JP2003205615A - Ink-jet recording apparatus and ink-jet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink-jet recording apparatus capable of preventing decline of throughput at the time of recording, restraining wasteful consumption of an ink in the preliminary ejection, and maintaining nozzle state capable of ejecting ink droplets always stably, and an ink-jet recording method. <P>SOLUTION: In the ink-jet recording apparatus for executing a time sharing separation drive of ejecting ink droplets to a recording medium per block unit of a plurality of ejection openings arranged in a recording head and divided into sets of a plurality of pieces, the recording head is driven by a block driving time interval shorter than an ordinary block driving time interval in the case the recording density of recording data is less than a predetermined value while driving the recording head by the ordinary block driving time interval at the time of recording so as to increase meniscus surface vibration of the ejection openings. In the case the recording density of the recording data is the predetermined value or more, the recording head is again driven by the ordinary block driving time interval. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet recording apparatus and an inkjet recording method, and more specifically,
The present invention relates to an inkjet recording device and an inkjet recording method for removing thickened ink in a nozzle.

[0002]

2. Description of the Related Art A recording device having a function of a printer, a copying machine, a facsimile or the like, or a recording device used as an output device such as a composite electronic device including a computer, a word processor or the like, a workstation, etc. An image (including characters and symbols) is recorded on a recording medium such as paper or a thin plastic plate. The recording method of the recording device is, for example, an inkjet,
Wire dots, thermal transfer, laser, etc. may be mentioned. Among these recording methods, the inkjet method ejects minute granular ink droplets from each nozzle of the recording head based on an electrical recording signal, and ejects the ink droplets on a recording medium provided facing the nozzle. Characters, figures, etc. are recorded by landing. Further, in an inkjet printing apparatus generally called a serial type, the print head is scanned in a direction intersecting the transport direction of the print medium while facing the print medium, and ink is ejected to the print medium during this scan. One line is recorded, and then a predetermined amount of paper is fed. In this way, by repeating recording and paper feeding, recording can be performed on the entire recording medium. Further, in a line type recording apparatus that uses a recording head in which nozzles are arranged to be wider than the paper width of the recording medium, the recording head does not scan, and when the recording medium is arranged at a predetermined position, the recording head collectively records one line. And then a predetermined amount of paper feed (pitch feed) is alternately repeated to form an image on the entire recording medium.
Such an ink jet method has relatively low noise during recording, is capable of outputting a high-definition image, and has the advantage of being high-speed recording, and thus has been rapidly popularized in recent years.

By the way, the ink discharge mechanism in the recording head of the ink jet recording apparatus is as follows.
A discharge pressure generating element such as a piezoelectric element or an electrothermal converting element (hereinafter referred to as "heater") provided in the recording head is used to convert electric energy into mechanical energy and eject ink. In particular, a so-called thermal ink jet recording method is used in which the ink is boiled instantly by heating a heater and the pressure of bubbles generated at that time is used (Japanese Patent Application Laid-Open No. 61-61160)
No. 59911 to 59914), it is known that the apparatus can be downsized, and the recording head can be easily increased in density. In this thermal inkjet recording method, the volume of the ejected ink droplets is always kept stable without being affected by external factors such as environmental temperature, and the bubbles generated on the heater are used as ink to obtain a higher quality image. A method for communicating with the outside air at the time of discharging a droplet is disclosed in Japanese Patent Laid-Open No. 4-109.
40 to 10942. As a recording head for realizing this method, a recording head having a short distance between the heater and the ejection port (for example, 15 to 30 μm) is suitable.
When the distance between the heater and the discharge port is short, the generated bubbles are in stable communication with the atmosphere, and this distance almost determines the volume of the discharged ink droplets, which is also effective in ejecting small droplets. It is attracting attention as a method.

