JP2002137396A - Ink-jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high performance ink-jet head capable of forming a desired image by accurately impacting ink droplets on a recording paper. SOLUTION: An ink-jet head comprising on the upper surface of a glaze substrate 2 a head substrate 1 having a large number of heat generating resistors 3 and a large number of individual power feeding wirings 4 disposed in the main scanning direction, and a nozzle member 8 having a large number of ink ejecting holes 9, with a predetermined interval provided therebetween, with the gap between the head substrate 1 and the nozzle member 8 filled with an ink 10, for executing a recording operation while circulating the ink such that the ink 10 is moved on the large number of the heat generating resistors 3 in the sub scanning direction, wherein the large number of individual power feeding wirings 4 are classified in a plurality of groups as well as the individual power feeding wirings 4 belonging to each group are disposed radially so that ink supplying holes 1a are provided in a blank part on the glaze substrate between the adjacent groups and outside the groups disposed on both ends in the main scanning direction, is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head for forming an image by depositing ink droplets on a recording paper in a predetermined pattern.

[0002]

2. Description of the Related Art Conventionally, an ink jet head has been used as a recording device for forming an image on recording paper.

[0003] The recording method of such an ink-jet head uses a method using thermal energy generated by a heating resistor, a method using deformation of a piezoelectric element, and a method using electromagnetic waves to discharge ink droplets toward recording paper. Of the thermal jet type, which uses the heat energy of the heating resistor, is easy to pattern the heating resistor, and has a small area. Since a heating resistor can generate relatively large heat energy, it is attracting attention as being suitable for high-density recording.

In such a thermal jet type ink jet head, for example, as shown in FIG. 3, a large number of heat generating resistors 23 and a large number of power supply wirings 24 and 25 are attached in a predetermined pattern on the upper surface of a glaze substrate 22. Nozzle member 26 having a large number of ink ejection holes 27 corresponding one-to-one to the heating resistors 23 on the head substrate 21
Are arranged with a predetermined interval therebetween, and a structure in which a gap between the head substrate 21 and the nozzle member 26 is filled with ink 28 is known, and a recording paper is placed on the outer surface of the nozzle member 26. Head substrate 2
The heating resistors 23 are individually selectively heated to generate air bubbles A in the ink 28 by the heat energy, and a part of the ink 28 is formed by the pressure of the air bubbles A into the ink ejection holes of the nozzle member 26. A predetermined image is recorded by discharging the ink from the outside 27 and attaching it to recording paper.

[0005] The ink 2 from an ink tank (not shown) is applied to the nozzle member 26 of the ink jet head.
An ink supply hole 29 for introducing the ink 8 into the gap between the head substrate 21 and the nozzle member 26 is provided. In the ink supply hole 29, an ink for guiding the ink 28 from the above-described ink tank to the ink supply hole 29 is provided. The supply pipe 30 was connected on the outer surface side of the nozzle member 26.

[0006]

However, in the above-mentioned conventional ink jet head, the ink 28 from the ink tank is supplied to the ink supply hole 2 of the nozzle member 26.
9 is introduced between the head substrate 21 and the nozzle member 26, and the outer surface of the nozzle member 26
An ink supply pipe 30 for guiding the ink 28 from the ink tank to the ink supply hole 29 is attached so as to protrude upward. Therefore, in order to prevent such protrusions from hindering the travel of the recording paper, it is necessary to keep the traveling position of the recording paper as far as possible from the nozzle member 26. Since the distance from the recording paper 27 to the recording paper becomes long, it becomes difficult to accurately land ink droplets discharged from the ink discharge holes 27 of the nozzle member 26 at a predetermined position on the recording paper, so that a desired print can be made. It had a disadvantage that it could not be formed.

When a recording operation is performed using the above-described conventional ink-jet head, for example, a driving cycle of 0.4 ms
When the heating resistor 23 is repeatedly heated in a short time in order to cope with high-speed recording of ec or less, a large amount of heat is accumulated inside the glaze substrate 22 disposed immediately below, and the temperature of the glaze substrate 22 becomes excessively high. High temperatures may occur. If the printing operation is continued in such a temperature state, the discharge amount of the ink 28 fluctuates, and the density of the image becomes uneven.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks, and has as its object to provide a high-performance ink jet head capable of forming a desired image by accurately landing ink droplets on recording paper. Is to provide.

