WO2023177109A1 - Touch sensor and image display device comprising same - Google Patents

Abstract

Provided according to embodiments of the present invention are a touch sensor and an image display device comprising same. The touch sensor comprises: a first electrode layer including first sensing lines; an interlayer insulating layer; and a second electrode layer opposite to the first electrode layer with the interlayer insulating layer interposed therebetween. The second electrode layer includes: second sensing lines crossing the first sensing lines in a planar direction; and floating electrodes arranged between the respective second sensing lines in the planar direction.

Description

Touch sensor and image display device including same

The present invention relates to a touch sensor and an image display device including the same. More specifically, it relates to a touch sensor including patterned sensing electrodes and an image display device including the same.

As information technology has recently developed, demands for the display field are also being presented in various forms. For example, various flat panel display devices with features such as thinner, lighter, and lower power consumption, such as liquid crystal display devices and plasma display devices, Electro Luminescent Display devices and Organic Light-Emitting Diode Display devices are being researched.

Meanwhile, a touch panel or touch sensor, which is an input device attached to the display device and allows the user to input commands by selecting the instructions displayed on the screen with a person's hand or an object, is combined with the display device to provide an image display function and Electronic devices with information input functions are being developed. For example, as in Korea Patent Publication No. 2014-0092366, a touch screen panel in which a touch sensor is combined with various image display devices is being developed.

In addition, as various sensors, such as fingerprint sensors, have been expanded in recent display devices, a sensor design capable of higher-resolution sensing is needed in a touch sensor capable of implementing fingerprint sensing. Accordingly, the spacing or pitch of the sensing electrodes may be reduced compared to a typical touch sensor.

For example, in the case of a fingerprint sensor, signal recognition or interpretation can be implemented based on the difference in capacitance between the ridges and valleys of the fingerprint. Therefore, an electrode design that can increase the capacitance difference is needed to increase fingerprint sensing with higher resolution at a reduced electrode pitch.

One object of the present invention is to provide a touch sensor with improved resolution and electrical characteristics.

One object of the present invention is to provide an image display device including a touch sensor with improved resolution and electrical characteristics.

1. A first electrode layer including first sensing lines; Interlayer insulating layer; and second sensing lines facing the first electrode layer with the interlayer insulating layer interposed therebetween and intersecting the first sensing lines in a plane direction. and a second electrode layer including floating electrodes arranged between the second sensing lines in the planar direction, wherein the width of the floating electrode is greater than the line width of the second sensing line and is larger than the line width of the first sensing line. A touch sensor that is small and has a line width of the first sensing line of 25㎛ to 75㎛.

2. The touch sensor of 1 above, wherein the line width of the second sensing line is 5㎛ to 20㎛.

3. The touch sensor of 2 above, wherein the width of the floating electrode is 5㎛ to 50㎛.

4. The touch sensor of 1 above, wherein the floating electrodes and the second sensing lines are located at the same level.

5. The touch sensor according to 1 above, wherein the plurality of floating electrodes form a floating electrode row, and the floating electrode row is disposed in every space between the neighboring second sensing lines.

6. The touch sensor according to 5 above, wherein one floating electrode row is disposed between the neighboring second sensing lines.

7. In 1 above, a touch sensor provided as a fingerprint sensor.

8. The touch sensor according to 7 above, wherein the capacitance difference between the valley of the fingerprint and the ridge of the fingerprint is 0.48 fF or more.

9. The touch sensor according to 8 above, wherein the second electrode layer is disposed toward the fingerprint input surface.

10. Window board; and a touch sensor according to the above-described embodiments laminated on one surface of the window substrate.

11. Display panel; and an image display device stacked on the display panel and including a touch sensor according to the above-described embodiments.

A touch sensor according to embodiments of the present invention includes first and second sensing lines that intersect each other, and floating electrodes may be arranged between the second sensing lines. A fringe field is induced toward the surface of the touch sensor by the floating electrodes, and the capacitance difference within the touch sensor may increase. Therefore, a high-resolution touch sensor capable of fingerprint sensing can be efficiently implemented.

