JPH11192723A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress unnecessary ink consumption by providing means for recovering an ink jet head and varying the number of ink jetting times in the recovery process for next recording depending on the previous recording state of the ink jet head. SOLUTION: The head station of an image forming apparatus comprises long line heads H for four colors each having a linear array of a plurality of recording elements, and corresponding recovery units R. Each recovery unit R has a recovery tub 21 filled with an absorber 22 of such size as covering the jet port lace of the line head H. Recovery process is performed by jetting ink, or the like, preliminarily from the recording element group of the line head H under a state where the cap 23 of the recovery unit R is applied tightly to the jet port face of the line head H, and the recovery process is controlled to vary the number of ink jetting times in the recovery process for next recording depending on the previous recording state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for performing recording by an ink jet system.

[0002]

2. Description of the Related Art In an image forming apparatus of an ink jet system, dust such as paper dust sometimes adheres to a nozzle surface of an ink jet head (hereinafter, also simply referred to as a head) for printing. In addition, non-printing nozzles that do not eject ink increase the viscosity of the ink due to evaporation of water or volatile components in the ink, and the ink cannot be actually ejected at the printing stage or hinder the ejection. (Hereinafter referred to as non-ejection). In addition, when printing is performed by ejecting ink from the nozzles of the head, mist-like ink droplets smaller than the main droplet called mist fly in addition to the main droplet for landing on the recording paper to form an image, and the head When the ink adheres to the nozzle surface and grows to cover the nozzle, the covered nozzle may be in a non-ejection state.

For this reason, in order to solve the above-mentioned problem, a recovery process is conventionally performed before printing.
In the recovery process before printing, first, after the nozzle surface of the head is covered with caching means, thickened ink is ejected by preliminary ejection performed by applying a constant drive signal to each ejection energy generating means in all nozzles. Then, the inside of the nozzle is replaced with fresh ink. After performing the preliminary ejection, the nozzle surface of the head is wiped with a blade to wipe off ink droplets such as dust and mist attached to the nozzle surface, which grow and cover the nozzle. This wiping causes the ink to be scraped out of the head nozzles.
Therefore, a small amount of preliminary ejection is performed again to adjust the inside of the head nozzle.

[0004]

However, since the number of ink ejections in the preliminary ejection in the conventional recovery process is always constant, the number of ejections is more than necessary even when the number of prints is small and the head nozzles themselves are not so dirty yet. May perform preliminary ejection. Therefore, there is a disadvantage that the consumption of ink is increased.

SUMMARY OF THE INVENTION It is an object of the present invention to perform an ink jet type image forming apparatus at a value which satisfies the condition of the number of preliminary ejections to be performed in a recovery process before recording necessary for normal recording.

[0006]

In order to achieve the above object, the present invention relates to an image forming apparatus for forming an image using an ink jet head for discharging ink onto a recording medium, wherein the image forming apparatus is provided for recovering the ink jet head. Recovery means, and control means for changing the number of ink ejections in the recovery processing before the next printing in accordance with the previous printing state of the ink jet head.

Here, the control means controls the number of recordings, the time required for recording, the number of ink ejections, the time elapsed since the previous recording, the temperature and humidity in the use environment, and the recovery processing performed before the next recording. The number of ink ejections is changed.

With such a configuration, the next preliminary ejection can be performed with the optimum number of ejections, and unnecessary consumption of ink can be suppressed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic perspective view showing an ink jet printing apparatus as one embodiment of the image forming apparatus of the present invention.

In FIGS. 1 and 2, reference numeral 1 denotes an image forming apparatus, 2 denotes a feeder cover for storing cut paper as a recording medium, and 3 denotes a head station, which will be described later, and a transport section for cut paper. An upper cover 4 for opening and closing, a front cover 4 for opening a tank for storing ink as a liquid to be supplied to a head of a head station described later, and a switch 5 for a power supply of the printing apparatus Reference numeral 6 denotes an operation panel for setting and changing an operation environment in the printing apparatus.

