JP2002103645A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ink jet recorder in which bubbles gathering in an ink jet recording head can be removed without wastefully consuming ink by a suction recovery and which uses a highly reliable ink jet recording head at a low running cost. SOLUTION: The ink jet recorder has the recording head for forming images by discharging the ink to a recording medium, an ink supply recovery means for supplying the ink to the recording head, a storage means for storing the ink, and an ink supply means for supplying the ink to the recording head from the storage means. The ink jet recorder includes a means for gathering bubbles into a common liquid chamber of the recording head after the ink is initially filled in the recording head.

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 apparatus using an ink jet recording head (hereinafter simply referred to as a recording head).

[0002]

2. Description of the Related Art In general, an ink jet recording apparatus performs recording by ejecting ink from a recording head to a recording medium. It is easy to make the recording head compact and to record a high-definition image at a high speed. This method has advantages such as low running cost, low noise due to the non-impact method, and easy recording of a color image using multicolor inks. Above all, a full-line type recording apparatus using a line type recording head having a large number of ejection ports arranged in the paper width direction can further increase the recording speed.

An example of such a conventional full multi-inkjet recording apparatus is schematically shown in FIGS. The ink jet recording apparatus shown in FIGS. 7 and 8 mainly includes a paper feed unit, a transport unit, a paper discharge unit, and a recording head unit. As shown in the figure, the paper supply unit has a paper supply cassette 10 and a paper supply roller 10a, and separates recording paper as a recording medium one by one by the paper supply roller 10a and a separation pad (not shown). The paper is fed by a method (duplo method), a claw separation method, or a retard method. Paper feed roller 10a from paper feed cassette 10
Or the recording paper P fed from the manual feed tray 9 by the feeding roller 8, the leading end of the recording paper P is abutted against the nip of the set of registration rollers 4 that are stopped, and the feeding roller 8 is further rotated slightly. The registration roller 4
The slack of the recording paper P can be corrected by making the recording paper P slack between the recording paper P and the feeding roller 8. Further, the fact that the recording paper P collides with the nip of the registration roller 4 is detected by a photo sensor. After the detection, the registration roller 4 is rotated, and the start of rotation of the registration roller 4 is used as a trigger to adjust the recording timing of the recording head 1 so that an image is formed at a predetermined position on the recording paper P by the recording head 1. can do.

The recording paper P conveyed by the registration roller 4 is nipped by a pair of a conveyance belt 5 and a pinch roller 12, and a voltage is applied to a lower roller 12 b of the pinch roller 12. Since the roller 12a is grounded, the recording paper P passing through the pinch roller 12 is conveyed while being electrostatically attracted to the conveyance belt 5. Then, the recording paper P electrostatically attracted onto the transport belt 5 is printed by the transport belt 5 transported by a driving roller 5b driven by a drive source which is a pulse motor (not shown), immediately below the recording heads 1K to 1C. It is transported to the start position.

The transport belt 5 is stretched by a driving roller 5b, a driven roller 5a, and a pressure roller 5c. The pressure roller 5c has one end of an arm (not shown) that is swingably attached to a transport belt box (not shown). The transport belt 5 is tensioned by being rotatably attached to the other end and being pressed by an arm.

The recording heads 1K, 1Y, 1M, and 1C are full-line type recording heads in which a plurality of recording elements are arranged over the entire width of the recording area of the recording paper P. 1K (black), 1Y (cyan),
1M (magenta) and 1C (yellow) are arranged at predetermined intervals, and the recording heads 1K, 1Y,
M and 1C are attached to the head holder 2.

In the above-described configuration, the recording paper P is attracted to the upper surface of the transport belt 5 by electrostatic attraction, and is transported by the transport belt 5 while being printed by the recording head 1.

The paper discharge roller 7 is composed of a paper discharge roller 7b and a spur 7a.
And driven by the rotational force of the drive roller 5b by a transmission means (not shown). Also, the discharge roller 7
The spur 7a, which is in pressure contact with b, is configured to sandwich the recording paper P after printing between the paper discharge rollers 7b and discharge the recording paper P to the paper discharge tray 13 for storage. The tip of the printed image is sharpened so that the ink of the printed image does not transfer as much as possible in order to roll on the subsequent printing surface.

FIG. 8 schematically shows an ink supply and recovery system from the recording head 1 to the ink tank 11. The ink tank 11 includes an ink bag 11a in which ink used for recording is stored, and a waste ink recovery unit 1 that recovers waste ink discharged from the nozzles by recovery means or the like.
1c.

