Force sensor preventing malfunction due to component interference and display device including the same

A display device includes a display panel and a first force sensor. The first force sensor is disposed adjacent to a first edge of the display panel and extends along the first edge. The first force sensor includes a plurality of first sensing regions and a second sensing region disposed closer to the second end of the first force sensor than the first sensing regions. The first sensing regions are disposed closer to a first end of the first force sensor than the second sensing region, and the second sensing region. The second sensing region is disposed closer to a second end of the first force sensor than the first sensing regions. The second sensing region has a larger area than each of the first sensing regions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2018-0056273, filed on May 17, 2018, in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

Exemplary embodiments of the present disclosure relate to a force sensor and a display device including the same.

DISCUSSION OF THE RELATED ART

Electronic devices that provide images to a user, such as a smartphone, a tablet PC, a digital camera, a notebook computer, a navigation system, a smart television, etc., include a display device that displays images. The display device includes a display panel that generates and displays an image, as well as various input devices such as a touch panel that recognizes a touch input. Due to the convenience of using a touch input method, the touch panel is replacing existing physical input devices such as physical buttons.

In addition to utilization of a touch panel, research has been conducted to provide a force sensor in a display device and utilize the force sensor in place of existing physical buttons. However, the use of the force sensor may result in certain drawbacks, such as interference of the force sensor with other components of the display device.

SUMMARY

Exemplary embodiments of the present disclosure provide a force sensor which can prevent a malfunction due to interference with other components and that enables convenient input, as well as a display device including the force sensor.

According to an exemplary embodiment, a display device includes a display panel and a first force sensor. The first force sensor is disposed adjacent to a first edge of the display panel and extends along the first edge. The first force sensor comprises a plurality of first sensing regions and a second sensing region. The first sensing regions are disposed closer to a first end of the first force sensor than the second sensing region. The second sensing region is disposed closer to a second end of the first force sensor than the first sensing regions. The second sensing region has a wider area than each of the first sensing regions.

According to an exemplary embodiment, a display device includes a display panel and a first force sensor. The first force sensor is disposed adjacent to a first edge of the display panel, extends along the first edge, and has a recess disposed at an inner side of the first force sensor. The first force sensor includes a plurality of first sensing regions and a second sensing region. The recess is disposed between the first sensing regions and the second sensing region. The second sensing region has a larger area than each of the first sensing regions.

According to an exemplary embodiment, a force sensor includes a recess disposed at one side of the force sensor, a plurality of first sensing regions, and a second sensing region. The first sensing regions sense a first force. The second sensing region senses a second force. The recess is disposed between the first sensing regions and the second sensing region. The second sensing region has a larger area than each of the first sensing regions.

DETAILED DESCRIPTION

Exemplary embodiments will be described more fully hereinafter with reference to the accompanying drawings. Like reference numerals may refer to like elements throughout the accompanying drawings.

It will be understood that when a layer is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present.

FIG.1is a perspective view of a display device1according to an exemplary embodiment.FIG.2is an exploded perspective view of the display device1according to the exemplary embodiment ofFIG.1.FIG.3is a cross-sectional view taken along line III-III′ ofFIG.2.

Referring toFIGS.1through3, according to an exemplary embodiment, display device1includes a display panel30and force sensors100and200disposed near edges of the display panel30. The display device1may further include a window10disposed above the display panel30, a cover panel sheet40disposed below the display panel30, and a bracket50(or a middle mold frame) disposed below the cover panel sheet40.

Unless otherwise defined, the terms “above” and “upper surface” in a thickness direction, as used herein, denote a display surface side of the display panel30, and the terms “below” and “lower surface” in the thickness direction, as used herein, denote an opposite side of the display panel30from the display surface side. In addition, the terms “above (upper),” “below (lower),” “left,” and “right” in a planar direction refer to directions when a display surface placed in position viewed from above.

The display device1may have a substantially rectangular shape in plan view. For example, the display device1may have the shape of a rectangle with right-angled corners, or a rectangle with round corners in a plan view. The display device1may include long sides LS1and LS2and short sides SS1and SS2. The long sides LS1and LS2are relatively longer than the short sides SS1and SS2. In the rectangular display device1or members such as the display panel30included in the rectangular display device1, a long side located on a right side in plan view will be referred to as a first long side LS1, a long side located on a left side in a plan view will be referred to as a second long side LS2, a short side located on an upper side in a plan view will be referred to as a first short side SS1, and a short side located on a lower side in a plan view will be referred to as a second short side SS2. The long sides LS1and LS2of the display device1may be, but are not limited to, about 1.5 to about 2.5 times longer than the short sides SS1and SS2.

The display device1may include a first area DR1and a second area DR2lying in different planes. The first area DR1lies in a first plane. The second area DR2is connected to the first area DR1, and is bent or curved from the first area DR1. The second area DR2may lie in a second plane located at a predetermined crossing angle to the first plane or may have a curved surface. The second area DR2of the display device1is disposed around the first area DR1. The first area DR1of the display device1is used as a main display surface. Both the first area DR1and the second area DR2can be used as a display area of the display device1. A case in which the first area DR1of the display device1is a flat portion and the second area DR2is a curved portion will be described below as an example.

The second area DR2, which is the curved portion, may have a constant curvature or a varying curvature. The second area DR2may be connected to the first area DR1.

The second area DR2may be disposed at edges of the display device1. In an exemplary embodiment, the second area DR2may be disposed at both long edges (long sides LS1and LS2) of the display device1which face each other. Alternatively, the second area DR2may be disposed at one edge, at both short edges (short sides SS1and SS2), at three edges, or at all edges of the display device1.

