JP2000318172A - 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 discharge of ink. SOLUTION: An ink jet recording head 10 has an ink discharge orifice 12 provided on an ink discharge surface, an discharge chamber 16 provided with a discharge means 14, an ink sump 18 for supplying ink to the discharge chamber 16, a seal liquid drawing-in means 24 for drawing in a seal liquid so as to separate the same into the seal liquid 22A positioned at the ink discharge orifice 12 and the seal liquid 22B positioned around the ink discharge orifice 12 and the detection parts 32A1, 32A2 of a seal detection means. The seal liquid judging part 34 of the seal liquid detection means is arranged inside or outside the ink jet recording head 10. That is, the seal liquid detection means is provided with the seal liquid detection parts 32A1, 32A2 and the seal liquid judging part 34.

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] In a commercially available ink jet recording apparatus, various maintenance operations are required in order to recover clogging of nozzles 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, a pump and an absorber of waste ink are required in the device, which complicates and enlarges the device, and increases the cost of the device. I have. 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, as disclosed in Japanese Patent Application Laid-Open No. 52-104130, a film of a seal liquid insoluble in ink and a film of the seal liquid are provided. There is known a method in which the ink discharge port is sealed by means to shield the ink from the 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.

Japanese Patent Application Laid-Open No. 54-69436 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.

JP-A-5-177841 describes a method of sealing a nozzle with a seal liquid as necessary, 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]

In order to achieve the above object, an ink jet recording head according to the first aspect of the present invention has an ink discharge port for discharging ink, a seal liquid for sealing the ink discharge port, and an input port. An ink discharge unit that discharges ink from the ink discharge port in accordance with the generated image signal, a seal liquid of the seal liquid positioned on the ink discharge port, and a seal positioned around the ink discharge port of the seal liquid There is provided a sealing liquid drawing means for drawing the seal liquid into the ink discharge port so as to separate the liquid from the liquid, and a detection means for detecting the seal liquid in the ink discharge port.

That is, the sealing 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 in a state where the ink ejection port is sealed with the seal liquid, only the seal liquid positioned on the ink ejection port due to the viscosity of the seal liquid or the like. In addition, the sealing liquid located around the ink ejection port also tries to prevent ink ejection.

Therefore, in the present invention, the sealing liquid drawing means is configured to divide the sealing liquid into the ink discharge port so that the sealing liquid positioned on the ink discharge port is separated from the seal liquid positioned around the ink discharge port. Draw in.

As described above, the seal liquid is drawn into the ink discharge port so as to separate the seal liquid located on the ink discharge port from the seal liquid located around the ink discharge port. In the case where ink is to be ejected, it is possible to eliminate the effect of hindering the ink ejection of the seal liquid positioned around the ink ejection port, and to stably eject ink.

The detecting means according to the present invention detects the seal liquid in the ink discharge port.

Here, the detecting means is as follows.
The presence or absence of the sealing liquid may be detected. In addition,
It is preferable for the detecting means to detect the position of the seal liquid accurately by determining the presence or absence of the ink in addition to the presence or absence of the seal liquid. The detecting means may detect the position of the sealing liquid. Further, the detecting means may include a plurality of detecting elements arranged in the ink ejection ports. In this case, the plurality of detection elements may be arranged in the ink discharge port so as to be separated from each other in a direction intersecting the direction in which the seal liquid is drawn. The detecting means may include at least a pair of detecting elements. The detecting element may be an electrode element. The detecting means detects any one of the resistance value between the plurality of electrode elements, the amount of current flowing between the plurality of electrode elements, and the capacitance between the plurality of electrode elements. And detecting the seal liquid in the ink ejection port. Further, as in the eleventh aspect, the detecting means detects the seal liquid in the ink ejection port by applying an AC voltage between the plurality of electrode elements.

Here, the sealing liquid drawing means may be arranged at a position other than the head, or may be arranged at the head. Thereby, the response of the drawing by the sealing liquid drawing means can be improved. In order to improve the response, it is desirable to dispose the sealing liquid drawing means in a position close to the ink ejection port, and more desirably to dispose it in the ink ejection chamber.

As described above, since the seal liquid in the ink discharge is detected, the seal liquid positioned at the ink discharge port and the seal liquid positioned around the ink discharge port can be detected.
Can be grasped as to whether or not the seal liquid is separated, and therefore, the seal liquid located at the ink discharge port and the seal liquid located around the ink discharge port can be surely separated. Then, immediately after the seal liquid positioned at the ink discharge port and the seal liquid positioned around the ink discharge port are separated from each other, if the ink is discharged by controlling the ink discharge means, there is no variation in the ink drop to be discharged. The printing quality is improved.

Further, since it is possible to grasp whether or not the seal liquid located at the ink discharge port and the seal liquid located around the ink discharge port are separated, the position adjusting means is provided. May adjust the positions of the seal liquid and the ink. In addition, as in claim 3,
The sealing liquid drawing means may also serve as the position adjusting means.

According to a thirteenth aspect, an ink jet recording apparatus including the ink jet recording head according to any one of the first to twelfth aspects may be used. In this case, an error processing unit for performing an error process when the detection result of the detection unit is not a desired result may be further provided.

