Patent Application
20050178644
The present invention relates to an integrated volume control and switch assembly comprising a combined potentiometer and switch function. In particular, the assembly is suitable for use in hearing aids and portable communication devices.
Known potentiometers may in addition to a variable resistance function have a built-in switch that provides the option of changing between first and second switch states via the potentiometer knob—typically in an extreme position of the potentiometer knob. The potentiometer may function as a volume control where the potentiometer knob upon turning in one direction decreases the volume, and finally turns off the signal and/or switches off power. Preferably, the user is provided with feedback indicating that the switch has reached an off state, e.g. light in a display or diode, a sound, a tactile mechanical resistance towards turning of the knob, or similar. In relation to volume controls for portable audio equipment feedback is often provided to the user by a tactile feedback upon turning a rotatable volume control knob to or beyond its lowermost position. Hereby, the user has a indication that the device has been switched off so as to save battery without the need for visual confirmation or feedback.
PJ 88 manufactured by the applicant is an example of a potentiometer with a built-in switch providing the user with a tactile feedback. PJ 88 is suited for miniature applications, such as a combined volume control and on/off switch in a hearing aid. PJ 88 provides a combined switch function and tactile feedback arranged by engagement of two metal springs upon interaction with a protrusion on a user rotatable part. The two metal springs are both engaged with the switch function as well as the tactile feedback function.
The combined switch and tactile feedback arrangement provided in PJ 88 has a number of disadvantages that are particularly troublesome with respect to further miniaturisation. The two metal springs are small when compared to an overall size of the potentiometer assembly. This means that the solutions are not suited for further miniaturisation, since a pure downscale of such potentiometers would include mechanical parts being too complicated to manufacture and handle in a cost efficient production process.
An additional problem with PJ 88 is that it is not possible to independently adjust an angular position of the user rotatable part where the switch function and the tactile feedback occur.
One object of the present invention is to provide an integrated volume control and switch assembly of a simple design that provides tactile feedback to a user of the assembly in connection with the switch function. The assembly must be suited for miniature applications, such as hearing aids, and still suited for cost efficient production.
An additional object is to provide an integrated volume control and switch assembly providing independently adjustable switch and feedback functions.
The mentioned objects are complied with by providing, in a first aspect, an integrated volume control and switch assembly comprising
It is understood that even though denoted “legs” the first and second conductive switch legs may be formed differently than long slim members or pins. For example the switch legs may be formed by conductive bumps adapted for soldering or they may be formed by pieces of Printed Circuit Boards (PCB), pieces of flexprint or flexible wires etc.
The invention is particularly advantageous in that it is possible to manufacture the assembly in miniature versions without the need for components being so small that they are difficult to handle in a mass production line. This is accomplished by the fact that the switch function and the tactile feedback function are formed by separate members.
Hereby, the separate members can be independently positioned in the assembly thus allowing each member to be located in positions with more space available.
An additional advantage is that the independent switch function and tactile feedback function allow independent choice of angular position of the rotatable member for switching and for tactile feedback. Once the assembly has been designed it is possible by simple changes to adjust a relative angular position of the rotatable member where switching and tactile feedback occurs—switching and tactile feedback need not be provided at the same angular position of the rotatable member.
The integral volume control and switch assembly may have the resilient tactile member (35) and the resilient conductive member (8) spatially separated along a rotational axis of the rotatable member (40). The resilient conductive member (8) and the switch legs (2,3) may constitute separate members.
The assembly may further comprise an intermediate link (20) rigidly connected to the rotatable member (40), the intermediate link (20) comprising a protrusion (21) being adapted to engage with the resilient conductive member (8) so as to either establish or break the electrical connection between the first (2) and second (3) switch legs.
The assembly may further comprise an intermediate housing (30) part being rigidly connected to the base plate (1), the intermediate housing part (30) having a top portion aligned with the base plate (1), wherein the top portion supports the resilient tactile member (35). The top portion of the intermediate housing part (30) may comprise an indentation (32) for guiding a first part (35a) of the resilient tactile member (35).
The rotatable member (40) may comprise at least one protrusion (39) adapted to engage with an engaging part (38) of the resilient tactile member (35).
The first part (35a) of the resilient tactile member (35) may be substantially U-shaped, and said first part (35a) being substantially perpendicular to the engaging part (38).
The at least one protrusion (39) of the rotatable member (40) may be adapted to engage with the resilient tactile member (35) so as to provide an audible feedback signal in addition to the tactile feedback. The predetermined angular position of the rotatable member (40) may be different from or equal to an angular position of the rotatable member (40) causing the resilient conductive member (8) to switch between the first and second switch states.
