JPH03292145A - Ink-jet recording device - Google Patents

Abstract

PURPOSE:To prevent insufficient discharge of recording ink drops from recording heads by a method wherein the discharge direction of the discharged ink drops is arranged so that it becomes aslant against the direction that is perpendicular to the recording surface of recording paper. CONSTITUTION:Each of recording heads 101 fixed to a recording head holder 118 through each of fixing members 317 is arranged so that discharge of ink drops 314 discharged out of a discharge port of each of nozzles 210 of each of the recording heads 101 is made aslant by the angle theta against the direction perpendicular to the surface of recording paper 113 toward the direction whereto a carriage 127 carrying the recording heads 101 proceeds. (namely the direction P) In the case where the recording is made on setting, for instance, as follows: Tilt angle of the recording head theta=30 deg. The distance between the carriage and the recording paper (d)=0.5mm Lcos 30 deg.=0.6mm The distance between the discharge surface of the recording head and the recording paper L=0.7mm, insufficiency does not occur to discharge of the recording ink drops even in the case where the printing is made (with 5X10<5> pulse per nozzle) to the whole area of a sheet of paper in full A-size.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method of ejecting a recording liquid, generally called ink, as small droplets from an orifice, causing the droplets to fly, and making the droplets adhere to a recording surface. The present invention relates to an inkjet recording device that performs recording.

[Traditional technique! #]

A recording head applied to an inkjet recording device generally includes a fine liquid ejection opening (orifice), a liquid flow path, an energy application section provided in a part of the liquid flow path, and an energy application section that acts on the liquid in the energy application section. and energy generating means for generating droplet formation energy to cause the droplet to form.

Energy generating means for generating such energy include recording methods using electromechanical transducers such as piezo elements, irradiating electromagnetic waves such as lasers, absorbing them into the liquid and generating heat, and the action of the heat generated. There are recording methods that eject or fly droplets, recording methods that use electrothermal transducers, and the like. Among them, inkjet recording heads that use electrothermal transducers as energy generating means are capable of achieving high performance by arranging liquid ejection ports in a high density for ejecting recording droplets to form flying droplets. It is possible to record with high resolution, and it is also easy to make the entire recording head more compact. In addition, recent advances in technology and reliability in the semiconductor field have been remarkable.
The advantages of C technology and micro-processing technology can be fully utilized,
To provide an inkjet recording head that is easy to make multi-nozzle and high-density packaging because it is easy to make it long and planar (two-dimensional), and has good mass productivity and low manufacturing cost. is possible.

In this way, when an inkjet recording head manufactured through a semiconductor manufacturing process using an electrothermal converter as an energy generating means has a multi-nozzle configuration, the liquid flow path corresponding to each nozzle is An electrothermal converter is provided for each liquid flow path as a means for applying thermal energy to the liquid filling the liquid flow path and ejecting the liquid from a corresponding nozzle to form flying droplets, Each liquid flow path is configured to be supplied with liquid from a common liquid chamber communicating with each liquid flow path.

By the way, as the recording head as described above is used to eject and fly the recording ink and continue the recording operation, as shown in FIG. 7, it is fixed to the recording head holder 718 via the recording head fixing member 717. When the recording ink droplets 714 are ejected from the ejection ports of each nozzle 710 of the print head 701, countless satellite-like minute ink mist 715 may adhere to and accumulate on the ejection surface 711 of the print head 701, and each When the ink droplet 714 ejected from the ejection port of the nozzle 710 reaches the surface of the recording paper 713 and an ink pool 714' is formed before being absorbed by the recording paper 713, an ink droplet 714 flies from behind. A satellite-like minute ink mist 715 is in this ink pool 714.
': The fine ink mist 715' generated by the ink splashing at that time adheres and accumulates on the ejection surface of the print head, causing each nozzle 71 of the print head to
A problem has arisen in that stable ejection of ink droplets from the nozzle nozzle is hindered. Therefore, conventionally, in order to solve the problem caused by the minute ink mist 715 that is generated when the ink droplets 714 are ejected from the ejection ports of the print head 701, air is placed near the ejection surface 711 of the print head 701. A suction device may be provided to suck out the fine ink mist 715, or a rubber plate may be brought into regular contact with the opposite side of the recording head holder 718 to prevent the fine ink mist 715 from adhering and accumulating. A method of scraping off the adhered ink droplets 719 has been considered.