Here, the error processing is performed by displaying a warning, stopping the printing operation, and using the seal liquid by the position adjusting means (note that the seal liquid drawing means may also be used (see claim 3)). Alternatively, it may be at least one of position adjustment of the ink position, display of the warning, and re-detection of the ink position after the position adjustment.

According to a sixteenth aspect of the present invention, in the ink jet recording method of the thirteenth aspect, the seal liquid is drawn in before the ink is ejected, and at least one of the seal liquid and the ink is drawn into a predetermined position. Detect whether or not. Therefore, it is possible to grasp whether or not the seal liquid located at the ink ejection port and the seal liquid located around the ink ejection port are separated, and if not, by controlling the position adjusting means. Thus, the sealing liquid can be reliably separated. Therefore, it is possible to reliably separate the seal liquid located at the ink ejection port from the seal liquid located around the ink ejection port.

Further, the position adjusting means may adjust the position of the seal liquid or the ink in a state where at least one of the seal liquid and the ink has been drawn in. In this way, if the adjustment is made so that the retracted state at the time of each ejection becomes the same, the ejection is stabilized, and high image quality can be achieved.

When returning at least one of the drawn seal liquid and the ink to the original state, it is determined whether or not the ink has returned to the original state. Therefore, when the ink does not return to the original state, it can be immediately notified. In this case, if a predetermined process is performed, accidental clogging, trouble, and the like can be avoided.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an ink jet recording head according to the present invention will be described with reference to the drawings. FIG. 1 shows a basic configuration example of an ink jet recording head according to the present embodiment. The ink jet recording head (hereinafter, may be simply referred to as “head”) 10 of the present embodiment includes:
Ink ejection port 12 provided on ink ejection surface, ejection means 1
The discharge chamber 16 is provided with an ink reservoir 18 for supplying ink to the discharge chamber 16, a seal liquid drawing means 24, and detection sections 32A1 and 32A2 of seal liquid detection means. Further, the inside of the inkjet recording head 10,
Alternatively, a seal liquid determination unit 34 of the seal liquid detecting means is provided outside. That is, the sealing liquid detecting means includes the sealing liquid detecting units 32A1, 32A2 and the sealing liquid determining unit 34. The ink is supplied from an ink tank and an ink supply path (not shown) outside the head 10 by an action caused by a capillary force and a pressure difference.

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. Note that FIG. 1 shows a diagram 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 heads 10 can be appropriately selected as desired. Generally, ink droplets are ejected in the direction of gravity (downward).

Here, the ink discharging means 14 usable in the present invention includes ink discharging means used in a conventional ink jet recording head, for example, a pressurizing method.
Ink jetting means such as a continuous flow method and an electrostatic suction method can be widely used, and a method of concentrating acoustic waves, pressure waves, and the like can also be used. A thermal ink jet system or a piezoelectric system can be used as a pressurizing system discharging unit.

The sealing liquid usable in the present invention includes:
It has a function of sealing the ink ejection port 12 and shielding the ink of the ink ejection port 12 from 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.

In order for the sealing liquid and the ink to be incompatible, specifically, the solubility of the sealing liquid in the ink is 0.1% by weight or less in an environment where the head 10 or the recording apparatus is used. Is preferred.

Further, when the sealing liquid is non-volatile,
This is preferable because the liquid does not evaporate while the head 10 is at rest and the sealing liquid does not change the sealing state of the discharge port 12. Non-volatile refers specifically to a vapor pressure of 0.1 mmHg or less under an environment in which the head 10 or the recording device is used.

The kinematic viscosity of the sealing liquid which can be used in the present invention is determined by setting a period for preventing clogging, a discharging means 14 and a discharging port 1.
2, the ejection frequency of the recording head 10, the film thickness of the sealing liquid, the method of disposing the sealing liquid, and other design specifications can be selected as appropriate. The kinematic viscosity ranges widely from low to high. Available. 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 this, the kinematic viscosity of the sealing liquid in the environment where the head 10 or the recording device is used is preferably in the range of 1 to 200 mm ² / s.

The surface tension of the sealing liquid which can be suitably used in the present invention is in the range of 15 to 70 mN / m in an environment in which the head 10 or the recording apparatus is used. 5 to progress
It is preferably 0 mN / m or less, and more preferably smaller than the surface tension of the ink used.

A liquid originally suitable for these properties may be used alone, or a plurality of materials may be mixed to adjust the viscosity and surface tension to a preferred range.

By the way, as the sealing liquid, for example,
Aqueous inks can be used.

As a sealing liquid when using an aqueous ink, an organic solvent or oil which is liquid at normal temperature can be used. For example, octane, nonane, tetradecane,
Hydrocarbons such as dodecane, higher fatty acids such as oleic acid and linoleic acid, water-insoluble alcohols such as n-decanol and dimethylbutanol, and 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.

Before starting printing, the sealing 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.

In the present invention, the film thickness of the seal liquid on the ink discharge surface is determined during the period for maintaining the sealing performance.
4, the diameter of the ejection port 12, the ejection frequency of the recording head 10,
The kinematic viscosity of the sealing liquid, the method for arranging the sealing liquid, and other design specifications can be appropriately set. 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 10 or the like into a shape that regulates the amount of the seal liquid held.

The sealing liquid may be provided in the ink jet recording head 10 in advance, or may be appropriately supplied to the ink jet recording head 10 at the time of use.

