Control input device for capacitive touchscreens

Abstract

A control input device for a capacitive touchscreen, a system, and a capacitive touchscreen including the control input device are disclosed, the control input device comprising a base for mounting the device at a predetermined location on the capacitive touchscreen, an actuator, the actuator supported by and electrically insulated from the base, the actuator having a conductive surface and further including an electrode that touches or is adjacent to the capacitive touchscreen when the base is in place, and an electrical circuit between the electrode and the conductive surface, the conductive surface having a surface area selected such that the conductive surface provides a capacitive coupling at or approaching infinity, whereby the capacitive coupling between the electrode and the capacitive touchscreen is detectable by a controller of the capacitive touchscreen, and in use the electrode is configured to undergo a change corresponding to a state of the actuator, and the controller of the touchscreen can determine the state of the actuator from the change in the electrode.

Description

[Technical field]

[0001] The present invention is particularly applicable for use in complex interfaces, and relates to a control input device for a capacitive touch screen where a user may navigate solely or primarily by touch. [Background technology]

[0002] Capacitive touchscreens are an increasingly popular input method for software and computer-based systems across many industries and applications. Capacitive touchscreens offer versatility, ease of operation, and compactness.

[0003] However, for complex operations such as audio mixing, using touch screen controls poses some problems.

[0004] First, manual operation of a touch screen cannot provide the precision of traditional controls such as potentiometers, shaft encoders, linear faders, and electromechanical switches.

[0005] Second, the lack of tactile feedback provided by a touchscreen prevents a user from developing the motor memory essential to enable them to concentrate on a complex task while interacting with a control interface.

[0006] Tactile switches exist for touch screens. Typically, a tactile switch includes an actuator, such as a switch or button, and a sensing electrode. The actuator has a user contact surface that is electrically connected to the electrode. When the actuator is pressed by a user, a circuit is completed, connecting the electrode to the touching finger, which represents ground, generating an input in the receiving software. However, a switch alone provides limited functionality.

[0007] A further area in which it is desirable to use touch screens is in medical and industrial applications. However, here a further complication exists in that such environments may require users to wear protective gloves etc. In such situations, conventional touch screens may not register the touch of a gloved individual adequately or at all. Summary of the Invention [Problem to be solved by the invention]

[0008] It is therefore desirable to provide an alternative input mechanism for touch screens as a means of interaction for complex operations such as audio mixing, particularly one that can provide precision control and tactile feedback. [Means for solving the problem]

[0009] According to one aspect of the present invention, there is provided a control input device for a capacitive touch screen, comprising: a base for mounting a control input device at a predetermined location on the capacitive touch screen; an actuator supported by and electrically insulated from the base, the actuator having a conductive surface and further including an electrode that touches or is adjacent to the capacitive touch screen when the base is in place; an electrical circuit between the electrode and the conductive surface; the conductive surface has a surface area selected such that the conductive surface provides infinite or near infinite capacitive coupling, such that capacitive coupling between the electrode and the capacitive touch screen is detectable by a controller of the capacitive touch screen; A control input device is provided in which, in use, the electrodes are arranged to undergo changes corresponding to a state of an actuator, such that a controller of the capacitive touch screen can determine the state of the actuator from the changes in the electrodes.

[0010] The actuator may include a switched connection whereby a switch is actuated by the actuator.

[0011] Actuation of the switch may be configured to alter an electrical circuit between the electrode and the conductive surface, thereby causing a change.

[0012] The alteration may include severing the conductive surface from the electrode.

[0013] The electrical circuit may include capacitive coupling between the electrode and the conductive surface.

[0014] The electrical circuitry may include optoelectronic components configured to modify the electrical circuitry in response to a received optical signal.

[0015] The actuator may be configured to control exposure of light from the capacitive touchscreen by the optoelectronic component when the control input device is mounted on the capacitive touchscreen.

[0016] The electrodes may change position relative to the capacitive touchscreen surface during operation, and the change in electrode position is detectable by the touchscreen controller.

[0017] The control input device may further comprise a first plurality of electrodes at respective predetermined locations on the capacitive touch screen, the control input device having a second plurality of electrodes arranged in a predetermined pattern, and actuation of the control input device causes a change in the relative positioning of the first and second plurality of electrodes and a corresponding change in capacitance in the first plurality of electrodes that is detectable by a controller of the capacitive touch screen.

