KR20170115899A - Measurement apparatus and method for liquid thickness - Google Patents

Abstract

A liquid film thickness measuring apparatus according to an embodiment of the present invention includes a flexible printed circuit board having a first electrode as an applied electrode, a second electrode and a third electrode as measurement electrodes, And a power applying unit for applying power to the first electrode, wherein when power is applied to the first electrode, the power is supplied from the first electrode to the second electrode and the second electrode through the fluid of the liquid film, The thickness of the liquid film is calculated based on the first current value and the second current value that are respectively transmitted to the three electrodes.

Description

TECHNICAL FIELD [0001] The present invention relates to a liquid film thickness measuring apparatus and a liquid film thickness measuring method,

The present invention relates to a liquid film thickness measuring apparatus and a liquid film thickness measuring method, and more particularly, to an apparatus and a method for measuring a liquid film thickness using a three-electrode flexible printed circuit board.

Techniques for measuring a liquid film present on a flat surface are various, and examples thereof include an electric conductivity method, a radiation attenuation method, and an ultrasonic method. In the case of the liquid film thickness measurement using the electric conductivity, the thickness of the liquid film is measured by measuring the current flowing from the application electrode 2 to the measurement electrode 3 as shown in Fig. 1 and inversely calculating the liquid film thickness .

The magnitude of the current flowing from the applying electrode 2 to the measuring electrode 3 is determined by the resistance or the impedance of the fluid constituting the liquid film and the magnitude of the current flowing from the applying electrode 2 to the measuring electrode The current flowing from the applying electrode 2 to the measuring electrode 3 is further increased because the resistance or impedance is reduced by the Ohm's law when the thickness t of the liquid film formed on the upper electrode 3 becomes thicker . As a result, the thickness of the liquid film is calculated by using the correlation between the thickness of the liquid film and the current flowing from the applying electrode 2 to the measuring electrode 3. Such a liquid film measuring method must take into consideration the electric conductivity of the fluid, and the magnitude of the electric current described above is changed by the electric conductivity of the fluid.

FIG. 2 is a graph showing a change in the electrical conductivity of water with respect to temperature. In general, the electrical conductivity of the fluid varies with the temperature of the fluid. For example, in the case of water, a conductivity of about 2% Can be confirmed in Fig.

Therefore, in the case of the liquid film measurement method described above, there is a problem that only the measurement of the liquid film flow in the isothermal state is possible because the current value varies depending on the temperature of the fluid. In general, the two-phase flow has many flow conditions accompanied by heat transfer. Therefore, it is necessary to measure the liquid film under the changing flow conditions in order to carry out the experiment reflecting the realistic conditions.

The following prior art document only discloses an apparatus and method for measuring liquid film thickness using liquid film refraction, but does not disclose the technical point of the present invention.

Korean Patent Registration No. 10-1542017

A liquid film thickness measuring apparatus and a liquid film thickness measuring method according to an embodiment of the present invention aim to solve the following problems.

The present invention proposes a liquid film thickness measuring apparatus and a measuring method capable of accurately measuring the liquid film thickness even under a flow condition in which the temperature of the liquid changes by minimizing the influence of the liquid film temperature change.

The present invention also proposes a liquid film thickness measuring apparatus and a measuring method which are capable of measuring the thickness of a liquid film formed on a curved surface including a dynamic curved surface and further applicable to a high temperature environment.

The solution to the problem of the present invention is not limited to those mentioned above, and other solutions not mentioned can be clearly understood by those skilled in the art from the following description.

A liquid film thickness measuring apparatus according to an embodiment of the present invention includes a flexible printed circuit board having a first electrode as an applied electrode, a second electrode and a third electrode as measurement electrodes, And a power applying unit for applying power to the first electrode, wherein when power is applied to the first electrode, the power is supplied from the first electrode to the second electrode and the second electrode through the fluid of the liquid film, The thickness of the liquid film is calculated based on the first current value and the second current value that are respectively transmitted to the three electrodes.

A flexible printed circuit board for measuring a liquid film thickness according to an embodiment of the present invention is a flexible printed circuit board included in an apparatus for measuring a liquid film thickness for measuring a thickness of a liquid film, ; And a second electrode and a third electrode that receive currents that flow from the first electrode and pass through the fluid of the liquid membrane when power is applied to the first electrode, Based on the first current value received by the second electrode and the second current value received by the third electrode.

