JPH0948121A - Printing head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing head for ink jet recording enabling highly detailed printing at a high speed, low in power consumption and capable of being produced in low cost. SOLUTION: A plurality of heating elements 5a are arranged on one surface of an insulating substrate 3. A pressure container 14 having the heating element 5a provided to the inner wall surface thereof and holding a definite amt. of ink and having an ink emitting nozzle 7 provided thereto as a through-hole at the position opposed to the heating element 5a is formed to each of the heating elements 5a. An ink container 2 filled with ink is arranged to the other surface of the insulating substrate 3 and the ink supply port 4a piercing the insulating substrate 3 to supply ink from the ink container 2 to the pressure container 14 is provided to the center part of the heating region by the heating element 5a. Typically, the heating element 5a is composed of a ring-shaped electric resistance heating element and the ink supply port 4a is opened to the center part of the ring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording apparatus (printer) for recording on a recording medium such as paper with ink, and particularly to heating the ink by a heating element to generate bubbles in the ink, The present invention relates to the structure of an inkjet printer head, that is, an ink ejection unit, which ejects ink from a nozzle onto a recording medium due to expansion and causes the recording medium to perform recording.

[0002]

2. Description of the Related Art In recent years, printers have become widespread as hard output terminal devices and hard copy devices used in computers, facsimile machines, word processors and the like. Various types of recording principles have been put into practical use as printers, and among them, inkjet printers have been attracting attention because they can realize high-speed, high-definition printing with low driving noise and low power consumption. Inkjet printers
Generally, ink is ejected intermittently in response to a recording signal from a nozzle containing an energy generating element that generates energy for ejecting ink, and dots are printed on a recording medium.
Ink is transferred in the form of (dot) to form a print record. As the energy generating element, an electric resistance heating element for heating and foaming the ink is preferably used.
In order to record a plurality of dots at the same time by using one printer head, the printer head for an inkjet printer has a structure in which a plurality of energy generating elements are arranged on an insulating substrate. The printer head is classified into a side chute type and an edge chute type according to the relationship between the insulating substrate and the ink ejection direction. Hereinafter, the case where an electric resistance heating element is used as the energy generating element is given as an example,
A conventional side chute type printer head and edge chute type printer head will be described.

FIG. 7 is a view showing a sectional structure of a printer head of a conventional side shoot type ink jet printer.

The printer head 1 has an insulating substrate 3 having a large number of heating elements 5 which are planar electric resistors arranged on one surface.
Is provided. An ink container 2 filled with ink is arranged on the other surface of the insulating base 3. Each heating element 5 corresponds to a dot, and each heating element 5
An ink supply pipe 4, an ink heating container 6, and an ink ejection nozzle 7 are provided. The ink supply pipe 4 penetrates the insulating substrate 3 in order to supply ink to the individual ink heating containers 6 from the ink container 2. In the ink heating container 6, the heating element 5 is arranged on the bottom surface, and the ink discharge nozzle 7 is arranged so as to face the heating element 5. These are finely formed in order to realize high resolution and high definition printing. The recording medium is arranged so as to face the ink discharge nozzles 7, and the heating element 5 is energized to generate heat according to a recording signal, whereby the ink 1 in the ink heating container 6 is heated.
2 foams and expands (air bubbles 9), and the pressure causes ink in the vicinity of the ink ejection nozzle 7 to be ejected toward the recording medium, and minute ink droplets 8 are ejected and fly and collide with the surface of the recording medium.
The ink is transferred.

In the ink jet printer, each ink discharge nozzle 7 corresponds to one color. Therefore, in order to realize high-definition / high-gradation color printing, which has been increasing in demand in recent years, it is necessary to aggregate the heads for each color into a so-called multi-head and further reduce the dot size. Tube 4, heating element 5
Also, the ink ejection holes 7 must be made finer.

