Electronic pen

Abstract

Provided is an electronic pen capable of stably receiving an external electric field. The present invention is provided with: a housing having an opening at one end in the axial direction; a core body having a first electrode for generating a first electric field for position indication, the core body being disposed so that a tip portion thereof protrudes outward from one opening of the housing; a second electrode that is electrically separated from the first electrode and is disposed so as to be able to receive an electric field from the outside; and a pressure detection unit that detects the pressure applied to the core using a strain gauge. The core body is directly or indirectly coupled to the pressure detection unit so as to transmit pressure to the pressure detection unit, and the second electrode is not coupled to the pressure detection unit and is disposed so as not to receive pressure when pressure is applied to the core body.

Description

Technical Field

[0001] The present invention relates to an active capacitance type electronic pen that realizes a function as a position indicator with respect to a position detection device mounted on an electronic device such as a tablet device or a tablet PC (Personal Computer). Background Art

[0002] A position detection device is installed in electronic devices such as a handwriting tablet device and a tablet PC as an input device for a personal computer. The position detection device generally includes a position detection sensor and a position detection circuit. The position detection sensor receives a position indication signal from an electronic pen, and based on the corresponding output signal from the position detection sensor, the position detection circuit detects the indication position of the electronic pen on the position detection sensor. In order to appropriately determine the state (writing state) in which the electronic pen is in contact with the operating surface of the position detection sensor to perform an input operation, the electronic pen is equipped with a pressure detection unit (pen pressure detection unit) that detects the pressure (pen pressure) applied to the pen tip. The electronic pen includes the detection result of the pressure detection unit in the position indication signal and sends it to the position detection device. As a result, when the electronic pen is in contact with the operating surface of the position detection sensor to perform writing, the indication can be appropriately detected based on the position indication signal from the electronic pen to realize the indication input of the electronic pen.

[0003] Various improvements have been made to electronic pens. In the past, efforts have been made to imitate the same ease of use as ordinary stationery in electronic pens. When writing on paper with writing utensils such as pencils and ballpoint pens, handwriting is left when the pen tip contacts the paper. In order to achieve this ease of use, in electronic pens, designs are being made to detect signals when the tip of the electronic pen contacts the input surface and calculate the pen pressure based on the signals. In other words, designs are being made for pressure detection elements and mechanisms that can detect small pressures applied to the pen tip.

[0004] As an example, the following technology (for example, see Patent Document 1 (Japanese Patent Publication No. 2016-126503)) is widely used: two electrodes are provided to face each other with a dielectric sandwiched therebetween, and the area between the two electrodes of the dielectric changes according to the pressure applied to the core, thereby changing the capacitance and capturing the pressure as an electrical signal. In addition, the following electronic pen has also been proposed (see Patent Document 2 (U.S. Patent No. 110168804)): a resistance element such as a strain gauge is installed on a strain body, the pressure of the core is transmitted to the strain body to cause the strain body to generate strain, and the strain is detected as a change in resistance value in the strain gauge.

[0005] The advantage of the electronic pen using this strain gauge is that the stroke of the core is small when pen pressure is applied. By reducing the stroke, the ease of use can be close to that of paper and pencil.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2016-126503

[0009] Patent Document 2: U.S. Patent No. 110168804 Summary of the invention

[0010] Problems to be solved by the invention

[0011] The electronic pen of the above-mentioned patent document 2 is an active electrostatic capacitance type electronic pen, and is a structure having a central electrode provided on a core body and a peripheral electrode provided around the central electrode. The central electrode sends a signal for detecting the position indicated by the front end (pen tip) of the core body of the electronic pen on the position detection sensor side. In addition, in patent document 2, the peripheral electrode is an electrode for sending a signal, and sends a signal for detecting the tilt of the electronic pen.

[0012] The electronic pen using a strain gauge in Patent Document 2 has the following structure: the core structure is unitized by concentrating the central electrode and the peripheral electrodes at the pen tip of the core, and the unitized core structure is pressed against the strain body to apply pressure to the strain body. Therefore, if pressure is applied to the core, the peripheral electrodes will also move together with the central electrode.

[0013] In recent years, electronic pens have come to communicate with position detection sensors by exchanging signals. Therefore, the peripheral electrodes play a greater role in receiving signals from the position detection sensors. However, in the case of a structure in which the peripheral electrodes move simultaneously with the central electrode in response to pressure applied to the core body, as in the electronic pen of Patent Document 2, there is a problem that signal reception at the peripheral electrodes becomes unstable.

[0014] An object of the present invention is to provide an electronic pen that can solve the above problems.

[0015] Means for solving problems

[0016] In order to solve the above-mentioned problem, an electronic pen is provided, characterized in that it comprises:

[0017] The housing has an opening at one end in the axial direction;

[0018] The core is configured so that the front end thereof protrudes to the outside from one opening of the housing, and has a first electrode for generating a first electric field for position indication;

[0019] a second electrode electrically separated from the first electrode and arranged in a manner capable of receiving an external electric field; and

[0020] The pressure detection unit detects the pressure applied to the core body using a strain gauge.

[0021] The core is directly or indirectly coupled to the pressure detection unit so that the pressure is transmitted to the pressure detection unit, and

[0022] The second electrode is not coupled to the pressure detection portion and is disposed so as not to receive the pressure when the pressure is applied to the core.

[0023] In the electronic pen having the above structure, the second electrode does not receive pressure applied to the core body, and therefore does not displace when pressure is applied to the core body. Therefore, the second electrode can well receive an electric field (signal) from the outside. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a partial cross-sectional view for explaining an outline of an embodiment of the electronic pen according to the present invention.

[0025] Figure 2 It is a cross-sectional view for explaining a configuration example of a pen tip side of a main part of an embodiment of the electronic pen according to the present invention.