The liquid film thickness measuring method according to an embodiment of the present invention includes measuring a liquid film thickness using a liquid film thickness measuring apparatus including a first electrode as an applied electrode and a flexible printed circuit board having second and third electrodes as measurement electrodes The method comprising: disposing the flexible printed circuit board in a liquid film; Applying power to the first electrode; Detecting a first current value and a second current value that flow from the first electrode and pass through the fluid of the liquid film to the second electrode and the third electrode, respectively; And calculating the thickness of the liquid film based on the first current value and the second current value.

The apparatus and method for measuring liquid film thickness according to an embodiment of the present invention are capable of measuring a liquid film on a curved surface including a dynamic curved surface by forming an applied electrode and a measuring electrode on a flexible printed circuit board (FPCB) The present invention can be applied even in a high temperature environment.

Further, by measuring the thickness of the liquid film by using the ratio of the two current values flowing through the two measurement electrodes from the application electrode to two measurement electrodes, even if there is a temperature change of the liquid forming the liquid film, The effect of ensuring the measurement of the thickness of the liquid film can be expected.

The effects of the present invention are not limited to those mentioned above, and other effects not mentioned may be clearly understood by those skilled in the art from the following description.

1 is a view showing a conventional liquid film thickness measuring apparatus.
2 is a graph showing the amount of change in electrical conductivity of water with temperature.
3 is a cross-sectional view of a flexible printed circuit board in an apparatus for measuring liquid film thickness according to an embodiment of the present invention.
4 is a view showing an apparatus for measuring a liquid film thickness according to an embodiment of the present invention.
5 is a front view of a flexible printed circuit board in an apparatus for measuring liquid film thickness according to an embodiment of the present invention.
6 is a graph showing a current ratio signal according to a liquid film thickness in an experimental result using a liquid film thickness measuring apparatus according to an embodiment of the present invention.
FIG. 7 is a graph showing current and current ratio signals according to temperature changes in an experimental result using a liquid film thickness measuring apparatus according to an embodiment of the present invention.
FIG. 8 is a flowchart illustrating a time-lapse thermal film thickness measuring method according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout.

In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. It is to be noted that the accompanying drawings are only for the purpose of facilitating understanding of the present invention, and should not be construed as limiting the scope of the present invention with reference to the accompanying drawings.

Hereinafter, a liquid film thickness measuring apparatus according to an embodiment of the present invention will be described with reference to FIGS. 3 to 7. FIG. FIG. 3 is a cross-sectional view of a flexible printed circuit board in a liquid film thickness measuring apparatus according to an embodiment of the present invention, FIG. 4 is a view illustrating an apparatus for measuring liquid film thickness according to an embodiment of the present invention, FIG. 6 is a graph showing a current ratio signal according to a liquid film thickness in an experimental result using a liquid film thickness measuring apparatus according to an embodiment of the present invention. FIG. And FIG. 7 is a graph showing a current and a current ratio signal according to a temperature change in an experimental result using a liquid film thickness measuring apparatus according to an embodiment of the present invention.

The liquid film thickness measuring apparatus according to an embodiment of the present invention includes a flexible printed circuit board 100 on which three electrodes are formed. Specifically, the flexible printed circuit board 100 includes a first electrode 110, A second electrode 120 and a third electrode 130, which are measurement electrodes, are formed.

The flexible printed circuit board 100 is disposed inside a liquid film formed on a flat or curved surface, and the first electrode 110 receives power from a power application unit 200 to be described later.

The first current value I1 and the second current value I2 flowing from the first electrode 110 and passing through the fluid in the liquid film 10 to the second electrode 120 and the third electrode 130, respectively, I2), the thickness of the liquid film 10 can be calculated.

Specifically, the thickness of the liquid film 10 is calculated by the ratio of the first current value I1 and the second current value I2. In this case, even when the fluid temperature changes, the first current value I1 and the second current value I2 Since the second current value I2 varies together and this current ratio can be regarded as being independent of the temperature change of the fluid during the measurement of the liquid film thickness, there is an advantage that the liquid film thickness can be measured even in the state of the temperature change of the fluid.

The flexible printed circuit board 100 is mainly used in information technology (IT) and micro-electrical mechanical system (MEMS). The flexible printed circuit board 100 is used in a liquid film thickness measuring apparatus according to an embodiment of the present invention. Unlike a plastic insulating substrate of a general printed circuit board, it is made of a polyimide (PI) film and thus has excellent ductility and heat resistance.

