Display device, method of determining driving frequency, and method of driving display device

Abstract

A display device, a method of determining a driving frequency, and a method of driving the display device are disclosed. The display device includes: a display panel configured to display an image; a display driving section configured to drive the display panel; a touch unit disposed on the display panel and including a driving electrode and a sensing electrode; a touch driving portion configured to transmit a touch driving signal to the driving electrode and receive a touch sensing signal from the sensing electrode; and a main processor configured to control the display driving portion and the touch driving portion, in which a driving frequency of the touch driving signal is determined based on a change amount of a touch capacitance due to an external input with respect to the touch capacitance between the driving electrode and the sensing electrode.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on and claims the benefit of priority from Korean Patent Application No. 10-2023-0138926 filed on October 17, 2023 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. Technical Field

[0003] One or more embodiments relate to a display device, a method of determining a driving frequency, and a method of driving the display device. Background Art

[0004] A touch panel is an input device for inputting a command by a user selecting an instruction displayed in a screen of an image display device using their hand or an object. To this end, a touch panel is provided in the image display device to convert a direct contact point with the user's hand or object into an electrical signal. Thus, the instruction selected at the direct contact point is accepted as an input signal. As the touch panel may replace other input devices such as a keyboard or a mouse, the scope of use of the touch panel is expanding.

[0005] Touch panel implementation methods may include a resistance method, a light sensing method, and an electrostatic capacitance method. In a touch panel using the electrostatic capacitance method, a touch position may be determined by detecting a capacitance change that occurs when a user's hand or an object touches a position. Summary of the invention

[0006] One or more embodiments include a method of determining a driving frequency for preventing a touch failure in a low temperature environment, a display device, and a method of driving a display device. However, this is an example and the scope of the present disclosure is not limited thereto.

[0007] Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the embodiments presented in the disclosure.

[0008] According to one or more embodiments, a display device includes: a display panel configured to display an image; a display driving part configured to drive the display panel; a touch unit disposed on the display panel and including a driving electrode and a sensing electrode; a touch driving part configured to send a touch driving signal to the driving electrode and receive a touch sensing signal from the sensing electrode; and a main processor configured to control the display driving part and the touch driving part, wherein a driving frequency of the touch driving signal is determined based on an amount of change in touch capacitance caused by an external input relative to a touch capacitance between the driving electrode and the sensing electrode.

[0009] In an embodiment, the driving frequency may be determined within a frequency range in which a ratio of the amount of change in touch capacitance to the touch capacitance is greater than or equal to a preset ratio.

[0010] In an embodiment, the preset ratio may be 8.6%.

[0011] In an embodiment, the driving frequency may be about 200 kHz to about 465 kHz.

[0012] In an embodiment, the driving frequency may be determined as a frequency that is the same as or less than the frequency at which the ratio of the change in touch capacitance to the touch capacitance corresponds to a preset ratio.

[0013] In an embodiment, the touch unit may be of an electrostatic capacitance type.

[0014] In an embodiment, the touch unit may be of a mutual electrostatic capacitance type.

[0015] In an embodiment, the touch driving part may be further configured to apply a touch driving signal having a driving frequency to the touch unit in response to a control signal received from the main processor.

[0016] In an embodiment, the touch driving part may be further configured to calculate coordinate information of an external input based on a touch sensing signal received from the touch unit and provide a coordinate signal having the coordinate information to the main processor.

[0017] According to one or more embodiments, a method for determining a driving frequency, wherein the method determines the driving frequency of a touch driving signal in a display device including a display panel and a touch unit, the touch driving signal being sent to the touch unit, the method comprising: obtaining data about a touch capacitance between a driving electrode and a sensing electrode across a frequency range, the driving electrode and the sensing electrode being included in the touch unit; obtaining data about an amount of change in the touch capacitance when an external input is applied to the touch unit for each frequency; and determining the driving frequency of the touch driving signal based on a ratio of the amount of change in the touch capacitance to the touch capacitance.

[0018] In an embodiment, the driving frequency may be determined within a frequency range in which a ratio of the amount of change in touch capacitance to the touch capacitance is greater than or equal to a preset ratio.

[0019] In an embodiment, the preset ratio may be 8.6%.

[0020] In an embodiment, the driving frequency may be about 200 kHz to about 465 kHz.

[0021] In an embodiment, the driving frequency may be determined as a frequency that is the same as or less than the frequency at which the ratio of the change in touch capacitance to the touch capacitance corresponds to a preset ratio.

[0022] In an embodiment, the touch unit may be of an electrostatic capacitance type.

[0023] In an embodiment, the touch unit may be of a mutual electrostatic capacitance type.

[0024] According to one or more embodiments, a method for driving a display device includes a display panel and a touch unit, the method including: obtaining data about touch capacitance between a driving electrode and a sensing electrode across a frequency range, the driving electrode and the sensing electrode being included in the touch unit; obtaining data about an amount of change in the touch capacitance when an external input is applied to the touch unit for each frequency; determining a driving frequency of a touch drive signal sent to the touch unit based on a ratio of the amount of change in the touch capacitance to the touch capacitance; and sending the touch drive signal having the driving frequency to the touch unit.

[0025] In an embodiment, the driving frequency may be determined within a frequency range in which a ratio of the amount of change in touch capacitance to the touch capacitance is greater than or equal to a preset ratio.

[0026] In an embodiment, the driving frequency may be determined as a frequency that is the same as or less than the frequency at which the ratio of the change in touch capacitance to the touch capacitance corresponds to a preset ratio.

[0027] In an embodiment, the touch unit may be of an electrostatic capacitance type. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent from the following description in conjunction with the accompanying drawings, in which:

[0029] Figure 1 is a schematic exploded perspective view of a display device according to an embodiment;

[0030] Figure 2 is a block diagram for describing the operation of the display device according to the embodiment;

[0031] Figure 3 yes Figure 1 A schematic plan view of a touch unit of a display device;

[0032] Figure 4A According to the embodiment Figure 3 A schematic enlarged plan view of a region A of a touch sensor in a touch unit;

[0033] Figure 4B is a view for describing an operation principle of a touch sensor in a display device according to an embodiment;

[0034] Figure 5 is a schematic cross-sectional view of a portion of a display device according to an embodiment;

[0035] Figure 6 is a flow chart showing a method of determining a driving frequency of a driving signal sent to a touch unit in a display device;

[0036] Figure 7 is a graph showing data on touch capacitance versus frequency;

[0037] Figure 8 is a graph showing data on the amount of change in touch capacitance with respect to frequency; and

[0038] Fig. 9 : is a graph showing (amount of change in touch capacitance / touch capacitance) with respect to frequency. DETAILED DESCRIPTION

[0039] Reference will now be made in detail to embodiments, examples of which are shown in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Therefore, embodiments are described below only by reference to the accompanying drawings to explain aspects of the specification.

