JP2000313118A - Ink jet recording head, ink jet recording apparatus and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower the resistance of a seal liquid at the time of the emission of ink. SOLUTION: A head 10 is equipped with an ink emitting orifice 12 provided to an ink emitting surface, an emitting chamber 16 provided with an emitting means 14, an ink sump 18 supplying ink to the emitting chamber 16 and a seal liquid drawing-in means 24 for drawing in a seal liquid so that the first seal liquid 22A positioned at the ink emitting orifice 12 and the second seal liquid 22B positioned in the periphery of the ink emitting orifice 12 are interrupted and the seal liquid drawing-in means 24 is constituted by forming composite members different in the coefficient of thermal expansion into a bimorph structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head, an ink jet recording apparatus, and an ink jet recording method, and more particularly, to an ink jet recording head and an ink jet recording apparatus for sealing an ink discharge port for discharging ink with a sealing liquid. And an ink jet recording method.

[0002]

2. Description of the Related Art In a conventional ink jet recording apparatus, it is a major problem to prevent nozzle clogging due to drying and thickening of ink during non-operation. Various ink materials have been developed to solve this problem, but it is still difficult to reduce evaporation of the ink solvent. In a commercially available ink jet recording apparatus, at the time of non-printing or during a long period of non-operation, the nozzle and the outside air are shielded by a capping means made of resin or the like to delay the drying of the ink. However, this capping means
In order to more effectively increase the airtightness of the nozzle, complicated procedures and devices are required. Also, with this capping means, the nozzle cannot be completely shielded from the air, and during storage, the drying and thickening of the ink inside the nozzle gradually progress, which may cause nozzle clogging. is there.

[0003] Maintenance for the above-mentioned clogging recovery is disadvantageous. That is, in a commercially available ink jet recording apparatus, various maintenance operations are required in order to recover clogging of the nozzle due to long-term suspension. For example, in the recovery by a vacuum operation in which a clog in the nozzle is pulled out from the outside of the nozzle by a negative pressure,
Since a pump and an absorber for waste ink are required in the apparatus, the apparatus is complicated and large, and the cost of the apparatus is increased. Further, since the nozzle surfaces are collectively made to have a negative pressure, a large amount of ink is also sucked out from nozzles where no clogging occurs and discarded, thereby increasing running costs. In addition, in the case where the recovery is performed by repeating the dummy jet operation and the wiping operation, the device becomes complicated, for example, a mechanism for moving the head to the maintenance position or pressing a member such as a blade against the head surface to perform a sliding motion is required. Cost increases. After a long-term suspension of the inkjet recording apparatus, a maintenance operation is performed by combining these operations before printing, and a waiting time before printing and noise due to the maintenance operation are generated, which is disadvantageous to the user.

As means for avoiding the problem caused by clogging after a long period of suspension, there is a method for avoiding clogging due to liquid capping as disclosed in Japanese Patent Application Laid-Open No. 52-104130. That is, a method is known in which a seal liquid insoluble in ink and a means for forming a film of the seal liquid are used to seal the ink discharge port to shield the ink from air and prevent the ink from drying.

Japanese Patent Application Laid-Open No. 49-115548 discloses that a seal liquid and a wetting mechanism seal an ink discharge port when the printing apparatus is not operating, and a seal liquid supply path is provided by a switch provided in a seal liquid supply path during operation. A method for stopping the supply of the water is described.

However, these methods have a disadvantage that the resistance of ink discharge is high at the start of discharge because the seal liquid is separated on the surface but is substantially continuous with the surrounding seal liquid inside. are doing. When the temperature of the environment in which the printing apparatus is used becomes low, the viscosity of the seal liquid may increase, and in the worst case, there is a problem that ink cannot be ejected.

In view of such a problem, Japanese Patent Application Laid-Open No. 54-69
No. 436 discloses a method of forming and releasing a seal liquid film in order to improve the ejection stability of ink droplets in a sealing method using a seal liquid.

Japanese Patent Application Laid-Open No. Hei 5-177841 describes a method of sealing a nozzle with a seal liquid as needed, and a method of opening and closing a seal with a seal liquid in conjunction with carriage scanning.

However, in either method, switching between the state of being sealed by the sealing liquid and the state of being unsealed requires an external force such as opening and closing by a pump, an electromagnet, and a support, and the structure of the head is complicated. This leads to an increase in the size of the printing apparatus.

[0010]

As described above, in the conventional method of sealing a nozzle with a sealing liquid, the worst case is when the sealing liquid has a high resistance at the time of discharge and the viscosity of the sealing liquid increases due to an environment change. The case (1) has a disadvantage that ink cannot be ejected. In general, many non-volatile liquids having a low vapor pressure have a high kinematic viscosity due to a large molecular weight. Therefore, it is desirable to select a seal liquid having a high kinematic viscosity in order to make the seal liquid non-volatile for a longer period of time and maintain the sealing performance against clogging. Therefore, in order to adopt a specification that prevents clogging for a longer period of time, a sealing liquid having a high kinematic viscosity must be used, or the thickness of the sealing liquid must be increased, and the discharge resistance further increases. As a result, it becomes difficult to achieve both clogging prevention performance and discharge performance. If means for opening and closing the seal of the seal liquid is provided to avoid these problems, the apparatus becomes complicated and large.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the related art, and has as its object to provide an ink jet recording head and an ink jet recording capable of reducing the resistance of a seal liquid at the time of ink ejection. An apparatus and an inkjet recording method are provided.

[0012]

According to the first aspect of the present invention, there is provided an ink ejection port for ejecting ink, a sealing liquid for sealing the ink ejection port, and an input image signal. An ink ejection unit that ejects ink from the ink ejection port in response to the seal liquid, wherein the seal liquid located at the ink ejection port of the seal liquid and the seal liquid of the seal liquid located around the ink ejection port are separated. A seal liquid drawing means for drawing the seal liquid into the ink discharge port, wherein the seal liquid drawing means is configured by forming a composite member having a different coefficient of thermal expansion into a bimorph structure. Features.

That is, the seal liquid is supplied to the ink discharge port automatically or manually. When the ink ejection unit attempts to eject ink from the ink ejection port while the ink ejection port is sealed with the seal liquid, not only the seal liquid located at the ink ejection port due to the viscosity of the seal liquid, but also Also, the seal liquid located around the ink ejection port also tries to prevent ink ejection.

Therefore, in the present invention, the sealing liquid drawing means separates the sealing liquid positioned at the ink discharging port of the sealing liquid from the sealing liquid positioned around the ink discharging port of the sealing liquid. Withdraw liquid.

As described above, the seal liquid is drawn into the ink discharge port so that the seal liquid located at the ink discharge port and the seal liquid located around the ink discharge port are separated, so that the ink is discharged from the ink discharge port. In such a case, it is possible to eliminate the effect of preventing the sealing liquid positioned around the ink discharge port from discharging the ink, and to stably discharge the ink.

In particular, in the present invention, the composite member having a different thermal expansion coefficient has a bimorph structure to constitute the sealing liquid drawing means. Therefore, the operation amount of the sealing liquid drawing means can be increased, and the drawing can be controlled with a small amount of energy, that is, the sealing liquid drawing means can be largely operated with the same energy.