[0026] Figure 3 This is a diagram showing a configuration example of a pressure detection unit used in an embodiment of the electronic pen according to the present invention.

[0027] Figure 4 It is a diagram showing a circuit configuration example of an embodiment of the electronic pen according to the present invention.

[0028] Figure 5 This is a cross-sectional view showing a configuration example of a main part on the pen tip side for explaining another embodiment of the electronic pen according to the present invention. DETAILED DESCRIPTION

[0029] Hereinafter, an embodiment of the electronic pen of the present invention will be described with reference to the drawings. In the embodiment described below, an active electrostatic capacitance type electronic pen is described that indicates the position on the position detection sensor by transmitting a position indication signal formed by a mounted transmitting circuit through a core toward the position detection sensor. It should be noted that in the embodiment described below, the circuit that forms the position indication signal is set as a "transmitting circuit." This is because there is not only a case where the signal generated by the oscillator is directly used as a position indication signal, but there is also a case where various modulations are performed on the signal generated by the oscillator to form a desired position indication signal and transmit it. Therefore, the word "transmit" which widely means sending information is used.

[0030] [Configuration Example of the Electronic Pen 1]

[0031] Figure 1 This is a diagram for explaining a configuration example of the digital pen 1 according to the present embodiment, in which a part of the outer casing (housing) 2 of the digital pen 1 is cut away to show the inside thereof. Figure 2 This is a diagram (enlarged cross-sectional view) for explaining a main part of the pen tip side of the electronic pen 1 .

[0032] like Figure 1 As shown, the electronic pen 1 includes a cylindrical housing (shell) 2 which is elongated in the axial direction (direction along the axial center), has an opening on one side of the axial direction as the pen tip side, and is closed on the other side of the axial direction (hereinafter referred to as the rear end side). The housing 2 is composed of a cylindrical housing body 21 having a hollow portion inside, and a front cap 22 and a rear cap 23 connected to the housing body 21. The housing 2 is formed by fitting the front cap 22 and the rear cap 23 to the housing body 21.

[0033] like Figure 1 As shown, a substrate holder 3 for holding mounted components such as a printed substrate 8 and a battery 9 are housed in the hollow portion of the housing 2, and components for realizing the function as an electronic pen are housed on the pen tip side. The housing body 21 and the rear cap 23 are formed of a conductive material. In this embodiment, the housing body 21 and the rear cap 23 are formed of, for example, anodized aluminum. In addition, the front cap 22 is formed of a non-conductive material. In this embodiment, the front cap 22 is formed of, for example, plastic. The substrate holder 3 is made of a hard resin.

[0034] like Figure 1 As shown, a terminal conductor 91 is provided at the end of the substrate holder 3 on the side opposite to the pen tip side. The terminal conductor 91 electrically contacts the positive terminal 9a of the battery 9 and is electrically connected to the copper foil pattern of the power line of the printed substrate 8. A coil spring terminal 92 made of conductive metal and electrically connected to the negative terminal 9b of the battery 9 is provided at the mating portion of the rear cap 23 and the housing body 21. Figure 1 As shown, the battery 9 is inserted into the case 2 so that the positive terminal 9a is connected to the terminal conductor 91. Then, the rear cap 23 is fitted to the case body 21 so that the negative terminal 9b of the battery 9 is pressed by the coil spring terminal 92.

[0035] In this embodiment, the housing body 21 made of a conductive material is connected to the ground conductor of the electrical printed circuit board 8 via a ground electrode (ground ring) 14 described later provided on the side of the front cap 22. Since the rear cap 23 and the housing body 21 are made of a conductive material, the negative terminal 9b of the battery 9 is electrically connected to the ground conductor of the printed circuit board 8 via these rear cap 23 and the housing body 21. On the other hand, the positive terminal 9a of the battery 9 is connected to the copper foil pattern of the power line of the printed circuit board 8 through the terminal conductor 91. Thus, the voltage of the battery 9 is supplied as the power supply voltage of the circuit formed on the printed circuit board 8.

[0036] Although in Figure 1 Although not shown in the figure, the printed circuit board 8 is provided with a transmission circuit (signal generating circuit) 8s, a demodulation circuit 8r, a switch circuit SW, Figure 1 The control IC (Integrate Circuit) 10 and other peripheral circuit components are shown in FIG. The transmission circuit 8s generates a signal sent from the electronic pen core 4 of the electronic pen 1 and a signal sent from the peripheral electrode 13 described later. The transmission circuit 8s can supply signals of different frequencies to the core 4 and the peripheral electrode 13, respectively. The demodulation circuit 8r is used to demodulate the signal received through the peripheral electrode 13 and supply the demodulated information to the control IC 10.

[0037] As will be described later, the switch circuit SW switches whether to supply the signal from the transmission circuit 8s to the peripheral electrode 13 or to supply the signal received through the peripheral electrode 13 to the demodulation circuit 8r under the control of the control IC 10. In addition, the control IC 10 constitutes a control circuit for controlling each circuit unit such as the transmission circuit 8s and the switch circuit SW. Figure 1 As shown, the peripheral circuit unit includes push switches (side switches) 11 and 12 that are pressed down by operation portions 11 a and 11 b provided on the side surfaces of the housing body 21 .

[0038] In addition, although Figure 1 Although not shown in the figure, conductive lines connecting the core 4 and the transmission circuit 8s and conductive lines connecting the peripheral electrode 13 and the switch circuit SW are connected to the printed circuit 8. The peripheral electrode 13 is connected to the transmission circuit 8s and the demodulation circuit 8r via the switch circuit SW.