300 dpi currently generally realized
(Dpi = dot / inch, 1 inch (25.4 mm)
The printer head with the number of dots per dot) is configured by arranging the ink discharge nozzles 7 having an opening diameter of 20 μm at a pitch of 80 μm. In future high-definition heads, for example, 60
In the 0 dpi head, the ink discharge nozzles should be arranged at a pitch of 40 μm, and in the 1200 dpi head, the ink discharge nozzles should be arranged at a pitch of 20 μm. In order to realize high-definition printing, the permissible size of each mechanism for ejecting ink, in particular, the area of the heating element 5 which is a sheet-like electric resistor becomes smaller and smaller. Therefore, generally, a silicon substrate whose surface is oxidized is used as the insulating base 3, and the ink supply pipe 4, the heating element 5, and the ink discharge nozzle 7 are finely formed on the insulating base 3 by the photolithography technique or the laser processing technique. . Further, as shown in FIG. 7, for example, the ink ejection nozzles 7 are arranged in two rows at a pitch (opening pitch A, here 80 μm) corresponding to 300 dpi for each row. 7a and the discharge nozzle row 7b are arranged so as to be displaced by a distance of half the opening pitch A (here, 40 μm),
Although the size of each mechanism is for 300 dpi, 6
It is possible to obtain a printer head corresponding to a recording density of 00 dpi, and it is possible to suppress the reduction in the size allowed for each mechanism for ejecting ink. If the number of ejection nozzle rows is increased, a printer head with higher resolution can be obtained. Further, by using the silicon substrate having the surface oxide film as the insulating base 3, it becomes possible to monolithically form various functional elements for driving the heating element 5 according to the recording signal in the insulating base 3. .

FIG. 8 shows a conventional printer head 1 of the edge shoot type. The ink container 2 and each heating element 5 are arranged on the same side of the insulating substrate 3. Therefore, one end of the flow path-shaped ink heating container 6 is opened to the outside as the ink discharge nozzle 7, and the other end is connected to the ink container 2 as the ink supply pipe 4. In the edge shoot type printer head 1, the heating elements 5 are arranged in a line in a direction parallel to the surface of the recording medium, and the longitudinal direction of the ink heating container 6 is perpendicular to the surface of the recording medium. . Even with an edge shoot type printer head,
By adhering and stacking, a plurality of ejection nozzle rows can be provided, and reduction in size of each mechanism can be suppressed and high resolution can be realized.

By the way, there is an increasing demand for the printer to be carried and used. Due to this demand, not only the printer is downsized and the resolution is increased, but also the power consumption is reduced in the printer using the heating element. Therefore, there is a demand to extend the uptime. In order to satisfy the demand for reducing the power consumption, it is required to reduce the driving power of the heating element, that is, to reduce the size of the heating element and increase the electric resistance.

As a material for a heating element of an ink jet printer, a tantalum nitride (Ta ₂ N) thin film, which is excellent in high resistance, heat resistance and mechanical strength, is used. Demand for smaller size, Ta ₂
TiAlN thin film or Mo, which has a higher specific resistance than N
High-resistance thin films such as Si thin films are also being considered as candidates for heating elements.

In the case of a side shoot type printer head, the heating element 5 is arranged immediately below the ink discharge nozzle 7 as shown in FIG. 7, and is an edge shoot type printer head. If there is, it is placed in the middle of the ink heating container 6 having a flow path shape as shown in FIG. 8, but in any case, the expansion pressure of the bubble 9 due to heating repels the internal pressure of the ink container 2. Concentrate in the direction of the ink ejection nozzle 7. Embankment 1 in the middle of ink supply pipe 4
It is also practiced to arrange 0 to increase the pressure resistance on the ink container 2 side.

The surface of the heating element 5 is hard for the purpose of ensuring electrical insulation from ink and preventing peeling and destruction of the heating element thin film from the insulating substrate 3 due to mechanical shock due to pulsation during bubble expansion. It is often covered with the insulating film 11. As a material of the ink 12, there is a material in which fine particles of a dye or pigment type are mixed, and a device for preventing image sticking due to heat generation has been made.

[0012]

In order to realize high resolution and high definition printing, a printer head for an ink jet printer has a small opening diameter of an ink discharge nozzle, a small discharge hole interval, and a heating element. Attempts have been made to reduce the size and increase the resistance. However, assuming an electric resistance heating element in which electrodes are arranged on both sides of the resistance film, miniaturization of the heating element means shortening of the length of the resistance portion, and the electric resistance of the heating element decreases. Electric resistance can be increased by making the resistance film thinner (smaller cross-sectional area).
Assuming that the temperature is raised to near 00 ° C. and the impact of foaming shrinkage is assumed, the mechanical durability of the heating element becomes a problem when the resistance film is thin. Moreover, the size of the ink droplets to be ejected is inevitably reduced due to the miniaturization of the ink ejection holes. Assuming that smaller ink droplets are projected and ejected to record in the same area as before, the time interval for ejecting ink droplets is shortened, that is, the heating element is heated and cooled in a short time. Will have to. From this, it is naturally required that the heating element has excellent heating efficiency and also has excellent heat dissipation function. The use of a silicon substrate whose surface is oxidized as the insulating substrate is convenient for heat dissipation because the ink itself is also a material with good heat conduction, but it becomes a factor that prevents the temperature rise of the heating element in a short time. . In particular, in the printer head in which the heating element of the ink flow path is arranged like the conventional edge shoot type, depending on the volume of the ink flow path part,
Since the heat dissipation through the ink becomes remarkable, there arises a problem that the electric power that must be applied to the heating element at the time of heat generation increases and the heating response characteristic of the heating element deteriorates.

