US1780378A - Electric pick-up for gramophone or other sound records - Google Patents

Description

J. DIEUX Nov. 4, 1930.

ELECTRIC PICKUP FOR GRAMOPHONE OR OTHER SOUND RECORDS Fi led March 1, 1929 Patented Nov. 4, 1930 UNITED STATES JEAN DIEUX, OF

ELECTRIC TICK-UP FOR GRAMOPHQN E B OTHER SOUND RECORDS Application filed March 1, 1929, Serial No. 343,776, andin France May 10, 1928.

The primary object of the present invention is the improvement of electric pick-ups for gramophone records or other sound surfaces.

Its particular purpose is the regulation of the pressure exerted by the stylus or needle on the sound surface under the action of the weight of the pick-up, so that this pressure will be just sufficient to provide the necessary adherence of the needle on the sound surface without causing premature wear of this surface.

The aforesaid objects are attained with an electric pick-up possessing the characteristic features given in the following description and especially in the accompanying claims.

Electric pick-ups conformable with the invention are shown, by way of example, in the accompanying drawings, wherein Fig. 1 is a view in perspective of one form of pick-up.

Fig. 2 is a front view of the same pick-up with the stylus-carrier and electromagnet uncovered.

Fig. 3 is a section through the supporting pivot for the pick-up taken on the line 3-3 in Fig. 1.

Figs. 4 and 5 are, respectively a. plan view and an elevation showing a modification according to the invention.

The electric pickup of Figs. 1 and 2 comprises a casing 1, ofebonite, for example, inside which there is a generator of electric oscillations such as the electromagnet 2 with coils 3. The vibratory member 4 carrying the needle 5 is disposed between the two poles of the electromagnet 2. The body portions 4 4 of the needle-holder are made of non-magnetic material, such as non-magnetic metal, non-resonant alloy, ebonite, fibre, etc. On the body portion is a soft magnetic iron core 4. located between the two poles of the electromagnet 2. The magnetic core 4- modifies the magnetic field of the electro-magnet 2 when the movable member 4 vibrates and thus induces current in the winding of the electro-magnet, whereas the ebonite portions 4:, of the needle holder, allow of lightening the vibratory member' iand of damping its vibrations and resonance, as also those of the needle. Thus a durable combination is obtained, which is very simple to make and regulate.

The casing l is hinged at 10 on the fork of a supporting arm. 11 and-provided with a counterweighn 12 which partially equilibrates the. casingl, and the elements with in or carried by the casing (needle, electromagnet, etc) with respect to axis 10. Thus, the needle 5 exerts only sufiicient pressure 011 therecord. 6zfor it to adhere to the record; and this pressure, which is much less than that in the known devices without counterweights such as 12, only involves slight wear of the record 6. A

The arm 11 is integral with a boss 13 adapted to receive a bolt 14 and resting thereon through the ball 15. This bolt 14; is itself fixed by means of washers 16 and 17 screwed against a supporting cap 18. In this way the arm 11 can be supported with a minimum of friction.

Various alterations can be made in the afore-d'escribed electric pickup. In particular, the counterweight can'be made in various ways. It may be obtained in a simple manner by the provision of a sufiicient extra thickness on the casing 1 at its upper part approximately to balance the rest of the casing and associated parts.

The casing (Figs. 4 and 5) can also be fixed on an arm 20 hinged on the axis 21, the angle of this casing with the arm remaining constant while the counterweight 12 gives partial equilibrium therefor.

Furthermore, the pivot arrangement shown in Fig. 3 can be reversed, viz. the bolt 14 being placed on the boss 13 and engaging in a seat in the cap 18 through a ball 15 itself resting on the cap.

What I claim as my invention, and desire to secure by Letters Patent is 1. In an electric pick-up, a supporting cap carrying a bolt, a ball mounted on said bolt, a supporting arm engaging said bolt and resting on said ball, a casing hinged to said supporting arm, a generator of electric oscillations such as an electromagnet mounted in said casing, a vibratory member mounted in said casing and movable with respect to said electromagnet; a counterweight forming one with said casing and balancing it with respect to the hinged axis so that said vibratory member only exerts sufficient pressure with its needle on the sound surface for adherence thereto, this equilibrium thus avoiding all premature wear of the said surface.

2. In an electric pick-up, a supporting arm, a casing pivotally carried by said arm, a generator of electric oscillations, such as an electromagnet, mounted in said casing, a vibrating member also mounted in said casing, and movable relative to said electromagnet, the movable assembly of said vibrating member,

( said electromagnet and said casing being traversed by the pivotal axis of suspension on said arm and being partially balanced with respect to said axis by its construction, and a counter-weight carried by said casing and completing the balance, thus insuring a perfect balance of said movable assembly without a material increase of the mass of said assembly.

In testimony whereof I have signed this JEAN DIEUX.

. specification.

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