Abstract:
Embodiments of a stylus having a capacitive slide sensor and grip sensors are disclosed, for use with electronic devices and particularly with touchscreen devices. The stylus is in signal communication with the electronic device, either wired or wirelessly, and the slide sensor allows a user to generate a sliding data value as well as a contact/no-contact datum; these can be used as scaled control values or as buttonpress control values to control features of applications running on the electronic device. The capacitive sensors are formed on a single flexible PCB wrapped inside the stylus barrel.

Description:
FIELD OF THE DISCLOSURE 
       [0001]    The disclosure relates to styluses, and more particularly to a stylus with a capacitive slide sensor for use with electronic devices such as those having a touchscreen 
       SUMMARY OF THE PRIOR ART 
       [0002]    Touchscreen devices have become widespread as tablet computers and smartphones. These devices allow the user to manipulate the phone&#39;s user interface through a touch sensor that overlays their displays, allowing the user to touch the screen with an object to input a position or movement to the device. These touches may then be used by the operating system of the device to interpret gestures and selections that control the device&#39;s functions. The touch sensor replaces the mouse, trackball, and other pointer devices to control position sensing on the user interface. 
         [0003]    These touchscreen devices may operate in a number of ways. Some require a dedicated stylus that must be used with the device at all times. This proves inconvenient, because the stylus may become lost or damaged, rendering the device partly useless until a new stylus is procured. As a result, touchscreen device manufacturers have moved to the use of touch sensors that can sense a human finger through capacitive sensing. Two major types of capacitive sensors are in use: mutual capacitance and self capacitance. Mutual capacitance has an advantage over self capacitance in that it allows for the tracking of multiple simultaneous touches. This allows for multi-touch gestures to be interpreted by the operating system, and so manufacturers have chosen to use mutual capacitance sensors in most modern devices. The mouse-replacement of the touch sensor is thus augmented beyond the capabilities of the computer mouse, which only generates a single position input. 
         [0004]    However, the use of a finger creates its own issues for the end user, such as imprecise touch precision recognition and leaving skin oils and other contaminants on the screen. So, many users choose to use styluses that can be detected by the touchscreens to control their phones, with their fingers as a backup option when multi-touch gestures are necessary. 
         [0005]    Styluses may further be in signal communication with an electronic device to transmit additional data to the electronic device, such as the force being applied to the stylus tip. Buttons may be added to the stylus, similar to mouse buttons, to allow additional user control as well as allowing the stylus to be powered on and off. Adding functionality and control features to styluses gives users an ability to augment the capabilities of their electronic devices for ease of use. 
         [0006]    Improvements in stylus sensors are therefore desirable. 
       SUMMARY OF CERTAIN ASPECTS OF THE EMBODIMENTS 
       [0007]    Embodiments described herein disclose a stylus for use with electronic devices such as touchscreen devices. Embodiments of the stylus have a capacitive slide sensor along the barrel (sometimes called the body or the housing) of the stylus, a control circuit, and a communications subcircuit so that the stylus may be in signal communication with an electronic device with which it is being used; communications may be either wired or wireless or both in different embodiments. Some embodiments have the slide sensor positioned in a grip area of the stylus barrel. Some embodiments position the slide sensor underneath a mechanical button or buttons located on a side of the stylus barrel. Some embodiments further comprise a second capacitive sensor that detects proximity of a capacitive target to the grip area. Some embodiments further comprise a three-axis accelerometer able to determine an orientation of the stylus. Some embodiments may further comprise other sensors, such as a force-sensing tip. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  shows a plan view of an embodiment of a stylus having proximity and slide sensors; 
           [0009]      FIG. 2  shows a sectional view of some interior components of a stylus having proximity and slide sensors; 
           [0010]      FIG. 3  shows a top view of some interior components of a stylus having proximity and slide sensors, showing the layout of a first conductive layer of the flexible PCB; 
           [0011]      FIG. 4  shows a left side view of some interior components of a stylus having proximity and slide sensors; 