Next, a schematic configuration of the above-described head station will be described with reference to FIGS. 2 (a) and 2 (b).

FIG. 2A is a schematic front view showing the internal structure of the ink jet printing apparatus shown in FIG.
FIG. 2B is a schematic cross-sectional view of a part of the ink jet head as the liquid discharge head shown in FIG. 2A and a recovery unit as recovery means for storing ink or the like as liquid preliminarily discharged from the head. It is a side view.

The head station according to the present embodiment comprises a long type ink jet line head (hereinafter, referred to as a line head) H in which a plurality of recording elements are linearly arranged in parallel with each other in a direction orthogonal to the cut sheet transport direction. Are arranged at equal intervals. Specifically, the four color line heads H include a yellow line head Y, a magenta line head M, a cyan line head C, and a black line head K. As shown in FIG. 2B, each line head H is provided with a heat radiating section 20 so as not to affect the image formation by the heat generated from the thermal energy generator in the printing element (not shown) due to the ink discharge.
, And heat is quickly diffused by a fan (not shown).

As shown in FIG. 2A, a transport unit V for transporting the cut sheet at a constant speed toward the recording position of the line head H is provided below the head station. Have been. The cut sheet on which the image is formed by the head station is carried out onto the stacker S by the transport unit V.

Below the transport unit V, a tank portion T for storing dedicated ink supplied to each line head H is detachably fixed.

As shown in FIG. 2B, each line head H is provided with a corresponding recovery unit R. As shown in FIG. 2A, the recovery unit R is specifically composed of a yellow recovery unit Yo, a magenta recovery unit Mo, a cyan recovery unit Co, and a black recovery unit Ko.

Each recovery unit R has a size enough to cover the discharge port surface of the line head H, an absorber 22 filled in the recovery tub 21, and projects from the upper part of the recovery tub 21. And a cap portion 23 made of an elastic material covering the periphery of the discharge port surface of the line head H, and a wiper made of an elastic material near the cap portion 23 and reaching above the discharge port surface of the line head H 24. Absorber 2 of this recovery unit R
The waste ink preliminarily ejected from the line head 2 is sent to a tank (not shown) as appropriate so as not to overflow from the recovery tub 21.

Next, the procedure of the recovery processing operation for the recording element will be described with reference to FIG.

FIGS. 3A to 3C are schematic side views showing a part of a series of recovery processing operations in a sectional view. First, FIG.
As shown in FIG. 3A, the line head H is maintained in order to maintain a predetermined distance between the upper surface of the cut sheet conveyed to a conveyance unit not shown in the drawing and the discharge port surface f of the line head H.
Has descended to the vicinity of the transport unit. At this time, a cover 30 for covering the absorber 22 in the recovery tub 21 is mounted on the cap 23 of the recovery unit R.

Next, as shown in FIG. 3 (b), after raising the only line head H in the arrow Y ₁ direction, FIG
(C), the cause submerge the recovery unit R to the bottom side of the discharge port surface f of the line head H is moved in the direction of arrow X _1. The cover 30 is removed simultaneously with the movement of the recovery unit R. Thereafter, in a state where the cap 23 of the recovery unit R is in close contact with the ejection port face f of the line head H, ink or the like is preliminarily ejected from the recording element group of the line head H by control means such as a CPU (not shown).

In the present invention, the conditions of the preliminary ejection in the recovery process for performing normal printing are determined according to various conditions in the preceding printing. Here, the printing conditions that affect the preliminary ejection conditions include, for example, the number of prints, the time required for printing, the number of ink discharges, the time elapsed since printing, the temperature and humidity in the use environment, and the like.

The ink accumulated in the absorber 22 in the recovery tub 21 is removed by suction to a waste ink tank (not shown).

The above-mentioned preliminary ejection means that if there is a high possibility that the physical properties such as the viscosity of the ink in the ink flow path of the recording element have changed, image formation is performed in order to remove such extraneous matter. This is a recovery operation in which ink is forcibly ejected into the absorber 22 by a signal irrelevant to the above.

