US2295460A - Phonograph trip mechanism - Google Patents

Description

Sept. 8, 1942. F. R. FARROW, JR

I PHONOGRAPH TRIP MECHANISM Filed Sept. 29, 1941 erable Patented Sept. 8, 1942 UNITED STATES PATENT OFFlCE' Frederick R. Farrow, J r., Audubon,

or to Philco Radio and Television Philadelphia, Pt,

N. 1., assign- Corporation,

a corporation of Delaware Application September 29, 1941, Serial No. 412,855

Claims. (Cl. 274-1) This invention relates to automatic phonographs of the type wherein the record-changing cycle is initiated by a trip mechanism responsive to the rate of movement of the tone arm pickup over the record being reproduced. x

More particularly, the invention relates to that type of trip which is adapted to function at the end of a recording, as the pickup stylus moves out of the reproducing grooves into' a spiral of greater pitch, or an eccentric groove; or in the event that the tone-arm moves too rapidly at any time during theplaying of a recording. .By way of example, the trip itself may be of the type which is triggered by the more rapid than normal movement of the pickup and which, in turn, serves to trigger a suitable mechanism adaptedto lift the pickup and swing it oil the record, in .order that a succeeding recording may be placed upon the turntable.

Many of the trip'mechanisms of .this general character, which have been employed heretofore, have been of a more or less complicated nature,

embodying a large number of moving parts. The

use of many parts not only raises the manufacturing cost of the trip mechanism, but has an additional disadvantage in that the trip mechanism, normally in operation, requires considord groove. Thus, it can be seen, especially with the very light stylus pressures now in use, that there may be a tendency toward bad tracking, that is, the needle point will often ride up one side of the groove and thereby distort the recorded signal.

The principal object of the present invention is to overcome the aforesaid dimculties by. the provision of a trip mechanism which is simple to manufacture, embodies relatively few mov-' ing parts, and which requires very little energy switch, the contacts of which remain open durenergy for its actuation. This energyi must come from the movement of the tone-arm, which movement is, in turn, brought about by the cooperation between the stylus and the recmoving in a predeillustrate the construction;

Fig. 2 is a fragmentary view illustrating the- ,to initiate operation of when the pickup moves more rapidly across" the record.

The invention also has for an object the provision 01' a velocity responsive trip mechanism embodying a switch, wherein the closing of the switch contacts completes an electrical circuit to.

an electrically-operated device, which is adapted the tone-arm lifting mechanism.

The invention may be fully understood by reference to the following description taken together with the accompanying drawing.

In'the drawing, g Fig. 1 is a perspective view of a phonograph device embodying one form of the present invention with certain parts broken operation of the device; and

Fig. 3 is a perspective view of a part of the apparatus.

ing normal movement of the piclrup and close The phonograph is assembled upon a base plate I which has a suitable bearing (not shown) for supporting a spindle 2 which carries a tumtable 3. A recording 4 is shown on the tumtable, the recording having a clear marginal edge 5, a low pitch spiral sound groove 6, and

a high pitch terminating groove I. Any suitable drive (not shown) may be used to rotate theturntable 3 as will be understood.

Adjacent the edge of the turntable a vertical post 8 may be mounted on the base plate I, there being resilient washers l on each side of plate I. At its upper end the post 8 pivotally Supports a conventional tone arm III. A reproducer of any suitable. type (not shown) may be positioned in. the free end of the tone arm, there being a stylus I I adapted to ride in the groove of the recording. Thus tone arm III ,will mov over a recording in the direction indicated until stylus II reaches the terminating groove I.

A vertical rod I2 shown extending below the base of post 8 extends upwardly through the same into engagement with tone arm I0 so that the rod I2 rotates with the tone arm. At its lower end rod I2 carries a horizontal arm I3 adapted to rotate about the pivot formed by 'rod I2 in a horizontal I. The arm It carries the switch mechanism which consists of two pivoted fingers.

l4 consists of an.L member I5 pivoted at II 'on arm- I3, an insulating extension I] carried away to better plane beneath the base plate Finger in contact with the sideof arm I13.

' resilient cushion member 21.

spring tends to rotate .arm I4 clockwise to normally maintain the adjustable set screw 2|- (See Fig. 3.) Finger 22 is pivotally supported'on arm I3 at 23, and carries near its free end a contact button 24 adjacentthe button I9 on finger II. To maintain finger 22 in its normal position, one endof a fiat leaf spring 25 i s secured to the inner end of finger 22, the other end of spring 25 being secured by a bracket 26 on arm I3.

At its outer extremity, finger 22 carries a semi- To control the operation of parts, there is provided an arm 28 'pivotally mounted beneath the base plate I at 29. Ann 28 extends through an opening 30 in the base plate and terminates adjacent the spindle 2 beneath the turntable.

slidably engage the upper surface of base plate I and serve to support arm 28 while permitting pivotal movement thereof. A self-lubricating fiber block 3| may be, secured to the inner end of arm 28 as shown. The turntable 3 has a hub 32 against which the block 3| is pressed by a spring 33 secured between arm'28 and base plate I. Hub 82 is formed with a cam like projection '84 on its periphery so that as the. turntable rotates, thearm' 28 will out of its. normal position for a brief interval. Arm 28 carries an arcuate plate 35 positioned so that when arm 28 is..in its-normal position,

Fingers 30a on arm 28.

the above described ys'ponsive When contacts I9 and 24 engage during clockwise movement of the tone arm, the finger I4 may rotate slightly about its pivot I6 by extending spring 20 thus preventing too'great a side thrust on the stylus I I. During counterclockwise movement of tone arm III, the member 21 may slide across the face 05 plate35 by causing a slight clockwise rotation of finger 22, or a suitable oneway latch-may be provided.

It willbe seen that the invention provides a trip mechanism for automatic phonographs, re-

to the rate ofmovement of the pickup, of such nature as to be smooth and positive in its action and which requires very little energy from the tone arm for its operation.

It willbe understood that the invention is not limited to the specific construction shown but is capable of modification within the scope of the appended claims.

-Iclaim:v

1. In an automatic phonograph having a. tone arm, a trip mechanism comprising a first means supported for movement in accordance with the movement of the tone arm over arecording, .a

member pivotally carried by said first means, op-

. positely facing contacts on said first means and be periodically pushed plate 85 will lightly engage cushion member 21 as shown.

The two contact buttons I9 and 24, are connected, by means of wires 38 and 81,- in circuit with a suitable relay or mechanism adapted to control the movement oi-the tone arm. While such mechanism may take any form, a suitable device is shown in the copending application of R. s. Cranmer, Serial No. 393,636, filedMay 15,

I 1941, to which the present application is related.

Having thus described the construction and relation of the parts of the device, the operation thereof may be considered. As the tone arm III moves over a recording during tbeplaying thereof, .the arm l3 moves correspondingly. During the intervals between successive actuations of arm 28 by cam 34, the contact 24 on finger 22 will remain relatively stationary because of the engagement of member 21 and plate 35, while thecontinuous movement of arm II by the tone arm II will cause finger 22 to. rotate slightly about its pivot 23 so as to slightlyfiex spring- 25. Contact I9 .will move toward contact 24 as the con.-

tact I9 is carried by and moves with arm I8.

' Periodic movement of arm 28 and plate 85 by cam er than normal rate.

fl releases member 21 to allow the spring to return finger 22 to its normal position relative to contact I8. The above described parts are so constructed-and adjusted that contacts I8 and 24 do not become engaged as the tone arm moves over the record at its normal rate of speed, and each time the finger 22 is released it will be advanced relative to plate 35. The solid line illus tration in Fig. 2 shows the position of the contacts just before member 21 is released, while the dotted line illustration shows the relative position of the parts when member 21 is released the tone arm III as when stylus I I from plate 35. However, when and arm I3 are moving rapidly, enters groove I, the finger ficiently during the interval between successive movements of arm 28 to cause the contacts I9 and 24 to engage and complete an electrical circuit through-any desired apparatus.

7o 22 will be rotated sufsaid member, means tending to maintain said member in a normal position relative to said first means,and means periodically restraining said member so -as-to cause rotation thereof relative.

to said first means as the latter moves in accordance with movement of said tone arm, the normal relative positions of the contacts on'said first means and said'member being such that said contacts become closed only upon movement of said, tone arm at a greater than normal rate.

2. In an automatic phonograph having a tone arm, a trip mechanism comprising an arm pivotally supported for rotation in accordance with the ment of said tone arm, the normal-relative .positions 01 said contacts on said arm and said memper being such that the contacts become closed only upon movement of said 3. In an automatic phonograph having a tone arm, a trip mechanism comprising a. first means supported for movement in accordance with the movement of the tone arm over a recording, a first contact-carrying member carried by said first means and movable therewith, a secondcontact-carrying member pivotally carried by said first means, oppositely facing contacts on said members, means tending tomaintain said second member in a normal position relative to said first member, and means periodically restraining said second member so as to cause rotation thereof relative to first member as said first means moves in accordance with movement of said tone arm, the normalrelative positions of said contacts being such that said contacts become closed only upon movement of said tone arm at agreater;

than normal rate.

4. In an automatic phonograph having a tone -arm,a trip mechanism. comprising a first means supported for movement in accordance-with the movement of said tone arm over a recording, a

member pivotally carried by said first means, op-

to said arm assaid arm rotates in accordance with the move-' tone arm .at a great- 7 3 positely facing contacts on said first means and.- arm and normally movable therewith, a second said member, means tending to maintain said con member-pivotallycarriedbysaid member in a normal position relative to said first means, and means ror periodically imposing a frictional drag on said member, thereby'to restrain said member and cause rotation thereof relative to said first-means as said-first means moves in accordance with movement 01' said tone arm, the normal relative positions at theoontacts on saidfirst means and said member bestrainingsaidsecondmember ing such that said contacts become closed only upon movement of said tone arm-at a greater than normal rate.

5. In an automatic phonograph having a tone arm, a trip mechanism comprising an aim pivotally supported for movement in accordance with the movement at the tone arm over a recording. a first contact-carrying member carried by said second member resulting arm and forming a longitudinal extension there-' oi, oppositely racing contacts on said members.

spring means tending to maintain said second member in a normal position relative to said first member, and friction means periodically recomprising an arlcuate plate member adapted to periodically engage the end face or! said second member to cause rotation thereod relative to said first member as said arm moves in accordance with the movement or said tone arm, the normal relative positions of said contacts being such that the contacts become closed only upon movement or said from movement or said tone arm at a greater than-normal rate.

' FREDERICK R. FARROW. Jn.

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