阅读说明：本技术 一种vcsel阵列、制造方法、平顶远场生成方法及照明模组 (VCSEL array, manufacturing method, flat top far field generating method and lighting module ) 是由 梁栋 张�成 于 2019-11-26 设计创作，主要内容包括：本发明提供了一种VCSEL阵列、制造方法、平顶远场生成方法及照明模组,相对于传统的VCSEL阵列,不需要设置漫射器等光学元件即可很容易地实现均匀的平顶远场,从而在良好满足TOF测量等需要的同时,显著降低了阵列及相应的模组成本。同时,由于漫射器的取消,相应的侧壁柱与漫射器盖等部件也得以省略,使得模组厚度明显降低,具有现有技术中所不具备的诸多有益效果。(Compared with the traditional VCSEL array, the flat-top far field can be easily realized without arranging optical elements such as a diffuser and the like, so that the requirements of TOF measurement and the like are well met, and the cost of the array and the corresponding module is remarkably reduced. Meanwhile, due to the fact that the diffuser is omitted, corresponding parts such as the side wall columns, the diffuser cover and the like are omitted, the thickness of the module is obviously reduced, and the light-emitting diode module has a plurality of beneficial effects which are not achieved in the prior art.)

1. A VCSEL array, characterized by: the array includes:

a plurality of VCSEL units, and the light emitting apertures of the VCSEL units have a combination of different shapes and/or sizes for generating a uniform flat top far field.

2. The VCSEL array of claim 1, wherein: the VCSEL units are arranged to have the same current density, respectively.

3. The VCSEL array of claim 1, wherein: the light emitting holes of some VCSEL units in the array are all circular in first shape.

4. The VCSEL array of claim 1, wherein: the second shape of the light emitting holes of some VCSEL units in the array is rectangular.

5. The VCSEL array of claim 1, wherein: the light emitting holes of some of the VCSEL units in the array are arranged in a third shape, which is: on at least two sides of a rectangle there are portions that are concave towards the interior direction of the rectangle.

6. The VCSEL array of claim 5, wherein: the recessed portions are arranged in an arcuate, rectangular, triangular or other polygonal shape.

7. The VCSEL array of claim 1, wherein: the VCSEL units in the VCSEL array are arranged as follows: VCSEL units having smaller sized light emitting apertures are disposed in opposite interior regions of the array and VCSEL units having larger sized light emitting apertures are disposed in opposite peripheral regions of the array.

8. The VCSEL array of claim 5, wherein: the VCSEL units of the third shape are disposed in opposite peripheral regions of the array and the VCSEL units of a different third shape are disposed in opposite interior regions of the array defined by the VCSEL units of the third shape.

9. The VCSEL array of claim 8, wherein: the dimensions of the VCSEL units different from the third shape are smaller relative to the VCSEL units of the third shape.

10. The VCSEL array of claim 1, wherein: the VCSEL units in the VCSEL array are arranged as follows: VCSEL units having smaller sized light emitting apertures are disposed in opposite peripheral regions of the array and VCSEL units having larger sized light emitting apertures are disposed in opposite interior regions of the array.

11. The VCSEL array of claim 8, wherein: the VCSEL units of the different third shape are larger in size than the VCSEL units of the third shape.

12. The VCSEL array of claim 5, wherein: the VCSEL units of the third shape are regularly or irregularly staggered with VCSEL units of a different shape in the row direction and/or the column direction of the array.

13. The VCSEL array of claim 1, wherein: the VCSEL array adopts a flip chip structure.

14. A method of fabricating a VCSEL array, comprising: the method specifically comprises the following steps:

(1) epitaxially growing a layered structure of VCSEL units on a substrate;

(2) forming oxidation channels with different shapes and/or sizes on the layered structure;

(3) carrying out transverse oxidation on the periphery of the oxidation channel to form an oxidation layer and form a plurality of light emitting holes of the VCSEL units;

wherein the light emitting apertures of the plurality of VCSEL units have a combination of different shapes and/or sizes for generating a uniform flat top far field.

15. The method of claim 14, wherein: different VCSEL units are made to have the same current density, respectively.

16. The method of claim 14, wherein: through the oxidation, the first shapes of the light emitting holes of the VCSEL units in the array are all formed to be circular.

