KR20150090940A - Method for detecting pressure event using capacitive touch input device - Google Patents

Abstract

The present invention discloses a technology which detects pressure by using only an electrostatic touch panel. In this technology, a property of stray capacity generated between the electrostatic touch panel and other components changing by touch pressure is used.

Description

TECHNICAL FIELD [0001] The present invention relates to a pressure sensing method using a capacitive touch input device,

The present invention relates to user electronics, and more particularly to techniques for detecting the intensity of pressure as a user input.

The touch input device refers to an input device that detects a contact position of a finger or the like on a touch panel and provides information about the sensed contact position as input information. There are various ways of touch input device, and there are typically resistance type and capacitive type. The capacitive method is largely divided into a magnetic storage method and a mutual storage method.

The mutual charging system has a working pattern and a sensing pattern made of a transparent conductive material, and a capacitance can be formed between the two patterns. When a finger is brought in or brought into contact with these two patterns, the value of the capacitance formed between the two patterns changes. Therefore, by measuring whether or not the value of the capacitance formed between the two patterns changes, it can be determined whether or not the finger touches the touch input device. When an electric signal is applied to the operation pattern for this purpose, a charge is injected into the detection pattern. Since the amount of charge injected depends on the capacitance value formed between the two patterns, the change in capacitance can be determined by measuring the amount of charge injected, and as a result, whether or not the touch input has been made can be known.

On the other hand, in the case of the capacitive touch input device, for example, from the moment when the finger starts to touch the surface of the touch input device, when the pressing pressure is increased, the capacitance formed between the two patterns to a certain level, Can be measured. However, even if the user presses with a pressure higher than the first pressure, the contact area between the finger and the touch input device no longer increases and the value of the capacitance may no longer change. This may not be consistent with the intent of the user to give new orders by giving more pressure.

Therefore, in order to overcome the limitation of the above-mentioned touch technology, a technique of sensing pressure is being studied. The pressure sensing technology is developed not only to overcome the limitations of the touch technology but also by its own logic. However, since each of the new pressure sensing technologies must have its own unique structure, there is a disadvantage that the complexity of the device increases in order to be used with the conventional touch input device.

The present invention provides a new technique for sensing pressure together using a conventional touch input device.

According to an aspect of the present invention, there is provided a touch pressure sensing method comprising: a capacitive touch panel; A second layer disposed below the capacitive touch panel; And a touch input device including a gap formed between the electrostatic touch panel and the second layer. The method includes measuring a change amount of a capacitance of a first touch node among a plurality of touch nodes formed on the capacitive touch panel; And determining that a touch pressure has occurred with respect to the first touch node when the change amount of the capacitance is equal to or greater than a second threshold value. In this case, when the touch pressure is generated, the size of the gap is reduced so that the distance between the electrostatic touch panel and the second layer is shortened. In the second layer, a gap between the second layer and the electrostatic touch panel And a second capacitance is formed in the second insulating layer. The above-described steps may be performed in the user input sensing IC connected to the capacitive touch panel.

The method of claim 2, further comprising, after the measuring, determining a magnitude of the touch pressure based on a value obtained by subtracting a predetermined third threshold from a measured amount of change in capacitance. However, the third threshold value may be equal to or less than the second threshold value and be equal to or greater than the first threshold value.

Here, the capacitive touch panel may include a driving electrode and a sensing electrode, and the second capacitance may be formed between the driving electrode and the second layer.

At this time, the driving electrode and the sensing electrode may be disposed in the same layer, or the driving electrode may be disposed in a layer closer to the second layer than the sensing electrode.

At this time, the electrostatic touch panel may be deformed in shape by an external force, and when the external force disappears, the shape of the touch panel may be restored to its original state. The gap may be filled with a material that narrows the gap between the electrostatic touch panel and the second layer by deforming the shape of the touch panel.

The touch input device may further include an elastic body disposed between the electrostatic touch panel and the second layer and supporting the electrostatic touch panel. The elastic body is retracted in the direction of an external force applied to the electrostatic touch panel, and is restored to its original state when the external force disappears. When the elastic body is retracted, an interval between the electrostatic touch panel and the second layer May be narrowed.

At this time, the second layer may be a display layer.