[0039] like Figure 2 As shown, the front cap 22 is a cylindrical body having a through hole in the axial direction through which the electronic pen core 4 passes, and the appearance of the portion on the pen tip side of the electronic pen 1 is a tapered shape whose outer diameter decreases as it approaches the pen tip. The end of the pen tip side of the front cap 22 is the opening of the through hole through which the electronic pen core 4 passes. As described above, the main parts for realizing the electronic pen function are mounted on the front cap 22 side.

[0040] like Figure 2 As shown, on the front cap 22 side of the housing 2, the core 4, the pressure transmission member 5 and the pressure detection unit 6 are arranged in series in the axial direction with their central axes being the same. That is, in this example, the pressure applied to the core 4 is also indirectly transmitted to the pressure detection unit 6 via the pressure transmission member 5.

[0041] like Figure 2 As shown, the electronic pen core 4 includes a core rod (hereinafter referred to as a center electrode) 41 formed of a conductive material and a protective member 42 formed of a non-conductive material, and has a structure in which a space (air layer) 43 is provided between the center electrode 41 and the protective member 42. The center electrode 41 constitutes an example of a first electrode that sends a signal for indicating a position to a position detection sensor. The center electrode 41 generates a first electric field that indicates a position to the position detection sensor. In this example, the core 4 is assembled to the pressure transmission member 5 in the housing 2 in such a manner that the axial center position of the center electrode 41 coincides with the axial center position of the housing 2.

[0042] In this case, if Figure 2 As shown, the wide portion of the pen tip of the core body 4 is in a state of protruding to the outside from the opening of the front cap 22 of the housing 2. The signal (electric field) radiated from the portion of the central electrode 41 of the core body 4 that is closer to the front end side than the wide portion of the oval pen tip is radiated relatively efficiently only via the protective member 42. However, the signal (electric field) radiated from the portion of the central electrode 41 that is narrower than the oval pen tip that is closer to the rear end side is suppressed by the action of the space 43 and the protective member 42. That is, this is because the dielectric constants of the space 43 and the protective member 42 are different, and this portion functions like a double capacitor. As a result, even if the electronic pen 1 is tilted, a good position indication signal that does not become unnecessarily wide can be sent from the central electrode 41. It should be noted that, hereinafter, the electronic pen core body 4 is referred to as the core body 4.

[0043] In this example, the pressure transmission member 5 is formed of a non-conductive material such as a hard resin. The pressure transmission member 5 includes a cup-shaped core holding portion 5a having a recess and an extension portion 5b extending from the rear end of the core holding portion 5a in a direction opposite to the pen tip. An elastic member 5c having conductivity such as conductive rubber is fixed to the inner side surface of the recess of the core holding portion 5a. The elastic member 5c slightly protrudes (extends) from the inner side surface of the recess of the core holding portion 5a.

[0044] Therefore, if Figure 2As shown in the figure, if the rear end of the core body 4 is inserted into the recess of the core body holding portion 5a, the elastic member 5c tightens the periphery of the rear end of the core body 4, and the core body 4 can be assembled to the pressure transmission member 5. In addition, if the pen tip portion of the core body 4 assembled to the pressure transmission member 5 is pulled out by grabbing it like a nail, for example, the core body 4 can be removed from the pressure transmission member 5. In this way, by providing the annular elastic member 5c on the inner side surface of the recess of the core body holding portion 5a of the pressure transmission member 5, the core body 4 can be assembled to the pressure transmission member 5 and removed from the pressure transmission member 5.

[0045] like Figure 2 As shown, a core coil spring 41C is provided around the extension portion 5b of the pressure transmission member 5. In other words, the extension portion 5b of the pressure transmission member 5 passes through the central axis space portion of the core coil spring 41C. In this case, one turn (one circle) of the core coil spring 41C on the side of the core retaining portion 5a is fitted into a recessed portion provided on the side between the core retaining portion 5a and the extension portion 5b of the pressure transmission member 5, and the core coil spring 41C retains the pressure transmission member 5. However, the pressure transmission member 5 is not applied with force by the core coil spring 41C. That is, the pressure transmission member 5 is retained in the housing 2 in a state of being suspended from the core coil spring 41C.

[0046] The end of the core coil spring 41C on the pen tip side is electrically connected to the conductive elastic member 5c provided in the core holding portion 5a of the pressure transmission member 5, and the other end is connected to the transmission circuit 8s of the printed circuit board 8. Figure 2 In the embodiment, the other end of the core coil spring 41C is formed as the end of an extension line (conductor line) 41L extending from the core coil spring 41C. Thus, the position indication signal from the transmission circuit 8s of the printed circuit board 8 is supplied to the center electrode 41 of the core 4 through the core coil spring 41C and the elastic member 5c, and is transmitted from the center electrode 41 of the core 4 toward the position detection sensor.

[0047] The extension portion 5b of the pressure transmission member 5 is coupled to the pressure detection portion 6, and transmits the pressure applied to the core body 4 held by the core body holding portion 5a to the pressure detection portion 6. In this example, a threaded portion is provided on the rear end side of the extension portion 5b, and as described later, the pressure transmission member 5 is firmly coupled to the pressure detection portion 6 by screwing.

[0048] In this embodiment, the main part for realizing the electronic pen function provided on the front cap 22 side includes the peripheral electrode 13. The peripheral electrode 13 constitutes an example of a second electrode electrically separated from (biased from) the central electrode 41.

[0049] In this example, the peripheral electrode 13 is a transmitting and receiving electrode. The peripheral electrode 13 is formed into a tubular shape by a conductive material such as metal. Figure 2 As shown in FIG. 1 , the peripheral electrode 13 is arranged in a state of surrounding the central portion of the core body 4 from the middle portion in the axial direction except the front end portion to the rear end side and the core body holding portion 5a of the pressure transmission member 5. In this case, the peripheral electrode 13 is arranged on the front cap 22 side in a state where the axial center position thereof coincides with the axial center position of the central electrode 41. That is, the peripheral electrode 13 is arranged on the front cap 22 side of the pen tip side of the housing 2 in this example in a manner that does not receive the pressure applied to the core body 4. In this example, the pen tip side of the peripheral electrode 13 is tapered (conical), and the peripheral electrode 13 is configured to more easily receive the electric field from the outside (position detection sensor).