As the insulating substrate, in addition to a silicon substrate having a thermal oxide film formed on its surface, there are those having a highly thermally conductive material such as aluminum and having an anodized film formed on the surface thereof. As an insulating substrate,
Those using resin, glass, various ceramics, etc. can be considered. Among these, the glass substrate is designed at a lower cost than the silicon substrate by using the photolithography technology, as is proved by the recent application examples to the display panel, and the design rule equivalent to that of the conventional silicon substrate is used. It is a promising material for supplying a printer head at low cost because the wiring can be patterned.
Moreover, considering that the area occupied by the input wirings other than the functional elements in the insulating base increases as the number of nozzles increases, it is disadvantageous in terms of cost to use an expensive base only as a supporting base.

On the other hand, if the base material immediately below the heating element is thick, this portion will act as a heat storage layer.
It becomes difficult to eject ink continuously in a short repetition period, and structural ingenuity is required. Further, when a mechanically flexible heat-resistant resin film such as polyimide amide is used as the insulating substrate, the insulating substrate buffers the pressure of foaming, which reduces the efficiency of pressure transmission to ink. There are drawbacks.

It is an object of the present invention to provide a printer head capable of high-speed, high-definition printing, low power consumption, and low cost.

[0016]

A printer head according to the present invention has an insulating base and a plurality of heating elements arranged on the insulating base, and heats ink in a liquid phase by the heating elements. In a printer head that prints by ejecting ink from an ink ejection nozzle by the pressure of vaporizing and expanding, the ink ejection nozzle is formed as a through hole provided for each heating element and having the heating element on the inner wall surface. A pressure container for holding a fixed amount of the ink and an ink container filled with ink provided in the central portion of the heating region of the heating element for each of the heating elements communicate with each other and are opened to penetrate the insulating substrate. An ink supply hole for supplying ink to a corresponding pressure container.

In the present invention, the plurality of pressure vessels are integrally formed, and the adjacent pressure vessels share a partition for isolating the thermal expansion pressure of the ink due to the heating of the heating element from each other. it can.

In the present invention, the heating element is preferably a linear electric resistance heating element which is heated by energization and bent in a predetermined pattern. In this case,
It is desirable to connect electrodes and wirings for supplying electric power for resistance heating from an external power supply source to both ends of the heating element, and cover the surface of the heating element with an electric insulating layer. Further, it is desirable to improve the ink ejection characteristics by providing a heat conductive film on the electrical insulating layer so as to open the ink supply hole and cover the entire heating region of the heating element. As the bending pattern of the heating element, for example, a single ring shape having a cutout portion, a roughly ring shape having a concentric folded multi-layered structure, a rough ring shape having a meandering structure, and a continuous concentric rectangular folded multi-layered structure. Examples thereof include a substantially rectangular shape having, or a roughly rectangular shape having a meandering structure. In these cases, the ink supply hole is opened at the center of the ring or the rectangle.

In the present invention, the ink container can be arranged in any manner as long as it communicates with the ink supply hole. For example, the ink container is formed on the surface of the insulating substrate on which the heating element is not provided, and the The substrate may form at least a part of the wall of the ink container. Further, in order to improve the efficiency of heating the ink by the heating element, the thickness of the insulating substrate is made thinner on the back surface side of the area of the insulating substrate where the heating element and the ink supply hole are formed, as compared to the other areas. You may form a recessed part.

In each pressure vessel, the ink supply hole and the ink discharge nozzle typically face each other. It is desirable that the opening diameter of the ink ejection nozzle is substantially the same as the opening diameter of the ink supply hole or larger than the opening diameter of the ink supply hole. The pressure vessel may be provided with an inner wall having a tapered structure that narrows from the insulating substrate side toward the ink discharge nozzle. Further, from the viewpoint of cooling the ink, the wall of the portion of the wall of the pressure container including the ink discharge nozzle can be formed of metal. In order to keep the distance between the ink ejection nozzle and the recording medium constant, a groove may be formed on the outer wall surface of the pressure container, and the ink ejection nozzle may be opened at the bottom surface of this groove.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The printer head of the present invention is a printer head of the side chute type described above, in which, for each heating element of each dot, an ink container and a pressure container are provided at a position substantially in the central region of the heating element. An ink supply hole communicating with the (ink heating container) is provided in the insulating base. Then, typically, in each pressure container, an ink discharge nozzle is provided at a position facing the ink supply hole, and the pressure container and the ink container are arranged adjacent to each other using the insulating substrate as a partition. The pressure container is separated for each dot, that is, for each ink ejection nozzle.