Therefore, the liquid film thickness measuring apparatus according to an embodiment of the present invention is capable of measuring the thickness of a liquid film formed on a curved surface rather than a flat surface, and is also applicable to a high temperature condition.

5, the first electrode 110, the second electrode 120, and the third electrode 130 formed on the flexible printed circuit board 100 are formed along the longitudinal direction of the flexible circuit board 100, The electrodes are arranged in a line, with each electrode being spaced apart from one another.

Particularly, it is preferable to form a ground electrode or a pattern 140 on both sides of the second electrode 120 and the third electrode 130 which are the measuring electrodes. Through the second electrode 120 and the third electrode 130, The current values having a constant current distribution can be transmitted to the electrode 130.

In addition, the flexible printed circuit board 100 should not have a separate pattern for electrical conduction between the first electrode 110, the second electrode 120, and the third electrode 130 .

As shown in FIG. 4, the liquid film thickness measuring apparatus according to an embodiment of the present invention includes a power applying unit 200, a first amplifier (not shown) 310, a second amplifier 320, and a calculation unit 400. [

The power applying unit 200 may be a function generator that applies a power to the first electrode 110 and is capable of applying an AC voltage having a specific size and period.

The first amplifier 310 and the second amplifier 320 are electrically connected to the second electrode 120 and the third electrode 130 and the first current I1 and the second current I2 acquired by the second electrode 120 And amplifies the second current I2 obtained by the third electrode 130, respectively.

In particular, the first amplifier and the second amplifier are preferably composed of a lock-in amplifier. In addition to the signal to be measured, the lock-in amplifier inputs a reference signal having a phase relationship with a predetermined frequency, It is possible to rectify and extract only a measurement signal having the same frequency and phase as that of the received signal, so that the signal embedded in the noise can be detected and amplified.

Meanwhile, it is preferable that the first current value I1 and the second current value I2 are obtained at the same time.

The calculation unit 400 calculates the thickness of the liquid film 10 based on the first current value I1 amplified by the first amplifier 310 and the second current value I2 amplified by the second amplifier 320. [ .

Specifically, the calculator 400 calculates the thickness of the liquid film 10 based on the ratio of the amplified first current value I1 and the second current value I2 to the first current value I2 The relationship between the ratio I2 / I1 of the first current I1 and the second current I2 and the thickness of the liquid film 10 is determined by the relationship between the first electrode 110, the second electrode 120, And the position and shape of the third electrode 130.

For example, when the size and position of the first electrode 110 shown in FIG. 5 are taken differently, a graph showing the correlation between the current ratio I2 / I1 and the liquid film thickness t is formed differently from FIG. 6 .

Therefore, it is preferable that the calculation unit 400 stores the correlation between the current ratio I2 / I1 and the liquid film thickness t according to the measurement conditions such as the kind of the fluid, the position of the electrodes, or the shapes of the electrodes.

As described above, the calculating unit 400 calculates the liquid film thickness t based on the current ratio I2 / I1 formed at the second electrode 110 and the third electrode 120, which are the two measurement electrodes, Even if the temperature of the fluid on the liquid film changes, it is possible to measure the exact liquid film thickness, which can be seen in Fig.

Hereinafter, a liquid film thickness measuring method according to an embodiment of the present invention will be described with reference to FIG. 8. In the description of the apparatus for measuring liquid film thickness according to an embodiment of the present invention, No detailed description is required. FIG. 8 is a flowchart illustrating a time-lapse thermal film thickness measuring method according to an embodiment of the present invention.

The liquid film thickness measuring method according to an embodiment of the present invention includes a first electrode 110 as an applied electrode and a flexible printed circuit board 100 having a second electrode 120 and a third electrode 130 as measurement electrodes And measuring the liquid film thickness using the apparatus.

The power application unit 300 may be installed on the first electrode 110 of the flexible printed circuit board 100 and the power application unit 300 may be mounted on the flexible printed circuit board 100. [ (S200) is performed.

Thereafter, the first current value I1 and the second current value I2, which flow from the first electrode 110 and are transmitted to the second electrode 120 and the third electrode 130 via the fluid of the liquid film 10, respectively, (S300) is performed. Finally, a step S500 of calculating the thickness of the liquid film 10 based on the first current value I1 and the second current value I2 is performed.

Meanwhile, in step S300 of detecting the first current value I1 and the second current value I2, it is preferable that the first current value I1 and the second current value I2 are simultaneously detected.

