WO2007069167A2

WO2007069167A2 - Conductive rotary touch sensor

Info

Publication number: WO2007069167A2
Application number: PCT/IB2006/054714
Authority: WO
Inventors: Vincentius Paulus Buil
Original assignee: Koninklijke Philips Electronics, N.V.; U.S. Philips Corporation
Priority date: 2005-12-13
Filing date: 2006-12-08
Publication date: 2007-06-21
Also published as: WO2007069167A3

Abstract

A conductive object position detector (200) for indicating a desired user interface task includes a conductive touch sensor (210) and a processor (250). The conductive touch sensor (210) includes first electrodes (212, 320, 520) disposed along a first substantially closed loop, each first electrode (212, 320, 520) being connected to a first supply voltage, and one or more second electrodes (214, 340, 540) disposed proximate the one or more first electrodes (212, 320, 520) and connected to a second supply voltage different from the first supply voltage. The processor (250) is coupled to the conductive touch sensor (210) and is configured to determine position and relative motion information about the conductive object, where the relative motion information is representative of a difference between a first position and second position of the conductive object. At least one of the position and relative motion information indicates the desired user interface task.

Description

CONDUCTIVE ROTARY TOUCH SENSOR

This invention pertains to rotary touch sensors, and in particular, to a conductive rotary touch sensor and a conductive object position detector including the same.

Touch sensors are becoming increasingly popular user input devices. In particular, the growing popularity of small, portable electronic devices, such as MP3 music players, drives the need for compact user input devices. Furthermore, there is a need for such devices that can recognize a variety of human gestures in order to allow a user to navigate a complex user interface which may include pull-out, hierarchical menus. As electronic devices get smaller and smaller, there is an increasing need for smaller and smaller user input devices.

One popular type of small user input device is a capacitive touch ring such as the "click wheel," an example of which is used on the APPLE® IPOD® portable media device. Such capacitive touch rings are a very attractive solution for scrolling, and for setting parameter levels (such as volume, time, etc.). Furthermore, they can be combined with other input possibilities, such as UP, DOWN, LEFT, and RIGHT "touch click" functions for navigating a user interface. FIG. 1 illustrates a capacitive touch ring 100 comprising a series of capacitor electrodes 120 arranged in a circular layout, as marketed by QUANTUM RESEARCH®. The capacitive touch ring 100 operates by detecting capacitance changes created when a human finger comes in close proximity to two or more of capacitor electrodes 120. However, capacitor electrodes 120 used in capacitive touch ring 100 have a lower bound in terms of surface area to be sensitive enough to detect the touch of a human finger.

QUANTUM RESEARCH® advises a minimum width of 12mm for capacitor electrodes 120 in capacitive touch ring 100 while using thin dielectric materials, and a minimum diameter of 6-7mm for capacitor electrodes used in single touch keys. With smaller surface areas the sensitivity and reliability of the touch sensor drops quickly. This limits the miniaturization of touch rings based on this technology.

As an alternative, SYNAPTICS® markets a round capacitive touch pad, available in a 48 x 64mm module, with hard-coded algorithms that can detect circular scrolling motion along its edges. However, the technology used in this round capacitive touch pad is fairly complex and expensive.

Accordingly, it would be desirable to provide a very small touch sensor that could be used as a user interface for small, portable devices, such as USB-stick size MP3 players, watches, or small remote controls. It would also be desirable to provide such a touch sensor that can be made at low cost and without excessive complexity. It would be further desirable to provide an object position detector including such a touch sensor. The present invention is directed to addressing one or more of the preceding concerns.

In one aspect of the invention, a conductive object position detector for indicating a desired user interface task comprises: a conductive touch sensor including, one or more first electrodes disposed along a first substantially closed loop, each first electrode being connected to a first supply voltage, and one or more second electrodes disposed proximate the one or more first electrodes and connected to a second supply voltage different from the first supply voltage; and a processor coupled to said conductive touch sensor, said processor configured to determine position and relative motion information about the conductive object, said relative motion information representative of a difference between a first position and second position of said conductive object, at least one of said position and relative motion information indicating said desired user interface task.

