JP4286422B2 - Liquid transport device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, by using a resistance applying portion whose conductance changes depending on the direction of ink flow, different inks are merged and ejected as continuous flow to an ink ejection port provided for each pixel, and the ejection flow rate is based on an image signal. The present invention relates to a liquid transport apparatus used for an image recording head that controls each ink for each pixel to form an image .
[0002]
[Prior art]
Conventionally, various types of image recording heads have been proposed as image recording heads for forming an image by controlling the amount of ink discharged based on an image signal. For example, there are known ones that form an image by changing the density of ejected ink (US Pat. Nos. 4,109,282, 4,614,953, JP-A-5-201024, and 7-125259). 3-207664, 9-156131, etc.).
[0003]
In U.S. Pat. No. 4,109,282 (hereinafter referred to as Prior Art Document 1), a valve called a flap valve is provided in a flow path for guiding two liquids of clear ink and black ink to a substrate for image formation. Disclosed is a printing apparatus in which the flow path of each ink is opened and closed by displacing the valve, and the two liquids are mixed to a desired concentration and transferred onto a substrate. As a result, an image having the same gray scale information as the image information displayed on the TV screen can be printed out. Here, it is disclosed that a voltage is applied between a valve of a flap valve and an electrode provided on an opposite surface thereof, and the valve is displaced by mechanically deforming the valve itself by its electrostatic attraction. Yes. The ink is sucked out by capillary action between fibers of the printing paper.
[0004]
U.S. Pat. No. 4,614,953 (hereinafter referred to as Prior Art Document 2) discloses a printer head device in which a plurality of differently colored inks and solvents are introduced into a third chamber and mixed in a desired amount. . Here, as a means for weighing a desired amount of ink, it is disclosed to use a pressure pulse obtained by driving a piezo element using a chamber and a piezo effect element portion attached to the chamber. Has been.
[0005]
Japanese Laid-Open Patent Publication No. 5-201024 (hereinafter referred to as Prior Art Document 3) discloses a liquid chamber filled with a carrier liquid, an ink jet driving means provided in the liquid chamber, a nozzle communicating with the liquid chamber, An ink jet print head is disclosed that includes a mixing section that mixes ink into a carrier liquid. It is also disclosed here that an adjusting means using an electroosmosis phenomenon is provided to adjust the ink mixing amount to a desired value.
[0006]
Similarly, Japanese Patent Laid-Open No. 7-125259 (hereinafter referred to as Prior Art Document 4) discloses first and second supply means for supplying ink having first and second densities, and first so as to obtain a desired ink density. And an ink jet recording head having control means for controlling the amount of the second ink supplied by the second supplying means.
[0007]
Here, as a control means, there is disclosed a micropump having a dedicated heating element and driven by its thermal energy. As this micropump, an example is disclosed in which heat energy is generated by a heating element, and a piston-like valve or a cantilever valve is driven by the pressure generated by nucleate boiling. Further, it is described here that by using this valve in combination with an actuator made of a shape memory alloy, the ink inflow amount can be effectively controlled particularly in a region where the inflow amount is small.
[0008]
Japanese Patent Application Laid-Open No. 3-207664 (hereinafter referred to as Prior Art Document 5) has a structure similar to that of Prior Art Document 2, except that the ejection amount of a plurality of inks is controlled by the pulse width applied to the piezoelectric element, and these are mixed. The structure to be combined is shown.
[0009]
Japanese Patent Application Laid-Open No. 9-156131 (hereinafter referred to as Prior Art Document 6) includes a plurality of printer heads that form images of a plurality of colors based on image data, and mixes ink and diluent at a predetermined mixing ratio. There is shown an ink jet printer which forms a recorded image on a recording medium by ejecting the diluted ink from a nozzle. Here, when, for example, all-white image data having a small ink mixing amount and does not reach a clear print density is input to the plurality of printer heads, the dilution liquid is supplied from at least one of the plurality of printer heads. An ink jet printer that discharges ink is disclosed. As a result, a sudden gradation change (tone jump) is prevented, and excessive consumption of the diluent is suppressed, thereby improving the drying property. The volume of the diluent is controlled by the pulse voltage, the pulse width, the number of pulses, etc. applied to the drive unit formed by the piezoelectric element.
