Touch operation sensing device using impedance change caused by touch operation

A touch operation sensing device configured to be added to an electronic device, the electronic device including a touch member disposed in a housing and having conductivity, the touch operation sensing device includes an oscillation circuit disposed on an internal side of the touch member and including an inductor element and a capacitor element to generate an oscillation signal in response to changed impedance during a touch operation through the touch member, and an insulating member disposed between a first terminal of the inductor element and the touch member, and between a second terminal of the inductor element and the touch member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 USC 119(a) of Korean Patent Application Nos. 10-2019-0105439 filed on Aug. 27, 2019, and 10-2019-0153233 filed on Nov. 26, 2019, in the Korean Intellectual Property Office, the entire disclosures of which are incorporated herein by reference for all purposes.

BACKGROUND

This disclosure relates to a touch operation sensing device using an impedance change caused by a touch operation.

2. Description of the Background

In general, it is desirable that a wearable device be thin and have a simple, clean design. To achieve this, existing mechanical switches in wearable devices may be replaced with non-mechanical switches implemented using dustproof and waterproof technologies, enabling the production of wearable devices having seamless housings.

For the purpose of implementing and developing non-mechanical switches, current technologies such as touch-on-metal (ToM) technology in which a metal surface is touched, a capacitance sensing method using a touch panel, a microelectromechanical system (MEMS), a micro strain gauge, and other technologies have been developed. In addition, even a force touch function that can determine how hard a button has been pushed is under development.

In the case of an existing mechanical switch, a large size and a large amount of internal space may be required to implement a switching function, and a design may be somewhat untidy and a large space may be required due to an outwardly protruding shape of the switch, the structure of the switch not being integrated with an external case, and other problems.

In addition, there may be a risk of an electric shock due to direct contact with an electrically connected mechanical switch. Moreover, a structure of the mechanical switch may make it difficult to implement dustproofing and waterproofing.

In an existing switching device, there is need for a technology to precisely detect an impedance change, caused by a touch operation, irrespective of locations of a metal case and an internal coil or a distance between the metal case and the internal coil.

SUMMARY

In one general aspect, a touch operation sensing device configured to be added to an electronic device, the electronic device including a touch member disposed in a housing and having conductivity, the touch operation sensing device includes an oscillation circuit disposed on an internal side of the touch member and including an inductor element and a capacitor element to generate an oscillation signal in response to changed impedance during a touch operation through the touch member, and an insulating member disposed between a first terminal of the inductor element and the touch member, and between a second terminal of the inductor element and the touch member.

The touch operation sensing device may further include a touch operation detection circuit configured to detect a touch operation in response to the oscillation signal from the oscillation circuit.

The insulating member may include an integrated insulator disposed between the first terminal of the inductor element and the touch member and between the second terminal of the inductor element and the touch member.

The insulating member may include a first insulator disposed between the first terminal of the inductor element and the touch member, and a second insulator disposed between the second terminal of the inductor element and the touch member.

The inductor element may be disposed on one surface of a substrate disposed on an internal side of the touch member, and the capacitor element may be disposed on the one surface of the substrate to be spaced apart from the inductor element.

The oscillation circuit may include an inductance circuit including the inductor element, a capacitor circuit including the capacitor element to be electrically connected to the inductance element, and an amplifier circuit connected to the inductance circuit and the capacitor circuit, and configured to generate an oscillation signal having a resonant frequency, variable during a touch operation through the touch member.

The touch operation sensing device may further include a first conductor line electrically connecting the first insulator, attached to an internal side surface of the touch member, and the first terminal of the inductor element to each other, and a second conductor line electrically connecting the second insulator, attached to the internal side surface of the touch member, and the second terminal of the inductor element to each other.

A distance between the first terminal and the second terminal of the inductor element may be greater than half of a length of the inductor element in a length direction.

One surface of the inductor element may be disposed on an internal side surface of the touch member and the capacitor element may be disposed on another surface of the inductor element opposing the one surface, and a circuit part disposed on the other surface of the inductor element may include the touch operation detection circuit.

The touch operation detection circuit may include a frequency digital converter configured to convert the oscillation signal from the oscillation circuit into a count value, and a touch operation detector configured to detect a touch operation in response to the count value input from the frequency digital converter to output a detection signal.

