JPH09193414A - Liquid holding and supplying apparatus and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart negative pressure generation function for preventing a liquid leak without using a porous element by providing a means for detecting the fluctuations of the liquid pressure in a closed supply passage by the consumption of the liquid and a means for driving an opening and closing means on the basis of the fluctuation value detected by the detection means. SOLUTION: An opening and closing mechanism 5 performing the opening and closing of a closed supply passage 4 is provided on the way of the closed supply passage 4 and the fluctuations of negative pressure generated by the consumption of ink of a recording head 1 are detected by a detection means 6 to be transmitted to the opening and closing mechanism 5. The opening and closing mechanism 5 is driven corresponding to the fluctuation detection signal by the detection means 6 to perform opening and closing operation to always keep the negative pressure of the ink in the closed supply passage 4 constant. When ink comes into contact with the atmosphere by the capillary force of a liquid passage through a meniscus at the ink emitting part 1A of the receiving head 1 in the ink supply passage 4 and emitting operation is not performed, the supply passage 4 is held to a closed state and an ink leak acts in a direction reducing the vol. of ink to hold the ink to negative pressure by the atmosphere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid holding / supplying apparatus and a liquid holding / supplying method therefor, and more specifically, it is capable of holding a liquid so that it can be held and supplying the liquid to the outside while maintaining a predetermined liquid pressure. The present invention relates to a liquid holding / supplying device and a holding / supplying method thereof.

[0002]

2. Description of the Related Art Conventionally, in an ink jet recording apparatus or the like, ink, which is a recording liquid, is supplied from a supply source to a recording element which ejects ink to perform recording. By the way, such a recording element generally has a downward or lateral ink ejection port, and an ink container for supplying ink to these is usually arranged above the recording element so that the ink ejection port always has a liquid. Since static pressure is applied by the ink, a pressure that is more negative than the outside air is generated around the ink ejection port for the purpose of preventing ink leakage from the ejection port.

Such negative pressure utilizes the capillary force generated by a thin liquid path, and a sponge-like continuous porous body as shown in FIG. 7 is loaded in the container to hold the ink in the porous body. Along with the ink holding function, ink leakage has been prevented. In FIG. 7, 101 is the ink container (ink tank), 102 is an ink supply port to a recording element (not shown), 103 is an atmosphere communication port, and 104
Is an ink holding member made of, for example, urethane foam, which is a continuous porous body loaded in the container 101.

[0004]

However, in the liquid holding / supplying device used as the ink supplying device as in the above-mentioned conventional example, a continuous porous body such as urethane foam is internally provided for holding / supplying the liquid. Is loaded into
Such a porous body must have good wettability so as not to be deteriorated by the liquid contained in the ink or the like, and the material to be selected is limited. Further, since the negative pressure generated by the porous body depends on the diameter of the pores when it is generated, technical control for generation is not easy to obtain a stable negative pressure, It also affects manufacturing costs.

The object of the present invention is to pay attention to the above-mentioned conventional problems, and to prevent liquid leakage without using a porous body such as urethane foam which is not chemically stable. Liquid holding with negative pressure generation function for
It is to provide and propose a supply device and a holding / supplying method thereof.

[0006]

To achieve the above object, a liquid holding / supplying device according to the present invention includes a closed supply passage which is kept closed except for a liquid consuming port of a liquid consuming portion, and a closed supply passage. A liquid storage portion that stores a liquid to be supplied to a supply path, an opening / closing means that is disposed in the closed supply path and opens and closes the closed supply path, and a hydraulic pressure fluctuation in the closed supply path due to consumption of the liquid. And a drive means for driving the opening / closing means based on the fluctuation value detected by the pressure fluctuation detecting means.

Further, the liquid holding / supplying method is such that, when the liquid in the closed supply path which is kept closed except the liquid consuming port of the liquid consuming portion is consumed from the liquid consuming port, Detects fluid pressure fluctuations that occur in the closed supply path,
Open the closed supply path based on the detected hydraulic pressure fluctuation value,
In order to return the fluctuated hydraulic pressure to a predetermined hydraulic pressure, the amount of the liquid consumed from the liquid container is replenished.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. Prior to the description, first, the basic principle of the configuration and the method according to the present invention will be described with reference to FIG. To do.