The display panel30is a panel for displaying an image and may be, for example, an organic light emitting diode (OLED) display panel. In the following exemplary embodiments, a case in which an OLED display panel is applied as the display panel30will be described as an example. However, exemplary embodiments are not limited thereto, and other types of display panels such as, for example, a liquid crystal display (LCD) panel and an electrophoretic display panel may also be applied as the display panel30. A display flexible circuit board31may be coupled to the display panel30.

The display panel30includes a plurality of organic light emitting elements disposed on a substrate. The substrate may be a rigid substrate made of, for example, glass, quartz, etc., or may be a flexible substrate made of, for example, polyimide or other polymer resins. When a polyimide substrate is applied as the substrate, the display panel30can be bent, curved, folded, or rolled. In the drawings, the second short side SS2of the display panel30is bent. In this case, the display flexible circuit board31may be attached to a bending area BA of the display panel30.

The window10is disposed above the display panel30. The window10protects the display panel30and allows for the transmission of light emitted from the display panel30. The window10may be made of, for example, glass or transparent plastic.

The window10may be disposed such that it overlaps the display panel30and covers the entire surface of the display panel30. The window10may be larger than the display panel30. For example, the window10may protrude outward from the display panel30at both short sides SS1and SS2of the display device1. The window10may also protrude from the display panel30at both long sides LS1and LS2of the display device1. However, the protruding distance of the window10may be greater at both short sides SS1and SS2.

In exemplary embodiments, the display device1may further include a touch member20disposed between the display panel30and the window10. The touch member20may be of a rigid panel type, a flexible panel type, or a film type. The touch member20may have substantially the same size as the display panel30and may overlap the display panel30. In an exemplary embodiment, side surfaces of the touch member20may be aligned with side surfaces of the display panel30at all sides excluding the bent short side SS2of the display panel30. However, exemplary embodiments are not limited thereto. The display panel30and the touch member20, and the touch member20and the window10, may be bonded together by transparent bonding layers61and62such as, for example, optically clear adhesives (OCA) or optically clear resins (OCR). A touch flexible circuit board21may be coupled to the touch member20.

In exemplary embodiments, the touch member20can be omitted. In this case, the display panel30and the window10may be bonded together by an OCA or an OCR. In exemplary embodiments, the display panel30may include a touch electrode portion.

The cover panel sheet40and the force sensors100and200are disposed below the display panel30. The cover panel sheet40and the force sensors100and200may be attached to a lower surface of the display panel30by bonding layers71,72and73such as, for example, force-sensitive adhesive layers or adhesive layers.

The cover panel sheet40is disposed such that it overlaps a central portion of the display panel30. The cover panel sheet40has a size substantially similar to that of the display panel30, but may expose the lower surface of the display panel30by a predetermined width in the vicinity of both long sides LS1and LS2where the force sensors100and200are disposed.

The cover panel sheet40may perform a heat dissipating function, an electromagnetic wave shielding function, a pattern detection preventing function, a grounding function, a buffering function, a strength enhancing function, and/or a digitizing function. The cover panel sheet40may include a functional layer having at least one of the above functions. The functional layer may be provided in various forms such as, for example, a layer, a membrane, a film, a sheet, a plate, and a panel. The cover panel sheet40may include one functional layer or a plurality of functional layers. For example, the cover panel sheet40may include a buffer sheet, a graphite sheet, and a copper sheet stacked sequentially from top to bottom.

The force sensors100and200may be disposed such that they overlap at least one edge of the display panel30. A plurality of force sensors100and200may be provided. As illustrated in the drawings, the force sensors100and200may include a first force sensor100overlapping a first long edge (first long side LS1) of the display panel30and a second force sensor200overlapping a second long edge (second long side LS2) of the display panel30. The force sensors100and200may be disposed in the second area DR2(e.g., the curved portion) of the display device1. However, exemplary embodiments are not limited thereto. For example, in exemplary embodiments, the force sensors100and200may be disposed in an area other than the second area DR2.

The first and second force sensors100and200may respectively be attached to portions of the lower surface of the display panel30near both long edges (long sides LS1and LS2) of the display panel30exposed by the cover panel sheet40. In an exemplary embodiment, the force sensors100and200are disposed in the second area DR2of the display device1and are not disposed in the first area DR1. However, exemplary embodiments are not limited to this case. For example, in exemplary embodiments, the force sensors100and200may also be disposed in the second area DR2and extended in a width direction to part of the first area DR1.

Although the force sensors100and200are overlapped by the display panel30, an area of the display panel30which overlaps the force sensors100and200may be, in an exemplary embodiment, a non-display area around the display area. That is, in an exemplary embodiment, the force sensors100and200are overlapped by the non-display area of the display panel30. An outermost black matrix may be disposed in the non-display area of the display panel30around the display area. In addition, although the force sensors100and200and the touch member20overlap, an area of the touch member20which overlaps the force sensors100and200may be a peripheral area in which a touch electrode is not disposed.

In exemplary embodiments, the force sensors100and200and the cover panel sheet40do not overlap in the thickness direction. The force sensors100and200will be described in detail later.

The bracket50is disposed below the force sensors100and200and the cover panel sheet40. The bracket50may be, for example, a storage container or a protective container that houses other components. For example, the bracket50may house the window10, the touch member20, the display panel30, the force sensors100and200, and the cover panel sheet40.

The bracket50may include a bottom portion51and sidewalls52extending from sides of the bottom portion51.

The bottom portion51of the bracket50faces the force sensors100and200and the cover panel sheet40. The force sensors100and200and the cover panel sheet40may be attached to the bottom portion51of the bracket50by bonding layers81,82and83. The bonding layers81,82and83may be, for example, force-sensitive adhesive layers or adhesive layers. In an exemplary embodiment, the bonding layers82and83, which attach the force sensors100and200to the bottom portion51of the bracket50, may be waterproof tapes.