Reference numeral 15 denotes a pressure pump which supplies ink to the recording head 1. Reference numeral 16 denotes a suction pump which is mainly used when the ink flow path of the nozzle portion of the recording head 1 is interrupted due to printing failure or the like. By pressing the cap 3 against the face surface of the recording head 1 and operating the suction pump 16 in a state in which the nozzle portion is sealed, the ink is discharged from the nozzle to recover the printing failure. The discharged ink is a waste ink recovery unit 11c (waste ink absorber) built in the ink tank 11.
Will be collected.

The pump of the pressurizing pump 15 and the suction pump 16 may be a tube pump which moves a fluid by mainly pressing a rubber tube with a roller, but other types of pumps (such as a piston type pump) are also possible. It is.

The ink bag 11a in the ink tank 11 is
The ink to be supplied to the recording head 1 is stored. The material of the film forming the ink bag 11a is preferably a plastic material or a material having low gas permeability.
Typically, a 15 μm thick nylon is formed on the front and a 60 μm thick is formed on the back based on a 9 μm thick aluminum film.
Of polyethylene (PE) laminated. The ink bag 11a is formed by heat-sealing the two aluminum sheets (aluminum foil film, aluminum vapor-deposited film, etc.) and the ink supply port of the polyethylene (PE) material and the aluminum sheet with the polyethylene (P) on the back surface.
E) Welding each other to complete sealing. The oxygen permeation of the aluminum foil film used here is 0 to 0.1 cc / m ^2.
Since it is 24 hours, the water content of the ink is not released to the atmosphere, and the expiration date of the ink tank 11 can be extended.

[0013]

However, when ink is initially charged into the print head 1 (in the case of a double-sided print head shown in FIG. 9) by such a pressure pump 15, both sides of the common liquid chamber of the print head are not filled. When the ink is filled from
While the ink filled from both sides is filled toward the center of the common liquid chamber, the air in the common liquid chamber is discharged from the nozzle to the atmosphere, but air bubbles cannot be removed near the center of the common liquid chamber ( FIGS. 10A and 10B).

In order to solve such a problem, conventionally, both sides of the common liquid chamber are connected by separate supply paths, respectively, and the pressure pump 1
By circulating the ink between the recording head 1 and the ink tank 11 at 5 or the like (circulation method), air in the common liquid chamber is processed by flowing air from the recording head 1 to the ink tank 11. . However, in such a circulating system, the configuration of the circulating system must be taken by the printing apparatus main body only at the time of initial ink filling, which leads to an increase in cost of the printing apparatus main body.

Accordingly, an object of the present invention is to solve the above-described conventional problems by removing bubbles accumulated in an ink jet recording head without consuming unnecessary ink due to suction recovery. Another object of the present invention is to provide an ink jet recording apparatus using a highly reliable ink jet recording head at a low running cost.

[0016]

In order to achieve the above object, an ink jet recording apparatus according to the present invention comprises a recording head which forms an image by discharging ink onto a recording medium;
An ink jet recording apparatus comprising: an ink supply recovery unit for supplying ink to the recording head; a storage unit for storing ink; and an ink supply unit for supplying ink from the storage unit to the recording head. After the recording head is initially filled with ink, a means for storing bubbles in a common liquid chamber of the recording head is provided.

Further, the ink jet recording apparatus of the present invention is characterized in that the means for storing the air bubbles is formed by a trap portion in which a part of the upper wall of the common liquid chamber of the recording head is raised.

Further, in the ink jet recording apparatus of the present invention, after initially filling the recording head, a pulse is applied to any one of a plurality of nozzles on the side opposite to the bubble generating section from immediately below the trap section. The method is characterized in that ink is ejected, and ink accumulated after initial filling is moved to the trap section.

Further, the ink jet recording apparatus of the present invention is characterized in that the timing of applying the pulse to eject ink is immediately after the initial ink filling.

The ink jet recording apparatus according to the present invention is characterized in that the ink supply into the recording head is supplied from both sides of the common liquid chamber.

Further, the ink jet recording apparatus of the present invention is characterized in that the supply of ink into the recording head is supplied from near the center of the common liquid chamber.

Further, in the ink jet recording apparatus of the present invention, the nozzles on both sides of the recording head are substantially formed up to both ends of the common liquid chamber, and the trap portion is disposed slightly inside both ends of the common liquid chamber. It is characterized by having been done.

Still further, in the ink jet recording apparatus according to the present invention, the nozzles on both sides of the recording head may include dummy nozzles from directly below the traps at both ends of the common liquid chamber to both ends of the common liquid chamber. It is characterized by being.

In the ink jet recording apparatus of the present invention, the ink supply / recovery means applies a positive pressure to the ink in the ink storage means or to the ink in the ink supply means between the ink storage means and the recording head. And supplying ink to the recording head.

