WO2011067118A1

WO2011067118A1 - Suspension arrangement for cantilevers in audio cartrigdes

Info

Publication number: WO2011067118A1
Application number: PCT/EP2010/067672
Authority: WO
Inventors: Leif Johannsen
Original assignee: Ortofon A/S
Priority date: 2009-12-01
Filing date: 2010-11-17
Publication date: 2011-06-09

Abstract

The present invention relates to a cantilever suspension arrangement for supporting a cantilever for an audio cartridge, the arrangement comprising a front end being adapted to support the cantilever at a position between a stylus of said cantilever and a root end of said cantilever, said front end of said arrangement comprising a front end support structure comprisinga material exhibiting intrinsic damping properties at least along two substantially opposite directions. The arrangement allows that a cantilever can withstand VTFs up to around 10 grams in order to comply with demands from for example DJs. The present invention offers a balanced vertical compliance while leaving the lateral compliance essentially unchanged.

Description

SUSPENSION ARRANGEMENT FOR CANTILEVERS IN AUDIO CARTRIGDES FIELD OF THE INVENTION

The present invention relates to a suspension arrangement for cantilevers in audio cartridges. In particular, the suspension arrangement is adapted to provide a vertical support of cantilevers at axial positions away from the root of cantilevers in order to allow higher vertical tracking forces (VTF).

BACKGROUND OF THE INVENTION

JP 55 097 004 discloses a support member for audio cantilevers. The support member suggested in JP 55 097 004 is implemented as a linear spring being made of phosphor bronze. Thus, the support member suggested in JP 55 097 004 has no intrinsic damping properties. Moreover, the support member of JP 55 097 004 is only suitable for supporting cantilevers in one direction. According to the embodiments disclosed in JP 55 097 004 this one direction is the upwards vertical direction.

It is a disadvantage of the arrangement suggested in JP 55 097 004 that the phosphor bronze spring offers no damping properties.

It is a further disadvantage of the arrangement suggested in JP 55 097 004 that cantilevers are only supported in the upwards vertical direction since this makes the vertical compliance asymmetric.

Another prior art suspension arrangement for cantilevers is shown in Fig. 1. As depicted in Fig. la the suspension arrangement 1 is symmetric whereby the vertical and lateral compliances are equally influenced by the suspension arrangement. The prior art suspension arrangement 1 of Fig. 1 is typically made of an elastomer, such as rubber. As depicted in Fig. lb the suspension arrangement only supports the cantilever 2 near its rear end. In the prior art suspension arrangement shown in Fig. 1 the cantilever is kept in position by an engagement between a recess in the suspension arrangement and a collar on the cantilever. It should be noted that other types of fixation system are available in other prior art systems.

It is an object of embodiments of the present invention to provide a cantilever support member which maintains the symmetric vertical compliance of an unsupported cantilever. It is a further object of embodiments of the present invention to provide a cantilever support member which decreases the vertical compliance of an unsupported cantilever in order to be able to withstand a higher VTF.

DESCRIPTION OF THE INVENTION The above-mentioned objects are complied with by providing, in a first aspect, a cantilever suspension arrangement for supporting a cantilever for an audio cartridge, the arrangement comprising a front end being adapted to support the cantilever at a position between a stylus of said cantilever and a root end of said cantilever, said front end of said arrangement comprising a front end support structure comprising a material exhibiting intrinsic damping properties at least along two substantially opposite directions.

The cantilever suspension arrangement mentioned above may be mounted in professional audio cartridges of the type used by professional DJs. This type of audio cartridge differs from high end audio cartridges in that they are designed to be operated with a high VTF, this typically being in the range 3-5 grams. If traditional DJ cartridges normally applying VTFs between 3 and 5 grams are equipped with a cantilever arrangement according to the present invention VTFs of up to 10 grams may be applied. If traditional DJ cartridges are exposed to VTFs of 10 grams they will certainly not perform in an optimal way. In fact it may easily happen that the housing of the cartridge touches the record surface thereby causing a general malfunctioning of the cartridge. In the professional world of DJs the appliance of high VTFs makes it easier for the stylus to stay in the record groove during heavy scratching performances. In order to be able to withstand VTFs of up to 10 grams a suspension arrangement according to the present invention may advantageously be applied. In fact it may be applied as an add-on to already existing DJ cartridges. The front end support structure may be at least partly made of an elastomeric material, such as rubber. The support structure may be made of a single material or a combination of materials. Moreover, the suspension arrangement may be shaped so as to be attachable to a specific or a group of audio cartridges housings.

The front end support structure may comprise a through-going opening adapted to receive a cantilever. Within said through-going opening first and second supporting members may be provided. Said first and second support members may be adapted to abut oppositely arranged surfaces of a cantilever, respectively, when said cantilever is mounted in the arrangement. Preferably, the first and second support members are positioned so as to support the cantilever along a substantially vertical direction, i.e. along the upwards and downwards vertical directions.