[0018] The control input device may be part of a system that includes a look-up table that maps capacitance detected at the first plurality of electrodes to actuator positions, which may also be provided in some other manner accessible to a controller of the capacitive touch screen.

[0019] According to another aspect of the present invention, A controller; a control input device as described herein; a base of the control input device is mounted on the capacitive touch screen, and electrodes of the control input device are configured to create a capacitance at one or more predetermined locations on the capacitive touch screen; A capacitive touch screen is provided, where the controller is configured to scan one or more predetermined locations for a capacitance induced.

[0020] The controller may include control logic for determining the state of the actuator from the resulting capacitance.

[0021] The controller may include control logic for determining the state of the actuator from the resulting capacitance value.

[0022] The controller may include control logic for determining the state of the actuator from the position of capacitance caused on the capacitive touch screen.

[0023] The electrical circuit may simply be a permanent electrical connection between the conductive surface and the electrode (e.g., the slider / fader and knob examples below), it may be a switched connection (e.g., one with a switch that is actuated by actuation of an actuator, such as the push button example below), or some other circuit. Alternatively or additionally, the electrical circuit may include capacitive coupling between the electrode and the conductive surface.

[0024] Embodiments of the present invention seek to provide a high precision control input device for use within the active display / touch area of ​​an LCD, TFT, or other display device, such that graphics and text can be placed immediately adjacent to the control input device and preferably also in the area behind the control input device. Precision in this context spans parameters such as the resolution of actuator movement, smoothness of the tactile sensation, and reliable detection of actuation.

[0025] To provide this precision and solve the problem of tactile feedback through manipulation control objects, embodiments are directed to a physical control input device that can be used with conventional capacitive touch screen devices. Advantageously, these embodiments not only provide tactile feedback, but also allow control input actuation to be detected without the presence of human capacitance through skin contact. This feature means that the control input device can be used by gloved individuals, for example in medical environments.

[0026] The embodiments are directed to a control input device that works when attached to a capacitive touch screen device, but does not require the human body grounding that results from a normal touch. The control input device has conductive surfaces, each with an area such that the conductive surface provides a capacitive coupling to infinity (or close enough to have the effect of being considered as infinity). It will be understood that in an electrical sense, infinity is equivalent to the value of the environmental / surrounding ground potential. Thus, the conductive surface provides the effect of a virtual ground. This virtual ground effect means that it can take the place of human touch (although it still works in the presence of human touch). And the presence of the virtual ground allows a different type of control input device to be implemented that uses a capacitive touch screen to signal actuation (but does not require the human touch that prior art approaches require).

[0027] Examples of control input devices are described below.

[0028] In one embodiment, the virtual ground is electrically connected by an electrical circuit to an electrode that changes position during actuation of a control input device (e.g., sliding a slider, turning a knob), and that change in position is detectable by the touch screen.

[0029] The use of a virtual ground means that the control input device can work with or without a human body ground, thus greatly expanding the field of use, including medical and industrial applications where two-handed ground contact is prohibited / prevented by protective gloves or the like. As the control input device uses a virtual ground instead of a human touch ground, this advantageously means that the conductive surface does not necessarily have to be a surface that the user can touch when operating the device. For example, the push button example below uses a transparent (and potentially non-conductive) material for the main button area so that images from the touch screen etc. are not corrupted. This approach allows the control input device to have a contact area made of a non-conductive material and still be operable. One particular benefit of a conductive surface that is different from the surface touched by the user is that it makes the control operation and the resulting signal less dependent on external factors. Although it is described as a surface, it will be understood that the surface does not have to be exposed and that the encapsulated body has a surface.

[0030] Each electrode of the control input device carries a capacitive charge that is detectable by sensor wiring in the touchscreen, allowing actuation of the control input device, or, if applicable, the position of the control input device, to be detected through the capacitive touchscreen's existing controller.