The ink jet recording apparatus according to the present invention is characterized in that the ink supply means is formed of a material having gas barrier properties.

Furthermore, the ink jet recording apparatus of the present invention is characterized in that the recording head has an electrothermal converter for generating thermal energy in response to energization as energy used for discharging ink.

Further, in the ink jet recording apparatus of the present invention, the ink is discharged from the ink discharge port toward the recording medium by utilizing the film boiling generated in the ink by the heat energy applied from the electrothermal transducer. It is characterized by the following.

[0028] The ink jet recording apparatus of the present invention is characterized in that an ink in a state in which gas such as oxygen, nitrogen and carbon dioxide dissolved in the ink is reduced is used as a print medium.

[0029]

According to the ink jet recording apparatus of the present invention having the above-described structure, the ink can be collected in the ink jet recording head without wasteful consumption of ink due to suction recovery. Thus, a highly reliable ink jet recording apparatus can be obtained at a low running cost.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of several embodiments of the present invention taken in conjunction with the accompanying drawings.

Hereinafter, the ink jet recording apparatus of the present invention will be described in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view showing Embodiment 1 of a recording head used in the configuration of the ink jet recording apparatus of the present invention, and FIG. 2 is a view showing a nozzle portion in the recording head in detail. 2 (A), 2 (B), and 2 (C) are diagrams sequentially showing the progress of filling the right end of the recording head with ink.

The recording head 1 in the ink jet recording apparatus according to the present invention shown in FIG. 1 has an aluminum plate which has a certain degree of rigidity and is a material having good heat dissipation as a base plate 1d, and has a large number of nozzles 1a. Is provided, a nozzle portion 1f as an element, an ink supply pipe 1c, an ink joint 1e including a connection member for connecting the ink supply device of the apparatus main body and an ink filter, and further, the printing of the recording head 1 is performed electrically. And an electric circuit for controlling the temperature. Further, in the present embodiment, the ink ejection direction is a main body configuration in which the ink is ejected in a downward direction. Further, an ink supply pipe 1c connected to the ink joint 1e is provided in the nozzle portion 1f which is an element. It is connected to the center of the liquid chamber 1g (hereinafter, referred to as center supply).

The nozzle portion 1f of the recording head 1 is provided with a nozzle 1a, a common liquid chamber 1g, and a driving heater 1j for discharging ink in the nozzle 1a. The ink in the ink tank is pressurized and supplied to the recording head 1 by a pressurizing pump in the main body of the recording apparatus. The ink is sequentially injected from the central nozzle 1a while the ink is being pushed down from both sides toward the both sides of the common liquid chamber 1a.
The air in g is pushed out of the recording head 1 from the nozzle 1a by the injected ink.

FIGS. 2A, 2B, and 2C are diagrams showing the progress of filling the recording head 1 at the right end of the recording head 1 with ink. The recording head 1 has a nozzle 1a substantially formed up to the common liquid chamber 1g and is provided with a driving heater 1j. Further, several tens of nozzles at the end have a dummy having no driving heater 1j for discharging ink. Nozzle 1
a ′. Of course, these dummy nozzles 1a 'at the ends are optimally without the driving heater 1j, but may be dischargeable nozzles 1a having the driving heater 1j. In addition, in a portion slightly closer to the center than the end of the common liquid chamber 1g, the height of the upper wall of the common liquid chamber 1g is higher than the other upper walls, forming a trap portion 1k. The dummy nozzle 1 is located in the range of the trap portion 1k.
When a 'is formed, it is preferable that the trap portion 1k is disposed above the dummy nozzle 1a', but other than that, there is no problem.

The ink injected from the central portion of the common liquid chamber 1g of the recording head 1 is formed into an arcuate shape with the center depressed by the surface tension of the ink as shown in FIG. While discharging the air from the nozzle 1a to the outside of the recording head 1, the ink is filled toward the end of the common liquid chamber 1g. However, when the leading end 1m of the ink reaches the common liquid chamber 1g, a state occurs in which the air in the common liquid chamber 1g cannot be completely removed due to the surface tension of the ink end, and bubbles B remain. Since the bubble B has elasticity, the bubble itself shrinks, and the bubble B itself does not fall out above the common liquid chamber 1g due to the buoyancy of the bubble itself, but remains as a bubble B at the end as shown in FIG. 2B.

Next, the bubbles B remaining at the end of the common liquid chamber 1g are moved toward the center of the common liquid chamber 1g as shown in FIG. 2C. As described above, by discharging ink using several tens of nozzles 1a that can be discharged from the end of the common liquid chamber 1g, the bubbles B accumulated at the end of the common liquid chamber 1g are moved toward the trap section 1k. Since the upper wall of the trap portion 1k is higher than the other upper walls, the bubble B moved to the trap portion 1k does not move from the trap portion 1k, and moves to the center of the common liquid chamber 1g. Will not move. Further, it is possible in actual use that the recording head 1 itself is obliquely placed or that the recording head 1 is slightly inclined due to mechanical precision in the recording apparatus main body. Room 1
It is also possible to prevent the g from moving toward the center.

