Note: Descriptions are shown in the official language in which they were submitted.
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INTEGRAL PLATEN RIBBON CARTRIDGE
Field of the Invention
This invention relates to serial or line impact
printers and mechanisms in general and specifically
to ribbon cartridges and platen elements for use in
such machines.
Prior Art
Numerous ribbon cartridges are known in the
art. These generally fall into two categories. In
the first category, ribbon is wound from reel to reel
within the cartridge by engagement of one of the reels
with a power drive source external to the cartridge.
Such ribbons are generally caused to traverse a
printing area to supply a fresh inked surface be-
tweet an impact printer and a mark able medium such
as a sheet of paper positioned over an appropriate
platen which is an integral part of the printing
machine.
A second category of prior art ribbon cartridges
are designed to house a continuous loop of ribbon.
The ribbon may or may not have a twist in it to create
a Mobius loop and is contained within a cassette body.
Means are provided either within the cassette or in
the printing machine for withdrawing the ribbon from
the cassette, feeding it past the printing area between
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a platen and an impact member and returning it to the
cassette via a drive means for stuffing it compactly
in a random or serpentine fashion within the body of
the cassette.
Both of the known prior art ribbon cassette
categories contemplate an inked ribbon or web or one
which is suitably coated with carbon film or the like.
Additionally, both categories utilize platens which
are an integral part of the printing machine. The
ribbon must be drawn from the cassette and exposed
to impact between an impact member and a platen
during a portion of its journey external to the body
of the cassette. Such ribbons or webs are subject
to continuous wear when the printer is in use and
are often replaced during the life of a printing
machine. A typical ribbon may have a useful life
of only two to six million character impacts. The
printing machines in which they are employed typically
have a finely finished, costly metal bar or resilient
carefully formed roller platen or the like which
serves as the impact resisting element in the printer
for the life thereof.
Where wire matrix printers are employed, the
platen element is often a metal bar or strip which
is carefully machined and must last for the life of
the printer. This is a fairly expensive component
to manufacture. It also requires that the framework
and structure of the printer be very carefully aligned
with the impact member or print elements to maintain
an even printing character intensity. The expense
of this accurate assembly and/or provision for adjust-
mint also adds a considerable portion of cost to the
machine.
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In addition, where hard, wear resistant surfaces
are used for the platen material, the repeated imp
pact of the impact member creates a significant noise
level which can be objectionable in many circumstances.
While resilient surfaces may be applied to the
metal platen by a coating of elastomeric material or
the like to reduce noise, this material is more sub-
jet to wear and leads to a more frequent replacement
of the expensive platen element.
Objects of the Invention
In light of the foregoing known deficiencies of
lo the prior art ribbon cassettes and platens, it is an
object of the present invention to provide an improved
replaceable cassette and platen assembly that avoids
the difficulties mentioned for designs in which these
elements are separate.
Yet another object of the present invention is
to provide an improved ribbon cassette and platen
assembly having reduced noise generation characteristics.
Summary
The foregoing and still other unenumerated objects
of the present invention are met by providing a ribbon
cassette in which the platen member is formed as an
integral part thereof. Cassettes are typically made of
molded plastic which, according to the dormitory of
material employed, may be either relatively hard and/or
brittle or soft and resilient. Making the cassette
of normal injection molded thermoplastic materials is
relatively commonplace in the art, but employing such
material as a platen integral with the cassette itself
represents an improvement. Not only is the high cost
of the usual separate platen which is a part of the
printing machine eliminated, but the platen need
only last as long as the ribbon material instead of
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for the life of the printing machine. Additionally,
since the plastic material is substantially the same
resiliency as an elastomeric coated hardened platen,
noise reduction it significant. While the platen
surfaces may wear out much sooner than a normal
platen, it is only required to last for the life of
the ribbon and is replaced when the cassette is
replaced for the purpose of presenting a fresh ink
supply. The platen is thus an integral part and of
lo the same material as the cassette body. Means are
provided for guiding the ribbon from an exit point
in -the cassette body across the surface thereof
which is utilized as a platen and back into the
cassette in the usual manner. The cassette is
modified in design to provide a space between the
ribbon and the platen portion of the cassette into
which a printing paper may be introduced where
front printing is desired. For multiple copy
printing or high impact forces, the face of the
platen portion may have an integrally molded
metal insert which is inserted into the injection
mold for the plastic cassette to provide a harder
more wear resistant surface to the platen portion
of the cassette body. Means for locating the
cartridge and platen in accurate registration
with the printing element so that the printing
line is parallel to the path of the printing
element is also provided. Locating holes that cooperate
with locating pins fix to the precise location required
on the printing machine provide this function.
