WO2001045125A1

WO2001045125A1 - Non-locking switch

Info

Publication number: WO2001045125A1
Application number: PCT/FI2000/001098
Authority: WO
Inventors: Heikki Vuolas; Petri Kortelainen
Original assignee: H.O. Vuolas Oy
Priority date: 1999-12-17
Filing date: 2000-12-14
Publication date: 2001-06-21
Also published as: TW476081B; AU2376901A

Abstract

A non-locking switch comprising a magnet (2), a contact means (4) and a measuring means (7). The contact means (4) is of at least partly magnetizable material, and the magnet (2) and the contact means (4) are arranged to move with respect to one another in such a way that the contact means (4) is on a continuous basis at least partly under the influence of the magnetic field of the magnet (2). An external force makes the magnet (2) and the contact means (4) move with respect to one another, whereby the magnetic field of the magnet (2) changes, which is detected by the measuring means (7). After the external force has ceased to affect, the magnetic field of the magnet (2) moves the magnet (2) and the contact means (4) back to their original mutual position.

Description

NON-LOCKING SWITCH

The invention relates to a non-locking switch which comprises an actuating means having at least one magnet and a contact means of at least partly magnetizable material, the magnet and the contact means being mov- able with respect to one another along a given predetermined path by the action of an external force, and the contact means being continuously at least partly under the influence of the magnetic field of at least one magnet acting as the actuating means such that the field of the magnet permits the magnet and the contact means to maintain a given mutual position when no external force is exerted on the switch and to return to the given mutual position after the external force has ceased to affect the switch.

Finnish patent publication 98,967 discloses a non-locking switch, wherein a press of the switch is detected by means of electrodes attached to the switch frame and extending outside said switch frame in such a manner that an electric contact is provided between the electrodes when the contact means is pressed against the electrodes by means of an external force, the contact means being located inside the switch frame and continuously at least partly under the influence of the magnetic field of the magnet. After the external force has ceased to affect the contact means returns to its initial position by the action of the magnetic field of the magnet. The switch disclosed in the publication is reliable but relatively difficult to manufacture because of the electrodes to be attached to the frame. The electrodes also add to the total height of the switch structure. Moreover, to place the switch inside a specific frame is almost the only way to construct a switch of this type. One known non-locking switch has a magnet attached to the switch shaft, which magnet moves, when the switch is pressed, with respect to a Hall generator placed in the switch and monitoring the movement of the magnet. The Hall generator reacts to the movement of the magnet with respect thereto and thus indicates the press of the switch. The switch shaft returns to its initial position by means of a spring. However, the spring will fatigue and become brittle with use, and therefore the service life of the spring-return switch is relatively short. It is also difficult to provide the spring-return switch with a property to allow the user of the switch to have reliable tactile feedback on the function of the switch. The switch has also a relatively high structure. The object of the present invention is to provide a simple and reliable non-locking switch. The switch of the invention is characterized in that at least one measuring means is arranged in connection with at least one magnet acting as the actuating means to detect a change in the magnetic field of said magnet caused by a mutual movement of the magnet and the contact means pro- duced by the action of an external force.

The basic idea of the invention is that the non-locking switch comprises an actuating means having at least one magnet, and a contact means made of at least partly magnetizable material, and that the magnet and the contact means are movable with respect to one another along a predeter- mined path by an external force. The mutual movement of the magnet and the contact means is detected as a change in the magnetic field of the magnet serving as the actuating means, i.e. as a change in density of magnetic flux, by a measuring means detecting the change in the magnetic field, preferably by a Hall generator. Further, the basic idea is that the contact means is con- tinuously under the influence of the magnetic field, and when the effect of an external force ceases the magnet and the contact means return to their original mutual position by the action of the magnetic field of the magnet serving as the actuating means. The magnet and the contact means remain in their original mutual position by the action of the magnetic field of the magnet when no external force is exerted on the switch. According to one preferred embodiment of the invention, a washer, which is made of paper or cardboard or other flexible and/or soft material having substantially no effect on the strength of the magnetic field of the magnet, is placed between the magnet and the contact means of the switch so as to absorb completely or partly the sound produced when the switch is operated. According to a second preferred embodiment of the invention, a traction force is required to move the contact means of the switch in the magnetic field of the magnet. According to a third preferred embodiment of the invention, the magnet of the switch is at least partly placed inside a cupped contact means made of at least partly magnetizable material. According to a fourth preferred embodiment of the invention, the magnet and the contact means of the switch are made of such materials that the magnetic field of the magnet pushes the contact means away from the magnet, whereby the contact means can also be used as a push button of the switch.

