WO2003013402A1

WO2003013402A1 - A tongue and jaw operable control apparatus

Info

Publication number: WO2003013402A1
Application number: PCT/AU2002/001045
Authority: WO
Inventors: Kevin Marcus
Original assignee: Divkey Pty Ltd
Priority date: 2001-08-08
Filing date: 2002-08-07
Publication date: 2003-02-20
Also published as: AUPR689101A0

Abstract

A tongue and jaw operable control apparatus (1) incudes an external body or housing and support means in the form of a multifunctional mouth piece. The mouth piece includes a pair of locating elements (4) and a tongue joystick (5), all of which are disposed, in use, to protrude inwardly into the user's mouth. An interface assembly (6), having an inner part (7) and an outer part (8), establishes connection and mechanical interaction between the tongue operable joystick (5) and a direction sensing device (13) mounted within the body of the apparatus. Output means including an infrared transmitter (43) are also provided to allow the apparatus to communicate with a device to be controlled. Preferably, the apparatus provides a 'hands-free' human-computer interface that functions in a manner similar to that of a conventional computer mouse, being particulary suitable for use by computer operators with severe physical disabilities.

Description

A TONGUE AND JAW OPERABLE CONTROL APPARATUS

FIELD OF THE INVENTION

This invention relates to a control apparatus, and more particularly to a hands- free control apparatus which is operable by the mouth and tongue of a user. Accordingly, the invention is suitable, although not limited to, use by physically handicapped people who do not have full use of their hands. The invention is particularly suitable for use by quadriplegics or amputees, or those suffering from severe arthritis.

The invention has been developed primarily for use as a replacement for a conventional mouse, as a means of controlling a personal computer or computer terminal, and will be described predominantly with reference to this application. It will be appreciated, however, that the invention is not limited to this particular field of use. The invention may also, for example, be used as a remote controller for an electric wheel-chair. Alternatively, it might be used to control actions for which the operator would ordinarily use his or her hands, but where the hands are being employed for other purposes. An example of this would be a surgeon performing a medical operation using his hands. The invention could be used in this context, for example, to scroll through a document such as a procedural or instructional manual on a computer, while performing related tasks with the hands. As another example, the invention could be used to allow the usual mouse commands and functions to be carried out by the operator using his or her mouth, leaving the hands free to simultaneously operate the keyboard.

It will therefore be appreciated that the invention in its broad form can be adapted and applied to the control or operation of a wide variety of equipment, ranging from fine manual control, through to the operation of power assisted vehicles and heavy machinery. BACKGROUND OF THE INVENTION

The following discussion of the prior art is intended to present the invention in an appropriate technical context and allow its significance to be properly appreciated. Unless clearly indicated to the contrary, however, reference to any prior art in this specification should not be construed as an admission that such art is widely known or forms part of common general knowledge in the field.

There are numerous known hands-free control devices which are intended as replacements for computer mouses. The devices considered most relevant in this context are those designed for use by physically handicapped people who do not have full use of their hands. A number of such devices are considered below, and each of these is designed to be operated by the mouth and/or tongue.

One known device includes a cylindrical body, a joystick extending from the body, and a cup-shaped tongue-engagement formation at a free end of the joystick. In use, the body is clamped between the operator's lips or front teeth, and the joystick is moved by the operator's tongue, which extends partially into the cup formation. The functionality of the conventional mouse left-click button is achieved by way of forward movement of the operator's tongue, which in turn moves the joystick axially. This device suffers from a number of disadvantages, including that it does not lend itself to be supported in a stable manner during use. This, in turn, results in a poor ability to control the joystick accurately and can result in the operator tiring relatively quickly.

Furthermore, the device does not adequately address issues of hygiene, particularly if the device is required to be used by more than one operator. The device also does not provide for the functionality of the conventional mouse right-click button.

Another known device includes a dental plate on which is supported a small joystick. Mounted on the dental plate is a switch which performs the function of a mouse left-click button and which is operated by pressure applied by the operator's teeth. As the joystick and associated electronic circuitry are, in use, disposed entirely within the operator's mouth, the device suffers from disadvantages associated with both hygiene and safety, because of the fact that moisture in the form of saliva can enter the device. The dental plate, which is custom fitted to a particular operator, may provide adequate stability to allow for accurate control of the joystick, but limits the device to use by that operator. Accordingly, the device is not suitable for mass-production. Furthermore, as in the case of the device described above, this device also does not provide for the operation of a mouse right-click and is therefore severely limited in its functionality.

