JP3158374B2 - Ink jet print head and ink jet printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet print head and an ink-jet printer, and more particularly to an ink-jet print head and an ink-jet printer which generate ink by a heating element (hereinafter referred to as a heater) to discharge ink.

[0002]

2. Description of the Related Art Thermal ink jet print heads include:
There are two methods, an edge shooter type thermal inkjet printhead and a side shooter type thermal inkjet printhead, depending on the opening direction of the nozzle.

FIGS. 12 and 14 show the construction of an edge shooter type and side shooter type thermal ink jet print head, respectively. The basic principle of ink ejection is exactly the same in both systems. 12 and 14, a heater 3 is provided on a substrate 1 via an insulating film 2 such as SiO ₂ . A pair of Al electrodes 4 and 5 are provided on the heater 3 so as to face each other, and the upper surfaces of the heater 3 and the electrodes 4 and 5 are covered with three protective films 6, 7 and 8. An opening 8a is formed in the uppermost protective film 8 made of polyimide at a position where the electrodes 4 and 5 face each other, and an orifice plate 9 is provided above the protective film 8. . Then, ink 11 is supplied from a not-shown ink supply unit to a liquid chamber 10 formed in the orifice plate 9.

Here, in the edge shooter type head shown in FIG. 12, the liquid chamber 10 is opened in a direction parallel to the heater 3, and in the side shooter type head shown in FIG.
The liquid chamber 10 is opened in a direction perpendicular to the direction, and forms nozzles 12 and 13, respectively. In the side shooter head, the protective film has two layers, 6 and 8.

When a predetermined voltage pulse is applied to the heater 3 for a certain period of time in the edge-shooter type thermal ink jet print head configured as described above, a nuclear bubble 21 is formed on the surface of the heater 3 as shown in FIG. Occurs. The nuclear bubbles 21 coalesce as shown in (b) and become film bubbles 22, and as shown in (c), the film bubbles 22 grow by adiabatic expansion to become bubbles 23. Next, when the application of the voltage to the heater 3 is stopped, as shown in (d), heat is taken by the surrounding ink 11, and the bubble 23 contracts, and (e).
The bubble 23 disappears as shown in FIG. And (c),
The ink 11 is ejected from the nozzle 12 to the outside as ink droplets 11a by the ejection force of the film boiling phenomenon generated in the processes (d) and (e).

In the side shooter type thermal ink jet head shown in FIG. 14, the ink droplets 11a are discharged by the same operation as shown in FIG. In FIG. 15, a plurality of liquid chambers 10 are provided in parallel with the orifice plate 9, and the ink 11 is supplied from a common ink supply unit 24. The ink supply unit 24 is provided with a barrier 25 for partitioning each liquid chamber 10.

[0007]

However, each of the conventional ink jet print heads configured as described above is intended for monochromatic binary recording, and cannot realize density gradation. Further, since the heat of the heater 3 is almost directly transmitted to the ink 11 via the protective film 6 and the like, there is a problem that the ink 11 is scorched on the contact surface and the heating efficiency is deteriorated. Also, when mixing and discharging ink and a transparent solvent in order to realize density gradation,
Even during standby, the ink and the transparent solvent are in contact with each other and are in contact with the outside air, so that there is a problem that natural mixing and natural drying occur and print quality is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of such a situation, and it is possible to prevent the occurrence of scorching by an ink heater, to reduce the deterioration of heating efficiency, and to reduce the ink and transparent solvent during standby. It is an object of the present invention to provide an ink jet print head and an ink jet printer capable of preventing a natural mixture and a natural drying with the ink jet head and realizing a stable density gradation during operation.

[0009]

According to the first aspect of the present invention, there is provided an ink jet print head comprising: a heater provided on a substrate; and a barrier formed on the heater and serving as a partition.
5, a liquid chamber 10 as a transparent solvent chamber, and a liquid chamber 1
And an orifice plate 9 provided with an opening 27 for discharging a transparent solvent 28 in which the ink 11 is mixed, and the orifice plate 9 is made of a soft member so that the opening 27 can be opened and closed. The ink supply passage 26 communicating with the opening 27 is formed in the orifice plate 9.

In the ink jet print head according to the second aspect, the orifice plate 9 is provided with an ink supply path 26.
There the surfaces of the first plate 9a as a first flexible plate member which is formed, and each configured by disposing a second plate 9b as the second flexible member opening 27 is provided It is characterized by the following.

An ink jet print head according to a third aspect is characterized in that the opening 27 is formed in a straight line.

An ink jet print head according to a fourth aspect is characterized in that the opening 27 is formed in an H shape.

