DE2020903A1 - Electrodynamic pickup or cutting box - Google Patents

Description

/ 2020803

, _: PATENT LAWYERS

PR. HUGO WILCKEN DIPL.-ING. THOMAS WILCKEN

D - 24 LÜBECK, BREITE STRASSE 52-54

/ 2Z April 1970

; ·: ';' ■. Th .W. / Cha.

Register . . '

Hermann Wilms, 24 Lübeck, Roeckstrasse Ib

Electrodynamic pickup or cutting box

The invention relates to an electrodynamic pickup or a cutting box for scanning or cutting two records lying at an angle to one another, for example stereophonic recording, sampling from a groove-shaped sound track with a scanning needle seated at the free end of a needle arm and two transducer or plunger coils attached to the needle arm are each located with their active sink sub-area in a magnetic air gap, the is formed by opposing pole pieces at a distance. "■ -

In known pickups of this type, the coils standing at right angles to one another and lying in a magnetic field are carried by a needle arm which is clamped at its inner end - * so that the center of oscillation is at the clamping-O ₀ end, while, the coils this a certain distance

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σ> · and by means of a support made of insulating material ° body are attached to the needle arm. This' construction leaves

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to; ; ; - 2 - '.; ■■■. ■ :

• libecfc (0451) 7MM, Mvoh Dr. H. Wild. ", Curau (W50S) JlO ·. HpMa * Th. Wllektn, LOb.ck (0451) 251 " lenk, Commwikonk A. G., Hl. Ub" *, account no. 3 " 0117 P" ti * "*, Hamburg 138119

2020103

holds large amplitudes of movement of the coils, so that 'With a given number of turns, a relatively large number of field lines can be cut, which is known because of the desired high signal or converter voltage is desired. However Such a construction usually suffers from the disadvantage that the The moment of inertia of the oscillating system is large because the coils are moved over a large radius. Also must a proportionate factor for the safe functioning of the system large air gap are provided, which leads to the fact that the Field strength in the air gap is low.

Ilan tried to solve this problem by making coils attached to a magnetically conductive armature on the needle arm, which reduces the effective air gap width. However, since the anchor resonates with the system, there are often distortion of the output, because the armature constantly changes the course of the field lines in the air gap. Incidentally, a Such a construction also does not represent a purely electrodynamic system.

Dynamic pickups are also known in which ^:

the two transducer coils triangular shape and parallel to each other on all sides of the vibratable IJadelarms' are arranged on both sides, wherein the active energy conversion! Coil parts run parallel to the I needle arm. This structure sawn ¹ hires a wide and thus adverse air gap, since the active coil sections are arranged one behind the other in the air gap. -

109846/0932

BATH

Another known embodiment is constructed so that the Levels of the two bobbins attached to the needle arm in the right Angle to each other are placed and one each in an air gap Permanent magnet system. To with a given air gap width To allow high numbers of turns, not too many turns can be placed next to each other in such a construction system, rather, they have to be placed on top of one another, which results in correspondingly large coil heights. This makes In turn, a complex fastening of the tall bobbins on the needle arm is necessary in order to avoid distortion-causing reverberation or to avoid mechanical swinging out of the coils.

In addition to the direct attachment of the transducer coils to the needle arm, there is also the option of attaching the coils to the needle arm via separate arms of a coupling link and holding them via elastic strips suitably attached to the pickup. The coil axes then lie parallel to the respective air gap in which the active coil part oscillates. Oa the coils in -, this design have a large distance to the needle arm and since the parts required to hold the coils have a certain sluggish hatred, these pickup systems have a frequency-dependent inertia, which has an unfavorable effect on the frequency of the pickup. _ \

The object of the invention consists essentially in the addition | Elimination of the disadvantages shown by creating an electro-dynamic pickup, its structure and vibration system "! with a low dynamic mass and compact design a u,

109 8 A6 / 093 2 ,,

_ 4 enables good frequency response of the converter system.

The aforementioned pickup is used to solve this problem according to the invention designed so that the coils or the winding planes of the coils transversely to the longitudinal course of the I needle arm be placed and that one of the two pole shoes at its end delimiting the air gap for ^ both coils to form is divided by two pole piece fingers, so that each of the One of the pole shoe fingers in and through the free central space Bobbins.

From the two pole pieces arranged at right angles to one another has one at its end a semicircular, that an end of the air gap delimiting recess, wherein the active coil subareas located in the air gaps and the other side of the air gap delimiting surfaces of the pole piece fingers reaching through the coils are parallel to one another get lost. Both coils lie in a mirror-inverted manner symmetrically to an imaginary vertical one that runs through the needle arm Level. The area adjacent to the needle arm is shown to be rectangular of the coils in a plastic or adhesive compound

■ embedded as a holding means that completely surrounds the needle arm. '

The needle arm is attached in a known manner with its end opposite the scanning needle "to one of the pole pieces and has a weakening point around which it is mounted so that it can vibrate elastically on all sides, the weakening point being through a

109846/0932

ORIGINAL BATHROOM

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in relation to the needle arm diameter thin ₅ thread-like section is formed from metal or plastic and in the area of this weakening point an elastic cushion surrounding it

is provided. ~ =

In the accompanying drawing is an embodiment of the Invention simplified and shown schematically. Show it:

Fig. 1 is a side view of the pickup system and t

Fig. 2 is a partial front view of the pickup

system according to FIG. 1 on an enlarged scale. -

The magnet system of the pickup consists of a permanent magnet

neten 1, at the ends of which a first pole piece 2 and a ί

Connect a bridge or a yoke 3. The second pole piece k comparable> runs parallel to the magnet 1 and is secured to the yoke. 3

The materials suitable for these components are generally j

known, j

The air gap 5 for the two transducer coils 6 and 7 is increased

j the opposite ends of the two pole shoes: 2 and 4 at a distance. The coils 6 _S 7 lie with their active coil areas 6a, Ta in the air gap 5 _S while their areas Gd, 7b opposite or adjacent to the needle arm 8 are embedded in a plastic or adhesive compound 9 which serves as a holding means for the coils and completely surrounds the Madel arm B carrying the Madel 10.

1098A670932

'Like from Pig. 2, in the embodiment shown, the coils 6, 7 placed transversely to the longitudinal course of the arm 8 have approximately the shape of a trapezoid, the longer base lines 6a » Yes in adaptation to the semicircular lower recess delimiting the air gap 5 on one side of the pole shoe 2 runs parallel to this, while the coils in the region of the shorter base line 6b, 7b are attached to the needle arm with the aid of the rigid mass 8. In addition, both transducer coils lie in a mirror-inverted manner symmetrically to a vertical imaginary plane 11 running through the needle arm.

The pole shoe 4 lying at right angles to the pole shoe 2 is divided at its end delimiting the air gap 5 for both coils 6, 7 to form two pole shoe fingers 12 and 13, in such a way that these pole shoe fingers as ring segments are mirror images of each other on both sides of the imaginary plane 11 _s are the Polschuhfingei .greifen "12 into and through the coil 6 and the pole piece fingers 13 into and through the coil. 7 The 'active coil sub-regions 6a,? A located in the air gap 5 or in the air gaps run, as has already been said, ₅ parallel to the semicircular recess 2a of the pole piece 2 which delimits one end of the air gap 5 and also parallel to the other end of the Air gap delimiting surfaces 12 a and 13 a of the pole shoe fingers reaching through the coils,

The formation of the pole piece with its finger-like shape

the shared end has in practice already resulted from manufacturing | proved to be particularly advantageous for technical reasons «- 7 -

"109846/0932

BAD OBiGINAL

_ 7

It should be pointed out, however, that this pole piece 4 can also be achieved by two parallel pole shoes: could be set, which then analogously to the ones described; Reach pole shoe fingers through the middle free coil areas have to, ;

The needle arm 8 is attached to the pole piece 4, with the help a sleeve 15 inserted into a bore 1-4 of the pole shoe made of brass * -which with a screw l6 in the hole against acIjsLale shift is set.

«The needle arm 8 is in a known way around a weakening point oscillating on all sides. This weakening point is caused by a Limiting the course of the needle arm and in relation to the needle arm ! thin, thread-like section IT made of metal or (Plastic formed that the sleeve 15 and the actual ials tubular body formed needle arm 8 connects to one another, ι It has proven to be advantageous in practice to use the section 17 to be designed as a pad element made of plastic material, otherwise mechanical damage when using a metallic thread Resonances in the listening frequency range are to be feared.

In the area of the weakening point or the connecting thread 17 is a these or these surrounding / les elastic pad 18 from Rubber is provided between a contact surface 19 of the PoI-Ijschuhs 4 and the holding means 9 surrounding the needle arm 8, [on its side facing the pad 18 with one of the

Needle arm 8 surrounding plate 20 made of plastic or hard paper is connected. The rubber pad is placed between the system - 8

1098A6 / 0932

2020Ö03

surface 19 and the plate 20 clamped under a certain bias. This has the consequence that centering

■ forces can be exerted on the vibration system. the end The holding body 9 for the coils can be used for stability reasons. ; 6 and 7 also completely enclosed by a stable paper layer.

• be wrapped. To save weight, the lower part of the Body 9 is roughly conical, while its upper region, in which the coils are embedded, is essentially rectangular Has cross section. . ;

On the lower extension of the yoke 3 there are soldering

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contacts 21, which in the usual way with the ends of the coil wires; i are to connect. The signal voltages are then applied to the ^con-: clock pins 22 and removed, for example, a signal

voltage amplifier supplied. The contact implementation through the Yoke 3 must of course be isolated from this. ;

If one assumes, for example, that the scanned writings are recorded at an angle of 90 degrees in the tone groove, the needle arm P oscillates around the described: and with the loading 'j zugsziffern are provided 23 and 2. * 1 It is obvious that when the needle arm ii of the plane 23 oscillates in the coil 6: a voltage is induced, since then its entire active sub-area 6 a field lines intersect in the air gap 5 in the same direction.

