DE2923500A1 - TONE ARM FOR RECORD PLAYER - Google Patents

Description

The present invention relates to a tonearm for record players, consisting of an elongated lightweight arm as well as a front and rear section, a cartridge in the front section of the arm, Fastening means which are connected to the arm and fasten it in a cantilevered manner about a pivot point, the disposed between the front and rear sections and one on the rear section of the arm arranged counterweight.

Turntable tonearms are very critical mechanisms which particularly affect the quality of the recorded signals from the record or the like, which are converted into electrical Signals are converted, amplified and finally converted into Sehall. Step on such tonearms always have dynamic problems caused by the spinning record.

The record is often not even, and thus the needle of the cartridge on the tonearm can follow the groove in the record, the cartridge must see moving up and down. Such a movement leads to the fact that the groove guide force of the needle on the Record changed a lot. Of course, this variation especially changes the effect of the groove vibration waves on the stylus,

Furthermore, the record wheels are often not complete concentric to the center opening of the record. Accordingly, the tonearm oscillates horizontally under the Influence of the sides of the record grooves that press against the needle. Of course, such a horizontal changed Oscillation is the force or pressure that keeps the needle engaged with the record, which leads to changes in the effective signal that carries out

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the use for reinforcement is generated.

Such dynamic properties can be relatively uniform or even abrupt. Rapid changes in the position of the tonearm and the influence of the record cause significant changes in the tone or the generated signals and also contribute to significant wear and tear on the record.

Although counterweights have previously been used on such tonearms, such counterweights are not special

ormt or so arranged to have the effect of a . significant movement and oscillation of the tonearm in relation to the type of signal or sound produced and likewise to minimize the wear and tear on the record.

The present invention therefore relates to the construction of tonearms and especially their counterweights in relation to the length and weight of the front end of the tonearm, taking into account the size and type of the pick-up cartridge, the lever arm and the stylus will..

In particular, the tonearm according to the invention is constructed in such a way that it acts as a counterweight of very significant weight includes, which is arranged on the rear end of the tonearm, but at the center of rotation of the tonearm. The tonearm and the counterweight arranged on the opposite sides of the pivot point are in static equilibrium. In most cases the counterweight is a body of revolution or a slight variation of it moves around an axis that extends through the center of gravity of the counterweight.

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Another important aspect of the tonearm is the moments of inertia of the front and rear sections of the tonearm on the opposite sides of the pivot point. The moments of inertia are · important, both accordingly to the horizontal as well as to the vertical axis through the pivot point and across the arm. In general is the moment of inertia of the arm in front of the pivot point, including the cartridge and stylus and mounting head For the customer it is primarily important because of the arm length and because the center of gravity is an important one Distance from the pivot point is arranged. It should be noted that the moment of inertia is squared the distance changed.

Although the counterweight of the invention has a significant weight, the moment of inertia of the counterweight portion is of the tonearm is unusually small, mainly because the front surface of the counterweight is attached to the pivot point adjoins. Accordingly, the center of gravity of the counterweight is also extremely close to the pivot point to minimize the moment of inertia of the counterweight portion of the arm.

In one form of the invention, the position of the counterweight can be adjusted in a direction along the arm axis even though it is adjacent to the pivot point.

In order to quantify certain aspects of the invention, it is helpful to compare the moment of inertia of the sections of the tonearm in front of and behind the pivot point to look at each other.

The ratio of the moment of inertia of the portion of the tonearm including the counterweight behind the

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Pivot point to the moment of inertia of the part of the tonearm, including the insert and the needle in front of the pivot point, should be as low as possible. This ratio is with the best prior art tonearms known methods have been measured and reported as 0.18 to 0.25; in contrast, the conditions are in the case of the invention Model tone arms have been measured to be 0.098 to 0.13 using the same procedures. As some of the basic Data on which these relationships are based are estimated or, to a certain extent, determined subjectively, and Because of the adjustment capability of the tonearms, the exact values of such ratios can change somewhat, however, because of the use of the same procedure in establishing the above ratios, it arises a surprising difference in the proportions of the invention Tonearms versus the best of the State of the art.

According to the invention, the counterweight can be designed differently in terms of its shape. Only minor differences can be found when tonearms with different counterweight shapes are used, provided that the other or inventive criteria to which reference is made are met. It can be considered that the counterweight should ideally be an ellipsoid with its axis extending along the arm axis, with its length between the ends and along the axis being substantially less than the maximum diameter, and with one end of the ellipsoidal counterweight is arranged at the pivot point. Such shaped and disposed counterweight has a minimum moment of inertia about a horizontal axis (Z) which extends through the pivot point and lower ^"ch ^ ur axis (X) of the arm;?. It also has a minimal moment of inertia about a vertical axis (Y), which also passes through the pivot point

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ORIGINAL INSPECTED

and is perpendicular to the axis of the arm.