The frequency digital converter may be configured to count a reference clock signal, divided by dividing an input reference clock signal by a division ratio, using the oscillation signal, to generate the count value.

The frequency digital converter may include a frequency down-converter configured to generate a reference clock signal divided by dividing an input reference clock signal by a division ratio, a periodic timer configured to count a one-period time of the divided reference clock signal using the oscillation signal to generate a periodic count value, and a cascaded integrator-comb (CIC) filter circuit configured to output the count value generated by performing cumulative amplification on the periodic count value received from the periodic timer.

The reference clock signal may have a frequency less than 0.5 times a frequency of the oscillation signal.

The CIC filter circuit may be configured to perform cumulative amplification of the periodic count value from the periodic timer using a cumulative gain determined in response to a predetermined integrating stage number, a predetermined decimator factor, and a predetermined comb differential delay order, and configured to provide the cumulatively amplified periodic count value.

The CIC filter circuit may include a decimator CIC filter configured to perform cumulative amplification of the periodic count value received from the periodic timer, and a first-order CIC filter configured to perform a moving average on an output value of the decimator CIC filter to output the count value with noise removed from the output value from the decimator CIC filter.

The touch operation detector may include a delay part configured to delay the count value, received from the frequency digital converter, by a time determined in response to a delay control signal to output a delayed count value, a subtraction part configured to output a difference value generated by subtracting the count value and the delayed count value received from the delay part, and a comparison part configured to compare the difference value, received from the subtraction part, with a predetermined threshold value to output a detection signal having a high level or a low level determined in response to the comparison result.

A mobile device may include the touch operation sensing device, a control circuit, and a touch operation detection circuit configured to detect a touch operation in response to the oscillation signal from the oscillation circuit, wherein in response to a detected touch operation, the control circuit may be configured to implement one or more of control power of the mobile device, lock the mobile device, navigate content display of a touch screen of the mobile device, control input to the touch screen, control color of the touch screen, control input to a speaker of the mobile device, and control volume of the speaker.

The mobile device may be a smartphone, a smartwatch, smart glasses, a virtual reality device, an augmented reality device, a head-mounted display, headphones, an earbud, a door lock, a vehicle smart key, a computer, or a refrigerator.

In another general aspect, an electronic device includes a housing, a touch member disposed in the housing and having conductivity, an oscillation circuit disposed on an internal side of the touch member and including an inductor element and a capacitor element to generate an oscillation signal in response to changed impedance during a touch operation through the touch member, and an insulating member disposed between a first terminal of the inductor element and the touch member, and between a second terminal of the inductor element and the touch member.

The touch member may be a conductor.

A first terminal of the inductor and a second terminal of the inductor may be disposed on an insulator disposed on a surface of the touch member on an internal side of the housing.

A first conductor line may be disposed between the first terminal and the insulator, and a second conductor line may be disposed between the second terminal and the insulator.

The insulator may include a first insulator disposed between the first conductor line and the touch member spaced apart from a second insulator disposed between the second conductor line and the touch member.

The insulator may include a first insulator disposed between the first terminal and the touch member spaced apart from a second insulator disposed between the second terminal and the touch member.

A substrate may be disposed inside of the housing and spaced apart from the touch member, wherein the inductor and the conductor may be disposed on a surface of the substrate spaced apart from each other.

A frequency down-converter may divide an input reference clock signal by a division ratio to output a divided reference clock signal, a periodic timer may count a one-period time of the divided reference clock signal using the oscillation signal to output a periodic count value, a cascaded integrator-comb (CIC) filter circuit may include a decimator CIC filter performing cumulative amplification of the periodic count value received from the periodic timer, and a first-order CIC filter performing a moving average on an output value of the decimator CIC filter to output the count value with noise removed from the output value from the decimator CIC filter, a delay part may delay the count value, received from the CIC filter circuit, by a time determined in response to a delay control signal to output a delayed count value, a subtraction part may subtract the count value and the delayed count value received from the delay part to output a difference value, and a comparison part may compare the difference value, received from the subtraction part, with a predetermined threshold value to output a detection signal having a high level or a low level determined in response to the comparison, wherein the oscillation circuit may include an amplifier circuit connected to the inductor and the capacitor, outputting the oscillation signal comprising a resonant frequency, which may vary during the touch operation, and wherein the touch operation may be determined in response to the detection signal.

