Patent Publication Number: US-2023161426-A1

Title: Electronic pen cartridge

Description:
BACKGROUND 
     Technical Field 
     The present disclosure relates to an electronic pen cartridge for constituting an electronic pen that inputs information by indicating coordinates to various electronic devices equipped with a position detection sensor, for example, such as a tablet personal computer (PC). 
     Description of the Related Art 
     With the appearance of various electronic devices equipped with position detection sensors, electronic pens have also become widely used. However, there are demands for use of a refill equipped with an electronic pen function, which is placed in the housing of an accustomed writing tool such as a ballpoint pen, instead of using an electronic pen dedicated to an electronic device equipped with a position detection sensor. Therefore, an electronic pen used by placing a cartridge-type refill equipped with an electronic pen function (hereinafter referred to as an electronic pen cartridge) in the housing of an existing writing tool is considered. 
     Electronic devices equipped with position detection sensors are often carried to various places for use, and may be used in outdoor areas in wet weather or near water such as on coasts or rivers. For this reason, some electronic devices equipped with a position detection sensor are waterproof. In response to this, waterproof measures are being considered for electronic pens as well. For example, in PCT Patent Publication No. WO 2017/149879, which will be described later, disclosed is one in which constituent members and a circuit board for executing electronic pen functions are housed in a hollow portion of a cylindrical inner housing (cartridge case), and waterproof measures and the like are taken by filling the inside of the hollow portion of the inner housing with resin. 
     In the electronic pen disclosed in PCT Patent Publication No. WO 2017/149879, the core body can be mounted in the inner housing so that the pen tip protrudes from the inner housing. Further, the pen pressure detector is provided at the rear end of the inner housing, and the inner housing itself slides and moves to the rear side in the axial direction according to the pen pressure applied to the core body, and then can detect the writing pressure by being pressed by a protrusion of the housing lid provided at the rear end. In a case of the disclosure disclosed in PCT Patent Publication No. WO 2017/149879, since the constituent parts and the circuit board for fulfilling the electronic pen functions can be covered with resin, an electronic pen with sufficient waterproof measures can be achieved. 
     The electronic pen of the disclosure disclosed in PCT Patent Publication No. WO 2017/149879 described above has a configuration in which a pen pressure detector is provided at the rear end of the inner housing. Therefore, the inner housing moves while sliding in the outer housing to the rear side in the axial direction according to the writing pressure applied to the core body, so that the protrusion of the housing lid provided at the rear end of the outer housing presses the pen pressure detector of the inner housing. In this way, when the pen pressure detector is provided at the rear end of the inner housing, there is a concern that the pen pressure applied to the core body may be scattered on the way because the pen pressure detector is not directly pressed by the core body, and the responsiveness of pen pressure detection will be slightly reduced. If possible, the pen pressure detector is desirably placed on the pen tip side so that the pen pressure detector can be pressed directly by the core body. 
     Further, considering a case of an electromagnetic induction type electronic pen cartridge, for example, electronic components such as a pen pressure detector and a circuit board are housed in an inner housing, but a coil for forming a resonance circuit is often provided in a part in front of the inner housing. As described above, in a case where the coil is provided outside the inner housing, it is necessary to take waterproof measures for the coil portion. It is considered that, if the coil part gets wet, there are cases where the characteristics of the coil change, which may affect the resonance frequency of the resonance circuit including the coil, and affect detection of the indicated position and pen pressure on the position detection sensor side. In addition, it is desirable to manufacture electronic pen cartridges with as little labor as possible. 
     BRIEF SUMMARY 
     In view of the above, an object of the present disclosure is to provide an electronic pen cartridge for which waterproof measures are appropriately provided and whose manufacturing process is not complicated. 
     To solve the above-mentioned problem, provided is an electronic pen cartridge that is replaceable and constitutes an electronic pen by being attached to a cylindrical outer housing having a hollow portion inside, the electronic pen cartridge including an inner housing that is cylindrical, a circuit board housed in the inner housing, a pen pressure detector provided in the inner housing on a side of the inner housing adjacent to a pen tip, a core body that is rod-shaped and presses the pen pressure detector, and a coil provided at a position closer to the pen tip than the inner housing and having a first end and a second end connected to the circuit board, in which at least the coil is covered with a resin sealing portion. 
