Electronic pen and core body for electronic pen

Abstract

The present invention achieves: a core body for an electronic pen, which has an excellent characteristic for detecting a specified position and an inclination, maintains sufficient strength, has a simple structure, and is easy to manufacture; and an electronic pen using the core body.　This electronic pen comprises a case (2), a core body (4), and a signal generation circuit (8). The core body (4) is installed in the case (2) such that a tip portion in an axial direction projects from an opening (H) of the case (2). The signal generation circuit (8) generates a signal to be transmitted from the core body (4). The core body (4) is constituted by a core rod (41), and a protection member (42) covering a pen tip portion (41a) and a shaft portion (41b) of the core rod (41). An intermediate portion (43) having permittivity different from the protection member (42) is provided around a side surface of the shaft portion (41b) of the core rod (41) so as to separate the shaft portion (41b) from the protection member (42).

Description

[Technical Field]

[0001] The present invention relates to an electronic pen used as a position indicator for a position detection device mounted on an information processing device such as a tablet PC (Personal Computer), and to a core body for the electronic pen used in the electronic pen. [Background technology]

[0002] Position detection devices and position indicators are used as input devices for various electronic devices, such as high-function telephone terminals known as smartphones and tablet PCs (Personal Computers). Position indicators are generally pen-shaped and are called electronic pens or styluses. There are various types of position detection devices and position indicators. Among them, the active capacitance type (AES (Active Electrostatic) type) sends (radiates) a signal from an oscillator circuit mounted on the electronic pen from the tip of the pen toward the position detection sensor of the position detection device, thereby indicating the position on the position detection sensor.

[0003] The position detection sensor used in the active capacitance type position detection device is configured by arranging linear transparent electrodes in the X-axis direction (horizontal direction) and Y-axis direction (vertical direction) on the display screen of a display device such as an LCD (Liquid Crystal Display). The position detection device detects the position indicated by the electronic pen according to the positions of the linear transparent electrodes of the position detection sensor that receive the signal (electric field) emitted from the electronic pen.

[0004] In the case of active capacitance electronic pens, as described above, signals from the signal generating circuit installed in the electronic pen are transmitted from the pen tip. Therefore, conventionally, the core body of active capacitance electronic pens has been a cylindrical rod-shaped body made entirely of conductive material. With this conventional electronic pen, when the electronic pen is tilted and the pen tip is moved, a wavy phenomenon appears in the received signal detected by the position detection device, resulting in poor linearity of the detected pointing position. This is because the signal (electric field) from the signal generating circuit is emitted not only from the pen tip (tip) of the core body of the electronic pen, but also from the shaft part of the core body.

[0005] That is, as the electronic pen moves, a signal (electric field) emitted from the shaft of the core body is received by the linear transparent electrode of the position detection sensor. In this case, the signal is received strongly when the shaft of the core body is on the transparent electrode, and weakly when it is off the transparent electrode, resulting in a wavy phenomenon appearing in the received signal received by the transparent electrode. This causes the linearity of the detection characteristic of the pointing position when the electronic pen is tilted to deteriorate.

[0006] Therefore, in order to improve the linearity of the detection characteristics of the indicated position, it has been considered to make the tip of the core body of an active capacitance type electronic pen spherical and make the shaft as thin as possible, as disclosed in Patent Document 1, which will be described later.Also, as disclosed in Patent Document 2, it has been considered to configure the core body by making the core rod made of a conductive material tapered from the pen tip side to the rear end side and covering the periphery with a protective member. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 5761773 [Patent Document 2] International Publication No. 2020 / 054163 Summary of the Invention [Problem to be solved by the invention]

[0008] In the case of the invention disclosed in Patent Document 1, because the conductive shaft is thin, tilting the pen has almost no effect on the signal (electric field) emitted from the shaft, and the spherical pen tip is primarily involved in emitting the signal (electric field), so the range of the received signal does not widen and good linear characteristics are obtained. However, in the case of the invention disclosed in Patent Document 1, in order to obtain sufficient linear characteristics, the electrode parts at the front and rear ends must be connected by the thin shaft and then covered with resin by injection processing, which makes manufacturing difficult.

[0009] Furthermore, in the case of the invention disclosed in Patent Document 2, the writing feel can be changed by changing the material of the core rod formed of a conductive material to a softer material. In this case, the strength of the core body is reduced, so the core rod made of conductive material is wrapped in resin to reinforce it. To ensure linearity, the core rod becomes thinner toward its rear end. For this reason, it is necessary to maintain sufficient strength by covering the rear end of the core rod made of conductive material with a protective material, for example. Furthermore, the core body of an electronic pen is the part that directly contacts the operating surface, and while it is thin and short when viewed from the perspective of the entire electronic pen, it is necessary for it to have the desired strength and be easy to manufacture.

[0010] In view of the above, an object of the present invention is to provide a core body for an electronic pen that has good detection characteristics for the indicated position and tilt, has sufficient strength, is simple in configuration, and is easy to manufacture, and an electronic pen that uses this core body. [Means for solving the problem]

[0011] In order to solve the above problems, a cylindrical housing having an opening at one end in an axial direction; a core body attached to the inside of the housing so that a tip portion in an axial direction thereof protrudes from the opening of the housing; a signal generating circuit that generates a signal to be sent from the core body; Equipped with The core body is a core rod having electrical conductivity and receiving a signal from the signal generating circuit; a protective member covering the core rod, The core rod comprises a pen tip portion at the front end, a mounting portion at the rear end, and a shaft portion connecting the pen tip portion and the mounting portion, an intermediate portion having a dielectric constant different from that of the protective member, the intermediate portion being provided around the side surface of the shaft portion of the core rod so as to be spaced from the protective member; The present invention provides an electronic pen characterized by the above features.

[0012] This electronic pen includes a housing, a core, and a signal generating circuit. The core is attached to the interior of the housing so that its axial tip protrudes from the opening of the housing, and the signal generating circuit generates a signal to be sent from the core. The core is configured with an intermediate section provided around the axial portion of the core rod, and a protective member provided around the intermediate section. Because the intermediate section and the protective member have different dielectric constants, a double capacitor is provided around the axial portion of the core rod, suppressing the signal (electric field) radiated from the axial portion of the core rod and resulting in an electronic pen with good pointing position and linearity characteristics. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 2 is a diagram illustrating an example of the configuration of an electronic pen according to an embodiment. [Figure 2] 1A and 1B are diagrams illustrating a main part of an electronic pen according to an embodiment. [Figure 3] 3A and 3B are diagrams illustrating an example of the configuration of a core body of an electronic pen according to an embodiment. [Figure 4] 10A and 10B are diagrams illustrating other configuration examples of the core rod of the core body of the electronic pen according to the embodiment. [Figure 5] 10A and 10B are diagrams illustrating another example of the configuration of the protection member for the core body of the electronic pen according to the embodiment. [Figure 6] 10A and 10B are diagrams illustrating another example of the configuration of the electronic pen according to the embodiment. [Figure 7] 10A and 10B are diagrams illustrating another example of the configuration of the core body of the electronic pen according to the embodiment. [Figure 8] 10A and 10B are diagrams illustrating another example of the configuration of the core body of the electronic pen according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of an electronic pen and a core body for the electronic pen according to the present invention will be described with reference to the drawings. The electronic pen of the embodiment described below is an active capacitance type that sends a signal from the electronic pen side and detects the indicated position according to the position on the position detection sensor that receives the signal.

[0015] [Configuration example of an active capacitive electronic pen] FIG. 1 is a diagram illustrating an example of the configuration of an electronic pen 1 according to this embodiment, and for the purpose of explanation, a part of the case (housing) 2 of the electronic pen 1 is cut away to show its interior. FIG. 2 is a diagram illustrating the main parts of the electronic pen 1. Specifically, FIG. 2(A) is an enlarged cross-sectional view of the main parts of the pen tip side of the electronic pen 1, which are not shown in FIG. 1. FIG. 2(B) is a diagram that schematically illustrates the parts of the electronic pen 1 that realize the functions of pen pressure detection and signal transmission.

