KR20120101950A - Water level sensing system of apparatus - Google Patents

Abstract

PURPOSE: A system for sensing a level of a device is provided to sense a level by sensing a capacitance change of a level sensor according to the level of a solution containing in a container, thereby sensing the level. CONSTITUTION: A system(100) for sensing a level of a device comprises a level sensor(120). A container or a solution in the inside of the container is grounded and the level sensor has capacitance proximate to a highest level of the solution in the container larger than 0. A capacitance change of the level sensor is sensed according to the level of the solution in the inside of the container so that the level is sensed.

Description

WATER LEVEL SENSING SYSTEM OF APPARATUS}

The present invention relates to a water level sensing system of a device, and more particularly, to a water level sensing system of a device having a container for containing a liquid.

In general, water level sensors are used in devices that use water such as washing machines, dishwashers, water purifiers, humidifiers, bidets, and boilers.In the process of manufacturing semiconductors, devices that use liquids such as chemicals are used to control the height of liquids. Liquid level sensors are used, especially in storage tanks of such solutions.

Such a water level sensor can be measured in various ways, and in the field of environmental monitoring such as rainfall measurement and river height measurement, a sensor with high measurement reliability, a small size, and a low cost is required for a service combined with a sensor network. In addition, the need for easy and simple sensor tags is increasing.

Recently, home appliances that use water have been improved due to the improvement of power consumption and regulations on water consumption. Accordingly, efforts to lower power consumption and reduce water consumption have continued. To this end, more precise control of the water level is required. For example, a washing machine, for example, measured the water level by a mechanical pressure sensor, but a water level sensor capable of precise water level measurement is required to reduce water usage.

Meanwhile, conventional water level sensors have been commercialized in various forms, such as capacitive water level sensors for measuring liquid level using difference in dielectric constant between air and liquid, ultrasonic level sensors using ultrasonic generators and sensors, and water level changes using pressure sensors. And a water level sensor for measuring the pressure change in accordance with the present invention.

Among them, the capacitive water level sensor is in the spotlight in terms of precision and economy, and the measuring principle is as shown in FIG. 1. That is, the capacitive water level sensor 10 is composed of a double cylinder (see Fig. 1 (a)) of the inner electrode 11 and the outer electrode 12, between the inner electrode 11 and the outer electrode 12 The water level is sensed by detecting a change in capacitance (C _h ) between the electrodes according to the height (h) of the liquid (1). At this time, the change in capacitance (C _h ) is the relative dielectric constant (ε _r , about '1' and the relative dielectric constant (ε) of the liquid (1) of air between the electrodes in the capacitance (C), which can be represented by the following equation (1) _r , water can be detected quantitatively by the difference of about '80').

[Equation 1]

(C: capacitance, ε ₀ : dielectric constant, ε _r : relative dielectric constant, L: cylinder height, a: inner electrode radius, b: outer electrode radius)

In addition, when using a plate-type capacitive water level sensor (refer to FIG. 1 (b)), such as a film form, capacitance can be calculated by following formula (2).

[Formula 2]

(C: capacitance, ε ₀ : vacuum dielectric constant, ε _r : relative dielectric constant, S: electrode area, d: electrode spacing distance)

If the capacitive water level sensor is used in a device in which a container containing liquid such as a washing machine or a dishwasher may be a metallic material, there is a problem. That is, in the case of the apparatus provided with the container which can contain a liquid, since there is a danger of an electric shock in a user's operation, the capacitance measurement object is generally grounded. However, in this case, since the liquid contained in the container is regarded as ground rather than dielectric, the capacitive water level sensor using the relative dielectric constant difference between air and liquid becomes impossible to measure the capacitance itself.

Accordingly, there is a need for a new level sensing system that can be applied to the capacitive level sensor even when the capacitance measurement object is grounded.

Accordingly, the present invention has been made to solve the above problems, and to provide a water level sensing system of the device that the capacitive water level sensor can be applied even when the capacitance measurement object is grounded.

In addition, the present invention is to provide a water level sensing system of the device that can increase the measurement reliability.

In addition, the present invention is to provide a water level sensing system of a device that is easy to install and economical.

According to an aspect of the present invention,

(1) A water level sensing system of a device having a container capable of containing a liquid, wherein the container or the liquid inside the container is grounded, and the capacitance immediately before the highest level of liquid submerged in the container has a value greater than zero. It is provided with a water level sensor having a water level sensing system of the device, characterized in that for sensing the change in the capacitance value of the water level sensor according to the level of the liquid submerged in the container.

