Patent Application
20140002358
The content of PCT/ZA2011/000021 is hereby fully incorporated into the present disclosure, without concession.
The invention pertains to user input devices for electronic products, particularly to detection of 2D movement and selection inputs on portable terminals using capacitive sensing.
Presently, compact mobile electronic terminals are taking up an increasing number of functions previously relegated to larger or fixed terminals. It is not uncommon for a human today to use his or her mobile phone to purchase products, browse the internet, communicate, photograph, document, navigate, study etc. This plethora of usable functions has significantly increased the need for compact user input devices that allow effortless navigation and manipulation of objects in the 2D space presented by the mobile terminal display. Two solution types have evolved to address this need. The first is a transparent touchscreen overlaid onto the mobile terminal display, allowing direct navigation and manipulation of the 2D space. However, this solution is costly, and suffers from other drawbacks, such as limited lifetime and forcing users to touch their screens which could lead to unwanted dirt and skin-oil deposits. The second solution type is a compact button-like device, allowing indirect navigation and manipulation. The present state of the art provides these in either optical or mechanical form, as will be discussed below.
As predecessors of present day mobile terminals, laptop and desktop computers used a large variety of user input devices. These included large pressure sensitive tablets with styli, mechanical mice, with a rollerball breaking light beams in the X and Y directions to capture user movement, optical mice which used irregularities in the supporting surface to deflect light in a varying manner according to the user's hand movement, small rollerballs inserted into the keyboard and capacitive touch pads. The latter are still used extensively in laptop computers, and are related to the present invention in some aspects.
In U.S. Pat. Nos. 5,495,077; 5,841,978; 6,188,391; 6,239,389; 7,202,859; 7,532,205; 7,656,392 and 7,821,502 assigned to Synaptics, U.S. Pat. No. 7,821,502 to Atmel and filing 2006/0066/581 by Apple, capacitive track pads are taught that utilize a matrix of orthogonal drive and sense lines or pads, in a 2D pattern. Further, in U.S. Pat. Nos. 7,129,935; 7,218,124; 7,548,073 and 7,692,431, all assigned to Synaptics, capacitive touchpads that utilize a high number of adjacent sense lines are taught. These two types of touchpad typify those found in today's laptop computers. User finger movement is detected by noting sequential capacitance changes, either from crossing to crossing, or along adjacent lines, or pairs of lines, and is unconstrained within the 2D borders of the touchpad. Due to the high number of lines, and associated 10's, as well as parasitic coupling, the method is not applicable to track pads on the order of 10 mm by 10 mm, as required by mobile terminals. It would require very high precision PCB manufacture, at a high cost. In US filing 2006/0244722A1 by Motorola, on a compact optical pointing apparatus and method, it is stated in paragraph [0009], that capacitive track pads need to be several times the width of the user's finger to be effective, and that this drawback has kept them out of handheld terminals at that stage of the art. Further, due to the matrices of orthogonal lines, capacitive touchpads of this type are constrained to rectangular shapes.
In US filing 2009/027573 by Apple, a mutual capacitance touch sensing device that is based on multiple groups of nodes is taught. A node is defined as 2 or more drive electrodes, and 2 or more sense electrodes. User finger movement is detected when capacitance change occurs sequentially from group to group. Therefore, movement detection is constrained by the pattern in which the groups of nodes, or electrodes, have been placed. Unlike the above Synaptics touchpads, a large number of shapes and patterns can be realized, without the rectangular constraint.
With the fast evolution of mobile electronic terminals, a fair amount of mechanical navigation and selection buttons have been contrived. Although these can be low cost, they somewhat constrain user navigation, with some types only allowing movement in the X or Y axis. For webpage browsing, this is not practical. Further, the contacts and mechanical mechanism of the buttons suffer wear and tear, limiting operational life. And protection against environmental ingress is challenging, requiring flexible coverings, which increases cost.
