GB2569945A

GB2569945A - Tip and stylus having the same

Info

Publication number: GB2569945A
Application number: GB1721931.2A
Authority: GB
Inventors: Li Yueh-Hua; Bloem Reinier
Original assignee: Adonit Co Ltd
Current assignee: Adonit Co Ltd
Priority date: 2017-12-27
Filing date: 2017-12-27
Publication date: 2019-07-10
Also published as: GB201721931D0

Abstract

A tip of an active stylus for a capacitive sensor, the tip has first and second electrodes wherein the first electrode 110 has first and second parts, 110A and 110B, parallel with each other and respectively aligned with latitudinal axes B’ and B’’ and wherein one of the parts can be turned off by connecting it to a ground potential. The second electrode 112 is aligned with a longitudinal axis A (see fig 2) of the stylus. The tip further includes a shield 111 between the two electrodes. The first and second electrodes are emitting and sensing electrodes. Parts of the electrodes may have a through hole so that a cable may connect the electrodes to processing circuitry (controller) in the stylus. The stylus may operate with a touchscreen which uses a sensor that can sense a mutual capacitance between the stylus and the touchscreen.

Description

TIP AND STYLUS HAVING THE SAME

BACKGROUND

Field of the Invention [0001] The disclosure relates to a tip and a stylus having the same, and more particularly to a stylus having a tip with multi-part electrodes.

Description of Related Art [0002] Generally speaking, styluses for use with capacitive touchscreens require a minimum level of capacitance between the stylus and the touchscreen for the capacitive sensor in the touchscreen to accurately detect the position of the stylus. Nowadays, most such styluses are passive, having a wide conductive tip that is electrically coupled to the stylus body, such that when the body is gripped by a user, the user is electrically coupled to the tip. This allows the capacitance of the user’s body to be sensed by the touchscreen across a large enough area to simulate a fingertip touch. Touchscreens on many of the most popular devices today require such large touches and capacitances in order to function; contacts by smaller capacitances or across smaller contact regions are ignored by the devices’ firmware in order to reject capacitive noise, thereby helping to lower complexity and cost.

[0003] Precisely locating and“touching”points on a screen is aided by having a stylus with a small, non-deforming tip. Not only does a small tip allow the surrounding screen to be seen by the user, thereby helping the user to position the tip precisely, but also a non-deforming tip means that the firmware will have a consistent contact shape from which to determine the centroid.

[0004] Higher resolution touchscreens exist, but generally require a stylus that is specifically designed to interact with the given touchscreen so that the touchscreen can ignore other touches as noise. This eliminates the user’s ability to use a fingertip to interact with the touchscreen, drastically reducing convenience and requiring that special hardware (the stylus) be developed and kept with the device.

[0005] Touchpad capacitive sensors are designed to require close proximity to avoid accidental touch detection, further limiting their capabilities. For example, custom hardware has been developed by some manufacturers that enable a stylus to be detected at some distance from the screen, thus allowing a touchscreen to display a cursor at an anticipated contact point. But this does not work for standard capacitive touchscreens which are designed to detect the capacitance of a user’s fingertip; instead, special hardware for these touchscreens requires the use of a special stylus, thereby entirely preventing users from using their fingertips.

[0006] However, fine tip active styluses that interact with a capacitive sensor in a touchscreen are susceptible to an offset problem. Therefore, a stylus capable of accurately interacting with a mutual capacitance touch device using a small, non-deformable tip is therefore desirable.

SUMMARY OF CERTAIN ASPECTS OF THE EMBODIMENTS

[0007] In one aspect, embodiments of the invention provide a tip of a stylus for a capacitive sensor. The tip includes a first electrode, a second electrode, and a shield.

The first electrode has a first part aligned with a first latitudinal axis of the stylus, and a second part disposed above the first part of the first electrode and aligned with a second latitudinal axis of the stylus, in which the first latitudinal axis and the second latitudinal axis are parallel with each other. The second electrode is aligned with a longitudinal axis of the stylus, the longitudinal axis being parallel with a central axis of the stylus. The shield is disposed between the first electrode and the second electrode.

