JP2000255053A - Ink-jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent defective ink-ejection from occurring without the need of a recovery process by providing a vapor generating means between a feeding means and an image forming means so as to prevent an ink in the recording operation from drying even in a low humidity environment. SOLUTION: A feeding means 1 separates and feeds a recording medium S loaded on a loading tray 1a by a feeding roller 1b and a separating guide 1c, feeds the same to a transporting means by a transporting roller pair 1d, 1e, and to an image forming means 3. The image forming means 3 provided above a transportation belt 2d, comprises recording heads 3a-3d for each color ink. A vapor generating means 4 is provided between the feeding means 1 and the image forming means 3, with a vapor generating part 4a thereof and a liquid storage container 4b communicating with a tube 4c. Vapor from the vapor generating part 4a is supplied to the vicinity of the recording heads 3a-3d according to the air flow.

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 which performs recording by discharging ink on a recording medium fed from a feeding means for feeding a recording medium by an image forming means.

[0002]

2. Description of the Related Art An ink jet recording apparatus is excellent in quietness because it is not in contact with a recording medium, can increase a recording speed, can perform high-density recording, and can easily perform colorization. It is widely used today because of its advantages.

When a full-line type ink jet head is used, an ink discharge portion (hereinafter, referred to as a "head nozzle") is always exposed during recording. Therefore, the ink of the head nozzle that is not ejected in a low humidity environment is easily dried, and when the recording time is prolonged, the viscosity of the ink of the head nozzle increases.
As a result, non-ejection may occur. That is, since the ink jet recording apparatus has a mechanism for discharging ink from the head nozzle, if the composition of the ink changes (particularly, the phenomenon of thickening), the discharge of the ink becomes unstable.

[0004] In printing in which the nozzle from which ink is ejected changes (recording data changes continuously), the head exposure time increases, and the time when a head nozzle that has not been printed suddenly enters the printing state is reduced. The second ejection tends to be non-ejection.

[0005] Therefore, in the ink jet recording apparatus, in order to stabilize the ink ejection, the ink to which drying or dust is attached is intentionally ejected (preliminary ejection), or an ejection recovery process such as ink suction is performed. I have.

[0006]

When performing the above-described ejection recovery processing, it is possible to perform the printing operation without stopping the printing operation during printing in a serial type printing apparatus. But,
In general, the head position of a full line type head is fixed during printing, and the recording medium passes under the fixed head nozzle, so the recovery stops the recording operation and moves the head to a position where preliminary ejection can be performed I have to do it.

In general, in a full-line type ink jet recording apparatus, this recovery processing is always performed while recording the maximum number of recording media onto a stacking tray, so that the total recording time is prolonged. .

[0008] The present invention is to solve the above problems,
The objective is to prevent the ink from drying during the printing operation even in a low humidity environment, and to reduce the total printing time without causing ink ejection failure without performing a recovery process during the printing operation. An apparatus is provided.

[0009]

In order to achieve the above object, a typical configuration according to the present invention is to discharge ink from an image forming means onto a recording medium fed from a feeding means for feeding the recording medium. In an ink jet recording apparatus for performing recording, a steam generating means for generating steam is arranged between the feeding means and the image forming means.

In the above arrangement, the steam generated by the steam generating means is supplied to the image forming means by the flow of air generated by feeding the recording medium. For this reason, it is difficult for the image forming means to increase the viscosity of the ink, and even in a full-line type recording apparatus, ink ejection failure or the like does not occur until recording on a continuously supplied recording medium is completed. Therefore, since it is not necessary to perform the recovery process during the recording, the total recording time can be reduced.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an ink jet recording apparatus according to one embodiment of the present invention will be described with reference to the drawings.

[First Embodiment] FIG. 1 is an overall schematic explanatory view of an ink jet recording apparatus, and FIG. 2 is a structural explanatory view of a steam generating means. The apparatus according to the present embodiment feeds a recording medium S from a feeding unit 1 and conveys the recording medium S by a conveying unit 2, and sequentially discharges four colors of ink on the recording medium S by an image forming unit 3. This is a color ink jet recording apparatus for recording an image, wherein a steam generating means 4 is provided between the feeding means 1 and the image forming means 3.

The feeding means 1 includes a vertically movable stacking tray 1a.
Is separated and fed one by one by a feed roller 1b and a separation guide 1c, and is fed to the transport means 2 by a pair of transport rollers 1d and 1e. Further, a shutter 1f for correcting skew is provided.