An ink jet print head according to a fifth aspect is characterized in that an electroosmotic membrane is used as means for feeding the ink 11 to the ink supply path 26 at a constant pressure.

In the ink jet printer according to the present invention, the head 31 is arranged so as to be movable in the axial direction of the drum 33 which rotates by rotating the drum 33 while winding the printing paper 32 as a printing material. It is characterized in that a feed screw 34 is provided as a driving member that is moved in conjunction with it.

[0015]

An ink jet printer according to a seventh aspect of the present invention is characterized in that a plurality of heads 31 are arranged in a line in the axial direction of a drum 33 which winds and rotates a print paper 32.

[0017]

In the ink jet print head according to any one of the first to fifth aspects, by supplying the determined amount of the ink 11 to the transparent solvent 28 filled in the liquid chamber 10 and mixing the same, an arbitrary density gradation can be obtained. Can be realized. At this time, the ink supply passage 26 is made of a soft material and
Is formed in an orifice plate 9 which covers the ink supply passage 26, and is provided with an opening 27 which can be opened and closed in communication with an ink supply passage 26, so that the opening 27 is closed during standby and the heater 3 provided on the substrate 1 during operation. Is heated to generate bubbles 23, and the ink 11 can be supplied by opening the opening 27 by the pressure at which the bubbles are generated. As a result, natural mixing and natural drying of the ink 11 and the transparent solvent 28 during standby can be prevented. Further, since the liquid heated by the heater 3 is the transparent solvent 28, deterioration of the heating efficiency due to scorching of the ink 11 can be reduced.

In the ink jet printer according to the sixth or seventh aspect , the feed and arrangement of the head 31 with respect to the drum 33 which rotates by rotating the print paper 32 can be changed into three types.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the ink jet print head and the ink jet printer of the present invention will be described below with reference to the drawings.

FIGS. 8 to 11 show examples of the configuration of an ink jet printer equipped with the ink jet print head 31 according to the present embodiment. FIG. 8 shows a configuration example of a drum rotation type. The printing paper 32 as a printing material is a drum 3
3 and is fixed at a predetermined position. A feed screw 34 is provided on the outer periphery of the drum 33 in parallel to the drum axis direction, and the head 31 is screwed to the feed screw 34. The rotation of the feed screw 34 causes the head 3
1 moves in the axial direction. The drum 33 is driven to rotate by a motor 38 via a pulley 35, a belt 36, and a pulley 37. Further, the feed screw 34
The drive of the head 38 and the rotation of the motor 38 are controlled by the drive control unit 39 based on the print data and the control signal 40.

In the above configuration, when the drum 33 rotates, ink is ejected from the head 31 in synchronization with the rotation, and an image is formed on the print paper 32. Drum 3
When one rotation of 3 is completed and printing of one line in the circumferential direction on the printing paper 32 is completed, the feed screw 34 rotates to move the head 31 by one pitch, and printing of the next line is performed. in this case,
There is also a method of simultaneously rotating the drum 33 and the feed screw 34 and gradually moving the head 31 while printing. In the case of a multi-nozzle head or a configuration in which the same location is printed several times, step feed is suitable. However, if the number of single nozzles or multi-nozzles is small, the drum 33 and the feed screw 34 are simultaneously operated in conjunction with each other. The spiral printing is performed while rotating.

FIG. 9 shows an example of a serial type configuration. In this case as well, the configuration is substantially the same as that of the drum rotating type shown in FIG. 8, except that the print paper 32 is not wound around the drum 33, and is provided by a paper pressure roller 41 provided in parallel in the axial direction. 33. In this case, when the head 31 moves and prints one line, the drum 33
Is rotated by one line to print the next line. The head 31 may move in the same direction or in the reciprocating direction.

FIG. 10 shows a line type configuration example. In this case, the serial type head 31 and the feed screw 3 shown in FIG.
Instead of 4, a line head 42 in which a number of heads 31 are arranged in a line is provided fixed in the axial direction.
In this configuration, printing of one line is performed simultaneously by the line head 42, and when printing is completed, the drum 33 is rotated by one line to print the next line. In this case, a method of printing all lines at once, dividing the data into a plurality of blocks, and alternately printing every other line can be considered.

FIG. 11 is a block diagram of a printing and control system. The signal 51 such as print data is sent to the signal processing / control circuit 5
2 and are sent to a head 54 via a driver 53 after being arranged in a printing order in a circuit 52. The order of printing differs depending on the configuration of the head and the printing unit, and also has a relationship with the order of inputting print data. The head 54 outputs a gradation signal and an ejection signal.