Here, the sealing liquid drawing means may include a heating means for heating the composite member, and the heating means may be the discharge means. Therefore, when there are a plurality of ink ejection ports, the sealing liquid can be drawn in and the ink can be ejected for each of the ejection ports.
The seal liquid can be drawn in without any loss, and the ink can be discharged in an optimum drawing state for each discharge port.

Here, a control means for controlling the ink discharge means and the seal liquid drawing means so that the drawing of the seal liquid and the discharge of the ink are performed within a predetermined basic discharge period. May be provided. As a result, the state in which the sealing liquid has been drawn is
The same state can be obtained every basic cycle. Therefore, the state of the ejected ink (e.g., amount, speed, etc.) can be made the same for each basic cycle, the size of the ink dots to be printed and the variation in the impact positions of the ink dots can be reduced, and the image quality can be improved. Can be improved.

The control means may control the ink discharge means so that the ink is discharged after a predetermined delay time from the input of the image signal.

Here, the ink jet recording apparatus is provided with the ink jet recording head according to claim 1 or 2. In the ink jet recording method of the ink jet recording apparatus, the sealing liquid is drawn in before the ink is ejected.

Further, the state in which the sealing liquid is drawn is maintained as in claim 7, and in this case, when the state in which the sealing liquid is drawn is maintained as in claim 8, the ink is discharged. A plurality of ejections may be performed. Therefore, it is possible to prevent the drawing operation every time the ink is ejected, and it is possible to shorten the ejection interval.

On the other hand, the ink jet recording apparatus may be provided with an ink jet recording head according to claim 3 or 4. In the ink jet recording method of the ink jet recording apparatus, the seal liquid may be drawn every time before the ink is ejected.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a basic configuration example of an ink jet recording head according to the present embodiment. As shown in FIG. 1, an ink jet recording head (hereinafter, may be simply referred to as “head”) 10 according to the present embodiment includes an ink ejection port 12 provided on an ink ejection surface and an ejection unit 14. The apparatus includes an ejection chamber 16, an ink reservoir 18 for supplying ink to the ejection chamber 16, and a seal liquid drawing unit 24. The ink is supplied to the head by an ink tank and an ink supply path (not shown) outside the head by an action caused by, for example, a capillary force or a pressure difference.

Here, the discharge port 12 and the discharge direction will be described.

FIG. 1 shows only one ink ejection port 12, but a plurality of ink ejection ports 12 may be provided on the ink ejection surface. Although FIG. 1 shows a state in which the ink ejection ports 12 are arranged in a horizontal direction for convenience, the ink ejection direction, that is, the arrangement direction of the recording head can be appropriately selected as desired. Is ejected in the direction of gravity (downward).

Next, an example of a system that can be used as output means will be described. That is, the ink ejection means 14 usable in the present embodiment includes ink ejection means 14 used in a conventional ink jet recording head, such as ink ejection means of a pressure type, a continuous flow type, an electrostatic suction type, or the like. The means 14 can be widely used, and a method of concentrating acoustic waves, pressure waves, and the like can also be used. As the discharge means 14 of the pressurizing method, a thermal ink jet method or a piezoelectric method can be used.

Next, the basic properties of a material that can be used as a sealing liquid will be described.

The seal liquid usable in the present embodiment seals the ink discharge ports 12 and
Has a function of shielding the ink from the air. The seal liquid that maintains such a function contains at least a component insoluble in the ink, is incompatible with the ink, and does not spontaneously emulsify with the ink.

Next, the compatibility between the sealing liquid and the ink will be described.

In order for the sealing liquid and the ink to be incompatible, specifically, the solubility of the sealing liquid in the ink is set to 0.1 in an environment where a head or a recording apparatus is used.
It is preferably at most 1% by weight.

Next, the non-volatility of the sealing liquid will be described.

Further, when the sealing liquid is non-volatile,
Ejection port 1 with sealing liquid, which does not evaporate while the head is at rest
This is preferable because no change occurs in the sealing state of No. 2. Non-volatile refers specifically to a vapor pressure of 0.1 mmHg or less under an environment where a head or a recording device is used.

Next, a preferred range of the kinematic viscosity of the sealing liquid will be described.

The kinematic viscosity of the seal liquid that can be used in the present embodiment is determined by setting the period for preventing clogging, the diameter of the discharge means 14 and the discharge port 12, the discharge frequency of the recording head, the thickness of the seal liquid, and the arrangement of the seal liquid. The kinematic viscosity can be widely used from low viscosity to high viscosity. However, in general, many non-volatile liquids having a low vapor pressure have a high kinematic viscosity due to a large molecular weight. For this reason, it is desirable to select a seal liquid having a high kinematic viscosity to maintain the sealing performance against clogging by making the seal liquid non-volatile for a longer period of time. Considering the desirable characteristics, the kinematic viscosity of the sealing liquid in the environment where the head or the recording apparatus is used is preferably in the range of 1 to 200 mm ² / s.

Next, a preferred range of the surface tension of the sealing liquid will be described.

The surface tension of the sealing liquid which can be suitably used in the present embodiment is in the range of 15 to 70 mN / m under the environment where the head or the recording device is used.
In order to wet the surface of the ink of the ink ejection port 12,
It is desirable that it is 50 mN / m or less, and it is desirable that it be smaller than the surface tension of the ink used.

To obtain the above properties, another material may be mixed and adjusted. That is, a liquid originally suitable for these properties may be used alone, or a plurality of materials may be mixed to adjust the viscosity or surface tension to a preferred range before use.

By the way, as a material that can be used as the sealing liquid, in the case of aqueous ink, an organic solvent or oil that is liquid at room temperature can be used. For example, hydrocarbons such as octane, nonane, tetradecane and dodecane, higher fatty acids such as oleic acid and linoleic acid, water-insoluble alcohols such as n-decanol and dimethylbutanol, plasticizers such as dibutyl phthalate and dibutyl maleate Can be used. Alternatively, vegetable oil, mineral oil, silicone oil, fluorine oil and the like can be used. These may be used alone or in combination of two or more as long as they can be mixed uniformly.

Next, a method that can be used as a method for arranging the sealing liquid will be described.

Before starting printing, the seal liquid is applied to a brush, cloth,
The ink is supplied to the ink ejection surface by a method such as coating with a blade. Further, a mechanism may be provided in which a tube or a porous member is arranged near the ink ejection surface, and the seal liquid is supplied to the ink ejection surface by capillary force, surface tension, pressure difference, or the like. The seal liquid supplied to the ink ejection surface by these methods forms a film of the seal liquid on the ink surface of the ink ejection port 12.

Next, a preferable range of the film thickness of the sealing liquid will be described.

In the present embodiment, the film thickness of the seal liquid on the ink discharge surface is determined by the period during which the sealing performance is maintained, the diameter of the discharge means 14, the diameter of the discharge port 12, the discharge frequency of the recording head, the kinematic viscosity of the seal liquid, It can be set as appropriate for design specifications such as a method of disposing the sealing liquid. However, considering the sealing performance against clogging and discharging with lower energy, it is preferably 1 μm or more and 200 μm or less. The film thickness of the seal liquid can be controlled, for example, by adjusting the supply amount of the seal liquid, or by forming the periphery of the recording head or the like into a shape that regulates the amount of the seal liquid held.

