Patent Application
20080043055
In the next place, embodiments according to the present invention will be described specifically with reference to the drawings. The same symbol in each drawing denotes the same part or corresponding part.
An ink tank (ink cartridge) 6 is detachably mounted in a recording head 3 carried by a carriage 2. Ink in the ink cartridge 6 is supplied to the recording head 3. A platen (not illustrated) for supporting a recording medium is installed at a position opposite to a discharge face (face having discharge ports arranged therein) of the recording head 3 carried by the carriage 2. A recording medium (P) fed from the paper feeding mechanism 5 is transported through a recording section (on the platen) by a transportation roller 61 driven by a transportation motor (not illustrated). The recording head 3 is a component for recording an image on the recording medium by discharging ink on the basis of an image signal. The ink jet recording apparatus 1 records an image on the recording medium transported over the platen by giving a driving signal based on the image signal to the recording head 3, in synchronization with the movement of the carriage 2 which is driven by the motor M1. The recording medium (P) having an image recorded is ejected from the main body of an apparatus by an ejection roller 63.
A recording head 3 in
A recording head 3 records an image by selectively discharging ink from a plurality of discharge ports when pulse voltage corresponding to a recording signal (image signal) is applied thereon. The recording head 3 according to the present embodiment in particular is provided with an electrothermal transducing member which generates thermal energy for discharging the ink when the pulse voltage is applied thereon. The recording head 3 discharges an ink droplet from the discharge port by making the electrothermal transducing member generate the thermal energy, making a film boil to grow and shrink a bubble and using the consequent pressure change. The electrothermal transducing member is individually provided in each of a plurality of the discharge ports, and makes the discharge port corresponding to the electrothermal transducing member discharge the ink droplet, by applying pulse voltage to the electrothermal transducing member in response to a recording signal.
In
In
The sucking recovery operation shall keep and recover the ink discharge performance of a recording head by eliminating the clogging in a discharge port through refreshing ink in each of the discharge ports (in each nozzle).
Then, the ink (waste ink) drained from a discharge port by the sucking operation is sent to a waste-ink-collecting portion connected to a sucking pump 62. The waste-ink-collecting portion is constituted by an ink absorbing member. The recording head is occasionally recovered by a preliminarily discharging operation for discharging the ink which does not contribute to recording toward an ink sump (or a cap 8) from each discharge port not illustrated.
The ink (waste ink) discharged to the ink sump through the preliminarily discharging operation is also sucked by the sucking pump 62 and is sent to the above described waste-ink-collecting portion. Thus, it is possible to protect a recording head 3 and also prevent ink from evaporating and drying while the recording head 3 is not in operation, by capping a discharge port of the recording head 3 with a cap 8. In addition, ink or dirt depositing on a discharge face 17 of the recording head 3 can be wiped and removed by a wiping mechanism 12. A capping unit 11, a wiping unit 12 and a sucking unit 62 as described above can co-operatively and appropriately keep and recover the ink discharge performance of the recording head 3 into a normal state.
The recovery unit keeps discharge characteristic normal or recovers the discharge characteristics to a normal condition, by forcefully draining ink from a recording head 3, apart from a discharge operation for recording.
An ink jet recording apparatus according to a first embodiment also has an ink absorbing member 31 (
At a predetermined position of the main body of a recording apparatus, a waste-ink-collecting unit 50 is arranged so as to collect ink drained by a sucking recovery unit 62, as is shown in
In the next place, examples of the ink and a coloring material will be described which can be used in an ink jet recording apparatus according to the present invention. An object of the present invention is to prevent a mixed ink from thickening or being fixed, even when such inks as to react with each other are sucked through the same cap in a sucking recovery operation for a recording head. The present invention provides an ink capable of further improving bleeding performance. The above described object is more effectively achieved by using the ink of which the coloring material precipitates when having contacted an ink absorbing member (also referred to as waste-ink absorbing member) for collecting the waste ink.
As a result of having searched for a cause or a factor which causes the above phenomenon, it was found that the ink has characteristic properties and shows a phenomenon associated with the characteristics of a coloring material itself, a relationship between the coloring material and a solvent and a mixed state of them, which will be described below. However, the present invention is not limited to the following description, but can be applied to various coloring materials in ink and the inks which cause newly found properties and phenomena or characteristic properties and phenomena.
