KR100859568B1 - Electrostatic capacitance type sensor for detecting liquid level and system - Google Patents

Abstract

The present invention by installing a capacitive sensor for measuring the level of the liquid stored in the liquid storage tank outside the liquid storage tank to prevent the generation of impurities due to reaction with the liquid to significantly reduce the defect rate generated in the liquid treatment process The present invention relates to a capacitive water level sensor and a system for lowering.

The present invention, the liquid storage tank for storing a liquid; A pipe connected upright from one side of the liquid storage tank and installed so that a portion of the liquid stored in the liquid storage tag flows through a through hole of a predetermined diameter so as to have the same level as the liquid stored in the liquid storage tank; A capacitive sensor installed on one side of an outer circumferential surface of the pipe to be in close contact with a predetermined height and detecting an amount of change in capacitance in accordance with the level of liquid introduced into the pipe; A signal processor for converting the amount of change in capacitance sensed by the capacitance detecting sensor into a level value; And a display unit for displaying the signal processing value processed by the signal processing unit.

Liquid, Capacitive, Sensor, Storage Tank, Pipe, Water Level, Electrode

Description

Electrostatic capacitance type sensor for detecting liquid level and system

1 is a view schematically showing the configuration of a capacitive water level detection system according to an embodiment of the present invention.

FIG. 2 is a view schematically illustrating an exploded perspective view of the capacitive water level sensor shown in FIG. 1 of the present invention.

3 is a cross-sectional view of the capacitive water level sensor shown in FIG.

4 is a diagram illustrating an electric field distribution curve formed by the capacitive water level sensor shown in FIG. 1.

FIG. 5 is a diagram schematically illustrating a configuration of a capacitive water level detection system according to an embodiment of the present invention.

FIG. 6 is a diagram illustrating an electric field distribution curve formed by the capacitive water level sensor shown in FIG. 5.

7 is a view showing a water level sensor according to the prior art.

8 is a view showing another water level sensor according to the prior art.

<Explanation of symbols for the main parts of the drawings>

110: liquid storage tank

120: pipe

130: capacitive sensor

140: fixed part

150: signal processing unit

160: display unit

170: auxiliary capacitance sensor

180: alarm unit

The present invention relates to a capacitive water level sensor and a system, in particular an impurity caused by reaction with a liquid by installing a capacitive sensor for measuring the level of the liquid stored in the liquid storage tank outside the liquid storage tank. The present invention relates to a capacitive water level sensor and system that prevents the formation of water, thereby significantly lowering the failure rate generated in the liquid processing process.

In general, fields such as semiconductors and LCDs require devices such as storage tanks that can store liquids such as water or chemicals and supply the correct amount depending on the intended use. At this time, by supplying a liquid such as a chemical to the place where the reaction takes place by measuring the supply amount using a flow meter.

However, most chemicals required for semiconductor or LCD processing have high toxicity or dissolve metal storage tanks, so that polymer compounds that are not soluble in these liquids are coated inside and outside metal containers to store liquids such as chemicals. use.

In addition, when chemicals are put into the storage tank from the outside, the height of the liquid surface in the storage tank is determined and the amount to be stored is determined, or the storage timing is determined according to the change in the liquid surface height. It can supply liquids such as chemicals.

Hereinafter, a water level sensor according to the prior art will be described with reference to FIG. 7, which is a view showing a water level sensor according to the prior art.

As shown in FIG. 7, in the prior art, in order to measure the height of the liquid surface, an ultrasonic sensor is used as a device for measuring the height of the liquid surface in the storage tank. That is, the ultrasonic sensor 11 is installed above the storage tank to measure the time when the sound waves are reflected from the surface of the liquid and return to measure the height d of the liquid surface.

However, the water level sensor as described above has the following problems.

First, when storing highly corrosive chemicals in storage tanks, impurities generated by reaction with ultrasonic sensors in the storage tanks enter chemicals and affect the precise processing of semiconductors and LCDs, thereby increasing the defect rate. .

Second, when the chemicals are dropped into the existing liquid surface when the chemicals are dropped into the storage tank, when the foam bubbles or the surface of the liquid is severely shaken, the ultrasonic sensor using the reflection from the surface does not accurately measure the height, so an error occurs and the accuracy to meet the standard Can't

Hereinafter, another level sensor according to the prior art will be described with reference to FIG. 8. FIG. 8 is a view showing another level sensor according to the related art.

The water level sensor shown in Figure 8, by inserting the probe rod 12 into the liquid to find a change in the height of the liquid surface according to the degree of the probe rod is locked, the problem that the generation of impurities due to the reaction of the chemical liquid and the probe rod can not be avoided There is this.

In order to solve the above problems, the present invention provides a capacitive sensor for measuring the level of the liquid stored in the liquid storage tank outside the liquid storage tank to prevent the generation of impurities by reaction with the liquid It is an object of the present invention to provide a capacitive water level sensor and system that significantly lowers the failure rate generated in the treatment process.

