JPS62278046A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To prevent thermal deterioration of ink and to enable high speed high density recording, by inserting a recording sheet between an electrostatic induction electrode and an ink absorbing member then flying a portion of heated ink to the recording sheet side by means of an electrostatic force between the electrostatic induction electrode and the ink absorbing member. CONSTITUTION:When a base member 1 is irradiated with a laser beam (s) corresponding to an image signal, irradiated portion A on the base member 1 is heated to rise the temperature thereon so as to heat indirectly the corresponding ink area B of an ink absorbing member 2. The viscosity or the surface tension of ink on the heated ink area B decreases while the conductivity increases. Since an electrostatic field is formed between the base member 1 and an electrostatic induction electrode 4, the heated ink area B is attracted electrostatically to the side of a recording sheet 6 and projects, thereby the end portion of an ink pole 3a comes into contact with the recording sheet 6 to form an ink dot D.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Field of Industrial Application] This invention relates to an inkjet recording device, and is particularly useful for increasing the density of recorded images and increasing the recording speed. Effective inkjet paper J, 1 - Concerning improvements in recording devices.

[Prior art j] Conventional inkjet recording devices have a number of ink ejection devices that seal the ink, and ejection ports (
It is known that the ink ejecting device is configured such that the ink ejecting device is configured with an orifice, and a pressure pulse is appropriately applied to the ink ejecting device to eject ink from the ejecting port.

In this type, it is difficult to downsize the ink ejection device because it is necessary to maintain a large volume ratio between the ejection port and the ink ejection device in order to maintain the ink ejection operation from the ejection port. However, it is necessary to increase the pitch between the ejection ports to some extent, making it impossible to set high image recording density. Therefore, there is a problem that the recording speed inevitably decreases.

As a means to solve this problem, magnetic ink is placed near the magnetic electrode array, and the swelling of the ink caused by the magnetic field is used to form an ink ejection state that corresponds to the image density, and the magnetic ink is recorded using an electrostatic field. Ink is applied to the so-called magnetic inkjet method (Japanese Patent Application Laid-Open No. 55-69469) in which the ink is ejected toward the sheet side, and a slit-shaped ink reservoir parallel to the electrode array is filled with ink, and the ink is opposed to the recording sheet through the recording sheet. This is an application of the so-called planar inkjet method in which ink is ejected toward the recording sheet according to the electric field pattern formed between the electrode and the electrode array (Japanese Patent Laid-Open No. 5
6-37163), or by applying thermal energy to the ink to rapidly heat the ink and cause film surface boiling, causing bubbles to rapidly grow within the ejection port (orifice). A so-called thermal bubble jet method has been devised (Japanese Patent Laid-Open No. 161664/1983) in which ink is ejected from an ejection port in an upper pressure range.

In each of the above-mentioned conventional inkjet recording devices,
In either case, not only can the density of the recorded image be increased, but also high-speed recording can be performed since electronic scanning is possible.

[Problems to be Solved by the Invention] However, in the type applying the magnetic inkjet method described above, it is necessary to use ink mixed with magnetic powder, so it is necessary to use black ink as the ink. This creates a problem in that it becomes difficult to obtain a color image by overprinting ink. Also,
In the type that applies the above-mentioned planar inkjet method, it is possible to improve ink clogging by eliminating the need for a minute orifice, but since a high voltage must be applied to make the ink fly, In order to prevent voltage leakage between adjacent electrodes, it is necessary to drive the electrode array in a time-division manner, which is not desirable for high-speed recording. Furthermore, in the case of applying the thermal bubble jet method mentioned above, it is necessary to rapidly raise the temperature of the heating element in order to cause film surface boiling, and as a result, thermal deterioration of the ink and heating There is a problem in that the heat-generating resistor protective layer provided as a means is likely to be thermally degraded.

In order to solve and overcome such problems, the inventors of the present invention filled a slit-shaped ink storage section with ink, applied thermal energy to this ink according to an image signal, and heated the ink based on a predetermined electrostatic field. A recording apparatus using a so-called thermostatic inkjet method has already been proposed in which the ink portion is ejected toward the recording sheet.

According to this type, it is not necessary to use magnetic ink by the so-called magnetic inkjet method, and it is not only possible to easily realize coloring based on overprinting of ink, but also it is not necessary to use magnetic ink by the so-called magnetic inkjet method. It is no longer necessary to make the ink fly using only an electric field, and there is no need to increase the strength of the electrostatic field to an extremely large extent, so it is possible to effectively prevent voltage leaks between the ink and the vicinity of the ink. Since it is no longer necessary to fly the ink using only energy, the thermal energy M can be suppressed to some extent, and thermal deterioration of the ink can be effectively prevented. Therefore, it is possible to perform high-speed, high-density recording while effectively preventing the drawbacks of conventional methods.