[0008] According to an embodiment of the invention, one of the first part or the second part of the first electrode is turned off by coupling to a ground potential.

[0009] According to an embodiment of the invention, the second part of the first electrode has a through hole, the through hole having a longitudinal axis in parallel with the central axis of the stylus.

[00010] According to an embodiment of the invention, a cable is inserted in the through hole and electrically coupled to the second electrode, and a signal received from the capacitive sensor is transmitted from the second electrode to a processing circuit in the stylus through the cable.

[00011] According to an embodiment of the invention, the cable has an outer portion that is electrically grounded.

[00012] According to an embodiment of the invention, the shield separates the first electrode from the second electrode, and the shield is grounded.

[00013] According to an embodiment of the invention, the first part and the second part of the first electrode are selectively turned on by floating the first part or the second part of the first electrode.

[00014] According to an embodiment of the invention, the first and second parts of the first electrode and the second electrode form a segmented rectangular shape.

[00015] According to an embodiment of the invention, the first and second parts of the first electrode form a segmented pie shape with the second electrode.

[00016] In another aspect of the invention, embodiments of the invention provide a stylus for a capacitive sensor, the stylus including a stylus body, an amplifier circuit, a tip, and a power source. The tip includes a first electrode, a second electrode, and a shield. The first electrode has a first part aligned with a first latitudinal axis of the stylus, and a second part is disposed above the first part of the first electrode and aligned with a second latitudinal axis of the stylus, in which the first latitudinal axis and the second latitudinal axis are parallel with each other. The second electrode is aligned with a longitudinal axis of the stylus, the longitudinal axis being parallel with a central axis of the stylus. The shield is disposed between the first electrode and the second electrode. The power source is electrically coupled to the amplifier circuit.

[00017] According to an embodiment of the invention, one of the first part or the second part of the first electrode is turned off by coupling to a ground potential.

[00018] According to an embodiment of the invention, the second part of the first electrode has a through hole, the through hole having a longitudinal axis in parallel with the central axis of the stylus.

[00019] According to an embodiment of the invention, a cable is inserted in the through hole and electrically coupled to the second electrode, and a signal received from the capacitive sensor is transmitted from the second electrode to a processing circuit in the stylus through the cable.

[00020] According to an embodiment of the invention, the cable has an outer portion that is electrically grounded.

[00021] According to an embodiment of the invention, the shield separates the first electrode from the second electrode, and the shield is grounded.

[00022] According to an embodiment of the invention, the first part and the second part of the first electrode are selectively turned on by floating the first part or the second part of the first electrode.

[00023] According to an embodiment of the invention, the first and second parts of the first electrode and the second electrode form a segmented rectangular shape.

[00024] According to an embodiment of the invention, the first and second parts of the first electrode form a segmented pie shape with the second electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

[00025] FIG. 1 is a perspective view of a stylus and a touchscreen according to an embodiment of the invention.

[00026] FIG. 2 is an orthogonal view of a tip for an active stylus according to an embodiment of the invention.

[00027] FIG. 3 is a cross-sectional view of the tip depicted in FIG. 2 across the plane of line AA.

[00028] FIG. 4 is a perspective view of an emitting electrode according to an embodiment of the invention.

[00029] FIG. 5 is a perspective view of a shield according to an embodiment of the invention.

[00030] FIG. 6 is a perspective view of a sensing electrode according to an embodiment of the invention.

[00031] FIG. 7 is a cross-sectional view of another tip configuration along the plane of line AA depicted in FIG. 2.

[00032] FIG. 8 is a bottom view of the anodized sensor/emitter tip depicted in FIG. 7. [00033] FIG. 9 A is a bottom view of the emitting electrode and sensing electrode of a tip from a stylus according to an embodiment of the invention.

[00034] FIG. 9B is a bottom view of the emitting electrode and sensing electrode of another tip from a stylus according to an embodiment of the invention.

DESCRIPTION OF THE EMBODIMENTS

[00035] The following detailed description of embodiments references the accompanying drawings that form a part hereof, in which are shown various illustrative embodiments through which the invention may be practiced. In the drawings, like reference numbers indicate like features or functionally identical steps. 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.

