KR20180022048A - Highly sensitive pressure sensor and input device using the highly sensitive pressure sensor - Google Patents

Abstract

The present invention provides an input device using a high sensitivity pressure sensor composed to be easily manufactured based on commonly used low-cost materials. According to an embodiment of the present invention, the high sensitivity pressure sensor comprises: a lower substrate having one surface on which a first electrode having a surface roughness is formed; an upper substrate having one surface on which a second electrode having a surface roughness is formed; and a dielectric material laminated between the lower substrate and the upper substrate so as to be located between the first electrode and the second electrode.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a high-sensitivity pressure sensor and an input device using the same,

The present invention relates to a pressure sensor and an input device, and more particularly, to a high-sensitivity pressure sensor capable of realizing high-sensitivity sensing with a simple configuration and an input device using the same.

With the digital Internet (IoT), which connects objects and objects digitally, there is a constantly growing demand for the development of various sensor technologies. In particular, the touch / pressure sensor is a sensor that is used in a wide range of everyday objects such as flexible / wearable devices, robots, and health care, as well as spaces close to life in homes, factories, offices and automobiles. This was a very high disadvantage. This is due to the fact that the prices of materials mainly used for electrodes such as gold, silver, and gold-based nanowires, indium tin oxide (ITO), and carbon nanotubes (CNT) are relatively high. In addition, in order to increase the sensitivity of a conventional parallel-plate capacitor structure, studies for forming a micro-structure by modifying the structure of a dielectric layer have been actively conducted. This is because a complicated process such as photo-lithography, etching, and the like must be carried out, and thus the process cost is considerably high.

For this reason, most of the high-sensitivity pressure sensors remain in the research stage and do not lead to commercialization. Therefore, it is required to develop a new high performance pressure sensor that can minimize the material and process cost by overcoming the limitation of the pressure sensor manufactured using the existing expensive material and the silicon process.

Korean Patent Publication No. 10-2012-0098749

According to various embodiments of the present invention, it is possible to provide an input device using a high-sensitivity pressure sensor that is configured to be easily manufacturable based on commonly-used low-cost materials.

According to various embodiments of the present invention, an input device using a high-sensitivity pressure sensor for inputting various keys based on a pressure using a high-sensitivity pressure sensor can be provided.

According to an embodiment of the present invention, there is provided a plasma display panel comprising: a lower substrate on which a first electrode having a surface roughness is formed; An upper substrate on which a second electrode having a surface roughness is formed; And a dielectric material laminated between the lower substrate and the upper substrate so as to be disposed between the first electrode and the second electrode.

According to various embodiments, the dielectric material may be formed to surround the surface of the first electrode or the irregular surface of the second electrode due to the surface roughness of the first electrode or the second electrode.

According to various embodiments, the dielectric material includes an elastomer, wherein the weight percentage of the elastomer in the dielectric material can be determined according to the surface roughness and the thickness of the dielectric material formed.

According to various embodiments, the lower substrate or the upper substrate may be a flexible or stretchable material.

According to various embodiments, the surface roughness of the first electrode or the second electrode may be represented by the surface roughness of the lower substrate or the upper substrate.

According to various embodiments, the surface roughness of the first electrode or the second electrode may be generated at the time of electrode formation or may be generated by processing after electrode formation.

According to various embodiments, the dielectric material comprises: a lower dielectric layer provided on the first electrode; And an upper dielectric layer provided on the second electrode.

According to various embodiments, the bottom dielectric layer is in intimate contact with the first electrode such that the surface roughness of the first electrode appears in the bottom dielectric layer, and the top dielectric layer is in close contact with the second electrode, Roughness may appear in the upper dielectric layer.

According to various embodiments, an air layer may be formed over a portion of the area between the lower dielectric layer and the upper dielectric layer.

According to various embodiments, when pressure is applied to at least one of the lower substrate and the upper substrate, at least some of the surfaces of the lower dielectric layer and the upper dielectric layer may engage and form an intersecting structure.

According to various embodiments, when pressure is applied to at least one of the lower substrate and the upper substrate, the air layer formed between the lower dielectric layer and the upper dielectric layer may be removed, or a smaller air layer may be formed It can be divided.

According to an embodiment of the present invention, there is provided a pressure sensor comprising: at least one high sensitivity pressure sensor as described above; And a controller for processing a key input according to a signal output from the pressure sensor with respect to the applied pressure when a pressure is applied through the pressure sensor.

According to various embodiments, the input device using the high-sensitivity pressure sensor may further include a pressure applying unit applying pressure to at least one of the lower substrate and the upper substrate of the pressure sensor.

According to various embodiments, the control unit may process the first signal when the applied pressure is less than the predetermined first reference pressure, and process the second signal if the applied pressure is equal to or greater than the first reference pressure .

According to various embodiments, when the applied pressure is less than a predetermined second reference pressure, the control unit may process the input to ignore the input.

According to various embodiments, the controller may process different inputs according to the intensity, time, or frequency of the applied pressure.

According to various embodiments, the control unit may include: a main control unit for outputting an excitation signal input to the pressure sensor and inputting the signal output from the pressure sensor; A demultiplexer for distributing the excitation signal to the at least one pressure sensor; And a multiplexer for converting a parallel signal output from the at least one pressure sensor into a serial signal.

According to various embodiments, the control unit may classify the signals received through the main control unit for each of the at least one high-sensitivity pressure sensor into a plurality of levels and divide the signals into a plurality of levels, Can be specified.

According to various embodiments, the control unit determines a key designated for the level of the signal based on the signal received via the main control unit and the high-sensitivity pressure sensor outputting the signal, and inputs the determined key To the multiplexer.

According to various embodiments, the signal may be a capacitance value corresponding to a pressure applied to each of the at least one high-sensitivity pressure sensor.