[Problem to be solved by the invention]

However, among the above-mentioned conventional inkjet recording devices, in the case of one that uses an air suction device to suck in minute ink mist, the device configuration is large and the noise is large. Not only is the ink droplet 714 suctioned, but the airflow also affects the ink droplet 714, causing a problem in that the recording position of the recording dot on the recording paper deviates from the original recording position. Furthermore, when a rubber blade is used to remove the adhered ink droplets 719, the ejection surface 711 of each recording head 701 is damaged by the rubber blade, and the ejection surface 711 of each nozzle 710 of each recording head 701 is ejected from the ejection port. This has the disadvantage that the direction of ejection of the ink droplets 714 is disturbed, and furthermore, when the print head 701 has multiple colors, the adhering ink droplets 719 attached to the ejection surface 711 of each print head 701 are separated from each other. Each color recording head 70
1 nozzle 710, each recording head 7
There was a drawback that it caused color mixing of the recording ink within the nozzle 710 of No. 01.

The present invention has been made in view of the drawbacks of the above-mentioned prior art.
It is an object of the present invention to provide an inkjet recording apparatus that can prevent the occurrence of defective ejection of recording ink droplets from a recording head due to accumulation.

[Means to solve the problem]

An inkjet recording apparatus of the present invention is an inkjet recording apparatus that performs recording on recording paper by ejecting ink droplets from a recording head. It is provided so as to be inclined with respect to the vertical direction.

In this case, cover the part of the recording head that faces the recording paper,
An ink absorbing member may be provided at a portion through which ink droplets are ejected from the recording head, and is provided with holes for allowing the ink droplets to pass through.

[For production]

Since the ejection direction of ink droplets ejected from the ejection ports of the nozzles of the print head is inclined with respect to the vertical direction of the recording surface, ink mist that bounces off the recording surface is reflected according to the inclination, and the ink droplets are Since the ink bounces back in a direction different from that of the print head that ejected the ink, it is less likely to adhere to the ejection surface of the print head. When an ink absorbing member is provided, these inks are absorbed and the reflection path is restricted, so that ink mist is even less likely to adhere to the ejection surface of the recording head.

〔Example〕

The present invention will be specifically described below with reference to the drawings.

FIG. 1 is a schematic diagram of a first embodiment of an inkjet recording apparatus of the present invention.

The continuous recording paper 113 wound into a roll is conveyed by the rotational frictional force of the sheet feed roller 123 via guide rollers 121 and 122, and is discharged in the direction of arrow 124.

Recording paper 11 between guide rollers 121 and 122 below L
3 has four recording heads l0IY on the front.

A carriage 127 carrying a recording head holder 118 accommodating 101M, 10IC, and 10IBK is arranged,
This area becomes the recording section.

The recording section is provided with a guide shaft 125 arranged parallel to guide rollers 121 and 122, and a carriage 127 reciprocates along the guide shaft 125.

Each recording head l0 accommodated in the recording head holder 118
IY, IOIM, 10IC, and 101BK are yellow Y and magenta M, respectively, from ink tanks not shown.
, cyan C, and black BK inks are supplied.

Each recording head l0IY, IOIM, l0IC.

At step 1018, the recording paper 113 is intermittently fed by the printing width of each recording head, and while the recording paper 113 is stopped in the feeding direction, it is scanned in the direction of arrow P and discharges recording ink droplets in accordance with the image signal. The carriage 127 is reciprocated by a carriage motor (pulse motor) 128 via a timing belt 126, and the sheet feed roller 123 is rotationally driven by a sheet feed motor 129. Each motor is driven by a carriage motor driver 133 and a sheet feed motor, respectively. It is controlled by control circuit 130 via driver 136.

The image data consisting of R2O and B outputted from the image data output unit 135 is processed by the image processing circuit 131 into Y, M,
According to this signal, the above-mentioned control circuit 130 outputs a drive signal to each recording head via flexible cables 120Y, 120M, 120C, and 1208K, and actually each Recording ink droplets are ejected from the recording head.