[00036] Please refer to FIG. 1, which is a perspective view of a stylus 100 and a touchscreen 1 according to an embodiment of the invention. In the present embodiment, the stylus 100 includes a tip 10, a body 11, a fairing 12, an emitting electrode 110, a sensing electrode 112, and a shield 111. A printed circuit board 20 and a battery 30 depicted as dashed outlines may be housed inside the body 11. The body 11 may be attached into the fairing 12 of the stylus 100. In the present embodiment, the printed circuit board 20 may include all circuitry necessary to implement the various electronic functions of the stylus 100, including a battery charging circuit, an amplifier circuit, and a power source circuit coupled to the amplifier circuit, a communication module for communicating with the touchscreen 1, a power switch, and so forth, although the invention is not limited thereto.

[00037] Moreover, an input terminal of the amplifier circuit may be electrically coupled to the sensing electrode 112 of the tip, and an output terminal of the circuit may be electrically coupled to the emitting electrode 110 of the tip. The amplifier circuit may receive a signal through the sensing electrode, amplify and inverts the signal, and output the signal through the emitting electrode 110 to the touchscreen 1. Furthermore, the amplifier circuit may amplify only a portion of the signal that exceeds a threshold voltage. For example, the amplifier circuit may modify amplification of the signal according to information received from the device through the communication module in the printed circuit board 20.

[00038] In a passive capacitive stylus, the stylus body may serve to electrically couple a conductive tip to the user’s hand. On the other hand, an active stylus does not necessarily need to use the stylus body to couple the conductive tip to the hand, and therefore the active stylus may be made of either conductive or nonconductive materials, or a combination thereof. In the present embodiment, the body 11 of the stylus 100 may serve to hold the tip 10 and to contain active electronic circuitry 20 and the battery' 30 for powering the active electronic circuitry 20. In FIG. 1, the tip 10 may be an anodized sensor/emitter tip, for example, although the invention is not limited thereto. The shield 111 may separate the emitting electrode 110 and the sensing electrode 112. The touchscreen 1 may be any type of touchscreen containing a sensor capable of sensing a mutual capacitance between the stylus 100 and the touchscreen 1. For example, the touchscreen 1 may include a capacitive sensor having a plurality of driving lines and a plurality of sensing lines (not shown) for sensing the mutual capacitance the stylus 100 and the touchscreen 1.

[0039] Please refer to FIG. 2, an orthogonal view of an embodiment of an anodized sensor/emitter tip, in combination with FIG. 3, a cross-sectional view of the anodized sensor/emitter tip depicted in FIG. 2 for an active stylus across the plane of a line A-A. The tip 100 comprises two electrodes, an emitting electrode 110 and a sensing electrode 112, separated by a shield 111. In the present embodiment, the emitting electrode 110 includes a first part 110A and a second part 110B. The first part 110A is aligned with a first latitudinal axis B’, and the second part 11 OB of the emitting electrode 110 is disposed above the first part 110A and aligned with a second latitudinal axis B”. The first latitudinal axis B’ and the second latitudinal axis B” are parallel with each other, although other embodiments of the invention are not limited thereto. The tip 100 may be substantially radially symmetrical around a longitudinal axis A of the stylus 100; in particular, the emitting electrode 110 including the first part 110A and the second part 110B, the sensing electrode 112, and the shield 111 may be symmetrical around their respective longitudinal axes (which are congruent to the longitudinal axis A of the stylus 100 itself when assembled) in order to present a consistent capacitive signature to a touchscreen regardless of the rotational orientation at which the stylus is held during use. In one embodiment, the first part 110A of the emitting electrode 110 is turned on and the second part 110B is floated to provide a suitably large capacitive signature to the touchscreen 1. In another embodiment, one of the first part 110A or the second part 110B of the emitting electrode 110 may be turned off by coupling to a ground potential, such as for use with a touchscreen 1 that does not require a large capacitive signature. [0040] All three layers 110, 111, 112 are conductive, and so must be electrically insulated from each other. Some embodiments of the invention may use a pair of electrically insulating layers (not shown), for example of a nonconductive polymer, one between the shield 111 and the emitting electrode 110, and one between the shield 111 and the sensing electrode 112, to electrically isolate the three layers. Other embodiments may anodize one, two, or all three of the layers 110, 111, and 112, so that the anodizing serves as electrical insulation, thereby eliminating the additional layers. One way of doing this is to anodize at least the shield 111 with a layer of anodizing (aluminum oxide) sufficient to prevent electrical conductivity between the layers; the emitting electrode 110 and sensing electrode 112 may optionally also be anodized. Alternately, the emitting electrode 110 and sensing electrode 112 are anodized, in which case the shield 111 may optionally also be anodized. Anodizing may serve as insulation when sufficiently thick; a layer of anodizing (Type II or Type III) of 0.0002 inches or greater is sufficient for the voltages involved. And yet in another embodiment, the electrically insulating layers may be an air gap between the shield 111 and the emitting electrode 110, and between the shield 111 and the sensing electrode 112.