In some embodiments, the line width of the second sensing line may be smaller than the line width of the first sensing line, and the width of the floating electrode may be larger than the line width of the second sensing line. Accordingly, the induction of the fringe field into the second sensing line through the floating electrode can be promoted, and capacitance/charge loss through the side of the second sensing line can also be reduced.

1 is a schematic cross-sectional view showing a touch sensor according to example embodiments.

2 and 3 are schematic plan views showing a first electrode layer and a second electrode layer, respectively, according to example embodiments.

Figure 4 is a schematic cross-sectional view showing field formation in a touch sensor of a comparative example.

Figure 5 is a schematic cross-sectional view showing field formation in a touch sensor according to example embodiments.

Figure 6 is a schematic diagram showing a window stack and an image display device according to example embodiments.

Embodiments of the present invention provide a touch sensor that includes first and second electrode layers of different structures/shapes and provides high-resolution fingerprint sensing. Additionally, an image display device including the touch sensor is provided.

With reference to the drawings below, embodiments of the present invention will be described in more detail. However, the following drawings attached to this specification illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of the present invention along with the contents of the above-described invention, so the present invention is described in such drawings. It should not be interpreted as limited to the specifics.

1 is a schematic cross-sectional view showing a touch sensor according to example embodiments. 2 and 3 are schematic plan views showing a first electrode layer and a second electrode layer, respectively, according to example embodiments.

The term "touch sensor" used in this application is used to encompass a sensor that inputs a command or generates a signal according to the touch of the user's finger or tool, and a sensor that generates a signal by recognizing the shape of the fingerprint of the finger. .

Referring to FIGS. 1 to 3 , the touch sensor 100 may include a first electrode layer 110 and a second electrode layer 120 facing each other with an interlayer insulating layer 105 therebetween.

The interlayer insulating layer 105 may be provided as a dielectric layer that generates mutual capacitance (Cm) between the first electrode layer 110 and the second electrode layer 120. According to example embodiments, the interlayer insulating layer 105 may include an organic polymer material in consideration of dielectric constant and flexibility for application to an image display device.

For example, the interlayer insulating layer 105 is made of cyclic olefin polymer (COP), polyethylene terephthalate (PET), polyacrylate (PAR), polyetherimide (PEI), polyethylene naphthalate (PEN), and polyphenylene sulfide. (PPS), polyallylate, polyimide (PI), cellulose acetate propionate (CAP), polyethersulfone (PES), cellulose triacetate (TAC), polycarbonate (PC), cyclic olefin copolymer (COC), polymethyl methacrylate (PMMA), etc. These may be used alone or in combination of two or more.

In a preferred embodiment, in terms of dielectric constant and flexibility described above, the interlayer insulating layer 105 may be formed of a polyimide (PI) layer.

The first electrode layer 110 may include a plurality of first sensing lines 115. As shown in FIG. 2, the first sensing line 115 may extend in a first direction parallel to the upper surface of the interlayer insulating layer 105. A plurality of first sensing lines 115 may be arranged along a second direction that intersects the first direction and is parallel to the top surface of the interlayer insulating layer 105. The first direction and the second direction may be perpendicular to each other.

In some embodiments, the line width (eg, width in the second direction) W1 of the first sensing line 115 may range from 25 μm to 75 μm. Preferably, the line width W1 of the first sensing line 115 may be in the range of 30 μm to 50 μm.

The second electrode layer 120 may include a plurality of second sensing lines 125 and floating electrodes 127.

As shown in FIG. 3, the second sensing line 125 may extend in the second direction. A plurality of second sensing lines 125 may be arranged along the second direction. Accordingly, the first sensing lines 115 and the second sensing lines 125 intersect each other with the interlayer insulating layer 105 in between, and coordinate information of the input position can be generated.