In order to achieve the above objects, the capacitive water level detection system according to an aspect of the present invention, the liquid storage tank for storing a liquid; A pipe connected to stand from one side of the liquid storage tank and installed so that a portion of the liquid stored in the liquid storage tag flows through a through hole of a predetermined diameter so as to have the same level as the liquid stored in the liquid storage tank; A capacitive sensor installed on one side of an outer circumferential surface of the pipe to be in close contact with a predetermined height and detecting an amount of change in capacitance in accordance with the level of liquid introduced into the pipe; A signal processor for converting the amount of change in capacitance sensed by the capacitance detecting sensor into a level value; And a display unit for displaying the signal processing value processed by the signal processing unit.

The sensing unit of the capacitive water level sensor according to another aspect of the present invention, the inner portion made of a cylindrical insulator; An electrode corresponding to the water level of the liquid flowed into the pipe consists of an anode installed to wrap the inner portion in a 90 ° arc shape toward the pipe containing the liquid and a cathode surrounding the inner portion in an arc shape of the remaining 270 °. An electrode unit for detecting the level of the liquid by detecting a change in capacitance according to the area change; And an outer part configured to have a cylindrical shape to surround the outer circumferential surface of the electrode part, to fix the anode and the cathode of the electrode part.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 to 4, a configuration of a capacitive water level detection system according to an embodiment of the present invention will be described. FIG. 1 is a view showing the configuration of a capacitive water level detection system according to an embodiment of the present invention. 2 is a schematic view showing an exploded perspective view of the capacitive water level sensor shown in FIG. 1 of the present invention, FIG. 3 is a cross-sectional view of the capacitive water level sensor shown in FIG. Is a diagram showing an electric field distribution curve formed by the capacitive water level sensor shown in FIG.

Capacitive water level detection system according to an embodiment of the present invention, the liquid storage tank 110, pipe 120, capacitive detection sensor 130, fixing unit 140, signal processing unit 150, display unit ( 160, the auxiliary capacitance detecting sensor 170 and the alarm unit 180.

The liquid storage tank 110 stores a liquid such as a chemical therein. A supply pipe 12 for supplying a liquid from the outside is installed at an upper portion thereof, and a connection hole 114 connected to the pipe 120 is formed at a lower surface thereof to allow the liquid inside to flow into the pipe 120.

Pipe 120 is installed so as to be connected to stand from the bottom of the liquid storage tank 110, a through hole of a predetermined diameter is formed therein, the liquid stored in the liquid storage tag 110 is introduced along the through hole to store the liquid It is to be the same height as the liquid stored in the tank (in this case, the liquid has the same height by the same air pressure because the upper through-hole 113 and the pipe 120 of the storage tank 110 is connected to each other).

In this case, the pipe 120 is preferably made of a non-conductor, such as a high molecular compound (eg, PE, PTFE) to withstand from a liquid such as chemicals.

The sensing unit 130 of the capacitive sensor is installed to be in close contact with a predetermined height on one side of the outer circumferential surface of the pipe 120, and detects a change in capacitance according to the level of the liquid introduced into the pipe 120, and the inner part ( 132, an electrode portion 134, and an outer portion 138.

The inner part 132 is made of a plastic of cylindrical shape to occupy the center of the capacitive sensor 130, and are installed side by side in the same direction along the pipe 120.

The electrode unit 134 is formed to surround the inner part 132, and is installed to be separated into the anode 135 and the cathode 136 to sense a change in capacitance according to a change in the area of the electrode contacting the liquid introduced into the pipe.

At this time, the anode 135 surrounds the inner portion 132 in an arc shape of 90 °, and is provided on the outer circumferential surface of the inner portion 132 as close as possible to the pipe 120. The cathode 136 wraps the remaining 270 ° portion of the inner portion 132 in an arc shape and is installed on the outer circumferential surface of the inner portion 132 as far as possible from the pipe 120.

The outer portion 138 has a cylindrical shape to surround the outer circumferential surface of the electrode portion 134 to fix the anode 135 and the cathode 136 of the electrode portion 130 to the inner portion 132.

The fixed part 140 accommodates the capacitive sensor 130 through the receiving groove 142 so that the sensor 130 of the capacitive sensor is in close contact with the pipe 120. Secure 130 to the pipe.

The signal processor 150 processes the signal through a detection circuit, an amplifier circuit, and an output circuit so as to convert the amount of change in capacitance detected by the sensing unit 130 of the capacitance sensor into a level value. That is, the change amount of the capacitance sensed by the sensing unit 130 of the capacitive sensor is converted into a water level value so that it can be recognized from the outside so as to be displayed on the display unit 160.

At this time, the detection circuit, the amplifier circuit and the output circuit is already known or widely used through the prior art, so a detailed description thereof will be omitted.

The display unit 160 displays the signal processing value processed by the signal processing unit 150 to the outside through the LED.

The auxiliary capacitance sensor 170 detects whether the level of the liquid introduced into the pipe 120 exceeds a preset maximum or minimum level.

That is, when the capacitive detection sensor 130 is not operated due to a failure or the like, when the level of the liquid introduced into the pipe 120 is out of the maximum or minimum level, it detects this and alerts the alarm unit 180. To transmit.