(Embodiment 2) Next, a description will be given of a print head according to a second embodiment of the present invention. FIGS. 3 and 4 are a sectional view and an enlarged cross section showing a print head according to the second embodiment of the present invention. FIGS. 4A, 4B, and 4C are diagrams showing the progress of filling the right end of the recording head with ink.

As shown, the recording head 1 according to the second embodiment of the present invention is connected to one supply tube in the ink jet recording apparatus main body by an ink joint 1e having a built-in filter. Ink flows from the ink supply pipes 1b and 1c to the center from both sides of a nozzle portion 1f having a common liquid chamber 1g provided with a large number of nozzles 1a as an element. Are supplied, and a two-sided supply is provided.

In the recording head 1 according to the present embodiment, since the flow resistance is different due to the difference in the length of the ink supply pipes 1b and 1c, the bubbles accumulated in the common liquid chamber 1g are generated in the central portion of the nozzle portion 1f as an element. Slightly to the left (as viewed in FIG. 3). Therefore, in this case, the trap unit 1k
It is preferable to be arranged at, for example, a substantially central portion of the nozzle portion 1f, which is an element, other than the bubble generation location.

FIGS. 4A, 4B, and 4C are diagrams sequentially showing the state of ink filling in the right end of the recording head 1 when the ink is supplied from both sides.

As described above, the recording head 1 having this configuration
In FIG. 4A, the air generated at the time of ink filling is closer to the left than the center, and first, as shown in FIG.
It is generated to the left of k and is discharged out of the nozzle 1a together with the ink, and then becomes a bubble B as shown in FIG.
The bubbles B generated in this manner are ejected as ink for preliminary ejection by several tens to several hundreds of nozzles 1a immediately below the trap portion 1k, so that the ink flows into the common liquid chamber 1g as shown in FIG. By generating the path, the bubble B generated in the common liquid chamber 1g can be moved toward the trap unit 1k.

The upper wall of the trap section 1k is
g is higher than the upper wall, so that the bubble B moves upward by entering the trap portion 1k due to the buoyancy of the bubble B. Therefore, the distance from the root of the nozzle 1a is far, and even if printing is performed thereafter, the trap portion is not moved. The bubbles B accumulated in 1k are not pulled by the nozzles 1a discharging the ink, and the bubbles B are not taken in. Therefore, it is possible to prevent the occurrence of non-discharge as a cause of printing failure. In addition, trap part 1k
Since the bubble B can be trapped in the air, the movement of the bubble B can be prevented, and the ink can be suitably ejected.

(Embodiment 3) The ink supply path from the ink tank to the print head described below is made of a material having a high gas barrier property, and the deaerated ink is used in any one of the constructions of Embodiment 1 and Embodiment 2. By using for printing media,
When ink is initially charged into the recording head, bubbles remaining in the trap section can be used for a long time without printing defects.During this time, bubbles can be reduced by deaerated ink around the bubbles, and can be erased further Becomes In the case of non-degassed ink, residual gas bubbles may further grow due to gas such as oxygen entering the ink from a nozzle or the like, or an increase in the temperature of the ink.

Hereinafter, the configuration of the main body of the recording apparatus according to this embodiment of the present invention will be described in detail.

FIG. 7 is a schematic sectional view showing an outline of the ink jet recording apparatus of this embodiment, and FIG. 8 is a block diagram showing a configuration of an ink supply / recovery apparatus.

As shown in the figure, the ink jet recording apparatus includes a full-line type recording head 1 held by a head holder 2, a cap member 3 such as a dust cap for covering the nozzle surface of the recording head 1, and a recording apparatus. A transport belt 5 for transporting paper, an ink tank 11 having a built-in ink bag 11a and provided with a waste ink recovery unit 11c, and a paper feed mechanism such as a paper feed cassette 10 loaded with recording paper are roughly provided. I have. The ink tank 11 is of a cartridge type that can be attached to and detached from the insertion opening of the recording apparatus main body. The ink tank 11 has an ink bag 11a containing ink, is provided with a waste ink recovery unit 11c for storing the recovered waste ink, and has an ink supply port to which a rubber material 11k is attached. 11f and pressurizing port 1
1h and an outlet 11j, and the outlet 11j
, A joint 40 with an open / close valve 46 is provided, a joint 41 is provided corresponding to the pressurizing port 11h, and an ink supply needle 48 is provided for the ink supply port 11f. The ink tank 11 is located below the transport belt 5 and has a height ρ (10) that can maintain the meniscus of the nozzle with respect to the recording head 1.
0 mm or more).