Incidentally, bleeding means the blur or color mixture of ink formed on a recording medium. In addition, bleeding performance means the performance of reducing or inhibiting the bleeding.
The ink having improved bleeding performance is an ink, for instance, using a self-dispersion pigment (such as carbon black) as a coloring material, which is coupled with a functional group having hydrophilicity directly or through another atomic group. Furthermore, the ink is also an ink (first ink) with the use of a plurality of water-soluble organic solvents at least one of which is a poor solvent having characteristics of lowering the dispersion stability of the pigment. When such ink is applied on a recording medium, the poor solvent increases its ratio with respect to the pigment along with the evaporation of water, so that the pigments start coagulating with each other in the upper layer of the recording medium. As a result of this, the ink can show a function (or performance) of inhibiting bleeding, even singly or even when another ink exists in the periphery.
Furthermore, as for a coloring material in first ink, when the ink uses a pigment densely having hydrophilic groups coupled on the pigment surface as the coloring material, the ink remarkably shows the following phenomenon.
Specifically, the ink remarkably shows the phenomenon that the coloring material is solidified and adhered to a waste-ink absorbing member and the waste-ink absorbing member extremely lowers the absorptivity thereof along with showing the above described advantage remarkably. In this case, a pigment is hardly solvated by a solvent in ink in comparison with a conventional self-dispersion pigment, because of being affected by steric hindrance originating in a coloring material structure, and the ink shows a tendency of lowering the dispersion stability of the pigment due to the evaporation of a trace amount of water. As a result of this, the ink has an effect of further reducing bleeding.
Furthermore, bleeding can be further reduced by an ink which is thickened or increases its particle size along with the evaporation of water, specifically, which varies an average particle diameter by about 25% or more between before and after the evaporation of water, when about 40% of water have evaporated from a liquid.
The particle size can be easily confirmed without diluting the ink, by using, for instance, Fiber-Optics Particle Analyzer with Autosampler FPAR-1000 (trade name; made by Otsuka Electronics Co., Ltd.)
The inks have an effect of further reducing bleeding, which show higher viscosity when the viscosity of the mixture is measured after a pigment black ink has been mixed with a dye color ink, than both of the viscosities of the pigment black ink and the dye color ink.
Examples of such a dye color ink are a dye color ink containing a solvent which is a poor solvent with respect to a pigment contained in the pigment black ink; and further an ink having a coloring material with a structure having a benzene ring in an end at least as the coloring material. The coloring material with the structure having the benzene ring in the end has generally characteristics of easily being adsorbed by the pigment. When such a dye color ink is mixed with pigment ink, the dye color ink deteriorates the dispersion stability of the pigment. In the present application, such a dye ink is referred to as a dye color ink which causes a phase reaction with the pigment black ink.
In addition, when a first ink and a second ink show higher viscosity when the viscosity of the mixture is measured after the two inks have been mixed than both of the viscosities of the first ink and the second ink, the first ink and the second ink have an effect of further reducing bleeding.
An evaporation degree of water from waste ink varies according to, for instance, a material of a waste-ink tube, an inner diameter of the tube, or the quantity of the ink (waste ink) drained by one recovery operation.
However, the quality of a material for a generally-used waste-ink tube and the inner diameter of the tube are limited, and the quantity of the waste ink drained by one recovery operation is also generally in a predetermined range.
Incidentally, a poor solvent according to the present invention is a solvent which shows such characteristics as “a particle in a pigment-dispersed liquid which includes about 50 mass % of a solvent to be evaluated and disperses a coloring material to be used in ink therein shows a larger size than the particle in a pigment-dispersed liquid described below, after the former liquid has been kept at 60° C. for 48 hours”. This “a pigment-dispersed liquid described below” is “a pigment-dispersed liquid which includes no or a small amount of the solvent to be evaluated and disperses the water-insoluble coloring material to be used in the ink therein”. In addition, a good solvent is a solvent which shows the characteristics except those of the poor solvent.
In the next place, an example of a second ink will be shown which inhibits a first ink and the second ink from diffusing or migrating into a waste-ink absorbing member when the first ink is made contact with the second ink.
