CN114660696A - Light guide plate with infrared ray transmitting and visible light reflecting functions and backlight module - Google Patents

Light guide plate with infrared ray transmitting and visible light reflecting functions and backlight module Download PDF

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Publication number
CN114660696A
CN114660696A CN202011522772.3A CN202011522772A CN114660696A CN 114660696 A CN114660696 A CN 114660696A CN 202011522772 A CN202011522772 A CN 202011522772A CN 114660696 A CN114660696 A CN 114660696A
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guide plate
light guide
substrate
visible light
infrared rays
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张彦
高斌基
夏寅
刘建凯
付坤
李刚
唐海江
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Ningbo Exciton Technology Co Ltd
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Ningbo Exciton Technology Co Ltd
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    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033Means for improving the coupling-out of light from the light guide
    • G02B6/005Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G02B6/0055Reflecting element, sheet or layer
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0065Manufacturing aspects; Material aspects
    • GPHYSICS
    • G02OPTICS
    • G02FOPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333Constructional arrangements; Manufacturing methods
    • G02F1/1335Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336Illuminating devices
    • G02F1/133615Edge-illuminating devices, i.e. illuminating from the side

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  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Nonlinear Science (AREA)
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Abstract

The invention relates to the technical field of LCD backlight sources, simultaneously covers the field of fingerprint identification of LCD backlight sources, and particularly relates to a light guide plate with functions of transmitting infrared rays and reflecting visible light and a backlight module. In order to solve the problem that the existing backlight module can not transmit infrared rays, the invention provides a light guide plate with the functions of transmitting infrared rays and reflecting visible light and a backlight module. The light guide plate sequentially comprises a substrate and a functional layer from top to bottom, wherein the functional layer is an inorganic matter coating, the inorganic matter coating is composed of a high-refractive-index inorganic matter A and a low-refractive-index inorganic matter B, the refractive index of the inorganic matter A is larger than that of the inorganic matter B, the inorganic matter coating A and the inorganic matter coating B are alternately deposited on the surface of the light guide plate, the deposition sequence is ABABA. The backlight module provided by the invention can transmit infrared rays and reflect visible light, is thinner in thickness and stronger in warping resistance, and can be applied to a fingerprint identification device.

Description

Light guide plate with infrared ray transmitting and visible light reflecting functions and backlight module
Technical Field
The invention relates to the technical field of LCD backlight sources, simultaneously covers the field of fingerprint identification of LCD backlight sources, and particularly relates to a light guide plate with functions of transmitting infrared rays and reflecting visible light and a backlight module.
Technical Field
With the rapid development of display technology, the demand for display screens is also more on large-area screens (referred to as full-screen in the industry). The coming of the full screen era squeezes the position of the capacitive or ultrasonic fingerprint identification device used at present, and the efficient utilization of the front screen is particularly important.
The optical fingerprint identification device under the screen well solves the problem and handles the position conflict between the full screen and the fingerprint identification device.
A TFT-LCD (thin film transistor liquid crystal display, an abbreviation of a head of a liquid crystal display) is a non-self-luminous display technology device, and a backlight source (also called a backlight module) is required to be present to drive and display an image.
The LCD backlight module comprises a reflecting film, a light guide plate, a diffusion film and a brightness enhancement film. Especially, the linear light source of LED lamp strip will be turned into the area source through the effect of light guide plate, and partly light will be followed the bottom of light guide plate and escaped simultaneously, and the reflective coating reflects this part of light back to backlight unit with high efficiency and low loss ground to reduce the optical loss, promote backlight unit's luminance.
The reflective film reflects visible light (light with a wavelength of 380nm-780nm generally) back to the backlight module, and simultaneously, infrared light (light with a wavelength of more than 780nm generally) is also reflected. The signals identified and received by the fingerprint sensor come from infrared rays, so that the signals cannot be received, and the fingerprint identification capability is lost.
