WO2001024726A1

WO2001024726A1 - A self-activating tool

Info

Publication number: WO2001024726A1
Application number: PCT/DK2000/000544
Authority: WO
Inventors: John Reipur
Original assignee: Reipur Technology A/S
Priority date: 1999-10-06
Filing date: 2000-09-29
Publication date: 2001-04-12
Also published as: AU7406200A; AU7406100A; WO2001026124A1

Abstract

A self-activating tool, which has a rotatable part and means for rotating the part, where rotation of the rotatable part is provided when a force is exerted on the rotating part. The present tool is insensitive to the actual direction of the force displaceing the tool so that rotation is maintained even if the force does not displace the part in a predetermined direction. The displacement-detecting means are provided in a fluid-tight container to apply the tool in dentistry, such as for polishing teeth.

Description

A SELF-ACTIVATING TOOL

The present invention relates to a tool, which may be activated without the use of a standard switch, such as a switch operable by a finger or a hand, and which will keep rotating even when the activation pressure varies. A number of situations exist where it is not desired to have to activate a separate switch in order to activate the tool.

One such situation is found when a dentist is cleaning the teeth of a patient. In this situation, the dentist will hold both a polishing tool - normally a motor with a polishing tool - and a suction device or a tool for providing pressurised air. A polishing tool of that type may be seen in US-A-3,675,330 where a simple switch is positioned so as to detect a forcing of the polishing tool against the teeth of the patient. Rotation of the tool will be maintained as long as the force exceeds that of a biasing spring.

However, the size and direction of the force applied to the teeth of the patient will vary. Thus, since the detector is only able to determine the force in one direction and due to the fact that there will always be clearance in the bearings of the instrument, the single detector may very well interrupt the rotation even though this was not intended.

The present invention relates to an improvement of the above tool - an improvement that makes it easier to determine the displacement of the tool independently of the direction of the force.

In a first aspect, the invention relates to a tool having: - a first part, a second part rotatable in relation to the first part, the rotatable part being displaceable in relation to the first part along a predetermined axis, means for rotating the rotatable part in relation to the first part, a plurality of means for detecting displacement of the rotatable part along the axis and means for subsequently making the rotating means rotate the rotatable part,

the plurality of detecting means being positioned at a distance from the axis and angularly spaced around the predetermined axis. Thus, the invention relates to the providing of a plurality of detecting means not directly on the axis of displacement but at a distance therefrom and angularly spaced around the axis. In this manner, clearance in the bearing of the instrument may slightly displace the detecting means in the tool in a direction away from one detecting means, but normally also toward another detecting means. Thus, even though the direction of the force changes in such a manner that one detecting means may at a point in time not detect a sufficient displacement, another detecting means may detect an even larger displacement - whereby the tool will keep rotating.

In order to obtain the optimal angular sensitivity - that is, to minimise any angles where the detecting means will not detect displacement, the plurality of detecting means is preferably at least substantially evenly, angularly spaced around the predetermined axis.

Preferably 3 or more detecting means are provided.

It may be desired that the plurality of detecting means has at least substantially the same distance from the predetermined axis.

In a preferred embodiment, the tool is adapted to be hand held whereby the first part would form a handle. The following description will refer to portable tools. This, however, should not be understood as limiting the present invention but only as an example of an embodiment. Most of the below embodiments of the invention are just as relevant for nonportable tools.

Normally, each of the plurality of detecting means comprises two parts, one being connected to the handle and one being connected to the rotatable part. In this manner, a single assembly may be formed having one part of each of the detecting means whereby assembly of the tool is facilitated.

In order to facilitate assembly, the plurality of detecting means is preferably positioned in at least substantially the same plane. Normally, the plane will be at least substantially perpendicular to the predetermined axis.

In one situation, the rotatable part may be displaceable in relation to the handle in a predetermined direction at least substantially along an axis of rotation thereof. Normally, the direction of the displacement will be along a line from the rotating part toward the handle. In general, the axis of rotation may be chosen arbitrarily in relation to this line.