Further, the input device using the high-sensitivity pressure sensor according to the embodiment of the present invention can be applied to various types of devices such as a paper, graphite or the like which can produce materials commonly used in daily life, for example, It is possible to provide an input device at an extremely low cost in accordance with the reduction of material and manufacturing process cost while realizing a high sensitivity characteristic.

Further, since the flexible printed circuit board is manufactured using the flexible printed circuit board, it is possible to provide an input device that can be bent, thereby providing an input device that is easy to carry.

As described above, by improving the sensing sensitivity of the pressure sensor without significantly changing the process of the pressure sensor, an input device for dividing the pressure measured from the pressure sensor into a plurality of levels and processing various inputs with one pressure sensor .

1 is a block diagram of an input device using a high-sensitivity pressure sensor according to an embodiment of the present invention.
2 is a perspective view of a pressure sensor in an input device using a high-sensitivity pressure sensor according to an embodiment of the present invention.
3 is a view illustrating a process of manufacturing a pressure sensor applied to an input device using a high-sensitivity pressure sensor according to an embodiment of the present invention.
4 is a view showing contact angles of the elastic polymer before dilution and the elastic polymer after dilution.
Figure 5 is a diagram showing the contact angle of water and diluted elastomer dropped on several substrates.
6 is a cross-sectional view of a high-sensitivity pressure sensor in which the roughness formed in the electrode and dielectric expression is expressed in an input device using a high-sensitivity pressure sensor according to an embodiment of the present invention.
7 and 8 are respectively a confocal microscope image and roughness analysis data of the electrode surface of the pressure sensor applied to the input device using the high sensitivity pressure sensor according to the embodiment of the present invention and the surface roughness coated with the elastomer, FIG.
9 is a view illustrating a process for forming a curl on a substrate in an input device using a high-sensitivity pressure sensor according to an embodiment of the present invention.
10 is a graph showing changes in the dielectric surface before and after pressure is applied in an input device using a high-sensitivity pressure sensor according to an embodiment of the present invention.
11 is a graph showing an input device using a high-sensitivity pressure sensor according to an embodiment of the present invention, and a graph of a capacitance change according to an applied pressure.
FIG. 12 is a diagram showing a sensitivity of a 3 × 3 pressure sensor array including an input device using a high-sensitivity pressure sensor according to an embodiment of the present invention, and a case in which a weight having a different weight is placed on two points.
FIG. 13 is a diagram illustrating a capacitance change with respect to a pressure applied to a pressure sensor in an input device using a high-sensitivity pressure sensor according to an embodiment of the present invention.
FIG. 14 is a graph illustrating a sensing speed and a recovery speed according to a pressure applied to a pressure sensor in an input device using a high-sensitivity pressure sensor according to an embodiment of the present invention.
15 is a graph of a nanoindentation analysis of a flexible substrate constituting an input device using a high-sensitivity pressure sensor according to an embodiment of the present invention.
16 is a diagram modeling reversible elastic characteristics of a pressure sensor in an input device using a high-sensitivity pressure sensor according to an embodiment of the present invention.
17 is a graph illustrating hysteresis and stability of a pressure sensor in an input device using a high-sensitivity pressure sensor according to an embodiment of the present invention.
FIG. 18 is a diagram illustrating an input device using a high-sensitivity pressure sensor according to an embodiment of the present invention, and an upper case and a lower case according to a pressure applied thereto.

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

The embodiments of the present invention are capable of various changes and various embodiments, and specific embodiments are illustrated in the drawings and the detailed description is described with reference to the drawings. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all changes and / or equivalents and alternatives falling within the spirit and scope of the invention. In the description of the drawings, like reference numerals may be used for similar elements.

It should be noted that the terms such as " comprising " or " may include " may be used among the various embodiments of the present invention to indicate the presence of a corresponding function, operation or component, Not limited.

Also, in various embodiments of the invention, the terms "comprise" or "having" are intended to specify the presence of stated features, integers, steps, operations, components, parts or combinations thereof, But do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

In various embodiments of the present invention, the term "or" or the like includes any and all combinations of words listed together. For example, 'A or B' may comprise A, include B, or both A and B.

In various embodiments of the present invention, expressions such as 'first', 'second', 'first' or 'second' may modify various elements of the present invention, but the order and / . In addition, the representations may be used to distinguish one component from another.

In the various embodiments of the present invention, when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, It is to be understood that components may also be present. On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

In various embodiments of the invention, the description may not exactly match the information presented, such as quoted properties, variables, or values, depending on the expressions "substantially," "for example, And should not limit embodiments of the invention according to various embodiments of the present invention, such as tolerances, measurement errors, limitations of measurement accuracy, and other factors commonly known.

The terms used in various embodiments of the present invention are used to illustrate specific embodiments and are not intended to limit the invention. The singular < RTI ID = 0.0 > expression < / RTI > may include a plurality of representations unless the context clearly dictates otherwise.

Also, all terms used herein, including technical or scientific terms, should be construed as having the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains, Unless expressly defined, it should not be construed or interpreted in an ideal or overly formal sense.

Hereinafter, various embodiments according to the present invention will be described in detail with reference to the accompanying drawings, wherein like reference numerals refer to the same or similar elements, and redundant explanations thereof may be omitted.

An input device using a high sensitivity pressure sensor according to an embodiment of the present invention includes a plurality of pressure sensors 100 and a controller 200 for applying an excitation signal to the pressure sensor and controlling the output of the pressure sensor .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an input device 10 using a high-sensitivity pressure sensor 100 and a high-sensitivity pressure sensor 100 according to various embodiments of the present invention will be described with reference to FIGS. 1 to 18.

