Liquid discharge recording head and method for manufacturing...

Incremental printing of symbolic information – Ink jet – Ejector mechanism

Reexamination Certificate

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Reexamination Certificate

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06799831

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid discharge recording head (ink jet recording head) used in liquid discharge recording (ink jet recording) for discharging liquid such as ink toward a recording medium, and a method for manufacturing such a liquid discharge recording head.
2. Related Background Art
As one aspect of recording apparatus for forming an image (here, regardless of meanings, a character, a figure, a pattern and/or the like are referred to as “image”) on a recording medium such as a recording paper, there is a liquid discharge recording apparatus (ink jet recording apparatus) for discharging minute ink droplet(s) from minute discharge port(s).
Among the liquid discharge recording heads, there are a liquid discharge recording head of edge shooter type in which an ink droplet is discharged in parallel with a substrate on which energy generating elements are formed and a liquid discharge recording head of side shooter type in which an ink droplet is discharged in perpendicular to the substrate. For example, Japanese Patent Application Laid-open Nos. 4-10940 (1992), 4-10941 (1992) and 4-10942 (1992) disclose a liquid discharge recording head of side shooter type. In the liquid discharge recording heads disclosed in these documents, an ink droplet is discharged while communicating a bubble generated by heating the heat generating resistance body with the atmosphere. In such a liquid discharge recording head, reduction of a distance between the energy generating element and the orifice and small liquid droplet recording which were difficult to achieve in the liquid discharge recording head of side shooter type in the conventional manufacturing method (for example, disclosed in Japanese Patent Application Laid-open No. 62-234941 (1987) can easily be achieved, and, thus, recent request for highly fine recording can be satisfied.
Further, in recent years, a higher output speed of a printer has been requested. The reason is that high density ink droplets is requested as a processing speed of a computer has been enhanced and an ink droplet has been minimized in order to output a highly fine image. Further, in printers for handling a large size recording medium and printers connected to a network, the request for high speed becomes more noticeable. The high output speed of the printer can be achieved by increasing the number of ink droplets per unit time, i.e., ink discharging frequency and/or by increasing the number of ink discharge ports. Normally, the high output speed of the printer is achieved by increasing the both. However, when the number of ink discharge ports is increased, nozzle arrays are increased, which leads to increase the dimension of the liquid discharge recording head.
In such a liquid discharge recording head, as shown in
FIG. 22A
, an orifice plate
105
having a plurality of ink discharge ports
106
is joined to a substrate
102
. As shown in
FIG. 22B
, an ink supply port
107
is formed in the substrate
102
, and a plurality of energy generating elements (heat generating resistance bodies)
101
are disposed on a surface of the substrate
102
joined to the orifice plate
105
at positions corresponding to the ink discharge ports
106
. As shown in
FIG. 22C
, an ink flow path (liquid chamber)
108
extending from the ink supply port
107
and communicated with the ink discharge ports
106
above the heat generating resistance bodies
101
is formed between the substrate
102
and the orifice plate
105
. Accordingly, ink is supplied from the ink supply port
107
to the ink flow path
108
and is discharged from the ink discharge port
106
by pressure of a bubble generated by the action of the heat generating resistance body
101
. Incidentally, in the drawings, for simplicity's sake, the ink discharge ports and the heat generating resistance bodies are schematically shown only in part or plural fine discharge port arrays are shown in a straight manner.
In a method for manufacturing such a liquid discharge recording head, as shown in
FIGS. 23A
to
23
D, a soluble resin layer
103
is formed on the substrate
102
on which the ink discharging energy generating elements (heat generating resistance bodies)
101
were formed, and, then, a coat resin layer
105
which constitutes the orifice plate later is coated by spin coating or the like. Thereafter, the soluble resin layer
103
is dissolved and the ink supply port
107
is formed in the substrate
102
. As a result, the dissolved portion of the resin layer
103
becomes the ink flow path
108
communicated with the ink discharge ports
106
and the ink supply port
107
, and the heat generating resistance bodies
101
are disposed in a confronting relationship to the ink flow path
108
. However, in this method, as shown in FIG.
22
C and by the two dot and chain line in
FIG. 23
, it is difficult to form the coat resin layer in a flat shape. As shown in
FIGS. 23B
to
23
D, the coat resin layer
105
is formed along corner portions (stepped portions) of the soluble resin layer
103
, with the result that a thick portion and a thin portion is included in the orifice plate
105
(dispersion). When a liquid discharge recording head in which the thickness of the orifice plate
105
is uneven is used, the thin portion of the orifice plate
105
is subjected to concentrated stress, with the result that the orifice plate may be apt to be peeled from the substrate
102
, reliability may be worsened and a service life of the liquid discharge recording head may be shortened. Further, since the ink discharged amount is determined by a distance (gap) between the heat generating resistance body
101
for generating the ink discharge energy and the front surface of the orifice plate
101
, as shown in
FIGS. 23B
to
23
D, when the thickness of the orifice plate
105
is not uniform and the gaps between the orifice plate and the heat generating resistance bodies
101
are uneven, it is very difficult to stably effect the small liquid droplet recording which is an effective method for realizing the highly fine recording.
A method for solving such a problem is disclosed in Japanese Patent Application Laid-open Nos. 10-157150 (1998) and 11-138817 (1999). In the manufacturing method disclosed in such documents, for the purpose of the flattening of the orifice plate
105
, the soluble resin layer
103
is formed not only as the pattern of the ink flow path
108
but also around outer periphery thereof, and the coat resin layer
105
is formed by using the soluble resin layer
103
as foundation. This manufacturing method will be fully explained with reference to
FIGS. 24A
to
24
D. Incidentally, in the actual manufacturing, although a plurality of heads are usually manufactured simultaneously on a single substrate, for simplifying the explanation, here, the manufacture of the single head will be explained.
First of all, as shown in
FIG. 24A
, a soluble resin layer
103
is formed on a substrate
102
on which a predetermined number of heat generating resistance bodies (electrical/thermal converting elements)
101
as ink discharging energy generating elements were arranged at predetermined positions. In this case, the soluble resin layer
103
includes not only a pattern
103
a
constituting an ink flow path but also a pattern
103
b
constituting a foundation encircling outer periphery of the ink flow path. Incidentally, the soluble resin layer
103
is coated, for example, by laminating of dry film or spin coating of resist and then is patterned, for example, by exposure and development by using ultraviolet ray (deep-UV light).
More concretely, after polymethyl isopropenyl ketone (such as ODUR-1010 manufactured by TOKYO OUKA KOGYO Co., Ltd.) is coated by spin coating and then is dried, it is patterned exposure and development by using deep-UV light.
Then, as shown in
FIG. 24B
, a coat resin layer
105
is formed on the soluble resin layer
103
by spin coating or the like.
In this case, if there is no pattern
103
b
as the foundation, since t

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