To overcome the ingress problem of mechanical solutions, and provide more unconstrained user navigation and selection, optical track pads have been developed. Crucialtec teaches such compact optical track pads (OTP's) in US filings 2008/0218474 A1 and 2008/0218769 A1. In essence, these devices operate much like extremely compact inverted optical mice. Infrared light is projected via a lens onto the user's finger. Due to skin irregularities, it is reflected back onto a sensor in a particular pattern. If the user finger moves, the pattern detected by the sensor changes. If sequential pattern changes are processed, the movement direction can be discerned. User selection inputs are still detected via mechanical switches in present state of the art modules. Although these devices have been widely deployed in present state of the art mobile phones, they suffer from a number of drawbacks. Considering mobile phone battery life, typical current consumption is high, in the mA range. They are susceptible to infra-red emissions from remote controls, particularly unintended scrolling of a webpage. Some reports of interference caused by sunlight or strong lighting have surfaced. Due to the sensitivity required, extremely high precision optical manufacturing is required, leading to high cost per unit, in some instances more than 3% of the complete bill of materials for the mobile phone. Only dedicated plastic coverings can be used on the track pad, due to the need for infrared permeability, and filtering, with high susceptibility to deep scratches limiting use in rugged applications. The OTP is also sensitive to the color of the user's skin, and its texture. It is also fairly difficult with present state of the art OTP's to detect rolling movements of the user's finger, as opposed to normal swiping movements. Lastly, by using a mechanical switch for selection detection, the problems of ingress and mechanical wear and tear persist.
In a number of prior art 2D navigation sensors a conductive surface spanning the area of sensing is required. Above a screen, such as an LCD, this is typically transparent (e.g. ITO coated glass or PET) which is costly to manufacture. The invention to be disclosed hereafter typically does not require any transparent conductive surface.
The invention presented herein purports to overcome the drawbacks of the above technologies, and is specifically aimed at improving the state of the art of user input devices allowing 2D navigation in mobile and other electronic terminals.
An extremely compact user input device which could allow unconstrained two dimensional (2D) navigation and selection, with dimensions on the order of 2 cm by 2 cm or less, typically the width of a user's finger, and based on highly sensitive capacitive sensing technology, with a minimal number of drive and sense lines and electrodes, is disclosed. Electrodes, in the sense of the disclosed invention, refer to conductive structures that may be used for capacitive sensing, or to make or break connections in an electronic circuit or circuits. An electrode sense pair for projected (or mutual) capacitive measurements is formed by a driver or transmitting electrode or sense plate and a receiver or sensing electrode forming a capacitive coupling that is measured. Specifically, the invention is aimed at mobile electronic terminals such as mobile phones, remote controls, for instance for web based television sets, e-Readers, for example a Kindle™, and gaming consoles, although it must be understood that it is by no means limited to these applications only.
In one embodiment of the invention, it may consist of only four electrode pairs and a projected (mutual) capacitance sensor and controller, with specific firmware being executed. The four pairs may be formed by two electrodes configured as drive electrodes, and two as sense (or receiver) electrodes. Or the electrodes may be constructed in a way to measure all four (or other number) at the same time. The electrodes are typically arranged in an optimum pattern. By alternately sensing the capacitance change between the various combinations of drive and sense electrodes, user finger movement may be detected with very high resolution and stability. The driving and sensing electrodes may be of various configurations or structures such as shown in the drawings. Specifically they may be on a single side of a PCB or on a single side of glass or other transparent material. In the latter cases the electrodes may consist of ITO or a range of other electrically conductive materials. The driving and sensing electrodes may also be dual-sided in construction such as on the two sides of a PCB. Finally the electrodes may be multi-sided such as on the side(s) of a PCB structure and also through the PCB (or material) such as using, for example, the construction of a through hole via to form an electrode. In this embodiment, the method of using a tap or double tap gesture to indicate a selection may be employed, if the touch start and release actions are cleanly handled in the Compact Capacitive Track Pad (CCTP) module. The tap gestures are bound to be well accepted by the market due to user experience on notebook and lap top PC track pads, and should hold several advantages in terms of cost and construction when compared to integrating a tactile or dome switch structure in the CCTP module. This aspect of the invention possibly allows it to overcome the ingress and mechanical wear problems inherent to all other present state of the art mobile phone user input devices, as the CCTP may be completely sealed within the mobile terminal plastics, and might be without any moving parts.
