Note: Descriptions are shown in the official language in which they were submitted.
~175~01
The present invention relates to ribbon cassettes for
printing machines e.g. typewriters, teleprinters or other business
machines.
Ribbon cassettes are lcnown which include a supply reel
and a take-up reel mounted for movement along a slot. Thus German
Offenlegungsschrift No. 28 20 266 describes a ribbon and corxecting
ribbon assembly for typewriters which contains a supply reel and a
wind-up reel, where the axis of rotation of the supply reel can be
moved and whereas the axis of rotation of the take-up reel can be
displaced along a guide slot.
Furthermore, German Offenlegungsschrift No. 25 53 329
discloses a ribbon cassette having a reel mounted in a manner which
allows the reel to be displaced along a circular path. However,
these known ribbon cassettes occup~ a great deal o~ space within
the printing device and are of elaborate construction.
An object o the invention is to provide a simple, com-
pact ribbon cassette.
The invention provides in a ribbon cassette for printing
devices having a cassette housing having a top and a bottom, a feed
reel and a take-up reel for transporting a ribbon contained in said
housing, said feed reel and said take-up reel each having a central
ly disposed hub about which each reel rotates, the improvement of:
a winding core ~or each reel surrounding each hub against which
said ribbon is carried on said reels; said housing having two pairs
of aligned guide slots in the top and the bottom thereof; at least
one straight guide pin carried on each of said hubs and extending
substantially perpendicularly through said slots in said housing for
permitting and guiding displacement of said reels along said slots;
B -2-
1 175001
a first guide roller in said housiny around which said ribbon moves
as the ribbon leaves said feed reel; a second guide roller around
which said ribbon moves immediately prior to being wound on said
take-up reel; and a biassing means in said housing connected to
each of said reel~ for exertiny outward pressure thereon for main~
-taining a selected ribbon tension, said feed reel and said take-up
reel respectively moving in said pairs of guide slots as said
ribbon is transferred from saia feed reel to said take-up reel.
Preferably, said biassing means consists of at least one
spring element, such as a single spring member positioned between
said reels.
Preferably, at least the take-up reel is provided with
a feed wheel for driving thereof, the or each feed wheel being
accessible from the exterior of the housing.
Each reel is preferably provided with at least one guide
pin in the form of a spigot arranged for engagement in the respec-
tive pair of slots. Preferably, at least on0 guide spigot is
arranged to move along an associated slot in accordance with the
amount of usable ribbon remaining in the cassette ko serve as an
indicator of said amount, said associated guide slot having scale
marks over the region of movement of the guide spigot. The indi-
cator is preferab~y provided on the supply reel. The indicator and
the associated guide slot have differing colours.
Prefer~bly, a friction component is arranged in a cover
of said housing to bear on the supply reel to produce a braking
torque therefor.
For a better understanding of the invention and to show
how the same may be carried into effect,
- ~17500~
. _ reference ~ill now be made b~ way of example to the'
accompanying drawings~ ln which:-
Figure l is a plan view o~ a ribbon ~assette
~ith the coves removed; and
Figure 2 is a side view of the ribbon cassette.
The illustrated ribbon cassette is suitable
for exchangeable use in a teleprinter and comprises a
cassette housing 1 of injection moulded plastic which
cantains a supply reel 2 and a take-up reel 3. Each of
~ .
the supply reel 2 and the take-up reel 3 consists of a
hub 5 provided with guide spigots 4 and of a core member
7 which is mounted for movement relative to the hub 5 and
which carries the rlbbon 6. In each case, the guide
spigots 4 are mounted for movement along a respective one
of gulde slots 8 and 9. Each slot is formed both in the
lower part of housing 1 and in a cover 21 of the
housing.
Thus supply reel 2 e~gages with its guide
spigots 4, in the guide slots 8 of the lower part of the
housiny and the cover 21. From reel 2, the ribbon 6
pa~ses ovèr a guide roller 10~ a spring 11 which
dete~mines the ribbon tension, guide members 1,2 and 13, and
a further guide roller 14 onto the core member of the take-
up reel 3. Reel 3 is provided with a feed wheel 15 to which
access may be gained from the exterior through a gap 16
in the cassette housing. The transfer of torque from the
feed wheel 15 to the take-up reel 3 is effected by
fri,ction. For this pur~ose, a rough friction surface is
--4--
- I 17~0~1
,
provided on the coxe ~f the ~eed wheel 15. This surface
is ~orced lnto contact with the outer la~er of the ribbon
o~ the wind~up reel 3, as hereinafter e~plained.
If the ribbo~ cassette is intended to trancpor
the ribbon in both~directions, a further feed wheel lS
may also be arranged on the left hand side of the cassette
to dri~e the other reel 2 when this serves as a take-up
reel.
A~pressure spring 17 consisting of a single
lQ member is Lnserted in a si~ple manner into holders 18 of
the cassette housing to produce the xequisite pressure
force between the supply reel 4 and the guide roller 10
and between the take-up reel 3 and the feed wheel 15.
The pressure spring 17 is inserted into openings in the
hubs S.
A lateral pressure force and thus a braking
tor~ue is produced upon the supply reel by a foam component
19 which is arranged in the cover of the cassette housing
_~ and whlch acts upon the supply reel 2 when the cover
is in place. In addition, the ribbon is subject to the
tension foxce of the spring 11. This spring 11 ensures
correct biassing of the ribbon and allows a certain
length adjustment.
; As both the supply reel 2 and the take-up
reel 3 are arranged so as to be displaceable in ~he~
cassette, a particularly compact structure of the cassette
container is possible. The winding state of the cassette
i.e. the amount of unused ribbon can be detexmined from
_- -5
- ~ 17SO~
the po~ition o~ the ~uide splgot 4 in the guide slot 8
o~ the supply reel 2. In dependence upon the winding
state of the cassette~ this guide spigot 4 moves along
the guide slot 8. The mark ~ (sho~n in broken lines)
on the guide slot 8 simpliies reading.
In order to facilitate read-off even under
poor llght conditions, the guide spigot 4 and the
surrounding ribbon container housing 1 may be of differing
- ~olours.
~hus, for example, the guide spigot 4 can
consist of a light-transparent synthetic material whereas
the ribbon cassette housing normally consists of black
synthetic material.
It is possible to provide the fullness
indicator either on the supply reel or the take-up reel.
However, provision on the take-up reel gives a reading
which is dependent upon the typing operation. For
example, the take-up reel may be wound up irregularly
~' whereas the unwinding state of the supply reel is clearly
defined and thus is substantially more accurate.
- It should be apparent that the displaceability
of both *he supply reel and the take up reel facilitates
a relatively narrow construction of the cassette housing.
The ribbon tension on the ~assette remains virtually
constant during the entire rewinding process.
As a result of the change of position of the
guide spigot of the supply reel along the guide slot 8
1175~01
with scale marks arranged thexeuponl it ls possible to
follow the wlnding st~te o~ the ribbon cassette in a
partlcularly simple manner. As~ in a pre:Eerred
embodiment, the guide spigot po5sesses colouring different
from that of the surrounding cassette housing, the
winding state is easily visible rapidly even under
unfavourable lighting conditions. No parallax errors
are likely to occur with the illustrated construction.
The illustrated cassette may be secured onto
the receiying platform of a printing machlne by means of
an engagement--element 20.