Yet a further known device includes a frame for mounting onto an operator's head, and a curved stick extending from a side of the frame adjacent the operator's ear, so as to protrude into the operator's mouth. The normal mouse displacement function is achieved by the operator's tongue moving the stick, and the mouse left-click function is achieved by sensors within the stick which are actuated by a biting action. However, in view of the asymmetrical structure of the device, sophisticated electronics are required in order to convert the movement of the stick to a corresponding and proportional displacement of the cursor on the computer screen. Also, the mass of the stick itself can cause unintended movement of the stick and hence "cursor creep" which must also ideally be eliminated using sophisticated computer software. The non-symmetrical configuration of the device also leads to discomfort and diminished "user-friendliness" due to differing sensations and feed-back from the device when moving the stick to opposite sides.

Other known devices are adapted to track the movement of an operator's head or eyes in order to move the cursor on the computer screen. However, the hardware and software for detecting such movements consistently and reliably to the level of accuracy required is particularly sophisticated and hence expensive. In addition, the types of movement in question are not natural movements for an operator and therefore result in negative effects such as operator dizziness and fatigue. Furthermore, it is natural for an operator to look around during use, and any such movements translate into corresponding, inadvertent movements of the cursor.

Other known devices make use of a fixed frame adapted to be secured to a desk or other surface, so as to support a joystick or other control elements at approximately head height, in front of the user, but essentially independently of the user's head. This system provides a relatively stable platform that potentially allows for accurate control. However, because the frame is essentially fixed to the desk, it must be accurately adjusted to suit each user. This in turn dictates a series of relatively expensive adjustment mechanisms, and a relatively time-consuming adjustment procedure, which must be repeated for each new operator. Also, this system does not allow for natural movements of the head while the apparatus is engaged, and therefore leads prematurely to operator discomfort, distraction and muscle fatigue.

Yet other known devices make use of so-called "sip and blow" systems. Such systems typically include a pressure pipe which permits control signals to be generated by the operator alternately sucking or blowing on a mouthpiece in fluid communication with the pipe. These systems suffer from the disadvantage of ingress of saliva to the pipes, with a resulting build-up of bacteria in areas that are difficult to clean. Accordingly these systems tend to be unhygienic, and difficult to transfer safely between different operators. They also tend to be limited in terms of their functionality, due to the restricted number of different command signals that can be readily generated. Furthermore, because of the need for the operator to breathe more or less continuously while using the device, precise control of cursor movements to the level of accuracy required can be difficult to achieve in practice.

It is an object of the present invention to overcome or substantially ameliorate one or more of the disadvantages of the prior art, or at least to provide a useful alternative.

SUMMARY OF THE INVENTION

According to a first aspect, the invention provides a hands-free control apparatus including: a body; first, second, and third control means connected to the body; support means adapted to support the control means adjacent a user's mouth in an operative position in which the first control means are operable by a first control action in the form of lateral and/or vertical movement of the user's tongue, the second control means are operable by a second control action in the form of changing pressure exerted by the user's jaw, and the third control means are operable by a third control action distinct from the first and second actions in the form of movement of part of the user's body above the neck; and output means adapted to generate output control signals corresponding to the respective control actions. Preferably, the first control means include a joystick which in the operative position extends into the user's mouth. The joystick is preferably adapted for lateral and vertical movement in response to corresponding lateral or vertical pressure or displacement imparted by the user's tongue. Most preferably, the joystick is adapted for both lateral and vertical movement about orthogonal axes, thereby in combination to

provide for pivotal movement with two degrees of freedom. Preferably, the remote end of the joystick is operably connected to directional sensor means, which functions as a pressure or displacement transducer, to convert the lateral and vertical displacements of the joystick, and any combinations thereof, into corresponding electronic control signals. In a preferred form of the invention, the directional sensor makes use of an array of conductors etched onto a circuit board. In alternative embodiments, however, strain gauges or other suitable pressure or displacement transducers may be used. It will also be appreciated that in other embodiments, the directional sensor means may take the form of rotational displacement transducers, integrated into a gimbal type mounting or a spherical type universal joint. The joystick preferably has an outwardly rounded contact surface for engaging the user's tongue. Most preferably, the contact surface is substantially spherical in shape, and is defined by a control ball formation disposed on the proximal end of the joystick.