FIG. 9 is a perspective view for explaining the periphery of the ink supply hole 4a for each dot in the preferred embodiment of the present invention. The insulating base 3 is provided with an ink supply hole 4a, which is a through hole, and one surface of the insulating base 3 is provided with
A ring-shaped heating element 5a having one missing portion is arranged so as to surround the ink supply hole 4a. 1 on each end of the heating element 5a across the missing part as a ring.
A pair of metal wirings 13 are connected to each other so that the heating element 5a, which is an electric resistor, can be energized.

As described in the prior art, by using a heating element material having a higher resistivity, the heating element can be downsized even with the conventional planar electric resistance heating element structure. High-definition printing is possible. However,
Since the heating element 5a shown in FIG. 9 has a linear configuration, the cross-sectional area of the heating element can be reduced and the extension of the heating element can be lengthened, so that a heating element having a small size and high resistance can be obtained. You can Further, by disposing the heat generating element 5a in the center of the heat generating element 5a, that is, so as to surround the ink supplying hole 4a, the efficiency of heat transfer from the heat generating element 5a to the ink is increased, as will be described later. be able to. By configuring the printer head as described above, even when using a conventional heating element material, the thermal energy required to eject ink is generated in a short time with a smaller size and lower power than the conventional one. It is possible to obtain a heating element that can.

The shape of the linear heating element 5a is not limited to a single ring shape, and a concentric circular folded ring shape, a rectangular shape with the same center, or a meandering shape can be used. In any case, the ink ejection nozzle is arranged above the center of the heating region of the heating element 5a.

FIGS. 10A and 10B are views for explaining a portion corresponding to one dot of the printer head, which is a cross-sectional view taken along a plane perpendicular to the insulating base 3. The lower side of the insulating substrate 3 in the drawing corresponds to an ink container filled with the ink 12. The ink container is commonly provided for a plurality of ink ejection nozzles 7 that eject ink of the same color. Also,
The surface of the heating element 5a has a hard insulating film 1 as described later.
It is covered by 1. On the other hand, a portion above the insulating substrate 3 in the drawing is the pressure container 14 for each dot, and the ink ejection nozzle 7 is directly faced to the ink supply hole 4a on the surface of the wall surface of the pressure container 14 facing the insulating substrate 3. Is provided.

As shown in FIG. 10A, the ink supply hole 4
The opening diameter of a is extremely small like the conventional printer head. Therefore, at the same time when the heating element 5a is energized to generate heat, the ink in the ink supply hole 4a is vaporized and the inside of the ink supply hole 4a is replaced with gas. In addition, the ink 12 near the heating element 5a in the pressure container 14 also foams into bubbles 9, and the expansion force of the bubbles 9 (the arrow shown in the figure) causes the ink that has not been vaporized into the ink droplets 8 in the pressure container 14. It projects from the ink ejection nozzle 7 and flies toward the recording medium.
The bubbling of ink on the heating element 5a continues until the ink in the entire area of the heating element 5a is replaced with gas, and the expansion of the gas is almost saturated by the heat insulation by the gas.
Has been completed. In this printer head, at the same time as the heat generation of the heating element 5a, the path through which the heat leaks to the ink container side via the ink supply hole 4a is blocked by the bubble 9, and the bubble 9 having a low thermal conductivity is passed. Since only the heat leaks, the heat insulating effect at the time of heat generation of the heating element 5a is enhanced. That is, the heating element in the printer head of the present invention needs to heat and foam only the ink in the pressure container, and compared with the conventional heating element in the printer head that also heats the ink in the ink supply pipe. , Excellent in heat efficiency.

By the way, in a flow path of a minute size as seen in the head of an ink jet printer, the kinematic viscosity coefficient of the vapor phase due to heating and foaming is remarkably larger than that of the liquid phase. It is known that it is much harder to flow than the phase (for example, published by Institute of Mechanical Engineering, Institute of Industrial Science, Machine Research News, No. 3, 199).
5 years). In the pressure vessel 14 shown in FIGS. 10 (a) and 10 (b),
When the opening diameter and the tube length of the ink supply hole 4a and the ink discharge nozzle 7 are substantially the same, the inside of the ink supply hole 4a becomes a vapor phase due to the heating by the heating element 5a, so that the liquid phase state inside the ink discharge nozzle 7 A viscous resistance larger than that of the ink is generated on the side of the ink supply hole 4a and acts like a check valve for the fluid, whereby the expansion pressure due to the heat bubbling of the ink is exclusively directed to the side of the ink discharge nozzle 7. Therefore, it has an advantageous effect in ejecting ink.

