Electronic pen

Abstract

The present invention enables an electronic pen to be made slimmer without reducing the functionality of the electronic pen. A columnar ferrite core (212) has a through-hole (212a) and comprises three sections, that is, a front section (212F), a middle section (212M), and a back section (212B). The outer diameter of the middle section (212M) is smaller than the outer diameters of the front section (212F) and the back section (212B), and thus the middle section (212M) has a thinner shape like that of a so-called dumbbell being a gymnastic instrument. An insulated conducting wire is wound around the middle section (212M), to form a coil (211), thus enabling the electronic pen to be made thinner without thickening the portion of the ferrite core (312) where the coil is wound.

Description

[Technical field]

[0001] The present invention relates to an electronic pen, which is a pen-type position indicator used together with a position detection device. [Background technology]

[0002] An electronic pen is held by a user and used to indicate a position on a sensor of a position detection device. Since electronic pens are configured with a circuit board and the like, they have been thicker than general writing implements such as ballpoint pens and fountain pens. However, with the miniaturization and thinning of electronic devices such as so-called tablet PCs (Personal Computers) and high-performance mobile phone terminals called smartphones, which are equipped with position detection devices, there has been a demand for thinner electronic pens.

[0003] Therefore, Patent Document 1 described later discloses an invention relating to an electronic pen body, etc., in which an electronic pen body of approximately the same size as a ballpoint pen refill (refill) is formed and can be mounted on an existing ballpoint pen housing for use. Patent Document 2 described later discloses an invention relating to an electronic pen, etc., in which the pen tip, which is susceptible to external pressure, has increased strength so that it will not bend or break even if it is made thinner. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-224178 A [Patent Document 2] International Publication No. 2017 / 183526 Summary of the Invention [Problem to be solved by the invention]

[0005] Position input devices consisting of an electronic pen and a position detection device include, for example, electromagnetic induction type and capacitance type. In the case of an electromagnetic induction type electronic pen, a coil that constitutes a resonance circuit together with a capacitor must be provided on the pen tip side in order to transmit and receive magnetic signals between the electronic pen and the electromagnetic induction type position detection device. In the case of a capacitance type electronic pen, for example, a coil connected to a battery may be provided on the pen tip side of the electronic pen to wirelessly charge the battery mounted thereon, and the battery may be charged by electromagnetic induction (magnetic field coupling).

[0006] In these cases, the coil is formed by winding an insulated conductor around a magnetic core. This is because the magnetic core has the effect of increasing the impedance of the insulated conductor according to its magnetization, thereby suppressing the propagation of noise current flowing through the coil. However, since the coil is formed by winding an insulated conductor around a magnetic core, the portion of the electronic pen where the coil is formed inevitably becomes thick, as shown in Fig. 3 of Patent Document 1 and Figs. 3 and 7 of Patent Document 2, etc., mentioned above.

[0007] In recent years, there has been an increasing demand for electronic pens equipped with coils to be made thinner. For example, electronic pens are required to be thinner than before so that they can be easily stored in the housings of mobile terminals. Functional One of the demands is to make electronic pens thinner so that electronic pen functions can be more easily implemented.

[0008] In view of the above, an object of the present invention is to realize a thinner electronic pen without compromising the functionality of the electronic pen. [Means for solving the problem]

[0009] In order to solve the above problems, A coil and a columnar magnetic core around which the coil is wound and which has a through hole in the axial direction; a capacitor that configures a resonant circuit together with the coil; a rod-shaped core body that is inserted through the through hole of the magnetic core; An electronic pen that transmits and receives signals between the electronic pen and a position detection sensor by electromagnetic induction, the magnetic core includes a front portion having a predetermined range from a tip end on the pen tip side to a rear end opposite the pen tip side, a rear portion having a predetermined range from the rear end to the tip end side, and an intermediate portion sandwiched between the front portion and the rear portion; an outer diameter of the intermediate portion is smaller than outer diameters of the front portion and the rear portion; The coil is wound around the intermediate portion. The present invention provides an electronic pen.