[0040] As used herein, the word "or" means a logical "OR," thus, unless the context indicates otherwise, the expression "A, B, or C" means "A and B and C," "A and B but not C," "A and C but not B," "B and C but not A," "A but not B and not C," "B but not A and not C," and "C but not A and not B." Throughout this disclosure, the expression "at least one of a, b, and c" means only a, only b, only c, both a and b, both a and c, both b and c, all a, b, and c, or variations thereof.

[0041] Various modifications may be applied to the present embodiment, and specific embodiments will be shown in the drawings and described in the detailed description section. The effects and features of the present embodiment and the method for implementing the present embodiment will become clearer with reference to the detailed description below in conjunction with the drawings. However, the present embodiment may be implemented in various forms and is not limited to the embodiments presented below.

[0042] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings, and in the description with reference to the accompanying drawings, the same or corresponding components are denoted by the same reference numerals and their redundant description is omitted.

[0043] In the following embodiments, it will be understood that although the terms "first", "second", etc. may be used herein to describe various elements, these elements should not be limited by these terms. These elements are only used to distinguish one element from another element.

[0044] In the following examples, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0045] In the following embodiments, it will also be understood that when the terms "comprises" and "includes" (and their variations, such as "comprising") are used in this specification, the presence of specified components or elements is specified, but does not exclude the presence or addition of one or more other components or elements thereof.

[0046] In the following embodiments, it will be understood that when an element such as a layer, film, region, or plate is referred to as being “on” another element, it can be directly on the other element or intervening elements may be present between the element and the other element.

[0047] For the convenience of explanation, the size of the elements in the drawings may be exaggerated. For example, since the size and thickness of the elements in the drawings are arbitrarily shown for the convenience of explanation, the following embodiments are not limited thereto.

[0048] When a certain embodiment can be implemented differently, a specific processing order can be performed differently from the described order. For example, two processes described successively can be performed substantially simultaneously, or in the reverse order of the described order.

[0049] In the following embodiments, it will be understood that when a layer, region, or component is referred to as being "connected to" another layer, region, or component, the layer, region, or component may be directly connected to the other layer, region, or component, or indirectly connected to the other layer, region, or component via an intervening layer, region, or component. For example, in the specification, when a layer, region, or component is referred to as being electrically connected to another layer, region, or component, the layer, region, or component can be directly electrically connected to the other layer, region, or component, or indirectly electrically connected to the other layer, region, or component via an intervening layer, region, or component.

[0050] Figure 1 is a schematic exploded perspective view of the display device 1 according to the embodiment.

[0051] Reference Figure 1, the display device 1 may include a display panel 100, a touch unit 200 disposed on the display panel 100, a polarization unit 300 disposed on the touch unit 200, and a cover window 400 disposed on the polarization unit 300. In an embodiment, an adhesive layer may be further provided between the display panel 100 and the touch unit 200, between the touch unit 200 and the polarization unit 300, and between the polarization unit 300 and the cover window 400. In addition, in another embodiment, the polarization unit 300 may be provided between the display panel 100 and the touch unit 200. Among them, one side of the display device 1 may be defined in a first direction (e.g., an x-axis direction), the other side of the display device 1 may be defined in a second direction (e.g., a y-axis direction), and the third direction (e.g., a z-axis direction) may be a direction perpendicular to both the first direction (e.g., the x-axis direction) and the second direction (e.g., the y-axis direction).

[0052] According to an embodiment, the touch unit 200 may be attached on the display panel 100 as a separate panel using an adhesive, or be provided integrally with the display panel 100 by being included in the display panel 100 .

[0053] Figure 2 is a block diagram for describing the operation of the display device 1 according to the embodiment.

[0054] Reference Figure 2 , the display device 1 may include a display panel 100, a touch unit 200, a display driving part 100D, a touch driving part 200D and a main processor 1D.

[0055] The display panel 100 may be a configuration for substantially generating an image. The display panel 100 may include an organic light emitting display layer, an inorganic light emitting display layer, an organic-inorganic light emitting display layer, a quantum dot display layer, a micro light emitting diode (LED) display layer, or a nano LED display layer.

[0056] The touch unit 200 may be provided on the display panel 100. The touch unit 200 may sense an external input 1000 applied from the outside. The external input 1000 may include all input devices capable of providing a capacitance change. For example, the touch unit 200 may sense not only an input of a passive type input device such as a user's body, but also an input of an active type input device providing a driving signal.

[0057] The main processor 1D may control the overall operation of the display device 1. For example, the main processor 1D may control the operation of the display driving part 100D and the touch driving part 200D. The main processor 1D may include at least one microprocessor and a graphic controller. The main processor 1D may be referred to as an application processor, a central processing unit, or a main driving part.

[0058] The display driving part 100D can drive the display panel 100. The display driving part 100D can receive the image data RGB and the control signal D-CS from the main processor 1D. The control signal D-CS may include various signals. For example, the control signal D-CS may include an input vertical synchronization signal, an input horizontal synchronization signal, a main clock, and a data enable signal. The display driving part 100D may generate a vertical synchronization signal and a horizontal synchronization signal based on the control signal D-CS to control the timing for providing a signal to the display panel 100.

[0059] The touch driving part 200D may drive the touch unit 200. The touch driving part 200D may receive a control signal I-CS from the main processor 1D. The control signal I-CS may include a mode determination signal determining a driving mode of the touch driving part 200D, and a clock signal.

[0060] The touch driving part 200D may apply the touch driving signal Tx to the touch unit 200 in response to the control signal I-CS received from the main processor 1D. The touch driving part 200D may apply the touch driving signal Tx having a preset driving frequency to the touch unit 200.