[0009]

According to an ink jet head of the present invention, a large number of heating resistors arranged in the main scanning direction on the upper surface of a glaze substrate, one end of which is individually connected to the heating resistor, and the other end of which is connected to the heating resistor. A head substrate having a large number of individual power supply wirings derived in a direction away from the heating resistor, and a nozzle member having a large number of ink ejection holes corresponding to the heating resistor, with a predetermined space therebetween. An ink jet head which is arranged and filled with ink in a gap between the head substrate and the nozzle member, and performs a recording operation while circulating the ink such that the ink flows on a large number of heating resistors in the sub-scanning direction. Wherein a number of the individual power supply wirings are N (N is 2
The above-mentioned (natural number) individual power supply wirings are divided into a plurality of groups each having one unit, and the arrangement pitch of the N individual power supply wirings belonging to each group is larger at one end side than at the other end side. The ink is arranged radially from the other end side to the one end side, and the ink is applied to the head substrate-nozzle in a blank portion on the upper surface of the glaze substrate provided between adjacent groups and outside the groups located at both ends in the main scanning direction. An ink supply hole for introducing between the members is provided.

The ink jet head according to the present invention is characterized in that the opening areas of the ink supply holes are all equal, and the ink supply holes are arranged at regular intervals in the main scanning direction at least over the arrangement region of the heating resistors. It is assumed that.

According to the ink jet head of the present invention,
Since the ink from the ink tank or the like is introduced into the gap between the head substrate and the nozzle member from the lower surface side of the head substrate through an ink supply hole provided in the head substrate, the ink is applied to the outer surface of the nozzle member. There is no need to attach a protruding object such as a supply pipe, so that the running position of the recording paper can be made closer to the outer surface of the nozzle member to reduce the overall structure of the printer in which the ink jet head is incorporated and to reduce the size of the recording. The paper can be smoothly transported along the outer surface of the nozzle member. Therefore, the ink droplets ejected from the ink ejection holes of the nozzle member can be accurately landed on a predetermined position of the recording paper, and a desired image can be formed.

According to the ink jet head of the present invention, since the recording operation is performed while the ink between the head substrate and the nozzle member flows in the sub-scanning direction, the heat in the glaze substrate is efficiently generated by the flowing ink. Cools well. Therefore, even when the heating resistor is repeatedly heated in a short time to cope with high-speed printing, it is possible to maintain the temperature of the glaze substrate at a temperature suitable for the printing operation and keep the ink ejection amount substantially constant. It is possible to form a good image with little density unevenness on the recording paper.

Further, according to the ink jet head of the present invention, the opening areas of the ink supply holes formed in the glaze substrate are all equalized, and the ink supply holes are arranged at regular intervals over at least the arrangement region of the heating resistors. By arranging them in the scanning direction, it is possible to control the flow rate of the ink flowing over the large number of heating resistors to be substantially constant, and to cool the glaze substrate evenly in the main scanning direction.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of an inkjet head according to an embodiment of the present invention, and FIG. 2 is a plan view of a head substrate used in the inkjet head of FIG. 1. The inkjet head shown in FIG. 1 and a nozzle member 8, and a gap formed therebetween is filled with ink 10.

The head substrate 1 is based on a glaze substrate 2 and has a plurality of heating resistors 3, a large number of individual power supply wirings 4, a common power supply wiring 5, and a plurality of driver ICs on the upper surface thereof.
7 is attached.

The glaze substrate 2 comprises a ceramic substrate 2a made of alumina ceramics or the like, and a glaze layer 2b having an arc-shaped cross section adhered on the upper surface of the ceramic substrate 2a in a band shape in the main scanning direction. The resistor 3 is
Power supply wirings 4, 5 and the like are attached and formed from the upper surface of the glaze layer 2b to the upper surface of the ceramic substrate 2a.

The glaze substrate 2 functions as a supporting base material for supporting the heating resistor 3 and the power supply wirings 4 and 5, and the pattern of the heating resistor 3 and the power supply wirings 4 and 5 is arranged. An ink supply hole 1a, which will be described later, is formed in a blank portion that is not formed.

The glaze substrate 2 is obtained by first punching a ceramic green sheet formed of a ceramic material such as alumina, silica, magnesia or the like into a predetermined shape, and firing this at a high temperature to obtain a ceramic substrate 2a. Thereafter, a predetermined glass paste is partially applied to the upper surface of the ceramic substrate 2a by a conventionally known screen printing or the like, and is baked at a high temperature to form a glaze layer 2b.

