WO2021051748A1 - 基于点阵结构分布光栅的触控屏 - Google Patents

基于点阵结构分布光栅的触控屏 Download PDF

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Publication number
WO2021051748A1
WO2021051748A1 PCT/CN2020/076907 CN2020076907W WO2021051748A1 WO 2021051748 A1 WO2021051748 A1 WO 2021051748A1 CN 2020076907 W CN2020076907 W CN 2020076907W WO 2021051748 A1 WO2021051748 A1 WO 2021051748A1
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grating
optical waveguide
waveguide layer
touch screen
lattice structure
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PCT/CN2020/076907
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English (en)
French (fr)
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叶志成
王成亮
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上海交通大学
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Publication of WO2021051748A1 publication Critical patent/WO2021051748A1/zh
Priority to US17/227,200 priority Critical patent/US11429228B2/en

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    • 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
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2203/00—Indexing scheme relating to G06F3/00 - G06F3/048
    • G06F2203/041—Indexing scheme relating to G06F3/041 - G06F3/045
    • G06F2203/04109—FTIR in optical digitiser, i.e. touch detection by frustrating the total internal reflection within an optical waveguide due to changes of optical properties or deformation at the touch location

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  • the invention relates to information display, in particular to a touch screen based on a lattice structure distributed grating.
  • touch screens it can be divided into four basic types: resistive touch screens, capacitive touch screens, surface acoustic wave touch screens and infrared touch screens.
  • the resistive touch screen uses two highly transparent conductive layers to form a touch screen. Usually an elastic material is used to separate the two conductive layers. When the pressure on the touch screen is large enough, contact occurs between the two layers, and the sensor Read the contact voltage to determine the touch point coordinates.
  • the resistive screen has the advantages of high precision and low cost, and the screen is not affected by dust, water vapor and oil, and can be touched with any object, but its light transmittance is low and it is not wear-resistant.
  • the capacitive touch screen is coated with a layer of ITO on the inner surface and the interlayer of the glass screen.
  • the surface acoustic wave touch screen is composed of a touch screen, a sound wave generator, a reflector, and a sound wave receiver. When a finger touches the screen, the sound waves on the contacts are blocked, thereby determining the touch coordinates.
  • the surface acoustic wave touch screen has good optical performance and scratch resistance, but it is easily affected by the dust layer, water droplets and oil stains.
  • the above-mentioned three types of touch screens are mainly used in small and medium-sized display devices.
  • Infrared touch screens are arranged on the four sides of the display with infrared emitting tubes and infrared receiving tubes. When the user touches the screen, the finger will block the infrared rays passing through the position, and the position of the touch point on the screen can be judged based on this.
  • the infrared touch screen currently occupies a dominant position in the large-size touch market, but it is still the traditional contact touch, so the size of the touch screen is limited.
  • touch screens all require contact interaction between the operator and the touch screen, and this contact interaction must consider the physical limitations of the operator's interaction, which undoubtedly limits the size of the touch screen.
  • the non-contact interaction in the market is mainly based on the human-computer interaction of image processing, but this interaction method has the disadvantages of high cost, complex algorithm and large delay.
  • the purpose of the present invention is to solve the above-mentioned shortcomings of the prior art and provide a touch screen based on a lattice structure distributed grating, using a laser light source as an interactive medium touch detection light, which can provide an operator with a larger operating space. So as to be able to realize the interaction with the large-size touch screen.
  • the lattice structure grating is used, the transmission loss of the coupled light in the optical waveguide layer is effectively reduced, thereby greatly improving the efficiency, light transmission performance and sensitivity of the touch screen.
  • a grating touch screen based on the distribution of a lattice structure, comprising a laser light source, an optical waveguide layer, a grating and a photodetector, and is characterized in that the grating lattice structure is distributed on the optical waveguide layer.
  • the photodetector is arranged on the periphery or two adjacent sides of the optical waveguide layer, the laser light source outputs laser light of a specific wavelength as the touch detection light, and the period, duty ratio, and duty cycle of the grating are selected.
  • the height of the grating, control of the number of reflections n, loss efficiency and coupling efficiency maximize the efficiency of the touch screen.
  • the optical waveguide layer is divided into two upper and lower layers, a lattice grating structure is arranged on the upper and lower optical waveguide layers, and the grating directions on the upper and lower optical waveguides are perpendicular to each other;
  • the grating is a two-dimensional structure, the grating structure of the dot matrix is set in the X direction and the Y direction.
