Patent Publication Number: US-2020285826-A1

Title: Display substrate and display device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. National Stage under 35 U.S.C. § 371 of International Application No. PCT/CN2017/107351, as filed on Oct. 23, 2017, which claims the benefit of priority to the Chinese Patent Application No. 201710192831.7, filed on Mar. 28, 2017. The disclosure of each application is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a display substrate and a display device. 
     BACKGROUND 
     Fingerprint is an invariant feature that is innate, unique and can distinguish one people from others. It is composed of a series of ridges and valleys on the skin surface of the fingertip. The minutes of the ridges and valleys usually include bifurcations of the ridges, ridge ending, arches, tent-shaped arches, left spin, right spin, whorl or double spins, and etc., which decide the uniqueness of the fingerprint pattern. The thus developed fingerprint recognition technology is a technology used for personal identity authentication, and according to the difference between the acquisition and input methods of the fingerprint, the currently widely used and well-known technologies comprise: optical imaging, heat-sensitive sensors, human body infrared sensors, and etc. 
     SUMMARY 
     Embodiments according to the present disclosure relate to a display substrate, comprising: 
     an array of optical sensing devices; 
     an optical structure disposed above the array of optical sensing devices, wherein the optical structure comprises a plurality of optical units each of which comprises a light shading region and a light transmission region; and 
     a pixel array disposed above the optical structure, wherein the pixel array comprises a plurality of pixel units each of which comprises subpixels of different colors. 
     Alternatively, a width of each of the optical units is “a” times a width of one of the subpixels in the pixel unit, where “a” is an integer greater than or equal to 1. 
     Alternatively, a width of each of the optical units is “im” times a width of one subpixel in the pixel unit, where “i” is a number of the subpixels in each pixel unit, and “m” is an integer greater than or equal to 1. In other words, the width of each of the optical units is m times the width of one of the pixel units. 
     Alternatively, the light transmission region in each of the optical units is arranged corresponding to “n” optical sensing devices in the array of optical sensing devices, where “n” is an integer greater than or equal to 1. 
     Alternatively, the light transmission regions in the plurality of optical units are arranged corresponding to one optical sensing device in the array of optical sensing devices. 
     Alternatively, the light shading region in each of the optical units is provided with, in turn, a first light shading layer, a first light transmission layer and a second light shading layer, in a direction away from the array of optical sensing devices. 
     Further alternatively, the light transmission region in each of the optical units is provided with a second light transmission layer, and each of the first light transmission layers is integrally formed with the second light transmission layer. 
     Further alternatively, a material of the first light shading layer and the second shading layer is a black matrix or metal; a material of the first light transmission layer is polyimide or glass. 
     Alternatively, the light shading region of each of the optical units is provided with a light shading body, and a through-hole defined by any adjacent two of the light shading bodies is the light transmission region. 
     Embodiments according to the present disclosure relate to a display device comprising the aforementioned display substrate. 
     Alternatively, the display device further comprises, in turn, a package layer, a polarizer, an optical adhesive and a protective glass arranged in a direction away from the pixel array. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram showing a structure of a display substrate in which one optical unit corresponds to one subpixel in the pixel unit according to some embodiments of the present disclosure; 
         FIG. 2  is a structural diagram of a display substrate in which one optical unit corresponds to one pixel unit according to some embodiments of the present disclosure; 
         FIG. 3  is a structural diagram of a display substrate in which one optical unit corresponds to a plurality of pixel units according to some embodiments of the present disclosure; 
         FIG. 4  is a schematic diagram of an optical structure in a display substrate according to some embodiments of the present disclosure; 
         FIG. 5  is a schematic diagram of an optical structure in a display substrate according to some embodiments of the present disclosure; 
         FIG. 6  is a schematic diagram showing a display substrate in which the light transmission region of one optical unit corresponds to one optical sensing device according to some embodiments of the present disclosure; 
         FIG. 7  is a schematic diagram showing a display substrate in which the light transmission region of one optical unit corresponds to a plurality of optical sensing devices according to some embodiments of the present disclosure; 
         FIG. 8  is a schematic diagram showing a display substrate in which the light transmission region of a plurality of optical units corresponds to one optical sensing device according to some embodiments of the present disclosure; 
         FIG. 9  is a schematic diagram showing a structure of a display device according to some other embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In order to enable those skilled in the art to better understand the technical solutions of the present disclosure, the present disclosure will be further described in detail in the following in combination with the accompanying drawings and the embodiments. 