[0010] In this electronic pen, the columnar magnetic core has a through hole and is composed of three parts: a front part, a middle part, and a rear part. The outer diameter of the middle part is shorter than the outer diameters of the front and rear parts, so that the middle part is narrower and has a shape similar to a so-called dumbbell, which is a gymnastics tool. Since an insulated conductor is wound around this middle part to form a coil, the part of the magnetic core around which the coil is wound does not become thick, which contributes to making the electronic pen slimmer. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram for explaining an electronic pen according to an embodiment and a tablet terminal in which the electronic pen is used; [Diagram 2] 2 is a diagram for explaining a configuration example of a main part of an electronic pen according to an embodiment; FIG. [Diagram 3] 5A to 5C are diagrams for explaining a configuration of a ferrite core portion of the electronic pen according to the embodiment. [Figure 4] 1A and 1B are diagrams for explaining a magnetic flux distribution in a ferrite core portion of an electronic pen according to the present invention and a magnetic flux distribution in a ferrite core portion of a conventional electronic pen; [Diagram 5] 5A and 5B are diagrams for explaining a groove provided in a ferrite core of the electronic pen according to the present invention. [Figure 6]1 is a diagram for explaining a configuration example in which the electronic pen according to the present invention is applied to an active capacitance type electronic pen. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the electronic pen according to the present invention will be described with reference to the drawings. The position detection methods of the electronic pen and the position detection sensor include, for example, an electromagnetic induction method and a capacitance method. In the electromagnetic induction method (EMR (Electro Magnetic Resonance) method), the position detection device is provided with a sensor unit in which a plurality of loop coils are arranged in each of the X-axis direction and the Y-axis direction. A transmission period in which power is supplied sequentially to the plurality of loop coils of the sensor unit to generate a magnetic field and a reception period in which the supply of power is stopped and a magnetic field from the outside is received are alternately provided. The corresponding electronic pen is provided with a resonant circuit consisting of a coil and a capacitor, and generates a signal by causing a current to flow through the coil in response to the magnetic field from the sensor unit, and transmits this signal including writing pressure information to the position detection sensor. The position detection device receives this during the reception period and detects the position indicated by the electronic pen and the writing pressure.

[0013] In the capacitive type, the position detection device is provided with a sensor unit having a plurality of linear conductors (line electrodes) arranged in each of the X-axis and Y-axis directions. The sensor unit detects the indicated position according to a change in capacitance (charge) generated in the linear conductor when a finger or electrostatic pen is brought close to the sensor unit. Electrostatic pens include conductive pen-type position indicators and so-called active electrostatic pens (AES (Active Electrostatic) type) that are battery-powered and transmit signals. In the case of the active electrostatic coupling type using an active electrostatic pen, the electronic pen transmits a signal from an oscillator circuit mounted on the electronic pen, including pen pressure information, which is received by the position detection device to detect the indicated position and pen pressure.

[0014] In the case of an active electrostatic pen, it is not necessary to mount a coil basically. However, when charging a mounted battery by non-contact charging, a coil may be mounted for charging. This invention is applicable to electronic pens that require a coil to be mounted. Therefore, the electronic pen of this invention is applicable to both an electromagnetic induction type electronic pen and an active electrostatic coupling type electronic pen (active electrostatic pen) that performs non-contact charging. In the embodiment described below, first, a case where this invention is applied to an electromagnetic induction type electronic pen in which a coil is an essential component will be described as an example.

[0015] [Example of overall configuration of tablet device 1 and electronic pen 2] <Example of tablet device configuration> FIG. 1 is a diagram for explaining an electronic pen 2 according to an embodiment and a tablet terminal 1 in which the electronic pen 2 is used. The tablet terminal 1 is provided with, for example, an LCD (Liquid Crystal Display) 11 as a display device, and has a configuration in which a relatively large display screen 1A of the LCD 11 is exposed on the front. For example, a protective glass is provided on the display screen 1A. A position detection sensor 12 and a position detection device unit 13 are provided on the back of the display screen 1A. The position detection sensor 12 has a detection area corresponding to the entire surface of the display screen 1A so that the indicated position can be detected no matter which position on the display screen 1A is pointed to by the electronic pen 2. The position detection device unit 13 controls the position detection sensor 12 and detects the indicated position and writing pressure based on an output signal from the position detection sensor 12.

[0016] As described above, the position detection sensor 12 is a part that is configured by stacking an X-axis direction sensor configured by arranging multiple loop coils in the X-axis direction (horizontal direction) and a Y-axis direction sensor configured by arranging multiple loop coils in the Y-axis direction (vertical direction). multipleThe position detector 13 detects the pointing position and the writing pressure based on the signal received during the reception period.

[0017] Although not shown, a motherboard is mounted inside the housing of the tablet terminal 1. This motherboard is equipped with various circuits such as a display control circuit, an information processing circuit, a communication processing circuit, and a memory, and is capable of performing various information processing. Although not shown, several operation buttons such as a power button are provided on the side of the housing of the tablet terminal 1, and are capable of receiving operation input from the user and performing processing according to the received operation.

