JP3563883B2 - Ink jet head and substrate for ink jet head - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a substrate for ink jet head and the ink jet head.
[0002]
[Prior art]
An ink jet recording apparatus is a recording apparatus of a so-called non-impact recording method. That is, it has a characteristic that it can be recorded on various recording media at a high speed and has little noise during recording. Therefore, it has a recording mechanism such as a printer, a word processor, a facsimile, and a copying machine. Widely used as a device.
[0003]
As a typical method of the ink jet recording, there is a method in which a minute droplet is ejected from a minute ejection port by using an electrothermal transducer to perform recording on recording paper.
[0004]
An ink jet head used for such ink jet recording generally includes an ink ejector for forming droplets and a supply system for supplying ink to the ink ejector. For example, in an ink jet head using an electrothermal conversion element, an electrothermal conversion element is provided in a pressurized chamber, and heat energy is given to the recording liquid by applying an electric pulse serving as a recording signal thereto, and the recording liquid at that time is used. The bubble pressure at the time of bubbling of the recording liquid caused by the phase change, that is, at the time of boiling is used for discharging the recording liquid droplets.
[0005]
Inkjet recording is an excellent recording method as described above, but has a problem that the recorded image depends on the temperature of the inkjet head. For example, the ejection amount changes depending on the temperature of the head. Specifically, a phenomenon occurs in which the ejection amount increases when the environmental temperature is high. This problem has been known for a long time. Since the temperature of the head during printing causes a difference between the head temperature at the start of printing and the head temperature during printing, uneven printing density occurs due to the difference in the ejection amount. To solve this problem, a conventional solution is to provide a means for detecting the head temperature, for example, one or more diode sensors in the ink jet head, and refer to the information on the temperature received from the detection means to determine the head temperature. To a certain point or a method of controlling the temperature of the recording liquid in the vicinity of the electrothermal conversion element by giving a plurality of pulses with extremely small energy so that the recording liquid is not ejected immediately before one ejection of the recording liquid. Had been proposed.
[0006]
Such a technical method for temperature adjustment has been proposed on the assumption that the temperature of the ink jet head is uniform, in other words, the temperature near the temperature sensor and the temperature at the far side in the same head are almost equal. .
[0007]
[Problems to be solved by the invention]
However, in the case where ink is supplied from an ink tank on the back surface of the substrate as shown in FIG. 8, a plurality of rows of electrothermal conversion elements are thermally separated from each other depending on the ink supply port, Heat generated from the electrothermal transducers in one row is less likely to be transmitted to the other row. FIG. 9 is a plan view of the entire element substrate of a conventional inkjet head. The substrate 4 on which the electrothermal transducers 1 are arranged is usually made of Si having good thermal conductivity. However, as can be seen from FIG. Not transmitted to the department. That is, since the thermal conductivity from the portion A to the portion B is poor, a bias of heat is easily generated in the ink jet head.
[0008]
In the case of an ink jet head, electric energy by an applied pulse is converted into heat energy by an electrothermal conversion element. This thermal energy is not only converted into kinetic energy for discharging the ink droplets, but also radiated to the atmosphere or the recording liquid, or remains on the ink jet head. If the heat remaining on the inkjet head is left as it is, it will eventually be radiated to the atmosphere, but normal printing will be performed by continuously applying high-frequency electric pulses to the electrothermal transducer to eject ink droplets. The situation is different below. Since the relaxation time consumed until the remaining heat is radiated is longer than the ejection cycle, heat is stored on the inkjet head, and the inkjet head self-heats. The heat remaining on the ink jet head poses a problem for the following reasons.
[0009]
That is, first, as an overall problem of the ink jet head, when the head is heated, the discharge amount changes, and therefore, a difference occurs in the recording density between the time of starting printing and the time immediately before finishing printing. Second, as a local problem of the inkjet head, a recording signal applied to the electrothermal transducer, that is, an electric pulse, varies in the frequency and timing of ejection between different inkjet recording elements if normal recording is performed. The variation in the ejection frequency and the timing appears as uneven temperature distribution on the inkjet head due to the heat remaining on the inkjet head. If the temperature distribution on the ink jet head is uneven, the discharge amount and the discharge speed of the recording liquid fluctuate between the respective ink jet recording elements constituting the ink jet head. Causes a reduction in image quality.