Disclosure of Invention
In order to solve the problem that the existing backlight module can not transmit infrared rays, the invention provides a light guide plate with the functions of transmitting infrared rays and reflecting visible light and a backlight module. The light guide plate with the functions of transmitting infrared rays and reflecting visible light combines the light guide plate and a reflecting film in a backlight module into a whole, and the functional layer is directly attached to the surface of one side of the light guide plate. Compared with the traditional backlight module, the light guide plate with the functions of transmitting infrared rays and reflecting visible light provided by the invention can transmit infrared rays and reflect visible light, and the problem that the existing backlight module reflects visible light and reflects infrared rays is solved. The light guide plate provided by the invention has the advantages of thinner thickness and stronger warping resistance.
The light guide plate with the functions of transmitting infrared rays and reflecting visible light sequentially comprises a substrate and a functional layer from top to bottom.
The substrate is a light guide plate for an LCD backlight.
The material of the substrate is selected from Polycarbonate (PC), polymethyl methacrylate (PMMA) or colorless transparent polyimide (CPI). The thickness of the substrate is 0.075mm-0.36 mm.
The light guide plate is formed in an injection molding mode, and the corresponding shape and thickness are obtained.
The functional layer is an inorganic plating layer. The functional layer is an inorganic coating prepared by vacuum magnetron sputtering or vacuum evaporation.
The inorganic coating is composed of a high-refractive index inorganic substance A and a low-refractive index inorganic substance B, wherein the refractive index of the inorganic substance A is greater than that of the inorganic substance B.
The thickness of the inorganic coating A is 10-300 nm. Further, the thickness of the inorganic plating layer A is 190 nm.
The inorganic coating A is made of metal oxide, and further, the inorganic coating A is made of one or a combination of at least two of titanium oxide, niobium pentoxide, aluminum oxide and zinc oxide. Furthermore, the targets used for preparing the titanium oxide, niobium pentoxide, aluminum oxide and zinc oxide coating are respectively a titanium oxide target, a niobium pentoxide target, an aluminum oxide target and a zinc oxide target. Further, the material of the inorganic plating layer a is niobium pentoxide.
The thickness of the inorganic coating B is 10-300 nm. Further, the thickness of the inorganic plating layer B was 270 nm.
The inorganic coating B is made of one or the combination of at least two of silicon oxide, magnesium fluoride and zinc sulfide. Furthermore, the targets used for preparing the silicon oxide coating, the magnesium fluoride coating and the zinc sulfide coating are respectively a silicon target, a magnesium fluoride target and a zinc sulfide target. Further, the material of the inorganic plating layer B is silicon oxide.
The inorganic plating layer A and the inorganic plating layer B are alternately deposited on the surface of the light guide plate, the deposition sequence is ABABA. Further, the number of deposition layers was 48.
The invention provides a light guide plate with the functions of transmitting infrared rays and reflecting visible light, which sequentially comprises a substrate and a functional layer from top to bottom; the substrate is made of Polycarbonate (PC), and the thickness of the substrate is 0.36 mm; the functional layer is an inorganic matter coating which is composed of a high-refractive-index inorganic matter A and a low-refractive-index inorganic matter B; the thickness of the inorganic coating A is 190nm, and the material of the inorganic coating A is niobium pentoxide; the thickness of the inorganic coating B is 270nm, and the material of the inorganic coating B is silicon oxide; the inorganic plating layers A and the inorganic plating layers B are alternately deposited on the surface of the light guide plate, the deposition sequence is ABABA. The foregoing technical solution includes example 7.
Light is an electromagnetic wave and has wave property, and the interference phenomenon is one of the basic characteristics of the wave property of light. Only the light waves emitted by two coherent light sources with the same frequency, the same vibration direction or the same vibration component, the same phase or the constant phase difference are coherent waves. The reflected light and the transmitted light between the film layers are coherent light, and the interference condition is met. The refractive index of light of different wavelengths is different in the same medium. Shorter wavelength light (e.g., visible light band) has a larger refractive index, while longer wavelength light (e.g., infrared band) has a smaller refractive index. Since the visible light and the infrared light have different optical path differences when passing through media having different refractive indexes due to the difference in wavelength, the interference is constructive and the interference is destructive, and thus the transmission and reflection of the two are also different.