Preferably, the means for rotating comprises a rotation axle. In that situation, the detecting means may be adapted to detect a displacement of the axle in the direction along a rotation axis thereof and in relation to the handle. This axle may thus be used both for e.g. transferring movement from the handle to the rotating part and for sensing/transferring the displacement.

Normally, it will be desired that the axle has a first end engaging with the rotating part and a second end rotationally engaging with the handle, and where the detecting means are provided between the second end and the handle.

In one situation, each detecting means comprises at least one pair of electrical contacts relatively displaceable in the predetermined direction and being adapted not to contact each other, when the part is not displaced, and to contact each other, when the part is displaced. In another situation, this is reversed so that no connection is a sign of displacement.

In dentistry, it is especially advantageous that the pairs of electrical contacts are sealed within a fluid-tight container. This is due to the fact that most of the tools used in this field should be cleaned by autoclaving - and due to the fact that most of the known types of electrical contacts cannot withstand autoclaving. Thus, providing the contacts within a fluid-tight container will obviate this problem. Preferably, the container is flexible so that a displacement of e.g. a side or part thereof will provide a displacement of the connectors - and thereby the detection of the displacement.

An especially advantageous detecting means is one where: at least two pairs of electrical contacts are provided, one first contact electrode of each pair engaging the rotational part and one second contact electrode of each pair engaging the handle, the first contacts being at least partly embedded in a resilient means, each electrical contact being exposed at a surface part of the resilient means, the resilient means being adapted to make the contacts displaceable in relation to the handle and the rotatable part, the resilient element is at least substantially enclosed by an enclosing means, except for the surface part(s) at which the engaging means are exposed, and the resilient means is at least substantially incompressible and at least substantially fills out a volume enclosed by the enclosing means.

Naturally, the silicone material needs not be completely enclosed (apart from the surface thereof covered by the contact elements). An opening far from the displaced contacts will have no actual influence due to the fact that, when a contact is displaced, the flow resistance of the silicone is normally so high that no significant portion of the silicone is displaced in more remote parts thereof. Thus, the largest displacement will be of adjacent contacts and/or projections.

The enclosing means preferably being essentially stiff or at least much stiffer than the resilient element.

Naturally, alternatively or additionally, the second contacts may be provided in the resilient means in the enclosing means.

Contacts of this type have been described in the Applicant's below-mentioned co-pending application and have a number of advantages both in relation to withstanding vibrations and autoclaving.

Preferably, the rotating part is adapted to be displaceable toward the handle. Also, the tool may comprise means for biasing the rotating part at least substantially along the direction and away from the handle. In that situation, a certain force has to be applied in order to provide the displacement and thus bringing about the rotation.

A preferred tool according to the first aspect is a tool adapted to be hand held, such as a tool for use by a dentist, such as for polishing teeth.

An especially interesting embodiment is one further comprising means for receiving and providing power to the rotating means and means for interrupting an electrical contact between the power-providing means and the rotating means, the interrupting means being different from but controlled by the detecting means so that when the detecting means detect the displacement, electrical contact is provided between the power-providing means and the rotating means. In this manner, the electrical contacts do not receive the actual power for the rotating means but merely controlling signals. This has a number of advantages due to sparks etc. when the distance between the contacts is small.

Also, when the interrupting means is adapted to maintain the electrical connection for a predetermined period of time after a point in time where the detecting means no longer detect the displacement, the further advantage is seen that if the displacement is too small to be detected for a small period of time, the tool will keep rotating for the predetermined period of time. A situation where the force is small may be a situation where a small part of a tooth, such as a small tooth or an edge thereof, is polished. If the "normal" force was to be applied, the polishing might damage the tooth. In this embodiment, the tool may keep rotating for 1 , 2, 3, or more seconds in order for the dentist to also be able to polish such teeth.

In a second aspect, the invention relates to a method for manufacturing a detecting means for the tool according to the first aspect, the method comprising:

embedding at least two contact elements in a surface part of a first element of a resilient material having a first hardness, - covering at least a part of those parts of the surface part in which the contact elements are not embedded with a material which has a hardness higher than the first hardness, providing at least two contact elements at, in or on a surface part of a second element, - assembling the first and second elements in such a manner that the contact elements are positioned adjacently and may engage when the first and second elements are forced toward each other or positioned adjacently to each other.