1, an input device (hereinafter, input device 10) using a high-sensitivity pressure sensor according to an embodiment of the present invention includes a plurality of high-sensitivity pressure sensors (hereinafter referred to as a pressure sensor 100) And a controller 200 for applying an excitation signal to the sensor 100 and controlling the output of the pressure sensor 100. [

The high-sensitivity pressure sensor 100 according to an embodiment of the present invention partially applies the structure of a parallel-plate capacitor and basically applies the high-sensitivity pressure sensor 100 to the high-sensitivity pressure sensor 100 based on the variation of the capacitance of the parallel-plate capacitor. Detects the pressure drop.

The structure of the pressure sensor 100 is formed of two substrates, for example, a lower substrate 110 and an upper substrate 120 as shown in FIG. 2, and each of the lower substrate 110 and the upper substrate 120 Electrodes (111, 121) and a dielectric (or dielectric layer (130)) are formed on one surface of the substrate. Here, the dielectric formed on the lower substrate 110 may be represented by a lower dielectric (or lower dielectric), and the dielectric formed on the upper substrate 120 may be represented by an upper dielectric (or upper dielectric).

Referring to FIG. 3, a method of manufacturing the pressure sensor 100 according to an exemplary embodiment of the present invention includes forming a first electrode 111 on a flexible substrate 110-1, The dielectric 130 may be formed on the flexible substrate 110-2 on which the first electrode 111 is formed to provide the lower substrate 110-3 having roughness on the dielectric.

Here, the flexible substrate is a substrate having flexible and / or stretchable characteristics which are bent based on a force applied from the outside of the substrate, a force generated from the inside of the substrate and / or a force generated on the surface of the substrate .

Similarly, the upper substrate 120 is also produced by the same or similar method as the manufacturing method of the lower substrate 110-3, and the lower substrate 110 and the upper substrate 120 are arranged so that the dielectrics formed on the respective substrates face each other The pressure sensor 100 can be constructed. Hereinafter, the lower substrate 110 and the upper substrate 120 may be referred to as a substrate in which the electrodes 111 and 121 and the dielectric 130 are formed, unless otherwise described.

2, the first electrode 111 and the second electrode 121 formed on the lower substrate 110 and the upper substrate 120 are connected to the outside of the substrates 110 and 120 through connecting lines 151 and 152, respectively, And the electrodes 111 and 121 may be connected to the connection lines 151 and 152 using the connection terminals 141 and 142. [

As described above, the high-sensitivity pressure sensor according to an embodiment of the present invention includes a first electrode 111, a second electrode 121, and a dielectric (first electrode) 121 disposed between the first electrode 111 and the second electrode 121 (Parallel plate capacitor) composed of a parallel plate capacitor 130 and a pressure applied from the outside on the basis of a change amount of the capacitance of the parallel plate capacitor. Here, the applied pressure may be expressed by force and / or weight.

The capacitance of such a capacitor is defined by the following equation (1).

(1)

(One)

(Where C is the capacitance, 竜 ₀ Is the dielectric constant (or permittivity) of the vacuum, ε _r Where A is the area between the electrodes, and d is the distance between the electrodes)

Referring to Equation (1), when a pressure 300 is applied through a pressure applying unit as shown in FIG. 10 in the case of a parallel plate capacitor, a change in capacitance occurs when the distance between the capacitors and the substrate changes. For example, a parallel-plate capacitor basically increases its capacitance because its thickness becomes thinner when a pressure is applied through a pressure applying section.

The pressure applying portion may be formed on one surface (for example, the lower surface of the lower substrate 110) on which the electrode 111 of the lower substrate 110 is not formed or the electrode 121 of the upper substrate 120 is not formed Or at least a part of the one surface (e.g., the lower surface of the upper substrate 120).

However, in the case of a general pressure sensor, since the distance d between the electrodes, which varies with the applied pressure, is insignificant due to the high elastic resistance of the dielectric, the substantial change in the capacitance is not large. Therefore, in order to control not only the distance d between the electrodes but also the effective dielectric constant and / or the area A between the electrodes, the roughness and curl of the pressure sensor 100 Can be applied.

In this case, in the case of roughness, an unintended roughness formed by a rubbing (or drawing) method on the substrates 110 and 120 may be used. Here, the roughness is for indicating the roughness (R _c , mean height of the profile elements) of the surfaces of the electrodes 111 and 121 formed on the substrates 110 and 120, but is not limited thereto, The roughness of the surface of the dielectric 130 formed on the substrate 110, the upper substrate 120 and / or the electrodes 111 and 121 can be shown.

The surfaces of the electrodes 111 and 121 formed on the substrates 110 and 120 may be formed to have a roughness of a specified size or more, for example, a roughness of 6 m or more, and preferably a roughness of 7 m or more.

Electrodes 111 and 121 formed on the substrates 110 and 120 may be made of an electrically conductive material such as graphite and may be formed on the substrates 110 and 120 by drawing or writing. have.

For example, the electrodes 111 and 121 can be formed by forming a material (e.g., graphite) for forming an electrode into a rod shape (e.g., pencil) and rubbing it on the substrates 110 and 120. At this time, the roughness and / or thickness of the electrodes 111 and 121 formed on the substrates 110 and 120 can be determined by adjusting the strength of rubbing the rods for forming the electrodes on the substrates 110 and 120.

The method of forming electrodes on the substrates 110 and 120 has been described as a drawing or a lighting method. However, the present invention is not limited to this. For example, printing, printing, spin coating, spraying ) May be formed in various ways.

The electrodes 111 and 121 are formed of graphite. However, the present invention is not limited to this, and may be a metal such as a silver nanoparticle, a carbon black, a carbon nanotube various conductive materials such as carbon allotrope such as carbon nanotube (CNT) and organic materials such as high functional conductive polymer (PEDOT-PSS) may be used.

In order to form the electrodes 111 and 121, the substrates 110 and 120 may also be made of a material having roughness, for example, paper, plastic, or the like. When the paper is used as a substrate, a surface-coated paper can be used so as not to get wet in the dielectric coating process. The surface of the substrate may be processed to form artificially roughness.