Alternatively, by making the cross-sectional shape of the pressure vessel 14 into a conical taper shape that narrows from the heating element 5a side to the ink discharge nozzle 7 side, the fluid resistance on the ink discharge hole nozzle 7 side is reduced and at the same time. In the case of pushing out with the same pressure, the opening is gradually narrowed to increase the ink ejection speed and improve the directivity in the ejection direction. Further, as typically seen in FIGS. 10 (a), (b),
By making the opening diameter of the ink discharge nozzle 7 larger than the opening diameter of the ink supply hole 4a and making the flow path asymmetrical, the pressure loss on the ink supply hole 4a side has a unidirectional characteristic (diode characteristic). The pressure due to the expansion of the bubbles is concentrated on the ink ejection nozzle 7 side. As a result, the conversion efficiency from the expansion pressure to the kinetic energy of the flying ink droplet is increased.

On the other hand, when the heating element 5a is cooled, as shown in FIG.
As shown in (b), the gas inside the pressure container 14 contracts (the arrow shown in the figure), and at the same time, due to the difference in the viscosity between the liquid phase and the gas phase, the ink in the liquid phase state flows from the ink container into the ink supply hole 4a. 1
2 flows in at a large flow rate, whereby the pressure container 14 is filled with ink in a short time. In addition, the inflow of ink from the ink container accelerates the cooling rate of the heating element 5a.

By the way, in the case of the conventional planar heating element, since the heating element itself acts as a heat storage element during cooling, it takes time to cool. On the other hand, when a linear heating element is used, the heat storage volume of the heating element itself is small, and since it can be regarded as a kind of fin structure, the cooling time can be shortened. Therefore, the linear heating element has excellent responsiveness in heating and cooling, and exerts its power in ink ejection in a short cycle associated with high-definition printing.

Here, assuming that the amount of ink ejected is approximately the same as the amount of ink required to print a single dot, and is the same as the minimum amount of bubbling gas, according to the configuration of the present invention, The minimum amount of ink on the heating element can be made approximately the same as this, and the power consumption can be reduced by downsizing the pressure vessel and the heating element. That is, if the amount of ink on the heating element 5a is fixed, a fixed amount of ink can be efficiently ejected by thermal bubbling.

As described above, the insulating film 11 is provided on the surface of the heating element 5a. In view of the fact that various ions and conductive particles are mixed in the ink 12, the insulating film 11
The heating element 5a and the ink 12 are arranged for the purpose of preventing them from coming into direct electrical contact with each other and leaking the electric power which should be used for heating. Further, a heat conductive film may be provided on the insulating film 11 so as to open the ink supply hole and cover the entire heating region by the heating element 5a. By providing a heat conductive film, the heating from the linear heating element can be made uniform in a plane, and the pressure shock to the heating element due to foaming and contraction of the ink is buffered by this heat conductive film. It becomes possible to improve the mechanical durability of the heating element. The heat conducting film is typically a metal film and comes into contact with the ink 12, and therefore the heat generating element 5a.
Is electrically separated from. When the linear heating element is formed by folding back, it is advisable to use a planar heat conduction film that fills the gap between the adjacent heating elements via the insulating film.

By the way, the heat generated by energizing the heating element 5a is transmitted to the pressure vessel 14 direction and the insulating base 3 direction. However, when the insulating base 3 is thick, the insulating base 3 functions as a heat sink and heats the ink. Transmission efficiency is reduced.
Therefore, it is conceivable that the thickness of the insulating substrate 3 immediately below the heating element 5a is optimally thin enough to withstand the mechanical strength and to insulate the heat required for heating the ink in a short time. With this configuration, the back surface of the insulating base 3 is always in contact with the ink 12 in the ink container, so that the insulating base 3 can be prevented from functioning as a heat sink. The thinning of the insulating substrate 3 at a portion immediately below the heating element 5a is realized by forming a groove or a recess which is continuous with the ink supply hole 4 on the back surface of the insulating substrate 3.

In this printer head, as described above, since the pressure vessels 14 are separated for each ink ejection nozzle 7, a partition wall exists between the adjacent pressure vessels 14. The partition wall is preferably made of a heat insulating material from the viewpoint of efficiently transferring the heat generated by the heating element to only the ink. Further, the pressure vessel 14 can be formed by processing a material such as glass or heat resistant resin by using a photolithography technique, or by cutting or molding. Furthermore, by using a heat conductive material such as metal as the wall material of the surface including the ink discharge nozzle 7 in the pressure container 14, heat accumulation can be avoided and the ink in the pressure container can be cooled by the atmosphere after the ink discharge. As a result, the heating element and the ink in the pressure container can be cooled in a shorter time.