  • the grating in the lattice structure unit is a single period or a gradual period.
  • the photodetectors are arranged on two adjacent sides of the optical waveguide layer; when the length and width of the optical waveguide layer are not equal, Then, the photodetector is arranged on two opposite short sides and one of the long sides of the optical waveguide layer.
  • An optical filter is arranged between the optical waveguide layer and the photodetector.
  • optical waveguide layer Below the optical waveguide layer are an isolation layer and a display screen in sequence.
  • the period of the grating enables the laser to be coupled into the optical waveguide layer.
  • the efficiency of the touch screen is:
  • C j is the coupling efficiency of region j grating
  • the range of region j is [(j-1)Nd, jNd)
  • d is the transmission distance of a single reflection
  • N is a positive integer
  • n is the number of times the coupled light is reflected at the interface between the waveguide layer and the grating.
  • Li is the grating loss efficiency of the i-th reflection.
  • an appropriate grating period, duty ratio, and grating height are set to control the number of reflections n, loss efficiency Li, and coupling efficiency C j to maximize the efficiency C t of the touch screen.
  • the grating is distributed on the optical waveguide layer in a lattice structure, and there is no grating between the lattice and the lattice.
  • the efficiency of the grating touch screen with dot matrix structure distribution can be expressed as:
  • C j is the coupling efficiency of region j grating
  • duty j is the duty ratio of the lattice structure of region j
  • the range of region j is [(j-1)Nd, jNd)
  • d is the transmission distance of a single reflection
  • N is a positive integer
  • n is the number of times the coupled light is reflected at the junction of the waveguide layer and the grating
  • k i is the loss coefficient, k i ⁇ [0,1].
  • Li is the grating loss efficiency of the i-th reflection.
  • the period and duty ratio of the dot matrix structure are set to maximize the touch screen efficiency C d.
  • the present invention can provide an operator with a larger operating space, thereby enabling interaction with a large-size touch screen.
  • the lattice structure grating is used, the transmission loss of the coupled light in the optical waveguide layer is effectively reduced, thereby greatly improving the sensitivity of the touch screen.
  • Figures 1(a) and 1(b) are schematic diagrams of a touch screen based on a lattice structure grating of the present invention.
  • Figure 2 is a diagram showing the relationship between the incident angle and the grating period when the incident light is incident normally.
  • Fig. 3 is a graph showing the relationship between the corresponding ⁇ 1 level coupling efficiency and the grating period when the incident light is incident normally.
  • Figure 4 is a diagram showing the relationship between the corresponding single-pass loss and the grating period when the incident light is incident normally.
  • Fig. 5 is a schematic diagram showing the structure of the entire surface of the optical waveguide layer covered with a grating.
  • Fig. 6 is a schematic diagram of a grating with a lattice structure covering an optical waveguide layer.
  • Figures 7(a) and 7(b) are schematic diagrams of the first reflection position corresponding to the light spot with different lattice period selection.
  • Fig. 8 is a schematic diagram of the structure of the first embodiment of the present invention.
  • Fig. 9 is a schematic structural diagram of a second embodiment of the present invention.
  • Fig. 10 is a schematic diagram of the structure of the third embodiment of the present invention.
  • 201-laser light source 202-optical waveguide layer, 203-grating, 204-photodetector.
  • the touch screen of the present invention based on a lattice structure grating includes a laser light source 201, an optical waveguide layer 202, a grating 203 and a photodetector 204, so The grating described above is covered on the optical waveguide layer 202 or embedded in the optical waveguide layer 202 in a lattice structure.
  • the lattice structure is not limited to the rectangle shown in Figure 1, and can be any other graphic.
  • the photodetectors 204 are respectively arranged on the four side walls of the optical waveguide layer 202 or two adjacent side walls.
  • the grating 203 makes the light of the laser light source 201 with a specific wavelength become a waveguide mode that can be transmitted in the optical waveguide layer 202.
  • the laser enters the optical waveguide layer 202 through the grating 203 and is transmitted laterally in the optical waveguide layer.
  • the photodetector 204 causing the corresponding photodetector current to increase, so as to determine the position of the touch.