The resilient conductive member (8) may comprise a first part (9a, 9b) adapted to engage with the protrusion (21) of the intermediate link (20).
The resilient conductive member (8) may comprise a detent spring manufactured in a material selected from the group consisting of: stainless steel, spring steel, low carbon steel, metallic alloys and Palladium alloys. The resilient conductive member (8) may be manufactured monolithically.
The resilient tactile member (35) may comprise a detent spring manufactured in a material selected from the group consisting of: stainless steel, spring steel, low carbon steel, and Palladium alloys. The resilient tactile member (35) may be manufactured monolithically.
The assembly may further comprise a user operable knob (50) connected to the rotatable member (40), the user operable knob (50) comprising means for providing friction with a user's finger.
The base plate (1) may be manufactured in a material selected from the group consisting of: heat resistive thermoplastics, insulating ceramics, LCP, PVC, PE, PP, and Polyetheretherketone. The intermediate housing part (30) may be manufactured in a material selected from the group consisting of: insulating ceramics, PVC, PE, PP, and Polyamide.
The variable resistance means may comprise
The variable resistance means may further comprise a fifth conductive leg (12) electrically connected to a second end portion of the conductive path (14). The substrate (10) supporting the conductive path (14) may comprise a PCB.
As described for the conductive switch legs (2,3) it is understood that the term “leg” is not limiting with respect to third, fourth and fifth conductive legs (11,12,13). These conductive legs (11,12,13) may also be shaped as for example flexible wires, flexprint or bumps etc.
An outer diameter of the assembly may be in the range 1-4 mm, preferably in the range 2-3 mm. By an outer diameter is understood an outer diameter including a suitable outer protective housing part of the volume control and switch assembly.
A total height of the assembly is in the range 1,5-4,5 mm, preferably in the range 2,5-3,5 mm.
In a second aspect, the invention relates to a hearing aid comprising an integral volume control and switch assembly according to the first aspect.
In a third aspect, the invention relates to a portable communication device comprising an integral volume control and switch assembly according to the first aspect.
The present invention will now be explained with reference to the accompanying figures, where
While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown only by way of examples. However, it should be understood that the invention is not intended to be limited to the particular embodiments disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
The base plate 1 further comprises three holes 6 for receiving third 11, fourth 13, and fifth 12 conductive legs mounted on substrate 10. These legs 11,12,13 form the termination of the 3-pin potentiometer part of the assembly. One of conductive legs 11 or 12 may be omitted, if preferred, thus leaving the potentiometer part in a 2-pin version providing an adjustable resistance value between the two legs 11,13 or 12,13.
The base plate 1 also comprises an indentation 7 fitted to receive and support a resilient conductive member 8. The resilient conductive member 8 is a detent spring having a first part 9c positioned in the indentation 7 and second parts 9a, 9b oriented substantially perpendicular to the first part 9c. The second part 9a of the resilient conductive member 8 is intended to co-operate with a protrusion 21 of the intermediate link 20, in order to change switch state, i.e. establish or break the electrical connection between the two terminals 4, 5 and hence the first 2 and second 3 conductive switch legs. The indentation 7 is preferably wider near the point of engagement between the resilient conductive member 8 and the protrusion 21 so as to allow bending of the first part 9c of the resilient conductive member 8 positioned in the indentation 7.
The substrate 10 comprises a conductive path 14 on a surface thereof. Third and fourth conductive legs 11, 12 penetrate the substrate 10 so as to be electrically connected to opposite end portions of the conductive path 14. The fifth conductive leg 13 is preferably positioned near the centre of the substrate 10 as the fifth conductive leg 13 is adapted to be in electrical contact with a centre mounted contact element 23 of a slidable contact 22 formed as a wiper, the slidable contact 22 further having a contact point 24 adapted for electrical contact with the conductive path 14. Preferably, the substantially circular substrate 10 comprises an indentation 16 so as to let the second part 9a, 9b of the resilient conductive member 8 extend above the substrate 10.
The intermediate link 20 has the slidable contact 22 rigidly mounted to its lower side. In a well-known manner the conductive legs 11, 12, 13, the conductive path 14, and the slidable contact 22 are capable of constituting a conventional voltage divider where the rotation of the conductive wiper 22 provides two mutually dependent variable resistance values between the third conductive leg 11 and the fifth conductive leg 13, and between the fourth conductive leg 12 and the fifth conductive leg 13, respectively.
