JPH0924612A - Inkjet head - Google Patents

Abstract

(57) [Abstract] [Purpose] Smooth ink supply to multiple ejection ports and prevent adverse effects between each ejection port during ink ejection, resulting in a uniform ink ejection amount and uniform image. It is possible to record and also to omit the ejection recovery device. [Structure] An ink supply port (8) is formed at each position on the opposite side of the ejection energy generators (3, 17) sandwiching the ejection energy generators (3, 17). A second liquid chamber (15) which also serves as an individual liquid passage having an ink supply port and an ejection port (7) is formed for each generator.

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 recording by discharging ink from a discharge port onto a recording material.

[0002]

2. Description of the Related Art A recording device having a function of a printer, a copying machine, a facsimile or the like, or a recording device used as an output device such as a composite electronic device including a computer, a word processor or the like, a workstation, etc. Image (including characters etc.) on the recording material (recording medium) such as paper or plastic thin plate based on
Is configured to be recorded. The recording apparatus can be classified into an ink jet type, a wire dot type, a thermal type, a laser beam type and the like according to a recording method.

In a serial type recording apparatus for recording while performing main scanning in a direction intersecting with a recording material conveying direction (sub-scanning direction), after the recording material is set at a predetermined recording position, the recording material is set on the recording material. The entire recording material is recorded by combining the recording operation by the recording means moving along with the conveying operation of feeding the recording material in the direction intersecting the moving direction of the recording means.

On the other hand, in a line type recording apparatus which records a recording material only in a sub-scanning direction in which the recording material is fed in the conveying direction, the recording material is set at a predetermined recording position and the recording for one line is continuously performed. A predetermined amount of paper feed (pitch feed) is performed while performing the recording, and an image is recorded on the entire recording material.

Among the above recording apparatuses, an ink jet type recording apparatus (ink jet recording apparatus) ejects ink from an ink jet head (recording means) onto a recording material to perform recording, so that the recording means can be made compact. Easy, high-definition images can be recorded at high speed, and can be recorded on plain paper without requiring special processing.
It has advantages such as low running cost, less noise due to the non-impact method, and easy recording of color images using multicolor inks. Above all, a line type using a full multi-type recording means in which a large number of discharge ports are arranged in the paper width direction can further increase the recording speed.

In particular, an ink jet head for ejecting ink by utilizing thermal energy is an electrothermal converter formed on a substrate, an electrode, a liquid path through a semiconductor manufacturing process such as etching, vapor deposition and sputtering. By forming the wall, the top plate, etc., it is possible to easily manufacture a device having a high-density liquid passage arrangement (ejection opening arrangement), and it is possible to further reduce the size. On the other hand, there are various requirements for the material of the recording material, and in recent years, in addition to the ordinary recording material such as paper and resin thin plate (OHP, etc.), thin paper and processed paper (with bunch holes for filing) It has become necessary to use paper, perforated paper, paper of any shape, etc.).

An ink jet head using a liquid jet recording method for forming flying droplets by utilizing thermal energy generally has a plurality of ejection openings for ejecting ink, a liquid passage communicating with each ejection opening, and each liquid passage. It is provided with an electric-energy converter having therein a portion for causing the ink ejection energy to act on the ink, and an electrode connected to each electric-energy converter.

Among the ink jet heads having such a structure, the ink jet heads disclosed in, for example, Japanese Patent Laid-Open Nos. 55-128467 and 59-194866 disclose thermal energy for ejection on the substrate surface. A heat generating resistor that generates heat, an electrode that supplies an electric signal to the heat generating resistor, and a protective layer that protects the heat generating resistor and the electrode from ink are laminated in a thin film forming technique or the like, and is formed on this substrate. A liquid path and a discharge port corresponding to each heating resistor are formed.

The ink jet head having such a structure is provided with wirings for selectively ejecting segments and a common electrode portion for current distribution. Further, the inkjet head has a structure in which a through hole is formed in a Si wafer forming a substrate and ink is supplied to the ejection port through the through hole. Wiring and resistors are arranged on both sides of the through hole of the substrate.