The seal liquid may be provided in advance in the ink jet recording head or may be supplied to the ink jet recording head as needed.

Next, the basic performance of the sealing liquid drawing means 24 will be described.

The sealing liquid drawing means 24 (hereinafter sometimes simply referred to as "drawing means") is shown in FIG.
As shown in FIG. 3, the sealing liquid is drawn into the ink ejection port 12 and the sealing liquid 22A positioned at the ink ejection port 12 is drawn.
And a seal liquid 22B located around the ink ejection port 12.
And the discharge port 1 in contact with the sealing liquid so that
The second ink is drawn into the ejection port 12.

Here, the position where the seal liquid drawing means 24 is disposed may be disposed on a head such as the discharge chamber 16 or the ink reservoir 18, or may be disposed on a head other than the head such as an ink tank for supplying ink to the head or a supply flow path. May be arranged in the recording device.

In this embodiment, as the sealing liquid drawing means 24, a method of drawing using a negative pressure is adopted. That is, since the operating state and the amount of pull-in of the pull-in means 24 can be easily controlled, it is preferable to use a negative pressure generating means for reducing the pressure inside the head to a negative pressure.

As described above, when the sealing liquid drawing means 24 is disposed on the head, as shown in FIG.
The sealing liquid drawing means 24 draws in using negative pressure. In this case, a negative pressure generating means as the seal liquid drawing means 24 is disposed in the ink reservoir 18 or the ejection chamber 16 and the inside of the head is drawn with a negative pressure.

By the way, the drawing means 24 and the discharge port 12
If there is a distance between them, the response of the drawing of the sealing liquid deteriorates. Therefore, it is desirable that the drawing means 24 such as the negative pressure generating means be disposed in a portion close to the head or in the head. It is desirable to be provided in a portion close to. Further, it is desirable to provide a drawing means 24 such as a negative pressure generating means in the discharge chamber 16 as shown in FIG.

Here, when providing the drawing means 24 in the discharge chamber 16, the drawing means 24 may be provided in accordance with each discharge port 12. In this case, the discharge port 1
If the retraction is controlled every two, the sealing liquid can be drawn without loss, and there is an advantage that the image quality can be improved.

Next, an example of a method that can be used as negative pressure generating means will be described.

As the negative pressure generating means, as shown in FIG. 4, it is preferable to increase the volume in that the pressure is easily controlled to a predetermined set value and the time required for reversible operation is short. Considering the responsiveness, a method of increasing the volume inside the head is more preferable.

The method of generating a negative pressure by increasing the volume uses a deformable member. That is, when a composite member is used and the composite member uses a bimorph structure, the control is simple and the displacement amount can be increased, so that it is preferable in terms of energy efficiency and ease of drawing in the sealing liquid. is there.

The bimorph structure here means, for example,
In the case of two types of members, as shown in FIG. 5, a structure in which two first members 42 and second members 44 that expand and contract in the longitudinal direction are combined, and when one expands, the other contracts.
It refers to a structure that is configured to cause bending displacement as a whole due to different elongation percentages, different shrinkage percentages, and the like. In this example, an example of expansion and contraction in the longitudinal direction is shown. However, the case of expansion and contraction in the direction perpendicular to the paper surface may be used.

As a method of causing the bending displacement,
In addition to the combination of members with different linear expansion coefficients, the combination of members with different volume expansion coefficients, and the combination of optical strain materials,
Combinations of magnetostrictive materials, materials that cause volume expansion and deflection due to heat, and combinations of these deformable members with elastic members such as spring materials and rubber materials can also be used, but in this embodiment, control by heating is easy. Therefore, a method utilizing volume expansion and deflection due to heat is adopted.

The above-mentioned method utilizing volume expansion or deflection due to heat is specifically performed by combining members having different linear thermal expansion coefficients and heating them. As a result, a member having a larger linear thermal expansion coefficient is greatly elongated, and thus a bending displacement occurs. That is, a structure in which both elongate but have different elongation rates.

As the above-mentioned heating method, heating is performed by itself or in combination with a heating member. In the case of own heat generation, Joule heat by energization or the like can be used.

As the members having different linear thermal expansion coefficients, a material having a small linear thermal expansion coefficient and a material having a large linear thermal expansion coefficient are appropriately combined to constitute the sealing liquid drawing means 24. As a material having a small linear thermal expansion coefficient, typically,
Various glasses such as quartz glass and Pyrex, various ceramics, simple metals such as tungsten and molybdenum, Fe-N
i alloy (invar), Fe-Ni-Co alloy (invar super), Fe-Co-
Various alloys such as Cr alloy (stainless steel invar), Fe-B alloy, Cr-Fe-Mn alloy and Mn-Ge alloy can be used. As the material having a large linear thermal expansion coefficient, typically, a metal simple substance such as zinc, aluminum, indium, silver, tin, copper, and nickel, and a metal alloy such as bronze, stainless steel, brass, and duralumin are used. Comes out. The ratio of the coefficient of linear expansion between a material having a small coefficient of linear thermal expansion and a material having a large coefficient of linear thermal expansion is desirably 2 or more.

As described above, the seal liquid drawing means 24 may be arranged in the ink reservoir as shown in FIG. 6, or may be arranged in the discharge chamber 16 as shown in FIG. In these configurations, the sealing liquid drawing means 2
The member having a different linear thermal expansion coefficient constituting the member 4 may generate power itself by energizing the member.
As shown in FIG. 6, heat may be generated by the heat generating means 32. Further, the heat generating means 32 may be used as the discharging means 14 as shown in FIG.

Here, the sealing liquid drawing means 24 is disposed in the discharge chamber 16, and the members 42, 44 of the sealing liquid drawing means 24 having different linear thermal expansion coefficients are heated by the heating means 32. A method of creating the sealing liquid drawing means 24 when the seal liquid is used as the discharging means 14 will be described. That is, as shown in FIG. 8, the substrate is formed of a laminated structure of two types of materials 42 and 44 having different linear expansion coefficients on a substrate. The substrate side is made of a first elastic member having a large linear expansion coefficient such as nickel, for example (nickel linear expansion coefficient α = 1).
3.4 × 10 ⁻⁶ ) 42, and a second elastic member having a small linear expansion coefficient such as quartz glass (α of quartz glass = 4.6)
× 10 ^-6 ) 44 are laminated. The first elastic member 42 having a large linear expansion coefficient is not limited to nickel, and may be zinc or the like. The second elastic member 44 having a small linear thermal expansion coefficient is not limited to quartz glass. Alternatively, any of the various ceramics described above may be used.

Here, when the first elastic member 42 is not heated (when it is not heated by the heating means or when the flowing current is zero), the stress is adjusted so as to be a flat plate. The adjustment of the stress can be adjusted by the film forming conditions of the material. For example, when nickel is used as the first elastic member and quartz glass is used as the second elastic member, the current density is set to 20 mA / cm 2 so that the stress of nickel becomes zero, and the film is formed by electrolytic plating. The gas pressure of argon is set to 8 mTorr and the power is set to 1 k so that the stress of quartz glass becomes zero.
It is set to W and a film is formed by a sputtering method.