When the number of nozzles is very large in a multi-head, an IC is mounted on the head 54 to reduce the number of wires connected to the head 54. Further, a correction circuit 56 is connected to the signal processing / control circuit 52, and performs γ correction, color correction in the case of color, and variation correction of each head. Generally, predetermined correction data is stored in the correction circuit 56 in the form of a ROM map, and is taken out according to external conditions such as a nozzle number, a temperature, and an input signal.

The signal processing / control circuit 52 includes a CPU and a DSP.
Generally, the processing is performed by software, and the processed signal is sent to various control units 57. The various control units 57 control the driving of the motor for rotating the drum 33 and the feed screw 34, the synchronization, the cleaning of the head, the supply and discharge of the print paper 32, and the like. Needless to say, the signal 51 includes an operation unit signal and an external control signal other than the print data.

FIGS. 1 to 3 show the structure of an embodiment of the ink jet print head according to the present invention. In these figures, portions corresponding to those of the conventional example shown in FIG. 15 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. The feature of this embodiment is that the orifice plate 9 covers the liquid chamber 10.
The liquid chamber 1 is provided with an ink supply path 26 and an opening 27 communicating with the ink supply path 26 and opening to the outside and the liquid chamber 10.
The point is that the transparent solvent 28 is filled within zero.

As shown in FIG. 3, the orifice plate 9 is composed of three plates made of a soft member, and the second plate is provided on both sides of a first plate 9a as a first flexible plate. A second plate 9b as a flexible plate material is bonded. The first plate 9a is a copper plate having a thickness of about 3 μm to 10 μm, and a groove having a width of about 20 μm and a depth of about 3 μm to 10 μm formed by a precise pattern forming technique by photolithography and a thin film technique mainly composed of plating. The ink supply path 26 is formed in the shape of a circle. At one end of the ink supply path 26, a slit-like opening 27a having a length of about 20 μm in a direction perpendicular to the ink supply path 26 is formed by laser processing using an excimer laser or the like. Further, the other end of the ink supply path 26 is connected to an ink supply source (not shown).

The second plate 9b is formed by forming an opening 27b in a polyimide plate having a thickness of about 10 μm, as in the case of the first plate 9a. And the first
When the second plate 9b is bonded to both surfaces of the plate 9a, the openings 27a and 27b are aligned with each other.
The position is opposed to. In the case where the heads are multiplexed as shown in FIG. 2, the heads are manufactured integrally by providing an ink supply path 26 and an opening 27 corresponding to each head.

A known electroosmosis phenomenon is used as means for feeding the ink 11 at a constant pressure into the ink supply path 26. That is, although not shown, an electroosmotic film having both surfaces sandwiched by mesh electrodes is provided in the ink supply path 26, and a predetermined voltage pulse is applied between the mesh electrodes, so that a desired amount of ink 11 is supplied through the electroosmotic film. The liquid can be supplied from the opening 27 to the liquid chamber 10 side.

Next, the operation of this embodiment will be described. During standby, as shown in FIG. 1, the opening 27 of the orifice plate 9 is closed, and the ink 11 and the transparent solvent 2 are closed.
8 is completely separated and sealed to prevent natural mixing and natural drying. During operation, as shown in FIG. 4, the transparent solvent 28 is heated by the heater 3 so that nuclear bubbles are generated on the surface of the heater 3, and the nuclear bubbles combine to form film bubbles. The opening 27 of the orifice 9 is pushed up by the pressure of the bubble 29 generated when the film bubble adiabatically expands, and at the same time, the ink 11 quantified so as to obtain a desired density oozes out from the opening 27. At this time,
The hardness of the orifice plate 9 is such that the opening 27 is opened by the pressure of the bubble 29.

Further, as shown in FIG. 5, a bubble 29 grows, and the ink 11 oozing into the opening 27 and the transparent solvent 28 are mixed. Next, when the heating by the heater 3 is stopped,
When the heat is absorbed by the surrounding transparent solvent 28 , the bubbles 29 shrink and disappear, and the ink 1 mixed with the transparent solvent 28 is removed.
1 is discharged from the opening 27 as a droplet 11a. At the same time, the orifice plate 9 returns to the original state, the transparent solvent 28 is refilled and filled, and returns to the standby state shown in FIG.
Printing is performed by repeating the above operation. Note that water, alcohol, and the like are used as the transparent solvent.