The sidewalls52of the bracket50face side surfaces of the touch member20, the display panel30, the force sensors100and200, and the cover panel sheet40. Upper ends of the sidewalls52of the bracket50face the window10. An outer surface of the bracket50may be aligned with an outer surface of the window10. The window10may be attached to the bracket50with, for example, a waterproof tape.

The bracket50may include a connect hole53, through which a display connector35(seeFIG.4) passes, near the first long edge (first long side LS1). The connect hole53may penetrate the bottom portion51of the bracket50in the thickness direction and may have, for example, a slit shape. The first force sensor100may have a recess NTH near the connect hole53of the bracket50. The recess NTH may have the shape of a notch, and thus may also be referred to herein as a notch-shaped recess NTH. This will be described in detail with reference toFIGS.4and5.

FIG.4is a bottom view of the display device1according to an exemplary embodiment.FIG.4illustrates the bottom shape of the display device1excluding the bracket50. InFIG.4, the display device1is turned upside down. Thus, the left and right sides are reversed, and the positions of the first long side LS1and the second long side LS2are also reversed.FIG.5is a perspective view illustrating the arrangement of the bracket50and the force sensors100and200according to an exemplary embodiment.

Referring toFIGS.4and5, the display flexible circuit board31is connected to the display connector35. The display flexible circuit board31is housed in the bracket50, and the display connector35comes out of the bracket50through the connect hole53so as to be connected to an external terminal. When the first force sensor100overlaps or physically contacts a space through which the display connector35comes out, there is a possibility that the first force sensor100will malfunction. Therefore, in exemplary embodiments, the first force sensor100includes the recess NTH at a corresponding position to avoid interfering with the display connector35. Since the first force sensor100is recessed outward due to the recess NTH, in exemplary embodiments, the first force sensor100does not overlap or physically contact the display connector35passing through the connect hole53. The recess NTH of the first force sensor100disposed in the bracket50may bypass the connect hole53in an outward direction.

The display connector35may be made of, for example, a flexible circuit board. Although the display flexible circuit board31and the display connector35are formed as separate members and connected to each other in the drawings, the display flexible circuit board31itself may also pass through the connect hole53in exemplary embodiments.

Unlike the first force sensor100, the second force sensor200may not include a notch-shaped recess. For example, in an exemplary embodiment, the first force sensor100includes the notch-shaped recess NTH, and the second force sensor200does not include the notch-shaped recess NTH.

The force sensors100and200will now be described in more detail.

FIG.6is an exploded perspective view of the first force sensor100according to an exemplary embodiment.FIG.7is a cross-sectional view taken along line VII-VII′ ofFIG.6.FIG.8is a graph illustrating the relationship between the electrical resistance of a force sensing layer122and a force. InFIGS.6through8, the structure and operation of the first force sensor100are described as an example. It is to be understood that the second force sensor200has substantially the same structure and operation as the first force sensor100, except for the presence of the recess NTH. Accordingly, for convenience of explanation, a duplicate description of the structure and operation of the second force sensor200will be omitted herein.

Referring toFIGS.6through8, the first force sensor100extends in one direction in a plane. A length of the first force sensor100in the extending direction is greater than a width of the first force sensor100. The width of the first force sensor100may be between about 2 mm and about 6 mm. The length of the first force sensor100may be substantially similar to the lengths of the long sides LS1and LS2of the display device1. The length of the first force sensor100may be, but is not limited to, about 80% to about 98% of the lengths of the long sides LS1and LS2of the display device1. In an exemplary embodiment, the length of the first force sensor100may be in the range of about 50 mm to about 300 mm or in the range of about 100 mm to about 150 mm.

The first force sensor100includes a first substrate110and a second substrate120facing each other. The first substrate110includes a first base111and an electrode layer112. The second substrate120includes a second base121and the force sensing layer122. The first substrate110and the second substrate120are bonded together by a bonding layer130. The first substrate110and the second substrate120may be, but are not limited to, films.

Each of the first base111and the second base121may include, for example, polyethylene, polyimide, polycarbonate, polysulfone, polyacrylate, polystyrene, polyvinyl chloride, polyvinyl alcohol, polynorbornene, or polyester. In an exemplary embodiment, each of the first base111and the second base121may be made of, for example, a polyethylene terephthalate (PET) film or a polyimide film.

The electrode layer112is disposed on a surface of the first base111. Here, the surface of the first base111is a surface facing the second base121. A thickness of the electrode layer112may be between about 2 um and about 8 um. For example, the thickness of the electrode layer112may be about 4 um in an exemplary embodiment. The electrode layer112includes a first electrode112TX and a second electrode112RX. The first electrode112TX may be, for example, a driving electrode, and the second electrode112RX may be, for example, a sensing electrode. The first electrode112TX and the second electrode112RX may be disposed adjacent to each other, but are spaced apart from each other so as not to short-circuit. For example, in an exemplary embodiment, the first electrode112TX and the second electrode112RX may be disposed adjacent to each other (e.g., directly adjacent to each other with no other components disposed therebetween) without contacting each other.

The first electrode112TX and the second electrode112RX may be disposed on the same layer. The first electrode112TX and the second electrode112RX may be made of the same material. For example, the first electrode112TX and the second electrode112RX may include a conductive material such as silver (Ag) or copper (Cu). The first electrode112TX and the second electrode112RX may be formed, for example, by a screen printing method.

In an exemplary embodiment, the first electrode112TX may be formed as a single piece along the direction in which the first force sensor100extends, and the second electrode112RX, which is separated from the first electrode112TX, may be formed as a single piece along the direction in which the first force sensor100extends.