Here, 1 is a recording head for ejecting a liquid (ink of the recording liquid in the case of this example) toward the recording material 2, and 3 is a liquid accommodating and accommodating ink for supplying to the recording head 1. Part (ink tank). Ink tank 3
From the recording head 1 to the recording head 1 through the ink supply path 4.
Although the ink is in contact with the atmosphere through the meniscus due to the capillary force of the liquid passage in the ink ejecting section 1A of FIG. The ink is passively kept at a negative pressure below the atmospheric pressure because it acts to reduce the volume of ink held.

Therefore, in the present invention, an opening / closing mechanism 5 for opening and closing the closed supply passage 4 is provided in the middle of an ink (liquid) supply passage (hereinafter referred to as a closed supply passage) 4 which is kept closed when not supplied. The opening / closing mechanism 5 detects the negative pressure fluctuation generated by the ink consumption of the recording head (liquid consuming portion) 1 by the detecting means 6 and transmits it. Then, in response to the fluctuation detection signal from the detection means 6, the opening / closing mechanism 5 is driven as shown by the arrow D (here, by the signal from the detection means 6) to perform the opening / closing operation, whereby the ink in the closed supply path 4 is discharged. The negative pressure is always kept constant. Reference numeral 7 denotes a liquid (ink) that fills a space from the liquid storage unit 3 to the liquid consuming unit 1 via the liquid supply path 4.
Reference numeral 8 is an atmosphere opening portion of the liquid storage portion 3.

FIG. 2 shows a state in which the negative pressure in the closed supply path 4 fluctuates due to the opening / closing operation of the above-mentioned opening / closing mechanism 5. Here, the abscissa axis represents a time elapsed state when ink (liquid) is consumed in accordance with the ejection, and the ordinate axis represents a negative pressure fluctuation state in the closed supply path 4, which is a level a.
The ink held at the initial negative pressure level of is lowered to the negative pressure level of b each time the ink is ejected, but each time the opening / closing mechanism 5 opens the closed supply path 4, the ink returns to the level a, and again. It is closed. Then, the negative pressure fluctuation due to the repetition of such an operation is shown as a zigzag curve C in which the ripple width d is maintained.

[Embodiment 1] FIG. 3 shows a first embodiment according to the present invention. In this example, reference pressure setting means corresponding to the initial negative pressure a shown in FIG. 2 is provided, and by comparing the pressure with the negative pressure generated in the closed supply path 4, the opening / closing mechanism is opened / closed by the differential pressure. It is the one. Here, 11 is a pressure detection unit for detecting a negative pressure in the closed supply path 4, and in this example, the closed pressure chamber 11A communicating with the closed supply path 4 and the diaphragm 11 displaced by the pressure in the pressure chamber 11A.
The pressure detection unit 11 is configured by B and the strain gauge 11C which is in contact with the diaphragm 11B and detects the displacement of the diaphragm 11B. Further, reference numeral 12 is a reference pressure generating portion including a reference pressure generating chamber 12A for generating the reference pressure, a diaphragm 12B for detecting the reference pressure, and a strain gauge 12C.

Pressure detector 11 and reference pressure generator 12
Each of the pressures detected in 1 is guided to the comparator 13, and the differential pressure is output to the amplifier 14. Here, DC power supply 1
When a signal having a working force of, for example, 1 to 4 kgf is obtained by supplying a voltage of 24 V from 5 to the amplifier 14, the opening / closing mechanism 5 configured as a solenoid valve is driven by such a working force. The solenoid valve 5 is opened to establish communication with the liquid storage portion 3, and the hydraulic pressure supplied to the recording head (liquid consumption portion) 1 is returned to the initial negative pressure a. Note that such an operation is repeated every time the liquid consuming unit 1 consumes the liquid 7 in the closed supply path 4 and drops to the level b.

In the first embodiment described above, the reference pressure generator 12
Is constituted by the reference pressure chamber 12A, the diaphragm 12B, and the strain gauge 12C. However, as long as it is configured to supply the electric signal corresponding to the reference pressure to the comparator 13, the configuration of the reference pressure generator 12 is limited to the above. It goes without saying that it is not a thing.

