Patent Publication Number: US-11662840-B2

Title: Capacitance electronic pen

Description:
BACKGROUND 
     Technical Field 
     The disclosure relates to a capacitance electronic pen used along with a position detection apparatus. 
     Background Art 
     An example of a prized capacitance electronic pen includes a generally-called active capacitance electronic pen that performs a transfer (interaction) of a signal to and from a position detection sensor of a position detection apparatus through electric field coupling, thereby allowing the position detection sensor to detect a position instructed by the electronic pen. 
     This type of electronic pen includes, in a hollow portion of a cylindrical housing, a battery (primary battery or secondary battery) as a power supply, a pen pressure detection unit, a circuit board provided with a signal transmission circuit, and the like, in which the components are lined up and housed in an axial direction of the housing of the electronic pen. 
     In this case, the circuit board is mounted on a board holder, and the pen pressure detection unit includes pressure sensing components and pressure transmission members housed in a housing for pen pressure detection unit. Furthermore, the pen pressure detection unit and the board holder are often coupled in the axial direction of the housing of the electronic pen to form a unit (form a module). The board holder includes a housing part of the pen pressure detection unit in some cases. 
     In the electronic pen, constituent components of the electronic pen and the battery are lined up in the axial direction and housed in the hollow portion of the cylindrical housing. In this way, a unit of the constituent components of the electronic pen is formed, and the electronic pen can prevent an impact on an internal circuit caused by a drop impact, can increase the strength, and can slightly adjust the internal circuit. In addition, there is an advantage that only the housing of the electronic pen is replaced to allow handling the electronic pen in various housing shapes. 
     Meanwhile, in active capacitance electronic pens of recent years, an electronic pen of two-way communication has emerged that receives a signal from a position detection sensor side, which detects an instruction position of the electronic pen, and that transmits a signal in a format based on a request of the received signal (for example, see Patent Document 1 (Japanese Patent Laid-Open No. 2016-134168)). 
     In this type of electronic pen of two-way communication, the position and the size of a reception unit (antenna) that receives the signal from the position detection sensor are important. In the case of the capacitance electronic pen, the signal transmitted from the position detection sensor is based on an electric field that can be received through capacitive coupling, and the travel distance is significantly short. Therefore, the reception unit (antenna) of the electronic pen of two-way communication is arranged at a position close to the pen tip to allow the signal from the position detection sensor to be received at high strength. Furthermore, the reception unit (antenna) of the electronic pen needs to have a size that provides a reception range as large as possible. 
     Therefore, in the electronic pen of Patent Document 1, the reception unit (antenna) includes a peripheral electrode including a cylindrical conductor provided to cover around a core body made of a conductive material, up to near a tip portion of the core body, while electrical insulation from the core body is taken into account. 
     Furthermore, it is proposed in recent years to use a position detection apparatus to detect a tilt angle of the electronic pen with respect to the position detection sensor surface (angle formed by the axial direction of the electronic pen and the position detection sensor surface) and to reflect the detected tilt angle on the thickness or the like of an instruction trajectory (writing trace) of the electronic pen. An example of this type of electronic pen corresponding to the detection of the tilt angle is disclosed in, for example, Patent Document 2 (Japanese Patent Laid-Open No. 2016-126503). 
     As disclosed in Patent Document 2, this type of electronic pen corresponding to the detection of the tilt angle or the like also includes a peripheral electrode including a cylindrical conductor provided to cover around the core body, up to near the tip portion of the core body, as in the electronic pen of two-way communication. 
       FIGS.  6 A and  6 B  illustrate an example of a configuration on a pen tip side of this type of conventional capacitance electronic pen.  FIG.  6 A  illustrates an appearance of the electronic pen, and  FIG.  6 B  is a longitudinal cross-sectional view of the electronic pen. An electronic pen  100  of this example includes a front cap  102  including a tapered cylindrical body fitted and attached to an opening on the pen tip side of a cylindrical housing  101  as illustrated in  FIGS.  6 A and  6 B . The housing  101  is made of a conductive material, such as metal, so that the housing  101  is earthed (grounded) through the human body when the user holds and operates the electronic pen  100 . In addition, the front cap  102  is made of an insulating material, such as a resin. 
     As illustrated in  FIG.  6 B , an opening  102   a  is provided on the tapered pen tip side of the front cap  102  so that a core body  103  can be inserted and freely moved in the axial direction. The core body  103  is made of a conductive material. The core body  103  is inserted into the housing of the electronic pen  100  from the opening  102   a  of the front cap  102  and is held by a core body holder  113  described later, with a tip portion  103   a  of the core body  103  protruding outside. In this case, the core body  103  made of a conductive material and the housing  101  made of a conductive material are electrically separated (insulated) through the front cap  102 . 
     As illustrated in  FIG.  6 B , a board holder  105  that places, on a mounting portion  105   a , a printed board  104  provided with circuit components, such as a signal transmission circuit, is housed in a hollow portion of the housing  101 . The board holder  105  is made of a resin that is an insulating material elongated in the axial direction, and in the example of  FIG.  6 B , the board holder  105  includes a cylindrical portion  105   b  on the pen tip side in the axial direction with respect to the mounting portion  105   a . Pressure sensing components and pressure transmission members included in a pen pressure detection unit  106  are housed in the cylindrical portion  105   b . The pen pressure detection unit  106  of the example includes a variable capacitor in which the capacitance changes according to the pen pressure applied to the core body  103 . 
     The pressure sensing components of the example include a plurality of components including a dielectric  107 , a terminal member  108 , a holding member  109 , a conductive member  110 , and an elastic member  111  as illustrated in  FIG.  6 B . The terminal member  108  is made of a conductive material, such as SUS, and is included in a first electrode of a variable capacitor including pressure sensing components. In addition, the conductive member  110  is made of, for example, conductive rubber, and the elastic member  111  includes a coil spring made of a conductive material, such as SUS. The conductive member  110  and the elastic member  111  are electrically connected and provide a second electrode of the variable capacitor. The conductive member  110  is held by the holding member  109 . Furthermore, the elastic member  111  is arranged between the dielectric  107  and the holding member  109 , and the elastic member  111  is provided so that the conductive member  110  is biased all the time in a direction away from the dielectric  107 . 
     The side of the core body  103  opposite the tip portion is fitted to the core body holder  113  made of a conductive material through a conductive elastic member  112 , and the core body  103  is coupled to and held by the core body holder  113 . Furthermore, the core body holder  113  is fitted to the holding member  109  of the pressure sensing components in the cylindrical portion  105   b  of the board holder  105 , and the pressure (pen pressure) applied to the core body  103  is transmitted to the pressure sensing components. 
     In this case, the core body holder  113  including the conductive elastic member  112  functions as a pressure transmission member that transmits, to the pressure sensing components, the pressure (pen pressure) applied to the core body  103 . In this case, the core body holder  113  is housed in a housing  114  for holding the core body holder  113  as illustrated in  FIGS.  6 A and  6 B . 
     Furthermore, a coil spring  115  that always biases the core body holder  113  toward the core body  103  is provided in the housing  114 . The coil spring  115  is made of a conductive material, such as conductive metal, and one end of the coil spring  115  is electrically connected to the signal transmission circuit arranged on the printed board  104 , although not illustrated. 
     The core body holder  113  is made of a conductive material, and the core body  103  made of a conductive material and installed on the core body holder  113  through the conductive elastic member  112  is electrically connected to the signal transmission circuit arranged on the printed board  104  through the coil spring  115 . 
     In the electronic pen  100  of the example, the core body  103  is displaced inside of the housing  101  of the electronic pen  100  in the axial direction when the pressure (pen pressure) is applied to the front end side of the core body  103 . Consequently, the core body holder  113  provided with the core body  103  is displaced in the axial direction together with the core body  103 , and the conductive member  110  is displaced toward the dielectric  107  against the elastic force of the elastic member  111  of the pressure sensing components. Consequently, the contact area of the conductive member  110  and the dielectric  107  is changed according to the applied pressure, and the capacitance of the variable capacitor including the pen pressure detection unit  106  is changed according to the applied pressure. Therefore, the pen pressure can be detected based on the capacitance of the variable capacitor including the pen pressure detection unit  106 . 