[0061] The touch driving part 200D may receive the touch sensing signal Rx from the touch unit 200 and convert the received touch sensing signal Rx into a digital signal. The touch driving part 200D may calculate the input coordinate information based on the touch sensing signal Rx received from the touch unit 200 and provide the coordinate signal I-SS having the coordinate information to the main processor 1D. The main processor 1D may perform an operation corresponding to the user input based on the coordinate signal I-SS. For example, the main processor 1D may operate the display driving part 100D so that a new application image is displayed in the display panel 100.

[0062] Figure 3 yes Figure 1 Schematic plan view of a touch unit 200 of a display device 1.

[0063] Reference Figure 3 , when an electric signal is formed according to the user's touch, the touch unit 200 is operated. In an embodiment, the touch unit 200 may be an electrostatic capacitance type. In an embodiment, the touch unit 200 may be a mutual electrostatic capacitance type.

[0064] The touch unit 200 may include a touch sensor TS including a touch electrode TCE. The touch unit 200 may include a plurality of touch electrodes TCE. The touch electrodes TCE may be electrically connected to each other through a connection pattern SP. First signal wiring SL1 and second signal wiring SL2 for connecting the touch electrode TCE to an external driving circuit through a pad portion PD may also be included in an outer region of the touch electrode TCE.

[0065] In an embodiment, when the touch unit 200 is provided as a separate panel, the touch electrode TCE and the connection pattern SP may be formed on a separate transparent substrate. In another embodiment, when the touch unit 200 is not provided as a separate panel but is directly formed on the display panel 100 (see Figure 2 ), the touch electrode TCE and the connection pattern SP may be formed on the encapsulation layer 30 (see Figure 5 )superior.

[0066] The touch electrodes TCE may include driving electrodes TE and sensing electrodes RE, the driving electrodes TE are connected to each other in a first direction (e.g., x-axis direction), and the sensing electrodes RE are connected to each other in a second direction (e.g., y-axis direction) perpendicular to the first direction (e.g., x-axis direction) and arranged to be distributed between the driving electrodes TE without overlapping with the driving electrodes TE. The driving electrodes TE and the sensing electrodes RE may be arranged to be alternately distributed and not overlap with each other.

[0067] A first direction (e.g., x-axis direction) in which the driving electrodes TE are connected to each other and a second direction (e.g., y-axis direction) in which the sensing electrodes RE are connected to each other are different directions that intersect each other, and for example, when the first direction (e.g., x-axis direction) is referred to as a row direction, the second direction (e.g., y-axis direction) can be referred to as a column direction.

[0068] In other words, the drive electrode TE may be arranged in plural along each row line, and the drive electrodes TE located at the same row line may be formed to be connected to each other in a first direction (e.g., x-axis direction) through a first connection pattern SP1 arranged in plural along the same row line. The form in which the drive electrodes TE are arranged in plural along the same row line and connected to each other may be referred to as a drive electrode line TEL. For example, one drive electrode line TEL may extend in a first direction (e.g., x-axis direction), and a plurality of drive electrode lines TEL may be arranged in a second direction (e.g., y-axis direction). The drive electrode lines TEL may be connected to the first signal wiring SL1 in units of lines. The first signal wiring SL1 may be a first signal wiring used to connect the first signal wiring SL1 to the first signal wiring SL1. Figure 2 The touch driving signal Tx applied by the touch driving part 200D is transmitted to the wiring of the driving electrode TE of the touch unit 200. In other words, the touch driving signal Tx may be applied to the driving electrode TE through the first signal wiring SL1.

[0069] The sensing electrodes RE may be arranged in plural along each column line, and the sensing electrodes RE located at the same column line may be formed to be connected to each other in a second direction (e.g., y-axis direction) intersecting the first direction through a second connection pattern SP2 arranged in plural along the same column line. The form in which the sensing electrodes RE are arranged in plural along the same column line and are connected to each other may be referred to as a sensing electrode line REL. For example, one sensing electrode line REL may extend in the second direction (e.g., y-axis direction), and a plurality of sensing electrode lines REL may be arranged in the first direction (e.g., x-axis direction). The sensing electrode lines REL may be connected to the second signal wiring SL2 in units of lines. The second signal wiring SL2 may be a wiring for connecting the reference Figure 2 The touch sensing signal Rx is transmitted to the wiring of the touch driving part 200D. In other words, the touch driving part 200D can be electrically connected to the sensing electrode RE through the second signal wiring SL2 to receive the touch sensing signal Rx from the sensing electrode RE. The touch sensing signal Rx can be a signal reflecting the amount of capacitance change between the driving electrode TE and the sensing electrode RE.

[0070] The touch electrode TCE is implemented to be transparent to have a certain transmittance or higher, thereby transmitting light from the display panel 100 (see FIG. 1 ) disposed under the touch electrode TCE. Figure 2 For example, the touch electrode TCE may include a transparent electrode layer formed of a transparent electrode material such as at least indium tin oxide (ITO).

[0071] The connection pattern SP may include a first connection pattern SP1 formed in a first direction (e.g., x-axis direction) and connecting the driving electrode TE in the first direction (e.g., x-axis direction), and a second connection pattern SP2 formed in a second direction (e.g., y-axis direction) and connecting the sensing electrode RE in the second direction (e.g., y-axis direction). An insulating layer for ensuring stability may be arranged between the first connection pattern SP1 and the second connection pattern SP2. The connection pattern SP may be formed of a transparent electrode material or an opaque low-resistance electrode material, and the thickness or width of the connection pattern SP may be adjusted to prevent visibility.

[0072] The signal wiring SL1 and the signal wiring SL2 are electrically connected to the driving electrodes TE and the sensing electrodes RE connected in a first direction (e.g., an x-axis direction) and a second direction (e.g., a y-axis direction) in units of lines, and can be connected to an external driving circuit (such as a reference MOSFET) through a pad portion PD. Figure 2The signal wiring SL1 and the signal wiring SL2 are located in the touch inactive area NAE defined outside the touch active area AE to avoid the touch active area AE of the transmitted image and have a wide range of material selection, so that they are formed not only of a transparent electrode material for forming the touch electrode TCE, but also of a low resistance material such as molybdenum (Mo), silver (Ag), titanium (Ti), copper (Cu), aluminum (Al), and molybdenum / aluminum / molybdenum (Mo / Al / Mo), etc.