[0031] Advantageously, the electrodes are configured to undergo a corresponding change in the state of the actuator. For example, the actuator may include a switched connection, where switching of the connection can change the electrical circuit between the electrode and the conductive surface. This can be used to disconnect the conductive surface and change the resulting capacitance, or in some cases, where there are multiple electrodes or the electrode has multiple parts, it can change which part of the electrode gives rise to the capacitance.

[0032] In addition to switching, other changes may include changes to capacitive coupling. The electrical circuit may include, for example, adjustable capacitors or other electronic components that can be set, adjusted, or controlled by manipulation of the actuator or from an external source / signal. In the case of a variable capacitor, for example, the electrodes of the capacitor may be physically moved during some manipulation of the actuator.

[0033] The change in capacitance can be used to improve the resolution of the detection of the induced capacitance by the touchscreen's controller and / or the change in capacitance can be detected separately, either in terms of moving the location of the induced capacitance on the touchscreen, or by actually measuring the induced capacitance by the touchscreen's controller, or by an external analog / digital controller or dedicated touchscreen controller operating in parallel with that of a conventional touchscreen.

[0034] In another advantageous embodiment (which may be combined with the above), the electrical circuitry may include an electronic component such as an optical photodiode or other optoelectronic detector. In such an embodiment, a touch screen may be used to communicate with the optoelectronic component and cause a change in the electrical circuitry (and thus a change to the capacitance caused by the electrodes). It will be appreciated that powering of the electrical circuitry may be via the optoelectronic component instead of or in addition to signal communication.

[0035] In one embodiment, the display may be used as a constant light source. A shutter disk is coupled to the actuator, which causes a rising and falling light beam to be directed towards an optoelectronic component (e.g., a photodiode) to couple the electrodes to or from virtual ground coupling. Multiple electrodes may be used to increase the bus width. In another embodiment, the light from the screen may be directed to a photovoltaic component in an electrical circuit that is used to power a controller that converts the relatively high frequency signal (e.g., >120Hz) of a mechanical quadrature encoder coupled to the actuator movement (e.g., rotation) into a semi-absolute 1-n code that can be communicated from the electrodes, such as those using virtual ground coupling described below.

[0036] In a further advantageous embodiment, in which the features of the embodiments outlined above may be optionally combined, the first plurality of electrodes may be fixed at respective predefined positions on the capacitive touch screen, and the control input device has a second plurality of electrodes arranged in a predefined pattern, which during actuation moves at least partially in alignment with the first plurality of electrodes and out of alignment with the first plurality of electrodes. For example, in the case of a rotary controller, the pattern moves in and out of alignment so that the capacitance caused by the second plurality of electrodes on the control input device can be detected by the touch screen controller via the first plurality of electrodes. The value of the capacitance caused by the various first electrodes depends on the relative position of the pattern, which changes as the controller rotates. A look-up table or the like may be provided, and capacitance values ​​that map to positions may be provided or learned by training and stored in the look-up table. When the touch screen controller needs to determine the position of the control input device, it obtains the capacitance at the first electrodes and obtains the position of the control input device using the look-up table.

[0037] It will further be appreciated that the pattern of second electrodes connected to the conductive surface can be varied by techniques such as those described above, and thus different patterns of active second electrodes can be provided depending on the mode of the control input device as set by the actuator and / or electrical circuitry.

[0038] Modulation of the signal by the touch screen controller may optionally be used to improve coupling and signal detection between the control input device and the touch screen controller, and thereby improve identification of control actuations.

[0039] The embodiments allow capacitive touchscreens to detect actuation without human conduction. This allows actuation with covered hands, e.g., surgical gloves, or through non-conductive objects. In at least selected embodiments, the electrodes physically move relative to the touchscreen surface, so capacitance differences created by non-human components that are optimized for capacitive effects can be seen.

[0040] The capacitance of a conductive sphere of radius r at infinity is C=4πε0r It is.

[0041] For this formula to be valid, it is necessary that the sphere be isolated in space, so that the surrounding field potential falls off in all directions as Φ≈1 / R. The presence of a ground or ground plane anywhere near the sphere violates this condition and adversely affects the capacitance. In this case, it is possible to find an equation for capacitance. The embodiment approximates the capacitance to infinity (ground potential) based on the above formula.