[0010]
Thus, in Prior Art Document 1, the amount of ink flowing down due to gravity is controlled by changing the opening area of the ink discharge port. In Document 2, the ink ejection amount is controlled by the displacement amount and the number of displacements of the diaphragm. In Document 3, the ink ejection amount is controlled by electroosmosis. In Document 4, the discharge amount of prepressurized ink is controlled by a micropump that is opened and closed by a heater. In Reference 5, it is controlled by the displacement amount and the number of displacements of the piezoelectric element. In Document 6, the ink discharge amount is controlled by displacing the wall of the ink tank with a piezoelectric element.
[0011]
[Problems to be solved by the invention]
Among these prior arts, those having a pump function for positively discharging ink include those in Documents 2, 5, and 6. However, these all have a pressurizing chamber (cavity part) whose volume is enlarged in the middle of the ink flow path, and the volume of the pressurizing chamber is changed by vibration of the diaphragm or the tank wall. The upstream side and the downstream side did not have a check valve for preventing the back flow of ink. For this reason, the ink flows backward to the upstream side with the change in the volume of the pressurizing chamber, and there is a problem that the reverse flow rate increases and the efficiency of the pump deteriorates.
[0012]
Therefore, the applicant provides resistance applying portions (throttles) whose conductance (reciprocal of resistance) varies depending on the direction of ink flow on the upstream side (inlet side) and downstream side (outlet side) of the pressurizing chamber (cavity portion). (Japanese Patent Application No. 11-351008 etc.). Since this resistance imparting part does not have a mechanical moving part like a general one-way valve, it is excellent in durability and reliability, and can be manufactured by a manufacturing method such as a micromachine, and is easy to manufacture. It has the advantage of being.
[0013]
However, since this resistance applying portion is provided with a geometrically complicated portion such as a minute restriction on the inner wall surface of the flow path, if the liquid contains fine bubbles, the bubbles will be It is easily trapped and attached. It is very difficult to discharge these bubbles when they enter a fine groove or the like of the resistance imparting portion.
[0014]
In addition, when bubbles are attached in this way, the volume of the bubbles changes as the volume of the cavity changes, and the drive energy that changes the volume of the cavity cannot be sufficiently transmitted to the liquid, and the pump efficiency is increased. It can be bad.
[0015]
This invention has been made in view of such circumstances, it is Rukoto ejected efficiently different inks to prevent backflow of different inks for each pixel from the transported are merged as a continuous flow in one direction the ink discharge port Furthermore, it is an object of the present invention to provide a liquid transport apparatus used for an image recording head that can be manufactured using a manufacturing method such as a micromachine and can be easily manufactured.
[0016]
[Structure of the invention]
According to the present invention, the object is to change the volume of the cavity portion of the ink discharge pump by driving the ink discharge pump provided in the middle of the ink flow path, and to transfer the ink to the image receptor, thereby transferring the image. In a liquid transport apparatus used for an image recording head for forming
An ink flow path in which non-image forming ink that does not substantially form an image after drying and image forming ink that substantially forms an image after drying are merged at a merging portion and ejected from an ink ejection port provided for each pixel; An ink supply pump that applies a constant pressure to the ink in the ink flow path, and a direction in which the conductance increases in the ink flow path upstream of the cavity portion and between the cavity portion and the merge portion. A resistance imparting portion having no movable portion provided in alignment with the transport direction and having a hydrophilic treatment in the vicinity of the inner wall surface thereof, and the non-image forming ink and the image forming ink ejected by the ink ejection pump to the pixels merging of these inks in the joint portion and the discharge flow rate while controlling the number of drive pulses based on the image signal so that these total flow rate is substantially constant The liquid transport apparatus, characterized in that it comprises a control unit from the ink discharge ports is discharged as a continuous flow to transfer as a continuous fluid to the image receptor, it is accomplished by.
