Note: Descriptions are shown in the official language in which they were submitted.
10854Z6
1 The invention concerns a paper transport mechanism for the transport of single
as well as endless forms in printers.
With reference to German Gebrauchsmuster 7,333,837 it is known, in desk
calculators, to use a print roll for the transport of the paper to be printed.
This print roll is used on the one hand as a support for the print unit and on
the other hand as a friction drive. For the transport of paper webs with mar-
ginal perforations this desk calculator can be provided with transport means
fitted pin rolls. Such a pin roll can be advanced by uniform angular steps
with the aid of a step drive comprising a unidirectional stepper unit actuated
by a stroke element operated in steps and driving the print roll. These known
transport means for forms operate either solely with the print roll as a fric-
tion drive or in such a manner that the drive of the print roll simultaneously
drives the pin roll. When both parts are simultaneously driven, the inaccur-
acies inherent in mechanical drives lead to a pile-up of the paper web between
the two transport means, so that a clean print image is not obtainable. Thus,
there are so-called inaccurate line spacings. In addition, because of the mech-
anical drive, such an arrangement is not suitable to obtain the relatively high
paper feed speeds and the flexibility in the lengths of the paper feed necessary
in terminal printers.
Therefore, it is the object of the present invention to provide a paper
transport mechanism readily adaptable to different tasks, to be of a simple
design, to operate safely and reliably, and to be readily operated.
Briefly, the transport mechanism for single and endless forms is provided
with a print roll as a support and transport means, and also includes a pin
transport means designed as a plug-in unit. The print roll can be driven by
means of a stepper motor as well as a handwheel. A ratchet wheel carries one
coupling part and, by means of the handwheel, can be shifted, latched, and
coupled to the other coupling part on the free-running gear arrangement. In
the coupled state, the tractors and the roll are driven via the free-running
gear arrangement located on the shaft of the print roll. In an intermediate
position, without coupling, only the roll is driven by hand or motor, if there
are no tractors. In a further position the ratchet wheel and the print roll are
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1 latched, so that only the tractors are driven
The design and operation of the paper transport mechanism in accordance
with the invention is described in detail below by means of the example illu-
strated in the figures.
The figures show in detail:
Figure 1 is a perspective view of the essential parts of the paper trans-
port mechanism designed in accordance with the invention, and
Figure 2 is a sectional view taken along plane 2-2 in accordance with
Figure 1.
The perspective view of Figure 1 contains the parts which are more or less
essential to the function of the invention. Parts used for bearing purposes,
for example, have been omitted for clarity's sake and because they are clearly
obvious to those skilled in the art. A print roll 1, which is used as a sup-
port for a paper web 2 in the print position as well as for feed purposes, is
permanently mounted on a shaft 3. The shaft 3 is pivotably mounted in bearings
not shown. The paper web 2 can be wound at an angle of more than 90 around the
print roll 1 and, if it is an endless form with marginal perforations as in the
case of the example shown in Figure 1, is guided by transport means provided
with pins and made up of two tractors 4 and 5. These tractors are guided on
two shafts 6 and 7 (the square shaft 6 serving as a drive shaft), and are later-
ally shiftable on said shafts for adaptation to different widths of paper web 2.
The tractors 4 and 5 essentially consist of one belt each 8 or 9 provided with
teeth on the inside and guided around two toothed wheels 11 and 12 and 13 and
14, respectively. The outside of belts 8 and 9 is provided with pins 15 which
at a corresponding spacing engage the marginal perforations of the paper web 2,
thus advancing the latter when it is driven. The tractors can also be provided
with fold-back covers 16, by means of which the paper web is held on the pins
15 and the belts 8 and 9, respectively. On the driving square shaft 6 of the
two tractors 4 and 5 a drive gear 17 is arranged which by means of an intermediate
gear 18 is driven in direction T, the direction of transport of paper web 2.