In another aspect of the invention, a conductive touch sensor comprising: one or more first electrodes disposed along a substantially closed loop, each first electrode being connected to a first supply voltage; one or more second electrodes disposed proximate the one or more first electrodes and connected to a second supply voltage; and means for detecting a change in voltage between at least one first electrode and at least one second electrode when a conductive object contacts said at least one first electrode and said at least one second electrode.

Further and other aspects will become evident from the description to follow.

FIG. 1 illustrates a capacitive touch ring;

FIGs. 2A-B are block diagrams of a conductive object position detector including a conductive touch sensor;

FIG. 3 illustrates one embodiment of a conductive touch sensor;

FIG. 4 is a cross-sectional view of the conductive touch sensor of FIG. 3; FIG. 5 illustrates another embodiment of a conductive touch sensor;

FIG. 6 is a cross-sectional view of the conductive touch sensor of FIG. 5;

FIGs. 7A-D illustrate a number of human gestures that may be detected and interpreted by a conductive object position detector.

FIG. 2 A is block diagram of a conductive object position detector 200 including a conductive touch sensor 210 and a processor 250.

Conductive touch sensor 210 includes: a voltage source 205; a first (sensing) electrode 212 connected to a first supply voltage of voltage source 205; a second electrode 214 connected to a second supply voltage of voltage source 205; a resistor 230 connected between first electrode 212 and the first supply voltage of voltage source 205; and a measurement device 240. Beneficially, the first supply voltage is a relatively low DC voltage, and the second supply voltage is ground. Optionally one, or any combination, of voltage source 205, resistor 230, and measurement device 240 can be provided externally to the conductive touch sensor 210. Also optionally, resistor 230 may be connected between second electrode 214 and the second supply voltage of voltage source 205.

Beneficially, conductive touch sensor 210 may include a plurality of first (sensing) electrodes 212, each connected to the first supply voltage. In that case, conductive touch sensor 210 may also include a corresponding plurality of resistors 230 each coupling one of the first electrodes 212 to the first supply voltage. Furthermore, conductive touch sensor 210 may include a plurality of second electrodes 214, each connected to the second supply voltage (e.g., ground).

FIG. 2B shows a block diagram of a portion of conductive touch sensor 210, showing a single first electrode 212 and a single measurement device 240, and wherein the second electrode 214 is connected to ground.

In FIG. 2B, measurement device 240 is a voltage measurement device. However, in general it should be understood that measurement device 240 may either detect a voltage change between first electrode and second electrodes 212 and 214, or may detect a change in a current flowing between electrode 212 and 214 (e.g., from zero current when there is no conductive object such as a human finger extending between first and second electrodes 212 and 214, to some finite current when a conductive object does extend between first and second electrodes 212 and 214), which is functionally equivalent according to Ohm's law. It should also be understood that although FIG. 2B shows measurement device 240 comprising a comprising a differential amplifier, that any convenient and suitable voltage or current measuring device may be used instead.

In a case where conductive touch sensor 210 includes a plurality of first electrodes 212 as discussed above, the circuitry of FIG. 2B may be repeated for each first electrode 212. Alternatively, in the case where multiple first electrodes 212 are employed, a single measurement device 240 may be sequentially switched or toggled between all of the plurality of first electrodes 212. Optionally, a separate dedicated measurement device 240 may be omitted altogether, and measurements instead may be performed by processor 250 together with an analog-to-digital converter.