Thus, in one form of the invention, there is provided a capacitive 2D track pad wherein only four projected capacitive sensing electrode pairs are used to determine any parameter from the group comprising speed, direction and distance, of a user touch gesture on a 2D plane, and that allows indirect user navigation in a displayed 2D space on a display terminal.
In a variation of the invention, the above embodiment could be augmented by an inexpensive dome switch or similar structure, underneath the CCTP overlay. However, the dome switch may not only be used to physically make/break an electrical connection, but is rather used in a capacitance measurement configuration to detect the deflection when pressure is exerted on the dome switch or other structure (on top or below) that deflects under pressure. The CCTP may contain an electrode or a plurality of electrodes that are used for capacitance measurement, to detect proximity of the user's finger, or other relevant body parts or members in general. If the CCTP is depressed against for e.g. the dome switch, a capacitance measurement could be used for detection hereof. For example the drive electrode may be contained in the PCB, and the metal of the deflecting structure may be used as the receiver electrode. Once depressed, the distance and capacitance between sense and drive electrodes are altered measurably, and the action is detected. In a variation, the metallic or conductive structure's deflection results in a variation in the capacitive coupling between a pair of projected sensing electrodes on a PCB—(one transmitting and one receiver electrode), in that a metal object is approaching both and this may enable the recognition of a pressure event. Surface capacitance implementation variations on this theme are also possible.
In a variation of the above embodiment of the CCTP invention, the dome switch may be used to break an electrical connection to note user selection, as is typically done with Optical Track Pads (see for example Nokia E72 mobile phone or several circa 2010 Blackberry phones). Therefore capacitance measurements may be used to detect proximity and user navigation with electrodes and firmware as per the first embodiment. To select, the user may depress the CCTP, resulting in electrical contact by the dome switch that may be detected.
In yet another possible embodiment of the invention, the disclosed CUP with dome switch incorporated may be used to detect user body proximity, user navigation, and offer two levels of selection. The electrodes described by the above embodiments may be used to detect user proximity. Once detected, this may be used for example to turn the backlight of an LCD on, or wake the mobile terminal from a power saving state. Here-after, the electrodes and specific firmware described by the above embodiments may be used to measure user navigation of the displayed 2D space, for example a webpage. To enable user selection, two mechanisms may possibly be provided by the CCTP. The first may be a light tap or double tap (touch) of specific nature, but without sufficient pressure to depress the dome switch or similar structure. Capacitive measurements may be used to detect this selection type. The second selection type may be a touch with sufficient pressure to depress the dome switch or other structure that will facilitate a tactile feeling. This selection type may be detected either galvanically, or capacitively, as described above. For example, a user might want to use the first selection mechanism to select a large number of icons within a displayed 2D space. Once all icons are selected, a single harder press on the CCTP could activate the second selection mechanism, resulting in a similar action being applied to all selected icons. This is similar to using a desktop or laptop computer mouse and the CTRL key simultaneously to select multiple icons and then applying one action, with the comfortable difference that only one input device is used at a given time.
In all the above embodiments, a similar increase or decrease in capacitance between all electrodes simultaneously may provide a boundary condition indication that the user is entering, or is about to enter, a selection. During navigation, the user finger moves between electrodes. This typically results in a dissimilar capacitance increase/decrease for the various electrode pairs and combinations. However, if the user is pressing down, or starts to press down, capacitance will typically increase or decrease at a single sensor or group of sensors. This may alert the controller to monitor the following data for a possible selection event, be it via a capacitive or mechanical dome switch. Typically, the above technique requires highly sensitive capacitance measurements, and may be implemented via projected (or mutual) capacitive, or surface capacitive measurement technology. However, this invention is not limited to this technology, and may be applied via any capacitance measurement technique that provides sufficient sensitivity.
