阅读说明：本技术 一种基于纳米线的μLED显示设计方法 (Nanowire-based mu LED display design method ) 是由 郭太良 江宗钊 叶芸 严群 谢洪兴 姚剑敏 于 2019-10-16 设计创作，主要内容包括：本发明涉及一种基于纳米线的μLED显示设计方法,首先在衬底上生长能够产生红、绿、蓝三基色的不同纳米线材料,然后将不同纳米线材料分别溶于绝缘的光固化胶后分别栅格池的不同栅格中,并进行固化,最后在栅格池的上、下表面设置电极。本发明能够简化结构,提升μLED的产业效率。(The invention relates to a mu LED display design method based on nanowires, firstly different nanowire materials capable of generating three primary colors of red, green and blue are grown on a substrate, then the different nanowire materials are respectively dissolved in different grids of a grid pool after insulated light curing glue, and are cured, and finally electrodes are arranged on the upper surface and the lower surface of the grid pool. The invention can simplify the structure and improve the industrial efficiency of the mu LED.)

1. A mu LED display design method based on nano-wires is characterized in that different nano-wire materials capable of generating three primary colors of red, green and blue grow on a substrate, the different nano-wire materials are respectively dissolved in different grids of a grid pool after being respectively dissolved in insulated light curing glue and are cured, and finally, electrodes are arranged on the upper surface and the lower surface of the grid pool.

2. The nanowire-based μ LED display design method according to claim 1, comprising the steps of:

step S1: growing a nanowire material for generating a red, green and blue tricolor light source;

step S2: respectively doping the nanowire materials generating the red, green and blue tricolor light sources into the photocuring glue and fully stirring, and uniformly dispersing the nanowire materials in the photocuring glue to obtain a fully-stirred photocuring glue-nanowire material colloid;

step S3: respectively and correspondingly injecting the fully-stirred photo-curing glue-nanowire material glue into grids of grid pools corresponding to red, green and blue three-primary-color sub-pixels for photo-curing, and cutting off overflowing curing glue in a laser cutting mode after photo-curing to obtain a sub-pixel cured mu LED;

step S4: and (3) attaching or growing electrodes on the upper surface and the lower surface of the grid pool through a patch electrode method, so that the electrodes capable of working under the condition of alternating current correspond to the cured mu LEDs of the corresponding sub-pixels one by one, and cutting the required display size by using a laser cutting method.

3. The method as claimed in claim 1, wherein the nanowire material is homojunction nano, the upper and lower ends of the nanowire material are doped with n and p respectively, the two end caps of the nanowire material have negative and positive tendencies respectively, and recombination of electrons and holes can be generated at the interface center of the n and p homojunction.

4. The method of claim 1, wherein the nanowires have an inner diameter of 40nm to 60nm and a length of 300nm to 400 nm.

5. The method of claim 2, wherein step S1 comprises the following steps:

step S11: cleaning and processing the substrate;

step S12: putting a substrate into a reaction cavity of a physical vapor deposition device, and starting evaporation of a nanowire buffer layer to solve mismatching of the substrate and the nanowire in the axial direction, releasing stress strain caused by mismatching of the substrate and the nanowire material lattices along the side surface and the direction vertical to a junction interface when the nanowire grows, and conveniently growing the materials with lattice mismatching in a radial or axial series connection manner;

step S13: placing the substrate covered with the buffer layer film into a multi-piece HVPE growth system, and starting to grow the nanowire at low temperature with the substrate as the lower part, so that the nanowire grows from bottom to top to form a positive-polarity-inclined p-doped nanowire end-p-doped nanowire-n-doped nanowire-negative-polarity-inclined n-doped nanowire end structure;

step S14: and cooling and taking out the sample to obtain the nanowire material.

6. The nanowire-based μ LED display design method of claim 5, wherein the nanowire growth material selects different direct bandgap semiconductor compounds from III-V for sub-pixels of different primary colors.

7. The method as claimed in claim 1, wherein the photo-curable glue is a transparent insulating material.

8. The method of claim 1, wherein the grid cells are made of transparent insulating material.

9. The method of claim 1, wherein the grids in the grid pool are square, have a length of 16-32 um, a width of 9-18um, and a depth of 9-18 um.