The invention has an advantage that the switch according to the in- vention has long operating life, has a low structure and is simple to manufacture as compared with known solutions. Moreover, the switch according to the invention does not necessarily require a separate frame of its own, but the switch can be arranged as an integral part of the structure of the device where the switch is used. Another advantage is that when the switch is employed the functioning of the switch can be felt as a tactile sensation. The switch can also be constructed such that it has no magnetic field in an off-position. In this context the term non-locking denotes that the switch returns to its original position after the external force has ceased to affect.

In the following, the invention will be described in greater detail with reference to the attached drawings, in which Figure 1 is a schematic side view and partly cross sectional view of an embodiment of a switch according to the invention;

Figure 2 is a schematic side view and partly cross sectional view of a second embodiment of the switch according to the invention;

Figure 3 is a third schematic side view and partly cross sectional view of the switch according to the invention; and

Figure 4 is a fourth schematic side view and partly cross sectional view of the switch according to the invention.

Figure 1 shows a schematic side view and partly cross sectional view of a switch 1 according to the invention. The switch 1 comprises a mag- net 2 attached to a support means 3 made of plastic, for instance. The switch 1 further comprises a contact means 4 that is preferably plate-like. The contact means 4 must be of at least partly magnetizable material, such as iron, in order for the magnetic field of the magnet 2 to affect the contact means 4. The contact means 4 can also be completely of iron, whereby it is fully magnetiz- able. In the present document, the term magnetizable refers to material that is susceptible to the effect of a magnetic field. The contact means 4 is movable by focusing a force on a shaft 5 which is arranged to extend through the magnet and is in connection with the contact means 4. A push button 6 is also attached to the shaft 5. The support means 3 and the push button 6 are de- signed such that in the off-position as in Figure 1 the push button 6 preferably remains within the outline of the support means structure, which allows the structure of the switch 1 to be extremely low. The switch 1 further comprises a measuring means 7 which is attached to the support means 3, in connection with the magnet 2, and which measures changes in the magnetic field of the magnet 2, the measuring means preferably being a Hall generator. The magnet 2 and the measuring means 7 of the switch 1 are arranged substantially immovable with respect to one another. The switch 1 of Figure 1 operates such that when no external force is exerted on the switch 1 , the magnetic field of the magnet 2 attracts the contact means 4 and consequently the magnetic field of the magnet 2 is shorted via the contact means 4. If the contact means 4 is thin, the magnetic field is shorted only partly. The thicker the contact means 4, the more the magnetic field is shorted, preferably the magnetic field is shorted completely via the contact means 4, whereby there will be no more magnetic field in the switch 1. Naturally, the properties of the material of the contact means 4 also contribute to the shorting of the magnetic field. In Figure 1 , when the push button 6 is pressed upwardly, the contact means 4 attached to the shaft 5 moves simultaneously upwardly, whereby the magnetic field of the magnet 2 changes by the action of the movement of the contact means 4, and consequently the measuring means 7 detects the press of the switch 1 on the basis of the change in the magnetic field of the magnet 2 and transmits typically a signal of a few micro volts from the switch 1 onwards to indicate the press of the switch 1. The structure of the switch 1 is such that even when the contact means 4 is in its highest position it is subjected to the effect of the magnetic field of the magnet 2. The highest possible position of the contact means 4 is defined on the basis of the structure of the shaft 5 and the push button 6. The shaft 5 can be arranged to move only slightly on the basis of the structure of the support means 3 and the push button 6. When the external force exerted on the push button 6 and thereby on the shaft 5 and the contact means 4 ceases, the magnetic field of the magnet 2 attracts the contact means 4 back against the magnet 2. The switch 1 of Figure 1 is thus a non- locking push button switch.

When the switch 1 is in its off-position as in Figure 1 , the magnetic field of the magnet 2 has no effect on the switch 1 , and therefore it is easier to detect a press of the push button 6 with the measuring means 7 as a greater change in the magnetic field of the magnet 2 than in a situation where the magnetic field would have a continuous effect on the switch 1.