     According to this electronic pen cartridge, an electronic pen can be configured by mounting the cartridge on an outer housing, and a circuit board and a pen pressure detector are provided in an inner housing, and a core body is provided so as to press the pen pressure detector inside the inner housing. A coil is provided at a position closer to the pen tip than the inner housing, but at least the coil is covered with a resin sealing portion so that waterproof measures are taken and the electrical characteristics can be prevented from changing. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIGS.  1 A and  1 B  are diagrams for illustrating an electronic pen cartridge of a first embodiment of the present disclosure; 
         FIGS.  2 A and  2 B  are diagrams for illustrating an electronic pen cartridge of a second embodiment of the present disclosure; 
         FIGS.  3 A and  3 B  are diagrams for illustrating another example of the electronic pen cartridge of the second embodiment of the present disclosure; 
         FIGS.  4 A,  4 B and  4 C  are diagrams for illustrating an electronic pen cartridge of a third embodiment of the present disclosure; 
         FIG.  5    is a diagram for illustrating another example of the electronic pen cartridge according to the third embodiment of the present disclosure; 
         FIGS.  6 A and  6 B  are diagrams for illustrating an electrical joint between the tip unit and the inner housing side of the electronic pen cartridge illustrated in  FIG.  5   ; and 
         FIG.  7    is a diagram illustrating an equivalent circuit of the electronic pen cartridge according to the embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of the electronic pen cartridge according to the present disclosure will be described with reference to the drawings. The position detection method of the electronic pen and the position detection sensor includes an electromagnetic induction method and a capacitance method, for example. In the electromagnetic induction method (electro magnetic resonance (EMR) method), the position detection device includes a sensor unit in which a plurality of loop coils are arranged in each of the X-axis direction and the Y-axis direction. A transmission period in which electric power is sequentially supplied to a plurality of loop coils of the sensor unit to generate a magnetic field and a reception period in which the supply of electric power is stopped and a magnetic field from the outside is received are alternately provided. The corresponding electronic pen is equipped with a resonance circuit having a coil and a capacitor, and generates a signal by a current flowing through the coil according to the magnetic field from the sensor unit, and then causes this signal to include the pen pressure information to send the signal to the position detection sensor. The position detection device receives the signal during the reception period, and detects the position indicated by the electronic pen and the pen pressure. 
     In the capacitance method, the position detection device includes a sensor unit in which a plurality of linear conductors (line electrodes) are arranged in each of the X-axis direction and the Y-axis direction. The sensor unit detects an indicated position according to a change in capacitance (charge) generated in the linear conductors when a finger or a capacitive pen is brought close to the sensor unit. The capacitive pen includes a pen-type position indicator having electric conductivity, or what is called an active capacitive pen (active electrostatic (AES) method) driven by a battery and transmitting signals. In a case of the active capacitive coupling method using an active capacitive pen, the electronic pen transmits signals from an oscillation circuit mounted on the electronic pen with the pen pressure information added to the signals, and the position detection device receives this and detects the indicated position and pen pressure. 
     The electronic pen cartridge of the present disclosure is suitable to be applied to an electromagnetic induction type electronic pen cartridge that includes a resonance circuit having a coil and a capacitor and may cause change of the characteristics of the resonance circuit when the coil gets wet. However, even in a case of an active capacitive coupling type electronic pen cartridge, the pen cartridge is similarly applicable when a coil for non-contact charging of the mounted battery is provided, for example. That is, the electronic pen cartridge of the present disclosure is applicable to one which is provided with a coil connected to a circuit board and for which appropriate waterproof measures need to be taken for the coil portion. In the embodiments described below, in order to simplify the explanation, a case of application to an electromagnetic induction type electronic pen cartridge will be described as an example. 
     The word “cartridge” means a component of a device that can be freely replaced. Hence, the electronic pen cartridge has an outer shape similar to that of a ballpoint pen refill, for example, and corresponds to a refill that fulfills an electronic pen function. Thus, by mounting the electronic pen cartridge of the present disclosure on an outer housing (a frame for housing a refill) such as a ballpoint pen, an electronic pen with an accustomed ballpoint pen housing can be achieved. Hereinafter, the electronic pen cartridge of the present disclosure will be specifically described. 
     First Embodiment 
       FIGS.  1 A and  1 B  are diagrams for illustrating a configuration example of an electronic pen cartridge  1  according to a first embodiment.  FIG.  1 A  is a cross-sectional view of the electronic pen cartridge  1  of the first embodiment cut in half in the longitudinal direction with the near side portion removed. Further,  FIG.  1 B  is an external view of the electronic pen cartridge  1  illustrated in  FIG.  1 A . As illustrated in  FIG.  1 A , the electronic pen cartridge  1  is roughly composed of two parts, a main body portion  1 Bd and a tip unit portion  1 Ut. 
     The main body portion  1 Bd is a portion configured by mounting various components in an inner housing  11 . The inner housing  11  is a cylindrical body having a hollow portion inside. The inner housing  11  has an opening on the pen tip side (left end side in  FIG.  1 A ), and the rear end side (right end side in  FIG.  1 A ) is closed to form a bottom face, and a rod-shaped connector  11   a  extended in a rod shape toward the rear end side is further formed in the outer central portion of the bottom face. The rod-shaped connector  11   a  is provided for being internally attached to an outer housing such as a ballpoint pen that is held by the user. 
     A tip cap  12  is provided at the opening portion on the pen tip side of the inner housing  11 , and a board holder  15  is provided behind the tip cap  12 . The board holder  15  is an elongated component provided with a tip cylindrical portion  15   a  on the pen tip side, and behind this, an intermediate bottom face portion  15   b  having a thickness so as to form the bottom face of the tip cylindrical portion  15   a , and further provided with a plate-shaped portion  15   c  extended from the rear end face of the intermediate bottom face portion  15   b  toward the rear end side. In addition, the board holder  15  includes a rear end bottom face portion  15   d  having a thick portion at the rear end of the plate-shaped portion  15   c , and the rear end face of the rear end bottom face portion  15   d  is in contact with the inner bottom face of the inner housing. The intermediate bottom face portion  15   b  and the rear end bottom face portion  15   d  are portions formed in a circular flat plate shape having a diameter slightly shorter than the inner diameter of the inner housing  11 . 