[0018] As a result, it is assumed that a position designation operation is performed on display screen 1A of tablet terminal 1 with electronic pen 2. In this case, position detection device unit 13 identifies the designated position on display screen 1A based on the detection output from position detection sensor 12 provided on the back of display screen 1A. Information indicating the designated position identified by position detection device unit 13 is supplied to an information processing circuit mounted on tablet terminal 1, and processing can be performed accordingly.

[0019] <Example of electronic pen 2 configuration> As described above, the electronic pen 2 uses an electromagnetic induction system to send and receive signals to and from the position detection sensor 12 of the position detection device unit 13 of the tablet terminal 1, thereby causing the position detection device unit 13 of the tablet terminal 1 to detect its indicated position. The mechanical configuration of the electronic pen 2 can be similar to that of a known electronic pen using an electromagnetic induction system, except that the shape of the magnetic core is unique.

[0020] 1, the electronic pen 2 of this embodiment includes an electronic pen main body 21 on one opening 20a side in the axial direction of a hollow part of a cylindrical housing 20 made of, for example, resin. The electronic pen main body 21 includes a coil 211, a magnetic core around which the coil 211 is wound, a ferrite core 212 in this example, a reinforcing pipe 213, a core body 214, a pen pressure detection unit 215, and a capacitor 216 that configures a resonance circuit together with the coil 211. In FIG. 1, the housing 20 is shown thick in order to clearly show the configuration of the main parts, but in reality, the electronic pen main body 21 is configured to be thin, and therefore is formed thinner than conventional electronic pens.

[0021] Fig. 2 is a diagram for explaining a configuration example of the electronic pen main body 21. As shown in Fig. 2(A), the ferrite core 212 is, for example, a cylindrical ferrite material, and has a through hole 212a in the axial direction with a predetermined diameter r1 (for example, r1 = 0.91 mm) for inserting a reinforcing pipe 213 described later. The ferrite core 212, which will be described in detail later, is made up of three parts, a front part 212F, a middle part 212M, and a rear part 212B, from the pen tip side to the rear end in the axial direction.

[0022] The outer diameter of middle portion 212M is shorter than the outer diameters of front portion 212F and rear portion 212B. In this way, the thickness of middle portion 212M is thinner than the thickness of front portion 212F and rear portion 212B, so that the overall shape of ferrite core 212 resembles a dumbbell, which is a gymnastics tool. As a result, coil 211 is formed by winding an insulated conductor around middle portion 212M, but the outer diameter of the portion where coil 211 is formed is not longer (thicker) than the outer diameters of front portion 212F and rear portion 212B.

[0023] In addition, a tapered portion 212T that gradually tapers is formed on the pen tip side of the front portion 212F of the ferrite core 212. This makes the magnetic coupling between the position detection sensor 12 of the position detection device unit 13 stronger than when the tapered portion 212T is not present. The outer diameter of the front portion 212F excluding the tapered portion 212T and the outer diameter of the rear portion 212B are the same length. As a result, the portion consisting of the ferrite core 212 and the coil 211 is made to have approximately the same outer diameter in any portion in the axial direction, excluding the tapered portion 212T, as shown in FIG. 2(A).

[0024] 1 and 2A, in the electronic pen body 21, a reinforcing pipe 213 is provided in the through hole 212a of the ferrite core 212. The reinforcing pipe 213 is made of stainless steel such as SUS316, and has an outer diameter equal to or larger than the through hole 212a of the ferrite core 212. 212a 2(A), the reinforcing pipe 213 is fixed from one end to the other end of the through hole 212a of the ferrite core 212, with its front end protruding from the front end opening of the ferrite core 212 and its rear end protruding from the rear end opening of the ferrite core 212. Therefore, the axial length of the reinforcing pipe 213 is longer than the axial length of the ferrite core 212, as shown in FIG.

[0025] A cylindrical body 217 made of, for example, resin is provided on the rear end side of the ferrite core 212. A writing pressure detection unit 215 is provided near the joint between the cylindrical body 217 and the ferrite core 212. The writing pressure detection unit 215 is configured using a semiconductor element that changes the capacitance according to the writing pressure, for example, as disclosed in Japanese Patent Application Laid-Open No. 2013-161307. Note that the writing pressure detection unit 215 can also be configured as a variable capacitance capacitor that changes the capacitance according to the writing pressure, using a writing pressure detection means with a known mechanical configuration, for example, as described in Japanese Patent Application Laid-Open No. 2011-186803.