[0016] 1, electronic pen 1 includes case (housing) 2 that is elongated in the axial direction (direction along the axis) and has a cylindrical shape with one end in the axial direction facing the pen tip and having an opening, and the other end in the axial direction being closed. This case 2 is made of a conductive material, in this example, anodized aluminum, and is composed of a cylindrical case main body 21 with an internal hollow, and a front cap 22 and a rear cap 23 that are coupled to this case main body 21. The case 2 is formed by fitting the front cap 22 and the rear cap 23 to the case main body 21.

[0017] As shown in Fig. 2(A), front cap 22 is configured as a cylindrical body having a through-hole 22a in the axial direction, and the external shape of the portion on the pen tip side of electronic pen 1 is tapered so that the outer diameter becomes smaller as it approaches the pen tip. The end of front cap 22 on the pen tip side forms opening H of through-hole 22a. As shown in Fig. 1, the hollow portion of case 2 houses board holder 3 for holding mounted components such as printed circuit board 8 and battery 5, and also houses core holder (core holding portion) 6 and pressure-sensitive component (pen pressure detection portion) 7, as shown in Fig. 2(A).

[0018] As shown in Figures 1 and 2(A), the core body 4 is inserted into the through-hole 22a through the opening H of the front cap 22 and attached to the core body holder 6 inside the case 2. The core body 4 can also be removed from the core body holder 6. In other words, the core body 4 can be attached and detached to and from the case 2. The core body 4, which will be described in detail later, is made up of a core rod 41 made of a conductive material and a protective member 42 made of a non-conductive material, and has a structure in which a space (air layer) 43 is provided between the core rod 41 and the protective member 42.

[0019] The board holder 3 is made of insulating resin, such as a liquid crystal polymer, and when housed in the hollow portion of the case 2, has a configuration in which a pressure-sensing component holding portion 3a and a printed circuit board mounting base portion 3b are continuous along the axial direction of the electronic pen 1, as shown in Fig. 2(A). The pressure-sensing component holding portion 3a is cylindrical with a hollow portion for housing the pressure-sensing components 7 (multiple components for detecting writing pressure), and has an outer diameter smaller than the inner diameter of the through-hole 22a of the front cap 22. The printed circuit board mounting base portion 3b is boat-shaped for placing and holding the printed circuit board 8, and specifically, has a shape similar to a cylindrical body cut approximately in half along the axial direction.

[0020] The board holder 3 is arranged so that the pressure-sensitive component holding portion 3a faces the core rod 41, and the entire pressure-sensitive component holding portion 3a and printed circuit board mounting portion 3b are housed in the case 2 and fixed so as not to move. Also, as shown in Fig. 2(A), a core body holder 6 that holds a core body 4 is connected to the pressure-sensitive component holding portion 3a of the board holder 3, so that pressure (writing pressure) applied mainly to the core rod 41 of the core body 4 is transmitted to the pressure-sensitive component 7 in the pressure-sensitive component holding portion 3a.

[0021] As shown in Figure 1, a terminal conductor 51 is provided on the end of the printed circuit board mounting base portion 3b of the board holder 3 opposite the pressure-sensing component holding portion 3a. This terminal conductor 51 electrically abuts against the positive terminal 5a of the battery 5 and is electrically connected to the copper foil pattern of the power line of the printed circuit board 8. A coil spring terminal 52 made of conductive metal is provided at the portion of the rear cap 23 that fits into the case body 21, and electrically connects to the negative terminal 5b of the battery 5. As shown in Figure 1, the battery 5 is inserted into the case 2 so that the positive terminal 5a is connected to the terminal conductor 51. The rear cap 23 is then fitted into the case body 21 so that the coil spring terminal 52 presses against the negative terminal 5b of the battery 5.

[0022] In this embodiment, the case body 21, which is made of a conductive material, is electrically connected to the earth conductor of the printed circuit board 8. Because the rear cap 23 and case body 21 are made of a conductive material, the negative terminal 5b of the battery 5 is electrically connected to the earth conductor of the printed circuit board 8 via the rear cap 23 and case body 21. Meanwhile, the positive terminal 5a of the battery 5 is connected to the copper foil pattern of the power supply line of the printed circuit board 8 via the terminal conductor 51. In this way, the voltage of the battery 5 is supplied as the power supply voltage for the circuits formed on the printed circuit board 8.

[0023] A circuit section consisting of a signal generating circuit 8S, an IC (Integrated Circuit) 10, and their peripheral circuit components is provided on the printed circuit board 8. The signal generating circuit 8S generates a signal to be sent from the core 41 of the electronic pen 1. The IC 10 constitutes a control circuit that controls the transmission of the signal from the signal generating circuit 8S to the core 41. The peripheral circuit section includes push switches (side switches) 11 and 12, which are operated via operation units 11a and 12a. Also connected to the printed circuit board 8 are a conductive terminal member 14 that connects the core 41 and the signal generating circuit 8S, and a conductive terminal member 15 that transmits the detection output of the writing pressure from the pressure-sensing component 7.

[0024] 2(A), the core body 4 is fitted into a core body holder 6 made of a conductive material via a conductive elastic member 9, and is thereby connected and held to the core body holder 6. The core body holder 6 is fitted into a holding member 73 of the pressure-sensing component 7 in the pressure-sensing component holding portion 3a of the board holder 3, so that the pressure (writing pressure) applied to the core body 4 is transmitted to the pressure-sensing component 7.

[0025] In this case, the core holder 6 is configured to be constantly biased toward the core rod 41 with respect to the board holder 3 by a coil spring 13, which is an example of an elastic member made of a conductive material such as a conductive metal, and is provided between the core holder 6 and the board holder 3. The coil spring 13, together with the conductive terminal member 14, constitutes an electrical connection member for transmitting to the core rod 41 a signal from the signal generating circuit 8S, the transmission of which is controlled by the IC 10 disposed on the printed circuit board 8. For this reason, a metal plate 13a is provided at the end of the pressure-sensing component holding portion 3a of the board holder 3 on the pen tip side, and electrically connects the coil spring 13 and the conductive terminal member 14.

[0026] 2(B), the signal from the signal generating circuit 8S passes through the conductive terminal member 14, metal plate 13a, coil spring 13, core body holder 6, and core rod 41 in this order, and is then transmitted from the core rod 41. The conductive terminal member 14, coil spring 13, metal plate 13a, core body holder 6, and core rod 41 constitute the electrical connection members, and form a transmission path for the position indication signal from the signal generating circuit 8S of the printed circuit board 8.

[0027] The pressure-sensitive component (pen pressure detection unit) 7 of this embodiment is a variable capacitance capacitor whose capacitance changes in response to the pen pressure applied to the core rod 41. As shown in FIG. 2(A), the pressure-sensitive component 7 is made up of multiple components: a dielectric 71, a terminal member 72, a holding member 73, a conductive member 74, and an elastic member 75. The terminal member 72 is made of a conductive material and constitutes a first electrode of the variable capacitance capacitor made up of the pressure-sensitive component 7. The conductive member 74 is made of, for example, conductive rubber, and the elastic member 75 is made of a coil spring made of a conductive material. The conductive member 74 and the elastic member 75 are electrically connected to constitute a second electrode of the variable capacitance capacitor.

[0028] As a result, the capacitance of the variable capacitor formed between the terminal member 72 constituting the first electrode and the conductive member 74 constituting the second electrode changes according to the pressure applied to the core rod 41. This change in capacitance of the variable capacitor is supplied to the IC 10 provided on the printed circuit board 8 from the pressure-sensing component 7 through the conductive terminal member 15, and the writing pressure is detected by the IC 10.