The alarm unit 180 notifies the outside through a speaker or the like according to the alarm signal transmitted from the auxiliary capacitance detecting sensor 170.

Hereinafter, a configuration of a capacitive water level sensor according to another embodiment of the present invention will be described with reference to FIGS. 5 and 6. FIG. 5 is an exploded perspective view of a capacitive water level sensor according to another embodiment of the present invention. 6 is a diagram illustrating an electric field distribution curve formed by the capacitive water level sensor shown in FIG. 5.

As shown in FIG. 5, the capacitive water level sensor 530 according to another embodiment of the present invention includes an inner portion 532, an electrode portion 534, a metal plate 537, and an outer portion 538.

The inner part 532 is made of a plastic of cylindrical shape to occupy the center of the capacitive sensor 530, and are installed side by side in the same direction along the pipe 520.

The electrode part 534 is formed to surround the inner part 532, and is installed to be separated into the positive electrode 535 and the negative electrode 536 to sense a change in capacitance according to a change in an area in contact with the liquid introduced into the pipe.

At this time, the anode 535 surrounds the inner portion 532 in an arc shape of 90 °, and is provided on the outer circumferential surface of the inner portion 532 as close as possible to the pipe 520. The cathode 536 surrounds the remaining 270 ° portion of the inner portion 532 in an arc shape and is installed on the outer circumferential surface of the inner portion 532 corresponding to the maximum distance from the pipe 520.

The metal plate 537 is made of a conductive material connected to the cathode 536 of the electrode part from one side of the fixing part 538, and increases the strength of the electric field penetrating the pipe 520 to flow into the pipe 520. The amount of change in capacitance caused by the change in the water level is linearly sensed.

At this time, the metal plate 537 preferably has a thin copper plate strip shape.

The outer portion 538 has a cylindrical shape to surround the outer circumferential surface of the electrode portion 530 to fix the anode 535 and the cathode 536 of the electrode portion 530 to the inner portion 532.

Those skilled in the art to which the present invention pertains will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. Therefore, the above-described embodiments are to be understood as illustrative in all respects and not as restrictive.

As described above, the present invention by installing a capacitive sensor for measuring the level of the liquid stored in the liquid storage tank outside the liquid storage tank to prevent the generation of impurities by reaction with the liquid in the liquid treatment process It significantly lowers the defective rate that occurs.

In addition, the present invention can improve the installation efficiency of the capacitive sensor by reducing the installation cost by installing both the positive and negative electrodes provided in the capacitive sensor in one direction of the measurement object.

In addition, the present invention by additionally installing a metal plate made of a conductive material connected to the external fixed portion from the cathode provided in the capacitive sensor to increase the strength of the electric field through the pipe to linearly detect the amount of change in capacitance .

Claims (6)

The liquid storage tank for storing the liquid and connected to stand from one side of the liquid storage tank and a portion of the liquid stored in the liquid storage tank is introduced through the through hole of a predetermined diameter to the same level as the liquid stored in the liquid storage tank A capacitive sensor installed in close contact with a predetermined height on one side of an outer circumferential surface of the pipe and configured to detect a change in capacitance according to the level of liquid introduced into the pipe, and in the capacitive sensor In the capacitive water level detection system comprising a signal processing unit for signal processing to convert the amount of change of the capacitance to a water level value, and a display unit for displaying the signal processing value processed by the signal processing unit, The capacitive sensing sensor may include an inner part made of a cylindrical insulator; Comprising an anode that is wrapped in the inner portion in an arc shape of 90 ° and facing the pipe and a cathode that wraps the inner portion in an arc shape of the remaining 270 ° to change the capacitance according to the change of the area in contact with the liquid introduced into the pipe An electrode unit for sensing; An outer portion formed of a cylindrical shape to surround the outer circumferential surface of the electrode portion to fix the anode and the cathode of the electrode portion; Capacitive water level detection system comprising a. The method of claim 1, An auxiliary capacitance sensor for detecting whether a level of the liquid introduced into the pipe exceeds a preset maximum or minimum level; And And a warning unit for generating an alarm signal when the level of the liquid detected by the auxiliary capacitance detecting sensor falls above a predetermined maximum level or below a minimum level. delete The method of claim 1, Capacitive water level detection system further comprises a fixing portion for fixing the capacitive sensor to the pipe so that the capacitive sensor is in close contact with the pipe uniformly. The method of claim 4, wherein It further comprises a metal plate of a conductive material connected to the cathode of the electrode portion from one side of the fixing portion to increase the electric field passing through the pipe so that the amount of change in the capacitance according to the change in the liquid level is linearly detected. Capacitive water level detection system. In the capacitive water level sensor, An inner portion made of a cylindrical insulator; The inner portion is made up of an anode installed to face the pipe containing the liquid while covering the 90 ° arc shape and the negative electrode surrounding the inner portion in an arc shape of the remaining 270 ° according to the change of the area in contact with the liquid introduced into the pipe An electrode unit for detecting a level of liquid by sensing a change in capacitance; And Capacitive water level sensor comprising a cylindrical portion to surround the outer peripheral surface of the electrode portion comprises an outer portion for fixing the positive electrode and the negative electrode of the electrode.

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