KR101148630B1 - Structure of water level sensor - Google Patents

Abstract

The present invention relates to a structure of a water level sensor, the structure of the water level sensor for measuring the level of the solution filled in a specific container according to the present invention, having a predetermined length in the longitudinal direction on at least one insulating film and spaced apart from each other in parallel And a first electrode and a second electrode, wherein the first electrode and the second electrode have a plurality of sections divided in a longitudinal direction, and the first electrode and the second electrode in the plurality of sections. A structure in which the separation distance or area of the electrode is different from each other or the separation distance or area of the first electrode and the second electrode is different from each other in two adjacent sections among the plurality of sections. A capacitive sensor having; And a signal processing unit electrically connected to the first electrode and the second electrode and generating a detection signal by detecting a water level through a sensing signal generated by a change in capacitance in the capacitance sensor. According to the present invention, even if the surface of the sensor is contaminated, it is possible to accurately measure the level, it is possible to measure the level of the solution by measuring the relative value of the capacitance.

Description

Structure of water level sensor

The present invention relates to the structure of the water level sensor, and the electrode intervals of the water level sensor are different for each section, so that even if the water level sensor is contaminated, the measurement object is contaminated, or the type of the solution is different, It is about.

In general, water level sensors are used to measure the water level in humidifiers, washing machines, water tanks, etc.In fields such as semiconductors and LCDs, liquids such as water or chemicals can be stored and stored in a storage tank that can supply the correct amount depending on the application. Water level sensors are used to measure the water level.

Such a water level sensor has been developed and used in various ways, and is currently expanding to an application field for a ubiquitous sensor network.

However, for ubiquitous sensor network service, the reliability of measurement tag should be high, small size and low cost. In addition, since the installation is easy and simple, the influence of the surrounding environment on the installation of the sensor tag should be small. Therefore, there is an increasing need for a sensor tag satisfying such a condition. In particular, there is an increasing need for a sensor capable of accurate measurement even when the surface of the sensor is contaminated.

Accordingly, an object of the present invention is to provide a structure of a water level sensor that can overcome the above-mentioned conventional problems.

Another object of the present invention is to provide a structure of a water level sensor capable of accurate water level measurement even if the sensor surface is contaminated.

Still another object of the present invention is to provide a structure of a level sensor that can measure the level of a solution by measuring a relative value of capacitance.

Still another object of the present invention is to provide a structure of a water level sensor that can measure the level and accurate measurement of various solutions by adjusting the interval or area between electrodes for each section.

According to an embodiment of the present invention for achieving some of the above technical problems, the structure of the water level sensor for measuring the level of the solution filled in a specific container according to the present invention, the length on the at least one insulating film in a longitudinal direction And a first electrode and a second electrode spaced apart from each other and arranged in parallel with each other, wherein the first electrode and the second electrode have a plurality of sections divided in a longitudinal direction, and wherein the first and second electrodes have a plurality of sections. The separation distance or area of the first electrode and the second electrode is different from each other, or the separation distance or area of the first electrode and the second electrode is in two adjacent sections among the plurality of sections. A capacitive sensor having a structure arranged differently from each other; And a signal processing unit electrically connected to the first electrode and the second electrode and generating a detection signal by detecting a water level through a sensing signal generated by a change in capacitance in the capacitance sensor.

The first electrode and the second electrode are arranged in parallel in a structure having a constant length and width in a first section, which is one of the plurality of sections, and the second section in a second section adjacent to the first section. The first electrode and the second electrode has an electrode structure in which a plurality of protrusions extending in the width direction toward the counter electrode are arranged at a predetermined interval, and the protrusions of the first electrode and the protrusions of the second electrode are engaged with each other. The first electrode and the second electrode may be disposed.

The first electrode and the second electrode are arranged in parallel in a structure having a constant length and width in a first section, which is one of the plurality of sections, and the second section in a second section adjacent to the first section. Each of the first electrode and the second electrode may have a structure in which the width of the first electrode and the second electrode are larger than that of the first section.