[0017]
The same purpose is to change the volume of the cavity of the ink discharge pump by driving the ink discharge pump provided in the middle of the ink flow path, and transfer the ink to the image receptor to form an image. In a liquid transport device used for a recording head,
An ink flow path in which non-image forming ink that does not substantially form an image after drying and image forming ink that substantially forms an image after drying are merged at a merging portion and ejected from an ink ejection port provided for each pixel; An ink supply pump that applies a constant pressure to the ink in the ink flow path, and a direction in which the conductance increases in the ink flow path upstream of the cavity portion and between the cavity portion and the merge portion. The inner wall surface is provided in the transport direction, and the inner wall surface is formed of a curved surface that is smoothly continuous in the ink transport direction. The resistance applying portion does not have a movable portion, and the image is ejected by the ink ejection pump to the pixels. the discharge flow rate of the non-forming ink and the image forming ink these while controlling the number of drive pulses based on the image signal so that these total flow rate is substantially constant It is also achieved by a liquid transporting apparatus comprising a control unit that merges different inks at the merging unit, ejects them from the ink ejection port as a continuous flow, and transfers them as a continuous fluid to the image receptor. .
[0019]
Such a configuration for preventing the adhesion of bubbles may be provided in all the resistance applying portions, but only a part of the resistance applying portions may have a configuration for preventing the bubble adhesion. Good.
[0020]
In order to change the volume of the cavity part, a structure in which a movable wall driven by a drive part is provided in the cavity part and the movable wall is moved can be used. For example, a part of the wall of the cavity portion may be formed of a diaphragm, and the diaphragm may be driven using a piezoelectric element (piezoelectric element), a magnetostrictive element, or an electrostatic force.
[0021]
The resistance applying portion may be of a geometric shape in which the conductance in the ink transport direction is larger than the conductance in the opposite direction. For example, it is possible to form a divergent nozzle (defuser nozzle) in which the cross-sectional area increases rapidly on the upstream side and gradually increases on the downstream side across the throat where the cross-sectional area of the flow path is minimized. . A plurality of resistance applying portions may be provided on either the upstream side of the cavity portion and between the cavity portion and the merging portion, but a plurality of resistance applying portions are provided both on the upstream side and between the cavity portion and the merging portion. If the portion is provided, the backflow of the ink is further prevented, and the improvement of the transport efficiency is increased.
[0022]
This liquid transport device is used for an image recording head, and forms an image by controlling the discharge amounts of different inks based on image signals. In this case, the total discharge amount of different inks is always kept substantially constant. That is, the ink to be ejected is formed with non-image forming ink (transparent ink) that does not substantially form an image after drying and image forming ink (for example, colored ink such as black ink) that substantially forms an image after drying. and, that controls the discharge amount of each of the solutions so that the total flow rate of the ink is substantially constant.
[0023]
A plurality of ink flow paths having different colors and an ink flow path for non-image forming ink are gathered on the upstream side of one ink discharge port, and the amount of ink supplied from each ink flow path is controlled separately to discharge ink. You may make it set the color of the fluid discharged from an exit.
[0024]
Ink ejected successively from the ink ejection port, you transfer the ink as a continuous fluid to the image receptor (continuous coating method). Here, when the ink transported from one ink discharge port to the image receptor is formed by the non-image forming liquid and the image forming liquid, the liquids may be mixed homogeneously, but without mixing them. You may make it apply | coat in the state piled up in layers.
[0026]
Embodiment
FIG. 1 is a conceptual diagram of a continuous coating type image forming apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of an image recording head used therein, FIG. 3 is an explanatory view of the structure of the ink discharge pump, and FIG. FIG. 4 is an enlarged cross-sectional view of a resistance applying portion. In FIG. 1, reference numeral 10 denotes a platen, and reference numeral 12 denotes a print sheet as an image receptor wound around the platen 10. The print paper 12 is fed in the direction of the arrow at a constant speed by the clockwise rotation of the platen 10 in the drawing.
