
  • the pitch P of the distribution of these arc-shaped protrusions 12B is less than or equal to 150, 100, or 80 microns to avoid moiré fringes.
  • the radius of each arc-shaped protrusion 12B is between 10 and 300 microns (between 10 and 150 microns, or between 30 and 120 microns, more preferably between 20 and 110 microns), and
  • the ratio of the distance P to the height H of each arc-shaped convex portion 12B is between 30 and 300 (between 20 and 150, between 30 and 120, or more preferably between 35 and 45).
  • the design example is that P/H is equal to 40. When 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.
  • the content of the disclosure is not only applicable to side lighting and light guide plate lighting, but also applicable to down lighting.
  • the use of infrared light can allow the optical sensing module disposed under the LCD to obtain a good biometric image without affecting the display function of the LCD, and the reflective layer of the LCD has different characteristics for infrared light and visible light.
  • the reflective layer that makes visible light impenetrable can allow infrared light to penetrate, and the reflected infrared light from the finger can easily penetrate the reflective layer to reach the optical sensor disposed under the reflective layer, achieving biometric sensing Function to provide an optical biosensing solution for electronic devices equipped with LCD displays.
  • FIG. 23 shows a schematic diagram of an electronic device with an under-screen infrared biosensor according to another embodiment of the invention.
  • this embodiment provides an electronic device 100 that at least includes a display panel 20, a light-transmitting protective plate 30, an optical sensor 40 and an infrared light source 50.
  • the display panel 20 provides visible light VL traveling 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 (OLED) display panel.
  • OLED Organic Light Emitting Diode
  • the light-transmitting protection plate 30 is arranged above the display panel 20 to allow information to pass through.
  • the optical sensor 40 is disposed under the display panel 20.
  • the infrared light source 50 provides infrared light IR1 to a living object F located on or above the light-transmitting protective plate 30.
  • the infrared light IR1 is, for example, Near Infrared (NIR) light, and the wavelength is about 0.75 to 1.4 microns.
  • the biological 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 transparent protective plate 30 and the display panel 20, so that the optical sensor 40 obtains an image signal representing an image of the biological body F.
  • the infrared light source 50 is located on one side of the display panel 20. With the above configuration, the function of under-screen infrared biosensing can also be achieved.
  • Fig. 24 shows a modified example of the electronic device of Fig. 23.
  • the difference from FIG. 23 is that the infrared light source 50 is located under 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 units 51 can be arranged beside or around the optical sensor 40, and provide infrared light IR1 to penetrate the display panel 20 and the light-transmitting protective plate 30 to reach
  • the biological body F can also achieve the function of under-screen infrared biological sensing.
  • FIG. 25 shows a front view of a modification example of the optical sensor and infrared light source of FIG. 23.
  • FIG. FIG. 26 shows a top view of the optical sensor of FIG. 25.
  • 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.
  • the optical sensor 40 includes a sensing unit 42 and a lens module 41.
  • the optical sensor can also be an ultra-thin optical sensor with a microlens 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, or may be a stack of multiple lenses, or may be composed of multiple lenses arranged in a two-dimensional array.
  • the light guide plate 56 may have a ring structure (for example, a circular ring or a polygonal ring structure), and is disposed around the lens module 41. In this way, the light guide plate 56 can be used to process the light of the light emitting unit 51 into a uniform and upward direction. Infrared light IR1, can provide uniform infrared light to improve sensing quality.
  • the light emitting unit 51 may be arranged on the side or the lower side of the light guide plate 56.
  • the embodiments of the present invention can provide an optical biosensing solution for an electronic device equipped with an LCD or OLED display, including an electronic device with an under-screen infrared biosensor and a backlight module applied to a display panel.

