This invention relates, in general, to print media feed apparatus
for hard copy printing devices capable of operating with printing media in continuous
band or sheet form and, more particularly, to large format ink jet printers, plotters
and the like with the ability to, interchangeably, handle a continuous media in
roll form and/or cut sheets.
An ink jet printer mechanism is a non-impact printing device which
forms characters and other images ejecting ink droplets, in a controllable manner,
from a print head. The ink jet mechanisms can be used in different devices, such
as printers, plotters, facsimile machines, copiers and the like. For the sake of
convenience reference shall hereinafter be made solely to large format ink jet
printers or plotters, to illustrate the concepts of the present invention.
The printhead of a machine of the kind mentioned ejects ink through
multiple nozzles as minuscule droplets, which "fly" over a short space and strike
a printing media. Different nozzles are used for different colours. Ink jet printers
usually print within a range of 180 to 2400 or more dots per inch. The ink thus
deposited on the media is immediately dried after being deposited to form the
desired printed images.
There are several types of ink jet printheads, for example, thermal
print heads and piezoelectric ones. By way of example, in a thermal ink jet printhead,
the ink droplets are ejected from individual nozzles by localized heating. Each
of the nozzles has a small heating element. An electric current is made to pass
through the element to heat it. This causes a tiny volume of ink to be heated by
the heating element and vaporized instantaneously. On vaporization the ink is ejected
through the nozzle. An exciter circuit is connected to individual heating elements
to supply energy impulses and, in this way, to deposit in a controlled way droplets
proceeding from associated individual nozzles onto the media. These exciter circuits
respond to character generators or other imaging circuits to activate selected
nozzles of the printhead to form the desired images on the media.
The ink nozzles customarily form part of an ink cartridge, disposable
or otherwise, and the printhead of a printer of the kind to which the invention
refers can have cartridges mounted for different ink colours, for example, cyan,
magenta, yellow and black. These are arranged in the carriage in such a way that
their nozzle sections are to be found very close to the surface of the support
platen of the media, but separated therefrom, for the purpose of allowing the passage
of said media between them. The carriage moves the printhead back and forth through
the printing zone in one direction, called the scan direction, the location of
the carriage in the printing zone being constantly controlled thanks to codifying
means which control an actuating motor, for example a stepping motor.
In machines of this type there is generally used, as media, a band
of paper of large width, for example D and E size, arranged in rolls of up to 90
m. in length. A 90 m. roll of E size paper can weigh almost 8 kg., so precautions
should be taken at the time of handling it.
Such handling is even more difficult if we consider that the face
of the media band on which the printing is performed is the external face and that
a large part of the media used in a machine of the kind to which the invention
refers have a coated surface which is sensitive to contact with the operator's
hands, such that the operator should as much as possible avoid touching said printing
surface during operation while, at the same time, keeping it clean and away from
objects that could harm or scratch the media surface.
Moreover; for certain printing tasks the operator may have to utilize
media in the form of large cut sheets, for example in A, B, C, D and E formats,
as well as in formats utilized in Architecture. Such pre-cut sheets can easily
spoil during handling, especially the larger sized ones. Care should be taken
when removing the media from the packet and during its insertion and adjustment
in the printer and, furthermore, care should be taken to touch the media only at
the edges, to avoid harming or soiling the area on which the printing has to take
Once the printing task concludes, the machine automatically cuts the
media (this does not occur in the case of printing on individual sheets) and the
media, in one or the other case, is allowed to drop on to the output tray, with
the possibility of the ink still not having dried completely with the resulting
risks this entails, i.e., that the printed work may be spoilt during initial handling
of the media.
In the prior art printing machines of different types are already
known (impact or ink jet, for example) which are capable of printing both on continuous
media and on cut sheets. A known machine of this type makes use of a "parking"
facility of the continuous paper while operating with cut sheets fed manually.
For example, from U.S. patent 5544966 a printer is known which, provided
with at least one tractor for continuous paper, allows the use of cut sheets to
print while the continuous paper is "parked" outside the printing area. This machine
achieves this interchangeable feeding by the provision of, at least, two different
pathways for paper input (continuous and cut sheets), a third pathway being foreseeable
for the input of continuous paper, likewise with the intervention of a tractor
(the one cited or another additional one) for paper.
In the first place the printer to which said document of the prior
art refers, is of small format and provided with tractors for the input of paper,
which can be fed into it in continuous band, folded zig-zag, with the usual perforations
in the margins or in the form of loose sheets, of small format.
