Patent Application
20090309930
1. Field of the Invention
The present invention relates to an inkjet printhead substrate used in an inkjet print head that performs recording by discharging ink droplets from discharge ports and to a method for manufacturing the inkjet printhead substrate. The present invention also relates to an inkjet print head including such an inkjet printhead substrate and to an inkjet recording apparatus including such an inkjet print head.
2. Description of the Related Art
An example of the inkjet print head has an inkjet recording chip as shown in
A plurality of rows of heat generating elements (not shown) that apply discharging energy to ink are arranged on both sides of the through hole 62 in the surface of the inkjet printhead substrate 11.
In addition, a discharge-port plate 12 is provided on the inkjet printhead substrate 11. The discharge-port plate 12 has a plurality of discharge ports 13 facing the heat generating elements.
A plurality of electrode pads 14 electrically connected to the heat generating elements are arranged at both ends of the surface of the inkjet printhead substrate 11.
Referring to
The inkjet recording element unit 73 includes contact pads 74 used for connection to a recording apparatus. In
Then, as shown in
In such an inkjet print head, a problem due to ink leakage from the discharge ports sometimes occurs. Japanese Patent Laid-Open No. 7-60954 discloses a technique in which an ink-leakage detection sensor is provided on a flexible substrate.
However, the recording head is heated when driven and cooled when not driven. The heat causes the components constituting the inkjet print head to alternately undergo slight expansion and contraction.
In the electrically connected portions, because the linear expansion coefficients of the inkjet printhead substrate and the sealing resin are different, separation occasionally occurs at the interface between the inkjet printhead substrate and the sealing resin.
Furthermore, when such an inkjet print head is used for a long time in, for example, a high-temperature and high-humidity environment, the sealing resin is gradually degraded, sometimes resulting in separation occurring at the interface between the inkjet printhead substrate and the sealing resin.
As a result, ink sometimes penetrates into the electrically connected portions of the electrode pads provided on the inkjet printhead substrate and the electrode leads provided on the flexible film wiring substrate, resulting in malfunction such as print failure. Thus, there is a problem in that ink and sheets are wasted during continuous printing.
The present invention provides an inkjet printhead substrate that solves at least one of the above-described problems. For example, the detection sensitivity to ink penetration into the peripheral region of the electrode pads is increased to prevent malfunction such as print failure.
An inkjet printhead substrate in accordance with an aspect of the present invention includes: a heat generating element configured to generate energy for ejecting ink; an electric wire electrically connecting the heat generating element and an electrode lead provided on a flexible film wiring substrate; a protecting film configured to protect the electric wire; an electrode pad to which the electrode lead is connected, the electrode pad being formed by providing an opening in the protecting film at a position above the electric wire; a region to which a sealing resin configured to protect an electrically connected portion of the electrode pad and the electrode lead is to be applied; and an ink-detecting electrode composed of a metal wire and formed at the region to which the sealing resin is to be applied. The metal wire has a smaller width than an opening provided in the protecting film from which the metal wire is exposed.
The ink-detecting electrode is provided at the region to which the sealing resin is to be applied. The ink-detecting electrode is composed of the metal wire exposed from the protecting film. The metal wire has a smaller width than the opening provided in the protecting film from which the metal wire is exposed. This configuration solves the above-described problem.
According to the present invention, the detection sensitivity to ink penetration into the peripheral region of the electrode pads can be increased.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Herein, the term “recording” refers not only to formation of information having a meaning, such as letters and diagrams, but also broadly to formation of images, designs, and patterns (regardless of whether or not they have a meaning or are exposed so as to be visible) on recording media, and to processing of media.
Herein, the term “recording media” refers not only to paper, which is used in a typical recording apparatus, but also broadly to materials capable of receiving ink, for example, fabric, plastic films, metal plates, glass, ceramics, wood, and leather.
In addition, the term “ink” (sometimes referred to as “liquid”) should be construed in a broad sense, similarly to the definition of “recording”, and thus refers to liquid that is applied to recording media to form images, designs, and patterns, to process recording media, or to treat ink (for example, solidification or insolubilization of the coloring material in the ink applied to the recording media).