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Abstract

一种应用于显示面板（20）的背光模组（10），至少包含一导光板（12）及一可见光源（13），导光板（12）配合一红外光源（50）产生一红外光（IR1），可见光源（13）设置于导光板（12）的一侧，并发射光线进入导光板（12）中行进以产生一可见光（VL），从而提供信息显示及生物感测的所需要的光线。

Description

应用于显示面板的背光模组
交叉引用
本申请根据35 U.S.C.§119要求2019年9月16日递交的，发明名称为“IR LED LIGHTING INTEGRATED WITH LGP IN LCD FOD SOLUTION”的美国临时申请案62/900,812；2019年11月26日递交的，发明名称为“LGP FINGERPRINT APPLICATION RULER”的美国临时申请案62/940,445的优先权，且将上述申请作为参考。
技术领域
本发明是有关于一种具有屏下式红外线生物感测器的电子设备，且特别是有关于一种可以应用于液晶显示器(Liquid Crystal Display，LCD)及OLED等具有屏下式红外线生物感测器的电子设备，以及应用于显示面板的背光模组。
背景技术
现今的移动电子装置(例如手机、平板电脑、笔记本电脑等)通常配备有使用者生物识别***，包括了例如指纹、脸型、虹膜等等不同技术，用以保护个人数据安全，其中例如应用于手机或智慧型手表等携带型装置，也兼具有行动支付的功能，对于使用者生物识别更是变成一种标准的功能，而手机等携带型装置的发展更是朝向全屏幕(或超窄边框)的趋势，使得传统电容式指纹按键(例如iphone 5到iphone 8的按键)无法再被继续使用，进而演进出新的微小化光学成像装置(非常类似传统的相机模组，具有互补式金属氧化物半导体(Complementary Metal-Oxide Semiconductor(CMOS)Image Sensor(简称CIS))感测元件及光学镜头模组)。将微小化光学成像装置设置于屏幕下方(可称为屏下)，通过屏幕部分透光(特别是有机发光二极管(Organic Light Emitting Diode，OLED)屏幕)，可以撷取按压于屏幕上方的物体的图像，特别是指纹图像，可以称为屏幕下指纹感测(Fingerprint On Display，FOD)。
现有的光学生物感测器(譬如指纹感测器)至少包含一光学模组，光学模组里面有CMOS影像感测器(CMOS Image Sensor，CIS)晶片或模组，透镜阵列模组(Lens array module)，这些元件或模组主要是放在OLED显示器的下方。因为OLED显示器本身就会透光，所以实施上没有问题。
但是除了OLED屏(或屏幕)，许多产品也使用LCD屏，还有OLED屏也还在演进，例如低穿透屏(穿透率由3％到1％)的发展，这些都需要新的屏下光学指纹方案。本案所要解决的是如何设计一红外线光学感测模组在液晶显示器(Liquid Crystal Display，LCD)，亦或者低穿透OLED，或者未来不同的屏的下方。这需要面临到很多挑战。譬如，LCD具有背光模组、增光膜、导光板等元件，RGB的可见光从侧面打进来，然后从导光板及增光膜扩散出去，把光线均匀化或模糊化。导光板和增光膜上面有很多锯齿状结构，把光线散射到各种方向。如果把CIS模组放在背光模组的增光膜及导光板下面的话，背光模组里面有抗反射涂层(Anti-Reflection Coating，ARC)，让可见光作全反射，因此从手指反射来的可见光无法穿透而达到CIS模组，造成图像感测的问题。
本案另一个要解决问题是例如OLED显示器，其解析度越来越高，可见光FOD受限于显示器可见光穿透率越来越低(解析度越来越高)，使得感测器的可见光的信噪比(Signal-to-Noise Ratio,SNR)越来越低，因此藉由IR的FOD方案也可以解决此一问题。当然其他显示器的技术，例如微发光二极管(Micro Light Emitting Diode，uLED)显示器等等，也都适用此一方案。
发明内容
因此，本发明的实施例的一个目的在于提供一种具有屏下式红外线生物感测器的电子设备以及应用于显示面板的背光模组，此电子设备具有信息显示及生物感测的功能。