[0026] A printed circuit board 218 is further housed inside the cylindrical body 217. A capacitor 216 is provided on the printed circuit board 218, which is connected in parallel to the coil 211 to form a resonant circuit. The variable capacitor formed in the pen pressure detection unit 215 is connected in parallel to the capacitor 216 provided on the printed circuit board 218, and forms a part of the above-mentioned resonant circuit.

[0027] 2(B), the rear end of the rear portion 212B of the ferrite core 212 is fitted into a recess 217a provided in the cylindrical body portion 217, thereby coupling the ferrite core 212 to the cylindrical body portion 217. Although not shown in the figure, when the ferrite core 212 is coupled to the cylindrical body portion 217, the extension wires 211a and 211b from both ends of the coil 211 are connected in parallel to the capacitor 216 provided on the printed circuit board 218 of the cylindrical body portion 217.

[0028] In this embodiment, the core body 214 is rod-shaped with a diameter smaller than the inner diameter of the inner hollow part (through hole) of the reinforcing pipe 213 that passes through the through hole 212a of the ferrite core 212. The axial length of the core body 214 is longer than the axial length of the reinforcing pipe 213. In this embodiment, as shown in FIG. 2(B), the core body 214 is inserted into the hollow part of the reinforcing pipe 213 that passes through the through hole 212a of the ferrite core 212, and the tail end part 214b is fitted into the fitting hole 215a of the writing pressure detection part 215. In this fitted state, the core body 214 is in a state in which the pen tip part protrudes from the opening on the tip side of the reinforcing pipe 213.

[0029] 2(B), in this embodiment, the pen tip portion 214a of the core body 214 protrudes to the outside from the opening 20a of the housing 20 of the electronic pen 2, together with a part of the pen tip side of the reinforcing pipe 213 and a part of the pen tip side of the ferrite core 212. Therefore, the writing pressure applied to the pen tip portion 214a of the core body 214 is directly transmitted to the writing pressure detection unit 215 through the core body 214.

[0030] In this embodiment, the electronic pen 2 receives an AC signal of frequency f0 transmitted through the position detection sensor 12 of the position detection device section 13 at a resonant circuit by electromagnetic induction coupling. Then, the resonant circuit of the electronic pen 2 feeds back the received AC signal to the position detection sensor 12 by electromagnetic induction coupling. The position detection device section 13 detects the position on the position detection sensor 12 of the AC signal fed back from the electronic pen 2, thereby detecting the position pointed to by the electronic pen 2. The position detection device section 13 also detects a change in the frequency or phase of the AC signal received from the electronic pen 2, thereby detecting the writing pressure applied to the electronic pen 2.

[0031] In addition, in order to minimize energy loss and ensure good interaction of AC signals between the electronic pen 2 and the position detection sensor 12, the resonant frequency of the resonant circuit of the electronic pen 2 is selected to be equal to the frequency f0 of the AC signal from the position detection device unit 13.

[0032] <Ferrite core configuration> Fig. 3 is a diagram for explaining the configuration of the ferrite core 212 portion of the electronic pen 2 according to the embodiment. Fig. 3(A) is a perspective view of the ferrite core 212 portion with the coil 211, the reinforcing pipe 213, and the core body 214 attached. Fig. 3(B) is a perspective view of only the ferrite core 212. Fig. 3(C) is an external view of the ferrite core 212 as viewed from a direction intersecting the axial direction (longitudinal direction).

[0033] Coil 211, ferrite core 212, reinforcing pipe 213, and core body 214 can each be of various sizes. However, in electronic pen 2 of this embodiment, the shape and size of ferrite core 212 are devised so that the outer diameter of the portion consisting of coil 211, ferrite core 212, reinforcing pipe 213, and core body 214 is the same as the 4C standard, which is the standard for ballpoint pen refills (refills), and sizes of the other parts are selected accordingly.

[0034] In addition, the 4C standard requires that the outer diameter φ be within a range of 2.3 mm to 2.4 mm, taking into consideration tolerances. Therefore, in the following, the outer diameter φ of the portion consisting of the coil 211, ferrite core 212, reinforcing pipe 213, and core body 214 will be described as being approximately 2.3 mm, which corresponds to the outer diameter of the 4C standard. In addition, although the word "approximately" is omitted for the lengths of the outer diameters of the other portions, this means that they will be approximately the lengths shown, and may include tolerances.

[0035] The ferrite core 212 is a magnetic body made of ferrite (ceramics mainly composed of iron oxide), and is formed in a cylindrical shape with a through hole 212a with the axis as the center line as shown in Fig. 3(B). As shown in Figs. 3(B) and (C), the ferrite core 212 is made up of three parts, a front part 212F, a middle part 212M, and a rear part 212B, and a tapered part 212T is provided on the pen tip side of the front part 212F.

