JPH02286345A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To further ensure the possibility of resupplying ink to an ink outlet part and to contrive to accelerate a printing speed by applying a spare heat energy from the region out of the ink outlet part, to which region a heat energy by a heat energy-applying means is applied, to the side of the interior of an ink chamber. CONSTITUTION:The ink chamber 2 of an ink jet recorder equipped with an electrostatic field-forming means 6 for applying an electrostatic field directed to the recording sheet 5 side to ink 3 retained by an ink outlet part 2a is provided with a passage resistance regulator 7 for reducing the resistance of an ink chamber 2 passage leading to the ink outlet part 2a, and is also provided with a preheating means 8 for applying a spare heat energy from the region out of the ink outlet part 2a, to which region a heat energy by a heat energy- applying means 4 is applied, to a part positioned on the side of the interior of the ink chamber 2. Because a spare heat energy from the preheating means 8 is applied to the ink 3, the ink 3 is smoothly supplied to the ink outlet part 2a side by the passage resistance regulator 7 after an ink 3 outlet operation and moves to the exit side of the ink outlet part 2a more quickly by a portion preheated at an entrance part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to an a1 thermoelectrostatic type inkjet recording device that ejects ink by the cooperative action of thermal energy and electrostatic energy, and particularly relates to an inkjet recording device using a thermoelectrostatic type in which ink is ejected by the cooperative action of thermal energy and electrostatic energy. This invention relates to improvements to inkjet recording devices that use ink to speed up printing operations.

[Prior Art] As an inkjet recording apparatus of this type, for example, the one described in Japanese Patent Application Laid-Open No. 62-225388 is already known.

This forms a slit or through-hole ink chamber in the head body that is filled with a predetermined amount of ink, and a group of heating resistors corresponding to the pixel density is placed on one side of the ink ejection part on the exit side of this ink chamber. An array of heating resistors arranged in a row is provided, and an electrostatic field forming means is provided to apply a negative electrostatic field from the ink surface toward the recording sheet side. Energy is applied to the ejecting ink of the ink ejecting unit, and the ejecting ink heated by the electrostatic attraction force from the electrostatic field forming means is ejected toward the recording sheet side according to the image pattern. It is.

[Problem to be Solved by the Invention J] Incidentally, in such a thermoelectrostatic inkjet recording device, there needs to be a viscosity difference between the image forming part and the non-image forming part, and the ink has a certain high viscosity at room temperature. It becomes necessary to use the .

Then, a problem arises in that the ability to resupply the ink to the ink ejection section inevitably deteriorates, and the printing speed decreases accordingly.

As a means to solve such problems, the present applicant has proposed, for example, Japanese Patent Application No. 62-182381 and Japanese Patent Application No. 62-182.
The technology described in No. 382 has already been provided.

This is achieved by providing a flow path paper FE adjustment &1 that reduces flow path resistance in the ink chamber leading to the ink ejection section, and the presence of this flow path resistance adjustment section improves the ability to resupply ink to the ink ejection section. It was designed to improve the performance.

However, when the viscosity of the ink used is relatively high, it is difficult to sufficiently improve the ink resupply performance just by the presence of the flow path resistance adjusting section as described above.
In some cases, this method is insufficient as a means to meet the demand for increased printing speed.

The present invention has been made based on the above-mentioned viewpoints, and effectively prevents erroneous ejection of ink from the ink ejection section while reliably improving the ability to resupply ink to the ink ejection S1m<. An object of the present invention is to provide an inkjet recording device that can fully satisfy the demand for increased printing speed.

[Means for Solving the Problems J1 That is, the present invention has a head main body 1 having an ink ejection portion 2a in which ejection ink 3 is held on the outlet side of an ink chamber 2, as shown in FIG. , a thermal energy applying means 4 for applying thermal energy according to image information to the ejecting ink 3 held in the ink ejecting section 2a, and an ink ejecting section 2.
It is assumed that the inkjet recording apparatus is equipped with an electrostatic field forming means 6 that applies a #71 electric field toward the recording sheet 5 side to the ink 3 held in the ink chamber 2, and the ink chamber 2 has an ink ejection section 2a. A flow path resistance adjusting section 7 is provided to reduce the resistance of the flow path leading to the ink chamber 2, and a flow path resistance adjusting section 7 is provided to reduce the resistance of the flow path of the ink chamber 2. This is characterized by the provision of preheating means 8 to which preheat energy is applied.