The example includes a second ink which contains, for instance, a poor solvent with respect to a pigment contained in a first ink, for the purpose of further reducing bleeding to be formed on a recording medium. The example further includes an ink that contains coloring materials at least one of which has a structure having a benzene ring (which may have a hydrophilic moiety in a part when having a hydrophobic moiety in most parts) in an end. The coloring material with the structure having a benzene ring in the end is generally provided with characteristics of easily being adsorbed by pigment.
The second ink thus deteriorates the dispersion stability of pigment, so that the first ink and the second ink easily form a barrier which inhibits a waste ink originating in both inks from diffusing or migrating into a waste-ink absorbing member, when the waste ink contacts the waste-ink absorbing member. Accordingly, the inks make a technical problem of preventing the inks from thickening and being fixed due to mixing in the present invention remarkable, and make an effect obtained by solving the technical problem as well remarkable. Furthermore, when the first ink and the second ink have a relationship described below, it is necessary to prescribe a position for the waste ink originating in each ink to be introduced, as the above description. Specifically, the above relationship between the first ink and the second ink includes a relationship that when both of the inks are mixed and the viscosity of the mixture is measured, the viscosity is higher than any one of the viscosities of the respective inks.
A specific example of a second coloring material includes the coloring material shown in a structural formula (1) and a structural formula (2), which facilitates the waste ink originating in a first ink and a second ink to form a barrier for inhibiting the waste ink from diffusing or migrating into a waste-ink absorbing member, when the waste ink contacts the waste-ink absorbing member.
Formula 1
R1 in the above described “Structural Formula (1)” represents a hydrogen atom, an alkyl group, a hydroxy lower alkyl group, a cyclohexyl group, a monoalkylamino alkyl group, a dialkylamino alkyl group or a cyano lower alkyl group. Y in “Structural Formula (1)” represents a chlorine atom, a hydroxyl group, an amino group, a monoalkylamino group or a dialkylamino group. The monoalkylamino group and the dialkylamino group may have a substituent selected from the group consisting of a sulfo group, a carboxyl group and a hydroxyl group on the alkyl group. R2, R3, R4, R5 and R6 in “Structural Formula (1)” each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or carboxyl group. However, all of R2, R3, R4, R5 and R6 cannot be simultaneously a hydrogen atom.
A specific example of a compound shown in “Structural Formula (1)” includes each exemplary compound which has a structure shown in each chemical formula in the following “Formula 2” in a form of a free acid. Among these exemplary compounds M1 to M7, the exemplary compound of M7 can be used in particular.
In the above described “Structural Formula (2)”, l=0 to 2, m=1 to 3, n=1 to 3, while satisfying l+m+n=3 to 4, and a substitution site by a substituent is shown by 4 or 4′. M in “Structural Formula (2) ” represents an alkali metal or ammonium. R1 and R2 represent each independently a hydrogen atom, a sulfo group or a carboxyl group. However, R1 and R2 cannot be simultaneously a hydrogen atom. Y in “Structural Formula (2)” represents a chlorine atom, a hydroxyl group, an amino group, a monoalkylamino group or a dialkylamino group.
A coloring material shown in “Structural Formula (2)” is a characteristic phthalocyanine compound that is prepared by: using a phthalocyanine compound as a raw material, which is obtained by reacting a 4-sulfophthalic derivative, or a 4-sulfophthalic derivative and a phthalic derivative (for instance, phthalic anhydride) in the presence of a metallic compound; converting a sulfone group in the raw material to a chlorosulfone group; and reacting the resultant compound with an amination agent in the presence of an organic amine.
A coloring material shown in “Structural Formula (2)” is a characteristic phthalocyanine compound which has an unsubstituted sulfamoyl group (—SO2NH2) and a substituted sulfamoyl group (Structural Formula (3) of “Formula 4” described below) introduced only at positions of 4 and 4′ in the structural formula. The above positions of 4 and 4′ in “Structural Formula (2)” are the positions of R2, R3, R6, R7, R10, R11, R14 and R15 in “Structure Formula (2)”. It was found that the ink using such a compound as a coloring material has extremely superior resistance to an environmental gas.
A specific example of a compound shown by “Structural Formula (3)” includes each exemplary compound having a structure shown by each chemical formula of “Formula 5” described below in a form of a free acid. Among these exemplary compounds C1 to C7, the exemplary compound C1 can be used in particular.