According to another aspect of the present invention, there is provided an electrostatic touch panel; A second layer disposed below the capacitive touch panel; And a user input sensing IC connected to the capacitive touch panel for sensing touch pressure in a touch input device including a gap formed between the capacitive touch panel and the second layer. The user input sensing IC may include measuring a change amount of a capacitance of a first touch node among a plurality of touch nodes formed on the capacitive touch panel; And determining that a touch pressure has occurred with respect to the first touch node when the change amount of the capacitance is equal to or greater than the second threshold value.

According to the present invention, it is possible to provide a new technique for detecting touch pressure together through an algorithm without particularly changing the structure of the conventional touch input device.

1 shows an example of an electronic device using a conductor pattern according to an embodiment of the present invention.
2 is a detailed view of the touch panel of Fig.
FIG. 3A is a conceptual illustration of a cross-sectional view of a touch input device according to an embodiment of the present invention.
FIG. 3B shows only a cover, a touch panel, a cavity, and a light emitting layer separately in FIG. 3A.
4 is a view for explaining the basic principle of a touch input sensing sensor according to an embodiment of the present invention.
FIG. 5A shows only the structure of a touch panel, a cavity, and a liquid crystal panel among touch input devices provided according to an embodiment of the present invention.
5B to 5D show cross-sectional views taken along line A-A 'in FIG. 5A.
FIG. 5E is a model diagram of the circuit structure described with reference to FIGS. 5A to 5D.
FIG. 6A shows the magnitude i2 of the current flowing in the integrated capacitor of FIG. 5E according to the force of approaching the touch panel or pressing the touch panel.
FIG. 6B shows the capacitance change value? Cx of the sensing capacitor calculated by the output voltage output by the operational amplifier shown in FIG. 5E.
7 is a flowchart illustrating a method of measuring a magnitude of a force applied to a touch input device according to an embodiment of the present invention.
8A and 8B show only touch panel, cavity, and liquid crystal panel of the touch input device provided according to another embodiment of the present invention.
9 is a sectional view of a touch input device according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein, but may be implemented in various other forms. The terminology used herein is for the purpose of understanding the embodiments and is not intended to limit the scope of the present invention. In addition, the singular forms used below include plural forms unless the phrases expressly have the opposite meaning.

1 shows an example of an electronic device using a conductor pattern according to an embodiment of the present invention.

The electronic device 100 can receive an input signal through the touch input device 1. [ The touch input device 1 may be formed to include a substrate having a matrix-shaped electrode pattern formed thereon. The electronic device 100 outputs a signal for driving the touch input device 1 and the touch input device 1 configured to transmit a touch input signal and receives an input signal from the touch input device 1 A voltage driver 2 for receiving a touch panel drive signal from the touch panel control device 3 and generating a touch panel drive voltage from the touch panel control device 3 from the touch panel control device 3, A storage device 5 for storing one or more programs to be executed in accordance with a touch input signal, and a storage device 5 for storing a processing result of the main processor 4 And a display device 6 for outputting the display data. The display device 6 and the touch input device 1 can overlap each other.

The touch panel control device 3 includes a touch sensing unit configured to sense a signal input from the touch input device 1, a panel driving unit configured to generate a touch panel driving signal to transmit an input signal to the touch input device 1, And a touch panel processor adapted to control them. The touch panel processor may be a reprogrammable processor or a processor of the type operated by dedicated logic, such as a state machine.

In addition, although not shown, the electronic device 100 may include a RAM or other type of storage device, and may further include other devices such as a watchdog.

2 is a detailed view of the touch panel of Fig.

The touch input device 1 includes a plurality of transparent electrodes C1 to CM extending in a first direction, for example, a vertical direction, and a plurality of transparent electrodes R1 to RN extending in a second direction, As shown in FIG. Here, the first direction and the second direction may be directions perpendicular to each other, but are not limited thereto. Herein, the electrode in the vertical direction may be referred to as a column electrode or the sensing electrode 72 for convenience, and the electrode in the horizontal direction may be referred to as a row electrode or a driving electrode 71). The sensing electrodes 72 and the driving electrodes 71 intersect with each other, and an area at or near the intersecting point can be referred to as a node 15. [ The term 'node' herein may be referred to as a 'touch node' or a term 'pixel' or 'touch pixel'.