A dielectric 130 is formed on the electrodes 111 and 121 formed on the substrates 110 and 120 and the substrates 110 and 120. At this time, the surface roughness of the electrodes 111 and 121 is reflected on the basis of the thickness of the dielectric 130 formed, and thus the microstructure (or micro-structure) due to the roughness of the surfaces of the electrodes 111 and 121 Is formed on the surface of the dielectric (130).

In this case, the dielectrics formed on the electrodes 111 and 121 are elastomers, and general elastomers have a high viscosity of several micrometers even when the spin coating RPM is increased due to high viscosity, and curing there is a problem in utilizing the roughness of the electrode formed on the flexible substrate because self-leveling phenomenon occurs at the time of curing.

Therefore, there is a need to provide a method for forming a dielectric below a specified thickness on the substrate 110, 120 using an elastomer and for reproducing the roughness of the electrodes 111, 121 on the dielectric surface.

According to one embodiment, the dielectric 130 formed on the electrodes 111 and 121 may be formed by mixing one dielectric material or two or more dielectric materials. For example, the dielectric 130 according to one embodiment of the present invention may be used by mixing an elastomer with a variety of solvents, and it is required to optimize the thickness by utilizing the viscoelastic properties of the diluted elastomer .

For example, a solution having a very low viscosity, which is formed by thermodynamically spontaneous mixing of an elastomer and hydrocarbon, can be used as a material of the dielectric 130.

At this time, the thermodynamic spontaneous mixing phenomenon depends on the solubility parameter between the materials, and the relationship between the enthalpy change amount and the solubility indexing for the Gibbs free energy (Equation 2) and Equation 3 ] Can be used.

(2)

(2)

(Where Gm is the Gibbs free energy, DELTA Hm is the enthalpy change at the time of mixing, T is the absolute temperature, and DELTA Sm is the entropy variation at the time of mixing)

(3)

(3)

(Where? _E is the solubility coefficient of the elastomer,? _S is the solubility coefficient of the hydrocarbon)

As the solubility coefficient values between materials are similar to each other, the Gibbs free energy (ΔGm) tends to be mixed with each other. Therefore, generally, when this value is smaller than 0, the thermodynamic spontaneous reaction proceeds rapidly.

According to one embodiment of the present invention, the elastomer for forming the dielectric may be polydimethylsiloxane (PDMS), ecoflex, etc., and hydrocarbons may be hexane, heptane, ) May be used. In this case, the solubility coefficient of the elastomer and the hydrocarbon are respectively ^{7.4 and 7.3 cal 1/2 cm 3/} 2, therefore, it takes place a spontaneous mixing phenomenon because it creates a Gibbs free energy value to a value less than zero.

As described above, the solution made by spontaneous mixing phenomenon is greatly reduced in viscosity and can be easily grasped by comparing the contact angles of the elastomer before and after dilution (mixing) on the surfaces of the electrodes 111 and 121 as shown in FIG. 4 have.

In the case of elastomers diluted in hydrocarbon (after dilution) not only the viscosity is greatly reduced compared to the elastomer before dilution, but also the contact angle is very low due to the low surface tension of the hydrocarbon itself.

That is, as the weight percentage of the diluted elastomer is decreased, the contact angle at the surface according to the weight percentage of the dielectric 130 formed becomes lower, and thus, as the weight percentage is lowered as in the example shown in the following table, can do.

Table 1 below shows the formation thickness of the dielectric layer according to the weight percentage of the elastomer.

number Weight percentage (wt.%) Formation thickness of layer (μm) One 50 10.5 2 40 6.4 3 30 3.3 4 20 1.7 5 10 0.8 6 5 0.3

5, the contact angle is changed according to the hydrophilic / hydrophobic properties of the substrate. However, in the case of the hydrocarbon-diluted elastomer, as shown in the lower table of FIG. 5, It can be confirmed that the contact angle is very low regardless of the type.

The contact angle is further lowered during curing, which means that a very thin dielectric layer 130 can be formed. In the case of hydrocarbons diluted elastomers, the contact angle at the substrate is very low and eventually the contact angle approaches zero (full wetting) as time elapses, and thus the dielectric 130 formed is shown in Figures 6 and 8 As a result, the surface roughness of the electrodes 111 and 121 can be effectively reproduced.

That is, the surface of the dielectric 130 formed on the lower substrate 110 and the upper substrate 120 may be formed such that the roughness of the surfaces of the electrodes 111 and 121 formed on the substrates 110 and 120 is partially reflected .

For example, the roughness of the dielectric surface can be controlled by controlling the degree of dilution of the elastomer and the spin coating conditions. In this study, the mass percentage of the elastomer on an electrode having a roughness of 6 μm or more than 7 μm (eg, graphite) The roughness Rc of the surface of the dielectric layer 130 ranges from 0 to 30% by weight, preferably 30 to 50% by weight, preferably 35 to 45% by weight, more preferably 40% Micro] m, preferably about 0 to 4 [micro] m.

The weight percentage of the elastomer can be determined according to the surface roughness of the electrodes 111 and 121 to be formed and therefore the weight percentage of the elastomer can be appropriately selected depending on the material of the electrode, It should be included in the scope.

According to the above description, the mass percentage for the dilution of the elastomer and the conditions of the spin coating can be determined so as to form a microstructure of 4 to 6 μm in forming the roughness of the surface of the dielectric 130.

According to various embodiments, the thickness of the dielectric layer 130 may be,

i) In order to effectively express the roughness of the surfaces of the electrodes 111 and 121, an elastomer having a thickness as thin as possible,

ii) a thickness in the range not exceeding the dielectric strength of the elastomer, taking into account the applied voltage,

iii) a thickness within a range in which no defect such as a pin-hole is formed due to the roughness of the surfaces of the electrodes 111 and 121,

At least one of the following conditions may be satisfied.