Embodiments of the present invention will be described below with reference to the drawings. Components having the same configuration as those described above with reference to
In
Electrode pads 14 electrically connected to the heat generating elements are provided at ends of the surface of the inkjet printhead substrate 11. A metal wire serving as an ink-detecting electrode 1 is provided near the electrode pads 14.
The ink-detecting electrode 1 is a metal wire having an upper layer not covered by a protecting film. In
Then, a protecting film 33 is formed on the Si substrate 31 so as to cover the electric wire 32 and the ink-detecting electrode 1. Finally, openings are formed in the protecting film 33 at positions above the electric wire 32 to form the electrode pads 14 and an opening is formed in the protecting film 33 at a position above the metal wire serving as the ink-detecting electrode 1 to expose the metal wire. Thus, the inkjet printhead substrate 11 is completed.
Thus, the metal wire serving as the ink-detecting electrode 1 and the electric wire 32 are formed in the same process.
It is desirable that the metal wire serving as the ink-detecting electrode 1 and the electric wire 32 be made of the same material. Examples of the material include aluminum, silicon-added aluminum, copper-added aluminum, and other materials containing aluminum. These materials are suitable for the ink-detecting electrode, as will be described below, because these materials are relatively easily corroded by ink.
It is desirable that the metal wire serving as the ink-detecting electrode 1 be narrow and thin so that the ink can quickly corrode and break the metal wire. The width of the wire can be appropriately selected from, for example, 1 μm to 10 μm, and the thickness of the wire can be appropriately selected from, for example, 50 nm to 500 nm, taking into consideration the wire resistance of the electric wires for the heat generating elements, according to the required specifications and process conditions.
The metal wire serving as the ink-detecting electrode 1 and the opening in the protecting film 33 will be described in more detail below.
In general, as shown in
On the other hand, as shown in
Therefore, the metal wire for detecting ink is completely exposed from the protecting film 33.
This structure enables the metal wire to easily corrode and break when touched by ink, and increases the detection sensitivity to ink penetration.
Gaps are formed between the ink-detecting electrode 1 and the protecting film 33. When ink leaks, the gaps retain the ink by the capillary force to enable the detection electrode to easily corrode and break. Thus, the detection accuracy increases.
Accordingly, the size of the opening for the metal wire serving as the ink-detecting electrode 1 and the size of the openings for typical electrode pads are determined on the basis of fundamentally different ideas.
This configuration enables the power to be supplied to the ink-detecting electrodes 1 with no additional electrode pads for supplying power, and therefore, the size of the inkjet printhead substrate does not need to be increased.
In this embodiment, the logic circuit 21 is an AND circuit which performs an AND operation and receives inputs from two metal wires. The number of metal wires is not limited to two, but may be three or four.
In a normal state, high-level signals are input to the logic circuit 21 because of electric potential supply from of the power sources. As a result, high-level signals are output. In contrast, when ink penetrates into the ink-detecting electrodes 1, the ink corrodes and breaks the ink-detecting electrodes 1 because the upper layers of the ink-detecting electrodes 1 are not covered by the protecting film 33.
This stops the electric potential supply from the power sources to the logic circuit 21, and pull-down resistors lower the electric potential to GND potential. Thus, low-level signals are input, and as a result, low-level signals are output.
This configuration enables detection of ink penetration into the peripheral region of the electrode pads.
There are various methods for transmitting a signal having detected ink penetration to the inkjet recording apparatus. The simplest method is to provide a dedicated output electrode pad.
As shown in
The inkjet recording element unit 73 includes the contact pads 74 used for connection to the recording apparatus. In
Then, as shown in
The inkjet recording apparatus using the inkjet print head 83 according to this embodiment is configured as shown in
Herein, the inkjet print head 83 mounted on the carriage 93 is of a type in which the recording head and the ink cartridge are integrated.