The floating electrodes 127 are arranged on the upper surface of the interlayer insulating layer 105 and may be located on the same layer or at the same level as the second sensing lines 125. According to example embodiments, the floating electrodes 127 may be arranged between the second sensing lines 125 in a planar direction.

For example, a plurality of floating electrodes 127 may be arranged in the second direction to form a floating electrode row. A plurality of floating electrode rows may be disposed between neighboring second sensing lines 125 .

The floating electrodes 127 are physically spaced apart from the second sensing lines 125 and may have an island pattern shape between neighboring second sensing lines 125.

In example embodiments, as shown in FIG. 3, the floating electrode 127 may have a rectangular shape, for example, may be formed in a square pattern.

In some embodiments, the shape of the floating electrode 127 may be appropriately changed to a polygon such as a pentagon or hexagon, a circle, or an oval.

According to example embodiments, the line width W2 (e.g., width in the first direction) of the second sensing line 125 may be smaller than the line width W1 of the first sensing line 115. . For example, the line width W2 of the second sensing line 125 may be in the range of 5 μm to 20 μm. Preferably, the line width W2 of the second sensing line 125 may be in the range of 5㎛ to 15㎛.

According to example embodiments, the width W3 (eg, width in the first direction) of the floating electrode 127 may be larger than the line width W2 of the second sensing line 125 . In some embodiments, the width W3 of the floating electrode 127 may be greater than the line width W2 of the second sensing line 125 and smaller than the line width W1 of the first sensing line 115.

According to exemplary embodiments, when the floating electrode 127 has a square shape, both the horizontal and vertical lengths of the floating electrode 127 are larger than the line width W2 of the second sensing line 125, and the first It may be smaller than the line width W1 of the sensing line 115.

For example, the width W3 of the floating electrode 127 may be in the range of 5㎛ to 50㎛. Preferably, the width W3 of the floating electrode 127 may range from 10 ㎛ to 50 ㎛, 15 ㎛ to 30 ㎛, or 15 ㎛ to 25 ㎛.

As shown in FIG. 3 , a plurality of floating electrodes 127 may be arranged along the second direction between neighboring second sensing lines 125 to form a floating electrode row. In a preferred embodiment, one floating electrode row may be disposed in each space between neighboring second sensing lines 125. Accordingly, uniform capacitance characteristics can be implemented over the entire area of the touch sensor.

The first electrode layer 110 and the second electrode layer 120 may include a low-resistance metal or alloy in consideration of high-resolution fingerprint sensing. For example, the first electrode layer 110 and the second electrode layer 120 are silver (Ag), gold (Au), copper (Cu), aluminum (Al), platinum (Pt), palladium (Pd), chromium ( Cr), titanium (Ti), tungsten (W), niobium (Nb), tantalum (Ta), vanadium (V), iron (Fe), manganese (Mn), cobalt (Co), nickel (Ni), zinc ( Zn), molybdenum (Mo), tin (Sn), calcium (Ca) or an alloy containing at least one of these (e.g., silver-palladium-copper (APC) or copper-calcium (CuCa)) You can. These may be used alone or in combination of two or more.

In some embodiments, the touch sensor 100 may further include a base layer 90. For example, the first electrode layer 110, the interlayer insulating layer 105, and the second electrode layer 120 may be sequentially disposed on the base layer 90.

The base layer 90 may include a material that is substantially the same as or similar to the polymer material mentioned in the interlayer insulating layer 105. In one embodiment, the base layer 90 may include an inorganic insulating material such as glass, silicon oxide, or silicon nitride.

A passivation layer 130 covering the second electrode layer 120 may be formed on the interlayer insulating layer 105. For example, the passivation layer 130 may be provided as a protective layer of the touch sensor 100 or a surface layer to which a touch input is applied. The passivation layer 130 may include an organic polymer material such as an acrylic polymer, a polyimide polymer, a siloxane polymer, an epoxy polymer, or an inorganic insulating material such as silicon oxide, silicon nitride, silicon oxynitride, or metal oxide. there is.