FIG. 2 shows each of the above-mentioned recording heads 10IY.

It is a schematic configuration diagram of 101M, 10IC, and 10IBK.

Since these devices have similar configurations, they will be described below as the recording head 101.

The recording head 101 is composed of an electrothermal transducer 203, an electrode 204, a nozzle wall 205, and a top plate 206, which are formed on a substrate 202 through semiconductor manufacturing process steps such as etching, evaporation, and sputtering. ink 212
The ink is supplied from an ink storage chamber (not shown) through an ink supply pipe 207 into the common ink chamber 208 of the recording head 101. Reference numeral 209 in the figure is a connector for the ink supply pipe. The ink 212 supplied into the common ink chamber 208 is supplied into each nozzle 210 by capillary action, and is stably held by forming a meniscus at the ejection port at the tip of the nozzle.

By energizing the electrothermal converter 203 in this state,
The ink on the surface of the electrothermal converter 203 is heated, a bubbling phenomenon occurs, and the energy of the bubbling causes each nozzle 210
Ink droplets are ejected from the ejection opening. With the above-mentioned configuration, a nozzle density of 400 nozzles/in h can be achieved with 128 nozzles or 25
It becomes possible to manufacture a multi-nozzle inkjet recording head with six nozzles.

FIG. 3 is a schematic cross-sectional view showing the main structure of the first embodiment of the present invention.

In this embodiment, each print head 101 fixed to a print head holder 118 via a print head fixing member 317 is configured to eject ink droplets 314 ejected from the ejection openings of each nozzle 210 of each print head 101. It is arranged so as to be inclined at an angle θ toward the traveling direction (direction P) of the carriage 127 on which the recording head 101 is mounted with respect to the direction perpendicular to the surface of the recording paper 113. That is, θ shown in the figure is defined as θ>○. That is, in this embodiment, the ejection direction of the ink droplets 314 ejected from the ejection ports of each nozzle 210 of each print head 101 is set to
3, each recording head 10
When each ink droplet 314 ejected from the ink droplet 314 reaches the surface of the recording paper 113 and forms an ink pool 314' before being absorbed by the recording paper 113, an ink droplet 314 ejected from behind the ink droplet 314 It is assumed that the rebounding minute ink mist 315' generated when the satellite-like minute ink mist 315 reaches the ink reservoir 314' is rebounding in a direction different from the ejection surface 211 of each recording head 101. This prevents the ejection surface 211 of the recording head 101 from being contaminated by splashed ink.

Each recording head 1 in the vertical direction of this recording paper 113
Ink droplet 3 ejected from the ejection port of the nozzle 210 of 01
If the angle θ of the inclination of the ejection direction of No. 14 is set to θ〉00, the rebound fine ink mist 315' generated on the surface of the recording paper 113 will be θ〉O on the side opposite to the ejection direction of the recording head 101. When the carriage 127 (see FIG. 1) carrying each recording head 101 is scanned in the direction of arrow P, this rebound fine ink mist 315' adheres to the ejection surface 211 of each recording head 101. For ease of printing, the recording head 101 is tilted so that the ink droplets 314 are ejected in the opposite direction of arrow P.

That is, the ink mist 315' is arranged so that the inclination angle θ is 00 and θ<90', thereby making it difficult for the minute ink mist 315' to re-adhere to the ejection surface 211 of the recording head 101.

In fact, the present inventors used a recording head with a nozzle density of 400 dpi and 256 nozzles as shown in Figure 2, and an aqueous ink consisting of a solvent of 70% water and 30% diethylene glycol, and all nozzles of the recording head were used. When driving at a driving frequency of 2.5KHz, conventionally it was fast and A
The ink droplet ejection failure due to the accumulation of the bounced minute ink mist 315' that occurred in all four sizes (approximately 6 x 104 pulses/nozzle) was caused by setting the recording head inclination angle θ to 30° and moving the carriage to Distance between recording sheets d=o,
5mm L cos 3 0 = 0.6mm and the distance between the recording head ejection surface and the recording paper L = 0.7mm. ) It was confirmed that no ejection failure of recording ink droplets occurred even when printing was performed.