The invention provides a preparation method of a light guide plate with the functions of transmitting infrared rays and reflecting visible light, which comprises the following steps:
(1) purging the surface of the substrate for 3-5min by nitrogen to remove larger particle impurities;
(2) cleaning the surface of the substrate by argon plasma bombardment for 10-15min, removing surface oxides, improving the surface energy of the substrate and improving the adhesive force between a coating and the substrate;
(3) depositing an inorganic matter coating A on the substrate by utilizing high-vacuum medium-frequency magnetron sputtering;
(4) depositing an inorganic matter coating layer B on the substrate by utilizing high-vacuum medium-frequency magnetron sputtering;
(5) the inorganic plating layers A and the inorganic plating layers B are alternately deposited in this way to the desired number of layers.
The coating a is a high refractive index material derived from metal oxides such as aluminum oxide, titanium oxide, niobium oxide, etc., which have better adhesion to PMMA, PC, etc., and therefore, an inorganic coating a is deposited on the substrate first.
The light guide plate with the functions of transmitting infrared rays and reflecting visible light is obtained through the steps of sputtering and depositing in sequence, and the light guide plate has the functions of efficiently reflecting visible light and transmitting infrared rays.
The invention also provides a backlight module which comprises the light guide plate with the functions of transmitting infrared rays and reflecting visible light.
Further, the backlight module does not comprise a separate reflecting film.
Furthermore, the backlight module comprises a light source, a light guide plate with the functions of transmitting infrared rays and reflecting visible light, a diffusion film and a brightness enhancement film. The light guide plate converts the light that the light source sent into the area source, simultaneously, reflects the module back with partial effluence visible light high-efficiently, and the infrared ray then normally sees through, and the diffusion barrier is used for improving the homogeneity of light, and the membrane that adds lustre to is used for gathering light in order to improve backlight unit's luminance.
Compared with the prior art, the invention has the following excellent effects:
(1) the light guide plate with the functions of transmitting infrared light and reflecting visible light is obtained by combining the light guide plate with the reflection function layer, and the thickness of the backlight module is greatly reduced due to the absence of a separate reflection film, so that the backlight module is more in line with the light and thin design and meets the market demand;
(2) because the existence of the independent reflection film is avoided, the escaped light rays do not pass through an air layer interface, the optical path is shortened, and the absorption of the light rays is weakened, so that the utilization rate of the light rays is improved;
(3) the multilayer coating film can generate large internal stress, so that the single reflecting film is seriously warped, and the assembly and the use of the backlight are influenced. The invention adopts multilayer coating films to be attached to the surface of the light guide plate, and the light guide plate is strong in internal stress resistance due to the special material of the light guide plate, so that the light guide plate with the functions of transmitting infrared rays and reflecting visible light is very flat and meets the market requirement;
(4) the light guide plate with the functions of transmitting infrared rays and reflecting visible light has a reflectivity of more than 95% for the visible light and a transmissivity of more than 85% for the infrared rays, and is very favorable for improving screen brightness and collecting signals by a fingerprint identification device.
The light guide plate with the infrared ray transmitting and visible light reflecting functions can transmit infrared rays and reflect visible light, solves the problem that the existing backlight module reflects visible light and reflects infrared rays at the same time, and can be applied to a fingerprint identification device. Furthermore, the light guide plate provided by the invention is thinner in thickness and stronger in warping resistance. The backlight module provided by the invention can transmit infrared rays and reflect visible light, is thinner in thickness and stronger in warping resistance, and can be applied to a fingerprint identification device.
Drawings
Fig. 1 is a schematic cross-sectional structure view of a light guide plate with the functions of transmitting infrared rays and reflecting visible light provided by the present invention.
10: light guide plate
20: coating A
30: coating B
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and examples.
As shown in fig. 1, the light guide plate with the functions of transmitting infrared rays and reflecting visible light provided by the invention comprises a light guide plate 10, wherein a plating layer a20 and a plating layer B30 are alternately attached to one side of the light guide plate 10.