The total capacitance measured across all the sensors may also be used as part of the equation to determine relative movement. For example an equal increase in counts across all measurements channels may indicate a stronger touch. A change in touch strength above a certain level (up or down) may be used to inhibit movement detection to reflect beginning and ending of a user gesture.
The disclosed CCTP device may also be used to detect rolling movement of the user's finger, in addition to the normal sliding movement. This will be especially convenient since the user does not need to lift his or her finger off the CCTP surface to register movement. It is important that the user may move the cursor over the full screen through a rolling action and manipulate the cursor position very effectively without lifting his or her finger.
The position of touch as described here is determined through the interpolation of the data as measured between the various electrodes. Typically two electrodes are used for X-direction and two electrodes are used for Y-direction. This relative measurement may create a problem at the boundaries, where it may not be clear that the user's finger has crossed outside the group of electrodes and this may lead to ambiguities in interpreting the data measured. However, it may be possible to create a boundary around the CCTP to remove this uncertainty. This is be done by positioning another sensing electrode structure within close proximity of the existing outer electrodes. This unequally spaced electrode may be shared, i.e. the same channel may be used on more than one side. Furthermore, it may be possible to only pair a single sense electrode, or a single drive electrode with the complementary electrode on the boundary. This will allow the edge of the CCTP to be more accurately detected by monitoring the relative change in measurements of the inner and outer channels per side. The second sensor channel need only be used for boundary determination.
Unlike other state of the art technologies, the invention may provide an extremely compact track pad. For example, it may be possible to realize a CCTP with dimensions between 8 mm by 8 mm to 2 cm by 2 cm, with just four electrodes. Due to capacitive sensing technology used, the disclosed invention may have extremely low power consumption and very low cost. For example, it is common to have CCTP supply currents in the low μA range.
Given the typical materials used by and dimensions of the disclosed invention, manufacturing may be much simpler, with the potential for fairly wide manufacturing tolerance margins. Therefore the disclosed invention might be very cost effective.
Another advantage of the disclosed invention is that it provides a mobile terminal track pad which may be more reliable, as there are few parts, and in some embodiments none, moving, unlike solely mechanical user input devices. It may also be suitable for use in rugged environments, as deep scratches on the track pad covering should not affect it significantly. Further, it may provide a mobile terminal track pad which is unaffected by infrared remotes. It may also be possible, through application of the disclosed invention, to realize a track pad that may work with a large number of inexpensive plastics, of varying thicknesses. Another aspect of the invention is the possibility for scaling. For example, the CCTP may be increased in dimensions by up to a factor of 2, with only a requirement for new firmware.
The disclosed invention also has fair field adjustability, and user selectable sensitivity range, based on proprietary firmware used in the CCTP.
Varying colors or shapes for the cursor, which relays relative position in the displayed 2D space, may be used to indicate various sensing conditions such as specifically—no touch/proximity; proximity detected; touch detected; touch movement detected and hard touch detected (without movement).
The disclosures above may actually enable the measurement or determination of absolute positions as well, offering the advantage of immediate positioning of a cursor or selection.
A further embodiment of the present invention may allow the realization of a low cost joystick that may sense the amount of force a user exerts in a particular direction. If a dielectric or conductive plate is placed above the various electrode pairs of the disclosed CCTP, and is supported mechanically by a flexible member, for example a spring, or compressible/flexible material, and the movement of the joystick tilts said plate to a particular direction, the capacitance of the electrodes should vary measurably according to the tilting angle of said plate. Since a certain amount of force is required to bend or compress the flexible member such that the plate arrives at a specific position, it may be possible to sense not only motion to a specific side, but also the amount of force exerted by the user in that direction.