As the ink used in the ink jet recording apparatus, a water-based ink to which a dye having water as a solvent, an organic solvent, a surfactant and the like are added is currently the mainstream. In such water-based ink, volatile components such as water contained in the ink may evaporate with the passage of time and temperature. In particular, when the volatile components of the ink in the recording head evaporate during non-ejection, the ink viscosity, solvent composition, and dye concentration near the ejection port change. When ink is ejected in a state where this change has progressed further, a so-called clogging phenomenon in which ink is not ejected even when an ejection pulse is applied to the drive element of the nozzle occurs, and various characteristics of ejected ink droplets such as the ejection direction are This may cause instability or increase in dot density. In particular, this phenomenon is more likely to occur as the discharge diameter of the nozzle becomes smaller. Since a higher quality image is required for a photographic image or the like, the ink droplets ejected in recent years tend to be miniaturized, and the above-mentioned harmful effects tend to affect the image formed. In addition, if a water-resistant dye is used in the ink, or if a pigment dispersant or various additives for increasing color resistance or light resistance are added to the ink, the state of the ink during non-ejection tends to deteriorate. Therefore, there are cases where the above-mentioned adverse effects are likely to occur. In order to prevent such harmful effects,
Conventionally, the following methods have been implemented. A first method is to perform so-called preliminary ejection, in which the recording head is temporarily moved to a predetermined position other than the recording area before or during recording to eject a fixed amount of ink droplets from all ejection ports. Can be mentioned. Note that the preliminary ejection may be performed at an inconspicuous position in the recording area. Pre-ejection is executed before printing when printing is performed after a certain time has passed since the previous printing, or in the case of a multi-nozzle type print head where not all nozzles in the print head are always used. In addition, it is periodically executed during recording. In addition, suction processing may be performed together by a pump provided at a predetermined position. The ink consumption amount in this preliminary ejection is determined by the number of preliminary ejection pulses, the ejection amount of nozzles, and the number of nozzles. The number of preliminary ejection pulses is the nature of the ink, the nozzle shape, and the main scanning time in the inkjet recording apparatus. , Is appropriately set according to the pause time from the previous recording.

A second method is Japanese Patent Laid-Open No. 57-6157.
The method described in Japanese Patent No. 6 is mentioned. In this method, the piezoelectric vibrator is driven with a driving voltage that is low enough to prevent ink droplets from being ejected when the ink is not ejected, and the meniscus surface of the ejection port is vibrated to stir the ink in the nozzle and bring it to the vicinity of the ejection port. By replacing the concentrated ink having a high viscosity with the ink having a low viscosity existing in another portion, the viscosity distribution in the nozzle is relaxed.

FIG. 1 schematically shows how the viscosity distribution of the ink near the discharge port changes by this method. It is assumed that the higher the density of the ink in the figure, that is, the higher the density of the dots, the higher the viscosity of the ink. FIG. 10A shows a state before being vibrated, and since a certain time has elapsed since the previous recording, the ink near the ejection port has a high viscosity. When the piezoelectric element is driven to vibrate the meniscus surface to such an extent that the ink is not ejected in this state, the highly viscous ink that was concentrated in the vicinity of the ejection port as shown in FIG. Be pulled back to. Further, along with this, as shown in FIG. 6C, the low-viscosity ink existing in the vicinity of the ejection port at the back of the nozzle is pushed out to the ejection port side. By repeating this operation a plurality of times, the viscosity of the ink existing in the vicinity of the ejection port is averaged, as shown in FIG. 7D, and the viscosity is such that ink ejection can be performed stably.

In this case, the ink condition can be improved without discarding the ink, so that the ink is not wastefully consumed as compared with the first method.

[0008]

However, even the above-mentioned conventional method for eliminating the ejection failure due to the increase in the viscosity of the ink has the following problems.

In the first method, the smaller the ejection port diameter, the higher the degree of increase in the viscosity of the ink, and the corresponding increase in the number of preliminary ejections. Therefore, not only the amount of ink wasted in vain in addition to printing increases, but also the amount of ink consumed in this preliminary ejection increases, and the capacity of the waste ink tank for storing waste ink also increases. Furthermore, when preliminary ejection is performed during the recording operation, there arises a problem that the number of recordings on the recording medium per unit time, that is, the throughput decreases. In particular, since the number of preliminary ejections increases when multi-pass recording is performed with a recording head having a small ejection aperture, the throughput may be significantly reduced in a mode in which preliminary ejection is performed by moving to a preliminary ejection position. On the other hand, in the method of directly ejecting the recording head to the recording medium without moving the recording head to the preliminary ejection position, the image quality deteriorates.

Further, in the second method, it is costly to install the piezoelectric element only for vibrating the meniscus surface in the recording head of the thermal ink jet recording method in which the heater is used for discharging ink droplets. Is not valid. In addition, when recent highly volatile ink is used, it can be seen that the ink with high viscosity does not move in the vicinity of the ejection port only by vibrating the meniscus surface.