  • k 0 is the wave number in vacuum
  • n 0 is the refractive index of the incident medium
  • ⁇ is the incident angle of the incident light
  • T is the grating period
  • n eff is the effective refractive index of the waveguide
  • n 1 is the waveguide refractive index.
  • the grating period in order to make the +1-order diffracted light become the waveguide mode in the waveguide, the grating period must meet the following conditions:
  • the -1st order diffracted light should meet the following conditions:
  • ⁇ is the wavelength of incident light in vacuum.
  • Fig. 4 is a diagram showing the relationship between single-pass loss and grating period at normal incidence.
  • Single-pass loss refers to the coupling light at the boundary between the optical waveguide layer and the grating Loss caused by reflection at the place.
  • the touch screen efficiency is the ratio of the output power P 0 to the input power, and there is the following relationship:
  • C is the grating coupling efficiency
  • L is the single reflection loss efficiency
  • n is the number of reflections.
  • the loss is mainly due to the coupling of light in the waveguide when it reflects at the junction of the waveguide layer and the grating, a part of the light will be coupled out through the grating. This means that every time a reflection occurs at the junction, there will be Once loss, loss will increase as the size of the optical film becomes larger. Obviously, it is difficult to meet the efficiency required for large-screen touch control.
  • a grating touch screen based on a dot matrix structure is proposed.
  • the design of the lattice structure grating reduces the coupling efficiency, it greatly reduces the total loss, thereby greatly improving the efficiency of touch control.
  • T d is the period of the dot matrix grating
  • w j is the length of the grating part of the area j dot matrix
  • duty j is the duty ratio of the area j dot matrix.
  • k i is the loss coefficient
  • k i [0, 1].
  • the optimal lattice structure grating can be obtained, so that the efficiency of the touch screen is maximized, that is, P 0 is maximized.
  • the optimization process will be described in detail below. Because the value of k i is determined by the period T d of the lattice structure and the lattice duty ratio, the optimal efficiency optimization mainly optimizes the period and duty ratio of the lattice structure. Referring to Figure 7(a), suppose the upper limit of the period of the scanned lattice structure grating is:
  • N is a positive integer
  • the value of N should be such that the number of dots contained in the light spot is greater than or equal to one.
  • the appropriate scanning step size can be selected to obtain a set of equally spaced lattice structures Period, scan a different duty cycle in each scan period.
  • the different values of k i in formula (8) can be calculated by the program according to the geometric relationship, and the output power P 0 can be finally obtained.
  • a set of P 0 can be obtained, and then the largest P 0 can be screened out, and the corresponding dot matrix period and duty cycle can be obtained.
  • FIG. 8 is a schematic structural cross-sectional view of Embodiment 1 of a touch screen based on a lattice structure grating of the present invention.
  • the grating 203 is embedded in the optical waveguide layer 202 in a lattice structure in an embedded manner.
  • the photodetector 204 is provided on the four side walls of the optical waveguide layer 202 or two adjacent side walls.
  • the grating 203 is a one-dimensional structure, the optical waveguide layer is divided into upper and lower layers and the grating directions on the upper and lower optical waveguides are perpendicular to each other.
  • the grating structure and lattice on the upper and lower optical waveguides are arranged
  • the structure meets the maximum conditions of claim 1 and claim 2 in two aspects; when the grating 203 is a two-dimensional structure, preferably, the grating structure and the lattice structure in the X direction and the Y direction are set, and the two aspects meet the claims respectively. 1 and the maximum condition of claim 2.
  • a filter is attached to the sidewall of the optical waveguide layer 202 adjacent to the photodetector 204.
  • the optical waveguide layer 202 is a transparent material. Below the optical waveguide layer 202 are an isolation layer and a display screen, but the application scenarios are not limited to the display screen. The purpose of the isolation layer is to not affect the total reflection of the coupled light on the lower surface of the optical waveguide layer 202.
  • the laser light source emits laser light, which first passes through the grating 203.
  • the laser passes through the grating 203, a part of the light will be coupled into the optical waveguide layer 202, become a waveguide mode, and transmit laterally in the optical waveguide; most of the light will pass through the optical waveguide layer 202 longitudinally.
  • the coupled light propagates in the lateral direction and finally reaches the sidewall of the optical waveguide layer 202, it will be detected by the photodetector 204 located on the sidewall, and the light intensity detected by the photodetector 204 will increase. Powerful and small can determine where the touch occurs. This solution can realize non-contact touch.
