Abstract:
Embodiments of a capacitive disk unit for a stylus for a capacitive touchscreen are disclosed. A conductive coupler has a flat proximal face and a socket for receiving a ball joint on its distal end. The distal portion of the socket may comprise a plurality of thin fingers that flex to capture the ball, forming notches between the fingers that are wide enough for the stylus shaft to pass into them, allowing the body of the stylus to be moved to a lower angle to the conductive coupler. Conductivity between the unit and the stylus is maintained continuously. If a larger diameter conductive surface is necessary, it may further comprise a disk and conductive layer, which may both be transparent. The conductive coupler may be molded of conductive polymer, and the disk may be overmolded using transparent polymer. Lack of metal parts reduces complexity, cost, and manufacturing defect risks.

Description:
[0001]    The disclosure relates to styluses for use with a capacitive touchscreen, and more particularly to articulated styluses having a conductive disk unit for use with a capacitive touchscreen. 
       DESCRIPTION OF THE RELATED ART 
       [0002]    Styluses for use with capacitive touchscreens are increasingly popular among users of tablet computers and touchscreen smartphones for a variety of reasons, such as keeping the touchscreen clean from fingerprints and other smears. Capacitive touchscreens on these devices have certain inherent limitations, however, in that they are designed to require the sensing of a capacitive touch over a large area while also having sufficient capacitance in order to be identified by the hardware and firmware as a touch. This generally means a contact area that is roughly the size of a fingertip, and a capacitance large enough to be a substantial part of a human body. 
         [0003]    A stylus tip must therefore mimic a human fingertip in size, and must somehow have enough capacitance electrically coupled to the stylus tip to meet the needs of the touchscreen hardware. Size is straightforward, but a large enough stylus tip, typically about 4.6 mm or larger in diameter, obscures the screen, making precision selection difficult. The capacitance of the human body can be electrically coupled to the stylus tip by providing a conductive path from the stylus tip through the handle to the hand of the user gripping the stylus, thus solving the second requirement. 
         [0004]    U.S. patent application Ser. No. 13/237974, filed Nov. 9, 2011, is incorporated herein by reference in its entirety, and discloses embodiments of a stylus for capacitive touchscreens having a disk with a conductive surface that is electrically coupled to the stylus body, the disk being joined to the stylus handle by an articulated joint. 
         [0005]    The inventors of the previous and present inventions created a stylus having a substantially transparent disk on an articulated joint to provide a precisely-sized non-obscuring stylus tip that remains flat against a touchscreen surface regardless of the angle at which the stylus body is being held or moved, across a wide angular range. Those previous embodiments used a transparent conducting disk, backed by a transparent polymer disk, having the conducting disk electrically coupled through a ball joint to the stylus handle, with a wear disk between the ball of the ball joint and the transparent conducting disk. The wear disk, made of a metal, prevented damage to the conducting disk by the ball of the ball joint while providing an electrically conductive path between the conductive disk and the ball of the ball joint. However, electrical coupling was intermittently lost when raising the stylus from the touchscreen because the ball of the ball joint would draw away from the wear disk. Also, the metal wear disk required careful preparation so that a sharp edge of the wear disk did not cut into the conductive disk; because of the resistivity of transparent conductors such as ITO, this type of damage changed the shape of the detected touch against the screen, and if the cut were around a substantial portion of the circumference of the metal wear disk, the damage could significantly reduce both the area over which capacitance was sensed and the amount of capacitance sensed, putting it below the threshold for which capacitive touchscreens are designed. Furthermore, the wear disk had a second potential damage mechanism in that when a wear disk was domed or dimpled or otherwise had a protrusion, it could force a portion of the conductive layer to protrude, resulting in increased wear of the conductive layer at the protrusion, ultimately leading to rapid degradation of electrical conductance as the conductive layer wore away. 
         [0006]    The risk of damage, as well as the ordinary wear on the transparent conductive disk, meant that it was desirable for the capacitive disk units to be user-replaceable, and so a snap-on/snap-off socket was used. However, the physical design of the snap meant that the socket had to engage the ball of the ball joint above a great circle such that greater than 50% of the ball was below the snap. This restricted the angle that could be formed between the stylus body and the capacitive disk to about 40 degrees from vertical in any direction. As touchscreens have grown in size, this increasingly limits the user&#39;s freedom of movement when using a stylus to interact with a touchscreen. 
         [0007]    Other stylus designs hold a transparent conductive member using an elastic coupler, or along an edge of the conductive member at a fixed angle. Other capacitive styluses are known in the art, most commonly using a conductive silicone rubber tip. 