为达上述目的，本发明的实施例提供一种电子设备，至少包含一背光模组、一显示面板、一透光保护板、一光学感测器以及一红外光源。背光模组提供可见光朝上方行进，并具有一反射层来阻挡可见光朝下方行进。显示面板设置于背光模组上方，并依据可见光来显示信息。透光保护板设置于显示面板上方并让信息穿透。光学感测器设置于背光模组的下方。红外光源提供红外光到位于透光保护板上或上方的一生物体。生物体反射红外光而产生反射的红外光，反射的红外光通过透光保护板、显示面板及背光模组而被光学感测器所接收，使光学感测器获得代表生物体的一图像的一图像信号，实现屏下式图像感测功能。
此外，本发明亦提供一种电子设备，至少包含：一显示面板，提供可见光朝上方行进，并依据可见光来显示信息；一透光保护板，设置于显示面板上方，让信息穿透；一光学感测器，设置于显示面板的下方；以及一红外光源，提供红外光到位于透光保护板上或上方的一生物体，生物体反射红外光而产生反射的红外光，反射的红外光通过透光 保护板及显示面板而被光学感测器所接收，使光学感测器获得代表生物体的一图像的一图像信号。
本发明更提供一种应用于显示面板的背光模组，至少包含一导光板及一可见光源。导光板配合一红外光源产生一红外光。可见光源，设置于导光板的一侧，并发射光线进入导光板中行进以产生一可见光。藉此可提供信息显示及生物感测的所需要的光线。
藉由上述实施例，利用红外光可以让LCD下方设置的光学感测模组获得良好的生物特征图像，而不影响LCD的显示功能，也利用LCD的反射层对于红外光和可见光具有不同的特性，使得可见光无法穿透的反射层可以让红外光穿透，从手指而来的反射的红外光可以轻易穿透反射层而到达设置于反射层下方的光学感测器，达成生物特征感测的功能，为配备有LCD显示器的电子装置提供一种光学生物感测方案。除了适用于LCD显示器以外，亦适用于OLED显示器等其他显示器的光学生物感测场合。
为让本发明之上述内容能更明显易懂，下文特举较佳实施例，并配合所附图式，作详细说明如下。
附图说明
为了更清楚地说明本发明实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。在附图中：
图1显示依据本发明较佳实施例的具有屏下式红外线生物感测器的电子设备的示意图。
图1A显示图1的电子设备的变化例的示意图。
图2显示图1的电子设备的局部示意图。
图2A显示图2的电子设备的变化例的示意图。
图3显示图1的背光模组、显示面板与透光保护板的组合结构的一个例子的示意图。
图4显示图1的一个实际配置例子的局部示意图。
图5与图6显示图4的两个变化配置例子的局部示意图。
图7至图9显示红外光源相对于透光保护板的三种配置的示意图。
图10至图12显示图1的三种变化例子的示意图。
图13显示对应于图10的背光模组的立体示意图。
图14显示对应于图13的背光模组的前视图。
图15与图16显示对应于图14的背光模组的两个变化例的前视图。
图17显示对应于图10的背光模组的变化例的立体示意图。
图18显示对应于图10的背光模组的局部示意图。
图19显示对应于图18的导光板的局部示意图。
图20显示对应于图19的导光板的另一例子的局部示意图。
图21显示导光板的各个部件的尺寸标注示意图。
图22A至图22F显示利用六种不同尺寸的导光板所获得的指纹图像。
图23显示依据本发明另一实施例的具有屏下式红外线生物感测器的电子设备的示意图。
图24显示图23的电子设备的变化例。
图25显示图23的光学感测器及红外光源的变化例的前视图。
图26显示图25的光学感测器的俯视图。
F：生物体
FR：峰部
FT：自由端
FV：谷部
H：高度
IR0：初始红外光线
IR1：红外光
IR2：反射的红外光
P：节距
R：半径
VL：可见光
10：背光模组
11：反射层
12：导光板
12A：基底
12B：弧状凸部
12C：V形切部
12D：底面
12E：顶面
13：可见光源
14：可见光发光二极管
15：扩散增亮层
16：扩散层
17：增亮膜
18：驱动器
20：显示面板
21：后偏光片
22：后配向层
23：液晶层
24：前电极
25：彩色滤光层
26：前偏光片
30：透光保护板
31：抗反射层
32：光学透明胶
40：光学感测器
41：透镜模组
42：感测单元
50：红外光源
51：发光单元
52：特定曲率透镜
53：光学膜
55：电路板
56：导光板
90：电池
100：电子设备
具体实施方式