The force sensing layer122is disposed on a surface of the second base121. Here, surface f the second base121is a surface facing the first base111. The force sensing layer122may include a force sensitive material. The force sensitive material may include metal nanoparticles such as, for example, nickel, aluminum, tin or copper, or may include carbon. The force sensitive material may be provided in a polymer resin in the form of, but not limited to, particles. As illustrated inFIG.8, the electrical resistance of the force sensing layer122decreases as the force increases. By using this characteristic, it is possible to sense whether the force has been applied, as well as the magnitude of the force.

For example, a surface of the force sensing layer122is in contact with or at least adjacent to surfaces of the first electrode112TX and the second electrode112RX. When force is applied to the first force sensor100, the surface of the force sensing layer122is brought into contact with the surfaces of the first electrode112TX and the second electrode112RX at a corresponding portion. Therefore, the first electrode112TX and the second electrode112RX may be physically connected by the force sensing layer122. The force sensing layer122lying between the first electrode112TX and the second electrode112RX may act as an electrical resistor.

When no force or little force is applied to the force sensing layer122, the force sensing layer122has a high resistance. In this case, even if a driving voltage is applied to the first electrode112TX, a current hardly flows to the second electrode112RX. On the other hand, when a large force is applied to the force sensing layer122, the resistance of the force sensing layer122is reduced, thus increasing the amount of current flowing between the first electrode112TX and the second electrode112RX.

Therefore, by sensing the amount of current or voltage at the second electrode112RX after applying a driving voltage to the first electrode112TX, it is possible to identify how much force has been applied to the force sensing layer122.

The thickness of the force sensing layer122may be, but is not limited to, a thickness that is thicker than the electrode layer112. For example, the thickness of the force sensing layer122may be between about 4 um and about 12 um. For example, the thickness of the force sensing layer122may be about 8 um.

The first force sensor100may further include the bonding layer130disposed between the first base111and the second base121. The bonding layer130bonds the first base111and the second base121. The bonding layer130may be disposed along the periphery of the first base111and the second base121. In an exemplary embodiment, the bonding layer130may completely surround the periphery of the first base111and the second base121, thus, sealing the first force sensor100. That is, the bonding layer130may serve as a gasket. Further, the bonding layer130may also serve as a spacer that maintains a constant gap between the first base111and the second base121. In exemplary embodiments, the bonding layer130does not overlap the electrode layer112and the force sensing layer122.

A thickness of the bonding layer130may be in the range of about 5 um to about 50 um, or in the range of about 12 um to about 30 um.

The bonding layer130may be made of a force-sensitive adhesive layer or an adhesive layer. The bonding layer130may first be attached to one of the surface of the first base111and the surface of the second base121, and then attached to the surface of the other base111or121in the process of assembling the first base111and the second base121. Alternatively, a bonding layer may be provided on each of the surface of the first base111and the surface of the second base121, and then the bonding layer of the first base111and the bonding layer of the second base121may be bonded together in the process of assembling the first base111and the second base121.

The first force sensor100may be placed in the display device1such that the first base111having the electrode layer112faces the display panel30. That is, the other surface (outer surface) of the first base111may be attached to the lower surface of the display panel30, and the other surface (outer surface) of the second base121may be attached to the bracket50. However, exemplary embodiments are not limited to this case. For example, in exemplary embodiments, the arrangement directions of the first base111and the second base121in the display device1may also be opposite to the directions described above.

FIG.9is a layout view of the first force sensor100and the second force sensor200according to an exemplary embodiment.

The arrangement of the first substrate110and the second substrate120of the first force sensor100is illustrated on the left side ofFIG.9, and the arrangement of a first substrate210and a second substrate220of the second force sensor200is illustrated on the right side ofFIG.9.

Referring toFIG.9, each of the first force sensor100and the second force sensor200includes a plurality of sensing regions SR1and SR2. The sensing regions SR1and SR2are regions capable of sensing forces. The sensing regions SR1and SR2may sense forces at their corresponding positions independently of each other. Similar to the first force sensor100, the second force sensor includes an electrode layer212.

The sensing regions SR1and SR2may be arranged in a longitudinal direction of each of the first force sensor100and the second force sensor200. In an exemplary embodiment, the sensing regions SR1and SR2may be arranged in one row. Neighboring sensing regions SR1and SR2may be arranged continuously. Alternatively, the neighboring sensing regions SR1and SR2may be spaced apart from each other. That is, a non-sensing region NSR may be disposed between the sensing regions SR1and SR2.

As shown inFIG.9, in an exemplary embodiment, the first force sensor100is disposed adjacent to a first edge of the display panel30and extends along the first edge. The first force sensor100includes a plurality of first sensing regions SR1disposed between a first end of the first force sensor100and a second end of the first force sensor100. The second sensing region SR2is disposed closer to the second end of the first force sensor100than the first sensing regions SR1, and has a wider area than each of the first sensing regions SR1.

In addition, in an exemplary embodiment, the second force sensor200is disposed adjacent to a second edge of the display panel30. The second edge faces the first edge, and the second force sensor200extends along the second edge. The second force sensor200includes a plurality of first sensing regions SR1disposed between a first end of the second force sensor200and a second end of the second force sensor200, and a second sensing region SR2disposed closer to the second end of the second force sensor200than the first sensing regions SR1included in the second force sensor200. The second sensing region SR2included in the second force sensor200has a wider area than each of the first sensing regions SR1included in the second force sensor200.