     The tip cap  12  is a cylindrical body having a shape in which two cylindrical portions having different diameters are connected to each other. The outer diameter of the cylindrical portion having a longer diameter of the tip cap  12  is the same as or slightly longer than the inner diameter of the inner housing  11 , and the cylindrical portion having the longer diameter of the tip cap  12  is fitted into the tip opening of the inner housing  11  to be fixed. Further, the outer diameter of the cylindrical portion having a shorter diameter of the tip cap  12  is the same as or slightly longer than the inner diameter of the tip cylindrical portion  15   a  of the board holder  15 , and the cylindrical portion having the shorter diameter of the tip cap  12  is fitted into the tip cylindrical portion  15   a  of the board holder  15  from the opening on the pen tip side. As a result, the board holder  15  is sandwiched between the tip cap  12  and the bottom face of the inner housing  11  and fixed in the hollow portion of the inner housing  11 . Further, as will be described later, the rear end side of a ferrite core  22  is fitted from the pen tip side into the cylindrical portion having a longer diameter of the tip cap  12 . 
     A cap-shaped pusher member  13  is provided behind the tip cap  12 . As will be described later, a rear end of a core body  21  is attached to the pusher member  13 , which functions to hold the core body  21  in the inner housing  11 . The core body  21  is composed of a pen tip  21   a  formed such that its tip is rounded, and a shaft  21   b  extended in a rod shape from the pen tip  21   a  to the rear end side. A pen pressure detector  14  is provided behind the pusher member  13  so as to be sandwiched between the pusher member  13  and the intermediate bottom face portion  15   b  of the tip cylindrical portion  15   a  of the board holder  15 . 
     The pen pressure detector  14  is configured as a micro electro mechanical systems (MEMS) sensor. The pen pressure detector  14  detects the pen pressure applied to the core body  21  as a change in capacitance, for example, by being pressed by the core body  21  and the pusher member  13 . A coil spring  13   a  is provided around a part of the outer side surface (outer wall surface) of the pen pressure detector  14 , and when the pen pressure applied to the core body  21  is released, the coil spring  13   a  pushes back the core body  21  to its original position by the restoration force. 
     In  FIG.  1 A , a circuit board  16  is placed and fixed on the upper surface of the board holder  15 . Various circuit components such as a capacitor  16   a  and a control integrated circuit (IC)  16   b  are mounted on the circuit board  16  as main components to form a circuit unit. As illustrated in  FIG.  1 A , an electrode  16   c  connected to the pen pressure detector  14  is provided on the pen tip side of the circuit board  16 , and the electrode  16   c  and the circuit unit formed on the circuit board  16  are electrically connected by a conductive portion  16   d.    
     Further, the circuit board  16  is provided with a fixing hole passing through the circuit board  16  in the thickness direction at a predetermined position on the pen tip side. As illustrated in  FIG.  1 A , when the circuit board  16  is placed in a fixed position on the board holder  15 , a fixing protrusion  15   e  provided on the board holder  15  is fitted in the fixing hole. Due to this, the position of the circuit board  16  on the board holder  15  is fixed. In this way, as illustrated in  FIG.  1 A , the tip cap  12 , the pusher member  13 , the pen pressure detector  14 , the board holder  15 , and the circuit board  16  are mounted in the inner housing  11  to configure the main body portion  1 Bd. 
     On the other hand, the tip unit portion  1 Ut is provided in front (pen tip side) of the main body portion  1 Bd. The tip unit portion  1 Ut includes the ferrite core  22  which has a cylindrical body having a through hole through which the core body  21  penetrates, and a coil  23  formed by winding a coated conductor wire around the side surface of the ferrite core  22 . In the first embodiment, as illustrated in  FIG.  1 A , a first non-winding portion  22   a  and a second non-winding portion  22   b  in which coated conductor wires are not wound and no coil is formed are provided on both ends of the ferrite core  22 , that is, certain definite ranges on the pen tip side and the rear end side. 
     Further, as illustrated in  FIG.  1 A , on the tip unit portion  1 Ut, a sealing portion  24  is formed in such a manner as to cover the coil  23 , a part of the first non-winding portion  22   a  on the coil  23  side, and a part of the second non-winding portion  22   b  on the coil  23  side. The sealing portion  24  gives a waterproof function to the coil  23  portion by covering the entire coil  23  with resin such as plastic, for example. To be specific, the coil  23  formed on the side surface of the ferrite core  22  is integrally wrapped by the sealing portion  24  formed of a resin material by what is called insert molding. 
     That is, insert molding is a molding method in which heat-melted resin such as plastic is injected into the space around a component inserted into a mold for the injection molding to integrate the inserted component and the injected resin. By integrating the components (a part of the ferrite core  22  and the coil  23 ) and the resin (sealing portion  24 ) in this way, the components can be shielded from the outside world by the resin and waterproof measures can be taken. The second non-winding portion  22   b  of the ferrite core  22  of the tip unit portion  1 Ut thus formed is fitted into the cylindrical portion having the longer diameter of the tip cap  12  of the main body portion  1 Bd for fixing. 
     The outer diameter of the ferrite core  22  is substantially the same as the inner diameter of the cylindrical portion having the longer diameter of the tip cap  12 . Therefore, in the first embodiment, the second non-winding portion  22   b  of the ferrite core  22  and the cylindrical portion having the longer diameter of the tip cap  12  are bonded to each other by an adhesive such as a two-part epoxy adhesive. As illustrated in  FIG.  1 A , conductive wires  23   a  and  23   b  extended from both ends of the coil  23  are led out to the circuit board  16  along the inner side surface of the inner housing  11  and are connected to the circuit unit formed on the circuit board  16 . 