In the second place, in said printer of the prior art is necessary
to change the turning direction of the main roller to take the continuous medium
towards a parking position, beyond the printing area and out of contact with said
main roller prior to being able to feed cut sheets.
Large-format printers are also known, to allow parking of a print
medium supplied starting from a roll and feeding in, in its place, a cut sheet
to perform a printing operation on it. These prior art printers have two superimposed
openings for input of the printing medium: one for the supply starting from a roll
and another for the supply as cut sheet. However, the said two superimposed openings
give way to a single advance path of the printer medium.
In machines of this type, when a user wishes to perform a printing
task on a cut sheet in a printer loaded with continuous medium, the printer has
to be requested, in the first place and by pressing a control panel button, to
withdraw the continuous medium from the printing area, making it recede separating
it from the main feeder roller and parking it, by a deviator which completely withdraws
it from the main advance roller. In the second place, the user has to manually
insert the medium in cut sheet form into the suitable opening, operation of which
is bothersome, since the manipulation of said cut sheet is difficult, owing to
its extreme width and, in particular, because of the close arrangement of said
two input openings (which are, moreover, hidden from the operator's view), the
most likely result being that the cut sheet will be fed into the wrong opening,
already occupied by the parked continuous medium. Finally, by means of another
push-button in the control panel, the user has to make the machine load the paper
in sheet form until the printing area.
Moreover, the input path of the means in sheet form is practically
mutual with that of feed in of the medium in cut sheet form and it is not possible
to supply said cut sheet simultaneously with removal of the medium fed in starting
from a roll.
According to the present invention there is provided, a printer for
printing on a first medium in the form of a continuous band or on a second medium
in the form of a sheet, in a print zone of the printer, the printer comprising
a movable cover giving access to the print zone for loading said second media,
a hold down system for holding said second media in position before and during
printing, a first sensor to detect opening of the cover linked to said hold down
system, storage means for storing said first medium, a feeder for moving said first
medium from the storage means to the print zone, wherein when the cover is opened
by a user of the printer the sensor activates the hold down system to accept said
second medium without any further action by said user.
Accordingly, one aim of embodiments of the present invention is to
provide a system for automatically changing the manner of feeding the printing
medium into a printer of the kind specified in the preamble of this specification,
between a manner of feeding in the medium in continuous band form and a manner
of feeding in the medium in cut sheet form with little intervention by the operator.
Embodiments of the invention provide two different input paths for
the medium: one for continuous medium and the other for medium in cut sheet form.
An operator can load continuous media into the machine starting from
a roll of the same and perform a printing task; afterwards he can load a cut sheet
without touching the media roll, perform another printing thereon and, after withdrawing
said cut sheet, he can once again operate with continuous media from the roll without
at any time touching the media.
To achieve this, in the advance path of the medium, there is provided
an auxiliary driver axis provided with, at least, one roller and arranged transversally
respecting the direction of advance of the medium, between a first input roller
intended to guide the medium and the main roller feeding in the same, whose auxiliary
driven axis can adopt a first position, in which it is to be found separated from
the path of the medium fed in starting from a roll, and a second position in which
it is applied with said medium, which is grasped between said at least one roller
of the auxiliary driven axis and by at least one roller assembled in a supporting
axis arranged to turn freely (whose geometrical axis is parallel to the geometrical
axis of said auxiliary tractoraxis) such that said continuous medium can be made
to advance and/or retrocede along said advance path.
In its turn, said auxiliary axis, when in said second position of
application with the continuous means, can adopt a first condition, in which it
turns freely, allowing advance of the medium removed from said input roll until
the medium achieves a "READY" position (prepared for printing) in the printing
area of the machine and while a printing operation is performed on it, and a second
condition, in which it is actuated in a first turning direction to make said continuous
medium recede, removing it from the printing area and from the main pulling roller
and taking it to a "STAND BY" or "parking" position, during which the printer can
be carrying out a printing operation on a cut sheet, or in which it is actuated
in the opposite direction to said first turning direction, to once again feed in
said continuous medium that was parked, until taking it to the ready to print position,
in said printing area.
In what follows a preferred embodiment of the invention will be described,
solely by way of example and making reference to the attached drawings, in which:
- Fig. 1 is a perspective view of a large format ink jet printer, which incorporates
- Fig. 2 is a perspective detailed view of the paper pulling mechanism and of
the area of the printing platen of a printer such as that of Fig. 1, on a first
- Fig. 3 is a view, similar to that of Fig. 2, on a second operative stage of
- Fig. 4 is a schematic end view, showing the feeder mechanism of a printer in
accordance with the invention, on a first operating stage corresponding to that
represented in Fig. 2.