The heat generating member is preferably made of a material which generates an electric heat phenomenon that generates Joule heat when energized, and has a volume specific resistance in the range of 10 ^-2 to 10 ⁶ Ω · cm.

The material may be a thin film of a resistive inorganic material such as polycrystalline Si or TaN, a single layer or a mixed / composite layer of various ceramic materials, or one or more of a heat-resistant resin and a conductive or insulating filler. A mixture / composite of various kinds or a mixture / composite of various ceramic materials and metal materials is used.

Examples of the heat resistant resin specifically used include:
Polyimide resin, polyphenylene oxide resin, polyimide amide resin, polysulfone resin, polyphenylene oxide resin, poly-P-xylylene resin, etc. or a material containing these dielectrics, or a conductive filler and a conductive material include C , Ni, Au, Ag, Fe, Al, T
i, Pd, Ta, Cu, Co, Cr, Pt, Mo, R
Inorganic material such as u, W, In and VO ₂ , RuO ₂ , Ta
N, SiC, ZrO ₂ , InO, Ta ₂ N, ZrN, Nb
N, VN, TiB ₂ , ZrB ₂ , HfB ₂ , TaB ₂ , Mo
B ₂ , CrB ₂ , B ₂ C, MoB, ZrC, VC, TiC
And the like, and compounds and mixtures thereof. It is preferable that the insulating material used for resistance value control and settlement is composed of the heat-resistant resin and various ceramic materials (alumina, zirconia, silicon compound, magnesium compound, etc.).

Next, a method of drawing in and discharging the sealing liquid will be described.

In the present embodiment, it is sufficient that the sealing liquid 22A drawn into the discharge port 12 before the ink is discharged is separated from the seal liquid 22B around the discharge port 12 by the drawing means 24 described above. Specifically, at the time of discharge, first, the drawing-in means 24 operates (drawing mode) to draw the sealing liquid into the discharge port 12, and the drawn-in sealing liquid 22A is turned into the surrounding sealing liquid 22B as shown in FIG. And separated. Next, in the separated state, the ink of the ink discharge port 12 is discharged together with the seal liquid by the discharge means 14 (discharge mode). At the time of ejection,
The seal liquid in the discharge port 12 does not have to be completely discharged together with the ink. By releasing the drawing means 24 and returning the drawn ink (or the ink and the sealing liquid) to the state before the drawing as shown in FIG. 10B, the sealing liquid around the discharge port 12 becomes the ink. The ink at the discharge port 12 is sealed again to prevent clogging.

Next, a method for holding the retracted state will be described.

The state in which the sealing liquid is drawn may be maintained, and a plurality of ejections may be performed in this state.
In this case, it is not necessary to perform the pull-in operation for each discharge, and there is an advantage that the discharge frequency can be increased because the discharge interval is shortened. This holding is performed by the retraction means 24.
Can be used in a state in which is kept in an operating state, and a method in which a closed state is created and held. The retracted state may be maintained by both keeping the retracting means 24 in the operating state and creating a closed state. In the case where the closed state is created and held, if the draw-in means 24 continues to consume power in the operating state, the drawn-in state can be maintained even when the draw-in means 24 is deactivated, so that there is an effect that power can be saved. are doing.

Here, as described above, the retracting means 2
4 can also be configured to also serve as the discharging means 14 (using the heat generating means as the discharging means 14). As shown in FIG. 9, the discharging means 14 which also serves as the drawing means 24, discharges the sealing liquid so as to separate the drawn sealing liquid from the surrounding sealing liquid.
4 and a discharge mode in which the discharge unit 14 operates so that ink droplets are discharged in accordance with an image signal after being separated. In the present embodiment, the ink is ejected in the ejection mode in the ejection mode by operating in the ejection mode before ejection to make the ejection state.

In order for the discharging means 14 which also serves as the drawing means 24 to operate in the discharging mode, the positive pressure (relative pressure) is applied by applying a positive pressure (relative pressure) based on the pressure in this state from the state where the discharging means 14 is separated. The ink and the sealing liquid drawn into the chamber 16 are discharged. If you are deformed and retracted,
The discharge chamber 16 is deformed so as to reduce the volume, and a positive pressure is applied. When the piezoelectric member is deformed and discharged, the potential is changed to a potential lower than the potential applied at the time of pulling in, and the piezoelectric member is deformed to apply a positive pressure. This potential depends on the diameter of the discharge port 12, the thickness of the seal liquid, the kinematic viscosity of the seal liquid,
An optimal potential is appropriately selected with respect to the surface tension of the sealing liquid and the diameter and speed of the ink droplet to be discharged.

Here, in order to maintain the pull-in state while maintaining the negative pressure of the discharge means 14, for example, as shown in FIG. The negative pressure is maintained by using a bias applying unit that continuously applies the voltage for the bias in a bias state. When the piezoelectric member is used for the ejection unit 14, the bias is applied to the ejection unit 14 to maintain the deformation. An ejection signal is output to the ejection means 14 in accordance with the image signal, and the bias potential is maintained after driving in the ejection mode. To release the holding, the bias-like pull-in potential is returned to the reference potential, and the pull-in is returned.

The above-described ink jet recording head is used as an ink jet recording apparatus. That is,
The ink jet recording apparatus according to the present embodiment includes an ink ejection port 12, a seal liquid for sealing the ink ejection port 12, an ink ejection unit 14 for ejecting ink from the ink ejection port 12 according to an image signal, and the seal This is an ink jet recording apparatus having a seal liquid drawing means 24 for drawing a liquid. With this inkjet recording apparatus, an image is recorded by discharging ink corresponding to an image signal onto an image recording medium. In the ink jet recording apparatus of the present embodiment, the above-described retracting means 24 may be incorporated in the inkjet recording head, or the retracting means 24 may be provided outside the head in the recording apparatus. As described above, the drawing-in means 24 is preferably provided in a portion near the discharge port 12 because the response of drawing in the sealing liquid is improved. In addition, retraction means 2
It is preferable to use the negative pressure generating means 4 because it is easy to control the operation state and the amount of drawing of the drawing means 24. In addition, since the ejection frequency can be increased, it is also preferable to perform a plurality of ejections by providing a holding unit that holds the retracted state,
In this case, the holding means may be a means for keeping the retraction means 24 in the operating state, or a means for making and holding a closed state.

Further, in the ink jet recording apparatus of the present embodiment, the ink discharging means 14 which discharges ink from the ink discharging port 12 in accordance with the image signal, and also serves as the sealing liquid drawing means 24 which draws the sealing liquid. 14 may be provided. The discharge means 14 which also serves as the drawing means 24 generates a negative pressure at the time of drawing, draws and separates the seal liquid, and generates a positive pressure at the time of discharge to discharge the ink. It is preferable to use a method of generating pressure by increasing or decreasing the volume of the discharge chamber 16.

