Refill for electronic pen

Abstract

This invention provides an electronic pen core that provides a desired pen feel and excellent wear resistance. The core is formed by integrally combining a tip portion that contacts the position indicator input surface and a rod-shaped core portion. At least the tip portion is composed of a filler-infused resin, which is formed by incorporating a fibrous material with a higher hardness than the base resin into a base resin.

Description

Technical Field

[0001] The present invention relates to a core for an electronic pen, suitable for use as a core in, for example, an electromagnetically inductive electronic pen. Background Technology

[0002] In recent years, with the expansion of computer graphics (CG) and digital painting, computers and handwriting tablets using coordinate input devices as input devices are becoming increasingly common. A coordinate input device consists of a position detection device equipped with a position detection sensor and an electronic pen that interacts with the position detection sensor.

[0003] The position detection sensor of the position detection device is located on the lower part (back side) of the computer screen and the tablet-shaped input surface. The user uses an electronic pen to input notes (drawing) by using the computer screen and the tablet-shaped input surface as the position indication input surface corresponding to the position detection area of ​​the position detection sensor. The position detection device detects the coordinates of the indicated position of the electronic pen tip through the position detection sensor, and the computer and tablet display a continuous drawing trajectory based on the detected coordinates of the indicated position on the screen.

[0004] In note-taking (drawing) input using electronic pens, reproducing the feel of drawing on paper with a pencil has become an important issue. In electronic pens, the tip of the pen core protrudes outward from the pen frame as the pen tip. The user makes contact with the computer screen, the tablet-shaped input surface of the pen core, or other indicator input surfaces to input positional information.

[0005] Therefore, the writing feel of an electronic pen is determined by the material of the pen tip and the material of the position indicator input surface. In this case, it is known that in order to obtain a writing feel similar to that of a combination of paper and pencil, a certain degree of friction is required between the electronic pen tip and the position indicator input surface.

[0006] Regarding the position indicator input surface, the following solution is proposed: In order to provide a good pen stroke feel, a surface sheet is attached to the display screen or the like, thereby generating friction through the mutual friction between the electronic pen core and the surface sheet, presenting the desired pen stroke feel (see Patent Document 1 (Japanese Patent No. 6405495)).

[0007] On the other hand, various materials have been used in the past for the core of electronic pens, but metal cores are too hard, and elastomeric cores are too soft, making it difficult to achieve the same writing feel as a combination of paper and pencil. Therefore, resin with moderate hardness and elasticity is best for achieving the same writing feel as a combination of paper and pencil.

[0008] Prior art literature

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent No. 6405495 Summary of the Invention

[0011] Summary of the invention

[0012] The problem that the invention aims to solve

[0013] If an electronic pen uses resin as its core and draws on a rough surface, the resin is scratched by friction, and empirically, this scratching creates a writing feel. The softness of the electronic pen core's scratching due to friction with the surface can reproduce the same writing feel as a combination of paper and pencil.

[0014] However, the pen tip is scratched by friction against the surface plate of the position indicator input surface, meaning it wears down slowly. Therefore, if the pen tip wears out quickly, users may have to replace it frequently.

[0015] In view of the above problems, the present invention aims to provide a pen core that can provide a desired pen stroke feel and reduce wear.

[0016] Solution for solving the problem

[0017] To address the aforementioned issues, a core for an electronic pen is provided, characterized by integrally forming a tip portion that contacts the position indicator input surface and a rod-shaped central portion, wherein...

[0018] At least the tip portion is composed of a filler mixed with resin, which is formed by mixing a fibrous material with a higher hardness than the matrix resin into the matrix resin as a filler.

[0019] In the above-described structure, at least the tip of the electronic pen core is composed of a filler-infused resin, which is formed by incorporating a fibrous material with a higher hardness than the matrix resin as a filler. Therefore, compared to electronic pen cores where the tip is composed solely of matrix resin, it exhibits superior wear resistance. Consequently, the above-described structure of the electronic pen core easily provides the desired pen stroke feel and achieves excellent wear resistance. Attached Figure Description

[0020] Figure 1 This is a diagram illustrating an example of the configuration of an electronic pen equipped with an embodiment of the electronic pen core of the present invention.

[0021] Figure 2This diagram illustrates the wear and tear on the core of an electronic pen.

[0022] Figure 3 This is a diagram illustrating the suppression of wear on the electronic pen core in an embodiment of the electronic pen core of the present invention.