A further embodiment of the present invention is the realization of a CCTP which may not only allow efficient navigation of a displayed 2D space, but also force dependent 2D navigation. This may assist to overcome the challenge of sensing navigation inputs if the user's finger covers all electrode pairs in an equal manner. By inserting a CCTP module, as taught during the previous discourse, into a section of compressible/flexible material, and realizing additional electrode pairs, which are static in position, on the periphery of the compressible/flexible material, and having conductive strips on the sides of the CCTP module, in juxtaposition to the additional electrode pairs, the force by which the user presses the CCTP module to a given side may be sensed, similar to the manner of the above mentioned joystick. This information may be used to affect the distance and speed of a cursor associated with the track pad on for example a pc or mobile phone display, or in a remote control and TV pair for example. This may have particular application in web enabled TV, or with products such as the Google™ TV type products. As said conductive strip approaches a given electrode pair, the amount of charge sensed changes, resulting in a change in charge transfer counts and capacitance measured. To position the CCTP module at a particular point, a specific amount of force will typically need to be exerted. This may allow determination of the force by which the user is trying to navigate. A higher force level may indicate user agitation, urgency, or other conditions, which may be used to adjust sensitivity, speed with which the cursor moves and other parameters. The construction may also be such that only said conductive strips are positioned on the floating member and the electrode sense pairs are all positioned on the outer member that forms the well that holds said floating member. This will alleviate any connection problems with regards to power and data lines to the floating/moving member. This configuration may further include the downward pressure switching functionality. As such pressure on both horizontal planes (2D) and in a vertical direction (dome structures) can be detected, as well as the tracking and proximity functions.
In another embodiment the disclosed track pad functionality may be combined with a number of tactile type switch functions in a structure such as is typically found on a remote control device for TV's and television decoders with five buttons (north, east, south and west, with OK in the center). The overlay structure (typically a circular ring with a round button in the center, with inscriptions indicating button function) may be placed upon a compressible/flexible layer. This layer will act as a better dielectric than air but still allow the user to effect a “click” effect on the five switches when pressure is exerted at the right position. The switches may function as capacitive switches (as described herein) or conventional switches where electrical contact must be made/broken to indicate switch actions. Said buttons may be located above the electrode pairs of the track pad, or may be located above dedicated additional electrode structures. Such an embodiment may find good application in remote controllers for television sets that have internet browsing abilities, as the increasing number of user actions typically required for such applications are not easily satisfied by the traditional mechanical five button structures, seeing that these only allow fairly constrained navigation of presented 2D spaces.
A benefit that arises from the capability to detect and measure pressure on the floating member of the CCTP in a specific direction is to have dual tracking detection modes. In cases where the user inadvertently covers the full track pad with a finger (typically due to too much pressure) the pressure measurements may provide enough information for the track pad to function seemingly normal.
Thus, according to another aspect of the invention there is provided a capacitive measurement track pad system using surface and/or projected capacitive measurement methods implemented in a single integrated circuit to recognize proximity detection or touch detection events in multiple electrodes or electrode pairs, as well as events related to touch events where more than a predetermined minimum pressure is applied to a structure causing a snap effect, through the capacitive measurement of the structure in the snapped state, wherein the snap can be detected by the user and wherein the capacitive sensing system further offers track pad operation and functionality using the capacitive measurement information from multiple electrodes or multiple electrode pairs related to the movement of the location of the detected event.
Yet another exemplary embodiment of the present invention allows for the integration of a 2D track pad and tactile button key pad or key board, as disclosed by the following. Said track pad employs a number of orthogonal electrodes on a single layer, with bridging connections on a second layer, and uses projected capacitance measurements to track the movement of an engaging probe, which may be a user's finger. For example, the electrodes may be in the form of a number of series connected diamond shapes, with thin, short sections, relative to the diamond shapes, connecting the various diamonds of a specific electrode together. Further, according to the present embodiment, by using a dome switch-like structure to place floating conductive material, said conductive material being either the dome itself, or material attached to the underside of its apex, over the junction of a plurality of said diamonds, a capacitive sensing tactile switch similar to that disclosed by PCT/ZA2011/000021, held by the present inventor, may be realized. If the user depress the dome switch structure beyond a certain point, it will snap or click and the measured mutual capacitance for said junction will typically change abruptly. This characteristic may be used to discern a user switching action that required more than a predetermined minimum pressure. The conductive or non-conductive nature of the dome material may result in either a decrease or an increase in capacitance measured at a electrode pair.