[0010]
In the conventional example relating to the temperature adjustment described above, the first problem described above can be solved, but the second problem cannot be solved because temperature information about each nozzle row is required.
[0011]
Therefore, an object of the present invention is to solve the second problem described above, and disperses the heat after ejection in the ink jet head so that the entire head has a uniform temperature with less temperature unevenness, thereby reducing the density unevenness. An object of the present invention is to provide an ink jet head, a substrate for the head, an ink jet cartridge and an ink jet device which can obtain a small output.
[0012]
[Means for Solving the Problems]
The present inventor has conducted various studies in order to achieve the above object, and as a result, completed the present invention.
[0013]
According to a first aspect of the present invention, an ejection port for ejecting ink is provided, and a plurality of rows of a plurality of electrothermal transducers that generate thermal energy used for ejecting ink from the ejection port are provided in a row. What is claimed is: 1. An ink jet head comprising: a substrate having a substrate provided with an ink supply port corresponding to the length of the row between the plurality of rows, wherein portions of the substrate provided with the plurality of rows are provided. Are connected by a member having a thermal conductivity higher than the thermal conductivity of the substrate.
[0014]
The second invention relates to the inkjet head according to the first invention, wherein the member is made of a metal material .
[0015]
A third invention relates to the inkjet head according to the first or second invention, wherein the substrate is made of Si.
[0017]
The fourth invention relates to the ink jet head according to the first , second or third invention, wherein the member is a filter directly attached to the substrate so as to cover the entire supply port.
[0018]
A fifth invention relates to the inkjet head according to any one of the first to fourth inventions, wherein a plurality of the supply ports to which different inks are supplied are provided on the common substrate.
[0019]
According to a sixth aspect of the present invention, a plurality of rows of a plurality of electrothermal transducers for generating thermal energy used for ejecting ink are provided side by side, and a length corresponding to the length of the row is provided between the plurality of rows. A substrate for an ink jet head provided with an ink supply port, wherein the portions of the substrate provided with the plurality of rows are connected by a member having a thermal conductivity higher than the thermal conductivity of the substrate. And a substrate for an ink jet head.
[0020]
A seventh invention relates to the substrate for an inkjet head according to the sixth invention, wherein the member is made of a metal material .
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0028]
The material connecting the portions of the substrate provided with the electrothermal conversion element rows separated from each other by the ink supply port may be a material having a thermal conductivity substantially equal to or higher than the material constituting the substrate. is necessary. Such materials, generally the thermal conductivity (168W · ^{m -1} · ^K -1 Thermal conductivity of Si is 0 ℃ having the Si or the like used as a substrate, 800W · ^{m -1} · ^K -1 at room temperature ), And a material having a thermal conductivity of 800 W · m ⁻¹ · K ⁻¹ or more at room temperature, more preferably 1000 W · m ⁻¹ · K ⁻¹ or more at room temperature is used.
[0029]
As a specific method of connecting one or more portions of the substrate provided with the electrothermal conversion element rows separated from each other by the ink supply ports using the material having the above-described thermal conductivity, the temperature on the ink jet head Any form may be used as long as it has a function of dispersing and uniforming unevenness. For example, as shown in FIG. 1 and FIG. One or a plurality of bridge-like connecting portions 6 connecting the conversion element rows may be used.
[0030]
Further, the metal recording liquid filter 8 shown in FIGS. 4 and 5 and employed in a second embodiment described later may be used. It is preferable that such a metal recording liquid filter is directly attached to the substrate on which the electrothermal conversion elements are arranged, thereby more reliably achieving the object of the present invention. As the metal material to be used, the metal material having the above-described thermal conductivity can be mentioned as a preferable material. In addition, a material that is not corroded by ink or the like is preferable. Specifically, alloy materials such as gold and iridium / tungsten are preferable.