In view of such conventional problems, an object of the present invention is to prevent a decrease in throughput at the time of recording, to suppress wasteful consumption of ink in preliminary ejection, and to always stably eject ink droplets. It is an object of the present invention to provide an inkjet recording apparatus and an inkjet recording method that maintain such a nozzle state.

[0012]

The ink jet recording apparatus of the present invention ejects ink droplets onto a recording medium in a block unit in which a plurality of ejection openings arranged in a recording head are divided into a plurality of blocks. In an inkjet recording apparatus that performs division and separation driving, when the recording head is driven at a normal block driving time interval during recording,
A recording head drive switching means for driving the recording head at block drive time intervals shorter than the normal block drive time interval at regular intervals is provided.

According to the above configuration, when the recording head is time-divisionally separated and driven, the block drive interval is set to a time interval shorter than the block drive interval at the time of recording according to the recording density of the recording data. Since the vibration of the meniscus surface is increased, it is possible to prevent the viscosity of the ink in the nozzle from increasing. In addition, ink with high viscosity can be effectively discharged, and the state near the discharge port can be improved.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 2 is a perspective view of an ink jet recording apparatus which is an embodiment of the present invention.

The recording head unit 21 is formed by integrating a recording head and an ink tank. The recording head unit 21 is mounted on a carriage 22, and moves at the time of recording as the carriage moves along the guide line 22 in the direction of arrow a or b. The recording head 21 has nozzles arranged at a position facing the recording medium P. Further, the nozzle is used in the moving direction of the recording head (arrows a and b).
Direction) is arranged in a predetermined number of rows in a direction perpendicular to the direction. In this embodiment, the recording head is a multi-nozzle type head in which a total of 128 nozzles are arranged.

At the time of recording, the carriage 22 moves from the recording start position in the direction of arrow a, and ink droplets are ejected toward the recording medium P from each nozzle in accordance with the movement. When the carriage moves to the other end of the recording medium P, the conveyance roller 24 rotates by a fixed amount and conveys the recording medium P in the direction of arrow c. During this carrying operation, the carriage 22 moves in the direction of arrow b.
Direction, and returns to the recording start position. And again
Recording is performed by moving in the direction of arrow a. In this way, printing is performed on the entire recording medium by repeating the recording operation and the conveying operation of the recording medium.

In the recording head (not shown), ink passages extend from the respective ejection openings, and the ink passages communicate with the common liquid chamber. The common liquid chamber is connected to the ink tank, and the ink is supplied from the ink tank. The supplied ink normally fills up to the ejection port.
The portion where this ejection port and the ink path for each ejection port are combined corresponds approximately to the "nozzle". Further, a heater is provided corresponding to each discharge port. When recording, an electric signal is applied to a predetermined heater, and when the heater generates heat by the electric signal, the ink in the ink path instantaneously film-boils and bubbles are generated. A predetermined amount of ink is ejected from the ejection port by the generation pressure of the bubbles generated by the film boiling.

By the way, when the ink is not recorded for a long time, the viscosity of the ink in the vicinity of the ejection port is increased.
Change. Since the ejection direction of the ink having the increased viscosity becomes unstable and the ink is clogged in a severe state, it is necessary to regularly remove the ink having the increased viscosity. In the present embodiment, the recording head is periodically moved to the position of the preliminary ejection cap 25 provided outside the recording area, and preliminary ejection is performed with the preliminary ejection cap 25 covering the nozzle portion of the recording head. The ink with increased viscosity is removed.

Further, even during the recording operation, the blade 26
By passing the recording head before, wiping can be performed to remove dust and the like adhering to the ejection port surface.

By the way, in a multi-nozzle type recording head in which a plurality of nozzle rows are arranged, the pressure and the ink flow at the time of droplet ejection are transmitted to the surrounding nozzles through the common liquid chamber, and the meniscus surface of the nozzles is vibrated. A so-called crosstalk phenomenon may occur. Since crosstalk changes the ejection amount and refill time and causes the image quality to be impaired, various methods have been proposed and implemented for the nozzle shape and recording methods to reduce the effect of crosstalk during recording. ing.