     In this way, the tip unit portion  1 Ut is attached to the main body portion  1 Bd, and further, the rear end side of the shaft  21   b  of the core body  21  is inserted into and pushed in the tip opening of the ferrite core  22 . As a result, as illustrated in  FIG.  1 A , the rear end of the shaft  21   b  of the core body  21  is attached to the pusher member  13  of the main body portion  1 Bd to form the electronic pen cartridge  1 . As illustrated in  FIG.  1 B , the appearance of the electronic pen cartridge  1  has a configuration in which the main body portion  1 Bd and the tip unit portion  1 Ut are connected, and the pen tip  21   a  of the core body  21  protrudes from the first non-winding portion  22   a  side of the ferrite core  22  of the tip unit portion  1 Ut. The core body  21  is removable and can be replaced as needed. 
     In a case of the electronic pen cartridge  1  of the first embodiment, the entire coil  23  of the tip unit portion  1 Ut is shielded from the outside world by the sealing portion  24 , so that a waterproof function can be given. Consequently, when the electronic pen cartridge  1  is mounted in an outer housing such as a ballpoint pen housing, an electronic pen having a waterproof function can be achieved. The electronic pen cartridge  1  of the first embodiment has a diameter of 3.8 mm and a total length of 65.65 mm in the longitudinal direction, for example, and has almost the same size as a commercially available ballpoint pen refill. 
     In  FIGS.  1 A and  1 B , in order to clarify the configuration including the main body portion  1 Bd and the tip unit portion  1 Ut, a gap is provided between the main body portion  1 Bd and the sealing portion  24  when the main body portion  1 Bd and the tip unit portion  1 Ut are connected. However, the embodiment is not limited to this. By providing the sealing portion  24  up to the rear end side so as to cover the second non-winding portion  22   b  more, it is, needless to say, possible to have a configuration such that the rear end face of the sealing portion  24  and the front end face of the main body portion  1 Bd are joined. 
     Second Embodiment 
     The electronic pen cartridge  1  of the first embodiment described above has a configuration in which the main body portion  1 Bd and the tip unit portion  1 Ut are bonded with an adhesive. For this reason, it is considered that the manufacturing efficiency may not be sufficiently improved because the bonding work process is typically required and the adhesive dry curing time is also required. Therefore, an electronic pen cartridge  1 A of the second embodiment eliminates the bonding work process and eliminates the need for adhesive dry curing time. 
       FIGS.  2 A and  2 B  are diagrams for illustrating a configuration example of the electronic pen cartridge  1 A according to the second embodiment.  FIG.  2 A  is a cross-sectional view of the electronic pen cartridge  1 A of the second embodiment cut in half in the longitudinal direction with the near side portion removed.  FIG.  2 B  is an external view of the electronic pen cartridge  1 A illustrated in  FIG.  2 A . As can be seen by comparing  FIG.  2 A  and  FIG.  1 A , in the electronic pen cartridge  1 A of the second embodiment illustrated in  FIGS.  2 A and  2 B , a component for fulfilling the electronic pen function has a configuration similar to that of the electronic pen cartridge  1  of the first embodiment described with reference to  FIGS.  1 A and  1 B . 
     Hence, in the electronic pen cartridge  1 A of the second embodiment illustrated in  FIGS.  2 A and  2 B , the same reference sign is used for the portion configured similarly to the electronic pen cartridge  1  of the first embodiment described with reference to  FIGS.  1 A and  1 B , and the detailed description of the part is omitted because of duplication. Also in a case of the electronic pen cartridge  1 A of the second embodiment, the cartridge has the main body portion  1 Bd and the tip unit portion  1 Ut as in the case of the electronic pen cartridge  1  of the first embodiment described with reference to  FIGS.  1 A and  1 B . 
     As illustrated in  FIG.  2 A , the main body portion  1 Bd is a portion configured by mounting the tip cap  12 , the pusher member  13 , the pen pressure detector  14 , the board holder  15 , and the circuit board  16  in the inner housing  11 . Further, the tip unit portion  1 Ut is a portion arranged in front of the main body portion  1 Bd, and is provided with the ferrite core  22  which is a cylindrical body having a through hole through which the core body  21  penetrates and the coil  23  formed by winding a coated conductor wire around the side surface of the ferrite core  22 . Further, as illustrated in FIG.  2 A, the first non-winding portion  22   a  and the second non-winding portion  22   b  in which coated conductor wires are not wound and no coil is formed are provided in certain definite ranges on the pen tip side and the rear end side of the ferrite core  22 . This point is also similar to that of the electronic pen cartridge  1  of the first embodiment. 
     Further, also in a case of the electronic pen cartridge  1 A of the second embodiment, the second non-winding portion  22   b  of the ferrite core  22  of the tip unit portion  1 Ut is fitted into a cylindrical portion with the longer diameter of the tip cap  12  of the main body portion  1 Bd to be fixed. However, in a case of the electronic pen cartridge  1 A of the second embodiment, it is not necessary to bond the joints of both the portions with a two-part epoxy adhesive, for example. In a state where the main body portion  1 Bd and the tip unit portion  1 Ut are joined, a sealing portion  24 A is formed by covering the periphery of these portions with a resin material such as plastic by insert molding. 
