阅读说明：本技术 基板缺陷标记方法和装置 (Substrate defect marking method and device ) 是由 粘巧芸 于 2021-09-13 设计创作，主要内容包括：本申请涉及一种基板缺陷标记方法和装置。一种基板缺陷标记方法,包括：获取可靠度试验前基板的第一图像；获取可靠度试验后该所述基板的第二图像；根据所述第一图像和所述第二图像,确定所述基板的缺陷区域；在所述基板的表面中对应于所述基板的缺陷区域的待标记区域进行标记。有针对性地对该缺陷区域对应的待标记区域进行标记,不容易出现缺陷标记的误判,也有利于以此缺陷推断出基板在长时间使用后可能产生的缺陷,有利于针对此缺陷进行提前改善。(The application relates to a substrate defect marking method and device. A method of marking a defect in a substrate, comprising: acquiring a first image of a substrate before reliability test; acquiring a second image of the substrate after the reliability test; determining a defect region of the substrate according to the first image and the second image; marking a region to be marked in the surface of the substrate corresponding to the defective region of the substrate. The area to be marked corresponding to the defect area is marked in a targeted manner, so that misjudgment of the defect mark is not easy to occur, the defect which is possibly generated after the substrate is used for a long time can be deduced according to the defect, and the defect can be improved in advance.)

1. A method for marking a defect on a substrate, comprising:

acquiring a first image of a substrate before reliability test;

acquiring a second image of the substrate after the reliability test;

determining a defect region of the substrate according to the first image and the second image;

marking a region to be marked in the surface of the substrate corresponding to the defective region of the substrate.

2. The method of claim 1, wherein determining the defective area of the substrate based on the first image and the second image comprises:

comparing image parameter values of the first image and the second image, and if an area with difference in image parameter values exists in the first image and the second image, determining the area as the defect area;

wherein the image parameter values comprise grayscale values and RGB color values.

3. The substrate defect marking method of claim 2, further comprising:

dividing the areas with the difference of the image parameter values into a plurality of independent sub-areas;

and selecting the sub-region with the screening area larger than or equal to a preset area value as the defect region.

4. The method according to claim 1, wherein the marking a region to be marked in the surface of the substrate corresponding to the defective region of the substrate comprises:

establishing a two-dimensional coordinate system by taking the substrate as a reference;

acquiring a position coordinate set corresponding to the area to be marked;

and marking according to the position coordinate set corresponding to the area to be marked.

5. The method of claim 4, wherein the marking according to the set of position coordinates corresponding to the region to be marked comprises:

identifying the contour line of the area to be marked according to the position coordinate set corresponding to the area to be marked;

and controlling an ink-jet mechanism to carry out ink-jet marking on the area to be marked along the contour line.

6. The substrate defect marking method according to claim 1, wherein the substrate comprises a plurality of base layers, and an adhesive layer is arranged between two adjacent base layers;

the substrate defect marking method further comprises:

and slicing and scanning the marked substrate in a direction parallel to the central line of the substrate to determine the bonding layer where the defect area of the substrate is located.

7. A substrate defect marking apparatus comprising an ink ejection mechanism and a controller, the controller comprising:

the first acquisition module is used for acquiring a first image of the substrate before the reliability test;

the first acquisition module is used for acquiring a second image of the substrate after the reliability test;

a defective region determining module for determining a defective region of the substrate based on the first image and the second image; and

and the control module is used for controlling the ink jet mechanism to mark an area to be marked, corresponding to the defect area of the substrate, in the surface of the substrate.

8. The substrate defect marking apparatus of claim 7, wherein the control module comprises:

the third acquisition module is used for establishing a two-dimensional coordinate system by taking the substrate as a reference and acquiring a position coordinate set corresponding to the area to be marked; and

and the control chip is used for identifying the contour line of the area to be marked according to the position coordinate set corresponding to the area to be marked and controlling the ink-jet mechanism to carry out ink-jet marking on the area to be marked along the contour line.

9. The substrate defect marking apparatus of claim 7, wherein the ink jetting mechanism comprises an ink jetting regulator and a nozzle;

the inkjet regulator is used to vary the size and/or number of ink drops ejected by the nozzle.

10. The substrate defect marking apparatus of claim 9, wherein the nozzles are inkjet electrodes;

the ink jet regulator is used for changing ink jet voltage led to the ink jet electrode so as to change the size and/or the number of ink drops ejected by the nozzle.

11. A substrate defect marking apparatus as defined in claim 10 wherein the ink ejection electrodes have oppositely disposed inlet and outlet ends;

the area of the end face of the outlet end is larger than that of the inlet end.