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

As shown in FIG. 1, the seal liquid drawing means 24 (hereinafter sometimes simply referred to as “drawing means 24”) includes a seal liquid 22A located at the ink discharge port 12 of the seal liquid 22 and a seal liquid 22A. The seal liquid is drawn into the ink discharge port 12 so that the seal liquid 22B positioned around the ink discharge port 12 is separated from the seal liquid 22B. If the seal liquid 22A and the seal liquid 22B are separated in this way, Any means may be used. The amount of the sealing liquid drawn in to separate the sealing liquid drawn into the discharge port 12 from the surrounding sealing liquid is appropriately selected depending on the kinematic viscosity of the sealing liquid, the surface tension, the diameter of the discharge port, the shape of the discharge port, and the like. As an example, in the case of a configuration in which the shape of the discharge port does not change the cross-sectional area in the discharge direction, it is possible to satisfactorily separate the shape by drawing in the seal liquid film thickness or more.

The position for disposing the sealing liquid drawing means is the head 10 such as the discharge chamber 16 and the ink reservoir 18.
May be disposed in the recording apparatus other than the head 10 such as an ink tank for supplying ink to the head 10 and a supply flow path.

The means for drawing in the seal liquid are roughly classified into a method using a negative pressure and a method using a capillary force. Since it is easy to control the operation state and the amount of retraction of the retraction means, it is preferable to use a negative pressure generating means for reducing the pressure inside the head 10 to a negative pressure.

When the sealing liquid drawing means is arranged in the head 10, the sealing liquid drawing means draws in using a negative pressure. In this case, the negative pressure generating means is disposed in the ink reservoir 18 or the discharge chamber 16, or the negative pressure generating means is disposed in a separate chamber connected to the ink reservoir 18 or the discharge chamber 16, and the inside of the head 10 is pulled into a negative pressure.

When the sealing liquid drawing means is arranged other than the head 10, both methods using negative pressure and methods using capillary force can be used as the sealing liquid drawing means. As a method of using the negative pressure, a method of connecting a negative pressure generating means disposed outside the head 10 to the head 10 and pulling the inside of the head 10 into a negative pressure, and a method of using the negative pressure generating means disposed outside the head 10 include: A method of connecting to an ink supply path or an ink tank for supplying ink to the head 10 and pulling the inside of the head 10 under a negative pressure, and arranging a negative pressure generating means in the ink supply path or the ink tank for supplying the ink to the head 10 Then, a method in which the inside of the head 10 is pulled in with a negative pressure can be used. As a method of utilizing the capillary force, the ink supply path for supplying ink to the head 10 and the pore diameter of a porous member such as a sponge for preventing ink leakage arranged inside the ink tank are controlled to control the capillary force for the ink. A method of controlling the temperature of the ink to change the surface tension of the ink and increasing the capillary force to a porous member such as an ink supply path or a sponge disposed inside the ink tank. Etc. can also be used. The methods described above may be used alone, in combination, or in any combination.

In the case where the discharge chamber 16 is provided with a drawing means, the drawing means may be provided in accordance with each discharge port 12. In this case, if the drawing is controlled for each discharge port 12, the sealing liquid can be drawn with high precision and without loss.

As negative pressure generating means, there are a method of generating a negative pressure by increasing the internal volume of a deformable or displacing member, and a method of generating a negative pressure by various pumps. Among these, the method of increasing the volume in that the pressure is easily controlled to a predetermined set value and the time required for reversible operation is short is preferable, and considering the responsiveness, the volume inside the head 10 is increased. The method of making it more suitable.

When the method of increasing the volume inside the head 10 is used, in particular, the ink reservoir 18, the ejection chamber 16,
Alternatively, a simple method is to arrange a piezoelectric member or a member deformable by the piezoelectric member in a separate chamber connected thereto, so as to increase the volume inside the head 10. In particular, the piezoelectric member has been put to practical use in devices such as the ink jet head 10 and the vibrator, and since advanced manufacturing technology has been established, various shapes and materials can be appropriately selected according to the specifications of the device. This is preferable for use in a method of increasing the volume inside the head 10.

As the piezoelectric member, there can be widely used materials used for a vibrator or the like which generates distortion or deformation when an electric field is applied. For example, thin films of polycrystals and single crystals, such as quartz, lead zirconate titanate (PZT), barium titanate, lead niobate, lithium niobate, bismuth germanate, and lithium tantalate, zinc oxide, and aluminum nitride Use of an inorganic piezoelectric material consisting of, or a piezoelectric polymer material such as polyurea, polyvinylidene fluoride (PVDF) or a copolymer of PVDF, or a composite piezoelectric material of an inorganic piezoelectric material and a piezoelectric polymer material You can also.

Next, the basic function of the seal liquid detecting means will be described.

The sealing liquid detecting means is provided at the place where the sealing liquid detecting sections 32A1 and 32A2 are installed.
And the ink is detected, and the operation timing is sent to the seal liquid drawing means 22 and the discharge means 14.

If the sealing liquid is drawn only by the sealing liquid drawing means 24 when drawing the sealing liquid, environmental changes, unexpected vibrations and shocks, dirt and scratches near the ink discharge port 12, and variations in the ink meniscus refill. If such occurs, the seal liquid is not reliably drawn in, and the seal liquid 22A positioned at the discharge port and the seal liquid 22B positioned around the discharge port cannot be separated.
Trouble that cannot be discharged due to the resistance of the sealing liquid occurs.