17. The method of claim 14, wherein: and forming the second shapes of the light emitting holes of part of the VCSEL units in the array into rectangles through the oxidation.

18. The method of claim 14, wherein: forming, by the oxidizing, light emitting holes of a part of the VCSEL units in the array into a third shape: on at least two sides of a rectangle there are portions that are concave towards the interior direction of the rectangle.

19. The method of claim 18, wherein: the shape of the recessed portion may be arcuate, rectangular, triangular or other polygonal shape.

20. The method of claim 19, wherein: by the oxidation, the arches with different radii of curvature are formed for interfering with the far field distribution that the VCSEL array can produce.

21. The method of claim 14, wherein: in the implementation of the manufacturing method, the arrangement density and the position of the VCSEL units are selected to provide different scattering angles.

22. The method of claim 14, wherein: through the oxidation, the VCSEL units in the VCSEL array are set to be: VCSEL units having smaller sized light emitting apertures are disposed in opposite interior regions of the array and VCSEL units having larger sized light emitting apertures are disposed in opposite peripheral regions of the array.

23. The method of claim 18, wherein: through the oxidation, the VCSEL units in the VCSEL array are set to be: VCSEL units of a third shape are arranged in a peripheral region of the array and VCSEL units of a different third shape are arranged in an inner region of the array defined by the VCSEL units of the third shape.

24. The method of claim 23, wherein: the size of the VCSEL units different from the third shape is made smaller relative to the VCSEL units of the third shape by the oxidation.

25. The method of claim 14, wherein: through the oxidation, the VCSEL units in the VCSEL array are set to be: VCSEL units having smaller sized light emitting apertures are disposed in opposite peripheral regions of the array and VCSEL units having larger sized light emitting apertures are disposed in opposite interior regions of the array.

26. The method of claim 23, wherein: the size of the VCSEL units different from the third shape is made larger relative to the VCSEL units of the third shape by the oxidation.

27. The method of claim 18, wherein: the oxidation causes the VCSEL units with the third shape and the VCSEL units with the third shape to be regularly or irregularly staggered in the row direction and/or the column direction of the array.

28. The method of claim 14, wherein: the layered structure of the VCSEL unit is formed as follows:

an n-type distributed Bragg reflector (n-DBR), a quantum well light-emitting layer (QW), an oxide layer and a metal layer are sequentially arranged on an n-type substrate from bottom to top.

29. The method of claim 14, wherein: and placing the oxidation layer at an antinode of the optical field standing wave or increasing the thickness and the number of the oxidation layers to generate a large angle.

30. A method of generating a uniform flat-topped far field distribution, comprising:

a VCSEL array fabricated using the VCSEL array of claims 1-13, or using the method of claims 14-29; and performing the following steps:

(1) applying a current to each VCSEL unit in the VCSEL array;

(2) and forming uniform flat-top far-field distribution by superposing the light fields respectively generated by the VCSEL units.

31. An illumination module characterized in that:

the module comprises a VCSEL array according to claims 1-13 or a VCSEL array manufactured using a method according to claims 14-29.

Technical Field

The invention relates to the technical field of Vertical Cavity Surface Emitting Lasers (VCSELs), in particular to a lens-free VCSEL unit and a corresponding illumination field generation method thereof.

Background

At present, in a plurality of intelligent devices such as smart phones, there is a great market demand for a flat-top infrared Illumination (IR) projection module, which plays a crucial role in specific applications such as TOF measurement and security camera equipment, and a Vertical Cavity Surface Emitting Laser (VCSEL) is the most central device in the flat-top IR projection module.