The switch 1 of Figure 1 can also be implemented such that the magnet 2 and the contact means 4 change places, i.e. the magnet 2 is arranged in connection with the shaft 5, in the place of the contact means 4, and the contact means 4 is attached to the support means 3, in the place of the magnet 2. The contact means 4 and the measuring means 7 are arranged to be substantially immobile with respect to one another. Otherwise the switch 1 operates as described above. In this embodiment, the separate contact means 4 can also be omitted, if the support means 3 is made of at least partly magnetizable material, whereby the support means 3 can serve as the contact means 4. In that case, it is advantageous to make the support means 3 of two separate parts to be attached to one another, when the support means 3 part made of at least partly magnetizable material acts as the contact means 4 and the support means 3 part made of e.g. plastic acts as a mounting base for the measuring means 7.

In one preferred embodiment of the switch 1 , a washer 8 made of paper or cardboard or other flexible and/or soft material is placed between the magnet 2 and the contact means 4 to dampen the operation of the switch 1 and at the same time to absorb, completely or partly, the sound produced by the switch 1 in operation. Preferably, the washer 8 is made of material that substantially has no effect on the magnetic field of the magnet 2. Figure 2 shows a schematic side view and partly cross sectional view of a second embodiment of the switch 1 according to the invention. In the switch 1 of Figure 2, the magnet 2 and the contact means 4 are made of such materials that the magnetic field of the magnet 2 pushes the contact means 4 away from the magnet 2. The structures of the shaft 5 and the push button 6 of the switch 1 are such that the contact means 4 arranged in connection with the shaft 5 is allowed to move away from the magnet 2 only a distance defined by the shaft 5 and the push button 6. In the switch of Figure 2, in order to provide a change in the magnetic field of the magnet 2 caused by a movement of the contact means 4, an external force, which pulls downwardly in the case of Figure 2, must be exerted on the push button 6. After the external force exerted on the push button 6 has ceased to affect, the magnet 2 pushes the contact means 4 back to its off-position appearing in Figure 2. The switch of Figure 2 is thus a non-locking pull switch.

Figure 3 shows a schematic side view and partly cross sectional view of a third embodiment of the switch 1 according to the invention. In the switch 1 of Figure 3, the contact means 4 has a cupped shape, the cupped contact means 4 partly surrounding the magnet 2 in such a way that in the off- position, as in Figure 3, the contact means 4 is partly located between the magnet 2 and the measuring means 7. When the push button 6 of the switch 1 is pressed upwardly as in Figure 3, the cupped contact means 4 attached in connection with the shaft 5 moves from around the magnet 2 producing a change in the magnetic field of the magnet 2 in the switch 1 , the change in the magnetic field being detected by the measuring means 7. When the cupped contact means 4 extends completely around the magnet 2, the switch 1 being in off-position as in Figure 3, there is no magnetic field outside the contact means 4, if the structure and/or thickness of the contact means 4 is such that the magnetic field of the magnet 2 is shorted completely via the contact means 4. The contact means can also completely encompass the magnet 2. The structure of the cupped contact means 4 can also be such that the contact means 4 will not come into contact with the magnet 2. The switch 1 of Figure 2 can also employ the cupped contact means 4 according to Figure 3, whereby the cupped contact means 4 moves at least partly around the magnet 2 by the action of the downward-pulling force exerted on the shaft 5 via the push button 6 causing a change in the magnetic field of the magnet 2.

Figure 4 shows a schematic side view and partly cross sectional view of a fourth embodiment of the switch 1 according to the invention. In the switch 1 of Figure 4, the magnet 2 and the contact means 4 supported to the frame 9 are made of such materials that the magnetic field of the magnet 2 pushes the contact means 4 away from the magnet 2. In the switch 1 of Figure 4, the contact means 4 also serves as the push button of the switch 1 , the ex- ternal force being exerted on the contact means 4 from above as seen in Figure 4. The structures of the contact means 4 and the frame 9 are such that in the off-position of the switch 1 as in Figure 4, the contact means 4 is allowed to move away from the magnet 2 only a distance defined by the structures of the contact means 4 and the frame 9. The switch 1 of Figure 4 does not re- quire a separate shaft 5 and a push button 6.