Preferably, the second control means include a pressure actuated "bite switch" adapted to be positioned between the user's teeth, for actuation in response to the second control action in the form of a jaw clenching or biting action.

Preferably the third control means are also associated with the joystick, and the corresponding third control action preferably takes the form of forward axial displacement of the joystick as a result of axial pressure exerted by the user's tongue on the control ball on the proximal end of the joystick.

Preferably, the support means include a mouthpiece configured for positioning in the user's mouth in the operative position, to enable the user securely to support the

apparatus and positively to locate the control means. The mouthpiece preferably includes a pair of protruding locating elements, configured respectively to be positioned between the teeth on opposite sides of the user's mouth in order to stabilise the mouthpiece against inadvertent rotational movement and to facilitate accurate articulation of the control means.

In a preferred embodiment, the mouthpiece includes a front formation configured for positioning between the user's upper and lower front teeth, the locating elements are respectively configured for positioning between the user's upper and lower teeth on opposite sides of the mouth, and the pressure switch is disposed within one of the locating elements. Most preferably, the apparatus includes two such pressure switches, each being located on or in a respective one of the locating elements on the mouthpiece, and both being electrically connected in a parallel circuit. In a preferred embodiment, the mouthpiece includes a moulded silicone skin and the switches are preferably encapsulated within the skin. In this case, the apparatus preferably includes a plunger assembly positioned adjacent each switch, and encapsulated within the skin for actuating the switch when increased gripping or clenching pressure is applied via the user's jaws. Preferably, the output means include an electromc control circuit including a microprocessor disposed within the body, and infrared or other wireless transmission means electrically connected to the control circuit.

The apparatus preferably also includes a power source. Preferably, the power source includes at least one battery, which is preferably a replaceable lithium battery, housed in a battery compartment within the body. Alternatively, it will be appreciated that rechargeable batteries, or a DC power pack connected with an appropriately isolated mains transformer may also be used.

Preferably, the body or housing is adapted to be disposed substantially outside of the user's mouth when the mouthpiece is in the operational position. The apparatus

preferably includes connection means for detachably connecting the mouthpiece to the body so as to permit substitution of alternative mouthpieces, and thereby enable the same body and housing to be readily and hygienically interchanged and shared between multiple users. The body is preferably configured to abut the user's chin in the operative position, to enhance the stability and accuracy of the control mechanisms. The apparatus preferably includes a moisture impermeable barrier in the form of a membrane disposed effectively intermediate the mouthpiece and the body in order substantially to prevent the ingress of moisture emanating from the user's mouth into the electronic control and output circuitry housed within the body.

In a preferred embodiment, the apparatus is adapted to serve as a computer mouse with the first control means performing the function of a conventional mouse track ball, the second control means performing the function of a conventional mouse left-click button, and the third control means performing the function of a conventional mouse right-click button.

According to a second aspect, the invention provides a mouthpiece for a control apparatus as defined above, the mouthpiece forming part of the support means and being configured for positioning in the user's mouth in the operative position, to enable the user securely to support the apparatus and positively to locate the control means.

Preferably, the mouthpiece includes a pair of protruding locating elements, configured respectively to be positioned between the teeth on opposite sides of the user's mouth in order to stabilise the mouthpiece against inadvertent rotational movement and to facilitate accurate articulation of the control means. More preferably, the mouthpiece includes a front formation configured for positioning between the user's upper and lower front teeth, the locating elements are respectively configured for positioning between the user's upper and lower teeth on opposite sides of the mouth, and the pressure switch is disposed within one of the locating elements. In a preferred form, the mouthpiece includes a pressure actuated "bite switch" adapted to be positioned between the user's teeth for actuation in response to a jaw clenching or biting action, the switch being located on or in one of the locating elements on the mouthpiece. More preferably, the mouthpiece includes two of the switches, each being located on or in a respective one of the locating elements on the mouthpiece, and both being electrically connected in a parallel circuit.

In a preferred embodiment, the mouthpiece includes a moulded silicone skin. Preferably, the switch or switches is/are encapsulated within the skin.