[0031]
FIG. 11 is a perspective view showing an ink jet cartridge in which an ink jet head of the present invention and an ink tank 101 provided with an ink chamber 102 for storing ink supplied to the head are integrated. The head and the ink tank may be detachably integrated, or may be fixed so as to be difficult to detach and integrate. A terminal 9 for supplying electric energy to the electrothermal conversion element is provided on an end of the substrate 4 and is electrically connected to a terminal on the device side.
[0032]
An example of an ink jet device in which the ink jet head of the present invention is detachably mounted will be described below. FIG. 12 is a partial cross-sectional perspective view for explaining a schematic configuration of the ink jet device of the present embodiment.
[0033]
In FIG. 12, reference numeral 200 denotes a carriage for detachably mounting the above-described inkjet head. The ink jet heads in this example are mounted in four types according to the type of ink color, and each head has a carriage 200 along with a yellow ink tank 201Y, a magenta ink tank 201M, a cyan ink tank 201C, and a black ink tank 201B. Mounted on top.
[0034]
The carriage 200 is supported by a guide shaft 202, and is reciprocally movable in the direction of arrow A on the guide shaft 202 by an endless belt 204 driven in a forward or reverse direction by a motor 203. Endless belt 204 is wound between pulleys 205 and 206.
[0035]
A recording sheet P as a recording medium is intermittently conveyed in a direction indicated by an arrow B perpendicular to the direction indicated by an arrow A. The recording paper P is supported by a pair of roller units 207 and 208 on the upstream side and a pair of roller units 209 and 210 on the downstream side, is applied with a constant tension, and is transported while ensuring flatness with respect to the head. Is done. The application of the driving force to each roller unit is performed by the driving unit 211, but the driving unit may be used to drive the roller unit.
[0036]
The carriage 200 stops at the home position as needed at the start of printing or during printing. In this position, a cap member 212 for capping the discharge port surface of each head is provided. The cap member 212 is forcibly sucked into the discharge port on the discharge port surface and clogged in the discharge port. Is connected to a suction recovery pump (not shown) for preventing the above.
[0037]
FIG. 13 is a block diagram of an entire apparatus for operating a recording apparatus which is an inkjet apparatus to which the inkjet head of the present invention is applied.
[0038]
The recording device receives print information from the host computer 300 as a control signal. The print information is temporarily stored in the input / output interface 301 inside the printing apparatus, and at the same time, is converted into data that can be processed in the printing apparatus, and is input to the CPU 302 also serving as a head drive signal supply unit.
[0039]
The CPU 302 processes data input to the CPU 302 using a peripheral unit such as the RAM 304 based on a control program stored in the ROM 303, and converts the data into print data (image data).
[0040]
Further, the CPU 302 generates drive data for driving a drive motor for moving the recording paper and the head in synchronization with the image data in order to record the image data at an appropriate position on the recording paper. The image data and the motor drive data are transmitted to the head 308 and the drive motor 306 via the head driver 307 and the motor driver 305, respectively, and are driven at controlled timing to form an image.
[0041]
Examples of the recording medium which can be applied to the above-described recording apparatus and to which a liquid such as ink is applied include various papers, OHP sheets, plastic materials used for compact discs and decorative plates, cloths, aluminum, copper, etc. Metal materials, leather materials such as cowhide, pigskin and artificial leather, wood materials such as wood and plywood, ceramic materials such as bamboo materials and tiles, and three-dimensional structures such as sponges.
[0042]
Further, the above-mentioned recording apparatus includes a printer apparatus for recording on various kinds of paper and OHP sheets, a recording apparatus for plastic for recording on a plastic material such as a compact disk, a recording apparatus for metal for recording on a metal plate, and leather. A recording device for leather that performs recording on wood, a recording device for wood that performs recording on wood, a recording device for ceramic that performs recording on ceramic materials, a recording device that performs recording on a three-dimensional network structure such as a sponge, or a fabric. It also includes a textile printing device that performs recording.