However, other forms of counterweights are almost as satisfactory. E.g. a cylindrical counterweight, with an end face adjacent to the pivot point and having a minimum moment of inertia, similar to that of the ellipsoidal counterweight.

However, the counterweights according to the invention can also have other shapes, such as a hemisphere, where its front face is adjacent to the pivot point, or a hollow hemisphere on a core, so that the periphery is cut of the core in a front and rear direction can be adjusted. Further others according to the invention Shapes include a truncated cone with its axis extending along the arm axis and the largest circular or the versatile end face is at the pivot point; the truncated cone can have a cylindrical base section, whose end face is adjacent to the pivot point. Rounded surfaces can be replaced by several planes Surfaces which, overall, have approximately the shape of such rounded surfaces. Furthermore, the counterweight have a different shape than that of the body of revolution, e.g. a half cylinder, which with its elongated diameter surface adjacent to the pivot point and perpendicular to the arm axis, which is the diameter area in the center the two ends intersect or e.g. a cube that is adjacent to the "pivot point.

An adjustable counterweight can in some cases move part of its weight in front of the pivot point, or alternatively a stationary counterweight can be arranged with a part in front of the pivot point. One of those Part in front of the pivot point contributes significantly to the heaviness,

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while it only changes the moment of inertia a little, because it is so close to the pivot point.

The stable mass of the counterweight is of particular importance with regard to the tendency for vibrations in the arm to prevent the vibrations from being fed back to the needle and to minimize vibration reflections. The mass at the fulcrum or oscillation point creates a useful substitute for the mass of the pickup insert, the It would be particularly valuable in preventing external vibrations from the needle, lever arm, and other parts of the insert without the other parameters, e.g. the excessive moment of inertia caused by the considerable mass of the Use would be generated.

The results obtained with the tonearm of the present invention as a result of using the tonearm are significant and numerous. The bass notes produced have less distortion; and the bass frequencies come with better matching amplitudes compared to what is on the record.

The needle of the insert is also better suited to precisely follow the sensitive grooves in the record; and whereas, in fact, all of the inserts indicate a minimum recommended groove force is used the present invention has a groove force that is either at or below the recommended minimum groove force is actually for all stakes, which leads to the stake and the record are considerably less worn and which further results in the sound produced being more open and lively.

Furthermore, by using the invention there is a better separation of the high frequencies between the channels, i.

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the channels overlap less (less cross-talk). In this respect, it is better to play a bent or curved record with significantly fewer changes in the groove guide force that occurs due to the deformations in the record.

Due to the tonearm according to the invention, the records continue to wear less; being less stress and less forces are exerted on the needle and boom assemblies.

The minimization of the vibrations had already been shown.

Another significant benefit concerns the fundamental Resonance of the tonearm system. Typically, the fundamental resonance of a tonearm system is 7 to 10 cycles per second area; mainly because of this frequency range is below the frequencies that are commonly heard, and this frequency range is also above those frequencies that create significant instability. According to the invention, however, it is special Meaning that the amplitude peaks of the vibrations are considerably lower due to the basic resonance are than those of the prior art; the amplitude range is in the range of a 3 dB peak, compared to a 6 to 9 dB peak amplitude in the known best Prior art tonearms.

The invention can be summarized as follows:

A tonearm for turntables, consisting of an elongated Tonearm, a lightweight construction that has an insert and needle on its front end, and a counterweight carries on its rear end, with the opposite or

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equilibrium to the center of oscillation or rotation of the tonearm with its front. ¹ adjoins or adjoins the center of rotation, wherein the counterweight and the front portion of the arm are in static equilibrium and wherein the counterweight has a minimum moment of inertia, particularly in relation to the moment of inertia of the front portion of the tonearm, and wherein the counterweight have a variety of shapes can represent the body of revolution around the longitudinal axis of the tonearm. Typical counterbalance shapes include the hemispherical shape, the ellipsoid, the semicylinder that is aligned transversely to the tone arm, as well as cylinders that are longitudinally aligned with the tone arm and truncated cones also aligned longitudinally with the tone arm, including flat-sided truncated cones and other variations of common shapes.

In the following, preferred exemplary embodiments of the invention are described in more detail in conjunction with the figures.