Preferably, the mouthpiece includes a plunger assembly positioned adjacent each switch, and encapsulated within the skin for actuating the switch when increased gripping or clenching pressure is applied via the user's jaws. DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a schematic side view of a control apparatus according to the invention held in an operative position by a user;

Figure 2 is a schematic sectional plan view through the control apparatus;

Figure 3 is a schematic side sectional view through part of the apparatus;

Figure 4 is a schematic block diagram showing the circuitry of the apparatus; Figure 5 is a diagrammatic view showing a preferred application of the invention wherein the apparatus held in the operative position by the user in order to control a computer terminal; and

Figure 6 is a perspective view of the joystick of the control apparatus. DETAILED DESCRIPTION

Referring to the drawings, the apparatus 1 includes a body or housing 2 and support means in the form of a mouth piece 3. The mouthpiece 3 includes a pair of locating elements 4 and a joystick 5, all of which are disposed, in use, to protrude inwardly into the user's mouth. An interface assembly 6, having an inner part 7 and an outer part 8, establishes connection and interaction between the mouthpiece and the body, as described in more detailed below.

The proximal or inward end of the joystick 5 has a spherical head 9 defining a smooth, rounded, generally spherical contact surface for comfortable manipulative engagement by the user's tongue. The remote end of the joystick is attached to a stainless steel intermediate support shaft 10, which extends from the base of the joystick into the inner part of the interface assembly 6, though a bush 12. This bush accommodates a limited degree of axial displacement of the support shaft.

The remote end of the joystick support shaft 10 is operably connected, via the interface assembly, to a directional sensor mechanism 13, incorporating a pressure or displacement transducer to convert the lateral and vertical movements of the joystick, and any combinations of such movements, into corresponding electronic control signals.

In the preferred form of the invention as illustrated, the directional sensor mechanism 13 makes use of a two-dimensional array of conductors etched onto an associated circuit board 14. These conductors are spatially arranged for engagement by complementary conducting elements formed in an adjacent pressure pad 15. The pressure pad is rigidly connected to an input control spigot 16, which extends outwardly in a normal orientation from the pressure pad, as best seen in figure 2. By virtue of the intermediate interface assembly, this arrangement is such that the joystick effectively forms an axial extension of the input spigot, with the electrical connections between the conducting elements on the circuit board and the pressure pad reflecting the instantaneous position and direction of the joystick at any given time.

In alternative embodiments, (not shown) strain gauges maybe used as pressure or displacement transducer elements within the directional sensor mechanism. In yet other embodiments, (also not shown) angular displacement transducers may be integrated into a gimbal type mounting or a spherical type universal joint, to generate composite control signals indicative of rotational displacement about a pair of orthogonally oriented control axes.

The mouthpiece 3 has an outer silicone skin 17 substantially encapsulating the various inner components. A flexible resilient diaphragm 18, formed as an integral continuation of the skin, extends continuously between the locating elements 4 and a collar 19 surrounding the base of the joystick. The diaphragm is sufficiently thin and flexible to permit universal movement of the joystick within the intended operating range, while having sufficient thickness to withstand tearing. In this way, the diaphragm resiliently supports the joystick, while also acting as a moisture barrier. Excessive lateral deflection of the joystick, and hence potential damage to the diaphragm, is prevented by the mutually opposing inner surfaces of the locating elements 4.

Between the joystick and the directional sensor, the intermediate support shaft 10, slidably supported by the surrounding bush 12, extends though an aperture 20 for selective axial engagement with a switch 21 mounted on an associated circuit board 22, disposed within the inner part 7 of the interface assembly. This "tongue switch" is thereby activated in response to axial pressure by the user's tongue on the outer contact surface 9 A of the spherical head of the joystick.

The circuit board 22 is supported by a spring 23, which is partly housed within a recess formed in the outer part 8 of the interface assembly. The spring 23 accommodates a degree of movement of the circuit board 22 in the direction of the arrow A, constrained axially by four guide posts 24 extending outwardly from the inner part 7 of the interface assembly. These guide posts extend into respective guide passages 25, which are recessed into the outer part 8 of the interface assembly. In normal circumstances, the spring 23 is not compressed, because the spring constant is such that the axial force required to activate the switch is less than the threshold force required to compress the spring in its preloaded condition. However, if sufficient transient force is applied in abnormal circumstances, such as when the apparatus is inadvertently dropped, the spring is momentarily compressed to absorb the resultant shock loading and thereby prevent the switch from being damaged. The design thus provides an effective measure of impact protection, should the mouthpiece be dropped onto the joystick or otherwise inadvertently bumped, jolted or jarred.