10. The method as claimed in claim 1, wherein the electrodes are made of a material capable of working under ac condition, including but not limited to graphene, PEDOT: PSS, metallic silver, platinum or gold.

Technical Field

The invention relates to the field of LED design, in particular to a mu LED display design method based on nanowires.

Background

In the field of flat panel display technology, the mu LED has many advantages, most notably low power consumption, high brightness, ultrahigh definition, high color saturation, faster response speed, longer service life, higher working efficiency and the like, so that the mu LED is a revolutionary novel display technology and is expected to replace a TFT liquid crystal display in almost all applications in the field of flat panel display.

When the production process of the next mu LED is continued to the traditional LED production mode, the size of a pn junction material is limited below 100 mu m by various thin film growth methods, and the problem of lattice mismatch is difficult to avoid in the growth process of a layered thin film, so that the problems of lattice mismatch and quantum conversion efficiency improvement need to be solved by introducing various buffer layers or functional layers in the production process of the layered mu LED, and therefore, the layered structure becomes more complex; after the manufacturing of the mu LED, the mu LED is required to be cut into micron-scale small LED chips, and the chips are transferred to a circuit substrate through various mechanical tools, so that a great amount of time is consumed in the process because a great amount of mu LED chips need to be picked, placed and assembled. In order to solve the above problems, the efficiency of the μ LED industry is improved, the structure is simplified, and the development and design of a new μ LED is required urgently.

Disclosure of Invention

In view of the above, an object of the present invention is to provide a method for designing a μ LED display based on nanowires, which can simplify the structure and improve the industrial efficiency of the μ LED.

The invention is realized by adopting the following scheme: a mu LED display design method based on nanowires specifically comprises the following steps: different nanowire materials capable of generating three primary colors of red, green and blue are grown on the substrate, the different nanowire materials are respectively dissolved in different grids of the grid pool after being respectively dissolved in insulated light curing glue and are cured, and finally electrodes are arranged on the upper surface and the lower surface of the grid pool. When the addressing signal passes through the corresponding electrode, the lighting of the corresponding pixel and the image display can be completed.

Further, the method specifically comprises the following steps:

step S1: growing a nanowire material (the MOCVD process can be utilized) for generating a red, green and blue three-primary-color light source, performing end positive and negative charge tendency treatment, and stripping after growth is completed;

step S2: respectively doping the nanowire materials generating the red, green and blue tricolor light sources into the light curing glue, fully stirring (including mechanical, magnetic or ultrasonic stirring), and uniformly dispersing the nanowire materials in the light curing glue to obtain a fully stirred light curing glue-nanowire material colloid;

step S3: respectively and correspondingly injecting the fully-stirred photo-curing glue-nanowire material glue into grids of grid pools corresponding to red, green and blue three-primary-color sub-pixels for photo-curing, and cutting off overflowing curing glue in a laser cutting mode after photo-curing to obtain a sub-pixel cured mu LED; during the process of injecting the colloidal solution mixed by the red, green and blue nanowire materials, the green and blue grid pools, the red and blue grid pools and the red and green grid pools can be shielded in sequence, and overflowing solidified colloid is cut off in a laser cutting mode after photocuring;

step S4: and (3) attaching or growing electrodes on the upper surface and the lower surface of the grid pool through a patch electrode method, so that the electrodes capable of working under the condition of alternating current correspond to the cured mu LEDs of the corresponding sub-pixels one by one, and cutting the required display size by using a laser cutting method.

Furthermore, the nanowire material is a homojunction material which grows on the silicon substrate from bottom to top and can generate different primary colors of red, green and blue, the homojunction material is doped with n and p at the upper end and the lower end respectively, the two end tops respectively have negative electricity tendency and positive electricity tendency, and electron and hole recombination can be generated in the center of the junction of the n and p homojunctions.

Further, the inner diameter of the nano-wire is between 40nm and 60nm, and the length of the nano-wire is between 300nm and 400nm, so that a proper contact area is provided for enabling the pn junction to generate carrier recombination and further perform radiative transition.