The arrangement according to the first aspect of the present invention may further comprise a rear end support structure being adapted to support the cantilever at its root end, said rear end support structure comprising a material exhibiting intrinsic damping properties. The rear end support structure may be at least partly made of an elastomeric material, such as rubber. Preferably, the rear end support structure and the front end support structure is made of the same material.

The rear end support structure may comprise a through-going opening adapted to receive the root of a cantilever. Moreover, a recess may be formed in an inner side wall of said through- going opening of the rear end support structure, said recess being adapted to engage with a collar of a cantilever so as to keep the read end support structure and the cantilever in a mutually fixed relationship.

Preferably, the rear end and the front end support structures form a single elastomeric component. By combining the rear end and the front end into a single component the manufacturing of the cantilever suspension arrangement becomes significantly easier.

Moreover, the assembling process of the cantilever suspension arrangement and an audio cartridge housing becomes easier.

In a second aspect, the present invention relates to an audio cartridge comprising a cantilever suspension arrangement according to the first aspect of the present invention. The cantilever suspension arrangement may be secured to an audio cartridge housing by frictional forces. As already mentioned such audio cartridge may be of the type used by professional DJs and they may be designed to be operated with a high VTF, this typically being in the range 5-10 grams. In order to be able to withstand such a high VTF a suspension

arrangement may advantageously be applied.

In a third aspect the present invention relates to an audio cartridge comprising a cantilever and a cantilever suspension arrangement for supporting said cantilever at a position between a stylus of said cantilever and a root end of said cantilever, the arrangement comprising a front end support structure comprising a material exhibiting intrinsic damping properties, the front end support structure supporting the cantilever in such a way that a vertical compliance of the cantilever is essentially symmetric. The cantilever suspension arrangement may be secured to an audio cartridge housing by frictional forces. Again, this type of audio cartridge differs from high end audio cartridges in that they are designed to be operated with a high VTF, this typically being in the range 5-10 grams. In order to be able to withstand such a high VTF a suspension arrangement may

advantageously be applied. Preferably, the front end support structure supports the cantilever in at least two

substantially opposite directions at the position between the stylus and the root end of said cantilever, and the front end support structure may be at least partly made of an elastomeric material, such as rubber. Similar to the first aspect of the present invention the front end support structure may comprise a through-going opening within which the cantilever is inserted. The front end support structure may comprise first and second supporting members being essentially oppositely arranged within the through-going opening so as to abut oppositely arranged surfaces of the cantilever, respectively.

The cantilever suspension arrangement of the audio cartridge may further comprise a rear end support structure supporting the cantilever at its root end, said rear end support structure comprising a material exhibiting intrinsic damping properties, such as an elastomeric material, such as rubber.

The rear end support structure may comprise a through-going opening within which the root of the cantilever is inserted, and wherein a recess may be formed in an inner side wall of the through-going opening of the rear end support structure, said recess engaging a collar of the cantilever so as to keep the read end support structure and the cantilever in a mutually fixed relationship.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be explained in further details with reference to the accompanying figures, where Fig. 1 shows a prior art cantilever support arrangement, Fig. 2 shows a cantilever support arrangement according to a first embodiment of the present invention,

Fig. 3 shows the cantilever support arrangement according to the first embodiment inserted in an audio cartridge, Fig. 4 also shows the cantilever support arrangement according to the first embodiment inserted in an audio cartridge,

Fig. 5 shows a cantilever support arrangement according to a second embodiment of the present invention,

Fig. 6 shows the cantilever support arrangement according to the second embodiment inserted in an audio cartridge, and

Fig. 7 also shows the cantilever support arrangement according to the second embodiment inserted in an audio cartridge,

While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of examples in the drawings and will be described in detail herein. It should be understood, however, that the invention is not intended to be limited to the particular forms 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.

DETAILED DESCRIPTION OF THE DRAWINGS In general terms the present invention relates to a new way of mounting and suspending a cantilever in an audio cartridge so that the cantilever can withstand VTFs up to around 10 grams in order to comply with demands from for example DJs. The present invention offers a balanced vertical compliance while leaving the lateral compliance essentially unchanged. In fact, by selecting a proper material, the suspension arrangement according to the present invention may provide a lateral compliance which is higher than normal. A higher lateral compliance gives the cartridge a better tracking ability, especially for tracking very loud drum and bass tracks.