Next, referring to FIGS. 4 and 5, FIG.
An example of a drive mechanism capable of performing the operation of the line head H and the operation of the recovery unit R shown in (a) to (c) will be described.

FIG. 4 is a schematic perspective view showing the relationship between the line head and the recovery tub unit in one embodiment of the image forming apparatus of the present invention.

The line head H used in the present embodiment is preferably provided with a means (described later) for generating thermal energy as energy used for performing ink ejection, but is not limited to this. Instead, one provided with an electromechanical transducer such as a piezo element may be used. Further, in the present embodiment, heads are separately provided for each color of ink as a liquid, and the plurality (four in the present embodiment) of the heads H are arranged in a frame body with their ejection ports facing downward. Are integrally connected and held by a head holder 110. The head H is held together as is suspended by a suspension system (not shown), and is always biased upward (arrow Y ₁ direction), for example, by urging means such as a spring (not shown). On the other hand, the head motor 111 is connected to a front side and a rear side (not shown) of the head holder 110 via a plurality of gears, a head drive shaft 112, and the like.
Are driven respectively. Here, when the head drive shaft 112 is rotated in the direction of the arrow (counterclockwise) in the figure by the head motor 111, the wire 113
Also moved, the head holder 110 is pushed downward against the urging force (the arrow Y ₂ direction). Conversely, when the head drive shaft 112 rotates in the clockwise direction in the drawing, the head holder 110 rises upward (arrow Y ₁ direction) by the biasing force.

An ink tank (both not shown) as an ink supply means for storing ink to be supplied is connected to each head H via a tube 3.

Under such a head H, a recovery unit R for recovering the ejection performance can be sunk. The recovery unit R is for humidifying the head H and holding excess ink, and is slidably mounted on the recovery plate 115. This sliding mechanism will be described with reference to FIG. FIG. 5 is an enlarged schematic perspective view showing a recovery unit in the image forming apparatus shown in FIG.

The recovery unit R, which is a storage unit that constitutes a part of the recovery unit, has a slide shaft 117 disposed at an edge of the recovery plate 115 via a guide holding unit 116 provided at one edge. And a roller 118 is attached to the other edge of the recovery unit R. Therefore, the recovery unit R is slidable in the direction of arrow X ₁ or X ₂ direction in FIG. The recovery motor 119 drives the recovery unit R via a plurality of gears, a recovery tub drive shaft 120, a pinion gear 121, and a rack 122 provided at one edge of the recovery unit R in the sliding direction.

[0031]

Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1] In the printing apparatus shown in FIG. 1, the time during which the head nozzle surface is exposed to the air is determined by the number of recordings in one recording. , The progress of thickening of the ink in the non-printing nozzle is also determined.

In this embodiment, as shown in FIG. 6, when the number of recordings P at one time is less than 10, the increase in the viscosity of the ink in the head nozzles is considered to have hardly progressed. In the state where the process is not performed, each nozzle eliminates non-ejection by preliminary ejection within 50 shots. However, when the number of recordings is less than 10 in consideration of the safety factor (S101), the number of preliminary ejections in the recovery process before recording is reduced The number is set to 100 (S102).

Next, when the number of recordings at one time is 10 or more and less than 50 (S103), the number of preliminary ejections in the recovery process before recording is set to 200 (S104), and the number of recordings at one time is 50 or more. If the number is less than 100 (S105), the number of preliminary ejections in the recovery process before recording is set to 1000 (S1).
06) When the number of recordings per recording is 100 or more, the number of preliminary ejections in the recovery processing before recording is set to 2,000 (S)
107).

In this embodiment, by performing the preliminary ejection in accordance with the table of the number of recordings in the previous recording and the number of preliminary ejections, it is possible to maintain a normal head state at the time of recording.

In this embodiment, four tables are used as an example. However, it is needless to say that the number of prints, the number of preliminary ejections, and the number of tables are not limited to those in this embodiment.