By using the first ink and the second ink having the above described characteristics, the ink jet recording apparatus can markedly improve bleeding performance in comparison with conventional inks. However, it was found that the above described respective waste inks cause a phenomenon of forming such a barrier as to inhibit the respective waste inks from diffusing or migrating into a waste-ink absorbing member, when the respective waste inks are each drained dropwise to an adjacent part of the waste-ink absorbing member.
In the next place, a first embodiment according to the present invention will be described in detail with reference to the drawings.
The structure of
In other words, as illustrated in
As waste ink is repeatedly collected by repeating a sucking recovery operation, a separated solid part 41 and liquid part 42 expands, as illustrated in
The ink absorbing member 31 is separately arranged below an outlet 43 of a sucking tube 7. However, a distance (L) between the outlet 43 and the surface of the ink absorbing member 31 is not limited in particular.
However, when a distance (L) is too short, an outlet 43 in itself may be blocked by thickened waste ink. Accordingly, it is necessary to secure the distance (L) to some extent.
Here, an ink to be used in an ink jet recording apparatus according to the present invention will be described in detail with reference to a specific example. However, the present invention is not limited to the example.
At first, a method for preparing a pigment-dispersed body for black ink will be described with reference to a specific example. The pigment-dispersed body for black ink was prepared by: at first, preparing a hydrochloric acid solution by dissolving 5 g of concentrated hydrochloric acid in 5.5 g of water, and adding 1.5 g of 4-amino-1,2-benzene dicarboxylic acid to the solution, while keeping the solution cooled to 5° C.; subsequently, accommodating a container containing the solution in an ice bath and stirring the solution to keep the solution to 10° C. or lower, preparing a sodium nitrite solution by dissolving 1.8 g of sodium nitrite in 9 g of water cooled to 5° C., and adding the latter solution to the former solution; further stirring the above mixed solution for 15 minutes, and adding 6 g of carbon black with a specific surface area of 220 m2/g and a DBP oil absorption of 105 mL/100 g into the solution while stirring the solution; and subsequently, further stirring the above mixed liquid for 15 minutes. Self-dispersible carbon black was prepared by: filtering obtained slurry with a filter paper (trade name: Standard Filter Paper No. 2; made by Advantec); thoroughly washing particles with water; and drying the particles in an oven of 110° C. A dispersion liquid having a concentration of 10 mass % of the pigment dispersed therein was prepared further by adding water to the obtained self-dispersible carbon black. The pigment-dispersed liquid obtained by the above described method had the self-dispersible carbon black dispersed in water, which had a —C6H3—(COONa)2 group introduced on the particle surface of carbon black.
Next, a method for preparing a black ink 1 will be described with reference to a specific example. The black ink 1 was prepared specifically by: mixing the above described pigment-dispersed liquid (35 parts by mass) with glycerine (7.0 parts by mass), diethylene glycol (6 parts by mass) and diammonium phthalate (0.5 parts by mass); mixing the above liquid further with Acetylenol E100 (an ethylene oxide adduct of acetylenic glycol made by Kawaken Fine Chemicals Co., Ltd.) (0.2 parts by mass) and water (45.3 parts by mass); stirring the above described mixture for one hour; and afterwards, pressure-filtering the mixture with a filter (FR20 made by FUJI FILM Corporation). The black ink 1 showed a viscosity of 2.3 mPa·s at 25° C.
Next, a method for preparing a yellow ink 1 will be described with reference to a specific example. The yellow ink 1 was prepared specifically by: mixing C.I. direct yellow 132 (4 parts by mass) with glycerine (7 parts by mass), polyethylene glycol 600 (4 parts by mass) and 2-pyrrolidone (5 parts by mass); mixing the above liquid further with Acetylenol E100 (an ethylene oxide adduct of acetylene glycol made by Kawaken Fine Chemicals Co., Ltd.) (1 part by mass) and water (79 parts by mass); stirring the above described mixture for one hour; and afterwards, pressure-filtering the mixture with a filter (FR20 made by Fuji Film). The yellow ink 1 showed a viscosity of 2.0 mPa·s at 25° C.