On the other hand, if the crosstalk phenomenon is used in the reverse ejection, the pressure variation in the common liquid chamber is positively caused to vibrate the meniscus surface, thereby alleviating the increase in the ink viscosity in the vicinity of the ejection port. It is possible to quickly shift to a stable discharge state. Normally, crosstalk is easily affected by the nozzle shape and the distance between the nozzle and the ink supply port. However, in the case of a multi-nozzle head, what has the greatest effect on crosstalk is the number of pits that are driven simultaneously in succession. That is, as the number of pits driven simultaneously increases, the crosstalk phenomenon is more likely to occur. further,
It is generally known that the pressure and ink flow received by driving the adjacent nozzles have the greatest influence.

FIG. 3 shows a recording head 128 of the present embodiment.
It is a figure which shows the position change of the meniscus surface of a non-driving nozzle at the time of measuring the position of a stationary state as a reference, when the nozzle which is individual is driven every other nozzle.

It should be noted that time 0 in the figure is the drive start time of the drive nozzle. The position change of the meniscus surface from the end of the ejection port depends on the structure of the nozzle, the driving method, the structure of the ink chamber, etc., but the driving at this time fluctuates by about ± 2 μm as compared to the stationary meniscus, The position of "+" in the graph is the convex state of the meniscus surface, and the position of "-" is the concave state of the meniscus surface. From this figure, it can be seen that the meniscus surface of the non-ejection nozzle is vibrating. In other words, it is expected that due to the vibration of the meniscus surface, a phenomenon in which high-viscosity ink near the ejection port and low-viscosity ink near the common liquid chamber are mixed in the nozzle as shown in FIG. It

By the way, in many ink jet recording apparatuses including this embodiment, at the time of recording, not all the nozzles in the recording head simultaneously perform ejection operation. In general, the nozzles are divided into a plurality of drive blocks from the array, and a separate division drive method is used in which each drive block is driven in a time division manner during recording.

This divisional drive system is an effective system for downsizing the power source for driving the head and the power source members such as the flexible cable for the power source connector. Further, especially in the case of a recording head using a heater, in order to perform stable ejection in consideration of the characteristics of the heater and ink, it is necessary to make the fluctuation of the voltage value extremely small and to finely adjust the voltage value. Since it is not necessary to increase the capacity of the power supply because it is necessary, the split drive method is effective in avoiding this.

Normal separation / division driving of the recording head in this embodiment is performed as follows.

FIG. 4 is a diagram showing a normal timing table of heat signals of the heaters in the recording head.

The 128 nozzles arranged in the direction perpendicular to the arrows a and b in FIG. 2 are divided into 16 sections in units of 8 nozzles. In FIG. 4, a state in which the nozzle row is viewed from the front of the ejection port is shown in the center.

The timing table on the left side of FIG. 4 shows the time change of the heat signal of the heater corresponding to each nozzle of the nozzle row. As described above, the nozzles divided into 16 sections in units of 8 units each include 8 drive blocks Bi (i = 1 to 8) for each section.
Is divided into The driving of each heater is executed in block units. Specifically, among the sections, the nozzle having the earliest arrangement order, for example, the nozzle 1 in the first section and the nozzle 9 in the second section are the same drive block 1. Therefore, since the heaters corresponding to the nozzle 1 and the nozzle 9 respectively receive the heat signal at the same timing, the nozzle 1 and the nozzle 9 eject ink droplets at the same timing.

During recording, these blocks are sequentially driven from block 1. The time interval Tb of the drive block is calculated from the drive frequency fop as follows: Tb≈1 / fop / Nd
iv. When the ink drops are ejected at this time interval, the position intervals of the ink drops at a certain time are as shown on the right side in FIG.

It has been confirmed by experiments by the inventor that in such a recording head of the separated and divided drive system, if the time interval is shortened without changing the drive frequency, the crosstalk becomes more intense and the vibration of the meniscus surface becomes more intense. Has been done.

FIG. 5 is a diagram showing a heat signal timing table of each heater when the block driving time interval is shortened. The block time interval is set to a time Tb ′ (Tb ′ <Tb) shorter than the time interval Tb during normal recording, and the drive frequency is the same as during normal recording. In the figure, as you can see from the ink droplet position interval at a certain time on the right side, as the time interval becomes shorter,
The difference in ejection time between the adjacent nozzles in each section is short.