The first electrode and the second electrode are respectively disposed on two insulating films spaced apart from each other, the first electrode has a predetermined length and a constant width, the length of the second electrode is the first electrode The same width and width may be arranged differently for each section for each of the plurality of sections or may be differently arranged for each section in two adjacent sections.

According to another embodiment of the present invention for achieving some of the above technical problems, the structure of the water level sensor for measuring the level of the solution filled in a specific container according to the present invention, the inner surface of the hollow cylindrical structure in the longitudinal direction A first pattern having a structure in which an electrode is patterned by dividing into a plurality of sections, the area being differently patterned for each of the plurality of sections, or the area patterned differently for each section in two adjacent sections among the plurality of sections. A capacitive sensor having an electrode, and a second electrode having a predetermined length and having a constant thickness or width, the second electrode being spaced apart from the first electrode and inserted into the cylindrical structure; And a signal processing unit electrically connected to the first electrode and the second electrode and generating a detection signal by detecting a water level through a sensing signal generated by a change in capacitance in the capacitance sensor.

The cylindrical structure may be an insulator.

The first electrode has a predetermined length and a predetermined width in a first section of any one of the plurality of sections, and in the second section adjacent to the first section, the first electrode has a width of the cylindrical structure. It may have a structure extending in the circumferential direction to surround part or all of the second electrode.

According to another embodiment of the present invention for achieving some of the above technical problems, the structure of the water level sensor for measuring the level of the solution filled in a specific container according to the present invention, the first electrode having a hollow cylindrical structure and And a second electrode having a predetermined length and inserted into the first electrode spaced apart from the first electrode, wherein the second electrode has a plurality of sections divided in a longitudinal direction, and the plurality of sections. A capacitive sensor having a structure in which the thicknesses are different from each other or the thicknesses are arranged differently in sections in two adjacent sections adjacent to each other; And a signal processing unit electrically connected to the first electrode and the second electrode and generating a detection signal by detecting a water level through a sensing signal generated by a change in capacitance in the capacitance sensor.

In the first section, which is one of the plurality of sections, the second electrode has a predetermined length and a predetermined thickness, and in the second section adjacent to the first section, the second electrode is less than in the first section. It can have a larger thickness.

According to the present invention, even if the surface of the sensor is contaminated, it is possible to accurately measure the water level, it is possible to measure the level of the solution by measuring the relative value of the capacitance. In addition, by adjusting the intervals or areas of the electrodes for each section, it is possible to measure the water level and accurate measurement of various solutions having different permittivity.

1A to 1F are cross-sectional views of a process sequence showing a method of manufacturing a water level sensor according to an embodiment of the present invention in a process order;
Figure 2 is an enlarged view of only the electrode pattern of the water level sensor completed in Figure 1,
FIG. 3 is a graph illustrating an example of the capacitance slope of each electrode section of FIG. 2.
4 to 7 is a view showing the electrode structure of the water level sensor according to other embodiments of the present invention,
8 and 9 are views for explaining the principle of the water level measurement in the water level sensor having the structure of FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings without intending to intend to provide a thorough understanding of the present invention to a person having ordinary skill in the art to which the present invention belongs.

1A to 1F are cross-sectional views of a method of manufacturing a water level sensor according to an embodiment of the present invention in a process order.

As shown in Figure 1a, for the manufacture of the water level sensor according to an embodiment of the present invention, a first insulating film 100 is prepared. In addition, the conductive film 110 is adhered to the first insulating film 100 by using a laminating process.

The first insulating film 100 may be a polyethylene terephthalate (PET) film.

The conductive film 110 is formed of a material such as an electrode, an antenna, a circuit of a water level sensor, and a copper film is mainly used, but is not limited thereto, and a copper component such as brass or bronze is partially used. A copper alloy film contained as a material may be used. Of course, a film of another conductive material such as nickel, gold or silver may be used.

The laminating process may include a method of rolling coating with a laminating machine at a temperature of about 100 to 120 ° C. preheated in advance. The conductive film 110 may be coated in a temperature range outside the temperature of about 100 ~ 120 ℃ course.

As shown in FIG. 1B, a capacitive sensor pattern (electrode pattern) 110a including two electrodes spaced apart from each other by a photolithography process and an etching process on the conductive film 110 is disposed. ), And the PCB pattern 110b for circuit connection is formed in a batch process.