[0010]

FIG. 8 is a schematic vertical sectional view showing a structural example of a conventional inkjet head, and FIG. 9 is a schematic vertical sectional view showing another structural example of a conventional inkjet head. . In FIGS. 8 and 9, 1 is a substrate, 3 is an electric-energy converter formed on the substrate 1, 4 is wiring, 7 is a discharge port, and 8 is formed by penetrating the substrate 1 or the top plate 19. Hole (ink supply port), 10 is electricity-
This is bonding for electrically connecting to a drive circuit for driving the energy converter 3.

In FIGS. 8 and 9, 11 is a flying droplet of ink ejected from the ejection port 7, 12 is a recording material such as recording paper, and 13 is for applying ejection energy to the ink in the ejection port 7. Bubble generated in the above, 17 is the bubble 13
Is a heater of a heating resistor formed in a part of the electric-energy conversion body 3 for generating.

In the head structures shown in FIGS. 8 and 9, the ink ejection direction is perpendicular to the surface on which the wiring is formed, and therefore the mechanical strength of the head does not decrease even if the number of ejection ports is increased. , It is not necessary to change the wiring rule, but if the distance between the ink supply port that supplies ink to each segment and the ejection port becomes longer, the solvent of the ink near the ejection port evaporates as the non-ejection period becomes longer. Ejection failure (including non-ejection) when performing the next recording because the viscosity becomes high
Occurs, and normal recording cannot be performed.

Therefore, when the time between recordings becomes long, a sealing means such as a cap for covering the discharge port is required, and in the case of a longer period of time, recovery by forcibly sucking out the ink near the discharge port. You need to do something. Therefore, in the ink jet recording apparatus that requires these additional devices, the manufacturing cost increases accordingly, and since the ink that is forcibly sucked is not directly related to the recording, the use efficiency of the ink is inevitably low. This will increase running costs.

FIG. 10 is a schematic view illustrating the influence of the pressure wave due to the previous ejection when the ink ejection time interval is short. That is, when one dot is ejected and the next dot is ejected, if the time interval is short, as shown in FIG. 10, the pressure wave 14 generated by the previous ejection due to the rapid expansion of the bubble 13 is indicated by an arrow. As shown by, the ink swelled portion 18 of the ink that is propagated to the other ejection ports 7 and protrudes forward is generated in these other ejection ports 7, and therefore the ink ejection amount from the other ejection ports 7 at the time of the next ejection. The density may increase and the recorded image may have uneven density. In FIG. 10, 11 is the discharge port 7.
And L ₃ is the maximum amount of ink swelling at the ejection port 7.

Further, in the ink jet head of FIGS. 8 and 9, it is necessary to form a hole penetrating the substrate, but since the hole is formed in the substrate after forming the wiring, the back surface (lower surface) of the substrate is formed. The hole is being drilled from. However, after the holes are formed, the Si wafer that constitutes the substrate is greatly chipped, so that various restrictions are caused by forming the through holes.

For example, it is not possible to approach the ideal structure in which the position of the hole is close to the electric-energy converter, or it is necessary to provide wiring on both sides of the hole. In order to increase the height, it is necessary to increase the substrate area, which causes an inconvenience that the manufacturing cost becomes too high. Note that it is possible to increase the dot density while suppressing an increase in the substrate area by performing a zigzag arrangement or the like, but this causes new restrictions and problems in manufacturing.

In order to solve this problem, Japanese Patent Laid-Open No. 62-
A method of providing a heating resistor on a cantilever beam as disclosed in Japanese Patent No. 259864 has been proposed. However, in this method, the energy of bubbles generated in the heat generating resistor escapes from the hole formed by the beam, and thus there is a disadvantage that the ink ejection efficiency is reduced. Therefore,
It is desirable to have an idea that allows patterning to be performed on a perforated substrate like a conventional substrate.

The present invention has been made in view of such a conventional technique, and an object of the present invention is to make it possible to smoothly supply ink to an ejection port and maintain stable ink ejection. When ejected, it is possible to reduce the influence on the ink ejection of other ejection ports, it is possible to record a uniform image with a constant ink ejection amount,
Another object of the present invention is to provide an ink jet head that does not require an ejection recovery device having a complicated structure and can realize an inexpensive and high performance recording device.

