JPS62278045A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To prevent a thermal degradation of ink and to enable a high speed high density recording, by applying a thermal energy according to an image signal of ink filled in a slit space section, and flying a portion of heated ink to a recording sheet side based upon a specified electrostatic field. CONSTITUTION:In a head body 1, glass substrates 2, 3 are arranged through a spacer member 4 to form a slit space section 5 while a control electrode 6 and an opposed electrode 8 are arranged on the inner face side of the glass substrates 2, 3 and the non-exposed portion of the control electrode 6 is covered with an insulative protection layer 7. Ink 10 dissolved with an oil soluble dye having a resistivity of at most 10<7>OMEGAcm is fed through a pressurizing means into the slit space section 5. When a control voltage corresponding to an image signal is applied onto the control electrode 6, an ink layer 10 positioned between the electrode 6 and the opposed electrode 8 is supplied with power and heated, thereby the viscosity and the surface tension decrease while the conductivity increases. Since an electrostatic field is formed on the surface of the ink 10 and the layer of an electrostatic induction electrode 11, the ink portion 10 is attracted electrostatically to the side of a recording sheet 12 so as to form ink dots thereon.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an inkjet recording device, and is particularly effective in increasing the density of recorded images and increasing the recording speed. This invention relates to improvements in inkjet recording devices.

[Prior Art] A conventional inkjet recording device has a large number of ink ejection devices that seal ink, and ejection ports (
It is known that the ink ejection device is provided with an orifice (orifice), respectively, and a pressure pulse is appropriately applied to the ink ejection device to eject ink from the ejection port.

In this type, it is difficult to downsize the ink ejecting device because it is necessary to ensure a large volume ratio between the ejection port and the ink ejecting device in order to maintain the ink ejecting operation from the ejection port. Therefore, the bits arranged between the ejection ports have to be set to a certain degree, which not only makes it impossible to set the recording density of the image to a high level, but also makes it impossible to set the recording density of the image to a high level. Since the ink is ejected, there is a problem in that the recording speed inevitably decreases.

As a means to solve this problem, ill ink is placed near the magnetic electrode array, and the image fg! There are methods that apply the so-called magnetic inkjet method (Japanese Unexamined Patent Publication No. 55-69469), which forms an ink ejection state corresponding to the density and causes magnetic ink to fly toward the recording sheet side using an electrostatic field, and electrode arrays and 1
A 17-row slit-shaped ink reservoir is filled with ink, and the ink is flown toward the recording sheet according to an electric field pattern formed between electrodes and electrode arrays facing each other via a recording sheet. An application of the inkjet method (Japanese Unexamined Patent Publication No. 56-37163), or by applying thermal energy to the ink, the ink is rapidly heated to cause film surface boiling, and the ink is heated inside the ejection port (orinois). This is an application of the so-called thermal bubble jet method, in which ink is ejected from the ejection port by increasing pressure by rapidly growing bubbles (Japanese Patent Laid-Open No. 55-161664).
No. 2) has been proposed.

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 is possible because electronic scanning is possible.

[Problems that the invention attempts to solve J However, in the case of the type applying the magnetic inkjet method described in 1., it is necessary to use an ink mixed with magnetic powder, so it is necessary to use a black ink as the ink. This causes a problem in that it becomes difficult to obtain a color image by overprinting ink. Also, -
[Article] Types that apply the inkjet method can reduce ink clogging by eliminating the need for minute orifices, but they require a high voltage to be applied to make the ink fly. In order to prevent voltage leakage between adjacent and nearby 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.

Means for Solving Problems] The present invention has been made by focusing on the following problems, and while increasing the density of recorded images and increasing the recording speed, it is possible to Inkjet recording that can reliably obtain color images through overprinting, effectively prevent voltage leaks at electrodes, thermal deterioration of ink, etc., and further minimize loss of energy consumption. It provides equipment.

That is, the present invention includes an insulating head body having a slit-like space in which ink that can generate heat when energized is accommodated, and a head body that is divided in accordance with the pixel density near the edge of the opening on one side of the slit-like space. a plurality of control electrodes arranged;
Electrostatic induction that forms a predetermined electrostatic field between a counter electrode provided on at least a part of the other side of the slit-shaped space and the ink surface that is disposed opposite to the opening surface of the slit-shaped space. A recording sheet is movably inserted between the ink surface and the electrostatic induction electrode, and a control signal corresponding to the image signal is applied to each of the control electrodes to face each control electrode. Each part of the ink layer located between the electrodes is electrically heated as appropriate, and the heated ink layer parts are flown toward the recording sheet based on the electrostatic field formed between the ink surface and the electrostatic induction electrode. This is how it was done.

In such technical means, as long as the head body has at least a slit-like space, the membrane H1 may be changed as appropriate; however, considering the manufacturing workability of the control electrode and the counter electrode, It is preferable that a pair of plates provided with electrodes are spaced apart with a spacer interposed therebetween.