           [0012]      FIG. 5  shows a top view of some interior components of a stylus having proximity and slide sensors; 
           [0013]      FIG. 6  shows a right side view of some interior components of a stylus having proximity and slide sensors; 
           [0014]      FIG. 7  shows a perspective view of some interior components of a stylus having proximity and slide sensors; 
           [0015]      FIG. 8  shows a flat view of a first side of a flexible PCB on which a slide sensor is formed; 
           [0016]      FIG. 9  shows a flat view of a second side of a flexible PCB on which a plurality of proximity sensors are formed; 
           [0017]      FIG. 10  shows a proximity sensor electrode; 
           [0018]      FIG. 11  shows a proximity sensor ground electrode; 
           [0019]      FIG. 12  shows an exploded view of a pair of electrodes for a slide sensor; 
           [0020]      FIG. 13  shows a slide sensor ground electrode; 
           [0021]      FIG. 14  shows a proximity sensor electrode; 
           [0022]      FIG. 15  shows a proximity sensor ground electrode; 
           [0023]      FIG. 16  shows an edge-on view of a flexible PCB; and 
           [0024]      FIG. 17  shows a cross sectional view of some components of a stylus having proximity and slide sensors. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0025]    The following detailed description of embodiments references the accompanying drawings that form a part hereof, and in which are shown by way of illustration various illustrative embodiments through 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 invention. The detailed description is, therefore, not to be taken in a limiting sense, and the scope of the invention is defined solely by the appended claims. 
         [0026]    Please refer to  FIG. 1 , an embodiment of a stylus. Externally, the stylus  1  has a barrel  10 , a tip  20 , and a cosmetic button  30 . In some embodiments, the tip  20  may be an active electronic stylus tip comprising a plurality of electrodes (as shown here); in some embodiments (not shown) the tip may be a disk tip or mesh tip or silicone tip. The stylus  1  may further have a charging port  40 , which may in some embodiments (shown here) be located on the rear of the stylus; other embodiments (not shown) may charge through the stylus tip; still other embodiments (not shown) may charge through the stylus barrel, for example by inductive charging. Shown in outline are a battery  45  and one possible general location of the components described in further detail below 99. 
         [0027]    Referring now to  FIGS. 2-7  and  FIG. 17 , internally, the stylus  1  comprises a circuit board  110 , a chassis  120  which may in some embodiments be made of multiple parts such as upper chassis  120 A and lower chassis  120 B, one or more proximity sensors  130 , and a slide sensor  140 . The proximity and slide sensors may be attached to or formed upon a flexible PCB  180 . The stylus  1  may also optionally comprise a force sensor (not shown) operatively coupled to the tip  20 , a battery to power the circuit, a charger (typically as part of the circuit on circuit board  110 ) to recharge the battery, and electrical contact points (typically as part of the charging port  40 ) for supplying power to the charger. 
         [0028]    In some embodiments, the circuit board  110  comprises a communication subcircuit  112  for example without limitation an RF communications chip for Bluetooth or WiFi. In some embodiments, the stylus may communicate over a wired connection such as a USB cable or dedicated cable. 
         [0029]    The proximity sensor or sensors  130  and the slide sensor  140  detect the proximity of a target, for example but not limited to a finger of a user of the stylus, near a given sensor. The slide sensor  140  uses a pair of proximity sensors, each having a varied width, to sense a relative position of a target along the length of the slide sensor  140  and to output a single datum indicating the position; the datum output by the slide sensor  140  may in some embodiments also indicate lack of a touch and hence lack of a position. The proximity sensor or sensors  130  are single proximity sensors that vary an output datum according to a target&#39;s nearness and capacity; they may output a boolean datum indicating presence or absence of a target, or may output a datum indicating a level of proximity. The word “touch” is used to indicate the detection of a target in proximity to generate a proximity datum, which may then be output by a sensor. A touch “on” a sensor does not necessarily indicate physical contact with the sensor, but rather indicates that the presence of a target was sufficiently close to the sensor to cause the sensor to detect proximity; this typically results in the generation of a datum indicating proximity which is then output by the sensor subsystem. 
