Tape recorder designed for low power consumption and resistance to operational failure under high stress condition

Uber, P. W.

English

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TAPE RECORoER 
Filed Sept. 6, 1967 2 Sheets-Sheet 1 
i 
38 
9' 
BY 
ATTORNEYS 
Filed Sept. 6, 1967 
P. w. UBE 
TAPE RECORDER 
2 Sheets-Sheet , 2  
BY 
t e 
National Aeronautics and Space Administration 
U.S. CI. 242-192 4 Claims 
XSCEOSU 
A tape recorder including a capstan having a resilient, 
deformable cylindrical drive surface adapted to directly 
couple and simultaneously drive both magnetic tape take- 
up and supply reels by frictional surface engagement 
with the outer layer of magnetic tape carried on the 
periphery of each reel. The takeup and supply reels are 
supported on slidably mounted carriages and nonaccumu- 
lative force springs are provided to  control movement 
of the carriages with respect to the capstan, so as to 
maintain a greater contact force between the capstan 
and the magnetic tape carried on the periphery of the 
takeup reel than on the magnetic tape carried on the 
periphery of the supply reel, whereby magnetic tape dur- 
ing transfer between reels is subjected to a desired tension. 
The invention described herein was made by an em- 
ployee of the United States Government and may be 
manufactured and used by or for the Government for 
governmental purposes without the payment of any royal- 
ties thereon or therefor. 
SUMMARY 
The present invention relates to recorder and more 
particularly to tape recorder characterized by low power 
consumption, simplicity of design and resistance to oper- 
ational failure under high stress conditions. 
Direct drive mechanisms for magnetic tape recorders 
wherein the driving force is imparted by a capstan in 
contact with the outermost tape layer on one of the 
recorder reels are well known as evidence lby the patent 
to Iida 3,161,361. A particular disadvantage of mech- 
anisms of this type includes the requirement that there be 
provided a friction or like brake for the supply reel, which 
brake tends to increase the recorder's power consumption 
and is subject to failure due to wear and environmental 
conditions. 
In attempting to design a recorder having a low power 
consumption, it has been proposed to drive both supply 
and takeup reels so as to avoid friction braking of the 
supply reel, by various means such as the utilization of 
a driven endless band or belt which passes about the 
periphery of each reel. However, the peripheral belts 
normally employed are subject to fatigue failure and 
exhibit nonuniform strain characteristics along their 
length, which results in the nonuniform driving of the 
reels. 
Accordingly, it is an object of the present invention 
to provide a tape recorder not subject to the disadvan- 
tages mentioned above. 
It is a specific object of the present invention to provide 
a recorder having minimum power consumption char- 
acterized by the utilization of a single capstan for simul- 
taneously driving both supply and takeup reels by surface 
engagement with the outermost layer of magnetic tape on 
each reel. 
It is a further object of the present invention to provide 
a tape recorder having a single capstan adapted to simul- 
taneously drive both a supply and takeup reel in such a 
manner that the magnetic tape passing between the reels 
is subject to a predetermined control tension. 
Still further, it is an obj to provide a tape recorder 
particularly adapted for use as an information recorder 
under high stress conditions encountered, for instance, in 
rocket and high altitude balloon test. 
These and other objects of the present invention will 
be more fully understood with reference to the following 
description taken with the accompanying drawings in 
which: 
FIGURE 1 is a perspective view of the tape recorder 
10 of the present invention; 
FIGURE 2 is a bottom plan view of the tape recorder 
shown in FIGURE 1; 
FIGURE 3 is an inverted vertical sectional view taken 
generally along the line 3-3 in FIGURE 2, having por- 
15 tions broken away for clarity; and 
FIGURE 4 is a fragmentary view illustrating the 
manner in which the surface of the capstan is deformed 
during driving engagement with the outer layer of mag- 
netic tape on the supply and takeup reels. 
The tape recorder according to the present invention is 
generally designated as 1 in the figures and includes a 
base plate 2, which is adapted to support a conventional 
recording and reproduction head 3, erasing head 4, tape 
guides 5 and drive motor 4. 
To facilitate understanding of the present invention, it 
will be understood at the outlet that in the preferred 
embodiment to be described, tape recorder 1 only pos- 
sesses a recording capability. Thus, the tape reels will 
be identified according to function as magnetic tape supply 
30 and takeup reels 7 and 8, respectively. Also, it will be 
understood that in the preferred embodiment, reels 7 and 
8 are directly coupled and simultaneously driven by a 
motion transmitting member, such as capstan 9, disposed 
in frictional surface engagement with the outer layer of 
35 magnetic tape carried on each reel, whereby upon rota- 
tion of capstan 9, magnetic tape 10 is transferred between 
the reels along the path shown in FIGURE 1 as being 
defined by tape guides 5 and heads 3 and 4. 