Therefore, during the actual recording by driving the recording head at the block time interval Tb shown in FIG.
If the block time interval is changed from Tb to Tb 'at a constant time interval and the block is driven, crosstalk becomes severe and ink is not ejected while the block time interval is driven at Tb'. The meniscus surface of the nozzle vibrates violently. Therefore, it is possible to reduce the ink viscosity in the vicinity of the ejection port of the nozzle that is not ejecting ink. Further, by performing the process of shortening the block time interval to Tb ′ a plurality of times periodically during the recording operation, it is possible to reduce the ink viscosity near the ejection ports of almost all nozzles.

As described above, the crosstalk causes the meniscus surface of the nozzle that is not ejecting ink to vibrate, while changing the ink ejection amount for the nozzle that is ejecting ink. Therefore, it is effective to limit the block time interval at a rate of 2 to 5% for each main scanning in order to deteriorate the image quality. When the block time interval is shortened regularly at this ratio, the image quality is hardly impaired even in the sensitivity evaluation.

Therefore, by performing the process of shortening the block time interval during the printing operation, the state of the nozzles can be kept better than in the case where this processing is not performed. Therefore, the preliminary ejection which is interrupted during the printing operation is performed. It is possible to reduce the number of times compared with the conventional method. By reducing the number of preliminary ejections, wasteful ink consumption can be suppressed and the recording throughput can be improved.

The process of changing the block time interval of this embodiment may be used in combination with the preliminary ejection process at the time of recording, or depending on the type and amount of recording data, the preliminary ejection may not be used at all. Good.

(Embodiment 2) In the present embodiment, the block time interval is switched from normal Tb to Tb 'during recording,
Then, a specific method of repeating returning to the original Tb again after a fixed time will be described.

The structure of the ink jet recording apparatus of this embodiment is the same as that of the first embodiment. However, it is assumed that the control unit (not shown) that controls the drive of each drive member is provided with the recording density detection unit and the block time interval change unit.

The recording density detecting section pre-reads the recording data and measures the recording density of the recording head in the recording data several lines ahead of the currently recorded line.

The block time interval changing unit has a recording density (ρshor) in which the recording density detected by the recording density detecting unit is constant.
If it is less than t), the block time interval is changed from the normal Tb to Tb 'and the recording operation is performed. further,
When the recording density detected by the recording density detecting means becomes equal to or higher than a certain recording density (ρlong), the block time interval is returned from Tb ′ to the original Tb again.

The recording density threshold value ρshort
And ρlong also include different values, and may be appropriately determined depending on the performance of the recording head and the ink.

The above processing will be described more concretely by using an example.

FIG. 6A is a diagram showing recording data for recording. If the direction indicated by the arrow is the recording direction,
The recording density changes as shown in the graph of FIG. Therefore, if the block time interval changes depending on the threshold value ρ of the recording density, the change in the block time interval becomes as shown in FIG.

When these FIGS. 6A to 6C are overlapped, it becomes as shown in FIG.

As described above, even if the block time interval is shortened and the crosstalk is increased in the portion where the recording density is low, the image is not so affected. Therefore, the number of preliminary ejections can be reduced without degrading the image quality.

By the way, in this embodiment, the threshold value ρ is set to the following value. Recording density of each color is 1 in 1-pass recording
When it is 0% or more, unevenness due to crosstalk tends to start to occur in an image recorded with a short drive interval. Therefore, when completing an image with 4-pass printing,
It is considered that unevenness starts to occur when the image density becomes 0 × 4 = 40% or more. Therefore, in this embodiment, the threshold value is 5
Set a value between% -30%, with 10% being most preferred.

The lower limit of Tb 'is the drive pulse,
The upper limit of Tb is (driving cycle) / (number of blocks).

When there is a concern that the viscosity of the ink in the nozzle will increase during the recording operation, specifically, a recording mode with a low recording density, for example, a multi-pass, economy, or fast mode nozzle that ejects simultaneously is used. This corresponds to the case of recording in a small recording mode or the case of recording recording data having a low recording density such as text data. If the block time interval is changed according to the change in the recording density as described above, it is possible to apply a means for reducing the viscosity in a targeted manner when such an increase in viscosity is concerned.

When the block time interval switching method of the present embodiment is used, not only when all nozzles do not eject, but when the number of ejecting nozzles is below an appropriate ratio, for example, 5% or less, with respect to all nozzles. It can be freely set, such as switching to.

(Others) The present invention is particularly provided with means for generating thermal energy as energy used for ejecting ink (for example, an electrothermal converter or a laser beam) even in the ink jet recording system. The present invention brings about excellent effects in a recording head and a recording apparatus of the type in which the state of ink is changed by the heat energy. This is because such a system can achieve high density recording and high definition recording.