Preferably: - the providing step comprises embedding the at least two contact elements partly in a surface part of a second element of a resilient material, and the assembling step comprises sealing the detecting means by sealing outer portions of the first and second elements, which outer portions form part of the surface parts of the first and second elements and, on those surface parts, encircle the at least two contact elements embedded in those surface parts. Naturally, the embedding steps may be performed at the same time, and, as a matter of fact, the detecting means may be moulded in a single operation where the electrical contacts are positioned in predetermined positions, whereupon the silicone material is moulded around these contacts. In order to provide air (or another, preferably compressible, material) between the contacts, the moulding may be performed in vacuum or under an increased pressure, while either an air bubble is provided or an air passage to the surroundings is maintained. That passage will then preferably be sealed subsequently to the moulding.

In the following, a preferred embodiment of the invention is described with reference to the drawing, wherein:

Fig. 1 illustrates a cross section of a preferred embodiment of the invention,

Fig. 2 is an end view of a contacting element of the embodiment of Fig. 1 ,

Fig. 3 is an enlarged cross section of the embodiment of Fig. 1,

Fig. 4 is an enlarged cross section of the embodiment of Fig. 3,

Fig. 5 is the cross section of Fig. 3 during displacement, and

Fig. 6 is an enlarged cross section of the embodiment of Fig. 5.

In Fig. 1 , a tool 10 is illustrated having an axle 12 and a polishing tool 14 for polishing teeth. The axle 12 is engaged by retaining means 16, which engage a narrow portion of the axle 12. The engaging means 16 may disengage the axle 12 when a button 20 is pressed, whereby the engaging means 16 rotate about centres of rotation 18.

It is seen that the narrow portion of the axle 12 has a longitudinal extension longer than that of the engaging means 16, whereby the axle 12 may be displaced in its longitudinal direction while engaged by the engaging means 16. The axle 12 abuts, at its end, a contact element 22 which engages a first part 32 of a set of electrical contacts 30 adapted to detect a displacement of the axle 12 toward the button 20.

The set 30 comprises two parts, 32 and 34, each having three electrical contact elements (see Fig. 2) embedded in a silicone material making the. electrical contact elements of a part displaceable in relation to each other. In addition, the silicone of the second part, 34, is surrounded/encircled/enclosed at all sides, and only the electrical contact elements thereof are exposed. This has the advantage that a displacement of one electrical contact element e.g. into the silicone will bring about a displacement of the other two electrical contact elements of the second part in a direction away from the silicone. The advantage of this type of electrical connection is described in detail in PCT/DK99/00229. The positioning of three sets of electrical contact elements provides a better electrical connection also during vibration of the tool 10 due to the action of the element 14. The action of the element 14 may act differently on the individual sets of electrical contact elements, but due to the interaction of the elements of the second part, an optimum connection is ensured. In fact, the electrical contact elements of the first part may also be embedded in an enclosed silicone material in order to also have this advantage provided thereby at the first part 32. Alternatively, the contact elements of the first part need not be embedded in a silicone material and may simply be more or less fixed to the element 22.

An alternative to the three sets of contact elements would be providing two concentric circular contact elements, where one contact element has a U-shaped cross section and the other contact element fits within the U-shape.

Figures 3 and 4 illustrate the situation where no displacement takes place. It is seen that the electrical contact elements of the first part, 32, do not contact those of the second part, 34.

Figures 5 and 6 illustrate the situation where a displacement has taken place in the direction toward the button 20. In this situation, the contact elements of the first and second parts touch, and this electrical connection - and thus the displacement - is detectable. This detection of the electrical contact may then be used for a standard start-up or controlling of e.g. a motor or turbine rotating the axle 12. Also, this motor or turbine may be stopped, when no electrical contact is detected between the first and second parts.