[0023] Figure 4 This is a diagram illustrating a manufacturing method for an embodiment of the electronic pen core of the present invention.

[0024] Figure 5 This is a diagram illustrating an example of an embodiment of the electronic pen core of the present invention.

[0025] Figure 6 This is a diagram illustrating another example of an embodiment of the electronic pen core of the present invention. Detailed Implementation

[0026] Hereinafter, embodiments of the electronic pen core of the present invention will be described with reference to the accompanying drawings. The electronic pen core described below is sometimes used as the core of an electronic pen for an electromagnetic induction coordinate input device.

[0027] Before describing an embodiment of the electronic pen core of the present invention, an outline of the coordinate input device using electromagnetic induction will be described.

[0028] The coordinate input device using electromagnetic induction consists of a position detection device and an electronic pen. The position detection device has a position detection sensor consisting of multiple loop coils arranged along the X-axis and Y-axis directions of the coordinate axis. The electronic pen has a resonant circuit consisting of a coil wound around a magnetic core as an example of an inductive element and a capacitor.

[0029] Furthermore, the position detection device supplies a transmission signal at a predetermined frequency to the loop coil of the position detection sensor, transmitting it as electromagnetic energy to the electronic pen. The resonant circuit of the electronic pen is configured to have a resonant frequency corresponding to the frequency of the transmission signal, accumulating electromagnetic energy based on electromagnetic induction with the loop coil of the position detection sensor. The electronic pen then returns the electromagnetic energy accumulated in the resonant circuit to the loop coil of the position detection sensor.

[0030] The position detection sensor's loop coil detects electromagnetic energy from the electronic pen. The position detection device detects the X-axis and Y-axis coordinates on the position detection sensor indicated by the electronic pen by supplying the position of the loop coil that transmits the signal and the position of the loop coil that detects electromagnetic energy from the electronic pen's resonant circuit.

[0031] Figure 1This is an example of the general structure of such an electronic pen 1. The housing (box) 2 of the electronic pen 1 has a cylindrical shape. Inside the hollow part of the housing 2, a coil 3 for position detection, a pen pressure detection unit 4, and a printed circuit board 6 are arranged sequentially along the axial direction. The printed circuit board 6 is equipped with electronic components such as a capacitor 5 that together with the coil 3 form a resonant circuit.

[0032] A coil 3 is wound around a cylindrical ferrite core 7, which serves as an example of a magnetic core, and has a through hole 7a in the axial direction. The structure with the coil 3 wound around the ferrite core 7 is housed near the opening 2a on the tip side of the housing 2. A pen pressure detection unit 4 is housed via a buffer member 8 on the side of the ferrite core 7 opposite to the opening 2a of the housing 2. The pen pressure detection unit 4 includes a core support 9.

[0033] In one embodiment of the electronic pen core, the core 10 has a structure in which the tip 11, which becomes the pen tip, and the axis 12 are integrated into one piece. In this example, the tip 11 of the core 10 is configured as a cylindrical structure with a circular cross-section, and the tip surface that contacts the indicator input surface is a hemispherical curved surface, so that when the user indicates the position of the indicator input surface, the same pen stroke feel is always presented even when the electronic pen is tilted or rotated. Moreover, in this example, the axis 12 of the core 10 is configured as a rod-shaped structure with a circular cross-section, and in this example, the diameter of the cross-section is smaller than the diameter of the cross-section of the tip 11.

[0034] The core 10 is inserted into the housing 2 through the opening 2a from the side of the spindle portion 12, passing through the through hole 7a of the ferrite core 7. Furthermore, the end of the spindle portion 12 of the core 10 is fitted and held in place by the core support 9 provided in the pen pressure detection unit 4. In this case, the core 10 is held in the core support 9 in a freely detachable state. And, when the end of the spindle portion 12 is fitted with the core support 9, as... Figure 1 As shown, the tip 11 of the core 10 protrudes outward from the opening 2a of the housing 2.

[0035] In the electronic pen 1 of this example, the pen pressure detection unit 4 is configured as a variable capacitor structure that detects the change in electrostatic capacitance as a result of the pressure (pen pressure) applied to the tip 11 of the core 10. It is electrically connected to the printed circuit board 6 through its terminals 4a and 4b, and together with the coil 3 and the capacitor 5, it forms a resonant circuit.

[0036] As described above, in the coordinate input device, the position indication input surface of the electronic pen 1 is formed overlapping with the position detection area of ​​the position detection sensor. The user performs position indication input, i.e., note-taking or drawing input, by contacting the tip of the core 10 of the electronic pen 1 with the position indication input surface. The electronic pen 1 transmits and receives electromagnetic waves with the position detection sensor through a resonant circuit.