[0019]

According to the present invention, a substrate is provided at each position on the opposite side of a connecting portion to a drive circuit for driving the electric-energy converting body, with each electric-energy converting body interposed therebetween. A penetrating ink supply port is formed, and the ink supply port is used as an ink supply path from the first liquid chamber. Further, for each electric-energy conversion body, only the surface having the ink supply port is open and the other surface. It is characterized in that the second liquid chamber which also functions as a liquid passage having a discharge port is formed.

That is, according to the first aspect of the present invention, there is provided an electric device having a plurality of ejection ports for ejecting ink, a liquid path communicating with each ejection port, and a portion for causing the ink ejection energy to act on the ink in each liquid channel. -In an inkjet head having an energy converter and an electrode connected to each electricity-energy converter, a drive circuit for driving the electricity-energy converter with each electricity-energy converter interposed An ink supply port penetrating the substrate is formed at each position opposite to the connection portion, and a plurality of second liquid chambers surrounding the electric-energy conversion body and the ink supply port are formed for each electric-energy conversion body. However, each of the second liquid chambers is configured to communicate with the common first liquid chamber through the ink supply port, thereby achieving the above object.

According to a second aspect of the present invention, in addition to the structure of the first aspect, the substrate for forming the electric-energy converter is made of metal, and the surface on which the electric-energy converter is formed has a mask. In this state, the ink supply port is formed by etching the surface of the metal opposite to the surface on which the electric-energy converter is formed, thereby achieving the above object more efficiently. .

According to a third aspect of the present invention, the substrate on which the electric-energy converter is formed is made of a Si wafer, and the surface on which the electric-energy converter is formed is masked on the Si surface. The above-described object can be achieved more efficiently by adopting a structure in which the ink supply port is formed by etching the surface of the wafer opposite to the surface on which the electric-energy converter is formed.

According to the above configuration of the present invention, the holes penetrating the front and back of the substrate are formed at accurate positions by the photolithography method, so that the flow resistance of the ink supply to the electric-energy converter is made constant. Therefore, an inkjet head capable of maintaining stable ink ejection can be obtained.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. Throughout the drawings, the same reference numerals indicate the same or corresponding parts. 1 to 3 are schematic vertical sectional views showing first to third embodiments of an inkjet head to which the present invention is applied.
The first to third embodiments are common in respect of the basic configuration, but different in shape and arrangement. FIG.
FIG. 4 is a partially cutaway perspective view schematically showing an internal structure of an ink ejection chamber of each inkjet head shown in FIGS. 1 to 3.

1 to 4, 1 is a substrate, 2 is a heat storage layer for blocking heat, 3 is an electric-energy converter (thin film resistor in this case), 4 is an electric-energy converter. For driving electrically, 5 is an ink ejection chamber forming a liquid chamber including an ejection port and an ink supply port for each electric-energy converter, 6 is a common electrode, 7 is an ejection port, and 8 is an ink supply port. Is.

1 to 4, a plurality of discharge ports 7 are formed at a predetermined pitch, and the electric-energy converter 3 is provided for each discharge port 7. A heater (heating element) for film-boiling the ink adjacent to it to foam the ink is provided in a part of 3. The interior of the ink ejection chamber 5 is defined by the partition wall 20 formed between the ejection ports 7.
A second liquid chamber 15 is formed for each discharge port (two discharge ports) 7.

Further, each of the discharge ports 7 corresponds to one of the electric-energy converter 3 and the heater 17, and therefore, the heater 17 corresponds to each of the second liquid chambers 15. An electric-energy converter 3 having is arranged. Each heater 17 is arranged at a position capable of generating bubbles suitable for applying ejection energy to the ink in the second liquid chamber 15.

1 to 4, each of the second liquid chambers 15 is
Is formed on the front surface (upper surface) of the substrate 1, and on the back surface (lower surface) of the substrate 1, a first liquid chamber 16 common to each ejection port 7 is formed. In each of the illustrated embodiments, the first liquid chamber 16
Are formed inside the ink tank / substrate support member 9. The ink supply port 8 penetrates through the front and back of the substrate 1 for each second liquid chamber and the first liquid chamber 16 and each second liquid chamber.
It is formed so as to communicate with the liquid chamber 15.