(2) In the above (1), the water level sensor has a predetermined length in the first direction, and a plurality of protrusions and a plurality of grooves are alternately arranged on at least one surface of the second direction crossing the first direction. And a first electrode and a second electrode arranged in parallel with each other, wherein the protrusions of the first electrode correspond to the grooves of the second electrode, and the protrusions of the second electrode in the grooves of the first electrode. A capacitance sensor in which the first electrode and the second electrode are disposed to be spaced apart at a predetermined interval to correspond to each other; And a signal processor disposed at upper ends of the first electrode and the second electrode to detect a water level through a sensing signal generated by the capacitive sensor to generate a detection signal. To provide.

(3) The method according to (2), wherein the water level sensor comprises: an antenna for transmitting a detection signal of the signal processing unit to the outside or supplying power to the signal processing unit and the capacitive sensor; And it provides a water level sensing system of the device, characterized in that the wireless structure having a; solar cell or battery for power supply.

(4) The method according to (2), wherein the water level sensor comprises: a connection line for transmitting a detection signal of the signal processing unit to the outside; It provides a water level sensing system of the device characterized in that it is streamlined; and a connecting line for power supply.

(5) In the above (2), the water level sensor, wherein the capacitance sensor is formed between the first insulating film and the second insulating film, the adhesive film is formed on the back of the first insulating film, the container It provides a water level sensing system of the device, characterized in that attached vertically to the inner surface.

(6) The water level sensing system according to (5) above, further comprising a shield electrode formed between the water level sensor and the first insulating film.

According to the present invention, when the container or the liquid inside the container is grounded, by providing a water level sensor having a value of the capacitance immediately before the highest level of the liquid submerged in the container, the value according to the height of the liquid contained in the container It is possible to provide a water level sensing system of a device capable of sensing a level of water by sensing a change in capacitance of a sensor.

In addition, it is possible to provide a water level sensing system having a relatively high sensitivity of the sensor, a shield electrode, and excellent measurement reliability, and a low material cost, and economical by using a film such as plastic and an adhesive film, without designing a special mechanism for the structure. It is possible to provide a water level sensing system that can be easily mounted.

1 is an explanatory diagram showing a measuring principle of a capacitive water level sensor;
2 is a schematic diagram illustrating a water level sensing system of a device according to an embodiment of the present invention;
3 and 4 is a schematic circuit diagram for explaining the capacitance change of the water level sensing system according to an embodiment of the present invention,
5 to 7 is a layout view showing an example of the water level sensor used in the present invention,
8 is a sectional view showing a water level sensor according to an embodiment of the present invention;
9 and 10 are schematic circuit diagrams for explaining the capacitance change of the water level sensing system according to another embodiment of the present invention.

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

In the drawings, the same or equivalent reference numerals are given to the same or similar reference numerals, and the direction will be described with reference to the drawings. The first direction means the longitudinal direction of the water level sensor, and the second direction indicates the horizontal direction of the water level sensor. (Short) direction means. In addition, throughout the specification, when a part is said to "include" a certain component, it means that unless otherwise stated, it may further include other components other than the other components.

2 is a schematic diagram illustrating a water level sensing system of a device according to an embodiment of the present invention.

Referring to FIG. 2, the water level sensing system 100 of the device according to the present invention is a water level sensing system 100 of a device having a container 110 capable of containing liquid, and the container 110 or the container. The liquid l in the interior 110 is grounded 111, and the water level sensor 120 having a value of a capacitance just before the highest level of the liquid l submerged in the container 110 has a value greater than zero (FIG. 2C). In the case of using only air as the dielectric (120 ', see FIG. 2 (b)), or even in the presence of the liquid (l) in the interior, the liquid (l) does not exist therein. A level sensor 120 having a large capacitance value (see FIG. 2 (c)), the change in the capacitance value of the level sensor 120 according to the level of the liquid l submerged in the vessel 110 Sensing the water level is characterized by.

The water level sensing system 100 according to the present invention, when the water level sensing in the device using a liquid (1), such as water, to be performed by the capacitance (C) difference, the risk of electric shock during the user's operation In order to prevent the change in the capacitance (C) according to the water level even when the ground 111 to the container 110 that can contain the liquid (1).