Existing flat-top infrared illumination projection modules typically structurally include a VCSEL array in combination with optics such as a diffuser (diffuser). The emission aperture of a typical VCSEL array is usually rectangular or circular, and the spatial light distribution (far field), which is usually gaussian or annular, is non-uniform and does not meet the requirements of TOF measurement etc., so that these shapes need to be changed by a diffuser into rectangular or circular flat-top intensity distributions (flat-top field), i.e. uniform light intensity distributions. In a typical application scenario, a light source with a flat-topped light field distribution of rectangular or circular shape, such as a combination of a VCSEL array plus a diffuser, illuminates a screen perpendicular to the direction of the light beam, and the light field on the screen is rectangular or circular with a uniform light field intensity distribution. There are several possible forms of a light field with a flat-top intensity profile, whose line scan profile at a certain position, either axial or angular, is shown in fig. 1(a) -1 (e). Generally, a flat top intensity profile is defined as: a certain light field distribution has a flat top region, the coordinate system of the flat top region may be an azimuth coordinate system or an angle coordinate system, the relative intensity fluctuation of the light field in the flat top region is within ± 15%, and more than 80% of the light field energy distribution is more than 50% of the intensity median of the flat top region, as shown in fig. 1 (e). The above-mentioned existing module structure, due to the arrangement of optical devices such as diffusers, has a severe requirement for the precision of assembly between the components, which increases the complexity of the structure and the production process, and in order to support such an optical system, a rigid frame with side walls is also required to support the VCSEL array and the optical elements, so as to provide a minimum spacing (typically 0.3-0.5 mm) between the two components, and the total thickness of the module is typically close to 1mm, which eventually makes it difficult to further reduce the thickness and volume of the device such as a mobile phone for which it is specifically applied. Therefore, how to manufacture a VCSEL unit that can generate a uniform far field and has a simple and reliable structure, and significantly reduce the cost of the IR module and the device applied thereto is a problem to be solved in the art.

Disclosure of Invention

In view of the above technical problems in the prior art, the present invention provides a lensless VCSEL array that does not require a diffuser (diffuser), the array comprising:

a plurality of VCSEL units and having a layered structure such as:

an n-type distributed Bragg reflector (n-DBR), a quantum well luminescent layer (QW), an oxidation layer and a metal layer are sequentially arranged on an n-type substrate from bottom to top;

wherein the current limiting layer is formed by an oxide layer so as to limit the light emitting holes of the plurality of VCSEL units;

the light emitting apertures of the VCSEL units in the array have different shapes and/or sizes.

The superimposed far field produced by the VCSEL array has a certain smoothing (averaging) effect with respect to the far field of the individual VCSEL units, thereby contributing to an improved uniformity of the far field distribution of the module as a whole.

Further, different VCSEL units can be arranged to have the same current density, respectively, thereby enabling a better control of the generated far field.

Further, the light emitting holes of some of the VCSEL units in the array are all circular in first shape.

In existing VCSEL arrays, VCSEL units with the same size and dimensions of the emission aperture are commonly used. The far field distributions produced by the superposition all present a gaussian or ring-shaped non-uniform distribution. Whereas a more uniform circular flat-topped far field can be achieved, for example, by a combination of circular apertures having different diameters.

Further, the second shapes of the light emitting holes of some of the VCSEL units in the array are each rectangular.

Further, the light emitting holes of some of the VCSEL units in the array are arranged in a third shape, which is: on at least two sides of a rectangle there are portions that are concave towards the interior direction of the rectangle.

The far field distribution produced by a VCSEL array having a rectangular light emitting aperture typically exhibits a rounded rectangular-like shape, whereas the shape of the far field distribution of the array can be significantly improved, relatively close to a rectangle, when an inwardly concave shape is to be formed on at least two sides of the rectangle.

The shape of the concave part can be an arch, a rectangle, a triangle or other polygons.

From maxwell's equations and their boundary conditions, it can be seen that apertures of different shapes and sizes have different boundary conditions and thus different optical modes. For example, a circular aperture allows the presence of an optical mode of the LP type, while a rectangular aperture allows the presence of a mode of the other type. Based on this theory, it can be found that the far field distribution of the array more closely approximates a standard rectangular shape when the radius of curvature of the arch is increased.

Since the divergence angle of a VCSEL array decreases with increasing temperature, with a correlation factor between divergence angle and temperature of about-0.04 °/° C to-0.05 °/° C, and the center of the array is typically hotter than the edges,

placing the small aperture light emitters in the middle of the array thus helps to reduce the angle.

Further, the VCSEL units in the VCSEL array are arranged to: VCSEL units having smaller sized light emitting apertures are disposed in opposite interior regions of the array and VCSEL units having larger sized light emitting apertures are disposed in opposite peripheral regions of the array.

Further, VCSEL units of a third shape are disposed on opposite peripheral regions of the array, and VCSEL units of a different shape than the third shape are disposed on opposite interior regions of the array defined by the VCSEL units of the third shape.