The ink supply port 8 is formed on the front side (left side in the drawing) of the electric-energy converter 3. Further, a drive circuit (not shown) for driving the electric-energy converter 3 is provided at the rear (right side in the figure) end of each electric-energy converter 3 to bond 1 in FIG.
They are connected by a fixing means such as 0.

In this way, a plurality of ejection openings 7 for ejecting ink, a liquid passage (second liquid chamber) 15 communicating with each ejection opening 7,
In an ink jet head having an electric-energy conversion body 3 having a portion for applying ink ejection energy to ink in each liquid path 15 and an electrode 6 connected to each electric-energy conversion body 3, An ink supply port 8 penetrating the substrate 1 is formed at each position on the opposite side of the connection part to the drive circuit for driving the electricity-energy conversion body with the energy conversion body 3 interposed therebetween. A plurality of second liquid chambers 15 surrounding the electricity-energy converter and the ink supply port 8 are formed for each energy converter 3, and each of the second liquid chambers 15 is a common first liquid chamber through the ink supply port 8. An ink jet head that communicates with 16 is configured.

Next, a first method of manufacturing an ink jet head according to the present invention will be described in the order of steps. First, thickness 0.
A 1 mm Al plate (substrate) 1 is coated with polyimide, which also serves as a heat storage layer 2 and a resist, by spin coating so as to have a thickness of 0.5 μm after curing. By the photolithography method, the portion that will become the common electrode 6 and the ink supply port 8 are removed, and curing is performed sequentially at 200 ° C. and 450 ° C.

HfB _{2 of the} thin film resistor forming the electric-energy converter 3 and Al forming the conductor of the wiring 4 are sputtered thereon and patterned by photolithography. Sputtering and patterning of protective film (not shown)
A resist having a hole for the ink supply port 8 is applied to the back surface of the substrate 1 for performing the above step, and thereafter, a casting is applied to a portion of each electric-energy conversion body 3 which becomes the chamber 5 (second liquid chamber 15). An agent is applied and patterned.

A resist for forming the wall of the ink ejection chamber 5 is applied, and the resist in the ejection port 7 is removed. When the hole of the resist applied on the back surface of the substrate 1 is removed by etching, a mortar-shaped through hole (ink supply port) 8 as shown in FIG. 6 is formed in the substrate 1. A slight displacement in this case can be corrected by the holes 18 formed in the upper heat storage layer 2.

The ink supply port 8 and the ink discharge port 7 are used as inlets and outlets for the chambers of the electric-energy converters 3 (second
The casting agent inside the liquid chamber 15) is removed. After that, the IC is bonded to the external connection terminal on the opposite side of the chamber 5 in which the discharge port 7 is located. An ink filtration filter and an ink supply unit are installed on the ink flow path side. An ink cooling unit is attached to the back surface of the substrate 1. Thus, the inkjet head to which the present invention is applied is completed.

According to the first method for manufacturing an ink jet head of the present invention described above, the substrate 1 on which the electric-energy converter 3 is formed is metal (Al in this embodiment).
The surface on which the electric-energy converter 3 is formed is a surface opposite to the electric-energy converter forming surface (upper surface = surface) of the metal in a masked state.
By etching from the back surface), an ink jet head characterized in that the ink supply port 8 is formed can be obtained.

Next, a second method of manufacturing an ink jet head according to the present invention will be described in the order of steps. First, thickness 0.
A 1 mm Si plate (substrate) 1 is coated with polyimide, which also serves as a heat storage layer 2 and a resist, by spin coating so as to have a thickness of 0.5 μm after curing. The ink supply port 8 is removed by the photolithography method, and curing is performed sequentially at 200 ° C. and 450 ° C.

HfB _{2 of the} thin film resistor forming the electric-energy converter 3 and Al forming the conductor of the wiring 4 are sputtered thereon and patterned by photolithography. Sputtering and patterning of protective film (not shown)
A resist having a hole for the ink supply port 8 is applied to the back surface of the substrate 1 for performing the above step, and thereafter, a casting is applied to a portion of each electric-energy conversion body 3 which becomes the chamber 5 (second liquid chamber 15). An agent is applied and patterned.