The conveying means 2 conveys the recording medium S fed from the feeding means 1 to the image forming means 3 and conveys the recording medium S after recording outside the apparatus, and is driven by a stepping motor 2a. A transport belt 2d is stretched between the driven pulley 2b and the driven pulley 2c, and a transport roller 2e is pressed against the transport belt 2d. Then, the fed recording medium S is passed through a position facing the image forming unit 3 while being attracted to the transport belt 2d by electrostatic attraction or the like, and is further discharged to a discharge tray 2h by discharge roller pairs 2f and 2g.

The image forming means 3 is disposed above the conveyor belt 2d, and sequentially prints yellow, cyan, magenta, and black inks from the upstream side to the downstream side in the conveying direction of the recording medium in accordance with the respective color signals. The recording heads 3a, 3b, 3c, 3d capable of discharging from nozzles are provided.

The recording heads 3a, 3b,
Reference numerals 3c and 3d denote line type heads in which head nozzles are arranged over the entire recording width in a direction intersecting with the transport direction of the recording medium S. Each recording head 3a, 3b, 3c, 3d is a head nozzle which is a fine liquid ejection port. , A liquid path, an energy action section provided in a part of the liquid path, and energy generating means for generating droplet forming energy to act on the liquid in the action section.

As an energy generating means for generating such energy, a recording method using an electromechanical transducer such as a piezo element or the like, an electromagnetic wave such as a laser is irradiated to generate heat, and a droplet is discharged by the action of the heat. There are a recording method using an energy generating means, and a recording method using an energy generating means for discharging a liquid by heating a liquid by an electrothermal converter such as a heating element having a heating resistor.

Among them, a recording head used in an ink jet recording method in which a liquid is ejected by thermal energy requires a high-density array of head nozzles for ejecting a recording droplet to form an ejection droplet. Because it is possible, it is possible to record at high resolution. Among them, a recording head using an electrothermal transducer as an energy generating means is advantageous because it can be easily made compact, easily mounted at a high density, and inexpensively manufactured.

Next, the steam generating means 4 supplies steam to the image forming means 3, and as shown in FIG. 1, a steam generating section 4a disposed between the feeding means 1 and the image forming means 3.
And a container 4b for storing liquid (water), both of which are communicated by a tube 4c.

To explain this more specifically, as shown in FIG. 2, the liquid is quickly absorbed by the vapor generating portion 4a.
In addition, an absorber 4d that can be evaporated is provided, and in order to suppress excess steam other than water vapor supplied to the head nozzle, the surroundings of the absorber 4d except for the image forming means side have low vapor permeability and low permeability. Included in member 4e. In a tube 4c for transporting water to the steam generator 4a, there is provided a liquid absorber 4f capable of contacting the steam w and the liquid w in the container 4b and transporting the water to the steam generator 4a. ing.

In the image forming apparatus having the above-described structure, when the image formation is started, the recording medium S is fed one by one by the feeding means 1 and sent to the image forming means 3 by the feeding means 2. Conveyed. Each of the recording heads 3a, 3b, 3c, 3d ejects yellow, cyan, magenta, and black color inks onto the recording medium S to form a color image, and is ejected to the ejection tray 2h.

At the time of the image formation, an air flow is generated in the same direction as the recording medium S is conveyed.
A steam generating means 4 is provided on the upstream side of the image forming means 3, and since steam is generated from the steam generating part 4a, the steam is generated by the recording heads 3a, 3b, 3c, 3c by the air flow. It is supplied around 3d. This makes it difficult for the recording heads 3a, 3b, 3c, 3d to dry, and makes it difficult for the ink in the head nozzles to thicken.

For this reason, the image forming apparatus of the present embodiment employs a recovery means (not shown) for performing recovery processing such as preliminary discharge of ink in order to prevent discharge failure of the recording heads 3a, 3b, 3c and 3d. However, in the case where continuous recording is performed on a recording medium fed continuously, the recovery process of the recording heads 3a, 3b, 3c, and 3d is not performed during a series of recording operations, and the recording operation ends. After that, the recovery process is controlled.

As described above, even if the recovery process is not performed until a series of printing operations is completed, the printing heads 3a, 3b,
Since the inks 3c and 3d are hardly thickened, ink ejection failure does not occur. Accordingly, since it is not necessary to perform the recovery process during the recording, the total recording time can be reduced.