[0029] That is, in the electronic pen 1 of this embodiment, as shown in Fig. 2(A), the core 4 is attached to the core holder 6 inside the case 2 and is movable in the axial direction. As a result, the core 4 is pushed toward the inside of the case 2 in response to the writing pressure applied to the core rod 41 by the user, and in response, the core rod 41 and the core holder 6 press the pressure-sensing component 7, making it possible to detect the writing pressure. Furthermore, when the writing pressure applied to the core rod 41 is released, the action of the coil spring 13 described above allows the core holder 6 and the core 4 to return to the initial state shown in Fig. 2(A).

[0030] The IC10 of the electronic pen 1 controls the position detection sensor to send a burst signal (position indication signal) for coordinate detection (position detection) in response to a signal from the signal generating circuit 8S. This allows the position detection sensor to detect the position indicated by the electronic pen 1 on the position detection sensor. Furthermore, a circuit including the IC10 configured on the printed circuit board 8 of the electronic pen 1 detects writing pressure based on the capacitance of the pressure-sensing component 7 during the period in which the burst signal is being sent. After the burst signal sending period ends, the IC10 modulates the signal from the signal generating circuit 8S in response to the detected writing pressure and sends an encoded signal from the core rod 41 to notify the position detection sensor of the writing pressure. This allows the position detection sensor to detect the writing pressure applied to the core body 4 of the electronic pen 1.

[0031] In this way, the electronic pen 1 of this embodiment indicates a position on the position detection sensor to the position detection sensor, and also detects the writing pressure applied to the core rod 41 and notifies the position detection sensor. Furthermore, the electronic pen 1 of this embodiment is characterized by the configuration of the core body 4, which maintains good linear characteristics for position detection and enables the position detection sensor to properly detect the indicated position. Furthermore, the core body 4 used in the electronic pen 1 of this embodiment has sufficient strength as a core body, has a simple configuration, and can be easily manufactured.

[0032] [Example of core body 4 configuration] Fig. 3 is a diagram illustrating an example of the configuration of the core body 4 of the electronic pen 1. In Fig. 3, Fig. 3(A) is an external view of the protective member 42 of the core body 4, and Fig. 3(B) is an external view of the core rod 41 of the core body 4. The core body 4 of this embodiment is composed of two members, the core rod 41 (Fig. 3(B)) and the protective member 42 (Fig. 3(A)), as shown in Fig. 2(A) and Fig. 3.

[0033] The core rod 41 is a conductive rod-like body that is cylindrical with portions of varying thickness except for the tip. The core rod 41 is formed, for example, from a metal material. In this embodiment, the core rod 41 is formed using stainless steel (SUS (Steel Special Use Stainless)) or brass. As shown in FIG. 3(B), the core rod 41 consists of three portions: a nib portion 41a, a shaft portion 41b, and an attachment portion 41c. The nib portion 41a is an egg-shaped (elongated sphere) portion at the tip of the core rod 41, and is shaped to efficiently emit a position indication signal toward the position detection sensor.

[0034] The shaft portion 41b is a portion that connects the nib portion 41a and the attachment portion 41c, and as shown in FIG. 3(B), is made up of three portions: a front shaft portion 41b1, an intermediate shaft portion 41b2, and a rear shaft portion 41b3. The rear shaft portion 41b3 forms a fitting portion with the protective member 42, which will be described in detail later. For this reason, hereinafter, the rear shaft portion 41b3 will be referred to as the fitting portion 41b3. In this embodiment, as shown in FIG. 3(B), the diameter of the widest portion of the nib portion 41a (hereinafter referred to as the wide portion) is L1, and the diameter of the fitting portion 41b3 of the shaft portion 41b is L2. The diameter L1 of the wide portion of the nib portion 41a is shorter than the diameter L2 of the fitting portion 41b3 (L1 <L2)。

[0035] In this embodiment, the side surface of the fitting portion 41b3 is knurled at the portion indicated by the symbol RT in Fig. 3(B). Knurling is a fine uneven machining applied to metal and is also called "nurling". Since knurling has an anti-slip effect, when the mandrel 41 is attached to the protective member 42 as described later, the mandrel 41 can be prevented from easily coming off the protective member 42.

[0036] Also, the diameter of the front shaft portion 41b1 is gradually increased from the pen tip side toward the rear end side. Similarly, the diameter of the intermediate shaft portion 41b2 is gradually increased from the pen tip side toward the rear end side. Also, at the connection portion between the front shaft portion 41b1 and the intermediate shaft portion 41b2, the change in diameter is large. The diameter of any part of the front shaft portion 41b1 is shorter than the diameter L1 of the pen tip portion 41a. Also, the diameter of any part of the intermediate shaft portion 41b2 is shorter than the diameter L2 of the fitting portion 41b3. Therefore, if the diameter of the front shaft portion 41b1 is Lb1 and the diameter of the intermediate shaft portion 41b2 is Lb2, the shaft portion 41b has a structure in which the diameter gradually increases from the tip side toward the rear end side, such as Lb1 < Lb2 < L2.

[0037] As described using Figs. 2(A) and (B), the mounting portion 41c is a portion where the mandrel 41 is mounted to the core holder 6 provided inside the electronic pen 1 via the conductive elastic member 9. That is, by pushing the mounting portion 41c of the mandrel 41 into the cup portion of the core holder 6 to which the conductive elastic member 9 is attached, it can be mounted to the electronic pen 1, and by pulling it out, the core 4 can be removed from the electronic pen 1. That is, the core 4 composed of the mandrel 41 and the protective member 42 described later is detachable from the electronic pen 1 via the mounting portion 4xc of the core 4.

[0038] As shown in Figures 2(A) and 2(B), the protective member 42, another component of the core 4, covers the sides of the nib portion 41a and the shaft portion 41b of the core 41, protecting the core 41 and ensuring a good writing feel. In this embodiment, the protective member 42 is made of various resin materials, such as polyamide, polycarbonate, modified polyphenylene ether, polybutylene terephthalate, and polyacetal. In this embodiment, the protective member 42 is made of polyacetal. Polyacetal is also known as POM (polyoxymethylene).

[0039] The protective member 42 comprises a tapered tip portion 42a tapering toward the tip and an extension portion 42b extending from the rear end face of the tip portion 42a toward the rear end. An insertion hole 42c is provided on the inside of the protective member 42 in the longitudinal direction, with the rear end face of the extension portion 42b opening. The insertion hole 42c is inserted and fitted with the core rod 41. The longitudinal center of the insertion hole 42c coincides with the longitudinal center (axial center) of the protective member 42. Furthermore, the longitudinal length (total length) LY of the insertion hole 42c of the protective member 42 coincides with the length LY from the tip of the nib portion 41a of the core rod 41 to a position slightly forward of the rear end face of the fitting portion 41b3 of the core rod 41, as shown in Figures 3(A) and (B).

[0040] The inner diameter of insertion hole 42c at a position corresponding to the wide portion of nib portion 41a of core rod 41 is the same as or slightly shorter than L1, and the inner diameter of insertion hole 42c at a position corresponding to fitting portion 41b3 of core rod 41 is the same as or slightly shorter than L2. Insertion hole 42c has a smooth inner wall surface and is a hole portion that tapers from the opening on the rear end toward the tip, making it easy to insert core rod 41.

[0041] As a result, when the core rod 41 is inserted and pushed into the insertion hole 42c of the protective member 42, the portion of the core rod 41 extending from the wide portion of the nib portion 41a toward the tip thereof comes into close contact with the inner wall surface of the tip side of the insertion hole 42c, as shown in FIGS. 2(A) and 2(B). Also, as shown in FIGS. 2(A) and 2(B), the side of the fitting portion 41b3 of the core rod 41 comes into close contact with the inner wall surface around the opening of the insertion hole 42c. This firmly attaches the protective member 42 to the core rod 41. When the core rod 41 is inserted and attached into the insertion hole 42c of the protective member 42 in this way, a space (air layer) 43 is formed between the shaft portion 41b of the core rod 41 and the inner wall surface of the insertion hole 42c, as shown in FIGS. 2(A) and 2(B).

