Patent Application
20070126809
1. Technical Field
The present disclosure relates to devices for depositing ink or other fluids or pastes onto media.
2. Description of the Related Art
Conventionally, ink cartridges have been widely used in devices using ink. An example of such a device is an ink jet printing device. The ink jet printing device typically includes an ink jet head or print head. The print head is driven to eject ink drops towards a recording medium such as a piece of paper to form images and characters thereon. Typically, the ink cartridge includes an ink reservoir, and the ink accommodated in the reservoir is supplied to the print head.
The ink that has been used in current ink jet systems can be high in cost, and thus can be unattractive for low cost applications like the marking of shipping labels. In addition, the time involved in allowing the ink to dry once it has been deposited onto the media slows down the process. To reduce the time involved with drying, fast evaporating solvents have been added with the ink, but the use of such solvents increases costs and adds to environmental burden. Alternatively, applying heat to the freshly applied ink can be costly due to the equipment used and the costs involved in operating the equipment. Also, increasing the rate at which conventional ink jet delivery systems deposit ink onto the media requires the use of elaborate electronic controls that make the process complex and increases the cost.
The present disclosure is directed to solving one or more of the above-described problems.
In an embodiment, an ink delivery device includes an ink reservoir, a reaction chamber, and a one-way valve that permits ink to flow from the reservoir to the reaction chamber when pressure in the reaction chamber equals or is lower than pressure in the reservoir. The valve prevents ink from flowing from the reservoir to the reaction chamber when pressure in the reaction chamber exceeds pressure in the reservoir. In an embodiment, the reservoir may include a pressure member, such as a magnetic weight, that applies pressure to the ink and causes the ink to escape from an outlet of the reservoir. Optionally, the one-way valve may include a first porous stop, a second porous stop, and a plug between the first and second porous stops. The plug may move between the first and second porous stops in response to the pressure changes in the reaction chamber.
In various embodiments, the ink may include a reactive compound, water, and pigment. The reactive compound may include an oxygen or nitrogen-containing compound, such as hydrogen peroxide, which forms a gas when exposed to a catalyst. In an embodiment, the reactive compound may be about ¼% by weight to about 15% by weight of the ink. In another embodiment, the reaction chamber may include at least one catalyst, such as catalase or peroxidases, which may react with the ink to form a gas.
A method of depositing a fluid on a medium may include directing the fluid onto a catalyst-containing surface, wherein the fluid reacts with the catalyst in the surface to form a gas, and the reacted fluid is expelled onto a medium. The fluid may be directed via gravitational pressure, by a pressure member applying pressure to the ink or by another method. In some embodiments, the catalyst-containing surface may comprise a wall or other interior portion of a reaction chamber. In such embodiments, the fluid may react with the catalyst in the reaction chamber to form a gas and increase pressure in the reaction chamber. The increase in pressure may cause the fluid to be expelled from the outlet of the reaction chamber and deposited on the medium. In some embodiments, the fluid may be ink that is expelled onto the medium at a rate of between about 500 deposits per second and about 1000 deposits per second. After the ink is expelled, additional ink may be delivered to the reaction chamber, optionally by the opening of a valve between an ink reservoir and the reaction chamber.
Before the present methods, systems and materials are described, it is to be understood that this disclosure is not limited to the particular methodologies, systems and materials described, as these may vary. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope.
It must also be noted that as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Unless defined otherwise herein, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art. All publications mentioned herein are incorporated by reference. Nothing herein is to be construed as an admission that the invention is not entitled to antedate such disclosure by virtue of prior invention.
The reservoir 11 may be comprised of a rigid inert plastic resin, but may also be made of any other material that would provide the reservoir 11 with rigid support and that would be compatible with ink. In an embodiment, the reservoir 11 may comprise ferromagnetic material, such as electroformed nickel bellows. The diameter of the reservoir outlet 13 may be dependent on the amount of ink 14 needed to flow into the reaction chamber 15 and be deposited onto the media.
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In addition to water and pigment, the ink formulation 14 may include a reactive compound that forms a gas when the compound is exposed to a catalyst. An example of such a compound is an oxygen-containing compound or a nitrogen-containing compound, such as hydrogen peroxide, which may form an oxygen or nitrogen gas when the compound is exposed to a catalyst. Exemplary ink formulations that incorporate water, pigment, and hydrogen peroxide can be found in U.S. Pat. Nos. 6,368,397 and 6,153,001, both disclosures of which are incorporated herein by reference in their entirety. If additional heat is desired in the ink, one or more additional exothermic reacting reagents could be included in the formulation. For example, hydroquinone (in the presence of the catalyst peroxidases) may generate additional heat through reaction with the oxygen that is produced when the hydrogen peroxide reacts with the catalyst.
Other compounds that form a gas when exposed to a catalyst may be used in the ink. In various embodiments, the gas may be of a gas that is non-corrosive and harmless to the material of the reaction chamber. In some embodiments, the reactive compound may comprise between about ½% by weight to about 3% by weight of the ink formulation. In other embodiments, the reactive compound may comprise between about ¼% by weight to about 15% by weight of the ink.
The reaction chamber 15 may be in the shape of a capillary tube and may be of a metal or plastic material. Alternatively, the chamber 15 may be of any other shape or material that is able to withstand the temperature and pressure of the reactions that take place in the chamber 15, as will be described later. In various embodiments, the size of the reaction chamber 15 may be about two to three times the size of the reservoir 11. However, other sizes are possible. The diameter of the inlet 16 and outlet 17 may be dependent on the amount of ink formulation 14 that is to be deposited onto the media. The reaction chamber may include at least one catalyst 25, which may include catalase and/or peroxidases. The catalyst may be in the form of a solid and may be impregnated in the walls of the chamber, may be contained in a matrix that forms the chamber's walls, may be in one or more capsules located within the reaction chamber, or may be otherwise situated within the chamber. Peroxidases are enzymes that utilize a peroxide or other material to oxidize certain oxidisable substrates. Catalase is an enzyme that catalyzes the decomposition of hydrogen peroxide into water and oxygen. Other oxygen or nitrogen forming catalysts, including those in solid, liquid or gas form, may be used in alternate embodiments.
In yet additional alternate embodiments, the reaction chamber and ink reservoir may be integrated such that the catalyst is introduced into the ink reservoir. Alternatively, the ink may be directed onto a catalyst-containing surface, including but not limited to a reaction chamber wall, a trench, an interior of a tube, a catalyst-containing screen, or other surface where the ink reacts with the catalyst and is expelled toward a medium.
In addition to a pressure increase within the reaction chamber, the reaction may cause an increase in temperature. The use of other material, such as hydroquinone, in the fluid may cause the reaction chamber temperature to be higher. For example, the temperature may be about 100° C., although other temperatures are possible. For example, temperatures ranging from about 60° C. to about 95° C. are possible. Depositing the ink onto the media at such a high temperature may allow drying of the deposited ink at a higher rate. Also, due to the pressure changes within the reaction chamber, the ink may be deposited onto the medium at a rate of about 500 deposits per second to about 1000 deposits per second. In some embodiments, the rate may be about 500 to about 800 deposits per second. Other rates are possible. The rate at which the ink is expelled onto the media may be dependent upon the size of the reaction chamber outlet and the rate of the reaction.
It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also, that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art, which are also intended to be encompassed by the following claims.