本案创作人发现红外线(Infrared，IR)可以穿透上述ARC，如此一来，将IR打上去手指，手指反射IR往下透过盖板玻璃、显示面板及背光模组而被CIS模组接收到，达成指纹的感测。但是，若要从背光模组的下方打IR上去到手指，IR朝上行进要经过背光模组，IR朝下行进也是要经过背光模组。如此一来，出射的IR被模糊化，反射回来的IR也被模糊化，使得感测到的指纹的图像模糊。若要从正面发射IR到手指，又会有很多干扰的问题需要解决。
本案提出四种设计架构来达成将IR发射到手指。第一种是有关于侧向打光，由保护玻璃(盖板玻璃)的一侧来发射IR，其中保护玻璃的下方可以设置ARC以让入射保护玻璃的IR强度保持在高强度。在这种打光方式中，可以采用全内反射(Total Internal Reflection，TIR)。第二种是有关于变更背光模组的设计，在背光模组侧边的可见光(红绿蓝GB)的LED阵列中，放入一些IR LED。第三种是有关于采用一条RGB LED的线性阵列及另一条IR LED的线性阵列平行设置。第四种则是透过修改导光模组的设计，这种方式可以将IR打光设置于所有可能的位置，包括侧向打光及下打光。
图1显示依据本发明较佳实施例的具有屏下式红外线生物感测器的电子设备100的示意图。图2显示图1的电子设备100的局部示意图。电子设备100譬如是移动电话、平板电脑、穿戴装置、具有生物特征感测功能的电子装置等。如图1与图2所示，电子设备100至少包含一背光模组10、一显示面板20、一透光保护板30、一光学感测器40以及一红外光源50。电子设备100具有显示信息以与使用者互动的功能，也可以具有触控功能来让使用者输入指令或数据。譬如，当使用者利用光学感测器40感测生物特征时，可以进行登录、生物特征比对等动作，若生物特征比对通过，则电子设备100的中央处理器(未显示)可以进行解锁，以让使用者进行进阶的操作，或进行交易等。
背光模组10提供可见光VL朝上方行进，背光模组10具有一反射层11，阻挡可见光VL朝下方(远离显示面板20的方向)行进。显示面板20设置于背光模组10上方，用于依据可见光VL来显示信息，在手机等移动装置上的应用可以是显示单元(Display Cell)，或者是具有触控功能的显示单元。透光保护板30设置于显示面板20上方，让信息穿透，在手机等移动装置上的应用可以是盖板玻璃(Cover Glass，CG)。光学感测器40设置于背光模组10的下方。于一例中，光学感测器40为透镜式光学感测器，利用一个 透镜或多个透镜的组合，达成图像感测功能，另一例的光学感测器40为超薄的光学感测器，具有微透镜准直器设计。
红外光源50提供红外光IR1到位于透光保护板30上或上方的一生物体F。于本实施例中，红外光源50设置于反射层11的上方。譬如是手指的生物体F反射红外光IR1而产生反射的红外光IR2，反射的红外光IR2通过透光保护板30、显示面板20及背光模组10而被光学感测器40所接收，使光学感测器40获得代表生物体F的一图像的一图像信号。图像包含指纹图像、血管图像、血氧浓度图像等等皮肤表层或皮肤下层的生物器官信息。以上的配置结构即可达到本发明的效果，达成屏下式红外线生物感测的功能。值得注意的是，上述的「反射」可以是红外光被生物体F的表面反射，也可以是红外光进入生物体F中而从生物体F发出的现象。
于本实施例中，红外光源50设置于透光保护板30的下方，并且设置于显示面板20的一侧。亦即，透光保护板30的面积大于显示面板20的面积，红外光源50设置于透光保护板30与显示面板20所形成的冗余空间中。光学感测器40设置于背光模组10的下方以及电子设备100的电池90的旁边。另一实施例的光学感测器40(例如是具有超薄微透镜准直器设计)可以设置于电池90与背光模组10之间，如图1A所示。
如图2所示，红外光IR1穿过透光保护板30的一抗反射层31，抗反射层31避免红外光IR1被透光保护板30反射而无法到达生物体F。如图2A所示，红外光源50位于背光模组10的下方，提供的是一种下打光的方式，同样适用于上述实施例。