[0042] That is, as described above and shown in Figure 3(A), the insertion hole 42c of the protective member 42 tapers from a portion with a diameter L2 at the rear end to a portion with a diameter L1 at the front end. Also, as described above with reference to Figure 3(B), the core rod 41 has a diameter L2 at the fitting portion 41b3 and a diameter L1 at the wide portion of the nib portion 41a, so that the core rod 41 tapers from the fitting portion 41b3 to the nib portion 41a. Furthermore, the diameter of every portion of the front shaft portion 41b1 is shorter than the diameter L1 of the wide portion of the nib portion 41a, and the diameter of every portion of the intermediate shaft portion 41b2 is shorter than the diameter L2 of the fitting portion 41b3.

[0043] For this reason, suppose the core rod 41 is inserted and pushed into the insertion hole 42c of the protective member 42 and attached to a fixed position. In this case, as shown in FIGS. 2(A) and 2(B), a space (air layer) 43 is created as an intermediate portion between the side surfaces of the front shaft portion 41b1 and the intermediate shaft portion 41b2 of the core rod 41 and the inner wall surface of the insertion hole 42c of the protective member 42. That is, the space (air layer) 43 is provided around the front shaft portion 41b1 and the intermediate shaft portion 41b2, and the protective member 42 is provided outside the space 43. Both the space (air layer) 43 and the protective member 42 made of polyacetal can be considered to be dielectrics, which are materials whose dielectric properties are superior to their electrical conductivity, and their respective dielectric constants are different.

[0044] That is, in the case of the core body 4 of this embodiment, as shown in FIG. 2(A), a space (air layer) 43 exists around the front shaft portion 41b1 and the intermediate shaft portion 41b2 of the core rod 41, and a protective member 42 exists outside the space (air layer) 43. Therefore, the front shaft portion 41b1 and the intermediate shaft portion 41b2 of the core rod 41 have a doubly enclosed structure with the space (air layer) 43 and the protective member 42. In other words, two capacitors are provided around the front shaft portion 41b1 and the intermediate shaft portion 41b2 of the core rod 41: one capacitor using the space (air layer) 43 as a dielectric, and another capacitor using polyacetal (protective member 42) as a dielectric. In this case, because the air layer and polyacetal have different dielectric constants, two capacitors using dielectrics with different dielectric constants are provided.

[0045] 2(A) and 2(B), in the area from the wide portion of the nib portion 41a of the core rod 41 toward the tip, the inner wall surface of the protective member 42 and the side surface of the nib portion of the core rod 41 are in close contact with each other, so no space is created, and only the tip portion 42a of the protective member 42 exists. In other words, in the area from the wide portion of the nib portion 41a of the core rod 41 toward the tip, a single capacitor is provided, with polyacetal (protective member 42) as the dielectric.

[0046] As a result, the signal (electric field) radiated from the portion of the core rod 41 closer to the tip than the wide portion of the nib portion 41a is radiated relatively efficiently only through the protective member 42. Therefore, the signal (electric field) radiated through the portion of the core rod 41 closer to the tip than the wide portion of the nib portion 41a becomes stronger. However, the signal (electric field) radiated from the front shaft portion 41b1 and intermediate shaft portion 41b2 of the core rod 41 is suppressed by the double capacitor of the space 43 and the protective member 42. Therefore, the signal (electric field) radiated through the front shaft portion 41b1 and intermediate shaft portion 41b2 of the core rod 41 becomes weaker. Moreover, because the diameter of the front shaft portion 41b1 of the core rod 41 is shorter than the diameter of the wide portion of the nib portion 41a, the radiated signal (electric field) can be made smaller than the signal (electric field) radiated from the nib portion 41a.

[0047] That is, the signal (electric field) radiated from the portion of the core rod 41 closer to the tip than the wide portion of the pen tip portion 41a is increased, and the signal (electric field) radiated from the front shaft portion 41b1 and the intermediate shaft portion 41b2 of the core rod 41 is reduced. In this way, the signal (electric field) leaking in from the front shaft portion 41b1 and the intermediate shaft portion 41b2 of the core rod 41 can be suppressed. This improves the linearity of the detection characteristic for the pointed position when the electronic pen 1 is tilted, and prevents the position detection device from misaligning the pointed position by the electronic pen 1.

[0048] In addition, in the conventional method, the core rod 41 is inserted into the mold and fixed in a fixed position, and polyacetal is injected into the mold. By doing so, The core is made by injection molding. 4 However, in the core body 4 of this embodiment, the core rod 41 and the protective member 42 are formed separately, and the core body 4 can be formed by a press-fit method in which the core rod 41 is inserted into the insertion hole 42c of the protective member 42, so that the core body 4 itself can be easily manufactured. The core rod 41 and the protective member 42 may be formed by methods suitable for each.

[0049] As described with reference to FIGS. 2 and 3, the core 4 of this embodiment is configured such that the protective member 42 covers the nib portion 41a and shaft portion 41b of the core 41. This allows the thickness of the extension 42b of the protective member 42 at the shaft portion 41b to be increased, thereby increasing the diameter of the portion of the core 4 that protrudes from the opening H of the front cap 22. This increases the strength of the extension 42b of the core 4 and the shaft portion 41b of the core 41, as shown in FIGS. 1 and 2(A). Furthermore, as shown in FIG. 2(A), the gap between the side surface of the extension 42b of the protective member 42 and the inner wall surface of the front cap 22 is extremely small. This effectively prevents the core 4 from wobbling during writing and protects the core 4 even when force is applied to the tip 42a of the core 4 in a direction intersecting the axial direction.

[0050] Furthermore, to ensure proper detection of writing pressure, the core 4 is slidable in the axial direction. However, the rear end surface 42T of the tip 42a of the protective member 42 and the tip surface 22T of the front cap 22 face each other with a small gap between them. Therefore, even if a large force is applied to the tip 42a in the axial direction of the electronic pen 1, such as when a large writing pressure is suddenly applied or the electronic pen 1 is dropped from a desk to the floor, the rear end surface 42T of the tip 42a and the tip surface 22T of the front cap 22 will abut against each other. This prevents the core 4 from being pushed into the case 2 of the electronic pen 1 more than necessary, which could result in damage to the pressure-sensing component 7.

[0051] [Effects of the embodiment] The core body 4 of the above-described embodiment has a space (air layer) 43 as an intermediate portion around the shaft portion 41b of the core rod 41, and an extension portion 42b of the protective member 42 around the space 43. Because the space 43 and the protective member 42 have different dielectric constants, a double capacitor is provided around the shaft portion 41b of the core rod 41, and the signal (electric field) radiated from the shaft portion 41b of the core rod 41 can be suppressed. This suppresses unnecessary electric fields from the shaft, thereby realizing a core body for an electronic pen with excellent pointing position and linearity characteristics when the electronic pen is tilted. Furthermore, because the configuration of the core body 4 itself is simple, a core body for an electronic pen that is easy to manufacture can be realized. Therefore, by using the core body 4 of the above-described embodiment, an electronic pen with excellent pointing position and tilt detection characteristics can be realized.

[0052] [Variations] <Another example of core rod 41> FIG. 4 is a diagram illustrating another example of the core rod 41 of the core body 4. As shown in FIG. 4(A) of the core rod 41A, the shaft portion 41bA connecting the nib portion 41aA and the mounting portion 41cA may be composed of a front shaft portion b1A and a fitting portion b3A. That is, the shaft portion 41bA has a single-stage straight configuration, rather than being divided into a front shaft portion 41b1 and an intermediate shaft portion 41b2, as in the shaft portion 41b shown in FIGS. 2 and 3. In this way, the shaft portion of the core rod can have a single stage configuration excluding the mounting portion 41cA, as shown in FIG. 4(A), or it can have a two-stage or more-stage configuration excluding the mounting portion 41cA, as shown in FIGS. 2 and 3.

