JPH077168Y2 - Inkjet head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an inkjet head used in an inkjet recording apparatus, and more particularly to an inkjet head suitable for high density recording by integrating nozzles.

[Conventional technology]

In recent years, as a non-impact recording method, an ink jet method has attracted attention because noise during recording is low and high speed recording is possible. The ink jet method is one in which recording is performed by ejecting ink from a nozzle hole provided in a recording head, and a method using a piezoelectric element as the discharging means and one using thermal energy have been proposed. Among these, particularly the method using heat energy can easily integrate nozzles because a large number of ejection means can be formed on the substrate by a film forming technique, and high density and high speed recording can be realized. Is expected as.

The inkjet head of the method using the thermal energy forms a number of heat generating parts corresponding to the number of nozzles on the substrate,
By connecting a common electrode to one of the heat generating parts and connecting an individual electrode to the other, each heat generating part is energized to generate heat and generate bubbles in the ink. Recording is performed by ejecting ink. With such a configuration, it is possible to easily integrate a large number of nozzles as described above. However, when the number of nozzles increases, the number of individual electrodes also increases accordingly, and the number of common electrodes also increases. Since the capacity increases as the number of nozzles increases, the line width of the electrode layer must be increased. Therefore, in addition to the increased number of individual electrodes, the line width of the electrode layer of the common electrode is increased,
There is a problem that the size of the substrate is increased by the area where they are routed, and the head itself is increased accordingly, which makes it impossible to reduce the size of the device. On the other hand, as a method of preventing the substrate from becoming larger than necessary, it has been considered to form the common electrode layer and the individual electrode layer into a multilayer structure.

FIG. 3 and FIG. 4 show the structure of an inkjet head using a substrate having a multi-layer structure of the common electrode and the individual electrode as described above. In the figure, 1 is a substrate made of glass, silicon, alumina or the like, and a partial glaze layer 2 for storing heat is formed on the substrate 1.
The conductive layer 3 of FIG. 1 is formed on top of this, and an undercoat made of silicon oxide, silicon nitride, tantalum oxide, tantalum pentoxide, etc. for heat storage, heat resistance, and interlayer insulation is formed on the conductive layer 3. Layer 4 has been formed.
A heating resistor layer 5 made of tantalum nitride or the like is formed on the undercoat layer 4, and a second conductor layer 6 is formed thereon to form a heating portion 12. Second conductor layer 6
One of them (on the right side in FIG. 4) is a common electrode, which is connected to the first conductor layer 3 through the contact hole 7 and has a multilayer structure. Reference numeral 8 denotes an overcoat layer which is provided on these layers to protect each layer from the influence of onk, and is made of silicon nitride, silicon oxide or the like.

Reference numeral 9 in the drawing denotes a nozzle plate, and a nozzle hole (orifice) 9a for ejecting ink is formed at a position corresponding to the heat generating portion 12. On the lower surface of the nozzle plate 9, partition walls 10, 10 ...
Is formed integrally with or separately from the nozzle plate 9, and the ink jet head is formed by joining the nozzle plate 9 and the substrate at a constant interval through the partition walls 10 ... Reference numeral 11 denotes an ink flow path for supplying ink from an ink tank (not shown) to the nozzle holes, which is formed simultaneously by joining the nozzle plate 9 and the substrate.

[Problems to be solved by the invention]

However, in the ink jet head as described above, a conductor layer made of aluminum or the like exists between the portion of the heating resistor layer that contributes to heat generation and the substrate. Since it is much softer than the material, the undercoat layer on the conductor layer undergoes mechanical deformation due to thermal expansion and contraction each time the heat generating part repeats heat generation-cooling (heat generation cycle) for ink ejection. There is a problem in that the heat generating portion is damaged in a short time due to the impact that is repeated and ink bubbles are generated and disappears, that is, cavitation, and a long-life and highly reliable head cannot be manufactured.

The present invention has been made in view of the above points, and an object of the present invention is to provide an ink jet head having a long life, in which the heat generating portion is not damaged even if ejection is repeated over a long period of time.

[Means for solving problems]

In order to achieve the above object, the present invention provides a nozzle hole for ejecting a recording liquid, a liquid passage communicating with the nozzle hole, and a heating resistor for generating thermal energy for ejecting the liquid. And a substrate having a conductor layer that is electrically connected to the heating resistor layer and that forms a common electrode and an individual electrode, in an inkjet head, a portion of the conductor layer that forms at least the common electrode has a plurality of portions. It is a multi-layer structure composed of layers, and each of these layers is electrically connected to each other by a connecting portion, and the conductor layer is not interposed between the portion of the heating resistor layer that contributes to heat generation and the substrate. Characterize.