A resist for forming the wall of the ink ejection chamber 5 is applied, and the resist in the ejection port 7 is removed. When the hole of the resist applied on the back surface of the substrate 1 is removed by etching, a mortar-shaped through hole (ink supply port) 8 as shown in FIG. 6 is formed in the substrate 1. A slight displacement in this case can be corrected by the holes 18 formed in the upper heat storage layer 2. Alternatively, a vertical hole may be formed by using anisotropic etching of Si, or a mortar-shaped hole with an inclination may be formed.

The ink supply port 8 and the ink discharge port 7 are used as inlets and outlets, and the chamber of each electric-energy converter 3 (second
The casting agent inside the liquid chamber 15) is removed. After that, the IC is bonded to the external connection terminal on the opposite side of the chamber 5 in which the discharge port 7 is located. An ink filtration filter and an ink supply unit are installed on the ink flow path side. An ink cooling unit is attached to the back surface of the substrate 1. Thus, the inkjet head to which the present invention is applied is completed.

According to the second method of manufacturing an ink jet head of the present invention described above, the substrate 1 on which the electric-energy converter 3 is formed is made of a Si wafer, and the electric-energy converter 3 is formed. On the surface to be formed,
The ink supply port 8 is formed by etching from a surface (lower surface = back surface) opposite to an electric-energy converter forming surface (upper surface = front surface) of the Si wafer in a masked state. The head is obtained.

Through the above manufacturing steps, the ink jet head of the present invention, that is, a plurality of ejection openings for ejecting ink, liquid passages communicating with the respective ejection openings, and energy for ejecting ink into the respective liquid passages are applied to the ink. In an inkjet head having an electric-energy converter having a portion to be activated and an electrode connected to each electric-energy converter, the electric-energy converter is driven by sandwiching each electric-energy converter 3. An ink supply port 8 penetrating the substrate 1 is formed at each position on the opposite side opposite to the connection portion to the drive circuit, and the electric-energy conversion body and the ink supply port are provided for each electric-energy conversion body 3. A plurality of surrounding second liquid chambers 15 are formed, and each of the second liquid chambers 15 is connected to the common first liquid chamber 16 through the ink supply port 8. Ttoheddo is obtained.

6 and 7 are drawings for explaining the effect of the ink jet head according to the present invention, FIG. 6 is a schematic vertical sectional view, and FIG. 7 is taken along line 7-7 in FIG. It is a schematic cross-sectional view. According to the inkjet head of the present invention described with reference to FIGS. 1 to 5, when the heater 17 of each electric-energy converter 3 is driven to eject ink, the pressure wave generated in the corresponding second liquid chamber 15 is generated. 14 is
As shown by the arrow in FIG. 6, the component in which the pressure wave 14 reaches the common first liquid chamber 16 by repeating reflection in the second liquid chamber 15 becomes very small.

Therefore, the pressure wave transmitted from the first liquid chamber 16 to the other second liquid chamber 15 can be almost eliminated.
Therefore, it is possible to substantially prevent the pressure wave generated inside one ejection port 7 from affecting the ink of the other ejection port, and the influence on the ink ejection function (image recording performance) of the other ejection port. Can be eliminated. In addition, since sufficient ink is supplied to the second liquid chamber 15, it is possible to prevent ejection failure due to ink component evaporation (ink thickening) of the ejection port 7 caused by standing for a long time.

[0044]

As is apparent from the above description, according to the invention of claim 1, a connecting portion to a drive circuit for driving the electric-energy converters with each electric-energy converter interposed therebetween. An ink supply port penetrating the substrate is formed at each position on the opposite side, and the ink supply port serves as an ink supply path from the first liquid chamber. Further, the ink supply port is provided for each electric-energy converter. Since the second liquid chamber also has a structure in which only one surface is opened and the other surface has an ejection port, the second liquid chamber also functions as a liquid path, so that when ink is ejected, the influence on ink ejection from other ejection ports is reduced. Inkjet head capable of recording a uniform image with a constant ink discharge amount, and without needing a discharge recovery device having a complicated configuration, and capable of realizing an inexpensive and high-performance recording device Provided by It is.