Further, as shown inFIG.9, in an exemplary embodiment, the first force sensor100includes the recess NTH disposed at an inner side of the first force sensor100. The first force sensor100includes a plurality of first sensing regions SR1disposed on a first side of the recess NTH and a second sensing region SR2disposed on a second side of the recess NTH. The second sensing region SR2disposed on the second side of the recess NTH has a wider area than each of the first sensing regions SR1disposed on the first side of the recess NTH. The first electrode112TX of the first force sensor100or a first electrode of the second force sensor200, the second electrode112RX of the first force sensor100or a second electrode of the second force sensor200, and the force sensing layer122or222, are disposed in each of the sensing regions SR1and SR2. The second electrode112RX of the first force sensor100or the second electrode of the second force sensor200serve as a sensing electrode that is a separate cell electrode disposed in each of the sensing regions SR1and SR2, and the first electrode112TX of the first force sensor100or the first electrode of the second force sensor200serve as a driving electrode and is a common electrode, all portions of which are electrically connected regardless of the sensing regions SR1and SR2. The force sensing layer122or222may also be patterned and disposed as a separate layer in each of the sensing regions SR1and SR2.

The sensing regions SR1and SR2may have different areas depending on their use. For example, the area of a second sensing region SR2(e.g., a squeezing sensing region) that senses a squeezing force may be larger than the area of a first sensing region SR1. (e.g., a pressing sensing region) used in place of a physical button. The second sensing region SR2has the same width as the first sensing region SR1, but may have a greater length (width in the extending direction of a force sensor) than the first sensing region SR1. The length of the second sensing region SR2may be about three to about fifteen times the length of the first sensing region SR1. For example, the length of the first sensing region SR1may be between about 4 mm and about 5 mm, and the length of the second sensing region SR2may be between about 30 mm and about 60 mm.

In an exemplary embodiment, a plurality of first sensing regions SR1may be arranged in a direction from an upper end toward a lower end of each of the first force sensor100and the second force sensor200, and one second sensing region SR2may be disposed near the lower end of each of the first force sensor100and the second force sensor200. The positions of the first sensing regions SR1and the second sensing region SR2in the first force sensor100may be distinguished based on the recess NTH. For example, the first sensing regions SR1may be disposed above the recess NTH, and the second sensing region SR2may be disposed below the recess NTH. Thus, the recess NTH may separate the first sensing regions SR1from the second sensing region SR2. The number of the first sensing regions SR1disposed above the recess NTH may be selected from, but is not limited to, the range of 2 to 20 or the range of 5 to 15. Although the second force sensor200does not have the recess NTH, it may have the first sensing regions SR1and the second sensing region SR2at positions corresponding to the first sensing regions SR1and the second sensing region SR2of the first force sensor100. In an exemplary embodiment, the sensing regions SR1and SR2of the first force sensor100and the sensing regions SR1and SR2of the second force sensor200may be substantially symmetrical to each other in terms of number, area, gap, position, etc. However, exemplary embodiments are not limited thereto.

The recess NTH of the first force sensor100may be located in the middle or below the middle of the first force sensor100in the longitudinal direction of the first force sensor100, as illustrated inFIG.9. For example, a distance from the lower end of the first force sensor100to the recess NTH in a plan view may be about 30% to about 50% of the total length of the first force sensor100. In an exemplary embodiment, the distance from the lower end of the first force sensor100to the recess NTH may be between about 50 mm and about 60 mm.

When the first force sensor100is placed in the display device1, if a long side positioned on an outer side of the display device1is defined as an outer side, and a long side positioned on an inner side of the display device1is defined as an inner side, the recess NTH is formed at the inner side of the first force sensor100. In an exemplary embodiment, a width of the recess NTH recessed inward from the inner side of the first force sensor100may be between about 1 mm and about 4 mm. In an exemplary embodiment, a width of the recess NTH recessed inward from the inner side of the first force sensor100may be about 2 mm. In an exemplary embodiment, a length of the recess NTH may be about equal to the width of the recess NTH. However, exemplary embodiments are not limited thereto. The length of the recess NTH may be about equal to or greater than that of the connect hole53. When the first force sensor100is placed in the display device1, a recessed region of the recess NTH may overlap the connect hole53. The recessed shape of the recess NTH may be, for example, a rectangular shape or a square shape. However, the recessed shape of the recess NTH is not limited to the rectangular shape or the square shape. For example, in an exemplary embodiment, the recessed shape of the recess NTH may include a concave curve.

The first electrode112TX of the first force sensor100or the first electrode of the second force sensor200, and the second electrode112RX of the first force sensor100or the second electrode of the second force sensor200may be, for example, comb-shaped electrodes. The first electrode112TX of the first force sensor100or the first electrode of the second force sensor200, and the second electrode112RX of the first force sensor100or the second electrode of the second force sensor200, may be arranged such that the comb shapes are engaged with each other.

For example, the first electrode112TX of the first force sensor100or the first electrode of the second force sensor200, and the second electrode112RX of the first force sensor100or the second electrode of the second force sensor200, may include a stem electrode (or a connection electrode) and branch electrodes (or finger electrodes). The first electrode112TX of the first force sensor100or the first electrode of the second force sensor200, and the second electrode112RX of the first force sensor100or the second electrode of the second force sensor200may be arranged such that the branch electrodes are alternately disposed. This arrangement increases an area in which the first electrode112TX of the first force sensor100or the first electrode of the second force sensor200, and the second electrode112RX of the first force sensor100or the second electrode of the second force sensor200face each other, thereby enabling effective force sensing.

For example, in an exemplary embodiment, the first electrode112TX of the first force sensor100is structured to include a first stem electrode112TX_ST extending in the longitudinal direction, and a plurality of first branch electrodes112T_BR branching in the width direction from the first stem electrode112TX_ST. Similarly, the first electrode of the second force sensor200is structured to include a first stem electrode212TX_ST extending in the longitudinal direction, and a plurality of first branch electrodes212TX_BR branching in the width direction from the first stem electrode212TX_ST.