[Second Embodiment] In the above-described first embodiment, the recording heads 3a and 3 are supplied with the steam generated by the steam generating means 4 by the air flow generated by the conveyance of the recording medium.
Although an example in which the steam is supplied to the vicinity of b, 3c, and 3d has been described, an example in which steam is forcibly supplied to the image forming unit 3 will be described as a second embodiment.

FIG. 3 is a schematic illustration of an image forming apparatus according to a second embodiment, and FIG. 3 is an illustration of the configuration of a steam generating means. Members having the same functions as those of the first embodiment described above are denoted by the same reference numerals, and redundant description will be omitted.

The image forming apparatus according to this embodiment has the configuration shown in FIG.
As shown in FIG. 3, a steam generating means 5 is disposed between the feeding means 1 and the image forming means 3, and the steam generating means 5 absorbs liquid as shown in FIGS. 3 and 4 (b). A tube 5c connects a steam generator 5a formed of a body and a container 5b for storing liquid (water), and the steam generator 5a is inserted into the tube 5c.
a and the water in the container 5b, and is similar to the first embodiment in that a liquid absorber 5d capable of transporting the water to the steam generator 5a is provided, but the steam is forcibly supplied. It has a fan 5e driven by a motor 5f as supply means. For this reason, when the fan 5e is driven, the steam generated in the steam generating section 5a is forcibly supplied to the image forming means 3 so that the humidity in the area increases.

In the area of the image forming means 3, FIG.
As shown in FIG. 4A, a humidity sensor 6 is provided as humidity detecting means for detecting humidity near the image forming means. Then, the fan 5e is controlled so as to be driven according to the detection result of the humidity sensor 6. That is, when the humidity of the image forming unit 3 becomes lower than the predetermined value during the image forming operation, the fan 5e is driven, and when the humidity of the image forming unit 3 becomes higher than the predetermined value, the driving of the fan 5e is stopped. Is controlled.

Thus, the recording heads 3a, 3b, 3
The ambient humidity of c and 3d is always kept constant, so that the ink of the head does not surely increase in viscosity and no ink ejection failure occurs.

[Other Embodiments] In the above-described embodiment, an example is shown in which a full-line type ink jet recording head is used as the image forming means. However, the recording head is mounted on a carriage, and the carriage is scanned to form an ink image. Even in the case of a serial type ink jet recording apparatus that forms the above, the same effect as in the above-described embodiment can be obtained by providing the steam generating means to suppress the increase in the viscosity of the ink.

In the above embodiment, a color ink jet apparatus using four recording heads has been described.
This may be an ink jet recording apparatus that performs monochrome recording using one recording head.

In the above-described embodiment, the ink jet recording system is used as the image forming means. However, an electric current is supplied to the electrothermal converter according to a recording signal, and the ink is generated in the ink by the thermal energy applied by the electrothermal converter. It is more preferable that the recording is performed by discharging the ink from the discharge port by the growth and shrinkage of the bubble generated in the ink using the film boiling.

With respect to the typical configuration and principle, it is preferable to use the basic principle disclosed in, for example, US Pat. Nos. 4,723,129 and 4,740,796. 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 a sheet or a liquid path holding a liquid (ink). By applying at least one drive signal corresponding to the recorded information and providing a rapid temperature rise above nucleate boiling,
This is effective because heat energy is generated in the electrothermal transducer, thereby causing film boiling on the heat-acting surface of the recording head. As a result, bubbles in the liquid corresponding to this drive signal one-to-one can be formed. The liquid 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 immediately and appropriately performed, so that particularly excellent liquid ejection can be achieved, which is more preferable.

As the pulse-shaped driving 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 of the invention 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 a discharge port, a liquid path, and an electrothermal converter (a linear liquid flow path or a right-angle liquid flow path) as disclosed in the above-mentioned respective specifications, The present invention also includes a configuration using U.S. Pat. Nos. 4,558,333 and 4,459,600 which disclose a configuration in which a heat acting portion is arranged in a bending region.

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 transducer for a plurality of electrothermal transducers, or an aperture for absorbing pressure waves of thermal energy. Unexamined Japanese Patent Application Publication No.
The effect of the present invention is effective even in a configuration based on JP-A-59-138461. That is, according to the present invention, the recording can be performed reliably and efficiently regardless of the form of the recording head.