It shows:

Fig. 1 is a side view, partially in section, of a tonearm according to the invention,

Fig.la a sectional view in detail along approximately the line Ia-Ia in Fig. 1,

Fig. 2 is a plan view of a modified form of a tonearm;

Fig. 3 is a side view of the tonearm of Fig. 2,

FIG. 4 is a detailed sectional view along approximately line 4-4 of FIG. 3;

Fig. 5 is a detailed plan view of the counterweight section a second modified form,

Fig. 6 is a side view of the counterweight portion of the tonearm shown in Fig. 5;

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Pig. 7 shows a detailed sectional view, along approximately the line 7-7 in FIG. 6,

8 is a detailed plan view of the counterweight section a third modified form according to the invention,

Fig. 9 is a side view of the mold shown in Fig. 8;

FIG. 10 shows a sectional view in detail, along the line 10-10 in FIG. 9,

Fig. 11 is a plan view of a fourth modified form of the invention;

Fig. 12 is a side view of the mold according to the invention shown in Fig. 11;

13 is a detailed sectional view along the line 13-13 in Fig. 12,. -

14 is a top plan view of a counterweight portion a fifth modified form according to the invention,

Fig. 15 is a side view of the shape shown in Fig. 14;

Fig. 16 is a detailed sectional view taken along the line 16-16 in Fig. 15 ""

17 is a plan view of a counterweight portion of a sixth modified embodiment of the present invention Shape, .

Fig. 18 is a side view of the mold shown in Fig. 17;

19 is a detailed sectional view taken along the line 19-19 in FIG. 18;

Figure 20 is a top plan view of a counterweight portion a seventh modified form of the invention,

FIG. 21 is a side view of the mold according to the invention shown in FIG. 20;

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Pig. 22 is a cross-sectional view taken along line 22-22 in FIG. 21;

Fig. 23 is a plan view of still another modified one Shape of the counterweight section of a tonearm according to the invention,

Fig. 24 is a plan view of a counterweight portion of still another modified one form according to the invention,

25 is a detailed plan view of a counterweight section yet another modified form of the invention,

FIG. 26 is a side view of that shown in FIG

Shape showing the position of some parts in dashed lines,

Fig. 27 is a side view in detail of a counterweight portion yet another modified form of the invention, and

FIG. 28 is a sectional view taken along line 28-28 in FIG. 27.

A basic form according to the invention is shown in FIGS. 1 and la. The panel 10 is part of the Frame structure which carries the tonearm of the record player, which is generally designated by the number 11 and also carries other significant parts of the turntable, e.g. the turntable, the drive motor and therewith related mechanisms and control devices.

The tonearm 11 comprises an elongated arm 12, the front part or front portion 13 of which is a lightweight metal tube made of such a material as aluminum, so that the front part of the tonearm is as light as possible is while it is still sufficiently stiff and coarse that

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it can be handled properly and normally. A fastening head assembly 14 is attached to the front end of the pipeline 13 and provides for the fastening of the pickup insert or the exchangeable scanning system 15. The insert 15 carries a lever arm 16 _a at the front end of which a pickup needle 17 is attached, which can be brought into engagement with the grooves of the record. Normally, the needle 17 has stereo properties in order to pick up two sets of vibration waves on the opposite sides of the grooves of the record and respond accordingly. The mounting structure 1H accommodates the insert and secures it in an extremely stationary position. The exact nature of the insert 15, the lever arm 16, the needle 17 and the fastening structure Ik and tube 13 are well known to those of ordinary skill in the art, so that a further detailed description for an understanding of the invention is unnecessary. The inserts vary widely in shape, size, and properties, and * will be known to those of ordinary skill in the art * how they have varying degrees of sensitivity. The insert 15 is connected to cables 18 which suitably pass through the pipe 13 to deliver the signals generated by the insert 15 to the amplifier of the turntable. Also, the particular manner in which these conduits or cables extend through tube 13 has little or nothing to do with the present invention, which technology of handling the cables emanating from the insert is again well known to those of ordinary skill in the art.

The tube 13 is at its rear end on a fastening ' Sleeve 19 attached, which provides for the attachment of the arm to the panel 10. A support 20 is provided with a threaded fitting 21a through which the support

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is firmly clamped to the panel 10 so as to come into a stationary position on the panel. One, traverse 21 is attached to the top of the support 20 and has a rear portion or end 22 which is spaced from the support 20 for securing the arm 12. The front part of the cross bar or traverse 21 extends from the support 20 to the front to the support or Bracket 23a to support the front part of the arm when the arm is outwardly away from the record player is swung and serves to keep it in a position of rest. A mounting structure that generally is indicated by the numeral 23, carries the entire Tonearm 11 for rotating or oscillating or pivoting movement, basically about the axis Z, which extends horizontally and transversely to elongate arm 12 and through the center of rotation created by mounting structure 23; and also a vertical one Axis Y extending vertically through the pivot point created by mounting structure 23 and to the elongated arm 12 runs transversely. In this in Figs. 1 and la The particular form shown, the fastening structure or the fastening assembly 23 also takes a limited one Self-rotation about an axis X which extends longitudinally from the arm and through the center of rotation defined by the mounting structure 23 is created.