Further, the dimensions of the VCSEL units of the different third shape are smaller relative to the VCSEL units of the third shape.

Further, the VCSEL units in the VCSEL array are arranged to: VCSEL units having smaller sized light emitting apertures are disposed in opposite peripheral regions of the array and VCSEL units having larger sized light emitting apertures are disposed in opposite interior regions of the array.

Further, the size of the VCSEL units of the different third shape is larger relative to the VCSEL units of the third shape.

Further, the arrangement of the VCSEL units in the array may be arranged in a manner that the VCSEL units of the third shape are regularly or irregularly staggered with the VCSEL units of the third shape in the row direction and/or the column direction.

Further, the VCSEL array may employ a Flip-Chip (Flip-Chip) structure, so that the Chip may be Flip-Chip bonded directly on a Printed Circuit Board (PCB) without wire bonding or a submount (submount). In this case, the entire module comprises only a single chip of the VCSEL array, which can be directly glued to the printed wiring board of its driver.

Based on the same inventive concept, the invention also provides a manufacturing method of the VCSEL array, which specifically comprises the following steps:

(1) epitaxially growing a layered structure of VCSEL units on a substrate;

(2) forming oxidation channels with different shapes and/or sizes on the layered structure;

(3) carrying out transverse oxidation on the periphery of the oxidation channel to form an oxidation layer and form a plurality of light emitting holes of the VCSEL units;

wherein the light emitting holes of the plurality of VCSEL units have different shapes and/or sizes.

Further, different VCSEL units can be made to have the same current density, respectively, thereby enabling a better control of the generated far field.

Further, the first shapes of the light emitting holes of the VCSEL units in the array are all formed to be circular through the oxidation.

Further, the second shapes of the light emitting holes of some VCSEL units in the array are formed into rectangles through the oxidation.

Further, through the oxidation, the light emitting holes of part of the VCSEL units in the array are formed into the following third shape: on at least two sides of a rectangle there are portions that are concave towards the interior direction of the rectangle.

The shape of the concave part can be an arch, a rectangle, a triangle or other polygons.

By the oxidation, the arches with different radii of curvature are formed for interfering with the far field distribution that the VCSEL array can produce.

Further, in the manufacturing method, the positions of the VCSEL units are selected to provide different scattering angles.

Further, the oxidation makes the VCSEL units in the VCSEL array set as: VCSEL units having smaller sized light emitting apertures are disposed in opposite interior regions of the array and VCSEL units having larger sized light emitting apertures are disposed in opposite peripheral regions of the array.

Further, the oxidation makes the VCSEL units in the VCSEL array set as: VCSEL units of a third shape are arranged in a peripheral region of the array and VCSEL units of a different third shape are arranged in an inner region of the array defined by the VCSEL units of the third shape.

Further, the size of the VCSEL units different from the third shape is made smaller relative to the VCSEL units of the third shape by the oxidation.

Further, the oxidation makes the VCSEL units in the VCSEL array set as: VCSEL units having smaller sized light emitting apertures are disposed in opposite peripheral regions of the array and VCSEL units having larger sized light emitting apertures are disposed in opposite interior regions of the array.

Further, the size of the VCSEL unit with the shape different from the third shape is made larger than that of the VCSEL unit with the third shape by the oxidation.

Further, the oxidation makes the VCSEL units in the VCSEL array set as: the VCSEL units of the third shape and the VCSEL units of the different third shape are arranged regularly or irregularly staggered in the row direction and/or the column direction of the array.

Further, the layered structure of the VCSEL unit specifically includes:

an n-type distributed Bragg reflector (n-DBR), a quantum well light-emitting layer (QW), an oxide layer and a metal layer are sequentially arranged on an n-type substrate from bottom to top.

The angle of the flat top far field can be adjusted by epitaxial growth design, and since most applications require an illumination area of > 40 °, the oxide layer can be further placed at the antinode of the optical field standing wave or the thickness and number of layers of the oxide layer can be increased to produce large angles.

By the VCSEL array provided by the present invention or the VCSEL array manufactured by the method, a uniform flat-top far-field distribution can be achieved by the following method:

(1) applying a current to each VCSEL unit in the VCSEL array;

(2) and forming uniform flat-top far-field distribution by superposing the light fields respectively generated by the VCSEL units.