[0027]
Reference numeral 14 denotes an undercoat portion, which applies a transparent undercoat liquid to the print paper 12 in order to improve ink adhesion and improve image quality. An image recording head 16 mixes the first ink and the second ink and guides them to the print paper 12 to form an image on the print paper 12. A heater 18 heats the print paper 12 on which an image is formed by the image recording head 16 to dry the ink.
[0028]
As shown in FIG. 2, the image recording head 16 includes a first ink flow path 20 and a second ink flow path 22, and each of the flow paths 20 and 22 includes a first ink and a second ink flow path, respectively. Of ink is supplied. The flow rates of the respective inks are merged after being controlled by the ink discharge pumps 24 and 26, and are guided to the ink discharge port 28.
[0029]
An ink discharge port 28 is provided for each pixel in the width direction of the print paper 12, and ink having a controlled density and / or color corresponding to each pixel is discharged from each ink discharge port 28. As the first ink, a colorless and transparent ink, that is, an ink that becomes colorless and transparent when dried, can be used, and includes an anti-fading agent such as an antioxidant or an ultraviolet absorber. The second ink is, for example, black ink.
[0030]
These first and second inks are accommodated in ink tanks 30 and 32, respectively, and constant pressure is applied from the ink tanks 30 and 32 to the first and second ink flow paths 20 and 22 by ink supply pumps 34 and 36, respectively. Sent out. As the pumps 34 and 36 used here, for example, a structure having a pressure regulating valve on the ink discharge side and holding the discharge pressure constant is suitable. Also that text others pressurizing ink by supplying a constant air pressure in these tanks 30 and 32 as being sealed.
[0031]
For example, ink discharge pumps 24 and 26 corresponding to one pixel can be formed on a common substrate. The image recording head 16 can be made by laminating each substrate prepared for each pixel with a partition plate in between.
[0032]
The pumps 24 and 26 include resistance applying portions 42a, 42b and 44a, 44b having no movable portions, and cavity portions 46, 48 formed between the resistance applying portions 42a and 42b and between 44a and 44b, Diaphragms 50 and 52 facing the cavity portions 46 and 48 and drive units 54 and 56 for driving the diaphragms 50 and 52 are provided.
[0033]
The resistance applying portions 42a, 42b and 44a, 44b do not have a movable portion, and are formed by a diaphragm having a shape in which conductance (reciprocal of resistance) changes with respect to the cavity portions 46, 48 depending on the ink flow direction. That is, these resistance applying portions 42a, 42b, 44a, and 44b are diaphragms having a geometric shape such that conductance (reciprocal of resistance) in the ink flow direction (transport direction) is larger than conductance in the reverse direction. Is. Therefore, it has no movable part and can be easily manufactured by a manufacturing method of a micromachine. Since these resistance applying portions 42a, 42b, 44a, and 44b all have the same structure, the structure will be described using one resistance applying portion 42a used for one ink discharge pump 24.
[0034]
As shown in FIG. 3, the resistance applying portion 42 a has a slope A in which the ink flow path area increases substantially continuously in the ink flow direction (the direction from the left to the right in FIGS. 2 and 3), and in the opposite direction. And a plane B in which the ink flow path area increases rapidly. That is, the nozzle is a divergent nozzle that has a long throat on the downstream side and a short upstream side across the throat that minimizes the cross-sectional area of the channel.
[0035]
The operation of the resistance applying unit 42a will be described qualitatively. First, when the ink flows from the left side to the right side in FIGS. 2 and 3, the ink flows through the throat along the slope A as a flow close to rectification. For this reason, the pressure loss at that time becomes small, and the flow resistance is small. On the contrary, when the ink flows from the right side to the left side, the ink passes through the throat and rapidly expands by the plane B, resulting in turbulent flow. For this reason, pressure loss increases and flow resistance increases. Depending on the angle between the slope A and the plane B, the flow direction in which the flow resistance increases may be reversed. At this time, the direction of the resistance applying portion is reversed.