     A touch control substrate with fingerprint recognition function in the related technologies generally comprises an array of optical sensing devices and a pixel array disposed above the array of optical sensing devices, and the pixel array comprises a plurality of pixel units each comprising a plurality of subpixels of different colors. The metal lines (these metals are driving lines used to drive the subpixels) beneath each subpixel have different areas, as a result, after the occurrence of a touch, a uniform light emitted by each subpixel is reflected from the finger onto the light path of the array of optical sensing devices. Although the subpixels in the pixel array are evenly distributed, the lights emitted by the different subpixels have different transmittances after they transmit from the side of their respective metal lines beneath. As a result, optical sensing devices in the array of optical sensing devices, which should have received the same proportion of light intensity reflected by the finger, now receive a reduced light of different proportions of intensity. In this way, the image acquisition capability of the optical sensing devices is worsened. When the light reflected by the finger is received, the valleys and ridges of the fingerprint will be blurred and cannot be discriminated from one another, and it is difficult to acquire the fingerprint image. 
     As shown in  FIG. 1 , some embodiments according to the present disclosure provide a display substrate, comprising: an array  1  of optical sensing devices; an optical structure  2  disposed above the array  1  of optical sensing devices; and a pixel array  3  disposed above the optical structure  2 . The optical structure  2  comprises a plurality of optical units  20  each comprising a light shading region Q 1  and a light transmission region Q 2 . The pixel array  3  comprises a plurality of pixel units  30  each comprising subpixels of different colors. 
     Since in the display substrate of this embodiment, each optical unit  20  comprises a light transmission region Q 2  and a light shading region Q 1 , in other words, light can transmit through only the light transmission region Q 2 , when a touch occurs on the display substrate, an emission angle of the light reflected, after the light from the subpixels in the pixel unit  30  above the optical unit  20  irradiates the touch object (including the finger), can be limited, so that only the light within a certain angle can transmit through the optical unit  20  and reach the array  1  of optical sensing devices beneath. Therefore, the object touching the display substrate can obtain a clear and sharp image in the array of optical sensing devices, and a blur will not occur due to crosstalk of lights from different directions. 
     It should be noted here that, the pixel array  3  in this embodiment is an organic electroluminescent or organic light emitting diode (OLED) pixel array  3 . The “width of optical unit  20 ” in this embodiment refers to a distance of the optical unit  20  in a row direction of the pixel array  3 . The “width of pixel unit  30 ” refers to a distance of the pixel unit  30  in the row direction of the pixel array  3 . The “width of subpixel” refers to a distance of the subpixel in the row direction of the pixel array  3 . The pixel array  3  includes a substrate  31 , a driving layer  32  (forming a pixel driving circuit) disposed above the substrate  31 , and a pixel unit  30  disposed above the driving layer  32 . The number of subpixels in each pixel unit  30  is i. An example is described in the following in which each pixel unit  30  comprises a red subpixel, a green subpixel, and a blue subpixel (i.e., i=3). Each subpixel comprises an OLED light-emitting device consisting of a cathode, an anode, and a light-emitting layer arranged between the cathode and the anode. 
     In one embodiment of this disclosure, the width of each optical unit  20  is “a” times the width of one subpixel of the pixel unit  30 , where “a” is an integer greater than or equal to 1. As shown in  FIG. 1 , each optical unit  20  is arranged corresponding to one subpixel in the pixel unit  30 . That is, the width of each optical unit  20  is 1 times the width of one subpixel in the pixel unit  30 , i.e., a=1. In this embodiment of this application, each optical unit  20  can also be arranged corresponding to a number (a) of subpixels, that is, the width of each optical unit  20  can also be “a” times the width of one subpixel in the pixel unit  30 . 