That is, in general, the capacitive water level sensor detects the water level by the capacitance difference using only the dielectric between the electrodes using air and liquid, but according to the present invention, the capacitance of the water level sensor is sufficiently large, that is, the container Designed to have a capacitance value greater than zero until just before the liquid level (l) of the highest level within the (110) inside, the value of the capacitance (C) decreases as the liquid level increases as the liquid level (l) increases. The water level can be detected by detecting a change in the capacitance value. In this case, when the container 110 of the device 110 or the liquid l inside the container 110 is not grounded 111 or when the ground 111 is weakly treated, the liquid 1 may be arbitrarily grounded 111. By adding an electrode connected to), a change in capacitance C can be detected by the same principle.

Here, the dielectric 121, having a larger dielectric constant than air (ε _r), as shown in the capacitance (C) It is large enough to design in advance the value, for example, FIG. 2 (c) of said level sensor It may be possible by filling between the electrodes 122a and 122b constituting the water level sensor 120, and forming protrusions on the electrodes 122a and 122b to increase the electrode area or the electrodes 122a and 122b. This may be possible by adjusting the spacing between.

3 and 4 are schematic circuit diagrams for explaining the change in capacitance of the water level sensing system according to an embodiment of the present invention. Here, Figure 3 (a) is schematically shown for convenience of understanding.

3 and 4, the water level sensing system 100 according to the present invention as described above, even if there is no liquid (1) so that the water level sensor 120 has a capacitance (C) value of a predetermined size (See FIG. 3 (b).) This constant capacitance C value is a relative dielectric constant of air between the water level sensor electrodes 122a and 122b as shown in FIG. 2 (c), for example. distance between ε _r) than by keeping it filled with the dielectric 121 having a large relative dielectric constant (ε _r), or by forming the projection on the electrode (122) enlarging the electrode area of the electrode (122a, 122b) As shown in FIG. 4, a plurality of capacitances can be expressed equivalently to a circuit connected in parallel with respect to the first direction as shown in FIG. 4. At this time, the electrode 122 surrounded by the liquid 1 is coupled to the ground 111 and the capacitance due to the increase in the water level, and the capacitance C of this portion is close to '0', where the water level is increased. By using the principle that the capacitance C is reduced by the height h corresponding to the total capacitance C, the water level sensing is possible. Therefore, in the case of the capacitive water level sensor, the liquid 110 in the container 110 or the inside of the container 110 is grounded 111, so that the liquid l, which is the capacitance C measurement object, is grounded 111 and is electrostatically charged. It is possible to overcome the problem that the capacity (C) measurement is impossible. On the other hand, when the water level reaches the maximum height of the water level sensor, the capacitance value is close to '0' as in the equivalent circuit shown in FIG.

In more detail, the principle C value of the water level sensor can be calculated by Equation 2 when there is no liquid l in the container 110. Here, the relative dielectric constant ε _r of air is known to have a value of about '1', and the water level sensor 120 according to the present invention is designed to have a sufficiently large capacitance C in advance. This may be represented by an equivalent circuit in which a plurality of capacitances are connected in parallel as shown in FIG. 4.

In addition, even when the liquid 1 is present, the capacitance value C can be calculated by equation (2). The relative dielectric constant epsilon _r of the liquid 1 is known as about '80', for example, with water. However, the liquid l is connected to the ground 111 and does not have a meaning of its relative dielectric constant ε _r at the value of the total capacitance C, and some capacitances of the plurality of capacitances are close to '0', thereby causing a total power failure. It will serve to reduce the value of the capacity (C).

Therefore, as the level of the liquid 1 increases, the capacitance value C through the water level sensor 120 decreases, and the value of the capacitance C obtained in inverse proportion to the level of the liquid 1 is read. Through the processing unit 123 it is possible to determine the level of the liquid (1).

5 to 7 are layout views showing an example of the water level sensor used in the present invention. 5 to 7 illustrate the position or arrangement of the electrode 122, the signal processor 123, and the solar cell 126 of the water level sensor 120 for convenience. The overall structure is not shown, and the second insulating film 127 is shown in the completed structure without being shown.

As shown in FIG. 5, the water level sensor 120 according to the exemplary embodiment of the present invention may include a first electrode 122a and a second electrode 122b constituting a capacitive sensor on the first insulating film 124. ), A signal processor 123, an antenna 125, and a solar cell 126. In addition, a battery (battery) 128 may be disposed.