Further, step S1 includes the steps of:

step S11: cleaning and processing the substrate; sequentially carrying out ultrasonic cleaning on a sample in deionized water, ethanol and deionized water to remove residual pollutants on the surface, and drying by using nitrogen;

step S12: putting a substrate into a reaction cavity of a physical vapor deposition device, and starting evaporation plating of a nanowire buffer layer under certain reaction cavity pressure and metal source temperature to solve mismatching of the substrate and the nanowire in the axial direction, releasing stress strain caused by mismatching of the substrate and the nanowire material lattices in the growth of the nanowire along the side surface and the direction vertical to a junction interface, and conveniently growing the materials with lattice mismatching in a radial or axial series manner; after the buffer layer film is grown, the vertical nanowire material can be grown;

step S13: placing the substrate covered with the buffer layer film into a multi-piece HVPE growth system, starting to grow the nanowire at low temperature with the substrate as the lower part, and controlling a nanowire material source, n-p doping gas, reaction gas, carrier gas and positive and negative electric tendency treatment to enable the nanowire to grow from bottom to top into a positive electric tendency p-doping nanowire end-p-doping nanowire-n-doping nanowire-negative electric tendency n-doping nanowire end structure;

step S14: and cooling and taking out the sample to obtain the nanowire material.

Further, for the sub-pixels with different primary colors, the nanowire growth material is selected from different direct band gap semiconductor compounds from III-V groups, for example, the sub-pixel emitting blue light is selected from GaN, the sub-pixel emitting green light is selected from InGaN, and the sub-pixel emitting red light is selected from GaAs, but not limited thereto.

Furthermore, the light-curing glue is made of a transparent insulating material. The light curing glue is used as a carrier of different nanowire materials of the red, green and blue sub-pixels, is a glue body at room temperature and normal pressure, has certain fluidity and can be cured at room temperature, and the light curing glue selects a transparent insulating material with a larger dielectric constant to realize transparent display.

The light-cured adhesive material can be prepared from an oligomer main component of unsaturated polyester resin, acrylic resin and polythiol/polyene resin, a proper diluent monomer, a photosensitizer and an auxiliary agent material, and can be quickly cured by ultraviolet light at room temperature.

Furthermore, the grid cells are made of transparent insulating materials. The grid pool is used as a place for curing the light curing glue and the nanowire material mixed solution, each grid is used as a red, green and blue sub-pixel point, and the grid pool selects a transparent insulating material with a large dielectric constant to realize transparent display.

The electrodes are sequentially arranged into conductive electrodes of sub-pixel units with different primary colors at intervals, and the size and the central position of the electrodes are accurately matched with those of the grid pool.

Furthermore, the grids in the grid pool are square, the length is between 16um and 32um, the width is between 9um and 18um, and the depth is 9um to 18 um. The transmittance of light with the wavelength of 380nm to 780nm is more than or equal to 90%, and the material can be organic material, and comprises: one or more of Polyethylene (PE), polypropylene (PP), polyethylene naphthalate (PEN), Polycarbonate (PC), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA), Cellulose Acetate Butyrate (CAB), siloxane, polyvinyl chloride (PVC), polyvinyl alcohol (PVA), polyethylene terephthalate (PET), modified polyethylene terephthalate (PETG), Polydimethylsiloxane (PDMS) or Cyclic Olefin Copolymer (COC); or an inorganic material comprising: one or more of glass, quartz and transmissive ceramic materials.

Further, the electrode is made of a material capable of working under alternating current conditions, including but not limited to graphene, PEDOT: PSS, metallic silver, platinum or gold. The electrodes can be patch electrodes or transparent electrode materials which grow on the mu LED subsequently, and due to the design, the nanowires in the mu LED are uniformly distributed in the colloid, and the distribution of the p-end nanowires and the n-end nanowires is unknown, pn junction carriers can emit light in a compounding mode to the maximum extent, and the electrode materials are materials capable of working under the condition of alternating current.