Now referring particularly to  FIGURES 1 and 2, it will 
40 be seen that supply takeup reel 8 are rotatably 
supported on shafts which are in turn mounted 
on reel carriages, generally designated as 13 and 14, re- 
spectively. Reel carriages 83 and 14 are preferably of 
identical construction and each includes an integrally 
45 formed central web portion IS and four laterally extend- 
ing arm portions 16, which are each bored to receive a 
cylindrical antifriction bearing 87. Bearing 17 and thus 
reel carriages 13 and 14 are slidably supported on pairs 
of spaced parallel guide shafts 18 and 19, which are 
50 mounted on the under surface of base plate 2 by suitable 
end brackets 20 and central brackets 21. 
Again referring to FIGURES 1 and 2, it will be seen 
that base plate 2 is provided with generally rectangular 
cutouts 22 and 23 in order to permit unobstructed sliding 
55 movement of reel carriages 13 and 14 and thus supply 
and takeup reels 7 and 8 with respect to capstan 9. Also, 
it will be seen that in the embodiment illustrated, the ro- 
tational axis of the capstan and takeup reels are parallel 
and disposed within a common plane, and that sliding 
60 movement of carriages 13 and 14 is in a direction parallel 
to  such plane. 
Capstan 9 is shown in FIGS. 1, 3 and 4 as being in the 
form of a sleeve 9' formed from a resilient deformable 
material, such as rubber, which is k e d  to one end of a 
65 drive shaft 24. Shaft 24 is adapted to freely pass through 
a bore opening, not shown, provided in base plate 2 and 
be rotatably supported within a cylindrical bearing hous- 
ing 25, which is suitably fixed to  the under surface of base 
plate 2. In FIGURES 2 and 3 capstan 9 is shown as being 
70 driven by motor 4 through a transmission including a 
seamless elastic drive belt 24, which passes from motor 
shaft pulley 27 to  a first or enlarged dismeter pulley 28 
20 
25 
3,460,181 
3 
affixed to idler shaft 29, and a seamless elastic drive belt 
30, which passes from a second or reduced diameter pul- 
ley 31 affixed to shaft 29 to pulley 32, which is a fked to 
capstan drive shaft 24. Idler shaft 29 is journaled within 
a bearing housing 29’, suitably affixed to the under surface 
of base plate 2. For purposes of the present invention, 
motor ‘6 may be electric or spring powered. 
In FIGURE 2, reel carriages 3 and 14 are shown as 
being coupled together by means of a spring 33, which is 
freely coiled at each end thereof around spools 34 and 
35, which are affixed to  the under surfaces of reel car- 
riages 13 and 14, respectively. Preferably, spring 33 is 
a nonaccumulative force type spring, which has been sold 
under the trademark Neg’ator, and is characterized by its 
ability, when the coils thereof are mounted for free rota- 
tion, to resist withdrawal from the coils with a force which 
is constant regardless of the spring length withdrawn. 
Thus, spring 33 provides a constant force tending to bias 
the reel carriages towards one another, so as to maintain 
an initial equal and constant contact force between the 
outer layer of magnetic tape on each of the reels and cap- 
stan 9. This initial force is independent of the amount of 
tape accumulated on the respective reels. The initial or 
basic contact force provided by spring 33 is employed to 
insure minimum driving engagement between the capstan 
and reels and is determined by the maximum momentary 
unbalancing force which the recorder is expected to  en- 
counter during use. For instance, if a tape reel when fully 
loaded weighs ?4 pound and the recorder is expected to  
encounter during use, as for instance in a rocket test, a 
force of about 10 G s  in the direction of sliding movement 
of the r e d  carriages, then a spring force slightly greater 
than five pounds would be required to maintain both reels 
in driving engagement with the capstan. 
Again referring to  FIGS. 2 and 3, it will be seen that 
a second nonaccumulative force spring 36 is employed to 
increase or provide an additional contact force between 
takeup reel 8 and capstan 9. One end of spring 34 is coiled 
about takeup carriage spool 35, while the other end there- 
of is coiled about capstan drive shaft housing 25. The 
effect produced by springs 33 and 34 is best illustrated in 
FIG. 4, wherein the portion 37 of capstan 9 in engagement 
with takeup reel 8 is shown as being subjected to  a greater 
degree of deformation than capstan surface portion 38 
in contact with supply reel 4. 