DETAILED DESCRIPTION

The features described herein may be embodied in different forms, and are not to be construed as being limited to the examples described herein. Rather, the examples described herein have been provided merely to illustrate some of the many possible ways of implementing the methods, apparatuses, and/or systems described herein that will be apparent after an understanding of this disclosure. Hereinafter, while embodiments of the present disclosure will be described in detail with reference to the accompanying drawings, it is noted that examples are not limited to the same.

Throughout the specification, when an element, such as a layer, region, or substrate, is described as being “on,” “connected to,” or “coupled to” another element, it may be directly “on,” “connected to,” or “coupled to” the other element, or there may be one or more other elements intervening therebetween. In contrast, when an element is described as being “directly on,” “directly connected to,” or “directly coupled to” another element, there can be no other elements intervening therebetween. As used herein “portion” of an element may include the whole element or less than the whole element.

An aspect of the present disclosure is to provide a touch operation sensing device, capable of more precisely sensing a touch operation using an impedance change of a touch member in response to a touch operation of the touch member.

FIG. 1is a perspective view illustrating one or more examples of a mobile device as disclosed herein.

Referring toFIG. 1, a mobile device10may include a touch screen11, a housing500, and a touch operation unit TSW including a touch member TM1, for example, as a replacement for a mechanical button switch.

The touch member TM1may be integrated with the housing500. In this case, the term “integrated” refers to the fact that irrespective of whether a material of the touch member and a material of the housing500are the same as each other or are different from each other, the touch member and the housing500are manufactured as a single body so that they cannot be separated from each other after manufacturing thereof and have a unitary structure, not an instrumentally or mechanically separated structure, in which there is no gap between the touch member and the housing500.

InFIG. 1, the touch operation unit TSW is illustrated as including the touch member TM1. However, the touch member TM1is merely an example for ease of description, and it will be understood that touch members are not limited to the touch member TM1and the number of the touch members may be increased in the same manner as the touch member TM1.

As an example, referring toFIG. 1, the mobile device10may be a mobile device such as a smartphone or a wearable device such as a smartwatch. The mobile device10is not limited to a specific device, and may be a mobile device or a wearable electric device, or an electric device having a switch for operation control.

The housing500may be an external case exposed to the outside of an electric device. As an example, when the touch operation sensing device is applied to the mobile device10, the touch operation sensing device may be a cover disposed on a side of the mobile device10. As an example, the housing500may be integrated with a cover disposed on a rear surface of the mobile device10or may be separated from the cover disposed on the rear surface of the mobile device10.

As described above, the housing500may be an external case of an electric device, and is not necessarily limited to a specific location, shape, or structure.

When describing examples in the drawings of the present disclosure, repeated descriptions may be omitted for components having the same reference numeral and the same function, while only differences may be described.

FIG. 2is a cross-sectional view illustrating one or more examples of a touch operation sensing device ofFIG. 1.

Referring toFIGS. 1 and 2, an example of a touch operation sensing device may include a touch operation unit TSW, an oscillation circuit600, and an insulating member700.

In addition, the touch operation sensing device may further include a touch operation detection circuit800.

The touch operation unit TSW may include a touch member TM1integrated with the housing500and having conductivity. As an example, the housing500may be a member having conductivity, similarly to the touch member TM1.

The oscillation circuit600may be disposed on an internal side of the touch member TM1, and may include an inductor element LE1and a capacitor element CE1to generate an oscillation signal LCosc1in response to impedance variation during a touch operation through the touch member TM1.

For example, in this application, impedance, changeable when touched, may correspond to impedance in a distribution constant circuit, and may be at least one of resistance, capacitance, and inductance formed by a passive element, a passive component, various conductor wirings, or the like. In subsequent descriptions, since describing the impedance, changeable when touched, as capacitance is just an example for ease of description; however, the impedance is not limited thereto.

The insulating member700may be disposed between a first terminal PA1of the inductor element LE1and the touch member TM1and between a second terminal PA2of the inductor element LE1and the touch member TM1(FIG. 3).

The touch operation detection circuit800may detect a touch operation using the oscillation signal LCosc1from the oscillation circuit600.

The impedance may be changed in response to an interaction of a touch body (for example, a human hand), the touch operation unit TSW, the insulating member700, and the inductor element LE1during the touch operation, which will be described in detail later.