[0035]

Next, the present invention will be described in more detail by way of examples.

<< Embodiment 1 >> FIG. 1 shows a sectional structure of an ink jet printer head according to Embodiment 1 of the present invention. In this printer head 1, an insulating base 3 made of glass is used.
BSG (borosilicate glass) film 14a having a plurality of circular through holes is laminated on the surface of the insulating substrate 3. Ring-shaped heating elements 5a are provided on the surface of the insulating base 3 inside the through holes of the BSG film 14a. The surface of each heating element 5a is covered with an electrically insulating insulating film 11 made of silicon nitride (SiN) or BSG, and the surface of the insulating film 11 is provided with a heat conducting film 15 made of metal. An ink supply hole 4a, which is a through hole, is formed in the insulating substrate 3 so as to correspond to the central portion of the ring-shaped heating element 5a. Then, a metal film 16 made of an aluminum film or the like is stacked on the BSG film 14a to form the metal film 1
An ink discharge nozzle 7, which is a through hole, is formed in the nozzle 6 at a position directly facing the ink supply hole 4a. With this configuration, the pressure vessel 1 having the insulating substrate 3 as the bottom surface, the BSG film 14a as the side surface, and the metal film 16 as the top surface 1
4 is formed for each ink ejection nozzle 7.

On the other hand, on the back surface side of the insulating substrate 3, a plastic ink container 2 common to each ink ejection nozzle 7 is adhered. Then, the back surface side of the insulating base 3 and at least the portion immediately below the heating element 5a is a recess 3a, and the thickness of the insulating base 3 at the portion directly below the heating element 5a is maintained while maintaining the mechanical strength. It is optimally thin.

Next, a method of manufacturing the printer head 1 will be described.

First, Ta is formed on the surface of the glass insulating substrate 3.
An N thin film is formed by sputtering and patterned to form a partially defective ring-shaped heating element 5a having an outer diameter of 40 μm and a line width of 10 μm as shown in FIG. further,
An aluminum thin film is formed and patterned to form a heating element 5
Metal wiring 13 (see FIG. 9) is formed on both ends of a.

Next, a film of silicon nitride (SiN) or borosilicate glass (BSG) is formed by thermal CVD and patterned to form the insulating film 11, and then a high temperature film such as a stainless film is formed on the surface of the insulating film 11. The heat conducting film 15 is formed by forming a metal film having heat resistance and patterning it. In this way, at least the heating region of the heating element 5a is covered with the insulating film 11 and the heat conducting film 15.
To cover. At that time, the ring-shaped heating element 5a
No insulating film or heat conducting film is formed in the central opening, that is, in the area where the ink supply hole 4a is to be formed.

For the insulating substrate 3 on which the heating element 5a, the insulating film 11 and the heat conducting film 15 are formed in this way, for example, 10
The BSG film 14a is formed with a thickness of μm. After that, the heat conducting film 15 and the insulating substrate 3 are concentric with the heating element 5a.
The BSG film 14a is patterned so that the opening that reaches the surface of the BSG film 14a is formed by etching, and the portion to be the opening is removed by etching. Further, a resist film (not shown) is applied on the entire surface, and a planarization process is performed by CMP (chemical mechanical polishing) until the surface of the applied resist film reaches the BSG film 14a. This allows
Only the opening that contains the heating element, that is, the portion that should be the internal volume of the pressure container 14 is filled with the resist evenly. Incidentally, instead of the BSG film 14a,
A SiN film or the like may be used.

The metal film 16 of aluminum or the like is formed on the surface of the BSG film 14a whose openings are filled with the resist as described above. On the other hand, on the back surface side of the insulating base body 3 made of glass, a concave portion 3a is formed at this position by machining so that the thickness of the insulating base body 3 at a position immediately below the heating element 5a becomes 50 μm. Recess 3a
The minimum width of is the outer diameter of the heating element 5a.

Next, laser beam processing is used to obtain a diameter 10 from the back surface side of the insulating substrate 3 at the center of the heating element 5a.
The ink supply hole 4a of μm is opened, and similarly, the metal film 16
An ink ejection hole 7 having a diameter of 20 μm is opened from the side. After that, the resist remaining inside the opening of the BSG film 14a is dissolved and discharged to form the pressure vessel 14.

The ink discharge nozzles 7 are arranged in a staggered pattern. The pitch of each row of the ink ejection nozzles 7 is 8
The printer head of 600 dpi is formed by forming the printer head with 0 μm and by displacing the relative position of the ink discharge nozzle between adjacent columns by 40 μm. Similarly, it is needless to say that if the relative positions of the ink discharge nozzles are shifted with a cycle of three rows or more, a printer head with higher definition can be formed.