According to a preferred embodiment, the roughness of the surface of the dielectric 130 to be formed satisfies the conditions iii) and i), and the roughness of the formed electrodes 130,111 formed on the substrates 110,120 and / or the substrates 110,120, Based on the surface roughness of the surface layer.

For this, referring to Table 1, as the surface roughness of the electrodes 111 and 121 formed on the substrates 110 and 120 and / or the substrates 110 and 120 is increased, the weight percentage of the diluted elastomer is increased, The weight percentage of the elastomer can be lowered as the surface roughness of the electrodes 111 and 121 formed on the substrates 110 and 120 and / or the substrates 110 and 120 is lower.

The microstructure of the rough surface formed on the surface of the dielectric 130 of the lower substrate 110 and the upper substrate 120 is such that when the pressure 300 is applied as shown in Figure 10, The surface of the first electrode 111 of the lower substrate 110 and the surface of the second electrode 121 of the upper substrate 120 may form an interlocked structure 321.

Such a cross structure is similar to the internal structure when pressure is applied to sense a tactile sense with a human finger. For example, the human fingers have a cross structure of the epidermis and the dermis, and this cross structure enhances the spatial resolution by amplifying the tactile signal of the portion where the stimulus is directly applied .

Similarly, the pressure sensor 100 has implemented a structure in which portions of the surface of the dielectric 130 are in contact with each other and the rough surface of the dielectric 130 is engaged when the pressure 300 is applied, as described above. That is, the surfaces of the electrodes 111 and 121 serving as the base of the rough surface of the dielectric 130 also form a cross structure, thereby increasing the area A between the electrodes in determining the capacitance.

In order to effectively generate the difference in capacitance by using the roughness of the surface formed on the lower substrate 110 and the upper substrate 120 constituting the pressure sensor 100, need.

For this purpose, a curl is formed on the lower substrate and the upper substrate, and an air layer may be formed between the facing dielectric layers of the lower substrate 110 and the upper substrate 120.

For example, the curls formed on the lower substrate 110 and the upper substrate 120 may have the characteristics of the flexible substrate 110-1 having flexibility as shown in FIG. 9 and the characteristics of the electrodes 111 and 121 and the dielectric 130 , A compressive strain based on the difference in thermal expansion rate formed between the flexible substrate 110-1 and the dielectric 130 after curing, for example, Curls may be formed so as to concave the substrates 110 and 120 in the direction of the dielectric 130.

10, an air layer (e.g., a large air layer) is formed between the lower substrate 110 provided on the pressure sensor 100 and the facing dielectric 130 of the upper substrate 120, using the curl formed as described above. , 310 can be formed.

The air layer 310 between the dielectrics reduces the elastic resistance when the pressure 300 is applied to the pressure sensor 100 and thus the distance d between the electrodes that change when the pressure 300 is applied is relatively , The magnitude of the change in the capacitance can be increased.

The air layer 310 between the dielectrics may also be removed or deformed into a plurality of small air layers when the pressure 300 is applied to the pressure sensor 100 due to the engagement of the microstructure formed in the dielectric 130 .

Since the dielectric constant of air is one less than the dielectric constant of the elastomer (epsilon, elastomer 3), the application of pressure 300 results in a large air layer 310 being based on the cross structure 320 By changing or removing the small air layer, a change occurs in the dielectric constant, and thus the effective dielectric constant can be greatly increased, so that the change magnitude of the capacitance can be increased.

As described above, it is possible to form a microstructure according to roughness and roughness in the dielectric body 130 without forming an artificial structure in the dielectric body, or performing processes such as photolithography and etching, The difference in capacitance can be largely formed by using the capacitance sensor 100, and thus the sensing sensitivity of the pressure sensor 100 can be improved. The sensing sensitivity of a capacitive pressure sensor can be generally described using Equation (4) below.

(4)

(4)

는 가해진 압력을 나타내며,

는 압력이 가해지기 전의 정전용량,

는 압력이 가해진 후의 정전용량)(here,

Lt; / RTI > represents the applied pressure,

Is the capacitance before pressure is applied,

Is the capacitance after pressure is applied)

The sensing sensitivity of the pressure sensor 100 is improved by increasing the magnitude of the change in capacitance based on the above-described Equation (4), and therefore, by using the input sensor 100 according to various embodiments of the present invention A sensing sensitivity graph as shown in FIG.

Referring to FIG. 11, the sensing sensitivity of the pressure sensor 100 can be determined based on the degree of dilution of the elastomer used as the dielectric 130. At this time, when the elastomer diluted with hydrocarbons is used, it indicates that the sensing sensitivity of the pressure sensor 100 is high. Especially, when the elastomer is 40 wt.%, It can be confirmed that the sensitivity is the highest.

The elastic resistance of the lower substrate 110 and / or the upper substrate 120 increases, and it is difficult to reduce the distance d between the electrodes, and the increase of the effective dielectric constant or the increase of the area A between the electrodes Can not be obtained. This is easily confirmed by the sensitivity of the pressure sensor using 100 wt.% Of elastomer (elastomer not diluted in hydrocarbon).

Even in the case of a pressure sensor using 100 wt.% Of elastomer, it is possible to form a curl of a flexible substrate under the influence of compressive deformation during the manufacturing process, but this is actually at an insufficient level. The characteristic that the material itself can easily bend or twist is related to the following equation (5).

(5)

(5)

(Where t is the thickness of the entire pressure sensor)

From the viewpoint of the flexural rigidity, the thicker the thickness, the greater the strength of the material itself. That is, in the case of the 100 wt.% Elastomer, since the elastomer itself is very thick, the formation of curl is not easy compared with the case of the diluted elastomer. Furthermore, even if curl is formed, if the pressure 300 is applied due to the high viscosity of the elastomer itself, the lower substrate 110 and the upper substrate 120 may be adhered to each other, which may have a negative effect on the efficiency of the sensor.

