Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-11-13
2003-05-20
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S042000
Reexamination Certificate
active
06565187
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid ejecting head discharging a liquid from discharge port and a liquid ejecting apparatus mounting the liquid ejecting head.
2. Description of the Related Art
A liquid ejecting (ink jet) apparatus is of the so-called non-impact recording type, and has features of permitting recording of information at a high speed and on various recording media, and of being almost free from noise upon recording. On account of these features, the liquid ejecting apparatus is widely adopted as a recording apparatus in printers, wordprocessors, facsimile machines, copying machines and the like.
The liquid ejecting apparatus is based on steps of discharging fine liquid drops from small discharge ports arranged on a liquid ejecting head and depositing these drops onto a recording medium, thereby accomplishing recording. Discharge energy generating elements using a piezo-element or an electro-thermal conversion element are known. Such a liquid ejecting apparatus generally comprises a liquid ejecting head having a nozzle for forming liquid drops, and a liquid feed system feeding the liquid to the liquid ejecting head. For example, in a liquid ejecting head using an electro-thermal conversion element, heat energy is imparted to a liquid by providing the electro-thermal conversion element in a nozzle and applying electric pulses giving a discharge signal thereto, and a foaming pressure occurring upon foaming (boiling) of the liquid caused by a phase change of the liquid is used for discharging liquid drops.
Liquid ejecting heads using electro-thermal conversion as described above are classified into a type in which the liquid is discharged in parallel with an element board having electro-thermal conversion elements arranged thereon (edge shooter), and a type in which the liquid is discharged perpendicularly to the element board having electro-thermal conversion elements arranged thereon (side shooter). A concrete configuration of the liquid ejecting head will now be described by citing the side shooter as an example with reference to
FIGS. 15 and 16
.
FIG. 15
is a schematic perspective view of a liquid ejecting head of a conventional side shooter; and
FIG. 16
is a sectional view of the same liquid ejecting head cut along a direction (line Y—Y) perpendicular to the discharge port arranging direction.
In
FIGS. 15 and 16
, a plurality of discharge ports
202
for discharging a liquid are pierced on the surface side near the center of an element board
201
, and electro-thermal conversion elements (called also heating elements or heaters, and hereinafter simply referred to as heating elements)
203
corresponding to the individual discharge ports
202
, for heating the liquid are formed on the element board
201
.
Electric wiring of the heating elements
203
is connected to a transistor circuit for driving the heating elements
203
. The transistor circuit is built in the element board, or mounted by mounting a separate element having a built-in transistor circuit. In an element board having a relatively small number of heating elements, it is the usual practice to build a transistor circuit in the element board. In an element board having a relatively large number of heating elements for the purpose of increasing the printing width, the configuration having the transistor circuit built in the element board leads to a considerable decrease in yield of the element board. The method of mounting the separate element having the transistor circuit built therein onto the element board is more advantageous in yield.
FIGS. 15 and 16
illustrate a conventional case where separate driving elements (drivers IC)
205
having built-in transistor circuit for driving the heating elements
203
are mounted on the element board
201
.
The driving element
205
having the transistor circuit for driving the heating element
203
is mounted on the element board
201
by the COB (chip on board) connecting method using an anisotropic conductive film or a soldered bump, and electrically connected to the electric wiring from the heating element
203
. A logic circuit for driving the transistor is mounted on the driving element
205
, in addition to the transistor circuit. The logic circuit is connected to a flexible film (flexible circuit board)
206
via the element board
201
, and a signal for driving the logic circuit is provided via the flexible film
206
. The flexible film
206
is connected by the COB connecting method based on an anisotropic conductive film or the like to a circuit board
207
comprising a composite material of the element board
201
and a glass epoxy or the like. The circuit board
207
is fixed to a side of a supporting member
212
and electrically connected to an area outside of the head. The flexible film
206
is bent along the side surface of the supporting member
212
from an end of the element board
201
.
The electric connecting portions of the driving element
205
and the flexible film
206
are covered and sealed by a sealing agent
214
(
FIG. 16
) excellent in sealing and ion shielding abilities such as an epoxy resin, a fluororesin, or a silicone resin to avoid corrosion of electrodes or substrate metals caused by deposition on the electrodes of liquid drops scattering from the discharge port or liquid rebounding from the recording medium.
As shown in
FIG. 16
, a slit
204
for receiving the liquid fed from the back is formed by anisotropic etching or the like on the element board
201
. Common liquid chamber
210
communicating with a slit
204
formed in the element board
201
are formed on a holding member
211
and the supporting member
212
of the element board. A liquid feed port
213
for feeding the liquid to the common liquid chamber
210
is formed in the supporting member
212
. The liquid feed port
213
communicates with a liquid feed tank not shown. A liquid feed channel is formed by laminating the element board
201
, the holding member
211
and the supporting member
212
as shown in FIG.
16
.
In the liquid ejecting apparatus, when mixture of bubbles or dust in the fine discharge port (nozzle)
202
of the liquid ejecting head occurs, or when evaporation of volatile matter in the liquid prevents discharge of the liquid, a discharge recovery operation is conducted, in which factors causing defective discharge are eliminated by refreshing the liquid. Available methods for such a discharge recovery operation include a method of providing a cap capable of covering the discharge port of the liquid ejecting head and a pump communicating with this cap and applying a suction force, and forcibly sucking out the liquid from the discharge port under the action of the suction force in a state in which the liquid ejecting head and the cap are kept in close contact; and a method of providing a mechanism applying a pressure on the liquid from the liquid feeding side of the liquid ejecting head, and forcibly extruding the liquid from the discharge port of the liquid ejecting head by applying the pressure from the liquid feeding side. In any of these methods, it is necessary to keep the liquid ejecting head and the cap in a perfectly enclosed state not permitting in-flow or out-flow of the liquid or air.
When the liquid ejecting head is in a standby state in which the liquid is not discharged, it is necessary to maintain the liquid ejecting head and the cap in close contact to prevent an increase in viscosity caused by evaporation of a liquid solvent or by solidification.
For this purpose, in the liquid ejecting head, it is necessary to provide an area suitable for obtaining and maintaining close contact with the cap. In a conventional liquid ejecting head, a flat surface for receiving the cap
217
(see
FIG. 16
) is provided between the row of discharge ports on the element board
201
and the driving element
205
.
SUMMARY OF THE INVENTION
However, in the conventional liquid ejecting head as described above, in which the flat area for receiving the cap
217
is provided on the el
Karita Seiichiro
Sueoka Manabu
Yamane Toru
Yasuda Junji
Barlow John
Brooke Michael S
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