Figure 4 is a schematic cross-sectional view showing field formation in a touch sensor of a comparative example.

Referring to FIG. 4, in the comparative example, the first sensing line 115 and the second sensing line 125 may have substantially the same or similar size/arrangement structure except for the extension direction.

As indicated by the dashed arrows, a direct mutual capacitance (Cm) is created in the first sensing line 115 and the second sensing line 125, and as indicated by the thick curved arrows, some electric field is directed toward the surface of the touch sensor. A fringe field can be formed.

The fringe field induced toward the surface can be quickly discharged when a finger touch is input adjacent to the second electrode layer 120. Accordingly, the fringe field can improve the response speed and sensitivity of the touch sensor.

However, in the comparative example in which the first and second electrode layers 110 and 120 have the same line structure, a sufficient fringe field is not formed from the first electrode layer 110 to the touch sensor surface, and most of the mutual capacitance (Cm) can be created by direct Cm between the electrode layers indicated by the dashed arrows.

Additionally, as indicated by the thin curved arrow, Cm may be generated on the side of the second sensing line 125, resulting in loss of charge.

Figure 5 is a schematic cross-sectional view showing field formation in a touch sensor according to example embodiments.

Referring to FIG. 5 , according to the above-described exemplary embodiments, floating electrodes 127 may be arranged around the second sensing line 125 .

Direct Cm may also be generated between the floating electrode 127 and the first sensing line 115, as indicated by a dotted arrow. In addition, the floating electrode 127 interacts with the second sensing line 125 at the same level and interacts with the second sensing line 125, as indicated by the thick dotted arrow, through a difference in charge amount, to the fringe field adjacent to the touch sensor surface. can be guided towards.

Accordingly, the total amount of fringe fields directed to the finger touch surface of the touch sensor as a whole may be increased.

For example, the fringe field may increase the amount of discharge at points corresponding to valleys and ridges of the fingerprint, thereby increasing the difference in capacitance between the valleys and ridges. The capacitance difference can be expressed as Equation 1 below.

[Equation 1]

△Cm = |Cm(valley) - Cm(ridge)|

Therefore, a touch sensor capable of recognizing the shape of a fingerprint at high resolution can be more effectively implemented. Additionally, as the capacitance difference increases, the ability to distinguish between signals and noise also increases, allowing a high-resolution/high-reliability fingerprint recognition sensor to be implemented.

According to example embodiments, ΔCm of the touch sensor 100 may be 0.48fF or more. In a preferred embodiment, △Cm of the touch sensor 100 may be 0.5fF or more, and fingerprint sensing with higher resolution and higher reliability can be implemented.

As described above, the line width of the second sensing line 125 can be relatively narrowed, and the width of the floating electrode 127 can be increased. Accordingly, the generation of a field on the side of the second sensing line 125 that causes loss of charge can be suppressed, while the generation of a fringe field can be promoted.

Figure 6 is a schematic diagram showing a window stack and an image display device according to example embodiments.

Referring to FIG. 6 , the window stack 250 may include a window substrate 230, a polarizing layer 210, and a touch sensor 200 according to the above-described exemplary embodiments.

The window substrate 230 includes, for example, thin glass (eg, UTG) or a hard coating film, and in one embodiment, a light blocking pattern 235 is formed on the periphery of one side of the window substrate 230. can be formed. The light blocking pattern 235 may include, for example, a color printing pattern and may have a single-layer or multi-layer structure. The bezel portion or non-display area of the image display device may be defined by the light blocking pattern 235.

The polarizing layer 210 may include a coated polarizer or a polarizing plate. The coated polarizer may include a liquid crystal coating layer containing a polymerizable liquid crystal compound and a dichroic dye. In this case, the polarizing layer 210 may further include an alignment film to provide alignment to the liquid crystal coating layer.

For example, the polarizing plate may include a polyvinyl alcohol-based polarizer and a protective film attached to at least one side of the polyvinyl alcohol-based polarizer.