[0037] That is, the electronic pen 1 receives the signal from the position detection sensor of the position detection device through a resonant circuit, and indicates the position to the position detection device by feeding it back to the position detection device. The position detection device detects the position at which the feedback signal from the electronic pen 1 is detected by the position detection sensor by monitoring the received signal of the loop coil, thereby detecting the coordinates of the position indicated by the electronic pen 1.

[0038] Furthermore, in the electronic pen 1, when pressure (pen pressure) is applied to the core 10, the capacitance of the capacitor in the pen pressure detection unit 4 changes, and the resonant frequency changes. The position detection device detects the pressure (pen pressure) applied to the tip 11 of the core 10 of the electronic pen 1 based on the detection of this change in resonant frequency.

[0039] [Example of the material of core 10 as an embodiment of the core for an electronic pen]

[0040] In the electronic pen 1 using the electromagnetic induction method described above, the core 10 is typically made of a resin material that provides the desired pen stroke feel. However, as mentioned earlier, a core made solely of this resin material suffers from the problem of relatively rapid wear due to friction with the position indicator input surface.

[0041] In view of this situation, in this embodiment, the core 10 is configured to maintain the desired pen stroke feel and to suppress wear as much as possible. That is, in this embodiment, the core 10 is composed of a filler-in-resin, which is a resin (hereinafter referred to as matrix resin) that is the main material, into which a filler is mixed.

[0042] As the base resin for the core 10, which provides the desired pen stroke feel, the resin needs to be abrasive. Therefore, in this embodiment, a resin material that can be abraded by friction with the surface sheet is used, such as POM (polyoxymethylene). It should be noted that the base resin is not limited to POM.

[0043] Furthermore, the filler incorporated into the matrix resin, i.e., POM, preferably meets the conditions described below. The conditions that the filler incorporated into the matrix resin should meet will be explained in more detail below.

[0044] <Mechanism of Core Wear>

[0045] like Figure 2 As shown in (A), when the electronic pen 1 is used for note-taking or drawing input, with the tip 11 of the core 10 in contact with the surface plate 100 attached to the position detection sensor, on the surface plate 100, ... Figure 2The arrow in (A) indicates that the pen slides along the direction of the surface plate 100. Therefore, the tip 11 of the core 10 of the electronic pen 1 wears down due to friction with the surface plate 100. The state of wear of the tip 11 of the core 10 with respect to the surface plate 100 will be explained. It should be noted that in this case, the surface of the surface plate 100 becomes the position indicator input surface.

[0046] like Figure 2 As shown in the enlarged views (B) and (C), the surface of the surface plate 100 is composed of multiple fine protrusions 100a to make the input sensation using the electronic pen 1 similar to the rough feel of writing with a pencil on paper. The surface of the tip 11 of the core 10 of the electronic pen 1 contacts the protrusions 100a and... Figure 2 When the arrow in (A) moves, the surface of the tip 11 of the core 10 rubs against the protrusion 100a of the surface plate 100, and the surface of the tip 11 of the core 10 of the electronic pen 1 is chipped off, thereby the tip 11 of the core 10 is slowly worn down (wear).

[0047] Wear can take many forms, but the two most relevant to wear on electronic pen cores are abrasive wear and fatigue friction.

[0048] Figure 2 (B) is a diagram showing abrasive wear. Abrasive wear is as follows: Figure 2 As shown in (B), wear occurs when a portion of the surface of the tip 11 of the core 10 is raised due to the protrusion 100a of the surface sheet, which is made of the opposing material, engaging with the tip 11. Furthermore, Figure 2 (C) is a diagram representing fatigue friction. Fatigue wear is as follows: Figure 2 As shown in (C), in the case of the tip 11 of the core 10, the tip 11 of the core 10 undergoes fatigue deterioration, and therefore, wear is caused by the protrusion 100a of the surface sheet, which is the opposite material, tearing.

[0049] <Parameters for improving the wear resistance of resin>

[0050] In the wear of the core 10 relative to the surface plate 100, abrasive wear is the main component. This abrasive wear can be expressed by the following formula.

[0051] Right now,

[0052] Friction volume = relative wear (constant) × load × sliding distance

[0053] = Constant × (Coefficient of friction / (Hardness × Tensile strength at break × Elongation at break))

[0054] ×load ×sliding distance…(Equation 1).