On the other hand, although it is expected that the more the elastomer is diluted with the hydrocarbon, for example, the lower the weight percentage of the elastomer is lowered to 40 wt.% Or less, the sensitivity will be improved. However, defects such as pin- The function as a dielectric may be lost due to the influence of the dielectric layer.

Accordingly, the weight percentage (or weight ratio) of the elastomer according to an embodiment of the present invention preferably maintains 40 wt.%, But is not so limited, and the degree of dilution of the elastomer varies depending on the roughness of the electrode used .

In other words, the roughness of the surface of the dielectric 130 can be formed by adjusting the degree of dilution based on the roughness of the material used as the electrode, thereby greatly improving the sensing sensitivity of the pressure sensor 130.

According to various embodiments of the present invention, the values measured from the pressure sensor 100 can be divided into various stages using greatly enhanced sensing sensitivity. For example, as shown in Figs. 11, 12 and 13, it is possible to determine the sensing sensitivity of the pressure sensor 100 and its change based on the change in pressure (or weight) and the capacitance, And the pressure (or weight) applied to the pressure sensor 100 can be divided into a plurality of levels by using the change.

Referring to FIG. 13, in the case of typing as in the left image, the pressure sensor 100 according to various embodiments of the present invention clearly shows the change in the capacitance measured as the image on the right according to the applied pressure, , It is possible to determine a reference point for discriminating the level of the pressure based on the magnitude (numerical value) of such a capacitance.

According to one embodiment, as shown in the top graph of FIG. 11, in the case of a pressure sensor 100 in which a 40 wt.% Diluted elastomer is used as the dielectric 130, . For example, the sensing sensitivity of 0.62 kPa ^-1 can be confirmed at 0 to 2 kPa, and the sensing sensitivity of 0.28 kPa ^-1 at 2 to 6 kPa is greatly changed.

Generally, a pressure sensor of a commercially available keyboard detects a load of about 5 to 6 kPa (50 to 60 g). Thus, in addressing the sensing sensitivity of the pressure sensor 100, it is possible to distinguish between a first pressure range of less than 6 kPa and a second pressure range of greater than 6 kPa at a reference (e.g., first reference pressure) of 6 kPa , The first pressure can be used to replace the input of a conventional keyboard.

At this time, it is possible to process another key input using the second pressure. For example, when sensing the pressure in the first pressure range through the pressure sensor 100, it can be processed to input a key input of a general keyboard, for example, lower case letters. On the other hand, when the pressure of the second pressure range is sensed through the pressure sensor 100, it can be regarded as inputting another specified key.

According to one embodiment, when sensing the pressure in the second pressure range through the pressure sensor 100, a key input (for example, alphabet capital letters As shown in Fig.

Further, it is obvious that the pressure range based on the sensing sensitivity of the pressure sensor 100 is not limited to two levels, but can be divided into various levels. For example, with a capacitive solid state keyboard, it senses a load of 3kPa (or 30g), reducing fatigue in input work and achieving smooth touch.

Accordingly, assuming that a general keyboard detects pressure of 3 kPa to 6 kPa to perform key input, according to one embodiment, a reference value of 2 kPa (for example, A second reference pressure) and a pressure sensed within the third pressure range may be treated as inputting another specified key.

For example, in the case of a keyboard, a key can be entered in response to an erroneous input that is thrown during a user's quick typing. Therefore, it is possible to determine that the input of the third pressure range is not input by the user, thereby reducing the occurrence of typo during typing of the user.

Referring to FIG. 14, the pressure sensor 100 according to various embodiments of the present invention not only has a high sensing sensitivity as described above, but also has a fast response time and a relaxation time Lt; / RTI >

For example, the diluted weight percentage of the elastomer that constitutes the dielectric 130 is not only a configuration for forming the roughness of the dielectric surface as described above, but also improves the sensing speed and recovery speed of the pressure sensor 100 As shown in FIG.

According to one embodiment, as shown in FIG. 14, when a pressure sensor having a weight percentage of an elastomer constituting a dielectric of 100 wt.% And 40 wt.% Is compared, a 40 wt.% Pressure sensor 100 ) Than that of 100 wt.% Pressure sensor, both the detection speed and the recovery speed are faster in both the pressure of 2 kPa and the pressure of 5 kPa.

In addition, the pressure sensor 100 can improve the detection speed and the recovery speed by using the elastic characteristics of the flexible substrate 110-1, which is the material of the pressure sensor 100. [ For example, a flexible substrate such as paper or plastic has a characteristic of reversibly maintaining its shape above a certain bending radius even if it is bent by using a pressure. At this time, due to the vertical drag applied from the pressure sensor 100 Deformation is very large in radius of curvature, so it can quickly recover its original shape.

According to one embodiment, as shown in FIG. 15, it is possible to repeatedly apply a force of 0.1 N (10 kPa) to the flexible substrate 110-1 having a curled shape with a width of 0.09 cm ² . At this time, the curl of the flexible substrate 110-1 with respect to the pressure repeatedly applied to the flexible substrate 110-1 exhibits a reversible elastic property, except for the irreversible deformation initially generated.

In general, the flexible substrate 110-1 itself can be included in viscoelastic materials as well as the elastomer, so that the sensing speed and the recovery speed can be judged to be slow. However, curled flexible substrates are structurally very fast in detection and recovery speeds and can be reversibly restored in shape.

According to the above description, the reversible elastic characteristics of the pressure sensor 100 can be modeled. For this purpose, a Kelvin-Voight model can be applied to the strain-stress characteristics of viscoelastic materials. The Kelvin-Voight model is a model of viscoelastic material. It is represented by a parallel connection of a spring representing elasticity and a dashpot representing viscosity, and their strain and stress ) Can be modeled as the following equation (6).