[0036] In this embodiment, the outer diameter φ of the front portion 212F and the rear portion 212B of the ferrite core 212 is approximately 2.3 mm, and the outer diameter φ of the middle portion 212M is 1.4 mm. That is, the outer diameter of the middle portion 212M is shorter than the outer diameters of the front portion 212F and the rear portion 212B by 0.9 mm, so that the shape of the middle portion 212M resembles a dumbbell as a whole. The inner diameter φ of the ferrite core 212 (diameter of the through hole 212a) is 0.91 mm in all of the front portion 212F, the middle portion 212M, and the rear portion 212B.

[0037] As shown in FIG. 3A, an insulated conductor is wound around the intermediate portion 212M of the ferrite core 212 having such a shape to form the coil 211. In this embodiment, the coil 211 is formed using a twisted wire (φ0.05 / 7) formed by twisting together seven conductor wires each having a diameter φ of 0.05 mm. Therefore, the diameter of the twisted wire is about 0.15 mm. However, even if the twisted wire is wound twice around the intermediate portion 212M, with 26 turns in the first turn (first layer) and 24 turns in the second turn (second layer), the thickness of the coil 211 portion is about 0.3 mm.

[0038] Therefore, even if the coil 211 is formed by winding an insulated conductor around the middle portion 212M of the ferrite core 212, the outer diameter of the portion where the coil 211 is formed is not longer than the outer diameter (about 2.3 mm) of the front portion 212F and the rear portion 212B where the coil is not formed. That is, the outer diameter of any portion consisting of the coil 211 and the ferrite core 212 is made to be about 2.3 mm or less. As described above, the reinforcing pipe 213 is made of stainless steel (SUS316) and has an outer diameter of φ0.89 mm and an inner diameter of φ0.6 mm as shown in FIG. 3(A). The core body 214 is made of a resin such as polyacetal (POM) and has a diameter φ of 0.56 mm.

[0039] 3(A), the reinforcing pipe 213 is inserted into the through hole 212a of the ferrite core 212 around which the coil 211 is wound, and the core body 214 is inserted into the hollow part of the reinforcing pipe 213, thereby forming the pen tip side part of the electronic pen body 21. The reinforcing pipe 213 not only reinforces the core body 214 but also reinforces the ferrite core 212, thereby increasing the strength of the components of the electronic pen body 21 on the pen tip side to which external pressure is applied.

[0040] The shape and size of the ferrite core 212 in this embodiment will be summarized with reference to Fig. 3(C). The ferrite core 212 is cylindrical with an outer diameter of approximately 2.3 mm, and has a through hole 212a with a diameter of 0.91 mm and with its axis at the center line L. The total length of the ferrite core 212 is 13 mm, but it is made up of a front portion 212F with a length of 3.5 mm, a middle portion 212M with a length of 6.5 mm, and a rear portion 212B with a length of 3.0 mm. The tip of the front portion 212F is a tapered portion 212T.

[0041] As shown in Fig. 3C, the outer diameter of the middle part 212M is 1.4 mm, which is shorter by 0.9 mm than the outer diameters of the front part 212F and the rear part 212B. Therefore, a step of 0.45 mm occurs over the entire circumference between the middle part 212M and the front part 212F and the rear part 212B, resulting in a difference of 0.9 mm in outer diameter. Therefore, as described above, even if the twisted wire (φ0.05 / 7), which is an insulated conductor, is wound twice around the middle part 212M, the thickness of the coil 211 is about 0.3 mm, so that the outer diameter of the middle part 212M around which the coil 211 is wound does not exceed about 2.3 mm, and the electronic pen main body 21 can be configured with an outer diameter (about 2.3 mm) conforming to the 4C standard, which is the standard for ballpoint pen refills.

[0042] 4A and 4B are diagrams for explaining the magnetic flux distribution in the ferrite core 212 portion of the electronic pen according to the present invention (FIG. 4A), and the magnetic flux distribution in the ferrite core 300 portion of a conventional electronic pen (FIG. 4B). Note that in FIG. 4, only the ferrite core and coil are shown, and the illustration of the core body and the like is omitted. The ferrite core 300 of the conventional electronic pen shown in FIG. 4B is cylindrical, with an axial length of 13 mm and an outer diameter of approximately 2.3 mm at any point in the axial direction.