[Embodiment 2] In the printing apparatus shown in FIG. 1, the time during which the head nozzle surface is exposed to the air is determined by the printing time in one printing operation. The progress of the thickening of the ink in the non-printing nozzle is also determined.

In the present embodiment, as shown in FIG. 7, when one recording time t is less than 10 seconds, it is considered that the viscosity of the ink in the head nozzle hardly progresses. In the state where the printing is not performed, each nozzle eliminates the non-ejection in the preliminary ejection within 50 shots. However, when the recording time is less than 10 seconds in consideration of the safety factor (S201), the number of preliminary ejections in the recovery process before the recording is reduced to 100. A call is issued (S202).

Next, when one recording time is 10 seconds or more and less than 30 seconds (S203), the number of preliminary ejections in the recovery process before recording is set to 200 (S204), and one recording time is 30 seconds or more. If the time is less than 60 seconds (S205), the number of preliminary ejections in the recovery process before recording is set to 1000 (S20).
6) If one recording time is 60 seconds or more, the number of preliminary ejections in the recovery process before recording is set to 2000 (S20).
7).

In this embodiment, by performing the preliminary ejection in accordance with the table of the recording time in the previous recording and the number of preliminary ejections, a normal head state can be maintained during the recording.

In this embodiment, four tables are taken as an example, but it goes without saying that the printing time, the number of preliminary ejections, and the number of tables are not limited to this embodiment.

[Embodiment 3] In the printing apparatus shown in FIG. 1, the progress of thickening of the ink in the non-printing nozzles in the head changes during printing depending on the number of inks ejected from each head in one printing. I do. The occurrence of recording failure is determined by the progress of the thickening of the ink in the head non-printing nozzles.

In this embodiment, as shown in FIG. 8, when the number E of ink ejected from each head in one recording is 100,000 or more, it is necessary that the viscosity of the ink in the head nozzle hardly progresses. Since it is conceivable, each nozzle has no non-ejection in preliminary ejection within 50 shots in a state where the recovery process before recording is not performed. However, in consideration of the safety factor, the number of ink ejections of each head in one recording is 100. 2,000 shots or more (S30
1), the number of preliminary ejections in the recovery process before recording is set to 100 (S302).

Next, when the number of ink ejections from each head in one recording is 10,000 or more and less than 100,000 (S303), the number of preliminary ejections in the recovery process before recording is set to 500 (S304). If the number of ink ejections from each head in one recording is 1,000 or more and less than 10,000 (S305), the number of preliminary ejections in the recovery process before recording is set to 1,000 (S306). If the number of ink ejections from each head in one recording is less than 999, the preliminary ejection number for recovery before printing is set to 2,000 (S30).
7).

In this embodiment, by performing preliminary ejection in accordance with the table of the number of ejections from the nozzles of each head and the number of preliminary ejections in the previous recording, a normal head state can be maintained during recording.

In this embodiment, four tables are used as an example. However, it goes without saying that the number of printed sheets, the number of preliminary ejections, and the number of tables are not limited to those in the embodiment.

[Embodiment 4] In the printing apparatus shown in FIG. 1, the progress of thickening of the ink in the non-printing nozzles in the head changes during recording depending on the use environment temperature.

In this embodiment, as shown in FIG. 9, when the use environment temperature _TP is 25 ° C. or more and less than 30 ° C. and the recording time is 10 seconds, it is considered that the thickening of the ink in the head nozzle hardly progresses. Therefore, in the state where the recovery process before recording is not performed, each nozzle has no ejection failure in preliminary ejection within 100 shots. However, considering the safety factor, the use environment temperature is 25 ° C. or more and less than 30 ° C., and the recording time is 10 seconds. In the case of (S401), the number of preliminary ejections in the recovery process before recording is set to 200 (S401).
402).