The ink tank 11 attached to the insertion port of the recording apparatus main body is connected to the ink supply needle 48 by the ink supply port 11f.
Can be supplied to the ink supply path. Further, the rubber material 11k prevents the ink from leaking when the ink supply needle 48 is pierced into the ink supply port 11f or when the ink supply needle 48 is pulled out.

The joint 41 mounted and connected to the pressurizing port 11 h of the ink tank 11 is connected to a switching valve 49, a stopper 42, an air buffer 43, and a pump 44 via an air supply pipe 47. As the pump 44, a tube pump or the like is suitable, and it is a matter of course that other similar mechanisms and members can be used. Also, the stopper 42
Is used to prevent air from flowing into the ink tank 11 when storing air in the air buffer 43,
When the air buffer 43 reaches a predetermined pressure, the stopper 42 is released. Also,
It is preferable to use a flexible rubber tube for the air supply pipe 47 connecting the ink tank 11 and the pump 44. The stopper 42 preferably has a configuration in which a roller is pressed against the tube by a spring force to use a solenoid so as to cut off the flow of air in the rubber tube of the air supply pipe 47.

The ink tank 11 pressurized by the pump 44 has four colors of black, cyan, yellow and magenta.
A switching valve 49 for switching between the ink tank and the sub-tank of the color ink is provided by the air supply pipe 4.
7. As the switching valve 49, a spool-type switching valve, a disk-type switching valve, or another similar switching valve can be suitably used.

A discharge port 11j of the ink tank 11 is connected to the joint 40 when the ink tank 11 is mounted on the recording apparatus main body, and is connected to a discharge port 11j capable of discharging air sent from the pump 44 into the ink tank 11. An opening / closing valve 46 is provided on the way to switch between shutoff and communication of the flow path.

As described in the first embodiment, the ink flow path between the ink tank 11 and the recording head 1 is particularly reduced in order to prevent the generation of air bubbles and to use deaerated ink. It is preferable to use a material having good gas barrier properties. The ink tank 11 is connected to the sub-ink bag 50b of the sub-tank 50 via the ink supply pipe 45, and further connected to the recording head 1 via the ink supply pipe 45 via the joint 1e.

The sub-ink bag 50b is preferably made of a flexible material such as an aluminum sheet, and has a function of holding the meniscus of the ink in the recording head 1. The height of the sub-tank 50 with respect to the recording head 1 requires a negative pressure that maintains the meniscus of the ink in the recording head 1 and does not adversely affect printing, and the height difference between the nozzle of the recording head 1 and the sub-tank 50 is required. Is 100 mm <(print head height) −
(Sub tank height) <0 mm is good.

The ink supply pipe 45 is provided with a pressure sensor 35 for detecting the ink pressure. The ink supply pipe 45 measures the pressure applied to the ink during the maintenance of the meniscus of the nozzles of the recording head 1 or the head recovery operation. , Sub tank 5
When the remaining amount of ink in the ink tank 0 runs out, the pressure in the ink supply pipe decreases, and the pressure in the ink supply pipe can be used to detect the remaining amount of ink in the sub-tank 50. The pressure operation can be stopped by detecting the pressure with the sensor 35, and the ink bag 11a or the like can be prevented from being ruptured.

The ink tank 1 is driven by the pressurizing pump 44.
The ink is supplied to the sub-tank 50 by pressurizing the ink bag 11a in 1. The amount of ink supplied to the sub-tank 50 can be detected by the pressure sensor 35. If the amount of ink in the sub-ink bag 50b is too large, the pressure detected by the pressure sensor 35 starts to increase. By stopping the pressurized supply of 11a, the amount of ink in the sub ink bag 50b can be adjusted.

The ink tank 11 and the sub tank 50
A one-way valve 51 is provided in the middle of the ink supply path in order to prevent the ink from flowing back to the ink tank 11 due to the pressure difference generated by the height difference between the ink tank 11 and the sub tank 50. . This one-way valve 51
For example, a bulky valve, a check valve, or the like can be suitably used.

The ink in the sub tank 50 can be supplied to the recording head 1 by pressurizing the sub ink bag 50b by the pressure pump 44. Also,
During continuous printing, the ink inside the recording head 1 mainly has a valve generated for discharging the ink, which remains in the ink, and the bubble grows, thereby cutting off the ink inside the nozzle. It ends up being non-discharge.

In order to prevent this state, the pump 44 is connected to the sub-tank 50 by the switching valve 49 shown in FIG.
By storing air in the air buffer 43 by the pump 44 while closing the stopper 42, the pressure can be increased.