[Embodiment 2] FIG. 4 is a second embodiment of the present invention in which the reference pressure generator 12 is constructed so that the reference pressure is variably set in relation to the atmosphere. That is, the reference pressure generation chamber 12A according to the present embodiment has a communication pipe 12D that communicates with the atmosphere, and the strain gauge 12C provided on the diaphragm 12B is configured so that pressure is always applied to atmospheric pressure. . Note that the other configurations are the same as those in the example shown in FIG. According to this embodiment, the reference pressure that is set to be variable by the atmospheric pressure is constantly compared with the generated pressure in the closed supply path 4, the differential pressure reaches a predetermined value, and the solenoid valve 5 is opened. The negative pressure adjustment described above is performed when the acting force for

[Third Embodiment] Next, a third embodiment of the present invention will be described with reference to FIG. Here, 20 is a negative pressure control unit that detects the negative pressure fluctuation in the closed supply path 4 and controls the opening / closing of the opening / closing mechanism, and is provided between the liquid storage unit 3 and the liquid consuming unit (recording head) 1. Has been. Reference numeral 21 denotes a thick movable plate that is displaced according to negative pressure fluctuations in the closed supply path 4, reference numeral 22 denotes a corrugated movable plate supporting portion that keeps the movable plate 21 displaceable, and the movable plate supporting portion 22 is a film-shaped movable plate supporting portion. It is made of thin-walled flexible material. Reference numeral 23 is a lever member swingably supported by a fulcrum 23A, and the lever member 23 is a transmission lever portion 2 that is in contact with substantially the center of the movable plate 21.
3B and a drive lever portion 23C for opening and closing the valve, the transmission lever portion 23B is set longer than the drive lever portion 23C in this example so as to facilitate the opening and closing operation. Reference numeral 24 is a coil spring for valve return, 25A is a ball valve element, and 25B is a valve seat for communicating the control chamber 20A of the negative pressure control section 20 with the liquid storage section 3 side.

In the liquid holding / supplying device having such a structure, the exposed surface of the movable plate 21 is in contact with the atmosphere, while the inner surface thereof is in contact with the liquid in the control chamber 20A, so that the supply is closed. When the negative pressure in the passage 4 becomes larger than the predetermined pressure,
The movable plate 21 is displaced to the control chamber 20A side. Then, the lever member 23 is swung around the fulcrum 23A in accordance with the displacement, and the ball opening / closing valve body 25A is lifted from the valve seat 25B against the spring force of the coil spring 24, so that the negative pressure control unit 20 is lifted. It communicates with the liquid storage portion 3 side. Therefore, in order to return the negative pressure in the control chamber 20A, that is, the closed supply path 4 to the predetermined pressure, the liquid (ink) is supplied from the liquid storage portion 3 and when the negative pressure reaches the predetermined pressure, the negative pressure control chamber 20A. Is cut off from the liquid storage portion 3, and the above operation is repeated.

[Embodiment 4] FIG. 6 shows a fourth embodiment of the present invention. In this example, by incorporating the negative pressure control unit 20 in the liquid storage unit 3 and integrating these, it is possible to contribute to space saving, and further, the assembling is easy and the negative pressure control in the closed supply path is surely performed. It was made to be seen. The integrated liquid holding / supplying member 30 according to the present example has a substantially rectangular box shape as a whole as shown in this figure, and is directly attached / detached to / from the liquid consuming portion (recording head) 1 that consumes liquid.

That is, in FIG. 6, 31 is the liquid storage portion, 32 is a partition wall that partitions the liquid storage portion 31 from the negative pressure control portion 20, and 33 is a partition wall 32 that is provided with the liquid storage portion 31. It is a valve seat for communicating with the negative pressure control chamber 20A side. An atmosphere communication hole 34 is provided in the upper portion of the liquid storage portion 31, and inside the atmosphere communication hole 34, in order to prevent liquid (ink) leakage from the liquid storage portion 31 during handling such as transportation. A hydrophobic film 35 that has been made liquid repellent is provided. Reference numeral 36 is a liquid supply port provided in the lower portion of the negative pressure control chamber 20A, and 37 is a rubber plug that seals the liquid supply port 36. The rubber plug 37 is attached when the apparatus 30 is attached to the liquid consumption unit 1 such as the recording head. An ink circuit is formed by inserting a hollow needle (not shown) into.