As an example, the insulating member700may be made of an integrated insulator disposed between the first terminal PA1of the inductor element LE1and the touch member TM1and between the second terminal PA2of the inductor element LE1and the touch member TM1. The integrated insulator may be an insulator composed of one body including the first insulator710and the second insulator720.

FIG. 3is a cross-sectional view, taken along line I-I′ inFIG. 1, illustrating one or more examples of the touch operation sensing device ofFIG. 1.

Referring toFIG. 3, the insulating member700may include a first insulator710and a second insulator720.

The first insulator710may be disposed between the first terminal PA1of the inductor element LE1and the touch member TM1. The second insulator720may be disposed between the second terminal PA2of the inductor element LE1and the touch member TM1. The first terminal PA1and the second terminal PA2of the inductor element LE1are connection pads for electrically connecting the first insulator710and the second insulator720to a substrate200. As an example, the first terminal PA1and the second terminal PA2may be connection pads, each having a predetermined area for electrical connection and electrical characteristics.

The inductor element LE1may be mounted on one surface of the substrate200disposed on an internal side of the touch member TM1. The capacitor element CE1may be spaced apart from the inductor element LE1on the one surface of the substrate200.

The oscillation circuit600may include an inductance circuit610, a capacitance circuit620, and an amplifier circuit630.

The inductance circuit610may include the inductor element LE1.

The capacitance circuit620may include the capacitor element CE1and may be electrically connected to the inductance circuit610through the substrate200.

The amplifier circuit630may be electrically connected to the inductance circuit610and the capacitance circuit620through the substrate200. During a touch operation through the touch member (TM1), the amplifier circuit630may generate an oscillation signal LCosc1having a variable resonant frequency. As an example, the amplifier circuit630may include an inverter or an amplifier maintaining resonance, generated by the inductance circuit610and the capacitance circuit620, to generate an oscillation signal.

The substrate200may be supported by a support bracket300. The support bracket300may support the substrate200and may be attached to an internal structure or a housing of an electric device in the examples described herein.

As an example, the housing500and the touch member TM1may be made of a conductor such as a metal. For example, the inductor element LE1may include a coil pattern having a spiral shape connected between the first terminal PA1and the second terminal PA2.

The first terminal PA1and the second terminal PA2of the inductor element LE1may be electrically connected to a circuit unit CS and the capacitor element CE1through the substrate200.

Accordingly, the inductor element LE1may form a closed circuit through the first and second terminals PA1and PA2, the first and second insulators710and720, and the touch member TM1of the housing500. Such a closed circuit may have metal impedance Zm generated by the touch member TM1, and the metal impedance Zm may be capacitance, inductance, or a combination thereof.

The first insulator710and the second insulator720may also have first insulation capacitance and second insulation capacitance, respectively.

For example, the touch member TM1may be integrated with the housing500, and may be aluminum or another metal.

The insulating member700may be provided to electrically insulate the inductor element LE1from the metal housing500and may be, for example, an adhesive tape or a bond, having adhesive force, or the like.

For example, since the insulating member700is disposed between the inductor element LE1and the touch member TM1of the housing500of a metal, the touch member TM1of a metal may be modeled as a type of metal impedance Zm. The modeled metal impedance Zm may be changed when the touch member TM1is touched by a human hand, and the metal impedance may be changed depending on a location, reached by the human hand, and areas of the first and second terminals PA1and PA2. As an example, when the location reached by the human hand contacts is changed, impedance of the distribution constant circuit, corresponding to a distance from the contact point to the first and second terminals PA1and PA2of the inductor element LE1, may be changed. In addition, when the areas of the first and second terminals PA1and PA2are changed, the impedance may be changed depending on the changed areas.

For example, when a conductor such as a human hand does not touch the touch member TM1, metal impedance of the touch member TM1is maintained at ‘Zm.’ Then, when the conductor such as a human hand touches the touch member TM1, the metal impedance of the touch member TM1may be changed to ‘Zm±α’.

Accordingly, when the metal impedance of the touch member TM1is changed, in response to whether or not touch of the touch member, the resonant frequency of the oscillation circuit600may vary in response to the impedance change of the touch member TM1.

Herein, the term “touch or touch operation” refers to a conductor such as a human hand comes close to or directly touches a touch member of a housing, and a resonant frequency may be varied by metal impedance changed in response to such a touch operation.