Accordingly, the center of rotation is located at the intersection of the three axes X, Y and Z, which are mutually exclusive are perpendicular to each other. This type of mounting structure 23 can be called single-point support, since the entire arm is pivoted around a single element or ball bearing 24 which is concentric to the center of the pivot point. the Ball 24 is on a downward support and Socket 25 carried, which is attached to the bracket 19 at the rear end of the tube 13. The single ball 24 is on

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ORIGINAL INSPECTED

a plurality of balls, a ball bearing 26, supported, d-ns arranged in an annular manner and by a Bracket 27 is limited, which forms a suitable race for the balls 26. The bracket 27 has a, dependent mounting stem, which is attached to the rear end 22 of the cross member A.

The tonearm 11 has a counterweight C to the right of the pivot center, which is formed by the ball 2k .

The counterweight C has two basic components in this embodiment, namely a stationary cylindrical head 28 which is formed in one piece on the arm mounting sleeve 19 and a generally hemispherical hollow weight 29 with an essentially cylindrical cavity 30 which telescopically accommodates the head 28. The weight 29 is slidable on the head 28 to allow a limited adjustment of the arrangement of the center of mass of the üfc ^ i-iü / üwichtüs G, and, as in Pig. I gezei _o t is the weight can result from the continuous line in by fj ·:>} temperate position to be moved as well to the other shown in dashed line position P Luid Γ ¹ both the one: ■.

The Koj-f 28 and the weight 29 are both made of steel, however it is Mii '.' Rkaniit that a significant part of 28 and / or 29 eng counterweights are made of other high density materials, e.g. lead or a number of other metallic or mineral-like materials Materials can be made. The counterweight 10, as shown in Fig. 1, has the shape of a body of revolution about the axis X, and the periphery of the weight 29 has approximately the shape of a half-length. The counterweight has a front surface 31 which is substantially flat and which is arranged in abutting relation to the vertical plane defined by the axes XZ ..

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In this form, the head 28 has a threaded opening 32 therein, with a screw 33 in it Opening is screwed and on an end wall 34 of the hemispherical weight 29 is rotatably supported. The screw 33 has a knurled thumb grip and a retaining ring on the inside of the wall 34 so that, when the screw is rotated, the hemispherical weight 29 along the longitudinal arm or substantially along the X-axis is set.

The sections of the tonearm 11 in front of (on the left in Pig. I) and behind (on the right in Fig. 1) the center of rotation which is formed in the case of the ball 24 are essentially in static equilibrium. In more technical terms, this means that their first moments are essentially the same. Since the front surface of the counterweight is at the center of rotation, the counterweight C according to the invention is and must be extremely massive or heavy so that this position lies against or adjoins the center of rotation. In this special form of the B ¹ Ig. 1 and la arm, the position of the center of gravity of the counterweight 10 can be adjusted in such a way that an adjustment of the groove guide force exerted by the needle on the record is set. Accordingly, the tonearm can accommodate any number of consumables produced by different manufacturers and having different properties, whereby the position of the counterweight can easily be adjusted to the desired groove depth. reach au.

I) ¹ H. rdymlich extreme M;.: - ü i r.keit dos no ^ eritfowichtes G creates a multitude of IV> 1 ι ·! As has been explained by ei r- ^ a * ¹ · .. :: ■ "·. In particular, the manse leads to minimizing or preventing the vibrations or oscillations in the arm and also prevents vibration feedback to the needle.

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^ - ■ - ■ ». • ■ τ ··" J ₁ "

BATH

The counterweight has its center of mass very close to the center of rotation and accordingly, although the counterweight is very heavy by its nature, has a minimal moment of inertia which changes with the square of the distance between the center of rotation and the center of mass of the counterweight. Accordingly, all of the numerous advantages already detailed above are achieved and. particularly the ability to play records bent, without causing further wear or damage of the disc or of the needle, wherein the ^peak: amplitudes of the vibration caused by the resonance of the fundamental Tomirma irrinimiert.

While other forms of counterweights may have a moment of inertia that is slightly less than the moment of inertia The hemispherical shape shown in Fig. 1, however, is the moment of inertia of the counterweight, the adjoining the threatening or pivoting center, as shown in Fig., of the same order of magnitude as the minimal possible moment of inertia that is achieved with ideal counterbalance shapes and andex'en ideal conditions.