Next, by opening the stopper 42, the air buffer 43 is formed around the sub ink bag 50b.
By feeding the air inside and pressurizing the sub ink bag 50b, a positive pressure can be applied to the ink to perform the pressure recovery operation. Furthermore, by opening a discharge port (not shown) after pressurizing, the amount of waste ink discharged by pressurization recovery can be reduced.

As means for lowering the gas permeability of the ink bag 11a using a resin film, means such as laminating a plurality of films or increasing the thickness of the film can be used. However, when the film is made thicker, and when the ink bag of the ink tank also serves as a means for holding the meniscus of the ink in the recording head, the thickness of the film itself increases, and when the ink is consumed, The thickness of the film is limited because the resulting deformation of the ink bag will adversely affect printing.

Therefore, in such an ink supply / recovery device of the recording apparatus main body, by providing the sub ink bag of the sub tank as the meniscus holding means of the ink in the recording head in the recording apparatus main body, the ink in the ink cartridge is provided. It is possible to increase the film thickness of the bag or to reduce the limitation of laminating a plurality of layers, and it is also possible to leave the degassed ink for a long time.

As described above, by constructing the present embodiment, the meniscus holding of the ink in the recording head can be performed by disposing the ink bag of the sub-tank having the function of holding the ink meniscus in the recording head in the present invention. It becomes possible to further reduce the gas permeability of the ink bag by reducing the thickness of the resin film of the ink bag or by laminating a plurality of layers of film, and to reduce the frequency of bubble discharge by deaerated ink, Furthermore, incineration processing becomes possible by using a resin film.

As described above, in the present invention, by forming the bubble reservoir at a predetermined position of the recording head,
By adopting a configuration in which air bubbles generated in the print head are guided to the air bubble storage section and the collected air bubbles are discharged out of the print head, the amount of ink consumed by recovery of the print head is significantly reduced, and running costs are reduced. And a highly reliable recording head and an ink jet recording apparatus using such a recording head.

(Others) The present invention can be applied to various ink jet recording apparatuses as long as they use ink as a recording agent. A means for generating thermal energy (for example, an electrothermal converter or a laser beam), which produces excellent effects in a recording (recording) head and a recording apparatus of a system in which a change in the state of ink is caused by the thermal energy. It is. This is because according to such a method, it is possible to achieve higher density and higher definition of recording.

The typical structure and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,723,129.
It is preferable to use the basic principle disclosed in the specification of US Pat. No. 740,796. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to the sheet or the liquid path holding the liquid (ink). Applying at least one drive signal corresponding to the recording information and providing a rapid temperature rise exceeding nucleate boiling to the electrothermal transducer, thereby generating heat energy in the electrothermal transducer, and thereby forming a recording head. This is effective because a film in the liquid (ink) corresponding to the driving signal can be formed one by one by causing film boiling on the heat acting surface. 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. U.S. Pat. No. 4,463,359 describes this pulse-shaped drive signal.
Nos. 4,345,262 are suitable. It should be noted that U.S. Pat.
If the conditions described in the specification of JP-A No. 4 are adopted, more excellent recording can be performed.

As the configuration of the recording head, a combination configuration (a linear liquid flow path or a right-angle liquid flow path) of an ink discharge port, a liquid path, and an electrothermal converter as disclosed in each of the above-mentioned specifications.
In addition to the above, a configuration using U.S. Pat. No. 4,558,333 or U.S. Pat. Included. In addition, Japanese Unexamined Patent Publication No. Sho 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. 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, when the recording head is fixed to the apparatus main body or is attached to the apparatus main body, the recording head is electrically connected to the apparatus main body and ink is discharged from 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, as a configuration of a printing apparatus to which the present invention can be applied, various forms of ejection recovery means (including preliminary auxiliary means and the like) of the printing head may be used. Specifically, capping means for the recording head,
A cleaning means such as a blade, a means for removing ink from the ink ejection port by pressurizing the ink supply system or suctioning as described above, an electrothermal converter, a separate heating element, or a combination thereof. Any means may be used as long as it includes a preliminary heating means for performing heating by heating and a preliminary ejection means for performing ejection other than recording. In the case where ink adheres or remains on the head face after such recovery processing, the arrangement of the absorber in the cap as in this example is effective, and the arrangement of the absorber for keeping the blade clean. This is because ink can be prevented from dropping onto an undesired portion.

