JP2001253075A - Ink jet print head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet print head capable of efficiently discharging a heat of a driving element for driving an energy generating element to the outside. SOLUTION: In the print head 15, a heating element 18 is provided on a chip substrate 16 at one side in the longitudinal direction and an ink supplying groove 25 is formed thereon at the other side. A common ink passage 29 is formed at a portion between the ink supplying groove 25 and the heating element 18, i.e., the portion along the longitudinal direction of the central section on the chip substrate 16. Multiple drivers 17 are arranged just beneath the common ink passage 29 with a driver protection layer 22. The heat of the drivers 17 is absorbed by the ink passing through the common ink passage 29 and is discharged to the outside together with ink drops ejected from an orifice 28.

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 which efficiently discharges heat generated by a driving element for driving an energy generating element to the outside.

[0002]

2. Description of the Related Art Conventionally, ink jet printers have been widely used. Ink jet print heads include a piezo print head having a piezoresistive element (piezoelectric element) as an energy generating element or a thermal print head having a resistive heating element.

[0003] A piezo-type print head ejects ink droplets by deformation of a piezoresistive element, and a thermal type print head ejects ink droplets by the pressure of a film bubble generated by heat generated by a resistance heating element.

In the thermal type, there are two types of configurations depending on the direction in which ink droplets are ejected. One type is a so-called side shooter type in which ink droplets are ejected in a direction parallel to the heating surface of a resistance heating element. The other is called a roof shooter type or a top shooter type in which ink droplets are ejected in a direction perpendicular to the heating surface of the resistance heating element.

FIG. 6A shows a roof shooter type ink jet print head (hereinafter simply referred to as a print head).
FIG. 2 is an exploded perspective view of FIG. 1, showing, from bottom to top, a chip substrate and the shape of each part directly formed on the chip substrate, a partition laminated thereon, and an orifice plate laminated on the top. I have. Also, FIG.
FIG. 3A is a sectional view taken along the line AA ′ of FIG.

[0006] As shown in FIGS.
A number of drivers 3 of a drive circuit are arranged along one long side of the surface of the chip substrate 2. Individual wiring electrodes 4, resistance heating elements 5, and common electrodes 6 are sequentially connected to each driver 3. Between the common electrode 6 and the other long side of the chip substrate 2, an ink supply groove 7 and an ink supply hole 8 communicating with the ink supply groove 7 and penetrating through the back surface of the chip substrate 2 are formed.

[0007] A partition 9 made of photosensitive polyimide is laminated on the driver 3, the individual wiring electrodes 4, between the resistance heating elements 5 and the periphery of the chip substrate 2, and along the periphery of the chip substrate 2. An orifice plate 11 made of a polyimide film is further laminated on the partition wall 9. The orifice plate 11 is provided with an orifice 12 that opens at a position facing the resistance heating element 5.

When the print head 1 performs printing, ink supplied from an external ink tank (not shown) or the like is supplied to the resistance heating element 5 through an ink supply hole 8 and an ink supply groove 7, and the driver 3 As a result, the resistive heating element 5 is selectively driven in accordance with the print information, thereby generating heat, generating film bubbles at the interface with the ink, and discharging the ink from the orifice 12 as ink droplets by the growth pressure of the film bubbles. Let it.

The amount of heat generated by the driver 3 varies depending on the state of ink discharge from the corresponding orifice 12.
That is, the amount of heat generated by the driver 3 and, consequently, the amount of heat generated by the chip substrate 2 change according to the image to be drawn. Normally, when printing all solid images, the amount of heat generated as a whole becomes the largest. In order to prevent the temperature of the driver 3 at that time from exceeding the maximum allowable junction temperature of the driver 3, the driver 3 determines the ink ejection cycle from the orifice 12 and the duty ratio of the drive pulse to be applied to the resistance heating element 5. Are set, and environmental conditions for dissipating the heat of the driver 3 are set.

In this case, the heat generated by the driver 3 is radiated to the outside mainly through the following two radiating paths. One is heat radiation through the partition 9 and the orifice plate 11,
The other is heat radiation through the chip substrate 2.

