JPH0781054A - Ink jet head - Google Patents

Abstract

PURPOSE:To obtain a stable dot reduced in irregularity by partitioning the nozzle communicating with an ink tank into a control nozzle and an emitting nozzle by a heat insulating material and integrating the substrates of both nozzles to process both nozzles into the same shape and fixing a heating element to the inner periphery of the control nozzle. CONSTITUTION:Conductive layers 14 are formed on both surfaces of a control nozzle substrate 10 and an emitting nozzle substrate 11 is bonded to the single surface of the substrate 10 through a heat insulating material 8. Next, V-grooves constituting nozzle orifices are formed in the end surfaces of the substrates 10,11 and a heating element 4 is formed in the V-groove of the control nozzle substrate 10. Subsequently, the V-grooves of both substrates are abutted to be bonded and the conductive layer 14 exposed to the surface of the substrate 10 is removed so as to leave a wiring pattern 15. When the heating element 4 is operated by supplying a current across the conductive layers and the wiring pattern 15 to generate heat, solid ink 9s is melted at the contact surface with the heating element 4 to be extruded to an emitting nozzle 3 and the molten ink 9r in the emitting nozzle 3 is emitted. The solid ink 9s advancing into the emitting nozzle 3 becomes the molten ink 9r by the heat of the substrate 11 and this molten ink 9r is emitted by next emitting operation.

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 of an apparatus for ejecting ink for printing or image recording. More specifically, the present invention relates to an improvement of an inkjet head using a heat-meltable ink (oil-based ink which is also generally called solid ink).

[0002]

2. Description of the Related Art The applicant of the present invention has proposed a multi-nozzle recording method using a hot-melt ink as Japanese Patent Application No. 5-131008. As shown in FIG. 1, this ink jetting method includes a shared ink tank 1 that constantly melts and stores the hot-melt ink, and a pressurizing unit 2 that pressurizes the molten ink 9r in the shared ink tank 1 in the ejection direction. Shared ink tank 1
A plurality of discharge nozzles 3 that communicate with each other and always store the ink in a molten state, and discharge the ink only when a pressure is applied; and an ink tank 1 and a discharge nozzle 3 that have individually heat-controllable heating elements 4. And a control nozzle 5 that solidifies and stores the molten ink 9r supplied from the shared ink tank 1 inside the control nozzle 5 and is selected by the individual temperature control of the heating element 4 of the control nozzle 5. The solid ink 9s is partially re-melted and the solid ink 9s in the control nozzle 5 selected by driving the pressurizing means 2 is pushed out into the ejection nozzle 3 to eject the molten ink 9r in the ejection nozzle. ing.

Here, the control nozzle 5 is installed between the shared ink tank 1 and the discharge nozzle 3 which are constantly heated through a heat insulating material 7 so as to make the ink easily solidify, and is thermally insulated from them. And also the heat sink 1
Two are connected. Further, in this ink jet head, the heating element 4 is provided on the inner peripheral surface of the control nozzle 5, and only the surface of the solid ink 9s that is in contact with the heating element 4 is melted by the heat generation of the heating element 4 and remains as the ink mass. It is adapted to be pushed into the discharge nozzle 3. The pressurizing means 2 is not particularly limited, but a known applying means such as a vibrating means using a resonance action such as a conventional general piezoelectric element, a diaphragm or a tuning fork, a pressure applying means using a centrifugal force, and the like. Pressure means are used.

[0004]

However, this ink jet head has complicated processing steps because it is formed by joining the control nozzle 5 and the discharge nozzle 3 after processing them. Further, it is difficult to accurately align and bond the respective hole positions of the control nozzle 5 and the discharge nozzle 3, and the hole positions are likely to shift during manufacturing. The ejection nozzle 3 is a hole having the same rectangular cross-section as the control nozzle 5 and a rectangular pyramid shape narrowing toward the ejection port 3a at the tip, but the ejection nozzle used for the inkjet head has a very small diameter of about 50 μm. Since it is a hole, it is difficult to perform the above-mentioned hole processing accurately, and the hole shape tends to vary. Therefore, the shape of each ejection nozzle is different, or the hole positions of the ejection nozzles / control nozzles are displaced, which causes variations in the amount of ejected ink or a state where ink is not ejected, resulting in problems such as missing dots. It is an object of the present invention to provide an inkjet head that can obtain stable dots with little dot variation and is excellent in productivity.