[0043]
Further, as a discharge liquid used in these ink jet devices, a liquid suitable for each recording medium and recording conditions may be used.
[0044]
Next, an example of an ink jet recording system that performs recording on a recording medium using the ink jet head of the present invention as a recording head will be described.
[0045]
FIG. 14 is a schematic diagram for explaining the configuration of an inkjet recording system using the inkjet head of the present invention described above. The inkjet head according to the present embodiment is a full-line type head in which a plurality of ejection ports are arranged at intervals of 360 dpi in a length corresponding to the recordable width of the recording medium P, and includes yellow (Y), magenta (M ), Cyan (C), and black (Bk) are fixedly supported in parallel with each other by a holder 402 at predetermined intervals in the X direction by a holder 402.
[0046]
A signal is supplied to each of these heads from a head driver 307 constituting a drive signal supply unit, and each head is driven based on this signal.
[0047]
To each head, four color inks of Y, M, C, and Bk are supplied as inks from ink containers 404a to 404d, respectively. Reference numeral 404e denotes a foaming liquid container in which the foaming liquid is stored, and the foaming liquid is supplied from the container to each head.
[0048]
Below each head, head caps 403a to 403d in which an ink absorbing member such as a sponge is disposed are provided. Maintenance can be performed.
[0049]
Reference numeral 406 denotes a transport belt which constitutes a transport unit for transporting various non-recording media as described above. The transport belt 406 is drawn around a predetermined path by various rollers, and is driven by a driving roller connected to a motor driver 305.
[0050]
In the ink jet recording system illustrated in the present embodiment, a pre-processing device 451 and a post-processing device 452 that perform various processes on a recording medium before and after recording are respectively arranged upstream and downstream of a recording medium transport path. Is provided.
[0051]
The contents of the pre-processing and post-processing differ depending on the type of recording medium on which recording is performed and the type of ink.For example, for recording media such as metals, plastics, ceramics, etc. By irradiating the surface with ozone and activating the surface, the adhesion of the ink can be improved. On a recording medium, such as plastic, which easily generates static electricity, dust easily adheres to the surface of the recording medium due to the static electricity, which may hinder good recording. By removing static electricity from the medium, dust can be removed from the recording medium. When a cloth is used as the recording medium, the cloth is selected from an alkaline substance, a water-soluble substance, a synthetic polymer, a water-soluble metal salt, urea, and thiourea from the viewpoint of preventing bleeding and improving the first-arrival rate. The process of applying the substance can be performed as a pre-process. The pre-processing is not limited to these, and may be a process of setting the temperature of the recording medium to a temperature suitable for recording.
[0052]
The post-processing is a fixing process that promotes the fixing of the ink to the recording medium to which the ink has been applied by heat treatment or ultraviolet irradiation, or a process that cleans the processing agent applied in the pre-processing and remaining after the final reaction. And so on.
[0053]
In the present embodiment, a full-line head has been described as a head. However, the present invention is not limited to this, and a small head as described above is conveyed in the direction of a recording medium to perform recording. Is also good.
[0054]
【Example】
Hereinafter, the present invention will be further described with reference to examples, but the present invention is not limited to these examples.
[0055]
Reference Example 1
Figure 1 is a fragmentary cross-sectional view of the vicinity of the center of the substrate of the ink jet head of the present embodiment, FIG. 2 is a plan view of the entire substrate. In the figure, 1 is an electrothermal conversion element, 2 is a discharge port, 3 is a nozzle orifice plate, 4 is a Si substrate, 5 is a supply port, and 6 is a connecting portion of the feature of the present invention. The space between 3 and 4 is filled with ink (recording liquid), and ink is supplied from the back side of the Si substrate.
[0056]
This reference example is a so-called side-star type in which the discharge ports are provided to face in parallel with the surface of the pressure source, and there is a substrate provided with a plurality of electrothermal conversion elements. There is a portion opened on the substrate to communicate with the ink tank, and a plurality of electrothermal conversion elements or piezoelectric elements 1 are provided on the substrate with the ink supply port 5 interposed therebetween. Connecting portion 6 material of the substrate in the present embodiment is the same as Si and a substrate provided with electrothermal converting element, the width of the connecting portion is 60 [mu] m, the interval of the connecting portion and the connecting portion are separated 100 [mu] m. If the width of the connecting portion is too large, it becomes difficult to supply the recording liquid.
