Stylus pen having a ferrite core and a wound coil

1 . A stylus pen comprising:

a ferrite core; and

a coil including a plurality of metal wires twisted to have a number of twist turns per unit length of 10 to 15 turns/cm, and wound on an outer surface of the ferrite core.

2 . The stylus pen of claim 1 , wherein:

the number of twist turns per unit length is the number of times the plurality of metal wires are wound from one point on the outer surface of the ferrite core through another point and back to the one point.

3 . The stylus pen of claim 2 , wherein:

the plurality of metal wires includes a central metal wire positioned at an inner center of the coil and a plurality of outer metal wires positioned at an inner periphery of the coil, and

the number of twist turns per unit length is the number of times the plurality of outer metal wires are wound from the one point on the outer surface of the ferrite core through the another point and back to the one point.

4 . The stylus pen of claim 2 , wherein:

the plurality of metal wires includes a plurality of central metal wires positioned at an inner center of the coil and a plurality of outer metal wires positioned at an inner periphery of the coil, and

the number of twist turns per unit length is the number of times the plurality of outer metal wires are wound from the one point on the outer surface of the ferrite core through the another point and back to the one point.

5 . The stylus pen of claim 2 , wherein:

the coil is wound while having a spaced distance from each of opposite ends of the ferrite core in an axial center direction.

6 . The stylus pen of claim 5 , wherein:

the ferrite core is separated into a plurality of regions at regular intervals, relative to the axial center direction of the ferrite core, and the coils are individually wound on the plurality of regions.

7 . The stylus pen of claim 6 , wherein:

each of the plurality of regions includes a lower layer region and an upper layer region disposed on top of the lower layer region, and when the winding of the lower layer region ends and the winding of the upper layer region starts.

8 . The stylus pen of claim 7 , wherein:

the upper layer region includes a first upper layer region and a second upper layer region,

the first upper layer region is disposed on top of the lower layer region, and

the second upper layer region is disposed on top of the first upper layer region.

9 . The stylus pen of claim 7 , wherein:

the coil is wound on a bobbin wrapped around at least a portion of the ferrite core.

10 . A touch system comprising:

a stylus pen including an inductor unit including a Litz wire cable including a plurality of metal wires twisted to have a number of twist turns per unit length of 10 to 15 turns/cm, in a rotary form around a portion of a ferrite core, and a capacitor electrically connected to the inductor unit; and

a touch screen including a touch electrode layer receiving a resonated electromagnetic signal from the stylus pen.

11 . The touch system of claim 10 , wherein:

the plurality of metal wires is twisted in a rotary form around a portion of the ferrite core while having a spaced distance from each of opposite ends of the ferrite core in an axial center direction.

12 . The touch system of claim 11 , wherein:

the ferrite core is separated into a plurality of regions at regular intervals, relative to the axial center direction of the ferrite core, and

the Litz wire cables are individually wound on the plurality of regions.

13 . The touch system of claim 12 , wherein:

each of the plurality of regions includes a lower layer region and an upper layer region disposed on top of the lower layer region, and when the winding of the lower layer region ends and the winding of the upper layer region starts.

14 . The touch system of claim 13 , wherein:

the Litz wire cable is wound around a first connection region that connects a first region, which is any one of the plurality of regions, and a second region adjacent to the first region.

15 . The touch system of claim 14 , wherein:

the first connection region includes a connection region in which an upper layer region of the first region is connected with a lower layer region of the second region by the Litz wire cable.

16 . The touch system of claim 15 , wherein:

the Litz wire cable is wound around a bobbin wrapped around at least a portion of the ferrite core.

17 . A stylus pen comprising:

an inductor unit including a coil wound on a portion of a ferrite core in a plurality of steps, and including a plurality of metal wires twisted to have a number of twist turns per unit length of 10 to 15 turns/cm, in a rotary form; and

a capacitor unit electrically connected with the coil.

18 . The stylus pen of claim 17 , wherein:

the coil wound on the portion of the ferrite core in the plurality of steps wound in a plurality of winding pile regions in which the ferrite core is wound and a plurality of winding connection regions connecting each of the plurality of winding pile regions.

19 . The stylus pen of claim 18 , wherein:

the plurality of winding pile regions is a region in which the ferrite core is separated into a plurality of regions and is wound with the coil while having a spaced distance from each of opposite ends of the ferrite core in an axial center direction, and each of the plurality of regions includes a plurality of layers around which the coil is wound.

20 . The stylus pen of claim 19 , wherein:

the plurality of winding connection regions connects a first winding pile region, which is any one winding pile region among the plurality of winding file regions, and a second winding pile region adjacent to the first winding pile region, and connects a first layer, which is the highest layer of a plurality of layers included in the first winding pile region, and a second layer, which is the lowest layer of a plurality of layers included in the second winding pile region.