12. The substrate defect marking apparatus of claim 10, wherein the ink jetting mechanism further comprises an electrode plate supported below the substrate, the electrode plate having a polarity opposite to that of the ink jetting electrode.

Technical Field

The application relates to the technical field of defect marking for a display screen attaching process, in particular to a substrate defect marking method and device.

Background

The laminating process of display screen includes the process of laminating polaroid and optical glass, and polaroid and optical glass can produce the difficult defect that perceives of naked eye at the laminating in-process, lead to observing through the naked eye or observe the erroneous judgement that the defect mark appears easily with the help of the magnifying glass, and then lead to can't accurately improving in advance to this defect.

Disclosure of Invention

In view of the above, it is necessary to provide a substrate defect marking method and apparatus for solving the problem that erroneous judgment of a defect mark is likely to occur by visual observation or observation through a magnifying glass.

According to an aspect of the present application, there is provided a substrate defect marking method including:

acquiring a first image of a substrate before reliability test;

acquiring a second image of the substrate after the reliability test;

determining a defect region of the substrate according to the first image and the second image;

marking a region to be marked in the surface of the substrate corresponding to the defective region of the substrate.

In one of the embodiments, the first and second electrodes are,

the determining a defective region of the substrate from the first image and the second image comprises:

comparing image parameter values of the first image and the second image, and if an area with difference in image parameter values exists in the first image and the second image, determining the area as the defect area;

wherein the image parameter values comprise grayscale values and RGB color values.

In one embodiment, the substrate defect marking method further includes:

dividing the areas with the difference of the image parameter values into a plurality of independent sub-areas;

and selecting the sub-region with the screening area larger than or equal to a preset area value as the defect region.

In one of the embodiments, the first and second electrodes are,

the marking of the region to be marked in the surface of the substrate corresponding to the defective region of the substrate includes:

establishing a two-dimensional coordinate system by taking the substrate as a reference;

acquiring a position coordinate set corresponding to the area to be marked;

and marking according to the position coordinate set corresponding to the area to be marked.

In one embodiment, the marking according to the position coordinate set corresponding to the to-be-marked region includes:

identifying the contour line of the area to be marked according to the position coordinate set corresponding to the area to be marked;

and controlling an ink-jet mechanism to carry out ink-jet marking on the area to be marked along the contour line.

In one embodiment, the substrate comprises a plurality of base layers, and an adhesive layer is arranged between two adjacent base layers;

the substrate defect marking method further comprises:

and slicing and scanning the marked substrate in a direction parallel to the central line of the substrate to determine the bonding layer where the defect area of the substrate is located. According to another aspect of the present application, there is provided a substrate defect marking apparatus including an ink ejection mechanism and a controller, the controller including:

the first acquisition module is used for acquiring a first image of the substrate before the reliability test;

the first acquisition module is used for acquiring a second image of the substrate after the reliability test;

a defective region determining module for determining a defective region of the substrate based on the first image and the second image; and

and the control module is used for controlling the ink jet mechanism to mark an area to be marked, corresponding to the defect area of the substrate, in the surface of the substrate.

In one embodiment, the control module comprises:

the third acquisition module is used for establishing a two-dimensional coordinate system by taking the substrate as a reference and acquiring a position coordinate set corresponding to the area to be marked; and

and the control chip is used for identifying the contour line of the area to be marked according to the position coordinate set corresponding to the area to be marked and controlling the ink-jet mechanism to carry out ink-jet marking on the area to be marked along the contour line.

In one embodiment, the ink ejection mechanism includes an ink ejection regulator and a nozzle;

the inkjet regulator is used to vary the size and/or number of ink drops ejected by the nozzle.

In one embodiment, the nozzles are ink ejection electrodes;

the ink jet regulator is used for changing ink jet voltage led to the ink jet electrode so as to change the size and/or the number of ink drops ejected by the nozzle.

In one embodiment, the ink ejection electrodes have oppositely disposed inlet and outlet ends;

the area of the end face of the outlet end is larger than that of the inlet end.

In one embodiment, the ink jetting mechanism further comprises an electrode plate supported and disposed below the substrate, wherein the electrode plate and the ink jetting electrode have opposite polarities.

The substrate defect marking method and the substrate defect marking device have the advantages that the reliability test is utilized to enable the defects of the substrate to be shown in a short time, the state change and the generated defects of the substrate can be observed conveniently, in addition, the defect area corresponds to the defects shown after the reliability test, the area to be marked corresponding to the defect area is marked in a targeted mode, the misjudgment of the defect mark is not easy to occur, the defects which are possibly generated after the substrate is used for a long time can be deduced according to the defects, and the defects can be improved in advance.

