Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2000-11-29
2002-01-01
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S068000
Reexamination Certificate
active
06334668
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an ink jet recording apparatus such as an ink jet printer or an ink jet plotter. More particularly, the present invention relates to the structure of a recording head in an ink jet recording apparatus.
BACKGROUND ART
Hitherto, in an ink jet recording apparatus such as an ink jet printer or an ink jet plotter, as shown in
FIG. 12
, in a drive signal generating circuit
8
formed in a apparatus main unit
2
, a drive signal COM generated by a waveform generating circuit
80
is amplified by a current amplification circuit
89
using push-pull-connected transistors, etc., for example, then is output to a recording head
10
mounted on a carriage. The recording head
10
is provided with a plurality of pressure generating elements
17
for jetting ink drops from nozzle openings by pressurizing ink in pressure generating chambers and a head drive circuit
18
for selecting which of the plurality of pressure generating elements
17
to drive based on recording data, and the drive signal COM is applied to the pressure generating element
17
selected by the head drive circuit
18
. As a result, the selected pressure generating element
17
pressurizes ink in the corresponding pressure generating chamber for jetting ink as an ink drop from the nozzle opening.
Here, the apparatus main unit
2
and the recording head
10
are connected by a flexible wiring board
100
having a length sufficient for the carriage to move, and the drive signal generating circuit
8
formed in the apparatus main unit
2
outputs a signal to the recording head
10
via the flexible wiring board
100
.
FIGS.
13
(A) and (B) show an example of a schematic structure of the recording head
10
in the conventional art. As shown in FIGS.
13
(A) and (B), the recording head
10
has a flow passage unit
230
, which comprises a nozzle plate
233
provided with a plurality of nozzle openings
231
as nozzle rows
232
, a flow passage formation board
237
comprising pressure generating chambers
234
communicating with the nozzle openings
231
and reservoirs
236
for supplying ink to the pressure generating chambers
234
through ink supply ports
235
, and an elastic plate
240
for abutting the tip of each piezoelectric vibrator
239
in a vertical vibration mode of piezoelectric vibration units
238
corresponding to the pressure generating elements
17
previously described with reference to
FIG. 12
for expanding or shrinking the pressure generating chamber
234
, the nozzle plate
233
, the flow passage formation board
237
, and the elastic plate
240
being stacked in one piece. The flow passage unit
230
is connected to a holder
241
formed by injection molding, etc., of a polymeric material and each piezoelectric vibration unit
238
is connected to a flexible cable
242
for communicating an external drive signal, then they are housed in a housing chamber
243
, the abutment faces (not shown) against the holders
241
are fixed with an adhesive, and a frame
244
also serving as a shield material is inserted into the nozzle plate
233
, forming the recording head
10
. The holder
241
is provided with an ink lead passage
245
communicating with an external ink tank (not shown) and the tip is connected to an ink introduction port
246
of the flow passage unit
230
for supplying ink from the ink tank to the flow passage unit
230
.
Each piezoelectric vibrator
239
in the vertical vibration mode forming a part of the piezoelectric vibration unit
238
is formed by stacking an electrode as one pole and an electrode as an opposite pole like a sandwich via a piezoelectric material, exposing one electrode to the tip side and the opposite electrode to the rear end side, and connecting to a segment electrode and a common electrode on each end face with piezoelectric constant d
31
, for example, although not shown, and is fixed to a fix board
247
matching the arrangement pitch of the pressure generating chamber
234
as a part of the piezoelectric vibration unit
238
.
The segment electrode and common electrode (not shown) of each piezoelectric vibrator
239
of the piezoelectric vibration unit
238
are connected to a conductive pattern for drive signal transmission of the flexible cable
242
via a solder layer. With the flexible cable
242
, a window
248
is formed in an area facing the fix board
247
, a semiconductor IC (integrated circuit)
249
provided with the head drive circuit
18
(see
FIG. 12
) for converting a print signal into a drive signal for driving each piezoelectric vibrator
239
is installed in the window, and the print signal is transmitted to the semiconductor IC (integrated circuit)
249
according to conductive pattern from the external drive signal generating circuit
8
(see
FIG. 12
) and the head drive signal is supplied to each piezoelectric vibrator
239
.
Thus, a plurality of pressure generating elements
17
(piezoelectric vibration units
238
) and head drive circuits
18
(semiconductor ICs
249
) are formed on the recording head
10
and mainly the transistors of the head drive circuits
18
(semiconductor ICs
249
) generate heat and therefore hitherto, a heat radiation measure has been taken for the recording head
10
.
That is, for the semiconductor IC (integrated circuit)
249
mounted on the flexible cable
242
, the area exposed from the window
248
is fixed to the fix board
247
with an adhesive via a thermal-conductivity fluid layer (for example, silicon grease, etc.,) not shown or is fixed with an adhesive having high thermal conductivity to the fix board
247
. The fix board
247
functions as a heat radiation member and is made of a material having high thermal conductivity such as metal or alumina. As shown in FIG.
13
(A), the fix board
247
is placed close to the ink lead passage
245
, whereby ink flowing through the ink lead passage
245
absorbs heat generated on the semiconductor IC
249
via the fix board
247
.
At the printing time, upon reception of input of a print signal via the flexible cable
242
from the external drive signal generating circuit
8
(see FIG.
12
), the semiconductor IC (integrated circuit)
249
generates a drive signal for driving each piezoelectric vibrator
239
and supplies the drive signal to each piezoelectric vibrator
239
. Thus, mainly the transistors in the head drive circuit
18
generate heat and the heat has thermal conduction relationship with the semiconductor IC (integrated circuit)
249
forming the head drive circuit
18
and is absorbed by the heat sink action of the fix board
247
having a large heat capacity and is radiated through the fix board
247
, so that the semiconductor IC (integrated circuit)
249
can be prevented from leading to thermal runaway or damage.
In the conventional art example described above, the recording head
10
is provided with the head drive circuit
18
. However, if the drive signal COM is output from the apparatus main unit
2
to the recording head
10
with the long flexible wiring board
100
, there is a problem of distorting the waveform of the drive signal COM because of parasitic inductance, etc., of the flexible wiring board
100
. For the recording head
10
, characteristics vary from one head to another, thus previous inspection is executed for ranking for matching with the drive signal COM, but the characteristics of the semiconductor IC
249
forming the drive signal generating circuit
8
also vary from one product to another, thus the drive signal COM output from the drive signal generating circuit
8
and the recording head
10
do not match in some cases.
In the conventional art example described above, as shown in FIGS.
13
(A) and (B), the adjacent nozzle rows
232
and
232
each formed with a plurality of nozzle openings
231
are formed comparatively close to each other in the nozzle plate
233
, thus it is feared that to jet an ink drop from a predetermined nozzle opening
231
in one nozzle row
232
, vibration excited by the corresponding piezoelectric vibration unit
238
may affect the other n
Barlow John
Seiko Epson Corporation
Stephens Juanita
Sughrue & Mion, PLLC
LandOfFree
Ink-jet recording apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ink-jet recording apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ink-jet recording apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2843989