.; It is true that the coil 7 also cuts in this direction of oscillation

. ι
i field lines, however, two oppositely directed

: and

109846/0 932

BATH ORIGINAL

2020303

voltages of the same magnitude are induced, which cancel each other out. The same applies analogously to an oscillation in the plane of 24 _s in which only the coil 7 supplies signal voltages.

It can be seen from the two figures that the coils 6, 7 or the winding planes of these coils are aligned with one another and placed transversely to the longitudinal course of the needle arm 8 and that the pole shoe fingers 12, 13 pass through the free central spaces of these Grip coils. A very low and compact design of the pickup allows. The air gap 5 can be kept very narrow, since in the construction principle described, the coils can be made relatively wide and flat to achieve high turns count. This also has the advantage that the oscillation radii of the sinks are relatively small,.

'Finally, it should be noted that the ι structure described can also be used as a cutting box, the

'The needle OK is then replaced by a cutting stylus with which

groove-shaped soundtracks are cut »The signal or * Cutting stresses are flushed in a known manner 6 and 7 supplied via the connection points 22.

101840/0112

Claims (1)

DR. HUGO WILCKEN DIPL.-ING. THOMAS WILCKEN D - 24 LÜBECK. WIDE STREET 52-54 Λ - '5 ζ Α; · - · i' * Ό ' Th, W. / Cha, Applicant: Hermann wilms, 24 Lübeck, Roeckstrasse 1 b Claims (ij Electrodynamic pickup or cutting box for scanning or cutting two recordings lying at an angle to one another, for example stereophonic recordings, whereby the scanning takes place from a groove-shaped sound track with a scanning needle located at the free end of a needle arm and two transducer or plunger coils attached to the needle arm with their active coil subarea each lie in a magnetic air gap which is formed by spaced opposing pole shoes, characterized in that the coils (.6,7) or the winding planes of the coils are placed transversely to the longitudinal course of the needle arm (8) and that one of the pole shoes (2,4) limit the air gap (£.!?) for both coils at its two
zenden end for the formation of ^y pole shoe fingers (12,13) is divided such that one of the pole shoe fingers in and through the free central space each one of the Bobbins, ** • / ■ ■ f ' 1OI0AS / O932 «Ub« * («51)?» H, TW. Dr. M. Wlfckw, CMl («βθβ) ίΐβ. Wpl.-t «,. TVWlki «, Uk« i («51) S51 Λ l «f * · C ^ wwMbenk A. β .., m. WN * KK». ^ f, SIOW PaHMHdti K «mbwi ISIt If ■ ORSGINALINSPECTED -'tr- ^: '. ■■: ■. ·. ■■ -: 2. Pickup, or cutting box according to claim 1, characterized in that the pole pieces (2,4) are arranged at right angles to each other, that a pole piece (2) at its end semi- circular, one end of the air gap (5) delimiting j , Recess (2a) and that the in the air gaps loaded ' sensitive active coil sub-areas (6a, 7a) and the other · | Side of the air gap delimiting surfaces · (12a, 13a) of the j Coils (6,7) engaging pole piece fingers (12,13) to one another j run parallel. ' . 3. Pickup or cutting box according to claims 1 and 2, characterized in that the two coils (6,7) are in mirror image symmetry to a vertical imaginary plane (11) running through the needle arm. '4. Pickup or cutting box according to Claims 1 to 3, characterized in that the coils (6, 7) have approximately the shape of a trapezoid , the longer base line (6a, 7a) of which adapts to the course of the pole shoe recess (2a) this runs parallel, while the coils in the area of the shorter base lines (6b, 7b) are connected to the needle arm (8) via fastening means (9). j ■ ■ ■ ■ ■ ■ ■ 1, - ■ .- ■ - ■■■ ..: ■: ■■■ - ■ 5, pickup or cutting box according to claims 1 to 4, characterized in that the part area t 6b, 7b) of the coils adjacent to the needle arm (8) is embedded in a plastic or adhesive compound (9) as a fastening means. "* Den * -i" surrounds. , O ₉₈₄₆ / ,, ^ BATH 6, pickup or cutting box according to one of the claims
Ibis 5, in which the needle arm is attached with its end opposite the scanning needle to one of the pole pieces and a
Has a weakening point around which it is elastic on all sides
■ is mounted oscillatable, characterized in that the
The weakening point is formed by a thread-like section (17) made of metal or plastic, which is thin in relation to the needle arm diameter, and an elastic cushion (18) surrounding it is provided in the area of the weakening point. . 7. Pickup or cutting box according to claim 6, characterized in that the cushion (18). between one through the
Pole shoe to which the Nadelamr (8) is attached, formed
' Contact surface (19) and the holding means surrounding the needle arm
ί (9) for the coils (6,7) lies. ' ^l ' ί , ί 8. Pickup or cutting box according to one of claims 1 to 7 * i ι characterized in that the bobbin holding means (9) on its 'the pad (l8) facing surface with a needle arm (8) j 'surrounding plate (20) made of plastic or paper is connected. 9. pickup or cutting box according to one of claims 1 to 8, j characterized in that the loading of .elastic rubber,
standing pad (18) is pretensioned between the contact surface Cl9) on the pole piece (k) and the plate (20). i 109846/0932 BATH ■ Ά. Read 11 e