Further, in the above-described embodiment, 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,
Alternatively, in the ink jet recording method, it is common to control the temperature of the ink itself within a range of 30 ° C. or more and 70 ° C. or less so that the viscosity of the ink is in a stable ejection range. It is sufficient if the ink is in a liquid state. In addition, positively prevent the 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 use an ink that solidifies in a standing state to prevent evaporation of the ink. In any case, the ink is liquefied by the application of the heat energy according to the recording signal, and the ink is liquefied, and the liquid ink is discharged. The present invention is also applicable to a case where an ink that liquefies for the first time by energy is used.

The ink in such a case is disclosed in JP-A-54-5
No. 6847 or Japanese Patent Application Laid-Open No. Sho 60-71260, in which the porous sheet is opposed to the electrothermal converter in a state of being held as a liquid or solid substance in the concave portion or through hole of the porous sheet. It is good. The most effective one for each of the above-mentioned inks is to execute the above-described film boiling method.

Further, as the form of the above-described ink jet recording apparatus, in addition to the one used as an image output terminal of an information processing apparatus such as a computer, a form of a copying apparatus combined with a reader or the like, and a form of a facsimile apparatus having a transmission / reception function May be used.

[0041]

The present invention is constructed as described above.
The steam generated by the steam generating means is supplied to the image forming means by a flow of air generated by feeding the recording medium. For this reason, it is difficult for the image forming means to increase the viscosity of the ink, and even in a full-line type recording apparatus, ink ejection failure or the like does not occur until recording on a continuously supplied recording medium is completed. Therefore, since it is not necessary to perform the recovery process during the recording, the total recording time can be reduced.

Further, if the steam generated by the steam generating means is supplied in accordance with the humidity of the image forming means, it is possible to more reliably prevent defective ink ejection.

[Brief description of the drawings]

FIG. 1 is an overall schematic diagram of an inkjet recording apparatus.

FIG. 2 is an explanatory diagram of a configuration of a steam generating means.

FIG. 3 is a schematic explanatory view of an image forming apparatus according to a second embodiment.

FIG. 4 is an explanatory diagram of a configuration of a humidity detecting unit and a steam generating unit.

[Explanation of symbols]

 S ... recording medium 1 ... feeding means 1a ... loading tray 1b ... feeding roller 1c ... separation guide 1d, 1e ... transport roller pair 1f ... shutter 2 ... transport means 2a ... stepping motor 2b ... driven pulley 2c ... driven pulley 2d ... Conveying belt 2e ... Conveying rollers 2f, 2g ... Discharge roller pair 2h ... Discharge tray 3 ... Image forming means 3a, 3b, 3c, 3d ... Recording head 4 ... Steam generating means 4a ... Steam generating section 4b ... Container 4c ... Tube 4d ... Absorber 4e Low-permeability member 4f Liquid absorber 5 Vapor generating means 5a Vapor generating unit 5b Container 5c Tube 5d Liquid absorber 5e Fan 5f Motor 6 Humidity sensor

Claims (6)

[Claims] 1. An ink jet recording apparatus that performs recording by discharging ink from an image forming unit onto a recording medium fed from a feeding unit that feeds a recording medium, wherein: between the feeding unit and the image forming unit. An ink jet recording apparatus, further comprising a steam generating means for generating steam. 2. An ink jet recording apparatus according to claim 1, wherein said steam generating means has a supply means for forcibly supplying steam to said image forming means. 3. The apparatus according to claim 2, further comprising a humidity detecting means for detecting humidity near the image forming means, and driving the steam generating means in accordance with a detection result of the humidity detecting means. The inkjet recording apparatus according to any one of the preceding claims. 4. The ink jet recording apparatus has a recovery unit for recovering an ink ejection state of the image forming unit, and the recovery unit continuously feeds a recording medium by a feeding unit to perform printing. 2. The ink jet recording apparatus according to claim 1, wherein the control is performed so as not to perform the recovery process. 5. The image forming unit according to claim 1, wherein the image forming unit is a line-type image forming unit in which ink discharge ports are arranged over the entire recording width in a direction intersecting with a feeding direction of the recording medium. Ink jet recording device. 6. The ink-jet recording apparatus according to claim 1, wherein the image forming means discharges the ink by using film boiling generated in the ink by thermal energy applied by an electrothermal converter. The inkjet recording apparatus according to any one of the preceding claims.