In summary, the mu LED display design of the invention utilizes the homogeneous pn junction nanowire material to complete the radiation transition generated by the electron and hole recombination, compared with the layered junction structure, the nanowire pn junction has lower working voltage and higher internal quantum efficiency, and the nanowire growth process can release the stress strain caused by the lattice mismatch of the substrate and the nanowire material along the side surface and the direction vertical to the junction interface, thereby overcoming the lattice mismatch limitation of the layered structure, simultaneously, various microprocessing can be carried out in the growth process, and the working efficiency of the device is improved. The nano wires and the light curing adhesive are dissolved mutually, and the curing is completed in the sub-pixel grid pool after uniform stirring, so that the structure of the laminated mu LED is simplified. When the sub-pixel is selected, electrons and holes complete short-distance transition in the insulating light curing adhesive through quantum tunneling, the electrons and the holes are injected into the nanowire to enable the pn junction to generate radiation transition, the end of the nanowire has positive and negative electron tendentiousness, and the guidance of current carriers can be completed, so that the mu LED under the structure can work in an alternating current state, a required display size can be obtained through a laser cutting mode, the problem of huge transfer is avoided, the manufacturing period of the mu LED is shortened, and the market competitiveness of the mu LED is greatly improved.

Compared with the prior art, the invention has the following beneficial effects:

1. the mu LED display design method mainly utilizes the pn junction carrier composite luminescence of the nanowire material to carry out sub-pixel lighting, and is different from the growth of a common traditional mu LED plane, and the semiconductor nanowire can release stress strain caused by the mismatch of the substrate and the crystal lattices of the nanowire material along the side surface and the direction vertical to the junction interface during the growth, so that the semiconductor nanowire can be grown on a specific substrate to overcome the limitation of the mismatch of the crystal lattices and can be conveniently designed into various complex structures;

2. the current through the nanowire shaped junction array is larger than the current of the layered junction, which design also reduces the operating voltage. The photocuring glue and the nano wires are mixed in the grid pool to form the sub-pixel points through photocuring, so that the manufacturing process of the mu LED is simple and easy to realize, and the structure is simpler.

3. The invention can obtain the required display size by cutting the grids in a laser cutting mode, thereby avoiding the problem of huge transfer of the traditional mu LED used in the display industry.

Drawings

Fig. 1 is a schematic cross-sectional view of a μ LED display structure designed by the design method of the embodiment of the present invention.

Fig. 2 is a schematic cross-sectional structure diagram of a nanowire according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a structure of a grid cell according to an embodiment of the present invention.

FIG. 4 is a diagram of a photo-curing glue-nanowire mixed solution according to an embodiment of the present invention.

FIG. 5 is a flowchart illustrating a method according to an embodiment of the present invention.

In the figure, 10 is a red mu LED, 11 is a substrate, 12 is a buffer layer, 13 is a positive-polarity-oriented nanowire tip, 14 is a p-type doped nanowire material, 15 is a nanowire, 16 is an n-type doped nanowire material, 17 is a negative-polarity-oriented nanowire tip, 20 is a green mu LED, 25 is a photo-curing glue, 30 is a blue mu LED, 40 is a grid cell, 50 is an electrode insulating portion, and 60 is an electrode.

Detailed Description

The invention is further explained below with reference to the drawings and the embodiments.

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

As shown in fig. 5, the present embodiment provides a method for designing a nanowire-based μ LED display, which specifically includes: different nanowire materials capable of generating three primary colors of red, green and blue are grown on the substrate, the different nanowire materials are respectively dissolved in different grids of the grid pool after being respectively dissolved in insulated light curing glue and are cured, and finally electrodes are arranged on the upper surface and the lower surface of the grid pool. When the addressing signal passes through the corresponding electrode, the lighting of the corresponding pixel and the image display can be completed.