[0053] As shown in Fig. 4(B), the core rod 41B comprises a nib portion 41aB, a shaft portion 41bB, and a mounting portion 41cB, and the shaft portion 41bB comprises a front shaft portion b1B and a fitting portion b3B. The shaft portion 41bB and the mounting portion 41cB are configured in substantially the same manner as the core rod 41A of Fig. 4(A), but the shape of the nib portion 41aA is spherical. In other words, the shape of the nib portion 41a of the core rod 41 is not limited to an egg shape, and can be various shapes such as a sphere, a bullet shape with a dome-shaped tip, or an arrowhead shape with a sharpened tip, taking into account the state of radiation of the signal (electric field).

[0054] 4(C), the pen tip portion 41aC, the shaft portion 41bC, and the mounting portion 41cC are integrally formed from a metal material, but the fitting portion 44 may be formed as a separate part. In this case, the fitting portion 44 can be formed from a metal material, but it can also be formed into a thick cylindrical shape from another material such as hard rubber. The pen tip portion 41aC, the shaft portion 41bC, and the mounting portion 41cC of the core rod 41C are integrally formed from a metal material and are conductive, so even if the fitting portion 44 is formed from a non-conductive material, the conductivity of the core rod 41C is not lost.

[0055] The core rods 41A, 41B, and 41C described using Fig. 4 are just examples, and various other modifications are possible. In short, the core rod is conductive from its tip to its rear end, and can have various shapes that can provide an intermediate portion such as a space (air layer) 43 between the axial center portion and the protective member 42 when inserted into the insertion hole 42c of the protective member 42 and attached in a fixed position.

[0056] <Other Examples of Protective Member 42> Fig. 5 is a diagram illustrating another example of the configuration of the protective member 42 of the core body 4. As explained with reference to Fig. 3, the protective member 42 is formed using a resin material, and in this embodiment, it has been explained as being formed from polyacetal. However, this is not limitative. The protective member can also be formed using a technique called two-color molding (double molding), which creates a single molded product using two types of resin materials.

[0057] Protective members 42A (FIG. 5(A)), 42B (FIG. 5(B)), and 42C (FIG. 5(C)) shown in FIG. 5 are formed to have the same shape as protective member 42 of core body 4 shown in FIGS. 1 to 3. That is, protective members 42A, 42B, and 42C shown in FIG. 5 have tip portions 42aA, 42aB, and 42aC, extension portions 42bA, 42bB, and 42bC, and insertion holes 42cA, 42cB, and 42cC, similar to protective member 42 described above. However, all of them are formed by two-color molding using two types of resin, polyacetal and elastomer.

[0058] In the protective member 42A shown in FIG. 5(A), most of the tip portion 42aA and the extension portion 42bA are made of polyacetal, and the very tip of the tip portion 42aA (the portion that comes into contact with the operating surface) is provided with a dome-shaped contact portion 42x made of elastomer. Elastomer refers to a soft polymer material with elasticity like rubber, and its softness, elasticity, and other physical properties can be adjusted by varying the material blend. In this way, by providing the elastomer contact portion 42x on the tip portion 42aA, a desired writing feel can be achieved.

[0059] The writing feel refers to the tone and feel of writing when the electronic pen is brought into contact with the operation surface, i.e., the feeling transmitted to the user's hand through the electronic pen. Therefore, by providing contact portion 42x made of elastomer, the electronic pen comes into contact with the operation surface more softly when writing, providing a writing feel.

[0060] In the case of the protective member 42A shown in FIG. 5(A), the tip side of the polyacetal tip portion 42aA and the elastomer contact portion 42x form a double capacitor. Because the contact portion 42x is thin, there is a possibility that the signal (electric field) radiated from the contact portion 42x side may be slightly suppressed. Therefore, as shown in FIG. 5(B), the protective member 42B has a thicker contact portion 42y of the tip portion 42aB. This ensures that only the contact portion 42y made of elastomer is present on the pen tip side, preventing the signal (electric field) radiated from the contact portion 42y side from being suppressed and achieving a desired writing feel.

[0061] 5(C), a portion of the tip 42aC of the protective member 42C located at least further toward the tip than the wide portion of the nib 41a of the core 41 is configured to be the contact portion 42z of the elastomer. In this way, the signal (electric field) emitted from the nib 41a of the core 41 can be efficiently emitted without being significantly suppressed, and a desired writing feel can also be achieved.

[0062] Protective members 42A, 42B, and 42C described using Figure 5 are just examples, and various other modifications are possible. In short, the protective member may be configured to radiate the signal (electric field) from the pen tip portion of the core rod without attenuation, and to attenuate and radiate the signal (electric field) from the shaft portion of the core rod by passing through an intermediate portion such as a space (air layer) and the protective member.

[0063] The contact portions 42x, 42y, and 42z attached to the tip by two-color molding may be conductive, which allows a strong electric field to be emitted from the core body.

[0064] <Other configuration examples of electronic pen 1> Fig. 6 is a diagram illustrating another example of the configuration of the electronic pen 1. In Fig. 6, parts configured in the same manner as the electronic pen 1 shown in Fig. 2 are given the same reference numerals, and detailed descriptions of these parts will be omitted to avoid duplication. In the case of the electronic pen 1 of the embodiment described above, as shown in Figs. 1 and 2, the entire tip portion 42a of the protective member 42 of the core body 4 protrudes from the opening H of the front cap 22 of the case 2. However, the present invention is not limited to this.

[0065] The core body 4X of the electronic pen 1A shown in Fig. 6 is configured using, for example, the core rod 41A shown in Fig. 4(A) and a protective member 42X, and a space (air layer) 43X is provided around the shaft portion 41b1A of the core rod 41A. However, as shown in Fig. 6, the protective member 42X is provided with a side portion 42Xa1 in which the rear end side of the tip portion 42Xa is parallel to the axis. Of course, the inside of the core body 4X can also be configured in the same way as the core body 4 of the above-mentioned embodiment.

[0066] 6, the opening HA of the front cap 22A is wider than the opening H of the front cap 22 of the electronic pen 1 shown in FIG. 2. The opening HA of the front cap 22A has a shape similar to the rear end surface 42XT of the protective member 42X at its tip end, but the diameter of the opening HA at the tip end is larger than the rear end surface 42XT of the protective member 42X. 42X The length of the protective member 42X is slightly longer than the rear end surface 42XT of the front end portion 42Xa of the protective member 42X. As a result, the core body 4X is configured such that the side surface portion 42Xa1 on the rear end side of the front end portion 42Xa of the protective member 42X fits into the opening HA of the front cap 22A.

[0067] However, in the case of the front cap 22A of the electronic pen 1A shown in FIG. 6, a ring-shaped protruding portion 22P that protrudes inward is provided at a position slightly rearward from the tip of the front cap 22A. A tip surface 22Px of this protruding portion 22P faces a rear end surface 42XT of a tip portion 42Xa of the core 4X. When the electronic pen 1A shown in FIG. 6 is not in use, a small gap is left between the tip surface 22Px of the protruding portion 22P and the rear end surface 42XT of the core 4X. Therefore, in the case of the electronic pen 1A, when writing pressure is applied to the core 4X, the core 4X is pushed toward the rear end, and when the writing pressure is released, the core 4X is pushed back to its original position.

[0068] Therefore, in the case of the electronic pen 1A shown in FIG. 6, if a large writing pressure is suddenly applied or the electronic pen 1A is dropped, the tip of the core body 4X may be damaged. 42Xa Even if a large axial force is applied to the core 42Xa, the rear end surface 42XT of the tip 42Xa and the tip surface 22Px of the front cap 22A abut against each other. This prevents the core 4X from being pushed into the housing of the electronic pen 1A more than necessary, which can prevent problems such as damage to the pressure-sensing component 7.