[0036]
There are cavity portions 46 and 48 whose volumes vary between the resistance applying portions 42a and 42b and between 44a and 44b. The volumes of the cavity portions 46 and 48 are diaphragms 50 and 52 driven by the drive portions 54 and 56, respectively. It depends on. Piezo elements (piezoelectric elements) and magnetostrictive elements are suitable for the drive units 54 and 56, and in particular, PZT (lead titanate / lead zirconate solid body), barium titanate (BaTiO ₃ ), solid bodies of PZT and barium titanate, etc. The piezo element used is optimal.
[0037]
The driving units 54 and 56 may use other effects instead of using the piezo effect or the magnetostriction effect. It is caused by thermal pressure effect, electrostatic attractive force or electrostatic repulsive force, effect of interfacial tension of fluids different from multiple fluids used for image formation, electrolysis and / or heat of fluids different from multiple fluids used for image formation For example, an effect of changing the fluid pressure of the liquid by changing the flow resistance of the fluid different from a plurality of fluids used for image formation may be used.
[0038]
When the volumes of the cavity portions 46 and 48 change due to the changes in the diaphragms 50 and 52, the ink reciprocates in the resistance applying portions 42a and 42b and 44a and 44b. In this case, the resistance of the ink flow decreases in the right direction in FIGS. 2 and 3, and the resistance increases in the reverse direction (left direction). For this reason, the ink flows in the direction of decreasing resistance due to the continuous volume fluctuation of the cavities 46 and 48, and functions as a check valve.
[0039]
If a plurality of resistance applying portions are provided on the upstream side and the downstream side of the cavity portions 46 and 48, the function of the pump is improved, but one resistance applying portion may be provided on one of the upstream and downstream sides. If two or more are provided on both sides of the cavity portions 46 and 48 as in this embodiment, the function of the pump is further improved.
[0040]
When the drive units 54 and 56 are driven, the diaphragms 50 and 52 move forward and backward into the cavity units 46 and 48, and the volumes of the cavity units 46 and 48 change. For this reason, the ink flows toward the ink discharge port 28. If the movement range of the diaphragms 50 and 52 at this time is regulated to be constant, the amount of ink ejected by one reciprocation of the diaphragms 50 and 52 becomes constant. Therefore, by controlling the number of drive pulses applied to the drive units 54 and 56, the supply amounts of the first and second inks can be controlled with high accuracy.
[0041]
Thus, if the ink discharge amount by one reciprocation of the drive units 54 and 56 is made constant, the ink discharge amounts by the respective ink discharge pumps 24 and 26 are proportional to the number of times the drive units 54 and 56 are driven. . Here, the control unit 62 (FIG. 1) controls the driving units 54 and 56 so that the total supply amount S ₀ of the first and second inks supplied from the ink passages 20 and 22 is always constant. .
[0042]
The control unit 62 includes a calculation unit 64 and drivers 66 and 68 as shown in FIG. The calculator 64 calculates the mixing ratio (S ₁ / S ₂ ) of the first and second inks based on the density signal (image signal). Here, the supply amounts S ₁ and S ₂ of the first and second inks are determined so that the sum (S ₁ + S ₂ ) becomes a constant amount S ₀ . The drivers 66 and 68 drive the drive units 54 and 56 so that the supply amounts of the flow paths 20 and 22 become S ₁ and S ₂ .
[0043]
The drive units 54 and 56 are driven by pulses, and the number of times of opening and closing the diaphragms 50 and 52 is controlled by the number of pulses, and as a result, the flow rates S ₁ and S ₂ can be controlled. In this case, it is assumed that the flow resistance of the ink flow paths 20 and 22, the ink supply pressure, the opening and closing conditions of the diaphragms 50 and 52, etc. are the same, and the amount of ink ejected by one pulse is the same. By controlling so that the total number of drive pulses of the drive units 54 and 56 becomes constant, the total flow rate S ₀ = S ₁ + S ₂ can be managed constant.
[0044]
As described above, the image recording head 16 is obtained by alternately stacking substrates and partition plates. As shown in FIG. 2, an ink discharge port 28, ink flow paths 20, 22 and ink discharge pumps 24, 26 corresponding to one pixel are formed on each substrate. Here, the ink discharge ports 28 of each substrate are arranged on a straight line orthogonal to the traveling direction of the print paper 12. In this case, the interval between the adjacent ink discharge ports 28 matches the pixel interval of the recorded image. Accordingly, the total thickness of one substrate and one partition matches the pixel interval.
