Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-05-21
2002-07-02
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S065000
Reexamination Certificate
active
06412918
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority benefit of Taiwan application serial no. 90105378, filed on Mar. 8, 2001.
BACKGROUND OF THE INVENTION
1 Field of the Invention
The invention relates to a print head used in a printer. More particularly, the present invention relates to an inkjet print head for a printer.
2 Description of the Related Art
With reference to U.S. Pat. Nos. 4,490,728, 4,809,428, 4,596,994, 4,723,129, 4,774,530, and 4,863,560, a conventional inkjet print head principally comprises: a capillary tube, an orifice plate, and a resistor. The resistor rapidly heats under a voltage pulse, which has a pulse width of a number of micro-seconds. The heating of the resistor is properly controlled such that the temperature of the ink is taken to a vapor nucleation point. The vapor bubble generated, under proper control, then causes ejection of a droplet of ink. With the conventional thermal inkjet technology as described above, a frequency of several kHz can be attained. Traditionally, conventional inkjet print heads typically comprise two types as described hereafter.
Referring to
FIG. 1
, a construction diagram schematically shows a conventional side-shooting inkjet print head. The conventional side-shooting inkjet print head comprises a thermal barrier layer
22
, a thermal resistor layer
24
, a conductive layer
26
, and an insulating layer
28
, sequentially formed on a substrate
10
. Through an adequate patterning processes, a plurality of resistors
20
are formed on the substrate
10
. A plurality of ink channels
32
, respectively comprising the resistors
20
therein, are formed in an isolation layer arranged above the insulating layer
28
, the ink channels being covered by a nozzle plate
40
. When a resistor
24
rapidly heats, a vapor bubble
50
is generated. The rapid expansion of the vapor bubble
50
causes ejection of a droplet of ink
52
. As shown in
FIG. 1
, the droplet of ink is ejected from the side of the inkjet print head, along the ink channel.
Referring to
FIG. 2
, a construction diagram schematically shows an up-shooting inkjet print head. The up-shooting inkjet print head of
FIG. 2
differs from that described above in
FIG. 1
in that the up-shooting inkjet print head has a plurality of orifices
42
in the nozzle plate
40
that respectively face the resistors
20
. When a resistor
20
heats the ink in the ink channel
32
, the vapor bubble
50
that is generated causes the ejection of the droplet of ink
52
from the orifice
42
facing the resistor
20
.
Both foregoing conventional inkjet print head structures are fabricated according to conventional methods as follows. The thermal barrier layer
22
is usually a silicon dioxide (SiO2) layer formed on the substrate
10
, which is usually a silicon (Si) substrate, through various method known in the art. Then, the thermal resistor layer
24
and the conductive layer
26
are deposited by typical sputtering. The resistors
20
are formed by photolithography and etching processes applied to the thermal resistor layer
24
and conductive layer
26
. The insulating layer
28
is then formed on the resistors
20
to prevent any electrochemical reaction between the resistors and the ink. The ink channels
32
are conventionally formed by specific laser drilling, sand blasting, or ultrasonic milling of a dry film arranged on substrate
10
. Finally, the inkjet print head structure is completed by aligning and bonding the nozzle plate
40
over the substrate
10
, covering the ink channels
32
.
The conventional inkjet print head, such as the above-described, has at least the following drawbacks. Specific machining processes and aligning-bonding are necessary to fabricate the nozzle plate, which substantially increases the fabrication cost, and does not allow for an all-batch process. Besides, the ink channel is formed through using machining processes that can generate residual material and deteriorates the efficiency of the inkjet print head.
An inkjet print head structure that, at least, can overcome the above drawbacks is thus needed.
SUMMARY OF THE INVENTION
A major aspect of the present invention is to provide a back-shooting inkjet print head that can allow for an all-batch process and a low cost of materials.
To attain the foregoing and other objects, the back-shooting inkjet print head, according to an embodiment of the present invention, comprises: a first substrate having a plurality of thermal resistors formed on a back surface thereof, and a plurality of orifices formed through the first substrate and respectively located proximate to the resistors; an isolation layer having a plurality of ink channels formed therein, wherein the isolation layer is arranged onto the back surface of the first substrate such that the region of each ink channel covers the region of one of the resistors and one of the orifices therein; and a second substrate having an ink supply window formed therethrough, wherein the second substrate is arranged on the isolation layer covering the ink channels, such that the ink supply window, connected to the ink channels, is located at one side of the resistors while the orifices of the first substrate are located at the other side of the resistors facing the second substrate.
To attain the foregoing and other objects, the back-shooting inkjet print head, according to another embodiment of the present invention, comprises: a first substrate having a plurality of thermal resistors formed on a back surface thereof, and a plurality of orifices formed through the first substrate and respectively located proximate to the resistors; and a second substrate having a plurality of ink channels formed on a front surface thereof and an ink supply window, connected to the ink channels, formed on a back surface thereof, wherein the second substrate, by its front surface, is arranged on the back surface of the first substrate, thereby covering the ink channels, such that the ink supply window is located at one side of the resistors while the orifices of the first substrate are located at the other side of the resistors facing the ink channels of the second substrate.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.
REFERENCES:
patent: 5016024 (1991-05-01), Lam et al.
patent: 5305018 (1994-04-01), Schantz et al.
Chang Charles C.
Chen Chia-Tai
Chen Chun-Jung
Hu Je-Ping
Mao Ching-Yi
Barlow John
Industrial Technology Research Institute
J.C. Patents
Stephens Juanita
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