Each node 15 may have a stray capacitance (Cstray) which is an electrostatic capacitance existing between electronic circuit components, wiring, wiring and components and a substrate. The stray capacitance may affect the operation because it acts as a capacitor in a high frequency circuit or a pulse circuit.

When a voltage is applied to the driving electrode 71, electrons are injected to the sensing electrodes 72 through a mutual capacitance Csense at the intersection of the driving electrode 71 and the sensing electrode 72 . The amount of charge Qsense input to each sensing electrode 72 can be expressed as a product of the first level Vdrive of the driving signal and the mutual capacitance Csense (i.e., Qsense = Vdrive * Csense).

The touch input device 1 may have a multi-layer structure. The driving electrode 71 and the sensing electrode 72 may be formed on different layers or on the same layer.

FIG. 3A is a conceptual illustration of a cross-sectional view of a touch input device 1 according to an embodiment of the present invention.

The touch input device 1 may include a housing 10, a cover 20, a touch panel 30, a cavity 40, and light emitting layers 50 and 60.

In one embodiment, the light emitting layer may be composed of a liquid crystal panel 50 and a backlight unit 60.

The touch panel 30 may be a device including the driving electrode 71 and the sensing electrode 72 described above.

The cavity may be a space formed between the touch panel 30 and the light emitting layer, and may be made of air or a material deformable by an external force. In this case, when the upward pressure is applied to the cover 20 in FIG. 3A, the cover 20 and the touch panel 30 can be convex downward. As a result, the depth of the air gap 40 can be reduced at the fin portion.

 FIG. 3B shows only the cover 20, the touch panel 30, the cavity 40, and the light emitting layers 50 and 60 in FIG. 3A.

4 is a view for explaining the basic principle of a touch input sensing sensor according to an embodiment of the present invention.

In Fig. 4, for example, a driving voltage in the form of a pulse train may be applied through the terminal 110. [ At this time, the current i1 flowing from the terminal 110 can be stored in the sensing capacitor 310 by turning on the switches 111 and 114 and putting the switches 112 and 113 in the off state. At this time, the amount of charge accumulated in the sensing capacitor 310 depends on the capacitance value of the sensing capacitor 310.

Then, when the switches 111 and 114 are turned off and the switches 112 and 113 are turned on, the charges stored in the sensing capacitor 310 are switched to the flow of the current i2, 320).

By repeatedly operating the switches 111 to 114 several times, it is possible to repeatedly perform the process of charging and discharging the electric charge to the sensing capacitor 310 several times. As a result, the integrating capacitor 320 Repeated charges are accumulated in turn. As a result, an analog output which can be converted into a digital signal of sufficient resolution is generated at the output terminal 340 of the operational amplifier 330.

As a result, it is detected whether or not the touch input is performed by using the output voltage outputted to the output terminal 340. The main factor for determining the output voltage is the capacitance value of the sensing capacitor 310. However, a more direct cause is that the magnitude of the current i2 flowing into the integrating capacitor 320 is considered to be a main factor for determining the output voltage.

Hereinafter, the principle of the present invention will be described with reference to FIGS. 5 to 8 based on the above-described principle of touch input sensing.

5A shows only the structure of the touch panel 30, the cavity 40, and the liquid crystal panel 50 of the touch input device provided according to an embodiment of the present invention. In another embodiment, a layer other than the liquid crystal panel 50 may be provided directly under the gap 40. [

5B to 5D show cross-sectional views taken along line A-A 'in FIG. 5A.

5B is a diagram illustrating a specific configuration of the touch panel 30 of the present invention and a spatial distribution of an electric field generated when the touch input device according to the present invention is driven.

In Fig. 5B, the touch panel is composed of the driving electrode n1 and the sensing electrode n2 disposed thereon. Basically, it is assumed on the assumption that a circuit of the same type as that of the circuit of Fig. 4 is adopted in Fig. The driving electrode n1 of FIG. 5B corresponds to the node n1 of the sensing capacitor 310 of FIG. 4 and the sensing electrode n2 corresponds to the electrode of the sensing capacitor 310 of the sensing capacitor 310 of FIG. Respectively.