[0045]
As described above, the first and second inks whose flow rates are controlled by the ink discharge pumps 24 and 26 are discharged in a continuous flow from the ink discharge port 28 where the first and second flow paths 20 and 22 merge. Then, the ink is continuously applied to the print paper 12 facing and close to the ink discharge port 28. At this time, since the total discharge flow rate S ₁ + S ₂ = S ₀ is managed by the number of drive pulses, the ink can be applied to the print paper 12 smoothly and stably. In this case, as shown in FIG. 2, the first and second inks are applied as laminar flows that do not mix with each other and are not disturbed.
[0046]
Here, the laminar flow includes a flow in a mixed state only in the vicinity of the boundary between the first and second inks. The first and second inks may be mixed uniformly, but by forming a laminar flow in this way, the image surface formed on the print paper 12 is covered with one of the inks (here, the first ink). be able to. In addition, image quality can be improved by using any one of the inks (here, the second ink) as an ink that is familiar to the undercoat layer of the print paper 12.
[0047]
A large number of first and second ink flow paths 20 and 22 and ink discharge pumps 24 and 26 are arranged in parallel in the width direction (direction perpendicular to the moving direction) of the print paper 12, and therefore correspond to each pixel. An image can be formed by controlling the ink discharge pumps 24 and 26 by the respective density signals (image signals). In this case, the ink discharge port 28 can be made to face the print paper 12 independently for each pixel. It is also possible to open these ink ejection openings 28 in slits communicating with the width direction of the print paper 12 and transfer ink liquid from the slits to the print paper 12 to be applied.
[0048]
In the image recording head 16 configured as described above, fine bubbles may be included in the ink guided from the ink tanks 30 and 32 to the image recording head 16. When these bubbles enter the ink discharge pumps 24 and 26, they tend to adhere to the inner wall surfaces of the ink flow paths 20 and 22. In particular, in the resistance applying portions 42a, 42b, 44a, and 44b, the shape of the inner wall surface changes in a complicated manner, and the ink flow path area changes suddenly, resulting in disturbance of the ink flow. Air bubbles are easily attached.
[0049]
Therefore, in this embodiment, the hydrophilic treatment P is performed in the vicinity of the resistance applying portions 42a, 42b, 44a, 44b. That is, hydrophilic treatment was applied to the plane B, which is a portion where bubbles are likely to adhere. Although FIG. 4 shows a cross section of one resistance applying portion 42a, the other resistance applying portions 42b, 44a, and 44b have the same structure, and it goes without saying that the hydrophilic treatment is performed in the same manner.
[0050]
Here, the hydrophilic treatment can be performed by forming a hydrophilic resin film on the ink contact surface. As such a hydrophilic resin, nylon resin, polyvinyl alcohol resin and the like are suitable. The hydrophilic treatment can also be performed by applying a surfactant. The hydrophilic treatment may be applied to the slope A or the entire inner wall surface of the resistance applying portion 42a instead of being applied only to the plane B of the resistance applying portion 42a, or the ink flow path 20 including the resistance applying portions 42a and 42b. A hydrophilic treatment may be applied to the entire inner wall surface.
[0051]
According to this embodiment, even if air bubbles mixed in the ink enter the ink flow paths 20 and 22 and pass through the resistance applying portions 42a, 42b, 44a, and 44b, the air bubbles in the resistance applying portions 42a, 42b, 44a, and 44b, in particular, Since the hydrophilic treatment is applied to the plane B where the air bubbles are likely to adhere, bubbles do not adhere to the plane B and are smoothly discharged. For this reason, bubbles are unlikely to remain particularly near the cavity portions 46 and 48, and the pump efficiency is not lowered.