[0043] In this case, if a coil is wound around the pen tip side of the ferrite core 300 of the conventional electronic pen, the coil gets in the way and the tip of the core body and the tip of the ferrite core 300 cannot be projected from the electronic pen housing having a tapered pen tip side. Therefore, as shown in Fig. 4B, in the case of the ferrite core 300 of the conventional electronic pen, the coil 310 is formed by winding an insulated conductor further toward the rear end side. In the case of the example shown in Fig. 4B, a non-wound portion of 5.4 mm is provided from the tip of the ferrite core 300 on the pen tip side to the rear end side, and then a coil is formed over a length of 6.0 mm, and then a non-wound portion of 1.6 mm is provided.

[0044] For this reason, in order to generate the desired magnetic flux (magnetic field) on the pen tip side, it is necessary to increase the self-inductance (L value). In the case of a pen In order to achieve this, it becomes necessary to wind the coil around the ferrite core 300, for example, three or more times, and the outer diameter of the part around which the coil is wound becomes as large as about 3.18 mm in the case of FIG. 4(B). As a result, as shown in FIG. 4(B), the desired magnetic flux is generated on the pen tip side. It is possible. However, since coil 310 is formed on the rear end side of ferrite core 300, in the case of a conventional electronic pen, a larger magnetic flux (magnetic field) is generated on the rear end side of ferrite core 300 than on the pen tip side.

[0045] In contrast, in the case of the ferrite core 212 of the electronic pen 2 of this embodiment shown in Fig. 4(A), as described with reference to Fig. 3(C), the outer diameters of the front portion 212F and the rear portion 212B are approximately 2.3 mm, but the outer diameter of the intermediate portion is 1.4 mm. Also, as shown in Fig. 4(A), the front portion 212F of the ferrite core 212 is a portion 3.5 mm from the tip on the pen tip side to the rear end, the intermediate portion 212M is a portion 6.5 mm behind the front portion 212F, and the rear portion is a portion 3.0 mm behind the intermediate portion 212M.

[0046] In the case of the electronic pen 2 of this embodiment, the coil is formed by winding an insulated conductor twice around the middle portion of the 6.5 mm long portion. As described above, the coil 211 is formed from an insulated conductor that is a twisted wire (φ0.05 / 7), and the diameter of the twisted wire is about 0.15 mm, so even if the coil is formed by winding it twice, the thickness is about 0.3 mm. Therefore, the outer diameter of the portion where the coil is formed is about 2.3 mm or less. Therefore, in the case of the electronic pen 2 of this embodiment, the outer diameter of the ferrite core 212 portion, including the portion where the coil 211 is formed, is about 2.3 mm or less.

[0047] 4(A), the coil 211 can be positioned on the pen tip side of the ferrite core 212, so that the desired magnetic flux can be generated on the pen tip side simply by winding an insulated conductor twice around the middle portion 212M to form the coil 211. In addition, in the case of the electronic pen 2 of this embodiment, the coil 211 can be formed in the approximate center of the ferrite core 212, so that an approximately equal magnetic flux (magnetic field) can be generated on the pen tip side and the rear end side of the ferrite core 212. Therefore, an unnecessarily large magnetic flux (magnetic field) is not generated on the rear end side of the electronic pen 2.

[0048] 5 is a diagram for explaining the groove provided in the ferrite core 212 of the electronic pen 2 according to the present invention. As described above, the extension wires 211a and 211b from both ends of the coil 211 wound around the ferrite core 212 are connected in parallel with the capacitor 216 provided on the printed circuit board 218. For this reason, a groove 212Gr is provided along the axial direction on the side surface of the rear portion 212B of the ferrite core 212 so that the extension wires 211a and 211b from both ends of the coil 211 can be appropriately extended to the rear end. This allows the extension wires 211a and 211b to be extended to the rear printed circuit board 218 through the groove 212Gr provided on the side surface of the ferrite core 212 without appearing on the side surface of the ferrite core 212.

[0049] [Application of active capacitive electronic pens] 6 is a diagram for explaining a configuration example in which the electronic pen according to the present invention is applied to an active capacitance type electronic pen (active electrostatic pen). The active electrostatic pen 400 in this example includes an electric double layer capacitor 401 that functions as a power storage unit, a rectifying diode 402, a voltage conversion circuit 403, and a charging coil 404. The active electrostatic pen 400 further includes an oscillation circuit 405, a writing pressure detection unit 406, a signal line 407, and a conductive core body 408.