On the upper surface of the glaze substrate 2, specifically, on the upper surface of the glaze layer 2b, for example, 2400 heating resistors 3 are linearly attached and arranged in the main scanning direction. The common power supply wiring 5 is commonly connected to one end, and one end of the individual power supply wiring 4 is individually connected to the other end.

The heating resistor 3 is, for example, 600 dpi.
(dot per inch) density, each of which is T
aN, TaSiO, TaSiNO, TiSiO, TiSi
Since it is made of an electric resistance material such as CO, NbSiO, etc., when power supply power is applied through the individual power supply wiring 4 and the common power supply wiring 5 and the like, Joule heat is generated and the ink 10
It acts to generate a predetermined heat energy necessary for generating bubbles A therein.

The individual power supply wiring 4 and the common power supply wiring 5 connected to the heating resistor 3 are formed of a metal material such as aluminum or copper. An operation of applying an external power supply to the heating resistor 3 based on the driving is performed.

The heating resistor 3, the individual power supply wirings 4, and the common power supply wirings 5 employ a conventionally known thin film forming technique, specifically, a sputtering method, a photolithography technique, an etching technique, or the like. It is formed by applying a resistance material or a metal material on the upper surface of the glaze substrate 2 in a predetermined thickness and a predetermined pattern.

Further, the above-mentioned large number of individual power supply wirings 4 are further N (N is a natural number of 2 or more) continuous in the main scanning direction.
Are divided into a plurality of groups each including the individual power supply wiring 4 as a unit, and each group is led out in a direction away from the heating resistor 3.

The number N of the individual power supply wirings 3 constituting each group is set to, for example, “64”, and the N individual power supply wirings 4 belonging to each group are arranged such that their arrangement bitch is closer to the other end. It is arranged radially from the other end to one end so that it becomes larger at one end (the heating resistor 3 side).

The lead-out portion of the individual power supply wiring 4 is provided with connection pads functioning as terminals for connecting the wiring 4 to an external electric circuit. It is arranged in the main scanning direction collectively for each group at a higher density.

In this embodiment, a flip-chip type driver IC 7 is used as an external electric circuit.
The connection pad is electrically connected to a terminal of the driver IC 7 via a brazing material such as solder. This driver IC
Numeral 7 is mounted on the upper surface of the glaze substrate 2 by face-down bonding in a one-to-one correspondence with the group of the individual power supply wirings 4, and controls the Joule heat generation of the heat generating resistor 3 based on external image data. I do.

As described above, the N individual power supply wirings 4 belonging to each group are radially arranged from the other end to the one end as described above, so that the upper surface of the glaze substrate 2 has Between the heating resistor 3 and the power supply wiring 4,
There are provided a plurality of blank portions where 5 and the like are not provided, and ink supply holes 1a are formed in these blank portions.

The ink supply hole 1a is for introducing the ink 10 from an ink tank (not shown) into the gap between the head substrate 1 and the nozzle member 8 from the lower surface side of the glaze substrate 2, and in this embodiment, Each is formed to have a substantially elliptical shape, and an ink supply pipe 11 for guiding the ink 10 between the head substrate 1 and the nozzle member 8 from an ink tank (not shown) is provided in the opening of the ink supply hole 1a. 1 are connected on the lower surface side.

The plurality of ink supply holes 1a have the same opening area and are arranged at equal intervals in the main scanning direction at least over the arrangement region of the heating resistors 3.

The ink supply hole 1a is formed by forming a substantially elliptical ink supply hole 1a in a blank portion of the glaze substrate 2 by employing a conventionally known laser processing or the like.

On the other hand, the nozzle member 8 is, for example, 10 μm to 100 μm between the nozzle member 8 and the upper surface of the head substrate 1.
The head substrate 1 is disposed substantially in parallel with a gap of m.

The nozzle member 8 has a plurality of ink ejection holes 9 corresponding to the heating resistors 3 in a one-to-one correspondence, and each of the ink ejection holes 9 is located directly above the corresponding heating resistor 3. It is located.

The ink ejection holes 9 of the nozzle member 8 are for ejecting ink droplets toward recording paper during the recording operation of the ink jet head, and have a density substantially equal to that of the heating resistor 3, for example, a dot of 600 dpi. They are arranged linearly in the main scanning direction at a high density.