[0042] In a preferred embodiment, the value of the capacitance of the conductive surface is at least on the order of the mutual capacitance of the sensor grid of the touchscreen. For example, for some touchscreens this may be around 0.7 pF. This can be converted to the surface area of ​​a sphere (using the formula above) and the minimum surface area required for the conductive surface can be calculated. For a standard capacitive touchscreen that has been tested, the radius of the sphere is around 5 mm, so the minimum area is around 200 mm. 2 However, it will be appreciated that the capacitance and signal to noise ratio at the time of reading will depend on factors such as the sensitivity of the touch screen controller, the configuration of the sensor grid, etc. Thus, smaller minimum areas are expected, depending on the characteristics of the touch screen used.

[0043] An embodiment applies this principle by incorporating conductive surfaces into control input device components such as knobs, buttons, faders, etc., that have a capacitance to or approaching ground when the control input device is attached to a capacitive touch sensor. A so-called "virtual ground" can replace the body ground of finger contact (but of course still works when finger contact is present).

[0044] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: [Brief description of the drawings]

[0045] [Figure 1] 1 is a schematic diagram illustrating aspects of a control input device according to one embodiment. [Diagram 2] FIG. 1 is a perspective view of a button array, where each button is a control input device, according to one embodiment. [Diagram 3] FIG. 1 is a perspective view of a slider control device according to one embodiment. [Figure 4] FIG. 1 is a perspective view of a rotary control device according to one embodiment. [Diagram 5] FIG. 3 is a diagram of an embodiment based on the control input device of FIG. 2 showing selected features in more detail. [Figure 6] FIG. 3 is a diagram of an embodiment based on the control input device of FIG. 2 showing selected features in more detail. [Figure 7] FIG. 3 is a diagram of an embodiment based on the control input device of FIG. 2 showing selected features in more detail. [Figure 8] FIG. 1 illustrates an embodiment of a button array in which two or more actuation types are housed in a control input device. [Figure 9] FIG. 4 is a diagram of an embodiment based on the slider-type control input device of FIG. 3 showing selected features in more detail. [Figure 10] FIG. 4 is a diagram of an embodiment based on the slider-type control input device of FIG. 3 showing selected features in more detail. [Figure 11a] FIG. 5 is a diagram of an embodiment based on the rotary control input device of FIG. 4. [Figure 11b] FIG. 5 is a diagram of an embodiment based on the rotary control input device of FIG. 4. [Figure 11c] FIG. 5 is a diagram of an embodiment based on the rotary control input device of FIG. 4. [Figure 12a] FIG. 13 illustrates a further embodiment in which multiple electrodes are used to signal the state of an actuator. [Figure 12b] FIG. 13 illustrates a further embodiment in which multiple electrodes are used to signal the state of an actuator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] FIG. 1 is a schematic diagram of a control input device for a capacitive touch screen according to one embodiment.

[0047] The control input device 10 includes a base 20 for mounting the device in a predetermined location on a capacitive touch screen 40 .

[0048] The control input device 10 also includes an actuator 30. The actuator 30 is supported by and electrically insulated from the base 20. The actuator 30 includes a conductive surface 35 and further includes an electrode 36 that touches or is adjacent to a capacitive touch screen 40 when the base 20 is in place.

[0049] An electrical circuit 37 connects the electrodes 36 and the conductive surface 35. The conductive surface 35 has a surface area selected such that the conductive surface 35 provides a capacitive coupling at or approaching infinity. The capacitive coupling between the electrodes 36 and the capacitive touchscreen 40 is detectable by a controller 41 of the capacitive touchscreen. The electrodes 36 are configured to undergo changes that correspond to the state of the actuator 30. The controller 41 of the touchscreen 40 can determine the state of the actuator 30 from the changes to the electrodes 36.

[0050] The control input device 10 can be embodied in many forms, examples of which are illustrated and described in the following embodiments. Furthermore, not only can the form of the control input device vary (rotary, slider, push button, etc. (or a control input device including a combination thereof)), but the effect of the actuator 30 and the operation of the electrical circuitry 37 can also vary between embodiments and / or between variations in the operation of the embodiments. Thus, it will be understood that the following embodiments are merely exemplary, and that other combinations of features beyond those described and illustrated can be realized depending on the desired application of the control input device and the number and type of control inputs that the designer wishes to provide.