The structure of the touch operation sensing device, illustrated inFIG. 3, is just an example, and thus, is not limited thereto.

FIG. 4is a cross-sectional view, taken along line I-I′ inFIG. 1, illustrating one or more other examples of the touch operation sensing device ofFIG. 1.

As compared to the touch operation sensing device inFIG. 3, a touch operation sensing device inFIG. 4may further include a first conductor line L1and a second conductor line L2.

The first conductor line L1may electrically connect a first insulator710, attached to an internal side surface of a touch member TM1, and a first terminal PA1of an inductor element LE1to each other.

The second conductor line L2may electrically connect a second insulator720, attached to the internal side surface of the touch member TM1, and a second terminal PA2of the inductor element LE1to each other.

As an example, the touch operation sensing device inFIG. 4may include a first electrode PE1, disposed between the first insulator710and the first conductor line L1, and a second electrode PE2disposed between the second insulator720and the second conductor line L2.

The first electrode PE1may serve to electrically connect the first insulator710and the first conductor line L1to each other, and the second electrode PE2may serve to electrically connect the second insulator720and the second conductor line L2to each other.

As illustrated inFIG. 4, the inductor element LE1may be disposed to be distant from the touch member TM1. In this case, when a conductor such as a human hand, or the like, touches the touch member TM1, metal impedance of the touch member TM1may be changed (Zm→Zm±α), and a distance between the touch member TM1and the inductor element LE1or a location of the inductor element LE1may be more freely set by the first conductor line L1and the second conductor L2. Accordingly, since the degree of freedom in the location of the inductor element LE1may be improved to locate the inductor element LE1in a desired location, space utilization may be improved.

As an example, the first conductor line L1and the second conductor line L2may be flexible conductor lines such that utilization of a disposition space is improved to increase the degree of freedom in a placement location and a placement distance. When such flexible first and second conductor lines L1and L2are used, locations of the first and second conductor lines L1and L2disposed in the inductor element LE1, a sensing element, may be freely selected.

As described above, the metal impedance may be capacitance, inductance, or a combination thereof. Accordingly, the resonant frequency of the oscillation signal LCosc1(inFIG. 2), generated by the oscillation circuit, may vary when the metal impedance is changed.

FIG. 5is a plan view illustrating one or more examples of a distance D between a first terminal and a second terminal of an inductor element.

Referring toFIG. 5, as an example, when a length of the inductor element LE1in a horizontal direction is defined as ‘L,’ a length of the inductor element LE1in a width direction is defined as ‘W,’ and a distance between the first terminal PA1and the second terminal PA2of the inductor element LE1is defined as ‘D,’ the distance D between the first terminal PA1and the second terminal PA2of the inductor element LE1may be greater than half of a length L of the inductor element LE1in the length direction (L/2).

Since the distance D may affect a magnitude of the metal impedance Zm, sensitivity may be improved by increasing the distance D within the size of the inductor element LE1as much as possible.

The inductor element LE1may be one selected from the group consisting of a printed circuit board (PCB) coil, a flexible printed circuit board (FPCB) coil, a single-sided PCB coil, a double-sided PCB coil, a multilayer PCB coil, and a chip inductor.

As described above, the inductor element LE1may include a flexible PCB (FPCB), and may include various types of PCB other than the FPCB. A circuit unit CS for sensing (for example, an integrated circuit (IC)) and a capacitor element CE1may be provided on the same surface or opposing surfaces of a PCB.

For example, a ferrite sheet, not illustrated, may be disposed on a lower surface of the inductor element LE1, but is not necessarily required. The inductor element LE1does not need to have a specific shape, and may have various shapes such as a circle, a rectangle, and the like.

The circuit unit CS may include a portion of the oscillation circuit600and a touch operation detection circuit800. In this case, the portion of the resonance circuit600may be an amplifier circuit630.

In addition, the circuit unit CS may or may not include a capacitor element CE1. When the capacitor element CE1is not included in the circuit unit CS, the touch operation sensing device may include a capacitor element CE1such as a multilayer ceramic capacitor (MLCC), or the like, disposed independently of the circuit unit CS. In each embodiment, the circuit unit CS may or may not be an integrated circuit.