  • Embodiment 9 is a schematic structural cross-sectional view of Embodiment 2 of a touch screen based on a lattice structure grating of the present invention.
  • this embodiment can protect the grating 203 and improve the coupling efficiency of the grating by plating a layer of high refractive index medium on the grating 203 structure.
  • the photodetector 204 is provided on the four side walls of the optical waveguide layer 202 or two adjacent side walls.
  • the grating 203 is a one-dimensional structure, the optical waveguide layer is divided into upper and lower layers and the grating directions on the upper and lower optical waveguides are perpendicular to each other.
  • the grating structure and lattice on the upper and lower optical waveguides are arranged
  • the structure meets the maximum conditions of claim 1 and claim 2 in two aspects; when the grating 203 is a two-dimensional structure, preferably, the grating structure and the lattice structure in the X direction and the Y direction are set, and the two aspects meet the claims respectively. 1 and the maximum condition of claim 2.
  • a filter is attached to the sidewall of the optical waveguide layer 202 adjacent to the photodetector 204.
  • the optical waveguide layer 202 is a transparent material. Below the optical waveguide layer 202 are an isolation layer and a display screen, but the application scenarios are not limited to the display screen. The purpose of the isolation layer is to not affect the total reflection of the coupled light on the lower surface of the optical waveguide layer 202.
  • the working mode is similar to the first embodiment, and non-contact touch can be realized.
  • FIG. 10 is a schematic diagram of a cross-sectional structure of Embodiment 3 of a touch screen based on a lattice structure grating of the present invention.
  • This embodiment adopts a double-layer optical waveguide layer 202 and a grating 203 structure.
  • the grating 203 is a two-dimensional structure. This structure can effectively improve the efficiency of the touch screen.
  • an embedded method is used to The grating 203 is embedded in the optical waveguide layer 202 in a lattice structure.
  • the photodetector 204 is provided on the four side walls of the optical waveguide layer 202 or two adjacent side walls.
  • a filter is attached to the sidewall of the optical waveguide layer 202 adjacent to the photodetector 204.
  • the optical waveguide layer 202 is a transparent material.
  • Below the optical waveguide layer 202 are an isolation layer and a display screen, but the application scenarios are not limited to the display screen. The purpose of the isolation layer is to not affect the total reflection of the coupled light on the lower surface of the optical waveguide layer 202.
  • the laser light source emits laser light, which first passes through the upper grating 203.
  • the laser passes through the grating 203, a part of the light will be coupled into the optical waveguide layer 202, become a waveguide mode, and transmit laterally in the upper optical waveguide layer 202; most of the light will pass through the upper optical waveguide layer 202 longitudinally, and then pass through the lower grating 203.
  • a part of the light will be coupled into the lower optical waveguide layer 202 to become a waveguide mode and be transmitted horizontally in the lower optical waveguide layer 202; most of the light will pass through the lower optical waveguide layer 202 longitudinally, and when the coupled light is transmitted horizontally, it finally reaches
  • the sidewall of the optical waveguide layer 202 is detected, it will be detected by the photodetector 204 located on the sidewall, and the light intensity detected by the photodetector 204 will increase. According to the position of the photodetector and its intensity, the touch can be determined position. This solution can effectively improve the efficiency and accuracy of the touch screen and can realize non-contact touch.
  • the present invention uses the diffraction of the grating to make the laser of a specific wavelength become a waveguide mode that can be transmitted in the waveguide.
  • the photoelectric sensor judges the position of the touch according to the intensity of the detected light. Realize non-contact touch.