The locating elements 4 in the mouthpiece are adapted respectively to be positioned between the user's teeth, on opposite sides of the mouth. A bite actuation mechanism 26 is disposed within each locating element (see particularly Figure 3). Each actuation mechanism 26 includes a circuit board 27 and an associated "bite switch" 28. Each circuit board 27 is also connected to the inner end of a respective connection pin 29. The opposite end 30 of each connection pin 29 protrudes from the silicone skin 17 adjacent the interface assembly. A plunger assembly 31 is disposed below each bite switch 28 to facilitate actuation. The plunger assembly consists of a cylindrical actuation bar 32, connected to a dome-shaped actuation head 33, by means of an intermediate connecting rod 34. The actuation bar 32 is oriented transversely with respect to the user's teeth, to ensure proper engagement notwithstanding variations in mouth shape between different users, and variations in the positioning of the mouthpiece. During manufacture of the apparatus, each bite switch 28, the associated actuation head 33 and part of the interconnecting rod 34 are encapsulated in a low- temperature curing layer of silicone 35. Thereafter, the entire bite-actuation mechanism 26, including the parts incorporated within the curing layer, is encapsulated in the outer skin 15 of the mouthpiece, which is composed of a more tear resistant grade of silicone than the low-temperature curing layer. Two electrical conductors (not shown) are embedded within the mouthpiece to interconnect the bite-actuation mechanisms 26 in the respective locating elements 4 such that the connecting pins 29 allow the two switches 28 to be wired in parallel. The shape and position of each actuation bar 32 produces a corresponding raised portion 36 in each respective locating element 4. The user positions these raised portions so as to be depressed by a biting or jaw clenching action. This control action causes the plungers 31 to be depressed so as to bring the actuators 33 to bear against the bite switches 28. This in turn activates these switches and closes associated control circuits on the respective circuit boards 27. In the absence of these plungers 31, the user would have to exert significantly greater pressure to overcome the resistance provided by the silicone covering 35 on the switches 28. However, the configuration of the plungers facilitates the activation of these switches, so that a lower threshold activation pressure is required. As a result of the resilient flexibility of the silicone, the plungers 31 return to their rest positions when the biting force is released, thereby deactivating the control circuits.

Each bite actuation mechanism 26 is also configured to provide a tactile detent or an audible "click" when the plungers 31 are depressed. This allows the user readily to discern that the desired switching action has occurred, and thereby avoid exerting excessive biting pressure, which might otherwise damage the control mechanism. As mentioned above, the mouthpiece 3 is detachable from the body 2. When the mouthpiece 3 and body 2 are connected to each other, the tapered shape of the sidewalls of the outer part 8 of the interface assembly 6 facilitates insertion of the assembly into a complementary aperture in a connection assembly 38 forming part of the body. During such connection, the protruding ends 30 of the connecting pins come into contact with springs 39 in the body. When the mouthpiece 3 is attached to body 2, the springs 39 are slightly compressed by the protruding ends 30 of the pins 29 so as to establish and maintain a positive electrical connection with the pins. When the mouthpiece 3 is detached from the body, the ends 30 of the pins are withdrawn from the springs. These springs 39, which form part of the connecting assembly 38, are electrically connected to a first micro-controller 40 incorporated into a circuit board 41 within the housing. Flexible conductors also connect the circuit board 22 associated with the tongue switch 21 to the micro-controller 40. Similarly, the circuit board 14 of the directional sensor 13 associated with the joystick is electrically connected to this micro- controller. These connections are best seen diagrammatically in the schematic of figure 4. Intermediate stage output signals from the first micro-controller 40 are then passed via a second micro-controller 42 on the same circuit board 41. The second microcontroller generates final stage output signals for delivery to an infrared transmitter 43 disposed on the front face of the body (see Figures 1 and 5). The apparatus further includes a replaceable lithium battery 44, disposed in a battery compartment located in the body, to power the micro-controllers, the associated circuit boards, and the infrared transmission circuitry. It will be appreciated, however, that any suitable power source may be used, including rechargeable batteries, or a DC power pack connected to mains power via an appropriately isolated transformer. In operation, lateral or vertical pressures on the control surface of the spherical head on the proximal end of the joystick constitute a first set of control actions imparted by the user's tongue. These inputs translate into corresponding pivotal movements of the joystick and hence of the support shaft 11, which in turn move the control spigot 16 via the interface assembly. These control inputs are translated by the circuit board 14 of the directional sensor mechanism 13 and the associated microprocessors 40 and 42 into a corresponding set of first control signals in electronic form. This reflects the first control mode.