[0050] In this embodiment, if Figure 2 As shown, the front end surface of the pen tip side of the peripheral electrode 13 abuts against the inner front end surface of the front cap 22, and the outer side surface of a certain range from the pen tip side to the rear end side of the peripheral electrode 13 contacts the inner wall surface of the front cap 22. As a result, the peripheral electrode 13 is arranged in a manner that does not loosen in the direction intersecting the axial direction. In this example, the inner diameter of the portion of the pen tip side of the peripheral electrode 13 facing the core 4 is short and thick, and the inner diameter of the portion of the rear end side of the peripheral electrode 13 facing the core holding portion 5a of the pressure transmission member 5 is long and thin.

[0051] A tubular holding portion 31 formed on the pen tip side of the substrate holder 3 is disposed on the rear end side of the peripheral electrode 13. In this example, although detailed illustration is omitted, the substrate holder 3 is formed into a boat-like shape having a mounting surface for the printed substrate and a pressure detection portion disposed thereon to be described later, and is provided with the tubular holding portion 31 on the pen tip side.

[0052] like Figure 2 As shown in FIG. 1 , the end surface of the pen tip side of the tubular holding portion 31 abuts against the end surface of the rear end side of the peripheral electrode 13. Figure 2 As shown, the pressure transmission member 5 , a part of the pressure detection unit 6 described later, and the core coil spring 41C are accommodated in a space formed by the peripheral electrode 13 and the tubular holding unit 31 .

[0053] And, if Figure 2 As shown in FIG. 1 , a coil spring 13C for the peripheral electrode is disposed on the side of the tubular holding portion 31. One end of the coil spring 13C is electrically connected to the peripheral electrode 13. Figure 2 As shown, the other end of the coil spring 13C is connected to a transmission circuit 8s provided on the printed circuit board 8 provided on the substrate holder 3. Figure 2In the embodiment, the other end of the coil spring 13C is formed as the end of an extension line (conductor line) 13L extending from the coil spring 13C for the peripheral electrode. In addition, a grounding electrode 14 formed of a conductive material such as metal is provided outside the tubular holding portion 31. The grounding electrode 14 connects the housing body 21 and the grounding conductor of the printed circuit board 8.

[0054] In this example, the pressure detection unit 6 is a force sensor using a strain gauge (strain sensing element), and is configured such that a sensor unit 62 composed of a plurality of strain gauges is provided on a strain body 61. Figure 3 As shown. Figure 3 (A) is a three-dimensional view of the pressure detection unit 6, Figure 3 (B) is a side view.

[0055] like Figure 3 As shown in (A) and (B) of FIG. 1 , the strain body 61 is made of a material having elasticity, and in this example, includes a coupling portion 611 and a strain portion 612 for screwing the extension portion 5b of the pressure transmission member 5. In this example, the strain body 61 is made of a metal (SUS in this example) as an example of a material having elasticity. In this example, the strain body 61 is an insulating member coated with an insulating layer (not shown).

[0056] like Figure 2 The cross-sectional view and Figure 3 As shown in (A), the coupling portion 611 of the strain body 61 has a cylindrical appearance, and is configured such that a fitting recess 611a is formed in the cylinder. Figure 2 As shown, a threaded portion that is threadedly engaged with the threaded portion of the extending portion 5 b of the pressure transmission member 5 is formed in the fitting recess 611 a .

[0057] The strain portion 612 of the strain body 61 is composed of a thin and elastic plate-like member having a width narrower than the inner diameter of the housing 2 of the electronic pen 1. The strain portion 612 includes facing plate portions 612a and 612b, both ends of which are bent in the same direction at right angles and face each other in parallel, and a connecting plate portion 612c between the facing plate portions 612a and 612b.

[0058] In this example, if Figure 2 As shown in FIG. 1 , the facing plate portion 612a of the strain portion 612 is disposed on the substrate holder 3 in a state where the facing plate portion 612a is on the pen tip side. Figure 2 and Figure 3 As shown, a connecting portion 611 is connected and mounted on the surface of the facing plate portion 612a that faces the pen tip side by, for example, welding.

[0059] In this example, the sensor section 62 is disposed on the surface of the facing plate section 612b on the rear end side of the strain section 612 on the side facing the facing plate section 612a. The sensor section 62 is configured by forming a plurality of strain gauges (strain sensing elements) and conductive patterns (on the surface of the facing plate section 612b) on the insulating layer on the surface of the facing plate section 612b on the side facing the facing plate section 612a. Figure 3 In this example, the strain gauge uses a strain gauge whose resistance value changes according to the strain caused by the external force.

[0060] The pressure detection unit 6 of this example is disposed on the pressure detection unit installation portion of the substrate holder 3 in a state where the coupling portion 611 of the strain body 61 is located in the hollow portion of the tubular holding portion 31 of the substrate holder 3 and the extension portion 5b of the pressure transmission member 5 is screwed into and mounted on the coupling portion 611. Figure 2 In the embodiment, the pressure detection part of the substrate holder 3 is arranged in the axial direction space on the substrate holder 3 between the end surface of the rear end side of the tubular holding part 31 and the wall plate part 32 which is arranged upright from the substrate holder 3 in a direction perpendicular to the axial direction. Figure 2 As shown, a substrate placement portion on which the printed substrate 8 is placed is provided on the rear end side of the wall plate portion 32 of the substrate holder 3 .