The actual manufacture of the first and second parts may be a two-step procedure where the individual parts are initially moulded and where the two parts are subsequently assembled. In the present embodiment, the two parts are assembled by a bracket 36. Naturally, this means that the silicone material of the second part is not completely enclosed (apart from the surface thereof covered by the contact elements). However, this has no actual influence due to the fact that, when a contact element of the second part is displaced, the flow resistance of the silicone is normally so high that no significant portion of the silicone is displaced toward the first part - whereby all of the displacement or almost all of the displacement is transferred to the other contact element of the second part.

Claims

1. A tool having:

- a first part, a second part rotatable in relation to the handle, the part being displaceable in relation to the handle along a predetermined axis, means for rotating the rotatable part in relation to the first part, a plurality of means for detecting displacement of the rotatable part along the axis and means for subsequently making the rotating means rotate the rotatable part,

the plurality of detecting means being positioned at a distance from the axis and angularly spaced around the predetermined axis.

2. A tool according to claim 1 , wherein the plurality of detecting means is at least substantially evenly, angularly spaced around the predetermined axis.

3. A tool according to claim 1 or 2, wherein the plurality of detecting means has at least substantially the same distance from the predetermined axis.

4. A tool according to any of the preceding claims, wherein each of the plurality of detecting means comprises two parts, one being connected to the handle and one being connected to the rotatable part.

5. A tool according to any of the preceding claims, wherein the plurality of detecting means is positioned in at least substantially the same plane.

6. A tool according to claim 5, wherein the plane is at least substantially perpendicular to the predetermined axis.

7. A tool according to any of the preceding claims, wherein the rotatable part is displaceable in relation to the first part in a predetermined direction at least substantially along an axis of rotation thereof,

8. A tool according to any of the preceding claims, wherein the means for rotating comprises a rotation axle, and wherein the plurality of detecting means is adapted to detect a displacement of the axle in the direction along a rotation axis thereof and in relation to the first part.

5

9. A tool according to claim 8, wherein the axle has a first end engaging with the rotatable part and a second end rotationally engaging with the first part, and wherein the detecting means is provided between the second end and the first part.

10 10. A tool according to any of the preceding claims, wherein the detecting means comprises at least one pair of electrical contacts relatively displaceable in the predetermined direction and being adapted not to contact each other, when the rotatable part is not displaced, and to contact each other, when the rotatable part is displaced.

15 11. A tool according to claim 10, wherein the at least two electrical contacts are sealed within a fluid-tight container.

12. A tool according to claim 10, wherein: at least two pairs of electrical contacts are provided, one first contact electrode of 20 each pair engaging the axle and one second contact electrode of each pair engaging the first part, the first contacts being at least partly embedded in a resilient means, each electrical contact being exposed at a surface part of the resilient means, the resilient means being adapted to make the first contacts displaceable in relation to the first 25 part and the rotational part, the resilient element is at least substantially enclosed by an enclosing means, except for the surface part(s) at which the engaging means are exposed, and the resilient means is at least substantially incompressible and at least substantially fills out a volume enclosed by the enclosing means. 30

13. A tool according to claim 11 , wherein the container is flexible.

14. A tool according to any of the preceding claims, wherein the rotatable part is adapted to be displaceable toward the first part.

35

15. A tool according to any of the preceding claims, further comprising means for biasing the rotatable part at least substantially in the direction and away from the first part.

16. A tool according to any of the preceding claims, the tool being adapted to be hand held, such as a tool for use by a dentist, such as for polishing teeth, and wherein the first part constitutes a handle.

17. A method for manufacturing a detecting means for a tool according to any of the preceding claims, the method comprising:

embedding at least two contact elements in a surface part of a first element of a resilient material having a first hardness, covering at least a part of those parts of the surface part in which the contact elements are not embedded with a material which has a hardness higher than the first hardness, providing at least two contact elements at, in, or on a surface part of a second element, assembling the first and second elements in such a manner that the contact elements are positioned adjacently and may engage when the first and second elements are forced toward each other.

18. A method according to claim 17, wherein: the providing step comprises embedding the at least two contact elements in a surface part of a second element of a resilient material, and - the assembling step comprises sealing the detecting means by sealing outer portions of the first and second elements, which outer portions form part of the surface parts of the first and second elements and, on those surface parts, encircle the at least two contact elements embedded in those surface parts.