Cassette tape recorder

A tape transport system for cassette tape recorders wherein a member engages the drive belt between the two flywheels and exerts a dragging action, such that the belt lengths each side of the member will be respectively tight or not tight according to the direction of rotation of the drive pulley thus increasing the traction on the tight length of the belt. The corresponding pulley will rotate at a slightly higher speed than the other pulley and the tape length between the two transport units will always be automatically tightened up.

This invention refers to improvements in the drive system for cassette tape 
recorders comprising two tape transport units. 
As it is well known in the art, cassette tape recorders of a certain type 
comprise two tape transport units, the motor drive being transmitted 
thereto using a belt drive by means of a pulley integrally formed with the 
drive shaft and two pulleys generally provided on the periphery of the 
flywheel which is integrally formed with each of the tape transport units. 
Each tape transport unit comprises capstan and a pinch roller associated 
thereto and the magnetic playback, record and erase head or heads are 
located between these two tape transport units. 
In the recorders of this type two tape transport units are utilized in 
order to obtain a tape speed as constant as possible, in the only possible 
direction, thus improving the playback of the recorder. 
Also the recorders provided with reverse operation comprise two tape 
transport units, one of these units being used for the normal operation 
and the other for the reverse operation thereof. 
The operation of these two types of cassette tape recorders comprising two 
tape transport units is not completely satisfying in the former and it is 
not as satisfying as it could be in the latter. 
The recorders comprising two tape transport units and unprovided with 
reverse operation have a drawback in that, since the two transport units 
acting simultaneously on the tape rotate at the same speed, these 
transport units cannot exert any tensioning action on the tape length 
comprised therebetween, as it would be desirable both for tensioning the 
tape length engaging the magnetic head, in order to improve the recorder 
characteristics, and for tightening up any undesirable slack in this 
length. 
On the other hand, in the recorders comprising two tape transport units and 
provided also with reverse operation, the possibilities offered by the 
presence of these two transport units are not completely utilized since 
these units are used one at a time with a considerably inefficient use of 
the components, as mentioned above. 
Accordingly, it is an object of the invention to provide a tape transport 
system for cassette tape recorders overcoming all the above-mentioned 
drawbacks, which tape transport system comprises two tape transport units 
and the drive associated thereto. 
The invention provides a tape transport system for cassette tape recorders 
comprising two tape transport units, wherein both units exert a gripping 
action on the tape and the transport unit located downstream of the 
magnetic head rotates at a higher speed than the transport unit located 
upstream thereof. 
Furthermore, the system of the invention presents this desirable 
characteristic also for the reverse operation. 
According to the improved system of the invention a member adapted to 
engage the drive belt between the two flywheels exerting a dragging action 
thereon is provided in the drive system. 
This member separates the belt into two distinct lengths each comprised 
between the drive pulley and the member. These two belt lengths will be 
respectively tight or not tight according to the direction of rotation of 
the drive pulley. With such an arrangement the dragging action exerted on 
the belt will increase the traction on the tight length of the belt. 
The higher traction on the tight length of the belt determines a relevant 
extension of this length and, accordingly, an apparent increase in the 
diameter of the circumference along which the belt lies in respect of the 
pulley formed by the flywheel of the tape transport unit located 
downstream of the member of the invention in the direction of movement of 
the belt, which pulley will rotate at a higher speed. The tape transport 
unit located downstream of the magnetic head corresponds to this flywheel 
and, according to what stated above, the tape length comprised between the 
two transport units will always be automatically tightened up.

Particularly with reference to FIGS. 1 and 2, the improved system of the 
invention is utilized for driving the tape in a cassette tape recorder 
wherein drive pulley 10, integrally formed with the shaft of the electric 
motor of the recorder (not shown), transmits the movement of this electric 
motor to flywheels 11 and 12. The two capstans of the tape transport units 
are integrally formed with flywheels 11 and 12 and, as it usually happens 
in the recorders of this type, they are located on the opposite side of 
bottom plate PB in respect of the side shown in the figure and they are 
not illustrated therein. 
The system is driven by a drive belt CT received into the race of pulley 
10, the suitable race on the periphery of flywheels 11 and 12 and the race 
of intermediate or idle pulley 13. 
For the purposes of the invention the construction and operation of the 
improved system of the invention will be described supposing that idle 
pulley 13 and flywheels 11 and 12 are independently supported on bottom 
plate PB so as to freely rotate in respect thereto through drive belt CT 
driven by drive pulley 10. 
It will be evident that idle pulley 13 will rotate about its axis while 
flywheels 11 and 12 will rotate together with their axes, the 
corresponding tape transport capstans being integrally formed therewith. 