Kb .IjL important to note that the inventive structure and the inventive arrangement of the counterweight significant and surprising improvements in the clay outlet glue system can be determined. In those counterweights dot'on front side or front surface adjacent to the pivotal center of the tone arm, the ratio of the moment of inertia of the counterweight section of the tone arm to the rear pivot or rotation center as compared to the moment of inertia of the tone arm in front of the pivoting or center of rotation, ' including the tube 13, the attachment I ¹ I and the insert minimal and surprisingly less than it has been previously with known tonearms. As this ratio decreases'

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and has been minimized, the operating characteristics free faithful audio or sound reproduction have been increased and maximized.

Under certain conditions and with the use of certain cartridges, one can find that while the Weight 29 of the counterweight forward to position P is moved, a significant part of the counterweight are arranged in front of the center of rotation or pivoting. This can be necessary to achieve a reasonable balance in front of and behind the center of rotation. Although part of the Counterweight is arranged in front of the center of rotation, this effect is on the moment of inertia of the tonearm in front of the center of oscillation negligible, since the part of the counterweight that is located in front of the center of oscillation is its own Has a center of mass that is very close to the center of vibration; and there is the moment of inertia with the square the distance between the center of gravity and the center of gravity changed, this small part of the front of the center of oscillation is arranged counterweight minimal or has a negligible effect on the total moment of inertia deü part of the tonearm lying in front of the vibration center.

So far, only the swinging of the tonearm 11 about the Z or transverse horizontal axis is due to the swinging center has been emphasized, but the same considerations apply to the swinging of the tonearm around the vertical Y-axis through the center of oscillation. The moment of inertia of the counterweight C around the Y-axis corresponds essentially to that around the Z-axis; and equally is the moment of inertia of the tonearm in front of the center of oscillation on the Y-axis is essentially the same as the moment of inertia of the same part of the tonearm around the Z-axis. Accordingly, although the record is no longer flat, it is wavy and not is more round, so that when the record runs down a side

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lent vibration of the tonearm occurs, obtained by the use of the tonearm according to the invention improved operating properties, due to the minimal moment of inertia of the counterweight section, _t whose front surface is in adjacent relationship to the center of rotation.

In den_Fig. 2 through 28, all of which are somewhat schematic, become various forms of counterbalance and counterbalance systems along with some changes in the mounting structure to determine the swing center. In the tonearm 11.2, which is shown in Figs. 2 to 4, the counterpart C.2 is hemispherical, with its plane Pront surface 31.2 adjoins the center of oscillation, which is the Intersection of the axes Y and Z lies.

In this embodiment, the mounting structure 2J.2 al has for the tone arm 11.2 a Doppelgimb _v, which has a fixed outer ring 35 on a stationary base 36, wherein a pair of pivot pins 37 on the Y-axis pivotally supports a second Gimbalring to oscillate about the Y Fasten the axis around. The ring 38 has a pair of pivot pins or bolts 39 _} which lie opposite one another on the Z-axis and which fasten the counterweight C.2 rotatably. In this construction, the counterweight C.2 has fastening eyes Ίθ on its opposite sides which protrude slightly from the front surface 31 * 2. The double gimbal attachment 23 · 2 for the tonearm completely absorbs the necessary vibrations of the tonearm around the Y and Z axes. It is thought that in this embodiment of the counterweight an adjustability as in Pig. I is not necessary and that a rubber O-ring 41 between 'the head 28 and the weight 29 is also unnecessary.

In don Pip · ,. 5 to 7 the tonearm 11.3 is shown, which is a Ha'Lbkugel blown counterweight C.3 used, with a Single point storage, shown schematically and with 24.3 is marked. Again, the front surface borders 31 * 3 of the counterweight to the center of oscillation at the intersection of the Y and Z axes.

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When shown in Figs. 8 to 10 according to the invention Embodiment, the tonearm 11.4 has a counterweight C. with a 'cylindrical shape whose longitudinal axis runs along the tone arm and essentially on the X-axis extends. The front surface 31.4 of the counterweight is located perpendicular to the axis of the cylindrical shape and is adjacent to the center of oscillation 24.2 at the intersection of the Y and Z-axis on.

In the embodiment according to the invention shown in FIGS. 11 to 13, the tonearm 11.5 has a counterweight C.5j which is designed as a half cylinder. The axis of the semi-cylindrical counterweight C. 5 extends horizontally along the Z-axis and runs transversely to the elongated tonearm. The front surface 31 * 5 of the counterweight adjoins the oscillation center 24.5. This counterweight C.5 is an example of a number of counterweights, which, while having minimal moments of inertia about the Z and Y axes, are not bodies of revolution. While that Moment of inertia about the Y-axis can deviate somewhat from the moment of inertia about the Z-axis, creates the mass of the counterweight and its contiguous relationship with the center of vibration have essentially the same advantages as above have already been enumerated.