When the discharge means 14 is a heater, if the seal liquid is drawn too much due to environmental changes, unexpected vibrations, impacts, etc., the seal liquid adheres to the heater section and cannot be discharged. Trouble may occur.

That is, the sealing liquid detecting means confirms that the sealing liquid has been drawn into a desired position (details will be described later), and sends the timing to the next discharge step, thereby preventing such troubles. Means.

Further, if the ink is not reliably returned from the pulled-in state after printing, the ink discharge port 12 there is left in a state where the seal liquid is released, which causes clogging. In such a case, the same means can be used to detect that the ink has not returned, which is effective for error detection.

Furthermore, when the seal liquid of each discharge port 12 is drawn in each time to release the seal liquid and open and close the seal liquid for discharging the ink on demand, the end of the drawing of the seal liquid is detected, and the ink discharge is started. As a result, variations in ink drops are eliminated, and printing quality is improved.

As described above, the seal liquid detecting means
The seal liquid detection sections 32A1, 32A2 and the seal liquid detection determination section 34 are provided.
A2 is installed at a desired position on the ink flow path wall surface where the seal liquid is drawn.

The seal liquid detectors 32A1 and 32A2 are composed of detection elements used in the seal liquid detection method. The seal liquid detection method only needs to be able to determine the presence / absence of the seal liquid by the detection element. It is preferable that the detection element can determine both the presence / absence of the seal liquid and the presence / absence of the ink, since it can be used for more accurate determination of the liquid position.

As a detection method that can be used in the present invention, there are a method of measuring and determining the capacitance of an object, a method of measuring a resistance value or a current amount by applying a voltage, and a method of determining.
In addition, various known detection methods such as an optical sensor, an ultrasonic sensor, and a detection method using a magnetic sensor can be used, but the viewpoint of ease of measurement, element size, and no influence on an object. The method of measuring and determining the capacitance of the object from the target is preferable. The voltage applied to the electrodes is preferably an AC voltage in order to suppress electrolysis of the ink. When detecting the state of the sealing liquid or the ink based on the capacitance, the determination may be made based on the specific capacitance of each liquid calculated from the detected capacitance, the electrode area, and the distance between the electrodes. The relative dielectric constant is ε _non when there is no seal liquid or ink between the electrodes, ε _s when there is a seal liquid between the electrodes, and ε _i when there is ink between the electrodes. When the ink liquid material is appropriately used, the following relationship can be approximately established. ε _non (approximately 1.0) <ε _s (2.0 to 50.0) <
ε _i (80 to) Therefore, if the determination is made based on the value of the relative dielectric constant, the state of the seal liquid and the ink can be easily detected. In this case, the seal liquid detection units 32A1 and 32A2 (detection elements)
May be a pair of electrodes spaced apart in a direction (preferably, a vertical direction) intersecting with the drawing direction, and various kinds of metals can be used as the electrodes. When used, a metal that is not easily affected by the ink and the sealing liquid is preferable. In the case of a metal which is easily attacked, it may be protected by coating the surface. In the case where a water-based ink is used, an insulating layer is preferably provided on the electrode.

The patterning of each ink ejection port 12 is performed by forming an electrode surface using various printing techniques and various deposition techniques such as sputtering, and then using various masking techniques such as photoresist and various etchings. A pair of electrodes can be installed inside.

The pair of electrodes is used as a seal liquid detection determination unit 34.
Can be determined by a known capacitance measurement method, and the result of the determination is connected to the seal liquid detection / determination unit 34, the seal liquid drawing means or the discharge means. 14 can be handed over.

In the present invention, the seal liquid 22A drawn into the discharge port 12 before the ink is discharged by the above-described drawing means may be separated from the seal liquid 22B around the discharge port 12. More specifically, as shown in the processing routine of FIG. 3, in step 52, at the time of discharging, first, the drawing-in means 24 operates to discharge the sealing liquid 22 to the discharge port 12.
The operation of pulling in is started. With the start of the retraction operation,
The seal liquid detecting means includes seal liquid detectors 32A1, 32A.
At A2, detection of the seal liquid 22 is started. Therefore, in step 54, it is determined whether the sealing liquid has been drawn to a desired position before the predetermined time has elapsed. If it is determined that the sealing liquid has not been drawn to the desired position even after the predetermined time has elapsed, the process proceeds to step 66.
On the other hand, when the sealing liquid 22 is drawn to a desired position before the predetermined time elapses, that is, as shown in FIG. 2A, the normally drawn sealing liquid 22A is separated from the surrounding sealing liquid 28B. To reach the desired position. When the seal liquid detecting means detects that the seal liquid has reached the desired position, in step 56, the ink is ejected. That is, the seal liquid detecting means also sends a signal to the discharge means 14 so that the ink in the ink discharge ports 12 is discharged together with the seal liquid. In this state, a plurality of ejections can be performed. At the time of discharge, the seal liquid 2 in the discharge port 12
2A does not have to be completely discharged together with the ink. In step 62, the operation of the drawing means is released, and the drawn ink (or ink and seal liquid) is released.
Is returned to the state before drawing (see FIG. 2D),
The seal liquid around the discharge port 12 seals the ink in the ink discharge port 12 again to prevent clogging. Steps 58, 64, and 66 will be described later.