The first electrode 122a and the second electrode 122b have a predetermined length in a first direction, and a plurality of protrusions and a plurality of grooves are alternately arranged on at least one surface of the second direction crossing the first direction. The structure may be arranged parallel to each other. That is, the protrusions of the first electrode 122a correspond to the grooves of the second electrode 122b, and the protrusions of the second electrode 122b correspond to the grooves of the first electrode 122a to engage with each other. The first electrode 122a and the second electrode 122b may be disposed to be spaced apart at regular intervals.

For example, the first electrode 122a and the second electrode 122b may be formed in a plurality of teeth (protrusions) of a quadrangular (or polygonal) having a shape protruding in a second direction at a predetermined interval. The first electrode may be disposed to maintain a predetermined distance in the first direction, and the teeth of the second electrode 122b and the teeth of the first electrode 122a may be arranged to engage each other. 122a and the second electrode 122b may be disposed to be spaced apart from each other by a predetermined interval.

In addition, one end of the first electrode 122a and the second electrode 122b may be electrically connected to the signal processor 123 through an electrode pattern. The signal processor 123 is disposed on the upper ends of the first electrode 122a and the second electrode 122b, and constitutes the capacitance sensor. The first electrode 122a and the second electrode 122b constitute the capacitive sensor. The water level is detected by the sensing signal generated by the to generate a detection signal.

The arrangement of the signal processor 123 may be arranged in a straight line as shown in FIG. 5, may have a circular arrangement, and may have various arrangements such as 'a' or 'b'. This may be variously configured according to the shape, size, or arrangement of chips or elements constituting the signal processor 123.

In addition, an antenna 125 may be disposed at an upper end of the signal processor 123, and a battery (battery) 128 may be disposed at a side surface of the antenna 125, and the antenna 125 and the battery may be disposed on the antenna 125. The solar cell 126 may be disposed at the upper end of the 128.

The antenna 125 supplies power to the signal processor 123, the first electrode 122a, and the second electrode 122b like a general RF tag, or externally detects a detection signal of the signal processor 123. Is to be sent to. The shape of the antenna 125 may have a hollow square shape as shown in FIG. 5, or may be arranged in various shapes such as a rectangle, a circle, and a straight line.

On the other hand, Figure 5 shows the water level sensor 120 when the solar cell 126 is provided, the water level sensor 120 according to the present invention is a wireless type (wireless type) or without the solar cell 126 It can be manufactured in a wire type.

The case of the wireless type having the solar cell 126 has been described with reference to FIG. 5, and the case of the wireless level sensor 220 without the solar cell 126 is shown in FIG. 6. The first electrode 222a and the second electrode 222b constituting the sensor, the signal processor 223, an antenna 225 and a battery (battery) 228 for communication, the arrangement structure is shown in FIG. Same or similar to that described above.

In another example, the wireless water level sensor 220 without the solar cell 126 may be a passive type water level sensor 220 without the battery 228.

In addition, in the case of the streamlined water level sensor 320 having no solar cell 126, as shown in FIG. 7, the first electrode 322a and the second electrode 322b constituting the capacitive sensor and The signal processing unit 323 may be provided, and the signal lines of the signal processing unit 323 may be connected to the outside or may be provided with connection lines 329 for power supply.

8 is a cross-sectional view showing a water level sensor according to an embodiment of the present invention. 8 and 2, in the water level sensor 120, a first electrode 122a and a second electrode 122b are formed between the first insulating film 124 and the second insulating film 127. An adhesive film 129-1 may be formed on the rear surface of the first insulating film 124 to be vertically attached to one surface of the container 110.

The first insulating film 124 and the second insulating film 127 are coated to insulate the liquid 1 from the first electrode 122a and the second electrode 122b and are made of polyethylene terephthalate (PET) or It may be a polyimide (PI).

In addition, the adhesive film 129-1 may form an adhesive material film in the form of a double-sided adhesive, thereby bonding or fixing the water level sensor 120 to a specific portion such as one surface of the container 110.

9 and 10 are schematic circuit diagrams for explaining the change in capacitance of the water level sensing system according to another embodiment of the present invention. Here, Figure 9 (a) is schematically shown for convenience of understanding.

9, 10, and 8, the water level sensing system 100 according to another embodiment of the present invention includes the electrodes (the first electrode 122a and the second electrode 122b) and the first insulating film. A shield electrode 129-2 may be further formed between the 124. The shield electrode 129-2 has a surface wider than that of the first electrode 122a and the second electrode 122b, so that the capacitance C can be more stably measured.