     Furthermore, in the electronic pen  100  of the example, a peripheral electrode  116  made of a conductor material surrounding the core body  103  is fitted to a peripheral portion of the cylindrical portion  105   b  of the board holder  105  on the pen tip side as illustrated in  FIG.  6 B . The peripheral electrode  116  is electrically connected to the circuit components of the printed board  104  although not illustrated in  FIG.  6 B . 
     In this case, the peripheral electrode  116  is electrically separated (insulated) from the core body  103  due to the existence of a section near the opening portion  102   a  of the front cap  102 . In addition, the front cap  102  also plays a role of electrically separating (insulating) the peripheral electrode  116  and the housing  101  of the electronic pen  100  as illustrated in  FIG.  6 B . 
     PRIOR ART DOCUMENT 
     Patent Documents 
     
         
         Patent Document 1: Japanese Patent Laid-Open No. 2016-134168 
         Patent Document 2: Japanese Patent Laid-Open No. 2016-126503 
       
    
     BRIEF SUMMARY 
     Technical Problems 
     Meanwhile, a portable terminal, such as a notebook computer and a tablet, of recent years is provided with a capacitance position detection sensor on which a display screen is placed, and the terminal can receive an instruction input of a capacitance electronic pen. Furthermore, the size and the thickness of this type of portable device are reduced to further improve the portability. Therefore, the size and the thickness of the capacitance electronic pen associated with the position detection sensor of this type of portable terminal also need to be reduced. 
     However, in the conventional electronic pen, the pressure sensing components and the core body holder  113  as a pressure transmission member housed in the housing  114  are housed in the cylindrical portion  105   b  of the board holder  105  in the pen pressure detection unit  106  as illustrated in  FIG.  6 B . Therefore, the cylindrical portion  105   b  of the board holder  105  providing the housing of the pen pressure detection unit  106  needs to have a thickness that allows to house the core body holder  113  as a pressure transmission member housed in the housing  114 , and it is difficult to reduce the thickness due to the existence of the housing  114 . 
     Furthermore, in the electronic pen of two-way communication or the electronic pen compatible with the detection of the tilt angle, the cylindrical peripheral electrode  116  needs to be electrically separated (insulated) from the housing  101  and the core body  103  and provided on the pen tip side of the electronic pen  100  as illustrated in  FIG.  6 B . 
     To realize the electrical separation (insulation) between the housing  101  and the peripheral electrode  116  in the conventional electronic pen  100 , the front cap  102  made of an insulating material is provided on the pen tip side of the electronic pen  100 , and the front cap  102  realizes the electrical separation (insulation) of the peripheral electrode  116  from the housing  101  and the core body  103 . Therefore, the front cap  102  is placed between the housing  101  and the peripheral electrode  116  and between the peripheral electrode  116  and the core body  103  in the direction orthogonal to the axial direction of the electronic pen  100 , and it is difficult to reduce the thickness of the electronic pen. In addition, the front cap  102  needs to have a complicated shape to provide the insulation. 
     In view of the problems, an object of the disclosure is to provide a capacitance electronic pen in which the thickness can be reduced. 
     Technical Solution 
     To solve the problems, provided is an electronic pen that includes: a cylindrical housing having a hollow portion, a core body made of a conductive material, the core body having a front end that protrudes from an opening in a side of the cylindrical housing, a plurality of components arranged in an axial direction of the housing in the hollow portion, a cylindrical coupling member made of an insulating material, the cylindrical coupling member housing at least some of the plurality of components. The cylindrical housing includes a first housing portion and a second housing portion separated in the axial direction of the housing. The first housing portion is made of a conductive material and includes an opening arranged such that the front end of the core body protrudes outside of the first housing portion through the opening in a state in which the first housing portion is electrically separated from the core body. A protrusion portion is formed on an outer peripheral surface of the cylindrical coupling member and the protrusion portion extends in a direction orthogonal to the axial direction of the housing from the peripheral side surface. An end surface of the protrusion portion is part of the cylindrical housing. A first side of the cylindrical coupling member in the axial direction of the housing with respect to the protrusion portion is fitted to the first housing portion, and a second side of the cylindrical coupling member in the axial direction of the housing with respect to the protrusion portion is fitted to the second housing portion. The first housing portion and the second housing portion are separated by the protrusion portion. 
     In the electronic pen with the configuration, some of the plurality of components included in the electronic pen, such as part of pen pressure detection components, can be housed in the hollow portion of the cylindrical coupling member. That is, a housing of a pen pressure detector can also be used as the cylindrical coupling member. In the cylindrical coupling member, the protrusion portion is part of the housing, and the thickness of the electronic pen can be reduced. 
     Furthermore, in the electronic pen with the configuration, the housing is divided into two portions, the first housing portion and the second housing portion. The first housing portion on the pen tip side is made of a conductive material. The first housing portion and the second housing portion are fitted to the first side and the second side of the cylindrical coupling member in the axial direction with respect to the protrusion portion to provide the housing of the electronic pen. In this case, the first housing portion and the second housing portion are not in contact with each other and are separated without coming into contact with each other due to the existence of the protrusion portion. 
     Therefore, in the electronic pen with the configuration, the first housing made of a conductive material can be provided as a peripheral electrode of an electronic pen of two-way communication or as a peripheral electrode of an electronic pen compatible with detection of a tilt angle. That is, the peripheral electrode can be provided as part of the housing. Therefore, the configuration is simplified, and the thickness of the electronic pen can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS.  1 A and  1 B  depict diagrams for describing a configuration example of an electronic pen according to an embodiment of the present disclosure. 
         FIG.  2    is a diagram for describing a configuration example of parts of an electronic pen according to an embodiment of the present disclosure. 
         FIGS.  3 A and  3 B  depict diagrams for describing constituent components of an electronic pen according to an embodiment of the present disclosure. 
         FIG.  4    is a diagram for describing constituent components of an electronic pen according to an embodiment of the present the present disclosure. 
         FIG.  5    is a diagram for describing a circuit example of an electrical configuration of an electronic pen according to an embodiment of the present disclosure. 
         FIGS.  6 A and  6 B  depicts diagrams for describing a configuration example of a conventional electronic pen. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS.  1 A and  1 B  depicts diagrams for describing a configuration example of a capacitance electronic pen  1  according to an embodiment of the present disclosure. FIG.  1 A is a diagram illustrating an appearance of the electronic pen  1 , and  FIG.  1 B  is a longitudinal cross-sectional view on a pen tip side of the electronic pen  1 . In addition,  FIG.  2    is an exploded perspective view for describing a configuration of a housing  10  of the capacitance electronic pen  1 . 
     The housing  10  of the capacitance electronic pen  1  of the embodiment includes a first housing portion  11  on the pen tip side and a second housing portion  12  on a back end side that are coupled through a cylindrical coupling member  13 . Furthermore, a core body  21  is held such that a tip portion  21   a  of the core body  21  protrudes outside from an opening  10   a  (see  FIG.  1 B ) on the first housing portion  11  side of the housing  10 . The core body  21  is made of a conductive material, such as conductive metal, and the core body  21  includes a rod-like body as illustrated in  FIG.  1 B . 
     Each of the first housing portion  11  on the pen tip side and the second housing portion  12  on the back end side is made of a conductive material, such as conductive metal, and the first housing portion  11  and the second housing portion  12  include cylindrical bodies as illustrated in  FIGS.  1 A,  1 B, and  2   . 
