JPS63151459A - Liquid jet recording head - Google Patents

Abstract

PURPOSE:To perform gradation recording of a sufficient step, by controlling the expanding operation of a flexible film to a flow passage by changing the quantity of heat energy supplied to the air in an air chamber and making the quantity of an emitted liquid droplet changeable. CONSTITUTION:When a liquid 4 is abruptly heated by the first heat generator 1, air bubbles 5 are generated in said liquid 4 and the liquid 4 is extruded from an orifice S by the pressure of said air bubbles 5 to form a liquid droplet 7. Now, when the air in an air chamber 9 is heated by the second heat generator 11 in synchronous relation to the heat generator 1 immediately before the liquid 4 is extruded, a flexible membrane 10 expands on the side of a flow passage 3 by the expansion of air and the quantity of the emitted liquid droplet 7 changes by the change of the fluid resistance in the flow passage 3. That is, the expansion degree of the air in the air chamber 9 is changed by changing the voltage applied to the second heat generator 1 for controlling gradation and the size of the emitted liquid droplet 7 is changed by changing the expansion degree of the membrane 10 and fine gradation recording can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid jet recording head, and in particular, the present invention relates to a liquid jet recording head, and in particular, it generates bubbles in a liquid using thermal energy and causes bubbles to fly from an orifice.
The present invention relates to a recording head for a liquid jet recording device that performs recording by ejecting target droplets.

[Prior Art] Conventionally, as liquid jet recording devices for printing and image recording, there are devices that eject droplets by deforming a nozzle using a piezoelectric element, and devices that generate air bubbles in ink liquid using thermal energy generating means placed inside the nozzle. Generally, methods are widely known in which droplets are ejected by the liquid pressure generated as the bubbles grow.

However, recording devices using the latter method can be manufactured by stacking a large number of nozzles at high density.
It is characterized by high density and high speed recording.

However, liquid jet recording devices that use thermal energy utilize the change in volume that occurs during the process from the generation to the disappearance of bubbles, so it is possible to reliably eject droplets in accordance with the recording signal. However, it has been difficult to precisely control the amount of droplets to be ejected over a wide range in multiple stages.

Accordingly, a system has been developed and put into practical use in which a plurality of thermal energy generating bodies are arranged for one orifice and gradation recording can be obtained by driving them individually or in combination.

However, in order to obtain gradation recording by arranging multiple thermal energy generating bodies in this way, due to manufacturing constraints, it is necessary to arrange a certain number of thermal energy generating bodies according to the gradation stage. However, the arrangement of the nozzles within the liquid path has to be determined, and it has been difficult to realize a recording head capable of recording gradations of 3 to 4 gradations or more.

[Problems to be Solved by the Invention] In view of the above-mentioned problems, it is an object of the present invention to provide a liquid jet recording head that solves the problems and enables recording of sufficient levels of gradation. .

[Means for Solving the Problems] In order to achieve the above object, the present invention supplies energy to the recording liquid in the flow path by means of an energy generation means provided in the flow path of the nozzle, so that droplets or the like can be generated from the orifice. In a liquid jet recording head that performs recording by ejecting liquid, there is a flexible film provided on the wall of the flow path, an air chamber separated from the flow path by the flexible film, and thermal energy that supplies thermal energy to the gas in the air chamber. A generating means and a means for controlling an electric signal applied to the thermal energy generating means are provided, and the control means changes the amount of thermal energy supplied to the gas in the air chamber to cause expansion of the flexible membrane into the flow path. It is characterized by controlling the ejecting operation and making it possible to change the amount of droplets ejected.

[Function] According to the liquid jet recording head of the present invention, the energy generating section generates air bubbles in the flow path, and at the same time, the flexible film provided in the flow path absorbs the liquid droplets that are about to be ejected from the orifice due to the air bubbles. By changing the degree of bulge toward the channel side, it is now possible to control gradation recording over a wide range of areas.

[Examples] Examples of the present invention will be described below in detail and specifically based on the drawings.

FIG. 1 shows an example of the basic configuration of the present invention, and here, a single nozzle is shown as opposed to the plurality of nozzles that are generally arranged. 1 is a first heating element formed on the substrate body 2, which is formed along the flow path 3 and can heat the liquid 4 filled in the flow path 3 to generate bubbles 5; The bubble 5 can cause the formed droplet 7 to be ejected from the orifice 6.

Reference numeral 8 denotes a cover plate having, for example, a silicon plate as a base. N.M.
On the MB2 side, an air chamber 9 is recessed along the flow path 3 on the downstream side of the first heating element 1, and a flexible thin film 10 is provided facing the flow path 3 of the air chamber 9. The space between the air chamber 9 and the channel 3 is kept airtight and liquid-tight by the membrane IO. 11 is a second heating element disposed in the air chamber 9.