         [0030]    Where a plurality of proximity sensors  130 , such as proximity sensor  130 A and proximity sensor  130 B of  FIG. 3 , are used, in some embodiments they may be independent of each other and generate a datum for each proximity sensor; in some embodiments they may be unitary and generate a single datum for whether at least one proximity sensor senses proximity; in some embodiments they may be unitary and generate a single datum only if all proximity sensors sense proximity. 
         [0031]    In a battery powered stylus  1 , the proximity sensor or sensors  130  may be used for saving power by keeping the stylus  1  in a low-power or standby mode when the proximity sensor or sensors  130  does not detect proximity, i.e., when the stylus is not being held by a user. In embodiments where a plurality of proximity sensors are used, the low-power mode may be entered into in some embodiments only when all proximity sensors do not detect proximity, while in other embodiments the low-power mode may be entered into when one or more proximity sensors do not detect proximity. 
         [0032]    Referring momentarily to  FIG. 16 , a flexible PCB  180  of two layers has a first side  181  and a second side  182 , with the first side  181  having a conductive layer  181 L and a nonconductive cover  1810 , and the second side having a conductive layer  182 L and a nonconductive cover  182 C. In some embodiments, the flexible PCB  180  is a two-layer circuit board having a first side  181  and a second side  182 , each side comprising a conductive layer  181 L, 182 L formed on a flexible substrate  185 , for example without limitation a polyimide flexible substrate. Each conductive layer may be formed or etched into different patterns. Each conductive layer may further be covered with a nonconductive cover layer  181 C, 182 C which protect the conductive layers and prevents them from shorting against other conductive components inside the stylus. 
         [0033]    Now please refer to  FIG. 8  through  FIG. 16 , which show a flexible PCB  180  having multiple sensors laid out upon it. 
         [0034]    In some embodiments, the slide sensor  140  and proximity sensor or sensors  130  are formed on a single flexible PCB  180 . In some embodiments (not shown), the slide sensor and proximity sensor or sensors may be formed on separate flexible PCBs. 
         [0035]    In some embodiments, the slide sensor  140  and proximity sensor or sensors  130  are formed on different sides of the flexible PCB  180  and in different regions from each other. For example, the slide sensor  140  is formed on conductive layer  181 L in region  180 R 1 , while the proximity sensor or sensors  130  are formed on conductive layer  182 L in region  180 R 2 . The slide sensor  140  comprises two electrodes  140 E 1 , 140 E 2  and a ground electrode  140 G to help isolate the electrodes  140 E 1 , 140 E 2  from outside interference. The proximity sensor  130 A comprises an electrode  130 AE and a ground electrode  130 AG; the proximity sensor  130 B comprises an electrode  130 BE and a ground electrode  130 BG. All ground electrodes may be tied together to a common ground (not shown). Each electrode  140 E 1 , 140 E 2 , 130 AE, 130 BE is separately electrically coupled by traces (not shown) on the flexible PCB  180  to a controller  116  on the circuit board  110 , said controller of which manages the capacitive sensing electrodes. The common-tied ground electrodes  130 AG, 130 BG, 140 G are also, as a group, electrically coupled by traces either to the controller  116  or simply to the overall circuit ground. 
         [0036]    In some embodiments (not shown), ground planes may be formed on the opposing layer of the flexible PCB to further isolate the electrodes from electrical noise generated by the stylus. 
         [0037]    By forming these regions on the same flexible PCB  180  but in different regions  180 R 1 , 180 R 2  of the flexible PCB  180 , costs are reduced and assembly is simplified. 
         [0038]    Referring now to  FIGS. 4-7 , in some embodiments, positioning the proximity sensor or sensors  130  and slide sensor  140  against an interior surface of the stylus barrel  10  is performed by a novel three-dimensional wrapping of the flexible PCB  180  around the chassis  120 . The flexible PCB  180  is attached to the circuit board  110  both mechanically and electrically, with the contact pads (not shown) for the traces leading to the electrodes of the proximity sensor or sensors  130  and the slide sensor  140  soldered or otherwise electrically coupled to the appropriate contact pads (not shown) on the circuit board  110 . The chassis  120  may be formed of two parts, upper chassis  120 A and lower chassis  120 B. The upper chassis  120 A and lower chassis  120 B sandwich the assembled combination of the circuit board  110  and flexible PCB  180 . 
