Note: Descriptions are shown in the official language in which they were submitted.
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1 BACKG~OUND OF THE INVENTION
l'he present invention relates to a paper and forms
handling system for a printer and more particularly to such
a system which permits continuous forms to be held ready in
the printer even while printing takes place on cut sheet
paper.
While it has previously been prop~sed to implement
the paper handling mechanism of a printer so that both cut
sheet and continuous forms can be handled, it was necessary
to completely remove the continuous fcrms paper from the
tractors typically utilized to feed such paper while
printing was being accomplished on individual cut sheets.
As is understood, the necessity of completely removing the
continuous form paper before printing on cu~t sheets requires
substantial operator intervention at each changeover. Such
time consuming operator intervention was particularly
wasteful in the context of an office environment where
frequent changeovers between continuous paper and cut sheet
are typical in the daily flow of work.
Among the several objects of the present
invention, may be noted the provision of a forms and
paper handling system for a printer which permits con-
tinuous forms to be held ready while printing takes place on
cut sheet paper; the provision of such a system in
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1 which cut sheets may be simpl~ fed to a roller platen
in the manner of a conventional typewriter; the provision
of such a system in which edge-per~orated continuous
form paper may be fed by conventional tractor assemblies
which engage the edge perforations; the provision of such
a system which is highly reliable; the provision of such
a system which is used friendly; and the provision of
such a system which is of relatively simple and inexpen-
sive construction. Other objects and features will be in
part apparent and in part pointed out hereinafter.
SUMMARY OF THE INVENTION
Briefly, in a forms and paper handling system
constructed in accordance with the present invention,
paper to be printed upon is fed past a traversable print-
head by means of a horizontally oriented roller platen.Guide means are provided for guiding a cu~ sheet from
above tangentially into contact with the rear of the
platen and causing it to follow under the platen and
past the traversable printhead. Further means, including
a pair of tractor assemblies adapted to feed edge-
perforated paper are arranged for feeding con-tinuous form
paper tangentially into contact with the bottom of the
platen where it again follows the platen up into the
printing position. Motor means are provided for driving
the platen in rotation to feed paper past the printhead.
A lever-operating clutch means is operable in a first
position lever for driving the tractor means from the
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1 motor means synchronously with the platen and~ in a
second position, releasing the tractor means from -the
platen drive means. Accordinglyl continuous forms can
be held ready in the tractor means while pr,inting takes
place on cut sheet paper.
BRIEF DESCRIPTION OF T~IE DRAWIWGS
Fig. 1 is a perspectiye drawing of a printer
mechanism constructed in accordance with the present
invention viewed from above and from the right front
corner;
Fig. 2 is a perspective drawing of the mechanism
of Fig. 1 viewed from above and from the right rear
corner showing forms tractors used in the mechanism;
Fig. 3 is a side view from the right showing a
lever-operating clutch mechanism for selectively disen-
gaging the forms tractors;
Fig.~ is an exploded view of a portion of the
mechanism showing a cam which operates a paper bail;
FigO 5 is a top view of a portion of the
mechanism illustrating the interaction of the cam with
a fixture on the printhead, carriage.
Corresponding reference characters indicate
corresponding parts -throughout the several view of the
drawings.
' DESCRIPTION OF THE PREFERRED EMBODIMENT
.
Referring now to Fig. 1, there is indicated
by reference character 11 a conventional roller platen,
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1 i.e., a platen of the type conventionally employed in
typewriters. Platen 11 is driven r through a train of
gears 13-15 from a pinion gear 17 mounted on the shaft
of a stepper motor, the stepper motor being behind an end
fr2me piece lg of the overall prlnter assembly and thus
not visible in Fig. 1.
A conventional dot matrix printhead 21, e.g.,
of the pin or needle type, is mounted on a carriage
assembly 27 riding on guides 31 so as to be traversable
along the platen 11. A ribbon cartridge 33 provides an
endless ribbon, a portion of which 35 extends àlong the
platen. Thus, byiappropriate energizing the printhead
25, printed characters may be formed on a piece of
paper overlying the platen 11. Preferably, the printhead
carries a rotary ribbon shifter 37 for vertically
positioning the ribbon, e.g., to select different colored
stripes thereon~ ~
Traversing of the carriage 27 with the printhead
25 is performed by means of a servo motor 41 which is
coupled to the carriage 27 by means of intermediate
gearing 43 and an endless cogged belt 45 which passes over
pulleys 47 adjacent each of the ends of the guides 31.
Co-ordination of the operation of the several motors and
the dot matrix printhead is preferably controlled by a
dedicated microprocessor/firmware system as is conventional
in the present state of the art.
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l Paper following -the rotary platen ll is held
against the platen by a bai:L assembly 51, as well as
fixed rollers beneath and behind the platen (not shown).