However, if the inkjet print head and the ink cartridge are separated, the ink cartridge is replaceable. Thus, the inkjet print head may be either fixed to the carriage or removably attached to the carriage.
An ink-detecting electrode according to another embodiment will be described with reference to
The upper layer 2 of the detection electrode may be made of the same material as the electric wire 32 according to the above-described embodiment. Examples of the material include aluminum, silicon-added aluminum, copper-added aluminum, and other materials containing aluminum. These materials are suitable for the ink-detecting electrode because these materials are relatively easily corroded by ink.
The upper layer 2 of the detection electrode may have a multilayer structure composed of, for example, a material containing aluminum and a material for improving adhesion, i.e., titanium or chromium. The lower layer 3 of the detection electrode may be made of the same material as the heat generating elements, and, for example, tantalum silicon nitride (TaSiN) or tantalum nitride (TaN) may be used.
By making the upper layer 2 of the detection electrode from the same material as the electric wire and the lower layer 3 from the same material as the heat generating elements, the sheet resistance of the upper layer 2 can be made lower than that of the lower layer 3. As a result, the upper layer 2 having a lower sheet resistance is more easily corroded by ink, which is desirable in that resistance variation during corrosion increases, and consequently, the detection sensitivity increases.
Referring to
First, as shown in
Second, as shown in
Third, as shown in
Finally, as shown in
Because TaSiN is used as the lower layer of the detection electrode and SiN is used as the protecting film, the lower layer and the protecting film contain the same composition. This allows the material of the lower layer of the detection electrode to be etched at a higher rate than the material of the upper layer during etching of the protecting film. Accordingly, the lower layer having a smaller width than the upper layer can be formed.
A method for transmitting a signal having detected ink penetration into the peripheral region of the electrode pads to the inkjet recording apparatus, according to another embodiment, will be described.
When the inkjet recording apparatus is provided with a connection-status output circuit for confirming a connection status of the electrically connected portions during mounting of the inkjet print head, by using the connection-status output circuit, no additional output electrode pads are required. Thus, the size of the inkjet printhead substrate does not need to be increased.
In this configuration, the output signal from the logic circuit is connected to and input to the input side of the connection-status output circuit. Thus, the output signal from the connection-status output circuit can be changed by the signal having detected ink penetration, whereby the signal can be transmitted to the inkjet recording apparatus.
Arrangement of the ink-detecting electrode according to another embodiment will be described with reference to
In this embodiment, as shown in
Electric wires for electrically connecting the heat generating elements to the external wire are formed into a multilayer interconnection structure with a first electric wire 51 and a second electric wire 53.
The first electric wire 51 is formed on the Si substrate 31, which serves as the base material of the inkjet printhead substrate 11, and an interlayer insulation film 52 is formed on the first electric wire 51. Then, the second electric wire 53 and the metal wire serving as the ink-detecting electrode 1 are simultaneously formed thereon by photolithography process.
The first electric wire 51 and the second electric wire 53 are electrically connected to each other through an opening in the interlayer insulation film 52.
The protecting film 33 is deposited on the Si substrate 31 so as to cover the second electric wire 53 and the ink-detecting electrode 1. Then, openings are formed in the protecting film 33 at positions above the second electric wire 53 to form the electrode pads 14 and an opening is formed in the protecting film 33 at a position above the metal wire serving as the ink-detecting electrode 1 to expose the metal wire. Thus, the inkjet printhead substrate 11 is completed.
In the above-described embodiments of the present invention, when ink penetrates into the electrode-pad sealing portions, the ink corrodes and breaks the ink-detecting electrode 1 composed of the metal wire that is not covered by the protecting film. Thus, ink penetration can be detected. By informing the inkjet recording apparatus of the ink penetration, supply of a print signal and power supply to the heat generating elements can be immediately stopped.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2008-156635 filed Jun. 16, 2008 and No. 2009-030896 filed Feb. 13, 2009, which are hereby incorporated by reference herein in their entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-156635 | Jun 2008 | JP | national |
| 2009-030896 | Feb 2009 | JP | national |