In such technical means, if the head body 1 has an ink chamber 2 provided with a flow path resistance adjustment @tJs7, the design of the head body 1's constituent material, the shape of the ink chamber 2, etc. may be changed as appropriate. The specific structure of the ink ejection portion 2a may be either slit-like or through-hole-like.

In this case, it is necessary to set the outlet width dimension of the ink discharge section 2a in consideration of the print dot diameter, and its depth should be determined not only in terms of the discharge amount of the ink 3 but also in the retention of the ink 3. It is necessary to set it to a certain length considering the gender.

The flow path resistance adjusting section 7 may be anything that can reduce the flow path resistance of the ink chamber 2 leading to the ink discharge section 2a, and may be any ink reservoir having a width gap wider than the width gap of the ink discharge section 8Ii2a. The head body may have a two-stage gap structure by forming a section, or a tapered head body may be formed by forming a pair of plate-like members for forming both ink chambers and arranging them at an angle so as to narrow toward the ink discharge section 2a side. Also, the thermal energy applying means 4 may be a wall.
The ink may be indirectly heated using a heating resistor array consisting of a plurality of heating resistors arranged according to the 111M density on one side near the exit of a, or the pixel may be heated using radiation as a heating source. The ink may be heated to the density fIIT, or the ink itself having a predetermined resistivity may be heated by being directly energized, or the like may be selected as appropriate.

Furthermore, the design of the electrostatic field forming means 6 may be changed as appropriate as long as it generates an appropriate electrostatic attraction force in the direction of raising the ink 3 from the ink 3 surface to the recording sheet 5 side during printing operation. do not have.

Furthermore, the preheating means 8 can be appropriately selected as long as it can appropriately heat the ink 3 located on the inlet side of the ink discharge section 2a. The heating source may be provided on the same side as the application portion, or may be provided on the opposite side, or may be provided on both sides. In this case, the heating source may be provided individually for each pixel, or may be provided continuously in a strip.

Further, the heating source for the preheating means 8 may be provided independently, but from the viewpoint of reducing the number of parts, for example, it may be a component of the electrostatic field forming means 6 on the head body 1 side. It is preferable that the conductive layer is formed of a resistive material so that it also serves as the conductive layer. Further, the heating timing of the preheating means 8 may be such that it is always heated, but the ink 3 for ejection in the ink ejection part 2a
From the viewpoint of minimizing the preheating phenomenon to the entire area of the ejecting ink 3 while ensuring a sufficiently large temperature contrast between the parts, the preheating J energy is synchronized with each ink ejection cycle and pulsed. It is preferable to apply it to

Furthermore, regarding the ink used, the viscosity and surface tension of the ink are reduced to the extent that the ink can fly in a predetermined electrostatic field when a predetermined thermal energy is applied, and the electrical conductivity of the ink is It is necessary to improve

[Operation] According to the technical means as described above, the ink ejection section 2a
A flow path resistance adjustment section 7 for reducing flow path resistance is provided in the ink chamber 2 portion leading to the ink discharge section 2.
Since the preheating energy r from the preheating means 8 is applied to the ink 3 at the inlet part a, after the ink 3 ejection operation, the ink 3 is heated to the ink ejection part by the flow path resistance adjustment part 7. The ink 3 is smoothly supplied to the ink ejection part 2a side, and the ink 3 supplied into the ink ejection part 2a is
Since the ink is preheated at the inlet portion of the ink ejection portion 2a, it quickly moves toward the outlet side of the ink ejection portion 2a.

Further, since the preheating means 8 heats the ink 3 located in the artificial part of the ink ejection section 2a, the temperature of the ejection ink 3 reaching the outlet side of the ink ejection section 2a rises unnecessarily. Therefore, it is possible to ensure a sufficiently large temperature contrast in the three portions of the ejecting ink.