By using a plurality of dome switch-like structures in the above disclosed embodiment, placed over a plurality of electrode junctions, a 2D track pad may be integrated into traditional key pads and key boards, for example T9™ or QWERTY™ types, according to the present invention. The biggest advantage of such an embodiment of the present invention may be that it still offers the user tactile feedback when individual buttons are depressed, but also allows for an realization of a 2D track pad using the upper surface of what was heretofore only considered for use as a key pad or key board. Another advantage may be that the physical mechanism of the buttons is capacitive in nature, implying the same controller may be used for the detection of 2D navigation and button activations of the user. As there are no electrical connections made/broken it is spark free and a good safety mechanism for use in gaseous environments.
In one form of the invention there is provided a 2D capacitive track pad that utilizes a plurality of sensing electrode pairs used for projected capacitance measurements, and with a plurality of conductive dome structures placed over specific junctions of said electrode pairs, where sufficient pressure on said overlay above the dome structures results in a snap or rapid deflection of the dome structures, providing the user with tactile feedback, and resulting in a sudden change in the capacitance measured for a specific electrode pair without making or breaking electrical contact, which can be used to discern a user selection action equivalent to a button activation.
A further exemplary embodiment of the present invention is the incorporation of touch tracking based predictive text entry held by the present art, and sold commercially, for example by Swype™, into an integrated 2D track pad and key board or key pad, as disclosed in the above discourse of the present invention. Such predictive text entry used in conjunction with the present invention may find good application in lower cost mobile electronic terminals, for instance cell phones, which at present only use low cost mechanical button key pads or key boards.
Naturally, an integrated 2D track pad and key pad/key board of the present invention, as disclosed above, is not constrained to the use of only diamond shapes for the realization of electrodes, but may use any other relevant geometric form.
Relevant to all the above mentioned embodiments is the fact that combinations of the listed embodiments, and new embodiments that fall within the sphere/claims of the disclosed invention, may be possible, and the above is by no means intended to limit the scope of the invention, but merely to assist in its disclosure.
The invention is further described by way of examples with reference to the accompanying drawings in which:
The following description of various embodiments, according to the preceding graphical illustrations, is given in an effort to fully disclose the invention, to enable sufficient comprehension by persons skilled in the art of capacitive sensing. However, the scope of the disclosed invention should by no means be limited by said description, and it is possible that a range of other embodiments can be realized that still fall within the claims to be presented hereafter.
To accurately and reliably measure small movements of a user's finger or thumb over a track pad that is smaller than the finger or thumb requires ultra-sensitive measurement technology. However, given the ever decreasing cost of mobile electronic terminals, relative to their processing power and functionality, the required solution needs to be cost effective as well. Therefore, having a high number of electrodes, with inter electrodes distances that does not leave much margin for manufacturing tolerances, and therefore being costly, is not a good option. If one reduces the number of electrodes to negate this drawback, the amount of required sensitivity to still detect the change in capacitance with a high enough resolution to enable use in a 2D track pad becomes increasingly higher. The amount of processing power required also increases significantly, more so if the sensitivity is not high enough.
These factors have combined to withhold compact capacitive track pads from mobile electronic terminals up to the present.
According to the disclosed invention, it may be possible to realize a high resolution compact capacitive track pad that is sufficiently small and cost effective to allow use in mobile electronic terminals, which will greatly improve the art, and challenge status quos.
The invention is based on the fact that an absolute minimal number of electrodes are used within a sufficiently small area, and by their arrangement, the methods by which their mutual capacitance is monitored and processed, and the techniques applied to discern various user actions.