The antenna pattern 110c may also be formed in a batch process together with the capacitive sensor pattern 110a and the PCB pattern 110b. The antenna pattern 110c may be formed only when necessary. Hereinafter, a case where the antenna pattern 110c is formed together will be described.

In the photolithography process, a photosensitive dry film or a photoresist film is formed on the conductive film 110, and the capacitive sensor pattern 110a and the PCB pattern 110b are formed through an exposure and development process. And a mask pattern (not shown) for forming the antenna pattern 110c.

The etching process is a process of forming a portion of the capacitive sensor pattern 110a, the PCB pattern 110b, and the antenna pattern 110c by etching a portion of the conductive film 110 using the mask pattern. . The etching process may use a variety of etching methods, including wet etching, dry etching, plasma etching method.

Thereafter, the mask pattern is removed through a separate process including a cleaning process.

According to another example, the capacitive sensor pattern (110a), the PCB pattern (110b), and the antenna pattern (110c) may be formed of a metal or conductive thin film that can be produced by screen printing, deposition or sputtering process have. In addition, gold, silver, platinum, copper, nickel or the like may be formed by coating or etching using a deposition or sputtering process, or may be formed using carbon or silver as a screen printing method.

As shown in FIG. 1C, of the first insulating film 100 on which the capacitive sensor pattern 110a, the PCB pattern 110b, and the antenna pattern 110c are formed, the capacitive sensor pattern 110a. The second insulating film 120 is bonded only to the portion where the) is formed by using a laminating process.

Before the process of adhering the second insulating film 120, a plating process may be performed on the capacitive sensor pattern 110a, the PCB pattern 110b, and the antenna pattern 110c. The plating material used for the plating may be any one material selected from nickel (Ni), gold (Au), platinum (Pt), and silver (Ag). The plating process may be performed at least twice by different materials. For example, it is possible to carry out gold plating continuously after performing nickel plating.

The plating process may be an electroless plating process.

The plating process is to extremely lower the resistance of the capacitive sensor pattern 110a, the PCB pattern 110b, and the antenna pattern 110c, and the capacitive sensor pattern 110a and the PCB pattern 110b. And, and the antenna pattern 110c has the advantage of lowering the production cost than forming the nickel, gold, platinum, silver and the like.

The second insulating film 120 is to insulate and protect the capacitive sensor pattern 110a from liquid and to prevent damage. The second insulating film 120 may be made of a polyethylene terephthalate (PET) film.

In this case, a process of performing hydrophobic treatment on the second insulating film 120 may be added.

As shown in FIG. 1D, the adhesive material layer 130 is formed on the back side (bottom surface) of the first insulating film 100 in the form of a double-sided adhesive by a laminating process, a coating process, or an adhesive process. The adhesive material film 130 serves to serve as an adhesive tape, and is for bonding or fixing the completed water level sensor to a specific portion.

Therefore, the process of forming the adhesive material layer 130 may be performed after any one of the above-described processes, or after any one of the processes described below. It is also possible to be performed after the production of the water level sensor according to the present invention is completed.

In another embodiment, the adhesive material layer 130 may be formed on the second insulating film 120.

As shown in FIG. 1E, at least one Surface Mount Devices (SMD) type for signal processing on the PCB pattern 110b after the adhesive material film 130 or the second insulating film 120 is formed. The signal processor 140 may be formed by soldering the signal processor or bonding a chip for signal processing.

The SMD-type signal processing element is a generic term for elements used for signal processing among electronic components mounted on the surface of a printed board, and is mounted on one or both sides of the printed board by using surface mount technology (SMT). Can include them. In addition, the dedicated chip for signal processing may include an application-specific integrated circuit (ASIC) chip of a custom semiconductor type, which is separately manufactured or sold for signal processing of the water level sensor.

As shown in FIG. 1F, the signal processor 140 is molded to protect it from external influences. Epoxy or the like may be used as the material for the molding. The molding part 150 may include not only the signal processor 140 but also the PCB pattern 110b.