 5B, when a driving voltage is applied to the driving electrode n1, a first electric field 310 is formed between the driving electrode n1 and the sensing electrode n2. This first electric field 310 becomes a main factor for determining the capacitance value of the sensing capacitor 310 of FIG.

In addition, a second electric field 311 is formed between the driving electrode n1 and the liquid crystal panel 50 as well. This second electric field 311 is a major factor for forming the stray capacitance between the driving electrode n1 and the liquid crystal panel 50. [ This stray capacitance can be modeled by the first stray capacitance 311 of FIG. 5E, which will be described later.

At this time, the size of the cavity 40 is represented by d1 in a state where no touch input is present.

5C shows a change in the electric field when the touch input is performed by the finger 600 of the person. 5C, it is assumed that the finger 600 is very close to the surface of the touch input device, or is in contact with the surface of the touch input device. At this time, a pressure strong enough to bend the touch panel 30 downward .

5C, the capacitance value of the sensing capacitor 310 is reduced because part of the first electric field 310 of FIG. 5B is not absorbed by the finger 600 and reaches the sensing electrode n2. That is, as the finger approaches the touch input device, the capacitance value of the sensing capacitor 310 gradually decreases. Since the impedance of the capacitor is inversely proportional to the capacitance value, as the capacitance value of the sensing capacitor 310 decreases, the impedance of the sensing capacitor 310 becomes larger, which makes it more difficult to flow the current through the sensing capacitor 310.

As the finger approaches the touch input device as described above, the amount of change in the capacitance value gradually increases. This phenomenon is shown in FIG.

On the other hand, since the finger 600 can not absorb the second electric field 311 existing in the space 40 between the driving electrode n1 and the liquid crystal panel 50, the size of the second electric field 311 is So that the capacitance value of the first reference capacitor 311 is not changed yet.

5D shows not only the finger 600 touches the surface of the touch input device, but also the case where the touch panel 30 applies a strong pressure downward to the wheel.

At this time, although the touch panel 30 is bent downward by the above-mentioned pressure, the liquid crystal device 50 is arranged such that the properties of the touch panel 30 and the liquid crystal device 50 are different from each other It can be designed differently.

Alternatively, an elastic body may be interposed between the touch panel 30 and the liquid crystal device 50, so that the elastic body can be designed to be contracted in the vertical direction by the pressure.

5D, when the finger 600 applies a strong force downward, the size of the gap 40 between the touch panel 30 and the liquid crystal panel 50 is reduced (d2 <d1). In this case, since the distance between the driving electrode n1 and the liquid crystal panel 50 is shortened, the size of the second electric field 311 becomes larger, and the capacitance value of the first stray capacitor 311 further increases . Since the impedance of the capacitor is inversely proportional to the capacitance value, the larger the capacitance value of the first stray capacitor 311, the smaller the impedance of the first stray capacitor 311 becomes. As a result, the first stray capacitor 311 Current flows more easily. That is, in the case of FIG. 5D, more current can flow through the second electric field 311 than in the case of FIG. 5C, and as the pressure increases, the current flows more easily through the first stray capacitor 311 .

FIG. 5E is a model diagram of the circuit structure described with reference to FIGS. 5A to 5D.

In FIG. 5E, the current i2 flowing into the integrating capacitor 320 can be seen to be proportional to the current i1 flowing out from the terminal 110, minus the current i3 flowing through the first stray capacitor 311. FIG. At this time, regardless of the values of the sensing capacitor 310 and the first reference capacitor 311, the current i1 flows by a predetermined amount. Therefore, the higher the impedance of the sensing capacitor 310 and the lower the impedance of the first stray capacitor 311, the larger the amount of change in i2. In other words, the greater the amount of contact with the touch panel 30 and the greater the pressing force F of the touch panel 30, the larger the amount of change in i2. This phenomenon is shown in Fig. 6A.

FIG. 6A shows the magnitude i2 of the current flowing in the integrated capacitor 320 of FIG. 5E according to the force of approaching the touch panel or pressing the touch panel.

The area A1 has not been touched at all and indicates that the finger is not approaching the touch panel 30 at all. At this time, the magnitude i2 of the current flowing through the integrating capacitor 320 is maintained at a constant value.