Example 1
The light guide plate with the functions of transmitting infrared rays and reflecting visible light is provided, the substrate is made of Polycarbonate (PC), the thickness of the substrate is 0.36mm, and the preparation method comprises the following steps:
(1) purging the surface of the substrate for 3min by nitrogen to remove larger granular impurities;
(2) the vacuum degree of a coating chamber is 0.1mbar, the argon flow is 20sccm, the negative bias power supply voltage is 700V, the argon plasma bombards and cleans the surface of the substrate for 10min, surface oxides are removed, the surface energy of the substrate is improved, and the adhesive force between a coating and the substrate can be improved;
(3) depositing a niobium pentoxide coating A on the substrate by high-vacuum medium-frequency magnetron sputtering, wherein the flow of argon is 120sccm, the flow of oxygen is 60sccm, starting a medium-frequency sputtering power supply loaded on a niobium pentoxide target, controlling the power at 12KW, and depositing the niobium pentoxide coating A with the thickness of 190 nm;
(4) depositing silicon dioxide B on the substrate by using high-vacuum medium-frequency magnetron sputtering, wherein the flow of argon is 100sccm, the flow of oxygen is 80sccm, starting a medium-frequency sputtering power supply loaded on a silicon target, controlling the power to be 17KW, and depositing a silicon dioxide coating B with the thickness of 270 nm;
(5) repeating the step (3) and the step (4), and thus alternately depositing the niobium pentoxide coating layer A and the silicon dioxide coating layer B for 2 periods (the total number of deposited layers is 4);
example 2
The light guide plate with the functions of transmitting infrared rays and reflecting visible light is provided, the substrate is made of Polycarbonate (PC), the thickness of the substrate is 0.36mm, and the preparation method comprises the following steps:
(1) purging the surface of the substrate for 3min by nitrogen to remove larger granular impurities;
(2) the vacuum degree of a coating chamber is 0.1mbar, the argon flow is 20sccm, the negative bias power supply voltage is 700V, the argon plasma bombards and cleans the surface of the substrate for 10min, surface oxides are removed, the surface energy of the substrate is improved, and the adhesive force between a coating and the substrate can be improved;
(3) depositing a niobium pentoxide coating A on the substrate by high-vacuum medium-frequency magnetron sputtering, wherein the flow of argon is 120sccm, the flow of oxygen is 60sccm, starting a medium-frequency sputtering power supply loaded on a niobium pentoxide target, controlling the power at 12KW, and depositing the niobium pentoxide coating A with the thickness of 190 nm;
(4) depositing silicon dioxide B on the substrate by using high-vacuum medium-frequency magnetron sputtering, wherein the flow of argon is 100sccm, the flow of oxygen is 80sccm, starting a medium-frequency sputtering power supply loaded on a silicon target, controlling the power to be 17KW, and depositing a silicon dioxide coating B with the thickness of 270 nm;
(5) repeating the step (3) and the step (4), and thus alternately depositing the niobium pentoxide coating layer A and the silicon dioxide coating layer B for 4 periods (the total number of layers is 8);
example 3
The light guide plate with the functions of transmitting infrared rays and reflecting visible light is provided, the substrate is made of Polycarbonate (PC), the thickness of the substrate is 0.36mm, and the preparation method comprises the following steps:
(1) purging the surface of the substrate for 3min by nitrogen to remove larger granular impurities;
(2) the vacuum degree of a coating chamber is 0.1mbar, the argon flow is 20sccm, the negative bias power supply voltage is 700V, the argon plasma bombards and cleans the surface of the substrate for 10min, the surface oxide is removed, the surface energy of the substrate is improved, and the adhesive force between the coating and the substrate can be improved;
(3) depositing a niobium pentoxide coating A on the substrate by high-vacuum medium-frequency magnetron sputtering, wherein the flow of argon is 120sccm, the flow of oxygen is 60sccm, starting a medium-frequency sputtering power supply loaded on a niobium pentoxide target, controlling the power at 12KW, and depositing the niobium pentoxide coating A with the thickness of 190 nm;