According to another embodiment of the present invention, the water level sensor may be generally manufactured by a PCB substrate manufacturing method well known to those skilled in the art. That is, after manufacturing the capacitive sensor pattern 110a, the PCB pattern 110b, and the antenna pattern 110c in the form of a general PCB, a method of coating the whole with an insulating material may be used.

According to another embodiment of the present invention, the capacitive sensor pattern 110a is manufactured by the manufacturing method of FIGS. 1A to 1F, and the signal processing unit 140 including the PCB pattern 110b is a general PCB. It is also possible to manufacture the water level sensor by a method of separately manufacturing in the form of a substrate and electrically connected to each other.

FIG. 2 is an enlarged view of only the electrode pattern of the water level sensor completed by the process of FIGS. 1A to 1F.

As shown in FIG. 2, the first electrode 110aa and the second electrode 110ab have a predetermined length in the longitudinal direction on one insulating film 100 and are spaced apart from each other in parallel.

The first electrode 110aa and the second electrode 110ab are divided into a plurality of sections 1, 2, and 3 in the longitudinal direction. In the plurality of sections 1, 2, and 3, the separation distance or the area of the first electrode 110aa and the second electrode 110ab may be different from each other.

In another embodiment, the first electrode 110aa and the second electrode 110ab in two sections (1 and 2, or 2 and 3) adjacent to each other among the plurality of sections (1, 2, 3). The separation distance or area of the may have a structure arranged differently for each section.

The first electrode 110aa and the second electrode 110ab have a constant length and width in a second section (eg, 2), which is one of the plurality of sections (1, 2, 3). Arranged parallel to the structure. In the first section (eg, 1) adjacent to the second section (eg, 2), the first electrode 110aa and the second electrode 110ab extend in the width direction toward the counter electrode. And a plurality of protruding protrusions are arranged at predetermined intervals, and the first electrode and the second electrode are formed in such a manner that the protrusions of the first electrode 110aa and the protrusions of the second electrode 110ab are engaged with each other. Can be deployed.

In other words, in the first section 1, the first electrode 110aa and the second electrode 110ab have a plurality of teeth (protrusions) of a quadrangular shape (or polygonal shape) protruding in the width direction. They are arranged at regular intervals, they are arranged with a certain distance in the longitudinal direction of the electrode. In addition, the teeth of the second electrode 110ab and the teeth of the first electrode 110aa are engaged with each other so that the first electrode 110aa and the second electrode 110ab are spaced apart from each other. .

One end of the first electrode 110aa and the second electrode 110ab having the arrangement structure as described above is electrically connected to the signal processor 140 through the PCB pattern 110b. The signal processor 140 is disposed on the upper ends of the first electrode 110aa and the second electrode 110ab in the drawing, and constitutes the capacitive sensor of the first electrode 110aa and the second electrode ( The water level is detected through the sensing signal generated at 110ab) to generate a detection signal.

3 is a graph showing a change in capacitance for each section in the water level sensor having the electrode structure as shown in FIG.

The capacitance (C; capacitance) of the level sensor is calculated by 'C = ε * A / d', where ε represents the dielectric constant of the dielectric material, A represents the cross-sectional area of the electrode, and d represents the length between the electrodes. Can be. Here, it is known that the relative dielectric constant of air has a value of approximately '1'.

In the above equation, the capacitance C is proportional to the dielectric constant and the area of the electrode, and inversely proportional to the distance (distance) between the electrodes.

In the water level measurement using the water level sensor, the relative dielectric constant of air is 1 while water has a relative dielectric constant of 80. Therefore, as the water level increases, a capacitor having a dielectric constant of 80 in a parallel connection structure of a capacitor having a dielectric constant of 1 and a capacitor having a dielectric constant of 80 The principle is to use the principle that the portion is gradually increased to increase the overall capacitance.

However, when measuring the water level using the film type water level sensor, there is a problem that various contaminants such as scales and microorganisms are adsorbed on the surface of the insulating film 100. The water level sensor as shown in FIGS. 3 and 4 is a method of measuring the capacitance (capacitance) in proportion to the dielectric constant of the material between the planar electrodes can measure the water level of water 80 times higher than the relative dielectric constant of the air.