[Action]

As described above, according to the ink jet of the present invention, since at least the portion of the conductor layer forming the common electrode has a multi-layer structure and each of these layers is electrically connected to each other by the connecting portion, the wiring The density of the layers can be increased, the wiring capacity can be increased, and since the soft layer of the conductor layer is not interposed between the heat generating portion and the substrate, even if the heat generating portion is driven repeatedly, However, it will not be damaged due to mechanical deformation, generation of bubbles, or cavitation at the time of disappearance.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2. FIG. 1 is a plan view of an inkjet head according to the present invention, and FIG. 2 is a cross-sectional view of the main part thereof.
In the figure, the same parts as those in FIGS. 3 and 4 are designated by the same reference numerals.

In this embodiment, first, a glass paste is printed on the substrate 1 and then baked to form the partial glaze layer 2. Next, a first conductor layer 3 made of aluminum or the like is formed on the partial glaze layer 2 by stuttering or vapor deposition, and then a portion of the conductor layer 3 corresponding to the heat generating portion 12 is removed by etching. Thereafter, an undercoat layer 4 made of silicon oxide, silicon nitride, tantalum oxide, tantalum pentoxide, etc., and a heating resistor layer 5 made of tantalum nitride, etc. are sequentially formed thereon by sputtering or the like, and the contact holes are etched. After drilling 7, the second conductor layer 6 made of aluminum or the like is formed again, and the heat generating portion 12 is formed. At that time, one (the right side in FIG. 2) of the second conductor layer 6 which becomes the common electrode is electrically connected to the first conductor layer 3 through the contact hole 7 and the other (the first electrode of the second conductor layer 6 becomes the individual electrode). The left side in FIG. 2) is routed as it is to form a multilayer wiring. Finally, a protective layer 8 is formed on these layers to form a head substrate, and the nozzle plate 8 is bonded to this substrate to form an inkjet head.

As described above, in this embodiment, since the soft layer such as aluminum is not interposed between the substrate and the heat generating resistor layer in the heat generating portion, the undercoat layer is formed even if the heat cycle of heat generation-cooling is repeated. Is firmly supported on the hard partial glaze layer, so that mechanical deformation does not occur and therefore the heat generating portion is not damaged.

In the above embodiment, the partial glaze layer is formed on the substrate, and then the layers are laminated, but if the substrate is formed of a material capable of imparting a heat storage function to the substrate, it is formed on the substrate. The undercoat layer may be directly formed.

[Effect of device]

As described above in detail, according to the inkjet head of the present invention, at least the portion of the conductor layer that constitutes the common electrode has a multi-layered structure, and these layers are electrically connected to each other by the connecting portion. As a result, it is possible to increase the density of the wiring layer and also increase the capacity of the wiring without increasing the size of the substrate. In addition to being able to drive, the structure does not include a soft conductor layer between the heat generating part and the substrate, so the heat generating part will not be damaged even if the heat generating cycle is repeated, and the head will have a long life and reliability. It is possible to have high quality.

[Brief description of drawings]

1 and 2 are explanatory views showing the structure of an ink jet head according to the present invention. FIG. 1 is a plan view and FIG. 2 is a cross-sectional view of a main part thereof. 3 and 4 are explanatory views showing a conventional ink jet head, FIG. 3 is a plan view, and FIG. 4 is a cross-sectional view of an essential part thereof. 1 ... Substrate, 2 ... Partial glaze layer 3 ... First conductor layer, 4 ... Undercoat layer 5 ... Heating resistor layer, 6 ... Second conductor layer 7 ... Contact hole, 8 ... … Overcoat layer 9 …… Nozzle plate, 10 …… Partition wall, 11 …… Ink flow path 12 …… Heating part

Claims (1)

[Scope of utility model registration request] 1. A nozzle hole for ejecting a recording liquid, a liquid passage communicating with the nozzle hole, a heating resistor layer for generating thermal energy for ejecting the liquid, and the heating resistor layer. An inkjet head comprising: a substrate having a conductor layer that is electrically connected to form a common electrode and an individual electrode; and a multilayer structure in which at least a portion of the conductor layer that forms the common electrode has a plurality of layers, and An ink jet head in which each of these layers is electrically connected to each other by a connecting portion, and the conductor layer is not interposed between a portion of the heating resistor layer that contributes to heat generation and the substrate.