[0073] although Figure 3 An embodiment in which the first connection pattern SP1 and the second connection pattern SP2 cross each other is shown, but the present disclosure is not limited thereto. For example, the first connection pattern SP1 may connect the drive electrodes TE to each other in the first direction without crossing the second connection pattern SP2 by bypassing along a path overlapping the adjacent sensing electrode RE. In this case, an insulating layer for ensuring stability may be arranged between the first connection pattern SP1 and the sensing electrode RE.

[0074] In the touch unit 200 configured as above, when an input device such as a finger approaches or contacts the touch unit 200, capacitance varied between the driving electrode TE and the sensing electrode RE is measured to detect a touch position.

[0075] The driving electrodes TE and the sensing electrodes RE may be respectively arranged in a structure in which a plurality of continuous polygons are connected in a rhombus shape, but the present disclosure is not limited thereto. The shape, size or arrangement form of the driving electrodes TE and the sensing electrodes RE may be changed differently depending on the shape, size or detection method of the display area where the pixels are arranged.

[0076] Figure 4A According to the embodiment Figure 3 FIG. 2 is a schematic enlarged plan view of a region A of a touch sensor TS in a touch unit 200 . Figure 4B is used to describe the display device 1 according to the embodiment (see Figure 1 ) in the touch sensor TS (see Figure 4A )'s operating principle.

[0077] The touch sensor TS can be used with reference Figure 3 The driving electrode lines TEL and the sensing electrode lines REL described above correspond to the portions where they intersect each other. Figure 4A As shown in FIG, the touch sensor TS may correspond to a portion where the first connection pattern SP1 and the second connection pattern SP2 cross. The touch sensor TS may correspond to a portion where the first connection pattern SP1 and the second connection pattern SP2 overlap.

[0078] Reference Figure 4A, the driving electrodes TE may be located on the left and right sides of the touch sensor TS, respectively, and the sensing electrodes RE may be located above and below the touch sensor TS, respectively. The touch sensor TS may detect the presence or absence of a touch through the driving electrodes TE and the sensing electrodes RE located around the touch sensor TS.

[0079] For details, refer to Figure 4B , the touch sensor TS may include a touch capacitor Ct. The touch capacitor Ct may include a first electrode ELtx and a second electrode ELrx. The first electrode ELtx may correspond to the driving electrode TE located on the left and right sides of the touch sensor TS, respectively, and the second electrode ELrx may correspond to the sensing electrode RE located above and below the touch sensor TS, respectively.

[0080] The touch capacitor Ct including the first electrode ELtx and the second electrode ELrx has a touch capacitance Cm. The touch capacitor Ct has a touch capacitance Cm by charging a charge between the drive electrode TE and the sensing electrode RE according to a touch drive signal Tx having a specific drive frequency. The touch capacitance Cm between the first electrode ELtx and the second electrode ELrx can be referred to as a mutual capacitance. In other words, the touch capacitor Ct can have a mutual touch capacitance Cm between the drive electrode TE and the sensing electrode RE. When no touch input is applied to the display device 1, the capacitance Cm remains unchanged and the existing value remains unchanged. When a touch input (e.g., a finger touch) is applied to the touch sensor TS or a point adjacent to the touch sensor TS, a capacitance is formed between the first electrode ELtx or the second electrode ELrx and the finger so that the capacitance Cm between the first electrode ELtx and the second electrode ELrx changes. Therefore, when a certain touch input is applied to the display device 1, the capacitance Cm changes, and the touch sensor TS can use the change in the capacitance Cm between the first electrode ELtx and the second electrode ELrx to detect the presence or absence of touch.

[0081] In the touch unit 200, the driving frequency of the touch driving signal Tx can be obtained by referring to the following: Figure 6 In an embodiment, the driving frequency of the touch driving signal Tx may be determined based on the data on the touch capacitance Cm and the data on the amount of change in the touch capacitance Cm.

[0082] Figure 5 is a schematic cross-sectional view of a portion of a display device 1 according to the embodiment. Figure 5 Shown is a reference Figure 1 The display panel 100 of the display device 1 and the cross section of the touch unit 200 on the display panel 100 are described. Figure 5, but the display device 1 may further include a polarization unit 300 and a cover window 400 above the touch unit 200, as shown in FIG. Figure 1 described.

[0083] Reference Figure 5 The display panel 100 may include a substrate 10 , a pixel circuit layer PCL on the substrate 10 , a light emitting element LED on the pixel circuit layer PCL, and an encapsulation layer 30 on the light emitting element LED.

[0084] The substrate 10 may include glass or a polymer resin. The polymer resin may include polyethersulfone, polyacrylate, polyetherimide, polyethylene naphthalate, polyethylene terephthalate, polyphenylene sulfide, polyarylate, polyimide, polycarbonate, or cellulose acetate propionate, etc. The substrate 10 including the polymer resin may be flexible (e.g., rollable or bendable). The substrate 10 may have a multilayer structure including a layer including the above-mentioned polymer resin and an inorganic layer (not shown).

[0085] The pixel circuit layer PCL may include a pixel circuit PC and an insulating layer, wherein the pixel circuit PC includes a thin film transistor TFT and a storage capacitor Cst. The pixel circuit layer PCL may include a barrier layer 11, a buffer layer 12, a first gate insulating layer 13, a second gate insulating layer 14, an interlayer insulating layer 15, and a planarizing insulating layer 17.

[0086] The buffer layer 12 may be disposed on the substrate 10 to reduce or prevent foreign matter, moisture, or external air from penetrating from below the substrate 10 and to provide a planarized surface for the semiconductor layer Act. The buffer layer 12 may include an inorganic material (such as an oxide or a nitride), an organic material, or an organic / inorganic composite, and have a single-layer structure or a multi-layer structure of an inorganic material and an organic material.

[0087] A barrier layer 11 for preventing external air from penetrating may be provided between the substrate 10 and the buffer layer 12. The barrier layer 11 and the buffer layer 12 may each include silicon oxide (SiO 2 ) or silicon nitride (SiN x ).

[0088] A pixel circuit PC including a thin film transistor TFT and a storage capacitor Cst may be disposed on the buffer layer 12. The thin film transistor TFT may include a semiconductor layer Act, a gate electrode GE, a drain electrode DE, and a source electrode SE.

