US3218878A - Drive arrangement - Google Patents

Description

Nov. 23, 1965 J. G. WALLACE ETAL' ,218,

DRIVE ARRANGEMENT Filed April 6, 1962 INVENTORS. 1 Jam/ l/(uzn: @024! 1. $04 775 v v I Y [3 7 3 39 United States Patent 3,218,878 DRIVE ARRANGEMENT John G. Wallace, Branford, and George L. Soltis, Shelton,

Conm, assignors to Dictaphone Corporation, Bridgeport, Conn., a corporation of Connecticut Filed Apr. 6, 1962, Ser. No. 185,619 6 Claims. (Cl. 74-424.8)

This invention relates to an improved supporting and driving arrangement for the transducer head carriage in a dictating machine and the like.

An object of this invention is to provide a rugged and efficient mounting and feedscrew engaging arrangement for a transducer head carriage.

A more specific object is to provide an improved feedscrew nut engaging arrangement in a machine of this kind.

A further object is to provided a feednut arrangement which is positive in its action and which is relatively inexpensive to manufacture and assemble.

These and other objects will in part be understood from and in part pointed out in the following description.

In a dictating machine such as shown in U.S. patent application, Serial No. 728,646 (-7180), now patent No. 3,056,606 a belt record is stretched over and upon a pair of mandrels. Mounted to slide on guide rods transversely beneath the record is a carriage which supports a recording head and a playback head. During recording, as the record is rotated on the mandrels, this carriage moves slowly across the record with the recording head in contact with it to trace out a close-pitch, helical signal track. The carriage is driven by a feedscrew to which, during this operation, it is coupled by means of a feednut mounted on the carriage and locked in engagement with the feedscrew. To permit the carriage to be shifted manually across the record, the feednut must be unlocked or otherwise disengaged from the feedscrew. The present invention provides an improved arrangement for locking and unlocking such a feednut. Moreover, this arrangement simplifies the mounting of the carriage.

In accordance with the present invention, in one specific embodiment thereof, a toothed feednut is mounted in bearings in a support housing afiixed to the carriage in a dictating machine, such as described above. The teeth of this member engage the threads of the feedscrew so that when the member is locked in its housing the carriage will be driven by the feedscreW. To provide quick and positive locking of the feednut, one end of its is tapered and is positioned to engage a mating tapered surface of the housing in which it is journaled. By shifting the feednut axially only a very small distance the feednut can be locked very tightly in its housing. Conversely, by shifting the tapered surfaces apart, the feednut is permitted to rotate freely. Advantageously, the feednut housing has a portion of plastic which bears against the feedscrew to provide a smoothly sliding support surface. This permits the carriage to be supported on only one guide rod, in addition to the feedscrew, and thereby simplifies mounting of the carriage.

A better understanding of the invention together with a fuller appreciation of its many advantages will best be gained from the following description given in connection with the accompanying drawings wherein:

FIGURE 1 is a perspective View of a portion of a dictating machine with a carriage embodying features of the invention; and

FIGURE 2 is a greatly enlarged section of the carriage showing the feednut and housing.

The mechanism 10 shown in FIGURE 1 includes two parallel mandrels 12 and 14 upon which is stretched a belt record 16. One of these mandrels is driven by a motor (not shown) and in turn revolves the record in the direction of an arrow 18. Details of mounting of these mandrels and an arrangement for driving them are given in detail in the above-mentioned patent.

Positioned beneath the mandrels is a transducer head carriage, generally indicated at 20. This carriage is mounted for movement across the record, i.e. parallel to the mandrels, being supported on a guide rod 22 and on a feedscrew 24. The carriage in turn supports in front of mandrel 14 a playback head 26 which is adapted to engage the record and reproduce sounds recorded on it. A recording head (not shown) is mounted on the carriage beneath mandrel 14. During a recording or playback operation, feedscrew 24 is rotated at a fixed speed ratio to mandrel 14, and carriage 20, by being coupled to the feedscrew, is driven slowly across the record while it passes longitudinally by the playback and recording heads.

As seen best in FIGURE 2, carriage 20 has fixed to it a plastic support housing 30. The latter embraces and half surrounds feedscrew 24. Positioned in an opening within housing 30 at right angles to the feedscrew is a feednut 32 whose central part has gear teeth which engage the thread on the feedscrew. The lower end of feednut 32 is mounted in a bushing 34 pressed into housing 30. Projecting beyond the lower end of the feednut is a roundheaded screw 36 which is axially threaded into the feednut. The head of this screw is adapted to be engaged by the inclined end 37 of a cam arm 38, which can be shifted to the left, as indicated by an arrow 39, and by means of which the feednut is shifted upward.

The upper end of the feednut is tapered at 40 and is adapted to engage a similarly tapered met-a1 bushing 42. Pressing downward on the upper end of the feednut is the free end of a leaf spring 44 which is attached to housing 30 by a screw 46.

Now, when the feednut is shifted upward by the camming action of the arm 38 against screw 36, tapered surface 40 will be raised out of intimate engagement with bushing 42. This shifting, which is illustrated in exaggerated form by the dotted lines in FIGURE 2, permits the feednut to rotate freely within housing 30. Thus, even though the teeth of the nut continue to engage the thread of feedscrew 24, the carriage can be freely shifted back and forth along the feedscrew. Conversely, when arm 38 is shifted back to the right to the position shown in FIG- URE 2, feednut 32 is allowed to move down under the force of spring 44, and tapered surface 40 will grip the corresponding surface of bushing 42 and strongly resist rotation of the feednut. This, of course, locks the carriage to feedscrew 24 so that when the latter is rotated the carriage is driven across the record. As seen best in FIGURE 1, the rightmost end of arm 38 carries a pin 46 which is engaged by a mechanism (not shown) which in turn is manually operable to shift arm 38 back and forth in the direction of arrow 39.

Housing 30 is advantageously made of a plastic such as Delrin (an acetal resin) having rigidity, strength and high surface lubricity. This enables the housing to slide smoothly along the feedsc-rew and eliminates an additional guide rod for the carriage. Both the feednut and feedscrew are usually made of metal, such as beryllium copper and steel, respectively.

In an actual machine which has been successfully operated, an axial shift of about .002 inch locks or unlocks the feednut. Surface 40 had a 10 taper. Arm 38 was selectively controlled to the right or left by a manually operable mechanism (not shown) on the carriage. The above description of the invention is intended in illustration and not in limitation thereof. Various changes may occur to those skilled in the art and these may be made without departing from the spirit or scope of the invention as set forth.

We claim:

1. In a dictating machine wherein a belt record is mounted upon a pair of spaced mandrels, a carriage for supporting a transducer head and for moving it laterally across the record, a guide rod for supporting one end of said carriage, a feedscrew for supporting another end of said carriage and for driving it, and a feednut housing on said carriage slidably engaging said feedscrew, at least a portion of said housing being of plastic having rigidity, strength and high surface lubricity, said housing having recessed in it transverse to said feedscrew a feednut, said feednut being continuously engaged with said feedscrew and being axially shiftable into and out of engagement with a locking detent on said housing.

2. The arrangement in claim 1 wherein said detent comprises a tapered bearing which engages a mating surface of said feednut at one end thereof, said feednut being spring-urged into said tapered bearing.

3. In a machine of the character described, an improved carriage driving and supporting arrangement comprising a feedscrew and a guide rod spaced parallel to each other and supported on a frame, a transducer head carriage slidably mounted on said rod, a housing on said carriage having a U-shaped portion embracing said feedscrew, a small diameter elongated feednut recessed in said housing at right angles to said feedscrew and in engagement therewith, a tapered bearing in said housing supporting one end of said feednut, said feednut having a mating tapered surface, locking means to urge said nut into locking engagement with said bearing and means to shift said nut axially against said locking means to permit said nut to rotate and said carriage to slide freely along said feedscrew.

4. The arrangement in claim 3 wherein said housing is of plastic and has physical properties substantially like Delrin.

5. An improved drive arrangement comprising a feedscrew, a housing adapted to slide therealong, a feednut rotatably mounted in said housing at right angles to said feedscrew and in engagement therewith, said feednut being axially shifta-ble in said housing and being locked against rotation at one end of its axial travel and unlocked for rotation at the other end of its axial travel, and means for axially shifting said feednut one way or the other to engage or disengage said arrangement.

6. The arrangement in claim 5 wherein said housing embraces said feedscrew and is at least partly of plastic having rigidity, strength and high surface lubricity, said housing and feednut having mating tapered surfaces which engage to lock said feednut against rotation when said feednut is axially shifted.

References Cited by the Examiner UNITED STATES PATENTS 2,714,010 7/1955 Gruber et al. 274-20 2,860,217 11/1958 Bourns 74424.8 3,059,933 10/1962 Proctor 274 20 DON A. WAITE, Primary Examiner.

Claims (1)

1. IN A DICTATING MACHINE WHEREIN A BELT RECORD IS MOUNTED UPON A PAIR OF SPACED MANDRELS, A CARRIAGE FOR SUPPORTING A TRANSDUCER HEAD AND FOR MOVING IT LATERALLY ACROSS THE RECORD, A GUIDE ROD FOR SUPPORTING ONE END OF SAID CARRIAGE, A FEEDSCREW FOR SUPPORTING ANOTHER END OF SAID CARRIAGE AND FOR DRIVING IT, AND A FEEDNUT HOUSING ON SAID CARRIAGE SLIDABLY ENGAGING SAID FEEDSCREW, AT LEAST A PORTION OF SAID HOUSING BEING OF PLASTIC HAVING RIGIDITY, STRENGTH AND HIGH SURFACE LUBRICITY, SAID HOUSING HAVING RECESSED IN IT TRANSVERSE TO SAID FEEDSCREW A FEEDNUT, SAID FEEDNUT BEING CONTINUOUSLY ENGAGED WITH SAID FEEDSCREW AND BEING AXIALLY SHIFTABLE INTO AND OUT OF ENGAGEMENT WITH A LOCKING DETENT ON SAID HOUSING.

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