To detect 2D movement of the user's finger 2.1, the difference in projected capacitance change between the various electrode pairs is continuously monitored. For example, if the user's finger moves in a straight vertical line, the change in measured projected capacitance for the two pairs of vertical electrodes 1.2/1.b and 1.4/1.d should be minimal. However, the change in projected capacitance for the two horizontal pairs 1.1/1.a and 1.3/1.c should be quite large. As the user's finger approaches the bottom horizontal electrode pair of 1.3/1.c, the projected capacitance for this pair should decrease significantly, typically reaching a minimum if the user's finger contact point is directly over the pair. At the same time the opposite electrode pair will experience an inverse effect. Conversely, if the user's finger moves in a horizontal direction, the measured projected capacitance for horizontal electrode pairs 1.1/1.a and 1.311.c should stay fairly constant, but projected capacitance for the vertical pairs 1.2/1.b and 1.411.d should change significantly, with the direction of movement determining which pair ends with the lowest capacitance. As such, movement is always accompanied by an opposing change in measured capacitance at opposing electrode pairs.
By alternately (or simultaneously) monitoring the horizontal and vertical electrode pairs, according to the above characteristic change in projected capacitance, it is possible to detect user finger movement with a very high resolution, which may enable accurate navigation of the exemplary 2D space 4.2 displayed by an exemplary mobile electronic terminal 4.1 via a CCTP module 4.3 in
If the user wants to highlight/navigate to discrete icons in a 2D menu, a slightly different, simplified technique may be used. As before, a touch event may first be declared by the CCTP. A starting capacitance value for all electrode pairs is stored. Hereafter, the CCTP may discern between a vertical or horizontal movement through comparison of the capacitance delta for the two groups of electrodes. This may be followed by declaration of a specific direction, left, right, up or down based on the pair with the lowest capacitance value. The starting position or icon may be the previous ending position or icon, when last the 2D menu was accessed, or it may be based on an absolute position detection algorithm.
For example, this may be a two-wire type, using one of the industry de facto protocols such as I2C. Furthermore, all required filtering and digital signal processing of the raw capacitance data may be done within said integrated circuit or may be done on the host microcontroller when only raw data is supplied. With the typical dimensions of these integrated circuits well below that of disclosed CCTP modules, they may be completely integrated within the module.
Once an icon has been highlighted, the user may want to select it, to activate further functions or open a specific item. To this end, the disclosed invention may enable the use of a double tap gesture on the CCTP, using only capacitive sensing. For example, if the controller in the CCTP senses two touch events with projected capacitance values that differ by less than a specific maximum for all four electrode pairs, within a certain period, a double tap gesture is declared and communicated to the hosting mobile electronic terminal. A further criterion for the declaration of a tap/double tap event may be that no movement had to precede the first tap, or both taps (touches), for a certain minimum period of time.
However, according to the disclosed invention, it may also be possible to enable user selection through use of an inexpensive dome switch.
The above may also allow the use of a mixture of projected and surface measurements by the CCTP. The electrodes 3.1 may be deposited with dimensions that allows surface (or self) capacitance measurement. As the user finger approaches the CCTP, surface measurements are used to detect proximity. Once the finger touches the CCTP, a mixture of surface and projected capacitance measurements may be used to detect touches and user navigation. To select, the user may depress the CCTP to activate or snap the dome switch 3.5. In another embodiment the dome switch is connected as a receiver electrode for projected capacitance measurement. Once the dome switch 3.5 is depressed sufficiently to activate it (snap/click), a sudden increase in measured capacitance should result, as the distance between the transmitting electrode 3.1 and the receiver dome switch (as electrode) should decrease quite significantly over a short period. The same can be achieved with a surface capacitance measurement through the dome being grounded for example. The use of this method allows for a feel equivalent to that of a normal electromechanical switch, although no making or breaking of electrical contact is required. This offers advantages in terms of wear and tear in a electromechanical switch as well as robustness against dirt, debris, or humidity for example.