[0089] The semiconductor layer Act may be disposed on the buffer layer 12 and may include polysilicon. In another embodiment, the semiconductor layer Act may include amorphous silicon. In another embodiment, the semiconductor layer Act may include an oxide of at least one material selected from indium (In), gallium (Ga), tin (Sn), zirconium (Zr), vanadium (V), hafnium (Hf), cadmium (Cd), germanium (Ge), chromium (Cr), Ti, and zinc (Zn). The semiconductor layer Act may include a channel region, a source region, and a drain region doped with impurities. The source region and the drain region may be arranged on opposite sides of the channel region.

[0090] A first gate insulating layer 13 may be provided to cover the semiconductor layer Act. The first gate insulating layer 13 may include an inorganic insulating material such as SiO 2 、SiN x 、Silicon Oxynitride (SiON), Aluminum Oxide (Al 2 O 3 ), titanium oxide (TiO 2 ), Tantalum Oxide (Ta 2 O 5 ), hafnium oxide (HfO 2 ) or zinc oxide ZnO x (It can be zinc oxide (ZnO) or zinc peroxide (ZnO 2 )) etc. The first gate insulating layer 13 may be a single layer or multiple layers including the above-mentioned inorganic insulating material.

[0091] The gate electrode GE may be disposed on the first gate insulating layer 13 to overlap the semiconductor layer Act. The gate electrode GE may include Mo, Al, Cu, Ti, etc. and may be formed as a single layer or multiple layers. As an example, the gate electrode GE may be a single layer of Mo.

[0092] A second gate insulating layer 14 may be provided to cover the gate electrode GE. The second gate insulating layer 14 may include an inorganic insulating material such as SiO 2 、SiN x 、SiON、Al 2 O 3 、TiO 2 、 2 O 5 , HfO 2 or ZnO x (It can be ZnO or ZnO 2 ) etc. The second gate insulating layer 14 may be a single layer or multiple layers including the above-mentioned inorganic insulating material.

[0093] The second capacitor electrode CE2 of the storage capacitor Cst may be disposed on the second gate insulating layer 14. The second capacitor electrode CE2 may overlap the gate electrode GE. The gate electrode GE and the second capacitor electrode CE2 may overlap each other (the second gate insulating layer 14 is located between the gate electrode GE and the second capacitor electrode CE2) to form the storage capacitor Cst. In other words, the gate electrode GE may serve as the first capacitor electrode CE1 of the storage capacitor Cst.

[0094] The second capacitor electrode CE2 may include Al, platinum (Pt), palladium (Pd), Ag, magnesium (Mg), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), calcium (Ca), Mo, Ti, tungsten (W) or Cu, and may be a single layer or a multilayer including the above materials.

[0095] The interlayer insulating layer 15 may be formed to cover the second capacitor electrode CE2. The interlayer insulating layer 15 may include SiO 2 、SiN x 、SiON、Al 2 O 3 、TiO 2 、 2 O 5 , HfO 2 or ZnO x (It can be ZnO or ZnO 2 ) etc. The interlayer insulating layer 15 may be a single layer or multiple layers including the above-mentioned inorganic insulating material.

[0096] The source electrode SE and the drain electrode DE may be disposed on the interlayer insulating layer 15. The source electrode SE and the drain electrode DE may include a conductive material including Mo, Al, Cu, and Ti, etc., and may be formed as a multilayer or a single layer including the above materials. As an example, the source electrode SE and the drain electrode DE may each have a multilayer structure of Ti / Al / Ti. In some embodiments, the source electrode SE or the drain electrode DE may be omitted. For example, thin film transistors TFT adjacent to each other may share a source region or a drain region of the semiconductor layer Act, and the source region or the drain region may be used as the source electrode SE or the drain electrode DE.

[0097] The planarization insulating layer 17 may be disposed to cover the source electrode SE and the drain electrode DE. The planarization insulating layer 17 may provide a flat base surface for the pixel electrode 21 disposed on the planarization insulating layer 17.

[0098] The planarization insulating layer 17 may include an organic material or an inorganic material and may have a single-layer structure or a multi-layer structure. The planarization insulating layer 17 may include a general polymer (such as polystyrene (PS)), benzocyclobutene (BCB), hexamethyldisiloxane (HMDSO), polymethylmethacrylate (PMMA), a polymer derivative having a phenol group, an acrylic polymer, an imide-based polymer (such as polyimide), an aryl ether-based polymer, an amide-based polymer, a fluorine-based polymer, a paraxylene-based polymer, or a vinyl alcohol-based polymer. The planarization insulating layer 17 may include an inorganic insulating material such as SiO 2 、SiN x 、SiON、Al 2 O 3 、TiO 2 、 2 O 5 , HfO 2 or (it can be ZnO or ZnO 2 ) etc. When the planarization insulating layer 17 is formed, in order to provide a flat upper surface after the planarization insulating layer 17 is formed, chemical mechanical polishing may be performed on the upper surface of the planarization insulating layer 17 .

[0099] The light emitting element LED may be disposed on the planarization insulating layer 17. The light emitting element LED may include a pixel electrode 21, an intermediate layer 22, and an opposing electrode 23.

[0100] The pixel electrode 21 may be disposed on the planarization insulating layer 17. The planarization insulating layer 17 may include a through hole for exposing any one of the source electrode SE and the drain electrode DE of the thin film transistor TFT, and the pixel electrode 21 may contact the source electrode SE or the drain electrode DE via the through hole to be electrically connected to the thin film transistor TFT.

[0101] The pixel electrode 21 may include a conductive oxide such as ITO, indium zinc oxide (IZO), zinc oxide (ZnO), indium oxide (In 2 O 3 ), indium gallium oxide (IGO) or aluminum zinc oxide (AZO). The pixel electrode 21 may include a reflective film, and the reflective film includes Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr or a compound thereof. For example, the pixel electrode 21 may have a layer composed of ITO, IZO, ZnO or In above or below the reflective film. 2 O 3 In this case, the pixel electrode 21 may have a stack structure of ITO / Ag / ITO.

[0102] The pixel defining layer 19 may cover the edge of the pixel electrode 21 on the planarization insulating layer 17 and may include a pixel opening OP for exposing a central portion of the pixel electrode 21. The emission area EA of the light emitting element LED (ie, the size and shape of the pixel) is defined by the pixel opening OP.