Fig. 2 shows a first embodiment of the present invention. As depicted in Fig. 2 the suspension arrangement comprises a front end 3 and a rear end 4. The rear end 4 corresponds to the prior art suspension arrangement shown in Fig. 1. Contrary to the rear end 4 the front end 3 of the suspension arrangement is not symmetric in that the front end 3 only supports the cantilever in a substantially vertical direction. As shown in Fig. 2a the suspension arrangement comprises a through-going opening through which the cantilever 2 is adapted to be inserted as depicted in Fig. 2b. A recess 5 is formed in the rear end 4 - this recess 5 engages with a collar of the cantilever in order to keep the cantilever 2 in a fixed relationship to the suspension arrangement.

As shown in Fig. 2a first and second supporting members 6, 7 are provided within the opening of the front end 3. The first and second supporting members 6, 7 abut and thereby support the cantilever in two opposite directions - cf. Fig. 2b. The side walls 8, 9 define the width of the opening in the front end 3. No support of the cantilever is provided in these transverse directions. For that reason the width of the opening in the front end 3, i.e. the distance between the side walls 8, 9, is made wider that the dimensions of the cantilever. Contrary to this the opening in the rear end 4 is dimensioned to support the cantilever in all radial directions in order to keep the cantilever in a fixed axial/longitudinal position relative to the rear end 4 by frictional forces.

The suspension arrangement depicted in Fig. 2 is preferably made of a compression mouldable elastomer, such as rubber. In particular, Brombutyl is a suitable material. It should be noted that the suspension arrangement may alternatively be made using a transfer or an injection mouldable process.

The length of the suspension arrangement is typically around 2 mm. As seen in Fig. 2a the cross-sectional shape of the front end 3 of the suspension arrangement is not completely circular. In fact the total height of the front end 3 is typically around 1.7 mm, whereas the total width of the front end 3 is typically around 2 mm. Fig. 3 shows an audio cartridge having a housing 10 with a suspension arrangement 11 and a cantilever 12 mounted therein. The suspension arrangement 11 is kept in position by frictional forces between the suspension arrangement and an appropriately shaped housing portion 13 of the audio cartridge.

Figs. 4a and 4b show a vertical and a horizontal cross-sectional profile of the audio cartridge depicted in Fig. 3, respectively. As shown in Fig. 4a the front end 14 of the suspension arrangement abuts both the upper and lower surfaces 15, 16 of the cantilever 17. Now referring to Fig. 4b no support is provided by the front end 20 of the suspension arrangement to the cantilever surfaces 18, 19. Thus, the front end of the suspension arrangement provides a symmetric support to the cantilever along a vertical direction, while at the same time, offering essentially no support to the cantilever along a lateral direction. Thus, the suspension arrangement offers a reduced, but balanced vertical compliance while leaving the high lateral compliance essentially unchanged. The reduced vertical compliance allows that the audio cartridge becomes operable with VTFs as high as 10 grams without the housing touching the surface of the record.

Fig. 5 shows another embodiment of the present invention. As depicted in Figs. 5a and 5b the front end 21 is separated from the rear end 22. This embodiment is particularly suitable for existing audio cartridges where the cantilever is suspended in the rear end 22 only. Thus, for existing audio cartridges the separated front end 21 may be considered an add-on in order to increase the allowable VTF from a few grams up to 10 grams.

The physical separation of the front end and the rear end has an additional benefit in that the front and rear ends can be made of two different materials having different hardness's. In this way the properties of the suspension arrangement can be custom-designed to fulfil specific demands. As depicted in Fig. 5a the front end suspension arrangement 21 comprises is asymmetric in that the front end 21 only supports the cantilever in a substantially vertical direction. As shown in Fig. 5a the front comprises a through-going opening through which the cantilever 23 is adapted to be inserted as depicted in Fig. 5b.

As shown in Fig. 5a first and second supporting members 24, 25 are provided within the opening of the front end 21. The first and second supporting members 24, 25 abut and thereby support the cantilever in two opposite directions - cf. Fig. 5b. The side walls 26, 27 define the width of the opening in the front end 21. No support of the cantilever is provided in these transverse directions. For that reason the width of the opening in the front end 21, i.e. the distance between the side walls 26, 27, is wider that the dimensions of the cantilever. The flange 28 may optionally be provided in order to secure the front end 21 to a housing of an audio cartridge.

The suspension arrangement depicted in Fig. 5 is preferably made of a compression mouldable elastomer, such as rubber. In particular, Brombutyl is a suitable material. It should be noted that the suspension arrangement may alternatively be made using a transfer or an injection mouldable process.

Fig. 6 shows an audio cartridge having a housing 29 with a front end suspension

arrangement 30 and a cantilever 31 mounted therein. The front end suspension arrangement 30 is kept in position by the flange 32 and an appropriately shaped housing portion 33 of the audio cartridge being adapted to engage with the flange 32. Alternatively, the front end suspension arrangement 30 may be kept in position by frictional forces between the front end suspension arrangement and an appropriately shaped housing portion of the audio cartridge. A separate rear end suspension arrangement 34 is also shown in Fig. 6.