Another option is the use of a Schmitt Trigger circuit, which converts analog signals to digital signals, e.g. 0 (+/- supply voltage 1) or 1 (+/- supply voltage 2)

Conductive touch sensor 210 operates by detecting the internal resistance of a part of the human body, typically the resistance through a finger that is "connected" between one or more of the first (sensing) electrodes 212 and one or more of the second electrodes 214. In the embodiment of FIG. 2B, this resistance is detected through a voltage divider, using the resistor 230 and measurement device 240 for detecting a change in voltage between one first electrode 212 and one second electrode 214. In particular, when no conductive object 50 (e.g., a human finger) extends between the first electrode 212 and the second electrode 214, then the output voltage of the voltage divider measured by measurement device 240 will be approximately equal to the difference between the second supply voltage and the first supply voltage (e.g., ground). However, when conductive object 50 extends between the first electrode 212 and the second electrode 214, then the voltage measured by measurement device 240 will decrease by the voltage divider effect between conductive object 50 and resistor 230. Accordingly, the touch of a human finger (or other similar conductive object) can then be detected by detecting the voltage change.

A user changes the position and/or relative motion of conductive object (e.g., a human finger) 50 with respect to conductive touch sensor 210 to indicate an instruction to perform a user interface task desired by a user. Meanwhile, processor 250 is coupled to the output of conductive touch sensor 210 to detect the position and/or relative motion of conductive object 50, to interpret the user's gesture, and in response thereto to determine the desired user interface task. To this end, processor 250 receives one or more signals from one or more measurement devices 240 (perhaps through an A/D converter and/or other intervening circuitry) indicating whether conductive object 50 is in contact between one or more first electrodes 212 and a second electrode 214. From this information, processor 250 is configured to determine position and relative motion information for conductive object 50, where the relative motion information represents a difference between a first position and second position of conductive object 50. Processor 250 is further provided with one or more algorithms for interpreting a human gesture from the position and relative motion information of conductive object 50. Optionally, processor 250 may also measure the rate of change, or "speed" of the movement of conductive object 50.

FIG. 3 illustrates one embodiment of a conductive touch sensor 300 that may be used in conductive object position detector 200. Conductive touch sensor 300 includes a plurality of first electrodes 320 and a second electrode 340 separated from first electrodes 320 by a thin partition of insulating material 360. Each of first electrodes 320 is connected to a first supply voltage through a corresponding resistor 230, and second electrode 340 is connected to a second supply voltage (e.g., ground).

In this layout the first and second electrodes 320, 340 are placed in parallel next to each other. First electrodes 320 are disposed along a first substantially closed loop, e.g., a circle. Second electrode 340 is formed in the shape of a second substantially closed loop, and can be placed inside or outside the first substantially closed loop of first electrodes 320. This has the advantage that a very high resolution can be achieved with a very small footprint, as the first electrodes 320 can be placed adjacent to each other, being separated from each other by a thin partition of insulating material 360. Depending on the size of the first electrodes 320 in comparison to a human finger, one or more than one first electrode 320, plus the second (e.g., ground) electrode 340 is touched at a single moment, which allows high precision (angular position) measurement. Beneficially, conductive touch sensor 300 is disposed on a planar surface. In that case, as shown in FIG. 4, first and second electrodes 320, 340 together may have an elevated, half-circular cross-section profile with respect to the planar surface. Of course, other profiles are possible, including a triangular cross-section, a rounded-square, etc. Alternatively, first and second electrodes 320, 340 may be engraved into the surface. Other arrangements are possible which can provide tactile feedback to a user. However, there are some disadvantages to the layout of the conductive touch sensor

300. Due to the layout, a user may only touch either the inner or outer ring of electrodes 320 or 340 with their finger during movements, thereby producing a lower contact quality. Also, as the size of the first electrodes 320 is reduced to increase angular resolution, it becomes more difficult to manufacture.

FIG. 5 shows another embodiment of a conductive touch sensor 500 that may be used in conductive object position detector 200. Conductive touch sensor 500 includes a plurality of first electrodes 520 and a plurality of second electrodes 540. Each of first electrodes 520 is connected to a first supply voltage though a corresponding resistor 230, and second electrode 540 is connected to a second supply voltage (e.g., ground).