     The first housing portion  11  is shaped to include a cylindrical shape portion  11   a  with a constant outer diameter and a tapered portion  11   b  formed in a tapered shape gradually becoming narrower toward the pen tip side as illustrated in  FIGS.  1  and  2   . The second housing portion  12  has a cylindrical shape with an outer diameter equal to the outer diameter of the cylindrical shape portion  11   a  of the first housing portion  11 . 
     The cylindrical coupling member  13  is made of an insulating material, a resin in the example, and is a cylindrical body as illustrated in  FIGS.  1 B and  2   . At a position close to the center of a peripheral surface in the axial direction, a ring-shaped flange portion  13 F (protruding portion) protruding in the direction orthogonal to the axial direction from the peripheral side surface is formed. The ring-shaped flange portion  13 F has a predetermined width W (see  FIGS.  1 B, and  2   ) in the axial direction. An end surface of the ring-shaped flange portion  13 F is flush with the first housing portion  11  and the second housing portion  12  without a difference in level and is part of the housing  10  as illustrated in  FIGS.  1 A and  1 B . That is, the diameter of the peripheral portion of the ring-shaped flange portion  13 F is selected to be equal to the outer diameter of the first housing portion  11  and the second housing portion  12 . 
     Furthermore, the pen tip side that is one side of the cylindrical coupling member  13  in the axial direction with respect to the ring-shaped flange portion  13 F is a first fitting cylindrical portion  13   a  fitted to the cylindrical shape portion  11   a  of the first housing portion  11 . The outer diameter of the first fitting cylindrical portion  13   a  of the cylindrical coupling member  13  is equal to or slightly smaller than the inner diameter of the cylindrical shape portion  11   a  of the first housing portion  11 . The cylindrical shape portion  11   a  of the first housing portion  11  is pressed, fitted, and coupled to the first fitting cylindrical portion  13   a  of the cylindrical coupling member  13 , up to the location of the ring-shaped flange portion  13 F. 
     In addition, the back end side of the cylindrical coupling member  13  in the axial direction with respect to the ring-shaped flange portion  13 F is a second fitting cylindrical portion  13   b  fitted to the second housing portion  12 . The outer diameter of the second fitting cylindrical portion  13   b  of the cylindrical coupling member  13  is equal to or slightly smaller than the inner diameter of the second housing portion  12 . The second housing portion  12  is pressed, fitted, and coupled to the second fitting cylindrical portion  13   b  of the cylindrical coupling member  13 , up to the location of the ring-shaped flange portion  13 F. 
     The first housing portion  11  and the second housing portion  12  are inserted, fitted, and coupled to the cylindrical coupling member  13  as indicated by arrows in  FIG.  2   , and in this state, the housing  10  as one cylindrical body is formed as illustrated in  FIGS.  1 A and  1 B . In this case, as described above, the peripheral surface of the cylindrical shape portion  11   a  of the first housing portion  11 , the peripheral surface of the second housing portion  12 , and the end surface of the ring-shaped flange portion  13 F are flush with each other. Furthermore, the first housing portion  11  and the second housing portion  12  made of a conductive material are not in contact with each other and are electrically separated (insulated) from each other due to the existence of the ring-shaped flange portion  13 F of the cylindrical coupling member  13 . 
     A front cap  14  made of an insulating material, such as a resin, is provided at an opening  11   c  (see  FIG.  2   ) on the pen tip side of the first housing portion  11  as illustrated in  FIGS.  1 A and  1 B . The opening  10   a  with a diameter slightly larger than the diameter of the core body  21  is formed on the front cap  14 . The core body  21  is inserted into the housing  10  of the electronic pen  1  through the opening  10   a  of the front cap  14 . The core body  21  and the first housing portion  11  made of a conductive material are electrically separated (insulated) by the front cap  14  as an insulating material as illustrated in  FIG.  1 B . In the electronic pen  1  of the embodiment, the first housing portion  11  is provided to cover the back end side of the core body  21  with respect to the tip portion  21   a  as illustrated in  FIG.  1 B , and the first housing portion  11  provides a peripheral electrode. 
     A board holder  30  provided with a printed circuit board  31  mounted on a board mounting table portion  301  and a battery  32  as a power supply are housed in a hollow portion of the second housing portion  12  as illustrated in  FIGS.  1 A and  1 B . The battery  32  may be a primary battery or may be a secondary battery (rechargeable battery). The back end side of the second housing portion  12  is blocked by a back cap  15  as illustrated in  FIG.  1 A . 
     The board holder  30  is made of an insulating resin, and the board holder  30  includes a pressure sensing component holding portion  302  on the opposite side of the board mounting table portion  301  side in the longitudinal direction that is the axial direction of the electronic pen  1 . When the board holder  30  is housed in the hollow portion of the housing  10 , the pressure sensing component holding portion  302  and the board mounting table portion  301  are continuous in the longitudinal direction that is the axial direction of the electronic pen  1  as illustrated in  FIG.  1 B . The pressure sensing component holding portion  302  has a cylindrical shape including a hollow portion that houses pressure sensing components  5  (a plurality of components for pen pressure detection) in a hollow portion inside. The board mounting table portion  301  has a boat-like shape that mounts and holds the printed circuit board  31  and has a shape as if a cylindrical body is cut in substantially half in the axial direction. 
     The board holder  30  is housed in the housing  10  such that the pressure sensing component holding portion  302  is on the core body  21  side. Furthermore, a core body holder  23  that holds the core body  21  is coupled to the pressure sensing component holding portion  302 , and the pressure (pen pressure) applied to the core body  21  is transmitted to the pressure sensing components  5  of the pressure sensing component holding portion  302 . 
     The outer diameter of the pressure sensing component holding portion  302  of the board holder  30  is selected to be equal to or a little smaller than the outer diameter of the second fitting cylindrical portion  13   b  of the cylindrical coupling member  13  in the embodiment. Furthermore, as illustrated in  FIG.  2   , part of the pressure sensing component holding portion  302  of the board holder  30  is fitted to part of the second fitting cylindrical portion  13   b  of the cylindrical coupling member  13  to thereby couple the pressure sensing component holding portion  302  of the board holder  30  and the second fitting cylindrical portion  13   b  of the cylindrical coupling member  13 . 
     As illustrated in  FIGS.  1 B and  2   , the pressure sensing component holding portion  302  is fitted and coupled to the second fitting cylindrical portion  13   b  of the cylindrical coupling member  13  in the axial direction to regulate the position of the board holder  30  to prevent the board holder  30  from moving in the axial direction in the housing  10 . 
     Furthermore, although not illustrated, both ends of the battery  32  arranged on the opposite side of the pressure sensing component holding portion  302  on the board mounting table portion  301  of the board holder  30  are electrically connected to a power line and a copper foil pattern of an earth line of the printed circuit board  31 . In this way, the voltage of the battery  32  is supplied as a power supply voltage to the circuit formed on the printed circuit board  31 . 
     In the present embodiment, the second housing portion  12  made of a conductive material is electrically connected to the copper foil pattern of the earth line of the printed circuit board  31 . 
     In the present embodiment, a peripheral circuit unit is provided on the printed circuit board  31 , the peripheral circuit unit including an IC (Integrated Circuit)  41  (see  FIGS.  1 A and  5   ) including a signal generation circuit that generates a signal to be transmitted from the core body  21  and a control circuit that controls the transmission of the signal from the signal generation circuit to the core body  21 , and peripheral circuit components of the IC  41 . Although not illustrated, the peripheral circuit unit includes a push switch (side switch) and a charging circuit of the battery  32 . 