The first stem electrode112TX_ST or212TX_ST is disposed over the sensing regions SR1and SR2to provide a voltage (a driving voltage) to the sensing regions SR1and SR2. The first stem electrode112TX_ST or212TX_ST extends up to the non-sensing region NSR between neighboring sensing regions SR1and SR2, and electrically connects portions of the first stem electrode112TX_ST or212TX_ST which are disposed in the neighboring regions SR1and SR2.

The first electrode112TX_ST of the first force sensor100may be disposed adjacent to the outer side of the first force sensor100which is opposite the inner side where the recess NTH is formed. However, exemplary embodiments are not limited to this case. For example, in an exemplary embodiment, the first stem electrode112TX_ST of the first force sensor100may also be disposed on the inner side of the first force sensor100where the recess NTH is formed. In this case, the first stem electrode112TX_ST of the first force sensor100may be bent several times along the shape of the recess NTH of the first force sensor100to bypass the recess NTH, and then extend to the lower end of the first force sensor100, as illustrated inFIG.15.

The first stem electrode212TX_ST of the second force sensor200may be disposed adjacent to an outer side of the second force sensor200as illustrated inFIG.9. However, exemplary embodiments are not limited thereto. For example, in an exemplary embodiment, the first stem electrode212TX_ST of the second force sensor200may be disposed adjacent to an inner side of the second force sensor200. Since the second force sensor200does not include the recess NTH, it may extend straight without being bent to bypass the recess NTH, on whichever side the second force sensor200is disposed.

The first branch electrodes112TX_BR or212TX_BR branch from the first stem electrode112TX_ST or212TX_ST and extend in the width direction. In an exemplary embodiment, the first branch electrodes112TX_BR or212TX_BR may be disposed in the sensing regions SR1and SR2and are not disposed in the non-sensing region NSR. In an exemplary embodiment, if a region in which the recess NTH is formed in the first force sensor100is the non-sensing region NSR, the first branch electrodes112TX_BR is not disposed in the region. In an exemplary embodiment, in the second force sensor200structured symmetrically to the first force sensor100, the first branch electrodes212TX_BR are not disposed in a region corresponding to the recess NTH.

In one sensing region SR1or SR2, neighboring first branch electrodes112TX_BR or212TX_BR may be spaced apart from each other by a predetermined distance, and a second branch electrode112RX_BR or212RX_BR of the second electrode112RX of the first force sensor100or the second electrode of the second force sensor200may be disposed in each space between the neighboring first branch electrodes112TX_BR or212TX_BR. The number of the first branch electrodes112TX_BR or212TX_BR disposed in one sensing region SR1or SR2may vary depending on the area of the sensing region SR1or SR2. In an exemplary embodiment, the number of the first branch electrodes112TX_BR or212TX_BR disposed in one sensing region SR1or SR2may be between about 2 and about 20 based on each first sensing region SR1. The first branch electrodes112TX_BR or212TX_BR disposed in the second sensing region SR2may have the same width and spacing as the first branch electrodes112TX_BR or212TX_BR disposed in each first sensing region SR1. However, the number of the first branch electrodes112TX_BR or212TX_BR disposed in the second sensing region SR2may be greater in proportion to the area of the second sensing region SR2.

The second electrode112RX of the first force sensor100or the second electrode of the second force sensor200includes a second stem electrode112RX_ST or212RX_ST extending in the longitudinal direction, and a plurality of second branch electrodes112RX_BR or212RX_BR branching from the second stem electrode112RX_ST or212RX_ST.

The second stem electrode112RX_ST or212RX_ST faces the first stem electrode112TX_ST or212TX_ST. When the first stem electrode112TX_ST or212TX_ST is disposed adjacent to the inner side of each of the force sensors100and200, the second stem electrode112RX_ST or212RX_ST may be disposed adjacent to the outer side of each of the force sensors100and200. Unlike the first stem electrode112TX_ST or212TX_ST, the second stem electrode112RX_ST or212RX_ST covers one sensing region SR1or SR2. The second stem electrode112RX_ST or212RX_ST is disposed in each of the sensing regions SR1and SR2, and the second stem electrodes112RX_ST or212RX_ST disposed in different sensing regions SR1and SR2are electrically insulated from each other. Each second stem electrode112RX_ST or212RX_ST is connected to an independent sensing wiring112RX_WR or212RX_WR. Each sensing wiring112RX_WR or212RX_WR may extend in one direction and may be connected to a controller. Accordingly, each sensing wiring112RX_WR or212RX_WR may transmit data about the voltage or the amount of current applied to a corresponding second electrode112RX or212RX to the controller.

The second branch electrodes112RX_BR or212RX_BR branch from the second stem electrode112RX_ST or212RX_ST and extend in the width direction. The extending direction of the second branch electrodes112RX_BR or212RX_BR and the extending direction of the first branch electrodes112TX_BR or212TX_BR are opposite to each other. The second branch electrodes112RX_BR or212RX_BR are disposed between the first branch electrodes112TX_BR or212TX_BR. The number of the first branch electrodes112TX_BR or212TX_BR and the number of the second branch electrodes112RX_BR or212RX_BR in one sensing region SR1or SR2may be equal, however, exemplary embodiments are not limited thereto.

In one sensing region SR1or ST2, the first branch electrodes112TX_BR or212TX_BR and the second branch electrodes112RX_BR or212RX_BR may be alternately arranged. A gap between neighboring first and second branch electrodes112TX_BR and112RX_BR or212TX_BR and212RX_BR in one sensing region SR1or SR2may be uniform, however, exemplary embodiments are not limited thereto. A gap between nearest branch electrodes112TX_BR and112RX_BR or212TX_BR and212RX_BR in different sensing regions SR1and SR2, which neighbor each other with the non-sensing region NSR interposed between them, may be greater than the gap between the branch electrodes112TX_BR and112RX_BR or212TX_BR and212RX_BR in one sensing region SR1or SR2.