Incidentally, the state in which the sealing liquid is drawn may be maintained, and a plurality of ejections may be performed in this state. That is, if it is determined in step 54 of FIG. 3 that the sealing liquid has been drawn to the desired position by the elapse of the predetermined time, a plurality of inks are ejected in step 56 while the drawing operation of the drawing means is performed. . As described above, when a plurality of inks are ejected while maintaining the state in which the seal liquid has been drawn, there is no need to perform the drawing operation for each discharge, and there is an advantage that the discharge frequency can be increased since the discharge interval is shortened. The holding can be performed by a method of holding the retraction means in the operating state and a method of holding the drawing means in a closed state. The retracted state may be maintained by both maintaining the retracting means 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 continues to consume power in the operating state, the drawn-in state can be maintained even when the draw-in means is deactivated, so that there is an effect that power can be saved. ing.

As described above, when the state in which the sealing liquid is drawn is maintained, it is determined in step 58 whether the maintained state can be maintained. That is, in the present embodiment, the position of the sealing liquid or the ink being held is monitored by the sealing liquid detecting means. Since it is determined whether the holding state cannot be maintained as in (c), it can be immediately detected that the holding state cannot be maintained,
By adjusting the retracted position according to the detection result, the reliability of the holding state is improved.

Further, if the holding state cannot be maintained according to this detection, in step 66, as described later, the drawing position is adjusted, that is, the sealing liquid drawing means is moved so that the sealing liquid is at a desired position. Control. The sealing liquid is controlled by the position adjusting means so as to be at a desired position. This makes it possible to properly return to the held state again. The position adjusting means may be any means capable of adjusting the positions of the sealing liquid and the ink in accordance with the result of the detecting means, and the means which can be used as the sealing liquid drawing means utilizing the negative pressure described above can be used. It is preferable that the amount of the sealing liquid drawn in by the position adjusting means is smaller than the amount of the sealing liquid drawn in by the sealing liquid drawing means, because precise position adjustment can be performed. Further, when there are a plurality of sensing elements, it is more preferable that the amount of pull-in can be varied according to the result of the sensing means.
More preferably, a positive pressure can be applied to return the excessively drawn seal liquid or ink. Further, the sealing liquid drawing means may also serve as the position adjusting means, and by also serving as such, the configuration of the apparatus becomes simpler, which leads to low cost and improved reliability. As a result, it is possible to properly return to the held state again.

If the seal liquid detecting means can also determine the presence / absence of ink, it is easy to detect an error that does not return to the state before the ink is drawn after the ink ejection is completed (see step 64).

That is, in order to detect an error that does not return to the state before the drawing, the ink (or the ink and the seal liquid) that has been drawn is returned to the state before the drawing as shown in FIG. The capacitance is monitored by the seal liquid detecting means. Refilling of ink is completed,
When the seal liquid is closed, as shown in FIG. 2 (e), and if there is a nozzle for which the seal liquid detecting means does not show an appropriate value, the seal liquid detecting means will use ink (or ink and seal liquid). It is determined that the seal liquid has not returned to the original position, and an error detection signal is issued in step 66, and the signal can be sent to a necessary part such as another maintenance means or a user.

These detection methods are also effective for detecting errors due to unexpected fluctuations and vibrations by constantly monitoring.

Here, processing after error detection (step 6)
6) will be described.

When an error is detected by the above error detection method, the error processing is passed to the error processing means. For example,
After the error is detected, the printing operation is stopped, the user is notified of the error detection, the user is prompted for maintenance, and the result of the error detection is passed to the position adjustment unit and the ejection unit 14,
There are methods such as adjusting the drawing-in amount and the return of the ink, and passing a result of the error detection to a maintenance unit or the like to perform a predetermined operation. These methods may be combined according to the result of the error detection. Note that it is preferable to perform an operation of retrying the error detection after performing the error processing because reliability is increased.

In the above, the case where one discharge chamber 16 has a pair of electrodes has been described as an example. However, if the seal liquid detectors 32A1 and 32A2 are provided at several places by a plurality of pairs of electrodes, the position where the seal liquid is drawn in It is also better to improve the detection accuracy, for example, by knowing the return position of the ink and the ink, and by making these precise adjustments.

In the case of the ink jet recording head 10 having a pull-in means for each ejection chamber 16, these detection methods can control the position of the seal liquid in each ejection chamber 16. By operating or canceling the retraction operation again, the normal discharge chamber 16
This is particularly effective because the maintenance of the user can be reduced.

The seal liquid detectors 32A1 and 32A2 are
The seal liquid is drawn into the desired position, that is, the seal liquid 22A located at the ink discharge port 12 and the seal liquid 22B positioned around the ink discharge port 12 are set at the position of the seal liquid when the seal liquid 22A is separated. Alternatively, as shown in FIG. 2A, the seal liquid-ink interface position at the time of proper retraction may be used. When the electrode is wide, the electrode may extend from the ink discharge port 12 to the position of the seal liquid when the seal liquid is separated. That is, there is no particular limitation as long as the presence or absence of the sealing liquid, preferably the presence or absence of the ink can be detected by measuring the capacitance.