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

Embodiment 1 In FIGS. 2 to 4, an inkjet recording apparatus includes a head main body 10 having an ink ejection part 11a in which ejection ink 12 is held on the outlet side of an ink chamber 11, and a head body 10 having an ink ejection part 11a that holds ejection ink 12 on the outlet side of an ink chamber 11, and Thermal energy applying means 30 applies thermal energy according to the image information to the ejected ink 12, and an electrostatic field directed toward the recording sheet 40 is applied to the ink 12 held in the ink ejecting section 11a. The apparatus includes an electrostatic field forming means 50 and a preheating means 60 for applying γ preheating energy to the ink 3 located at the inlet of the ink discharge section 11a.

In this embodiment, the head main body 10 has a pair of insulating substrates 13.14 made of alumina ceramic or the like separated from each other with a substrate member 15 interposed therebetween, and a sulin L-shaped ink chamber 11 between the two insulating substrates 13.14. It was designed to ensure that The ink chamber 11 has an ink discharge section 1.
A flow path resistance adjusting section 20 is formed to reduce the flow path resistance of the ink chamber 11 leading to the ink chamber 1a.
0, a recess 21 is provided in one insulating substrate 14, and the ink ejection part 11 has a predetermined width gap (for example, 40 μyrt).
The ink reservoir portion 11b is formed with a wide gap (for example, 1 m) with respect to a. An ink supply bypass 116 is connected to the ink chamber 11, and an ink pump supplies the ink 12 in the ink tank.
are sequentially supplied to the ink chamber 11 via the ink supply via 16 at a predetermined supply pressure.

Further, the thermal energy V applying means 30 includes the ink ejection section 11a.
T to the 13th surface of one of the 8 substrates located near the exit side of the
A thin film resistor made of an a2N thin film is deposited to a thickness of about 0.2 μIn by sputtering, and a rectangular heating resistor 31 is formed for each pixel density (for example, 8 dots/un) in a photolithography process, and then , 500 layers of nichrome and 1 μm of gold as the adhesive layer as the current-carrying electrode layer.
A pair of energizing electrodes 4132 connected to the base of the heat generating resistor 31 are sequentially attached and patterned using a photolithographic etching process, and a thermal drive signal is outputted to the energizing electrode 32 according to the image information. A drive circuit 33 is connected thereto. Incidentally, the reference numeral 34 is an insulating layer such as 5i02 which insulates and covers the heating resistor 31 and each current-carrying electrode 32.

Further, the electrostatic field forming means 50 includes an inductive electrode 51 provided at a location corresponding to the ink ejection portion 11a on the insulation 1134.1 of the one insulating substrate 13, and an inductive electrode 51 provided from the end surface of the ink ejection portion 11a of the head body 10. A predetermined distance (e.g. 2
00 μm) is interposed between the 160-rule-shaped counter electrode 55 which is spaced apart and also functions as a support surface for the recording channel 40, the dielectric electrode 51 and the counter-type J4i 55, and is synchronized with the thermal drive signal. The electrostatic drive circuit 56 is provided with an electrostatic drive circuit 56 to which an electrostatic drive signal is output.

In this embodiment, the induction electrode 51 has a resistive conductive layer made of Ta2N of about 0.5 cm, similar to the heating resistor 31.
After the film was deposited in micrometers, it was patterned as follows using a nootorithoetching process. That is, the induction electrode 51 includes a rectangular main electrode portion 52 corresponding to the heat generating resistor 31, a connecting portion 53 extending from the center of the main electrode portion 52 on the base side toward the back side of the ink chamber 12; It is composed of a band-shaped common electrode part 54 connected to each connecting part 53 and extending in the longitudinal direction of the insulating substrate 13, and an electrostatic drive circuit 56 is interposed between the common electrode part 54 and the counter electrode 55. ing. Note that the ink chambers 11 are provided at both ends of the common electrode section 54.
An extraction electrode portion 54a extending toward the depth side is integrally formed.

Furthermore, the preheating means 60 includes the induction electrode 51
A preheating resistor 61 which also serves as the common electrode portion 54 of C, and a preheating drive circuit 62 which outputs a preheating drive signal to the preheating resistor 61 using the extraction electrode portion 54a. It is configured. In this embodiment, the preliminary heating resistor 61 (common electrode section 54) is grounded.