     That is, the sealing portion  24 A includes a part of the first non-winding portion  22   a  of the ferrite core  22  and covers the entire portion including the rear end face of the inner housing  11 . However, in the second embodiment, the sealing portion  24 A does not cover the entire rod-shaped connector  11   a  provided in the outer central portion of the bottom face of the inner housing  11 , and covers only the outer portion of the bottom face. In other words, except for the pen tip side portion of the first non-winding portion  22   a  of the ferrite core  22  and the rod-shaped connector  11   a  provided on the outside of the bottom face of the inner housing  11 , the entire portion is covered with the sealing portion  24 A. 
     As a result, as illustrated in  FIG.  2 B , the entire area including the connection between the main body portion  1 Bd and the tip unit portion  1 Ut can be covered with the sealing portion  24 A, so that the electronic pen cartridge  1 A in which the connection is not exposed can be achieved. In this case, the waterproof function can be firmly added to almost the entire electronic pen cartridge  1 A including the coil  23 . Moreover, since it is not necessary to bond the joint between the main body portion  1 Bd and the tip unit portion  1 Ut with an adhesive, the manufacturing efficiency can be improved. 
     Another Example of Second Embodiment 
       FIGS.  3 A and  3 B  are diagrams for illustrating a configuration example of an electronic pen cartridge  1 AX of another example of the second embodiment.  FIG.  3 A  is a cross-sectional view of the electronic pen cartridge  1 AX of another example of the second embodiment cut in half in the longitudinal direction with the near side portion removed. Further,  FIG.  3 B  is an external view of the electronic pen cartridge  1 AX illustrated in  FIG.  3 A . The electronic pen cartridge  1 AX illustrated in  FIGS.  3 A and  3 B  has substantially the same configuration as the electronic pen cartridge  1 A of the second embodiment described with reference to  FIGS.  2 A and  2 B . 
     However, the configurations of an inner housing  11 A and a sealing portion  24 B are different from those of the inner housing  11  and the sealing portion  24 A of the electronic pen cartridge  1 A of  FIGS.  2 A and  2 B . Therefore, in the electronic pen cartridge  1 AX of another example illustrated in  FIGS.  3 A and  3 B , the same reference signs are given to the portions configured similarly to the electronic pen cartridge  1 A illustrated in  FIGS.  2 A and  2 B , so that the description of the relevant portions is omitted, and the portions with different configurations will be described in detail. 
     In the electronic pen cartridge  1 AX of another example of the second embodiment illustrated in  FIG.  3 A , the inner housing  11 A of a main body portion  1 BdA does not have the rod-shaped connector  11   a  formed on the outer surface of the bottom face of the rear end. The outer surface of the bottom face of the inner housing  11 A is a flat surface. However, on the outside of the bottom face of the sealing portion  24 B, a rod-shaped connector  24 Ba is formed integrally with the sealing portion  24 B. That is, in a case of the electronic pen cartridge  1 AX of another example of the second embodiment illustrated in  FIGS.  3 A and  3 B , the rod-shaped connector  24 Ba extended in a rod shape on the rear end side is integrally formed at the central portion of the outer surface of the bottom face of the sealing portion  24 B formed by insert molding. 
     As a result, the inner housing  11 A can be made simple in shape so as not to include the rod-shaped connector  11   a , and the rod-shaped connector  24 Ba for use of attachment to the outer housing can also be formed as a part of the sealing portion  24 B formed by insert molding. In this case, the appearance of the electronic pen cartridge  1 AX illustrated in  FIG.  3 B  can be made the same as the appearance of the electronic pen cartridge  1 A illustrated in  FIG.  2 B . Consequently, the manufacturing process of the electronic pen cartridge can be simplified. 
     Third Embodiment 
     In the electronic pen cartridge  1  of the first embodiment described with reference to  FIGS.  1 A and  1 B , since the main body portion  1 Bd and the tip unit portion  1 Ut are bonded with an adhesive, these portions are not able to be separated after bonding. Further, since the electronic pen cartridges  1 A and  1 AX of the second embodiment described with reference to  FIGS.  2 A to  3 B  are configured to be entirely covered with the sealing portions  24 A and  24 B, each of the main body portions  1 Bd and  1 BdA and the tip unit portion  1 Ut are not able to be separated after the formation. 
     However, if the main body portion and the tip unit portion can be made up separately and connected closely so as to be attachable and detachable, the assembly is easy, and if there is a problem with either the main body portion or the tip unit portion, the defective one can be replaced. In addition, the components of the main body portion can also be replaced. Thus, an electronic pen cartridge  1 B of the third embodiment described below is configured such that the main body portion and the tip unit portion are separately made up and can be closely attached so as to be attachable and detachable. 
       FIGS.  4 A,  4 B and  4 C  are diagrams for illustrating a configuration example of the electronic pen cartridge  1 B according to the third embodiment.  FIG.  4 A  is a cross-sectional view of the electronic pen cartridge  1 B of the third embodiment cut in half in the longitudinal direction with the near side portion removed. Further,  FIG.  4 B  is an external view of the electronic pen cartridge  1 B illustrated in  FIG.  4 A . Further,  FIG.  4 C  is an external view of only a tip unit portion  1 UtB of the electronic pen cartridge  1 B illustrated in  FIG.  4 B . 