The ink jet recording apparatus of the present invention comprises an ink ejection port 12, a seal liquid for sealing the ink ejection port 12, an ink ejection means 14 for ejecting ink from the ink ejection port 12 in accordance with an image signal, and a sealant. An ink jet recording apparatus having a liquid detecting unit and a sealing liquid drawing unit for drawing the sealing liquid. With this inkjet recording apparatus, an image is recorded by discharging ink corresponding to an image signal onto an image recording medium.

According to the present embodiment, the seal liquid 22B around the discharge port 12 is separated (separated) from the seal liquid 22A at the discharge port 12 and the seal liquid 22B around the discharge port 12. Therefore, it is possible to eliminate the effect of hindering ink ejection from the ink jet head, thereby reducing the resistance during ejection. 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.

Further, according to the present embodiment, the position of the seal liquid is detected, and the seal liquid of the discharge port 12 is discharged.
Since the liquid can be reliably separated from the surrounding seal liquid, it is possible to eliminate troubles such as ejecting ink in a state where the seal liquid is not released even under environmental fluctuations, unexpected vibrations and shocks. Further, it is possible to suppress a problem that the seal liquid is drawn too much and the seal liquid enters the heater section. 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.
Further, according to the present invention, since the resistance at the time of discharge is low, even when using a thick seal liquid or a seal liquid having a high viscosity, it is possible to achieve both the performance of preventing clogging and the discharge performance, It is also possible to design the ink jet head 10 and the ink jet recording apparatus to prevent clogging for a longer period.

Further, since clogging does not occur even after the long-term suspension, the ink discharge operation can be performed immediately when necessary, and the maintenance process after the long-term suspension can be reduced or omitted. 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.

Further, since the ink can be ejected by the ejection means 14 immediately after the seal liquid is surely released, the time lag is eliminated and the printing speed is improved.

Further, when holding the sealing liquid withdrawal, by detecting the position of the sealing liquid and adjusting the drawing position according to the detection result, the reliability of the holding state is improved.

Further, even when the sealing liquid is resealed to the ink discharge port 12 at the end of the drawing operation, the return of the ink can be confirmed by operating the seal liquid detecting means. Thus, there is no transition to the next ejection or suspension, and the ink ejection stability and reliability against clogging are improved.

Further, by operating the seal liquid detecting means at the time of a stop, an error can be detected when the seal liquid moves to a heater position where the seal liquid is drawn due to, for example, an environmental change or unexpected vibration. Reliability against clogging is improved.

Further, the seal liquid detectors 32A1, 32A
By using a plurality of electrode pairs for A2, the position of the seal liquid or the position of the ink liquid can be detected more accurately.

Since the seal liquid 22A located on the ink discharge port 12 and the surrounding seal liquid 22B are separated from each other, in the present embodiment, more than the seal liquid located on the ink discharge port 12 is drawn. That is, the ink ejection port 1
2 within a predetermined time so that the seal liquid is drawn in at least the amount of the seal liquid located on the upper side.
Is driven by a predetermined operation amount. By the way, JP-A-3-1
As described in Japanese Patent No. 32356, there is a method in which the sealing liquid is drawn by solidification shrinkage of hot melt ink. However, in the case of shrinkage during cooling and solidification, as in the present embodiment, the drawing amount required for partitioning is reduced. I can't get it. Further, 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 12 according to the drawing and is separated. Can not. That is, JP-A-3-
The contents described in JP 132356 and the contents of the present application are essentially different.

[0084]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

As shown in FIG. 4, the head 10 has an ink reservoir 18 inside, and an ink discharge means 14 is disposed in a discharge chamber 16 communicating with a discharge port 12 having a diameter of 40 μm. Further, on the wall surface of the ink reservoir 18, there is disposed a drawing means 24 including a piezoelectric member PZT layer 42 as a sealing liquid drawing means.

The sealing liquid 22 is 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 21 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 and a surface tension of 40 mN / s.
m, specific gravity 1.06.

The discharge means 14 is of the thermal ink jet type, and is constituted by providing a heater on the wall surface of the discharge chamber 16. The heater is configured by laminating a protective layer made of tantalum on a heating element layer made of polycrystalline silicon.
The heater is wired so that a predetermined signal is applied to the heater at a timing corresponding to the image signal by a signal applying unit (not shown).

The retraction means 24 including the piezoelectric member is provided with a PZ
The head 10 is formed by using a T (lead zirconate titanate) piezoelectric member, and is bent and deformed by applying a voltage to the first electrode 44 and the second electrode 40 provided on both sides of the PZT layer 42. Increase the volume of The pull-in means 24 includes a protective layer 48 of silicon oxide having a thickness of 1.0 μm formed by thermally oxidizing a silicon single crystal substrate, an elastic film 46 of zirconium oxide having a thickness of 0.8 μm formed by a sputtering method, Thickness formed by sputtering method
A first electrode 44 made of 2 μm platinum and a PZT layer 42 having a thickness of 1.0 μm formed by repeating a sol-gel method a plurality of times;
And a second electrode 40 made of platinum having a thickness of 0.1 μm and formed by a sputtering method. The pull-in means 24 sequentially forms a protective layer 48, an elastic film 46, a first electrode 44, a PZT layer 42, a second
After the electrodes 40 were stacked and formed, the silicon single crystal portion was removed by etching. In addition, the PZT layer 42 and the second electrode 40 can be patterned into a predetermined shape by photoresist and etching.
It is formed in a rectangle having a length of m and 800 μm. The wall of the ink reservoir 18 is formed by bonding the drawing unit 24 thus manufactured. When a voltage of 20 V is applied between the first electrode 44 and the second electrode 40, the ink reservoir 18 formed by the drawing unit 24 is formed. A concave flexure deformation of a maximum of 2 μm occurred at the center of the wall surface, and the volume of the ink reservoir 18 increased. When the inside of the head 10 was filled with ink and the ink was drawn in under these conditions, the ink was drawn from the ejection port 12 toward the inside of the head 10 to a position of 80 μm.