The thermal conductivity of polyimide as a material forming the partition 9 and the orifice plate 11 is 0.21 (W /
m / ° C.), and the thermal conductivity of silicon as the material of the other chip substrate 2 is 150 (W / m / ° C.). As a result of such heat conduction characteristics, heat generated by the driver 3 is radiated not toward the front surface of the chip substrate 2 on which the partition walls 9 and the orifice plate 11 are provided, but toward the rear surface of the silicon chip substrate 2. The Rukoto.

Therefore, in general, the chip substrate 2 is bonded to a heat radiating plate made of Al or the like (not shown) in consideration of the above as a heat radiating environment of the driver 3, and is connected to the printer through the heat radiating plate. It is connected to the main body of the apparatus or a replaceable ink cartridge. Then, depending on the state of contact with the heat sink, silicone grease or the like is interposed on the joint surface so that the substantial contact area is further increased. As a result, the heat generated by the driver 3 is released to the outside.

[0013]

However, the above-mentioned heat radiating plate requires a considerable area in order to completely radiate the heat generated by the driver. As a result, the size of the printer body has been increased, and therefore, there has been a problem that it has not been possible to cope with the recent market demand for downsizing OA equipment.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances,
An object of the present invention is to provide an ink jet print head that efficiently discharges heat generated by a driving element for driving an energy generating element to the outside.

[0015]

The construction of the ink jet print head according to the present invention will be described below. An ink jet print head according to the present invention includes a plurality of energy generating elements arranged in a predetermined direction on a substrate to generate pressure energy for discharging a liquid, a driving element for driving the energy generating element, and the substrate A partition wall, which is formed on the partition wall to form a pressurizing chamber for applying pressure to the liquid by each energy generating element, an orifice plate provided on the partition wall and having an orifice for ink ejection, and An ink jet printhead having at least a common ink flow path for supplying ink to a pressure chamber, wherein the common ink flow path exchanges heat generated by the driving element with the ink in the common ink flow path. It is arranged and arranged at possible positions.

Further, for example, between the energy supply element and the ink supply groove which communicates the common ink flow path with the common ink flow path and supplies ink from the back side of the substrate. It is formed so as to be located, and the drive element is arranged immediately below the common ink flow path so as to cool the drive element by ink flowing through the common ink flow path.

Further, for example, a hollow portion is provided in at least a hexahedral base body having a pair of opposed flat surfaces and at least four end surfaces, and the hollow portion serves as the common ink flow path. The pressure chamber communicates with the opening of the base so that the plurality of energy generating elements are juxtaposed in the longitudinal direction on one end face having an area smaller than the plane where the hollow of the base opens. The drive element is mounted on at least one of the pair of planes of the base so as to cool the drive element with ink flowing through the common ink flow path.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view showing an internal configuration of a roof shooter type ink jet print head (hereinafter, simply referred to as a print head) according to the first embodiment. Configuration of each part formed directly on, a driver protective film deposited thereon, a partition wall laminated thereon,
And an orifice plate laminated on top.

FIG. 2A is a perspective view showing a partially cut-out part of the completed print head, and FIG. 2B is a perspective view showing the same.
FIG. 4 is an enlarged view taken along a line BB ′ of FIG. These FIGS. 1 and 2
As shown in (a) and (b), the print head 15 has a chip substrate 16 cut out of a silicon wafer (not shown) after completion.
In the first, along the central longitudinal direction of the surface, LSI
A large number of drivers 17 as driving elements formed by the formation processing technique are arranged in parallel.

Along the left long side of the chip substrate 16, for example, Ta
A heating element 18 made of -Si-O or the like is formed by a thin film formation processing technique, and an individual wiring electrode 19 connecting one end of the heating element 18 to the driver 17 and a common end to the other ends of all the heating elements 18 Is formed by, for example, Al, Cu, Au, or the like by the same thin film formation processing technique.

On top of these, for example, a transparent driver protection layer 22 (see FIG. 1) forms a heating portion 22-1 corresponding to the heating element 18 and a groove portion 22- corresponding to an ink supply groove to be formed later. Except for 2, it is applied, for example, by vapor deposition or sputtering.