(6)

(6)

는 normal stress,

는 normal strain,

는 strain rate,

는 elastic modulus(Young's modulus),

는 viscosity coefficient)(here,

Normal stress,

Normal strain,

Strain rate,

Elastic modulus (Young's modulus),

Viscosity coefficient)

16 and FIG. 6, components of the pressure sensor 100 according to various embodiments of the present invention include a curled dielectric 130 and a flexible substrate 110- 1).

At this time, the curl of the flexible substrate 110-1 can be confirmed as an elastic material through nanoindentation analysis, and can be expressed as a spring. Since the dielectric 130 and the flexible substrate 110-1 are viscoelastic materials, they can be represented by a Kelvin-Void model. The pressure sensor 100 is a structure in which these components are connected in series, and the element that first changes when the pressure 300 is applied in the series structure can be determined depending on each Young's modulus.

Young's modulus of curling (30 kPa) of the flexible substrate 110-1 is the lowest calculation result and Young's moduli of the dielectric 130 and the flexible substrate 110-1 themselves can be determined to be about 1 MPa and 20 MPa, respectively. Therefore, when the pressure is applied, the curl of the flexible substrate 110-1 is preferentially deformed. As a result, as shown in the graph of Fig. 14, high sensitivity sensing of the pressure sensor 100 is possible, .

In addition, since it has a fast sensing speed and a recovery speed, hysteresis hardly occurs as shown in the upper graph of FIG. 17, and the performance is maintained even in the repetitive pressure test of about 5000 times as shown in the lower graph of FIG. Stability can be ensured.

The pressure sensor 100 not only forms a kind of microstructure through the roughness of the surfaces of the electrodes 111 and 121 and / or the dielectric 130, but also forms a microstructure on the flexible substrate 110 -1, and when a pressure is applied to the pressure sensor 100 using curls formed on the substrates 110 and 120, it is possible to secure a fast sensing speed, a recovery speed, and a high sensitivity sensing performance .

1, the control unit 200 of the input device 10 using the high sensitivity pressure sensor includes a main control unit 210, a demultiplexer 220, and a multiplexer 230. The main control unit 210 generates an excitation signal input to the pressure sensor 100 and receives a signal output from the pressure sensor 100 and transmits the signal to an output device such as a monitor .

Here, the excitation signal may be a signal for measuring the capacitance of the pressure sensor 100, that is, a signal input for grasping whether it is a touch (and / or a pressing force). The demultiplexer 220 may perform a function of distributing a serial signal input from the main control unit 210 to a plurality of pressure sensors in parallel.

The multiplexer 230 converts a parallel input signal received from a plurality of pressure sensors into a serial signal.

Meanwhile, the control unit of the input device 10 using the high-sensitivity pressure sensor may further include an amplifier 240 and an analog-to-digital converter (ADC) 250. The amplifier 240 amplifies the serial signal outputted from the multiplexer 230. The analog-to-digital converter 250 is connected to the output of the amplifier 240 and amplified by the amplifier 240, And converts the signal into a digital signal.

Hereinafter, an example of driving the input device 10 will be described.

According to one embodiment, the excitation signal generated in the main control unit 210 may be distributed to the plurality of pressure sensors through the demultiplexer 220, respectively. When the user touches the pressure sensor 100 and performs typing in the state that the excitation signal is applied, the parallel analog output signal of the pressure sensor 100 is converted into the serial analog output signal through the multiplexer 230, The serial analog output signal may be amplified through an amplifier 240, converted into a digital circuit through an analog-to-digital converter 250, and then input to a main control unit 210.

The signal input to the main control unit 210 may be a signal modulated by the charge and discharge of the capacitor generated through the pressure sensor 100, with an excitational signal output to the first pressure sensor 100. The charging and discharging time t and the voltage Vc across the capacitor at the time correspond to the relationship between the capacitance C of the pressure sensor and the resistance R of the circuit and the voltage intensity V signal of the excitation signal Can be explained using Equation (7) below.

(7)

(7)

The capacitance value of the pressure sensor 100 can be determined by calculating the maximum and minimum voltages of the signal input to the main controller unit 210 and substituting the voltage and period of the applied excitation signal into Equation (7).

As described above, the main control unit 210 can process the output of the pressure sensor 100 based on the signal output from the pressure sensor 100 to output the capacitance values of the pressure sensor.

Since the capacitance value of the pressure sensor 100 is proportional to the applied pressure, it is possible to implement a 3D touch (or 3D force touch) that measures the magnitude of the capacitance and senses the pressure for a plurality of levels by using the input intensity.

According to one embodiment, the input device 10 using the high-sensitivity pressure sensor assigns an alphabetic character to each pressure sensor 100, compares the measured capacitance with a threshold level, and when a small capacitance is measured, And output a capital letter when a large capacitance is measured.

For example, the main controller unit 210 determines whether the pressure inputted through the pressure sensor 100 is equal to or higher than a reference pressure, for example, a first reference pressure of 6 kPa, A capacitance (e.g., a first signal) and a second capacitance (e.g., a second signal) corresponding to a pressure range greater than 6 kPa.

At this time, the main controller unit 210 outputs a lower case letter when the capacitance measured through the pressure sensor 100 is included in the first capacitance range, and outputs an upper case letter when the measured capacitance is included in the second capacitance range have.

Further, the controller unit 210 can determine a third capacitance corresponding to a pressure less than 3 kPa based on a pressure that is input through the pressure sensor 100, for example, a pressure of 3 kPa.

At this time, if the capacitance measured through the pressure sensor 100 is included in the third capacitance range, the main controller unit 210 can treat the absence of a key input.

As described above, by improving the sensing sensitivity of the pressure sensor 100 without significantly changing the process of the pressure sensor, the pressure measured from the pressure sensor 100 can be divided into a plurality of levels, Can be provided.