[0061] And, if Figure 2 As shown, a locking and holding portion 32a is provided at the upper end of the wall plate portion 32 on the rear end side of the pressure detection portion arrangement portion of the substrate holder 3, which fits and locks the upper end of the opposing plate portion 612b on the rear end side of the strain portion 612 of the strain body 61 of the pressure detection portion 6. In addition, in this example, a through hole 32b is provided at the upper end of the wall plate portion 32 on the rear end side of the pressure detection portion arrangement portion of the substrate holder 3, through which the extension portion of the coil spring 41C for the core body and the extension portion of the coil spring 13C for the peripheral electrode pass. It should be noted that a V-shaped groove for accommodating the extension portion of the coil spring 41C for the core body and the extension portion of the coil spring 13C for the peripheral electrode may be provided at the upper end of the wall plate portion 32 on the rear end side of the pressure detection portion arrangement portion of the substrate holder 3 instead of the through hole 32b.

[0062] like Figure 2 As shown, the pressure detection unit 6 is arranged at the pressure detection unit installation part in a state where the coupling part 611 of the strain body 61 is located at the pen tip side and the upper end of the facing plate part 612b at the rear end side of the strain part 612 of the strain body 61 is fitted and locked and held at the locking and holding part 32a at the upper end of the wall plate part 32 at the rear end side of the pressure detection unit installation part of the substrate holder 3. At this time, the connecting plate part 612c of the strain part 612 is in a state of abutting against the pressure detection unit installation surface of the pressure detection unit installation part.

[0063] In this case, in the pressure detection part installation part of the substrate holder 3, the upper end of the facing plate part 612b on the rear end side of the strain part 612 of the strain body 61 is fitted and locked and held in the locking and holding part 32a on the upper end of the wall plate part 32 of the substrate holder 3, but the strain body 61 is not fixed to the pressure detection part installation surface of the pressure detection part installation part. Therefore, the pressure detection part 6 is in a state where the upper end of the facing plate part 612b on the rear end side of the strain body 61 is prevented from moving in the axial direction. In other words, the pressure detection part 6 is in a so-called cantilever beam state in which the upper end of the facing plate part 612b on the rear end side of the strain body 61 is fixed.

[0064] Therefore, if Figure 3 When a force in the axial direction is applied to the pressure detection part 6 as shown by the arrow in (B), the opposing plate parts 612a and 612b of the strain part 612 of the strain body 61 of the pressure detection part 6 are as follows: Figure 3 The plate 612a is deformed as shown by the dotted line in (B), and the strain corresponding to the deformation is detected by the strain gauge provided in the sensor section 62 of the facing plate section 612b. In this embodiment, the pressure applied in the direction of the arrow is detected based on the strain detected by the sensor section 62.

[0065] In this embodiment, since it is configured as above, Figure 2 In the embodiment, if pressure is applied to the front end of the core 4, the pressure is transmitted to the pressure detection unit 6 via the pressure transmission member 5. At this time, in the electronic pen 1 of this embodiment, the peripheral electrode 13 is an independent member completely separated from the core 4 and the pressure transmission member 5, and therefore does not participate in the pressure transmission at all.

[0066] In the pressure detection unit 6, the transmitted pressure becomes as follows Figure 3 As described above, the strain body 61 is displaced (deformed) by the external force indicated by the arrow in (B), and the strain based on the displacement (deformation) is detected by the sensor unit 62. In addition, the output corresponding to the strain detected by the sensor unit 62 is supplied to the detection circuit 64, and the detection circuit 64 detects the pressure (pen pressure) applied to the front end of the core body 4.

[0067] like Figure 2As shown, in this example, a printed circuit board 63 is provided on the connecting plate portion 612c of the strain portion 612 of the strain body 61, and a detection circuit 64 is provided on the printed circuit board 63. In addition, although it is omitted in the figure, the output end of the sensor portion 62 is connected to the detection circuit 64. It should be noted that the detection circuit 64 is connected to the transmission circuit 8s provided on the printed substrate 8. In addition, the power supply voltage is also supplied to the detection circuit 64 of the printed substrate 63 via the printed substrate 8. Therefore, although it is omitted in the figure, the lower part of the pressure detection portion arrangement portion of the substrate holder 3 and the lower part of the loading portion of the printed substrate 8 are thin-walled, and are configured to be provided with a conductor that electrically connects the printed substrate 8 and the printed substrate 63 via a through hole.

[0068] Figure 4 It is shown that the use Figure 1 , Figure 2 The equivalent circuit diagram of the electronic pen 1 according to the embodiment is shown in FIG. Figure 4 As shown, the central electrode 41 of the core 4 is connected to the transmission circuit 8s through the core coil spring 41C, and can send out a position indication signal with a frequency of, for example, f0. In addition, the peripheral electrode 13 is connected to the switch circuit SW through the coil spring 13C, and is connected to the transmission circuit 8s and the demodulation circuit 8r through the switch circuit SW. The switch circuit SW is switched and controlled by the control IC 10.

[0069] When the switch circuit SW is switched to the transmission circuit 8s side, the peripheral electrode 13 sends out a tilt detection signal having a frequency of, for example, f1 from the transmission circuit 8s. In addition, when the switch circuit SW is switched to the demodulation circuit 8r side, the peripheral electrode 13 receives a signal from the position detection device and supplies it to the demodulation circuit 8r. Thus, it is possible to receive a request for sending identification information from the position detection circuit side through the peripheral electrode 13, demodulate it using the demodulation circuit 8r, and notify the control IC 10 of the demodulation result. In this case, the control IC 10 controls the transmission circuit 8s to send a position indication signal including the identification ID of the device to the position detection device. In this way, the peripheral electrode 13 can send a tilt detection signal and receive an identification signal from the position detection circuit side. In addition, the peripheral electrode 13 receives a timing signal from the position detection circuit side. This timing signal is used to control the timing of sending the position detection signal sent from the central electrode 41 from the electronic pen 1.