The invention also provides an illumination module comprising the VCSEL array provided by the invention or the VCSEL array manufactured by the method provided by the invention.

Compared with the traditional VCSEL array, the VCSEL array provided by the invention or the VCSEL array product obtained by the manufacturing method can easily realize a uniform flat-top far field without arranging optical elements such as a diffuser and the like, thereby obviously reducing the cost of the array and a corresponding module. Meanwhile, due to the elimination of the diffuser, corresponding components such as the side wall columns, the diffuser cover and the like are also omitted, so that the thickness of the module can be reduced from about 1.5mm to 0.5 mm. In some cases where a VCSEL array is fabricated using a flip-chip structure, the module thickness is only the VCSEL chip thickness and can be reduced to 0.1mm or less.

Drawings

FIG. 1 is a flat-top uniform far-field line scan intensity distribution diagram

FIG. 2 is a far field distribution diagram of a single circular VCSEL unit with superimposed far field and different light emitting holes

FIG. 3 is a schematic diagram of the smoothing effect of a VCSEL array

FIG. 4 is several preferred shapes of the concave portion

FIG. 5 is a graph comparing the far field distribution of a concave-sided rectangle and a standard rectangle light emitting aperture

FIG. 6 is a graph of divergence angle versus temperature

FIG. 7 is a diagram of an array and far field distribution using a combination of large concave-sided rectangles and small rectangular light emitting apertures

FIG. 8 is a far field distribution effect using a large concave side rectangle and small rectangle light emitting aperture combined array

FIG. 9 is a diagram comparing the structure of a module including an array provided by the present invention with that of a module in the prior art

FIG. 10 is a preferred embodiment of the manufacturing method provided by the present invention

FIG. 11 is a block diagram of a VCSEL unit that can be used with the present invention

Fig. 12 shows a chip structure and a far-field distribution diagram according to a preferred embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the scope of the present invention.

The light field distribution imaging and waveform diagrams in fig. 2, 7-8 and 12 are for the purpose of showing the effects achieved by the scheme of the present invention and the comparison with the prior art, and the specific coordinate values are not important points to be presented.

The present invention provides a lensless VCSEL array that does not require a diffuser (diffuser) to be provided, the array comprising:

a plurality of VCSEL units, the light emitting apertures of the VCSEL units having different shapes and/or sizes.

Fig. 2 shows the far field distribution of a single VCSEL with a circular light emitting aperture and the far field distribution resulting from the superposition of VCSEL units comprising light emitting apertures of different sizes. It can be seen that the far fields of the individual VCSEL units are non-uniform, such as a ring or gaussian distribution, while the far field distributions generated by stacking in the array are more uniform.

As shown in fig. 3, the superimposed far fields generated by the VCSEL arrays with rectangular, circular and rectangular light emitting holes have a certain smoothing (averaging) effect with respect to the far field of the individual VCSEL units, thereby contributing to the uniformity of the far field distribution of the module as a whole.

In a preferred embodiment of the present application, different VCSEL units can be arranged to have the same current density, respectively, thereby enabling a better control of the generated far field.

A preferred embodiment of the present invention is also shown in fig. 2, i.e. the first shape of the light emitting apertures of some of the VCSEL units in the array is circular as shown in fig. 3 (b).

In a preferred embodiment of the present application, the second shapes of the light emitting holes of some of the VCSEL units in the array are each rectangular as shown in fig. 3 (c).

In a preferred embodiment of the present application, the light emitting holes of some VCSEL units in the array are arranged in a third shape as shown in fig. 3 (a), the shape being: on at least two sides of a rectangle there are portions that are concave towards the interior direction of the rectangle. Fig. 4 shows several preferred shapes for the recess, which may be arcuate, rectangular, triangular, or other polygonal shapes may be selected in practice.

As shown in fig. 5, the far field distribution produced by a VCSEL array having rectangular light emitting apertures generally exhibits a shape resembling a rounded rectangle, and the shape of the array far field distribution can be significantly improved, relatively close to a rectangle, when an inwardly concave shape is to be formed on at least two sides of the rectangle. And when the radius of curvature of the arch is increased, the far field distribution of the array can be found to be closer to the standard rectangular shape.