In FIGS. 14 to 16, the tonearm 11.6 has a counterweight C.6 with the shape of an ellipsoid, the axis of which extends lengthways to the elongated tonearm and adjoins the oscillation center 24.6. The ellipsoidal shape of the Counterweight C.6 is arranged along the X-axis, this length being slightly less than the maximum diameter of the ellipsoid in the direction perpendicular to the X-axis.

It should be noted that the front surface 31.6 of the ellipsoidal counterweight is somewhat convex in relation to the

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The front part of the tonearm is bent is unequal to the flat surface 31 of the counterweight C of the Pig. I and similar to the flat surfaces of the other shapes. It has been found that the counterweight C.6 with the ellipsoidal shape shown has the lowest moment of inertia of all possible shapes. The pretty minor ones Deviations in the moments of inertia of the variously shaped Counterweights, however, are insignificant compared to the very substantial reduction in all moments of inertia in all different forms of counterweights according to the present invention, in which the Adjacent counterweights to the respective center of oscillation of the tonearm.

In the embodiment shown in FIGS the tonearm 11.7 has a counterweight C.7 that some Outlines united. A part has a cylindrical Outline. The end b of the counterweight adjoins the cylindrical section and has the shape of a truncated cone Shapes, with its end face 31.7 adjoining the center of oscillation 24.7. The outer end part c of the counterweight C.7 is also a truncated cone, but with a different one Cone slope.

In the embodiment shown in FIGS the tonearm 11.8 has. a counterweight C.8 with half Cylindrical shape, as in FIGS. 11 to 13, and also has a single gimbal pivot structure 23.8, the one U-shaped upright gimbal 42 with pivot pin 43 which are aligned with one another on the Z-axis and extend into the openings of the fastening eyes 44 on the Extend ends of the counterweight. The gimbal 42 has a depending mounting bracket 45, which is with the gimbal 42 rotates around the Y-axis and within the stationary mounting sleeve 46. A suitable camp

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takes the swiveling of the gimbal around the Y-axis accordingly to the sleeve 46. Accordingly, the tonearm 11.8 swings freely around the Y and Z axes, at the intersection of which the Pivot center lies.

In FIGS. 23 to 26, various embodiments of different positions of the center of gravity are shown of the counterweight is shown relative to the pivot center of the tonearm. .

In Fig. 23 the tonearm 11.9 has a counterweight C9, which is designed as a cylinder whose axis extends along the X-axis of the tonearm and whose front surface 31 · 9 adjoins the pivot center 24.9. At this Embodiment, an auxiliary counterweight sleeve 48 has the shape of a cylindrical ring that rests on the counterweight C.9 is attached and can be moved lengthways on it. While the counterweight C.9 is generally made of steel, a central cavity 49 contains a lot of lead to keep the To increase the weight of the counterweight and to increase the average or effective density of it. At this Embodiment is a further setting option created by alternative pivot positions a and b to make significant changes in the position of the counterweight take up accordingly to the swivel center.

In the embodiment shown in FIG. 24, the tonearm 11.10 has a counterweight ClO with a hemispherical shape, its front surface 31.10 adjoining the oscillation center 24.10. A hollow hemispherical shell 50 is removably disposed and secured in such a way on the counterweight ClO that the effective weight of _the: is increased counterweight. Alternative pivot centers A and B are also provided for the tonearm 11.10 in order to allow the adjustment of the front surface of the counterweight to

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different positions according to the swivel center * to accomplish.

In FIGS. 25 and 26, the tonearm 11.11 has a counterweight CIl with a half-cylinder shape, as it has been shown substantially in FIGS. 11 to 13, the axis the cylinder shape is along the Z-axis and through the Swing center extends therethrough. The counterweight is fitted with a pair of semicircular disks 51 on the opposite • provided overlying sides of the counterweight and mounted on pivot pins 52 to pivot the loaded To receive discs 51, as shown in the dashed position D in FIG. Such panning of the disks 51 takes the displacement of the effective Center of gravity of the counterweight.

In FIGS. 25 and 26, the front surface 31.11 adjoins the oscillating center 2 ^ .11. Additionally there are two alternatives Positions of the center of oscillation A and B, shown to determine the distance between the effective center of mass of the To change the counterweight and the pivoting center of the tonearm.