However, in such thermostatic inkjet recording devices, a heating element array in which a plurality of heating resistors are arranged according to the image density marks is usually used as the ink heating means, so it is structurally difficult. Assembling the heating element array
Not only will the efficiency of heat transfer to the ink deteriorate,
If the heat generating element array is rapidly heated in order to increase the recording speed, there is a risk that the constituent members may be thermally destroyed due to differences in thermal expansion or heat accumulation of the materials used in the heat generating element array.

In addition, because the ink storage section must be filled with ink and the ink must be resupplied quickly after the ink has flown out, the usable ink is limited to those with relatively low viscosity and fluidity. , That's it (J has the problem of lacking in versatility as an inkjet recording device.

[Means for Solving the Problems 1] This invention has been made in view of the above problems, and is based on the so-called thermoelectrostatic inkjet method that enables high-speed, high-density recording. To provide an inkjet recording cleft that enables rapid heating of ink while further improving heat transfer efficiency to the ink, and also expands the types of ink that can be used and increases the versatility of the dosage itself. It is.

That is, the present invention provides a radiation absorbing and conductive base member, an insulating ink absorbing member disposed on the base member for holding ink, and a predetermined space between the ink absorbing member and the ink absorbing member. Electrostatic induction electrodes are disposed facing each other with a gap and generate an electrostatic field between the surface of the ink absorbing member and a predetermined portion of the base member.ii! ii#g! an image control means for irradiating radiation according to a signal, a recording sheet is inserted between the electrostatic induction electrode and the ink absorbing member, and the ink of the corresponding ink absorbing member is transferred to the base member by the radiation. The heated ink is caused to fly toward the recording sheet by the electrostatic force between the electrostatic induction electrode and the ink absorbing member.

In such technical means, the base member may have a single-layer structure, or may be a radiation-absorbing and conductive material on a radiation-transmitting support layer such as glass or resin film. It may have a structure in which base layers having properties are laminated, or it may be intermediate between a single layer and a lamination. As the upper single-layer type, a polymer resin film in which colored conductive fine particles such as carbon black are dispersed is suitable, and materials with relatively excellent heat resistance such as polyimide and polycarbonate resin are desirable from the viewpoint of the intended use. . In addition, as a laminated type, if a certain degree of mechanical strength is given to the support layer side, mechanical strength is not required for the base layer, so it can be formed into a thin film to improve heat conduction efficiency to the ink absorbing member. be able to. When flexibility is not required for the support layer, glass is suitable; when flexibility is required, polyimide, polyester, polycarbonate films, etc. are used. On the other hand, as the base layer, a resin thin film layer in which carbon black is dispersed, a metal vapor deposited layer, a carbon vapor deposited layer, etc. are used. Furthermore, as an intermediate type between a single layer and a laminated layer, there may be mentioned, for example, a single-side electrically conductive treated film in which the dispersion distribution of carbon black or the like is induced in the thickness direction of the resin film.

Further, as the ink absorbing member, a porous aluminum sheet obtained by subjecting a mesh of nylon, Teflon, etc., a non-woven fabric, or an aluminum sheet to a directional etching process, etc. are used. At this time, when the porous aluminum sheet is used as an ink absorbing member, it is necessary in design to perform an alumite treatment to impart insulation properties.

Furthermore, the ink used must have a resistivity at the temperature at which the ink flies in the irradiated area, or in other words, at the operating temperature of the ink, such that it causes electrostatic induction in the ink. It is.

Specifically, since the temperature distribution of each part of the ink varies to some extent, the operating temperature of the ink cannot be unambiguously determined, but if the ink has a resistivity of about 10140α or less at 80°C, , it is possible to cause ink to fly due to electrostatic induction. However, if the resistivity of the ink exceeds 10110 CIR, it is necessary to set the electrostatic field action time to a certain length. Also,
The viscosity of the ink may be appropriately selected from a wide range of inks, ranging from low viscosity inks that are fluid at room temperature to high viscosity inks such as wax and offset printing ink, which are normally solid at room temperature. Furthermore, the design of the means for supplying ink to the ink absorbing member can be changed as appropriate.