Next, a viscosity of a mixed ink of the above described black ink 1 and the above described yellow ink 1 will be described. The above described black ink 1 and the above described yellow ink 1 were mixed at a ratio of 1:1, and the mixture was thoroughly stirred. Subsequently, the liquid mixture showed the viscosity of 3.0 mPa·s when measured at 25° C. From the measurement result on the viscosity, it was confirmed that the mixing action of two inks increases (thickens) the viscosity of the mixed ink.
An ink jet recording apparatus having a waste-ink-collecting unit 50 according to the above described first embodiment will be described with reference to some Examples. In these Examples, a recovery unit (sucking pump 62) sucks the above described black ink 1 and the above described color ink 1 together; introduces the mixed ink into a waste-ink-collecting unit 50; and drains waste ink dropwise onto an ink absorbing member 31. Thus, the waste-ink-collecting unit 50 collects the waste ink.
A used waste-ink-collecting unit 50 employed a structure which accommodates an ink absorbing member 31 with a rectangular solid shape in a frame 35 with a rectangular shape, as is illustrated in
A recording head 3 had a discharge face 17 having a discharge port array 13 for discharging a black ink 1 and a discharge port array 14 for discharging a yellow ink 1 arrayed thereon, as is illustrated in
The other structure is substantially the same as in the case of the above described Example 1. Then, a recovery operation was repeated and an upper part of the ink absorbing member 31 was observed. Then, the waste ink 45 was separated into a solid part 41 and a liquid part 42, and was retained by the ink absorbing member 31. A deposit of the solid part 41 in the present embodiment was dispersed toward the lower part of the ink absorbing member 31, similarly to the case of Example 2.
In addition, in Examples 1 to 4 described above, a capability of inhibiting bleeding on a recording image was evaluated which is specifically a capability of reducing bleeding or color mixture on an image recorded by printing a black line on the backdrop of a solid printing of yellow, with the use of a black ink 1 and a yellow ink 1. As a result of this, any Example showed an extremely satisfactory capability.
An ink jet recording apparatus according to the above described embodiment drains a mixed ink of pigment ink drained from a discharge portion of black ink and a dye ink which has been drained from a color ink discharge portion and has reactivity with the pigment ink; collects it on an ink absorbing member 31; and vaporizes water in the mixed ink on the ink absorbing member.
As a result of this, the ink jet recording apparatus can separate the drained ink into a solid part 41 of pigment and a liquid part 42 of dye, and retain the solid part and the liquid part on the ink absorbing member. Accordingly, the ink jet recording apparatus can keep an adequate absorptivity of the ink absorbing member 31 of a waste-ink-collecting unit 50 for a long period of time, even when recording an image of high quality free from blur by reacting black ink with color ink to make them solidified or thickened when recording the image.
In the next place, a second embodiment according to the present invention will be described in detail with reference to the drawings.
Around the hole 37 engaging with the protruding portion 36, the ink absorbing member 31 shows such a shape as to swell up to a part right under the transfer member 33 along the protruding portion, and also shows such a shape as to swell up along an inner wall surface of a frame 35 in a peripheral area along the inner wall surface. In the case of the figure, the ink absorbing member 31 in the peripheral area swells up to a slightly higher position than the transfer member 33. Accordingly, as a whole, the ink absorbing member shows such a shape as to swell up in the central part around the protruding portion 36 and in the peripheral area, and to be dent between them while the upper surface is opened. A sucking tube 7 works as an ink introduction unit for introducing ink (waste ink) drained by a recovery unit such as a sucking pump 62 to a waste-ink-collecting unit 60.
A transfer member 33 is arranged below and detached from an outlet 43 of the sucking tube 7 which is the ink introduction unit. The ink which has been introduced by the sucking tube 7 is drained dropwise onto the transfer member 33 through the outlet 43 of the tube. In the lower part of the transfer member 33, an ink absorbing member 31 is arranged. The waste ink 45 drained dropwise onto the transfer member 33 flows down on the surface of the transfer member and is drained dropwise onto the ink absorbing member 31.