The bail assembly 51 comprises three roller assemblies
53-55 carried on a rod 57 which is in turn mounted on a
pair of pivoted arms 58 and 59. The arms 58 and 59 are
each biased by an over-center spring arrangement 61 so
that the bail assembly is stably held in either of two
positions, an engage position in which the rollers are
pressed against the platen ll and a disengaged position
in which the rollers are swung back away from the platen,
e.g., for initially inserting a new sheet of paper.
In normal printing~ the printhead carriage 27
traverses most but not all of the travel distance accom-
i5 modated by the guides 31. In accordance with another
aspect of the invention, the carriage can be traversed,
by the motor 41 under microprocessor control, to an
extreme right hand position where a fixture 81 carried by
the carriage can engage a C-shaped cam member 83 which
is pivotally mounted on a bracket 84 supported on the
printer end frame l9o The cam 83 is pivotally mounted
on the bracket 8~ and carries a pin 85 which extends
through the end plate of the printer frame and engages a
slot 87 in one of the arms 59 which hold the bail rod 51.
As may be seen from Fig. 5, motion of the
carriage 27 towards its extreme right hand position will
cause a surface 87 on the fixture 81 to engage a mating
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1 surface 89 on the cam 83 there~y causing a coun-terclock-
wise rotation of the cam as seen from the top. As a
result of this motion, the pin 85 will cause the bail
assembly 51 to be pivotea back into a disengaged or
spaced-hack position from the platen 11. As indicated
previously, this position is stably held aue to the
operation of the over center spring 61.
On the other hand, when the carriage moves away
from its right hand extreme position, a second, pin-like,
contact surface 91 on the carriage fixture 81 will
engage an opposing operative surface 93 on the cam 83,
causing the cam to rotate clockwise as the carriage moves
to the left. This clockwise motion of the cam 83 causes
the pin 85 to pivot the bail arm structure 59 so that
the bail is snapped back into operative position, i.e.,
with the rollers 53-55 biased against the rotary platen
11. Again, this position is maintained by the over
center spring 61, even though the carriage moves further
to the le-ft, iOe., down the print line and completely out
of engagement with the cam 83~
In operation, the microprocessor control system
drives the carriage to the ex-treme right position
whenever it is appropriate for the operator to insert
a new piece of cut paper or to initiate feeding of the
leading edge of continuous form paper fed through the
tractors 61 and 63. When the leading edge of the paper
has been fed through the platen assembly and is above the
1 level oE the prin-thead and the bar 57, the printhead is
moved to the left causing the bail to move forwàrd in its
operative position wherein the rollers 53-55 engage and
hol~ the paper -to the platen. Thus, the paper, particu
larly if it comprises multi-part forms, is not loose over
the platen. As is understood by those skilled in the art,
this clamping facilitates clear and efficient printing,
particularly with a dot matrix impact printhead of the
type contemplated in the printer of the type disclosed
herein.
Referring now to Fig. 2, which shows the back
side of the printer mechanism, a pair of essentially
convention tractor assemblies 61 and 63 are slidably
mounted on a pair o-E guiae bars 65 and 67. The guide
bar 67 is essentially a stationary guide while the bar
65 is grooved and can be selectively driven in rotation
so as to couple a driving motion to the tractors in
conventional fashion. For this prupose, the guide bar
shaft 65 carries a spur gear 57. An idler gear 69 is
mounted on a carrier plate 71 which is pivoted around the
axis of the shaft 65~ i.e., it~ pivot is concentric
with the gear 67. Further, the gear 69 is meshed and
engages with the gear 67O
A manually operated lever 73 is pivotally
mounted on the end frame piece 19 and is biased towards
either of two stable positions by an overcenter spring
75. Lever 73 carries a lug 74 which rides in a slot 76 in
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1 plate 71 so that the plate can be moved or switched
between two stable positions. In the first of these
positions, the idler gear 69 is brought into engagement
with the gear 1~ which is part of the gear train driving
the platen 11. In this positionl the tractors 61 and 63
are thus driven in synchronism with the platen 11, the
various gear ratios being selected so that the paper speed
is -the same past the tractors and past the platen. In the
second position, the gear 69 is moved out of contact with
the gear 14 so that the tractors 61 and 63 are free of
the platen driving system~ This arrangement is illust-
rated in greater detail in Fig. 3. If desired, a sole
noid might operate the lever or an electrically operated
clutch might be employed.
In addition to moving the gear 69 out of
engagement with the drive train gear 1~, operation of
the lever 73 also causes a tang 77 on the place 71 to
actuate a microswitch 79. Microswitch 79 signals the
lever setting to the microprocessor control sys-tem-
which coordinates -the operation of the overall printer
system.
In view of the foregoing, it may be seen that
several objects of the present invention are achieved
and other advantageous results have been attained.
As various changes could be made in the above
constructions without departing from the scope of the
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1 invention, it should be understood that all matter con-
tained in the above description or shown in the accom-
panying drawings shall be interpreted as illustrative .
and not in a limiting sense.