On top of this, a partition wall 23 made of photosensitive polyimide or the like integrally formed by photolithography and sintering is laminated. The partition 23 is formed by a seal partition 23-1 surrounding the periphery of the chip substrate 16 and a partition 23-2 extending between the heat generating elements 18 described above. These partition walls 23
The ink pressurizing chambers 24 corresponding to the individual heating elements 18 are defined by -2.

An ink supply groove 25 is first formed by a dry etching technique such as sandblasting so as to match the groove portion 22-2 of the driver protection layer 22, and further communicates with the ink supply groove 25 to form the chip substrate 16. An ink supply hole 26 penetrating the back surface is provided.

On the entire upper surface of these, that is, the partition 23
An orifice plate 27 made of a film-like polyimide is laminated on and fixed by an adhesive member. An orifice 28 formed by, for example, a helicon wave etching device is disposed at a position of the orifice plate 27 facing the heating element 18.

The groove portion 22-of the driver protection layer 22 described above.
A common ink flow path 29 having a height corresponding to the height of the partition wall 23 is provided in a portion from the second portion to the heat generating portion 22-1, that is, a portion from the ink supply groove 25 to the heat generating element 18 (see FIGS. 1 and 2B). Are formed. And under this, driver 1
7 are provided.

As described above, the upper portion of the entire area where the driver 17 is formed on the chip substrate 16 over a large area is formed as the common ink flow path 29. Heat is radiated almost directly to the ink in the common ink flow path 29 though it passes therethrough. The ink on the common ink flow path 29 that has absorbed the heat is sequentially supplied to the ink pressurizing chamber 24 and is ejected from the orifice 28 as an ink droplet. As described above, the heat generated by the driver 17 is efficiently discharged to the outside along with the ink droplets without remaining in the head.

The ejection of ink from the orifice 28 causes a flow of ink in the common ink flow path 29, so that low-temperature ink always flows from the ink supply groove 25 and is supplied. That is, the orifice 28 having a larger ink discharge amount, that is, the driver 17 having a larger heat generation amount has a larger ink flow in the common ink flow path 29 thereabove. become able to.

Further, since the heat generated by the driving element is absorbed by the ink flowing before discharging, the temperature of the ink rises enough to lower the viscosity of the ink supplied to the discharging part without the aid of a chip heater or the like. Thus, the ejection speed, that is, the printing speed can be improved with a simple configuration.

The print head 15 shown in FIGS. 1 and 2 (a) and 2 (b) is a print head for mono-color ink having only one nozzle row. The print head 15 having the above configuration is used for black (Bk) ink,
A four-color print head for yellow (Y) ink, magenta (M) ink, and cyan (C) ink is integrated into a full-color print head, and the print heads are arranged in an array to form a long print head. It can be.

FIG. 3 is an exploded perspective view of such a long print head and its peripheral members. The long print head 30 shown in FIG. 3 is configured such that the discharge heads 31 in which the print heads 15 shown in FIG. Die bonding is performed by alternately arranging arrays in a zigzag manner in the direction.

Four groove holes 33, which penetrate vertically through the heat radiating plate 32, are in close contact with the ink supply holes 26 corresponding to the four rows of each color ink located above the drawing of the discharge head 31. And communicate. In each of these four slots 33, four inks corresponding to each color ink, which are formed in a zigzag manner on the lower surface of an ink supply plate 34 which is brought into close contact with the upper surface of the heat radiating plate 32 and are united. The supply paths 35 are in close contact with each other and communicate with each other.

At the end of the ink supply plate 34, an ink pressurizing mechanism 36 is provided. Above the ink pressurizing mechanism 36, an ink tank 38 having four ink chambers 37 corresponding to each color ink is provided. Are engaged portions 39 (39-1, 39-
Engage via 2). The ink is held in each ink chamber 37 in a state where a negative pressure is generated by infiltrating the sponge with the ink.