According to the present embodiment, the natural mixing and natural drying of the ink 11 and the transparent solvent 28 can be prevented by closing the opening 27 of the orifice plate 9 during standby. Further, during operation, the opening 27 is opened by the bubble generating force, and at the same time, the determined amount of the ink 11 is mixed into the transparent solvent 28 and the mixed liquid is discharged from the opening 27, whereby a stable density gradation can be realized. . Further, since the liquid to be heated is the transparent solvent 28, deterioration of the heating efficiency due to scorching of the ink 11 can be reduced.

In the above embodiment, the case where the opening 27 provided in the orifice plate 9 is perpendicular to the longitudinal direction of the head has been described. However, as shown in FIG. Alternatively, they may be parallel. In this case, the ink supply passages 26 are at right angles to the longitudinal direction, and are connected to the common ink supply passages 30, respectively.

Further, in each of the above embodiments, the case where the shape of the opening 27 is linear has been described, but it may be H-shaped as shown in FIG.

The material of the orifice plate 9, the dimensions of each part, and the manufacturing method described in each of the above embodiments are merely examples, and are not limited thereto.

[0037]

As described above, according to the ink jet print head and the ink jet printer of the present invention, the orifice plate covering the transparent solvent chamber is formed of a soft member, and the orifice plate is provided with the ink supply path and the bubble generation pressure. The opening can be closed during standby to prevent spontaneous mixing and drying of the ink and the transparent solvent during standby. By mixing with a solvent and discharging from the opening, a stable density gradation can be realized. Further, since the liquid to be heated is a transparent solvent, it is possible to reduce the deterioration of the heating efficiency due to the scorching of the ink.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a configuration of an embodiment of an ink jet print head of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is an exploded perspective view showing a configuration of the orifice plate of FIG. 1;

FIG. 4 is a longitudinal sectional view for explaining a first step of the operation of the embodiment.

FIG. 5 is a longitudinal sectional view for explaining a second step of the operation of the present embodiment.

FIG. 6 is a plan view showing the configuration of another embodiment of the present invention.

FIG. 7 is a plan view showing a configuration of another embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a configuration of an example of a rotary drum type inkjet printer to which the present invention is applied.

FIG. 9 is an explanatory diagram illustrating a configuration of an example of a serial type inkjet printer to which the present invention is applied.

FIG. 10 is an explanatory diagram illustrating a configuration of an example of a line-type inkjet printer to which the present invention is applied.

FIG. 11 is a block diagram illustrating a configuration of an example of a signal processing and control system of the inkjet printer.

FIG. 12 is a longitudinal sectional view showing a configuration of an example of a conventional edge shooter type ink jet print head.

FIG. 13 is a diagram illustrating the operation of the inkjet print head shown in FIG.

FIG. 14 is a longitudinal sectional view showing a configuration of an example of a conventional side shooter type ink jet print head.

FIG. 15 is an operation explanatory view of the ink jet print head shown in FIG.

[Explanation of symbols]

 Reference Signs List 1 substrate 3 heater (heating element) 9 orifice plate 9a first plate (first flexible plate) 9b second plate (second flexible plate) 10 liquid chamber (transparent solvent chamber) 11 ink 25 Barrier (partition wall) 26 Ink supply path 27 Opening 28 Transparent solvent 31 Head 32 Print paper (substrate to be printed) 33 Drum 34 Feed screw (drive member) 38 Motor (drive member)

Claims (7)

(57) [Claims] 1. A heating element provided on a substrate; a transparent solvent chamber formed on the heating element and partitioned by a partition; and a transparent solvent in which the transparent solvent chamber covers the transparent solvent chamber and is mixed with ink. And an orifice plate provided with an opening to be provided, wherein the orifice plate is formed of a soft member, the opening is openable and closable, and the ink supply path communicating with the opening is formed in the orifice plate. Characteristic inkjet print head. 2. The orifice plate is formed by arranging a second flexible plate having the openings on both surfaces of a first flexible plate on which the ink supply passage is formed. The ink jet print head according to claim 1, wherein: 3. The ink jet print head according to claim 1, wherein said opening is formed in a straight line. 4. The ink jet print head according to claim 1, wherein said opening is formed in an H shape. 5. The ink jet print head according to claim 1, wherein an electroosmotic membrane is used as a means for feeding the ink to the ink supply path at a constant pressure. 6. An ink jet printer according to claim 1, wherein said ink jet printer is movable in the axial direction of a drum which rotates while rotating a printing medium.
With arranging the collector head, the ink jet printer, characterized in that the head provided with a drive member for moving in conjunction with the rotation of the drum. 7. The ink jet printer according to claim 1 , wherein a plurality of ink jets are wound in the axial direction of the drum that winds and rotates the substrate.
7. The ink jet printer according to claim 6, wherein the print heads are arranged in a line.