(4) depositing silicon dioxide B on the substrate by using high-vacuum medium-frequency magnetron sputtering, wherein the flow of argon is 100sccm, the flow of oxygen is 80sccm, starting a medium-frequency sputtering power supply loaded on a silicon target, controlling the power to be 17KW, and depositing a silicon dioxide coating B with the thickness of 270 nm;
(5) repeating the step (3) and the step (4), and thus alternately depositing the niobium pentoxide coating layer A and the silicon dioxide coating layer B for 6 periods (the total number of layers is 12);
example 4
The light guide plate with the functions of transmitting infrared rays and reflecting visible light is provided, the substrate is made of Polycarbonate (PC), the thickness of the substrate is 0.36mm, and the preparation method comprises the following steps:
(1) purging the surface of the substrate for 3min by nitrogen to remove larger granular impurities;
(2) the vacuum degree of a coating chamber is 0.1mbar, the argon flow is 20sccm, the negative bias power supply voltage is 700V, the argon plasma bombards and cleans the surface of the substrate for 10min, surface oxides are removed, the surface energy of the substrate is improved, and the adhesive force between a coating and the substrate can be improved;
(3) depositing a niobium pentoxide coating A on the substrate by high-vacuum medium-frequency magnetron sputtering, wherein the flow of argon is 120sccm, the flow of oxygen is 60sccm, starting a medium-frequency sputtering power supply loaded on a niobium pentoxide target, controlling the power at 12KW, and depositing the niobium pentoxide coating A with the thickness of 190 nm;
(4) depositing silicon dioxide B on the substrate by using high-vacuum medium-frequency magnetron sputtering, wherein the flow of argon is 100sccm, the flow of oxygen is 80sccm, starting a medium-frequency sputtering power supply loaded on a silicon target, controlling the power to be 17KW, and depositing a silicon dioxide coating B with the thickness of 270 nm;
(5) repeating the step (3) and the step (4), and thus alternately depositing the niobium pentoxide coating layer A and the silicon dioxide coating layer B for 8 periods (the total number of layers is 16);
example 5
The light guide plate with the functions of transmitting infrared rays and reflecting visible light is provided, the substrate is made of Polycarbonate (PC), the thickness of the substrate is 0.36mm, and the preparation method comprises the following steps:
(1) purging the surface of the substrate with nitrogen for 3min to remove larger particles of impurities;
(2) the vacuum degree of a coating chamber is 0.1mbar, the argon flow is 20sccm, the negative bias power supply voltage is 700V, the argon plasma bombards and cleans the surface of the substrate for 10min, surface oxides are removed, the surface energy of the substrate is improved, and the adhesive force between a coating and the substrate can be improved;
(3) depositing a niobium pentoxide coating A on the substrate by high-vacuum medium-frequency magnetron sputtering, wherein the flow of argon is 120sccm, the flow of oxygen is 60sccm, starting a medium-frequency sputtering power supply loaded on a niobium pentoxide target, controlling the power at 12KW, and depositing the niobium pentoxide coating A with the thickness of 190 nm;
(4) depositing silicon dioxide B on the substrate by using high-vacuum medium-frequency magnetron sputtering, wherein the flow of argon is 100sccm, the flow of oxygen is 80sccm, starting a medium-frequency sputtering power supply loaded on a silicon target, controlling the power to be 17KW, and depositing a silicon dioxide coating B with the thickness of 270 nm;
(5) repeating the step (3) and the step (4), and thus alternately depositing the niobium pentoxide coating layer A and the silicon dioxide coating layer B for 12 periods (the total number of layers is 24);
example 6
The light guide plate with the functions of transmitting infrared rays and reflecting visible light is provided, the substrate is made of Polycarbonate (PC), the thickness of the substrate is 0.36mm, and the preparation method comprises the following steps:
(1) purging the surface of the substrate for 3min by nitrogen to remove larger granular impurities;