[0055] Based on Equation 1 above, the following four points can be listed as parameters (main causes) related to abrasive wear:

[0056] 1. The less friction, the less likely it is to wear out;

[0057] 2. The harder a material is, the less likely it is to wear down;

[0058] 3. The higher the tensile strength of a material, the less likely it is to wear out;

[0059] 4. The higher the elongation at break of a material during tensile testing, the less likely it is to wear out.

[0060] Furthermore, it is conceivable that the parameter "2. material hardness" in the above four points is particularly effective for abrasive wear. Therefore, in this embodiment, the core 10 is a structure in which a filler with a material having a hardness higher than that of the matrix resin is mixed into the matrix resin, which in this example is POM, thus constituting a filler mixed into the resin.

[0061] Furthermore, in this embodiment, in order to prevent the matrix resin from peeling off due to fatigue wear and abrasive wear as described above, a filler is constructed using a fibrous material, based on the viewpoint of pulling back the peeled matrix resin portion.

[0062] Figure 3 This diagram illustrates how abrasive wear and fatigue wear can be suppressed by incorporating a filler composed of fibrous material into the matrix resin of the core 10. That is, Figure 3 (A) is a diagram showing the abrasive wear situation, and, Figure 3 (B) is a diagram about fatigue wear, with the thick dashed line representing the filler FI made of fibrous material.

[0063] from Figure 3 (A) It is known that, regarding abrasive wear, the filler FI, which is composed of fibrous material, enters the matrix resin and pulls back the peeled part of the matrix resin through the fibrous material, making it difficult to dig up the surface of the tip 11 of the core 10.

[0064] In addition, from Figure 3 (B) It can be seen that, regarding fatigue wear, by binding the broken part with the filler FI made of fibrous material, the tip 11 of the core 10 caused by fatigue wear is difficult to reduce.

[0065] As described above, the fibrous material pulls the peeled parts of the matrix resin or binds the broken parts. Therefore, the parameters "3. tensile strength of material" and "4. elongation at break of material" mentioned above are also considered important. In this embodiment, the fibrous material used as the filler is a material with a higher hardness and a higher tensile strength than POM, which is an example of a matrix resin.

[0066] Examples of fibrous materials that meet the above conditions include carbon fiber, glass fiber, and fibers made of a resin called Kevlar (registered trademark) that is poly(p-phenylene terephthalamide) (hereinafter referred to as Kevlar fiber). Any fibrous material can be used as the core of the electronic pen in this embodiment.

[0067] However, Kevlar fibers are more effective as a fibrous material incorporated into the matrix resin of an electronic pen core, taking into account the following viewpoints.

[0068] That is, when the tip 11 of the core 10, which is made of resin mixed with a filler containing fibrous material, wears down, the fibrous material may fly off the surface of the tip 11. In this case, if the fibrous material is hard, it may damage the surface sheet. Therefore, when using a hard fibrous material as a filler, the surface sheet must be made of a material with a higher hardness than the hard fibrous material. The material of the surface sheet is limited, making it difficult to construct a surface sheet that provides the desired pen feel for the core 10 of the electronic pen 1.

[0069] The hardness of the fibrous materials used as fillers in the examples follows the order: carbon fiber > glass fiber > Kevlar fiber > POM (matrix resin). In the examples, Kevlar fiber has the lowest hardness and is flexible. Furthermore, the hardness of the surface sheet varies. Therefore, when the surface sheet hardness is 3H to 5H (the hardness of a pencil), if the filler ejected from the tip 11 of the core 10 is carbon fiber, its hardness of 9H or higher will damage the surface sheet. Similarly, if it is glass fiber, its hardness of around 9H will also damage the surface sheet. However, when the filler ejected from the tip 11 of the core 10 is Kevlar fiber, its hardness of 4H to 5H makes it less susceptible to damage, especially if the surface sheet has a hardness of 3H to 5H. Therefore, in this embodiment, Kevlar fiber is the optimal material to be used as the fibrous material mixed into the matrix resin of the electronic pen core.

[0070] [Manufacturing method of core 10 as an example of an electronic pen core]

[0071] The core 10 is manufactured by injecting a resin containing a filler incorporating fibrous material into a dedicated mold and then cooling it. In this case, the length of the fibrous material fibers is set to ensure the fluidity of the filler mixed into the resin. That is, if the length of the fibrous material fibers is longer than the diameter of the cross-section of the core 10's central portion 12 and the diameter of the cross-section of the tip portion 11, the fluidity of the filler mixed into the resin will deteriorate due to the fibrous material, which will hinder the molding of the core 10. Therefore, in this embodiment, the length of the fibrous material fibers is set to be at least shorter than the diameter of the cross-section of the core 10's central portion 12 and the diameter of the cross-section of the tip portion 11.