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  • General Engineering & Computer Science (AREA)
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Abstract

一种基于点阵结构分布的光栅触控屏，包括激光光源（201）、光波导层（202）、光栅（203）和光电探测器（204），通过在光波导层（202）上合理设置点阵结构分布的光栅（203），使激光光源通过光栅触控屏到达周边光电探测器（204）的检测光的效率最大，从而有效地提高了触控屏的灵敏度。

Description

基于点阵结构分布光栅的触控屏 技术领域
本发明涉及信息显示，特别是一种基于点阵结构分布光栅的触控屏。
背景技术
根据触控屏不同的技术原理，可以分为四种基本类型：电阻式触控屏、电容式触控屏、表面声波式触控屏和红外触控屏。
电阻式触控屏是利用两层高透明的导电层组成触控屏，通常用一种弹性材料将两导电层隔开，当触控屏上的压力足够大，两层之间发生接触，传感器读到触点电压，以此来确定触控点坐标。电阻屏具有高精度、低成本等优势，并且屏幕不受灰尘、水汽和油污影响，可以用任何物体来触摸，但是其透光率低，不耐磨。
电容式触控屏是玻璃屏内表面和夹层各涂一层ITO,当手指触摸电容屏时，由于人体电场，手指和工作面形成一个耦合电容，手指会吸走一个很小的电流，控制器通过电流变化来确定触摸位置信息。电容屏具有耐磨损和寿命长的优势，但当环境温度、湿度改变时会发生漂移，易受电磁信号影响，而且必须是导体才能触控。
表面声波式触控屏是由触摸屏、声波发生器、反射器和声波接收器组成，当手指触摸屏幕时，触点上的声波会被阻止，由此确定触控坐标。表面声波式触控屏光学性能好和耐刮擦，但易受灰层、水滴和油污等影响。
上述三种触控屏主要应用于中小尺寸显示设备。
红外触控屏是在显示器四边排布红外发射管和红外接收管，当用户触摸屏幕时，手指就会挡住经过该位置的红外线，据此可以判断出触控点在屏幕上的位置。红外触控屏目前在大尺寸触控市场占据主导地位，但仍然是传统的接触式触控，因此触摸屏尺寸受到限制。
上述的触控屏都要求操作者和触控屏之间进行接触式交互，这种接触式交互必须要考虑操作者可进行交互的物理限制，这无疑限制了触控屏尺寸的大小。目前市场上存在的非接触式交互主要基于图像处理的人机交互，但这种交互方式存在成本高、算法复杂和延迟大等缺点。
目前有一种基于光栅的光学触控屏(专利申请号：201410203219.1)，这种触控屏虽然无需额外提供光源，但显示光经过光栅多次反射之后，光强会显著下降，由 于只利用了显示光，这种触控屏的效率及触控精度较低。另一方面，由于光波导上整面都有光栅，会带来较大的传输损耗。
发明内容
本发明的目的在于针对上述现有技术的不足，提供一种基于点阵结构分布光栅的触控屏，使用激光光源作为交互媒介触控的检测光，可以给操作者提供更大的操作空间，从而能够实现与大尺寸触控屏的交互。此外，由于使用了点阵结构光栅，有效地降低了耦合光在光波导层中的传输损耗，从而极大的提高触控屏的效率、透光性能以及灵敏度。
本发明的技术解决方案如下：
一种基于点阵结构分布的光栅触控屏，包括激光光源、光波导层、光栅和光电探测器，其特点在于，所述的光栅点阵结构地分布在所述的光波导层上，在所述的光波导层的周边或两相邻边设置所述的光电探测器，所述的激光光源输出特定波长的激光作为触控的检测光，选择所述的光栅的周期、占空比、光栅高度、控制反射次数n、损耗效率和耦合效率，使触控屏的效率最大。
当所述的光栅为一维结构时，所述的光波导层分为上下两层，在上下两光波导层上设置点阵的光栅结构，且上下两层光波导上的光栅方向互相垂直；当光栅为二维结构时，在X方向和Y方向设置点阵的光栅结构。
在点阵结构单元里的光栅是单周期或渐变周期。
当所述的光波导层的长和宽相等时，则在所述的光波导层的两相邻边设置所述的光电探测器；当所述的光波导层的长和宽不相等时，则在所述的光波导层两个相对的短边和其中一个长边设置所述的光电探测器。
在所述的光波导层与所述的光电探测器之间设有滤光片。
在所述的光波导层的下方依次为隔离层和显示屏。
光栅的周期能够使得激光耦合进光波导层，光栅整面覆盖在光波导层时，触控屏的效率为:
Figure PCTCN2020076907-appb-000001
其中，C j为区域j光栅的耦合效率，区域j的范围是[(j-1)Nd，jNd),d为单次反射的传输距离，N为正整数，
Figure PCTCN2020076907-appb-000002
n为耦合光在波导层与光栅交界处发生反射的次数。L i为第i次反射的光栅损耗效率。优选的，设置合适的光栅周期、占空比和光栅高度控制反射次数n、损耗效率L i和耦合效率C j使得触控屏的效率C t最大。
所述的光栅以点阵结构分布在光波导层上，点阵与点阵之间不存在光栅。
点阵结构分布的光栅触控屏的效率可表示为：
Figure PCTCN2020076907-appb-000003
其中，C j为区域j光栅的耦合效率,duty j为区域j点阵结构的占空比，区域j的范围是[(j-1)Nd，jNd),d为单次反射的传输距离，N为正整数，
Figure PCTCN2020076907-appb-000004
n为耦合光在波导层与光栅交界处发生反射的次数。k i为损耗系数，k i∈[0，1]。L i为第i次反射的光栅损耗效率。优选的，设置的点阵结构的周期和占空比，使得触控屏效率C d最大。
与现有技术相比，本发明的有益效果如下：
本发明通过使用激光光源作为交互媒介，可以给操作者提供更大的操作空间，从而能够实现与大尺寸触控屏的交互。此外，由于使用了点阵结构光栅，有效地降低了耦合光在光波导层中的传输损耗，从而极大的提高触控屏的灵敏度。
附图说明
图1(a)，1(b)是本发明基于点阵结构光栅的触控屏的示意图。
图2是入射光正入射时，入射角与光栅周期的关系图。
图3是入射光正入射时，对应的±1级耦合效率与光栅周期的关系图。
图4是入射光正入射时，对应的单次损耗与光栅周期的关系图。
图5是光波导层之上整面覆盖光栅的结构示意图。
图6是光波导层之上覆盖点阵结构光栅示意图。
图7(a)，7(b)是不同点阵周期选取，光斑对应的第一次反射位置示意图。
图8是本发明第一实施例的结构示意图。
图9是本发明第二实施例的结构示意图。
图10是本发明第三实施例的结构示意图。
图中：201-激光光源，202-光波导层，203-光栅，204-光电探测器。
具体实施方式
下面结合实例和附图对本发明作详细说明，但不应以此限制本发明的保护范围。
先请参阅图1(a),图1(b),由图可见，本发明基于点阵结构光栅的触控屏，包括激光光源201、光波导层202、光栅203和光电探测器204，所述的光栅以点阵结构覆盖在所述光波导层202之上或者内嵌在光波导层202中。其中点阵结构不限 于图1的矩形，可以是其他任意图形。所述的光电探测器204分别被设于光波导层202的四个侧壁或者相邻的两个侧壁。
所述的光栅203使特定波长的激光光源201的光成为可在光波导层202内传输的波导模，当产生触控时，激光通过光栅203进入光波导层202并在光波导层中横向传输，最终到达所述的光电探测器204，导致相应光电探测器电流变大，以此判断触控发生的位置。下面通过理论分析证明本发明的可行性。
光栅波导的+1级和-1级衍射方程：
Figure PCTCN2020076907-appb-000005
其中，k 0为真空中的波数，n 0是入射介质的折射率，θ为入射光的入射角，T为光栅周期，n eff为波导有效折射率，n 1为波导折射率。公式(1)中绝对值部分，对于+1级衍射光取正号，-1级衍射光取负号。并且有n 1＞n 0,
Figure PCTCN2020076907-appb-000006
由公式(1)变形可得，要使+1级衍射光成为波导中的波导模式，光栅周期因满足以下条件：
Figure PCTCN2020076907-appb-000007
同理-1级衍射光应该满足以下条件：
Figure PCTCN2020076907-appb-000008
其中，λ为真空中入射光波长。
当入射光波长λ和入射角度θ确定时，只要光栅周期T满足公式(2)、公式(3)，入射光便能成为波导模并在光波中横向传输。当波导折射率n 1＝1.59，入射光波长λ＝532nm时，入射角度θ与光栅周期T关系如图2所示，据此可以选择合适的光栅周期T。图3是正入射时即θ＝0时，光栅耦合效率与光栅周期的关系图，图4是正入射时单次损耗与光栅周期的关系图，单次损耗是指耦合光在光波导层与光栅交界处反射时产生的损耗。