图3显示图1的背光模组10、显示面板20与透光保护板30的组合结构的一个例子的示意图。如图3所示，背光模组10与显示面板20构成液晶显示器(Liquid Crystal Display,LCD)。于一非限制例中，背光模组10至少包含反射层11、导光板(Light Guide Plate，LGP)12、可见光源13及扩散增亮层15。扩散增亮层15包含扩散层(Diffuser，DIFF)16及增亮膜(Brightness Enhanced Film，BEF)17。反射层11譬如是3M公司出产的增强型镜面反射镜(Enhanced Specular Reflector，ESR)。显示面板20包含从下而上依序堆迭的后偏光片(Rear Polarizer)21、后配向层22、液晶层23、前电极24、彩色滤光层25及前偏光片(Front Polarizer)26，但是并非将本发明限制于此。此外，显示面板20通过光学透明胶(Optical Clear Adhesive，OCA)32而粘接到透光保护板30。值得注意的是，图3只是显示出其中一个例子，并非特别将本发明限制于此。对于可见光而言，扩散层16及增亮膜17会使图像模糊，导光板12会使图像品质降低，反射层11会将可见光朝上反射。然而，本案创作人发现对于红外光而言，红外光可以穿透反射层11，且不会大幅受 到扩散层16、增亮膜17及导光板12的影响。因此，本发明的实施例的配置是适合于LCD的应用场合，但不特别限制于此，举凡设置有具有反射可见光的反射层的显示器，都属于本发明的实施例的应用场合。
图4显示图1的一个实际配置例子的局部示意图。如图4所示，电子设备100的一驱动器18控制背光模组10及显示面板20的运作，以让电子设备100可以显示出信息给使用者。如图4所示，红外光IR1穿透透光保护板30而照射在直接接触透光保护板30的生物体F的一峰部FR上而产生反射的红外光IR2，而反射的红外光IR2耦合进透光保护板30中，使得峰部FR对应的图像的一部分呈现亮态。另一方面，而生物体F的一谷部FV无法反射穿透透光保护板30的红外光IR1，使得谷部FV对应的图像的一部分呈现暗态。于一例子中，红外光源50与生物体F之间的一距离介于10mm至30mm之间或介于15mm至20mm之间，或者生物体F的感测区与红外光源50的距离介于10mm至30mm之间或介于15mm至20mm之间。于图4所示之范例中，可以获得相当均匀的光场，增强图像感测结果。
图5与图6显示图4的两个变化配置例子的局部示意图。如图5所示，红外光IR1穿透透光保护板30而照射在生物体F的一自由端FT上，由自由端FT耦合进生物体F中而产生反射的红外光IR2，或者说红外光IR1于生物体F中散射而产生反射的红外光IR2。于此情况下，直接接触透光保护板30的生物体F的峰部FR将反射的红外光IR2耦合进透光保护板30中，使峰部FR对应的图像的一部分呈现亮态，而谷部FV无法将反射的红外光IR2耦合进生物体F中。于此例子中，生物体F受到的照光比较一致，相对于后述图6的方式，变化比较小，也比较没有透光保护板30上的残留物影响图像感测的问题。红外光源50与生物体F之间的距离介于15mm至20mm之间，或者生物体F的感测区与红外光源50的距离介于15mm至20mm之间。如图6所示，红外光IR1于透光保护板30内进行全反射，直接接触透光保护板30的生物体F的峰部FR将红外光IR1耦合进生物体F中，使峰部FR对应的图像的一部分呈现暗态，而谷部FV无法将红外光IR1耦合进生物体F中，使得光学感测器40感测到的对应部分呈现亮态。利用全反射的优点是红外光源50距离生物体F的距离可以比较远，光场也会比较均匀，因为要使全反射效率到达一定的水平，红外光的衰减程度并不高。
图7至图9显示红外光源相对于透光保护板的三种配置的示意图。这三种配置可以各自应用于图4至图6的结构中。如图7所示，可以藉由转动红外光源50的发光单元的配置角度而改变光场，使得安装有发光单元的电路板55呈现倾斜的非水平状态，这样可 以提供较佳的光场给生物体，目前的移动装置的边框大约有1mm来允许红外光源50的转动，但也可以加大边框以提供适当的转动空间。如图8所示，红外光源50包含：一发光单元51，发出红外光IR1；以及一特定曲率透镜52，覆盖发光单元51来改变红外光IR1的光发散角度与光场。发光单元51包含发光二极管(Light-Emitting Diode，LED)或雷射二极管(Laser Diode，LD)，雷射二极管包含垂直共振腔面射型雷射(Vertical-Cavity Surface-Emitting Laser)。于一例子中，LD发出的光线的波长为940纳米(nm)。在图8中，可以采用改变LED或LD的封装的方式，利用特殊区率透镜或结构来改变光发散角度与光场，以目前的技术而言，可以采用0402的LED封装。