The polarizing layer 210 may be directly bonded to the one surface of the window substrate 230 or may be attached through the first point adhesive layer 220.

The touch sensor 200 may be included in the window laminate 250 in the form of a film or panel. In one embodiment, the touch sensor 200 may be coupled to the polarization layer 210 through the second point adhesive layer 225.

As shown in FIG. 6, the window substrate 230, the polarization layer 210, and the touch sensor 200 may be arranged in that order from the user's viewing side. In this case, since the electrode layer of the touch sensor 200 is disposed below the polarization layer 210, the electrode visibility phenomenon can be more effectively prevented.

In one embodiment, the touch sensor 200 may be directly transferred onto the window substrate 230 or the polarizing layer 210. In one embodiment, the window substrate 230, the touch sensor 200, and the polarizing layer 210 may be arranged in that order from the user's viewing side.

The touch sensor 200 may include a high-resolution fingerprint sensor according to the exemplary embodiments described above. In some embodiments, the touch sensor 200 may also include a low-resolution touch sensor that recognizes coordinate information depending on the presence or absence of a general touch input. For example, the low-resolution touch sensor includes sensing unit electrodes, and the width of the sensing unit electrode may be 1 mm or more, 2 mm or more, 3 mm or more, or 4 mm or more.

Sensing The high-resolution fingerprint sensor and the low-resolution touch sensor may be placed together at the same level, or may be placed separately on different floors.

The image display device may include a display panel 360 and the window stack 250 described above coupled to the display panel 360.

The display panel 360 may include a pixel electrode 310, a pixel defining film 320, a display layer 330, an opposing electrode 340, and an encapsulation layer 350 disposed on the panel substrate 300. You can.

A pixel circuit including a thin film transistor (TFT) is formed on the panel substrate 300, and an insulating film covering the pixel circuit may be formed. The pixel electrode 310 may be electrically connected to, for example, a drain electrode of a TFT on the insulating film.

The pixel defining layer 320 may be formed on the insulating layer to expose the pixel electrode 310 to define the pixel area. A display layer 330 is formed on the pixel electrode 310, and the display layer 330 may include, for example, a liquid crystal layer or an organic light-emitting layer.

An opposing electrode 340 may be disposed on the pixel defining layer 320 and the display layer 330. The counter electrode 340 may be provided as a common electrode or cathode of an image display device, for example. An encapsulation layer 350 for protecting the display panel 360 may be stacked on the counter electrode 340 .

In some embodiments, the display panel 360 and the window laminate 250 may be coupled through a point adhesive layer 260. For example, the thickness of the point adhesive layer 260 may be greater than the thickness of each of the first and second point adhesive layers 220 and 225, and the viscoelasticity at -20 to 80 ^o C may be about 0.2 MPa or less. In this case, noise from the display panel 360 can be shielded, and damage to the window laminate 250 can be suppressed by relieving interfacial stress during bending. In one embodiment, the viscoelasticity may be about 0.01 to 0.15 MPa.

Hereinafter, experimental examples including preferred embodiments are presented to aid understanding of the present invention. However, these examples are only illustrative of the present invention and do not limit the scope of the appended claims, and do not limit the scope and technical idea of the present invention. It is obvious to those skilled in the art that various changes and modifications to the embodiments are possible within the scope, and it is natural that such changes and modifications fall within the scope of the appended patent claims.

Example 1-2

A touch sensor having the structure shown in Figure 1 was manufactured. Specifically, a first electrode layer having the structure shown in FIG. 2 and a second electrode layer having the structure shown in FIG. 3 were formed on the top and bottom surfaces of the interlayer insulating layer made of polyimide (PI) film, respectively.

The first electrode layer and the second electrode layer were formed of copper lines having the line widths listed in Table 1. The floating electrodes were formed in rectangular patterns with the width*height sizes listed in Table 1.