Drawings

Fig. 1 is a schematic flow chart illustrating a substrate defect marking method according to an embodiment of the present disclosure;

FIG. 2 is a schematic diagram of a substrate according to an embodiment of the present disclosure;

FIG. 3 shows a schematic diagram of a first image in an embodiment of the present application;

FIG. 4 shows a schematic diagram of a second image in an embodiment of the present application;

FIG. 5 is a schematic diagram illustrating a process of marking a first area corresponding to a defective area on a second image in an embodiment of the present application;

fig. 6 is a schematic diagram illustrating a process of defect marking a to-be-marked area of a substrate by a substrate defect marking apparatus in an embodiment of the present application;

FIG. 7 is a schematic flow chart illustrating a method for marking defects on a substrate according to another embodiment of the present disclosure;

FIG. 8 is a schematic diagram illustrating the ink spraying process performed by the nozzle in one embodiment of the present application;

fig. 9 is a schematic diagram illustrating an ink spraying process performed by a nozzle according to another embodiment of the present application.

In the figure: 300. a substrate; 310. a first base layer; 320. a second base layer; 330. an adhesive layer; 340. a region to be marked; 400. an ink jet mechanism; 410. a nozzle; 420. an electrode plate; 500. a first region.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the present application are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is capable of embodiments in many different forms than those described herein and that modifications may be made by one skilled in the art without departing from the spirit and scope of the application and it is therefore not intended to be limited to the specific embodiments disclosed below.

In the description of the present application, it is to be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present application and for simplicity in description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the present application.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In this application, unless expressly stated or limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can include, for example, fixed connections, removable connections, or integral parts; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through intervening media. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.

Fig. 1 is a schematic flow chart illustrating a substrate defect marking method according to an embodiment of the present application.

Referring to fig. 1, an embodiment of the present application provides a method for marking a defect on a substrate, including the following steps:

s110, a first image of the substrate 300 before the reliability test is acquired. Referring to fig. 2, the substrate 300 includes a first base layer 310, a second base layer 320, and an adhesive layer 330 disposed between the first base layer 310 and the second base layer 320, wherein optionally, the first base layer 310 is optical glass, and the second base layer 320 is a polarizer.

In the embodiment shown in fig. 2, an example of a two-layer base layer is given. The structure of the substrate 300 is not limited to the embodiment shown in fig. 2, and in other embodiments, the substrate 300 is a multi-layer laminated structure.

And S120, acquiring a second image of the substrate 300 after the reliability test. The reliability test is to test the substrate 300 under severe conditions, so that the substrate 300 is aged in a short time to observe the state change of the adhesive layer 330 of the substrate 300 and the generated defect, and thus, the defect which may be generated after the substrate 300 is used for a long time can be deduced, and the defect can be improved in advance.

Optionally, the reliability test includes, but is not limited to, a temperature and humidity aging test, a cold and hot impact test, an ultraviolet aging test, a waterproof test, and the like.

Alternatively, the first image and the second image of the substrate 300 may be acquired by photographing.

And S130, determining a defect area of the substrate 300 according to the first image and the second image. Referring to fig. 3 and 4, fig. 3 corresponds to a first image of the substrate 300 before the reliability test, and fig. 4 corresponds to a second image of the substrate 300 after the reliability test, and comparing fig. 3 and 4, the defect regions of the substrate 300 corresponding to the differences can be determined from the differences of fig. 3 and 4.

S140, marking a region to be marked 340 corresponding to the defective region of the substrate 300 in the surface of the substrate 300. The reliability test is utilized to show the defects of the substrate 300 in a short time, so that the state change and the generated defects of the bonding layer 330 of the substrate 300 can be observed conveniently, in addition, the defect area corresponds to the defects shown after the reliability test, the area to be marked 340 corresponding to the defect area is marked in a targeted manner, the misjudgment of the defect mark is not easy to occur, the defects which are possibly generated after the substrate 300 is used for a long time can be deduced according to the defects, and the defects can be improved in advance. In the embodiment shown in fig. 2, the surface of the substrate 300 is the surface of the second base layer 320 away from the adhesive layer 330.

Further, the step S130 of determining the defective region of the substrate 300 according to the first image and the second image includes:

comparing the image parameter values of the first image and the second image, if there is a region with difference in image parameter values in the first image and the second image, determining that the region is a defective region, please refer to fig. 3 and 4 again, comparing the image parameter values of the first image in fig. 3 and the second image in fig. 4, specifically, the image parameter values include a gray value and RGB color values, etc. The corresponding defect area can be determined from the difference between the gray scale value and RGB color value of the pixel points in the first image in fig. 3 and the second image in fig. 4, please refer to fig. 5, or the first area 500 corresponding to the defect area can be marked on the second image.