Area A2 indicates a finger touching the touch panel or a finger very close to the touch panel. However, this shows a case where the gap 40 between the touch panel 30 and the liquid crystal panel 50 is not narrower than the equilibrium state. At this time, as the touch area increases, the capacitance of the sensing capacitor 310 increases, and thus the impedance of the sensing capacitor 310 increases, so that the magnitude i2 of the current flowing through the integrated capacitor 320 gradually decreases.

The area A3 shows a case where not only a finger is touched to the touch panel but also the gap 40 between the touch panel 30 and the liquid crystal panel 50 is gradually narrowed due to the force of the finger pressing the touch panel. At this time, as the pressing force increases and the gap 40 becomes narrower, the capacitance value of the first speculated capacitor 311 becomes smaller, and the impedance of the first speculated capacitor 311 becomes smaller. Therefore, The amount of charge stored in the memory cell is reduced. Since the amount of charge stored in the sensing capacitor 310 is a source of the current i2 flowing into the integrating capacitor 320, the magnitude i2 of the current flowing in the integrating capacitor 320 gradually decreases as the pressing force increases.

6B shows the capacitance change value? Cx of the sensing capacitor 310 calculated by the output voltage 340 output by the operational amplifier 330 shown in FIG. 5E. At this time, the capacitance change value? Cx of the sensing capacitor 310 may actually appear to be larger due to the influence of the stray capacitors. When the capacitance change value? Cx exceeds the second threshold value? Cx, th2, it can be determined that the touch panel 30 has generated a pressure of about a wheel. The second threshold value [Delta] Cx, th2 may be calculated by theory or may be measured and set by the characteristics of the produced touch input device.

7 is a flowchart illustrating a method of measuring a magnitude of a force applied to a touch input device according to an embodiment of the present invention.

In step S1, the amount of change in the capacitance indicated by the specific touch node is measured.

If the measured value is greater than the first threshold value? Cx, th1 in step S2, it is determined that the touch input has been performed.

If it is determined in step S3 that the measured value is greater than the second threshold value? Cx, th2, it is determined that a pressure enough to deform the touch panel is applied. However, the second threshold value? Cx, th2 is greater than or equal to the first threshold value? Cx, th1.

In step S4, the degree to which the touch panel is deformed is calculated based on a value obtained by subtracting the third threshold from the measured value. However, the relationship of the first threshold? Third threshold? Second threshold can be established.

At this time, the time from when the pressure applied to the touch input device occurs can be determined in advance. For example, the pressure at which the deformation of the touch panel is started may be set to the pressure value of 0, or alternatively, it may be determined that the pressure has occurred even before the deformation of the touch panel is started, 0 &quot;. If this threshold value is defined as the third threshold value? Cx, th3, the relationship of the first threshold value? Cx, th1 <= the third threshold value? Cx, th3 <= the second threshold value? have.

Therefore, in an embodiment of the present invention, the magnitude of the pressure input by the user can be calculated from the measured? Cx -? Cx, th3.

8A and 8B show only the structure of the touch panel 30, the cavity 40, and the liquid crystal panel 50 of the touch input device provided according to another embodiment of the present invention. In another embodiment, a layer other than the liquid crystal panel 50 may be provided directly under the gap 40. [

In this configuration, the driving electrode n1 and the sensing electrode n2 of the touch panel 30 may be provided in the same layer. A second electric field 311 may be formed between the driving electrode n1 and the liquid crystal panel 50 and a third electric field 312 may be formed between the sensing electrode n2 and the liquid crystal panel 50. [ The second electric field 311 and the third electric field 312 may correspond to the first and second stray capacitors 311 and 312 modeled in FIG. 8B, respectively. As the pressing force of the touch panel 30 downward is strengthened, the gap 40 is shortened, so that the capacitance values of the first and second stray capacitors 311 and 312 gradually increase.

Referring to FIG. 8B, the current i2 flowing in the integrating capacitor 320 as shown in FIG. 5E shows a tendency to be proportional to the current i1 - i3 - i2. Therefore, the larger the capacitance value of the first and second stray capacitors 311 and 312 and the smaller the capacitance value of the sensing capacitor 310, the smaller the current i2. Accordingly, as the capacitances of the first and second stray capacitors 311 and 312 are increased, the capacitance value of the sensing capacitor 310 is increased at the output terminal of the operational amplifier 330, Can be measured as being smaller.