首先讨论在光波导层上整面覆盖光栅时触控屏的效率，此处讨论的光栅为均匀光栅，参阅图5，D为耦合光在波导层中传输的总距离，d为单次反射的传输距离，h为波导层厚度，
Figure PCTCN2020076907-appb-000009
为衍射角，设输入光强为I,光斑面积为A,那么触控屏效率即输出功率P 0和输入功率比值，存在以下关系:
P 0＝P i*c*(1-L) n         (4)
P i＝I*A          (5)
Figure PCTCN2020076907-appb-000010
Figure PCTCN2020076907-appb-000011
其中，C为光栅耦合效率，L为单次反射损耗效率，n为反射的次数。
对于大屏触控，损耗的产生主要是由于波导中的耦合光在波导层与光栅交界处反射时会有一部分光通过光栅耦合出去，这就意味着在交界处每发生一次反射，就会产生一次损耗，损耗会随着光学膜尺寸变大而增加，显然这很难满足大屏触控所要求的效率。
为了降低损耗，提高触控屏的效率，于是提出了基于点阵结构的光栅触控屏。点阵结构光栅的设计，虽然降低了耦合效率，但极大地降低了总的损耗，从而极大地提高了触控的效率。
接下来讨论在光波导层上以点阵结构覆盖光栅时触控屏的效率，以矩形点阵结构为例，但不应以此限制本发明的保护范围。参阅图6，T d为点阵光栅的周期，w j为区域j点阵有光栅部分长度，设duty j为区域j点阵占空比，根据公式(4)，那么矩形点阵光栅的输出功率可表示为：
Figure PCTCN2020076907-appb-000012
Figure PCTCN2020076907-appb-000013
其中k i为损耗系数，k i∈[0，1]。
通过具体的算法优化可以得出最优的点阵结构光栅，使得触控屏的效率最大即P 0最大。下面将具体介绍优化过程，因为k i的值由点阵结构的周期T d和点阵占空比决定，所以最优效率优化主要对点阵结构的周期和占空比进行优化。参阅图7(a),假设扫描的点阵结构光栅的周期上限为：
Figure PCTCN2020076907-appb-000014
其中N为正整数，所取的N值应该使得光斑包含的点阵个数大于等于1个。参阅图7(b),设扫描的点阵结构光栅的周期下限为：
Figure PCTCN2020076907-appb-000015
当T dmin≤T d≤T dmax时，第一次全反射的光斑便可以落在点阵结构的不同位置，可以根据实际需求，选取合适的扫描步长，获取一组等间距的点阵结构周期，在每一个扫描周期下扫描不同的占空比。当确定点阵周期和占空比时，便可以根据几何关 系由程序计算出公式(8)中不同的k i值，最终便可求得输出功率P 0。依次类推，可求一组P 0，然后筛选出最大的P 0，获得与其对应的点阵周期和占空比。
下面，通过具体实施列来详细说明。
实施例1
图8为本发明基于点阵结构光栅的触控屏的实施例1的结构截面示意图。为了保护光栅203，采用了内嵌的方式将光栅203以点阵结构内嵌于光波导层202中。光电探测器204被设于光波导层202的四个侧壁或者相邻的两个侧壁。当光栅203为一维结构时，所述的光波导层分为上下两层且上下两层光波导上的光栅方向互相垂直，优选的，设置的上下两层光波导上的光栅结构和点阵结构，两方面分别满足权利要求1和权利要求2的最大条件；当光栅203为二维结构时，优选的，设置的X方向和Y方向的光栅结构和点阵结构，两方面分别满足权利要求1和权利要求2的最大条件。为了减少环境光干扰，在光波导层202紧邻光电探测器204的侧壁贴有滤光片。光波导层202是透明材料。光波导层202下方分别为隔离层和显示屏，但应用场景不限于显示屏，隔离层的目的是为了不影响耦合光在光波导层202下表面全反射。
工作时，激光光源发出激光，首先通过光栅203。在激光通过光栅203时，有一部分光会被耦合进光波导层202，成为波导模，并在光波导中横向传输；大部分光会纵向通过光波导层202。当耦合光沿横向传输最终到达光波导层202侧壁时，会被位于侧壁的光电探测器204检测，光电探测器204检测到的光强会变大，根据光电探测器的位置及其光强大小可确定触控发生的位置。本方案可实现非接触式触控。
实施例2