         [0008]    Improvements reducing the complexity and the chance of self-inflicted physical damage to the capacitive disk unit, and increasing the range of movement of the capacitive disk unit, are greatly desirable. 
       BRIEF DESCRIPTION OF THE EMBODIMENTS 
       [0009]    Embodiments are disclosed using a conductive polymer coupler to provide electrical conductance from a contacting surface of the conductive disk unit to the ball of the ball joint. By making the coupler of a conductive polymer, the metal wear disk of prior art designs can be eliminated. Embodiments are disclosed having a ball socket with fingers, which allows a wider range of angles between the stylus body and the contacting surface of the conductive disk unit. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a perspective drawing of an embodiment of a capacitive disk unit having a coupler; 
           [0011]      FIG. 2  is a cross-sectional view of a capacitive disk unit having a coupler; 
           [0012]      FIG. 3  is a top view of an embodiment of a capacitive disk unit having a coupler; 
           [0013]      FIG. 4  is a side view of an embodiment of a capacitive disk unit having a coupler; 
           [0014]      FIG. 5  is a perspective drawing of an embodiment of a capacitive disk unit with a stylus coupled to it; 
           [0015]      FIG. 6  is a cross-sectional view of a capacitive disk unit with a stylus coupled to it; 
           [0016]      FIG. 7  is a top view of an embodiment of a capacitive disk unit with a stylus coupled to it; 
           [0017]      FIG. 8  is a side view of an embodiment of a capacitive disk unit with a stylus coupled to it; 
           [0018]      FIG. 9  is a perspective drawing of an embodiment of a capacitive disk unit for a high-resolution capacitive touchscreen with a stylus coupled to it; 
           [0019]      FIG. 10  is a cross-sectional view of a capacitive disk unit for a high-resolution capacitive touchscreen; 
           [0020]      FIG. 11  is a top view of an embodiment of a capacitive disk unit for a high-resolution capacitive touchscreen; 
           [0021]      FIG. 12  is a side view of an embodiment of a capacitive disk unit for a high-resolution capacitive touchscreen; 
           [0022]      FIG. 13  is a perspective drawing of an embodiment of a capacitive disk unit having a wear disk; 
           [0023]      FIG. 14  is a cross-sectional view of a capacitive disk unit having a wear disk; 
           [0024]      FIG. 15  is a top view of an embodiment of a capacitive disk unit having a wear disk; 
           [0025]      FIG. 16  is a side view of an embodiment of a capacitive disk unit having a wear disk; 
           [0026]      FIG. 17  is a cross-sectional view of parts other than the monolithic body for an embodiment of a capacitive disk unit having a wear disk; 
           [0027]      FIG. 18  is a cross-sectional view of a monolithic body for an embodiment of a capacitive disk unit having a wear disk; 
           [0028]      FIG. 19  is a cross-sectional view of an embodiment of a capacitive disk unit having a wear disk, coupled to a stylus; 
           [0029]      FIG. 20  is a cross-sectional view of an embodiment of a capacitive disk unit having a coupler with a stylus coupled to it; 
           [0030]      FIG. 21  is a perspective view of an embodiment of a capacitive disk unit; 
           [0031]      FIG. 22  is a cross-sectional view of an embodiment of a capacitive disk unit; 
           [0032]      FIG. 23  is a top view of an embodiment of a capacitive disk unit; 
           [0033]      FIG. 24  is a side view of an embodiment of a capacitive disk unit coupled to a stylus; 
           [0034]      FIG. 25  is a top view of an embodiment of a disk component; 
           [0035]      FIG. 26  is a perspective view of an embodiment of a disk component; 
           [0036]      FIG. 27  is a side view of an embodiment of a disk component; 
           [0037]      FIG. 28  is a cross-sectional view of an embodiment of a disk component; and 
           [0038]      FIG. 29  is a top view of an embodiment of a conductive layer. 
       
    
    
     DETAILED DESCRIPTION 
       [0039]    The following detailed description of embodiments of the invention references the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. The embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that logical changes may be made without departing from the spirit and scope of the present invention. The detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined solely by the appended claims. 
         [0040]    Please refer to  FIG. 1 ,  FIG. 2 ,  FIG. 3 , and  FIG. 4 , four views (perspective, cross-sectional, top, and side, respectively) of an embodiment of a capacitive disk unit. The embodiment of a capacitive disk unit  100  has a conductive layer  110 , a disk  120 , and a coupler  130 . 