Further, the application timing of each drive signal from the thermal drive circuit 33, electrostatic drive circuit 56, and preheat drive circuit 62 is controlled by a timing control circuit 70 as shown in FIG.

Next, the operation of the inkjet recording apparatus according to this embodiment will be explained.

Now, the printing conditions are 0 as thermal drive signal @ T H1.
．． Apply 25W, 2m5ec, static M drive 1h (a
¥]HV, thermal drive signal T1]1 applied (l l,
5 m5ec.

2. with the starting point and the counter electrode 55. OKV.

Q, 5 m5ec, is applied, and a thermal driving signal THI is applied as a preheating driving signal T[12.
01sec, as the starting point, o, IW, 2a for each pixel.
+sec was applied.

Under such printing conditions, using ink with a high viscosity of about 1120 cpS, Comparative Example 1 (no two-stage gap, no preheating means), Comparative Example 2 (with two-stage gap, no preheating means) Comparing the printing operations between the two, it was found that in Comparative Example 1, when the repetitive printing frequency exceeds 100 Hz, image quality defects such as spotting occur due to ink resupply performance, and Similarly, in Comparative Example 2, poor image quality occurs when the repetitive printing frequency exceeds 250 Hz, but in the example (in other words, even when the repetitive printing frequency exceeds 300 Hz, dots etc. occur). Good printing was possible without any problems.

Also, under the above printing conditions, room temperature 1000Cp
The above-mentioned Comparative Example 1.
When comparing the printing operation with Comparative Example 2, it was found that Comparative Example 1
In Comparative Example 2, poor image quality occurs when the repetition frequency exceeds 50H7, but in the case of the example, it is difficult to obtain good printing. Even at 150 Hz, good printing was possible without any dots or the like.

Embodiment 2 In FIG. 6, the basic configuration of the inkjet recording apparatus is almost the same as in Embodiment 1, but unlike Embodiment 1, the preliminary heating resistor 61 of the preliminary heating means 60 is a part of the induction electrode 51. The common electrode part 5 of the induction electrode 51 can be
An insulator 1 substantially opposite to 4 is formed in a band shape on the 14 side. Historically, in this embodiment, the structure for supplying electricity to the preliminary heating resistor 61 is such that, as shown in FIG. 7 and FIG. On the other hand, current-carrying electrodes 64 made of vapor-deposited metal such as copper or aluminum are formed on both ends of the spacer member 15, and the preliminary heating resistor 61 described in F is heated through the current-carrying electrodes 64. It is.

Note that it is not necessary to use a particularly resistive conductive layer as the induction electrode 51 in this embodiment, and a simple conductive layer may be used.

Therefore, according to the inkjet recording apparatus according to this embodiment, in addition to achieving the same functions and effects as in the first embodiment, in the case of the first embodiment, the induction electrode 51 and the preliminary heating resistor 61 are
Because it also serves as the induction electrode 51, it is necessary to set the heating operation timing of the preliminary heating resistor 61 in a pulsed manner at the time when it is not functioning as the induction electrode 51. Since there are no particular restrictions on controlling the heating operation timing of the heating resistor 61, for example, if a temperature sensor or the like is used to perform the second ON control, the ink temperature around the preliminary heating resistor 61 can be made uniform. This makes it easier to achieve this, and the ability to resupply ink to the ink ejection section 11a is accordingly stabilized.

Example 3 The basic configuration of the inkjet recording apparatus shown in FIG. 9 is substantially the same as that of Example 2, but the configuration of the flow path resistance adjusting section 20 of the ink chamber 11 differs from that of Example 2.

In this embodiment, in J3, the flow path resistance adjustment section 20 is composed of a tapered wall 25 formed by arranging a pair of insulating bases 13, 14 at an angle so as to narrow toward the ink discharge section 11a side. , ink discharge section 11a1. :Imoru ink room 1
The flow path resistance of the ink chamber 11 gradually decreases in the depth direction of the ink chamber 11.