     In the present embodiment, the core body  21  is fitted to the core body holder  23  made of a conductive material through a conductive elastic member  22  as illustrated in  FIG.  1 B , and the core body  21  is coupled to and held by the core body holder  23 . Furthermore, the core body holder  23  is fitted to a holding member  53  described later of the pressure sensing components  5  in the pressure sensing component holding portion  302  of the board holder  30 , and the pressure (pen pressure) applied to the core body  21  is transmitted to the pressure sensing components  5 . In this case, a coil spring  34  as an example of an elastic member made of a conductive material, such as conductive metal, provided between the core body holder  23  and the board holder  30  always biases the core body holder  23  toward the core body  21  with respect to the board holder  30 . Note that the coil spring  24  provides, along with a conductor terminal member  25  described later, an electrical connection member for transmitting the signal from the IC  41  arranged on the printed circuit board  31  to the core body  21 . 
       FIG.  3 A  is an exploded perspective view of the part of the core body  21 , the conductive elastic member  22 , the core body holder  23 , the coil spring  24 , and the pressure sensing component holding portion  302  of the board holder  30 . 
     The conductive elastic member  22  is made of, for example, conductive rubber and is formed in a cylindrical shape including a through hole  22   a  to which an end portion of the core body  21  on the opposite side of the tip portion  21   a  is fitted. The core body  21  side of the conductive elastic member  22  includes a thin portion with the outer diameter smaller than the outer diameter of the other parts, and slits  222  are formed to provide a grip portion  221  that facilitates gripping the core body  21 . 
     According to the configuration, an arc-shaped part of the grip portion  221  including two thin portions provided with the slit portions  222  is used to grip the core body  21 . Therefore, the core body  21  can be easily inserted and fitted to the grip portion  221  of the conductive elastic member  22  and can be pulled by predetermined force to easily pull out the core body  21  from the conductive elastic member  22 . 
     The core body holder  23  is made of, for example, a conductive material, such as SUS (Steel Special Use Stainless), and a house fitting portion  231  including a recess hole  231   a  for housing and fitting the conductive elastic member  22  and a rod-like portion  232  fitted to the holding member  53  described later of the pressure sensing components  5  are integrated to form the core body holder  23 . 
     After the conductive coil spring  24  is installed on the rod-like portion  232  of the core body holder  23  housing the conductive elastic member  22  as described above, the rod-like portion  232  of the core body holder  23  is fitted to the holding member  53  of the pressure sensing components  5  in the pressure sensing component holding portion  302  of the board holder  30 . 
     In this case, the transmission signal generated by the circuit provided on the printed circuit board  31  needs to be supplied to the core body  21 , and this needs to be taken into account in the electronic pen  1  of the present embodiment. However, the board holder  30  and the holding member  53  of the pressure sensing components  5  housed in the pressure sensing component holding portion  302  are made of a resin that is an insulating material, and the core body holder  23  and the holding member  53  cannot be electrically connected. 
     Therefore, in the present embodiment, the coil spring  24  made of a conductive material provided between the core body holder  23  and the pressure sensing component holding portion  302  of the board holder  30  and the conductor terminal member  25  provided in the pressure sensing component holding portion  302  of the board holder  30  provide electrical connection members, and the electrical connection members realize the electrical connection for supplying the signal from the signal transmission circuit of the printed circuit board  31 . 
     That is, in the embodiment, the conductor terminal member  25  made of a conductive material, such as SUS, is installed on the pressure sensing component holding portion  302  of the board holder  30  so as to cover an opening portion  302   a  side, into which the rod-like portion  232  of the core body holder  23  is inserted, as illustrated in  FIG.  3 A . 
     The conductor terminal member  25  includes, as illustrated in  FIGS.  3 A and  3 B , an abutment plate portion  251  that covers the opening portion  302   a  side of the pressure sensing component holding portion  302  of the board holder  30  and that includes a through hole  251   a  into which the rod-like portion  232  of the core body holder  23  is inserted, and attachment plate portions  252  and  253  orthogonal to the abutment plate portion  251  and facing each other. 
     In addition, an extension portion  254  extending to the part of the board mounting table portion  301  across the part of the pressure sensing component holding portion  302  of the board holder  30  is provided. A terminal portion  254   a  that is, for example, soldered to the back side of the printed circuit board  31  is formed on a tip portion of the extension portion  254  in the example. 
     Furthermore, in the state in which the conductor terminal member  25  is installed on the pressure sensing component holding portion  302  of the board holder  30 , the terminal portion  254   a  at the front end of the extension portion  254  extending from the conductor terminal member  25  is abutted to a conductor on the back surface side of the printed circuit board  31  mounted on the board mounting table portion  301  of the board holder  30  and is, for example, soldered as illustrated in  FIG.  1 B . In this way, the conductor terminal member  25  and the signal generation circuit formed on the front surface of the printed circuit board  31  are electrically connected. 
     Furthermore, as described above, in the state in which the rod-like portion  232  of the core body holder  23  provided with the conductive elastic member  22  is put through the coil spring  24 , the rod-like portion  232  is inserted into the hollow portion of the pressure sensing component holding portion  302  of the board holder  30  through the through hole  251   a  of the abutment plate portion  251  of the conductor terminal member  25  and fitted to the pressure sensing component holding portion  302 . The inner diameter of the coil spring  24  is larger than the external shape of the rod-like portion  232  of the core body holder  23 . 
     Therefore, the coil spring  24  elastically comes into contact with the core body holder  23  and abuts and elastically comes into contact with the abutment plate portion  251  of the conductor terminal member  25 . The coil spring  24  is made of a conductive material, and the conductive elastic member  22  and the core body holder  23  are conductive. Therefore, the conductive elastic member  22  fitted to the core body holder  23  through the coil spring  24  and the conductor terminal member  25  is electrically connected to the circuit unit of the printed circuit board  31 . 
     Furthermore, as described above, the core body  21  is inserted and fitted to the through hole  22   a  of the conductive elastic member  22  fitted to the core body holder  23  housed in the housing  10  as described above, and the core body  21  is held with respect to the core body holder  23  through the conductive elastic member  22 . In this state, the core body  21  is electrically connected to the signal transmission circuit of the printed circuit board  31 , and the signal from the signal transmission circuit is supplied to the core body  21 . 
     Next, the configuration of the pressure sensing component holding portion  302  of the board holder  30  and the pressure sensing components  5  as well as the fitting of the holding member  53  of the pressure sensing components  5  and the core body holder  23  will be described. 
       FIG.  4    is an exploded perspective view of the pressure sensing components  5  housed in the pressure sensing component holding portion  302  of the board holder  30 . The pressure sensing components  5  are housed in the pressure sensing component holding portion  302  as illustrated in  FIG.  4    and are provided as illustrated in  FIG.  1 B  to provide a pen pressure detection module. Furthermore, the core body  21  is coupled to the pen pressure detection module through the core body holder  23 , and the pen pressure applied to the tip portion  21   a  of the core body  21  is detected by the pressure sensing components  5  of the pen pressure detection module. In this case, part of the pressure sensing components  5  included in the pen pressure detection module moves in the axial direction along with the core body  21  and the core body holder  23  according to the pen pressure applied to the tip portion  21   a  of the core body  21 , and the pen pressure detection module detects the pen pressure. 
     A variable capacitor is used in the case of the pen pressure detector of the example, in which the capacitance changes according to the pen pressure applied to the core body  21 . 
     The pressure sensing components  5  of the example include a plurality of components including a dielectric  51 , a terminal member  52 , the holding member  53 , a conductive member  54 , and an elastic member  55  as illustrated in  FIG.  4   . The terminal member  52  is made of a conductive material, such as SUS, and provides the first electrode of the variable capacitor including the pressure sensing components  5 . In addition, the conductive member  54  is made of, for example, conductive rubber, and the elastic member includes a coil spring made of a conductive material, such as SUS. The conductive member  54  and the elastic member  55  are electrically connected to provide the second electrode of the variable capacitor. 
     The pressure sensing component holding portion  302  of the board holder  30  includes a cylindrical body including a hollow portion as illustrated in  FIG.  4   , and the pressure sensing components  5  are lined up and housed in the axial direction in the hollow portion. 