         [0041]    The conductive layer  110  is conductive so that it can interact with a capacitive touchscreen of a typical smartphone or tablet computer, such as the Apple® iPhone® or iPad®. The conductive layer  110  serves to couple a capacitance to a larger area of a capacitive touchscreen, in order to meet the touch size requirements of a given capacitive touchscreen. The size of the conductive layer  110  is thus determined by the requirements of the capacitive touchscreen(s) on which the capacitive disk unit  100  is intended to be used; current devices typically use capacitive touchscreens designed to detect objects of about the size and capacitance of a human fingertip, leading to a diameter of about  4 . 6 mm. The conductive layer  110  is substantially flat. The conductive layer  110  may optionally have the property of being transparent by manufacturing it with a transparent conductor, for example ITO or AZO. The conductive layer  110  is backed by both the disk  120  and the coupler  130 . The conductive layer may be formed directly upon the disk  120  and coupler  130 , or it may be formed separately and attached to the disk  120 , or to the disk  120  and coupler  130 , with an adhesive layer  115 . When attached with adhesive, then either the adhesive must be conductive or the adhesive should be applied in a pattern such that the conductive layer  110  remains electrically coupled to the coupler  130 . In  FIG. 2 , the adhesive layer  115  is shown as having a central hole  116  so that the coupler  130  may directly abut the conductive layer  110 ; for example, the adhesive may be laid out in an annular pattern on the disk  120 , or on the disk  120  and the coupler  130 . 
         [0042]    The disk  120  may be made of any rigid material, and may be transparent. Some embodiments use a transparent polymer material for the disk  120 . The disk  120  serves to protect the conductive layer  110  from damage that might otherwise be caused by overstressing the conductive layer  110 , such as by bending the conductive layer  110  or nicking the edges of the conductive layer  110 . The size of the disk  120  may be equal to or larger than the size of the conductive layer  110 . The size and shape of the disk  120  is selected to conform to the size and shape of the conductive layer  110 , which in turn is based upon the requirements of the electronic device for which the stylus and capacitive disk unit will be used; current devices typically use capacitive touchscreens designed to detect objects of about the size and capacitance of a human fingertip, leading to a diameter of about  4 . 6 mm. 
         [0043]    The coupler  130  has a socket  133  to receive a ball of a ball joint, the socket comprising a plurality of fingers  132 , which define a plurality of notches  131 ; optionally, the coupler  130  may further have a slight protrusion on its proximal face  134  to press against the conductive layer  110 , or the coupler&#39;s proximal face  134  may be substantially flat. In embodiments in which the coupler  130  has a protrusion, the protrusion increases the contact pressure between the coupler  130  and the conductive layer  110 , thereby helping to ensure conductivity. Unlike uncontrolled convexity as a result of manufacturing defects in the prior art products, such a protrusion in the present invention can be designed in and carefully controlled in the design, forming, and assembly processes so that the resulting product does not cause premature wear of the conductive layer  110  of the capacitive disk unit  100 . The notches  131  may optionally extend below an equator of the socket  133 , whereas the fingers  132  extend above the equator of the socket  133  and serve to retain a ball of a ball joint in the socket  133 . The coupler  130  is made of a conductive material; some embodiments use a conductive polymer for the coupler  130 . Because the fingers  132  can be made thin enough to allow a conductive polymer to flex without fracturing, a ball of a ball joint can be snapped into and out of the socket  133  repeatedly. Although three notches  131  are shown in the example drawings, embodiments using two, three, four, and more notches have been considered during development; as the number of notches  131  increases, the amount of remaining material in the fingers  132  for effecting retention of the ball in the socket  133  necessarily decreases. Testing has found that three notches  131 , defining three fingers  132 , provides a good balance between the competing desires of a strong connection and smooth movement. The disk  120  may ride on the sides #### of the coupler  130  without being attached; or may be mechanically attached to the coupler  130  along a contact region  137  through friction or through the use of interlocking shapes such as grooves or scallops (for example, see the embodiments of  FIG. 20  and  FIG. 24  below); or may be bonded to the coupler  130  along the contact region  137  either chemically, or with adhesives, or during molding when appropriate materials (such as compatible polymers) are selected for both the disk  120  and the coupler  130  such that, for example, overmolding melts or bonds the two materials together. 