Furthermore, the most preferable example of the radiation is a laser beam that is deflected and modulated according to image information, and the light source power etc. are appropriately selected in consideration of printing speed and deflection modulation loss. For example, when applying an irradiation time of about 1 μsec, the light source power needs to be about 1 W or more, and the irradiation time is about 1 μsec.
When applying an irradiation time of about EC, approximately 10 mW or more is required, but when setting a long beam irradiation time, it is desirable to adopt a multi-beam method so as not to reduce the recording speed.

Further, the design of the electrostatic induction electrode may be changed as appropriate as long as it forms a predetermined electrostatic field at least with the ink surface, but as for the voltage applied to the electrostatic induction electrode, The polarity is arbitrarily set to positive or negative using the potential of the base member as a reference potential.

[Function] According to the above-mentioned technical means, when the base member is irradiated with radiation according to the image signal from the image control means, the irradiation part is heated and the temperature of the irradiation part is increased. The ink portion of the corresponding ink absorbing member is heated by thermal conduction, and the heated ink portion flies toward the recording sheet based on the electrostatic field between the ink surface and the electrostatic induction electrode.

At this time, since the base member simultaneously functions as a heat generating member, the generated thermal energy is efficiently transmitted to the ink side, and at least one of the radiation irradiation position and the base member is moved as appropriate. If this is done, the radiation irradiation part will not be fixedly set and will move as appropriate, so the radiation irradiation part will naturally cool down immediately after being heated, and the radiation Unnecessary accumulation of thermal energy in the irradiated portion of the line is avoided.

In addition, by appropriately moving the radiation irradiation part, it is possible to relatively move the heating point of the ink absorbing member, so it is possible to fill the ink absorbing member with ink appropriately at a location other than the location where the inkjet operation occurs. If this is done, there is no need to resupply ink immediately after the ink flies.

[Embodiments] Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.

◎Example 1 In FIGS. 1 and 2, an inkjet recording apparatus includes a base member 1 having radiation absorbing properties and conductivity, and an ink absorbing member disposed on the base member 1 and holding ink 3. 2 and the ink absorbing member 2, an electrostatic induction electrode 4 is disposed facing the ink absorbing member 2 with a predetermined gap therebetween and generates an electrostatic field between the ink absorbing member 2 and the base member 1. It includes an image control unit 5 that irradiates a predetermined region with a laser beam S as radiation according to an image signal.

In this example, the base member 1 is made of a conductively treated polyimide film 1b (Hokushin Kogyo Co., Ltd.) having a carbon black dispersion layer on one side of the polyimide film 1a.
A laminated polyimide EC belt (70 mm thick) made by Co., Ltd. is used, and the base member 1 is adapted to move at a predetermined speed.

Further, as the ink absorbing member 2, a nylon mesh (N0380T, 380 mesh, manufactured by NBC Koso Co., Ltd., thickness 75 μm, opening 32 μm) is used, and this ink absorbing member 2 is a conductive treatment of the base member 1. It is attached on the surface of the polyimide film 1b.

The ink 3 held in the ink absorbing member 2 is a mineral oil-based oil-based ink in which carbon black is dispersed and has a viscosity of about 1000 cps and a volume resistivity of about 109 ΩCtS at room temperature. As a method of supplying this ink 3, for example, an ink supply roll 8 such as a sponge is placed in an ink reservoir 7 containing the ink 3.
The ink supply roll 8 and the ink absorbing member 2 are brought into contact with each other at appropriate locations to allow the ink 3 to penetrate into the ink absorbing member 2 side, and while pressing the ink absorbing member 2 with the elastic blade 9, excess ink is removed. The one that squeezes out the filtrate is used.

Further, a recording sheet 6 is disposed oppositely at a position 200 μm apart from the surface of the ink absorbing member 2, and current is passed between the conductive surface of the base member 1 and the electrostatic induction electrode 4 on the back surface of the recording sheet 6. A potential difference of 1500 (V) is applied by the power supply 10. The image control unit l-5 is a continuous wave YAG (approximately 1W) (
A yttrium, aluminum, garnet) laser is used, and its laser beam diameter is narrowed down to about 80 μm in diameter by the conductive surface of the base member 1, and its irradiation time is set to about 1 μsec per dot.