Referring to FIG. 18, a high-sensitivity pressure sensor 100 and an input device 10 using the same according to various embodiments of the present invention can be provided as a computer keyboard. Such a computer keyboard does not use a caps lock or a shift key, and only a difference in pressure applied to the pressure sensor 100 as shown in Fig. 18 makes it possible to change the upper and lower case letters such as " Yonsei " You can enter mixed words.

The input device 10 using the high-sensitivity input sensor identifies the pressure acting on the pressure sensors as shown in the right-hand table of Fig. 18, and when the pressure is greater than a specified value, quot; Y " when a pressure higher than a predetermined reference pressure is applied from a pressure sensor designated to output a signal corresponding to " y ".

According to various embodiments, in the input device 10 using the high-sensitivity pressure sensor, the controller 200 may control the pressure sensor 100 according to the intensity, time, or frequency of the applied pressure applied to the pressure sensor 100 It is possible to process (or recognize) the signals output through the respective channels as different inputs.

Although the keyboard is described as the input device 10 using the high-sensitivity pressure sensor as described above, the present invention is not limited thereto. The keyboard may be applied to various input devices for inputting a key according to a keypad, a touch pad, It is self-evident.

Further, the input device using the high-sensitivity pressure sensor according to the embodiment of the present invention can be applied to various types of devices such as a paper, graphite or the like which can produce materials commonly used in daily life, for example, It is possible to provide an input device at an extremely low cost in accordance with the reduction of material and manufacturing process cost while realizing a high sensitivity characteristic.

Further, since the flexible printed circuit board is manufactured using the flexible printed circuit board, it is possible to provide an input device that can be bent, thereby providing an input device that is easy to carry.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the invention is not limited to the disclosed exemplary embodiments, It will be understood by those skilled 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.

10: Input device using high sensitive pressure sensor
100: pressure sensor 110: lower substrate
120: upper substrate 111: first electrode
121: second electrode 130: dielectric
141, 142: connection terminal 151, 152: connection terminal
200: control unit 210: main control unit
220: Demultiplexer 230: Multiplexer
240: Amplifier 250: Analog-to-digital converter

Claims (20)

A lower substrate on which a first electrode having a surface roughness is formed;
An upper substrate on which a second electrode having a surface roughness is formed; And
And a dielectric material laminated between the lower substrate and the upper substrate so as to be disposed between the first electrode and the second electrode. The method according to claim 1,
Wherein the dielectric material surrounds the uneven surface of the first electrode or the second electrode due to the surface roughness of the first electrode or the second electrode. 3. The method of claim 2,
Wherein the dielectric material comprises an elastomer, wherein the weight percentage in the dielectric material of the elastomer is determined according to the surface roughness and the thickness of the dielectric material to be formed. The method according to claim 1,
Wherein the lower substrate or the upper substrate is a flexible or stretchable material. The method according to claim 1,
Wherein the surface roughness of the first electrode or the second electrode is represented by the surface roughness of the lower substrate or the upper substrate. The method according to claim 1,
Wherein the surface roughness of the first electrode or the second electrode is generated when the electrode is formed or after the electrode is formed. The method according to claim 1,
Wherein the dielectric material comprises:
A lower dielectric layer provided on the first electrode; And
And an upper dielectric layer provided on the second electrode. 8. The method of claim 7,
Wherein the lower dielectric layer is in close contact with the first electrode, the surface roughness of the first electrode appears on the lower dielectric layer,
Wherein the upper dielectric layer is in close contact with the second electrode, and the surface roughness of the second electrode appears in the upper dielectric layer. 9. The method of claim 8,
Wherein an air layer is formed on at least a part of a region between the lower dielectric layer and the upper dielectric layer. 10. The method of claim 9,
Wherein when pressure is applied to at least one of the lower substrate and the upper substrate,
Characterized in that at least some of the surfaces of the bottom dielectric layer and the top dielectric layer are engaged and form an intersecting structure. 11. The method of claim 10,
The air layer formed between the lower dielectric layer and the upper dielectric layer is removed or divided into smaller air layers based on the cross structure when pressure is applied to at least one of the lower substrate and the upper substrate. , High sensitivity pressure sensor. At least one high-sensitivity pressure sensor according to any one of claims 1 to 11; And
And a control unit for processing a key input according to a signal output from the pressure sensor with respect to the applied pressure when a pressure is applied to the high-sensitivity pressure sensor. 13. The method of claim 12,
And a pressure application unit for applying pressure to at least one of the lower substrate and the upper substrate of the pressure sensor. 13. The method of claim 12,
Wherein,
Processing the first signal when the applied pressure is lower than a predetermined first reference pressure,
And when the applied pressure is equal to or higher than the first reference pressure, processing is performed using the second signal. 13. The method of claim 12,
Wherein the control unit ignores the input when the applied pressure is less than a predetermined second reference pressure. 13. The method of claim 12,
Wherein,
Wherein the input device recognizes different inputs depending on the intensity, time, or frequency of the applied pressure. 13. The method of claim 12,
Wherein,
A main control unit for outputting an excitation signal input to the pressure sensor and inputting the signal outputted from the pressure sensor;
A demultiplexer for distributing the excitation signal to the at least one pressure sensor; And
And a multiplexer for converting a parallel signal output from the at least one pressure sensor into a serial signal. 13. The method of claim 12,
Wherein,
The signal received through the main control unit for each of the at least one high-sensitivity pressure sensor is divided into a plurality of levels by defining a range,
Wherein a different key is assigned to each of the plurality of levels. 19. The method of claim 18,
Wherein,
Determines a key designated for the level of the signal based on the signal received through the main control unit and a high-sensitivity pressure sensor outputting the signal, and transmits the determined key to the multiplexer to input the determined key. , Input device using high sensitivity pressure sensor. 15. The method of claim 12,
Wherein the signal is a capacitance value corresponding to a pressure applied to each of the at least one high-sensitivity pressure sensor.

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