In an exemplary embodiment, the second electrode112RX of the first force sensor100and the second electrode of the second force sensor200are not disposed in the recess NTH of the first force sensor100and in a region of the second force sensor200which corresponds to the recess NTH. In some cases, however, the sensing wirings112RX_WR and212RX_WR of the second electrode112RX of the first force sensor100and the second electrode of the second force sensor200may pass through the above regions.

The force sensing layer122or222may have a shape corresponding to each of the sensing regions SR1and SR2. The force sensing layer122or222covers each of the sensing regions SR1and SR2. The first branch electrodes112TX_BR or212TX_BR and the second branch electrodes112RX_BR or212RX_BR in each of the sensing regions SR1and SR2may overlap the force sensing layer122or222in the thickness direction.

The force sensors100and200described above can be used as input devices for various electronic devices including the display device1, such as, for example, a smartphone and a tablet PC. The force sensors100and200can be used in place of physical input buttons or in combination with physical input buttons.

FIGS.10and11are diagrams illustrating a method of transmitting a force signal to the display device1according to an exemplary embodiment.

InFIGS.10and11, the display device1is implemented in a smartphone. In the display device1ofFIGS.10and11, the force sensors100and200are disposed on the long sides in place of physical input buttons. Thus, according to exemplary embodiments, a smartphone including the display device1may be implemented without any physical buttons.

InFIG.10, a case in which the first sensing regions SR1are used as pressing recognition regions is illustrated. A pressing recognition region is a region configured to sense a press input operation provided by the user. That is, inFIG.10, a user is pressing a specific position with an index finger while gripping the display device1with fingers. At the specific position, a first sensing region SR1of the force sensor100or200is disposed. When the first sensing region SR1receives a force, the resistance of the force sensing layer122or222is changed, and the change in the resistance of the force sensing layer122or222is sensed through the second electrode112RX of the first force sensor100or the second electrode of the second force sensor200to identify whether the force has been applied to the specific position, as well as the magnitude of the force. Then, a preprogrammed operation of the display device1may be output according to the force and/or the magnitude of the force applied to the specific position. For example, a preprogrammed function such as screen adjustment, screen lock, screen conversion, application calling, application execution, picture taking, or telephone reception may be performed. Different operations may be preprogrammed for different first sensing regions SR1. Therefore, as the number of the first sensing regions SR1increases, the display device1can produce additional outputs.

InFIG.11, a case in which the second sensing region SR2is used as a squeezing recognition region is illustrated. A squeezing recognition region is a region configured to sense a squeezing input operation provided by the user. That is, inFIG.11, the user is squeezing a relatively large area using the palm and fingers while gripping the display device1with the fingers. The second sensing region SR2is disposed in the area in which the squeezing is performed to sense whether a force has been applied by the squeezing, as well as the magnitude of the force. Thus, a preprogrammed operation of the display device1may be performed according to the sensing result (e.g., when it is sensed that the second sensing region SR2has been squeezed).

The user may perform the squeezing operation by naturally applying force using the entire hand while gripping the display device1. Since the user can quickly perform the squeezing operation without the elaborate movement of the hand while gripping the display device1, a simpler and quicker input is possible. For example, the user may provide a squeeze input without being concerned with the precise location at which each of the fingers are located on the display device1. Therefore, the second sensing region SR2can be used as an input medium for a frequently used function or a program requiring rapid inputs, such as using a camera application to take pictures.

Hereinafter, additional exemplary embodiments will be described. In the following exemplary embodiments, the same components as those described above will be indicated by the same reference numerals. Thus, for convenience of explanation, a redundant description of such components may be omitted or only briefly described. The following exemplary embodiments will be described by focusing mainly on differences with the previously described exemplary embodiment.

FIG.12is a layout view of a first force sensor100and a second force sensor200_1according to an exemplary embodiment.

The exemplary embodiment fFIG.12is different from the exemplary embodiment ofFIG.9in that a second sensing region SR2of the second force sensor200_1has a wider area than a second sensing region. SR2of the first force sensor100. Referring toFIG.12, the second sensing region SR2of the second force sensor200_1extends further toward an upper end than the second sensing region SR2of the first force sensor100. For example, the second sensing region SR2of the second force sensor200_1may extend up to a region corresponding to a recess NTH of the first force sensor100.

Referring to the squeezing operation ofFIG.11, the areas in which the palm or the fingers naturally touch the first long side and the second long side may be different. The exemplary embodiment ofFIG.12enables a more precise force measurement in this case.

InFIG.12, reference numeral210_1indicates a first substrate of the second force sensor200_1, and reference numeral220_1indicates a second substrate of the second force sensor200_1.

FIG.13is a layout view of a first force sensor100_2and a second force sensor200_2according to an exemplary embodiment.

InFIG.13, a case in which a force sensing layer122or222is formed as a single piece without being divided into segments respectively corresponding to sensing regions SR1and SR2is illustrated. Referring toFIG.13, a second substrate120_2or220_2of each of the first force sensor100_2and the second force sensor200_2includes the force sensing layer122or222formed as a single piece. Although the force sensing layer122or222is formed as a single piece, the second electrode112RX of the first force sensor100_2or the second electrode of the second force sensor200_2, or the first electrode112TX of the first force sensor100_2or the first electrode of the second force sensor200_2, is still a functionally separate electrode disposed in each of the sensing regions SR1and SR2. Therefore, when a force is applied to a specific sensing region SR1or SR2, the transmission of a sensing signal to other sensing regions SR1and SR2can be prevented, thereby preventing the generation of noise at an input position.