     Even in a case of the electronic pen cartridge  1 B of the third embodiment, the configuration of the portion that executes the electronic pen function is made in a similar manner to the electronic pen cartridge  1  of the first embodiment and the electronic pen cartridges  1 A and  1 AX of the second embodiment described above. Hence, also in the electronic pen cartridge  1 B of the third embodiment illustrated in  FIGS.  4 A,  4 B and  4 C , the portion configured in a similar manner to the electronic pen cartridges  1 ,  1 A and  1 AX of the first and second embodiments described above is assigned with the same reference sign, and detailed description of the relevant portion will be omitted. 
     As illustrated in  FIG.  4 A , the electronic pen cartridge  1 B of the third embodiment also includes a main body portion  1 BdB and the tip unit portion  1 UtB. The tip unit portion  1 UtB is provided with the coil  23  by winding a coated conducting wire around a central portion of a side surface of the ferrite core  22  which is a cylindrical body having a through hole through which the core body  21  penetrates. Therefore, the first non-winding portion  22   a  in which a coil is not formed is set in a fixed range from one end (the end on the pen tip side) toward the other end (the end on the rear end side) of the ferrite core  22  in the longitudinal direction. Similarly, a fixed range from the other end (the end on the rear end side) toward the one end (the end on the pen tip side) is set as the second non-winding portion  22   b  in which the coil is not formed. 
     Further, a sealing portion  24 C is provided so as to cover the coil  23 , a part of the first non-winding portion  22   a  on the coil  23  side of the ferrite core  22 , and the entire second non-winding portion  22   b . Unlike the sealing portion  24  of the electronic pen cartridge  1  of the first embodiment, the sealing portion  24 C is provided with a joint  24 Ca behind the second non-winding portion  22   b . The joint  24 Ca is a protrusion which has a through hole through which the core body  21  passing through the through hole of the ferrite core  22  is allowed to penetrate, and projects toward the rear end side, and on which a thread for connecting to an inner housing  11 B is formed. 
     That is, as illustrated in  FIG.  4 C , the tip unit portion  1 UtB is configured so as to cover a part of the first non-winding portion  22   a  on the coil  23  side of the ferrite core  22 , the coil  23 , and the entire second non-winding portion  22   b  and have the joint  24 Ca protruding toward the rear end side. As described above, the tip unit portion  1 UtB is made by integrally forming the portion covering the coil  23  and the joint  24 Ca having a thread by insert molding. 
     On the other hand, as illustrated in  FIG.  4 A , the inner housing  11 B of the third embodiment has, in the opening on the pen tip side, a connecting portion  11 Ba having a thread corresponding to a thread of the joint  24 Ca formed on the sealing portion  24 C of the tip unit portion  1 UtB. A holding ring  12 A is fitted into the opening of the tip cylindrical portion  15   a  of the board holder  15  so as to retain the pusher member  13  in the tip cylindrical portion  15   a  of the board holder  15 . That is, the outer diameter of the holding ring  12 A is the same as or slightly longer than the inner diameter of the tip cylindrical portion  15   a.    
     Due to this, as illustrated in  FIG.  4 A , the joint  24 Ca of the sealing portion  24 C can be attached, by being rotated in a screw-in manner, to the connecting portion  11 Ba formed by giving a thread in the opening of the inner housing  11 B. Therefore, as illustrated in  FIG.  4 B , one electronic pen cartridge  1 B can be configured in which the main body portion  1 BdB and the tip unit portion  1 UtB are closely connected to each other. 
     In this case, the coil  23  side of the first non-winding portion  22   a  of the ferrite core  22 , the coil  23 , and the entire second non-winding portion  22   b  are covered by the sealing portion  24 C, so that these portions can be firmly provided with a waterproof function. Moreover, since the tip unit portion  1 UtB and the inner housing  11 B are connected by a screw, water or the like does not enter the inner housing  11 B from the opening of tip of the inner housing  11 B. Therefore, the waterproof function can be firmly added to the entire electronic pen cartridge  1 B of the third embodiment. 
     As illustrated in  FIG.  4 C , the conductive wires  23   a  and  23   b  extended from both ends of the coil  23  are derived from the tip unit portion  1 UtB. The conductive wires  23   a  and  23   b  are extended toward the inner housing  11 B side, for example, through a groove provided in the longitudinal direction on a side surface of the inner housing  11 B and is connected to the circuit unit formed on the circuit board  16  in the inner housing  11 B. Actually, it is sufficient if the conductive wires from the circuit unit formed on the circuit board  16  in the inner housing  11 B are led out to the groove provided on the side surface of the inner housing  11 B in advance and the conductive wires  23   a  and  23   b  from the coil  23  of the tip unit portion  1 UtB are connected thereto. 
     The connector between the conductive wires from the circuit unit formed on the circuit board  16  and the conductive wires  23   a  and  23   b  from the coil  23  can take various measures. For example, when a ring-shaped terminal for connection is provided at the tips of the conductive wires sent out in the groove on the side surface of the inner housing  11 B and the conductive wires  23   a  and  23   b  from the coil  23  are hooked on this terminal, the connection can be easily made. Needless to say, other connection methods may be used. In conclusion, various connection methods for easy connection without any trouble can be adopted. 