Therefore, even if both the driving electrode and the sensing electrode are disposed on the same layer as shown in FIG. 8A, it can be understood that they have the same pattern as that arranged on different layers.

FIG. 9 shows a structure similar to FIG. 3A, but further includes an elastic body 70 between the touch panel 30 and the liquid crystal panel 50. FIG. The elastic body 70 serves to support the touch panel 30 and when the vertical force is applied to the touch panel 30, the shape of the elastic body 70 contracts in the vertical direction, The shape of the elastic body 70 has a property of returning to the original shape within a short time.

In the case of Fig. 9, the touch panel 30 does not need to be rotated by an external force. In contrast, in the case of FIG. 3A, the touch panel 30 must be made of a material that is bent by itself due to an external force.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the essential characteristics thereof. The contents of each claim in the claims may be combined with other claims without departing from the scope of the claims.

Claims (12)

Electrostatic touch panel; A second layer disposed below the capacitive touch panel; And a touch input device including a gap formed between the capacitive touch panel and the second layer,
Measuring a change amount of a capacitance of the first touch node among the plurality of touch nodes formed on the capacitive touch panel; And
Determining that a touch pressure has occurred with respect to the first touch node when the change amount of the capacitance is equal to or greater than a second threshold value
/ RTI &gt;
Wherein the gap between the electrostatic touch panel and the second layer is reduced when the touch pressure is generated,
Touch Pressure Sensing Method The method of claim 1, further comprising: after the measuring, determining that a touch input has occurred if the amount of change in capacitance is greater than or equal to a first threshold value that is less than the second threshold. 3. The method according to claim 2, further comprising, after the measuring step, determining a magnitude of the touch pressure based on a value obtained by subtracting a predetermined third threshold from a measured amount of change in capacitance Wherein the threshold is below the second threshold and above the first threshold. The touch sensing method of claim 1, wherein the capacitive touch panel includes a driving electrode and a sensing electrode, and the second capacitance is formed between the driving electrode and the second layer. The touch pressure sensing method according to claim 4, wherein the driving electrode and the sensing electrode are disposed in the same layer, or the driving electrode is disposed in a layer closer to the second layer than the sensing electrode. The method according to claim 1,
The electrostatic touch panel is made of a material that can be deformed by an external force and can return to its original shape when the external force disappears,
Wherein the gap is filled with a material that narrows the gap between the electrostatic touch panel and the second layer by deforming the shape of the touch panel.
Touch pressure sensing method. The method according to claim 1,
Wherein the touch input device further comprises an elastic body disposed between the electrostatic touch panel and the second layer and supporting the electrostatic touch panel,
The elastic body is retracted in the direction of an external force applied to the electrostatic touch panel and restored to its original state when the external force disappears,
Wherein the gap between the electrostatic touch panel and the second layer is narrowed when the elastic body is contracted.
Touch pressure sensing method. The method of claim 1, wherein the second layer is a display layer. The touch pressure sensing method of claim 1, wherein the second layer includes a component made of a material such that a second capacitance is formed between the second layer and the electrostatic touch panel. Electrostatic touch panel; A second layer disposed below the capacitive touch panel; A user input sensing IC connected to the capacitive touch panel for sensing a touch pressure in a touch input device including a gap formed between the capacitive touch panel and the second layer,
Measuring a change amount of a capacitance of the first touch node among the plurality of touch nodes formed on the capacitive touch panel; And
Determining that a touch pressure has occurred with respect to the first touch node when the change amount of the capacitance is equal to or greater than a second threshold value
, And the &lt; RTI ID =
Wherein the gap between the electrostatic touch panel and the second layer is reduced when the touch pressure is generated,
User input sensing IC. The method according to claim 10, further comprising, after the measuring step, determining a magnitude of the touch pressure based on a value obtained by subtracting a predetermined third threshold from a measured amount of change in capacitance And the third threshold is below the second threshold and above the first threshold. 11. The method of claim 10,
The electrostatic touch panel is made of a material that can be deformed by an external force and can return to its original shape when the external force disappears,
Wherein the gap is filled with a material that narrows the gap between the electrostatic touch panel and the second layer by deforming the shape of the touch panel.
User input sensing IC.

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