The engaging portion 39-1 of the ink tank 38
In the drawing, ink supply ports for each color are formed although they are not shaded in the drawing.
At -2, a connection port for each color corresponding to the ink supply port is formed.

The ink impregnated in the sponge in the four ink chambers 37 of the ink tank 38 is
-1, 39-2, sent out to the ink supply path 35 via the ink pressurizing mechanism 36, and further sent to the slot 33, the ink supply hole 26.
Are supplied to the nozzle row of the corresponding color ink of each ejection head 31 (a row of the orifices 28).

Below the long print head 30, a cap mechanism 41 which rises from the retracted position below as necessary and closely contacts the lower surface of the long print head 30 to seal the long print head 30 from the outside. Is arranged. Cap mechanism 41
Is connected to a suction pipe 42 communicating with a vacuum pump (not shown).

The cap mechanism 41 moves upward when the printing operation is stopped, that is, when printing is not being performed, and caps the orifice surface of the long print head 30. When ink is conducted at the beginning of printing, clogging occurs. The orifice which may be inhaled is sucked by the suction pipe 42 so that the ink can be ejected satisfactorily.

When the cap mechanism 41 is at the lower retreat position, a sheet (not shown) is transported between the long print head 30 and the cap mechanism 41. The long print head 30
The sheet is formed to have a length corresponding to the effective printing area in the width direction of the conveyed sheet.

During printing, the heating elements are selectively heated by applying an electric current from an unillustrated individual wiring electrode and a common electrode disposed on the chip substrate surface of each ejection head 31 and a control circuit (not shown). Then, the ink is ejected from the orifice by volume expansion due to a film bubble generated at the interface with the ink.

When the above printing operation is continued, the discharge head 31 gradually generates heat, and the heat is stored in the heat radiating plate 32. However, the radiator plate 32 has an ink supply plate 34
The ink supply path 35 formed by the above is in close contact. As a result, the heat of the heat radiating plate 32 is absorbed by the ink flowing through the ink supply 35, and is discharged to the outside along with the ink droplets subsequently discharged. .

FIG. 4 is an external perspective view showing a long and long head unit provided with a roof shooter type ink jet print head according to the second embodiment.

FIG. 5 (a) is an exploded perspective view showing the structure, and FIG. 5 (b) is a portion indicated by a circle C in FIG. It is an enlarged plan view.
As shown in FIGS. 4 and 5A and 5B, the ink jet print head 45 includes a flat substrate 46. The base 46 is made of, for example, aluminum (Al).
Or aluminum nitride (AlN) or Cu: 90
%, Al: 5%, and Ni: 4.5%, such as aluminum bronze, which has a higher thermal conductivity than silicon and is excellent in heat dissipation, and is made of a material that is less expensive than silicon.

The flat plate-shaped hexahedral base 46 is formed by a pair of large flat surfaces 47-1 and 47-2 (plane 47-
4 and 5 (a) are obliquely left-hand sides and cannot be seen), and four end faces 48-1 and 48-2 (end faces) having an area smaller than these planes 47-1 and 47-2. 48-
4 and 5 (a) are obliquely rightward and invisible, and 49-1 and 49-2 (the end face 49-1 is on the lower side in FIGS. 4 and 5 (a)). Invisible).

At least the upper end surface 49-1 is covered on its entire surface with an insulating layer formed of, for example, SiO ₂ to a thickness of about 1 μm using a thin film forming technique such as sputtering. From the end face 49-1 to the end face 49-2 on the opposite side (the lower side in FIG. 5 (a), which cannot be seen), the central part in the thickness direction of the base body 46 is penetrated.
A rectangular hollow portion having a cross section extending long in the longitudinal direction of the base 46 is formed as the common ink channel 51.

The end face 4 where the common ink flow path 51 opens.
A large number of heating elements 52 are linearly arranged side by side on both sides of 9-1, that is, along both sides in the longitudinal direction of the end face 49-1 from end to end to form two heating element rows. are doing. A common electrode 53 connected to all the heating elements 52 is provided between the opening of the common ink flow path 51 and the two heating element rows. , An individual wiring electrode 54 is provided.