(2) the vacuum degree of a coating chamber is 0.1mbar, the argon flow is 20sccm, the negative bias power supply voltage is 700V, the argon plasma bombards and cleans the surface of the substrate for 10min, surface oxides are removed, the surface energy of the substrate is improved, and the adhesive force between a coating and the substrate can be improved;
(3) depositing a niobium pentoxide coating A on the substrate by high-vacuum medium-frequency magnetron sputtering, wherein the flow of argon is 120sccm, the flow of oxygen is 60sccm, starting a medium-frequency sputtering power supply loaded on a niobium pentoxide target, controlling the power at 12KW, and depositing the niobium pentoxide coating A with the thickness of 190 nm;
(4) depositing silicon dioxide B on the substrate by using high-vacuum medium-frequency magnetron sputtering, wherein the flow of argon is 100sccm, the flow of oxygen is 80sccm, starting a medium-frequency sputtering power supply loaded on a silicon target, controlling the power to be 17KW, and depositing a silicon dioxide coating B with the thickness of 270 nm;
(5) repeating the step (3) and the step (4), and thus alternately depositing the niobium pentoxide coating layer A and the silicon dioxide coating layer B for 16 cycles (the total number of layers is 32);
example 7
The light guide plate with the functions of transmitting infrared rays and reflecting visible light is provided, the substrate is made of Polycarbonate (PC), the thickness of the substrate is 0.36mm, and the preparation method comprises the following steps:
(1) purging the surface of the substrate for 3min by nitrogen to remove larger granular impurities;
(2) the vacuum degree of a coating chamber is 0.1mbar, the argon flow is 20sccm, the negative bias power supply voltage is 700V, the argon plasma bombards and cleans the surface of the substrate for 10min, the surface oxide is removed, the surface energy of the substrate is improved, and the adhesive force between the coating and the substrate can be improved;
(3) depositing a niobium pentoxide coating A on the substrate by high-vacuum medium-frequency magnetron sputtering, wherein the flow of argon is 120sccm, the flow of oxygen is 60sccm, starting a medium-frequency sputtering power supply loaded on a niobium pentoxide target, controlling the power at 12KW, and depositing the niobium pentoxide coating A with the thickness of 190 nm;
(4) depositing silicon dioxide B on the substrate by using high-vacuum medium-frequency magnetron sputtering, wherein the flow of argon is 100sccm, the flow of oxygen is 80sccm, starting a medium-frequency sputtering power supply loaded on a silicon target, controlling the power to be 17KW, and depositing a silicon dioxide coating B with the thickness of 270 nm;
(5) repeating the step (3) and the step (4), and thus alternately depositing the niobium pentoxide coating layer A and the silicon dioxide coating layer B for 24 cycles (total number of layers is 48).
Comparative example 1
Providing a light guide plate, wherein the substrate is made of Polycarbonate (PC) and has a thickness of 0.36mm, and the preparation method comprises the following steps:
(1) purging the surface of the substrate for 3min by nitrogen to remove larger granular impurities;
(2) depositing a niobium pentoxide coating A on the substrate by high-vacuum medium-frequency magnetron sputtering, wherein the flow of argon is 120sccm, the flow of oxygen is 60sccm, starting a medium-frequency sputtering power supply loaded on a niobium pentoxide target, controlling the power at 12KW, and depositing the niobium pentoxide coating A with the thickness of 190 nm;
(3) depositing silicon dioxide B on the substrate by using high-vacuum medium-frequency magnetron sputtering, wherein the flow of argon is 100sccm, the flow of oxygen is 80sccm, starting a medium-frequency sputtering power supply loaded on a silicon target, controlling the power to be 17KW, and depositing a silicon dioxide coating B with the thickness of 270 nm;
(4) repeating the step (3) and the step (4), and thus alternately depositing the niobium pentoxide coating layer A and the silicon dioxide coating layer B for 2 periods (the deposition AB is 1 period);
the light guide plate provided by the comparative example is different from the technical scheme provided by the application in that the substrate used in the comparative example is not subjected to argon plasma bombardment cleaning, and the aim is to show that the argon plasma attack cleaning of the substrate is favorable for improving the adhesive force.