Further, referring to fig. 5 again, the region having the difference in the image parameter values is divided into several independent sub-regions.

And screening the subarea with the area larger than or equal to the preset area value to be a defect area. The corresponding defects at the defect area comprise particle defects, breakage defects, bubble defects and the like, so that the defects can be improved in a targeted manner after marking.

In the embodiment shown in fig. 5, fig. 5 shows an example of two first regions 500, wherein one first region 500 is circular, and correspondingly, a defect region corresponding to the first region 500 on the substrate 300 is also circular, and the radius of the first region 500 is 20-100 μm, so that the area of the defect region is greater than or equal to a predetermined area value, which indicates that there is a high possibility of defects such as particle defects, breakage defects, and bubble defects at the defect region; the area of the other first region 500, which is independent of the circular first region 500, is also greater than the predetermined area value, and then the area of the other defect region, which is independent of the circular defect region, is also greater than the predetermined area value, and defects such as particle defects, breakage defects, and bubble defects may also exist at the other defect region. Corresponding improvements to the defect are subsequently required.

Specifically, in the embodiment shown in fig. 6, an example of marking one to-be-marked region 340 is shown in fig. 6, the to-be-marked region 340 is circular, the to-be-marked region 340 corresponds to the circular first region 500 in fig. 5, and the first region 500 corresponding to the defect region in fig. 5 can be referred to as a comparison reference for marking the to-be-marked region 340 of the substrate 300, so as to avoid the occurrence of missing marks. In comparison with fig. 5, the defect area corresponding to the another first region 500 (the another first region 500 independent from the circular first region 500) in fig. 5 has not been marked on the substrate 300, and the "leakage repairing" can be properly performed with reference to fig. 5.

Further, referring to fig. 7, in some embodiments, a method for marking a substrate defect includes:

s210, a first image of the substrate 300 before the reliability test is acquired.

S220, a second image of the substrate 300 after the reliability test is obtained.

And S230, determining a defect area of the substrate 300 according to the first image and the second image.

S240, establishing a two-dimensional coordinate system by taking the substrate 300 as a reference so as to obtain a position coordinate set corresponding to the to-be-marked area 340 corresponding to the defect area according to the position coordinate of the substrate 300. The position coordinate set is a set of position coordinates of all points in the region to be marked 340, wherein the position coordinates are two-dimensional coordinates.

And S250, acquiring a position coordinate set corresponding to the to-be-marked area 340.

And S260, marking according to the position coordinate set corresponding to the area to be marked 340.

Further, the step S260 of marking according to the position coordinate set corresponding to the to-be-marked region 340 includes:

and identifying the contour line of the area to be marked 340 according to the position coordinate set corresponding to the area to be marked 340.

The ink-jet mechanism 400 is controlled to ink-jet mark the area to be marked 340 along the contour line. Referring to fig. 6 again, the nozzle 410 of the ink-jet mechanism 400 is not in contact with the substrate 300, and the ink is transferred to the substrate 300 by jetting. The ink-jet marking can be performed on both horizontal and vertical surfaces. It is particularly suitable for ink jet marking of the substrate 300 with a curved surface. In addition, the region to be marked 340 of the substrate 300 is marked along the contour line, so that the region to be marked 340 can be accurately marked, the defect marking is more accurate, and the directionality for guiding and improving the corresponding defect is provided.

Further, the substrate 300 includes a plurality of base layers, and an adhesive layer 330 (as can be understood by referring to fig. 2) is disposed between two adjacent base layers, that is, the substrate 300 is a multi-layer laminated structure.

The substrate defect marking method further includes:

the marked substrate 300 is sliced and scanned in a direction parallel to the center line of the substrate 300 to determine the adhesive layer 330 where the defective area of the substrate 300 is located, so as to correspondingly improve the adhesive layer 330 where the defective area exists.

Since the substrate 300 has a multi-layer base lamination structure, it is necessary to determine the layer defects of the bonding layer 330 between two adjacent curved base layers, so that the substrate 300 can be sliced and scanned, and the bonding layer 330 where the defect area is located can be obtained.

Optionally, the substrate 300 is sliced and scanned using 3D-Xray detection analysis techniques.

Fig. 6 is a schematic diagram illustrating a process of defect marking by the substrate defect marking apparatus in an embodiment of the present application.

Referring to fig. 6 again, an embodiment of the defect marking apparatus includes an inkjet mechanism 400 and a controller, wherein the controller includes a first acquiring module, a second acquiring module, a determining module, and a control module.