[0005]

In order to achieve such an object, the present invention relates to an ink jet head in an apparatus for ejecting a melted heat-melting ink to print or record an image, and an ink which communicates with a common ink tank 1 respectively. Between the shared ink tank 1 and the discharge nozzle 3 having a plurality of discharge nozzles 3 for always storing the ink in a molten state and discharging it only when pressure is applied, and a heating element 4 capable of individually controlling the temperature. And a control nozzle 5 that solidifies and stores the melted ink 9r that is arranged and supplied from the shared ink tank 1. The discharge nozzle 3 and the control nozzle 5 have the same cross-sectional shape, and the shared ink tank 1 extends from the discharge port 3a. A straight nozzle communicating with each other was formed.

[0006]

The control nozzle 5 and the ejection nozzle 3 have the same cross-sectional shape, and form a straight nozzle that communicates from the shared ink tank 1 to the ejection nozzle tip 3a. Therefore, by laminating the base material layer 10, the heat insulating layer 8, and the base material layer 11 that form the control nozzle 5 and the discharge nozzle 3 and cutting the end face (nozzle portion), both can be formed in one step, A nozzle can be created by abutting the formed cutting surfaces. The action of the nozzle is the same as that of the conventional one, and by heating the heating element 4 of the nozzle for ejecting ink and operating the pressurizing means 2, the ejection nozzle 3
The molten ink 9r is ejected from the tip 3a of the. Incidentally, since the ejection nozzle 3 which has conventionally been tapered has a straight shape in the present invention, the nozzle hole from the shared ink tank 1 to the ejection nozzle 3 is thinner than the conventional one, and a larger pressure is required for ejecting ink. Becomes However, since the basic operation of discharging is the same as the conventional one, the same operation as the conventional one can be performed if the pressurizing means 2 generates a larger pressure than the conventional one.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described in detail below with reference to the embodiments shown in the drawings. The inkjet head of the present invention will be described with reference to FIGS. This ink jet head includes a shared ink tank 1 that constantly melts and stores a heat-meltable ink, a pressurizing unit 2 that pressurizes the melted ink 9r in the shared ink tank 1 in an ejection direction, and a shared ink tank 1. Between the shared ink tank 1 and the discharge nozzle 3, which has a plurality of discharge nozzles 3 that always store the communicating ink in a molten state and discharges only when pressure is applied, and a heating element 4 that can individually control the temperature. And the control nozzle 5 which solidifies the molten ink 9r supplied from the shared ink tank 1 and stores the lump 9s.

The melted ink 9r stored in the shared ink tank 1 is heated by a heating element 6 (which is attached to the surface of the shared ink tank 1 that comes into contact with the melted ink 9r, for example, the inner surface of the pressing means 2 as shown in FIG. It is always heated to a constant temperature by a surface heater, etc. and maintains a molten state. Of course, shared ink tank 1
The heating of the ink in the inside and the discharge nozzle 3 is not limited to the above method, and a heater may be arranged on the inner surface of the discharge nozzle 3 or the inner surface of the shared ink tank 1 itself, or a heater may be arranged inside the nozzle or the tank. May be.

Further, in order to make the solidification of the ink in the control nozzle 5 easy, the conductive ink layer 14 is formed on one surface of the control nozzle substrate 10 provided with the control nozzle 5, and the shared ink is constantly heated. The heat insulating material 8 is interposed between the discharge nozzle substrate 11 provided with the tank 1 and the discharge nozzle 3 and the conductive layer 14, and the heat insulating material 8 is interposed between the shared ink tank 1 and the control nozzle substrate 10. Therefore, the space between them is thermally blocked and the heat dissipation plate 12 is directly connected to the control nozzle substrate 10. Therefore, almost no heat is transferred to the ink in the control nozzle 5 from other than the heating element 4. Therefore, when the heating element 4 is not heated, the ink is solid ink 9
s.

A linear heating element 13 is provided around the discharge port 3a of the discharge nozzle 3 so as to sew between the discharge nozzles 3. The heating element 13 is constantly energized and holds the ink stored in the ejection nozzle 3 in a molten state. The discharge nozzle substrate 11 on which the discharge nozzles 3 are provided is preferably made of a material having good thermal conductivity, such as ceramics. Since the heating element 13 is provided to heat the discharge nozzle 3, the arrangement position is not limited to the position around the discharge port 3a.

The heating element 4 of the control nozzle 5 is formed on the entire inner peripheral surface of the nozzle, and the shared ink tank 1 side is connected to the wiring pattern 15 and the ejection side is connected to the conductive layer 14. Therefore, the heating element 4 generates heat when electricity is applied between the conductive layer 14 and the pattern 15. Only the surface of the solid ink 9s in contact with the heating element 4 is melted by the heat generation of the heating element 4 and is extruded into the ejection nozzle 3 as the solid ink 9s, and the molten ink 9r in the ejection nozzle 3 is ejected.
(Piston action) The portion of the solid ink 9s that has advanced into the ejection nozzle 3 by ejection receives the heat from the substrate 11 and changes to the molten ink 9r, so the next ejection operation is performed in the same manner as above.