Brief Description of the Drawings
The invention will now be described with
reference to a preferred embodiment thereof as
depicted in the drawings, in which:
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Figure 1 illustrates a top or plan view of
a typical ribbon cassette and platen unit according
to the present invention and having its top cover or
wall partially broken away to show the interior.
Figure 2 illustrates a cross-sectional view
horizontal elevation of the combined cassette and
platen depicted in Figure 1.
Figure 3 illustrates an enlarged partial
section of a modification of the preferred embody-
mint shown in Figures 1 and 2 and further depicting
the locating means for accurate registration of
the platen surface and thy printing machine.
Specification
.,
Turning to Figure 1, a plan view of a pro-
furred embodiment of the present invention is
illustrated. The cassette body 1 is preferably
made of injection molded thermoplastic in the
conventional manner well known to those of skill
in the art. The inked ribbon 2 is illustrated
as a continuous or serpentine, randomly stuffed
loop which is contained primarily in the body of
the cassette I Guide arms or fingers 3 extend
from the main body portion of the cassette 1 to
support the ribbon 2 spaced apart from the platen
surface 5 which is a portion of the outer wall of
cassette 1. This permits paper to be inserted
between the ribbon 2 and the platen surface 5
for printing thereon and maintains alignment
between the ribbon 2 and surface 5 in both the
horizontal and vertical directions. Guide pin
locating holes 4 are also illustrated. These
holes cooperate with fixed location guide pins
rigidly affixed in a printer mechanism (not shown),
to accurately position the platen surface 5 and
the cassette 1 relative to the intended printing
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line for accurate registration with an impact
printing means (also not shown).
An internally contained drive and pressure
roller set 6 are shown in Figure 1 and will be under-
stood by those of skill in the art to comprise the
usual stuffing rollers for drawing ribbon 2 into
the body of cassette 1. The ribbon exits from the
cassette 1 through an aperture (not shown) neat the
other end of the cassette. Details of this are well
-- 10 known to those of skill in the art and form no part
of the present invention. While the stuffing roller
form of cassette embodiment is illustrated, this is
not an element of the present invention and it will
be understood by those of skill in the art that reel-
to-reel cassette ribbons systems may be equally em-
plowed. It is the structure of the cassette case
and its cooperation with the ribbon and printer with
the cassette forming the platen as well that is of
importance in this invention.
Turning to Figure 2, a horizontal cross-section
elevation view taken through the structure depicted
in Figure 1 is shown.
As may be seen in Figure 2, a cassette body 1
has a hollow interior portion 7 for containing
reels or a randomly folded or serpentine stuffed
ribbon as depicted in Figure 1. Ribbon 2 is
supported on the guide arms or fingers 3 at either
end of the cassette as shown in Figure 1 and a
small gap or space 9, through which the paper center
line 8 passes, is shown. The paper which is to be
printed upon is passed between the backside of
ribbon 2 and the front surface of the platen 5
and can be impacted by an impacting means driving
against the opposite face of the printing ribbon.
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The center line for the locating pin holes 4 is also
shown and it will be understood by those of skill in
the art that accurate registration between the front
surface of the platen 5 and the center lines of the
locating holes 4 will cooperate with precisely located
pins within the printing machine to accurately place
the platen 5 in a position parallel to the printing
line and to the printing head (not shown).