For purposes of the present invention, the end coils of 
springs 33 and 36 may be either loosely coiled or be 
affixed to  freely rotatable sleeves, not shown, carried re- 
spectively on spools 34, 35 and housing 25. Also, while 
springs 33 and 36 are shown as  being loosely coiled about 
each other on spool 35, it will be apparent that the coils 
of the respective springs may be axially spaced, particu- 
larly in those instances wherein it is desirable to  discon- 
nect spring 36 lfrom reel carriage 14 and attach such 
spring for movement with reel carriage 13 so as to  reverse 
the functions of the carriages and permit recorder 1 to 
possess both recording and playback capabilities. Alterna- 
tively, an additional force spring similar to  spring 34 may 
be provided one for each carnage and selectively con- 
nected for movement therewith by suitable means, not 
shown. 
From the foregoing it will be apparent that in opera- 
tion, full supply and empty takeup reels are mounted upon 
supporting shafts 11 and 12 and magnetic tape threaded 
therebetween. Positioning of the reels and threading of the 
tape may be facilitated by providing suitable latch means, 
not shown, to retain carriages 13 and 14 in full right and 
full left positions, as viewed in FIG. 1, against the restor- 
ing bias of springs 33 and 36. Such latches additionally 
serve to space the tape reels from the driving capstan to  
prevent setting or permanent deformation thereof during 
long periods between recorder operation. Thereafter, the 
latches may be released t o  permit springs 33 and 36 to 
draw the carriages towards each other and the outermost 
into surface engagement with the resilient surface of the 
driving capstan. Suitable switch means, also not shown, 
may then be operated to energize the capstan drive motor 
and effect driving rotation of the capstan, in a clockwise 
direction, as viewed in FIG. 1, to effect transfer of the tape 
to the takeup reel. As tape transfer progresses, carriages 
simultaneously slide to  the left, also as viewed in FIG. 1, 
to compensate for the changing amounts of tape on the 
respective reels while maintaining such reels in driving 
engagement with the capstan. 
It has been found that by employing a resilient surfaced 
capstan disposed in driving engagement with the magnetic 
tape on the respective reels and providing additional spring 
36 to effect uneven deformation of the capstan, the speeds 
15 of the supply and takeup reels may be varied to  achieve 
a controlled tension of the magnetic tape during transfer 
between reels. 
The phenomena of tape tension obtained by employing 
a single resilient surfaced capstan to simultaneously drive 
20 takeup and supply reels will be readily understood by 
considering that the magnetic tape, when wound on the 
supply and takeup reels, forms relatively hard cylindrical 
surfaces. It may be shown that for deformations of the 
resilient surface of the capstan sufficient to avoid gross 
25 slippage in rolling, the surface-speed ratio of the unde- 
formed capstan vs. the hard surface presented by the 
tape, vR/vH, is less than one and decreases with increasing 
deformation of the capstan according to a non-linear 
relationship. For reference, see ASME publication 6 1- 
30 SA-67, “On the Kinematics of Rubber-Covered Cylin- 
ders Rolling on a Hard Surface,” by George N Sandor, 
June 1961. Thus, it will apparent that if the deformation 
of the capstan due to surface contact with the takeup 
reel is greater than that due to engagement with the supply 
35 reel, the surface speed of the takeup reel will be greater 
than that of the supply reel, as a function of the relative 
deformation. This phenomena may be domenstrated by 
assuming for purposes of illustration that the ratio 
vR/vH for the supply reel is 0.9045 and the ratio vR/vH for 
40 the takeup reel is 0.9000. Since vR is a constant, it can 
be shown that vH (takeup reel)/vH (supply reel is equal 
to  1.005. If it is further assumed that the supply reel 
speed or peripheral velocity is 10 inches/second and that 
the tape length between reels is 10 inohes, it may be 
determined that the speed of the takeup will be 10.05 
45 inchedsecond, and that the length of tape passing be- 
tween the reels will experience a 0.5% increase in length. 
If it is further assumed that for a given %” tape, a 1% 
elongation requires about 0.7 pound tension, the 0.5% 
5o elongation will result in a transferred tape tension of 
about 5.6 ounces. This degree of tension is sufficient to 
insure proper tape transfer and prevent the formation of 
undesirable slack loops in t,he transferred tape. Due to 
the constant force imparted by the nonaccumulative force 
55 springs, irregular tension and accompanying uneven wind- 
ing of the tape during normal use is effectively prevented. 