On this, a partition member 55 having both sides formed in a comb tooth shape is provided with a pressure chamber 56 formed between the teeth of the comb.
The heating elements 52 and the individual wiring electrodes 54 are stacked inside. The lower part of the pressurizing chamber 56 formed between the teeth of the comb communicates with the common ink channel 51, and the upper part is later covered with the orifice plate.

Next, the end surface 49-1 of the base 46, the flat surface 47
Orifice plate 5 large enough to cover -1 and 47-2
7 are prepared. An orifice 58 is drilled at a position corresponding to the heating element 52 at the center of the orifice plate 57 in advance or later.

The orifice plate 57 also serves as a flexible printed circuit board, and its back surface 57-1 has
Although not particularly shown, a predetermined printed wiring is patterned. A predetermined number of I
The C bare chip 59 is mounted. IC bare chip 5
Reference numeral 9 denotes a silicon chip, on one side of which a heating element drive circuit is formed by an LSI formation processing technique. The IC bear chip 59 is mounted with the surface on which the drive circuit is formed facing the orifice plate back surface 57-1.

In the flat surfaces 47-1 and 47-2 of the base 46, holes 61 are formed in advance, into which the above-mentioned IC bear chips 59 are just fitted. The above-mentioned orifice plate 57 is attached to the base 4
6 after being attached on the partition member 55 formed on the end surface 49-1 of the base member 4 and bent in a direction perpendicular to the lower side so that the back surface of the base member 4 where the drive circuit of the IC bear chip 59 is not formed is formed.
The IC bear chip 59 is adhered and fixed to the base 46 in a state of being fitted into the holes 61 of the flat surfaces 47-1 and 47-2 and closely contacting the bottom surface of the holes 61.

Under the base 46, a common ink flow path 51 is provided.
An ink holding chamber 62 communicating with a lower opening of the ink holding chamber 62 is integrally attached, and tubes 63 for supplying ink from the outside are connected to both ends of the ink holding chamber 62 in the longitudinal direction. These tubes 63 and 63 constitute an ink supply and circulation path via an ink tank (not shown).

Also in the case of this embodiment, the individual wiring electrodes 5
The heating element 52 is selectively heated by applying a current from the drive circuit of the IC chip 4 and the common electrode 53 and the IC bare chip 59, and the ink is ejected from the orifice 58 by volume expansion due to a film bubble generated at the interface with the ink.

When the above-described printing operation is continued, the drive circuit, that is, the IC bare chip 59 on which the drive circuit is mounted gradually generates heat, and the heat is generated by the flat surface 47- 1 and 47-2
The heat is stored.

However, the back surfaces of the flat surfaces 47-1 and 47-2 of the base 46 form the common ink flow path 51. As a result, the heat of the flat surfaces 47-1 and 47-2 is absorbed by the ink flowing through the common ink flow path 51, and the ink having absorbed the heat is discharged to the outside from the orifice 58, so that the heat generation of the drive circuit is always generated. Common ink channel 5
The ink will flow out of the ink jet print head 45 via the ink flowing through 1 and therefore the drive circuit will not overheat above the allowable temperature.

In the above embodiment, the shape of the base 46 was described as a hexahedron. However, the shape of the base 46 is not limited to this shape. It may have a variable speed shape. For example, in a shape with one corner cut out, 7
The shape is a cuboid, and the shape in which two corners are cut out results in an octahedron, but the above embodiment can be applied to such a shape.

[0054]

As described above in detail, according to the present invention, the flowing ink is driven close to the entire surface of the silicon chip substrate or the hollow substrate surface. Since the common ink flow path is formed so as to be heat-exchangeable with the elements, the ink flowing through the common ink flow path and ejected to the outside can absorb the heat generated by the driving elements, thereby further reducing the heat radiation of the print head. It can be performed efficiently.

Further, since the heat generated by the driving element is absorbed by the ink flowing before ejection, the temperature rise of the ink is sufficient to lower the viscosity of the ink supplied to the ejection portion without the aid of a chip heater or the like. As a result, it is possible to improve the ejection speed, that is, the printing speed, with a simple configuration.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view illustrating an internal configuration of an inkjet print head according to a first embodiment.