[0072] In this case, the shorter the length of the fibrous material, the better the flowability of the filler mixed with the resin during the molding of the core 10, and therefore the easier it is to manufacture the core 10. However, if the fiber length is too short, it is difficult to obtain usable results. Figure 3 The wear-prevention effect of the fibrous material described herein makes the tip 11 of the core 10 prone to wear. On the other hand, if the fibers of the fibrous material are long, the fibrous material is easily exposed from the surface of the tip 11 when the tip 11 of the core 10 wears.

[0073] Therefore, in this embodiment, the length of the fibrous material mixed into the matrix resin is selected to be at least shorter than the diameter of the cross-section of the core 10's axial portion 12 and the diameter of the cross-section of the tip portion 11, and is a length that, taking into account the fluidity of the filler mixed into the resin, makes it as difficult as possible for the fibrous material to be exposed from the surface of the tip portion 11 when the tip portion 11 of the core 10 is worn.

[0074] Furthermore, regarding the injection position and direction of the filler material mixed with fibrous material into the resin in the mold, in this embodiment, it is configured such that it is injected from the side of the core 10 toward the axis 12, rather than from the tip of the core 10 toward the axis 12. Moreover, with the recent trend towards thinner electronic pens, considering the thickness of the core 10 and the diameter of the axis 12 being set to, for example, 0.5 mm, the filler material mixed with resin is injected from the middle of the axis 12.

[0075] That is, if the filler mixed with resin is injected from the end side of the axial portion 12 of the core 10 in the axial direction, there is a concern that the fibrous material FI, as the filler, may become blocked midway in the portion corresponding to the axial portion 12 and fail to reach the portion corresponding to the tip 11. However, if the filler mixed with resin is injected from the position corresponding to the midway of the axial portion 12, the filler mixed with resin flows in such a way that the fibrous material reaches the portion corresponding to the tip 11 of the core 10.

[0076] Figure 4An outline of the mold for manufacturing the core 10, which is an example of the core for an electronic pen in this embodiment, and the resin injection position are shown.

[0077] like Figure 4 As shown, a cavity 201 with a shape corresponding to the tip 11 and the axial portion 12 of the core 10 is formed in the mold 200. Furthermore, in the mold 200, a resin injection port 202 connected to the cavity 201 is provided at the middle position of the cavity 201 corresponding to the middle portion of the axial portion 12 of the core 10.

[0078] Furthermore, the molten filler mixed with fibrous material is injected from the resin container 203 through the resin injection port 202 of the mold 200, such as... Figure 4 As indicated by the middle arrow, the material flows toward the tip 11 and the rear end of the shaft 12, thereby forming the core 10.

[0079] Figure 5 A schematic diagram showing the incorporation state of the fibrous material FI in the core 10 manufactured as described above within the filler and resin RS. That is, as... Figure 5 As shown, the tip face of the tip 11 of the core 10 is hemispherical, so the fibrous material FI at the tip 11 of the core 10 is inclined along the shape of its tip face (in a direction that is inclined to intersect the axial direction). This is because the fibrous material FI flows into the cavity 201 of the mold 200 together with the filler mixed with resin RS and fills the cavity 201 together with the filler mixed with resin RS. That is, the reason is that the filler mixed with resin RS flows along the curved surface of the cavity 201 of the mold 200 corresponding to the tip 11 of the core 10 and fills the cavity 201, so the fibrous material FI carried by this flow is filled in a state along the curved surface of the portion corresponding to the tip 11 of the core 10.

[0080] Therefore, even if the tip 11 of the core 10 wears, the tip of the fibrous material is unlikely to fly outward, thus suppressing damage to the surface sheet. Furthermore, as mentioned earlier, when Kevlar fiber is used as the fibrous material, even if the tip flies out, its softness and high flexibility further suppress damage to the surface sheet.

[0081] Furthermore, regarding the core 10 of this embodiment, the filler mixed with resin RS injected from the resin injection port 202 is prevented from flowing by the tip 11, which has a larger diameter than the core portion 12. Therefore, the density of the fibrous material in the tip 11 is higher than that in the core portion 12. As a result, the wear resistance of the tip 11 of the core 10 is increased.