FIG. 4 is a schematic cross-sectional view showing the main structure of a second embodiment of the present invention.

In this embodiment, each recording head 101 arranged at an angle with respect to the perpendicular direction of the recording surface of the recording paper 113 is fixed, and each recording head holder 118 mounted on a carriage 127 (see FIG. 1) is used for each recording. The ejection surface side of the head 101 is covered with an ink absorbing member 437 provided with slit-shaped holes 438 large enough to allow ink droplets 314 ejected from the nozzles 210 to pass through.

As in this embodiment, the ejection surface 211 of each recording head 101
By providing the ink absorbing member 437 on the front side of the
When there are a plurality of recording heads 101 or more, it is possible to prevent minute ink mist 315' generated by other recording heads 101 from adhering to and accumulating on each ejection surface 211 of each recording head 101.

Note that a porous polymer material is used as the ink absorbing member 437 used here, but especially in the case of polymer foam, its volume often changes when it absorbs ink mist. Therefore, it is necessary to use a type that does not change its volume even when it absorbs ink, and foamed formal resin type is particularly good.

In addition to the above-mentioned materials, thermally sintered porous polymer materials are also effective as the ink absorbing member 437 used here, such as low-density polyethylene, high-density polyethylene,
High molecular weight polyethylene, composite Boeriethylene, polypropylene, polymethyl methacrylate, polystyrene,
It is possible to use a thermally sintered body of an acrylonitrile copolymer, an ethylene vinyl acetate copolymer, a fluororesin, or a phenol resin. Among them, those using low-density polyethylene, high-density polyethylene, high-molecular-weight polyethylene, and polypropylene are preferable in terms of ink mist absorbability and ink resistance.

Furthermore, the ink absorbing member 437 made of these porous polymers is treated with a surfactant to reduce the contact angle with the ink in order to improve the absorption of ink mist. The effect of the ink absorbing member of the present invention is further improved by improving the wettability.

FIG. 5 is a schematic cross-sectional view showing the main structure of a third embodiment of the present invention.

In this embodiment, the ejection surface side of each recording head 101 of the recording head holder 118, which fixes each recording head 101 arranged at an angle θ in the recording scanning direction with respect to the recording surface of the recording paper 113, is A slit-shaped hole 538 that is large enough to allow ink $314 from the nozzle 210 to pass through.
An ink absorbing member 539 is provided to cover the entire surface of each recording head 101 except for this portion. As in this embodiment, by providing the ink absorbing member 539 on almost the entire surface of the recording head holder 118 on the recording paper side,
Ink droplets 3 ejected from the ejection ports of each recording head 101
The minute ink mist 315' generated by
It is possible to prevent the particles from adhering and accumulating on the surface of the recording paper (see FIG. 1), resulting in poor ejection of the recording head and staining of the recording paper.

FIG. 6 is a schematic cross-sectional view showing the main structure of a fourth embodiment of the present invention.

In this embodiment, a recording head holder 11 fixes each recording head 101 arranged at an angle θ in the recording scanning direction with respect to the direction perpendicular to the recording surface of the recording paper 113.
A front plate 640 having grooves 641 with a fine pitch is provided on the side of the recording paper 113 of No. 8. The front plate 640 also has the ink absorbing member 5 shown in FIG.
39, the slit-shaped holes 6 are large enough to allow the ink droplets 314 from the nozzles 210 of each recording head 101 to pass through.
38 is provided, and the other parts are each recording head 101.
It is intended to cover the entire surface of the

That is, in this embodiment, the fine ink mist 315' generated by the ink droplets 314 ejected from the ejection openings of the nozzles 210 of each recording head 101 is
7 (see FIG. 1), even if the ink accumulates on the surface of the recording paper, it will flow downward in the vertical direction along the fine pitch grooves 641 provided on the front plate 640. There is. This front plate 6
In order to make it easier for ink pools that have adhered and accumulated in the grooves 641 provided in the front plate 640 to flow down,
This embodiment can be made more effective by using a material that has poor wettability with ink.