According to the present embodiment, the seal liquid 22A located at the discharge port 12 and the seal liquid 22B positioned around the discharge port 12 are separated (separated), whereby the discharge port 12 The effect of hindering ink ejection from the surrounding seal liquid 22B can be eliminated.
Resistance at the time of ejection can be reduced. For this reason, even in a low temperature environment in which the viscosity of the sealing liquid increases, a clear image can be printed without causing ejection failure.
In addition, since the discharge resistance is low, even if the seal liquid to be arranged is thick or a high-viscosity seal liquid material is selected, both performance against clogging and discharge performance can be achieved, preventing clogging for a longer period of time. Such a design of the head 10 is also possible. Further, in the present embodiment, since the discharge port 12 is sealed by the sealing liquid, clogging due to drying of the ink does not occur even after a long period of rest, so that the discharge operation can be performed immediately when necessary, It is possible to reduce or eliminate a maintenance process after a long-term suspension. As a result, it is possible to reduce the size and cost of the recording apparatus, reduce the waiting time before printing and the noise due to maintenance, which have been caused by maintenance after a long pause, and reduce the running cost due to the disposal of a large amount of ink. It is also possible to suppress the rise.

Since the seal liquid 22A located at the ink discharge port 12 is separated from the seal liquid 22B located at the periphery, in the present embodiment, the seal liquid 22A positioned at the ink discharge port 12 is discharged from the ink discharge port 12. Pull into exit 12. The amount of pull-in required for this separation is the diameter of the discharge port 12, the thickness of the seal liquid, the kinematic viscosity of the seal liquid,
The optimum value is appropriately set according to a design value such as the surface tension of the sealing liquid. Further, the pull-in amount may be variably controlled in response to a case where these conditions change due to an environment or the like.

Incidentally, as described in Japanese Patent Application Laid-Open No. 3-132356, there is a method in which a sealing liquid is drawn by solidification and contraction of hot melt ink. However, in the shrinkage during cooling and solidification, the sealing liquid is drawn in at a slower speed than the drawing in the present embodiment, so that the surrounding sealing liquid gradually flows into the discharge port in accordance with the drawing and cannot be separated. Further, in the retracted state, the ink 21 cannot be discharged because the ink 21 is solidified. Further, in the case of shrinkage during cooling and solidification, a cooling time of several hours is required in the case of a long time from several minutes, whereas in the present embodiment, the time required for retraction is the kinematic viscosity of the sealing liquid, the surface tension, The thickness is appropriately selected depending on the thickness, the diameter of the discharge port, and the shape of the discharge port. In order to effectively separate the discharge port, it is preferable that the pull-in operation is performed within one second.
It is preferred to step in (within seconds) and operate the means. That is, the contents described in JP-A-3-132356 are essentially different from the contents of the present application.

In the present embodiment, since the sealing liquid drawing means 24 has a bimorph structure using composite members having different thermal expansion coefficients, the displacement amount of the discharging means 14 which generates heat is particularly high. Can be adjusted, so that control for each ejection port can be performed with good timing, ink ejection can be stabilized, and high image quality can be achieved.

In this embodiment, the individual discharge ports 1
The discharge means 14 which also serves as the pull-in means 24 is provided according to 2 to perform pull-in and discharge. Accordingly, it is possible to control the drawing-in and the discharging for each discharge port 12, and it is possible to set such that the sealing liquid is drawn in with high accuracy without loss, and the optimum drawing-in state is selected and discharged, and high image quality can be achieved. . In addition, since the drawing means 24 and the discharging means 14 are combined, the drawing means 24 and the discharging means 14 can be collectively formed and formed on the same substrate. Pricing becomes possible. Further, since the driving means of the drawing means 24 and the driving means of the discharge means 14 are also used, the size and the price can be reduced.

[0080]

First Embodiment Hereinafter, the present invention will be described in more detail with reference to a first embodiment, but the present invention is not limited thereto.

As shown in FIG. 11, the head has an ink reservoir 18 inside and a discharge chamber 16 having a diameter of 40 μm.
Communicates. 12, first elastic members 42 having different linear thermal expansion coefficients are provided on the wall surface of the ink reservoir 18.
Nickel (linear thermal expansion coefficient α = 13.4 × 10 ^-6 )
The sealing liquid drawing means 24, which has a bimorph structure made of quartz glass (linear thermal expansion coefficient α = 4.6 × 10 ⁻⁶ ) as the second elastic member 44, is used as the diaphragm 40.
Is disposed on the head 10 via the. That is, the heating means constitutes the ejection means 14 as described above.

As a sealing liquid, a liquid prepared by mixing a plurality of types of silicone oils (kinematic viscosity: 30 mm ² /
s, surface tension 20.8 mN / m, specific gravity 1.0). The vapor pressure of this sealing liquid at 25 ° C. is 0.1 mmH
g or less, and there was no compatibility with the used ink.

The ink used was composed of 60% by weight of water, 38% by weight of diethylene glycol and 2% by weight of a dye, and had a kinematic viscosity of 2.0 mm ² / s, a surface tension of 40 mN / m and a specific gravity of 1.06.

Using the head of this example, the state of ejection was observed under magnification. The seal liquid was arranged in a film shape on the surface of the head where the ejection ports were arranged so that the thickness thereof became 50 μm. First,
The voltage was applied to the discharge means 14 by the bias applying means, and the discharge chamber 16 was deformed so as to increase its volume. Negative pressure was generated by this volume increase, and the sealing liquid in contact with the discharge port was drawn into the discharge port to separate it from the surrounding seal liquid. In this state, when a voltage of 16 V was applied to the ejection means 14 in accordance with the image signal to eject the ink, it was observed that the ink droplets were ejected stably. After a series of ejections, the bias was released to set the potential to 0 V, and the drawn ink was returned to return to the sealed state.

In this embodiment, before the head moves for one line (one way by the carriage) to perform discharge, a bias is applied to draw in the seal liquid, and the discharge corresponding to the image signal is performed while moving the head. went. After the head has moved by one line, the bias is released, the drawing is returned, and the head returns to the sealed state. Printing was performed by repeating this series of operations.

Then, a printing test was performed in a normal temperature environment. That is, the head of this embodiment is attached to a recording apparatus provided with a mechanism for feeding recording paper under conditions of normal temperature environment, and an image is printed in a room at normal temperature (temperature: 25 ° C., relative humidity: 50%). Observation of the resulting image with the naked eye revealed that there was no print defect such as blurring and a clear image was recorded.

A printing test was performed in a low-temperature environment.
That is, this recording apparatus is used in a low temperature environment (air temperature 5 ° C., relative humidity 3
(0%) for 24 hours, and a printing test was performed in this low-temperature environment. As a result, clear printing was possible as in the previous test. Observation of the printed image with the naked eye revealed no difference from the printing test at room temperature, and a clear image was recorded.

Further, after leaving the ink jet recording head in an environment of a temperature of 25 ° C. and a relative humidity of 30% RH for 30 days, a print test was performed without performing any maintenance operation of a normal ink jet recording apparatus, and an output was performed. The image was observed. No ejection failure due to clogging occurred in the ink ejection ports, and the printed image had no disturbance of the dots, and a clear image was recorded as before leaving. A print test was performed after leaving a head similar to the recording head of the present embodiment under the same conditions for 30 days except that no seal liquid was disposed, and clogging occurred in more than half of the ejection openings. , Could be printed only partially.