FIG. 6is a perspective view illustrating one or more examples of the inductor element, andFIG. 7is a perspective view illustrating one or more other examples of the inductor element.

Referring toFIGS. 6 and 7, the inductor element LE1is illustrated as an inductor element in the form of a printed circuit board (PCB) coil formed in a PCB pattern.

For example, the inductor element LE1includes a coil pattern LE1-P having a spiral shape connected between the first terminal PA1and the second terminal PA2, and the coil pattern LE1-P is a PCB pattern.

In one example, when a double-sided PCB having a first surface (for example, an upper surface) and a second surface (for example, a lower surface) is used, a pair of a first terminal PA1and a second terminal PA2may be disposed on the first surface to connect the double-sided PCB to first and second insulators710and720and another pair of a first terminal PA1and a second terminal PA2may be disposed on the second surface to connect the double-sided PCB to a substrate200, as illustrated inFIG. 6.

The first terminal PA1may be connected to an external end (or one end) of the coil pattern LE1-P through the first surface (for example, the upper surface), and the second terminal PA2may be connected to an internal end (or the other end) of the coil pattern LE1-P through a via pattern via the inside thereof.

In another example, referring toFIG. 7, when a double-sided PCB having a first surface (for example, an upper surface) and a second surface (for example, a lower surface) is used, a pair of a first terminal PA1and a second terminal PA2may be disposed on the first surface to connect the double-side PCB to first and second insulators710and720, and another pair of a first terminal PA1and a second terminal PA2may be disposed on the second surface to connect the double-side PCB to a substrate200. A first coil pattern LE1-P1may be formed on the first surface (for example, the upper surface), and a second coil pattern LE1-P2may be formed on the second surface (for example, the lower surface). An internal side end of the first coil pattern LE1-P1and an internal end of the second coil pattern LE1-P2may be connected to each other through a through-conductor. An external side end of the first coil pattern LE1-P1may be connected to the first terminal PA1, and an external side end of the second coil pattern LE1-P2may be connected to the second terminal PA2through the through-conductor.

For example, the inductor element LE1may be formed to have various shapes such as a circle, a triangle, and a rectangle, and the like, but the shape is not limited thereto.

Unlike the description of the inductor element LE1in the form of a double-sided PCB coil, the inductor element LE1inFIGS. 6 and 7may be implemented on a multilayer PCB having a plurality of layers. In this case, the first surface may be an upper surface of an uppermost layer of the multilayer PCB, and the second surface may be an upper surface of a lowermost layer of the multilayer PCB.

FIGS. 6 and 7are just examples of the inductor element LE1in the form of a double-sided PCB coil, and the inductor element LE1is not limited thereto. As the inductor element LE1, any inductor element may be used as long as it is in the form of a PCB coil providing inductance to an oscillation circuit.

FIG. 8is a perspective view illustrating one or more examples of a disposition of the inductor element, andFIG. 9is a perspective view illustrating one or more other examples of a disposition of an inductor element.

Referring toFIG. 8, an inductor element LE1is disposed on one surface of the substrate200, facing a touch member TM1. The one surface of the substrate200, on which the inductor element LE1is disposed, may be disposed parallel to an internal side surface of the touch member TM1while facing the internal side surface of the touch member TM1.

For example, in a three-dimensional (x, y, z) coordinate system ofFIGS. 8 and 9, an x axis is defined as a length direction of the touch member TM1, a y axis is defined as a width direction of the touch member TM1, and a z axis is defined as an upward direction of the touch member TM1.

In the three-dimensional coordinate system, the substrate200and the touch member TM1may each be disposed on an x-y plane while being spaced apart from each other, for example, in the z-axis direction.

Referring toFIG. 9, the inductor element LE1is disposed on one surface of a substrate200. As an example, the substrate200, on which the inductor element LE1is disposed, may be disposed in a direction substantially perpendicular to the touch member TM1, rather than parallel to the touch member TM1.

In a three-dimensional coordinate system, the touch member TM1may be disposed on an x-y plane while being spaced apart from the substrate200, for example, in the z-axis direction, and the substrate200may be disposed on an x-z plane.

Referring toFIGS. 8 and 9, it will be understood that the substrate200, on which the inductor element LE1is disposed, may be disposed in various ways with respect to the touch member TM1. Therefore, the disposition of the substrate200is not limited to the examples illustrated inFIGS. 8 and 9, and any disposition form and any location of the inductor element LE1are not necessarily limited.