In fact, the materials used for this front plate 640 include plastic members such as polypropylene and fluororesin,
It is sufficient to use a metal member coated with a water-repellent coating such as a fluororesin on the side of the recording paper.
For the grooves 641 provided at 0, the pitch between the grooves and the depth of the grooves may be approximately 0.1 mm to 1 mm.

Even if the minute ink mist 315' adheres to and accumulates on the recording paper surface side of the carriage 127 as described above, causing an ink puddle, the ink puddle is flushed vertically downward (from the front side of the paper surface to the back side in the figure). By adopting the method of dropping the carriage 127, the degree of freedom in selecting the material for constructing the carriage 127 can be increased.

The present invention brings about excellent effects particularly in a bubble jet type recording head and recording apparatus among inkjet recording types.

As for typical configurations and principles thereof, it is preferable to use the basic principles disclosed in, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740,796. This method can be applied to both the so-called on-demand type and continuous type, but especially in the case of the on-demand type, it is necessary to arrange the liquid (ink) in accordance with the sheet and liquid path that hold it. By applying at least one drive signal that corresponds to recorded information and causes a rapid temperature rise exceeding nucleate boiling to the electrothermal transducer, the electrothermal transducer generates thermal energy, and the recording head This is effective because it causes film boiling on the heat acting surface of the liquid (ink), resulting in the formation of bubbles in the liquid (ink) in one-to-one correspondence with this drive signal. The growth and contraction of the bubble causes liquid (ink) to be ejected through the ejection opening to form at least one drop. It is more preferable to use this drive signal in a pulse form, since the growth and contraction of bubbles can be carried out immediately and appropriately, so that ejection of liquid (ink) with particularly excellent responsiveness can be achieved. As this pulse-shaped drive signal, those described in US Pat. No. 4,463,359 and US Pat. No. 4,345,262 are suitable. Furthermore, even better recording can be achieved by adopting the conditions described in US Pat.

The configuration of the recording head includes a combination configuration of an ejection port, a liquid path, and an electrothermal converter (straight liquid flow path or right-angled liquid flow path) as disclosed in each of the above-mentioned specifications. U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,459,600 disclose a configuration in which the portion is arranged in a bending region.
The structure described in the specification may be used. In addition, Japanese Patent Application Laid-Open No. 1983 discloses a configuration in which a common slit is used as a discharge part of a plurality of electrothermal converters.
No. 23670 and Japanese Unexamined Patent Publication No. 1, 1982, which discloses a configuration compatible with an open discharge part that absorbs pressure waves of thermal energy.
The present invention is also effective with a configuration based on Publication No. 38461.

Furthermore, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording device, the length can be increased by combining multiple recording heads as disclosed in the above-mentioned specification. Either a configuration satisfying the above requirements or a configuration as a single recording head formed integrally may be used, but the present invention can more effectively exhibit the above-mentioned effects. In this case, the nozzles may be provided at an angle so that the ink droplets ejected from each nozzle are ejected to the downstream side of the recording paper.

In addition, a replaceable chip-type recording head that is attached to the device body enables electrical connection to the device body and ink supply from the device body, or a chip-type recording head that is installed integrally with the recording head itself. The present invention is also effective when a cartridge type recording head is used.

Further, it is preferable to add recovery means, preliminary auxiliary means, etc. for the recording head, which are provided as a configuration of the recording apparatus of the present invention, because the effects of the present invention can be further stabilized. Specifically, stable recording can be achieved by using a preheating means using an electrothermal converter, a heating element separate from this, or a combination thereof, and a preliminary ejection mode in which ejection is performed separately from recording. It is effective for

Furthermore, the recording mode of the recording device is not limited to the recording mode of only mainstream colors such as black, but also the recording head may be configured integrally or by a combination of multiple colors, but it may also be possible to use multiple colors of different colors or mixed colors. The present invention is also extremely effective for devices equipped with at least one full color image.