However, if the surface of the sensor is contaminated, measurement reproducibility can be a problem as the initial capacitance and the rate of change of capacitance due to the change of dielectric constant are different. In order to solve this problem, it is necessary to use a method of measuring a relative value without measuring an absolute value of the capacitance of the water level sensor.

That is, as shown in FIG. 2, when the interval (separation distance) of the electrode for each section is different, the rate of change of capacitance varies for each section.

Even if the surface of the water level sensor is contaminated and the absolute value of the capacitance changes, the rate of change of capacitance is changed at the boundary of each section, and the level of the capacitance can be known through the signal processing circuit so that the water level can be measured.

By separating the intervals by adjusting the electrode gap of the level sensor, it is possible to measure the correct level even if the level sensor is contaminated by various contaminants.

For example, in the case of the first section 1 having a small distance between electrodes, the slope of the capacitance becomes larger than in the case of the second section 2 having a large distance between electrodes. Therefore, the water level can be measured by subdividing a section having a different distance between electrodes as necessary.

As can be seen from the formula for calculating the capacitance C in the same way, if the area of the electrode is changed for each section, the change rate of the capacitance can be obtained for each section. Can be.

In addition, it is possible to measure the water level of various solutions having different permittivity other than water without compensation.

In more detail, because the relative dielectric constant is different for a solution other than water, when the water level sensor according to the present invention is applied to a solution other than water, the capacitance value is changed even at the same water level. In this case, if the target value is adjusted according to the solution through signal processing, it is possible to accurately measure the level of the solution.

In fact, even in the case of water, the dielectric constant will be slightly different depending on what substance is contained. Therefore, it was cumbersome to develop various kinds of water level sensors in order to measure the level of various liquids having different dielectric constants. However, as in the present invention, even if the relative dielectric constant of the liquid is changed by performing the section-by-section measurement, there is no problem in the water level measurement because the interval of each section does not change.

In addition, as shown in FIG. 3, since the change rate of the capacitance in each section, that is, the slope is different, various information such as the contamination level of the water level sensor and the contamination degree of the solution may be obtained by measuring the capacitance slope of the specific section. .

Pollution of the water level sensor means that an impurity film such as microorganisms is formed on the surface of the water level sensor (on the insulating film for protection), and in this case, since the insulating layer is thickened and the dielectric constant is changed, the capacitance value at the same level may be changed. . In particular, when PET film used as a protective insulating film, since the PET film is originally hydrophobic film, if it is not contaminated, the water does not adhere to the surface, but when it is contaminated with microorganisms, the characteristic is changed to hydrophilicity and the capacitance value is greatly changed. The problem arises. Even when such a problem occurs, it is possible to monitor the degree of contamination of the solution (change of permittivity when water is contaminated) because the capacitance gradient (change rate) changes in each section.

Figure 4 shows the electrode structure of the water level sensor according to another embodiment of the present invention. Except for the electrode structure of the water level sensor in Figure 4, the rest of the structure or manufacturing method is the same as described in FIG.

As shown in FIG. 4, the first electrode 110aa and the second electrode 110ab constituting the water level sensor have a predetermined length in the longitudinal direction on one insulating film 100 and are spaced apart from each other in parallel. .

The first electrode 110aa and the second electrode 110ab are divided into a plurality of sections 1, 2, and 3 in the longitudinal direction. In the plurality of sections 1, 2, and 3, the separation distance or the area of the first electrode 110aa and the second electrode 110ab may be different from each other.

In another embodiment, the first electrode 110aa and the second electrode 110ab in two sections (1 and 2, or 2 and 3) adjacent to each other among the plurality of sections (1, 2, 3). The separation distance or area of the may have a structure arranged differently for each section.

More specifically, in the second section 2, which is one of the plurality of sections 1, 2, and 3, the first electrode and the second electrode are arranged in parallel in a constant length and width. Each of the first electrode and the second electrode may have a structure in which the width of the first electrode and the second electrode is wider than that of the second section 2 in the first section 1 and 3 adjacent to the second section 2. have. As shown in FIG. 4, the width-expanding direction may be a direction toward the counter electrode, or may be the opposite direction. In other words, the separation distance (interval) between the first sections 1 and 3 in the second section 2 is larger.