While a preferred embodiment of the present invention 
has been described wherein the tape reels are supported 
on slidably mounted and aligned carriages adapted to 
60 position the reels in driven contact with diametrically o p  
posite sides of the driving capstan, various alternative 
embodiments are anticipated. Exemplatory of such em- 
bodiments are to movably mount the tape reels one above 
the other for engagement with the same side of the driving 
65 capstan; to support each tape reel on a pivot arm car- 
riage which is spring loaded into contact with the driving 
capstan; t o  mount the driving capstan on a carriage for 
movement with respect to fixed axis tape reels; or to em- 
ploy a fixed axis tape reel to drive a movably mounted 
70 tape reel through a movably mounted motion transmitting 
capstan. 
Further, while in the discussion reference has been 
made to positively driving the capstan directly by a suit- 
able motor, the term positively driving or positively driven 
#layer of magnetic tape carried upon the respective reels 75 as used in the claims is meant to include an embodiment 
3,460,781 
wherein additional alternative means are employed to 
drivingly engage the magnetic tape, for instance tape 
passing from the supply reel, whereby the supply reel 
is positively driven by the forwarded tape and the takeup 
reel is driven through an idler capstan or motion trans- 
mitting member. 
Also, while a tape recording machine having only 
recording capabilities has been described in detail, it will 
be apparent that the machine may function solely as a 
play-back or erasing machine, and by providing additional 
force spring means for each tape reel accompanied by 
suitable means to selectively disconnect such springs a 
machine having both recording and play-back capabilities 
may be obtained. Further, the recorder mechanism dis- 
closed may be employed as a perforated paper tape re- 
corder with an appropriate transducer or photo pick up 
head replacing the magnetic tape recording and repro- 
duction head. Accordingly, the above discussed alternative 
embodiments, as well as additional modifications of the 
recorder of the present invention, will become apparent 
to one skilled in the art in view of the foreging de- 
scription. 
What is claimed is: 
I. In a recorder of the type for supporting a pair of 
reels of recording tape forming supply and takeup reels, 
the improvement comprising: means for supporting said 
supply reel; means for supporting said takeup reel; an- 
nular rotating tape drive means having resilient surface 
portions to contact and rotate said supply reel and takeup 
reels to feed tape from said supply to said takeup reel; 
and positioning means including a first nonaccumulative 
force type spring having its ends fixed to said supporting 
means, thereby biasing each of said supporting means for 
movement with respect to said drive means to maintain 
said drive means in surface engagement with said record- 
ing tape on said reels, and a second nonaccumulative 
force type spring having one end fixed to said means for 
5 
10 
15 
20 
25 
30 
35 
supporting said takeup reel and the other end fixed adja- 
cent said drive means, thereby biasing said takeup reel 
for movement with respect to said drive means to develop 
a greater compressive force between said takeup reel and 
said surface poritons than between said supply reel and 
said surface portions for tensioning said tape. 
2. The apparatus according to claim 1, wherein said 
drive means and said reels are mounted for rotation about 
three parallel spaced axis and supply and takeup reel sup- 
porting means further includes first and second movably 
mounted carriages, said drive means being rotatably 
mounted at a fixed point and said reels being mounted 
respectively one on each of said carriage for movement 
therewith relative to said fixed point. 
3. The combination according to claim 2, wherein said 
carriages are slidably mounted, the rotational axis of said 
drive means and said reels are disposed in a common 
plane, and sliding movement of said carriages is in a direc- 
tion parallel to said plane. 
4. The combination according to claim 2, w.herein said 
drive means is adapted to be positively driven and is 
mounted at said fixed point. 
eferences Cited 
UNITED STATES PATENTS 
2,605,056 711952 De Kanski et al. _ _ _ _  242-54.1 
2,733,069 111956 Frost et al. _ _ _ _  242-55.14 X 
3,252,669 511966 Geri _ _ _ _ _ _ _ _ _ _ _ _ _  242-55.13 
3,294,332 12/1966 Miville et al. _ _ _ _ _ _  242-55.12 
3,370,803 2/ 1968 Newel1 _ _ _ _ _ _ _ _ _ _ _ _  242-55.12 
3,370,804 2/1968 Peyton _ _ _ _ _ _ _ _ _ _ _  242-55.12 
GEORGE F. MAUTZ, Primary Examiner 
U.S. C1. X.R. 
242-55 


Tape recorder Patent

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