     Among the pressure sensing components  5  including the plurality of components, the dielectric  51  and the terminal member  52  that are components not moved in the axial direction in the pressure sensing component holding portion  302  including the cylindrical body are inserted from a direction perpendicular to the board surface of the printed circuit board  31  orthogonal to the axial direction of the pressure sensing component holding portion  302  through an opening portion  303  including an opening in a direction orthogonal to the axial direction formed on part of the side peripheral surface of the cylindrical body of the pressure sensing component holding portion  302  as illustrated in  FIG.  4   , and the dielectric  51  and the terminal member  52  are housed as illustrated in  FIG.  1 B . 
     A wall portion  304  is provided at a boundary of the pressure sensing component holding portion  302  and the board mounting table portion  301  of the board holder  30 , and the terminal member  52  is pressed against the wall portion  304 . 
     The dielectric  51  includes a plate-like body with a predetermined thickness, and the dielectric  51  in contact with the terminal member  52  is housed in the pressure sensing component holding portion  302 . Therefore, the dielectric  51  does not move toward the terminal member  52  in the axial direction in the pressure sensing component holding portion  302 . 
     The terminal member  52  that plays a role of the first electrode of the variable capacitor includes a lead portion  52   c . When the lead portion  52   c  is housed in the pressure sensing component holding portion  302 , the lead portion  52   c  is soldered and connected to a land portion (not illustrated) on the board surface of the printed circuit board  31  mounted on the board mounting table portion  301  across the wall portion  304 . 
     Note that the terminal member  52  includes an L-shaped projection  52   d  for holding a side surface portion on the opening portion  303  side of the dielectric  51  when the dielectric  51  and the terminal member  52  are housed in the pressure sensing component holding portion  302 . 
     The holding member  53  is made of a non-conductive material, a resin as an insulating material in the example. As illustrated in  FIG.  4   , the holding member  53  includes a columnar shape portion  53   a  provided with a recess hole  53   b  in which the rod-like portion  232  of the core body holder  23  is pressed and fitted, on a side that is the core body  21  side in the axial direction of the holding member  53 , and a ring-shaped projection portion  53   c  provided with a recess hole  53   d  for fitting the conductive member  54 , on the opposite side of the recess hole  53   b  side in the axial direction. 
     The columnar shape portion  53   a  of the holding member  53  is provided with a slit  53   e  in the axial direction of the recess hole  53   b  with the intention to assist the ease of pressing and fitting the rod-like portion  232  of the core body holder  23  into the recess hole  53   b . The columnar shape portion  53   a  of the holding member  53  includes the slit  53   e , thereby providing a grip portion corresponding to the rod-like portion  232  of the core body holder  23 , and the holding member  53  surely grips and holds the core body holder  23 . That is, the columnar shape portion  53   a  of the holding member  53  provides a core body holder holding portion. 
     In addition, the ring-shaped projection portion  53   c  of the holding member  53  also includes a slit  53   f  communicating across the recess hole  53   d . The conductive member  54  is surely gripped by the ring-shaped projection portion  53   c  and held by the holding member  53  due to the existence of the slit  53   f.    
     In addition, opening portions  53   g  and  53   h  communicating with the recess hole  53   b  are formed on a side surface portion of the columnar shape portion  53   a  of the holding member  53 , the opening portions  53   g  and  53   h  facing each other across a cylinder central axis position. In addition, engagement projection portions  53   i  and  53   j  are formed on a peripheral surface of the columnar shape portion  53   a  of the holding member  53 . 
     On the other hand, stage portions  232   b  and  232   c  engaged with the opening portions  53   g  and  53   h  of the holding member  53  are formed near a tip portion  232   a  of the rod-like portion  232  of the core body holder  23  as illustrated in  FIG.  3 A . When the rod-like portion  232  of the core body holder  23  is pressed and fitted to the recess hole  53   b  of the holding member  53  as illustrated in  FIG.  1 B , the stage portions  232   b  and  232   c  are abutted against wall portions of the opening portions  53   g  and  53   h  and engaged to prevent the rod-like portion  232  from falling out to the core body  21  side. 
     The conductive member  54  includes a conductive elastic member that can be elastically deformed and is made of, for example, silicone conductive rubber or pressure conductive rubber. The conductive member  54  includes a projection portion  54   a  fitted to the recess hole  53   d  of the ring-shaped projection portion  53   c  of the holding member  53 . 
     In addition, the elastic member  55  includes, for example, a conductive coil spring. The elastic member  55  includes an elastic winding portion  55   a , a terminal piece  55   b  at one end portion of the winding portion  55   a , and a connection portion  55   c  at another end portion of the winding portion  55   a.    
     The ring-shaped projection portion  53   c  of the holding member  53  is housed in the winding portion  55   a  of the elastic member  55 , and the elastic member  55  is assembled in the axial direction of the holding member  53 . Furthermore, the projection portion  54   a  of the conductive member  54  is fitted to the recess hole  53   d  of the ring-shaped projection portion  53   c  of the holding member  53 . In this case, the connection portion  55   c  of the elastic member  55  is inserted into a bottom portion of the recess hole  53   d  formed on the ring-shaped projection portion  53   c  from a slit portion of the ring-shaped projection portion  53   c  of the holding member  53 . Therefore, when a small diameter portion  54   b  of the conductive member  54  is pressed and fitted to the ring-shaped projection portion  53   c  of the holding member  53 , an end surface of the small diameter portion  54   b  of the conductive member  54  is brought into contact with and electrically connected to the connection portion  55   c  of the conductive elastic member  55 . 
     Furthermore, when the terminal piece  55   b  of the elastic member  55  is inserted into the pressure sensing component holding portion  302 , the terminal piece  55   b  is soldered and connected to the conductive pattern on the board surface of the printed circuit board  31  mounted on the board mounting table portion  301  across the dielectric  51 , the terminal member  52 , and the wall portion  304 . 
     Furthermore, the combination of the conductive member  54  with the holding member  53  in the axial direction through the elastic member  55  is inserted into the pressure sensing component holding portion  302  from the opening portion  302   a  side. Furthermore, the engagement projection portions  53   i  and  53   j  formed on the side peripheral surface of the columnar shape portion  53   a  of the holding member  53  are engaged with an engagement stage portion (see  FIG.  1 B ) formed on the side peripheral surface of the pressure sensing component holding portion  302  to prevent the holding member  53  from falling out to the core body  21  side from the pressure sensing component holding portion  302 . However, when the pen pressure is applied from the core body  21  side, the holding member  53  can move in the hollow portion of the pressure sensing component holding portion  302 , toward the opposite side of the core body  21  in the axial direction. Furthermore, when the pen pressure is not applied from the core body  21  side any more due to the elastic biasing force of the elastic member  55 , the engagement projection portions  53   i  and  53   j  return to the state of being engaged with the engagement stage portion of the pressure sensing component holding portion  302 . 
     After the pressure sensing components  5  are housed in the cylindrical body of the pressure sensing component holding portion  302  in this way, the conductor terminal member  25  illustrated in  FIG.  3 B  is elastically installed on the end surface of the pressure sensing component holding portion  302  on the opening  302   a  side as described above. Subsequently, as described above, the rod-like portion  232  of the core body holder  23  provided with the conductive elastic member  22  is inserted into the pressure sensing component holding portion  302  through the through hole  251   a  of the abutment plate portion  251  of the conductor terminal member  25  and is fitted to the holding member  53 . In this way, the core body holder  23  is held with respect to the pressure sensing component holding portion  302  of the board holder  30 . 
     Furthermore, while the core body holder  23  is fitted to the pressure sensing component holding portion  302  of the board holder  30  in this way, the core body  21  is pressed into the through hole  22   a  of the conductive elastic member  22  fitted to the core body holder  23 . As a result, the core body  21  is firmly held by the conductive elastic member  22  with respect to the core body holder  23  as described above. 