         [0044]    Referring to  FIG. 5 ,  FIG. 6 ,  FIG. 7 , and  FIG. 8 , four views (perspective, cross-sectional, top, and side respectively) of the same embodiment as in  FIGS. 1-4  of a capacitive disk unit  100 , shown here coupled to a stylus  10 . The stylus  10  comprises a handle  11 , a shaft  12 , and a ball  13 . The ball  13  fits within the socket  133  of the coupler  130 , thus forming a ball joint. The ball  13 , shaft  12 , and handle  11  may be made of a conductive material such as a metal or a conductive polymer. The shaft  12  is electrically coupled to the ball  13 . The shaft  12  may be directly connected to the handle  11  thus forming an electrical connection therewith, or the shaft  12  may be isolated from the handle  11  and be coupled to electronics (not shown), which may optionally in turn be coupled to the handle  11 . 
         [0045]    Referring to  FIG. 6  and  FIG. 8  in particular, the shaft  12  of the stylus is shown nestled in one of the notches  131  of the coupler  130 . This allows the handle to be held at a closer angle to the conductive layer  110  of the capacitive disk unit  100  than with prior-art capacitive disks. This allows a user more freedom of movement and position when using the stylus  10 , for example when drawing or writing on a large-screen tablet computer. 
         [0046]    As seen in  FIG. 3  and  FIG. 7  the fingers  132  have a wedge-shaped aspect when viewed from above. The design allows the shaft  12  of the stylus  10  to engage a notch  131  no matter what angle relative to the capacitive disk unit  100  at which the shaft  12  is moved; due to the small sizes of the fingers  132 , the shaft  12  readily slips into a nearby notch  131  regardless of the angle and pressure used. In use, with the capacitive disk unit  100  pressed flat against a surface such as a capacitive touchscreen (not shown), this wedging causes the capacitive disk unit  100  to rotate such that the shaft  12  moves into a notch  131  as the handle moves away from an orthogonal position. In use, pressure by the ball  13  of the stylus  10  against the bottom of the socket  133  elastically deforms the coupler  130 , pressing its proximal face  134  against the capacitive layer  110 , thus helping to ensure that electrical conductivity is maintained. The bottom of the socket  133  is closed, which limits the force that can be transmitted through the shaft  12  and ball  13  against the conductive layer  110 , and helps prevent wear and damage to the conductive layer  110  by spreading the force over a wider area. 
         [0047]    Please refer now to  FIG. 9 ,  FIG. 10 ,  FIG. 11 , and  FIG. 12 , four views (perspective, cross-sectional, top, and side respectively) of an embodiment of a capacitive disk unit consisting of a monolithic coupler.  FIG. 9  also shows the capacitive disk unit  101 , which in this embodiment is the coupler  130 , coupled to a stylus  10 . High-resolution touchscreens exist for some electronic devices and may become more prevalent; the necessary diameter of a detectable touch for these is smaller, and indeed the electronics can be designed to require a small enough touch that the larger area provided by having a disk  120  and conductive layer  110  are unnecessary. However, a large capacitance is still desirable to weed out noise. The coupler  130  may be used by itself on the end of a stylus, without a conductive layer  110  or a disk  120 . These figures show a coupler  130  with a substantially flat proximal face  134  as the conductive surface that interacts with a capacitive touchscreen&#39;s capacitive flux. The coupler  130  further has a ball joint socket comprising fingers  132 , notches  131 , and substantially spherical socket  133  for coupling to a ball  13  as seen in  FIG. 9 . 
         [0048]    The coupler  130  is made of a conductive polymer, and so serves to electrically couple a conductive surface that interacts with the touchscreen to the ball joint  13 , whether that conductive surface is a conductive layer  110  electrically coupled to a coupler  130 , as in some embodiments, or a proximal face  134  of the coupler  130  itself as in other embodiments. The ball joint  13  is in turn electrically coupled to the shaft  12 , which in turn may be electrically coupled to the handle  11  when used with passive styluses, or may be electrically coupled to active electronics (not shown). When a passive stylus is held by a human hand, the human body is thus electrically coupled to the conductive surface that is interacting with the touchscreen&#39;s capacitive flux, thereby providing sufficient capacitance to interact with high-resolution capacitive touchscreens. 
         [0049]    Please refer now to  FIG. 20 , which shows a cross-section of an embodiment of a capacitive disk unit with a stylus. The capacitive disk unit  300  comprises a coupler  330  and disk  320 . In this embodiment, the coupler  330  further comprises a step in the contact region  337  between the disk  320  and the coupler  330 , and the disk  320  further comprises a matching step, which serves to increase the contact area between the disk  320  and the coupler  330 . This variation in the shape of the contact region  337  serves to provide increased surface area for bonding between the two materials, and may instead or in addition be shaped with ridges, grooves, scallops, dimples, textured surfaces, or other variations, to interlock and/or create mechanical interference between the two materials so as to prevent separation. Although  FIG. 20  shows a step in the contact region  337 , other shapes are well known in the art of plastic injection molding and may be used instead or in addition. 