The nozzle member 8 is formed by processing a photosensitive epoxy resin, a polyimide resin, molybdenum, or the like into a predetermined shape, or by combining the above materials. For example, when the nozzle member 8 is made of molybdenum, it is formed of molybdenum. The ingot is formed into a plate having a predetermined thickness by a conventionally known metal working method, and a plurality of ink discharge holes 9 having a diameter of 10 μm to 100 μm are formed in the obtained plate by a conventionally known laser processing. By mounting the obtained nozzle member 8 on the head substrate 1 via a spacer (not shown), the nozzle member 8 is fixed at a predetermined position on the head substrate 1.

As the ink 10 to be filled in the gap between the head substrate 1 and the nozzle member 8, for example, pigment type oil-based ink or water-based dye ink is used, and the viscosity is, for example, 0.3 mPa · s to 3 mPa · s. 0.0mPa · s (25 ° C)
It is adjusted to.

The ink 10 is supplied from an ink tank (not shown) between the head substrate 1 and the nozzle member 8 through an ink supply pipe 11 and an ink supply hole 1a. The head substrate 1 is connected via a discharge hole (not shown) opened over the arrangement region of the body 3.
The ink 10 is discharged from the space between the nozzle members 8 so that the ink 10 flows over the plurality of heating resistors 3 in the sub-scanning direction (a direction orthogonal to the arrangement of the heating resistors 3) during the printing operation. Then, the ink is circulated between the above-described ink tank and a pump (not shown).

The flow rate of the ink 10 is, for example, 5
It is maintained substantially constant at a flow rate of 0 μm / sec to 2000 μm / sec. When the bubble A is generated in the ink 10 by the heat energy of the heating resistor 3, the bubble A
A part of the ink 10 is turned into an ink droplet by the pressure caused by

In this case, the ink supply holes 1a provided in the blank portions of the head substrate 1 for supplying the ink 10 between the head substrate 1 and the nozzle member 8 have the same opening area as described above. And the heating resistor 3
Are arranged in the main scanning direction at equal intervals over the arrangement area of the ink, the flow rate of the ink 10 flowing on the heating resistor 3 is controlled to be substantially constant over the main scanning direction.

Thus, the ink jet head of the present embodiment described above, while causing the ink 10 between the head substrate 1 and the nozzle member 8 to flow in the sub-scanning direction, while transporting the recording paper along the outer surface of the nozzle member 8, The plurality of heating resistors 3 are selectively and individually heated in accordance with the driving of the driver IC 7, and the thermal energy generates bubbles A in the ink 10 on the heating resistors 3. A predetermined image is recorded on the recording paper by discharging a part of the ink 10 from the ink discharge hole 9 of the nozzle member 8 to the outside by pressure and attaching the ink to the recording paper.

In the ink jet head of this embodiment as described above, the ink 10 from the ink tank is
Since the ink is introduced into the gap between the head substrate 1 and the nozzle member 8 from the lower surface side of the head substrate 1 through the ink supply hole 1a provided in the head substrate 1, the ink supply pipe is provided on the outer surface of the nozzle member 8. It is not necessary to attach a protruding object such as the above, so that the running position of the recording paper can be made closer to the outer surface of the nozzle member 8 and the overall structure of the printer in which the inkjet head is incorporated can be reduced in size.
The recording paper can be smoothly transported along the outer surface of the nozzle member 8. Accordingly, ink droplets ejected from the ink ejection holes 9 of the nozzle member 8 are accurately landed on predetermined positions of the recording paper, and a desired image can be formed.

According to the above-described ink jet head of the present embodiment, the recording operation is performed while the ink 10 between the head substrate 1 and the nozzle member 8 flows in the sub-scanning direction. The heat is efficiently cooled by the flowing ink 10. Therefore, even when the heating resistor 3 is repeatedly heated in a short time to cope with high-speed printing, the temperature of the glaze substrate 2 is maintained at a temperature suitable for the printing operation, and the ejection amount of the ink 10 is kept substantially constant. This makes it possible to form a clear image on the recording paper.

Further, according to the above-described ink jet head of the present embodiment, the opening areas of the ink supply holes 1a formed in the glaze substrate 2 are all equal, and the ink supply holes 1a are By arranging in the main scanning direction at equal intervals over the arrangement area,
By controlling the flow rate of the ink 10 flowing over the large number of heating resistors 3 to be substantially constant, the glaze substrate 2 can be cooled uniformly in the main scanning direction.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made without departing from the spirit of the present invention.