FIG. 10illustrates one or more other examples of an inductor element.

Referring toFIG. 10, the substrate200described in other examples may be omitted in this example.

A capacitor element CE1may be disposed on another surface of an inductor element LE1having one surface opposing the other surface attached to an internal side surface of a touch member TM1. In this case, a touch operation detection circuit800may be included in a circuit unit CS disposed on the other surface of the inductor element LE1.

The inductor element LE1includes a multilayer PCB substrate LE1-S having an uppermost surface facing the touch member TM1(see, for example,FIG. 2), and a lowermost surface opposing the uppermost surface.

The multilayer PCB substrate LE1-S may have at least a lowermost layer, an intermediate layer, and an uppermost layer. The lowermost layer may be a lower surface, and the uppermost layer may be an upper surface.

A capacitor element CE1such as an MLCC, or the like, and a circuit unit CS may be disposed on the lower surface of the multilayer PCB substrate LE1-S. The circuit unit CS, the capacitor element CE1, and the coil pattern LE1-P may be electrically connected to each other through the multilayer PCB substrate LE1-S.

In the coil pattern LE1-P, a first terminal PA1and a second terminal PA2may be disposed on upper and lower surfaces of the multilayer PCB substrate LE1-S. The coil pattern LE1-P having a spiral shape may be connected between the first terminal PA1and the second terminal PA2, and the coil pattern LE1-P may be a PCB pattern. A pair of first and second terminals PA1and PA2, disposed on the upper surface, may be connected to first and second insulators710and720, and another pair of first and second terminals PA1and PA2may be electrically connected to the circuit unit CS and the capacitor element CE1.

In addition, the touch operation detection circuit800may be included in the circuit unit CS disposed on the other surface of the inductor element LE1.

FIG. 11is a block diagram illustrating one or more examples of a touch operation detection circuit.

Referring toFIG. 11, a touch operation detection circuit800may include a frequency digital converter810and a touch operation detector830.

The frequency digital converter810may convert an oscillation signal LCosc1from the oscillation circuit600into a count value CV.

The touch operation detector830may detect a touch operation, in response to the count value CV input from the frequency digital converter810, to output a detection signal DF.

FIG. 12is a circuit diagram illustrating one or more examples of a frequency digital converter.

Referring toFIG. 12, a frequency digital converter810may divide an input reference clock signal CLK_ref by a division ratio N to generate a divided reference clock signal DOSC_ref and may count the divided reference clock signal DOSC_ref using an oscillation signal LCosc1to generate a count value CV.

The frequency digital converter810may include a frequency down-converter811, a periodic timer813, and a cascaded integrator-comb (CIC) filter circuit815.

The frequency down-converter811may divide an input reference clock signal CLK_ref by a division ratio N to generate a divided reference clock signal DOSC_ref.

The periodic timer813may generate a periodic count value PCV by counting one-period time of the divided reference clock signal DOSC_ref using the oscillation signal LCosc1.

The CIC filter circuit815may output the count value CV generated by performing cumulative amplification on the periodic count value PCV received from the periodic timer813.

The CIC filter circuit815may perform cumulative amplification of the periodic count value PCV from the periodic timer813using a cumulative gain determined in response to a predetermined integrating stage number, a predetermined decimator factor, and a predetermined comb differential delay order, and may provide the cumulatively amplified periodic count value.

For example, the CIC filter circuit815may include a decimator CIC filter815-1and a first-order CIC filter815-2.

The decimator CIC filter815-1may perform cumulative amplification of the periodic count value PCV received from the periodic timer813.

The first-order CIC filter815-2may perform a moving average on an output value from the decimator CIC filter815-1to output the count value CV with noise removed from the output value from the decimator CIC filter.

For example, when the decimator CIC filter includes an integrating circuit, a decimator, and a differential circuit, the cumulative gain may be obtained as (R*M){circumflex over ( )}S based on a stage order S of the integrating circuit, a decimator factor R, and a delay order M of the differentiating circuit. As an example, when the stage order S of the integrating circuit is 4, the decimator factor R is 1, and the delay order M of the differential circuit is 4, the cumulative gain is 256 ((1*4){circumflex over ( )}4).