As mentioned, the intermediate link 20 comprises a protrusion 21 adapted to engage with the second part 9b of the resilient conductive member 8. The protrusion 21 is preferably manufactured in a material appropriate for the engagement with the resilient conductive member 8, such as insulating ceramics, PVC, PE, PP or similar. Polyamide 6.6 with 50% glass is a preferred choice of material for the intermediate link 20. Preferably, the intermediate link 20 and the protrusion 21 are manufactured, e.g. moulded, in one piece to simplify manufacturing.
An intermediate housing part 30 comprises a through-going opening 31 suited for receiving and preferably supporting the intermediate link 20 in such a way as to allow the intermediate link 20 to rotate at least part of a full revolution. The intermediate housing part 30 preferably comprises a U-shaped indentation 32 adapted to receive and support a resilient tactile member 35 formed as a detent spring. The leg parts of the U-shaped indentation 32 are wider than the bottom part of the U-shaped indentation 32 so as to allow bending of a first part 35a of the resilient tactile member 35 when positioned in the leg parts of the U-shaped indentation 32. The resilient tactile member 35 comprises a second part 38 oriented substantially perpendicular to the first part 35a. The intermediate housing part 30 preferably comprises a projection part 36 that supports the rotatable member 40. In addition, the projection part 36 serves as stopping means by preventing damage of the assembly that would occur by overturning the rotatable member 40. As the rotatable member 40 is turned in one direction relative to the intermediate housing part 30 a protrusion 39 (further described in the following) of the rotatable member 40 will at one point of the rotation engage with the projecting part 36 that will thus hinder further rotation of the rotatable member 40 in the same direction. The same applies by rotation of the rotatable member 40 in the opposite direction. The intermediate housing part 30 also comprises an outer projection 33 for easy and reliable mounting/fixing of the assembly in a device, such as in a face plate of a hearing aid.
The resilient conductive member 8 is formed as a separate member from the contact parts 4,5 with which the resilient conductive member 8 is adapted to engage. If preferred, the switching mechanism according to the invention may be arranged so that the resilient conductive member 8 can be formed integral with one of the contact parts 4,5 and consequently integral with one of the conductive switch legs 2,3.
A rotatable member 40 is rigidly connected to the intermediate link 20 in order to transfer rotational displacement of the rotatable member 40 to the intermediate link 20. Preferably, the rigid connection is established bydesigning the rotatable member 40 and the intermediate link 20 to be combined or forced together in a locking engagement. Alternatively, the rotatable member 40 and the intermediate link 20 are joined by welding, gluing or similar. Rotation of the rotatable member 40 and the intermediate link 20 is preferably performed around a substantially central axis of the assembly. Preferably the fifth conductive leg 13 is also positioned in the axis of rotation.
A knob 50 for user friendly interaction may be provided on top of the rotatable member 40 so as to allow a user to easily operate the assembly. The knob 50 is preferably joined to the rotatable member 40 by fastening on a central projection 41 of the rotatable member 40 and an indentation 42 of the rotatable member 40, e.g. by a locking engagement or similar methods. The knob 50 shown has a number of wings adapted to provide sufficient friction to a user's finger during operation. The knob 50 may be omitted if preferred or made integral with the rotatable member 40.
The angular difference between change of switch state and tactile feedback can be adjusted on the shown embodiment in several ways. For example the rotatable member 40 may be turned into another angular position when locked into engagement with the intermediate link 20. Another way to adjust the switch function in relation to the tactile feedback is by providing a rotatable member 40 with its protrusion 39 positioned at another angular position relative to its locking mechanism for engagement with the intermediate link 20. Still another way of adjusting the switch function in relation to the tactile feedback is by providing an intermediate link 20 with its protrusion positioned at another angular position relative to its locking mechanism for engagement with the rotatable member 40.
The detailed kind of engagement between the protrusion 39 and the second part 38 of the resilient tactile member 35 can be performed in a variety of ways and a variety of tactile and also acoustic effects experienced by a user can be obtained. Due to the fact that the tactile feedback arrangement, formed by the resilient tactile member 35 and the protrusion 39, is separated from the switch arrangement formed by the protrusion 21 of the intermediate link 20 actuating the second part 9b of the resilient conductive member 8, a variety of different schemes for timing of tactile feedback relative to the electrical switch function can be provided. Only a few examples will be given below.