Thus the proximity and/or touch events are used to provide information to a user with regards to specific buttons in close proximity to the user's finger or operating member and/or touched by a user. Also, the touch event with at least a minimum pressure applied through the touch is used to recognize an event equivalent to an electromechanical button switch being pressed.
A significant contribution of the disclosed invention to the state of the art is the ability to use only rolling movement of the user's finger to enable 2D navigation.
Due to the highly sensitive proprietary capacitance measurement technology available on the market, it may be possible to measure a sufficient change in projected capacitance due to finger rolling to allow accurate navigation of the complete 2D space displayed by the hosting mobile electronic terminal.
The disclosed invention may lend itself to implementation using only a single sided PCB material for the electrode pattern. Due to the simplicity of the electrode patterns, it may be possible to easily scale the CCTP module, for example from 5 mm by 5 mm to 20 mm by 20 mm, without significant design changes. These dimensions are given only as example, and not to place upper or lower dimensional limits on the disclosed invention. Indeed, it may be quite possible to realize capacitive track pads with dimensions well above 20 mm by 20 mm, using the simple minimal electrode pattern disclosed. Another advantage of the invention is that it may allow the realization of non-square track pads that can facilitate highly accurate 2D navigation of the complete space available on a mobile electronic terminal display. The art holds many projected capacitance structures that are non-square. However, all of these are used for single point actions, such as selection, or very limited navigation. It may also be possible to incorporate a large number of different electrode types and combinations within the scope of application of the disclosed invention, with good results.
Although the disclosed invention's ability to use only a single layer of deposited electrodes provides a clear cost advantage, it need not be constrained to such a single layer embodiment. As illustrated by
The disclosed invention should also not be constrained to embodiments that have the minimal number of electrodes on the periphery of the CCTP. As
An improved CCTP according the present invention is shown in exemplary manner in
It should further be appreciated that the embodiment exemplified by
It must be noted that in both the joystick implementation and the track pad with directional pressure detection capability, the movement shown in the diagrams may be seen as exaggerated to better illustrate the concept. In fact the finest of deflections can be accurately measured and as such the stiffness against movement may be accommodated in the algorithms to reflect the desired movement of the cursor vs. movement of the floating member.
In the exemplary embodiments as shown in
Essentially the invention requires a construction wherein pressure towards a specific direction can be detected and this information is used to interpret or assist in interpreting the user action in terms of track pad functionality.
In another embodiment as a variation on
The presently disclosed invention also allows for the realization of switching structures that use capacitive measurements to discern a switching action, using the methods disclosed in PCT/ZA2011/000021, filed by the present inventor, and which is incorporated in its entirety into the present disclosure.
By using projected or mutual capacitance measurements, between various combinations of vertical and horizontal electrodes, the position and movement of an engaging probe, for instance a user's finger(s), on the track pad may be discerned, as is well known in the art of capacitive sensing. As is shown, a thin piece of track or otherwise conductive material is typically used to connect the diamond shapes of a given electrode together. Said pieces of track or otherwise conductive material of vertical and horizontal electrodes cross each other at intervals, necessarily without making electrical contact, for example by using vias and more than one layer of conductive material. By nature of the projected capacitance measurements used for such track pads, the most sensitive spots are located where four diamond points are juxtaposed. Therefore, as is known in the art, the resolution of the track pad may typically be improved by increasing the number of vertical and horizontal electrodes per area.
However, one of the drawbacks of track pads is the lack of tactile feedback given to a user, especially during selection actions. According to the present invention, this can be overcome without the need for electrical make/break switches. As shown in the exemplary embodiment of
Naturally, an embodiment as disclosed above, and presented by the example of
In the exemplary embodiment of
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010/09238 | Dec 2010 | ZA | national |
| 2011/08711 | Nov 2011 | ZA | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/ZA2011/000098 | 12/22/2011 | WO | 00 | 9/16/2013 |