     Modification Example of Third Embodiment 
     As described above, in a case of the electronic pen cartridge  1 B of the third embodiment, the connection between the conduction wires extending from both ends of the coil  23  and the circuit unit of the circuit board  16  is made on the outer side surface of the inner housing. Thus, in addition to a process for connecting the coil  23  to the circuit unit, the part of the conductive wire, which is laid on the outer side surface, needs to be subjected to a waterproof process separately in a case of connection on the outer side surface of the inner housing  11 B. Therefore, in the modification of the third embodiment, the coil  23  and the circuit unit of the circuit board  16  are connected to each other inside (within) the inner housing. 
       FIG.  5    is a cross-sectional view in a case where an electronic pen cartridge  1 BX of another example of the third embodiment is cut in half in the longitudinal direction with the near side portion removed, and the connection between a main body portion  1 BdC and a tip unit portion  1 UtC is illustrated as an enlarged view. Further,  FIGS.  6 A and  6 B  are diagrams for illustrating the configurations of the rear end face of the joint  24 Da of the tip unit portion  1 UtC, and the tip faces of the tip cylindrical portion  15   a  and the holding ring  12 A of the main body portion  1 BdC. 
     The electronic pen cartridge  1 BX of another example of the third embodiment illustrated in  FIG.  5    is configured in substantially the same manner as the electronic pen cartridge  1 B of the third embodiment described with reference to  FIGS.  4 A,  4 B and  4 C . Hence, in  FIG.  5   , the same reference signs are given to the portions configured in a similar manner to the electronic pen cartridge  1 B of the third embodiment illustrated in  FIGS.  4 A,  4 B and  4 C , and detailed description of the portions will be omitted. 
     As illustrated in  FIG.  5   , in the tip unit portion  1 UtC, the conductive wire  23   a  extending from one end of the coil  23  is connected to an electrode  25   a  provided on the rear end face of the joint  24 Da. Similarly, the conductive wire  23   b  extended from the other end of the coil  23  is connected to an electrode  25   b  provided on the rear end face of the joint  24 Da. That is, as illustrated in  FIG.  6 A , on the rear end face (end face exposed to the outside) of the joint  24 Da formed by insert molding as a part of a sealing portion  24 D, the electrodes  25   a  and  25   b  are provided at positions facing each other on both sides of a through hole HN through which the core body penetrates. As illustrated in  FIG.  6 A , the electrode  25   a  is connected to the conductive wire  23   a  extended from one end of the coil  23 , and the electrode  25   b  is connected to the conductive wire  23   b  extended from the other end of the coil  23 . 
     As described above, the joint  24 Da is formed as a part of the sealing portion  24 D, similarly to the joint  24 Ca of the electronic pen cartridge  1 B of the third embodiment illustrated in  FIGS.  4 A,  4 B and  4 C . However, the case of the joint  24 Da is different from the tip unit portion  1 UtB illustrated in  FIGS.  4 A,  4 B and  4 C  in that the electrodes  25   a  and  25   b  are provided on the rear end face, and the conductive wires  23   a  and  23   b  from the coil are connected to the electrodes through the inside of the joint  24 Da. 
     On the other hand, as illustrated in  FIG.  5   , conductive wires  16   e  and  16   f  extended from the circuit unit formed on the circuit board  16  mounted on the inner housing  11 B are connected to electrodes  17   a  and  17   b  provided on the tip faces of the tip cylindrical portion  15   a  and the holding ring  12 A of the main body portion  1 BdC. To be specific, as illustrated in  FIG.  6 B , on the tip faces of the tip cylindrical portion  15   a  and the holding ring  12 A, the electrodes  17   a  and  17   b  are provided at positions facing each other on both sides of a hole HB into which the core body is inserted. As illustrated in  FIG.  6 B , the conductive wire  16   e  extended from the circuit unit is connected to the electrode  17   a , and the conductive wire  16   f  extended from the circuit unit is connected to the electrode  17   b.    
     The rear end face of the joint  24 Da illustrated in  FIG.  6 A  and the tip faces of the tip cylindrical portion  15   a  and the holding ring  12 A illustrated in  FIG.  6 B  are surfaces facing each other when the tip unit portion  1 UtC is attached to the connecting portion  11 Ba of the main body portion  1 BdC in a screw-in manner. It is assumed that the joint  24 Da is fully inserted into the connecting portion  11 Ba of the main body portion  1 BdC by rotation. In this case, the electrode  25   a  on the rear end face of the joint  24 Da and the electrode  17   a  on the tip faces of the tip cylindrical portion  15   a  and the holding ring  12 A come in contact with each other while facing each other. Similarly, the electrode  25   b  on the rear end face of the joint  24 Da and the electrode  17   b  on the tip faces of the tip cylindrical portion  15   a  and the holding ring  12 A come in contact with each other while facing each other. 
     As a result, the coil  23  of the tip unit portion  1 UtC and the circuit unit of the circuit board  16  mounted on the inner housing are electrically connected. As described above, in a case of the electronic pen cartridge  1 BX of another example of the third embodiment, an electrical connection between the coil  23  and the circuit unit on the circuit board  16  can be made by simply attaching the joint  24 Da to the connecting portion  11 Ba of the main body portion  1 BdC in a screw-in manner. Therefore, unlike the case of the electronic pen cartridge  1 B of the third embodiment described with reference to  FIGS.  4 A,  4 B and  4 C , there is no need to connect the conductive wires extended from both ends of the coil  23  and the circuit unit of the circuit board  16  on the side surface of the inner housing. Consequently, the electronic pen cartridge  1 BX for easy connection work can be configured. 