In FIGS. 27 and 28, the tonearm 11.12 has a counterweight C.12 which is in the shape of a truncated cone with flat Has circumferential surfaces 53. Again, the front surface 31.12 of the counterweight is adjacent to the pivoting center 24.12, the frustoconical shape of the counterweight converging convergently from the front surface 31.12. This Truncated cone counterweight C. 12 shows that the inventive Counterweight need not be rounded or circular, but also have flat surfaces can and still have a minimum moment of inertia corresponding to the Y and Z axes through the pivot center.

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It should be noted that while a variety of counterbalance forms have been shown, one an unlimited number of different forms of counterweights is conceivable that embody the idea according to the invention use. While FIG. 23 shows a shape with an inner cavity, other openings or with different types Substance-filled inner cavities or empty cavities are provided to support the weight or the moment of inertia to change the counterweight as necessary. It is also important to note that normally the counterweight has a shape in which the length of the counterweight is along the X-axis of the tonearm in the same order of magnitude as the width of the counterweight is.

With further reference to FIGS. 1 and la, the critical physical dimensions and dimensions for a particular Tonearm determined as follows:

Weight of the pipe 1J>, approximately 2.75 g weight of the attachment or of the head 14, 2.5 to 3 g weight of the insert 15, approximately 3 to 13 g * Distance from the pivot center to the needle 9 · 5 inches = 24 cm Mass of the counterweight (actually) 250 g - 5 g ₅ including the head 28 and weight 29 , mass of the outer hemispherical weight, approximately 193 g »maximum diameter of the counterweight 4.57 cm, groove guide force of the needle, approximately 1 to 4 g, effective Mass of the arm minus the counterweight, approximately 12.6 to 12.7 g.

The moments of inertia of the counterweights of the various shapes can be determined mathematically. .F, ür,, each special Form of the counterweight in its relation to the,. Transverse ends

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ORIGINAL INSPECTED

horizontal or Z-axis through the center of oscillation, the moment of inertia is approximately

where C is a constant for the counterweight of a particular shape j & is the density of the material in the counterweight; and Myz is the first moment of the counterweight corresponding to the perpendicular plane, including the Y and Z axes.

The constant (C) for the various types of counterweight are as follows:

Best possible cylindrical counterweight, accordingly Figures 8-10, C = 0.9724.

• Best possible cylindrical counterweight, corresponding to those shown in Figures 8 to IQ are, but the front surface is slightly spaced to the rear from the center of oscillation, C = 0.9578.

Hemispherical counterweight, essentially as in .den Fig. 5 to 7, C = 1.1331-.

Counterweight in the form of an ellipsoid, with the least possible Moment of inertia, as shown in FIGS. 14 to 16 shown C = 0.9405. _ "■■" "" ..

It follows that all the moments of inertia of this Counterweight shapes are of the same order of magnitude as one another and also with regard to the minimum possible moment of inertia .

Corresponding to the above-mentioned cylindrical counterweight, with the front surface slightly spaced from the pivot center (C = 0.9578), is the distance D between the center of oscillation.

and the center of gravity of the cylinder approximately 0.645 t, where t is the axial length of the cylindrical counterweights

909651/0791

" ²⁸ " 2S23500

Accordingly, it should be evident that the counterweight can take a multitude of different forms. the Changing the shape of the counterweight - changes the moment of inertia something just inconsistent. The extremely heavy counterweight of the tonearm according to the present Invention provides a more stable platform than was previously known, since the counterweight to the Schwingbzw. Swivel center adjoins. Because the distance from the center of the swing to the center of gravity of the counterweight is significant has been decreased, the angular acceleration of the tone arm according to the present invention becomes considerable reduced from the previously known and accordingly the angular velocity is lower in the arm according to the invention be. The movement of the arm is therefore less disturbed by external forces than was previously known. The heavier counterweight The present invention is responsible for this improved stability as it is the center of gravity of the overall system close to the pivot point 'sets or moves. The hemispherical shape of the counterweight in one Example and its position, adjacent to the pivot point, lead to the high mass of the counterweight around the arm and to keep the stakes in balance. The presence of a considerable mass in the counterweight attached to the Pan center is very important to the present invention.

It can therefore be seen that a new and improved tonearm has been created with a particularly massive counterweight has been, with its front surface at the pivot or swing center of the tonearm around its vertical and horizontal Axis around adjacent, which extend transversely to the tonearm and through the center of oscillation. The extreme mass of the counterweight, together with the minimum distance between the center of gravity of the counterweight and the

309851/0791

ORIGINAL INSPECTED

The vibration center of the tonearm surprisingly provides improved results for the tonearm.