[0041] As shown in FIG. 4, FIG. 5, and FIG. 6, a flange 11 IF at the proximal end of the shield 111 is located between and therefore isolates the proximal edge 11 OP of the emitting electrode 110 from the distal face 112D of the sensing electrode 112.

[0042] The sensing electrode 112 may be formed of a conductive material such as a metal or metal alloy, conductive polymer, or conductive shell formed over a polymer. The proximal surface 112P of the sensing tip 112 may be in the form of a spherical cap, paraboloid, one sheet of a hyperboloid of two sheets, or a similar smoothly curved surface. In some embodiments, the sensing tip 112 is electrically connected to a center conductor 121 of a coaxial cable 120; the sensing tip 112 may be set closely against the dielectric 122. In some embodiments, the sensing electrode 112 is formed of solder that is melted onto the center conductor 121 of the coaxial cable 120 and is then molded into an appropriate shape as listed above. In other embodiments, the sensing electrode 112 is formed of a conductive metal such as copper, aluminum, steel, etc., and then soldered, brazed, welded, press-fitted, staked, or otherwise electrically and mechanically connected to the center conductor 121. The shielding conductor 123 (which may be braided, foil, or both) of the coaxial cable 120 is electrically connected to the shield 111 to extend the shielding layer at least past the emitting electrode 110 and in some embodiments to substantially near the PCB (not shown). The shield 111 may have an outer diameter substantially similar to the outer diameter of the coaxial cable 120, and an inner diameter substantially similar to the outer diameter of the coaxial cable’s dielectric layer 122. The emitting electrode 110 has a central axis hole of substantially the same diameter as the coaxial cable 120, thereby allowing the emitting electrode 110 to slide over an outer sheath 124 of the coaxial cable 120. The center conductor 121 of the coaxial cable 120 is electrically coupled to the printed circuit board (not shown), the shielding conductor 123 of the coaxial cable 120 is electrically coupled to ground on the printed circuit board (not shown), and the emitting electrode 110 is electrically coupled to the printed circuit board (not shown) with a wire (not shown).

[0043] Referring to FIG. 4 in combination with FIG. 3, the emitting electrode 110 may be a right circular conical frustum having a cylindrical hole, axially aligned with the axis of the conic frustum and of a size to fit closely around the coaxial cable 120 and the shield 111, through the center. An optional flange 110F at the distal end may be used to align and stabilize the emitting electrode 110 in the fairing 12 when assembled.

[0044] Referring now to FIG. 5 in combination with FIG. 3, the shield 111 may be a hollow cylinder having a flange 11 ID on one end, the flange 11 IF being wide enough to electrically isolate the emitting electrode 110 from the sensing electrode 112, for example by having its widest diameter be as wide as the proximal end of the emitting electrode 110. The shield 111 is formed of a conductive material, and in some embodiments is anodized aluminum, although the invention is not limited thereto. The shield 111 may have a first segment in which the central hole is of a diameter to admit the dielectric 122 of the coaxial cable 120, and a second segment in which the central hole is of a diameter to admit a shielding layer 123 of the coaxial cable. The shield 111 is electrically coupled to the shielding layer 123 of the coaxial cable 120.