FIG.14is a layout view of a first force sensor100_3and a second force sensor200_3according to an exemplary embodiment. In the exemplary embodiment ofFIG.14, a case in which a non-sensing region NSR is disposed in portions of a second sensing region SR2of each of the first force sensor100_3and the second force sensor200_3is illustrated.

Referring toFIG.14, in the second sensing region SR2of each of the first and second force sensors100_3and200_3, first branch electrodes112TX_BR or212TX_BR and second branch electrodes112RX_BR or212RX_BR of a first substrate110_3or210_3may be arranged similarly to a plurality of first sensing regions SR1. That is, the first branch electrodes112TX_BR of212TX_BR and the second branch electrodes112RX_BR or212RX_BR are alternately arranged in predetermined numbers at a first interval in the longitudinal direction, are not arranged by a second interval larger than the first interval, and then are alternately arranged again at the first interval. Even in this case, the second branch electrodes112RX_BR or212RX_BR in the second sensing region SR2are electrically connected by one second stem electrode112RX_ST or212RX_ST. A force sensing layer122or222of a second substrate120_3or220_3may also be patterned like the first sensing regions SR1. However, exemplary embodiments are not limited to this case, and the force sensing layer122or222in the second sensing region SR2may also be formed as a single piece as illustrated inFIG.9without being patterned.

In the exemplary embodiment ofFIG.14, the first and second electrodes112TX and112RX of the first force sensor100_3, or the first and second electrodes of the second force sensor200_3, and the force sensing layer122or222, have similar patterns in the first sensing regions SR1as well as in the second sensing region SR2. Therefore, problems that may occur due to differences in shape can be prevented. Although the non-sensing region NSR is disposed in portions of the second sensing region SR2, since the entire second sensing region SR2is sensed using one second electrode (e.g., the second electrode112RX of the first force sensor100_3or the second electrode of the second force sensor200_3) as in the exemplary embodiment ofFIG.9and a squeezing operation is performed on a wide area, a squeezing input may be accurately recognized.

FIG.15is a layout view of a first force sensor100_4and a second force sensor200_4according to an exemplary embodiment. The exemplary embodiment ofFIG.15is different from the exemplary embodiment ofFIG.9in that a second electrode112RX of the first force sensor100_4or a second electrode of the second force sensor200_4is formed as a single piece.

Referring toFIG.15, in an exemplary embodiment, all portions of the second electrode112RX of the first force sensor100_4or the second electrode of the second force sensor200_4are connected by a second stem electrode112RX_ST or212RX_ST, like a first electrode112TX of the first force sensor100_4or a first electrode of the second force sensor200_4. Therefore, when a force is applied, it is possible to measure the presence or absence of the force and the magnitude of the force, but it may be difficult to identify a position at which the force has been applied. The first force sensor100_4includes a first substrate110_4and a second substrate120_4, and the second force sensor200_4includes a first substrate210_4and a second substrate220_4.

The position at which the force has been applied may be identified through a touch member20(seeFIG.2). That is, a touch electrode may be disposed in regions of the touch member20which overlap the force sensors100_4and200_4. The touch electrode may be used to detect the presence or absence of a touch and the position of the touch. The presence or absence of a force and the magnitude of the force may be measured by the force sensors100_4and200_4and used as an input signal.

FIG.16is a cross-sectional view of a first force sensor100_5according to an exemplary embodiment.FIG.17is a layout view of the first force sensor100_5ofFIG.16. Referring toFIGS.16and17, the shape and arrangement of first and second electrodes113and123of the first force sensor100_5according to the current exemplary embodiment are different from those of the exemplary embodiment ofFIG.9.

For example, a first substrate110_5includes a first base111and the first electrode113disposed on the first base111. A second substrate120_5includes a second base121, the second electrode123disposed on the second base121, and a force sensing layer122disposed on the second electrode123. The first electrode113faces the force sensing layer122and is in contact with or adjacent to the force sensing layer122.

In the exemplary embodiment ofFIGS.16and17, the first electrode113and the second electrode123face each other in the thickness direction with the force sensing layer122interposed between them. When a force is applied, the resistance of the input sensing layer122is changed, thereby changing the amount of current flowing between the first electrode113and the second electrode123. Thus, the force input can be sensed.

InFIG.17, the first electrode113is a separate sensing electrode disposed in each sensing region, and the second electrode123is a driving electrode formed as a whole-plate electrode. However, the first electrode113may also be formed as a whole-plate electrode, and the second electrode123may also be formed as a sensing electrode.

Although only the first force sensor100_5is illustrated inFIGS.16and17, a second force sensor may also have the same configuration as the first force sensor100_5except for the inclusion of a recess NTH.

FIG.18is a cross-sectional view of a display device2according to an exemplary embodiment.

FIG.18shows that the attachment position of a first force sensor100and a second force sensor200in the display device2can be changed. That is, as illustrated inFIG.18, the first force sensor100and the second force sensor200can be directly attached to a window10without overlapping a display panel30and a touch member20.

FIG.19is a cross-sectional view of a display device3according to an exemplary embodiment.

FIG.19shows that a second area DR2of the display device3can lie in a plane at an angle of about 90 degrees or more to a first area DR1. The second area DR2may substantially form side surfaces of the display device3. The second area DR2may be a display surface, and may correspond to a non-display area. A first force sensor100and a second force sensor200are attached to the second area DR2of the display device3. Since the first force sensor100and the second force sensor200are attached to the side surfaces of the display device3in the exemplary embodiment ofFIG.19, a user can easily input a force while gripping the display device3.

A force sensor and a display device according to an exemplary embodiment can prevent a malfunction due to interference between components, and can simplify an input method.