Independently of the first control mode, depression of the plungers 31 by clenching the teeth in a second control action activates one or both of the associated bite switches 28, to generate corresponding second control signals representing the second control mode.

Independently of both the first and second modes, axial depression of the joystick 5 in the direction of arrow A by the user's tongue in a third control action causes the shaft 10 to slide through the bush 12 and actuate the tongue switch 21 on the circuit board 22, thereby to generate a third discrete control signal corresponding to the third control mode.

In a particularly preferred embodiment of the invention, the apparatus is intended for use as a mouse to control a computer 45 (see figure 5). In this embodiment, the apparatus is configured for the joystick 5, insofar as it is laterally and vertically movable, to take the place of the track-ball of a conventional mouse, and for the joystick, insofar as it is axially depressible as described above, to take the place of a conventional mouse

right-click button. The bite switches 28, sealingly housed within the actuating elements of the mouthpiece, are configured to perform the function of a conventional mouse left- click button. Of course, it will be appreciated that these control inputs may also be reconfigured in other ways as desired.

To enable the apparatus to be used in this way, the computer must first be connected to a receiver module 46. As represented diagrammatically in figure 5, the receiver module receives the output control signals 47 from the infrared transmitter 43, and converts these to a standardised format of the type that would ordinarily be generated by a conventional mouse for positioning the cursor and performing other control functions on the computer. In this way, advantageously, no special-purpose programming is required and conventional mouse software drivers may be employed. Turning now to describe the use of the apparatus in more detail in the control of a computer terminal, the mouthpiece 3 is initially positioned in the user's mouth, with the body 2 outside the mouth. The part of the mouthpiece immediately adjacent the point of attachment to the body is shaped to provide a locating formation 50 configured to be firmly gripped by the user's front teeth, with a lower part 51 of the body being sculpted so as comfortably to abut the user's chin 52. In this position, it will be appreciated that the gripping of the locating formation 50 by the user's front teeth in conjunction with the body or housing resting against the user's chin results in the apparatus being firmly supported relative to the user's head while allowing it to move readily with the head. Furthermore, the lateral locating elements 4, being disposed on opposite sides of the user's mouth, resist any tendency of the apparatus to rotate about an horizontal axis, so that it is stably supported for precise control. In this way, the apparatus is stably supported for precise control in the various modes, while not constraining in any way the natural movements of the user's head.

More specifically, with the mouthpiece 3 and hence the apparatus as a whole held firmly and stably as described, the user is free to manipulate the joystick 5 and the plunger mechanisms 31 with the tongue and jaw, respectively. Thus, the user can move the joystick 5 laterally and vertically to enable the full extent of control ordinarily provided by moving a mouse forward and backward, and from side to side, over a mouse pad, which has the effect of moving the mouse's internal track ball. This of course is also analogous to the movement of an operator's finger across the touch pad of a laptop computer or equivalent input devices. Similarly, the user can depress the joystick 5 axially with the tongue, to provide the functionality of the conventional mouse right- click. Likewise, the user can actuate the bite switches 28 by biting upwardly onto the locating elements 4 with the lower jaw, to provide the same functionality as the left-click button on a conventional mouse.

It will be appreciated that the smooth dome-shape of the control head of the joystick minimises discomfort, fatigue or injury to the user's tongue, which might otherwise result from friction, abrasion or repeated localised pressure concentrations.

As mentioned above, the mouthpiece 3 is waterproof and hence is impervious to the user's saliva. The diaphragm 18 also acts as a barrier to prevent the user's saliva from reaching and penetrating the body section. Thus, the apparatus has a "wet" area that is exposed to the user's saliva during use, and a "dry" area that is protected from the user's saliva as well as moisture from other external sources. As a result, moisture is prevented from penetrating the electronics of the apparatus, which affords a greater degree of safety, reliability and longevity than in prior art devices. Furthermore, the accumulation of saliva and the resultant build-up of bacteria is prevented, so that the apparatus affords a higher level of hygiene. The mouthpiece, being removable and waterproof, readily lends itself to being properly washed in a dishwasher or sterilised in a suitable apparatus, further contributing to convenient hygienic use. It will also be appreciated that, due to the detachability of the mouthpiece, the apparatus is suitable for use by more than one user, each user having his or her own mouthpiece which can be interchangeably connected to a shared body or housing. To facilitate such shared use, the mouthpieces of the respective users may be differently coloured or otherwise visually tagged for easy identification. The mouthpieces may also be customised and form fitted to suit individual user's requirements although it is envisaged that, subject to the provision of a selection of sizes, a relatively universal shape and configuration should suit most users. In this regard, it has been found that a mouthpiece similar in shape to those found on snorkels and other diving equipment is effective. Such a configuration readily lends itself to mass production at minimal cost, unlike the more complex and intricate componentry of many prior art devices.