     In this case, all of the core body  21 , the conductive elastic member  22 , and the core body holder  23  are conductive, and therefore, the core body  21  and the signal transmission circuit of the printed circuit board  31  are electrically connected through the conductive coil spring  24  and conductor terminal member  25  (see dotted line in  FIG.  1 B ). Therefore, the signal from the signal transmission circuit of the printed circuit board  31  is transmitted from the core body  21 . 
     Note that the core body  21  fitted and held by the core body holder  23  can be pulled out in the direction of the tip portion  21   a . Therefore, the core body  21  can be replaced as described above. 
     When the pressure is applied to the tip portion  21   a  of the core body  21  in the electronic pen  1 , the core body  21  is displaced toward the back end in the axial direction according to the pressure. Due to the displacement of the core body  21 , the holding member  53  in the pressure sensing component holding portion  302  is displaced toward the dielectric  51  against the elastic biasing force of the elastic member  55 . As a result, the conductive member  54  fitted to the holding member  53  is displaced toward the dielectric  51 , and the distance between the conductive member  54  and the dielectric  51  and the contact area of the conductive member  54  and the dielectric  51  change according to the pressure applied to the core body  21 . 
     In this way, the capacitance of the variable capacitor formed between the terminal member  52  included in the first electrode and the conductive member  54  included in the second electrode changes according to the pressure applied to the core body  21 . The change in the capacitance of the variable capacitor is detected by the IC  41  provided on the printed circuit board  31 , and the pen pressure is detected. 
     Next, the electrical connection of the first housing portion  11  included in the peripheral electrode and the circuit unit of the printed circuit board  31  will be described. 
     Here,  FIG.  2    illustrates the first housing portion  11  and the second housing portion  12  when the board holder  30  is viewed from the opposite side of the board mounting table portion  301  and further illustrates the cylindrical coupling member  13 . As illustrated in  FIG.  2   , a recess groove  13   c  is formed on the peripheral surface of the cylindrical coupling member  13  in the direction along the axial direction of the cylindrical coupling member  13 , from the first fitting cylindrical portion  13   a , below the lower part of the ring-shaped flange portion  13 F, and across a second fitting cylindrical portion  13   b . In this case, the recess groove  13   c  is formed throughout the entire axial direction in the second fitting cylindrical portion  13   b.    
     Furthermore, a recess groove  3023  continuous with the recess groove  13   c  of the second fitting cylindrical portion  13   b  when coupled is also formed on the peripheral surface of the pressure sensing component holding portion  302  of the board holder  30  coupled to the second fitting cylindrical portion  13   b  of the cylindrical coupling member  13 . The recess groove  3023  is extended to the position of the board mounting table portion  301  and formed throughout the entire peripheral surface of the pressure sensing component holding portion  302  in the axial direction. Furthermore, a cut-out portion  3011  is formed on the board mounting table portion  301  of the board holder  30  as illustrated in  FIG.  2   , such that a back surface  31   b  side of the placed printed circuit board  31  is visible from the cut-out portion  3011  side. 
     Furthermore, as illustrated in  FIG.  2   , a connection terminal conductor  16  made of a conductor material, conductor metal in the example, is arranged in the recess groove  13   c  and the recess groove  3023 . In this case, as also illustrated in  FIG.  1 B , at least part of an end portion  16   a  of the connection terminal conductor  16  arranged in the recess groove  13   c  on the first fitting cylindrical portion  13   a  side of the cylindrical coupling member  13  is arranged to protrude a little more than the peripheral surface of the first fitting cylindrical portion  13   a . However, the depth of the recess groove  13   c  of the part of the end portion  16   a  is set to a depth that allows to elastically press the end portion  16   a  downward when the end portion  16   a  is pressed from above. 
     In this way, when the first housing portion  11  is fitted to the first fitting cylindrical portion  13   a  of the cylindrical coupling member  13 , the end portion  16   a  of the connection terminal conductor  16  and the inner wall of the first housing portion  11  are surely brought into contact with each other, and the first housing portion  11  and the connection terminal conductor  16  are electrically connected. 
     On the other hand, the depth of the part of the recess groove  13   c  provided on the second fitting cylindrical portion  13   b  side of the cylindrical coupling member  13  is deep, and the upper surface of the connection terminal conductor  16  arranged in the recess groove  13   c  is at a position lower than the peripheral surface position of the second fitting cylindrical portion  13   b.    
     The depth of the recess groove  3023  provided on the pressure sensing component holding portion  302  of the board holder  30  is also similarly deep, and the upper surface of the connection terminal conductor  16  arranged in the recess groove  3023  is at a position lower than the peripheral surface position of the pressure sensing component holding portion  302 . 
     In this way, when the second housing portion  12  housing the board holder  30  inside is fitted to the second fitting cylindrical portion  13   b  of the cylindrical coupling member  13 , there is an air layer or gap between the upper surface of the connection terminal conductor  16  in the recess groove  13   c  and the recess groove  3023  and the inner wall surface of the second housing portion  12 , and electrical separation (insulation) of the upper surface and the inner wall surface is realized. 
     Furthermore, the end portion  16   b  extending toward the printed circuit board  31  of the connection terminal conductor  16  is bent at the location of the cut-out portion  3011  of the board holder  30  and electrically connected to the back surface  31   b  side of the printed circuit board  31 . Although not illustrated, the end portion  16   b  of the connection terminal conductor  16  is electrically connected to the circuit unit on the front side of the printed circuit board  31  through a through hole. 
     Note that instead of adjusting the depth of the recess groove  13   c  and the recess groove  3023 , the thickness of the connection terminal conductor  16  may be changed. In this way, the end portion  16   a  may protrude slightly more than the peripheral surface of the first fitting cylindrical portion  13   a , and there may be a space between the connection terminal conductor  16  and the second housing portion  12  in the second fitting cylindrical portion  13   b  and the pressure sensing component holding portion  302  of the board holder  30  to realize the insulation of the connection terminal conductor  16  and the second housing portion  12 . Note that the upper surface of the connection terminal conductor  16  of the recess groove  13   c  may be covered by an insulating layer in the second fitting cylindrical portion  13   b  and the pressure sensing component holding portion  302  of the board holder  30  to more surely realize the insulation of the connection terminal conductor  16  and the second housing portion  12 . 
     The assembly of the electronic pen  1  of the embodiment configured in this way will be described. First, the printed circuit board  31  provided with the circuit components in advance is mounted and fitted on the board mounting table portion  301  of the board holder  30 . Next, the pressure sensing components  5  included in the pen pressure detector are housed in the pressure sensing component holding portion  302  of the board holder  30 . 
     Next, as described above, the conductor terminal member  25  is attached to the pressure sensing component holding portion  302  of the board holder  30  such that the abutment plate portion  251  blocks the opening portion  302   a  side of the pressure sensing component holding portion  302  of the board holder  30 . Furthermore, the terminal portion  254   a  at the front end of the extension portion  254  of the conductor terminal member  25  is soldered to the back surface  31   b  of the printed circuit board  31  and electrically connected to the circuit unit on a front surface  31   a  side of the printed circuit board  31  through the through hole. 
     Next, the core body holder  23  provided with the coil spring  24  at the part of the rod-like portion  232  is inserted into the pressure sensing component holding portion  302  from the opening portion  302   a , with the coil spring  24  held between the core body holder  23  and the abutment plate portion  251  of the conductor terminal member  25 , so that the core body holder  23  is held by the holding member  53 . 
     Next, the core body holder  23  is housed in the hollow portion of the cylindrical coupling member  13 , and the second fitting cylindrical portion  13   b  of the cylindrical coupling member  13  and the pressure sensing component holding portion  302  of the board holder  30  are coupled. Furthermore, the connection terminal conductor  16  is arranged in the recess groove  13   c  of the cylindrical coupling member  13  and the recess groove  3023  of the pressure sensing component holding portion  302  in the state as described above, and the end portion  16   b  of the connection terminal conductor  16  closer to the board mounting table portion  301  of the board holder  30  is soldered to the back surface  31   b  of the printed circuit board  31  and electrically connected to the circuit unit on the front surface  31   a  side of the printed circuit board  31  through the through hole. 