- Fig. 5 is a view similar to that of Fig. 4, with parts withdrawn for greater
clarity, but on a second operating stage corresponding to that shown in Fig. 3;
- Figs. 6A-6D are schematic views in cross section, taken along the line A-B
of fig. 3, representing different phases of operation of the printer according
to the invention.
In fig. 1 an ink jet printer is illustrated generally, of the type
mentioned in the preamble of this specification, in this case a large format high
yield plotter, including a central platen 12 intended to support the medium during
printing and above which, there moves, the length of at least one guide bar, a
carriage carrying the printer head (hidden in this case by the cover 11), intended
to move, from one end to the other of the same, thus defining a printing area of
the machine. Occasionally the carriage, carrying the printer head, moves towards
one end of the machine; for example that designated with 14, in which a service
station is located, to carry out cleaning of the nozzles and/or priming of the
A feeder mechanism (of which the input guide roller 20 of this figure
forms part) is utilised to achieve advance of the medium along a first feeder path
through the machine, said feeder mechanism being comprised by a set of shafts
and rollers which shall be described hereinafter. This feeder mechanism allows,
in general, removal of the medium from the storage roll 16, causing it to pass
through the printer, above the platen 12, where the printing operation is performed,
and causing it to come out of the machine, after cutting it, to fall into a collector
Said roller 20, assembled rotatively at its ends on both sides of
the printer frame, can turn freely and facilitates input of the printing medium,
guiding it in its entry into the machine and at the same time eliminating friction
to which said medium would otherwise be subject and which could damage its surface
on which it has to be printed. By way of example, said roller 20 can have a longitudinally
slotted or striated surface to facilitate guiding the paper.
The printer 10 has a predefined printing area which coincides, at
least partially, with a part of the feeder path of the medium, such that this is
fed in through the printer area. One illustrative printer area is defined as that
within which each one of the multiple nozzles of the printer head can print the
entire width of the medium.
We shall make reference now to figs. 2 to 5 of the drawings, in which
the spatial relationship is shown, of the components of the system for feeding
the printing medium into the machine, there being represented in figs. 2 and 4
the printer with a swinging chassis 21 in a raised condition and, in figs. 3 and
5 in a lowered condition. In said figures there is indicated with 12 the central
platen intended to support said medium during the printing operation, representing,
with 34 and 35, respectively, the front and rear platens for supporting the medium
while coming out of the machine. With 20 the roller is indicated, intended to guide
the medium on entering the printer from its storage roll 16 (see fig. 1). Above
said roll 20 a swinging chassis 21 is provided, provided with flaps 22 to be moved
manually by the operator between two positions: one above (figs. 2 and 4) in which
it is to be found separated from said roller 20, and a lower one (figs. 3 and 5),
in which it is to be found close to said roller 20. This swinging movement of the
chassis 21 is achieved thanks to its pivoting assembly at 39 (See fig. 5) in one
and the other sides of the printer frame.
In said chassis 21 there is rotationally assembled an auxiliary axis
23 provided with a roller to pull the medium. Said axis 23 has a pinion 24 at one
of its ends, which pinion 24 is to be found in constant contact with the toothed
wheel 25. In the first position of said chassis 21, the said axis is separated
from a roller 36 (see fig. 4) assembled to turn freely in subchassis 37, while
in said second position of said chassis 21, said at least one roller assembled
in said axis 23 achieves being applied with said roller 36 to grasp between both
the printing means supplied starting from said storage roll 16.
The toothed wheel 25 has, in its inner face looking towards the printing
area, a toothed crown (not shown), intended to mesh, on being required to do so,
with a corresponding toothed crown (not represented) formed in the face opposite
another toothed wheel 25a, coaxial with it and permanently engaged to the main
roller 29. The selective coupling of said toothed wheel 25 with the toothed actuating
wheel 25a is achieved by movement of the former towards the latter on pushing the
lever 26 to said toothed wheel 25 every time the carriage carrying the printer
heads, under the control of the logic of the printer, reaches a determined end
position, outside the printing area and impacts against part 27 of said lever 26.