Regarding the typical structure and principle thereof, see, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740.
What is done using the basic principles disclosed in 796 is preferred. This method is a so-called on-demand type,
It can be applied to any of the continuous type, but especially in the case of the on-demand type, it can be applied to the sheet holding the liquid (ink) or the electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recording information and giving a rapid temperature rise exceeding nucleate boiling, heat energy is generated in the electrothermal converter, and film boiling is caused on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal in a one-to-one correspondence
It is effective because bubbles can be formed inside. Due to the growth and contraction of the bubbles, the liquid (ink) is ejected through the ejection opening to form at least one droplet. It is more preferable to make this drive signal into a pulse shape, because the bubble growth and contraction are immediately and appropriately performed, so that the ejection of the liquid (ink) with excellent responsiveness can be achieved. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise on the heat acting surface are adopted, more excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the discharge port, the liquid passage, and the electrothermal converter (the linear liquid passage or the right-angle liquid passage) as disclosed in the above-mentioned specifications, US Pat. No. 4,558,333, US Pat. No. 4,558,333, which discloses a configuration in which a heat acting portion is arranged in a bending region.
The structure using the specification of No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration corresponding to the ejection portion is disclosed in JP-A-59-138461. That is, according to the present invention, recording can be surely and efficiently performed regardless of the form of the recording head.

Furthermore, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium that can be recorded by the recording apparatus. Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads or a configuration as one recording head integrally formed.

In addition, even in the case of the serial type as in the above example, the recording head fixed to the main body of the apparatus or the electrical connection with the main body of the apparatus or the ink from the main body of the apparatus by being attached to the main body of the apparatus. The present invention is also effective when a replaceable chip-type recording head that can be supplied or a cartridge-type recording head in which an ink tank is integrally provided in the recording head itself is used.

Further, as the constitution of the recording apparatus of the present invention, it is preferable to add ejection recovery means of the recording head, preliminary auxiliary means and the like because the effects of the present invention can be further stabilized. Specifically, heating is performed by using a capping unit, a cleaning unit, a pressure or suction unit for the recording head, an electrothermal converter or a heating element other than this, or a combination thereof. Examples thereof include a preliminary heating unit for performing the discharge and a preliminary discharge unit for performing discharge different from the recording.

Regarding the type or number of recording heads to be mounted, for example, only one is provided corresponding to a single color ink, or a plurality of inks having different recording colors and densities are supported. A plurality of pieces may be provided. That is, for example, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but it may be either the recording head is integrally formed or a plurality of combinations may be used. The present invention is also extremely effective for an apparatus provided with at least one of full-color recording modes by color mixing.

In addition, in the above-described embodiments of the present invention, the ink is described as a liquid, but an ink that solidifies at room temperature or lower and that softens or liquefies at room temperature may be used. Or, in the inkjet system, it is common to control the temperature of the ink itself within the range of 30 ° C. or higher and 70 ° C. or lower to control the temperature so that the viscosity of the ink is within the stable ejection range. Sometimes, a liquid ink may be used. In addition, the temperature rise due to thermal energy is positively prevented by using it as the energy of the state change of the ink from the solid state to the liquid state, or in order to prevent the evaporation of the ink, it is solidified and heated in the standing state. You may use the ink liquefied by. In any case, by applying thermal energy such as ink that is liquefied by applying thermal energy according to the recording signal and liquid ink is ejected, or that begins to solidify when it reaches the recording medium. The present invention can be applied to the case where an ink having a property of being liquefied for the first time is used. In this case, the ink is
JP-A-54-56847 or JP-A-60-7
As described in Japanese Patent No. 1260, it may be configured to face the electrothermal converter in a state of being held as a liquid or a solid in the concave portion or the through hole of the porous sheet. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, as the form of the ink jet recording apparatus of the present invention, besides the one used as an image output terminal of an information processing apparatus such as a computer, a copying apparatus combined with a reader or the like, and a facsimile apparatus having a transmission / reception function It may be a form or the like.