[0051] 2 is a perspective view of a button array housed within a common base 20, where each button 30 is a control input device according to one embodiment. Although a single button may be a control input device, it will be appreciated that the control input device can be scaled to incorporate many actuators.

[0052] FIG. 3 is a perspective view of a slider control device that can be used, for example, as a fader.

[0053] 4 is a perspective view of a rotary control according to another embodiment, in which two different control actuators 30a, 30b are combined in a device whose status can be sensed via respective tracks labelled 36a and 36b on the base 20 relative to the touch screen.

[0054] 5-7 are diagrams of an embodiment based on the control input device of FIG. 2 showing selected features in more detail.

[0055] In this embodiment, each control input device is a push button 30. In the illustrated embodiment, the array of buttons are housed together in a common chassis (base) 20. However, they may be individually packaged and used alone.

[0056] As shown in Figure 5, each button has a conductive surface 35 in the form of an actuator frame. The actuator frame 35 is attached to the chassis 20 and provides infinite or near infinite capacitive coupling. An electrical circuit (in this embodiment in the form of a switched connection) connects the actuator frame 35 to an electrode 36 via a switch 37. The electrode 36 is adjacent to or in contact with the touchscreen and is configured to indicate a change in capacitive charge to the touchscreen when the switch is closed by pressing the button.

[0057] When a button is pressed, as shown in Figure 6, a downward force F1 is applied. In this embodiment, each button is suspended within the chassis and includes a bearing 60a, 60b connected to a spring-loaded post 61a, 61b (preferably a bearing and spring-loaded post at each corner of the button). The bearings 60a, 60b and corresponding springs 61a, 61b provide reaction forces F2 and F3, which are directed towards the switch 37, pressing the actuator frame into contact with the electrode 36.

[0058] Advantageously, the bearing and spring-loaded post arrangement ensures that even if the user presses the button off-center, the reaction force still resolves as a downward force on the switch 37 .

[0059] Pressing the button 30 completes a circuit by closing switch 37. This causes a change in capacitance at electrode 36 so that the touchscreen controller can determine the state of the button.

[0060] As shown in FIG. 7, when multiple buttons are provided in an array, the multiple buttons may be connected via connections 35a, so that the multiple buttons share a common conductive surface 35 (frame). Alternatively, the multiple buttons may have separate conductive surfaces 35. The advantage of the common surface 35 is a larger body mass that provides capacitive charging. In one embodiment, the common surface 35 may have a reduced width, etc., to reduce the touchscreen area lost by the frame while simultaneously maintaining sufficient conductive surface area to provide the effect of a virtual ground. As can be seen in FIG. 7, each button has a respective switch 37a-37f so that the actuation of the buttons can be differentiated.

[0061] As highlighted in Figure 8, more than one actuation type may be housed in the control input device. In the illustrated embodiment, the button cap 30 (electrically separate from the frame and the portion pressed by the user) may have a conductive coating or be made of a conductive material. In this embodiment, the button cap has a transparent conductive coating and is connected to a second set of electrodes 71 that are galvanically conductive and can be sensed by the touch screen controller in the same manner as the other electrodes, providing touch sensing independent of the press.

[0062] 9 and 10 are diagrams of the slider-type control input device of FIG. 3 showing selected features in greater detail.

[0063] In this embodiment, the control input device is a slider (also known as a fader) type control device 10. The slider 10 includes an actuator 30 slidably mounted on a chassis (base) 20 (slider rails 21 are part of the chassis 20).

[0064] The actuator 30 is disposed adjacent to the touchscreen and includes an electrode 36 that moves relative to the surface of the touchscreen when the actuator is moved along rails 21 of the chassis 20 .

[0065] As with the push button configuration above, the electrode 36 may be positioned adjacent to or in contact with the touch screen 40. In a preferred embodiment, the actuator 30 in one embodiment may have a body 35 made entirely or partially from aluminum and permanently galvanically connected to the electrode 36. Such a configuration means that touching the aluminum body 35 may be detectable (as the ground signal increases). Furthermore, the position of the slider may be determined by the touch screen controller by the position of the electrode 36. Optionally, the actuator may include a pointer 31 to provide a visual indicator as to its placement.