Since the divergence angle of a VCSEL array decreases with increasing temperature, with a correlation factor between divergence angle and temperature of about-0.04 °/° C to-0.05 °/° C, and the center of the array is typically hotter than the edges, as shown in fig. 6, small aperture light emitters can be placed in the middle of the array to help reduce the divergence angle in a preferred embodiment of the present application.

In some preferred embodiments, the VCSEL units in the VCSEL array can be arranged as: VCSEL units having smaller sized light emitting apertures are disposed in opposite interior regions of the array and VCSEL units having larger sized light emitting apertures are disposed in opposite peripheral regions of the array.

Further, VCSEL units of a third shape are disposed on opposite peripheral regions of the array, and VCSEL units of a different shape than the third shape are disposed on opposite interior regions of the array defined by the VCSEL units of the third shape.

Further, the dimensions of the VCSEL units of the different third shape are smaller relative to the VCSEL units of the third shape.

Of course, in some preferred embodiments, the VCSEL units with smaller-sized light-emitting holes are arranged in the opposite peripheral region of the array, and the VCSEL units with larger-sized light-emitting holes are arranged in the opposite inner region of the array, so that a better flat-top far-field effect can be achieved. In this case, an arrangement in which the size of the VCSEL units of the third shape is different from the VCSEL units of the third shape is larger than the VCSEL units of the third shape may be adopted.

In certain preferred embodiments, the VCSEL units of the third shape and the VCSEL units of the different third shape may also be arranged regularly or irregularly staggered in the row direction and/or in the column direction on the array.

Fig. 7 shows a preferred embodiment using the above arrangement, which uses a combination of a larger size concave rectangular light emitting hole and two small size rectangular light emitting holes with different placement directions. The concave side rectangle adopts a preferred form enclosed by four concave arcs. Fig. 8 shows the far-field distribution effect obtained by such an array, and it can be seen that the fluctuation of the light field intensity of the rectangular flat top can be within ± 10%, which completely meets the requirements of most applications of the TOF projection module.

In some preferred embodiments, the VCSEL array may adopt a Flip-Chip (Flip-Chip) structure, so as to significantly reduce the thickness of the device and the module, and fig. 9 shows the structure and thickness of the array provided by the present invention compared with the conventional VCSEL array.

The invention also provides a corresponding manufacturing method of the VCSEL array, which comprises the following steps:

(1) epitaxially growing a layered structure of VCSEL units on a substrate;

(2) forming oxidation channels with different shapes and/or sizes on the layered structure;

(3) carrying out transverse oxidation on the periphery of the oxidation channel to form an oxidation layer and form a plurality of light emitting holes of the VCSEL units;

wherein the light emitting holes of the plurality of VCSEL units have different shapes and/or sizes.

FIG. 10 shows a preferred embodiment of the above method, in which the black regions are oxide channel regions, allowing water vapor to enter the channel and contact the sides of the AlGaAs layer of high aluminum composition, to effect lateral oxidation of the AlGaAs layer of high aluminum composition to form Al₂O₃A current confinement layer. The white area defined by the dotted line is an oxidized area, and the shaded concave-sided rectangle and the small straight-sided rectangle are light-emitting areas. An array format corresponding to that shown in figure 7 can be produced by this method. Typical dimensions that may be selected are:

oxidation length: 5 μm;

minimum size of oxidation channel: 6 μm;

small rectangle: 3 μm × 4 μm;

concave side rectangle: 15X 11.25 μm;

R1：16um，R2：20 μm。

the layered structure of the VCSEL unit may employ a typical structure as shown in fig. 11. Wherein, each layer is respectively: a metal layer 1, a p-type distributed bragg reflector (p-DBR) 2, an oxide layer 3, a quantum well light-emitting layer (QW) 4, an n-type distributed bragg reflector (n-DBR) 5, and an n-type substrate 6.

FIG. 12 shows a preferred chip structure and its far field distribution provided by the present invention, with concave rectangular light emitting holes around the array and rectangular light emitting holes in the inner region.

The invention also provides a corresponding method for generating a uniform flat-top far field, which is shown in the embodiments and the attached drawings.

The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only examples of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.