A material of an ink absorbing member 31 has only to have a function for moderately retaining waste ink, and is not limited in particular. A usable material includes, for instance, a porous member such as a sponge, or a fibrous body using a pulp as a raw material; and a member made from a polymer absorbent, or a member made of a paper-shaped body having the polymer absorbent sprinkled thereon. In the case of the figure, a transfer member 33 and a protruding portion 36 are formed integrally with a frame 35 and from the same material, but are not limited to this; and may have a structure, for instance, in which members made from different materials is jointed.
In
In
The higher is a density of the ink absorbing member 31, the more remarkably the drained ink shows a tendency of being separated immediately.
As waste ink is repeatedly collected by repeating a sucking recovery operation, a separated solid part 41 and liquid part 42 expands, as shown in
The second embodiment in
A used waste-ink-collecting unit 60 had a structure which accommodates an ink absorbing member 31 in a frame 35 with a rectangular shape, as is illustrated in
In the present Example as well, a recording head 3 had a discharge face 17 having a discharge port array 13 for discharging a black ink 1 and a discharge port array 14 for discharging a yellow ink 1 arrayed thereon, as is illustrated in
The sucked waste ink was drained dropwise onto the top part of a transfer member 33 through a sucking tube 7. The sucked waste ink was further drained dropwise onto a slope of an ink absorbing member 31 through the surface of the transfer member 33. The surface of the transfer member 33 can be treated to be water repellent, in this case as well. Such a recovery operation was repeated and the ink absorbing member 31 was observed. Then, the waste ink (mixed ink) 45 was separated into a solid part 41 and a liquid part 42, and was retained by the ink absorbing member (
The present Example has a feature of arranging an ink absorbing member 31 so as to surround a transfer member 33 (and protruding portion 36). Specifically, a waste-ink-collecting unit has a structure of accommodating the ink absorbing member 31 with a recessed shape having an opening 38 in a central part and having an opened upper end along an inner wall surface and the bottom surface of a frame 35, and arranging the transfer member 33 in the center of the opening 38. In the present Example as well, when a recovery operation was repeated and the ink absorbing member 31 was observed, the waste ink drained dropwise was separated into a solid part 41 and a liquid part 42, and was retained by the ink absorbing member 31. In addition, a waste-ink-collecting unit in the present Example has a structure of hardly leaking a deposit of the solid part 41 to the outside of a recording apparatus in comparison with that in Example 5, because the transfer member 33 is surrounded by the cylindrical ink absorbing member 31.
In the above described second embodiment as well, a capability of inhibiting bleeding on a recording image was evaluated which is specifically a capability of reducing bleeding or color mixture on an image recorded by printing a black line on the backdrop of a solid printing of yellow, with the use of a black ink 1 and a yellow ink 1. As a result of this, both of Examples showed extremely satisfactory capability.
An ink jet recording apparatus according to the above described second embodiment has a structure of transferring a mixed ink of pigment ink drained from a discharge portion of black ink and a dye ink which has been drained from a color ink discharge portion and has reactivity with the pigment ink, onto an ink absorbing member through a transfer member; and being capable of vaporizing water of the mixed ink on the ink absorbing member. As a result of this, the ink jet recording apparatus can separate the drained ink into a solid part of a pigment and a liquid part of a dye, on the ink absorbing member. Accordingly, the ink jet recording apparatus can keep an adequate absorptivity of the ink absorbing member 31 of a waste-ink-collecting unit 60 for a long period of time, even when recording an image of high quality free from blur by reacting black ink with color ink to make them solidified or thickened when recording the image.
An ink-jet recording apparatus described as an example in the above embodiment was a serial type which uses a recording head that is carried by a carriage and moves along a recording medium. The present invention can be also similarly applied to an ink-jet recording apparatus of a line type which records an image only by vertically scanning a recording head for full-line recording. The present invention also can be similarly applied to any ink-jet recording apparatus regardless of the number of recording heads, and of the number of types and properties of the ink, and shows a similar operation/working-effect. Furthermore, the present invention is not limited to a unit device such as a printer, a copying machine, a facsimile and an image-forming device. The present invention can be widely applied to a combined apparatus like a composite apparatus which combines the above unit devices, or a recording apparatus in a computer system, and shows a similar operation/working-effect.
While the present invention has been described with reference to Examples, it is to be understood that the invention is not limited to the disclosed Examples. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2006-170977, filed Jun. 21, 2006, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-170977 | Jun 2006 | JP | national |