如图9所示，红外光源50包含：一发光单元51，发出红外光IR1；以及一光学膜53，设置于发光单元51上，光学膜53贴合于透光保护板30上并覆盖发光单元51，来改变红外光IR1的光发散角度与光场，发光单元51包含发光二极管或雷射二极管，光学膜53包含光栅(grating)、菲涅耳(Fresnel)透镜或元件、或绕射元件。设计时，通过选择光栅的绕射项或阶层，可以控制出光角度。绕射元件譬如是绕射式光学元件(Diffractive Optical Element，DOE)。在光学膜中，较佳是采用近乎平行光的输出，所以可以搭配LED或LD，在封装上利用准直器或准直结构先作简单的准直效果，再使用这些元件作出光角度与光场的改变与控制，可以让设计更加容易。或者，光学膜可以整合准直、光栅、菲涅耳透镜以及绕射元件的至少两者的功能，以产生所需的光场。
因此，于图9中，可以将光学膜贴合在透光保护板30的侧面或底面，再将LED或LD贴合在光学膜上，来改变光发散角度与光场，机构组装容易，也不需要扩大边框，只需增加些许的厚度，而且增加的厚度又不影响到整个LCD，所以可以降低成本，譬如可以使用纳米压印的方式来制造光学膜。此外，因为LED与光学膜是贴合的状态，所以设计时需要有近场光学的考量。藉由以上的设置，可以改变光场以符合生物特征感测的功能。
图10至图12显示图1的三种变化例子的示意图。图13显示对应于图10的背光模组的立体示意图。图14显示对应于图13的背光模组的前视图。如图10、13与14所示，红外光源50与背光模组10的可见光源13设置于背光模组10的同一侧。详细而言，红外光源50的多个发光单元51与背光模组10的可见光源13的多个可见光发光二极管14设置于背光模组10的导光板12的同一侧。以另一角度看来，此等发光单元51与此等可见光发光二极管14交错设置于导光板12的同一侧，并且排列成一直线。值得注意的是，虽然图14是以2个红外光发光二极管当作例子作说明，但是于另一例子中， 以4个红外光发光二极管穿插于可见光发光二极管14之间，亦可获得可以进行图像感测的光场。
图15与图16显示对应于图14的背光模组的两个变化例的前视图。如图11与15所示，此等发光单元51与此等可见光发光二极管14设置于导光板12的同一侧，并且排列成两直线。如图11与16所示，此等发光单元51与此等可见光发光二极管14设置于导光板12的同一侧，并且排列成两直线，且此等发光单元51的分布面积小于此等可见光发光二极管14的分布面积。
如图12所示，红外光源50的多个发光单元51与背光模组10的可见光源13的多个可见光发光二极管14设置于背光模组10的导光板12的相对侧。
图17显示对应于图10的背光模组的变化例的立体示意图。如图17所示，红外光源50的多个发光单元51与背光模组10的可见光源13的多个可见光发光二极管14设置于背光模组10的导光板12的相邻侧。
图18显示对应于图10的背光模组的局部示意图。图19显示对应于图18的导光板的局部示意图。如图18与19所示，背光模组10应用于显示面板20或与显示面板20搭配使用，藉此可提供信息显示及生物感测的所需要的光线。背光模组10的导光板12配合红外光源50产生红外光IR1(光源50在此不是必要的元件，因为也可以如图4到图6地设置于侧边，也就是红外光从指纹反射后透过背光模组，而被光学感测器40侦测)，可见光源13设置于导光板12的一侧，并发射光线进入导光板12中行进以产生可见光VL。导光板12至少包含一基底12A、多个弧状凸部(Dot)12B以及多个V形切部(V-cut)12C。弧状凸部12B设置于基底12A的一底面12D，用于破坏光线在基底12A中的全反射以产生可见光VL。V形切部12C设置于基底12A的一顶面12E，用于破坏光线在基底12A中的全反射以产生可见光VL。亦即，在没有弧状凸部12B以及V形切部12C的情况下，可见光源13的光线仅能在基底12A内作全反射，藉由弧状凸部12B及/或V形切部12C来将光线导引出来而产生可见光VL。弧状凸部12B以及V形切部12C也会影响到红外光的行进，所以在不影响可见光VL的情况下，需要设计出较佳的弧状凸部12B以及V形切部12C，以获得可接受的指纹图像。
图20显示对应于图19的导光板的另一例子的局部示意图。如图20所示，也可以不需设置V形切部12C。
图21显示导光板的各个部件的尺寸标注示意图。如图21所示，弧状凸部12B具有半径R及高度H。此些弧状凸部12B分布的节距(pitch)等于节距P。图22A至图22F显 示利用六种不同尺寸的导光板所获得的指纹图像。于本揭露内容中，利用六种不同的设计参数(如表1所列)来获得六种指纹图像(图22A至图22F)，其调制转换函数(Modulation Transfer Function)数值MTF(代表图像模糊的程度)也列于表1中。