In a first embodiment of the engagement between the protrusion 39 and the second part 38 of the resilient tactile member 35 the protrusion 39 has a slope as viewed in a profile view that bends the second part 38 of the resilient tactile member 35 away from its equilibrium position upon engagement. The engagement provides the user with an increasing mechanical resistance towards rotation of the rotatable member 40 depending on the rate of increase of the slope and a stiffness of the resilient tactile member 35. In particular the stiffness of the second part 38 of the resilient tactile member 35 but also a stiffness of the first part 35a of the resilient tactile member 35 influences the mechanical resistance that will be experienced by the user. Preferably, the slope of the protrusion 39 has a linear slope, but as an alternative to a linear slope, the slope might have a concave shape, a convex shape, a step-ladder shape, or similar. Preferably, a surface of the protrusion 39 is coated or treated to facilitate different kinds of engagement with the second part 38 of the resilient tactile member 35.
So as to protect the potentiometer part from dirt and moist, the intermediate link 20 is fitted to the opening 31 in the intermediate housing part 30 substantially water-tight. This is crucial for example for hearing aid applications where it is essential that the volume and switch assembly is capable of reliable operation in a humid environment, i.e. the assembly needs to be at least substantially sweat-tight.
In a second embodiment of the engagement between the protrusion 39 and the second part 38 of the resilient tactile member 35, the protrusion 39 has a maximum as viewed in a profile view. In this embodiment the user experiences an initially increasing mechanical resistance towards rotation of the rotatable member 40 being similar to the first embodiment described above. However, as the second part 38 of the resilient tactile member 35 reaches the maximum, the mechanical resistance will decrease relatively upon further rotation of the rotatable member 40, thus providing the user with a different type of tactile feedback relative to the first embodiment. Preferably, the protrusion 39 has more than one maximum as viewed in a profile view.
In a third embodiment of the engagement between the protrusion 39 and the second part 38 of the resilient tactile member 35, the protrusion 39 has an abrupt or discontinuous maximum following by a steep decline as viewed in a profile view. This can be considered as a special case of the second embodiment described above. The steep decline allows the second part 38 of the resilient tactile member 35, at least for a short period of time, to accelerate towards a stop part of the protrusion 39 to provide a mechanical impact by the second part 38 of the resilient tactile member 35 on said stop of the protrusion 39. This mechanical impact will result in an audible sound to the user, thereby informing the user about the change of switch state of the assembly via an audible click sound. Preferably, the audible sound is combined with a mechanical tactile feedback.
Optionally, the protrusion 39 is specifically treated or prepared at the point of the mechanical impact to enhance the audible sound. The protrusion may e.g. be metallised or similarly. In addition, the rotatable member 40 and/or the knob 50 may be designed specifically with respect to enhance their ability to transmit vibrations resulting from mentioned impact so as to enhance the acoustic signal radiated by external elements of the assembly, such as the knob 50.
As seen from
Due to its conductive function the resilient conductive member 8 is preferably formed by an electrically conductive material. However, the resilient members 8, 35 may be formed by different materials. The resilient tactile member 35 may be formed in an electrically non-conductive material such as a polymeric material that is capable of providing a spring effect so as to provide a tactile sensation to a user upon interaction of the resilient tactile member 35 with the protrusion 39 of the rotatable member 40.
Preferred materials for the resilient conductive member 8 is Paliney 6, i.e. a Palladium-Silver based alloy. Another suitable material for the resilient conductive member 8 is Hera, which is a Palladium, Copper, Silver and Nickel based alloy. The same materials mentioned for the resilient conductive member 8 are also suitable for the slidable contact 22. The resilient tactile member 35 is preferably manufactured in stainless steel such as W No. 1.4310. At least the material for the resilient tactile member 35 must provide a spring effect. All terminals, i.e. conductive switch legs 2, 3 as well as conductive legs 11, 12, 13 are preferably manufactured in a silver alloy plated with 2 μm gold, such as AgCu 97/3. Preferred materials for intermediate link 20, intermediate housing part 30, rotatable member 40 as well as knob 50 is Ultramid A3EG10, i.e. Polyamide 6.6 comprising 50% glass. Materials for the base plate 1 must be able to withstand heat from welding. A preferred material for the base plate 1 is Victrex PEEK GL30, i.e. Polyetheretherketone comprising 30% glass.
In principle, the assembly can be brought into the same switch state by turning the rotatably mounted elements 20, 40 and 50 in the opposite direction so that the protrusion 21 engages with the other leg 9b of the second part 9a,9b of the resilient conductive member 8 so as to break the electrical connection between the contact terminal 4 and the resilient conductive member 8. However, preferably as described in connection with
As it is seen from
A volume control and switch assembly according to the invention and according to the shown embodiments may be manufactured in a variety of sizes adapted to fit into different miniature applications such as portable audio devices for entertainment such as portable MP3 players, CD players or portable radios. The assembly may also be manufactured in sizes small enough to fit hearing aid applications while still acceptable with respect to large scale manufacturing.