[0069] 6, a side surface 42Xa1 at the rear end of the tip 42Xa of the protective member 42X faces the inner wall surface at the tip end of the opening HA of the front cap 22A. This makes it possible to almost completely prevent the lead 4X from rattling during writing, and also makes it possible to prevent the lead 4X from rattling even if a force is applied to the tip 42Xa of the lead 4X in a direction intersecting the axial direction. 4X Furthermore, by narrowing the gap as much as possible between the side surface of the extension 42Xb of the core body 4X and the inner wall surface of the protruding portion 22P of the front cap 22A, the core body 4X can be made stronger against forces in a direction intersecting the axial direction. In this case, the protruding portion 22P of the front cap 22A may be made to extend further in the axial direction, thereby increasing the area facing the side surface of the extension 42Xb of the core body 4X.

[0070] <Other configuration examples of the core body 4> 7 and 8 are diagrams illustrating another example configuration (core body 4Y) of the core body 4 of the electronic pen 1. The core body 4 described above with reference to FIG. 3 is configured from two members: a protective member 42 and a core rod 41. In contrast, the core body 4Y in this example is configured from three members: a tip member 45, an extension member 46, and the core rod 41. In FIG. 7, FIG. 7(A) is an external view of the tip member 45, FIG. 7(B) is an external view of the extension member 46, and FIG. 7(C) is an external view of the core rod 41.

[0071] As can be seen by comparing Figures 3(B) and 7(C), the core rod 41 of the core body 4Y in this example is similar to the core rod 41 of the core body 4 described above. For this reason, the core rod 41 is given the same reference numeral as the core rod 41 shown in Figure 3(C), and a redundant explanation of the core rod 41 will be omitted. The core rod 41 is made of a metal material, and in this example as well, the core rod 41 is made of stainless steel (SUS (Steel Special Use Stainless)) or brass.

[0072] In this example, the tip member 45 and the extension member 46 constitute a portion corresponding to the protective member 42 of the core 4 described above with reference to FIG. 3. As shown in FIG. 7(A), the tip member 45 has a conical appearance with a rounded tip portion, and a large circular bottom opening 45H is provided at the bottom, forming a so-called dome-shaped space inside. The space inside the tip member 45, on the tip side, constitutes a nib fitting portion 451 into which the nib portion 41a of the core rod 41 fits. Furthermore, the space inside the tip member 45, on the bottom side, constitutes an extension member fitting portion 452 into which the front portion of the extension member 46 (the front tapered portion 461, the side groove portion 46G, and a front part of the intermediate portion 462) fit, as described below.

[0073] A ring-shaped inner protrusion 452P is provided on the inner wall surface of the extension member fitting portion 452 on the bottom opening 45H side along the inner edge of the bottom opening 45H. Bottom opening 45HThe outer portion of the tip member 45 is a rear end surface 45T of the tip member that has a thickness in a direction intersecting (in this example, perpendicular to) the axis (central axis of the core body 4Y). When the core body 4Y of this example is attached to the electronic pen 1, the rear end surface 45T of the tip member is the portion that faces the front end surface 22T of the front cap 22 of the case 2, similar to when the core body 4 shown in FIG. 2 is used. In this embodiment, the tip member 45 is made of silicon rubber.

[0074] 7(B), the extension member 46 is cylindrical (pipe-shaped) with a through hole formed in the axial direction (the same direction as the axis), with a front opening 46FH on the front side (near the tip member 45) and a rear opening 46BH on the rear side. The extension member 46 is made up of three sections: a front tapered section 461 having a tapered shape (narrowing shape), an intermediate section 462, and a rear section 463 having a diameter slightly shorter than that of the intermediate section 462, from the front side. A side groove 46G is provided on the side surface (outer wall surface) of the extension member 46 at the boundary between the front tapered section 461 and the intermediate section 462.

[0075] The extension member 46 can be made of the same material as the protective member 42 of the core 4 described above. Specifically, the extension member 46 can be made of various resin materials, such as polyamide, polycarbonate, modified polyphenylene ether, polybutylene terephthalate, and polyacetal. In this embodiment, the extension member 46 is made of polyacetal. As described above, polyacetal is also called POM (polyoxymethylene).

[0076] 7(A) and 7(B), the shape of the extension member fitting portion 452, which is the space inside the tip member 45, and the shape of the front portion of the extension member 46 (the portion consisting of the front tapered portion 461, the side groove portion 46G, and a part of the front side of the intermediate portion 462) are consistent. Therefore, the tip member 45 and the extension member 46 can be joined by inserting and pushing the front tapered portion of the extension member 46 through the bottom opening 45H of the tip member 45. In this case, the inner tip surface 452T of the extension member fitting portion 452 and the tip surface 461T of the extension member 46 abut against each other, and the inner protrusion 452P of the extension member fitting portion 452 of the tip member 45 fits into the side groove portion 46G of the extension member 46. This causes the inner wall surface of the extension member fitting portion 452 of the tip member 45 and the side surface (outer wall surface) of the front portion of the extension member 46 to come into close contact with each other, preventing them from easily coming apart.

[0077] In this way, the joined member formed by joining the tip member 45 and the extension member 46 has the same outer and inner shapes as the protective member 42 shown in FIG. 3(A). As described above, the tip member 45 is made of silicone rubber and is elastic, while the extension member 46 is made of POM and is hard. Therefore, the joined tip member 45 and extension member 46 can be separated by pulling them apart with a certain amount of force. In this way, the tip member 45 and extension member 46 are configured to be detachable.

[0078] As can be seen from Figures 7(A) and (B), the joining member formed by joining the tip member 45 and the extension member 46 has an insertion hole 47h into which the core rod 41 is inserted and attached in the inner longitudinal direction. Insertion hole 3(A), the insertion hole 47h corresponds to the through hole 42c in the protective member 42. The longitudinal center of the insertion hole 47h coincides with the longitudinal center (axial center) of the joining member made up of the tip member 45 and the extension member 46. The longitudinal length (total length) of the insertion hole 47h of the joining member coincides with the length LY from the tip of the nib portion 41a of the core rod 41 to a position slightly forward of the rear end surface of the fitting portion 41b3 of the core rod 41 shown in FIG.

[0079] The inner diameter of the insertion hole 47h of the joining member at a position corresponding to the wide portion of the nib portion 41a of the core 41 is the same as or slightly shorter than L1, and the inner diameter of the insertion hole 47h at a position corresponding to the fitting portion 41b3 of the core 41 is the same as or slightly shorter than L2. The insertion hole 47h has a smooth inner wall surface and is a hole portion that tapers from the opening on the rear end toward the tip, making it easy to insert the core 41.

[0080] When the core rod 41 is inserted and pushed into the insertion hole 47h of the joint member consisting of the tip member 45 and the extension member 46, the portion of the core rod 41 extending from the wide portion of the tip member 41a of the core rod 41 toward the tip comes into close contact with the inner wall surface of the tip side of the insertion hole 47h, as shown in FIG. 8. Also, as shown in FIG. 8, the side of the fitting portion 41b3 at the rear end of the core rod 41 comes into close contact with the inner wall surface around the opening of the insertion hole 47c. This attaches the joint member, in which the tip member 45 and the extension member 46 are joined, to the core rod 41, thereby forming the core body 4Y. Even with the core body 4Y configured in this manner, a space (air layer) 43Y is formed between the shaft portion 41b of the core rod 41 and the inner wall surface of the insertion hole 47h of the joint member, as shown in FIG. 8.