With the above described construction of the drive, flywheels 11 and 12 
will rotate in the same direction as drive pulley 10, changing the 
direction of rotation whenever the pulley direction is changed. 
Accordingly, it is an object of the invention to cause flywheel 11 to 
rotate at a higher speed than flywheel 12 when drive pulley 10 rotates in 
the direction of arrow F1 and, conversely, flywheel 12 to rotate at a 
higher speed than flywheel 11 when pulley 10 rotates in the direction of 
arrow F2. For a better understanding of what stated above in the first 
part of the description, FIG. 1 schematically shows also magnetic tape NM 
which will be of course on the other side of bottom plate PB in respect of 
the drive system, the two directions of movement of tape NM corresponding 
to the rotation of drive pulley 10 either in the direction of arrow F1 or 
in the direction of arrow F2 being indicated by the same arrows. 
In order to obtain a different angular speed of flywheels 11 and 12 so that 
the two tape transport units keep the tape length comprised therebetween 
in a tight condition according to both directions of rotation of drive 
pulley 10, the drive system of the invention comprises a member adapted to 
exert a dragging action on drive belt CT, thus limiting the free movement 
thereof. 
In a first embodiment of the invention shown in FIGS. 1 and 2, an axis 14 
is mounted on bottom plate PB between flywheels 11 and 12. Axis 14 
supports a race pulley 15, the position of axis 14 and the diameter of 
pulley 15 being such that pulley 15 modifies the path of the belt length 
comprised between flywheels 11 and 12, thus forming a loop which, in the 
illustrated embodiment, is directed inwardly of the periphery of these 
flywheels. 
Axis 14 also supports a friction device 18 acting on pulley 15 to prevent 
the rotation thereof. 
This friction device comprises a friction wheel 18 having an upwardly 
protruding peripheral edge 19 and placed below pulley 15 and a compression 
cup-shaped spring 20 acting between bottom plate PB and the lower portion 
of friction wheel 18, thus urging protruding edge 19 thereof against the 
lower surface of pulley 15. 
It should be noted that both friction wheel 18 and cup-shaped spring 20 are 
provided with a central elongated opening and are fitted onto lower 
section 21 of axis 14 which is correspondingly shaped so as to prevent any 
angular movements of spring 20 and wheel 18 in respect thereto. 
With such an arrangement, pulley 15 cannot rotate freely due to the 
friction exerted thereon by edge 19 of friction wheel 18 and, accordingly, 
pulley 15 will exert a strong dragging action on moving drive belt CT. 
This dragging action will cause either belt length 22 or belt length 23, 
both comprised between the contact points of belt CT with pulley 15 and 
drive pulley 10, to be highly tensioned depending on the rotation of drive 
pulley 10 in the direction of arrow F1 or F2, disregarding the effects of 
idle pulley 13 on the drive. 
The traction exerted on belt length 22 by the dragging action of friction 
pulley 15 when drive pulley 10 rotates in the direction of arrow F1 will 
cause length 22 and particularly the arcuated length thereof engaging 
flywheel 11 to be highly lengthened while length 23 will be less tight. 
Accordingly, as mentioned above, the movement of drive belt CT will be 
transmitted to flywheel 11 at a higher speed than to flywheel 12 so that 
the former will rotate at a higher speed than the latter. Accordingly, if 
considering the movement of magnetic tape NM schematically shown in FIG. 
1, which movement occurs in the direction of arrow F1 in this case, the 
tape length comprised between the upstream capstan integrally formed with 
flywheel 12 and the downstream capstan integrally formed with flywheel 11 
will be subjected to a traction keeping it suitably tight, as desired. 
Evidently, changing the direction of rotation of drive pulley 10, which 
will thus rotate in the direction of arrow F2, the same phenomenon will 
occur for belt length 23 which will be now subjected to a strong traction 
causing flywheel 12 to rotate at a higher speed than flywheel 11 thus 
tensioning the tape length comprised between the two capstans, which tape 
will now move in the direction of arrow F2. 
Referring now to FIGS. 3 and 4, there is shown therein a second embodiment 
of the invention by which the same phenomenon as described above with 
reference to FIGS. 1 and 2 is obtained. 
The embodiment of FIGS. 3 and 4, wherein the parts identical with or 
similar to the parts of the first embodiment are referred to with the same 
reference numbers increased by 100, is applied to a drive system 
comprising a drive pulley 110, two flywheels 111 and 112 and an idle 
pulley 113. 