[0070] In the pressure detection unit 6 , the strain detection output of the sensor unit 62 corresponding to the writing pressure applied to the core 4 is supplied to the detection circuit 64 . The detection circuit 64 detects the pressure (writing pressure) applied to the core 4 based on the strain detection output of the sensor unit 62 .

[0071] The pressure (writing pressure) applied to the core 4 detected by the detection circuit 64 can be included in the position indication signal in the transmission circuit 8s and transmitted to the position detection sensor from the core 4. In addition, the transmission circuit 8s is controlled by the control IC 10, and the supply of driving power to each circuit unit is performed by the power circuit 15. It should be noted that in the electronic pen 1 of this embodiment, the core coil spring 41C and the coil spring 13C do not function as inductor elements.

[0072] Specifically, the core coil spring 41C realizes the function of holding the core holding member 51 in the housing 2 in a state that can move with a high degree of freedom without applying force, and the function of supplying the position indication signal from the transmission circuit 8s to the central electrode 41 of the core 4. In addition, the coil spring 13C realizes the function of supplying the tilt detection signal from the transmission circuit 8s to the peripheral electrode 13 in a manner that does not affect the surroundings and without effort. In addition, the coil spring 13C realizes the function of supplying the signal received through the peripheral electrode 13 to the demodulation circuit 8r in a manner that does not affect the surroundings and without effort.

[0073] As described above, in the electronic pen 1 of the above-mentioned embodiment, the structure is to transmit pressure to the pressure detection unit 6 using a strain gauge in the active electrostatic capacitance type electronic pen 1 having the central electrode 41 and the peripheral electrode 13, so that the displacement of the core 4 (displacement (stroke) in the axial direction) can be reduced.

[0074] Furthermore, in the electronic pen 1 of the above-mentioned embodiment, only the central electrode 41 is displaced according to the pressure applied to the core body 4, and the peripheral electrode 13 is not subjected to the pressure applied to the core body 4, so that the signal from the position detection sensor side can be stably received by the peripheral electrode 13. In this case, the peripheral electrode 13 has a tapered shape toward the pen tip side, so that it can receive better and can send.

[0075] [Other embodiments]

[0076] Figure 5 This is a cross-sectional view showing a configuration example of another embodiment of the electronic pen of the present invention, and only the pen tip side which is a main part is shown.

[0077] The electronic pen 1A of this embodiment is an improved version of the electronic pen 1 of the above-mentioned embodiment. That is, in the electronic pen 1 of the above-mentioned embodiment, the printed circuit board 63 provided with the detection circuit for detecting the writing pressure based on the strain detection output of the pressure detection unit 6 is different from the printed circuit board 8 provided with the main circuit parts such as the transmission circuit 8s. In the electronic pen 1A of this embodiment, this point is improved and the printed circuit board can be configured as one. It should be noted that, for the components corresponding to the components of the electronic pen 1 of the above-mentioned embodiment, the suffix A is added to the same reference numerals (numbers) in the examples described below.

[0078] In the electronic pen 1A of this embodiment, as Figure 5 As shown in FIG. 1 , the peripheral electrode 13A is connected to the cylindrical housing (casing) 2A via an annular connecting member 24. The housing 2A and the peripheral electrode 13A are made of conductive metal in this example, similarly to the above-mentioned example.

[0079] like Figure 5 As shown, the peripheral electrode 13A of this example includes a rear end side portion 13Ab having an outer diameter equal to that of the outer diameter of the housing 2A and a pen tip side portion 13Aa having a conical outer shape having a tapered portion that becomes increasingly tapered toward the pen tip side, and is connected to the housing 2A via a connecting member 24 to form a pen tip side housing of the electronic pen 1A. Therefore, in this example, the peripheral electrode 13A is exposed to the outside.

[0080] The annular connecting member 24 is made of an insulating material (resin in this example), and plays the role of connecting the housing 2A and the peripheral electrode 13A and insulating and separating the two. The annular connecting member 24 is composed of an annular central portion 24M having an outer diameter equal to that of the housing 2A and the rear end portion 13Ab of the peripheral electrode 13A and a wall thickness greater than that of the housing 2A and the peripheral electrode 13A, an annular tip side flange portion 24Fa formed in a manner protruding from the annular central portion 24M in the axial direction toward the pen tip side, and an annular rear end side flange portion 24Fb formed in a manner protruding from the annular central portion 24M in the axial direction toward the rear end side.

[0081] The outer diameter of the pen tip side flange portion 24Fa of the connecting member 24 is slightly smaller than the inner diameter of the rear end side portion 13Ab of the peripheral electrode 13A. In addition, the outer diameter of the rear end side flange portion 24Fb of the connecting member 24 is slightly smaller than the inner diameter of the housing 2A.

[0082] And, if Figure 5As shown in the figure, the peripheral electrode 13A is attached to the connecting member 24 by inserting the pen tip side flange portion 24Fa of the connecting member 24 into the rear end side portion 13Ab of the peripheral electrode 13A. In this case, the pen tip side flange portion 24Fa of the connecting member 24 can be pressed into the rear end side portion 13Ab of the peripheral electrode 13A to maintain the connection state of the two, or the pen tip side flange portion 24Fa can be bonded to the rear end side portion 13Ab of the peripheral electrode 13A to maintain the connection state of the two.

[0083] In addition, if Figure 5 As shown in the figure, the connecting member 24 is attached to the housing 2A by inserting the rear end side flange portion 24Fb of the connecting member 24 into the interior of the pen tip side portion of the housing 2A. In this case, the connecting member 24 may be pressed into the interior of the pen tip side portion of the housing 2A to maintain the connection state of the two, or the rear end side flange portion 24Fb may be bonded to the interior of the pen tip side portion of the housing 2A to maintain the connection state of the two.