[0103] The pixel defining layer 19 may prevent arcing, etc., from being generated at the edge of the pixel electrode 21 by increasing the distance between the edge of the pixel electrode 21 and the counter electrode 23 located above the pixel electrode 21 .

[0104] The pixel defining layer 19 may be formed of an organic insulating material such as polyimide, polyamide, acrylic resin, benzocyclobutene, hexamethyldisiloxane (HMDSO), phenolic resin, etc., by a method such as spin coating.

[0105] In an embodiment, the pixel defining layer 19 may further include a light-blocking material. The light-blocking material may include a resin or a paste including carbon black, carbon nanotubes or black dye, metal (e.g., Ni, Al, Mo, and alloys thereof) particles, metal oxide (e.g., chromium oxide) particles, or metal nitride (e.g., chromium nitride) particles, etc. When the pixel defining layer 19 includes a light-blocking material, external light reflection caused by a metal structure arranged below the pixel defining layer 19 may be reduced.

[0106] The intermediate layer 22 may be disposed between the pixel electrode 21 and the counter electrode 23. The intermediate layer 22 may include a first functional layer 22a, an emission layer 22b, and a second functional layer 22c.

[0107] The emission layer 22b formed corresponding to the pixel electrode 21 is disposed within the pixel opening OP of the pixel defining layer 19. The emission layer 22b may include a high molecular weight material or a low molecular weight material and emit red light, green light, blue light, or white light.

[0108] The first and second functional layers 22a and 22c may be disposed under or over the emission layer 22b, respectively. In an embodiment, unlike the emission layer 22b patterned and arranged for each pixel, the first and second functional layers 22a and 22c may be integrally provided across the entire surface of the display area.

[0109] The first functional layer 22a may be a single layer or a multilayer. For example, when the first functional layer 22a is formed of a high molecular weight material, the first functional layer 22a as a hole transport layer having a single layer structure may include poly-(3,4)-ethylene-dihydroxythiophene (PEDOT) or polyaniline (PANI). When the first functional layer 22a is formed of a low molecular weight material, the first functional layer 22a may include a hole injection layer and a hole transport layer.

[0110] The second functional layer 22c may be selectively provided. For example, when the first functional layer 22a and the emission layer 22b are formed of a high molecular weight material, the second functional layer 22c may be formed. The second functional layer 22c may be a single layer or a multilayer. The second functional layer 22c may include an electron transport layer or an electron injection layer. In some embodiments, at least one of the hole injection layer, the hole transport layer, the electron transport layer, and the electron injection layer may be omitted.

[0111] The counter electrode 23 may include a relatively conductive material having a low work function. For example, the counter electrode 23 may include a (semi) transparent layer including Ag, Mg, Al, Ni, Cr, lithium (Li), Ca, or alloys thereof. Alternatively, the counter electrode 23 may also include a (semi) transparent layer including ITO, IZO, ZnO, or In 2 O 3 In an embodiment, the counter electrode 23 may include Ag and Mg.

[0112] In an embodiment, a capping layer (not shown) may be provided on the light emitting element LED. Based on the principle of constructive interference, the capping layer may improve the luminous efficiency of the light emitting element LED. The capping layer may include an organic capping layer including an organic material, an inorganic capping layer including an inorganic material, or a composite capping layer including an organic material and an inorganic material.

[0113] The encapsulation layer 30 may be disposed on the light emitting element LED. In an embodiment, the encapsulation layer 30 may include at least one inorganic encapsulation layer and at least one organic encapsulation layer. For example, the encapsulation layer 30 may include a first inorganic encapsulation layer 31 and a second inorganic encapsulation layer 33 and an organic encapsulation layer 32 disposed between the first inorganic encapsulation layer 31 and the second inorganic encapsulation layer 33.

[0114] The first inorganic encapsulating layer 31 and the second inorganic encapsulating layer 33 may each include one or more inorganic insulating materials. The inorganic insulating material may include Al 2 O 3 、TiO 2 、 2 O 5 , HfO 2 、ZnO x (It can be ZnO or ZnO 2 )、SiO 2 、SiN x and / or SiON. The first inorganic encapsulating layer 31 and the second inorganic encapsulating layer 33 may be formed by chemical vapor deposition.

[0115] The organic encapsulation layer 32 may also include polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyimide, polyvinyl sulfonate, polyoxymethylene, polyarylate, HMDSO, acrylic resin, or a combination thereof.

[0116] The encapsulation layer 30 may include the organic encapsulation layer 32 as described above and provide a more polarized substrate surface. Therefore, even when components of the touch unit 200 are formed through a continuous process, a defect rate may be reduced.

[0117] The touch unit 200 may be disposed on the display panel 100. The touch unit 200 may have a multi-layer structure. The touch unit 200 may include Figure 3 The driving electrode TE connected to the driving electrode TE Figure 3 The first signal wiring SL1, Figure 3 The sensing electrode RE connected to the sensing electrode RE Figure 3 The touch sensor TS included in the touch unit 200 may detect an external input by, for example, an electrostatic capacitance method.

[0118] The touch unit 200 may include a first touch insulating layer 210 , a first touch conductive layer MTL1 , a second touch insulating layer 220 , a second touch conductive layer MTL2 , and a third touch insulating layer 230 .

[0119] The first touch insulation layer 210 may be directly disposed on the encapsulation layer 30. The first touch insulation layer 210 may include an inorganic material or an organic material and may be provided in a single layer or a multi-layer.

[0120] The first touch insulation layer 210 may prevent damage to the encapsulation layer 30 and block an interference signal that may be generated during driving of the touch unit 200 .

[0121] For example, the first touch conductive layer MTL1 and the second touch conductive layer MTL2 may each have a single-layer structure or a stacked multilayer structure. The first touch conductive layer MTL1 and the second touch conductive layer MTL2 may each include a metal layer or a transparent conductive layer. The metal layer may include Mo, Ag, Ti, Cu, Al, and alloys thereof. The transparent conductive layer may include a transparent conductive oxide such as ITO, IZO, ZnO, and indium tin zinc oxide (ITZO). In addition, the transparent conductive layer may include a conductive polymer (such as PEDOT), a metal nanowire, and graphene.