Therefore, according to the inkjet recording apparatus according to this embodiment, in addition to achieving substantially the same functions and effects as in the second embodiment, the wall surface defining the ink ejection portion 11a is also arranged at an angle, so that the ink ejection portion 11a The flow path resistance in the ink reservoir does not increase rapidly compared to that in the ink reservoir leading to the ink discharge section 11a, and the resupply of ink 3 to the ink discharge section 11a can be made smoother.

[Effects of the Invention] As described above, according to the inkjet recording apparatus according to the present invention, the flow path resistance of the ink chamber -T to the ink 1 outlet part is reduced, and the inlet part of the ink discharge part is preheated. Since the preheating method is applied, even if ink with a relatively low viscosity Iα is used, in order to maintain good ink retention in the ink ejection portion, the ink will not be heated to the ink ejection portion. Ink resupply performance can be improved,
Accordingly, the printing speed can be increased accordingly.

Furthermore, according to the present invention, it is possible to prevent the preliminary heat energy from being unnecessarily transmitted to the ejecting ink located at the outlet portion of the ink ejecting section, so that the ejection of ink within the ink ejecting section is prevented. It becomes possible to ensure a large temperature contrast between the area and the non-ejection area, and erroneous ejection of ink can be effectively prevented accordingly.

Further, according to the inkjet recording apparatus according to the second aspect, since there is no need to independently provide a preliminary heat energy application part in the head body, the configuration of the recording head can be simplified accordingly.

Furthermore, according to the inkjet recording apparatus according to the third aspect, since the necessary minimum preheat energy 1= is applied to the ink located in the artificial part of the ink ejection part,
Compared to the type that continuously applies preliminary heat energy,
Thermal energy transferred to the ejecting ink located at the outlet of the ink ejecting part can be further reduced.
Accordingly, it is possible to easily ensure temperature contrast in the ejecting ink portion within the ink ejecting section.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a schematic configuration of an ink jet recording apparatus according to the present invention, FIG. 2 is a perspective view showing an ink ejection unit according to the present invention, and FIG. 3 is a perspective view showing a first embodiment of the recording apparatus.
4 is a sectional view taken along the line ■-■ in the figure, FIG. 4 is a view taken from the arrow direction in FIG. Embodiment 2 of the inkjet recording apparatus according to the invention is not shown, but FIG. 7 is an explanatory diagram corresponding to FIG. 3, FIG. 7th
9 is an explanatory view corresponding to FIG. 3 showing a third embodiment of the inkjet recording apparatus according to the present invention. [Explanation of symbols] 1... Head main body 2... Ink chamber 2a... Ink discharge section 3... Ink 4... Thermal energy application means 5... Recording sheet 6... Electrostatic field formation Means 7...Flow path resistance adjustment section 8...Preheating means Patent applicant Agent of Fuji Xerox Co., Ltd.
Patent Attorney Tomohiro Nakamura (2 others) Figure 7 Figure 1 Figure 8

Claims (1)

[Claims] 1) A head main body (1) having an ink ejection part (2a) in which ejection ink (3) is held on the outlet side of the ink chamber (2).
), a thermal energy applying means (4) for applying thermal energy according to image information to the ejection ink (3) held in the ink ejection part (2a), and In an inkjet recording apparatus equipped with an electrostatic field forming means (6) for applying an electrostatic field toward the recording sheet (5) on the ink (3), the ink chamber (2) includes an ink ejection section (2a). ) to the ink chamber (2), a flow path resistance adjustment section that reduces the resistance of the flow path (
7) is provided, and preheating is performed in which preheating energy is applied to a portion of the ink discharge portion (2a) that is located on the back side of the ink chamber (2) from the area to which thermal energy is applied by the thermal energy application means (4). An inkjet recording apparatus characterized by comprising means (8). 2) In the device according to claim 1, the electrostatic field forming means (6) has a resistive conductive layer made of a heating resistor on the head body (1) side, and this resistive conductive layer also serves as the preheating means (8). An inkjet recording device characterized by: 3) The inkjet recording apparatus according to claim 1, wherein the preheating means (8) applies preheating energy in a pulsed manner in synchronization with each ink ejection cycle.