Comparative example 2
Providing a light guide plate, wherein the substrate is made of Polycarbonate (PC) and has a thickness of 0.36mm, and the preparation method comprises the following steps:
(1) purging the surface of the substrate for 3min by nitrogen to remove larger granular impurities;
(2) the vacuum degree of a coating chamber is 0.1mbar, the argon flow is 20sccm, the negative bias power supply voltage is 700V, the argon plasma bombards and cleans the surface of the substrate for 10min, surface oxides are removed, the surface energy of the substrate is improved, and the adhesive force between a coating and the substrate can be improved;
(3) depositing a niobium pentoxide coating A on the substrate by high-vacuum medium-frequency magnetron sputtering, wherein the flow of argon is 120sccm, the flow of oxygen is 60sccm, starting a medium-frequency sputtering power supply loaded on a niobium pentoxide target, controlling the power at 12KW, and depositing the niobium pentoxide coating A with the thickness of 190 nm;
(4) depositing silicon dioxide B on the substrate by using high-vacuum medium-frequency magnetron sputtering, wherein the flow of argon is 100sccm, the flow of oxygen is 80sccm, starting a medium-frequency sputtering power supply loaded on a silicon target, controlling the power to be 17KW, and depositing a silicon dioxide coating B with the thickness of 270 nm;
(5) repeating the step (3) and the step (4), and thus alternately depositing the niobium pentoxide coating layer A and the silicon dioxide coating layer B for 30 periods (the total number of layers is 60);
the light guide plate provided by the comparative example is different from the technical scheme provided by the application in that the total number of the plated film layers in the comparative example is increased to 60, and the purpose is to show that the total number of the plated film layers has an upper limit value.
The light guide plates prepared in the examples of the present invention and the comparative examples were subjected to main performance tests in the following manner:
1. reflectance and transmittance testing: the reflectance and transmittance at a wavelength of 380nm to 1000nm were measured using an Agilent Cary5000 UV-visible near-IR spectrophotometer according to the NIST 2054 standard. The average value of the reflectivity of the wavelength of 380nm-780nm is taken, and if the average value is larger, the reflectivity of the visible light is stronger. The transmittance values at 850nm and 940nm wavelength are taken, and the larger the value is, the stronger the transmittance is.
And (3) testing the adhesive force: the adhesion of the functional layer to the substrate was tested according to the criteria of GB 1720-1979 "paint adhesion test", wherein 100/100 stands for no release and 90/100 for 10% release.
And (3) testing a warping value: the sample size should be 12cm long and 6cm wide, the sample is placed on a marble table, the warpage values of the four corners of the sample are measured using a plug gauge, and the maximum value is taken as the warpage value of the sample. The smaller the value, the better the warpage resistance, and the warpage value of less than 1mm is judged as being acceptable.
Table 1 results of performance tests of the light guide plates provided in examples 1 to 7 and comparative examples 1 to 2:
Figure BDA0002849802710000111
as can be seen from Table 1, comparative example 1 lacks the argon plasma to bombard the substrate and does not carry out the pretreatment of the substrate, resulting in poor adhesion of the plating layer to the substrate, and therefore the pretreatment process of the argon plasma is very necessary. The comparative example 2 has a large number of coating layers, so that the internal stress of the coating is correspondingly increased, the adhesive force of the coating is reduced, and about 20 percent of the coating in the test area is peeled off. Therefore, the coating period has a certain upper limit on the premise of meeting the optical performance.
It can be seen from examples 1-7 that, as the coating period increases, the number of coating layers increases, and the reflection of visible light by the light guide plate having the function of transmitting infrared light and reflecting visible light increases gradually. In particular, the light guide plate provided in embodiment 7 of the present invention has the best performance, and the average reflectance in the 380nm-780nm wavelength band exceeds 95%, while the transmittance at 850nm and 940nm is maintained at a level of more than 85%. The light guide plate provided by embodiment 7 well satisfies the high-efficiency reflection of visible light, guarantees the transmission of infrared rays, can well satisfy the requirements of visible light reflection in the field of LCD backlight sources, and well satisfies the acquisition of signals by a fingerprint identification device.
As can be seen from examples 1-7 and comparative example 2, with the increase of the film plating period, the number of the film plating layers is increased, and the warping caused by the increase of the internal stress of the plating layer is gradually highlighted, but the warping value is still less than 1mm, and the warping is qualified. Therefore, the light guide plate has better anti-warping capability.