Particularly, in the case where the width-expansion direction of the first electrode and the second electrode is arranged toward the counter electrode in the first section (1,3), the distance between the electrodes (d) and the area (A) are all different. The slope difference for each section of the capacitance can be increased.

5A illustrates an electrode structure of a water level sensor according to another embodiment of the present invention, FIG. 5B is a cross-sectional view taken along line AA ′ of FIG. 5A, and FIG. 5C is a cross-sectional view taken along line BB ′ of FIG. 5A.

Except for the electrode structures facing each other in the water level sensor in FIG. 5A, the remaining structure or manufacturing method is the same as described with reference to FIG. 1. Here, the structure except for the electrode structure may be variously changed and configured at the level of those skilled in the art to which the present invention belongs. For example, the signal processor and the antenna may be mounted on a separate substrate, or may be implemented on any one of two insulating films provided with electrodes.

In FIG. 5, the spacing between electrodes is the same as the spacing of the insulating films 100a and 100b. This case illustrates a case in which one of the two electrodes 110aa and 110ab has a different area for each section.

As shown in FIG. 5, the first electrode 110ab and the second electrode 110aa constituting the water level sensor have a predetermined length in the length direction on each of the two insulating films 100a and 100b spaced apart from each other. Spaced apart in parallel. And a plastic film for protecting the electrodes may be adhered on top of the electrodes, or an insulating material may be coated, which is not separately indicated.

The first electrode 110ab and the second electrode 110aa are divided into a plurality of sections 1, 2, and 3 in the longitudinal direction. Areas of the first electrode 110ab and the second electrode 110aa in the plurality of sections 1, 2, and 3 may be differently arranged for each section.

In another embodiment, the first electrode 110ab and the second electrode 110aa in two sections 1 and 2 or 2 and 3 adjacent to each other among the plurality of sections 1, 2 and 3. The area of may have a structure arranged differently for each section.

That is, the first electrode 110ab has a predetermined length on the first insulating film 100a and the width is uniformly arranged in the entire section, and the second electrode 110aa has a length on the second insulating film 100b. The same width as the first electrode 110ab and the width of each of the plurality of sections (1, 2, 3) are arranged in different sections or adjacent to each other in two sections (1 and 2, or 2 and 3). Each section may have a structure arranged differently.

For example, the width of the second electrode 110aa in the first section 1 may be configured to be larger or smaller than the width of the second electrode 110aa in the second section 2. In this case, the slope of the capacitance changes according to the difference in width. The larger the difference in width, the larger the difference in capacitance slope.

6 and 7 illustrate a water level sensor electrode structure according to still another embodiment of the present invention, showing a case having a cylindrical structure.

As shown in FIG. 6, the electrodes of the water level sensor according to another embodiment of the present invention have a structure including a hollow cylindrical structure 200, a first electrode 220b, and a second electrode 220a. Have

The first electrode 220b has a structure in which an electrode is patterned by dividing an inner surface of the hollow cylindrical structure 200 into a plurality of sections in a longitudinal direction. In this case, the first electrode 220b may have a structure in which an area is patterned differently for each of the plurality of sections, or an area is patterned differently for each section in two adjacent sections among the plurality of sections.

The second electrode 220a has a predetermined length and has a structure in which a thickness or a width is constant and inserted into the cylindrical structure to be spaced apart from the first electrode.

At this time, the cylindrical structure 200 should be an insulator.

The first electrode 220b or the second electrode 220a may be coated with an insulating material such as Teflon.

The first electrode 220b has a predetermined length and a predetermined width in one section, which is one of the plurality of sections, and has a width in the second section adjacent to the first section, the width of the cylindrical structure 200. It may have a structure extending in the circumferential direction to surround part or all of the second electrode (220a).

For example, the first electrode 220b may have a structure in which the pattern of the first section and the pattern of the second section are repeated in the longitudinal direction, or may have a structure in which the width thereof is different for each section. .

Accordingly, it is possible to facilitate the level measurement by changing the slope of the capacitance in accordance with the difference in the width of the electrode for each section.