The central platen 12 has a slot 28 with a zig-zag design, in which
openings are provided (not illustrated) intended to allow the application of a
vacuum, generated under said platen, to the upper face of this, on which the printing
medium slides. The actuation of this vacuum is limited to the moment at which said
medium is fed in, in the form of cut sheet, as shall be explained hereinafter.
This platen 12 has ribs 40, equally spaced the length of the same and penetrating
into mouths provided for the purpose in the main feeder roller 29 of the printer.
The function of these ribs 40 shall be explained in more detail hereinafter, in
relation to figs. 6A-6D.
In said figures 2 and 3 there can also be seen the main feeder roller
29, actuated by means of a toothed wheel 30 meshed constantly with said toothed
wheel 25a. With said roller 29 a pressure roller 31 operates (see figs. 4 and 5)
for the purpose of grasping between both the printing medium and making it advance
or retrocede during operation of the machine.
With 32 various rollers to pull the medium are designated, assembled
in an axis provided, at one of its ends, with a pinion 33 in constant mesh with
said toothed wheel 25a. These rollers 32 collaborate, too, with moving the medium
in the printing area.
Finally, front and rear platens, 34 and 35, respectively, are provided,
intended to support and to guide the medium to facilitate its coming out of the
printing area and preventing said medium coming into contact with other mechanisms
or cables of the machine and being damaged.
Reference will be made now, in particular, to figs. 3 and 5, being
views similar to those of figs. 2 and 4, in which the same elements have been
designated with the same reference numbers. In the first of them, the front platen
34 has been removed from the printer, so that the position can be more clearly
seen, adopted by the chassis 21 when this is found in its lower swinging position,
to which it has been taken by the operator on the latter pressing on the flaps
22 downwards. In fig. 5 the toothed wheel 25 has been removed and the lever 26,
27 which moves it to couple with the toothed wheel 25a, so that the pivoting assembly,
in 39, of the brackets 38 constituting the sides of the chassis 21 in the printer
frame, can be seen more clearly.
The operation shall now be explained of the input system according
to the invention, making reference for the purpose to figs. 6A-6D in particular,
representing different operative phases of the machine.
Once the printer is connected, the user manually raises the chassis
21, pulling the flaps 22 upwards; to move it to its upper or open swinging position
(see figs. 1 and 2). Next, he removes from storage roll 16 of the medium a determined
length of the same and causes it to pass above the input roller 20 and above the
roller/s 36, along the path represented with lines in the form of dots and dashes
in fig. 6A, taking care the medium does not break or turn out damaged (for example,
creased). The printer, thanks to the existence of a paper detector indicated in
general manner with 50, advises the operator, for example by an acoustic signal,
that the existence of the printing medium has been detected. Then the operator
lowers the flaps 22 to bring the chassis 21 to its lower or closed swinging position,
the medium being grasped between the roller 70 assembled in said axis 23 of the
chassis 21 and the rollers 36. The medium is then made to advance towards the printing
area, in the direction of the arrows adjacent to T1-T1 and fig. 6A, around the
main roller 29, to the flexible fingers 60, forcing them to divert upwards. These
fingers 60 constitute the so-called valve for the medium and are to be found housed
in the same periphery slots provided in roller 29 in which there is likewise housed
the ribs 40 of the central platen 12. The medium thereafter passes above said central
platen 12, said rollers 32 and, finally, coming out above said front platen 34.
The path of the medium, in this condition, is indicated, as already stated, by
the line comprised by dots and dashes T1-T1 in fig. 6A,
On arriving at this point, the machine interrupts advance of the
medium, cutting it transverally to its direction of advance, the length of the entire
platen 12, by means of a cutting device of the kind already known in the art, and
remains in the stand by position for printing, alerting the operator of this by
the usual acoustic signal. In this condition of stand by to print, of the machine,
the continuous medium remains in the T1-T1 position of fig. 6B, with the printer
cover 11 in lowered position.
We shall now assume that the user decides to carry out a printing
operation on said continuous medium. This will be made to advance as the printer
head carries out said task, following the mentioned path T1-T1 (see the arrows
of Fig. 6a) thanks to the cooperation of the main roller 29 with the
roller 31, while the rollers 20, 36 and 70 turn freely. Once the printing task
ends, the machine detains advance of the medium, makes a new cut the whole width
of the printing area and the printing medium is left to fall on the collection
tray 18 (fig. 1), the continuous medium once again being left located in the printer
in the condition represented in fig. 6B with T1-T1
If, then, the user decides to carry out a printing task on a cut sheet,
he lifts the protecting cover 11 of the machine. Every time this step of lifting
said cover 11 is performed a sensor or switch (not shown) is activated, controlled
by it, causing the logic of the printer to order application to begin of a vacuum
to the lower part of the central platen 12, vacuum which acts on the upper part
of this thanks to the said perforations existing in said slot 28 of the platen.