The seal liquid detecting section 3 of the seal liquid detecting means
2A1 and 32A2, a platinum layer having a thickness of 0.2 μm is formed on the back side of the discharge surface plate 50 using a silicon substrate by a sputtering method, and a pair of electrodes 32A1 is formed on each ink discharge port 12 by photoresist and etching. 32A2 was formed so as to be patterned. This surface was insulated and coated with a polyimide thin film so that the electrode did not come into direct contact with the ink. Next, the respective electrodes are connected to the seal liquid detection / judgment unit 34, and the seal liquid detection judgment unit 34 and the driver of the drawing-in unit and the ejection unit 14 are connected.
Connected the driver.

The ink ejection port 12 and the seal liquid detecting section 32
A1, 32A2 and the positional relationship between the ejection means 14 are as shown in FIG.
50um up to the end of 2A2, seal liquid detector 32A1,
The distance from the end of 32A2 to the end of the discharge means 14 became 50 μm.

Using the head 10 of this embodiment, the state of ejection was observed under magnification. The seal liquid was disposed in a film shape on the surface of the head 10 where the ejection ports 12 were arranged so as to have a thickness of 20 μm. First, the voltage applied to the piezoelectric member 42 from 0 V was gradually increased, and the head 10 was deformed so as to increase its internal volume. To the discharge port 12. Then, each of the seal liquid detecting sections 32A1, 3A
At 2A2, the presence of the sealing liquid at this position was confirmed, and at the same time, a signal indicating the completion of retraction was sent to the retraction means, and the retraction means was stopped. As a result, the drawn seal liquid is separated from the surrounding seal liquid. At the same time, the sealing liquid detecting means sends a signal of the end of the drawing to the drawing means and also sends a signal to the discharging means 14, and the heater which is the discharging means 14 receives the signal.
A pulse of V was applied for a period of 6 μs to eject ink. As a result, it was observed that ink droplets were stably ejected. When the voltage of the drawing means was released after the ejection, the ink in the ejection port 12 returned to the initial state, and the seal liquid around the ejection port 12 sealed the ink in the ejection port 12.

Further, this recording apparatus is used in a low-temperature environment (temperature
(C, 30% relative humidity) for 24 hours, and a printing test was performed in this low-temperature environment. As a result, it took longer for the seal liquid detecting means to detect the presence of the seal than in the normal temperature test. . However, the end of the drawing of the seal liquid was reliably detected, and the discharge timing was adjusted so that the discharge was possible immediately after the drawing was completed. 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. The reason why it took longer to detect than the normal temperature test was that the viscosity of the sealing liquid increased due to the low temperature environment,
This is probably due to the increased resistance at the time of retraction.

Further, the recording apparatus is used in a high-temperature environment (temperature 40
(24 ° C., 80% relative humidity) for 24 hours, and a printing test was performed in this high temperature environment. As a result, it took a shorter time than the normal temperature test until the seal liquid detecting means detected the presence of the seal. . Then, it was detected that the drawing-in of the seal liquid was completed, and the ejection timing was adjusted so that it could be ejected immediately after that.As a result, the printing time was shorter than in the previous test, and it was as clear as in the previous test. Printing was possible. 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. It is considered that the reason why the time before the detection is shorter than that at the time of the normal temperature test is that the viscosity of the sealing liquid is lowered due to the high temperature environment, and the resistance at the time of drawing is reduced.

Further, the ink jet recording head 1
0 while the seal liquid detecting means is operated,
After leaving in an environment of 30 ° C. and a relative humidity of 30% RH for 30 days, a print test was performed without performing any ordinary maintenance operation of the inkjet recording apparatus, and an output image was observed. No ejection failure due to clogging has occurred in the ink ejection port 12, and the printed image has no dot disturbance,
The same clear image was recorded as before. A print test was performed after leaving the recording head 10 similar to the recording head 10 of the present embodiment under the same conditions for 30 days except that the seal liquid detecting means was not operated, and a printing test was performed. And printing could only be partially performed. This was observed by observing the discharge port before performing the printing test, and it was found that this was caused by the seal liquid being drawn in too much. It is considered that this was due to unexpected vibration during the leaving.

For comparison, a head 10 similar to the head 10 of this embodiment is used except that the seal liquid detecting means is not provided, and the seal liquid is applied to the surface where the discharge ports 12 are lined up to a thickness of 20 μm. It was arranged in the form of a film. The condition of the drawing operation is such that the sealing liquid of all the ink discharge ports 12 is separated by the drawing operation test at room temperature.
The ejection conditions were the same as those of the head 10 of the embodiment,
When a print test of an image was performed in a room at room temperature (temperature: 25 ° C., relative humidity: 50%), 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 3
(0%) for 24 hours, and a printing test was performed in this low-temperature environment. When the ink was drawn in and discharged under the same drawing operation conditions as at room temperature, defective portions where no printing was performed were conspicuous, and only an unclear image was obtained. I couldn't. As a result of the discharge observation, it was found that due to the increase in the viscosity of the seal liquid due to low temperature, the pull-in operation was not completed completely even if the pull-in operation was performed under the same conditions at normal temperature, and the discharge could not be performed due to resistance with the surrounding seal liquid all right.