The force required for moving the contact means 4 of the switch 1 according to the invention can be controlled, for instance, by using magnets of various sizes as actuating means. An easier way to control the force required for moving the contact means 4 is to change the thickness of the contact means 4. Controlling the force required for moving the contact means 4 is particularly advantageous in a situation where Braille characters are placed on the push button 6, when the force needed for pressing the switch 1 exceeds the force used for feeling the characters, preventing an accidental press of the switch 1. The drawings and the relating specification are only intended to illustrate the inventive idea. The details of the invention may vary within the scope of the claims. Thus, the switch 1 in Figure 1 can have a structure in which a traction force is required for detaching the contact means 4 from the magnet 2. The contact means 4 can also be rod-like or have any other suitable shape. The switch 1 of the invention needs no specific frame, but the switch 1 parts can also be arranged in a separate frame. Further, the support means 3 can also serve as the frame of the switch 1. Furthermore, it is possible to implement the structure of the actuating means such that it employs e.g. an auxiliary spring or springs, in addition to the magnet 2, however, it is substantial that the actuating means comprises at least one magnet 2.

Claims

1. A non-locking switch which comprises an actuating means having at least one magnet (2) and a contact means (4) of at least partly magnetizable material, the magnet (2) and the contact means (4) being movable with respect to one another along a given predetermined path by the action of an external force, and the contact means (4) being continuously at least partly under the influence of the magnetic field of at least one magnet (2) acting as the actuating means such that the field of the magnet (2) permits the magnet (2) and the contact means (4) to maintain a given mutual position when no external force is exerted on the switch (1) and to return to the given mutual position after the external force has ceased to affect the switch, characterized in that at least one measuring means (7) is arranged in connection with at least one magnet (2) acting as the actuating means to detect a change in the magnetic field of said magnet (2) caused by a mutual movement of the magnet (2) and the contact means (4) produced by the action of an external force.

2. A non-locking switch as claimed in claim 1, characterized in that the magnet (2) acting as the actuating means and the measuring means (7) are arranged to be substantially immobile with respect to one an- other.

3. A non-locking switch as claimed in claim 1, characterized in that the contact means (4) and the measuring means (7) are arranged to be substantially immobile with respect to one another.

4. A non-locking switch as claimed in claim 1 or 2, charac- t e r i z e d in that the magnet (2) and the measuring means (7) are attached to the same support means (3).

5. A non-locking switch as claimed in claim 1 or 3, characterized in that the contact means (4) and the measuring means (7) are attached to the same support means (3).

6. A non-locking switch as claimed in any one of the preceding claims, characterized in that the contact means (4) is plate-like.

7. A non-locking switch as claimed in any one of claims 1 to 5, characterized in that the contact means (4) is rod-like.

8. A non-locking switch as claimed in any one of claims 1 to 5, characterized in that the contact means (4) is cupped.

9. A non-locking switch as claimed in claim 8, characterized in that the switch (1) being in off-position the contact means (4) at least partly surrounds the magnet (2).

10. A non-locking switch as claimed in any one of the preceding claims, characterized in that the materials of the magnet (2) and the contact means (4) are selected such that the magnet (2) rejects the contact means (4).

11. A non-locking switch as claimed in claim 10, characterized in that the contact means (4) is the push button of the switch (1).

12. A non-locking switch as claimed in any one of the preceding claims, characterized in that the switch (1) has a shaft (5).

13. A non-locking switch as claimed in claim 12, characterized in that the shaft (5) is arranged to extend through the magnet (2).

14. A non-locking switch as claimed in claim 12, character- ize d in that the shaft (5) is arranged to extend through the contact means

(4).

15. A non-locking switch as claimed in any one of the preceding claims, characterized in that a washer (8) made of flexible and/or soft material is arranged between the magnet (2) and the contact means (4).

16. A non-locking switch as claimed in claim 15, characterized in that the washer (8) is made of material having substantially no effect on the magnetic field of the magnet (2).

17. A non-locking switch as claimed in claim 16, characterized in that the washer (8) arranged between the magnet (2) and the con- tact means (4) is made of paper or cardboard.

18. A non-locking switch as claimed in any one of the preceding claims, characterized in that the contact means (4) is of completely magnetizable material.

19. A non-locking switch as claimed in any one of the preceding claims, characterized in that the measuring means (7) is a Hall generator.