US2580694A

US2580694A - Dual stylus phonograph pickup

Info

Publication number: US2580694A
Application number: US86474A
Authority: US
Inventors: David J Munroe
Original assignee: Webster Electric Co Inc
Current assignee: Webster Electric Co Inc
Priority date: 1949-04-09
Filing date: 1949-04-09
Publication date: 1952-01-01
Anticipated expiration: 1969-01-01

Description

Jan. 1, 1952 D, 1 MUNROE DUAL STYLUS PHONOGRAPH PICKUP Filed Rpyil 9, 1949 dws@ Patented Jan. 1, 1952 DUAL STYLUS PHONOGRAPH PICKUP David J. Munroe, Racine, Wis., assgnor to Webster Electric Company, Racine, Wis., a corporation of Delaware Application April 9, 1949, Serial No. 86,474

8 Claims.

The present invention relates to a reproducer or pickup and has for one of its primary objects a provision of a new and improved pickup for playing records.

Another object of the present invention is to provide a new and improved pickup characterized by its simplicity, economical construction and low mechanical inertia whereby it is especially suitable for installations requiring low needle pressures.

Another object of the present invention is to provide a new and improved pickup characterized particularly by a novel coupling between a drive element and a crystal type transducer.

The pickup of the present invention is light in weight and has a low mechanical inertia so that it can be used satisfactorily with low needle pressure and is particularly suited for use in playing diierent kinds of records, such as conventional and long-playing records, the latter of which require a low needle pressure for good reproduction. The pickup also faithfully reproduces high frequency vibrations as well as the low frequency vibrations, even with low needle pressure.

In brief, the pickup of the present invention includes a transducer element such as a crystal, a movable driving element which may be the needle chuck, and a coupling between the two comprising a yieldable tongue and slot connection. The tongue may be formed at one end of the chuck and the slot is formed in the bight of a generally U-shaped element, the arms of which are bifurcated and secured to opposite sides of the crystal at a space such that movements of the chuck are transmitted to and actuate the crystal in a degree determined by the yieldability of the connection, the yieldability being provided by damping material located between the tongue and slot defining portion.

Other objects and advantages of the present invention will become apparent from the ensuing description of an illustrative embodiment thereof, in the course of which reference is had to the accompanying drawing, in which:

Fig. l is an enlarged vertical cross-sectional view through a pickup unit constructed in accordance with the present invention;

Fig. 2 is a top plan view of the chuck, crystal and coupling of the pickup illustrated in Fig. 1;

Fig. 3 is a fragmentary cross-sectional View taken along the line 3-3 of Fig. 2; and

Fig. 4 is a fragmentary cross-sectional view taken along the line 4-4 of Fig. 3.

Referring now to the drawing, the pickup of the present invention is indicated as a whole by reference character I0. It comprises a two part housing including upper and lower parts I2 and It which may be identical metal stampings, plastic moldings or the like, a transducer in the formof a crystal element I6, a movement transmitting element which may be a needle chuck I 8, and coupling means 20 between the crystal and chuck.

The crystal is secured inside the housing between spaced mounting blocks 2B held in compression against the end of the crystal by adjacent portions of the housing parts which are held in assembled relation by a plurality of screws, bolts, rivets or the like, not shown. The mounting blocks are made of rubber or rubberlike damping material and they may have a width such as about one-third that of the crystal. The crystal is electrically connected by conductors 22 to terminals 24 projecting rearwardly through a terminal strip 25 at the rear of the pickup. AThe conductors may be insulated by the sleeves 26.

The needle chuck I8 is mounted for movement in the restricted dimensional portions 3i) and 32 of the housing parts which constitute bearing supports for the

trunnions

34 and 36 of the chuck. The trunnions are mounted for restricted movement, torsional in the illustrated construction, in

bearing sleeves

36 and 38 held in compression by the portions 3Q and 32 of the housing parts. These sleeves are made of some resilient damping material which may be rubber or rubber-like.

The chuck is provided with a diametrical opening 40 for the reception of a double ended needle structure i2 comprising a generally cylindrical shank All adapted detachably to receive

needles

48 and 48 which are constructed for playing conventional and long-playing records, respectively. The shank is held in the chuck as by an axial securing screw 50 extending through trunnion 34. that other needle and needle clamping structures can be used.

The present invention has to do with the coupling between the chuck and the crystal. 'Ihis coupling is characterized by its simplicity, low weight and low mechanical inertia. It comprises a tongue 52 which is generally rectangular in shape and cross section and a generally U- shaped coupling element 54 the spaced apart arms 56 and 5B of which are bifurcated and embrace and are secured to the crystal I6 near its outer edges in permanent manner, as by cement.