Next, the operating environment temperature is 20 ° C. or more and 25 ° C.
In the case where the temperature is lower than 0 ° C. and the recording time is 10 seconds (S403), the number of preliminary ejections in the recovery process before recording is set to 400 (S40)
4) If the use environment temperature is 15 ° C. or more and less than 20 ° C. and the printing time is 10 seconds (S405), the number of preliminary ejections in the recovery processing before recording is set to 1,000 (S406), and the use environment temperature is 15 ° C. If the recording time is less than 10 seconds, the number of preliminary ejections in the recovery process before recording is set to 2000 (S407).

In this embodiment, by performing the preliminary ejection in accordance with the table of the ambient temperature and the number of preliminary ejections, it is possible to maintain a normal head state during recording.

In this embodiment, four tables have been described as an example. However, in the present invention, it is needless to say that the environmental temperature range, the printing time, the number of preliminary ejections, and the number of tables are not limited to the embodiments.

[Embodiment 5] In the printing apparatus shown in FIG. 1, during recording, the progress of thickening of the ink in the non-printing nozzles in the head changes depending on the operating environment humidity.

In this embodiment, as shown in FIG. 10, when the operating environment temperature is 25.degree.
When the printing time is 0% or more and the printing time is 10 seconds (S501), it is considered that the thickening of the ink in the head nozzles hardly progresses. Although non-discharge is eliminated by discharge, the number of preliminary discharges is set to 200 in consideration of the safety factor (S50).
2).

Next, the operating environment humidity H is not less than 60% and not more than 80%.
If the print time is less than 10 seconds (S503), the number of preliminary ejections in the recovery process before recording is set to 400 (S50).
4) If the use environment humidity H is 40% or more and less than 60% and the printing time is 10 seconds (S505), the number of preliminary ejections in the recovery process before recording is set to 1000 (S506), and the use environment humidity H is 40%. If the printing time is less than 10 seconds, the number of preliminary ejections for recovery before printing is set to 2000 (S507).

In the present embodiment, by performing the preliminary ejection in accordance with the table of the environmental humidity and the number of preliminary ejections, it is possible to maintain a normal head state during recording.

In this embodiment, four tables have been described as an example. However, it is needless to say that the present invention is not limited to the embodiment in terms of the environmental humidity range, the printing time, the number of preliminary ejections, the environmental temperature, and the number of tables.

[Embodiment 6] In the printing apparatus shown in FIG. 1, the viscosity of the ink in the head nozzles is increased by leaving it in the recording standby state. The progress of the thickening of the ink is determined.

In this embodiment, the idle time t in the recording standby state
_{If 0} is less than 10 minutes (S601), it is considered that the increase in the viscosity of the ink in the head nozzles hardly progresses. However, the number of preliminary ejections is set to 200 in consideration of the safety factor (S602).

Next, the idle time t _{0 in the} recording standby state is set to 10
If the time is less than 30 minutes (S603), the number of preliminary ejections in the recovery process before printing is set to 400 (S604). If the idle time t _{0 in the} printing standby state is 30 minutes or more and less than 60 minutes (S605), printing is performed. The number of preliminary ejections in the previous recovery process is set to 800 (S606), and when the idle time t _{0 in the} recording standby state is 60 minutes or more, the number of preliminary ejections in the recovery process before recording is set to 2,000 (S607). .

In this embodiment, the idle time t in the recording standby state
By performing preliminary ejection in accordance with the table of ₀ and the number of preliminary ejections, a normal head state can be maintained during recording.

In this embodiment, four tables are taken as an example. However, in the present invention, it goes without saying that the standby time, the number of preliminary ejections, and the number of tables are not limited to the embodiment.

Although the above six embodiments have been described, each of the above embodiments may be used alone or in combination. Further, in the above embodiment, the number of preliminary discharges is determined from the table, but the number of preliminary discharges may be determined by calculation under each condition.

In the present invention, a head nozzle is a concept including a discharge port from which ink is discharged and an ink flow path communicating with the discharge port. It means a plane including a plurality of ejection openings in a row. When a printing element is called, the printing element includes the nozzle and a heater as a thermal energy generating element arranged in the ink flow path. .