Regarding the type and number of the recording heads to be mounted, for example, in addition to the one provided corresponding to a single color ink, a plurality of inks having different recording colors and densities as described above are provided. May be provided in plurality. 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 embodiment 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 ink from evaporating, the ink is solidified in a standing state and heated. May be used. In any case, the ink liquefies by the application according to the recording signal of the thermal energy,
The present invention is also applicable to the case where ink having a property of being liquefied for the first time by the application of thermal energy, such as one in which liquid ink is ejected, one in which solidification is already started upon reaching a recording medium, and the like. In such a case, the ink is held in a state in which the ink is held as a liquid or a solid in the concave portion or through hole of the porous sheet as described in JP-A-54-56847 or JP-A-60-71260. Alternatively, it may be configured to face the electrothermal converter. 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, examples of the form of the ink jet recording apparatus applicable to the present invention include those used as image output terminals of information processing equipment such as a computer, and the like.
A copying machine combined with a reader or the like, or a facsimile machine having a transmission / reception function may be used.

[0073]

According to the first aspect of the present invention, there is provided an ink jet recording apparatus, comprising: a recording head for forming an image by ejecting ink to a recording medium; and an ink supply recovery means for supplying the recording head with ink. And an ink supply device for storing ink, and an ink supply device for supplying ink from the storage device to the recording head, wherein after initially filling the recording head with ink, the recording head is Since the common liquid chamber has a means for storing bubbles, suction recovery of the recording head is suitably performed, the amount of ink consumed by the recovery is significantly reduced, the running cost is extremely low, and printing at a low running cost is performed. And a highly reliable recording head and ink jet recording apparatus can be obtained.

In the ink jet recording apparatus according to a second aspect of the present invention, since the means for storing air bubbles is formed by a trap portion having a part of the upper wall of the common liquid chamber of the recording head raised, the common liquid chamber is formed. Just raise some of the walls of
The trap section can be simply configured, and can be manufactured at low cost.

In the ink jet recording apparatus according to a third aspect of the present invention, after the recording head is initially charged, a pulse is applied to a plurality of nozzles from immediately below the trap section to one of the nozzles on the side opposite to the bubble generating section. By acting to eject ink and moving the bubbles accumulated after the initial filling to the trap portion, the ink can be reliably ejected and the bubbles can be reliably trapped in the trap portion.

In the ink jet recording apparatus according to the fourth aspect of the present invention, the timing at which the pulse is applied to eject the ink is immediately after the initial ink filling, so that the ink is reliably ejected to perform good printing. Can be.

In the ink jet recording apparatus according to the fifth aspect of the present invention, since the ink supply into the recording head is supplied from both sides of the common liquid chamber, the ink is preferably discharged by the recording head for printing. Can be performed favorably.

In the ink jet recording apparatus according to the sixth aspect of the present invention, the ink is supplied to the recording head from the vicinity of the center of the common liquid chamber, so that the recording head preferably discharges the ink. And good printing can be obtained.

In an ink jet recording apparatus according to a seventh aspect of the present invention, the nozzles on both sides of the recording head are substantially formed up to both ends of the common liquid chamber, and the trap portion is slightly larger than both ends of the common liquid chamber. Since it is arranged inside, air bubbles can be trapped appropriately, and printing can be suitably performed.

According to an eighth aspect of the present invention, in the ink jet recording apparatus, the nozzles on both sides of the recording head are arranged from right under the trap section at both ends of the common liquid chamber to both ends of the common liquid chamber. Since it is a dummy nozzle, it is possible to prevent unnecessary ejection of ink and perform good printing.

10. The ink jet recording apparatus according to claim 9, wherein said ink supply / recovery means is an ink in said ink storage means or an ink of said ink supply means between said ink storage means and said recording head. Since the ink is supplied to the recording head by applying a positive pressure to the recording medium, it is possible to discharge the ink satisfactorily and to obtain a suitable print.

In the ink jet recording apparatus according to the tenth aspect of the present invention, since the ink supply means is formed of a material having a gas barrier property, a gas such as oxygen does not enter the ink, and the ink supply means includes a bubble. Generation can be suitably prevented.

According to the ink jet recording apparatus of the present invention, the recording head has an electrothermal transducer for generating thermal energy in response to energization as energy used for discharging ink. Good stable printing can be performed by suitably discharging ink to the medium.

According to a twelfth aspect of the present invention, there is provided an ink jet recording apparatus which directs ink from the ink discharge port toward a recording medium by utilizing film boiling generated in the ink by thermal energy applied from the electrothermal transducer. Since the ink is ejected, the ink can be favorably ejected to stably print, and the print quality can be improved and maintained.