The thickness of the traditional backlight module with the reflecting film is 0.766mm, while the thickness of the backlight module using the invention is reduced to 0.686mm, the comprehensive thickness is reduced by 10.4%, and the requirements of the market on light weight and ultra-thinning of the backlight module are met.
Examples 5-7 are preferred embodiments of the present invention, having a high visible reflectance and good infrared transmittance. The embodiment 7 has excellent performances and is the most preferable technical scheme of the invention.
The above are only preferred embodiments of the present invention, and are not intended to limit the present invention, and various modifications and changes may be made to the present invention by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. The light guide plate with the functions of transmitting infrared rays and reflecting visible light is characterized by sequentially comprising a substrate and a functional layer from top to bottom.
2. The light guide plate having the function of transmitting infrared rays and reflecting visible light according to claim 1, wherein the substrate is made of a material selected from Polycarbonate (PC), polymethyl methacrylate (PMMA) and colorless transparent polyimide (CPI); the thickness of the substrate is 0.075mm-0.36 mm.
3. The light guide plate with the function of transmitting infrared rays and reflecting visible light according to claim 1, wherein the functional layer is an inorganic plating layer.
4. The light guide plate with the function of transmitting infrared rays and reflecting visible light as claimed in claim 3, wherein the inorganic coating is composed of a high refractive index inorganic A and a low refractive index inorganic B, wherein the refractive index of inorganic A is greater than that of inorganic B.
5. The light guide plate with the function of transmitting infrared rays and reflecting visible light according to claim 4, wherein the thickness of the inorganic plating layer A is 10 to 300 nm.
6. The light guide plate with the function of transmitting infrared rays and reflecting visible light according to claim 3, wherein the inorganic plating layer A is made of a material selected from metal oxides.
7. The light guide plate with the function of transmitting infrared rays and reflecting visible light according to claim 3, wherein the thickness of the inorganic plating layer B is 10 to 300 nm.
8. The light guide plate with the function of transmitting infrared rays and reflecting visible light according to claim 3, wherein the inorganic coating B is made of one or a combination of at least two of silicon oxide, magnesium fluoride and zinc sulfide.
9. The light guide plate having the function of transmitting infrared rays and reflecting visible light as claimed in claim 3, wherein the inorganic plating layers A and the inorganic plating layers B are alternately deposited on the surface of the light guide plate in the order ABABA.
10. A backlight module, comprising the light guide plate having the function of transmitting infrared rays and reflecting visible light as claimed in any one of claims 1 to 9.
CN202011522772.3A 2020-12-22 2020-12-22 Light guide plate with infrared ray transmitting and visible light reflecting functions and backlight module Pending CN114660696A (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB722006A (en) * 1948-12-27 1955-01-19 Hubert Schroeder Infra-red transmitting mirror
CN203606527U (en) * 2013-12-09 2014-05-21 伯恩光学(惠州)有限公司 Infrared ray filter lens
CN110073366A (en) * 2019-03-11 2019-07-30 深圳阜时科技有限公司 Biological characteristic detects mould group, backlight module, display and electronic device
CN210894926U (en) * 2019-11-06 2020-06-30 深圳市汇顶科技股份有限公司 Reflective film, backlight module, liquid crystal display and fingerprint recognition device under screen
CN211826824U (en) * 2020-02-13 2020-10-30 深圳市隆利科技股份有限公司 Backlight module for face recognition

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB722006A (en) * 1948-12-27 1955-01-19 Hubert Schroeder Infra-red transmitting mirror
CN203606527U (en) * 2013-12-09 2014-05-21 伯恩光学(惠州)有限公司 Infrared ray filter lens
CN110073366A (en) * 2019-03-11 2019-07-30 深圳阜时科技有限公司 Biological characteristic detects mould group, backlight module, display and electronic device
CN210894926U (en) * 2019-11-06 2020-06-30 深圳市汇顶科技股份有限公司 Reflective film, backlight module, liquid crystal display and fingerprint recognition device under screen
CN211826824U (en) * 2020-02-13 2020-10-30 深圳市隆利科技股份有限公司 Backlight module for face recognition

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