         [0050]    Refer now to  FIG. 21 ,  FIG. 22 ,  FIG. 23 , and  FIG. 24 , which are four views (perspective, cross-sectional side, top, and side with stylus view respectively) of an embodiment of a capacitive disk unit. The capacitive disk unit  400  has a conductive layer  110 , a disk  420 , and a coupler  430 . The disk&#39;s proximal face  424  and coupler&#39;s proximal face  434  may be substantially coplanar, or the proximal face  434  of the coupler  430  may protrude slightly beyond the proximal face  424  of the disk  420  to increase contact with the conductive layer  110 . The contact region  437  between the disk  420  and coupler  430  may optionally be physically shaped to help prevent separation of the two components, as shown in the figures of this embodiment, or the disk  420  may ride loosely upon the coupler  430  as discussed in previous embodiments, or the disk  420  may be attached to the coupler  430  through overmolding, adhesive or chemical bonding, or other means generally known. The disk  420  may optionally be of a transparent material such as a transparent polymer. The coupler  430  is conductive; the coupler  430  may be made of a conductive polymer. The coupler  430  is electrically coupled to the conductive layer  110 . The conductive layer  110  may be formed directly upon the proximal faces  424 , 434  of the disk  420  and coupler  430  or may be adhered to the disk  420 , or to the disk  420  and coupler  430 , by means of an adhesive layer  115 . The conductive layer  110  may be formed of a transparent conductive material, for example ITO or AZO. The adhesive layer  115  may be of a conductive adhesive or a nonconductive adhesive; if the adhesive layer  115  is of a nonconductive adhesive, then the adhesive layer  115  must have a hole  116  through which the coupler  430  may electrically couple to the conductive layer  110 ; the adhesive layer  115  and hole  116  may, for example, be substantially annular in layout. The coupler  430  has a socket  433  sized to fit a ball  13  of a stylus  10 , thus forming a ball joint. The rim  432  of the socket  433  is of a smaller diameter than the ball  13 , thereby retaining the ball  13  when the ball  13  is snapped into the socket  433 . 
         [0051]      FIG. 25 ,  FIG. 26 ,  FIG. 27 , and  FIG. 28  are top, perspective, side, and cross-sectional views of a disk  120  used by some embodiments. The disk  120  has a central hole  126  that fits around a coupler embodiment. The contact surface  127  of the disk  120  is shaped or molded to substantially match the contact surface of the embodiment of the coupler for which the particular embodiment of the disk  120  is to be used. The proximal face  124  of the disk  120  may have a conductive layer formed directly upon it or attached by conventional means such as adhesive. 
         [0052]      FIG. 29  shows a top view of a conductive layer  110 . The conductive layer  110  is substantially flat and is electrically conductive. The conductive layer  110  may optionally be transparent, for example when made with ITO, AZO, or a similar transparent conductive material, or may be translucent or opaque if made with a metal foil, conductive polymer, or other conductive material. 
         [0053]    As explained in the previous embodiments, using a conductive polymer as the material for the coupler  130  has several advantages over the prior art. First, conductivity is maintained no matter whether the stylus is being pressed against a surface or not, because no matter whether the stylus is being lifted (in embodiments using a coupler, resulting in the conductive disk unit  101  hanging from the ball  13  of the stylus  10 , with the resultant contact between the ball  13  of the ball joint and the socket  133  being at an upper interior surface of the socket  133  such as at the fingers  132 ) or the stylus is being pressed, the ball  13  of the ball joint will always be in contact with conductive material of the socket  133  of the coupler  130  in embodiments of the present invention. Second, manufacturing is simplified, because no conductive metal wear disk is necessary to protect the thin and fragile conductive layer  110 , reducing parts complexity. Third, the metal wear disk of the prior art had to be made carefully so that no sharp edges could result in cutting of the conductive layer  110 ; if a sharp edge damaged the conductive layer  110 , because of the resistivity of the ITO used for the transparent conductive layer, overall capacitive coupling could be reduced and the touch sensed by a capacitive touchscreen could become reduced and distorted in size and shape. 