For comparison, a head similar to the head of this embodiment was used except that the ejection means 14 was not driven in the pull-in mode, and a sealing liquid having a thickness of 50 μm was applied to the surface where the ejection ports are arranged.
m. The ejection of this head was observed, and a voltage was applied to the ejection means 14 for a period of 10 μs so that ejection was performed only at a positive pressure so that ejection similar to that of the head of the example was obtained. Further, this head is attached to a recording apparatus, and is operated at normal temperature (air temperature: 25 ° C., relative humidity: 50%).
When a print test of an image was performed in the room No. 2, no significant difference was observed with the naked eye from the print result of the example. However, in a low temperature environment (temperature 5 ° C, relative humidity 30%), 24
When the printing test was performed in this low temperature environment after standing for a long time, a defective portion where no printing was performed was noticeable, and only an unclear image was obtained. (Second Embodiment) Next, a second embodiment of the present invention will be described. This embodiment has the same configuration as the above-described first embodiment (the various configuration patterns of the first embodiment can be similarly applied to this embodiment). The reference numerals are attached and the description is omitted. Note that the seal liquid drawing means 24 (also in the case of the structure also serving as the discharge means 14) is formed of a bimorph composite member as described above.

In the present embodiment, as shown in FIG. 13, a pull-in signal for driving the pull-in means 24 based on a discharge basic signal and an image signal, which will be described later, and the discharge means 14 are driven in accordance with the image signal. Signal control means 60 for controlling a discharge signal for performing the discharge. The signal control unit 60 outputs a pull-in signal and drives the pull-in unit 24 so as to draw the seal liquid every time before ink discharge, and then outputs a discharge signal to drive the discharge unit 14. The process from the driving of the pull-in means 24 to the end of the ejection is performed within an ejection cycle (hereinafter, referred to as a “basic ejection cycle”) in the case where ink droplets are continuously ejected from the same ejection port 12. The signal control means 60 of the present embodiment outputs a discharge signal with a predetermined delay from the pull-in signal so as to discharge the ink after the drawn-in seal liquid is separated from the surrounding seal liquid.

The signal control means 60 controls the ejection frequency (= 1 unit) for continuously ejecting ink droplets from the same ejection port 12.
/ Discharge basic cycle) (hereinafter referred to as “discharge basic signal”) and an image signal for selecting discharge / non-discharge when the ink is discharged from the discharge unit 14 according to image information. A pull-in signal is output, and an ejection signal delayed by a predetermined delay time a (details will be described later) from the pull-in signal is output. To output the delayed ejection signal, the signal control means 6
In the case of 0, an image signal is delayed to be an ejection signal, or an image signal is generated based on a signal delayed with respect to an ejection basic signal, and is used as an ejection signal. The delay time a is determined by taking into account design specifications such as the diameter of the discharge means 14, the discharge port 12, the basic discharge frequency, the thickness of the seal liquid, the kinematic viscosity of the seal liquid, and the surface tension of the seal liquid. Sets the optimal time after is separated from the surrounding sealing liquid.
Further, the delay time a is set so that the ejection is completed by the next pull-in.

The signal control means 60 may be disposed in the head 10, may be disposed in a recording device other than the head 10, and may be disposed together with the head 10 and an electric circuit for controlling the device. I don't care.

The signal control means 60 controls a signal applied to, for example, a piezoelectric member constituting the pull-in means 24 and a signal applied to, for example, a heater constituting the ejection means 14 in order to output a delayed ejection signal. It may control a signal on the way to the pull-in means 24 or the discharge means 14, control the basic discharge signal and the image signal, and generate a signal delayed when the basic discharge signal and the image signal are generated. It may be generated and controlled.

Here, an example of a circuit used for the signal control means 60 will be described.

To delay the image signal and the basic clock signal by the signal control means 60, various known delay circuits are used. For example, a delay circuit including a capacitor and a resistor, a delay circuit in which a plurality of buffer circuits are connected in cascade,
The signal control means 60 can be configured using a delay circuit including a transmission circuit, a counter circuit, and a comparator circuit, but the signal control means 60 can be configured by various electric circuits or IC circuits. Alternatively, a dedicated IC circuit or the like can be manufactured. Further, it is also possible to configure the signal control means 60 for performing a delay by converting an input signal into data and comparing the data with data on a memory by microcomputer control or the like.

By the way, there are two types of synchronization methods for pull-in.

The signal control means 60 has two methods of outputting a pull-in signal so as to draw in the sealing liquid for each discharge basic signal and outputting a pull-in signal so as to draw in the sealing liquid for each image signal.

As shown in FIG. 14, the control system for drawing in the sealing liquid for each discharge basic signal, according to the input timing of the clock signal from the basic clock generation circuit 62, receives the device setting information from the device setting information generation circuit 64. And an image for outputting an image signal based on the image information from the image information generation circuit 68 in accordance with the input timing of the clock signal from the basic clock generation circuit 62 and the basic ejection signal generation circuit 66 for outputting the basic ejection signal based on Based on the signal generation circuit 70, the basic discharge signal and the image signal, the power supply of the drawing-in drive power supply 72 controls the sealing liquid drawing-in means 24, and the power supply of the discharge means 14 driving power supply 74 controls the discharge means 14. The signal control means 60
It has.

The signal control means 60 includes a delay circuit 76 connected to the discharge basic signal generation circuit 66 and the image signal generation circuit 70, and a pull-in drive circuit connected to the pull-in drive power supply 72 and the discharge basic signal generation circuit 66. 78,
And a discharge circuit 14 driving circuit 80 connected to the delay circuit 76 and the discharge means 14 driving power supply 74.

Then, the signal control means 60 outputs a pull-in signal in accordance with the basic ejection signal as shown in FIG. In this method, ink ejection / non-ejection (image signal)
Irrespective of the above, the sealing liquid at the discharge port 12 is drawn in at the basic discharge cycle. In order to always perform the pull-in, the pull-in is performed even when no discharge is performed. However, when the head 10 having a plurality of discharge ports 12 is used, the pull-in conditions for each discharge are the same since the pull-in for all the discharge ports 12 is performed evenly. There is a feature that there is.

Therefore, in this method, it is preferable that the head 10 be provided with a common drawing means 24 corresponding to the plurality of ejection ports 12, so that the control of the drawing means 24 is easy and the signal control means 60 There is an advantage that the apparatus is cheaper because the configuration is simplified.

As shown in FIG. 15, the control system for drawing in the seal liquid for each image signal has substantially the same configuration as the control system for drawing in the seal liquid for each discharge basic signal. The difference is that the circuit 78 is configured to receive an image signal.

Then, the signal control means 60 outputs a pull-in signal according to the image signal as shown in FIG.
In this method, the seal liquid of the discharge port 12 is drawn on demand only immediately before ink is discharged. Since the retraction is performed just before the discharge, there is no waste in the retraction,
When the head 10 having a plurality of ejection ports 12 is used, it is possible to control the pull-in corresponding to each of the ejection ports 12. Therefore, in this method, it is preferable that the head 10 has a configuration in which the individual retraction means 24 corresponding to the plurality of ejection ports 12 are provided, and the optimal retraction control for ejection is performed for each individual ejection port 12. This has the advantage that high image quality can be achieved.

Next, the operation of the present embodiment will be described.