The operator can then place in position in the platen 12 a cut sheet, drawing
assistance therefor from the slight retention which said vacuum exercises through
said platen 12 on said cut sheet. Next the operator lowers the cover 11 to its
closed position which activates the same switch and indicates to the printer that
the user may have loaded a cut sheet. The printer performs a detection step of
said cut sheet (presumed to be in the position designated with T2-T2) on the printing
platen 12 by a detector provided in the carriage bearing the printer heads which,
for the purpose, performs an exploration the width of said printing area.
If the user has not placed a single sheet on the platen 12, the printer
does not detect its presence and moves on to a stand by condition, the carriage
bearing the printing heads returning to its resting position and generation of
the said vacuum being interrupted. On the contrary, if the user has in fact placed
said cut sheet in the direction T2-T2, assisted by the action of the vacuum through
said platen 12 to achieve its correct positioning, the printer detects its presence
and proceeds to remove the continuous medium from the printing area and from the
main roller 29 (in the direction of the arrows adjacent to the path T1-T1 in fig.
6C) and, simultaneously, to take the cut sheet, pulling it in the direction of
the arrows of path T2-T2.
To carry out said change of printing medium, the said carriage bearing
the printer heads moves outside the printing area, towards the end of the machine
where the lever 27 is to be found, touching it and moving it such that the part
26 of said lever moves the toothed wheel 25 to couple it with the toothed wheel
25a, whereby the latter will transmit the actuation, through said toothed wheel
25 temporarily meshed with it and through the pinion 24, to the auxiliary axis
23, which will be made to turn in a first direction so that the roller 70, in cooperation
with the roller 36, withdraws the medium downwards, until stopping at the position
illustrated in fig. 6D with T1-T1. Simultaneously with this removal of the continuous
medium, the rollers 32, in cooperation with the vacuum applied on said cut sheet
through the platen 12, pull this in the direction of the arrows adjacent to the
path T2-T2 (fig. 6C).
On removing the continuous medium T1-T1 from below the flexible fingers
60 of the valve of the medium, these have once again adopted their non-diverted
position inside the slots of the roller 29, so that the medium in cut sheet form
T2-T2 continues to move towards the left in fig. 6C, passing above said fingers
60 and the rear platen 35, until reaching the position represented in fig. 6D,
following the necessary checks having been made as to position and alignment of
said cut sheet in the printing area and the corresponding cutting of its front
edge as perparation for a printing operation on it.
At this moment, with the continuous medium T1-T1 and the medium in
cut sheet form T2-T2 in the positions represented in fig. 6D, the printer has "parked"
the continuous medium T1-T1, holding it between the roller 70 and the roller 36,
the carriage bearing the heads ceasing to act on the lever 26, 27, said toothed
wheels 25, 25a hence uncoupling themselves and the actuation for the auxiliary
70 axis therefore being interrupted, the machine then beginning the printing task
on said cut sheet, once the cover 11 is lowered manually.
Once said printing task on the medium in cut sheet form ends, this
is ejected from the machine and the tray 18 and the carriage bearing heads moves
once again to act on the lever 26, 27 in order to transmit the actuation of the
toothed wheel 25a to the axis 23 and, therefore, to the roller 70, but now in a
second direction opposite to said first turning direction, such that the medium
in band form continues to be fed automatically to the printing position represented
with T1-T1 in fig. 6B. At this moment, on the existence of said continuous medium
being detected in this position, the carriage bearing the printer heads is returned
to its resting position, separating itself from said lever 26, 27, whereby said
toothed wheels 25, 25a uncouple and the actuation on the axis 23 and the roller
70 is interrupted, the printer once again remaining in the stand by condition on
the medium in band form, with the cover 11 in closed position.
As from this moment, the machine is to be found in the same starting
condition, i.e., with the continuous medium loaded in condition for printing on
it, the printer cover in lowered position and in stand by to print condition.
It can be seen, from the above, that the feeder mechanism in accordance
with embodiments of the invention offers a new solution to the problems that arise
at the time of, in printing machines, using a media fed continuously from a roll
of the same and, alternatively, a media in the form of cut sheets, on providing
a printer of the type mentioned, having two different paths for feeding the media.