In the embodiments of the present invention described above, the ink is explained as a liquid, but it is an ink that solidifies at room temperature or lower, and is softened or liquid at room temperature, or in the above-mentioned inkjet, the ink itself is heated at a temperature of 30°C or higher and 70°C. Generally, the temperature is controlled within a range below ℃ to keep the viscosity of the ink within the stable ejection range.
Any ink may be used as long as the ink is in a liquid state when the recording signal is applied. In addition, it is possible to proactively prevent temperature rise caused by thermal energy by using the ink as energy to change its state from a solid state to a liquid state, or to use ink that solidifies when left in order to prevent ink evaporation. In any case, the ink may be liquefied by application of thermal energy in accordance with the recording signal and ejected as liquid ink, or the ink may have already begun to solidify by the time it reaches the recording medium. The present invention is also applicable to the use of ink that is liquefied for the first time. In such a case, the ink is held in a liquid or solid state in the recesses or through holes of the porous sheet, as described in JP-A-54-56847 or JP-A-60-71260. , it may also be in a form that faces the electrothermal converter. In the present invention, the most effective method for each of the above-mentioned inks is to implement the above-mentioned film boiling method.

[Effects of the Invention] Since the present invention is configured as described above, it has the following effects.

In the first aspect of the present invention, the minute ink mist generated when the ink droplets reach the recording paper surface is bounced in a direction different from the ejection surface of the recording head, so that this ink mist adheres to the ejection surface of the recording head. This has the effect of preventing the ejection failure of recording ink droplets from the recording head due to accumulation.

According to the second and third aspects of the present invention, it is possible to realize a carriage moving type inkjet recording device and a full line type inkjet recording device each having the above-mentioned effects.

In the fourth aspect of the present invention, since an ink absorbing member is provided which also serves as a means for restricting ink splashing, the above-mentioned effects can be further improved.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of an inkjet recording apparatus of the present invention, FIG. 2 is a schematic configuration diagram of the recording head in FIG. 1, and FIG. 3 is a main part configuration of the first embodiment. 4 to 6 are schematic sectional views showing the main part configuration of the second to fourth embodiments of the present invention, and FIG. 7 is a schematic sectional view showing the main part structure of the conventional example. It is a diagram. 113... Recording paper, 118... Recording head holder, 121.122-... Guide roller, 123... Sheet feed roller, 125... Guide shaft, 126... Timing belt, 127... Carriage, 128... Carriage motor, 129... Sheet feed motor, 130... Control circuit, 131... Image processing circuit, 202... Board, 203
...Electrothermal converter, 204... Electrode, 205-...
Nozzle wall, 208... Top plate, 207... Ink supply pipe, 208... Common ink chamber, 209... Connector, 2
10... Nozzle, 211... Discharge surface, 212...
Ink, 314.315... Ink drop, 314'315'... Ink mist, 317
... Recording head fixing member, 437.539 ... Ink absorption member, 438.538
, 638...hole, 640...front plate, 641...groove.

Claims (1)

[Claims] 1. By ejecting ink droplets from a recording head,
In an inkjet recording apparatus that performs recording on recording paper, the recording head is provided so as to be inclined so that the ejection direction of the ink droplets to be ejected is inclined with respect to the direction perpendicular to the recording surface of the recording paper. Inkjet recording device. 2. The inkjet recording apparatus according to claim 1, wherein the recording head is mounted on a carriage, and is inclined so that the ink droplets to be discharged are discharged to the downstream side of the carriage in the recording scanning direction. An inkjet recording device characterized by: 3. The inkjet recording apparatus according to claim 1, wherein the recording head is of a full line type in which ejection ports are formed on the recording paper over the entire width of the recording area, and the ejected ink droplets are directed in the conveyance direction of the recording paper. An inkjet recording device characterized in that the inkjet recording device is installed so as to be inclined so as to eject to the downstream side. 4. The inkjet recording apparatus according to claim 1, 2 or 3, wherein a portion of the recording head facing the recording paper is covered, and a portion through which ink droplets are ejected from the recording head is provided with a groove for passing the ink droplets. An inkjet recording device comprising an ink absorbing member provided with holes. 5. The inkjet recording apparatus according to claim 1, 2, 3 or 4, wherein the recording head ejects ink using thermal energy, and includes an electrothermal converter for generating the thermal energy. An inkjet recording device characterized by comprising: