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EP 1 674 278 B1 |
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EUROPEAN PATENT SPECIFICATION |
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Mention of the grant of the patent: |
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15.07.2009 Bulletin 2009/29 |
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Date of filing: 14.12.2005 |
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International Patent Classification (IPC):
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Printer with reciprocating printhead carriage
Drucker mit hin- und herbewegbarem Druckwagen
Imprimante avec un chariot oscillante pour une tête d'impression
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Designated Contracting States: |
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AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC NL PL PT RO SE
SI SK TR |
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Priority: |
22.12.2004 EP 04106831
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Date of publication of application: |
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28.06.2006 Bulletin 2006/26 |
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Proprietor: Océ-Technologies B.V. |
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5914 CC Venlo (NL) |
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Inventors: |
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- Nottelman, Frank J.H.
5951 AW, Belfeld (NL)
- Goeree, Barry B.
5914 WD, Venlo (NL)
- Zwiers, Henk-Jan
5911 CP, Venlo (NL)
- Van Dorp, Bas W.J.J.A.
5615 AD, Eindhoven (NL)
- Dircks, Luc G.T.
5809 BW Leunen (NL)
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Representative: Vanoppen, Ronny R.J. |
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Océ-Technologies B.V.
Corporate Patents
Postbus 101 5900 MA Venlo 5900 MA Venlo (NL) |
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References cited: :
EP-A- 0 810 546 EP-A- 1 393 921 US-B1- 6 264 303
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EP-A- 1 077 139 US-A- 6 010 206
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- PATENT ABSTRACTS OF JAPAN vol. 1998, no. 14, 31 December 1998 (1998-12-31) & JP 10
253318 A (BROTHER IND LTD), 25 September 1998 (1998-09-25)
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Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
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[0001] The Invention relates to a printer comprising: a frame, a bearing assembly mounted
to said frame, a platen rotatably supported in the bearing assembly for advancing
a sheet of a recording medium, a guide rail mounted to the frame and extending in
parallel with an axial direction of the platen, a ruler extending in parallel with
the guide rail, a carriage driven to reciprocate along the guide rail and carrying
a printhead, and a detector arranged to detect the position of the carriage relative
to the ruler.
[0002] A typical example of a printer of this type, as disclosed for example in
EP-A-1 393 921, is an ink Jet printer having a printhead or printheads adapted to expel droplets
of liquid ink onto the recording medium that is advanced over the platen. The timings
at which the nozzles of the printhead are energised must be accurately synchronised
with the movement of the carriage. To this end, the carriage is equipped with the
detector for reading markings on the ruler. In order to achieve a high print quality,
it is prerequisite that the position of the ruler relative to the recording medium
in the direction of the reciprocating movement of the carriage is stable over the
whole print process.
[0003] In a conventional printer, the ruler is fixed at the guide rail, and the frame has
a very stiff construction so that it will not be distorted by forces of inertia that
are created by the acceleration and deceleration of the carriage.
[0004] It is an object of the invention to provide a printer which has a simple construction
and nevertheless permits a high print quality, especially in highspeed printing.
[0005] According to the invention, this object is achieved by a printer of the type indicated
above, wherein, in said axial direction, the ruler is rigidly fixed at a location
of the bearing assembly independently of the guide rail.
[0006] Thus, the position of the ruler is directly coupled to the position of the bearing
assembly which itself defines the axial position of the platen and hence the position
of the sheet of the recording medium. When the frame becomes distorted, this will
induce a lateral displacement of both, the platen and the guide rail, but the displacement
of the guide rail will be different from that of the platen. However, since the ruler
is not coupled to the guide rail but to the bearing assembly for the platen, the lateral
displacement of the ruler will be the same as that of the platen, so that a stable
relation between the position of the ruler and the recording medium is assured. As
a result, the stiffness requirements for the frame may be less strict, which leads
to a cost and weight reduction, and/or the print quality is improved or, for a given
print quality, the carriage may be accelerated and decelerated more rapidly, so that
a higher throughput can be achieved.
[0007] Preferred embodiments of the invention are indicated in the dependent claims.
[0008] The bearing assembly typically is formed by two bearings that are fixed at respective
frame members at opposite ends of the platen. In one embodiment, both ends of the
ruler are rigidly held at a respective one of the two bearings. In another embodiment,
only one end of the ruler is held at one of the bearings, and the other end of the
ruler is elastically connected to the frame, so that the ruler is tensioned between
the two frame members. Then, the elastic suspension of the ruler permits the ruler
to follow the lateral displacements of the one bearing to which it is connected.
[0009] The rigid connection between the end of the ruler and the bearing may preferably
be achieved by means of a holding plate that is oriented in parallel with the axial
direction of the platen, so that it has a high stiffness in this axial direction.
The holding plate may be mounted to a bracket that is itself attached to the bearing
or to a frame member directly at the mounting position of the bearing.
[0010] If the platen and the ruler are arranged on opposite sides of the guide rail, the
mounting plate may form an extended arm which passes through a slot formed in the
guide rail. Preferred embodiments of the invention will now be described in conjunction
with the drawings, in which:
- Fig. 1
- is a front view of a printer according to the invention;
- Fig. 2
- is an enlarged cross-section along the line II-II in Fig. 1.
- Fig. 3
- is a schematic front view of a printer according to a modified embodiment;
- Fig. 4
- is a schematic front view analogous to Fig. 3, illustrating a distorted condition
of a frame; and
- Fig. 5
- is a schematic view analogous to Fig. 4, for a printer according to a comparison example.
[0011] The printer shown in figure 1 comprises a frame 10 which is composed of a lower frame
12 formed by two uprights 14 and two cross-bars 16, and an upper frame that is formed
by two plate-like frame members 18 projecting upwardly from the cross-bars 16.
[0012] A bearing assembly is formed by two bearings 20 which rotatably support a platen
22 between the two frame members 18.
[0013] A sheet support plate 24 is horizontally supported on the two frame members 18 and
serves to support a sheet of a recording medium (not shown in Fig. 1) which is advanced
in X-direction (normal to the plane of the drawing in Fig. 1) by means of the platen
22. A worm-type drive mechanism 26 for the platen 22 is arranged near one of the bearings
20 (on the left side in Fig. 1).
[0014] A guide rail 28 rests on the top ends of the frame members 18 and extends in parallel
with the axial direction Y of the platen 22. A carriage 30 is guided on the guide
rail 28 and is driven to move back and forth along the guide rail by means of a belt
drive mechanism 32. The carriage 30 has a portion extending over the sheet support
plate 24, and a printhead 34 is mounted on the bottom side of this carriage portion
so as to face the sheet that is advanced over the sheet support plate 24. The printhead
34 may for example be a hot melt ink jet printhead.
[0015] A ruler 36 extends above and in parallel with the guide rail 28 and has markings
that can be read by a detector 38 mounted on the carriage 30. On the basis of the
markings read by the detector 38, an electronic control system of the printer determines
the timings at which the print units or nozzles of the printhead 34 are energised
while the carriage 30 moves across the recording medium.
[0016] As can best be seen on the right side in Fig. 1, a bracket 40 is rigidly mounted
on each of the bearings 20, more precisely, on the stationary part of the bearing,
and a holding plate 42 oriented in the Y-Z-plane is ridigly secured to the bracket
40. Each holding plate 42 forms an arm 44 which extends obliquely upwardly and outwardly
through a slot formed in the guide rail 28. The ruler 36 is, with its opposite ends,
rigidly held between the top ends of the arms 44.
[0017] On the left side in Fig. 1, the bracket 40 also accommodates the drive mechanism
26, and the holding plate 42 straddles a worm gear 46 of the drive mechanism.
[0018] As is shown in Fig. 2, the guide rail 28 is formed by a profile member which supports
two cylindrical rods 48 on which the carriage 30 is supported and guided with roller
bearings. The slot for the arm 44 is indicated as 50. The inclined position of the
arms 44, as shown in Fig. 1, has the advantage that the ruler 36 can be held under
a certain tension and at the same time permits the carriage 30 to travel over the
full width of the sheet support plate.
[0019] The main advantage of the mounting structure for the ruler 36 as described above
will now be explained in conjunction with Figs. 3 and 4 which, however, show a slightly
modified embodiment example.
[0020] As is symbolically shown in Fig. 3, only one end (left) of the ruler 36 is directly
connected to one of the bearings 20 by means of the arm 44, whereas the other end
of the ruler is elastically connected to a frame member 52 which projects from the
guide rail 28. The elastic suspension of that end of the ruler 36 is symbolised by
a spring 54.
[0021] The spring 54 will hold the ruler 36 under a certain tension, but nevertheless, as
in the first embodiment, the position of the ruler in Y-direction will be determined
by the position of the bearing 20 and will thus be locked to the Y-position of the
platen 22 and the sheet 56 advanced thereby.