FIG. 2 (a) is a perspective view showing a partially cut-out finished product of the ink jet print head according to the first embodiment, and FIG. 2 (b) is an enlarged view taken along the line BB 'of FIG. .

FIG. 3 is an exploded perspective view of a long print head in which the inkjet print head according to the first embodiment has a full-color configuration and is further arranged in a staggered array, and peripheral members thereof.

FIG. 4 is an external perspective view showing the inkjet print head according to the second embodiment with a part cut away.

FIG. 5A is an exploded perspective view of an ink jet print head according to a second embodiment, and FIG. 5B is an enlarged plan view of a portion indicated by a circle C in FIG.

6 (a) is an exploded perspective view of a conventional ink jet print head, and FIG. 6 (b) is a sectional view taken along line AA 'of FIG. 6 (a).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Print head 2 Chip board 3 Driver 4 Individual wiring electrode 5 Resistance heating element 6 Common electrode 7 Ink supply groove 8 Ink supply hole 9 Partition wall 11 Orifice plate 12 Orifice 15 Print head 16 Chip substrate 17 Driver 18 Heating element 19 Individual wiring electrode 21 Common electrode 22 Driver protective layer 22-1 Heat generating portion 22-2 Groove portion 23 Partition 23-1 Seal partition 23-2 Partition partition 24 Ink pressurizing chamber 25 Ink supply groove 26 Ink supply hole 27 Orifice plate 28 Orifice 29 Common Ink flow path 30 Long print head 31 Discharge head 32 Heat sink 33 Slot hole 34 Ink supply plate 35 Ink supply path 36 Ink pressurizing mechanism 37 Ink chamber 38 Ink tank 39 Engagement part 41 Cap mechanism 42 Suction pipe 45 Inkjet printing Head 46 Base 47-1, 47-2 Plane 48-1, 48-2, 49-1, 49-2 End face 51 Common ink channel 52 Heating element 53 Common electrode 54 Individual wiring electrode 55 Partition member 56 Pressure chamber 57 Orifice plate 57-1 Back surface of orifice plate 58 Orifice 59 IC bare chip 61 Hole 62 Ink holding chamber 63 Tube

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Naohiro Osugi 3-2-1 Sakaemachi, Hamura-shi, Tokyo Casio Computer Co., Ltd. Hamura Technical Center F-term (reference) 2C057 AF25 AF34 AF99 AG12 AG46 AG83 BA04 BA05 BA13

Claims (3)

[Claims] 1. A plurality of energy generating elements arranged in a predetermined direction on a substrate for generating pressure energy for discharging a liquid, a driving element for driving the energy generating elements, and a standing element on the substrate. A partition wall for forming a pressurized chamber for applying pressure to the liquid by each energy generating element, an orifice plate provided with an orifice for ink ejection provided to overlap with the partition wall, and the pressurized chamber. An ink-jet printhead having at least a common ink flow path for supplying ink, wherein the common ink flow path is a position at which ink in the common ink flow path can exchange heat generated by the driving element. An ink-jet printhead, which is arranged in 2. The method according to claim 1, wherein the common ink flow path communicates with the common ink flow path, and is formed between an ink supply groove for supplying ink from the back side of the substrate and the energy generating element. 2. The ink-jet printhead according to claim 1, wherein the drive element is disposed immediately below the common ink flow path so as to cool the drive element by ink flowing through the ink flow path. 3. A hollow portion is provided in at least a hexahedral base body comprising a pair of opposed flat surfaces and at least four end surfaces, the hollow portion being the common ink flow path, and the hollow portion of the base body being open. 1 smaller in area than plane
On one end face, the substrate is mounted such that the plurality of energy generating elements are arranged side by side in the longitudinal direction, and the pressure chamber and the hollow portion opening of the base communicate with each other, and the ink flowing through the common ink flow path 2. The ink-jet printhead according to claim 1, wherein the drive element is disposed in close contact with at least one of the pair of planes of the base to cool the drive element.