         [0039]    The region  180 R 2  is wrapped around the lower chassis  120 B such that the layer  182 L is positioned proximally to the lower chassis  120 B and the layer  181 L is positioned proximally to the barrel  10  of the stylus  1 . 
         [0040]    The region  180 R 1  is wrapped around the upper chassis  120 A such that the layer  181 L is positioned proximally to the upper chassis  120 A and the layer  182 L is positioned proximally to the barrel  10  of the stylus  1 . 
         [0041]    Optionally, adhesive applied to the flexible PCB  180  on at least the edges of the sensor regions, holds the wrapped portions to the chassis  120  for ease of assembly and to ensure that the positions of the slide sensor  140  and proximity sensor or sensors  130  are maintained. 
         [0042]    When assembled, the barrel  10  surrounds the chassis  120 , circuit board  110 , slide sensor  140 , and proximity sensor or sensors  130 . A cosmetic button  30  is positioned to protrude through a slot  11  in the barrel  10  and rests against the slide sensor  140 ; in some embodiments, the upper chassis  120 A comprises a hinged segment  121 A such that when the cosmetic button  30  is pressed, it presses the slide sensor  140  portion of the flexible PCB  180  against the hinged segment  121 A and the inward force is applied to a switch  113  (see  FIG. 3 ) on the circuit board  110 ; the hinged segment  121 A may optionally be slightly taller than the chassis  120 A to facilitate its motion. Similar structures are well known in the art and may be substituted. The switch  113  may in some embodiments be a bistate dome switch. The flexible PCB  180  and its conductive layers  181 L, 182 L are protected by the nonconductive cover layers  181 C, 182 C from being damaged. In some embodiments, the barrel  10  is made of a nonconductive material so that the proximity sensor or sensors  130  and slide sensor  140  are not shielded from external capacitive influences. In some embodiments, the barrel  10  is nonmonolithic and may optionally contain conductive materials in areas located away from the proximity sensor or sensors  130  and slide sensor  140 . 
         [0043]    In some embodiments, a plurality of cosmetic buttons  30  and the associated mechanical and electrical components may be used to provide additional button features. 
         [0044]    In some embodiments, the circuit board  110  of the stylus  1  may comprise additional sensors, for example but not limited to a three-axis accelerometer  114 . 
         [0045]    In use, the stylus  1  having a slide sensor  140  may be used in a variety of ways. In communication with a tablet via the communications subcircuit  112 , the stylus transmits data to the tablet including tip force, tip contact, button presses, proximity sensor level or levels, and slide sensor level. In some embodiments, the optional accelerometer data from the optional accelerometer  114  is also transmitted to the tablet. The accelerometer  114  is preferably configured to generate a triplet of the detected force in each axis as a triplet of floating-point numbers in the range [−1,1]. Intermediary software on the tablet, either in the operating system or in a helper application layer or in an application-level API, may use these data to provide a variety of new functions associated with the stylus. 
         [0046]    In some embodiments, the controller  116  is configured to generate a numerical slide position whenever sufficient capacitive load is detected by the slide sensor  140 . In some embodiments, the controller  116  generates a range value for the slide sensor in the range between 0 to 255 inclusive, usually noted as [0,255]. In some embodiments, the controller  116  is configured to generate a separate numerical value for the capacitance level detected by each proximity sensor of the one or more proximity sensors  130 . In some embodiments, the controller generates a range value for each proximity sensor in the range [0,255]. 
         [0047]    There are many use cases for a stylus with slide sensor and proximity sensors. When communicating with an electronic device, even if that device does not have a touchscreen, the slide sensor can be used as a scroll control, and the slide sensor and proximity sensor or sensors and the physical buttons can all be used as inputs. When the electronic device does have a touchscreen, the slide sensor can add a third dimension of control to the X-Y control dimensions of the screen.