Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-09-16
2002-09-17
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06450621
ABSTRACT:
This application is based on Japanese Patent Application No. 10-263547 (1998) filed Sep. 17, 1998, the content of which is incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device having an inkjet recording capability and a method of making such a device. The present invention also relates to an inkjet head to which an inkjet recording mode for producing an output of information including characters and images is applicable, a recording apparatus on which such a recording head can be fixed or detachably installed, and an information-processing system having such a recording apparatus as its output means. In particular, the present invention relates to an inkjet recording head of the side-shooter type that ejects a droplet of recording liquid perpendicularly on a surface thereof where a plurality of elements for generating ejection-energies to be used for ejecting ink is formed.
2. Description of the Related Art
Commonly, an inkjet recording apparatus comprises: a carriage on which a recording means (hereinafter, also referred to as an inkjet head) and an ink-supplying means (e.g., an ink tank) for supplying a recording liquid (e.g., ink) to the recording means are installed; a transfer means for transferring a recording medium (hereinafter, also referred to as recording paper) such as paper, fabric, plastic sheet, and OHP sheet; and a control means for controlling the motion of those components. The inkjet head adapted to eject ink droplets from a plurality of ejection ports thereof is serially scanned in the direction (i.e., in the main-scanning direction) at a right angle relative to the direction of transferring the recording medium (i.e., in the sub-scanning direction), and subsequently, the recording medium is intermittently transferred at a quantity of displacement thereof equal to the recording width of the recording medium while no recording operation is performed. The inkjet head has elements that cause pressures for ejecting ink as means for generating energies to eject ink. That is, the means are electro-thermal energy converters that cause membrane-boiling phenomena in ink.
In general, there are two types of inkjet heads, i.e., an edge-shooter type and a side-shooter type. The edge-shooter type inkjet head has a plurality of ink-ejecting orifices, which is formed on an end portion of ink passage. That is, each of the orifices is in the downstream part of ink flow with respect to heater portions provided for heating ink. Ink passes through a plurality of ink-supplying paths branched from an ink-reservoir portion, so that each of the heater portions is provided in the corresponding ink-supplying path. On the other hand, each of the ink-ejecting orifices of the side-shooter type inkjet head is formed so as to face to the corresponding heater portion. That is, the side-shooter type inkjet head is prepared by forming a through hole (hereinafter, also referred to as an ink-supplying opening) on a substrate on which ink-ejecting energy generating elements are formed. The through hole provides the ink from the backside (i.e., the ink-supplying tank is arranged on the backside), while the ink is ejected from an orifice formed on a place in the direction perpendicular to the ink-ejecting energy generating element. The reason for supplying ink from the backside of the substrate is to make the distance between the inkjet head and the recording medium short. If the ink is supplied from the side on which the ink-ejecting energy generating element is formed, the distance between the inkjet head and the recording medium can be increased because of the presence of the ink-supplying tank.
The ink-supplying opening is formed by the method of making semiconductor integrated circuits (i.e., the process of semiconductor photolithography) using a single crystal silicon substrate (hereinafter, referred to as a Si substrate). For example, the ink-supplying opening is formed as a through hole by performing an anisotropic etching from the back side of the Si substrate.
However, the process of forming the above ink-supplying opening has the following problems.
FIGS. 1A
to
1
D are schematic cross sectional views for explaining the process of forming the conventional ink-supplying opening and each of them corresponds to each of the steps in the process. The figures focus attention on oxygen precipitates
5
,
6
,
7
in a Si substrate and a plurality of ink-supplying openings
8
a,
8
b,
8
c.
As shown in the figures, the precipitates are indicated by different numerals because they are different in size and density. That is, the oxygen precipitate
5
shows the highest density and the smallest size. The oxygen precipitate
6
shows the medium density and the medium size. The oxygen precipitate
7
shows the lowest density and the smallest size. The process includes the steps of: (a) preparing a silicon (Si) substrate: (b) forming a semiconductor device for inkjet-drive on the surface of the substrate; (c) forming a pattern of ink-supplying opening on the back of the substrate; and (D) performing an anisotropic etching from the back of the substrate. As shown in
FIG. 1D
, however, defectives (oxygen precipitate) with nonuniform sizes and densities are generated as a result of variations in concentrations of Oi (interstitial oxygen atoms) in the Si substrates after the step of crystal-pulling and variations in nonuniform thermal applications during the formation of semiconductor device among wafers and in each of them. Consequently, the rate of anisotropic etching on the Si substrate is not constant because of the presence of the above defectives, resulting in variations in sizes of the completed ink-supplying openings formed by the Si anisotropic etching. Regarding the variations in sizes of the ink-supplying openings
8
a,
8
b,
8
c,
therefore, the difference between the maximum and minimum opening widths is in the range of 40 to 60 &mgr;m in one wafer and in the range of 100 to 150 &mgr;m among the wafers.
FIGS. 2A and 2B
are schematic plane views for explaining the conditions of ink-supplying openings formed by the above conventional method. The figures focus attention on one ink-supplying opening for purposes of simple illustration.
FIG. 2A
shows the condition of the surface of the Si substrate
1
, while
FIG. 2B
shows the condition of the back of the Si substrate
1
. In the ink-supplying opening
8
b,
an opening width of an opening portion
9
on the surface of the Si substrate
1
is different from an opening width of an opening portion
10
on the back of the Si substrate
1
. In
FIG. 2A
, furthermore, the shape of the opening portion
9
of the ink-supplying opening
8
b
prepared by performing an anisotropic etching on the back of the Si substrate
1
is different from the shape of an opening portion
11
having an ideal opening size to be calculated from a mask size.
Variations in the shape of opening portion
9
on the side of semiconductor device having an inkjet recording capability leads to variations of the distances between the ink-supplying orifices and the ejection-energy generating portions (not shown) and significantly effects on the characteristics of operating frequencies of the inkjet head.
However, it is impossible to get an appropriate size of the etching mask
3
for etching the back of the Si substrate to satisfy an appropriate opening width of ink-supplying opening in consideration of those variations. Consequently, as shown in
FIG. 1D
, there are different openings. The ink-supplying opening
8
b
with an appropriate opening width, the ink-supplying opening
8
a
with a less opening width, and the ink-supplying opening
8
c
with no opening width on the surface of the Si substrate.
Therefore, there are demands for technological breakthroughs in the process of forming an ink-supplying opening with the more precise distance between the ink-supplying opening and the ink-ejection energy generating element by forming an ink-supplying opening more precisely.
SUMMARY OF
Barlow John
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Stephens Juanita
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