[0052]
[Other Embodiments]
FIG. 5 is an enlarged cross-sectional view of a resistance applying portion according to another embodiment. The resistance imparting portion 142 is formed by a curved surface that smoothly continues the inner wall surface in the ink transport direction. That is, the inner wall surface is a smooth curved surface so that the shape does not change in a complicated manner, in other words, the curvature radius of the inner surface is not changed rapidly.
[0053]
According to this embodiment, the curved surface R1 is formed at the corner of the wall surface B rising from the inner wall surface of the ink flow path 120, and the throat edge (the portion where the plane B and the inclined surface A intersect) is not an edge shape and is a smooth curved surface R. ₂ and a curved surface R ₃ is formed at the corner where the slope A and the inner wall surface of the ink flow path 120 intersect. For this reason, it becomes difficult for bubbles to adhere to these corners and edges. Therefore, it is difficult for bubbles to remain in the cavity, and the pump efficiency is not reduced.
[0054]
[Other Embodiments]
FIG. 6 is an enlarged cross-sectional view of a resistance applying portion according to another embodiment. The resistance applying portion 242 has a rising angle β of the slope Ba rising from the upstream side toward the throat where the ink flow path cross-sectional area is minimum, and a rising angle α of the slope A rising from the downstream side toward the throat. And the following relational expression: 0 <β <α;
[0055]
According to this embodiment, since the upstream slope Ba is inclined downstream toward the throat, bubbles are less likely to adhere to the slope Ba. That is, by making the shape not having a wall that intersects perpendicularly with respect to the ink flow direction in the ink flow path 220, adhesion of bubbles is prevented.
[0056]
[Other Embodiments]
FIG. 7 is an enlarged cross-sectional view of a resistance applying portion according to another embodiment. The resistance applying unit 342 is a combination of the embodiments shown in FIGS. That is, as in the embodiment of FIG. 6, the angles β and α rising from the inner wall surface of the ink flow path 320 toward the throat have slopes Ba and A set so that 0 <β <α, The corner where the ink flow path 320 and the slopes Ba and A intersect and the edge of the throat where the slope Ba and A meet are curved surfaces R ₁ , R ₃ and R _2, and the slope Ba facing the upstream side is subjected to hydrophilic treatment P. Is.
[0057]
According to this embodiment, the advantages of the embodiments shown in FIGS. 4 to 7 can be used in combination with different resistance applying portions in one ink discharge pump 24, 26. However, in order to prevent an increase in the number of manufacturing steps, the resistance application with the same structure is possible. It is better to use the part.
[0058]
Further, all the resistance applying portions in each of the ink discharge pumps 24 and 26 may be configured to prevent bubble adhesion as shown in FIGS. 4 to 7, but only some of the resistance applying portions prevent this bubble adhesion. You may provide the structure of.
[0059]
【The invention's effect】
According to the first aspect of the present invention, the ink flow path in which the non-image forming ink and the image forming ink are merged at the merging portion and ejected from the ink ejection port provided for each pixel, and the ink that applies a constant pressure in the ink delivery direction Between the supply pump and the upstream side of the cavity portion provided in the ink flow path and between the cavity portion and the merging portion, a resistance applying portion having no movable portion is provided, and these resistance applying portions have conductance in the ink transport direction. align the smaller orientation to a large reverse direction, merging these inks while controlling for each pixel based on the discharge amount of the non-image-forming ink and the image forming ink on the image signal so that these total flow rate is substantially constant A liquid transport device for an image recording head that is controlled so as to be joined as a continuous flow, discharged from an ink discharge port as a continuous flow, and transferred as a continuous fluid to an image receptor Et al., Improve the efficiency of the pump, it is possible to form an image while discharging a continuous stream is combined with different ink.
[0060]
In particular, since the hydrophilic treatment is applied to the vicinity of the inner wall surface of the resistance imparting portion, it is difficult for bubbles to adhere to the vicinity of the resistance imparting portion, and the pump efficiency at the time of discharging the liquid is prevented from decreasing due to the adhesion of the bubbles Can do. Further, since the resistance applying portion does not have a movable portion, it can be easily manufactured, and for example, it can be manufactured using a manufacturing method of a micromachine.