The longitudinal dimension of the slit-like space is determined by considering the image forming range, and the slit width is determined by considering the pixel density, for example, a pixel density of 16 dots/l1.
25 μm to 100 μm for 11 to 8 dots/m
The amount is set as appropriate. The number of control electrodes and the spacing between the control electrodes can be appropriately selected depending on the pixel density. It is necessary to arrange a control electrode at the In this case, there is no problem even if the control electrode extends to a position away from the opening surface of the slit-shaped space, but since the part of the ink that actually flies is near the entrance of the slit-shaped space, the energized Considering efficiency, it is desirable to expose only the control I electrode portion corresponding to the inlet portion and cover the other portions with an insulating protective layer. Furthermore, the counter electrode needs only to be formed in a range where a current conducting path can be formed between it and the control electrode, and if manufacturing workability is considered, it is possible to uniformly form the counter electrode facing the control electrode. desirable.

Furthermore, the ink used must have a resistivity within a range that allows resistance heating by energization. Specifically, when trying to realize a drive element for the control signal applied to the control electrode with an integrated transistor array, the permissible switching voltage is 500V or less, and the ink is energized and the resistance is 10m when heating
Since approximately W or more is required, the current to be applied is 20 μA.
It is necessary to flow more than that. Therefore, the resistance when energized is 2.58Ω or less, and the resistivity of the ink is approximately 1.
070 cm or less, more preferably 1040 cm or less is required. Further, as the above-mentioned ink, both water-based and oil-based inks can be used, but oil-based inks are preferable because they are less susceptible to electrolysis at the electrode portion and change in resistance over time.

Furthermore, the design of the electrostatic induction electrode may be changed as appropriate as long as it forms a small (at least a predetermined) electrostatic field between it and the ink surface; The polarity of is set so that the potential difference between the electrostatic induction electrode and the control electrode is larger than the potential difference between the electrostatic induction electrode and the counter electrode.In other words, the control voltage is set with the counter electrode as a reference potential. When a positive voltage is applied to , the polarity of the applied voltage becomes negative.

[Operation] According to the above-mentioned technical means, when a control signal corresponding to an image signal is applied to the control electrode, the ink layer located between the control electrode and the counter electrode directly responds to the image signal. The viscosity and surface tension of the heated ink layer portion decrease and the conductivity increases, and this heated ink layer portion is formed between the electrostatic induction electrode and the ink layer. Based on the electrostatic field, the particles fly toward the recording sheet.

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

1 and 2, the head main body 1 has a pair of glass substrates 2.3 spaced apart by a spacer member 4, and a slit-shaped space 5 is secured between the two glass substrates 2.3. In this embodiment, one of the glass substrates 2 is J3.
On the inner surface side, a metal layer consisting of Cr (chromium)/Cu (copper)/Cr is deposited to a thickness of 500A/1μm/500A by vacuum evaporation, and then this metal layer is deposited using photolithography to form a layer of, for example, 16 The control electrodes 6 are divided and arranged at 1/m.

Then, a SiO2 film is sputtered to a thickness of approximately 5 μm on the non-exposed portion of the control electrode 6 so that the end portion of the control electrode 6 is exposed by approximately 50 μm from the opening surface of the slit-shaped space 5.
The non-exposed portion of the control electrode 6 is covered with an insulating protective layer 7. Further, on the inner surface side of the other glass substrate 3, a metal layer made of Cr/cu/Cr is deposited to a predetermined thickness by vacuum deposition, and this metal layer functions as a uniform counter electrode 8. ing. Further, the gap between the pair of glass substrates 2.3 is set to 30 μm by the spacer member 4, and the gap between the pair of glass substrates 2.3 is set to 30 μm.
A portion of the spacer member 4 between the spacer members 3 and 3 is sealed with a heat-sealing glass paste.

-10= Also, the end of the head body 1 is polished as appropriate, and the distance between the opening surface of the slit-shaped space 5 and the control electrode 6 is 50.
In addition, the distance 1!1 between the opening surface of the slit-like space 5 and the counter electrode 8 is set to 20 μm.

Further, an oil-soluble dye-dissolving ink 10 containing diisopropylnaphthalene as a main solvent is supplied to the sulin 1 to 5-shaped spaces 5 by a pressurizing means (not shown).

In this example, the ink 1o was heated at 25°C.
A material having a viscosity of 50 cps and a volume resistivity of 4×10 6 Ωcm is used.

Furthermore, based on the ON operation of the driving switching element 15, a current of 300 V and 5 m5ec is applied to the control electrode 6 as a control signal corresponding to the image signal, and the current flowing at this time is 5 m5ec. 0.5 between
It changes from μA to 50 μA. On the other hand, a roll-shaped electrostatic induction electrode 11 is arranged at a distance of 300 μm at a portion facing the opening surface of the slit-like space 5, and this electrostatic induction electrode 11 is connected to the recording sheet 12.
It also serves as a support surface. A voltage of -1500 V is applied to the electrostatic induction electrode 11, so that a predetermined electrostatic field is formed between the ink 10 surface and the electrostatic induction electrode 11. In FIG. 2, reference numeral 16 is a power supply for supplying current to the control electrode 6, and reference numeral 17 is a power supply for supplying current to the electrostatic induction electrode 11.