In the above structure, the hole shape of the discharge nozzle 3 and the control nozzle 5 is rectangular so that the thin film of the heating element 4 can be easily formed uniformly on the inner surface by a thin film forming technique such as sputtering. Of course, a circular or elliptical hole may be used, but in the present invention, the ejection nozzle 3 and the control nozzle 5 have the same hole shape, and a straight nozzle communicating from the shared ink tank 1 to the ejection port 3a is formed. In the embodiment, since the heating element 4 is provided only on the inner peripheral surface of the control nozzle 5, the heating element 4 is thinner than the discharge nozzle by the amount of the heating element 4, but the nozzle shape at the time of processing is completely straight. ing.

An example of the method of forming this nozzle is shown in FIG. A material suitable for forming a nozzle, for example, a control nozzle substrate 10 made of ceramic is formed with conductive layers 14 such as Cu on both surfaces (), and a discharge nozzle substrate 11 is bonded to one surface via a heat insulating material 8 such as glass ( ). If glass is used as the heat insulating material 8, it can be integrated by heat bonding.
Next, V-grooves forming nozzle holes are formed in the end faces of the substrate 10 with the conductive layer, the heat insulating material 8 and the substrate 11 (), and the heating element 4 is vapor-deposited on the portion of the control nozzle substrate 10 on the surface including the V-grooves. And the like (). (Other portions may be masked and vapor-deposited) Then, the heating element 4 in the V groove portion
The end face on which the nozzle is formed is polished while leaving (2), and the nozzle processed in this way is butt-joined by aligning the V groove. Next, the conductive layer 14 exposed on the surface is removed except for the wiring pattern 15 ().

Regarding the formation of the heating element 4, there is no functional problem even if it is provided in the entire V groove without masking as described above.
When the heating element 4 is heated, since electricity is applied between the conductive layer 14 and the wiring pattern 15, only the heating element 4 in the control nozzle 5 generates heat, so there is no functional problem. That is,
In this case, the heating element in this portion is heated by the discharge nozzle substrate 11 which is constantly heated. However, since the heating element 4 is in the form of a thin film, heat is not transferred so much to the heating element 4 in the control nozzle portion, and the control nozzle 5 The ink inside is the heating element 4
The solid ink is 9 s unless it is energized. The size of the solid ink 9s is not limited to the size shown in the figure, as long as it can function as a piston, even if a part of the solid ink 9s on the ejection nozzle 3 side becomes the melted ink 9r, it does not affect the operation.

[0015]

MODIFICATION The above embodiment is one example of the preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, although the hole shape of the control nozzle 5 and the discharge nozzle 3 is rectangular in this embodiment, the shape is not particularly limited to this, and another shape such as a triangle or a circle may be used.

[0016]

As described above, according to the present invention, since the control nozzle 5 and the discharge nozzle 3 are formed by the same groove processing, there is no deviation between the hole positions of the two, and the shared ink tank 1 to the discharge port 3a. Since they have the same shape, they can be processed in one process, and the hole diameter of each nozzle can be made uniform. That is, it is possible to easily manufacture a stable dot-shaped inkjet head with little variation in dots.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a conventional example of an inkjet head, (A) showing a state before ejection and (B) showing a state during ejection.

FIG. 2 is a sectional view showing an embodiment of the inkjet head of the present invention.

FIG. 3 is a perspective view of FIG. 2 without ink.

FIG. 4 is an explanatory diagram of a nozzle processing step of the inkjet head of the present invention.

[Explanation of symbols]

 1 Shared Ink Tank 2 Pressurizing Means 3 Ejection Nozzle 4 Heating Element 5 Control Nozzle 6 Heating Element 7, 8 Heat Insulating Material 9r Molten Ink 9s Solid Ink 10 Control Nozzle Substrate 11 Ejection Nozzle Substrate 12 Heat Sink 13 Heating Element 14 Conductive Layer 15 Wiring pattern

Claims (1)

[Claims] 1. A device for printing by ejecting heat-meltable ink from a nozzle, wherein a nozzle communicating with the ink tank is divided into a control nozzle and a discharge nozzle, and a base material of both nozzles is used. An inkjet head with both nozzles processed into the same shape and a heating element fixed to the inner circumference of the control nozzle.