[0081] Thus, even in the case of the core body 4Y of this example, the space (air layer) 43Y and the joint member consisting of the tip member 45 made of silicone rubber and the extension member 46 made of polyacetal can be considered to be dielectrics, which are materials in which dielectric properties predominate over conductivity. The space 43Y and the joint member (mainly the extension member 46) also have different dielectric constants. Therefore, even in the case of the core body 4Y of this example, the signal (electric field) radiated from the front shaft portion 41b1 and the intermediate shaft portion 41b2 of the core rod 41 is suppressed by a double capacitor consisting of the space 43Y and the joint member consisting of the tip member 45 and the extension member 46.

[0082] Therefore, in the case of the core body 4Y of this example, the signal (electric field) radiated through the front shaft portion 41b1 and the intermediate shaft portion 41b2 of the core rod 41 is small. Moreover, since the diameter of the front shaft portion 41b1 of the core rod 41 is shorter than the diameter of the wide portion of the pen tip portion 41a, the radiated signal (electric field) can be made smaller than the signal (electric field) radiated from the pen tip portion 41a.

[0083] In this way, even in the case of the core body 4Y of this example, the signal (electric field) radiated through the portion of the core rod 41 closer to the tip than the wide portion of the pen tip portion 41a can be increased, and the signal (electric field) radiated from the front shaft portion 41b1 and the intermediate shaft portion 41b2 of the core rod 41 can be reduced. In other words, the signal (electric field) leaking in from the front shaft portion 41b1 and the intermediate shaft portion 41b2 of the core rod 41 can be suppressed. As a result, even when the core body 4Y of this example is used for the electronic pen 1, the linearity of the detection characteristic for the pointed position when the electronic pen 1 is tilted can be improved, and the position detection device can prevent the pointed position from being shifted by the electronic pen 1.

[0084] Thus, the core body 4Y of this example can achieve the same effects as the core body 4 described above. Furthermore, the core body 4 of this example is formed by separately forming the core rod 41, the tip member 45, and the extension member 46. In this case, the tip member 45 and the extension member 46 are joined to form a joint member. This joint member corresponds to the protective member 42 of the core body 4 described with reference to FIG. 3. The core body 4Y can be formed by a press-fit method in which the core rod 41 is inserted into the insertion hole 47h of this joint member. Therefore, the core body 4Y itself can be easily manufactured. The core rod 41, the tip member 45, and the extension member 46 can be formed by methods appropriate for each.

[0085] In particular, in the case of the core 4Y of this example, the tip member 45 is made of an elastic material such as silicone rubber, so that a softer writing feel can be realized. Also, by making the tip member 45 of an elastic material such as silicone rubber, the rear end surface 45T of the tip member 45 and the case 2 of the electronic pen 1 can be easily attached to each other. Front cap 22This narrows the gap between the tip end surface 22T of the front cap 22 and the rear end surface 45T of the tip end member 45. If the tip end member 45 is made of an elastic member, it becomes possible to push the core body 4Y toward the rear end to some extent even after the rear end surface 45T of the tip end member 45 and the tip end surface 22T of the front cap 22 come into contact with each other.

[0086] Furthermore, since the electronic pen is used by bringing the pen tip into contact with the operation surface, the pen tip wears due to friction. In the core body 4Y consisting of the tip member 45, the extension member 46, and the core rod 41, it is possible to easily replace only the tip member 45. Therefore, in the case of the core body 4Y, it is only necessary to replace the tip member 45, and the core body 4Y This is more economical than replacing the entire core body 4Y. In other words, a more economically usable core body 4Y for an electronic pen can be realized.

[0087] <Intermediate part replacing space (air layer) 43> In the above-described embodiment, as shown in FIG. 2, a space (air layer) 43 serving as an intermediate portion is provided between the shaft portion 41b (front shaft portion 41b1 and intermediate shaft portion 41b2) of the core rod 41 and the extension portion 42b of the protective member 42. Similarly, in the core body 4X of the electronic pen shown in FIG. 6, a space (air layer) 43X serving as an intermediate portion is provided between the shaft portion 41b1A of the core rod 41A and the extension portion 42Xb of the protective member 42X. Also, in the case of the core body 4Y shown in FIGS. 7 and 8, a space (air layer) 43Y serving as an intermediate portion is formed between the shaft portion 41b of the core rod 41 and the inner wall surface of the insertion hole 47h of the joining member consisting of the tip member 45 and the extension member 46. However, the intermediate portion is not limited to a space (air layer).

[0088] For example, a material with a different dielectric constant than the protective member 42 can be applied to the side surfaces of the front shaft portion 41b1 and the intermediate shaft portion 41b2 of the core rod 41 by various methods such as coating, vapor deposition, fusion bonding, or winding, so as to have the same thickness and at the same position as the space 43. In this way, an intermediate portion made of a material different from the protective member 42 can be provided on the side surfaces of the front shaft portion 41b1 and the intermediate shaft portion 41b2 of the core rod 41. The core rod 41 with the intermediate portion thus provided is inserted into the insertion hole 42c of the protective member 42. This allows the extension portion 42b of the protective member 42 to be positioned outside the intermediate portion, resulting in a structure similar to that of a double capacitor formed around the front shaft portion 41b1 and the intermediate shaft portion 41b2.

[0089] Similarly, the shaft portion 41bA of the core rod 41A shown in Fig. 6 can be provided with an intermediate portion made of a material having a different dielectric constant from that of the protective member 42X, and this can be inserted into the insertion hole of the protective member 42X to form the core body 4X. Also, in the case of the core body 4Y shown in Figs. 7 and 8, Tip Part An intermediate portion may be provided by filling the material with a dielectric constant different from that of the extending member 45 and the extending member 46 .

[0090] In this way, the intermediate portion provided in the core body 4, 4X, 4Y is not limited to the space (air layer) 43, but by constructing the intermediate portion using a material with a different dielectric constant from the protective member 42, 42X, a core body for an electronic pen with good detection characteristics for the pointing position and tilt can be constructed.

[0091] <Other> In the above-described embodiment, the core rod 41 is provided with the fitting portion 41b3, but this is not limiting. The core rod 41 may be configured without the fitting portion 41b3, with the intermediate shaft portion 41b2 extending to the fitting portion 41b3. In this case, instead of the fitting portion 41b3 of the core rod 41, a protruding portion protruding inward is provided at the corresponding portion of the protective member 42 or the extension member 46, i.e., at the opening portion on the rear end side of the protective member 42 or the extension member 46. In this way, the protruding portion of the protective member 42 or the extension member 46 fits into the rear end portion of the intermediate shaft portion 41b2 of the core rod 41, thereby securing the core rod 41 to the protective member 42 or the extension member 46. In this case, a knurling process may be applied to the rear end portion of the intermediate shaft portion 41b2 of the core rod 41, which faces the protruding portion of the protective member 42 or the extension member 46. [Explanation of symbols]

[0092] 1, 1A...electronic pen, 2...case, 21...case body, 22, 22A...front cap, 22a...through hole, H, HA...opening, 22T...tip surface, 22P...extension, 22Px...tip surface, 23...rear cap, 3...board holder, 3a...pressure-sensitive component holding portion, 3b...printed circuit board mounting base portion, 4, 4X, 4Y...core body, 41, 41A, 41B, 41C, 41X...core rod, 41a, 41aA, 41aB, 41aC...pen tip portion, 41b, 41bA, 4 1bB, 41bC, 41b1A...shaft portion, 41b1, b1A, b1B...front shaft portion, 41b2...intermediate shaft portion, 41b3, b3A, b3B...fitting portion (rear shaft portion), 41c, 41cA, 41cB, 41cC...mounting portion, 42, 42A, 42B, 42C, 42X...protective member, 42a, 42aA, 42aB, 42aC, 42Xa...tip portion, 42b, 42bA, 42bB, 42bC, 42Xb...extension portion, 42c, 42cA, 42cB, 42cC...insertion hole, 42x , 42y, 42z...contact portion, 42T, 42XT...rear end surface, 42Xa1...side portion, 43, 43X, 43Y...middle portion (space, air layer), 44...fitting portion, 45...tip member, 451...pen tip fitting portion, 452...extension member fitting portion, 452P...inner protrusion, 45T...tip member rear end surface, 45H...bottom opening, 46...extension member, 46G...side groove portion, 461...front tapered portion, 462...middle portion, 463...rear side, 46FH...front opening, 46BH...rear opening, 5 ...Battery, 5a...Positive terminal, 5b...Negative terminal, 6...Core holder, 7...Pressure-sensing part, 71...Dielectric, 72...Terminal member, 73...Retaining member, 74...Conductive member, 75...Elastic member, 8...Printed circuit board, 8S...Signal generating circuit, 9...Conductive elastic member, 10...IC, 11, 12...Push switch, 11a, 12a...Operating unit, 13...Coil spring, 13a...Metal plate, 14...Conductive terminal member, 15...Conductive terminal member, 51...Terminal conductor, 52...Coil spring terminal