The first-order CIC filter815-2may take a moving average, corresponding to a rope pass function, from a count value from the decimator CIC filter to remove noise.

FIG. 13illustrates one or more examples of main signals in the frequency digital converter ofFIG. 12.

Referring toFIG. 13, CLK_ref denotes a reference clock signal, DOSC_ref denotes a divided reference clock signal, and LCosc1denotes an oscillation signal.

The reference clock signal CLK_ref may have a frequency less than 0.5 times a frequency of the oscillation signal LCosc1.

FIG. 14is a circuit diagram illustrating one or more examples of a touch operation detector.

Referring toFIG. 14, a touch operation detector830may include a delay part831, a subtraction part833, and a comparison part835.

The delay part831may delay a count value CV, received from a frequency digital converter810, by a time determined in response to a delay control signal Delay_Ctrl to output a delayed count value CV_Delay.

The subtraction part833may output a difference value Diff generated by subtracting the count value CV and the delayed count value CV_Delay from the delay part831.

The comparison part835may compare the difference value Diff, received from the subtraction part833, with a predetermined threshold value TH to output a detection signal DF having a high level or a low level determined in response to the comparison result.

FIG. 15illustrates one or more examples of various applications of a touch operation sensing device.

Referring toFIG. 15, Application Examples 1 to 7 of a touch operation sensing device are illustrated.

Application Example 1 ofFIG. 15is an example in which an operation control button of Bluetooth® headphones may be a touch operation sensing device, and Application Example 2 ofFIG. 15is an example in which an operation control button of a Bluetooth® earbud may be a touch operation sensing device. As an example, Application Examples 1 and 2 may be examples in which on/off power switches of Bluetooth® headphones and a Bluetooth® earbud may be touch operation sensing devices.

Application Example 3 ofFIG. 15is an example in which an operation control button of smart glasses may be a touch operation sensing device. As an example, Application Example 3 may be an example in which a button for performing functions such as a phone function and a mail function, a home button, and other buttons of a device such as Google Glasses, a virtual reality (VR) device, or an augmented reality (AR) device may be a touch operation sensing device.

Application Example 4 ofFIG. 15is an example in which a door lock button of a vehicle may be a touch operation sensing device. Application Example 5 ofFIG. 15is an example in which a button of a smart key of a vehicle may be a touch operation sensing device. Application Example 6 ofFIG. 15is an example in which an operation control button of a computer may be a touch sensing apparatus. Application Example 7 ofFIG. 15is an example in which an operation control button of a refrigerator may be a touch operation sensing device.

In addition, a touch operation sensing device may be volume and power switches of a laptop computer, a switch of a VR device, a head-mounted display (HMD), a Bluetooth® earphone, a stylus touch pen, or the like, and may be applied to be buttons of a monitor of a home appliance, a refrigerator, a laptop computer, or the like.

For example, a touch operation sensing device being an operation control button of a device may be integrated with a cover, a frame, or a housing of the applied device, and may be used to turn power on and off, control a volume, and perform other specific functions (back, movement to home, locking, and the like).

In addition, a plurality of touch switches may be provided to perform a plurality of functions when corresponding functions (back, movement to home, locking, and the like) are performed.

The touch operation sensing device of the examples described herein is not limited to the above-mentioned devices, and may be applied to devices such as mobile and wearable devices requiring switches. In addition, a touch switch of the examples described herein may be applied to implement a seamless design.

When the above-described embodiments are applied to a mobile device, a thinner, simpler, and tidier design may be implemented and, unlike an existing capacitive sensing method, a high-cost analog-to-digital converter (ADC) is not required. In addition, a touch member integrated with a housing may be used to implement a switch having dustproof and waterproof functions and to perform capacitive sensing more precisely, even in a humid environment.

As described above, sensing may be precisely performed using an impedance change of a touch member in response to a touch operation of the touch member, irrespective of locations of a housing and an inductor element disposed inside of the housing or a distance between the housing and the inductor element.

In addition, an existing physical key used in a mobile or wearable device may be eliminated to address fundamental defects such as wear, failure, and the like, and a connection portion, exposed outwardly of the housing such as a physical key, may be eliminated to be advantageous for dustproof and waterproof.

Furthermore, an existing physical key, suffering from a defect such as outward protrusion, may be eliminated to achieve a simpler design and to reduce manufacturing costs.