[0084] The core 4A in this embodiment is configured such that a center electrode 41A made of a conductive material, for example, a conductive metal, is covered with a protection member 42A made of an insulating material in a state where the rear end side of the center electrode 41A protrudes.

[0085] The pressure transmission member 5A in this embodiment is made of a conductive material (conductive metal in this example). The pressure transmission member 5A has a fitting portion at the pen tip side portion 5Aa for fitting the exposed rear end side portion of the center electrode 41A of the core body 4A, and an elastic member 5Ac such as conductive rubber is provided in the fitting portion. Figure 5 As shown in the figure, the rear end side of the core body 4A is inserted from the opening on the pen tip side of the peripheral electrode 13A, and the rear end portion of the central electrode 41A of the core body 4A that is not covered by the protective member 42A is fitted into the fitting portion of the pen tip side portion 5Aa of the pressure transmission member 5A, and is tightened by the elastic member 5Ac, so that the core body 4A is assembled to the pressure transmission member 5A. In this example, the core body 4A can also be attached and detached.

[0086] In this example, a donut-shaped portion 24FaD having a through hole in the center is provided at the end of the pen tip side of the pen tip side flange portion 24Fa of the connecting member 24, and the pen tip side portion 5Aa of the pressure transmission member 5A is inserted and arranged in a state that it can move in the through hole portion. In addition, the rear end side portion 5Ab of the pressure transmission member 5A is configured to be larger than the through hole of the donut-shaped portion 24FaD of the connecting member 24. The rear end side portion 5Ab of the pressure transmission member 5A becomes a portion with which the coupling portion 611A of the strain body 61A of the pressure detection portion 6A is engaged.

[0087] The pressure detection unit 6A of this embodiment is similar to the pressure detection unit 6 in the above-mentioned embodiment, and is configured such that a sensor unit 62A using a strain gauge is provided on a strain body 61A. In this example, the strain body 61A is also composed of a joint 611A and a strain part 612A. The strain part 612A is composed of a slender and elastic plate-like member similar to the strain part 612 of the strain body 61 of the pressure detection unit 6 in the above-mentioned example, but the bending shape is different from the strain part 612 in the above-mentioned example.

[0088] That is, Figure 5 As shown, in this example, the elongated plate-like member is bent at right angles at three locations in the longitudinal direction. As a result, the strain portion 612A is configured as a structure in which four plate portions 612Aa, 612Ab, 612Ac, and 612Ad are connected in sequence from the pen tip side.

[0089] In this case, the plate portion 612Ad of the plate-shaped member constituting the strain portion 612A, which is the rear end side, is embedded and fixed to the pen tip side of the substrate holder 3A in a state of being oriented parallel to the axial direction of the electronic pen 1A. In this example, in addition to the transmission circuit (signal generation circuit) 8s, the demodulation circuit 8r, the switch circuit SW, the control IC 10A, etc., the substrate holder 3A is also equipped with a detection circuit 64A that detects pressure (writing pressure) based on the strain detection output from the pressure detection unit 6A.

[0090] The plate portion 612Ac of the strain portion 612A is a portion bent upward at a right angle relative to the plate portion 612Ad. Figure 5 As shown, it has a surface facing the printed circuit board 8A side mounted on the board holder 3A, and a sensor section 62A using a strain gauge is provided on this surface.

[0091] The plate portion 612Ab of the strain portion 612A is a portion that is bent at a right angle to the pen tip side in the axial direction relative to the plate portion 612Ac. Furthermore, the plate portion 612Aa closest to the pen tip side of the strain portion 612A is a portion that is bent in a manner that is parallel to the plate portion 612Ac in the direction perpendicular to the axial direction to the pen tip side of the plate portion 612Ab.

[0092] Furthermore, the plate portion 612Aa of the strain portion 612A closest to the pen tip is as shown in FIG. Figure 5 As shown by the dotted line, the bonding portion 611A is embedded in the bonding portion 611A made of an insulating material (resin in this example). Figure 5 As shown, the coupling portion 611A includes a fitting convex portion 611Aa that is fitted into a fitting concave portion of the rear end side portion 5Ab of the pressure transmission member 5A.

[0093] In this case, the pressure detection part 6A is in a state of a so-called cantilever beam in which the plate part 612Ad of the strain part 612A of the strain body 61A is fixed to the substrate holder 3A. Therefore, when an axial force is applied to the pressure detection part 6A, the plate part 612Ac of the strain part 612A of the strain body 61A of the pressure detection part 6A is deformed, and the strain corresponding to the deformation is detected by the strain gauge of the sensor part 62A provided on the plate part 612Ac.

[0094] In this embodiment, since it is configured as above, Figure 5 In the embodiment, if pressure is applied to the front end of the core 4A, the pressure is transmitted to the pressure detection unit 6A via the pressure transmission member 5A. At this time, in the electronic pen 1A of this embodiment, the peripheral electrode 13A is an independent member completely separated from the core 4A and the pressure transmission member 5A, and therefore does not participate in the pressure transmission at all.

[0095] In the pressure detection unit 6A, the transmitted pressure is detected as strain by the sensor unit 62A provided in the strain body 61, and the output corresponding to the strain detected by the sensor unit 62A is supplied to the detection circuit 64A, which detects the pressure (pen pressure) applied to the front end of the core 4A.

[0096] like Figure 5 As shown in FIG. 1 , in this example, a detection circuit 64A for detecting pen pressure is provided on the substrate holder 3A together with the control IC 10A, the transmission circuit and other main circuit parts. Also, although not shown in the figure, the output end of the sensor part 62 is connected to the detection circuit 63. It should be noted that in this example, the circuit structure of the electronic pen 1A is also similar to that of the electronic pen 1A. Figure 3 The structure shown is the same structure.