The first acquiring module is used for acquiring a first image of the substrate 300 before the reliability test.

The second acquiring module is used for acquiring a second image of the substrate 300 after the reliability test.

The defective area determining module is configured to determine a defective area of the substrate 300 according to the first image and the second image.

The control module is used for controlling the ink jet mechanism 400 to mark the area to be marked 340 corresponding to the defect area of the substrate 300 in the surface of the substrate 300.

Further, the control module comprises a third acquisition module and a control chip.

The third obtaining module is configured to establish a two-dimensional coordinate system based on the substrate 300, and obtain a position coordinate set corresponding to the to-be-marked region 340 corresponding to the defect region.

And the control chip is used for identifying the contour line of the area to be marked 340 according to the position coordinate set corresponding to the area to be marked 340 and controlling the ink-jet mechanism 400 to perform ink-jet marking on the area to be marked 340 along the contour line. The defect marking accuracy can be improved by performing the guide marking along the contour line by means of the ink-jet mechanism 400.

Further, the ink jet mechanism 400 includes an ink jet regulator and the nozzles 410, the ink jet regulator is used for changing the size and/or the number of the ink drops ejected by the nozzles 410, and the size and/or the number of the ink drops can be reduced as required, so that the ink jet marking with a small area is performed, and the accuracy of the defect marking is further improved.

Further, the nozzles 410 are ink ejection electrodes, and the ink ejection regulator is configured to vary an ink ejection voltage applied to the ink ejection electrodes to vary the size and/or number of ink drops ejected from the nozzles 410. Specifically, an ink-jet voltage is applied to the ink-jet electrode to charge each ink droplet ejected from the nozzle 410, and the ink-jet voltage applied to the ink-jet electrode is reduced under the condition that the number of the ink droplets is not changed, so that the charge amount of each ink droplet can be reduced, the size of each ink droplet can be reduced (the charge amount of the ink droplet is in direct proportion to the size of the ink droplet), and then the ink-jet marking with a small area can be performed.

The ink jetting mechanism 400 further includes an ink recovery unit connected to the nozzle 410, and if the ink jetting marking is completed by the ink jetting mechanism 400, the charging of the ink droplets is controlled, for example, by reversing the polarity of the ink jetting electrode and the recovery electrode in the ink recovery unit, so that the ink droplets are absorbed and recovered in the ink recovery unit.

Further, referring to fig. 8, the ink-jetting electrode has an inlet end and an outlet end opposite to each other, and the area of the end surface of the outlet end is larger than that of the inlet end. The spraying range of the ink can be conveniently adjusted according to the requirement, so that the marking range of the ink mark can be adjusted. For example, the ink spraying range can be adjusted correspondingly according to the size of the area to be marked 340, and if the area of the area to be marked 340 is smaller in fig. 6, the ink spraying voltage applied to the ink spraying electrode can be reduced, so that the size of the ink can be reduced, and the ink spraying range can be reduced. The ink ejection voltage of the ink ejection electrode in fig. 9 is smaller than that of the ink ejection electrode in fig. 8, and it is obvious that the ejection range of the nozzle 410 in fig. 9 is smaller than that of the nozzle 410 in fig. 8, and a small area of the ink ejection mark can be realized.

Further, referring to fig. 6 again, the ink jet mechanism 400 further includes an electrode plate 420 supported below the substrate 300, the electrode plate 420 and the ink jet electrode have opposite polarities, and the attraction force of positive and negative charges between the electrode plate 420 and the charged ink drops ejected from the nozzle 410 is used to induce the charged ink to accurately fall into the region to be marked 340 and to be adsorbed to the region to be marked 340 of the substrate 300, which is beneficial for rapid and accurate marking.

Referring to fig. 3 and 4, the first image and the second image are two-dimensional images, which is more convenient to find the difference between the first image and the second image; referring to fig. 5 again, the defect area of the substrate 300 is determined according to the first image and the second image; establishing a two-dimensional coordinate system by taking the substrate 300 as a reference, and acquiring a position coordinate set corresponding to the to-be-marked area 340 of the defect area corresponding to the substrate 300; then, identifying the contour line of the area to be marked 340 according to the position coordinate set corresponding to the area to be marked 340; referring to fig. 6 again, the substrate 300 is disposed on the electrode plate 420, and referring to fig. 9, the inkjet voltage applied to the inkjet electrode is reduced, and finally the inkjet mechanism 400 performs inkjet marking on the region to be marked 340 of the substrate 300 along the contour line, and the electrode plate 420 can guide the charged ink to quickly and accurately mark in the region to be marked 340, so as to avoid erroneous judgment caused by manual operation and improve the accuracy of defect marking.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.