The present invention relates to a printing apparatus for printing
on a print medium according to the preamble of claim 1.
Conventionally, some recording apparatuses have been known in which
a plurality of recording heads are arranged along a direction of conveying a recording
sheet or the like, and the image recording is performed on the recording sheet
by conveying the recording sheet to pass through a plurality of recording sites
by the plurality of recording heads.
In such recording apparatuses, after recording by a recording head
on the upstream side in the direction of conveying the recording sheet, and when
conveying the recording sheet to the next recording site by a recording head subsequently
located downstream, the rising of the recording sheet off a platen surface might
occur, so that the recording sheet was brought into a space within the recording
head out of the normal conveying path, because of, for example, rolling recording
sheet, oblique running of recording sheet, or the effect which the recording sheet
undergoes from the recording head in recording (pressure applied by the recording
head in case of a recording head of contact recording type, or deformation of the
recording sheet due to sticking of ink droplets in case of a recording head of
non-contact recording type). Therefore, there was a risk that the normal recording
at the recording site downstream might be hampered, or the conveyance stop might
occur due to jam of the recording sheet.
To prevent such unfavorable conveyance of the recording sheet, an
apparatus is known in which the recording sheet is adsorbed onto a platen by sucking
the air from the back side of the platen through fine apertures punched on the
platen supporting the recording sheet in a plurality of recording sites. Further,
an apparatus is known in which the recording sheet is adsorbed onto the conveying
surface of an endless conveying belt for conveying the recording sheet through
a plurality of recording sites by means of static electricity or weak adhesives.
However, such a recording apparatus may require a pump device for
suction, an electric apparatus for charging or discharging the endless conveying
belt or the recording sheet, or a device for applying adhesives to the endless
conveying belt, resulting in larger recording apparatus as such, or more complex
process, with higher costs. On the other hand, conventionally, there
was a label sheet of the type in which a number of labels were successively bonded,
easily releasably, on a lengthwise released paper called a separator as the recording
sheet, but this label sheet was commonly in the form of having labels bonded on
the separator, such labels made of thermal paper to effect thermal printing by
means of a thermal head. Further, this separator was mostly formed like a roll
and delivered to the recording apparatus.
The above-described technical problem was significantly serious,
considering that when using a label sheet as the recording sheet, there was a risk
that the label sheet might not be conveyed normally to the downstream recording
site, since the label sheet might rise up from a mount, due to the above-mentioned
phenomenon, though the released paper itself as the mount could be conveyed normally.
Furthermore, this problem is conceivably a very important subject,
in that when using a recording apparatus of ink jet system, as the recording system,
in which a fixed gap is held contactless between the recording head and the recording
sheet in recording, the label sheet may swell out to cause deformation like wrinkles
or decrease the adhesive power of adhesives, due to sticking of ink droplets produced
by the ink jet recording at a plurality of recording sites, resulting in abnormal
condition of conveying the recording sheet as previously described, whereby it
is expected that new problems may be possibly incurred, such as clogging of ink
discharge ports with paper scraps produced by contact of the recording sheet with
a member for guiding the recording sheet, false recording of image or clogging
of ink discharge ports caused by contact of the recording sheet with the ink jet
head disposed downstream, which was no problem in the case of the contact type
recording system such as a thermal system or a thermal transfer system.
A generic printing apparatus for printing on a print medium is known
from EP-A-0 376 354. According thereto, rotary members are arranged on a different
side of the conveyance path compared with the plurality of print heads because
the rotary members are provided directly below the print heads.
US-A-5 356 229 shows a printing apparatus having one single print
head and a flexure limiter as a rotary member. The flexure limiter is disposed
generally downstream from a print zone.
It is an object of the present invention to further develop a printing
apparatus according to the preamble of claim 1 such that a print medium can be
conveyed in well condition through a plurality of printing positions.
This object is achieved by a printing apparatus having the features
of the new claim 1.
Advantageous further developments are set out in the dependent claims.
The printing apparatus of the invention can make excellent image
prints by conveying a print medium in well condition through a plurality of printing
Furthermore the printing apparatus of the invention can convey a
print medium in well condition, while preventing a displacement beyond a predetermined
amount off a print medium conveyance path between printing positions, in conveying
the print medium through a plurality of printing positions.
Moreover, the printing apparatus of the invention can convey a print
medium with a recording sheet in well condition through a plurality of printing
positions, with the recording sheet held on a sheet substrate.
According to the present invention, a printing apparatus can make
excellent image prints by conveying a print medium in well condition through a
plurality of printing positions, with the recording sheet held on a sheet substrate.
According to the invention, a plurality of print heads are disposed
along a conveyance direction of said print medium, and rotary members are provided
over the print face of said print medium between print heads mutually, said rotary
members suppressing displacement from the print face of said print medium.
A printing apparatus in accordance to the invention is defined in
Fig. 1 is an external perspective view showing a label printer according
to an embodiment of the present invention.
Fig. 2 is a perspective view showing the label printer as shown in
Fig. 1, with its case cover removed.
Fig. 3 is a perspective view showing the label printer as shown in
Fig. 1, with its front cover opened.
Fig. 4 is a front view showing a mechanism of a print head station
(PHS) for the label printer as shown in Fig. 1.
Fig. 5 is a perspective view for illustrating a conveying mechanism
for the label printer as shown in Fig. 1.
Fig. 6 is a plan view of the conveying mechanism as shown in Fig.
Fig. 7 is a side view of the conveying mechanism as shown in Fig.
Fig. 8 is a front view of the conveying mechanism as shown in Fig.
The preferred embodiments of the present invention will be described
below in detail with reference to the drawings.
It is to be noted that the following embodiments use the print medium
in the form of roll paper where labels are successively arranged on a released
sheet, but may use other print media in various forms, kinds or materials in conformance
to the printer used. For example, the print medium may be a cut sheet, or may be
of film, cloth or others. Also, in this embodiment, an ink jet print head of full-line
type which can exhibit the most remarkable effect of the present invention is
used, but a serial type ink jet print head can be also used, or other recording
systems, e.g., a thermal head, may be used to obtain desired effects.
While this invention is described below with a label printer, it
is of course possible that the printer of the present invention may take various
forms in which the print medium is a scored continuous paper to be able to cut
away, a calling card, other cards, or the form of a ticket vending machine.
Fig. 1 is a perspective view showing the appearance of a label printer
according to an embodiment of the present invention.
The label printer of this embodiment uses a sheet in the form of
roll paper in which labels are successively arranged on a released paper, and can
be largely classified, in its arrangement or constitution, into three units, including
a roll paper supply unit 101, a print head unit 102, and an ink cartridge accommodating
unit 103. A cover 111 of roll paper supply unit 101 is detachably mounted, thereby
enabling a new roll paper to be set. The roll paper accommodated within the roll
paper supply unit 101, which is conveyed by a sheet conveying mechanism constructed
between the print head unit 102 and the ink cartridge accommodating unit 103, as
will be described later in connection with Fig. 2, is printed on each label by
a print head of print head unit 102, and then exhausted via an exhaust opening
114 out of the apparatus. It is to be noted that a device for releasing a label
from the released paper which is exhausted through the sheet exhaust opening 114,
or a device for winding the released paper to be exhausted together with bonded
labels, may be connected to the label printer of this embodiment.
The print head unit 102 is provided such that the whole head unit
can be opened or closed around a support shaft at a back end portion in the cartridge
accommodating unit 103, as will be described later in connection with Fig. 2,
thereby allowing maintenance of a print head of print head unit 102, or a sheet
conveying mechanism, or setting of the roll paper. At a front end portion of print
head unit 102, there are provided a lamp or a liquid crystal display for informing
various sorts of printer status, as well as an operation unit 112 equipped with
A front cover 113 of ink cartridge accommodating unit 103 can be
opened or closed around a rotational shaft at an end portion to the left in the
figure, thereby allowing mounting or dismounting of an ink cartridge by opening
this front cover 113 for the replacement of the ink cartridge.
Fig. 2 is a perspective view of the label printer as shown in Fig.
1, in which the cover 111 of roll paper supply unit 101 is removed and the print
head unit 102 is turned upward into open state, and Fig. 3 is a perspective view
showing the label printer in the state where the front cover 113 of ink cartridge
unit 103 is opened.
As shown in Fig. 2, a roll 126 around which the roll paper 124 accommodated
within the roll paper supply unit 101 is wound is placed on two drive rollers
301 (one not shown) installed on the bottom of the unit 101, in which the external
periphery of the roll 126 and the drive rollers are in contact owing to a pressure
produced by its dead weight of the roll paper. In this state, by the above drive
rollers 301 being rotated due to the motive power of a motor, not shown, the roll
paper 124 is subjected to separation at the outermost turn from its inner roll
paper and delivered therefrom. This supply of roll paper is performed, substantially
independently of the conveyance by the roll paper conveying mechanism 104 (its
details not shown) between the printer head unit 102 and the cartridge accommodating
unit 103. Accordingly, to regulate the conveyance between these two units, the
supply of roll paper is controlled to form a loop (slack, not shown in Fig. 2)
which serves as a buffer in the roll paper supply as above described. That is,
if a loop sensor (not shown) does not sense any loop in the conveyance by the
conveying mechanism 104, the roll paper supply is performed while forming a loop
by driving the above drive rollers.
A sheet guide 131 is slidably provided along a direction of the width
of a roll 126 to be accommodated. That is, in accommodating the roll paper, the
sheet guide 131 is slid beyond the width of roll paper 124 to place the roll 126
on the driving rollers, and then is slid up to the width of roll 126, so that
a part of sheet guide 131 can be abutted against a core 125 of roll 126. Thereby,
when the roll paper 124 is supplied, it is possible to regulate the roll paper
124, within a tolerance of minute deflection, from being swung widthwise upstream
of the driving rollers in its supply direction. It is to be noted that the sheet
guide 131 is provided with a stopper 316 for securing its slide position.
In the roll paper conveyance path, as obliquely feeding unit 128
is provided near an entrance into the conveyance path for the conveying mechanism
104. The obliquely feeding unit 128 has two obliquely feeding rollers (not shown)
contacting with the lower surface of roll paper 124, and obliquely feeding rolls
129, 130 contacting with the upper surface of roll paper 124 placed opposed to
those rollers. Two obliquely feeding rollers consist of a driving roller disposed
opposite an obliquely feeding roll 130, and driven by a driving force from the
conveying mechanism 104, and a driven roller disposed opposite an obliquely feeding
roll 129 and not driven by any driving force, each roller being mounted to be
rotated obliquely relative to the direction of conveying the roll paper (the rotational
shaft is inclined from a direction orthogonal to the conveyance direction). Also,
the obliquely feeding rolls 129, 130 are also mounted obliquely relative to the
conveyance direction, like the obliquely feeding rollers. With these obliquely
feeding rollers and obliquely feeding rolls 129, 130, the roll paper being conveyed
is subjected to a conveying force obliquely directed, which acts to press the roll
paper onto the predefined guide on the rear side in the figure. As a result, since
the roll paper 124 is subjected to a regulation force to perform the conveyance
in a fixed direction, it can be conveyed satisfactorily without fluctuations in
the conveyance direction.
The roll paper conveying mechanism 104 provided between the print
head unit 102 and the cartridge accommodating unit 103 is comprised of a plurality
of belts disposed under the roll paper 124 (or accordingly on the upper surface
of cartridge accommodating unit 103) and extending in the conveyance direction,
though they are omitted in Fig. 2, rollers for driving them, provided upstream
and downstream in the conveying direction, and spurs 141 (shown in Fig. 4) disposed
under the lower surface of print head unit 102, each spur getting a driving force
via a predetermined belt among the above-mentioned belts.
In Fig. 3, the ink cartridge accommodating unit 103 comprises four
cartridge accommodating chambers 140Y, 140M, 140C, 140Bk, corresponding to four
kinds of inks for use in the label printer in this embodiment, i.e., yellow (Y),
magenta (M), cyan (C) and black (Bk). Near an entrance of each cartridge accommodating
chamber, a shutter 142Y, 142M, 142C or 142Bk for substantially shuttering the
inside of this accommodating chamber is provided. Those shutters have the upper
portion supported rotatably, provided to protect the user from falsely putting
a hand into the accommodating chamber and touching an ink supply needle. When
inserting an ink cartridge, the cartridge itself forces a shutter to open to the
rear side of accommodating chamber to achieve the insertion.
Fig. 4 is a front view showing the constitution of a print head station
151 (hereinafter referred to as PHS) which is a main mechanism of the print head
PHS 151 has an ink jet head (hereinafter referred to as a head) 155Y,
155M, 155C, 155Bk which has discharge ports arranged over the entire width of label
in a width direction of roll paper to make prints on labels placed on the roll
label 124. This head is one having elements for generating thermal energy for
causing film boiling in the ink as the energy for use to discharge the ink from
the ink discharge ports. Also, PHS 151 has withdrawal means of the ink which is
discharged out of the ink discharge ports disposed on each head, a blade for wiping
and removing remaining ink on the discharge port formation face near the ink discharge
ports of head, and a recovery system unit 153 having a cap for preventing drying
around the ink discharge ports.
In PHS 151, there are provided a drive system unit for moving vertically
a head holder unit 152 for supporting each head from the print position onto the
roll paper 124, and moving the recovery system unit 153 horizontally along the
roll paper conveyance direction a predetermined amount, and a cool unit for cooling
Also, beneath the PHS 151, spurs 141 are provided on both sides of
each head, as above noted.
While in the above description, the label printer was largely classified
into three units, it is of course possible that each unit is not only provided
with elements or mechanisms as described. Other relevant elements to those as
described, or a control substrate, a driving motor, and an ink supply system,
are appropriately disposed, wherein well-known elements can be used, except for
each of elements or mechanisms as described below.
Next, the conveying mechanism 104 as above will be described in detail.
While in the following embodiment the print medium is conveyed by means of the
conveying belt 401, it will be appreciated that the print medium may be directly
conveyed on a flat platen (print medium supporting surface), instead of using the
conveying belt 401.
Fig. 5 is a perspective view showing the whole label printer including
the conveying mechanism 104, Fig. 6 is a plan view of the conveying mechanism 104,
Fig. 7 is a side view of the conveying mechanism 104, and Fig. 8 is a front view
of the conveying mechanism.
The conveying mechanism 104 comprises a plurality of conveying belts
401 forming the conveyance surface on the platen 400, a spur driving belt 402 which
is driven by the same driving source (omitted in the figure) as that for the plurality
of conveying belts 401, and forms the drive plane on the platen 400 outside the
roll paper 124 (as seen to the left and downward in Fig. 5) to be conveyed by the
conveying belts 401, a plurality of spurs 141 disposed in suspension a predetermined
height above the plurality of conveying belts 401, and pulleys 404 for sharing
the rotational shaft with the plurality of spurs 141, and transmitting a rotational
driving force to the spurs 403 by abutting with the spur driving belt 402.
The plurality of conveying belts 401 are stretched around the rotational
shafts 405 and 406 disposed downstream and upstream of the platen 400, respectively.
The provision of plural conveying belts 401 has the advantage that the use of a
wide and expensive conveying belt can be avoided, and the assembling operation
can be facilitated, compared to the wide conveying belt. It is needless to say
that the thickness of the plural conveying belts 401 is all equal.
At one end of the rotational shaft 405 (on the rear side in Fig.
5), a conveyance drive motor, not shown, is attached, this drive force being transmitted
to the rotational shaft 406 via the plural drive belts 401. Therefore, even with
the provision of plural conveying belts 401, there is no variation in the conveying
speed between conveying belts, so that the occurrence of any inconvenience, such
as oblique running of the roll paper 124 to be conveyed, can be prevented. The
other end of rotational shaft 405 is connected via a round belt 409 with a rotational
shaft 408 of a waste paper system for the roll paper 124, as shown in Figs. 6
and 7. Also, the other end of rotational shaft 406 is connected via a round unit
410 with the driving system of the obliquely running unit 128 as above. In either
case, the connection via the round belt has the effect of improving the unevenness
The spur driving belt 402 is stretched between the rotational shafts
405 and 406, like the conveying belts 401. In this embodiment, the spur driving
belt 402 is looped around the other end of each rotational shaft (on the fore
side in Fig. 5). This position corresponds to the outside of the roll paper 124
to be conveyed by the plurality of conveying belts 401. Accordingly, the spur
driving belt 402 is not directly involved in conveying the label sheet.
This spur driving belt 402 is abutted by pulleys 404 which share
the rotational shafts with the spurs 141. A driving force from the spur driving
belt 402 is transmitted via the pulleys 404 to the plurality of spurs 141.
These spurs 141 are provided on the lower portion of PHS 151, and
set in suspended state a predetermined height above the roll paper 124 to be conveyed,
when this PHS 151 is covered over the platen 400. Herein, the gap between the
surface of roll paper 124 and the spurs 141 is normally set to 0.14mm ± 0.05mm,
but is not particularly limited as far as it is in the range where the roll paper
is satisfactorily conveyed to the next print position.
The height of spurs 141 above the platen 400 is adjusted so that
the wall thickness of spur driving belt 402 is greater than that of the plurality
of conveying belts 401 in this embodiment. With this method, it is possible to
make the spurs 141 and the pulleys 404 of the same diameter, and render the peripheral
speed of both equal. Of course, the above-mentioned height may be adjusted in such
a way that the wall thickness of spur driving belt 402 is made equal to that of
conveying belts 401, and the size of spurs 401 is made different from that of pulleys
Also, the spurs 141 are disposed on the PHS 151 under the platen
400 and near a TOP sensor 411 disposed at a position upstream of the conveyance
path, as shown in Fig. 7. This TOP sensor 411 is to sense a TOF (Top of Form)
mark as a trigger for print start attached on the back side of roll paper 124.
When this roll paper 124 is rising up, the separation distance between the TOP
sensor 411 and the TOF mark may vary, resulting in less sensing accuracy, but owing
to the presence of spurs 141 near the TOF sensor 411, the variation of the above
separation distance can be suppressed to the minimum, thereby making it possible
to raise the sensing accuracy.
Further, the plurality of spurs 141 are each equipped with a cleaner
412 made of an absorbing material. This cleaner 412 abuts against the marginal
portion of spur 141 owing to its dead weight or an urging member such as a leaf
spring, thereby allowing removal of adhering matter such as ink discharged by
each ink jet head 155 onto the roll paper 124 constantly.
While in the above embodiment, the spur drive belt 402 was disposed
to the fore side as shown in Fig. 5, it will be appreciated that the spur drive
belt may be disposed to the rear side. When it is disposed to the rear side, the
width of roll paper 124 to be conveyed is not limitative, but a wider roll paper
124 can be also conveyed and printed, with the advantage of having a higher degree
of freedom for the applied sheet. In this case, pulleys 413 mounted at the end
portion opposite pulleys 404 take over a rotational driving force transmission
function to the spurs 141 which is a function of pulleys 404, while the pulleys
404 share a spacer function which is a function of the pulleys 413. For this purpose,
the pulleys 413 are of the same diameter as the spurs 141, and the pulleys 404
are needed to be replaced with those having a radius equal to the radius of spurs
141 plus the thickness of spur drive belt 402.
It should be noted that the ink jet recording apparatus as above
described may be used as an image output terminal for an information processing
equipment such as a computer, and additionally take the form of a copying machine
in combination with a reader, and further a facsimile apparatus having the transmission
and reception function.
As above described, according to this embodiment, by providing spurs
between a plurality of print heads, the print medium can be securely suppressed
from rising up, even if it rises up during the conveyance, so that the contact
between the discharge port face of print heads and the surface of print medium
can be prevented. If the print head is of the ink jet print system, it is possible
to make high quality prints on the print medium with the same method.
Also, by providing spurs suspended over the surface of the print
medium, they normally make no contact with the print medium surface being conveyed,
so that the production of paper powder from the print medium can be prevented,
and the increase in conveyance load of the print medium can be suppressed, and
further, when the print medium rises up, its rising part can be suppressed to
prevent contact with the print head firmly.
Further, by rotating the spurs at the same speed as the conveying
speed of print medium, even when the print medium rises up to make contact with
spurs, the spurs will not impose any load on the conveyance, whereby it is possible
to prevent oblique running of the print medium, and to perform the conveyance at
a constant speed.
Also, by driving the print medium via a plurality of conveying belts
to be driven by the same drive source, it is possible to prevent oblique running
of the print medium securely by eliminating the variations in the conveying speed
between the plurality of conveyance belts. Also, owing to the provision of the
plurality of conveyance belts, the use of a wider and expensive conveyance belt
can be avoided, and the cost can be reduced.
Further, by providing a spur drive belt to drive for rotation the
spurs outside the print medium being conveyed, and making the spurs contacting
with this spur drive belt and the pulleys sharing the rotational shaft with the
spurs the same diameter, the peripheral speed of pulleys and spurs can be made
equal to realize the conveyance at stable speed.