According to the invention of claim 2, in addition to the constitution of claim 1, the substrate for forming the electric-energy converter is made of metal, and the surface on which the electric-energy converter is formed is In addition to the effect of claim 1, since the ink supply port is formed by etching from a surface of the metal opposite to the surface on which the electric-energy converter is formed in a masked state, Since the distance between the ink supply port and the electric-energy converter can be controlled with high accuracy up to the degree of alignment of the photomask, an inkjet head that can smoothly supply ink to the discharge port and maintain stable ink discharge is provided. To be done.

According to the invention of claim 3, in addition to the structure of claim 1, the substrate on which the electric-energy converter is formed is made of a Si wafer, and the electric-energy converter is formed. The surface is masked with the Si
Since the ink supply port is formed by etching from the surface of the wafer opposite to the surface on which the electric-energy converter is formed, the ink supply port and the electric-energy can be obtained in addition to the effect of the above-mentioned claim 1. Since the distance between the converters can be controlled with high accuracy up to the degree of alignment of the photomask, an ink jet head that can smoothly supply ink to the ejection ports and maintain stable ink ejection is provided.

[Brief description of drawings]

FIG. 1 is a first inkjet head to which the present invention is applied.
It is a typical longitudinal cross-sectional view of an example.

FIG. 2 is a second inkjet head to which the present invention is applied.
It is a typical longitudinal cross-sectional view of an example.

FIG. 3 is a third view of an inkjet head to which the present invention is applied.
It is a typical longitudinal cross-sectional view of an example.

FIG. 4 is a partially cutaway perspective view schematically showing the structure of a second liquid chamber of each inkjet head shown in FIGS. 1 to 3.

FIG. 5 is a schematic vertical sectional view showing an ink supply port formed in a substrate of an inkjet head to which the present invention is applied.

FIG. 6 is a vertical cross-sectional view schematically showing the propagation state of pressure waves during ink ejection in the inkjet head according to the present invention.

7 is a cross-sectional view taken along the line 7-7 in FIG.

FIG. 8 is a vertical cross-sectional view schematically showing a structural example of a conventional inkjet head.

FIG. 9 is a vertical cross-sectional view schematically showing another structural example of a conventional inkjet head.

FIG. 10 is a schematic diagram exemplifying a swelling of ink generated in another ejection port due to the propagation of a pressure wave associated with ink ejection.

[Explanation of symbols]

 1 Substrate 2 Heat Storage Layer (PI) 3 Electric-Energy Converter 4 Electric Wire 5 Ink Ejection Chamber 6 Common Electrode 7 Ejection Port 8 Ink Supply Port 9 Ink Tank / Substrate Support Member 10 Bonding (Connecting Portion with External Driving Circuit) 11 Flying Droplet (ejected ink) 12 Recording material (recording paper) 13 Bubble 14 Pressure wave in ink 15 Second liquid chamber 16 First liquid chamber 17 Heater 18 Rising ink 20 Partition wall (second liquid chamber)

Claims (3)

[Claims] 1. An electric-energy conversion body having a plurality of ejection openings for ejecting ink, liquid passages communicating with the respective ejection openings, and a portion for causing the ink ejection energy to act on the ink in each liquid passage, In an inkjet head having an electrode connected to an electric-to-energy converter, the opposite side of each electric-to-energy converter sandwiching the electric-energy converter to a connecting portion to a drive circuit for driving the electric-to-energy converter. Ink supply port that penetrates the substrate is formed at each position of
Forming a plurality of second liquid chambers surrounding the electric-energy converter and the ink supply port for each electric-energy converter,
An ink jet head characterized in that each of the second liquid chambers is connected to a common first liquid chamber through an ink supply port. 2. The substrate for forming the electric-to-energy converter is made of metal, and the surface on which the electric-to-energy converter is formed is masked to form the electric-metal of the metal.
The ink jet head according to claim 1, wherein the ink supply port is formed by etching from a surface opposite to an energy converter forming surface. 3. The substrate on which the electric-energy conversion body is formed is made of a Si wafer, and the surface on which the electric-energy conversion body is formed is masked and the electric-energy of the Si wafer is formed. The inkjet head according to claim 1, wherein the ink supply port is formed by etching from a surface opposite to the conversion body forming surface.