[0045] To assemble the anodized tip 100, the coaxial cable 120 may have its outer insulating layer 124 stripped, a lower portion of the shielding layer 123 stripped, and a short segment of the dielectric 122 removed, leaving a short segment of the center conductor 121 exposed. The shield 111 may then be slipped over the end of the coaxial cable 120 until the distal end of the shield 111 abuts the insulating layer 124 of the coaxial cable 120, and the shielding layer 123 may then be electrically coupled to the shield 111. The sensing tip 112 may then be attached to or formed upon the center conductor 121 such that the sensing tip’s distal surface 112d abuts the flange 11 IF of the shield 111. The emitting electrode 110 may then be slid down over the coaxial cable 120 to rest on the shield 111 and abut the flange 11 IF. The coaxial cable 120 may then be slid into the fairing 12 until the distal surface 110D of the emitting electrode 110 abuts the fairing 12 and the flange 110G rests inside a receiving portion of the fairing 12. The center conductor 121 may then be connected to the sensing electrode pad (not shown) on the PCB (not shown), the shielding layer 122 may be connected to ground (not shown) on the PCB (not shown), and the emitting electrode 110 may be connected to the emitting electrode pad (not shown) on the PCB (not shown) using, for example, a wire (not shown).

[0046] FIG. 7 is a cross-sectional view of another anodized sensor/emitter tip configuration along the plane of line A-A depicted in FIG. 2. FIG. 8 is a bottom view of the anodized sensor/emitter tip depicted in FIG. 7. With reference to FIG. 7 and FIG. 8, a tip 500 includes a first part 210A and a second part 21 OB of an emitting electrode 210, a shield 211, and a sensing electrode 212. The tip 500 of FIG. 7 includes a first part 210A of an emitting electrode 210 aligned with a latitudinal axis C’ of the stylus, and a second part 210B disposed above the first part of the first electrode and aligned with a latitudinal axis C” of the stylus, wherein the latitudinal axis C’ and the latitudinal axis C” are parallel with each other. In the present embodiment, the sensing electrode 212 is aligned with the center axis A of the stylus 100, although in other embodiments, the sensing electrode 212 may be aligned with another longitudinal axis that is parallel with the central axis A of the stylus 100. A shield 211 is disposed between the emitting electrode 210 and the sensing electrode 212. A difference between the tip 10 shown in FIG. 2 and the tip 500 shown in FIG. 7 is that, in the present embodiment, the second part 210B of the emitting electrode 210 has a through hole 230. The through hole 230 has a longitudinal axis D in parallel with the central axis A of the stylus 100. In the present embodiment, a cable 220 may be inserted in the through hole 230 and have a center conductor 221 electrically coupled to the sensing electrode 212. In the present embodiment, a signal received from a capacitive sensor on touchscreen 1, for example, may be transmitted from the sensing electrode 212 to a processing circuit in the stylus 100 through the cable 220. In some embodiments, the cable 220 has an outer portion 231 that is electrically grounded. Moreover, the shield 211 may separate the emitting electrode 210 from the sensing electrode 212, and the shield 211 is electrically grounded. As in the tip 10 of FIG. 2, the first part 210A and the second part 210B of the emitting electrode 210 may be selectively turned on by floating the first part 210A or the second part 21 OB of the emitting electrode 210, and one of the first part 210A or the second part 21 OB of the emitting electrode 210 may be turned off by coupling to a ground potential.

[0047] It should be noted that, in some embodiments of the invention, the configuration of the emitting electrode and the sensing electrode may be alternated. That is, the emitting electrode may be configured in the location of the sensing electrode 112 or the sensing electrode 212, and the sensing electrode may be configured to have two parts, such as for the emitting electrode 110 and the emitting electrode 210. Moreover, the configuration of the emitting electrode and the sensing electrode is not limited by those described in the disclosure. For example, FIG. 9A is a bottom view of the emitting electrode and sensing electrode of a tip from a stylus according to an embodiment of the invention, and FIG. 9B is a bottom view of the emitting electrode and sensing electrode of another tip from a stylus according to an embodiment of the invention. With reference to FIG. 9 A, in the tip 800, the first and second parts 310A and 310B of the emitting electrode 310 and the first and second parts 312A and 312B of the sensing electrode 312 may form a segmented pie shape. A grounded shield 311 may be disposed between the emitting electrode 310 and the sensing electrode 312. With reference to FIG. 9B, in the tip 900, the first and second parts 410A and 410B of the emitting electrode 410 and the first and second parts 412A and 412B of the sensing electrode 412 form a segmented rectangular shape. A grounded shield 411 may be disposed between the emitting electrode 410 and the sensing electrode 412. It should be appreciated that, the shape of the emitting electrode and the sensing electrode is not limited to the configurations shown in the disclosure, and other suitable shapes or configurations may be used.