As shown in FIG. 7, the electrodes of the water level sensor according to another embodiment of the present invention have a predetermined length with a first electrode 240a having a hollow cylindrical structure and have a predetermined length inside the first electrode 240a. The electrode structure includes a second electrode 240b spaced apart from the first electrode 240a.

The first electrode 240a has a hollow cylindrical structure and should be a conductor in its entirety.

Of course, the outer surface or the inner surface of the first electrode 240a may be coated with an insulating material such as Teflon or other materials. The same applies to the case of the second electrode 240b.

The second electrode 240b includes a plurality of sections divided in a longitudinal direction, and the thicknesses of the plurality of sections are different from each other, or the thicknesses of the second electrodes 240b are different from each other in two adjacent sections. It has a structure.

For example, the second electrode 240b has a predetermined length and a predetermined thickness in a first section, which is one of the plurality of sections, and the second electrode in a second section adjacent to the first section. May have a larger thickness than in the first section.

When the cross-sectional structure of the second electrode 240b has a circular shape, the second electrode 240b may have a larger diameter in the second section than in the first section.

In addition, the second electrode 240b may have a structure in which the pattern of the first section and the pattern of the second section are repeated in the longitudinal direction, or may have a structure in which the thickness or diameter thereof is different for each section. .

8 and 9 are diagrams for explaining the principle of the water level measurement in the water level sensor having the electrode structure of FIGS. 1 to 7, the case having the electrode structure of FIG.

8 illustrates a case where the electrodes 110aa and 110ab constituting the level sensor are exposed to no liquid (eg, water), and FIG. 9 illustrates the electrodes 110aa and 110ab constituting the level sensor. The change in capacitance when exposed to the presence of a liquid (eg water) is shown.

As shown in FIG. 8, when no liquid is present, the capacitance value C between the first electrode 110aa and the second electrode 110ab is 'C = ε * A / d' ( Where ε represents the dielectric constant of the dielectric material, A represents the cross-sectional area of the electrode, and d represents the length between the electrode plates. Here, it is known that the relative dielectric constant of air has a value of approximately '1'.

In addition, as shown in FIG. 9, even when liquid is present, the capacitance value can be calculated by the above equation, and when the liquid is water, the relative dielectric constant of water is known as approximately '80'.

Therefore, as the liquid level becomes higher and higher, the capacitance value C through the first electrode 110aa and the second electrode 110ab increases in proportion, and the capacitance value obtained in proportion to the liquid level is read. It is possible to determine the level of the liquid through the signal processor 140.

The water level sensor according to the present invention can be applied not only to the water level sensor for measuring the level of liquid, but also to a rain sensor for measuring the presence or absence of rainfall. The rainfall measurement mechanism can measure the presence or absence of rain because the change of capacitance occurs due to the change of the relative dielectric constant when rain occurs on the sensor and rainwater falls on the sensor.

As described above, the water level sensor according to the present invention can accurately measure the water level even if the sensor surface is contaminated, and can measure the water level of the solution by measuring the relative value of the capacitance. And it is possible to measure the level and accurate measurement of the various solutions by adjusting the interval or area between the electrodes for each section.

In addition, since the conductive film is adhered on the insulating film by a laminating process and the electrode is formed by a photolithography and etching process, mass production is easy. In addition, sensors of various shapes and sizes can be manufactured, and the cost of the sensor can be very low due to low material costs.

In addition, since the sensitivity of the sensor is relatively high and the sensor is manufactured using a film such as plastic, the sensor is flexible and lightweight, and thus it is easy to be mounted on the structure. If an adhesive material film (adhesive tape) is formed on the back or front of the sensor, it can be easily attached and mounted on the structure without special device design. In other words, the capacitive plastic film level sensor using PET film can be attached to various types of structures because the sensor itself is flexible, so that the utilization of the level sensor can be increased. In addition, it is possible to bond the electrode and the electrode protective film in a batch process on the PET film, so that mass production is possible, and thus, there is an advantage of lowering the production cost of the sensor.