In the ink jet recording apparatus according to the thirteenth aspect of the present invention, since the ink in which the gas such as oxygen, nitrogen, carbon dioxide and the like dissolved in the ink is reduced is used as the printing medium, the degassed ink is used. It can be suitably recorded.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a recording head according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional partial view of a recording head showing a state when ink is filled in a common liquid chamber in Embodiment 1 of the present invention in FIG. 1; FIG.
(B) is a diagram in which bubbles are accumulated on the right side of the trap portion, and (C) is a diagram in which bubbles have moved to the central trap portion.

FIG. 3 is a schematic sectional view of a recording head according to a second embodiment of the present invention.

FIG. 4 is an enlarged cross-sectional partial view of a recording head showing a state when ink is filled in a common liquid chamber in Embodiment 2 of the present invention.
(A) is a diagram in which bubbles are accumulated in a trap portion in the center, (B)
FIG. 3B is a diagram in which bubbles are accumulated on the left side of the trap portion, and FIG. 3C is a diagram in which bubbles have moved to the central trap portion.

FIG. 5 is a schematic sectional view of an ink jet recording apparatus according to a third embodiment of the present invention.

FIG. 6 is a block diagram of a gas flow path for pressurizing, supplying, and recovering an ink tank and a sub-tank bag according to a third embodiment of the present invention.

FIG. 7 is a schematic diagram showing a conventional recording apparatus.

FIG. 8 is a schematic sectional view of an ink supply / recovery device of a conventional recording apparatus.

FIG. 9 is a schematic sectional view of a recording head of a conventional recording apparatus.

FIG. 10 is an enlarged cross-sectional partial view of a recording head showing a state when ink is filled in a common liquid chamber in a conventional recording apparatus.
(A) is a diagram in which bubbles are accumulated in a central portion, and (B) is a diagram in which bubbles are discharged and partially remain.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 recording head 2 head holder 4 registration roller 5 transport belt 7 paper discharge roller 8 feed roller 9 manual feed tray 10 paper feed cassette 11 ink tank 12 pinch roller 13 paper discharge tray 15 pressure pump 16 suction pump 35 pressure sensor 40 joint 42 Stopper 43 Air buffer 44 Pump 45 Ink supply tube 48 Ink supply needle 49 Switching valve 50 Subtank 51 One-way valve 52 Suction pump 54 Waste ink tube

Claims (13)

[Claims] A recording head for ejecting ink to a recording medium to form an image; an ink supply recovery unit for supplying ink to the recording head; a storage unit for storing ink; And an ink supply unit for supplying ink to the recording head from the above, further comprising means for storing bubbles in a common liquid chamber of the recording head after the recording head is initially filled with ink. Inkjet recording apparatus. 2. An ink jet recording apparatus according to claim 1, wherein said means for storing air bubbles is formed by a trap portion having a part of an upper wall of a common liquid chamber of said recording head raised. 3. After the recording head is initially charged, a pulse is applied to one or more of the nozzles on the side opposite to the bubble generating portion from immediately below the trap portion to cause ink to be ejected, thereby causing the initial filling. 2. The ink jet recording apparatus according to claim 1, wherein the ink remaining afterward is moved to the trap section. 4. The ink jet recording apparatus according to claim 3, wherein the timing at which the pulse is applied to eject the ink is immediately after the initial ink filling. 5. The ink jet recording apparatus according to claim 1, wherein ink is supplied to the recording head from both sides of the common liquid chamber. 6. The ink jet recording apparatus according to claim 1, wherein ink is supplied to the inside of the recording head from near the center of the common liquid chamber. 7. The recording head according to claim 1, wherein nozzles on both sides of the recording head are substantially formed up to both ends of the common liquid chamber, and the trap portion is arranged slightly inside both ends of the common liquid chamber. The inkjet recording apparatus according to claim 1. 8. A nozzle on both sides of the recording head,
2. The ink jet recording apparatus according to claim 1, wherein dummy nozzles are provided from directly below the trap section at both ends of the common liquid chamber to both ends of the common liquid chamber. 3. 9. The ink supply / recovery means applies a positive pressure to the ink in the ink storage means or to the ink in the ink supply means between the ink storage means and the recording head to apply a positive pressure to the recording head. The ink jet recording apparatus according to claim 1, wherein the ink is supplied. 10. An ink jet recording apparatus according to claim 1, wherein said ink supply means is formed of a material having gas barrier properties. 11. The ink jet recording apparatus according to claim 1, wherein the recording head has an electrothermal converter that generates thermal energy in response to energization as energy used for discharging ink. 12. The method according to claim 11, wherein the ink is ejected from the ink ejection port toward a recording medium using film boiling generated in the ink by thermal energy applied from the electrothermal converter. Inkjet recording device. 13. Oxygen and nitrogen dissolved in the ink,
The ink in a state in which a gas such as carbon dioxide is reduced is used as a print medium.
13. The ink jet recording apparatus according to any one of 12.