[0057]
FIG. 3 is a graph comparing the temperature change when only one side row of the electrothermal transducers is continuously discharged using the inkjet head of this reference example on the discharge row side (solid line) and the non-discharge row side (dashed line). It was made. FIG. 10 is a graph of a temperature change when the same is performed for the conventional heads as shown in FIGS. 8 and 9. The two types of ink jet heads each have 256 nozzles of 360 dpi, are provided with an in-machine temperature sensor and an in-head temperature sensor, and perform appropriate temperature control of the head. The driving frequency of the head was 10.0 kHz.
[0058]
As is clear from the comparison between FIG. 3 and FIG. 10, the ink jet head of this reference example has excellent thermal characteristics, and the temperature on the non-ejection row side is close to the temperature on the ejection row side. That is, the temperature of the entire head is likely to be uniform.
[0059]
In addition, an experiment was performed using the conventional head and the head of the present reference example in which solid printing was performed using the nozzles in the other row immediately after solid printing was performed using the nozzles in one side row. While the change in the OD value at that time was 1.45 → 1.37, the head of the present reference example was considerably improved from 1.45 → 1.43.
[0060]
Example 1
FIG. 4 is a sectional view showing a main part near the center of the substrate, and FIG. 5 is a plan view of the entire substrate. In the figure, 1 is an electrothermal conversion element, 2 is a discharge port, 3 is a nozzle orifice plate, 4 is a Si substrate, 5 is a supply port, 7 is an ink tank, and 8 is a metal filter characteristic of the present invention. . The space between 3 and 4 is filled with ink (recording liquid), and ink is supplied from the back side of the Si substrate.
[0061]
This embodiment is a so-called side-star type in which the discharge ports are provided to face in parallel with the surface of the pressure source, and there is a substrate provided with a plurality of electrothermal conversion elements. There is a portion opened on the substrate to communicate with the ink tank, and a plurality of electrothermal conversion elements or piezoelectric elements 1 are provided on the substrate with the ink supply port 5 interposed therebetween. The metal filter 8 in this example was made of Au and had a mesh width of 12 μm.
[0062]
FIG. 6 is a graph comparing the temperature change when only one side of the electrothermal transducer is continuously discharged using the inkjet head of the present embodiment on the discharge line side (solid line) and the non-discharge line side (dashed line). It was made. This model also has a head of 256 nozzles of 360 dpi, is equipped with an in-machine temperature sensor and an in-head temperature sensor, and performs appropriate temperature control of the head. The driving frequency of the head was 10.0 kHz.
[0063]
As is clear from the comparison between FIG. 6 and FIG. 10, the inkjet head of the present invention has excellent thermal characteristics, and the temperature on the non-ejection row side takes a value close to the temperature on the ejection row side. That is, the temperature of the entire head is likely to be uniform.
[0064]
Oite to the present embodiment, it is possible to obtain the same effect as in Reference Example 1. Further, the metal filter of the present embodiment can also have a role of removing dust from the recording liquid.
[0065]
Example 2 and Reference Example 2
Embodiment 1 and Reference Example 1 described above are examples in which the electrothermal transducers are arranged in two rows, but the present invention is applicable even when three or more electrothermal transducers are provided. It is. As such an embodiment, FIGS. 7A and 7B show an example in which Y (yellow), M (magenta), C (cyan), and K (black) color inkjet heads are used. This shows a substrate provided on the same substrate and having supply ports communicating with ink tanks of the respective colors. FIG. 7A is an example ( Reference Example 2 ) in which a connection portion 6 is provided in an ink supply port corresponding to each color in the figure, and FIG. 7B is an example in which a metal filter 8 is provided. (Example 2 ).