     Next, the cylindrical shape portion  11   a  of the first housing portion  11  provided with the front cap  14  at the opening  11   c  is fitted to the first fitting cylindrical portion  13   a  side of the cylindrical coupling member  13 . In this case, the cylindrical shape portion  11   a  of the first housing portion  11  is pushed up to the location of the ring-shaped flange portion  13 F and fitted to the first fitting cylindrical portion  13   a  of the cylindrical coupling member  13 . As a result, the first housing portion  11  is pressed against and electrically connected to the end portion  16   a  of the connection terminal conductor  16  as illustrated in  FIG.  1 B . That is, the first housing portion  11  is fitted to the first fitting cylindrical portion  13   a  of the cylindrical coupling member  13  so that the first housing portion  11  is electrically connected to the circuit unit of the printed circuit board  31  through the connection terminal conductor  16 . 
     Next, the second housing portion  12  is fitted to the second fitting cylindrical portion  13   b  of the cylindrical coupling member  13 , with the board holder  30  housed in the hollow portion of the second housing portion  12 . In this case, the second housing portion  12  is also pushed up to the location of the ring-shaped flange portion  13 F and fitted to the second fitting cylindrical portion  13   b  of the cylindrical coupling member  13 . Note that although not illustrated here, the second housing portion  12  housing the board holder  30  and fitted to the second fitting cylindrical portion  13   b  of the cylindrical coupling member  13  is electrically connected to the earth conductor of the printed circuit board  31 . 
     Subsequently, the battery  32  is inserted and fixed in the hollow portion of the second housing portion  12 , on the back end side of the board mounting table portion  301  of the board holder  30  in the axial direction. Furthermore, the opening of the second housing portion  12  on the back end side is blocked by the back cap  15 . 
     Lastly, the core body  21  is inserted through the opening  10   a  of the front cap  14  installed on the first housing portion  11  and is fitted to and held by the conductive elastic member  22  held by the core body holder  23 . This completes the electronic pen  1 . 
     In this case, the length of the first housing portion  11  in the axial direction, the length of the front cap  14  in the axial direction, and the length of the core body  21  are selected so that a length L 1  (see  FIG.  1 A ) from the tip portion  21   a  of the core body  21  to the side of the ring-shaped flange portion  13 F of the cylindrical coupling member  13  coupled to the first housing portion  11  is a length that prevents fingers from coming into contact when the user uses a hand to grip and use the electronic pen  1 . The length of the tip portion  21   a  protruding outside from the opening of the front cap  14  mainly affects the length L 1 , and this is taken into account to select the length of the core body  21 . Meanwhile, the length L 1  can be set to 10 to 15 mm to provide the length that prevents the fingers of the user from coming into contact. 
       FIG.  5    illustrates an electrical configuration example of the electronic pen  1  of the embodiment. As illustrated in  FIG.  5   , the control circuit  41  includes an IC  40  mounted on the printed circuit board  31 . Furthermore, a signal transmission circuit  42  and a reception circuit  43  are connected to the control circuit  41 , and a variable capacitor  5 C including the pressure sensing components  5  of the pen pressure detector is connected to the control circuit  41 . A resistance  5 R is connected in parallel to the variable capacitor  5 C. 
     Furthermore, a signal output end of the signal transmission circuit  42  is connected to the core body  21  through the conductor terminal member  25 , the core body holder  23 , and the conductive elastic member  22 . In addition, the first housing portion  11  (peripheral electrode) arranged to cover around the core body  21  is connected to an input end of the reception circuit  43  through the connection terminal conductor  16 . 
     Furthermore, the power supply voltage from the battery  32  is supplied to each of the IC  41 , the signal transmission circuit  42 , and the reception circuit  43 . 
     The reception circuit  43  receives a signal received by the peripheral electrode including the first housing portion  11  through capacitive coupling (electric field coupling) with the position detection sensor of the position detection apparatus. The reception circuit  43  performs a process, such as demodulation, according to the received signal and transmits a signal of the processing result to the control circuit  41 . 
     The control circuit  41  analyzes the signal from the reception circuit  43  to determine the specifications of the position detection apparatus of the partner. Furthermore, the control circuit  41  controls the format of the signal to be output from the signal transmission circuit  42  based on the determination result so that the format matches the specifications of the position detection apparatus of the partner. 
     The signal transmission circuit  42  basically outputs, under the control of the control circuit  41 , a signal including a position detection signal (burst signal) for the position detection in the position detection apparatus and including pen pressure information detected by the pressure sensing components  5  of the pen pressure detector. That is, the signal transmission circuit  42  transmits a burst signal for the position detection under the control of the control circuit  41 . Furthermore, in a period in which the burst signal is transmitted from the signal transmission circuit  42 , the control circuit  41  an operation of detecting the pen pressure based on the capacitance of the variable capacitor  5 C including the pressure sensing components  5  of the pen pressure detector. For example, the control circuit  41  includes a processor and a memory storing instructions that, when executed by the processor, cause the control circuit  41  to perform the operation of detecting the pen pressure. 
     In the example, the control circuit  41  first charges the variable capacitor  5 C to a fully charged state and then stops charging to discharge the variable capacitor  5 C through the resistance  5 R. Furthermore, the control circuit  41  measures the time period from the start of the discharge to the time that the voltage at both ends of the variable capacitor  5 C becomes a predetermined voltage set in advance and detects the capacitance of the variable capacitor  5 C at that time based on the time period. The capacitance of the variable capacitor  5 C corresponds to the pen pressure applied to the core body  21  at that time, and the pen pressure is detected based on the detected capacitance. 
     Furthermore, the control circuit  41  controls the signal transmission circuit  42  to transmit, from the core body  21 , pen pressure information including, for example, an encoded signal corresponding to the detected pen pressure after the end of the transmission period of the burst signal. The control circuit  41  further controls generation of a signal according to the determined specifications of the position detection apparatus of the partner, such as transmission of identification information of the electronic pen  1  and transmission of information of the remaining capacity of the battery  32 . 
     Note that the circuit configurations of the position detection apparatus and the position detection sensor can be well-known circuit configurations, and configuration examples of the circuit configurations will not be described here. 
     Advantageous Effects of Embodiment 
     As described above, the housing  10  is separated into the first housing portion  11  and the second housing portion  12  in the electronic pen  1  of the embodiment, and the first housing portion  11  and the second housing portion  12  are fitted to one side and the other side of the cylindrical coupling member  13  in the axial direction, respectively, to form the housing  10 . Furthermore, the cylindrical coupling member  13  is coupled to the pressure sensing component holding portion  302  of the board holder  30  in the embodiment. The pressure sensing components  5  of the components included in the pen pressure detector (the pressure sensing components  5  and the core body holder  23  as a pressure transmission member) are housed in the pressure sensing component holding portion  302  of the board holder  30 , and the core body holder  23  as a pressure transmission member is housed in the cylindrical coupling member  13 . 
     Therefore, compared to the configuration of the pen pressure detector in the conventional electronic pen  100  illustrated in  FIGS.  6 A and  6 B , the cylindrical coupling member  13  is used as a housing that houses the core body holder  23  included in the pressure transmission member in the electronic pen  1  of the embodiment. Therefore, the housing  114  in the electronic pen  100  housed in the pressure sensing component holding portion  302  of the board holder  30  is unnecessary, and this reduces the thickness. 