表1
例子 R(μm) H(μm) P(μm) P/H MTF(％)
1 31.64 0.52 60.08 115.5 70.30
2 31.31 1.39 59.8 43.02 43.7
3 37.87 2.6 119.96 46.13 68.5
4 40.34 2 80.33 40.16 53.8
5 79.85 1.17 35.58 30.4 6.7
6 100.75 0.5 19.92 39.94 56.1
上述六个例子中，所有例子的导光板12对于显示功能的效果差异不大，所以比较指纹图像的MTF数值，即可获得哪些参数是较佳的参数。从表1及图22A至22F可以得到，MTF数值与P/H有相关性，从第一例与第二例来看，半径R相同，但是P/H的数值越大，则MTF数值越高。从第二例与第四例及第六例来看，P/H差不多，但是R值越大，MTF数值越高，虽然第六例的P/H数值略低于第二及第四例，但是R值的贡献可以让第六例的MTF数值高一些。然而，这并没有绝对的线性关系，当P/H低于一定的数值以后，MTF数值会急遽下降，譬如从第五例可以看出。从第三例对应的图22C来看，虽然MTF数值较高，但是在图像上会造成莫尔条纹(moiré pattern)，再依据其他实验结果，P较佳是不要超过100微米，更佳是不要超过80微米。
因此，依据上述及其他实验结果，关于指纹方面的应用，统整设计规范如下。此等弧状凸部12B分布的节距P小于或等于150、100或80微米，以避免莫尔条纹。各弧状凸部12B的半径介于10至300微米之间(介于10至150微米之间，或介于30至120微米之间，更佳是介于20至110微米之间)，且节距P与各弧状凸部12B的高度H的比值介于30至300之间(介于20至150之间，介于30至120之间或更佳是介于35至45之间)，于一个设计例子是P/H等于40。当P/H增加时，可获得改良的指纹图像品质。因此，上述设计规范可以在不影响显示功能的状况下，抑制莫尔条纹并增加MTF数值。当然本揭露内容不仅仅适用于侧向打光、导光板打光，对于下打光也是一样适用的。
藉由上述实施例，利用红外光可以让LCD下方设置的光学感测模组获得良好的生物特征图像，而不影响LCD的显示功能，也利用LCD的反射层对于红外光和可见光具有不同的特性，使得可见光无法穿透的反射层可以让红外光穿透，从手指而来的反射的红外光可以轻易穿透反射层而到达设置于反射层下方的光学感测器，达成生物特征感测的功能，为配备有LCD显示器的电子装置提供一种光学生物感测方案。
上述的设计方式，除了适用于LCD显示器以外，亦可以作适当变化以适合于其他显示器，譬如OLED显示器或者未来可能发展的显示器例如uLED等等。图23显示依据本发明另一实施例的具有屏下式红外线生物感测器的电子设备的示意图。如图23所示，本实施例提供一种电子设备100，至少包含一显示面板20、一透光保护板30、一光学感测器40以及一红外光源50。显示面板20提供可见光VL朝上方行进，并依据可见光VL来显示信息。显示面板20包含但不限于有机发光二极管(Organic Light Emitting Diode，OLED)显示面板。透光保护板30设置于显示面板20上方，让信息穿透。光学感测器40设置于显示面板20的下方。红外光源50提供红外光IR1到位于透光保护板30上或上方的一生物体F。红外光IR1譬如是近红外光(Near Infrared，NIR)，波长大约在0.75至1.4微米之间。生物体F反射红外光IR1而产生反射的红外光IR2。反射的红外光IR2通过透光保护板30及显示面板20而被光学感测器40所接收，使光学感测器40获得代表生物体F的一图像的一图像信号。于本例子中，红外光源50位于显示面板20的一侧。藉由上述配置，亦可以达成屏下式红外线生物感测的功能。
图24显示图23的电子设备的变化例。如图24所示，与图23的差异特征在于红外光源50位于显示面板20的下方。红外光源50具有一个或多个发光单元51，譬如是发光二极管，发光单元51可以设置于光学感测器40旁或周围，并提供红外光IR1穿透显示面板20及透光保护板30而到达生物体F，如此亦可以达成屏下式红外线生物感测的功能。