The intermediate gear 18 meshes with a toothed wheel 19 of a gear arrangement
which is arranged to run freely on the shaft 3 of the print roll 1. The free-
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1 running toothed wheel 19 on shaft 3 can be directly driven by a stepper motor
20 with a drive gear 21 or, as shown in Figure 1, via a further toothed wheel
22 which engages the pinion 21 of the motor 20. During this, the two toothed
wheels 19 and 22 are rigidly connected to each other via a sleeve 23. The
toothed wheel 22 is provided with a first coupling part 24 comprising slits 25
which are engaged by noses 27 in a second coupling part 26, in order to non-
pivotably connect the two coupling parts.
The second coupling part 26 is arranged on a toothed ratchet wheel 28 on
the side of the first coupling part 24 of the toothed wheel 22. The ratchet
wheel 28 is non pivotably connected to a handwheel 30 via a sleeve 29. The
ratchet wheel 28 together with the sleeve 29 and the handwheel 30 is axially
shiftable on the shaft 3 of the roll 1. For axial shifting, the sleeve 29 is
provided on both sides with a slotted hole 31. On the shaft 3 a pin 32 is
arranged past which the sleeve 29 together with the handwheel 30 and the ratchetwheel 28 can be axially shifted on the shaft 3 of the print roll 1, the shift
path being limited by the length of the slotted hole 31. In the position shown
in Figure 1, in which the ratchet wheel 28 together with the handwheel 30 is on
the right-hand side on the extreme end of the shaft 3, the ratchet wheel 28 is
non-pivotably latched to a notch 33. During this, the two coupling parts 24
and 26 do not mesh.
Figure 2 shows a lateral sectional view taken along plane 2-2 of Figure 1.
It is shown quite clearly how the paper web 2 is wound at an angle of more than
90 around the print roll 1 and can be fed in the direction of arrow T by the
transport means with pins, as, for example, tractor 5. The print roll 1 serves
as a support for a print unit 34 which may be designed as a wire pin printer.
During this, the paper in the print position in print unit 34 rests reliably on
the print roll 1, so that a clean print image is ensured by the paper guide.
In order to improve the paper guide, paper brakes 35, consisting of leaf
springs, are provided which are bent to rest against the print roll 1. Also
provided are paper pressure rolls 36 which via arms 37 in the direction of arrow38 can be applied to the print roll 1 or kept lifted off the latter by actuatingmeans not shown in detail. If, for example, the paper is fed by the tractors 4
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10~5'~26
1 and 5, the paper pressure rolls 36 are best kept in the lifted off state, as
shown in Figure 2, because otherwise the braking effect would become too strong.The transport means consisting of the two tractors 4 and 5 as well as the
toothed wheels 17 and 18 and provided with pins are suitably designed as one
assembly and can be easily plugged into and arrested in the frame not shown in
the figures. The drive coupling, when plugging such transport means provided
with pins into the roll drive, is effected via the gear arrangement which in
the illustrated example consists of the toothed wheels 19 and 22 connected by
a fixed sleeve 23. As previously mentioned, it is also possible to provide a
single toothed wheel for this purposes, ratios and space permitting.
The paper transport means designed in accordance with the invention are
used for several purposes. Initially a case will be considered where an endlessform web with marginal perforations is to be inserted into the transport means
illustrated in the figures. For this purpose the handwheel 30 with the ratchetwheel 28 is shifted by the operator to the left, so that it is unlatched from the
notch 33 but not to the extent that the two coupling parts 24 and 26 mesh with
each other.