[0066]
In these examples and reference examples , heat is dispersed and uniformized through the substrate between the ink supply ports 5 for each color.
[0067]
【The invention's effect】
As is apparent from the above description, according to the present invention, even with a small temperature sensor, the ink supply characteristics to all the electrothermal conversion elements are good, and the ink jet ink has excellent temperature characteristics with little local heat unevenness. A head, a substrate for the head, an ink jet cartridge, and an ink jet device can be provided, and an output with less print density unevenness can be obtained.
[0068]
Further, by using a metal filter, it is not necessary to provide a separate filter, and an effect of removing dust from the recording liquid can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part near the center of a substrate of an inkjet head according to a reference example 1 .
FIG. 2 is a plan view of the entire substrate of the inkjet head of FIG. 1;
FIG. 3 is a graph comparing the temperature change when only one nozzle row is ejected with the inkjet head of FIG. 1 on the ejection side and the non-ejection side.
FIG. 4 is a cross-sectional view of a main part near the center of the substrate of the inkjet head of the present invention (Example 1 ).
FIG. 5 is a plan view of the entire substrate of the inkjet head of FIG. 4;
FIG. 6 is a graph comparing the temperature change when only one nozzle row is ejected with the inkjet head of FIG. 4 on the ejection side and the non-ejection side.
FIG. 7 is a plan view of the entire substrate of the color inkjet head of the present invention (Example 2, Reference Example 2 ).
FIG. 8 is a cross-sectional view of a main part near the center of a substrate of a conventional inkjet head.
FIG. 9 is a plan view of the entire substrate of a conventional inkjet head (the head in FIG. 8).
FIG. 10 is a graph showing a comparison between a change in temperature when a nozzle row on one side is ejected by a conventional inkjet head (the head in FIG. 8) on the ejection side and a non-ejection side.
FIG. 11 is a perspective view showing an inkjet cartridge in which an inkjet head and an ink tank of the present invention are integrated.
FIG. 12 is a perspective view illustrating a main part of an ink jet device on which the ink jet cartridge is mounted.
FIG. 13 is a block diagram of an inkjet apparatus.
FIG. 14 is a perspective view illustrating a main part of the inkjet recording system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electrothermal conversion element 2 Discharge port 3 Nozzle orifice plate 4 Substrate 5 Supply port 6 Connection part 7 Ink tank 8 Metal filter 9 Electric energy supply terminal 101 Ink tank 102 Ink chamber 200 Carriage 201Y Yellow ink tank 201M Magenta ink tank 201C Cyan ink tank 201B Black ink tank 202 Guide shaft 203 Motor 204 Endless belt 205, 206 Pulley 207, 208, 209, 210 Roller unit 211 Drive unit 212 Cap member P Recording medium

Claims (7)

A substrate provided with discharge ports for discharging ink, and a plurality of rows of a plurality of electrothermal transducers for generating thermal energy used for discharging ink from the discharge ports, the plurality of rows being provided. An ink jet head having a substrate provided with ink supply ports corresponding to the length of the row between the rows of the plurality of rows, wherein the portions of the substrate provided with the plurality of rows are formed by heat of the substrate . An ink jet head connected by a member having a thermal conductivity higher than the conductivity. The ink jet head according to claim 1, wherein the member is made of a metal material . 3. The ink jet head according to claim 1, wherein the substrate is made of Si. The inkjet head according to claim 1 , wherein the member is a filter directly attached to the substrate so as to cover the entire supply port. The inkjet head according to any one of claims 1 to 4 , wherein a plurality of the supply ports to which different inks are supplied are provided in the common substrate. A plurality of rows composed of a plurality of electrothermal transducers that generate thermal energy used for discharging ink are provided side by side, and an ink supply port corresponding to the length of the row is provided between the plurality of rows. Is provided, wherein the portions of the substrate provided with the plurality of rows are connected by a member having a thermal conductivity greater than the thermal conductivity of the substrate. Substrate for inkjet heads. The substrate for an ink jet head according to claim 6, wherein the member is made of a metal material .

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