As will be instantly appreciated, the platen
surface S is a directly exposed portion of the wall
of the cassette 1 and is formed of the same material,
namely injection molded thermoplastic. Such a material
is more resilient than hardened or machined steel or
similar metal platens normally employed and will
therefore experience a greater degree of wear. How-
everyone the present invention, this greater degree
of wear of the platen is unimportant since the
platen need only last for the life of the ribbon
rather than for the life of the printing machine.
The resilience of the platen surface greatly no-
dupes the impact noise of printing which is an
additional benefit.
Testing has shown that such plastic cassette
surfaces function quite well as platens and are not
subject to exceptional wear prior to the time that
the ribbon has expired. However, if extremely
small dots such as for fine, high resolution ma-
trip printing are required r the impact and penes
traction forces may be relatively greater and a
hardened surface may be applied to the platen 5.
This may also be necessary in the case where mull
triple copies are desired since generally higher
print forces are encountered. The plastic cassette,
however, still functions to partially reduce noise
by resiliently absorbing forces transmitted from the
hardened surface.
Turning to Figure 3, an enlarged partial view
of a modification of the cartridge as depicted in
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Figure 2 is shown. In Figure 3, the printing element
10 is schematically shown as impacting hammer or dot
matrix element positioned along the printing center
line adjacent to the opposite surface of ribbon 2
from which the platen surface 5 is positioned. Platen
surface 5 as depicted in Figure 3 is shown to be a
metallic insert which is normally put in place within
the injection mold when the plastic 1 is injected
to form the cassette body. The metal surface 5 enables
the higher printing forces to be withstood and adds
no significant cost to the overall cassette. Typic
gaily a thin 22 or 24 gauge piece of cold rolled
sheet steel or the like is sufficient to harden the
platen surface for these conditions sufficiently to
last the life of a ribbon 2.
Also shown are the guide fingers 3 and the
aperture 9 through which paper along center line 8
- can be inserted. The locating pin apertures 4 with
their center line are also indicated as is the hollow
central body cavity 7 for the cassette.
The overall action and cooperation of the elements
of the present invention may now be clearly understood.
The locating holes are accurately and precisely pox
sitioned with respect to the platen surface 5 on the
surface of the cassette 1 and cooperate with precision
locating pins in the printing machine to accurately
position the platen surface in registration with -the
30 - printing line and print elements. The resilient
nature of the platen reduces impact printing noise
. . .
as has been pointed out and, due to its manufacture
by injection molding with the cassette, eliminates
the cost of an entire separate element in the overall
printer structure in the form of a separate platen
as is usually employed. The fact that the platen
is made of the same thermoplastic material and is
formed on a surface of a cassette entails hardly
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any additional cost whatsoever and is therefore of
great benefit in producing an economical and quiet
operating printer.
The use of the cassette surface as the platen
element is not limited to the specific embodiment
shown since reel-to-reel type ribbon cassettes
may be similarly employed. Also, it is not recess-
cry to insert the paper between the ribbon and the
platen surface since back printing can be performed
with the paper positioned between the impact eye-
mint and the front surface of the ribbon 2 if
desired. In such an operation, as will be readily
understood by those of skill in the art, character
inversion may occur and hence, the font of the
printing element may similarly have to be in-
vented. If serial dot matrix printing is employed,
electronic character reversals are necessary from
time to time as appropriate in this type of printing.
The registration or locating means in the form
of the locating apertures 4 are positioned in pro-
else relation to the platen surface 5 which is a
portion of the surface of the cassette 1. Together
they function to create an accurately positioned
platen in the printing machine and also serve to
accurately position the ribbon with respect to the
intended line of printing. Hence, the overall in-
tegral structure of ribbon, guide fingers, platen
Jo 30 and cassette body is a compact, low cost, quiet
operating and easily replaced subassembly for use
in a variety of impact printers.
Therefore, having thus described our invention
with reference to a preferred embodiment thereof and
having indicated some obvious modifications, it will
be apparent to those of skill in the art that many
departures from the specific design may be encom-
passed without departing from the spirit and scope
ox the invention.