Figs. 7a and 7b show a vertical and a horizontal cross-sectional profile of the audio cartridge depicted in Fig. 6, respectively. As shown in Fig. 7a the front end suspension arrangement 35 abuts both the upper and lower surfaces 36, 37 of the cantilever 38. Now referring to Fig. 7b no support is provided by the front end suspension arrangement 39 to the cantilever surfaces 40, 41. Thus, the front end suspension arrangement provides a symmetric support to the cantilever along a vertical direction, while at the same time, offering essentially no support to the cantilever along a lateral direction. Thus, the suspension arrangement offers a reduced, but balanced vertical compliance while leaving the high lateral compliance essentially unchanged. The reduced vertical compliance allows that the audio cartridge becomes operable with VTFs as high as 10 grams without the housing touching the surface of the record.

Claims

1. A cantilever suspension arrangement for supporting a cantilever for an audio cartridge, the arrangement comprising a front end being adapted to support the cantilever at a position between a stylus of said cantilever and a root end of said cantilever, said front end of said arrangement comprising a front end support structure comprising a material exhibiting intrinsic damping properties at least along two substantially opposite directions.

2. An arrangement according to claim 1, wherein the front end support structure is at least partly made of an elastomeric material, such as rubber.

3. An arrangement according to claim 1 or 2, wherein the front end support structure comprises a through-going opening adapted to receive a cantilever.

4. An arrangement according to claim 3, wherein the front end support structure comprises first and second supporting members.

5. An arrangement according to claim 4, wherein the first and second support members are essentially oppositely arranged within the through-going opening.

6. An arrangement according to claim 4 or 5, wherein the first and second support members are adapted to abut oppositely arranged surfaces of a cantilever, respectively, when said cantilever is mounted in the arrangement.

7. An arrangement according to any of the preceding claims, further comprising a rear end support structure being adapted to support the cantilever at its root end, said rear end support structure comprising a material exhibiting intrinsic damping properties.

8. An arrangement according to claim 7, wherein the rear end support structure is at least partly made of an elastomeric material, such as rubber.

9. An arrangement according to claim 7 or 8, wherein the rear end support structure comprises a through-going opening adapted to receive the root of a cantilever.

10. An arrangement according to claim 9, wherein a recess is formed in an inner side wall of the through-going opening of the rear end support structure, said recess being adapted to engage with a collar of a cantilever so as to keep the read end support structure and the cantilever in a mutually fixed relationship.

11. An arrangement according to any of claims 7-10, wherein the rear end and the front end support structures form a single elastomeric component.

12. An audio cartridge comprising a cantilever and a cantilever suspension arrangement according to any of the preceding claims.

13. An audio cartridge according to claim 12, wherein the cantilever suspension arrangement is secured to an audio cartridge housing by frictional forces.

14. An audio cartridge comprising a cantilever and a cantilever suspension arrangement for supporting said cantilever at a position between a stylus of said cantilever and a root end of said cantilever, the arrangement comprising a front end support structure comprising a material exhibiting intrinsic damping properties, the front end support structure supporting the cantilever in such a way that a vertical compliance of the cantilever is essentially symmetric.

15. An audio cartridge according to claim 14, wherein the front end support structure supports the cantilever in at least two substantially opposite directions at the position between the stylus and the root end of said cantilever.

16. An audio cartridge according to claim 14 or 15, wherein the front end support structure is at least partly made of an elastomeric material, such as rubber.

17. An audio cartridge according to any of claims 14-16, wherein the front end support structure comprises a through-going opening within which the cantilever is inserted.

18. An audio cartridge according to claim 17, wherein the front end support structure comprises first and second supporting members.

19. An audio cartridge according to claim 18, wherein the first and second support members are essentially oppositely arranged within the through-going opening.

20. An audio cartridge according to claim 18 or 19, wherein the first and second support members abut oppositely arranged surfaces of the cantilever, respectively.

21. An audio cartridge according to any of claims 14-20, further comprising a rear end support structure supporting the cantilever at its root end, said rear end support structure comprising a material exhibiting intrinsic damping properties.

22. An audio cartridge according to claim 21, wherein the rear end support structure is at least partly made of an elastomeric material, such as rubber.

23. An audio cartridge according to claim 21 or 22, wherein the rear end support structure comprises a through-going opening within which the root of the cantilever is inserted.

24. An audio cartridge according to claim 23, wherein a recess is formed in an inner side wall of the through-going opening of the rear end support structure, said recess engaging a collar of the cantilever so as to keep the read end support structure and the cantilever in a mutually fixed relationship.

25. An audio cartridge according to any of claims 21-24, wherein the rear end and the front end support structures form a single elastomeric component.

26. An audio cartridge according to any of claims 14-25, wherein the cantilever suspension arrangement is secured to an audio cartridge housing by frictional forces.