         [0054]    The shape of the improved coupler  130  also has significant advantages over the prior art. In addition to allowing the stylus body to be moved through a broader angular range relative to the face of the capacitive disk unit by virtue of allowing the shaft  12  of a stylus  10  to fit into a notch  131 , the fingered design allows more brittle polymers, such as conductive polymers, to be used; the fingers  132  allow the polymer to flex more than the previous full-circumference-capture socket design, so although the conductive polymer is more brittle than the polymers used in prior-art implementations, the socket  133  nevertheless does not fracture. The fingers  132  also retain the ball over a larger effective volume, resulting in a more secure connection and helping to maintain electrical conductivity at all times. 
         [0055]      FIG. 13 ,  FIG. 14 ,  FIG. 15 , and  FIG. 16  are drawings (in perspective, cross-section, top view, and side view respectively) of an embodiment of a capacitive disk unit having a monolithic body. Additionally, for clarity,  FIG. 18  shows the monolithic body  230  alone in cross-section.  FIG. 17  shows a cross-sectional view of parts other than the monolithic body  230  for the embodiment of a capacitive disk unit  200  having a monolithic body  230 .  FIG. 19  shows an embodiment of a capacitive disk unit  200  coupled to a stylus. The capacitive disk unit  200  comprises a monolithic body  230  having a socket  233  for a ball joint intersecting a hollow  250 , thus allowing a ball  13  of a ball joint to contact a wear disk  50  inserted into the hollow  250  molded into the underside of the monolithic body  230 . The top of the socket  233  has a plurality of fingers  132  defining a plurality of notches  131 . An adhesive layer  215  bonds a conductive layer  110  to the proximal face  234  of the monolithic body  230 . A hole  216  in the adhesive layer  215 , said hole  216  being larger than the opening  251  in the bottom of the ball socket  233 , prevents the adhesive of the adhesive layer  215  from gumming up the ball joint and also allows the conductive layer  110  to remain in contact with and hence electrically coupled to the wear disk  50 . The wear disk  50  protects the relatively fragile conductive layer  110  from being torn or worn away by the motion of the ball  13  in the socket  233  while allowing the conductive layer  110  to be electrically coupled to the ball  13 , which is electrically coupled to the shaft  12 . The ball socket  233  is in the form of a substantially spherical intersection with the monolithic body  230 , as contrasted with the prior art being roughly hemispherical at the socket and open toward the proximal face  234 . Because the ball socket  233  is spherical, it provides support to the ball  13  of the ball joint when the stylus  10  is pressed against a surface; this support helps to prevent damage to the conductive layer  110  from the ball  13  transmitting the full user-applied force to the wear disk  50 , and through that to the conductive layer  110 . Instead, in the present embodiment, force is transmitted through the ball  13  to the monolithic body  230  as well as the wear disk  50 , thus limiting the differences in force applied between an edge of the conductive layer  110  and the center of the conductive layer  110  directly below the wear disk  50 . The shaft  12  may electrically couple the conductive layer  110  to the handle  11 , and through that to the user, in the case of a passive stylus; or to electronic circuitry (not shown) in the case of an active stylus, or to both, to provide sufficient capacitance for the capacitive touchscreen (not shown) with which the stylus is used to function. 
         [0056]      FIG. 17  shows the cross-section view of  FIG. 14 , but with the monolithic body  230  removed so that details of the adhesive layer  215  can be seen more readily. At manufacturing time, the conductive layer  110  is laid flat, the wear disk  50  is placed on top of the conductive layer  110 , and the adhesive layer  215  is placed over the tops of both the wear disk  50  and conductive layer  110 . This helps to hold the wear disk  50  against the conductive layer  110 , thus helping to maintain conductivity between them. The wear disk  50  fits within the hollow  250  in the monolithic body  230 , and the ball  13  of the stylus body  10  is held against it. The hollow  250  may be shaped to fit the wear disk  50  and adhesive layer  215  closely, or may be of a more open size or more arbitrary shape. The hollow  250  intersects the socket  233  to form an opening  251  through which the ball  13  of the ball joint, when inserted into the socket  233 , contacts the wear disk  50 . The wall  252  of the hollow  250  may optionally be tapered such that the hollow  250  is wider where it intersects the proximal face  234  than at its top  253  where it intersects the socket  233 ; this helps to center the wear disk  50  during assembly of the capacitive disk unit  200 , particularly when the hollow  250  is shaped to fit the wear disk  50  and adhesive layer  215  closely. 
         [0057]    While the disclosure has been described by way of examples and in terms of embodiments, it is to be understood that the disclosure is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.