Between the step S300 of detecting the first current value I1 and the second current value I2 and the step S500 of calculating the thickness of the liquid film 10, the first current value I1 and the second current value I2 And amplifying the current value I2 (S400).

The step S500 of calculating the thickness of the liquid film 10 may further include a step S510 of calculating the ratio I2 / I1 of the first current value I1 and the second current value I2, (S520) of calculating the thickness of the liquid film 10 based on the correlation between the ratio I2 / I1 and the thickness of the liquid film.

The embodiments and the accompanying drawings described in the present specification are merely illustrative of some of the technical ideas included in the present invention. Therefore, it is to be understood that the embodiments disclosed herein are not intended to limit the scope of the present invention but to limit the scope of the present invention. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. It should be interpreted.

10: liquid film 100: flexible printed circuit board
110: first electrode 120: second electrode
130: third electrode 140: ground electrode
200: power applying unit 310: first amplifier
320: second amplifier 400:

Claims (15)

A flexible printed circuit board on which a first electrode as an applied electrode and a second electrode and a third electrode as measurement electrodes are formed; And
A power applying unit for applying power to the first electrode;
Lt; / RTI >
A liquid film thickness measuring device for calculating a thickness of the liquid film based on a first current value and a second current value which are respectively outputted from the first electrode and transmitted to the second electrode and the third electrode via the fluid of the liquid film, .
The method according to claim 1,
A first amplifier for amplifying the first current value; And
A second amplifier for amplifying the second current value;
Further comprising: a liquid film thickness measuring device for measuring the film thickness of the liquid film.
3. The method of claim 2,
Wherein the first amplifier and the second amplifier are lock in amplifiers.
3. The method of claim 2,
A calculator for calculating a thickness of the liquid film based on the first current value amplified through the first amplifier and the second current value amplified through the second amplifier;
Further comprising: a liquid film thickness measuring device for measuring the film thickness of the liquid film.
5. The method of claim 4,
And the calculating section calculates the thickness of the liquid film based on the ratio of the amplified first current value and the second current value.
The method according to claim 1,
Wherein the first electrode, the second electrode, and the third electrode are arranged in a line in a longitudinal direction of the flexible printed circuit board.
The method according to claim 6,
And ground electrodes are formed on both sides of the second electrode and the third electrode.
A flexible printed circuit board for measuring a liquid film thickness for measuring a thickness of a liquid film,
A first electrode for receiving power from the outside; And
A second electrode and a third electrode, respectively, when power is applied to the first electrode, the current is transmitted from the first electrode to the liquid through the liquid film;
/ RTI >
Wherein the thickness of the liquid film is calculated based on the first current value transmitted by the second electrode and the second current value transmitted by the third electrode.
9. The method of claim 8,
Wherein the thickness of the liquid film is calculated based on a ratio of the first current value and the second current value.
9. The method of claim 8,
Wherein the first electrode, the second electrode, and the third electrode are arranged in a line in a longitudinal direction of the flexible printed circuit board.
11. The method of claim 10,
A ground electrode formed on both sides of the second electrode and the third electrode;
Further comprising: a flexible printed circuit board for measuring a liquid film thickness.
1. A liquid film thickness measuring method using a liquid film thickness measuring apparatus comprising a flexible printed circuit board on which a first electrode as an applied electrode and a second electrode and a third electrode as measuring electrodes are formed,
Disposing the flexible printed circuit board in a liquid film;
The power application unit applies power to the first electrode;
Detecting a first current value and a second current value that flow from the first electrode and pass through the fluid of the liquid film to the second electrode and the third electrode, respectively; And
Calculating a thickness of the liquid film based on the first current value and the second current value;
And measuring the liquid film thickness.
13. The method of claim 12,
Amplifying the first current value and the second current value between the step of detecting the first current value and the second current value and the step of calculating the thickness of the liquid film,
Wherein the step of calculating the thickness of the liquid film is a step of calculating the thickness of the liquid film based on the amplified first current value and the second current value.
13. The method of claim 12, wherein calculating the thickness of the liquid film comprises:
Calculating a ratio of the first current value and the second current value; And
Calculating a thickness of the liquid film based on a correlation between the calculated ratio and the thickness of the liquid film;
And measuring the liquid film thickness.
13. The method of claim 12,
Wherein the first current value and the second current value are simultaneously detected.

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