[00048] It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the disclosed embodiments without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the invention covers modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.

Claims

1. A tip of a stylus for a capacitive sensor, the tip comprising: a first electrode having a first part aligned with a first latitudinal axis of the stylus, and a second part disposed above the first part of the first electrode and aligned with a second latitudinal axis of the stylus, wherein the first latitudinal axis and the second latitudinal axis are parallel with each other, wherein one of the first part or the second part can be turned off by coupling to a ground potential; a second electrode aligned with a longitudinal axis of the stylus, the longitudinal axis being parallel with a central axis of the stylus; and a shield disposed between the first electrode and the second electrode, wherein the shield is electrically insulated from the emitting electrode and the sensing electrode, respectively.

2. The tip of claim 1, the second part of the first electrode having a through hole, the through hole having a longitudinal axis in parallel with the central axis of the stylus.

3. The tip of claim 2, wherein a cable is inserted in the through hole and electrically coupled to the second electrode, and a signal received from the capacitive sensor is transmitted from the second electrode to a processing circuit in the stylus through the cable.

4. The tip of claim 3, wherein the cable has an outer portion that is electrically grounded.

5. The tip of claim 1, wherein the shield separates the first electrode from the second electrode, and the shield is grounded.

6. The tip of claim 1, wherein the first part and the second part of the first electrode are selectively turned on by floating the first part or the second part of the first electrode.

7. The tip of claim 1, wherein the first and second parts of the first electrode and the second electrode form a segmented rectangular shape.

8. The tip of claim 1, wherein the first and second parts of the first electrode form a segmented pie shape with the second electrode.

9. The tip of claim 1, wherein an air gap is provided between the shield and the emitting electrode, and between the shield and the sensing electrode.

10. A stylus for a capacitive sensor, the stylus comprising: a stylus body; an amplifier circuit; a tip, comprising: a first electrode having a first part aligned with a first latitudinal axis of the stylus, and a second part disposed above the first part of the first electrode and aligned with a second latitudinal axis of the stylus, wherein the first latitudinal axis and the second latitudinal axis are parallel with each other, wherein one of the first part or the second part can be turned off by coupling to a ground potential; a second electrode aligned with a longitudinal axis of the stylus, the longitudinal axis being parallel with a central axis of the stylus; and a shield disposed between the first electrode and the second electrode; and a power source, the power source electrically coupled to the amplifier circuit, wherein the shield is electrically insulated from the emitting electrode and the sensing electrode, respectively.

11. The stylus of claim 10, the second part of the first electrode having a through hole, the through hole having a longitudinal axis in parallel with the central axis of the stylus.

12. The stylus of claim 11, wherein a cable is inserted in the through hole and electrically coupled to the second electrode, and a signal received from the capacitive sensor is transmitted from the second electrode to a processing circuit in the stylus through the cable.

13. The stylus of claim 12, wherein the cable has an outer portion that is electrically grounded.

14. The stylus of claim 10, wherein the shield separates the first electrode from the second electrode, and the shield is grounded.

15. The stylus of claim 10, wherein the first part and the second part of the first electrode are selectively turned on by floating the first part or the second part of the first electrode.

16. The stylus of claim 10, wherein the first and second parts of the first electrode and the second electrode form a segmented rectangular shape.

17. The stylus of claim 10, wherein the first and second parts of the first electrode form a segmented pie shape with the second electrode.

18. The tip of claim 10, wherein an air gap is provided between the shield and the emitting electrode, and between the shield and the sensing electrode.