Further, in the case of the present embodiment, the movable plate 21 is swingably held via the film-shaped support portion 22 and the hinge portion 22A, and the swing motion thereof causes the valve body portion via the lever member 23. The valve seat 33 is opened and closed by means of 25. 3
Reference numeral 6 denotes a film-shaped protective film provided on the outside of the movable plate 21 of the negative pressure control unit 20, which not only prevents the movable plate 21 from being displaced by an unnecessary external force but also keeps the area of the movable plate 21 large. Although an appropriate actuating force is obtained according to a slight negative pressure fluctuation, it is not always necessary to provide the protective film 36 when there is no risk of an external force acting on the movable plate 21. Absent. It is necessary that the protective film 36 does not directly hinder the displacement of the movable plate 21 so that the atmospheric pressure directly acts on the outside of the movable plate 21.

The most characteristic feature of the present embodiment is that the flat bellows (protective film) 36 is provided on the outer wall of the movable plate 20 so that the movable plate 20 can have a large area while saving space. The advantage is that a strong lever operating force can be obtained.

According to experiments by the authors, a weak pressing force of 10 to 30 gf was obtained by a flat bellows obtained by heat-sealing a flat plate of about 20 mm ² and an unstretched polypropylene sheet of t = 0.1 mm. By operating this flat bellows under 1 atm and giving a lever ratio of 3 to 5 times to amplify the bellows operating force, it is possible to obtain a lever operating force of 600 to 1000 g as a valve opening and closing force. In the case of recording element, 40
A valve mechanism capable of withstanding a negative pressure of 70 mmAq was constructed. Also, the ripple of negative pressure generated at this time is about 10 m.
It was within mAq, and was at a level with no practical problems as a liquid supply device for an inkjet recording element.

[0023]

As described above, according to the present invention, a closed supply passage which is kept closed except for the liquid consumption port of the liquid consuming portion, and a liquid which contains the liquid to be fed to the closed supply passage. An accommodating part, an opening / closing means arranged in the closed supply path to open / close the closed supply path, a pressure fluctuation detecting means for detecting a hydraulic pressure fluctuation in the closed supply path due to consumption of the liquid, and the pressure Since the driving means drives the opening / closing means on the basis of the fluctuation value detected by the fluctuation detecting means, it is possible to supply the liquid without loading the continuous porous body such as urethane foam in the liquid container as in the conventional case. Therefore, it is possible to maintain the negative pressure necessary for the closed supply path, and it is possible to freely set the fluctuation range of the negative pressure.

Further, the number of times of opening and closing can be reduced by setting the volume fluctuation range of the closed supply path to be large by configuring the closed supply path to respond to a slight negative pressure fluctuation. On the contrary, it is also possible to change the setting element according to the purpose of use, such as setting the fluctuation range of the negative pressure in order to reduce the number of times the opening / closing mechanism is operated.

Since it is not necessary to provide a liquid negative pressure holding member having chemically unstable physical properties such as urethane foam, it is possible to increase the degree of freedom in the selection area of the liquid used.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a basic configuration according to the present invention.

FIG. 2 is a graph showing, in principle, an example of a negative pressure fluctuation of the supply liquid that occurs over time according to the present invention.

FIG. 3 is a block diagram showing a configuration according to a first exemplary embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration according to a second exemplary embodiment of the present invention.

FIG. 5 is a sectional view showing a structure according to a third embodiment of the present invention.

FIG. 6 is a sectional view showing a configuration according to a fourth exemplary embodiment of the present invention.

FIG. 7 is an explanatory diagram schematically showing a configuration of a liquid storage section according to a conventional example.