[0122] The conductive layer having a multilayer structure may include a metal layer in the multilayer. The metal layer in the multilayer may have a three-layer structure of, for example, Ti / Al / Ti. The conductive layer having a multilayer structure may include at least one metal layer and at least one transparent conductive layer.

[0123] In another embodiment, the first touch conductive layer MTL1 and the second touch conductive layer MTL2 may each include a plurality of patterns. It is understood that although the first touch conductive layer MTL1 may include a first conductive pattern, the second touch conductive layer MTL2 may include a second conductive pattern. The first conductive pattern and the second conductive pattern may form a touch sensor.

[0124] The first touch conductive layer MTL1 and the second touch conductive layer MTL2 may be electrically connected to each other through a contact hole. In an embodiment, the first touch conductive layer MTL1 and the second touch conductive layer MTL2 may each have a mesh structure so that light emitted from the light emitting element LED may pass through the mesh structure. In this state, the first touch conductive layer MTL1 and the second touch conductive layer MTL2 may be arranged not to overlap with the emission area EA.

[0125] The second touch insulating layer 220 may include an organic material. The organic material may include at least one material selected from acrylic resin, methacrylic resin, polyisoprene, vinyl resin, epoxy resin, urethane resin, cellulose resin, and perylene resin. The second touch insulating layer 220 may also include an inorganic material. The inorganic material may include SiN x 、Aluminum nitride (AlN), zirconium nitride (ZrN), titanium nitride (TiN), hafnium nitride (HfN), tantalum nitride (TaN), SiO x 、Al 2 O 3 、TiO 2 , Tin Oxide (SnO 2 ), cerium oxide (CeO 2 ) and at least one material selected from SiON.

[0126] The third touch insulating layer 230 may be disposed on the second touch conductive layer MTL2. The third touch insulating layer 230 may have a single layer structure or a multi-layer structure. The third touch insulating layer 230 may include an organic material, an inorganic material, or a composite material.

[0127] In the embodiments, reference Figure 3 and Figure 5 , the first touch conductive layer MTL1 may include a second connection pattern SP2 connecting the sensing electrode RE. The second touch conductive layer MTL2 may include the sensing electrode RE, the driving electrode TE, and the first connection pattern SP1 connecting the driving electrode TE. In other words, the driving electrodes TE may be connected to each other through the first connection pattern SP1 formed on the same layer, and the sensing electrodes RE may be connected to each other through the second connection pattern SP2 formed on another layer through the contact hole. In an embodiment, the driving electrode TE and the first connection pattern SP1 may be formed integrally.

[0128] although Figure 5 An embodiment is shown in which the touch unit 200 is not provided as a separate panel but is directly formed on the display panel 100, but the present disclosure is not limited thereto. In another embodiment, the touch unit 200 may be provided as a separate functional module and coupled to the display panel 100 by an optically transparent adhesive or the like.

[0129] Figure 6 is to show that the determination is sent to the display device 1 (see Figure 1 ) in the touch unit 200 (see Figure 5 ) of the driving signal Tx (see Figure 2 )'s driving frequency.

[0130] Reference Figure 6 , also refer to Figure 1 , Figure 2 and Figure 5 , data of the touch capacitance Cm is obtained for each frequency (S10). The data of the touch capacitance Cm may be data of the capacitance between the driving electrode TE and the sensing electrode RE that cross each other.

[0131] The variation data for the touch capacitance Cm is obtained for each frequency (S20). The variation data for the touch capacitance Cm may be the variation data for the touch capacitance Cm between the driving electrode TE and the sensing electrode RE when the external input 1000 is applied to the touch unit 200.

[0132] The ratio of the amount of change in the touch capacitance Cm obtained for each frequency to the touch capacitance Cm is calculated ( S30 ).

[0133] The driving frequency of the touch drive signal Tx sent to the driving electrode TE is determined based on the ratio of the change amount of the touch capacitance Cm to the touch capacitance Cm according to the frequency (S40). In other words, the driving frequency can be determined based on the touch capacitance Cm and the change amount of the touch capacitance Cm. In detail, the driving frequency can be determined within a frequency range in which the ratio of the change amount of the touch capacitance Cm to the touch capacitance Cm has a value greater than or equal to the preset ratio. The maximum value that can be determined in the frequency range may be a frequency value when the ratio of the change amount of the touch capacitance Cm to the touch capacitance Cm corresponds to the preset ratio. For example, the driving frequency may be determined as a frequency that is the same as the frequency at which the ratio of the change amount of the touch capacitance Cm to the touch capacitance Cm corresponds to the preset ratio or less than the frequency at which the ratio of the change amount of the touch capacitance Cm to the touch capacitance Cm corresponds to the preset ratio. For example, the percentage value of the change amount of the touch capacitance Cm relative to the preset touch capacitance Cm may be 8.6%. For example, the maximum frequency value at which the percentage value of the change amount of the touch capacitance Cm relative to the touch capacitance Cm is 8.6% or more is 465 kHz, and the driving frequency range to be selected may be about 200 kHz to about 465 kHz.

[0134] In addition to detecting the capacitance change by touch, the touch sensor can also identify the situation where the capacitance change is too large due to the ambient temperature difference as a touch. Therefore, when the touch sensor detects the capacitance change caused by the temperature drop after touching in a low temperature environment, a ghost touch problem may occur. According to an embodiment, when the driving frequency is set within a frequency range where the ratio of the change in touch capacitance Cm to the touch capacitance Cm is greater than or equal to a preset ratio, the ghost touch problem can be prevented from being generated after touching in a low temperature environment.

[0135] The method of driving the display device 1 according to the embodiment may include: Figure 6 The method of determining the driving frequency described above determines the driving frequency and sends the touch driving signal Tx having the driving frequency to the touch unit 200. For example, the method of driving the display device 1 may include: obtaining data of the touch capacitance Cm between the driving electrode TE and the sensing electrode RE in the touch unit 200 for each frequency; obtaining data of the change amount of the touch capacitance Cm for each frequency when an external input is applied to the touch unit 200; determining the driving frequency of the touch driving signal Tx sent to the driving electrode TE based on the touch capacitance Cm and the data of the change amount of the touch capacitance Cm; and sending the touch driving signal Tx having the driving frequency to the touch unit 200.