In the present embodiment, the sealing liquid is drawn into the discharge port 12 before each ink discharge, and discharge is performed. More specifically, the pull-in means operates in response to the discharge basic signal (see FIG. 16) or the image signal (see FIG. 17) to draw the seal liquid into the discharge port 12, and as shown in FIG. Seal liquid 22A is replaced with surrounding seal liquid 2
Separate with 2B. When performing ejection, the ejection means 14 operates in a divided state to eject ink from the ink ejection ports 12 together with the seal liquid. At the time of discharge, the seal liquid in the discharge port 12 may not be completely discharged together with the ink. Further, it is also possible to release the operation of the drawing means and return the drawn ink (or the ink and the seal liquid) to a state before the drawing and prepare for the next ejection. The above-described control of the pull-in means and the discharge means 14 includes, in response to the pull-in signal, a discharge signal for controlling the pull-in means to return the pull-in state to the original state before the pull-in, and a signal control means 60. Is performed with a predetermined delay time b.

Next, the ink jet recording apparatus will be described.

The ink jet recording apparatus according to the present embodiment comprises an ink ejection port 12, a sealing liquid for sealing the ink ejection port 12, and the ink ejection port 1 according to an image signal.
2, an ink ejection unit 14 for ejecting ink from 2, a seal liquid drawing unit for drawing the seal liquid, a discharge signal for driving the discharge unit 14 according to an image signal, and a drawing signal for driving the seal liquid drawing unit. ,
An ink jet recording apparatus having a signal control unit 60 that applies the ejection signal to the ejection unit 14 after applying a pull-in signal to the sealing liquid entrance unit. From the driving of the pull-in means to the end of ejection, the ejection is performed within the ejection basic cycle. With this ink jet recording apparatus, an image is recorded by discharging ink corresponding to image information onto an image recording medium. In the inkjet recording apparatus of the present embodiment, the above-described retracting means may be incorporated in the inkjet recording head, or the retracting means may be provided outside the head in the recording apparatus. The drawing means is preferably provided in a portion near the discharge port 12 because the response of drawing the sealing liquid is improved. Further, it is preferable to use a negative pressure generating means as the retracting means because the operating state of the retracting means and the amount of retraction can be easily controlled.

It is also preferable to provide sealing means since the amount of operation of the retraction means for obtaining the required retraction amount is small and the time required for completing the retraction is short. The signal control means 60 may be incorporated in the head, or may be arranged outside the head in the recording apparatus. Further, the signal control means 60 may drive the sealing liquid drawing means for each ejection basic signal, or may drive the sealing liquid drawing means for each image signal. Although the signal control means 60 outputs a pull-in release signal, the pull-in state can be quickly returned, so that the basic discharge frequency can be increased and the time required for printing can be shortened, which is preferable. It is also preferable to control the ejection signal and the pull-in release signal variably, since ejection can be performed under more stable conditions according to the environment and the setting and state of the apparatus.

As described above, since the sealing liquid is drawn in every time ink is ejected, the following effects can be obtained. Since the signal control means 60 is provided to control the time from the retraction to the ejection after each retraction, the ejection state can be set to be the same every time the retraction is performed.
As a result, the state (amount, speed, etc.) of the ejected ink can be kept constant every time, the size of the ink dot to be printed, and the variation in the landing position of the ink dot are reduced, the ejection is stable, and the image quality of the printed improves. Immediately after retraction,
Since the amplitude of the vibration remaining on the pull-in means or the meniscus liquid level may be large, in such a case, it is possible to discharge more stably if the vibration is set to be sufficiently small before discharging. If the signal control means 60 is provided to pull in each time and output a pull-in release signal, the drawn-in state can be reliably returned to the sealed state each time. If the retracting means is deactivated each time, the discharge port 12 can be quickly sealed with the sealing liquid to prepare for the next discharge cycle, so that the basic discharge frequency can be increased and the time required for printing can be reduced. Can be shortened. If the delay time a from the retraction to the discharge is variably controlled based on various conditions, the retraction state is the same every time even if the time until the retraction state becomes stable due to environmental fluctuations changes. Since it is possible to set the ejection after the ejection, the ejection is further stabilized, and the printed image quality is improved. Due to environmental fluctuations, device settings and conditions, etc., the time from retraction to separation and the decay time of vibrations remaining on the seal liquid surface immediately after retraction may change. By selecting and discharging, it is possible to stabilize the operation and effect on the environment and the setting and state of the apparatus. The delay time b until the pull-in is released (FIGS. 16 and 17)
) Is variably controlled based on various conditions, it is possible to quickly return to the sealed state and prepare for the next ejection cycle when the delay time before ejection becomes short. The basic discharge frequency can be increased, and the time required for printing can be reduced.

In the present embodiment, the individual discharge ports 1
2, a discharge means 14 serving also as a drawing means is provided,
Pull and discharge are performed. Therefore, it is possible to control the drawing-in and the discharging for each of the discharge ports 12, so that it is possible to set such that the sealing liquid is drawn in without any loss, and the optimum drawing-in state is selected and discharged, and high image quality can be achieved. Further, since the drawing means and the discharging means 14 are combined, the drawing means and the discharging means 14 can be formed and formed collectively on the same substrate, which simplifies the structure of the head and reduces the cost of the apparatus. Becomes possible. Furthermore, since the driving means of the drawing means and the driving means of the discharge means 14 are also used, the size and the price can be reduced.

[0111]

Second Embodiment Hereinafter, the present invention will be described in more detail with reference to a second embodiment, but the present invention is not limited to this. Since the configuration of the present embodiment is the same as that of the first embodiment described above, a description thereof will be omitted, and only different portions will be described.

The signal control means (not shown) was manufactured using an IC circuit and was arranged on the outer wall of the head. The signal control means is configured using a delay circuit as a circuit for outputting the ejection signal, and the circuit for outputting the pull-in release signal is configured as a delay circuit and a flip-flop circuit. The signal control unit receives the image signal, outputs a pull-in signal in accordance with the image signal, switches the potential applied to the pull-in unit from V1 to V2, delays the image signal, and outputs a discharge signal after a predetermined time. The delay time from the input of the image signal to the output of the ejection signal was set to 100 μs. Further, the signal control means delays the image signal, outputs a pull-in release signal after a predetermined time, and switches the potential applied to the pull-in means from 20V to 0V. The delay time from the input of the image signal to the output of the pull-in release signal was set to 120 μs.

Using the head of this example, the state of ejection was observed under magnification. The seal liquid was arranged in a film shape on the surface of the head where the ejection ports were arranged so that the thickness thereof became 50 μm. First,
An image signal was input to the signal control means, a pull-in signal was output, and a voltage of 20 V was applied to the piezoelectric member serving as the pull-in means to deform the head so as to increase the volume inside the head.
A negative pressure was generated due to this increase in volume, and the seal liquid in contact with the discharge port was drawn into the discharge port, and separated from the surrounding seal liquid by 100 μs from the input of the image signal. 1 from image signal input
After 00 μs, the signal control unit outputs an ejection signal, and when a voltage of 15 V is applied to the heater as the ejection unit 14 in a pulsed manner for 6 μs to eject ink, it is observed that ink droplets are ejected stably. Was done. The signal control means includes:
A pull-in release signal is output 120 μs after the input of the image signal, and the potential applied to the pull-in means is set to 0 V.
The ink in the ejection port was returned to the initial state, and the sealing liquid around the ejection port was sealing the ink in the ejection port by the elapse of 500 μs after the operation of the drawing-in means. When an image signal was input as a continuous pulse and this discharge cycle was repeated at a frequency of 1 kHz, it was observed that the seal liquid was drawn in before every discharge, and that the liquid was stably discharged in that state. Further, the frequency of the basic discharge signal is 1 kHz.
When an image signal corresponding to the image information is input under z and the ink is ejected, the measurement result of the diameter and the ejection speed of the ejected ink droplet is continuous / discontinuous of the image signal (that is, the ejection time interval). ), It was almost constant, and it was observed that the liquid was discharged stably.