By means of the non-pivotable connection via the slotted hole 31 and the
pin 32 the handwheel 30 is non-pivotably connected to the shaft 3. As a result,the print roll 1 is turned upon turning the handwheel 30, without the two trac-
tors 4 and 5 being turned via the decoupled gear connection 21, 23, 22 as well
as the intermediate gear 18 and the drive gear 17, because the gear connection
consisting of the two toothed wheels 19 and 22 is mounted to run freely on shaft3. Thus, in this intermediate position of the ratchet wheel 28 it is possible
for the print roll 1, via the handwheel 30, to thread in the paper web, which isintroduced from behind, without simultaneously turning the transport means pro-
vided with pins. During this operation, the pressure rolls 36 are best lifted
off the print roll 1, so that the paper can be easily threaded in and inserted
by hand. After a sufficient quantity of paper has been advanced over the print
roll 1 serving as a friction drive, the marginally perforated paper web 2 can beaccurately positioned on the pins 15 with the covers 16 folded back.
To effect the drive via the pin carrying transport means after the paper web
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1 2 has been inserted, the handwheel 30 with the ratchet wheel 28 is axially
shifted to the left (cf. Figure 1) to such an extent that the noses 27 of the
coupling part 26 engage the slits 25 of the coupling part 24, thus establishing
a connection between the toothed wheel 22 and the print roll 1, since the con-
nection consisting of the slotted hole 31 and the pin 32 is non-pivotably linkedto the shaft 3 and thus to the print roll 1. Thus, it is possible, via the
handwheel 30, to continue turning the print roll 1 and the tractors 4 and 5
jointly. On the other hand, it is possible in this position of the handwheel
30 to jointly drive, via the stepper motor 20 and its drive gear 21 as well as
the toothed wheel 22, the sleeve 23? and the toothed wheel 19, the tractors 4
and 5 and, via the connection of the slotted hole 31 and the pin 32, the print
roll 1. Thus, in this position both the print roll 1 and the transport means 4
and 5 provided with pins rotate jointly.
For some applications it may be expedient to use the print roll 1 as a
paper brake if the marginally perforated paper web 2 is solely advanced by the
two tractors 4 and 5. For this purpose the handwheel 30 with the ratchet wheel
28 is positioned as shown in Figure 1, so that, as a result of notch 23 engaginga tooth gap of the ratchet wheel 28, the shaft 3 and the print roll 1 are latched
and thus inoperative. Via its drive gear 21 and the free-running gear arrange-
ment 19, 22, the intermediate gear 18, the drive gear 17, and the square drive
shaft 6, the stepper motor 20 is, however, capable of driving the two tractors
4 and 5.
If the two tractors 4 and 5 are not present in a particular unit, for
example, if the print roll 1 is used to print and feed single forms with or
without marginal perforations, then drive by means of stepper motor 20 via its
drive gear 21 is effected in such a manner that toothed wheel 22 transfers the
drive force to the shaft 3 of the print roll 1 via the coupled coupling parts
24 and 26, with the handwheel 30 being in the left-most position in accordance
with Figure 1, or in an intermediate position via the slotted hole 31 and the .
pin 32. In this case the paper pressure rolls 36 preferably rest against the
print roll 1, so that the latter serves as a friction drive on the one hand and
as a support for the print unit 34 on the other.
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1 The transport means with pins shown in the figures consist of two tractors
4 and 5. These tractors may be replaced by so-called pin roll transport means
comprising on their edges two pin rolls of a relatively great diameter for guid-
ing marginally perforated paper webs. It is also possible to replace the gear
arrangement consisting of the two toothed wheels 19 and 22 by a single toothed
wheel running freely on shaft 3 and meshing with the drive pinion 21 of the
stepper motor 20 by which it is driven. The stepper motor 20 is used in a
known manner to feed the paper web stepwise, as required during printing.
The paper transport mechanism designed in accordance with the invention can
be used in different ways in data and information recording systems, as previously
described. Because of their flexibility, for example, with regard to endless
webs with marginal perforations or single forms, whereby feeding is effected by
means of the print roll serving solely as a friction drive, the described trans-
port means are particularly suitable for so-called terminal printers. Thus, the
paper transport mechanism in accordance with the invention in very flexible with
regard to its applications, easy and convenient to handle for the operator, and
of a simple and practical design.