     Equivalent Circuit of Electronic Pen Cartridge 
       FIG.  7    is a diagram illustrating an equivalent circuit of the electronic pen cartridges  1 ,  1 A,  1 AX,  1 B, and  1 BX according to the first, second, and third embodiments described above. As illustrated in  FIG.  7   , the electronic pen cartridges  1 ,  1 A,  1 AX,  1 B, and  1 BX have a configuration in which the coil (inductor)  23 , the capacitor  16   a , and the pen pressure detector  14  configured as a variable capacitance capacitor are connected in parallel. 
     Due to this, a resonance circuit is formed by the coil  23  and the capacitor  16   a , and it becomes possible to receive a signal from a position detection sensor of the electromagnetic induction type to form a transmission signal, and to transmit the signal to the position detection sensor to indicate the position. Further, by providing the pen pressure detector  14  configured as a variable capacitance capacitor, information indicating the pen pressure can be included in the transmission signal transmitted from the electronic pen cartridges  1 ,  1 A,  1 AX,  1 B, and  1 BX, as a phase change of the transmission signal. As described above, each of the electronic pen cartridges  1 ,  1 A,  1 AX,  1 B, and  1 BX can execute the function as an electromagnetic induction type electronic pen. 
     Effects of Embodiments 
     In the case of the electronic pen cartridge  1  of the first embodiment described above, the coil  23  provided at a position closer to the pen tip side than the main body portion  1 Bd can be covered thoroughly with the sealing portion  24  made of resin, so that waterproof functions can be added appropriately. Therefore, even if the electronic pen cartridge  1  is submerged in water, the resonance circuit including the coil  23  does not cause inconvenience such as change of the resonance frequency. 
     Further, in the case of the electronic pen cartridges  1 A and  1 AX of the second embodiment described above, the tip unit portion  1 Ut including the coil  23  and the main body portion  1 Bd or  1 BdA can be entirely covered with the resin sealing portions  24 A or  24 B. As a result, a waterproof function can be added entirely to the tip unit portion  1 Ut and the main body portion  1 Bd or  1 BdA. 
     Moreover, since the entire body is covered with the sealing portion  24 A or  24 B, it is not necessary to bond the main body portion  1 Bd or  1 BdA and the tip unit portion  1 Ut with an adhesive, and it is not necessary to secure a curing time until the adhesive is cured. That is, the manufacturing process can be simplified, and the manufacturing time can be shortened. Further, in the case of the electronic pen cartridge  1 AX of another example of the second embodiment, since the rod-shaped connector  24 Ba for connecting to the outer housing can also be formed as a part of the sealing portion  24 B, the manufacturing process can be further simplified. 
     Further, in a case of the electronic pen cartridges  1 B and  1 BX of the third embodiment described above, the main body portions  1 BdB and  1 BdC and the tip unit portions  1 UtB and  1 UtC can be connected in a screw-in manner, respectively. Due to this, the main body portion  1 BdB or  1 BdC and the tip unit portion  1 UtB or  1 UtC can be separately produced and easily connected in a screw-in manner, and thus the manufacturing process can be simplified. Moreover, since the main body portion  1 BdB or  1 BdC and the tip unit portion  1 UtB or  1 UtC can be separated at any time, a portion can be replaced if any of the portions is inconvenient. 
     Further, in the case of the electronic pen cartridge  1 BX of another example of the third embodiment, when the main body portion  1 BdC and the tip unit portion  1 UtC are connected in a screw-in manner, the coil  23  and the circuit unit formed on the circuit board  16  can also be electrically connected. Consequently, further simplification of the manufacturing process can be realized. 
     Modification Example 
     In the above-described embodiment, the size of the electronic pen cartridge  1  is described as having a diameter of 3.8 mm and a total length of 65.65 mm, but this is an example, and the size is not limited thereto. The size of the electronic pen cartridge can be adjusted in various ways. 
     Further, in the above-described embodiment, the case where the pen is applied to an electromagnetic coupling type electronic pen has been described as an example, but the present disclosure is not limited to this. As described above, the present disclosure can be also applied to a case where a waterproof function is added to the coil portion, for an electronic pen cartridge of an active capacitive type, for example, an electronic pen cartridge having a coil for charging a battery on the pen tip side. 
     Further, in another example of the third embodiment described with reference to  FIGS.  5 ,  6 A, and  6 B , the electrodes  25   a  and  25   b  and the electrodes  17   a  and  17   b  can have various positions and shapes. That is, when the tip unit portion  1 UtC and the main body portion  1 BdC are connected, various modes can be used as long as the coil  23  and the circuit unit of the circuit board  16  can be electrically and reliably connected. 
     Further, it is sufficient if the inner housing is what is called a pipe-shaped one having a hollow portion, and its appearance may have various shapes such as a cylindrical shape and a polygonal columnar shape. Needless to say, it is sufficient if the shape of the outer housing to which the electronic pen cartridge of the present disclosure is mounted is what is called a pipe shape having a hollow portion into which the electronic pen cartridge can be mounted. Hence, the appearance of the outer housing may, needless to say, have various shapes such as a cylindrical shape and a polygonal columnar shape. 
     It is to be noted that embodiments of the present disclosure are not limited to the foregoing embodiments, and that various changes can be made without departing from the spirit of the present disclosure. 
     The various embodiments described above can be combined to provide further embodiments. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications and publications to provide yet further embodiments. 
     These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.