In this embodiment, the method specifically includes the following steps:

step S1: growing a nanowire material (the MOCVD process can be utilized) for generating a red, green and blue three-primary-color light source, performing end positive and negative charge tendency treatment, and stripping after growth is completed;

step S2: respectively doping the nanowire materials generating the red, green and blue tricolor light sources into the light curing glue, fully stirring (including mechanical, magnetic or ultrasonic stirring), and uniformly dispersing the nanowire materials in the light curing glue to obtain a fully stirred light curing glue-nanowire material colloid;

step S3: respectively and correspondingly injecting the fully-stirred photo-curing glue-nanowire material glue into grids of grid pools corresponding to red, green and blue three-primary-color sub-pixels for photo-curing, and cutting off overflowing curing glue in a laser cutting mode after photo-curing to obtain a sub-pixel cured mu LED; during the process of injecting the colloidal solution mixed by the red, green and blue nanowire materials, the green and blue grid pools, the red and blue grid pools and the red and green grid pools can be shielded in sequence, and overflowing solidified colloid is cut off in a laser cutting mode after photocuring;

step S4: and (3) attaching or growing electrodes on the upper surface and the lower surface of the grid pool through a patch electrode method, so that the electrodes capable of working under the condition of alternating current correspond to the cured mu LEDs of the corresponding sub-pixels one by one, and cutting the required display size by using a laser cutting method.

In this embodiment, the nanowire material is a homojunction material capable of generating different primary colors of red, green and blue, which grows on a silicon substrate from bottom to top, and the homojunction material has n-doped and p-doped upper and lower ends, respectively, and has negative and positive terminal tendencies at the top ends, respectively, and can generate electron and hole recombination at the junction center of the n-and p-homojunction.

In the embodiment, the inner diameter of the nanowire is between 40nm and 60nm, and the length of the nanowire is between 300nm and 400nm, so that a proper contact area is provided for the pn junction to generate carrier recombination and further perform radiative transition.

In the present embodiment, step S1 includes the following steps:

step S11: cleaning and processing the substrate; sequentially carrying out ultrasonic cleaning on a sample in deionized water, ethanol and deionized water to remove residual pollutants on the surface, and drying by using nitrogen;

step S12: putting a substrate into a reaction cavity of a physical vapor deposition device, and starting evaporation plating of a nanowire buffer layer under certain reaction cavity pressure and metal source temperature to solve mismatching of the substrate and the nanowire in the axial direction, releasing stress strain caused by mismatching of the substrate and the nanowire material lattices in the growth of the nanowire along the side surface and the direction vertical to a junction interface, and conveniently growing the materials with lattice mismatching in a radial or axial series manner; after the buffer layer film is grown, the vertical nanowire material can be grown;

step S13: placing the substrate covered with the buffer layer film into a multi-piece HVPE growth system, starting to grow the nanowire at low temperature with the substrate as the lower part, and controlling a nanowire material source, n-p doping gas, reaction gas, carrier gas and positive and negative electric tendency treatment to enable the nanowire to grow from bottom to top into a positive electric tendency p-doping nanowire end-p-doping nanowire-n-doping nanowire-negative electric tendency n-doping nanowire end structure;

step S14: and cooling and taking out the sample to obtain the nanowire material.

In this embodiment, for the sub-pixels with different primary colors, the nanowire growth material is selected from different direct band gap semiconductor compounds from III-V groups, for example, the sub-pixel emitting blue light is selected from GaN, the sub-pixel emitting green light is selected from InGaN, and the sub-pixel emitting red light is selected from GaAs, but not limited thereto.

In this embodiment, the light-curable adhesive is made of a transparent insulating material. The light curing glue is used as a carrier of different nanowire materials of the red, green and blue sub-pixels, is a glue body at room temperature and normal pressure, has certain fluidity and can be cured at room temperature, and the light curing glue selects a transparent insulating material with a larger dielectric constant to realize transparent display.

The light-cured adhesive material can be prepared from an oligomer main component of unsaturated polyester resin, acrylic resin and polythiol/polyene resin, a proper diluent monomer, a photosensitizer and an auxiliary agent material, and can be quickly cured by ultraviolet light at room temperature.

In this embodiment, the grid cells are made of a transparent insulating material. The grid pool is used as a place for curing the light curing glue and the nanowire material mixed solution, each grid is used as a red, green and blue sub-pixel point, and the grid pool selects a transparent insulating material with a large dielectric constant to realize transparent display.

The electrodes are sequentially arranged into conductive electrodes of sub-pixel units with different primary colors at intervals, and the size and the central position of the electrodes are accurately matched with those of the grid pool.