Therefore, according to the inkjet recording apparatus according to this embodiment, when a control voltage corresponding to a predetermined image signal is applied to a certain control electrode 6, as shown by arrow a in FIG. Ink 1 located between the opposing type MA8
The 0 layer is directly heated by electricity, and the viscosity and surface tension of the heated ink 10 portion decreases and the conductivity increases. In this case, since an electrostatic field as shown in the figure is already formed between the surface of the ink 10 and the electrostatic induction electrode 11, the heated portion of the ink 10 is As shown by the imaginary line, the ink column 1 is electrostatically attracted to the recording sheet 12 side and raised.
The end portion 0a contacts the recording sheet 12 to form ink drums 1 to 1. Incidentally, when the inventors of the present application actually conducted an experiment under the conditions of the above-mentioned embodiment, it was confirmed that ink dots having a diameter of approximately 50 μm were formed on the recording sheet 12.

In addition, in this embodiment, when heating the ink 1o, the ink 10 layer is made to function as a heat generating resistor. Set the body 2o according to the pixel density9)
, a method of indirectly heating the ink 10 by causing the heat generating resistor 20 to generate heat appropriately according to the image signal (due to the large heat loss due to heat conduction to the heat generating resistor substrate, the human body thermal energy is 0.1 to 0. In addition, the amount of loss of thermal energy supplied to the ink 1o is suppressed to a small level compared to the case where about 3 W is required. In this embodiment, since it is sufficient to secure a space for disposing the W electrode 6 in each unit area of the ink 10, it is possible to further increase the density of the recorded image.

Furthermore, in this case, each control electrode 6 is exposed only at the entrance of the slit-shaped space 5, and the sacrum is covered with an insulating protective layer 7, so that the current supply path to the ink 10 is Since the energization energy is limited to the location corresponding to the exposed portion of the control electrode 6, unnecessary diffusion of the energization energy is eliminated. Therefore, an appropriate temperature distribution corresponding to the image signal is obtained on the surface of the ink 10, and the heated portion of the ink 10 is reliably flown toward the recording sheet 12.

[Effects of the Invention] As described above, according to the inkjet recording apparatus according to the present invention, thermal energy is applied to the ink filled in the slit-shaped space according to an image signal, and
Since the heated ink portion is ejected toward the recording sheet based on a predetermined electrostatic field, there is no need to use magnetic ink using the so-called magnetic inkjet method, which facilitates colorization based on overprinting of ink. Not only can this be achieved, but it also eliminates the need to fly ink using only an electrostatic field, as is the case with the so-called flat inkjet method.
Since there is no need to extremely increase the strength of the electrostatic field, it is possible to effectively prevent voltage leaks between areas near the ink.
Since there is no need to use heat-L energy to fly the ink as in the so-called thermal bubble jet method, the amount of thermal energy can be reduced to a certain extent, making it possible to effectively prevent thermal deterioration of the ink. Become. Therefore, high-speed, high-density recording can be performed while effectively preventing the drawbacks of conventional methods.

Further, according to the inkjet recording apparatus of the present invention, thermal energy is directly applied to the ink, and the ink itself is made to function as a heat generating resistor, so that a heat generating resistor is used separately from the ink as a heating means for the ink. It is no longer necessary to indirectly heat the ink, and the amount of heat energy lost can be reduced, making the recording process more efficient. When applying current, it is necessary to connect a pair of electrodes to each unit, but in this invention, one control electrode is provided for each unit area of ink, and each control electrode Since it is sufficient to provide opposing poles to form a current-conducting path between the ink and the ink, the space of each unit area of ink can be narrowed, and the density of the recorded image can be further increased.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the infusiera 1 to recording apparatus according to the present invention, FIG. 2 is a top view taken along the line ■-II in FIG. 1, and FIG. 3 is an inkjet recording apparatus according to the embodiment. FIG. 4 is an explanatory diagram showing a recording operation process, and FIG. 4 is an explanatory diagram showing a comparative example of the inkjet recording apparatus according to the present invention. [Explanation of symbols] (1)...Head body (5)...Slit-shaped space (6)...Control voltage ffl (8)...Counter electrode (
10)... Ink (11)... Electrostatic induction electrode (12)... Recording sheet

Claims (1)

[Scope of Claims] 1) An insulating head body having a slit-like space in which ink that can generate heat when energized is accommodated, and the slit-like space is divided near the edge of an opening on one side in accordance with pixel density. a plurality of control electrodes disposed, a counter electrode provided on at least a portion of the other side of the slit-shaped space, and a counter electrode disposed opposite to the opening surface of the slit-shaped space and provided between the ink surface and the ink surface. A recording sheet is movably inserted between the ink surface and the electrostatic induction electrode, and a control signal according to the image signal is sent to each of the control electrodes. The heated ink layer is heated based on the electrostatic field formed between the ink surface and the electrostatic induction electrode. An inkjet recording device characterized in that a part of the inkjet recording device is made to fly toward the recording sheet side. 2) Claim 1, wherein the ink has a resistivity of 10^7 Ωcm or less.
The inkjet recording device described in Section 1.