US2251322A

US2251322A - Telegraphone

Info

Publication number: US2251322A
Application number: US321392A
Authority: US
Inventors: Frederick G Buhrendorf
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1940-02-29
Filing date: 1940-02-29
Publication date: 1941-08-05
Anticipated expiration: 1958-08-05

Description

Aug 5 1941- F. G. BUHRENDORF 2,251,322 TELEGRAPIHONE Filed Feb. 29. 1940 ATTORNEY Patented Aug. 5,- 1941 2,251,322 l TELEGRAPHONE Frederick G. Bulirendorf, Hastings on Hudson, N. Y., assigner to Belly Telephone Laboratories, Incorporated, New York, N. Y., a corporation of N cw York Application February 29, 1940, Serial No. 321,392

3 Claims.

The linvention relates to telegraphones and the object of the invention is to maintain constant linear speed of the record member through the talking head.

According to the invention the speed f the record member, such as a tape or wire, passing through the talking head is controlled by an inertia roller or fly-wheel device of high inertia which rotates freely and independently of the record driving means. This control is effected by looping the tape around the roller, passing the looped portion through the talking head and tensioning the tape at the roller by means of resiliently mounted idlers between the roller and the tape storage means. 'I'he inertia roller is driven solely by the frictional contact of the tape therewith and any flutter inthe speed of the` tape on the storage means produces compensating changes in the positions of the idlers and the flutter is not transmitted to the looped portion of the tape with which the magnets are cooperating. y

This invention will be more clearly understood from the following detailed description and the accompanying drawing in which:

Fig. 1 is a plan View of a continuous tape telegraphone according to the invention; and

Fig. 2 is an elevation showing particularly the inertia roller.

In the drawing, the telegraphone shown has tape storage mechanism comprising two spaced drums II, I2 with the tape record member I3 spirally wound around them in a continuous loop as disclosed more in detail in a copending application, Serial No. 284,155, filed by C. C. Towne, July 13, 1939, The talking head I4 is of the type shown in Patent 2,202,139 granted to me May 28, 1940, but it will be understood that both the tape storage mechanism and talking head shown are merely illustrative and that the invention is equally applicable to any telegraphone using a continuous tape or wire record member.'

The inertia roller comprises a heavy fly-wheel I8 secured to a shaft I9 which is suitably mounted for free rotation in a bearing 20 in the base plate I 6. At its upper end there is secured to the shaft a roller 2| around which the tape passes in its transit from one drum to the other. The tape I3 is driven at the required speed by the motor I5 beneath the base plate I6 through suitable gearing on the shaft of the drum I2. As it leaves the drum II, the tape passes first under the idler 22, which is mounted1 on a pivoted arm 23, then over the roller 2|, through the talking head I4, back over the roller 2 I', under the pivoted idler 24 and (ol. ,17a- 1002) around the drum I2 to the drum II as indicated by-the arrows. The

idlers

22 and 24 are pressed against the tape by

suitable springs

25 and 26 in such a manner as to hold the tape in contact with the roller 2| over a considerable part of its circumference but, because of the high inertia of the roller and its associated fly-wheel, slippage may occur at the roller in some cases when the tape nrst begins to move. The friction between the tape and the roller, however, soon accelerates the roller to the speed of the tape and no slippage occurs in normal operation.

It will be seen that with this construction the loop of tape extending from the roller 2| through the talking head and back to the roller is entirely under the control of the roller which, due to the large inertia of the associated ily-wheel, keeps the tape passing through the head at substantially constant speed.

If, due to imperfect gearing in the driving mechanism, eccentricities of the drums on which the tape is stored or to any other cause, the linear speed of the portions of the tape leaving or approaching the drums is subjected to flutter vari-ations, the

idlers

22 and 24 will shift their tions and in such directions as to prevent the variations from affecting the tensions of the tape at the roller. For example, if at a given instant the speed of the tape tends to increase, thereby tending to increase the tension at idler 24 and decrease the tension at idler 22, the spring 25 will elongate slightly and spring 25 will contract slightly, thereby keeping the tensions of the parts of the tape approaching and leavingthe roller 2| substantially const-ant. Conversely, if `the speed of the tape tends to decrease, spring 26 contracts slightly and spring 25 elongates slightly and the tape tensions are again maintained substantially constant, The

springs

25 and 26 are, of course,

preferably such as to give small changes in tension for relatively large changes, in length so that for the slight movements of the idlers necessary to compensate for flutter variations, the changes in the spring tensions are negligible. Since the inertia of the mass rotating with the roller 2| is very large and the period of the flutter variations is ordinarily very short, the speed of the t-ape through the talking head is not appreciably affected by these variations and sound reproduced .from the tape will be free from this distortion.

-,With a single inertia l` roller, the

idlers

22 and 24 must be mounted i a slight angular relation to each other to keep the adjacent turns of the tape on thekroller running freely. It Will be understood that, if desired, two spaced inertia rollers may beused between the idlers instead of the single roller shown. In that case, the talking head will engage the tape between the rollers and the idlers nay be positioned in the same plane but the operation is essentially the same as with the single roller. The talking head I4 has been shown as provided with' stationary

grooved tape guides

21, 28. It theseare replaced with rotary guides to reduce friction, they must be made and mounted with great accuracy since any eccentricities in such rotary' guides would introduce other iiutter variations in the tape which cannot 4be eliminated by the roller.

What is claimed is:

1. In a telegraphone, a record member, means for driving the member, a roller of high inertia freely rotatable independently of the driving means and a signal translating device cooperating with the member, said member being looped around the roller with the looped portion spaced away from one side of the roller and passing through the device betweenjts successive engagements with the roller.

2. In a telegraphone, a record member, record member storage means comprising a feed reel and a take-up reel, means for driving the takeup reel, two resilient record member tensioning means, a freely rotatable roller of high inertia engaging the member between the tensioning means and a signal translating device having guides for and cooperating with the member, said member being looped around the roller with the looped portion passing through the guides and the translating device.

3. In a telegraphone, a magnetic tape, driving means therefor, freely rotatable means of high inertia engaging the tape and driven thereby at the average speed imparted to the tape by the driving means, a spring tensioned idler engaging the tape on each side of the inertia means and translating magnets cooperating with the tape between the spring tensioned idlers.

FREDERICK G. BUHRENDORF.