(Others) It should be noted that the present invention includes a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for discharging ink, particularly in an ink jet recording system. An excellent effect is obtained in a recording head and a recording apparatus of a type in which the state of ink is changed by the thermal energy. This is because according to such a method, it is possible to achieve higher density and higher definition of recording.

The typical configuration and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method is a so-called on-demand type,
Although it can be applied to any type of continuous type, in particular, in the case of the on-demand type, it can be applied to a sheet holding liquid (ink) or an electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recorded information and providing a rapid temperature rise exceeding nucleate boiling, heat energy is generated in the electrothermal transducer, and film boiling occurs on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal on a one-to-one basis.
This is effective because air bubbles inside can be formed. The liquid (ink) is ejected through the ejection opening by the growth and contraction of the bubble to form at least one droplet. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As the configuration of the recording head, in addition to the combination of the discharge port, the liquid path, and the electrothermal converter (linear liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned respective specifications, U.S. Pat. No. 4,558,333 and U.S. Pat. No. 44,558 which disclose a configuration in which a heat acting portion is arranged in a bending region.
A configuration using the specification of Japanese Patent No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Application Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an aperture for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration is based on JP-A-59-138461, which discloses a configuration corresponding to a discharge unit. That is, according to the present invention, recording can be reliably and efficiently performed regardless of the form of the recording head.

Further, 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 on which a recording apparatus can record. 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 integrally formed recording head.

In addition, even in the case of the serial type as described above, the recording head fixed to the apparatus main body or the electric connection with the apparatus main body and the ink from the apparatus main body can be provided by being mounted on the apparatus main body. 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 provided integrally with the recording head itself is used.

Further, it is preferable to add ejection recovery means for the recording head, preliminary auxiliary means, and the like as the constitution of the recording apparatus of the present invention since the effect of the present invention can be further stabilized. If these are specifically mentioned, the recording head is heated using capping means, cleaning means, pressurizing or suction means, an electrothermal transducer, another heating element or a combination thereof. Pre-heating means for performing the pre-heating and pre-discharging means for performing the discharging other than the recording can be used.

The type and number of recording heads to be mounted are, for example, different from those provided with only one ink corresponding to a single color ink and those corresponding to a plurality of inks having different recording colors and densities. A plurality may be provided. That is, for example, the printing mode of the printing apparatus is not limited to a printing mode of only a mainstream color such as black, but may be any of integrally forming a printing head or a combination of a plurality of printing heads. The present invention is also very effective for an apparatus provided with at least one of the recording modes of full color by color mixture.

In addition, in the embodiments of the present invention described above, the ink is described as a liquid. However, an ink which solidifies at room temperature or lower and which softens or liquefies at room temperature may be used. In general, the ink jet method generally controls the temperature of the ink itself within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. Sometimes, the ink may be in a liquid state. In addition, in order to positively prevent temperature rise due to thermal energy by using it as energy for changing the state of the ink from a solid state to a liquid state, or to prevent evaporation of the ink, the ink is solidified in a standing state and heated. May be used. In any case, the application of heat energy causes the ink to be liquefied by the application of the heat energy according to the recording signal and the liquid ink to be ejected, or to start solidifying when it reaches the recording medium. The present invention is also applicable to a case where an ink having a property of liquefying for the first time is used. In such a case, the ink
JP-A-54-56847 or JP-A-60-7
As described in Japanese Patent Publication No. 1260, it is also possible to adopt a form in which the sheet is opposed to the electrothermal converter in a state where it is held as a liquid or solid substance in the concave portion or 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, the form of the ink jet recording apparatus of the present invention is not limited to those used as image output terminals of information processing equipment such as computers, copying apparatuses combined with readers and the like, and facsimile apparatuses having a transmission / reception function. It may take a form.