Therefore, according to the inkjet recording apparatus according to this embodiment, when the base member 1 is irradiated with a predetermined laser beam S corresponding to an image signal, as shown in FIG. A is heated and its temperature rises, and the ink area B of the ink absorbing member 2 corresponding to this beam irradiation part A is indirectly heated. Then, the viscosity and surface tension of the heated ink region B decrease, and the conductivity decreases by 1. At this time, since an electrostatic field is formed between the base member 1 and the electrostatic induction electrode 4 as shown by the arrow a in the figure, the heated ink area B is As shown, the ink column 3a is electrostatically attracted toward the recording sheet 6 and bulges, and the end of the ink column 3a comes into contact with the recording sheet 6, forming an ink dot D. In addition, when the inventors actually conducted an experiment under the above-mentioned conditions, it was found that a diameter of approximately 100 μm was formed on the recording sheet 6 portion corresponding to the beam irradiation position.
It was confirmed that ink dots D were formed.

◎Example 2 In FIG. 3, an inkjet recording apparatus using high viscosity ink is shown. In the figure, the base member 1 is a Ta2N layer deposited on a cylindrical glass substrate with a thickness of about 1000 A by reactive sputtering, and the ink absorption member 2 is a Ta2N layer deposited on the base member 1 with a thickness of about 50 μm. A layered and bonded polyester nonwoven fabric is used. In addition, as ink 3, about 70℃
A wax ink made by dispersing carbon black in wax having a melting temperature of 3 is used.
A porous ink supply roll 11 made of sponge or the like is filled in advance. The ink supply roll 11 is placed in contact with the ink absorption member 2, and a quartz lamp 12 for heating is provided near the contact portion, and the ink supply roll 11 is heated by the irradiated heat from the quartz lamp 12. The filled ink is appropriately supplied to the ink absorbing member 2.

Then, under the same conditions as in Example 1, a 20 mW semiconductor laser constituting a part of the image control means 5 was used to generate a laser with a diameter of 2 mm.
When the beam S was narrowed down to 0 μm and irradiated for 80 μsec, it was confirmed that ink dots with a diameter of about 50 μm were formed on the recording sheet 6.

[Effects of the Invention] As described above, the inkjet recording apparatus according to the present invention provides the following effects without sacrificing the advantages of the so-called thermostatic inkjet system.

First, the radiation-absorbing base member is appropriately irradiated with radiation corresponding to the image signal, and the thermal energy of the base member is conducted to the ink in the ink-absorbing member to heat it. Compared to the type in which a heat generating element array is arranged on a predetermined substrate, the amount of thermal energy loss is smaller.
In addition to improving the efficiency of heat transfer to the ink,
By moving the radiation irradiation position or the base member appropriately, it is possible to change the radiation irradiation part position appropriately, and even if the radiation irradiation timing is accelerated to some extent, the radiation irradiation of the base member There is no risk that thermal energy will be accumulated unnecessarily in the recording section and cause thermal damage, and the recording speed can be increased accordingly.

Second, the ink absorbing member is filled with ink in advance,
Since the recording operation can be performed continuously using the ink in each part of the ink absorbing member, there is no need to re-supply ink immediately after the ink flies, and the range of application of the ink can be reduced accordingly. The inkjet recording apparatus can be used in a variety of applications, from low to high viscosity, increasing the versatility of the inkjet recording apparatus.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of Embodiment 1 of an inkjet recording apparatus according to the present invention, FIG. 2 is an explanatory diagram of its operating principle, and FIG. 3 is an illustration of Embodiment 2 of an inkjet recording apparatus according to the invention. FIG. [Explanation of symbols] (S)... Laser beam (radiation) (1)... Base member (2)... Ink absorbing member (3)... Ink (4)... Electrostatic induction electrode (5)...image control unit (image control means) (6)
...Record sheet patent applicant Fuji Xerox Co., Ltd. Agent
Patent attorney Tomohiro Nakatoshi (2 others) 5: Laser beam robot

Claims (1)

[Scope of Claims] 1) Between a base member having radiation absorbing properties and conductivity, an insulating ink absorbing member disposed on this base member to hold ink, and this ink absorbing member. Electrostatic induction electrodes that are arranged to face each other with a predetermined gap and generate an electrostatic field between them and the surface of the ink absorbing member, and image control that irradiates a predetermined portion of the base member with radiation according to an image signal. and means for inserting a recording sheet between the electrostatic induction electrode and the ink absorption member, and heating the ink of the corresponding ink absorption member by the radiation through the base member, An inkjet recording apparatus characterized in that the heated ink portion is caused to fly toward a recording sheet by electrostatic force between an electrode and an ink absorbing member. 2) The inkjet recording apparatus according to claim 1, wherein the image control means uses a laser beam as the radiation.