[0022] When the carriage 30 moves back and forth along the guide rail 28, the drive mechanism
for the carriage (not shown in Fig. 3) and the guide rail 28 will be subject to considerable
forces of inertia, especially when large format prints, such as A0, shall be made
with a high throughput, so that the acceleration and deceleration rates of the carriage
are high. These forces tend to distort the frame 10, as has exaggeratedly been shown
in Fig. 4. As a result of this distortion, the guide rail 28 is offset in Y-direction
relative to the sheet 56 on the platen 22. However, since the ruler 36 is rigidly
held by the arm 44, the markings on the ruler 36 will exactly be kept in registry
with the sheet 56 on the platen 52. As a result, the distortion of the frame 10 will
have no influence on the print position on the sheet 56, as is indicated by arrows
in Figs. 3 and 4. The relative movement between the ruler 36 and the guide rail 28
is absorbed by the spring 54 in this embodiment.
[0023] For comparison, Fig. 5 illustrates the conventional case that the ruler 36 is rigidly
supported at the guide rail 28. Then, the distortion of the frame 10 would lead to
a displacement of the ruler markings and hence of the actual print position Pa in
Y-direction relative to the intended target print position Pt, and the print quality
would be deteriorated. The present invention successfully solves this problem.
1. A printer comprising:
- a frame (10),
- a bearing assembly (20) mounted to said frame,
- a platen (22) rotatably supported in the bearing assembly (20) for advancing a sheet
(56) of a recording medium,
- a guide rail (28) mounted to the frame (10) and extending in parallel with an axial
direction (Y) of the platen (22),
- a ruler (36) extending in parallel with the guide rail (28) and being fixed, rigidly
in said axial direction (Y), at a location of the bearing assembly (20),
- a carriage (30) driven to reciprocate along the guide rail (28) and carrying a printhead
(34), and
- a detector (38) arranged to detect the position of the carriage relative to the
ruler,
characterized in that, in said axial direction (Y), the ruler (36) is rigidly fixed at said location of
the bearing assembly (20) independently of the guide rail (28).
2. The printer according to claim 1, wherein the bearing assembly comprises two bearings
(20), one at each end of the platen (22), and both ends of the ruler (36) are rigidly
connected to a respective one of these bearings (20).
3. The printer according to claim 1, wherein one point on the ruler (36) is rigidly connected
to a single bearing (20) of the platen (22), and at least one other point on the ruler
(36) is elastically connected to a part (52) of the frame or the guide rail (28).
4. The printer according to any of the preceding claims, comprising a holding plate (42)
oriented in a plane (Y-Z) in parallel with the axial direction (Y) of the platen (22)
and connecting an end portion of the ruler (36) to the bearing (20) for the platen
(22).
5. The printer according to claim 4, wherein the holding plate (42) forms an arm (44)
which extends obliquely outwardly from the bearing (20) to the end portion of the
ruler (36).
6. The printer according to claim 4 or 5, wherein the ruler (36) and the platen (22)
are arranged on opposite sides of the guide rail (28) and the holding plate (42) forms
an arm (44) which passes through a slot (50) formed in the guide rail (28).
7. The printer according to any of the claims 4 to 6, wherein the holding plate (42)
is fixed to a bracket (40) that is fixed on the bearing (20) and/or at a frame part
(18) directly at the mounting position of the bearing (20).
8. The printer according to any of the preceding claims, wherein the printer is an ink
Jet printer.
1. Drucker mit:
- einem Gestell (10),
- einer an dem Gestell montierten Lageranordnung (20),
- einer Walze (22), die drehbar in der Lageranordnung (20) gehalten ist, um einen
Bogen (56) eines Aufzeichnungsmediums zu transportieren,
- einer an dem Gestell (10) montierten Führungsschiene, die parallel zu einer axialen
Richtung (Y) der Walze (22) verläuft,
- einem parallel zu der Führungsschiene (28) verlaufenden Lineal (36), das in der
axialen Richtung (Y) starr an einem Punkt der Lageranordnung (20) befestigt ist,
- einem Wagen (30), der zu einer hin- und hergehenden Bewegung entlang der Führungsschiene
(28) angetrieben ist und einen Druckkopf (34) trägt, und
- einem Detektor (38), der dazu ausgebildet ist, die Position des Wagens relativ zu
dem Lineal zu detektieren,
dadurch gekennzeichnet, daß das Lineal (36) in der genannten axialen Richtung (Y) unabhängig von der Führungsschiene
(28) starr an dem genannten Punkt der Lageranordnung (20) befestigt ist.
2. Drucker nach Anspruch 1, bei dem die Lageranordnung zwei Lager (20) aufweist, eines
an jedem Ende der Walze (22), und beide Enden des Lineals (36) starr mit je einem
dieser Lager verbunden ist.
3. Drucker nach Anspruch 1, bei dem ein Punkt an dem Lineal (36) starr mit einem einzelnen
Lager (20) der Walze (22) verbunden ist und wenigstens ein anderer Punkt an dem Lineal
(36) elastisch mit einem Teil (52) des Gestells oder der Führungsschiene (28) verbunden
ist.
4. Drucker nach einem der vorstehenden Ansprüche, mit einer Halteplatte (42), die in
einer Ebene (Y-Z) parallel zu der axialen Richtung (Y) der Walze orientiert ist und
einen Endbereich des Lineals (36) mit dem Lager (20) für die Walze (22) verbindet.
5. Drucker nach Anspruch 4, bei dem die Halteplatte (42) einen Arm (44) bildet, der sich
von dem Lager (20) aus schräg auswärts zu dem Endbereich des Lineals (36) erstreckt.
6. Drucker nach Anspruch 4 oder 5, bei dem das Lineal (36) und die Walze (22) auf entgegengesetzten
Seiten der Führungsschiene (28) angeordnet sind und die Halteplatte (42) einen Arm
(44) bildet, der durch einen in der Führungsschiene (28) gebildeten Schlitz (50) hindurchgeht.
7. Drucker nach einem der Ansprüche 4 bis 6, bei dem die Halteplatte (42) an einer Konsole
(40) befestigt ist, die an dem Lager (20) und/oder einem Teil (18) des Gestells direkt
an der Montageposition des Lagers (20) befestigt ist.
8. Drucker nach einem der vorstehenden Ansprüche, welcher Drucker ein Tintenstrahldrucker
ist.
1. Imprimante comprenant :
- un cadre (10),
- un ensemble palier (20) fixé sur ledit cadre,
- un plateau (22) supporté en rotation dans l'ensemble palier (20) destiné à faire
avancer une feuille (56) d'un support d'enregistrement,
- un rail de guidage (28) fixé sur le cadre (10) et s'étendant parallèlement à une
direction axiale (Y) du plateau (22),
- une règle (36) s'étendant parallèlement au rail de guidage (28), ladite règle étant
fixée, de façon rigide dans ladite direction axiale (Y), à un emplacement de l'ensemble
palier (20),
- un chariot (30) entraîné pour effectuer un mouvement de va-et-vient le long du rail
de guidage (28) et portant une tête d'impression (34), et
- un détecteur (38) configuré pour détecter la position du chariot par rapport à la
règle,
caractérisé en ce que, dans ladite direction axiale (Y), la règle (36) est fixée de façon rigide à ledit
emplacement de l'ensemble palier (20), indépendamment du rail de guidage (28).
2. Imprimante selon la revendication 1, dans laquelle l'ensemble palier comprend deux
paliers (20), un palier situé à chaque extrémité du plateau (22) et les deux extrémités
de la règle (36) étant reliées de façon rigide à un palier respectif sélectionné parmi
ces paliers (20).
3. Imprimante selon la revendication 1, dans laquelle un point sur la règle (36) est
relié de façon rigide à un palier unique (20) du plateau (22), et au moins un autre
point sur la règle (36) est relié de manière élastique à une partie (52) du cadre
ou du rail de guidage (28).
4. Imprimante selon l'une quelconque des revendications précédentes comprenant une plaque
de maintien (42) orientée dans un plan (Y-Z) parallèle à la direction axiale (Y) du
plateau (22) et reliant une partie terminale de la règle (36) au palier (20) pour
le plateau (22).
5. Imprimante selon la revendication 4, dans laquelle la plaque de maintien (42) forme
un bras (44) qui part en oblique vers l'extérieur du palier (20) jusqu'à la partie
terminale de la règle (36).
6. Imprimante selon la revendication 4 ou la revendication 5, dans laquelle la règle
(36) et le plateau (22) sont disposés sur les côtés opposés du rail de guidage (28)
et la plaque de maintien (42) forme un bras (44) qui traverse une fente (50) formée
dans le rail de guidage (28).
7. Imprimante selon l'une quelconque des revendications 4 à 6, dans laquelle la plaque
de maintien (42) est fixée à un support (40) fixé sur le palier (20) et/ou au niveau
d'une partie de cadre (18), directement sur la position de montage du palier (20).
8. Imprimante selon l'une quelconque des revendications précédentes, dans laquelle l'imprimante
est une imprimante à jet d'encre.
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only.
It does not form part of the European patent document. Even though great care has
been taken in compiling the references, errors or omissions cannot be excluded and
the EPO disclaims all liability in this regard.
Patent documents cited in the description