Advantageously, the modes of operation of the apparatus corresponding to the three primary mouse functions described above have been selected according to the nature and frequency of these functions. More specifically, as the mouse right-click function is less frequently performed than the other mouse functions, it is appropriate for this f nction to be performed by forward thrusting of the user's tongue, which is a marginally more difficult control action. This mode of operation might be excessively tiring for the user if it were employed for a more frequently performed operation. By contrast, the biting action used to effect the more frequently used mouse left-click operation, is inherently less tiring for the user, and therefore more suitable to this function. The mode of operation for the mouse track-ball function, of lateral and vertical movement of the user's tongue, is also an appropriate mode, as the tongue is capable of sustained and accurate movement in these directions which are somewhat reflective of the tongue's natural movements while chewing food. In fact overall, the strength, accuracy and dexterity of the tongue as a muscle make it particularly well adapted, with only minimal specialised training, for this purpose. Accordingly, the control modes of the apparatus are ideally aligned to both the tasks to be performed and the ergonomics of the user.

Furthermore, it will be appreciated that the separation of the three modes of control enables them to be carried out simultaneously. This, in turn, permits the relatively easy performance of both "click and drag" type operations and right mouse button functions on the computer, which many previously known mouth controllers of this type are incapable of performing.

In all these respects, the invention represents both a practical and a commercially significant improvement over the prior art.

Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS :-

1. A hands-free control apparatus including: a body; first, second, and third control means connected to the body; support means adapted to support the control means adjacent a user's mouth in an operative position in which the first control means are operable by a first control action in the form of lateral and/or vertical movement of the user's tongue, the second control means are operable by a second control action in the form of changing pressure exerted by the user's jaw, and the third control means are operable by a third control action distinct from the first and second actions in the form of movement of part of the user's body above the neck; and output means adapted to generate output control signals corresponding to the respective control actions.

2. Apparatus according to claim 1 wherein the first control means include a joystick which in the operative position extends into the user's mouth.

3. Apparatus according to claim 2 wherein the joystick is adapted for lateral and vertical movement in response to corresponding lateral or vertical pressure or displacement imparted by the user's tongue.

4. Apparatus according to claim 3 wherein the joystick is adapted for both lateral and vertical movement about orthogonal axes, thereby in combination to provide for pivotal movement with two degrees of freedom.

5. Apparatus according to any one of claims 2 to 4 wherein the remote end of the joystick is operably connected to directional sensor means, which functions as a pressure or displacement transducer, to convert the lateral and vertical displacements of the joystick, and any combinations thereof, into corresponding electronic control signals.

6. Apparatus according to claim 5 wherein the directional sensor means makes use of an array of conductors etched onto a circuit board.

7. Apparatus according to claim 5 wherein the directional sensor means makes use of strain gauges or other suitable pressure or displacement transducers.

8. Apparatus according to claim 5 wherein the directional sensor means takes the form of a rotational displacement transducer, integrated into a gimbal type mounting or a spherical type universal joint.

9. Apparatus according to any one of claims 2 to 8 wherein the joystick has an outwardly rounded contact surface for engaging the user's tongue.

10. Apparatus according to claim 9 wherein the contact surface is substantially spherical in shape, and is defined by a control ball formation disposed on the proximal end of the joystick.

11. Apparatus according to any one of claims 2 to 10 wherein the second control means include a pressure actuated "bite switch" adapted to be positioned between the user's teeth, for actuation in response to the second control action in the form of a jaw clenching or biting action.

12. Apparatus according to any one of claims 2 to 11 wherein the third control means are associated with the joystick.

13. Apparatus according to claim 12 wherein the third control action takes the form of forward axial displacement of the j oystick as a result of axial pressure exerted by the user's tongue on the proximal end of the joystick.

14. Apparatus according to any one of the preceding claims wherein the support means include a mouthpiece configured for positioning in the user's mouth in the operative position, to enable the user securely to support the apparatus and positively to locate the control means.