图25显示图23的光学感测器及红外光源的变化例的前视图。图26显示图25的光学感测器的俯视图。如图25与26所示，红外光源50包含一个或多个发光单元51及一导光板56。发光单元51提供初始红外光线IR0。导光板56位于光学感测器40周围，将初始红外光线IR0导光后产生红外光IR1。于本例子中，光学感测器40包含一感测单元42及一透镜模组41，光学感测器也可以是超薄的光学感测器，具有微透镜准直器设计。反射的红外光IR2透过透镜模组41而聚焦于感测单元42上以获得感测图像。透镜模组41可以是单一透镜，也可以是多重透镜迭合，或者是多重透镜排列成二维阵列所构成。导光板56可以具有环状结构(譬如是圆环状或多边形环状结构)，配置于透镜模组41的周围，如此可以利用导光板56将发光单元51的光线处理成均匀且朝上行进的红外光IR1，可提供均匀的红外光来提升感测品质。发光单元51可以配置在导光板56的旁侧或下侧。
因此，本发明的实施例可以为配备有LCD或OLED显示器的电子装置提供一种光学生物感测方案，包含具有屏下式红外线生物感测器的电子设备以及应用于显示面板的背光模组。
在较佳实施例的详细说明中所提出的具体实施例仅用以方便说明本发明的技术内容，而非将本发明狭义地限制于上述实施例，在不超出本发明的精神及权利要求保护范围的情况，所做的种种变化实施，皆属于本发明的范围。

Claims (14)

  1. 一种应用于显示面板(20)的背光模组(10)，其特征在于，至少包含：
    一导光板(12)，配合一红外光源(50)产生一红外光(IR1)；以及
    一可见光源(13)，设置于该导光板(12)的一侧，并发射光线进入该导光板(12)中行进以产生一可见光(VL)。
  2. 如权利要求1所述的背光模组(10)，其特征在于，该导光板(12)包含：
    一基底(12A)；以及
    多个弧状凸部(12B)，设置于该基底(12A)的一底面(12D)，用于破坏该光线在该基底(12A)中的全反射以产生该可见光(VL)。
  3. 如权利要求2所述的背光模组(10)，其特征在于，该导光板(12)更包含：
    多个V形切部(12C)，设置于该基底(12A)的一顶面(12E)，用于破坏该光线在该基底(12A)中的全反射以产生该可见光(VL)。
  4. 如权利要求2所述的背光模组(10)，其特征在于，所述的多个弧状凸部(12B)分布的节距(P)小于或等于150微米。
  5. 如权利要求2所述的背光模组(10)，其特征在于，各该弧状凸部(12B)的半径介于10至150微米之间。
  6. 如权利要求2所述的背光模组(10)，其特征在于，各该弧状凸部(12B)的节距(P)与各该弧状凸部(12B)的高度(H)的比值介于20至150之间。
  7. 如权利要求2所述的背光模组(10)，其特征在于，所述的多个弧状凸部(12B)分布的节距(P)小于或等于150微米，各该弧状凸部(12B)的半径介于10至150微米之间，且该节距(P)与各该弧状凸部(12B)的高度(H)的比值介于20至150之间。
  8. 如权利要求2所述的背光模组(10)，其特征在于，所述的多个弧状凸部(12B)分布的节距(P)小于或等于80微米。
  9. 如权利要求2所述的背光模组(10)，其特征在于，所述的多个弧状凸部(12B)的半径介于20至110微米之间。
  10. 如权利要求2所述的背光模组(10)，其特征在于，各该弧状凸部(12B)分布的节距(P)与各该弧状凸部(12B)的高度(H)的比值介于30至120之间。
  11. 如权利要求2所述的背光模组(10)，其特征在于，所述的多个弧状凸部(12B)分布的节距(P)小于或等于80微米，各该弧状凸部(12B)的半径介于20至110微米之间，且该节距(P)与各该弧状凸部(12B)的高度(H)的比值介于30至120之间。
  12. 如权利要求1所述的背光模组(10)，其特征在于，该导光板(12)包含：
    一基底(12A)；以及
    多个V形切部(12C)，设置于该基底(12A)的一顶面(12E)，用于破坏该光线在该基底(12A)中的全反射以产生该可见光(VL)。
  13. 如权利要求1所述的背光模组，其特征在于，该显示面板(20)依据该可见光(VL)来显示信息。
  14. 如权利要求1所述的背光模组，其特征在于，该背光模组(10)具有一反射层(11)，阻挡该可见光(VL)朝远离该显示面板(20)的方向行进。
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