In this embodiment, the grids in the grid pool are square, the length is between 16um-32um, the width is between 9-18um, the depth is 9-18um, and the distance between the grid wall and the outer wall of the grid pool is between 1um and 3 um. The transmittance of light with the wavelength of 380nm to 780nm is more than or equal to 90%, and the material can be organic material, and comprises: one or more of Polyethylene (PE), polypropylene (PP), polyethylene naphthalate (PEN), Polycarbonate (PC), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA), Cellulose Acetate Butyrate (CAB), siloxane, polyvinyl chloride (PVC), polyvinyl alcohol (PVA), polyethylene terephthalate (PET), modified polyethylene terephthalate (PETG), Polydimethylsiloxane (PDMS) or Cyclic Olefin Copolymer (COC); or an inorganic material comprising: one or more of glass, quartz and transmissive ceramic materials.

In this embodiment, the electrode is made of a material capable of operating under ac conditions, including but not limited to graphene, PEDOT: PSS, metallic silver, platinum or gold. The electrodes can be patch electrodes or transparent electrode materials which grow on the mu LED subsequently, and due to the design, the nanowires in the mu LED are uniformly distributed in the colloid, and the distribution of the p-end nanowires and the n-end nanowires is unknown, pn junction carriers can emit light in a compounding mode to the maximum extent, and the electrode materials are materials capable of working under the condition of alternating current.

As shown in fig. 1, 10 is a red μ LED, 20 is a green μ LED, 30 is a blue μ LED, 40 is a grid cell, 50 is an electrode insulating portion, and 60 is an electrode. The nano-wire materials of the mu LED for red, green and blue are respectively GaN, InGaN and GaAs, the electrode adopts a patch type, the insulating part is silicon dioxide, and the conducting part is Ag. As shown in fig. 2, the nanowire grows on a 11 substrate, the material of the nanowire is simple substance silicon, a 12 buffer layer (the material of the nanowire is AlN), a 13 positive electric-polarity-oriented nanowire end, a 14 p-type doped nanowire material, a 16 n-type doped nanowire material and a 17 negative electric-polarity-oriented nanowire end sequentially grow on the silicon substrate by using an MOCVD method, and the nanowire is centrifugally stripped after the growth of the nanowire material is completed. As shown in fig. 3, 40 is a grid cell, which is distributed in a rectangular shape like a Chinese character 'kou', the thickness is 1um, each grid is 16um long, 9um wide and 9um deep, the material is a transparent silicon dioxide insulating material, and the light transmittance is greater than 90%. As shown in fig. 4, 15 is a nanowire, 25 is a light-cured adhesive, which is a μ V light-cured adhesive mainly composed of methacrylic acid epoxy resin, the nanowire and the μ V adhesive which are separated from each other by centrifugation are mechanically stirred to uniformly disperse the carbon nanowire in the colloid, and the single-primary-color subpixel μ LED is formed by ultraviolet curing.

In summary, the μ LED display design of the present embodiment utilizes a homogeneous pn junction nanowire material to complete electron and hole recombination to generate radiation transition, compared with a layered junction structure, the nanowire pn junction has a lower working voltage and a higher internal quantum efficiency, and the nanowire growth process can release stress strain caused by lattice mismatch between the substrate and the nanowire material along the side surface and the direction perpendicular to the junction interface, thereby overcoming the lattice mismatch limitation of the layered structure, and simultaneously performing various micro-processing during the growth process, thereby improving the working efficiency of the device. The nano wires and the light curing adhesive are dissolved mutually, and the curing is completed in the sub-pixel grid pool after uniform stirring, so that the structure of the laminated mu LED is simplified. When the sub-pixel is selected, electrons and holes complete short-distance transition in the insulating light curing adhesive through quantum tunneling, the electrons and the holes are injected into the nanowire to enable the pn junction to generate radiation transition, the end of the nanowire has positive and negative electron tendentiousness, and the guidance of current carriers can be completed, so that the mu LED under the structure can work in an alternating current state, a required display size can be obtained through a laser cutting mode, the problem of huge transfer is avoided, the manufacturing period of the mu LED is shortened, and the market competitiveness of the mu LED is greatly improved.

The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.