     Furthermore, in the conventional electronic pen  100  illustrated in  FIGS.  6 A and  6 B , the front cap  102  as an insulating material is placed between the housing  101  and the peripheral electrode  116  in the direction orthogonal to the axial direction of the electronic pen  100 . On the other hand, in the electronic pen  100  of the embodiment, the ring-shaped flange portion  13 F of the cylindrical coupling member  13  is placed in the axial direction to realize the electrical separation (insulation) of the first housing portion  11  included in the peripheral electrode and the second housing portion  12 . The first housing portion  11  and the second housing portion  12  can be lined up in the axial direction, and the thickness can be reduced. 
     Furthermore, the electrical separation (insulation) of the first housing portion  11  as a peripheral electrode and the core body  21  is realized by only providing the front cap  14  in a simple cylindrical shape on the opening  11   c  side of the first housing portion  11 . This is advantageous in that the front cap  102  with a special shape in the conventional electronic pen  100  illustrated in  FIGS.  6 A and  6 B  is unnecessary. 
     Other Embodiments or Modifications 
     In the embodiment as described above, the first fitting cylindrical portion  13   a  of the cylindrical coupling member  13  and the first housing portion  11  are pressed, fitted, and coupled, and the second fitting cylindrical portion  13   b  of the cylindrical coupling member  13  and the second housing portion  12  are pressed, fitted, and coupled to thereby provide the housing  10 . However, the components may be screwed with each other, instead of the pressing and fitting. In addition, a ring-shaped projection portion may be provided on one of the first fitting cylindrical portion  13   a  of the cylindrical coupling member  13  and the first housing portion  11  or on one of the second fitting cylindrical portion  13   b  of the cylindrical coupling member  13  and the second housing portion  12 , and a corresponding ring-shaped recess portion may be provided on the other. In this way, the ring-shaped projection portion and the ring-shaped recess portion can be used to engage and fit the components with a click sound. 
     In addition, the first fitting cylindrical portion  13   a  of the cylindrical coupling member  13  and the first housing portion  11  may be fitted by screwing, and the second fitting cylindrical portion  13   b  of the cylindrical coupling member  13  and the second housing portion  12  may be fitted by pressing or by engagement with a click sound. Conversely, the second fitting cylindrical portion  13   b  of the cylindrical coupling member  13  and the second housing portion  12  may be fitted by screwing, and the first fitting cylindrical portion  13   a  of the cylindrical coupling member  13  and the first housing portion  11  may be fitted by pressing or by engagement with a click sound. 
     Furthermore, in the embodiment as described above, the outer diameter of the end surface of the ring-shaped flange portion  13 F of the cylindrical coupling member  13 , the outer diameter of the first housing portion  11 , and the outer diameter of the second housing portion  12  are all the same, and the housing  10  has a shape without recess and projection areas in the axial direction. However, the outer diameter of the end surface of the ring-shaped flange portion  13 F of the cylindrical coupling member  13 , the outer diameter of the first housing portion  11 , and the outer diameter of the second housing portion  12  may not be all the same. For example, the outer diameter of the first housing portion  11  and the outer diameter of the second housing portion  12  may be the same, and the outer diameter of the ring-shaped flange portion  13 F may be larger or smaller than that. In this case, the outer diameter of the ring-shaped flange portion  13 F is large, and the part is a projection portion in the housing  10 . The part serves as a handhold for preventing the fingers from coming into contact with the first housing portion  11  side when the user grips the electronic pen to use the electronic pen, and this is convenient. 
     In addition, the outer diameter of the first housing portion  11  and the outer diameter of the second housing portion  12  may be different from each other, and the outer diameter of the ring-shaped flange portion  13 F may be equal to one of the first housing portion  11  and the second housing portion  12 . In this case, the difference in level generated on the peripheral surface of the housing  10  also serves as a handhold for preventing the fingers from coming into contact with the first housing portion  11  side when the user grips the electronic pen to use the electric pen, and this is convenient. 
     In the embodiment, the cylindrical coupling member  13  and the pressure sensing component holding portion  302  of the board holder  30  are partially fitted and coupled. However, the end portion of the second fitting cylindrical portion  13   b  of the cylindrical coupling member  13  in the axial direction and the end portion of the pressure sensing component holding portion  302  of the board holder  30  in the axial direction may be simply abutted against each other. 
     In addition, the holding portion of the pressure sensing components  5  of the pen pressure detector may be integrated with the second fitting cylindrical portion  13   b  side of the cylindrical coupling member  13 , instead of integrating the holding portion with the board holder  30 . 
     In addition, the cylindrical coupling member  13  and the board holder  30  may be integrated. In this case, the outer diameter of the part of the board holder  30  can be smaller than the outer diameter of the second fitting cylindrical portion  13   b  of the cylindrical coupling member  13  to facilitate the housing in the second housing portion  12 . 
     Note that, although not only the first housing portion  11 , but also the second housing portion  12  is made of a conductive material in the embodiment as described above, the second housing portion  12  may not be made of a conductive material, and the second housing portion  12  may be made of an insulating material, such as a resin. 
     Note that, although the first housing portion  11  included in the peripheral electrode is dedicated to the signal reception in the electronic pen described in the embodiment as described above, the first housing portion  11  may transmit a signal in the electronic pen. 
     For example, when the electronic pen is in the air (generally-called hover state) without coming into contact with the input surface of the position detection sensor, the signal can be transmitted from not only the core body  21 , but also from the first housing portion  11  as a peripheral electrode, or the signal may be transmitted from the first housing portion  11  instead of the signal transmission from the core body  21 . In this way, the position detection sensor can easily detect an approximate position of the electronic pen in the hover state. 
     Furthermore, as in the electronic pen of Patent Document 2 as described above, the signal can be transmitted from the first housing portion  11  as a peripheral electrode to allow the position detection apparatus to detect the tilt of the electronic pen. 
     Note that, although the core body  21  only transmits a signal to the position detection sensor in the electronic pen  1  of the embodiment as described above, the core body  21  can transmit a signal to the position detection sensor and receive a signal from the position detection sensor in time division in the electronic pen. 
     In addition, although the signals are transmitted and received only between the core body  21  and the position detection sensor of the position detection apparatus or between the first housing portion  11  and the position detection sensor of the position detection apparatus in the electronic pen of the embodiment as described above, the electronic pen may use wireless communication means of, for example, a Bluetooth (registered trademark) standard to transmit and receive signals to and from the position detection apparatus through wireless communication. 
     Note that, although the dielectric  51  is placed between the terminal member  52  and the conductive member  54  in the pressure sensing components of the pen pressure detector to provide the variable capacitor in the embodiment as described above, a semiconductor element as a variable capacitor including an MEMS (Micro Elector Mechanical Systems) element may also be used, in which the capacitance is variable according to the pen pressure, as disclosed in, for example, Japanese Patent Laid-Open No. 2013-161307. 
     In addition, although the first housing portion  11  includes one conductive member in the embodiment as described above, the first housing portion  11  may be divided in the circumferential direction to provide a plurality of conductive members, such as two or three conductive members. Signals may be independently supplied to the plurality of conductive members to transmit the signals to the position detection sensor. In this case, the position detection apparatus can also detect the angle of rotation of the electronic pen. 
     DESCRIPTION OF REFERENCE SYMBOLS 
       1  . . . Electronic pen,  10  . . . Housing,  11  . . . First housing portion,  12  . . . Second housing portion,  13  . . . Cylindrical coupling member,  13   a  . . . First fitting cylindrical portion,  13   b  . . . Second fitting cylindrical portion,  13 F . . . Ring-shaped flange portion,  14  . . . Front cap,  15  . . . Back cap,  16  . . . Connection terminal conductor,  21  . . . Core body,  22  . . . Conductive elastic member,  23  . . . Core body holder,  24  . . . Coil spring,  25  . . . Conductor terminal member,  30  . . . Board holder,  301  . . . Board mounting table portion,  302  . . . Pressure sensing component holding portion,  31  . . . Printed board,  32  . . . Battery,  41  . . . Control circuit,  42  . . . Signal transmission circuit,  43  . . . Reception circuit.