Claims

1. a cylindrical housing having an opening at one end in an axial direction; a core body attached to the inside of the housing so that a tip portion in an axial direction thereof protrudes from the opening of the housing; a signal generating circuit that generates a signal to be sent from the core body; Equipped with The core body is a core rod having electrical conductivity and receiving a signal from the signal generating circuit; a protective member covering the core rod, The core rod comprises a pen tip portion at the front end, a mounting portion at the rear end, and a shaft portion connecting the pen tip portion and the mounting portion, an intermediate portion having a dielectric constant different from that of the protective member, the intermediate portion being provided around the side surface of the shaft portion of the core rod so as to be spaced from the protective member; An electronic pen characterized by:

2. The electronic pen according to claim 1 , the protective member has an insertion hole into which the core rod is inserted, a fitting portion that protrudes in a direction intersecting with the axis of the core rod is provided on the rear end side of the shaft portion of the core rod, When the core rod is inserted into the insertion hole and attached, the pen tip portion of the core rod is in close contact with the front end portion of the insertion hole, and the fitting portion of the core rod is in close contact with the rear end portion of the insertion hole. An electronic pen characterized by:

3. The electronic pen according to claim 1 , the protective member has an insertion hole into which the core rod is inserted, a fitting portion is provided on the rear end side of the shaft portion of the core rod, the fitting portion extending in a direction intersecting the shaft center and having a knurled side surface; When the core rod is inserted into the insertion hole and attached, the pen tip portion of the core rod is in close contact with the front end portion of the insertion hole, and the fitting portion of the core rod is in close contact with the rear end portion of the insertion hole. An electronic pen characterized by:

4. The electronic pen according to claim 1 , the protective member has an insertion hole into which the core rod is inserted, and an inner diameter of a portion of the insertion hole corresponding to the shaft portion of the core rod is longer than an outer diameter of the shaft portion; When the core rod is inserted into the insertion hole and attached, a space is provided as the intermediate portion between the protection member and the shaft portion. An electronic pen characterized by:

5. The electronic pen according to claim 1 , the protective member has an insertion hole into which the core rod is inserted, and an inner diameter of a portion of the insertion hole corresponding to the shaft portion of the core rod is longer than an outer diameter of the shaft portion; a fitting portion that protrudes in a direction intersecting the axis of the core rod is provided on the rear end side of the shaft portion of the core rod, When the core rod is inserted into the insertion hole and attached, The pen tip portion of the core rod is in close contact with the tip portion of the insertion hole, The fitting portion of the core rod is in close contact with the rear end portion of the insertion hole, A space is provided as the intermediate portion between the protective member and the shaft portion. An electronic pen characterized by:

6. The electronic pen according to claim 1 , a core body holding portion to which the core body is attached is provided inside the housing, The mounting portion of the core rod of the core body is mounted to the core body holding portion and is electrically connected to the signal generating circuit. An electronic pen characterized by:

7. The electronic pen according to claim 1 , The tip of the protection member of the core body is tapered. An electronic pen characterized by:

8. The electronic pen according to claim 1 , The core rod of the core body is formed from a metal material, The core protection member is made of a resin material. An electronic pen characterized by:

9. The electronic pen according to claim 1 , The core rod of the core body is made of stainless steel or brass. An electronic pen characterized by:

10. The electronic pen according to claim 1 , The core protection member is made of a resin material, and is formed by two-color molding using different materials for the tip portion and the remaining portion. An electronic pen characterized by:

11. The electronic pen according to claim 1 , The core protection member is formed by two-color molding, with the tip portion made of elastomer and the other portion made of polyacetal. An electronic pen characterized by:

12. The electronic pen according to claim 10, The tip portion formed by two-color molding is made of a conductive material. An electronic pen characterized by:

13. The electronic pen according to claim 1 , The protective member for the core body is a dome-shaped tip member having a rounded conical appearance at the tip, a large circular bottom opening at the bottom, and an empty space inside; a cylindrical extension member having a through hole formed in the axial direction; An electronic pen characterized by comprising:

14. A core body for an electronic pen is attached to an interior of a cylindrical housing of the electronic pen, the housing having an opening at one end in an axial direction of the electronic pen, such that a tip end in an axial direction of the electronic pen protrudes from the opening, a core rod having electrical conductivity and receiving a signal from a signal generating circuit; a protective member covering the core rod, The core rod comprises a pen tip portion at the front end, a mounting portion at the rear end, and a shaft portion connecting the pen tip portion and the mounting portion, an intermediate portion provided around a side surface of the shaft portion of the core rod so as to be spaced from the protective member, the intermediate portion having a dielectric constant different from that of the protective member; A core body for an electronic pen.

15. A core body for an electronic pen according to claim 14, the protective member has an insertion hole into which the core rod is inserted, a fitting portion that protrudes in a direction intersecting the axis of the core rod is provided on the rear end side of the shaft portion of the core rod, When the core rod is inserted into the insertion hole and attached, the pen tip portion of the core rod is in close contact with the front end portion of the insertion hole, and the fitting portion of the core rod is in close contact with the rear end portion of the insertion hole. A core body for an electronic pen.

16. A core body for an electronic pen according to claim 14, the protective member has an insertion hole into which the core rod is inserted, The rear end of the shaft portion is provided with a fitting portion that protrudes in a direction intersecting the shaft center and has a knurled side surface, When the core rod is inserted into the insertion hole and attached, the pen tip portion of the core rod is in close contact with the front end portion of the insertion hole, and the fitting portion of the core rod is in close contact with the rear end portion of the insertion hole. A core body for an electronic pen.

17. A core body for an electronic pen according to claim 14, the protective member has an insertion hole into which the core rod is inserted, and an inner diameter of a portion of the insertion hole corresponding to the shaft portion of the core rod is longer than an outer diameter of the shaft portion; When the core rod is inserted into the insertion hole and attached, a space is provided as the intermediate portion between the protection member and the shaft portion. A core body for an electronic pen.

18. A core body for an electronic pen according to claim 14, the protective member has an insertion hole into which the core rod is inserted, and an inner diameter of a portion of the insertion hole corresponding to the shaft portion of the core rod is longer than an outer diameter of the shaft portion; A fitting portion is provided on the rear end side of the shaft portion, the fitting portion extending in a direction intersecting the axis, When the core rod is inserted into the insertion hole and attached, The pen tip portion of the core rod is in close contact with the tip portion of the insertion hole, The fitting portion of the core rod is in close contact with the rear end portion of the insertion hole, A space is provided as the intermediate portion between the protective member and the shaft portion. A core body for an electronic pen.

19. A core body for an electronic pen according to claim 14, The protective member is a dome-shaped tip member having a rounded conical appearance at the tip, a large circular bottom opening at the bottom, and an empty space inside; a cylindrical extension member having a through hole formed in the axial direction; A core body for an electronic pen, characterized by being composed of:

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