[0050] In this example, one end of the coil 404 is connected to the anode of the rectifier diode 402, and the other end is grounded (GND). In addition, one end of the electric double layer capacitor 401 is connected to the cathode of the rectifier diode 402, and the other end is grounded. The coil 404 does not constitute a resonance circuit for position indication by electromagnetic induction, but is used as a power supply terminal that receives power supply from an external source, and realizes a contactless charging function. The conductive core 408 is electrically connected to the oscillation circuit 405 through a signal line 407. In addition, the writing pressure detection unit 406 is electrically connected to the oscillation circuit 405.

[0051] The oscillator circuit 405 generates a signal whose frequency changes according to the capacitance of a variable capacitor (condenser) of the writing pressure detection unit 406, and supplies the generated signal to the core body 408 through a signal line 407. The signal from the oscillator circuit 405 is emitted from the pen tip portion (tip portion) of the core body 408 as an electric field based on the signal. The oscillator circuit 405 is composed of, for example, an LC oscillator circuit that utilizes resonance between a coil and a capacitor. In a position detection device that detects the coordinate position indicated by the active electrostatic pen 400 of this example, the writing pressure applied to the pen tip of the core body 408 can be obtained from the frequency of this signal.

[0052] The voltage conversion circuit 403 converts the voltage stored in the electric double layer capacitor 401 into a constant voltage and supplies it as a power source for the oscillation circuit 405. When the capacitive active electrostatic pen 400 of this example is attached to a charger (not shown), an induced electromotive force is generated in the coil 404 by the alternating magnetic field generated by the charger, and the electric double layer capacitor 401 can be charged via the rectifier diode 402.

[0053] In the active electrostatic pen 400 configured as described above, a ferrite core configured to have the same volume as the above-mentioned ferrite core 212 is provided around the core body 408, and a charging coil 404 is provided in the middle of this ferrite core. This allows the active electrostatic pen 400 to be configured without increasing the outer diameter of the portion consisting of the ferrite core and the coil 404.

[0054] In the active electrostatic pen 400 having such a configuration, the above-mentioned ferrite core 212 and Similar A ferrite core configured as above is provided, and a charging coil 404 is provided in the middle of this ferrite core. This allows the active electrostatic pen 400 to be configured without increasing the outer diameter of the portion consisting of the ferrite core and the coil 404.

[0055] Also, since the coil 211 can be formed closer to the pen tip side of the ferrite core 212, the inductance can be increased. This allows the magnetic flux distribution to be broadened on the pen tip side of the electronic pen 2. In other words, a good magnetic flux (magnetic field) can be generated by the coil 211 on the pen tip side of the electronic pen 2. This allows the position indication and writing pressure to be appropriately transmitted to the position detection sensor 12 and the position detection device unit 13 in the case of an electromagnetic coupling type electronic pen. Also, in the case of a capacitance type electronic pen, the electric double layer capacitor can be efficiently charged.

[0056] [Variations] In the above-mentioned embodiment, the sizes of the coil 211, the ferrite core 212, the reinforcing pipe 213, and the core body 214 are merely examples, and are not limited to these sizes. For example, it is also possible to provide the middle part 212M of the ferrite core 212 closer to the pen tip side, and form the coil 211 closer to the pen tip side. That is, the axial lengths of the front part 212F, the middle part 212M, and the rear part 212B of the ferrite core 212 can also be various lengths. In the case of the electronic pen 2 of the above-mentioned embodiment, the part where the coil 211 is formed does not become thick, so that the part where the coil 211 is formed can also be made to protrude from the housing 20 of the electronic pen 2. That is, it is possible to further strengthen the electromagnetic coupling with the position detection device unit 13.

[0057] In the case of the electronic pen main body 21 described above, in order to make the outer diameter of the portion where the coil 211 is provided approximately 2.3 mm or less, the coil 211 is wound with an insulated conductor twice (in two stages) around the middle portion 212M. However, if it is not necessary to make it approximately 2.3 mm or less, the coil may be wound with an insulated conductor three times (in three stages). By increasing the number of stages of the coil, the insulated conductor The winding part of Since the wires are in close contact with each other and the magnetic flux linkage can be increased, the self-inductance (L value) increases and magnetic flux (magnetic field) can be generated effectively.