     In addition, each subpixel further comprises a pixel driving circuit generally located beneath the OLED light-emitting device, and a metal signal line connected to the pixel driving circuit, for providing a driving signal for the OLED light-emitting device. Although the metal signal lines located beneath the subpixels of different colors occupy different areas, that is, for each OLED light-emitting device, the light reflected from the side of the metal signal line beneath has a different transmittance, for each pixel unit  30 , the total transmittance of the light reflected from the sides of the metal signal lines beneath the individual OLED light-emitting devices in the pixel unit  30  is the same. 
     Alternatively, a width of each of the optical units  20  is “im” times a width of one subpixel in the pixel unit  30 , where “i” is a number of the subpixels in each pixel unit, and “m” is an integer greater than or equal to 1. In other words, the width of each optical unit  20  is “m” times the width of one pixel unit  30 . 
     The display substrate in this embodiment is provided with an optical structure  2 , and a width of each of the optical units in the optical structure  2  is “im” times a width of one subpixel in the pixel unit  30 , where “i” is a number of the subpixels in each pixel unit, and “m” is an integer greater than or equal to 1. In other words, one optical unit  20  is arranged corresponding to m pixel units  30 . Moreover, the total transmittance of the light reflected from the sides of the metal signal lines beneath the individual subpixels in each pixel unit  30  is the same, and similarly, the total transmittance of the light reflected from the sides of the metal signal lines beneath the individual subpixels in each plurality of pixel units  30  is also the same, so the same light transmits through every “m” pixel units  30 . Thereafter, the light passing through the lower corresponding optical unit  20  is reduced in the same ratio, and the light then passes through the optical structure  2  and arrives at the lower array  1  of optical sensing devices to obtain an also uniformly reduced light intensity, so the optical sensing device  30  uniformly acquires the image of the object on the display substrate. In particular, if the object is a finger, it is possible to acquire the valleys and ridges in the fingerprint of the finger to achieve fingerprint recognition. 
     Among them, as shown in  FIG. 2 , one optical structure  2  in the optical structures  2  of the display substrate in this embodiment is arranged alternatively corresponding to one pixel unit  30 , i.e., m=1 (at this time, a=i), and at this time, comparatively minute and fine images such as fingerprint can be recognized. As shown in  FIG. 3 , of course, it can also be that one optical unit  20  corresponds to a plurality of display units, i.e., m&gt;1, and such a setting can be used to roughly recognize an object with larger lines such as palm print. At this time, the image obtained by the array of the optical sensing devices has rougher details, but the overall structure is recognizable. Since there is not too much information recognizable, the processing time of the terminal can be saved, such that the terminal is more rapid and saves more power, and this is very essential to the mobile terminal. 
     Specifically, as shown in  FIG. 4 , for each optical unit  20 , the light shading region Q 1  can comprise a first light shading layer  21 , a first light transmission layer  23  and a second light shading layer  22  arranged in this order in a direction away from the array  1  of optical sensing devices. That is, the optical unit  20  is composed of two layers of light shading material with a layer of light transmission material sandwiched therebetween. The material of the first light shading layer  21  and the second light shading layer  22  is black matrix or metal. Of course, it may be other composite materials, as long as light cannot transmit through it. The material of the first light transmission layer  23  is polyimide or glass. Of course, the first light transmission layer  23  can be an air layer, and it also can be other composite materials, as long as light can transmit through it. Moreover, for the light transmission region Q 2  in each optical unit  20 , since the light transmission region Q 2  allows light to transmit therethrough, no material can be provided in the light transmission region Q 2 . Of course the second light transmission layer  24  can be formed while forming the first light transmission layer, and at this time the individual first light transmission layer  23  is formed integrally with the second light transmission layer  24 , and the two are made of the same material. This can simplify the fabrication process of the optical unit  20 . 
     Of course, the light shading region Q 1  of each optical unit  20  can also adopt the structure of the light shading body  25 , and a through-hole defined by any adjacent two of the light shading bodies  25  is the light transmission region Q 2 , as shown in  FIG. 5 . Such a structure can be realized by depositing an entire layer of light shading material, and then etching at a position corresponding to the light transmission region Q 2  of each optical unit  20  to form the through-hole. 