Finally, the plastic ink container 2 is adhered to the back surface of the insulating substrate 3 to fill the ink in the ink container 2. Each heating element 5a on the insulating base 3 is connected to a shift register IC (not shown) mounted on the insulating base via a metal wiring 13 (see FIG. 9), and a printer via a signal terminal (not shown). Driver of main body (not shown), CP
U, connected to a power source, etc.

<Embodiment 2> Next, a printer head manufactured by modifying a part of the manufacturing process in Embodiment 1 will be described with reference to FIG.

The heating element 5a and the insulating film 11 on the insulating substrate 3
The formation and patterning of the heat conductive film 15 are performed in the same manner as in the first embodiment. Then, the recess 3a on the back surface side and the ink supply hole 4a (processed by a laser beam or the like) are formed in the insulating substrate 3. On the other hand, a cover plate 17 made of glass or heat resistant resin is prepared.
Then, a cylindrical recess to be the pressure vessel 14 is formed by molding or the like, and the ink discharge nozzle 7 is formed by laser beam processing or the like. And adhesive 1
The printer head is completed by adhering the insulating substrate 3 processed as described above to the cover plate 17 by using No. 8 and further attaching the ink container 2. In addition to the laser beam processing described above, reactive ion etching (RIE) using a metal mask or photoexcited dry etching may be used for processing the ink supply hole 4a or the ink discharge nozzle 7.

<Embodiment 3> In the printer head according to the present invention, the shape of the linear heating element provided on the insulating substrate is not limited to the above-mentioned single ring shape. For example,
As shown in FIGS. 3 (a) to 3 (d), various shapes such as a concentric multiple ring shape, a concentric multiple square shape, a radial ring shape, and a serpentine shape can be used. Whichever shape you choose
It can be easily formed by using the photolithography technique. Further, the line width of the heating element is, for example, 10 μm in the above-described first embodiment, which is sufficiently reproducible according to the design rule of 3 μm. In any case, it is preferable that the ink discharge nozzle 7 is located above the center of the heating region of the heating element.

<Embodiment 4> As shown in FIG. 4, the ink supply hole 4a can be provided outside the heating region of the heating element 5a. In this case, it is preferable that the pressure container 14 has a two-circle connection shape to minimize the size of the pressurizing space for the ink.

<Embodiment 5> The shape of the pressure vessel 14 is not limited to a cylindrical shape, but may be, for example, a taper shape that expands toward the insulating substrate 3 side and narrows toward the ink discharge nozzle 7 side. FIG. 5 shows a printer head having a pressure container 14 having such a tapered inner wall 19. This printer head has the same procedure as in the second embodiment.
However, it can be easily realized by forming the recess in the cover plate 17 so as to have the tapered inner wall 19.

<Embodiment 6> The printer head shown in FIG. 6 is the same as the printer head described in Embodiment 2 except that the thickness of the cover plate 17 is increased and the surface of the cover plate 17 on the recording medium 20 side is grooved. 17a is formed and this groove 17a is formed.
The recording medium 20 is brought into close contact with a flat surface other than the above, and the recording medium 20 is moved in a direction perpendicular to the longitudinal direction of the groove 17a so as to keep the distance between the recording medium 20 and the ink discharge nozzle 7 constant. It is a thing. The ink discharge nozzle 7 is
The opening is formed on the bottom surface of the groove 17a. If the cover plate 17 is processed by molding, the pressure vessel 1
It is also possible to simultaneously process and form the recess and the groove 17a corresponding to No. 4 on the front and back surfaces of the cover plate 17.

In this printer head, the flying distance of the ink (that is, the distance between the ink discharge nozzle 7 and the surface of the recording medium 20) can be defined by the depth of the groove 17a. The shape at the time of collision with the recording medium can be made constant. In addition, since the flight space of the ink droplet 8 is closed by the cover plate 17 and the recording medium 20, it is possible to prevent the flight direction from being disturbed due to a disturbance factor such as an air flow, and to increase the definition of the printer head. Effective for transferring and printing minute ink droplets.

[0053]

As described above, according to the present invention, the ink supply hole for communicating the ink container and the pressure container (ink heating container) with each other for the heating element of each dot at a position which is substantially the central region of the heating element. By providing the insulating substrate,
Even if a conventional heating element material is used, the interval between adjacent print dots can be made minute, and a small and high-definition printer head can be manufactured at low cost. Further, by using the linear heating element, it is possible to obtain a heating element having a high electric resistance without making the film thickness of the heating element extremely thin, so that it is possible to reduce the power consumption of the printer head. It becomes possible to realize a portable printer that can operate for a long time by reducing the power supply load of the main body. In addition, the present invention also has an effect that, in high-definition printing, it is possible to eliminate turbulence due to disturbance such as air flow and control the shape of flying ink droplets.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing a cross-sectional structure of a printer head according to a first embodiment.