[0058] Also, if the strength of the ferrite core 212 and the core body 214 is high, it is possible to adopt a configuration without providing the reinforcing pipe 213. Also, in the above-mentioned embodiment, a ferrite core is used as the magnetic core, but this is not limited to this. If a core material that achieves the same function as a ferrite core can be realized using various magnetic materials, this may be used. [Explanation of symbols]

[0059] 1...tablet terminal, 1A...display screen, 11...LCD, 12...position detection sensor, 13...position detection device section, 2...electronic pen, 20...housing, 20a...opening, 21...electronic pen main body section, 211...coil, 211a, 211b...extended wire, 212...ferrite core, 212a...through hole, 212T...tapered section, 212F...front section, 212M...middle section, 212B...rear section, 212Gr...groove section, 213...reinforcing pipe, 214...core body, 214a... Pen tip portion, 214b... tail end portion, 215... writing pressure detection portion, 215a... fitting hole, 216... capacitor, 217... cylindrical body portion, 217a... recess, 218... printed circuit board, 300... ferrite core, 310... coil, 400... active electrostatic pen, 401... electric double layer capacitor, 402... rectifier diode, 403... voltage conversion circuit, 404... charging coil, 405... oscillation circuit, 406... writing pressure detection portion, 407... signal line, 408... conductive core body

Claims

1. A coil and a columnar magnetic core around which the coil is wound and which has a through hole in the axial direction; a capacitor that configures a resonant circuit together with the coil; a rod-shaped core body that is inserted through the through hole of the magnetic core; An electronic pen that transmits and receives signals between the electronic pen and a position detection sensor by electromagnetic induction, the magnetic core includes a front portion having a predetermined range from a tip end on the pen tip side to a rear end opposite the pen tip side, a rear portion having a predetermined range from the rear end to the tip end side, and an intermediate portion sandwiched between the front portion and the rear portion; an outer diameter of the intermediate portion is smaller than outer diameters of the front portion and the rear portion; The coil is wound around the intermediate portion.

1. An electronic pen comprising:

2. 2. The electronic pen according to claim 1, the intermediate portion of the magnetic core is a wound portion around which the coil is wound, and the front portion and the rear portion are non-wound portions around which the coil is not wound, The outer diameter of the wound portion when the coil is wound is equal to or smaller than the outer diameter of the non-wound portion.

1. An electronic pen comprising:

3. 2. The electronic pen according to claim 1, The front portion of the magnetic core on the pen tip side gradually tapers to form a tapered portion.

2. The electronic pen according to claim 1 .

4. 2. The electronic pen according to claim 1, A groove is provided on a side surface of the rear portion of the magnetic core along the axial direction for extending an insulated conductor from the coil wound around the intermediate portion of the magnetic core to the rear end side.

1. An electronic pen comprising:

5. 2. The electronic pen according to claim 1, a reinforcing pipe fixed to the magnetic core from one end to the other end of the through hole and having a tip protruding from a tip opening of the magnetic core, The core body is allowed to slide in the axial direction within the reinforcing pipe.

1. An electronic pen comprising:

6. 2. The electronic pen according to claim 1, 2. The electronic pen according to claim 1, The electronic pen is used in a state in which at least a part of the front portion of the magnetic core and the pen tip portion of the core body protrude from the electronic pen housing.

1. An electronic pen comprising:

7. 2. The electronic pen according to claim 1, a reinforcing pipe fixed to the through hole of the magnetic core from one end to the other end and having a tip protruding from a front portion of the magnetic core, The electronic pen is used in a state in which at least a part of the front portion of the magnetic core, the tip of the reinforcing pipe, and the pen tip of the core body protrude from the electronic pen housing.

1. An electronic pen comprising:

8. 2. The electronic pen according to claim 1, The axial length of the intermediate portion of the magnetic core is equal to the combined axial length of the front portion and the rear portion of the magnetic core.

1. An electronic pen comprising:

9. 2. The electronic pen according to claim 1, an axial length of the intermediate portion of the magnetic core is equal to a combined axial length of the front portion and the rear portion of the magnetic core, The length of the front portion in the axial direction is slightly longer than the length of the rear portion in the axial direction.

1. An electronic pen comprising:

10. 2. The electronic pen according to claim 1, The outer diameter of the front and rear portions of the magnetic core is approximately 2.3 mm.

1. An electronic pen comprising:

11. a coil connected to a charging circuit of a battery that supplies driving power; a columnar magnetic core around which the coil is wound and which has a through hole in the axial direction; a rod-shaped core body that is inserted through the through hole of the magnetic core; an oscillator circuit for generating a signal to be transmitted through the core; A capacitive electronic pen comprising: the magnetic core is made up of a front portion having a predetermined range from a tip portion that is a pen tip portion to a rear end side opposite to the pen tip side, a rear portion having a predetermined range from the rear end to the tip portion, and an intermediate portion sandwiched between the front portion and the rear portion, an outer diameter of the intermediate portion is smaller than outer diameters of the front portion and the rear portion; The coil is wound around the intermediate portion.

1. An electronic pen comprising:

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