[Explanation of symbols]

 1 Recording Head (Liquid Consumption Section) 1A Ink Ejection Section 3 Liquid Storage Section (Ink Tank) 4 Liquid (Ink) Supply Path (Closed Supply Path) 5 Opening / Closing Mechanism (Solenoid Valve) 6 Negative Pressure Fluctuation Detection Means 7 Liquid (Ink) 11 Pressure Detection Section 11A Pressure Chamber 11B, 12B Diaphragm 11C, 12C Strain Gauge 12 Reference Pressure Generation Section 12A Reference Pressure Generation Chamber 13 Comparator 14 Amplifier 20 Negative Pressure Control Section 20A Negative Pressure Control Room 21 Movable Plate 22 Movable Plate Support Section 23 Lever member 24 Coil spring 25A Ball valve body 25B Valve seat 30 Liquid holding / supplying member 31 Liquid containing portion 33 Partition wall 34 Atmosphere communicating hole 36 Protective film

Claims (14)

[Claims] 1. A closed supply path, which is kept closed except for the liquid consumption port of the liquid consumption section, a liquid storage section for storing a liquid to be supplied to the closed supply path, and a closed supply path. An opening / closing unit that opens and closes the closed supply path, a pressure fluctuation detection unit that detects a liquid pressure fluctuation in the closed supply path due to the consumption of the liquid, and a fluctuation value that is detected by the pressure fluctuation detection unit. A liquid holding / supplying device comprising: a driving unit that drives the opening / closing unit. 2. The liquid holding / holding device according to claim 1, wherein the liquid is a recording liquid, and the liquid consuming portion is a recording head that discharges the recording liquid from a recording liquid discharge port to perform recording. Supply device. 3. The liquid holding / supplying device according to claim 1, wherein the liquid storage section has an atmosphere communication section that communicates with the atmosphere. 4. The liquid is replenished to the closed supply passage for each open passage by the opening / closing means in an amount corresponding to the amount of the liquid consumed by the liquid consuming portion.
The liquid holding / supplying device according to any one of items 1 to 3. 5. The pressure fluctuation detection means is means for comparing a hydraulic pressure in the closed supply passage with a predetermined reference pressure to detect a differential pressure, and the driving means is driven by a driving force generated by the differential pressure. The liquid holding / supplying device according to any one of claims 1 to 4, wherein the opening / closing means is driven. 6. The liquid holding / supplying device according to claim 5, wherein the predetermined reference pressure is atmospheric pressure. 7. The differential pressure amplifying means for amplifying the differential pressure is provided, and the driving means generates the driving force based on the differential pressure amplified by the differential pressure amplifying means. 5. The liquid holding / supplying device according to 5 or 6. 8. When the liquid in the closed supply passage, which is kept closed except for the liquid consumption opening of the liquid consuming portion, is consumed from the liquid consumption opening, the liquid is consumed to generate in the closed supply passage. Detects hydraulic pressure fluctuations, opens the closed supply path based on the detected hydraulic pressure fluctuation value, and replenishes the amount of liquid consumed from the liquid storage unit in order to return the changed hydraulic pressure to the prescribed hydraulic pressure. A liquid holding / supplying method characterized in that 9. The liquid holding / holding device according to claim 8, wherein the liquid is a recording liquid, and the liquid consuming portion is a recording head that discharges the recording liquid from a recording liquid discharge port to perform recording. Supply method. 10. The liquid holding / supplying method according to claim 8, wherein the liquid storage section has an atmosphere communication section that communicates with the atmosphere. 11. The liquid according to claim 8, wherein the closed supply path is replenished with liquid for each open path by the opening / closing means according to the amount of liquid consumed by the liquid consuming portion. The liquid holding / supplying method described in the section. 12. The differential pressure is detected by comparing the hydraulic pressure in the closed supply passage with a predetermined reference pressure by a pressure detection means, and the opening / closing means is driven by the driving force generated by the differential pressure. The liquid holding / supplying method according to any one of claims 8 to 11. 13. The liquid holding / supplying method according to claim 12, wherein the predetermined reference pressure is atmospheric pressure. 14. The differential pressure amplifying means for amplifying the differential pressure is provided, and the driving means generates the driving force based on the differential pressure amplified by the differential pressure amplifying means. 12. The liquid holding / supplying method according to 12 or 13.