In this layout, first and second electrodes 520, 540 are disposed alternatingly along a first substantially closed loop, e.g., a circle, separated from each other by thin insulator material 560. Every first electrode 520 is attached to a separate measurement resistor 230, and may be connected to a separate measurement device 240, as explained above with respect to FIGs. 2A-B.

Beneficially, conductive touch sensor 500 is disposed on a planar surface. In that case, as shown in FIG. 6, each of first and second electrodes 520, 540 may have an elevated, half-circular cross-section profile with respect to the planar surface. Of course as noted above with respect to electrodes 320, 340 in conductive touch sensor 300, other arrangements are also possible. Furthermore, first electrodes 520 beneficially are of such size that a user cannot touch the conductive touch sensor 500 without touching at least one first electrode 520 and one second electrode 540. Conductive touch sensor 500 is a 16 segments layout, which results in an angular resolution of 22.5 degrees. This can easily be extended to a layout having 32 segments or more, or a lower resolution layout (e.g., 8 or 4 segments), depending on the total size and diameter of conductive touch sensor 500. With a higher resolution layout, a finger may touch more than one first electrode 520 at a time. This can be used to even further enhance the measurement resolution.

Conductive object position detector 200 can facilitate various interaction gestures: rotational movements over the electrodes, short touch actions, and prolonged touch actions. FIGs. 7A-D show four types of attractive interactions that are possible with conductive object position detector 200 with a diameter equal to average finger thickness (~12mm). FIG. 7A shows a circular touch movement gesture which is useful for scrolling up and down a list or menu. FIG. 7B shows a 'RIGHT' (or 'UP, 'DOWN', 'LEFT') touch movement gesture. FIG. 7C shows a 'RIGHT' (or 'UP, 'DOWN', 'LEFT') touch click gesture. FIG. 7D shows an 'OK' touch click gesture, indicating acceptance of an optional selection in the user interface. The gestures of FIGs. 7B and 7D are not currently offered with existing capacitive touch sensors, and can be detected through changes in multiple simultaneously touched first electrodes. In the case of FIG. 7B, there is a sequence of many to few touched first electrodes on the right side of the conductive touch sensor. In the case of FIG. 7D, there is a click sequence on at least half of the first electrodes. These events can easily be discriminated by simple algorithms executed by processor 250. While preferred embodiments are disclosed herein, many variations are possible which remain within the concept and scope of the invention. Such variations would become clear to one of ordinary skill in the art after inspection of the specification, drawings and claims herein. The invention therefore is not to be restricted except within the spirit and scope of the appended claims.

Claims

CLAIMS:

1. A conductive object position detector (200) for indicating a desired user interface task, comprising: a conductive touch sensor (210, 300, 500) including, one or more first electrodes (212, 320, 520) disposed along a first substantially closed loop, at least one first electrode (212, 320, 520) being connected to a first supply voltage, and one or more second electrodes (214, 340, 540) disposed proximate the one or more first electrodes (212, 320, 520) and connected to a second supply voltage different from the first supply voltage; and means (250) coupled to said conductive touch sensor for initiating a desired user interface task based on one ore more outputs of the conductive touch sensor (210, 300,

500).

2. The conductive object position detector (200) of claim 1, wherein at least one second electrode (214, 340, 540) is configured in the shape of a second substantially closed loop and is disposed along the first substantially closed loop, being separated from the one or more first electrodes (212, 320, 520) by an insulating material.

3. The conductive object position detector (200) of claim 2, wherein the at least one second electrode (214, 340, 540) configured in the shape of a second substantially closed loop is disposed inside the first substantially closed loop.

4. The conductive object position detector (200) of claim 1, wherein the second supply voltage is a ground voltage.

5. The conductive object position detector (200) of claim 1, wherein the second electrodes (214, 340, 540) are also disposed along the first substantially closed loop, each said second electrode (214, 340, 540) being arranged between a pair of first electrodes (212, 320, 520).