In this embodiment, the member adapted to exert a dragging action on belt 
CT is a wheel 115 supported idle by a fork-shaped element 114 integrally 
formed with a lever 130 pivoted on plate 132 through pin 131. 
Plate 132 is supported on bottom plate PB through two elongated openings 
133 each receiving a pin provided with a head 134 integrally formed with 
bottom plate PB. 
Plate 132 carries a pin 135 having the end of a traction coil spring 136 
anchored thereto, the other end of spring 136 being anchored to a pin 137 
integrally formed with bottom plate PB, spring 136 being so shaped as to 
elastically pull end 138 of plate 132 towards pin 137, which thus acts as 
a blocking element. 
Pins 139 and 140 are also integrally formed with plate 132, these pins 
being placed on both sides of lever 130 thus forming two blocking elements 
for suitably limiting the angular movements thereof. 
With such an arrangement the dragging action on drive belt CT is exerted by 
wheel 115 which follows the movements of drive belt CT urging the same 
against flywheel 111, when drive pulley 110 rotates in the direction of 
arrow F1 (FIG. 4), and against flywheel 112 when drive pulley 110 rotates 
in the direction of arrow F2 (FIG. 3). 
The angular movements of lever 130 from the position of FIG. 3 to the 
position of FIG. 4 and vice versa, of course, are caused by the friction 
of the belt against wheel 115 and they are limited by blocking elements 
139 and 140, respectively. 
Evidently, the construction comprising sliding plate 132 and spring 136 
provides the system with the suitable elasticity. 
It will be evident that the dragging action in this second embodiment is of 
a different nature from the dragging action exerted in the first 
embodiment, since it is due to wheel 115 which tends to wedge between 
flywheel 111 (or 112) and pin 131 and to grip drive belt CT against the 
flywheel. 
Accordingly, while devising the mechanism the system should be so designed 
that this action is neither so strong as to block the belt nor so weak as 
to be insufficient for tensioning the tight length of the belt. This can 
be obtained by suitably acting both on the position of pin 131 in respect 
of flywheels 111 and 112 and the extension of the front arm of lever 130 
and on the bias of spring 136 and the position of blocking element 137. 
Also in this embodiment the action of wheel 115 will tighten up belt length 
122 according to rotations in the direction of arrow F1 and belt length 
123 according to rotations in the direction of arrow F2, causing flywheel 
111 to rotate at a higher speed in the first case and flywheel 112 to 
rotate at a higher speed in the second case. 
The third embodiment shown in FIG. 5, wherein the parts identical with or 
similar to the parts of FIG. 1 are referred to with the same reference 
numbers increased by 200, is less complex and comprises a shoe member 215 
secured to bottom plate PB between flywheels 211 and 212, thus causing 
drive belt CT to form a loop. 
With such an arrangement, the dragging action on the movement of drive belt 
CT is due to the friction exerted thereon by the abutment against the 
periphery of member 215, this friction being high also owing to the 
pronounced arcuation of the loop. 
A further possible embodiment of the invention is shown in FIG. 6, wherein 
the parts identical with or similar to the parts of the embodiment of FIG. 
1 are referred to with the same reference numbers increased by 300. 
In this embodiment the member adapted to exert a dragging action on belt CT 
is an idle pulley 313 and, accordingly, the path of belt CT has been 
suitably modified as shown in the figure. 
For the purposes of the invention, pulley 313 could be a friction pulley as 
pulley 15 described and illustrated in FIGS. 1 and 2. 
However, since as it is well known to those skilled in the art, cassette 
tape recorders are all provided with a friction device connected to the 
drive shaft of the tape winding up reel, this embodiment of the invention 
is particularly intended to utilize this friction device which can either 
be formed by pulley 313 or connected thereto. In this latter case the 
friction device is not shown in the figure since it will be sufficient to 
note that it is suitably connected to pulley 313 which makes part of the 
drive system transmitting the movement of the motor to flywheels 311 and 
312. 
It will be evident that in both cases the direct or indirect provision of a 
friction element in the belt drive will cause either flywheel 311 to 
rotate at a higher speed, according to a rotation of drive pulley 310 in 
the direction of arrow F1, or flywheel 312 to rotate at a higher speed 
according to a rotation of drive pulley 310 in the direction of arrow F2. 
It will be evident from the embodiments described and illustrated above 
that the invention fully reaches the objects thereof. 
It will also be evident that the invention is not limited to these 
embodiments and it can be realized also in a different manner without 
departing from the scope and concepts thereof. 
For example, one of the two belt lengths can be tightened up in respect of 
the other making use of a braking member acting on either one or the other 
flywheel.