9Q98S1 / Q79J

Claims (23)

2823500 RAFFAY & BÖETER * S "-" - 'I PATENTANWÄLTE DIPL.-ING. VINCENCE V. RAFFAY POST BOX 32 3217 HAMBURG O-2000 HAMBURG 13 DIPL.-OHEM. DR. HANS O. BOETERS MONKS CHANCELLERY: 7 June 1979 qeffckenstrasse β TELEPHONE: CO4O) 47 SUN Ξ: PATFAY, HAMBURG MAGNEPAN, INCORPORATED our act: 2065/13 First Street
White Bear Lake
Minnesota 55110, USA Tonearm for turntables Claims Tonearm for turntables, consisting of an elongated Lightweight arm and a front and rear section, a cartridge in the front Section of the arm, fasteners connected to the arm and swinging it freely around a Fasten the fulcrum located between the front and rear sections and one on top of the rear portion of the arm arranged counterweight, characterized in that the arm (11) around itself intersecting vertical and horizontal axes swings (X, Y and Z), which extend transversely to the arm, wherein the counterweight (C) has a front portion adjoining the pivot point, and that the counterweight and the front portion of the arm are roughly statically balanced. 9 0 9 8 5 1/0791 PROFESSIONAL REPRESENTATIVES BEFORETHE EUROPEAN PATENT OFFIOE 2. Tonearm according to claim 1, characterized in that the counterweight (G) has such a shape "that it essentially minimizes the distance between the pivot point or center of rotation and the center of inertia of the counterweight. ^;: ■" ^: · ^; * " 3. Tonearm according to claim 1, characterized in that the counterweight has such a shape that it "builds up a moment of inertia in the same order of magnitude as the minimum possible moment of inertia of the" counterweight. ■ -. "-.: .. -" - """■" ■ - - · "- ^: ^ 4. Tonearm according to claim 3j, characterized in that the moments of inertia in 'relationship to' a ¹ axis ^: "Stand, which extends generally horizontally and through the ^{: i center of} visual oscillation as well as transversely to the elongated 'arm. 5. Tonearm according to claim 3 *, characterized in that the Moments of inertia are related to an axis that is generally perpendicular and through the center of vibration as well as extending transversely to the elongated arm. 6. tonearm according to claim 1, characterized in that the Counterweight is made of steel. 7. Tonearm according to claim 1, characterized in that ^: that the counterweight consists of lead. 8. tonearm according to claim 1, characterized in that the Counterweight is made of a material with a density that is in an order of magnitude not less than that Density of steel. 9. tonearm according to claim 1, characterized in that the counterweight has a ^: length in the direction along the elongated arm and also has a shape with a length and width which is of the same order of magnitude. 90 9851/0791 ORIGINAL INSPECTED 10. Tonearm according to claim 1, characterized in that the the rear section of the arm and the counterweight have a means acting in the same direction, that allows moving at least a part of the counterweight corresponding to the arm. 11. Tonearm according to claim 10 ^ characterized in that the acting in the same direction means moving the counterweight in the longitudinal direction along the elongated Poor picks up. 12. Tonearm according to claim 1, characterized in that the Counterweight has a front surface that is adjacent to the pivot point and oriented transversely to the elongated arm is. 13. Tonearm according to claim 12, characterized in that the front surface is flat. m. tone arm according to claim 12, characterized in that the front face is rounded convexly corresponding to the front portion of the arm. 15. Tonearm according to claim 12, characterized in that the counterweight essentially as a body of revolution around a longitudinal arm extending along the elongated arm Axis is formed. 16. Tonearm according to claim 15 *, characterized in that the counterweight has a substantially hemispherical shape. 17. Tonearm according to claim 15, characterized in that the counterweight comprises a portion of substantially cylindrical shape. 9Q98S1 / 0791 ORIGINAL INSPECTED 18. Tonearm according to claim 15, characterized in that • the counterweight has a part with frustoconical '- Form includes. - 19. Tonearm according to claim 12, characterized in that the counterweight in a horizontal direction is elongated or elongated transversely to the arm. 20. Tonearm according to claim 19, characterized in that the counterweight is substantially in the shape of a half cylinder having. 21. Tonearm according to claim 15 , characterized in that the counterweight has a substantially ellipsoidal shape with a maximum diameter which is not less than its length along the axis of rotation. 22. Tonearm according to claim 12, characterized in that the counterweight is symmetrical in the transverse directions is corresponding to the elongated arm both horizontally and vertically corresponding to the arm. 23. Tonearm according to claim 22, characterized in that the counterweight comprises a plurality of flat outer surfaces. Description; 909851/0791 ORIGINAL INSPECTED