For example, in the above-described embodiment, the ink supply hole 1a provided in the blank portion of the glaze substrate 2 has a circular shape, but may have an elliptical shape or a polygonal shape instead.

In the above-described embodiment, the terminal of the driver IC 7 is connected to the connection pad of the individual power supply wiring via a brazing material such as solder.
The terminal of the driver IC 7 may be connected to the connection pad via another connection member such as a bonding wire.

Further, in the above embodiment, the driver IC 7 is used as an external electric circuit, and the driver IC 7
Are connected to the connection pads. Alternatively, a wiring board such as a flexible printed wiring board may be used as an external electric circuit, and the connection terminals may be electrically connected to the connection pads.

Further, in the above-described embodiment, it is a matter of course that the heating resistor 3 and the power supply wirings 4 and 5 may be covered with a protective film made of silicon nitride or the like.

[0048]

According to the ink jet head of the present invention, the ink from the ink tank or the like is introduced into the gap between the head substrate and the nozzle member from the lower surface side of the head substrate through the ink supply hole provided in the head substrate. With this configuration, it is not necessary to attach a protrusion such as an ink supply pipe to the outer surface of the nozzle member, whereby the recording paper is moved closer to the outer surface of the nozzle member and the inkjet head is incorporated. The overall structure of the printer can be reduced in size, and the recording paper can be smoothly conveyed along the outer surface of the nozzle member. Therefore,
Ink droplets ejected from the ink ejection holes of the nozzle member are accurately landed at predetermined positions on the recording paper, and a desired image can be formed.

According to the ink jet head of the present invention, since the recording operation is performed while the ink between the head substrate and the nozzle member flows in the sub-scanning direction, the heat in the glaze substrate is efficiently changed by the flowing ink. Cools well. Therefore, even when the heating resistor is repeatedly heated in a short time to cope with high-speed printing, it is possible to maintain the temperature of the glaze substrate at a temperature suitable for the printing operation and keep the ink ejection amount substantially constant. As a result, a clear image can be formed on the recording paper.

Further, according to the ink jet head of the present invention, the opening areas of the ink supply holes formed in the glaze substrate are all equal, and the ink supply holes are arranged at regular intervals over at least the arrangement region of the heating resistors. By arranging them in the scanning direction, it is possible to control the flow rate of the ink flowing over the large number of heating resistors to be substantially constant, and to cool the glaze substrate evenly in the main scanning direction.

[Brief description of the drawings]

FIG. 1 is a sectional view of an inkjet head according to an embodiment of the present invention.

FIG. 2 is a plan view of a head substrate used in the inkjet head of FIG.

FIG. 3 is a cross-sectional view of a conventional inkjet head.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Head substrate, 1a ... Ink supply hole, 2 ...
-Glaze substrate, 3-Heating resistor, 4-Individual power supply wiring, 8-Nozzle member, 9-Ink ejection, 1
0 ... ink

Claims (2)

[Claims] 1. A plurality of heating resistors arranged in a main scanning direction on an upper surface of a glaze substrate, and one end is individually connected to the heating resistor, and the other end is led out in a direction away from the heating resistor. A head substrate having a large number of individual power supply wirings and a nozzle member having a large number of ink ejection holes corresponding to the heating resistors are arranged at a predetermined interval therebetween, and the head substrate-nozzle member is disposed between the head substrate and the nozzle member. An ink jet head that performs a recording operation while circulating ink so that the ink flows in a sub-scanning direction over a large number of heating resistors. , Divided into a plurality of groups each including N (N is a natural number of 2 or more) consecutive individual power supply lines in the main scanning direction, and N individual power supply lines belonging to each group. Are arranged radially from the other end side to the one end side so that the arrangement pitch is larger at one end side than at the other end side, and between the adjacent groups and outside the groups located at both ends in the main scanning direction. An ink supply hole for introducing the ink between the head substrate and the nozzle member is formed in a blank portion on the upper surface of the glaze substrate provided in the ink jet head. 2. An ink jet printer according to claim 1, wherein the opening areas of the ink supply holes are all equal, and the ink supply holes are arranged in the main scanning direction at regular intervals over at least the arrangement region of the heating resistors. The inkjet head according to the above.