[0066] For ease of understanding, a connection 37 between the electrode 36 and the body 35 is shown in FIG. 10, however this line is for illustration purposes only and in reality the connection here is between the body 35, the spring 38 (which is also used to hold the actuator on the rail 21) and the electrode 36.

[0067] 11a-11c show diagrams of an embodiment of the rotary control input device of FIG.

[0068] The rotary control input device 10 includes a mounting element (base) 20 for holding the device in place on a capacitive touch screen, and a circuit frame 30 rotatably mounted to the mounting element 20 .

[0069] The circuit frame 30 has a conductive body that is electrically connected to the rotating electrode. In this embodiment, an optional component, the circuit frame is divided into two parts 30a and 30b, both of which are connected to respective (separate) conductive surfaces, each with a surface area selected to provide infinite or near infinite capacitive coupling. The inner body part 30a is conductive in this embodiment, but is galvanically isolated from the outer part 30b by an insulator 31. This allows the rotation and pushing to be sensed separately by the touch screen at the respective electrodes 36a, 36b. In this embodiment, a spring 70a connects the inner part 30a to its electrode 36a, and a corresponding spring 70b connects the outer part to its electrode 36b. As with the previous embodiment, the conductive surface providing a virtual ground means that neither the rotation nor the pushing actuation requires the human ground to be detected at the respective electrodes 36a, 36b.

[0070] In the above embodiment, a single electrode in the capacitive touch screen is used to transmit the state of the actuator, however more complex configurations are possible, as shown in Figures 12a and 12b.

[0071] In this embodiment, the first plurality of electrodes (36a..n, for simplicity of illustration only 36c, 36d and 36e are shown and for further simplicity only 36c and 36d show lines connecting to the touchscreen but all of the first plurality of electrodes are on the touchscreen) are fixed in their respective predefined positions on the capacitive touchscreen 40. The control input device 10 has a second plurality of electrodes 37a..h which are part of an electrical circuit and are arranged in a predefined pattern such that at some point during rotation they are at least partially aligned with the first plurality of electrodes but the alignment of each electrode is different at points during a complete rotation. The pattern is such that as the control input device (here the control input device is a knob type control input device) rotates about its fixed axis of rotation, the second plurality of electrodes rotate in a plane generally parallel to the plane of the touchscreen (and therefore the first plurality of electrodes) and as they rotate they move in and out of alignment with the first plurality of electrodes. The number of first and second electrodes does not have to be the same.

[0072] In this example, the capacitance exhibited by the second plurality of electrodes on the control input device can be detected by the touch screen controller via the first plurality of electrodes. This is illustrated by way of example only in FIG. 12b. Here, it can be seen that the electrodes 36a and 36b are arranged across various cells of the touch screen. The value of the capacitance resulting in the cells corresponding to the electrodes depends on the relative position of the pattern of the second electrodes, which changes as the controller rotates. A look-up table or the like can be provided, and the value of the capacitance mapping to the position can be provided or learned by training and stored in the look-up table. When the touch screen controller 41 needs to determine the position of the control input device, it obtains the capacitance at the first electrode and uses the look-up table to obtain the position of the control input device.

[0073] The illustrated configuration allows an 8-bit Gray code to be used, resolving the positions into 128 unique codes. Such an arrangement may be possible, for example, by using a 20 mm diameter area for the electrodes 36.

[0074] In addition to, or as an alternative to, a lookup table, a learning and / or memory-based system may be used to determine position from the capacitance that occurs. For example, the controller may be told what the capacitances are at various increments around the axis of rotation, and it can track when these occur and infer position from the last known sensed capacitance and, optionally, the degree of capacitance difference compared to the current value.

[0075] It will be further appreciated that the pattern of second electrodes connected to the conductive surface can be varied by approaches such as those described above, and thus different patterns of active second electrodes can be provided depending on the mode of the control input device as set by the actuator and / or electrical circuitry.

[0076] Any embodiment of the present invention may be understood as including the parts, elements, and features referred to or indicated in this specification, either individually, or collectively in any or all combinations of two or more of the parts, elements, or features, where a particular integer is referred to herein, this particular integer has known equivalents in the art to which the present invention pertains, and such known equivalents are deemed to be incorporated herein as if individually set forth.