It should be understood, however,

The bight 59 of the coupling element is apertured at 6I to receive the tongue and the securing is made more effective by providing the opposite sides of the aperture with anges 69 adapted to be forced against a strip 62 of resilient damping material of rubber or rubberlike material extending over at least the upper and lower sides of the tongue. The choice of materialI and the pressure with which the coupling element is secured to the tongue may be varied to provide desired coupling characteristics.

It may be noted from the foregoing detailed description of the pickup ofthe presentI inven-V tion that it can be made simply and economically. It is also very light and the structure is located in vlarge part at or near the axis of the torsion transmitting element and near the crystal so that its mechanical inertia is low. It-also has a desired compliance to vertical movements of the needle andl the desired rigidity of torsional coupling by reason of the yieldable coupling providedby the tongue and slot connection with the yieldable strip between them. In the illustrated arrangement the crystal is of the twister type and twisted by torsional movement ofthe chuck and tongue, but it should be understood that the crystal can be of other types and diierently moved through the coupling means.

While the present invention has been described in connection with speciiicdetails of an illustrative embodiment thereof, it should beunderstood that these details arel not intended to be limitative of the invention,- except as set forth in theaccompanying claims.y

Having thus `described my invention, what I claim as new and desireV to secure by Letters Patent of the United States is:

1. A phonograph pickup, including in combination,- a resiliently mounted movable driving element having'a tongue-like portion; an electro-.- mechanical transducer adjacent the tongue-like portion, and means'including a. unitary U-shaped element having spacedfarms' secured to and partially encircling said transducer and having also an apertured bight into which said tongue-likeA portion is insertable for coupling said driving element to said transducer.

2. A phonograph pickup, including in combination, a movable driving element having a tongue-like portion, a crystal electro-mechanical transducer, and meansincluding a unitary generally U-shaped element having an apertured bight receiving said portion and'bifurcated arms spaced laterally of said transducer and secured to opposite sides of said transducer for coupling said driving element to said transducer.

3. A phonograph pickup, including in combination, a movable driving element having a tongue-like portion, a crystal electro-mechanical transducer, and means including a unitary generally U'-shaped element' having anA apertured bight receiving said'portion and bifurcated' arms spaced laterally of said transducer and secured to' opposite sides of said transducer for coupling said" driving element: to said transducer, said coupling means including also a strip of damping material covering at least the end portion of said tongue-like portion.

4. A phonograph pickup, including in combination, a resiliently mounted movable driving element having a tongue-like portion, a crystal electro-mechanical transducer, and means including a coupling element permanently secured to the crystal and having an aperture receiving said tongue-like portion and into which said portion is insertable for coupling said driving element to said transducer.

5. A phonograph pickup, including in combination, a resiliently mounted movable driving element having atongue-like portion, damping material at opposite sides of said tongue-like portion, a crystal' electro-mechanical transducer, a. coupling element permanently secured to the crystal and having structure dening an aperture into which said tongue-like portion is insertable, said tongue-like portion and damping material extending into said aperture, and securing flanges adjacent the aperture extending from said structure engaging saiddamping material.

6. A phonograph pickup, including in combination, a torsional type driving element having a tongue-like terminal portion, an electro-mechanical transducer, and means including a unitary U-shaped element secured to said transducer having a bight with an aperture into which said tongue extends, and a damping strip interposed between the tongue andthe aperture delining portion of said U-shaped element for coupling said driving element to said transducer.

7. A crystal pickup. of the type including a movable chuck and a crystal transducer element actuated thereby, including a tongueextending from said chuck, damping material` covering at least portions Aof ,opposite-sidesof the tongue, and a unitary U-shapedV coupling element permanently securedtosaid. crystal andy having a bight with an aperture to receive-said tongue and its covering.

8. A torsion type ycrystal pickupy of the Vtype including a torsionally movable chuck and a (A integral generally U-shapedv coupling element having an apertured bight to receivesaid tongue and its covering and' bifurcated"v armsspaced laterally of the-crystal'for securing said coupling element to the crystal.

DAVID J. MUNROE.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,649,257 Rowe Nov. 15, 1927 2,313,324 Dally Mar. 9,1943 2,326,280 Bauer Aug. 10, 1943 2,332,204 Chorpening Oct. 19, 1943" 2,513,269 Bauerv July 4, 1950