[0082] Furthermore, in this embodiment, the core 10 integrates the tip 11 and the shaft portion 12, and the shaft portion 12 is also formed by incorporating a filler containing fibrous material into the resin. Therefore, the strength of the shaft portion 12 is enhanced, making it difficult to break. It should be noted that, in the case of a thin electronic pen core, carbon fiber or glass fiber, which has a higher hardness than Kevlar fiber, is preferably used as the fibrous material incorporated into the matrix resin.

[0083] It should be noted that, as a thin electronic pen core that is difficult to break, the core can be covered with an outer skin that is harder than the base resin. Figure 6 The core 10A is shown with its outer skin covering the central part.

[0084] That is, in this example, the core 10A has a circular cross-section and one end of the rod-shaped axial portion 12A with a predetermined diameter is configured as a pointed portion 11A in the shape of, for example, a projectile. Furthermore, the core 10A is constructed by, for example, mixing a filler, which is a fibrous material FI made of Kevlar fiber in this example, into a matrix resin made of POM and then mixing it into the resin RS.

[0085] Furthermore, in this example, the core 10A's axial portion 12A is covered by an outer skin 13 in a cylindrical shape. In this example, the cylindrical outer skin 13 is made of carbon fiber or glass fiber, which has a higher hardness than POM, the matrix resin. It should be noted that the cylindrical outer skin 13 can also be made of other materials with a higher hardness than POM, the matrix resin.

[0086] [Effects of the electronic pen core according to the embodiment]

[0087] The electronic pen core of the above-described embodiment is made of a filler-mixed resin. The filler-mixed resin uses a resin that can be worn in a way that provides the desired pen stroke feel as the base resin, and a fibrous material with a hardness higher than that base resin is mixed into the base resin as a filler. Therefore, the desired pen stroke feel of the electronic pen can be obtained, and the strength of the resin at the tip of the core relative to friction can be improved, thereby improving wear resistance.

[0088] [Other implementation methods or variations]

[0089] In the above embodiments, both the tip and the core of the electronic pen core are made of a filler mixed with resin. However, it is also possible to make only the tip of the core core of the electronic pen core of a filler mixed with resin, which is a fibrous material mixed into the base resin.

[0090] Furthermore, in the above embodiments, the tip and the core of the electronic pen core are both circular in cross-section, but it is not limited to a circular cross-section; it can also be, for example, a polygonal shape.

[0091] Furthermore, while the electronic pen core described in the above embodiment is designed for electromagnetic induction, it can also be designed for electrostatic capacitance (active electrostatic capacitance). However, in this case, conductive materials such as conductive metal powder are mixed into the matrix resin of the electronic pen core, thereby giving the core a conductive structure.

[0092] Explanation of reference numerals in the attached figures

[0093] 1…electronic pen, 10, 10A…electronic pen core, 11, 11A…tip, 12, 12A…axis, 13…cylindrical outer skin, 100…surface sheet, 200…mold, RS…filler mixed with resin, FI…fibrous material.

Claims

1. A core for an electronic pen, characterized in that it is integrally formed by a tip portion that contacts the position indicator input surface and a rod-shaped central portion, wherein... At least the tip portion is composed of a filler incorporated into the resin, which is achieved by incorporating a fibrous material with a hardness higher than that of the matrix resin into the matrix resin as a filler. Both the tip and the core are composed of the filler mixed with resin. The density of the fibrous material at the tip is higher than the density of the fibrous material at the core. The central portion is thinner than the tip portion.

2. The electronic pen core according to claim 1, characterized in that, The fibrous material is configured to be shorter than the thickness of the tip and the axis.

3. The electronic pen core according to claim 2, characterized in that, The length direction of the fibrous material becomes an inclined direction along the shape of the tip surface at the tip.

4. The electronic pen core according to claim 1, characterized in that, The fibrous material has a lower hardness than glass fiber or carbon fiber.

5. The electronic pen core according to claim 4, characterized in that, The fibrous material is a fiber of poly(p-phenylene terephthalamide).

6. The electronic pen core according to claim 1, characterized in that, The matrix resin is a resin that is worn down due to friction between the tip and the position indicator input surface.

7. The electronic pen core according to claim 1, characterized in that, The fibrous material is composed of a material whose tensile strength is greater than that of the matrix resin.

8. The electronic pen core according to claim 1, characterized in that, The core portion is formed by being wrapped with an outer skin, which is made of a material with a hardness higher than that of the matrix resin.

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