FIG. 2 is a diagram illustrating a manufacturing process of a printer head according to a second embodiment.

3 (a) to 3 (d) are plan views showing the shapes of linear heating elements.

FIG. 4 is a diagram illustrating positions of ink supply holes in a printer head according to a fourth embodiment.

FIG. 5 is a partially cutaway perspective view showing a printer head having a tapered pressure container.

FIG. 6 is a partially cutaway perspective view showing a cross-sectional structure of a printer head according to a sixth embodiment.

FIG. 7 is a partially cutaway perspective view illustrating a sectional structure of a conventional side shoot type printer head.

FIG. 8 is a partially cutaway perspective view illustrating a sectional structure of a conventional edge shoot type printer head.

FIG. 9 is a perspective view illustrating a basic structure of an ink supply hole and a ring-shaped heating element.

10A and 10B are diagrams illustrating the behavior of ink in a pressure container, in which FIG. 10A is a sectional view illustrating heating and FIG. 10B is a sectional view illustrating cooling.

[Explanation of symbols]

 1 Printer Head 2 Ink Container 3 Insulating Substrate 4,4a Ink Supply Pipe 5,5a Heating Element 6 Ink Heating Container 7 Ink Discharging Nozzle 8 Ink Drop 9 Bubble 9 Insulation Film 12 Ink 13 Wiring 14 Pressure Vessel 15 Thermal Conductive Film 16 Metal film 17 Cover plate 18 Adhesive 19 Inner wall 20 Recording medium

Claims (13)

[Claims] 1. An ink discharge nozzle having an insulating substrate and a plurality of heating elements arranged on the insulating substrate, the heating element heating ink in a liquid phase to vaporize and expand the ink. In a printer head that ejects ink to perform recording, a pressure container that is provided for each heating element, has the heating element on an inner wall surface, forms the ink discharge nozzle as a through hole, and holds a fixed amount of the ink. An ink supply for each of the heating elements, which communicates with an ink container provided in the central portion of a heating region by the heating element and which communicates with the ink container and opens through the insulating substrate to supply the ink to a corresponding pressure container. A printer head having a hole. 2. The printer according to claim 1, wherein the plurality of pressure vessels are integrally formed, and adjacent pressure vessels share a partition wall that isolates the thermal expansion pressure of the ink due to the heating of the heating element from each other. head. 3. A linear electric resistance heating element, which is heated by energization, is bent in a predetermined pattern, and an electrode for supplying electric power for resistance heating from an external power supply source; 3. The printer head according to claim 1, wherein wiring is connected to both ends of the heating element, and the surface of the heating element is covered with an electrically insulating layer. 4. The printer head according to claim 3, wherein a heat conductive film is provided on the electrical insulating layer so as to open the ink supply hole and cover the entire heating region of the heating element. 5. The ink container is formed on a surface of the insulating substrate on which the heating element is not provided, and the insulating substrate forms at least a part of a wall of the ink container. The printer head according to item. 6. The printer head according to claim 1, wherein the heating element has a ring shape having a missing portion, and the ink supply hole is opened at the center of the ring. 7. The heating element according to claim 1, wherein the heating element has a substantially ring shape having a continuous concentric folded multi-layered structure or a meandering structure, and the ink supply hole is opened at the center of the ring. Printer head as described. 8. The heating element has a substantially rectangular shape having a continuous concentric rectangular folded multiple structure or a meandering structure, and the ink supply hole is opened at the center of the rectangular shape. The printer head described in 1. 9. The printer head according to claim 1, wherein the opening diameter of the ink discharge nozzle is substantially the same as or larger than the opening diameter of the ink supply hole. 10. A recess is formed on the back surface side of the region of the insulating base where the heating element and the ink supply hole are formed so that the insulating base is thinner than other regions. The printer head according to any one of claims 1 to 9, wherein: 11. The printer head according to claim 1, wherein a wall of a portion of the wall of the pressure container including the ink ejection nozzle is made of metal. 12. The pressure container is provided with an inner wall having a tapered structure that narrows from the side of the insulating substrate toward the ink discharge nozzle.
The printer head according to item. 13. The printer head according to claim 1, wherein a groove is formed on an outer wall surface of the pressure container, and the ink discharge nozzle is opened on a bottom surface of the groove.