The foregoing description of the embodiments is merely illustrative of the present invention with reference to the drawings for a more thorough understanding of the present invention, and thus should not be construed as limiting the present invention. It will be apparent to those skilled in the art that various changes and modifications may be made without departing from the basic principles of the present invention.

100: first insulating film, 110aa, 110ab: electrode
110c: antenna 140: signal processing unit

Claims (9)

In the construction of a level sensor for measuring the level of a solution filled in a specific container:
A first electrode and a second electrode having a predetermined length in the longitudinal direction on the at least one insulating film and spaced apart from each other in parallel with each other, wherein the first electrode and the second electrode are divided into a plurality of sections And a separation distance or an area of the first electrode and the second electrode in the plurality of sections is different from each other, or the first electrode in two sections adjacent to each other among the plurality of sections. A capacitive sensor having a structure in which the separation distance or the area of the second electrode is different from each other in each section;
And a signal processing unit electrically connected to the first electrode and the second electrode and generating a detection signal by detecting a water level using a sensing signal generated by a change in capacitance in the capacitance sensor. The structure of the water level sensor. The method according to claim 1,
In the first section, which is one of the plurality of sections, the first electrode and the second electrode are arranged in parallel in a structure having a constant length and width, and in the second section adjacent to the first section, the first electrode and the second electrode are disposed in parallel. The first electrode and the second electrode have an electrode structure in which a plurality of protrusions extending in the width direction toward the counter electrode are arranged at a predetermined interval, and the protrusions of the first electrode and the protrusions of the second electrode are engaged with each other. The structure of the water level sensor, characterized in that the first electrode and the second electrode is disposed. The method according to claim 1,
The first electrode and the second electrode are arranged in parallel in a structure having a constant length and width in a first section, which is one of the plurality of sections, and the second section in a second section adjacent to the first section. Each of the first electrode and the second electrode has a structure in which the width is larger than that in the first section is arranged. The method according to claim 1,
The first electrode and the second electrode are disposed on two opposing insulating films spaced apart from each other, the first electrode has a predetermined length and a constant width, and the length of the second electrode is the first electrode. The structure of the water level sensor, which is disposed in the same manner as one electrode and has a structure in which the width is different from each other in each of the plurality of sections or in the two adjacent sections. In the construction of a level sensor for measuring the level of a solution filled in a specific container:
The electrode is patterned by dividing the inner surface of the hollow cylindrical structure into a plurality of sections in the longitudinal direction, and patterning the area differently for each of the plurality of sections, or in two sections adjacent to each other among the plurality of sections. Capacitive sensor having a first electrode having a structure patterned differently for each area, and a second electrode which is spaced apart from the first electrode in the cylindrical structure having a predetermined length and a constant thickness or width Wow;
And a signal processing unit electrically connected to the first electrode and the second electrode and generating a detection signal by detecting a water level using a sensing signal generated by a change in capacitance in the capacitance sensor. The structure of the water level sensor. The method according to claim 5,
The cylindrical structure is a structure of a water level sensor, characterized in that the insulator. The method of claim 6,
The first electrode has a predetermined length and a predetermined width in a first section of any one of the plurality of sections, and in the second section adjacent to the first section, the first electrode has a width of the cylindrical structure. The structure of the water level sensor, characterized in that it has a structure extending in the circumferential direction to surround part or all of the second electrode. In the construction of a level sensor for measuring the level of a solution filled in a specific container:
A first electrode having a hollow cylindrical structure and a second electrode having a predetermined length and inserted into the first electrode spaced apart from the first electrode, wherein the second electrode is a plurality of longitudinally divided A capacitive sensor having a section of which the thickness is arranged differently for each of the plurality of sections, or the thickness of the sections being different for each section in two adjacent sections adjacent to each other;
And a signal processor electrically connected to the first electrode and the second electrode and generating a detection signal by detecting a water level through a sensing signal generated by a change in capacitance in the capacitance sensor. The structure of the water level sensor. The method according to claim 8,
In the first section, which is one of the plurality of sections, the second electrode has a predetermined length and a predetermined thickness, and in the second section adjacent to the first section, the second electrode is less than in the first section. The structure of the water level sensor characterized by having a greater thickness.

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