     It should be noted here that, a ratio of the light shading region Q 1  and light transmission region Q 2  in each optical unit  20  can be varied, that is, the light shading region Q 1  is wider and the corresponding light transmission region Q 2  is narrower, or the light shading region Q 1  is narrower and the corresponding light transmission region Q 2  is wider. The width of the light shading region Q 1  in the optical unit  20  is relatively larger, so as to deal with a different OLED module thickness and a thickness of the opaque material in the optical unit  20 , thereby limiting the angle of light from the pixel unit  30  above. Therefore, only the light of a certain angle can pass through the optical structure  2  to reach the array  1  of optical sensing devices. 
     The light transmittance region Q 2  in each optical unit  20  is arranged corresponding to the n optical sensing devices  10  in the array  1  of optical sensing devices, where n is an integer greater than or equal to 1. In other words, the light transmittance region Q 2  in one optical unit  20  is arranged corresponding to one optical sensing device  10 , as shown in  FIG. 6 . Otherwise, the light transmittance region Q 2  in one optical unit  20  is arranged corresponding to a plurality of optical sensing device  10 , as shown in  FIG. 7 . Of course, it can also be that, the light transmittance regions Q 2  in a plurality of optical unit  20  is arranged corresponding to one optical sensing device  10  in the array  1  of optical sensing devices, as shown in  FIG. 8 . 
     The size of the optical sensing device  10  in each of the above implementations depends on the material of the optical sensing device  10  and the size of the display substrate. The array  1  of optical sensing devices can be composed of a thin film transistor and an optical sensing device  10 , and the optical sensing device  10  can be a photoelectric device. 
     As shown in  FIG. 9 , some other embodiments according to the present disclosure provides a display device comprising the display substrate in the aforementioned embodiments. Of course, the display device further comprises a package layer  4 , a polarizer, an optical adhesive  5  and a protective glass  6  arranged in this order in a direction away from the pixel array  3 . 
     As the display device in this embodiment includes the display substrate in the above embodiments, and the optical structure  2  arranged in the display substrate of the above embodiments, wherein each optical unit  20  includes a light transmission region Q 2  and a light shading region Q 1 , that is, only the light transmittance area Q 2  can allow light to transmit threethrough. When a touch occurs on the display substrate, an emission angle of the light reflected, after the light from the subpixels in the pixel unit  30  above the optical unit  20  irradiates the touch object (including the finger), can be limited, so that only a certain angle of light can transmit through this optical unit  20  and reach the array  1  of optical sensing devices beneath, such that the object touching the display substrate can obtain a clear and sharp image in the array of optical sensing devices, and a blur due to crosstalk of lights from different directions will not occur. In one embodiment of the present disclosure, a width of each optical unit  20  is “a” times a width of one subpixel in the pixel unit  30 , where “a” is an integer greater than or equal to 1. In this embodiment, a width of each optical unit  20  in the optical structure  2  may be “im” times a width of one of the subpixels in the pixel unit  30 , where “I” is a number of the subpixels in each pixel unit, and “m” is an integer greater than or equal to 1. In other words, one optical unit  20  may be arranged corresponding to m pixel units  30 . Moreover, the total transmittance of the light reflected from the sides of the metal signal lines beneath the individual subpixels in each pixel unit  30  is the same, and similarly, the total transmittance of the light reflected from the sides of the metal signal lines beneath the individual subpixels in each plurality of pixel units  30  is also the same, so the same light transmits through each m pixel units  30 . Thereafter, the light passing through the lower corresponding optical unit  20  is reduced in the same ratio, and the light then passes through the optical structure  2  and arrives at the lower array  1  of optical sensing devices to obtain an also uniformly reduced light intensity, so the optical sensing device  30  uniformly acquires the image of the object on the display substrate. In particular, if the object is a finger, it is possible to acquire the valleys and ridges in the fingerprint of the finger to achieve fingerprint recognition. 
     The display device can be an electroluminescent display device such as electronic paper, OLED panel, mobile phone, tablet, television set, monitor, notebook computer, digital photo frame, navigator, and any product or component with the display functionality. 
     It should be appreciated that, the above embodiments merely are illustrative embodiments adopted for explaining the principle of the present disclosure, but the present disclosure is not limited thereto. Those skilled in the art could make various variations and modifications within the spirit and substance of the present disclosure, and all these variations and modifications are also regarded as the scope of protection of the present disclosure.