[0097] In addition, in this embodiment, since the pressure transmission member 5A is made of conductive metal, when the core 4A is mounted on the pressure transmission member 5A, the center electrode 41A and the pressure transmission member 5A are electrically connected. Taking advantage of this, in this embodiment, one end of the core connection wire 41AL, which is made of a coated wire in this example, is connected to the rear end portion 5Ab of the pressure transmission member 5A, and the other end is connected to the printed circuit board 8A, and is connected to the transmission circuit provided on the printed circuit board 8A. Thus, the signal from the transmission circuit is supplied to the center electrode 41A through the core connection wire 41AL and the pressure transmission member 5A, and is sent from the center electrode 41A to the position detection sensor.

[0098] In addition, in this embodiment, if Figure 5As shown in FIG. 1 , the peripheral electrode 13A and the printed circuit board 8A are also connected by the peripheral electrode connection wire 13AL composed of a covered conductive wire in this example. In this example, a through hole 24Fah for inserting the peripheral electrode connection wire 13AL is formed in the tip side flange portion 24Fa of the connecting member 24, and the peripheral electrode connection wire 13AL is arranged so as to be inserted through the through hole 24Fah to electrically connect the peripheral electrode 13A and the printed circuit board 8A.

[0099] In this Figure 5 In the electronic pen 1A of the example, since the peripheral electrode 13A is structured not to be displaced by the pressure applied to the core 4A, the peripheral electrode 13A can stably receive the signal from the position detection sensor side. Figure 5 In the electronic pen 1A of the example, since the peripheral electrode 13A is exposed to the outside, it is possible to sensitively receive a signal from the position detection sensor.

[0100] In addition, in this Figure 5 In the electronic pen 1A of the example, since only the printed circuit board 8A is placed on the circuit board holder 3A, the printed circuit board 63 in the case of the electronic pen 1 described above can be omitted, and the structure can be simplified.

[0101] [Other embodiments or modifications]

[0102] In the electronic pens 1 and 1A of the above-described embodiments, the peripheral electrodes 13 and 13A are configured to be capable of transmitting and receiving, but may be configured as electrodes dedicated to reception.

[0103] In addition, the pressure (pen pressure) applied to the core body 4, 4A is configured to be transmitted to the pressure detection unit 6, 6A via the pressure transmission component 5, 5A, but the core body and the pressure detection unit can be directly combined without using the pressure transmission component 5, 5A, so that the pressure applied to the core body is directly transmitted to the pressure detection unit.

[0104] In addition, in the above-mentioned embodiment, the strain bodies 61 and 61A of the pressure detection parts 6 and 6A are configured as a single plate-shaped member, but are not limited to such a structure. For example, the following structure may be adopted: the plate-shaped member of the strain part 612 of the strain body 61 is divided into two L-shaped parts at the middle part of the connecting plate part 612c, and the two L-shaped parts are joined in a manner to form the connecting plate part 612c.

[0105] Description of Reference Numerals

[0106] 1, 1A…electronic pen, 2, 2A…housing (shell), 3, 3A…substrate holder, 4, 4A…core, 5, 5A…pressure transmission member, 6, 6A…pressure detection portion, 13, 13A…peripheral electrode, 13C…coil spring for peripheral electrode, 13L, 41L…extension wire of coil spring, 13AL…connecting wire for peripheral electrode, 22…housing cap, 24…connecting member, 41…coil spring for core, 41AL…connecting wire for core, 61, 61A…strain body, 62, 62A…sensor portion.

Claims

1. An electronic pen, characterized in that: have: The housing has an opening at one end in the axial direction; The core is configured so that the front end thereof protrudes to the outside from one opening of the housing, and has a first electrode for generating a first electric field for position indication; a second electrode electrically separated from the first electrode and arranged in a manner capable of receiving an external electric field; and The pressure detection unit detects the pressure applied to the core body using a strain gauge. The core is directly or indirectly coupled to the pressure detection unit so that the pressure is transmitted to the pressure detection unit, and The second electrode is not coupled to the pressure detection portion and is disposed so as not to receive the pressure when the pressure is applied to the core.

2. The electronic pen according to claim 1, characterized in that: The second electrode is a peripheral electrode configured to surround the first electrode.

3. The electronic pen according to claim 2, characterized in that: The first electrode is arranged so that its axial center position coincides with the axial center position of the housing, and The second electrode is disposed so that the axial center position thereof coincides with the axial center position of the housing.

4. The electronic pen according to claim 1, characterized in that: A switching circuit is provided for switching the second electrode between reception and transmission.

5. The electronic pen according to claim 1, characterized in that: A pressure transmitting member is provided for transmitting the pressure applied to the core to the pressure detecting portion. The pressure transmission member is made of a conductive material, and when the core is coupled to the pressure transmission member, the pressure transmission member and the first electrode of the core are electrically connected.

6. The electronic pen according to claim 1, characterized in that: The pressure detection part includes a combination part and a strain part. The combining portion is used to combine with the core directly or indirectly. The strain portion is coupled to the coupling portion and deforms in accordance with the pressure transmitted to the coupling portion. The strain portion is provided with a sensor portion using the strain gauge.

7. The electronic pen according to claim 1, characterized in that: The core has a structure in which the first electrode is covered with a protective member.

8. The electronic pen according to claim 1, characterized in that: The core has a structure in which the first electrode is covered with a protective member, and a space is provided in a portion between the first electrode and the protective member.

9. The electronic pen according to claim 2, characterized in that: The second electrode includes a tapered portion that tapers toward a front end portion of the core.

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