Here, a printing test was performed under a normal temperature environment. That is, the head of this embodiment is attached to a recording apparatus having a mechanism for feeding recording paper under normal temperature environment conditions, and an image is printed in a room at normal temperature (air temperature 25 ° C., relative humidity 50%).
When the printed image was observed with the naked eye, there was no printing defect such as blurring, and a clear image was recorded.

Further, a printing test was performed in a low temperature environment.
That is, when the recording apparatus was left for 24 hours in a low-temperature environment (temperature of 5 ° C., relative humidity of 30%) and then a printing test was performed in this low-temperature environment, clear printing was possible as in the previous test. was. Observation of the printed image with the naked eye revealed no difference from the printing test at room temperature, and a clear image was recorded.

Further, after leaving the ink jet recording head in an environment of a temperature of 25 ° C. and a relative humidity of 30% RH for 30 days, a print test was performed without performing any maintenance operation of a normal ink jet recording apparatus, and an output was performed. The image was observed. No ejection failure due to clogging occurred in the ink ejection ports, and the printed image had no disturbance of the dots, and a clear image was recorded as before leaving. A print test was performed after leaving a head similar to the recording head of the present embodiment under the same conditions for 30 days except that no seal liquid was disposed, and clogging occurred in more than half of the ejection openings. , Could be printed only partially.

For comparison, a head similar to the head of this embodiment except that it did not have a drawing-in means was used, and a sealing liquid was arranged in a film shape so as to have a thickness of 50 μm on the surface where the ejection ports were arranged. By observing the ejection of this head, the ejection means 14 was set to 16 so that the same ejection as the head of the embodiment was obtained.
Adjustment was performed so that a voltage of V was applied for a period of 7 μs. Further, this head is attached to a recording apparatus, and is operated at normal temperature (air temperature 25
(° C., relative humidity: 50%), a print test of an image was performed. As a result, no significant difference was observed with the naked eye from the print result of the example. However, when the printing test was performed in a low-temperature environment (temperature 5 ° C., relative humidity 30%) for 24 hours and then performed in this low-temperature environment, defective portions that were not printed were conspicuous and only unclear images were obtained. Was.

[0118]

As described above, according to the present invention, the composite member having a different coefficient of thermal expansion has a bimorph structure to constitute the sealing liquid drawing means, so that the operation amount of the sealing liquid drawing means can be increased. This has the effect that the pull-in can be controlled with less energy.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of an inkjet recording head according to a first embodiment.

FIG. 2 is a diagram showing an example in which a negative pressure generating means is provided as a sealing liquid drawing means.

FIG. 3 is an explanatory diagram for generating a negative pressure.

FIG. 4 is an explanatory diagram of a method for increasing the volume inside the head.

FIG. 5 is an explanatory diagram of a bimorph structure.

FIG. 6 is an explanatory diagram of a negative pressure generating means.

FIG. 7 is an explanatory diagram illustrating a method of generating a negative pressure and a positive pressure by changing the volume of a discharge chamber.

FIG. 8 is an explanatory view for explaining that the heat generating means constitutes the discharging means.

FIG. 9 is a timing chart of the present embodiment.

FIG. 10 is an explanatory diagram of a drawn-in state and a sealed state of a sealing liquid.

FIG. 11 is an explanatory diagram of a method of using a composite member as a drawing means.

FIG. 12 is an explanatory diagram of a configuration of a composite member used for a retracting unit.

FIG. 13 is a basic configuration diagram of an ink jet recording head according to a second embodiment.

FIG. 14 is a block diagram of a control system in a case where a sealing liquid is drawn in for each basic discharge signal.

FIG. 15 is a block diagram of a control system when a seal liquid is drawn in for each image signal.

FIG. 16 is a timing chart in the case where a seal liquid is drawn in for each basic discharge signal.

FIG. 17 is a timing chart when a seal liquid is drawn in for each image signal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Head 12 Ink discharge port 14 Discharge means 14 16 Discharge chamber 18 Ink reservoir 22 Seal liquid 24 Seal liquid drawing means

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Susumu Hirata 430 Green Tech Nakai, Nakai-cho, Ashigara-gun, Kanagawa Fuji Xerox Co., Ltd. (72) Inventor Hiroaki Sato 430 Sakai Nakai-cho, Nakai-machi, Ashigara-gun, Kanagawa Fuji Xerox Inside (72) Inventor Yasufumi Suwabe 430 Green Tech Nakai, Nakai-cho, Ashigara-Kan, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Megumi Hasebe 430 Sakai, Nakai-cho, Nakai-cho, Ashigara-Kanagawa, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. 72) Inventor Tetsu Mori 430 Green Tech Nakai, Nakai-cho, Ashigarakami-gun, Kanagawa Prefecture Fuji Xerox Co., Ltd. F-term (reference) 2C056 EA17 EC07 EC08 EC32 EC37 FA03 FA04 JA24 2C057 AF74 AG44 AG46 AM17 BA03 BA14 BA15

Claims (10)

[Claims] An ink ejection port for ejecting ink; a sealing liquid for sealing the ink ejection port; an ink ejection means for ejecting ink from the ink ejection port in accordance with an input image signal; A seal liquid draw-in which draws the seal liquid into the ink discharge port so that a seal liquid located at the ink discharge port of the seal liquid and a seal liquid of the seal liquid positioned around the ink discharge port are separated. Means, and a composite member having a different coefficient of thermal expansion having a bimorph structure,
An ink jet recording head comprising the sealing liquid drawing means. 2. An ink jet recording head according to claim 1, wherein said sealing liquid drawing means includes a heating means for heating said composite member, and said heating means is said discharging means. 3. A control means for controlling the ink discharge means and the seal liquid drawing means such that the drawing of the seal liquid and the discharge of the ink are executed within a predetermined discharge basic cycle. The ink jet recording head according to claim 1 or 2, wherein: 4. An ink jet recording apparatus according to claim 3, wherein said control means controls said ink discharge means such that discharge of said ink is executed after a predetermined delay time from the input of said image signal. head. 5. An ink jet recording apparatus comprising the ink jet recording head according to claim 1. 6. An ink jet recording method for an ink jet recording apparatus according to claim 5, wherein a sealing liquid is drawn in before ink is ejected. 7. The ink jet recording method according to claim 6, wherein a state in which the sealing liquid is drawn is maintained. 8. The ink jet recording method according to claim 7, wherein a plurality of inks are ejected when the state where the sealing liquid is drawn is maintained. 9. An ink jet recording apparatus comprising the ink jet recording head according to claim 3. 10. An ink jet recording method for an ink jet recording apparatus according to claim 10, wherein a sealing liquid is drawn in each time before ink is ejected.