As described above with reference to FIG. 3, the water level sensing system 100 having the water level sensor 120 having the shield electrode 129-2 formed therein is sufficiently large even when there is no liquid l. It is designed to have a constant value of capacitance C. (See Fig. 9 (b).) The constant value of capacitance C is, for example, an analogy of air between the water level sensor electrodes 122. the distance between the dielectric constant (ε _r) than by keeping it filled with a dielectric having a high relative dielectric constant (ε _r), or by forming the projection on the electrode (122) enlarging the electrode area of the electrode (122a, 122b) By adjusting, the plurality of capacitances can be expressed equivalently to a circuit connected in parallel with respect to the first direction. At this time, the electrode 122 surrounded by the liquid 1 is coupled to the ground 111 and the capacitance due to the increase in the water level, and the capacitance C of this portion is close to '0', where the water level is increased. By using the principle that the capacitance C is reduced by the height h corresponding to the total capacitance C, the water level sensing is possible. Therefore, in the case of the capacitive water level sensor, the liquid 110 in the container 110 or the inside of the container 110 is grounded 111, so that the liquid l, which is the capacitance C measurement object, is grounded 111 and is electrostatically charged. It is possible to overcome the problem that the capacity (C) measurement is impossible. On the other hand, when the water level reaches the maximum height of the water level sensor, the capacitance value is close to '0' as in the equivalent circuit shown in FIG.

In addition, as described in FIG. 4, when the liquid 1 does not exist in the container 110, the capacitance value C of the water level sensor may be calculated by Equation 2. Here, the relative dielectric constant ε _r of air is known to have a value of about '1', and the water level sensor 120 according to the present invention has a sufficiently large capacitance. This may be equivalent to that of a plurality of capacitances connected in parallel as shown in FIG. 10.

The foregoing is a description of specific embodiments of the present invention. The above embodiments according to the present invention are not to be understood as limiting the scope of the present invention or the matter disclosed for the purpose of description, and those skilled in the art without departing from the spirit of the present invention various changes and modifications It should be understood that this is possible. It is therefore to be understood that all such modifications and alterations are intended to fall within the scope of the invention as disclosed in the following claims or their equivalents.

100: water level sensing system 110: container
111: ground 120, 220, 320: water level sensor
121: dielectric 122a, 222a, 322a: first electrode
122b, 222b, and 322b: second electrodes 123, 223, and 323: signal processor
124: first insulating film 125, 225: antenna
126: solar cell 127: second insulating film
128, 228: battery (battery) 129-1: adhesive film
129-2: shield electrode 329: connecting line
l: liquid

Claims (6)

A water level sensing system of a device having a container for containing liquid,
The container or the liquid inside the container is grounded, and is provided with a water level sensor whose capacitance immediately before the highest level of the liquid immersed in the container is greater than zero, so that the liquid is submerged in accordance with the level of the liquid immersed in the container. The water level sensing system of the device, characterized in that for sensing the change in the capacitance value of the water level sensor. The method of claim 1,
The water level sensor,
The first electrode and the second electrode having a predetermined length in the first direction and arranged in parallel with each other in a structure in which a plurality of protrusions and a plurality of grooves are alternately arranged on at least one surface of the second direction crossing the first direction. Wherein the projection of the first electrode corresponds to the groove of the second electrode, the projection of the second electrode corresponding to the groove of the first electrode is spaced apart at a predetermined interval in the form of engagement with each other the first electrode And a capacitance sensor on which the second electrode is disposed; And
A signal processor disposed at upper ends of the first electrode and the second electrode to detect a water level through a sensing signal generated by the capacitance sensor to generate a detection signal;
Water level sensing system of the device, characterized in that provided with. The method of claim 2,
The water level sensor,
An antenna for transmitting the detection signal of the signal processor to the outside or supplying power to the signal processor and the capacitive sensor; And
Solar cells or batteries for power supply;
Water level sensing system of the device, characterized in that the wireless structure having a. The method of claim 2,
The water level sensor,
A connection line for transmitting the detection signal of the signal processor to the outside; And
Connecting line for power supply;
Water level sensing system of the device, characterized in that the streamlined. The method of claim 2,
The water level sensor is characterized in that the capacitive sensor is formed between the first insulating film and the second insulating film, the adhesive film is formed on the back of the first insulating film, it is attached vertically to one surface inside the container Level sensing system of the device. The method of claim 5,
And a shield electrode is further formed between the water level sensor and the first insulating film.

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