[0073]

As described above, according to the present invention,
In the image forming apparatus, the number of preliminary ejections is determined in accordance with conditions such as the state at the time of the previous recording, the standby time since the previous recording, etc., so that the appropriate number of ejections can be used to prevent non-ejection due to dust and increase the viscosity of the ink in the head nozzles. The defect can be eliminated, and unnecessary consumption of ink can be suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an inkjet printing apparatus as one embodiment of an image forming apparatus of the present invention.

FIG. 2A is a schematic front view showing the internal structure of the ink jet printing apparatus shown in FIG. 1, and FIG.
FIG. 2 is a schematic side view showing a cross-sectional view of a part of an ink-jet head serving as a liquid discharge head shown in FIG. 1A and a recovery unit serving as recovery means for storing ink and the like as liquid preliminarily discharged from the head.

FIGS. 3 (a) to 3 (c) are schematic side views showing a part of a series of recovery processing operations in cross section.

FIG. 4 is a schematic perspective view showing a relationship between a line head and a recovery tub unit in one embodiment of the image forming apparatus of the present invention.

5 is an enlarged schematic perspective view showing a recovery unit in the image forming apparatus shown in FIG. 4;

FIG. 6 is a flowchart illustrating control of preliminary ejection in Embodiment 1 of the image forming apparatus of the present invention.

FIG. 7 is a flowchart illustrating control of preliminary ejection in Embodiment 2 of the image forming apparatus of the present invention.

FIG. 8 is a flowchart illustrating control of preliminary ejection in Embodiment 3 of the image forming apparatus of the present invention.

FIG. 9 is a flowchart illustrating control of preliminary ejection in Embodiment 4 of the image forming apparatus of the present invention.

FIG. 10 is a flowchart illustrating control of preliminary ejection in Embodiment 5 of the image forming apparatus of the present invention.

FIG. 11 is a flowchart illustrating control of preliminary ejection in Embodiment 6 of the image forming apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Feeder cover 3 Upper cover 4 Front cover 5 Switch part 6 Operation panel H Ink jet head (liquid ejection head) P Liquid crystal panel 110 Head holder 111 Head motor 112 Drive shaft 113 Wire 115 Recovery plate 117 Slide shaft 118 Roller 119 Recovery motor 120 Recovery tub drive shaft 121 Pinion gear 122 Rack

Claims (11)

[Claims] 1. An image forming apparatus for forming an image using an ink jet head for discharging ink onto a recording medium, comprising: a recovery unit for recovering the ink jet head; And a control means for changing the number of ink ejections in a recovery process before the next recording. 2. The image forming apparatus according to claim 1, wherein the control unit changes the number of ink ejections in a recovery process before the next printing in accordance with the number of prints of the previous printing. 3. The image forming apparatus according to claim 1, wherein the control unit changes the number of ink ejections in a recovery process before the next printing according to a time required for printing of the previous printing. 4. The image forming apparatus according to claim 1, wherein the control unit changes the number of ink ejections in a recovery process before the next printing according to the number of ink ejections in the previous printing. 5. The image forming apparatus according to claim 1, wherein the control unit changes the number of ink ejections in a recovery process before the next printing according to a standby time. 6. The control device according to claim 1, wherein the control unit changes the number of ink ejections in a recovery process before the next printing according to a time elapsed from the recovery process before the previous printing.
The image forming apparatus as described in the above. 7. The image forming apparatus according to claim 1, wherein the control unit changes the number of ink ejections in a recovery process before the next printing according to a time elapsed from the end of the previous printing. 8. The image forming apparatus according to claim 1, wherein the control unit changes the number of ink ejections in a recovery process before the next printing depending on a use environment temperature. 9. The image forming apparatus according to claim 1, wherein the control unit changes the number of ink ejections in a recovery process before the next printing according to a use environment humidity. 10. The image according to claim 1, wherein the ink jet head has a plurality of recording elements arranged in a width direction of an image forming area on the recording medium. Forming equipment. 11. The recording element according to claim 1, further comprising: an ejection port from which the ink is ejected; an ink flow path communicating with the ejection port; The image forming apparatus according to claim 10, further comprising: a heat energy generator configured to generate heat.