[0136] Figure 7 is a graph showing data on touch capacitance Cm with respect to frequency. Figure 8: is a graph showing data on the amount of change dCm of the touch capacitance Cm with respect to the frequency. Fig. 9 : is a graph showing (amount of change dCm of touch capacitance Cm / touch capacitance Cm) with respect to frequency. Figures 7 to 9 is a diagram showing data for each frequency in a touch sensor according to an embodiment. Figure 7 shows the digital conversion value of the touch capacitance Cm according to the frequency, and Figure 8 A digital conversion value of a change amount dCm of the touch capacitance Cm according to the frequency is shown.

[0137] In the following description, reference is made to Figure 2 and Figures 7 to 9 A method of determining a driving frequency of a touch driving signal Tx is described.

[0138] Reference Figures 7 to 9 , the ratio of the change dCm of the touch capacitance Cm to the touch capacitance Cm is shown by obtaining data for each frequency in a specific touch capacitor. In the touch sensor according to the embodiment, when the ratio of the change dCm of the touch capacitance Cm to the touch capacitance Cm is 8.6% or more, the ghost touch phenomenon may not occur. Therefore, the touch drive signal Tx may have a driving frequency within a frequency range in which the ratio of the change dCm of the touch capacitance Cm to the touch capacitance Cm has a value of 8.6% or more. The frequency at which the ratio of the change dCm of the touch capacitance Cm to the touch capacitance Cm is 8.6% is 465kHz, which may be the maximum value of the driving frequency to be selected. Therefore, the driving frequency may be selected within a range of 465kHz or less than 465kHz. In addition, when the driving frequency is less than 200kHz, the driving signal may not be smoothly transmitted, so that the driving frequency may be determined within a range of about 200kHz to about 465kHz.

[0139] In the display device according to the embodiment, since an appropriate driving frequency is set based on the capacitance between the driving electrode and the sensing electrode and the capacitance change amount when receiving a touch, a touch failure in a low temperature environment can be prevented. Since the above effects are examples, the scope of the present disclosure is not limited by the above effects.

[0140] It should be understood that the embodiments described herein should be considered to be illustrative only and not for limiting purposes. The description of features or aspects in each embodiment should generally be considered to be applicable to other similar features or aspects in other embodiments. Although the embodiments have been described with reference to the accompanying drawings, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope defined by the appended claims.

Claims

1. A display device, wherein: The display device comprises: a display panel configured to display an image; A display driving part, configured to drive the display panel; A touch unit, disposed on the display panel and comprising a driving electrode and a sensing electrode; a touch driving section configured to send a touch driving signal to the driving electrodes and receive a touch sensing signal from the sensing electrodes; and a main processor configured to control the display driving part and the touch driving part, The driving frequency of the touch driving signal is determined based on a change in touch capacitance caused by an external input relative to a touch capacitance between the driving electrode and the sensing electrode.

2. The display device according to claim 1, wherein: The driving frequency is determined within a frequency range in which a ratio of the change amount of the touch capacitance to the touch capacitance is greater than or equal to a preset ratio.

3. The display device according to claim 2, wherein: The preset ratio is 8.6%.

4. The display device according to claim 3, wherein: The driving frequency is 200 kHz to 465 kHz.

5. The display device according to claim 1, wherein: The driving frequency is determined to be a frequency that is the same as or less than the frequency at which the ratio of the change in the touch capacitance to the touch capacitance corresponds to a preset ratio.

6. The display device according to claim 1, wherein: The touch unit is of an electrostatic capacitance type.

7. The display device according to claim 6, wherein: The touch unit is of a mutual electrostatic capacitance type.

8. The display device according to claim 1, wherein: The touch driving part is further configured to apply the touch driving signal having the driving frequency to the touch unit in response to a control signal received from the main processor.

9. The display device according to claim 1, wherein: The touch driving part is further configured to calculate coordinate information of the external input based on the touch sensing signal received from the touch unit, and provide a coordinate signal having the coordinate information to the main processor.

10. A method for determining a driving frequency, wherein: The method determines the driving frequency of a touch driving signal in a display device including a display panel and a touch unit, the touch driving signal being sent to the touch unit, the method comprising: obtaining data on touch capacitance between a driving electrode and a sensing electrode across a frequency range, the driving electrode and the sensing electrode being included in the touch unit; obtaining data on a change amount of touch capacitance when an external input is applied to the touch unit for each frequency; and A driving frequency of the touch driving signal is determined based on a ratio of the change amount of the touch capacitance to the touch capacitance.

11. The method according to claim 10, wherein: The driving frequency is determined within a frequency range in which the ratio of the change amount of the touch capacitance to the touch capacitance is greater than or equal to a preset ratio.

12. The method according to claim 11, wherein: The preset ratio is 8.6%.

13. The method according to claim 12, wherein: The driving frequency is 200 kHz to 465 kHz.

14. The method according to claim 10, wherein: The driving frequency is determined to be a frequency that is the same as or less than the frequency at which the ratio of the change in the touch capacitance to the touch capacitance corresponds to a preset ratio.

15. The method according to claim 10, wherein: The touch unit is of an electrostatic capacitance type.

16. The method according to claim 15, wherein: The touch unit is of a mutual electrostatic capacitance type.

17. A method for driving a display device, wherein: The display device includes a display panel and a touch unit, and the method includes: obtaining data on touch capacitance between a driving electrode and a sensing electrode across a frequency range, the driving electrode and the sensing electrode being included in the touch unit; obtaining data regarding an amount of change in touch capacitance when an external input is applied to the touch unit for each frequency; determining a driving frequency of a touch driving signal transmitted to the touch unit based on a ratio of the change amount of the touch capacitance to the touch capacitance; and The touch driving signal having the driving frequency is transmitted to the touch unit.

18. The method according to claim 17, wherein: The driving frequency is determined within a frequency range in which the ratio of the change amount of the touch capacitance to the touch capacitance is greater than or equal to a preset ratio.

19. The method according to claim 17, wherein: The driving frequency is determined to be a frequency that is the same as or less than the frequency at which the ratio of the change in the touch capacitance to the touch capacitance corresponds to a preset ratio.

20. The method according to claim 17, wherein: The touch unit is of an electrostatic capacitance type.

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