In a high temperature environment (air temperature 40 ° C., relative humidity 80
%) For 24 hours, and a printing test was performed in this high-temperature environment. When the ink was pulled out and discharged under the same pull-in operating conditions as at room temperature, defective portions where no printing was performed were conspicuous, and only an unclear image was obtained. Did not. As a result of the ejection observation, a large number of ink ejection ports 12 that cannot be ejected appear. As a result of the disassembly observation of the recording head 10, when the seal liquid viscosity decreases due to high temperature, the retraction operation is performed under the same conditions at normal temperature. , It was found that bubble formation could not be performed because the sealing liquid entered and adhered to the heater.

[0099]

As described above, according to the present invention, since the seal liquid in the ink discharge is detected, the seal liquid located at the ink discharge port is separated from the seal liquid located around the ink discharge port. Therefore, it is possible to grasp whether or not the seal liquid is located at the ink discharge port and to discharge the seal liquid positioned around the ink discharge port in a reliably separated state.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of an ink jet recording head according to an embodiment.

FIG. 2 is an explanatory diagram illustrating the operation of the present embodiment.

FIG. 3 is a flowchart illustrating a control routine of a seal liquid detection determination unit.

FIG. 4 is a configuration diagram of an inkjet recording head according to an embodiment.

[Explanation of symbols]

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

Continued on the front page (72) Inventor Yasufumi Suwabe 430 Green Tech Nakai, Nakai-cho, Ashigara-gun, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Yuji Suemitsu 430 Green Tech Nakai, Nakai-cho, Ashigara-kami, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. Person Tetsu Mohri 430 Green Tech Nakai-cho, Nakai-machi, Ashigara-gun, Kanagawa F-term in Fuji Xerox Co., Ltd. (reference) 2C056 EA17 EB08 EB29 EB51 EC08 EC26 EC32 EC63 HA05 HA16 HA17 JA24

Claims (18)

[Claims] An ink ejection port for ejecting ink; a seal 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; Sealing liquid drawing means for drawing the seal liquid into the ink discharge port so that the seal liquid located at the ink discharge port of the seal liquid and the seal liquid of the seal liquid positioned around the ink discharge port are separated from each other; An ink jet recording head comprising: a detection unit configured to detect a seal liquid in the ink discharge port. 2. The ink jet recording head according to claim 1, further comprising a position adjusting means for adjusting the positions of the seal liquid and the ink. 3. The ink jet recording head according to claim 2, wherein said sealing liquid drawing means also functions as said position adjusting means. 4. The ink jet recording head according to claim 1, wherein said detecting means detects the presence or absence of said seal liquid. 5. The ink jet recording head according to claim 1, wherein the detecting unit detects a position of the seal liquid. 6. An ink jet recording apparatus according to claim 1, wherein said detecting means includes a plurality of detecting elements disposed in said ink discharge port. head. 7. The ink jet recording head according to claim 6, wherein the plurality of detection elements are arranged in the ink ejection port so as to be separated from each other in a direction intersecting with a direction in which the seal liquid is drawn. 8. The ink jet recording head according to claim 6, wherein said detecting means includes at least a pair of detecting elements. 9. The ink jet recording head according to claim 8, wherein said detecting element is an electrode element. 10. The ink detecting device detects one of a resistance value between a plurality of electrode elements, a current amount flowing between the plurality of electrode elements, and a capacitance between the plurality of electrode elements. The ink jet recording head according to claim 9, which detects a seal liquid in the discharge port. 11. The ink jet recording head according to claim 9, wherein said detecting means detects the seal liquid in said ink discharge port by applying an AC voltage between a plurality of electrode elements. 12. The ink jet recording head according to claim 1, wherein the detecting means further detects the ink in the ink ejection port. 13. An ink jet recording apparatus comprising the ink jet recording head according to claim 1. 14. The ink jet recording apparatus according to claim 13, further comprising an error processing unit for performing an error process when a detection result of said detection unit is not a desired result. 15. The error processing includes displaying a warning, stopping a printing operation, adjusting the position of a seal liquid or ink position by the position adjusting means, displaying the warning and re-printing the ink position after the position adjustment. 15. The ink jet recording apparatus according to claim 14, which is at least one of detection. 16. An ink jet recording method for an ink jet recording apparatus having an ink jet recording head according to claim 13, wherein the sealing liquid is drawn before the ink is ejected, and at least one of the sealing liquid and the ink is drawn into a predetermined position. An ink jet recording method that detects whether or not it is. 17. The ink jet recording method according to claim 16, wherein the position adjusting means adjusts the position of the seal liquid or the ink in a state where at least one of the seal liquid and the ink is held. . 18. The ink jet recording method according to claim 16, wherein when returning at least one of the drawn-in sealing liquid and ink to the original state, it is determined whether or not the ink has returned to the original state. .