6. The conductive object position detector (200) of claim 1, wherein the first electrodes (212, 320, 520) are connected by a resistor (230) to the first supply voltage, and wherein the second supply voltage is a ground voltage.

7. The conductive object position detector (200) of claim 1, further comprising a measurement device (240, 250) adapted to detect a change in at least one of a voltage and a current between at least one first electrode (212, 320, 520) and at least one second electrode (214, 340, 540) when the conductive object contacts said at least one first electrode (212, 320, 520) and said at least one second electrode (214, 340, 540).

8. The conductive object position detector (200) of claim 1, wherein the means for initiating a desired user interface task is a processor (250).

9. The conductive object position detector (200) of claim 8, wherein said processor (250) is adapted to detect a change in voltage between at least one first electrode (212, 320, 520) and at least one second electrode (214, 340, 540) when the conductive object contacts said at least one first electrode (212, 320, 520) and said at least one second electrode (214, 340, 540).

10. The conductive object position detector (200) of claim 8, wherein when the conductive object is positioned to extend across opposite sides of said first substantially closed loop, said processor (250) is adapted to interpret said positioning as a gesture indicating acceptance of an optional selection in the user interface.

11. The conductive object position detector (200) of claim 8, wherein when the conductive object is positioned at one side of said first substantially closed loop and moving away from the closed loop, said processor (250) is adapted to interpret said positioning as a gesture indicating a movement in a corresponding direction within the user interface.

12. The conductive object position detector (200) of claim 1, wherein the conductive touch sensor (210, 300, 500) is disposed on a substantially planar surface, and wherein the conductive touch sensor has one of an engraved cross-section profile and an elevated cross-section profile with respect to the planar surface.

13. A conductive touch sensor (210, 300, 500), comprising: one or more first electrodes (212, 320, 520) disposed along a first substantially closed loop, at least one first electrode being connected to a first supply voltage; one or more second electrodes (214, 340, 540) disposed proximate the one or more first electrodes and connected to a second supply voltage different from the first supply voltage; and means (240, 250) for detecting a change in at least one of a voltage and a current between at least one first electrode (212, 320, 520) and at least one second electrode (214, 340, 540) when a conductive object contacts said at least one first electrode (212, 320, 520) and said at least one second electrode (214, 340, 540).

14. The conductive touch sensor (200, 300, 500) of claim 13, wherein the means (240, 250) for detecting a change in voltage between said at least one first electrode (212, 320, 5240) and said at least one second electrode (214, 340, 540) comprises a processor (250).

15. The conductive touch sensor (200, 300, 500) of claim 13, wherein the means (240, 250) for detecting a change in voltage between said at least one first electrode (212, 320, 520) and said at least one second electrode (214, 340, 540) comprises a difference amplifier.

16. The conductive touch sensor (200, 300, 500) of claim 13, wherein at least one second electrode (214, 340, 540) is configured in the shape of a second substantially closed loop and is disposed adjacent to the one or more first electrodes (212, 320, 520) disposed along the first substantially closed loop, being separated from the one or more first electrodes (212, 320, 520) by an insulating material.

17. The conductive touch sensor (200, 300, 500) of claim 16, wherein the at least one second electrode (214, 340, 540) configured in the shape of a second substantially closed loop is disposed inside the first substantially closed loop.

18. The conductive touch sensor (210, 300, 500) of claim 13, wherein the second supply voltage is a ground voltage.

19. The conductive touch sensor (210, 300, 500) of claim 13, wherein the second electrodes (214, 340, 540) are also disposed along the first substantially closed loop, each said second electrode (214, 340, 540) being arranged between a pair of first electrodes (212, 320, 520).

20. The conductive touch sensor (210, 300, 500) of claim 13, wherein the conductive touch sensor (210, 300, 500) is disposed on a substantially planar surface, and wherein the conductive touch sensor (210, 300, 500) has one of an engraved cross-section profile and an elevated cross-section profile with respect to the planar surface.