[0061]
According to the invention of claim 2, since the inner wall surface of the resistance imparting portion is formed with a curved surface that smoothly continues in the liquid transport direction, it is difficult for bubbles to adhere to the inner wall surface. Similar effects can be obtained.
[0063]
In order to change the volume of the cavity part, the wall of the cavity part may be vibrated by the drive part (claim 3 ). However but it may also a part of the wall as a diaphragm.
[0064]
This liquid transport device is used for an image recording head such as a printer. In this case, the liquid transport device is used to control the amount of non-image forming ink and image forming ink supplied to the ink discharge ports provided for each pixel. To do. Also a non-imaging ink and the image forming ink flowed case forms a concentration or / and color of ink corresponding to the image signal, which is transferred to the image receptor, and total flow rate at this time is substantially constant since you like to become the transfer of ink to the image receptor you stable.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of an image recording head. FIG. 3 is an explanatory view of an ink discharge pump. FIG. 5 is a view showing another embodiment of the resistance applying portion. FIG. 6 is a view showing another embodiment of the resistance applying portion. FIG. 7 is a view showing another embodiment of the resistance applying portion.
12 Print Paper as Image Receptor 16 Image Recording Head 20, 120, 220, 320 First Ink Channel 22 Second Ink Channel 24, 26 Ink Ejection Pump 28 Ink Ejection Ports 42a, 42b, 44a, 44b, 142,242,342 resistance application portion 46, 48 cavity 50, 52 diaphragm 54, 56 drive unit A, Ba slope B plane P hydrophilic treatment R _1, R _2, R ₃ curved

Claims (3)

Liquid used in an image recording head for forming an image by changing the volume of a cavity portion of the ink discharge pump by pulse driving an ink discharge pump provided in the middle of the ink flow path and transferring the ink to an image receptor In transportation equipment,
An ink flow path in which non-image forming ink that does not substantially form an image after drying and image forming ink that substantially forms an image after drying are merged at a merging portion and ejected from an ink ejection port provided for each pixel; An ink supply pump that applies a constant pressure to the ink in the ink flow path, and a direction in which the conductance increases in the ink flow path upstream of the cavity portion and between the cavity portion and the merge portion. A resistance imparting portion having no movable portion provided in alignment with the transport direction and having a hydrophilic treatment in the vicinity of the inner wall surface thereof, and the non-image forming ink and the image forming ink ejected by the ink ejection pump to the pixels merging of these inks in the joint portion and the discharge flow rate while controlling the number of drive pulses based on the image signal so that these total flow rate is substantially constant Liquid transfer apparatus characterized by comprising a control unit for transferring a fluid continuous with the image receptor is discharged as a continuous flow from the ink discharge ports. Liquid used in an image recording head for forming an image by changing the volume of a cavity portion of the ink discharge pump by pulse driving an ink discharge pump provided in the middle of the ink flow path and transferring the ink to an image receptor In transportation equipment,
An ink flow path in which non-image forming ink that does not substantially form an image after drying and image forming ink that substantially forms an image after drying are merged at a merging portion and ejected from an ink ejection port provided for each pixel; An ink supply pump that applies a constant pressure to the ink in the ink flow path, and a direction in which the conductance increases in the ink flow path upstream of the cavity portion and between the cavity portion and the merge portion. The inner wall surface is provided in the transport direction, and the inner wall surface is formed of a curved surface that is smoothly continuous in the ink transport direction. The resistance applying portion does not have a movable portion, and the image is ejected by the ink ejection pump to the pixels. the discharge flow rate of the non-forming ink and the image forming ink these while controlling the number of drive pulses based on the image signal so that these total flow rate is substantially constant Liquid transfer apparatus characterized by comprising a control unit for transferring the different inks as fluid is discharged as a continuous flow was continuous with the image receptor from the ink discharge port are merged in the merging section.   The liquid transport device according to claim 1, wherein a movable wall driven by a driving unit is provided in the cavity unit, and the volume of the cavity unit is changed by the movement of the movable wall.

Images