15. Apparatus according to claim 14 wherein the mouthpiece includes a pair of protruding locating elements, configured respectively to be positioned between the teeth on opposite sides of the user's mouth in order to stabilise the mouthpiece against inadvertent rotational movement and to facilitate accurate articulation of the control means.

16. Apparatus according to claim 15 wherein the mouthpiece includes a front formation configured for positioning between the user's upper and lower front teeth, the locating elements are respectively configured for positioning between the user's upper and lower teeth on opposite sides of the mouth, and the pressure switch is disposed within one of the locating elements.

17. Apparatus according to claim 15 or claim 16 including two of the pressure switches, each being located on or in a respective one of the locating elements on the mouthpiece, and both being electrically connected in a parallel circuit.

18. Apparatus according to any one of claims 14 to 17 wherein the mouthpiece includes a moulded silicone skin

19. Apparatus according to claim 18 wherein the switch or switches is/are encapsulated within the skin.

20. Apparatus according to claim 19 including a plunger assembly positioned adjacent each switch, and encapsulated within the skin for actuating the switch when increased gripping or clenching pressure is applied via the user's jaws.

21. Apparatus according to any one of the preceding claims wherein the output means include an electronic control circuit including a microprocessor disposed within the body, and infrared or other wireless transmission means electrically connected to the control circuit.

22. Apparatus according to any one of the preceding claims including a power source.

23. Apparatus according to claim 22 wherein the power source includes at least one battery.

24. Apparatus according to claim 23 wherein the battery is a replaceable lithium battery, housed in a battery compartment within the body.

25. Apparatus according to claim 23 or claim 24 wherein the battery is rechargeable.

26. Apparatus according to claim 22 wherein the power source includes a DC power pack connected with an appropriately isolated mains transformer.

27. Apparatus according to any one of the preceding claims wherein the body is adapted to be disposed substantially outside of the user's mouth when the mouthpiece is in the operational position.

28. Apparatus according to any one of the preceding claims including connection means for detachably connecting the mouthpiece to the body so as to permit substitution of alternative mouthpieces, and thereby enable the same body and housing to be readily and hygienically interchanged and shared between multiple users.

29. Apparatus according to any one of the preceding claims wherein the body is configured to abut the user's chin in the operative position, to enhance the stability and accuracy of the control mechanisms.

30. Apparatus according to any one of the preceding clams including a moisture impermeable barrier in order substantially to prevent the ingress of moisture emanating from the user's mouth into the electronic control and output circuitry housed within the body.

31. Apparatus according to claim 30 wherein the barrier is a membrane disposed effectively intermediate the mouthpiece and the body.

32. Apparatus according to any one of the preceding claims being adapted to serve as a computer mouse with the first control means performing the function of a conventional mouse track ball, the second control means performing the function of a conventional mouse left-click button, and the third control means performing the function of a conventional mouse right-click button.

33. A mouthpiece for a control apparatus as defined in any one of the preceding claims, the mouthpiece forming part of the support means and being configured for positioning in the user's mouth in the operative position, to enable the user securely to support the apparatus and positively to locate the control means.

34. A mouthpiece according to claim 33 including a pair of protruding locating elements, configured respectively to be positioned between the teeth on opposite sides of the user's mouth in order to stabilise the mouthpiece against inadvertent rotational movement and to facilitate accurate articulation of the control means.

35. A mouthpiece according to claim 34 including a front formation configured for positioning between the user's upper and lower front teeth, the locating elements are respectively configured for positioning between the user's upper and lower teeth on opposite sides of the mouth, and the pressure switch is disposed within one of the locating elements.

36. A mouthpiece according to claim 34 or claim 35 including a pressure actuated "bite switch" adapted to be positioned between the user's teeth for actuation in response to a jaw clenching or biting action, the switch being located on or in one of the locating elements on the mouthpiece.

37. A mouthpiece according to claim 36 including two of the switches, each being located on or in a respective one of the locating elements on the mouthpiece, and both being electrically connected in a parallel circuit.

38. A mouthpiece according to any one of claims 33 to 37 including a moulded silicone skin.

39. A mouthpiece according to claim 38 wherein the switch or switches is/are encapsulated within the skin.

40. A mouthpiece according to claim 39 including a plunger assembly positioned adjacent each switch, and encapsulated within the skin for actuating the switch when increased gripping or clenching pressure is applied via the user's jaws.