[0060]

By using the present invention, in the time-division separation drive type recording head, the block drive interval is set to a time interval shorter than the block drive interval during recording in accordance with the recording density of the recording data. Since the vibration of the meniscus surface is increased, it is possible to prevent the viscosity of the ink in the nozzle from increasing. Therefore, it is possible to reduce the number of preliminary ejections performed by interruption during the printing operation, and it is possible to improve the throughput. Further, it is possible to suppress the wasteful consumption of ink in the preliminary ejection and to maintain the state of the nozzle that can always stably eject the ink droplet.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a state near a discharge port, (a)
Is the state before vibration is applied to the meniscus surface,
(B)-(d) is a figure which shows the mode of a change after giving a vibration to a meniscus surface.

FIG. 2 is a perspective view showing the ink jet recording apparatus of the present embodiment.

FIG. 3 is a diagram showing a positional change of a meniscus surface of a nozzle which is not driven when an adjacent nozzle is driven.

FIG. 4 is a diagram showing a timing table of heat signals of a heater of a recording head during recording.

FIG. 5 is a diagram showing a timing table of heat signals of a heater of a recording head during preliminary ejection.

6A and 6B are diagrams showing a change in recording density and a change in block time interval with respect to print data, wherein FIG. 6A shows print data, FIG. 6B shows change in print density, and FIG. Of change, (d) is (a) (b) (c)
It is the figure which piled up the figure.

[Explanation of symbols]

21 Recording head unit 22 Guidelines 22 carriage 24 transport rollers 25 Pre-discharge cap 26 blades

Claims (8)

[Claims] 1. An ink jet recording apparatus for performing time-division separation driving of ejecting ink droplets onto a recording medium in a block unit in which a plurality of ejection openings arranged in a recording head are divided into a plurality of blocks. A recording head drive switching unit that drives the recording head at a block driving time interval shorter than the normal block driving time interval at regular intervals when the recording head is driven at a normal block driving time interval during recording. An ink jet recording apparatus comprising: 2. An ink jet recording apparatus for performing time-division separation drive of ejecting ink droplets onto a recording medium in a block unit in which a plurality of ejection openings arranged in a recording head are divided into a plurality of blocks. When the recording head is driven at a normal block driving time interval during recording, when the recording density of the recording data becomes less than a predetermined value, the block driving time interval shorter than the normal block driving time interval is used. An ink jet recording apparatus comprising a recording head drive switching means for driving a recording head. 3. A recording density detecting means for detecting a recording density of the recording data is further provided, and the recording head drive switching means is configured to perform the normal operation when the recording density detected by the recording density detecting means is less than a predetermined value. When the recording head is driven at a block drive time interval shorter than the block drive time interval of, and the recording density is equal to or higher than a predetermined value,
The ink jet recording apparatus according to claim 2, wherein the short block drive time interval is returned to a normal block drive time interval to drive the recording head. 4. The recording head drive switching means, when the recording density of recording data is less than a predetermined value, vibration of the meniscus surface of the ejection port that is not ejected among the plurality of ejection ports is normal ejection. 4. The ink jet recording apparatus according to claim 2, wherein the block driving time interval is shortened at an interval that is larger than vibration during operation. 5. The recording head drive switching means sets the ratio of driving the recording head at the short block time intervals to about 2% or more and less than 5% of the entire recording area. The inkjet recording device according to any one of 1. 6. The recording head comprises an electrothermal converter corresponding to each ejection port, and a predetermined amount of ink droplets are ejected by the pressure generated by the bubbles formed in the ink due to heat generation of the electrothermal converter. The ink jet recording apparatus according to any one of claims 1 to 5, wherein: 7. An inkjet using an inkjet recording apparatus that performs time-division separation driving in which ink droplets are ejected onto a recording medium in a block unit in which a plurality of ejection openings arranged in a recording head are divided into a plurality of blocks. A recording method, wherein when the recording head is driven at a normal block driving time interval at the time of recording, the recording head is driven at a block driving time interval shorter than the normal block driving time interval at regular intervals. An ink jet recording method comprising a recording head drive switching step of 8. An ink jet recording apparatus using an ink jet recording apparatus for performing time-division separation driving in which ink droplets are ejected onto a recording medium in a block unit in which a plurality of ejection openings arranged in a recording head are divided into a plurality of blocks. A recording method, wherein when the recording head is driven at a normal block drive time interval during recording, the recording data is shorter than the normal block drive time interval when the recording density of the recording data becomes less than a predetermined value. An inkjet recording method comprising a recording head drive switching step of driving the recording head at block drive time intervals.