Comparative Example 1

A touch sensor having the same structure as Example 1 was manufactured, except that the first electrode layer and the second electrode layer each included sensing lines with a line width of 40 μm, and the floating electrodes were omitted.

Comparative Example 2-6

The first electrode layer and the second electrode layer were formed of copper lines having the line widths listed in Table 1. The floating electrodes were formed in rectangular patterns with the width*height sizes listed in Table 1.

	first electrode layer (1st sensing line) (㎛)	second electrode layer (2nd sensing line) (㎛)	floating electrode (width and length) (㎛*㎛)
Example 1	40	10	20*20
Example 2	40	10	15*15
Comparative Example 1	40	40	-
Comparative Example 2	40	10	20*10
Comparative Example 3	40	10	10*10
Comparative Example 4	40	10	5*5
Comparative Example 5	80	25	55*55
Comparative Example 6	20	3	4*4

Experiment example

Base Cm (total capacitance before touch input), Cm (valley), Cm (ridge) and △ through simulation results generated when a predetermined voltage is applied using the Q3d Extractor as an analysis tool using the touch sensors of the examples and comparative examples. Cm was obtained.

The evaluation results are shown in Table 2 below (unit: fF).

	base cm	Cm(valley)	Cm(ridge)	△Cm
Example 1	1.9	1.84	1.34	0.504
Example 2	1.87	1.75	1.25	0.504
Comparative Example 1	2.20	2.11	2.08	0.032
Comparative Example 2	1.90	1.80	1.44	0.360
Comparative Example 3	1.75	1.64	1.18	0.453
Comparative Example 4	1.68	1.42	1.07	0.344
Comparative Example 5	2.752	2.665	2.387	0.278
Comparative Example 6	0.091	0.082	0.077	0.005

Referring to Table 2, △Cm in the touch sensor of the example increased by more than 10 times compared to the touch sensor of Comparative Example 1 in which the floating electrode was omitted. Accordingly, it can be predicted that the fingerprint sensor recognition resolution can be significantly increased through the above-described embodiments.

In addition, in embodiments in which the line width increases in the order of the second sensing line, the floating electrode, and the first sensing line, an increased ΔCm exceeding 0.5 was secured.

In Comparative Examples 5 and 6, ΔCm decreased as the line widths of the first sensing line, the second sensing line, and/or the floating electrode were excessively increased or decreased.

Claims (11)

1. A first electrode layer including first sensing lines;

   Interlayer insulating layer; and

   Opposing the first electrode layer with the interlayer insulating layer interposed therebetween,

   second sensing lines intersecting the first sensing lines in a plane direction; and

   A second electrode layer including floating electrodes arranged between the second sensing lines in the planar direction,

   The width of the floating electrode is larger than the line width of the second sensing line and smaller than the line width of the first sensing line,

   A touch sensor wherein the line width of the first sensing line is 25㎛ to 75㎛.
2. The touch sensor according to claim 1, wherein the line width of the second sensing line is 5㎛ to 20㎛.
3. The touch sensor according to claim 2, wherein the floating electrode has a width of 5㎛ to 50㎛.
4. The touch sensor according to claim 1, wherein the floating electrodes and the second sensing lines are located at the same level.
5. The touch sensor according to claim 1, wherein the plurality of floating electrodes form a floating electrode row, and the floating electrode row is disposed between neighboring second sensing lines.
6. The touch sensor according to claim 5, wherein one floating electrode row is disposed between the neighboring second sensing lines.
7. The touch sensor according to claim 1, provided as a fingerprint sensor.
8. The touch sensor according to claim 7, wherein the capacitance difference between the valley of the fingerprint and the ridge of the fingerprint is 0.48 fF or more.
9. The touch sensor according to claim 8, wherein the second electrode layer is disposed toward the fingerprint input surface.
10. window board; and

    A window laminate comprising the touch sensor according to claim 1 laminated on one surface of the window substrate.
11. display panel; and

    An image display device stacked on the display panel and including the touch sensor according to claim 1.

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