图9为本发明基于点阵结构光栅的触控屏的实施例2的结构截面示意图。与第一个实施例不同的是，本实施例通过在光栅203结构上镀一层高折射率介质，可以保护光栅203和提高光栅耦合效率。光电探测器204被设于光波导层202的四个侧壁或者相邻的两个侧壁。当光栅203为一维结构时，所述的光波导层分为上下两层且上下两层光波导上的光栅方向互相垂直，优选的，设置的上下两层光波导上的光栅结构和点阵结构，两方面分别满足权利要求1和权利要求2的最大条件；当光栅203为二维结构时，优选的，设置的X方向和Y方向的光栅结构和点阵结构，两方面分别满足权利要求1和权利要求2的最大条件。为了减少环境光干扰，在光波导层202紧邻光电探测器204的侧壁贴有滤光片。光波导层202是透明材料。光波导层202的下方分别为隔离层和显示屏，但应用场景不限于显示屏，隔离层的目的是为了不影响耦合光在光波导层202下表面全反射。
工作方式类似第一实施例，可实现非接触式触控。
实施例3
图10为本发明基于点阵结构光栅的触控屏的实施例3的截面结构示意图。本实施例采用双层光波导层202和光栅203结构，光栅203为二维结构，采用这种结构可以有效的提高触控屏的效率，和第一实施例一样，采用了内嵌的方式将光栅203以点阵结构内嵌于光波导层202中。光电探测器204被设于光波导层202的四个侧壁或者相邻的两个侧壁。为了减少环境光干扰，在光波导层202紧邻光电探测器204的侧壁贴有滤光片。光波导层202是透明材料。光波导层202下方分别为隔离层和显示屏，但应用场景不限于显示屏，隔离层的目的是为了不影响耦合光在光波导层202下表面全反射。
工作时，激光光源发出激光，首先通过上层光栅203。在激光通过光栅203时，有一部分光会被耦合进光波导层202，成为波导模，并在上层光波导层202中横向传输；大部分光会纵向通过上层光波导层202，之后通过下层光栅203，有一部分光会被耦合进下层光波导层202，成为波导模，并在下层光波导层202中横向传输；大部分光会纵向通过下层光波导层202，当耦合光沿横向传输最终到达光波导层202侧壁时，会被位于侧壁的光电探测器204检测，光电探测器204检测到的光强会变大，根据光电探测器的位置及其光强大小可确定触控发生的位置。本方案可有效提高触控屏的效率和精度以及可实现非接触式触控。
实验表明，本发明利用光栅的衍射，使特定波长的激光成为可在波导内传输的波导模，作为触控的检测光，由光电传感器根据检测到的光强大小判断发生触控的位置，可以实现非接触式触控。通过对光栅采用内嵌和镀膜的方法，有效的保证了触控屏的使用寿命，同时通过点阵结构光栅的使用，有效提高触控屏的灵敏度

Claims (6)

  1. 一种基于点阵结构分布的光栅触控屏，包括激光光源(201)、光波导层(202)、光栅(203)和光电探测器(204)，其特征在于，所述的光栅(203)点阵结构地分布在所述的光波导层(202)上，在所述的光波导层(202)的周边或两相邻边设置所述的光电探测器(204)，所述的激光光源(201)输出特定波长的激光作为触控的检测光，选择所述的光栅(203)的周期、占空比、光栅高度、控制反射次数n、损耗效率和耦合效率，使触控屏的效率最大。
  2. 根据权利要求1所述的基于点阵结构分布的光栅触控屏，其特征在于，当所述的光栅(203)为一维结构时，所述的光波导层(202)分为上下两层，在上下两光波导层上设置点阵的光栅结构，且上下两层光波导上的光栅方向互相垂直；当光栅为二维结构时，在X方向和Y方向设置点阵的光栅结构。
  3. 根据权利要求1所述的基于点阵结构分布的光栅触控屏，其特征在于，在点阵结构单元里的光栅(203)是单周期或渐变周期。
  4. 根据权利要求1所述的基于点阵结构分布的光栅触控屏，其特征在于，当所述的光波导层(202)的长和宽相等时，则在所述的光波导层的两相邻边设置所述的光电探测器(204)；当所述的光波导层(202)的长和宽不相等时，则在所述的光波导层两个相对的短边和其中一个长边设置所述的光电探测器(204)。
  5. 根据权利要求1所述的基于点阵结构分布的光栅触控屏，其特征在于，在所述的光波导层(202)与所述的光电探测器(204)之间设有滤光片。
  6. 根据权利要求1至5任一项所述的基于点阵结构分布的光栅触控屏，其特征在于，在所述的光波导层(202)的下方依次为隔离层和显示屏。
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