[0077] Although illustrative embodiments of the present invention have been described, it should be understood that various changes, substitutions, and alterations may be made by those skilled in the art without departing from the invention as defined by the claims set forth below and their equivalents.

Claims

1. A control input device for a capacitive touchscreen, A base for mounting the control input device at a predetermined location on the capacitive touchscreen, An actuator supported by the base and electrically insulated from the base, further comprising an electrode having a conductive surface that touches or is adjacent to the capacitive touchscreen when the base is in a predetermined position, The electrical circuit comprises the electrode and the conductive surface, The conductive surface has a surface area selected such that it provides an infinite or near-infinite capacitive coupling, thereby having a capacitance to or near ground when the control input device is mounted in a predetermined location on the capacitive touchscreen, and the capacitive coupling between the electrode and the capacitive touchscreen is detectable by the controller of the capacitive touchscreen. A control input device in which, during use, the electrode is configured to undergo further changes corresponding to the relative position of the actuator, the change in the relative position of the actuator causes a variable change in capacitance indicated by the conductive surface, thereby enabling the controller of the capacitive touchscreen to determine the relative position of the actuator from the changes in the electrode.

2. The control input device according to claim 1, wherein the actuator includes a switchable connection that is operated by the actuator.

3. The control input device according to claim 2, wherein the operation of the switch is configured to modify the electrical circuit between the electrode and the conductive surface, thereby causing the change.

4. The control input device according to claim 3, wherein the change includes cutting the conductive surface from the electrode.

5. The control input device according to claim 1, wherein the electrical circuit includes a capacitive coupling between the electrode and the conductive surface.

6. The control input device according to claim 1, wherein the electrical circuit includes an optoelectronic component configured to change the electrical circuit in response to a received optical signal.

7. The control input device according to claim 6, wherein the actuator is configured to control the exposure of light from the capacitive touchscreen by the optoelectronic component when the control input device is mounted on the capacitive touchscreen.

8. The control input device according to claim 1, wherein the electrode changes its position relative to the surface of a capacitive touchscreen during operation, and the change in the position of the electrode is detectable by the controller of the capacitive touchscreen.

9. The control input device according to claim 1, further comprising a first plurality of electrodes at predetermined positions on the capacitive touchscreen, wherein the control input device has a second plurality of electrodes arranged in a predetermined pattern, and the operation of the control input device causes a change in the relative arrangement of the first and second plurality of electrodes, and a corresponding change in capacitance in the first plurality of electrodes which can be detected by the controller of the capacitive touchscreen.

10. A control input device system comprising the control input device according to claim 9, further comprising a lookup table for mapping capacitances detected by the first plurality of electrodes to the positions of the actuator.

11. Controller and Includes the control input device described in claim 1, The base of the control input device is mounted on the capacitive touchscreen, and the electrodes of the control input device are configured to generate capacitance at one or more predetermined locations on the capacitive touchscreen. The controller is configured to scan one or more predetermined locations for the generated capacitance, and is a capacitive touchscreen.

12. The capacitive touchscreen according to claim 11, wherein the controller includes control logic for determining the relative position of the actuator from the generated capacitance.

13. The capacitive touchscreen according to claim 11, wherein the controller includes control logic for determining the relative position of the actuator from the generated capacitance value.

14. The capacitive touchscreen according to claim 11, wherein the controller includes control logic for determining the relative position of the actuator from the position of the capacitance generated on the capacitive touchscreen.

15. A control input device for a capacitive touchscreen, A base for mounting the control input device at a predetermined location on the capacitive touchscreen, An actuator supported by the base and electrically insulated from the base, having a conductive surface, movable from one relative position to another relative position with respect to the base, and further including an electrode that touches or is adjacent to the capacitive touchscreen when the base is in a predetermined position, The electrical circuit comprises the electrode and the conductive surface, When the conductive surface of the actuator is mounted at a predetermined position on the capacitive touchscreen, it provides infinite or near-infinite capacitive coupling. A control input device in which the movement of the actuator generates a variable capacitance detectable by the controller of the capacitive touchscreen, thereby determining the position of the movable actuator.

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