In the liquid jet recording head configured as described above, when the liquid 4 is rapidly heated by the first heating element 1, air bubbles 5 are generated therein, and the liquid 4 is pushed out from the orifice 6 by the pressure of the liquid 4, forming droplets 7. is formed. However, just before the liquid 4 is pushed out, the second
When the gas in the air chamber 9 is heated by the heating element 11, the flexible thin film 1O bulges toward the flow path 3 as shown in this figure due to the expansion of the gas, causing a change in fluid resistance in the flow path 3. Accordingly, the amount of droplets 7 to be ejected changes.

That is, by changing the voltage applied to the second heating element 11 for gradation control, the degree of expansion of the gas in the air chamber 9 is changed, and by changing the degree of expansion of the thin film 10. By changing the size of the ejected droplets 7, fine gradation recording can be performed.

FIG. 2 shows an embodiment of the liquid jet recording head of the present invention. Reference numeral 21 denotes a silicon substrate, on which a silica (5i(h) layer 22 is formed as a lower layer to a thickness of several μm by sputtering, and then a heat generating resistor layer 11 is formed on top of the silica (5i(h) layer 22 using hafnium boride HfB2). The electrode layer 12 was similarly laminated with aluminum AJ2 to a thickness of 3000 mm, and then the heating element 1 was formed by selective etching.
A protective layer 14 having a thickness of 5 μm was formed.

On the other hand, in the MMMB2, a silica layer 82 is formed on a silicon substrate 81, an air chamber 9 is formed in a part of the silica layer 82, and a heating resistor layer 111 and an electrode are formed on the bottom of the air chamber 9 by the same method as described above. A second heating element 11 was formed by laminating layers 112. Additionally, a top plate 83 formed of photosensitive resin or the like may be used.
A window is provided at a position corresponding to the air chamber 9, a flexible thin film 10 is adhered to this window, and the top plate 8 is attached to the 5i02 layer 82 described above.
3, a recording head as shown in FIG. 1 can be obtained.

In the liquid jet recording head configured as described above, when a pulse signal is supplied to the ejection electrode formed by the electrode layer 12, bubbles are generated due to a rapid rise in the temperature of the first heating element 1. This occurs near the heating limit of the liquid, and is not affected much by the magnitude of the pulse signal, and its magnitude is almost constant.

Therefore, if only the first heating element 1 is energized without energizing the second heating element 11 for gradation control, the air bubbles 5 are generated, as shown in FIG. 38, and the fluid resistance is at its lowest. Droplets 78 are ejected, but when a control voltage is now supplied to the second heating element 11, the gas in the air chamber 9 thermally expands, causing the thin film 10 to protrude into the flow path 3. Since the fluid resistance in the flow path 3 on the downstream side of the generated bubbles 5 is increased, the droplets 7B are formed small as shown in FIG. 3B and are ejected.

Therefore, by changing the voltage signal supplied to the second heating element 11, the ejection amount of the thin film 10 is changed, and the above-mentioned fluid resistance is changed accordingly to change the size of the ejected droplet, thereby changing the gradation level. Records can be made.

In addition, in the above explanation, the case where the second heating element is provided between the first heating element and the orifice has been described, but the present invention is not limited to this, and the second heating element is provided immediately before the orifice or the first heating element. Alternatively, the air chamber 9 may be provided on the upstream side of the air chamber 9. Of course, it is also possible to provide the thin film 10 and the second heating element 11 not only on a part of the wall surface of the channel 3, but also in an annular shape, for example, along the circumferential direction of the channel 3. In short, it is sufficient if a means is provided along the flow path so as to change the fluid resistance of the liquid to be discharged within the flow path.

Further, the present invention can be similarly applied to a recording head having a single nozzle or a recording head having a plurality of nozzles arranged in an array. Needless to say, it can also be applied.

[Effects of the Invention] As explained above, according to the present invention, liquid jet recording is performed in which droplets are ejected by generating bubbles in the recording liquid in the flow path by the energy generating means provided in the flow path of the nozzle. The head is provided with a flexible membrane provided in a part of the flow path, an air chamber separated from the flow path by the flexible membrane, and thermal energy generation means for heating the gas in the air chamber. By changing the signal applied to the means, the degree of gas expansion is changed, and by deforming the flexible membrane according to the degree, the fluid resistance during ejection is changed, so the amount of droplets ejected can be changed. It has become possible to change the gradation in various ways, and it has become possible to record gradations with a sufficient control range.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of the structure of the liquid jet recording head of the present invention, FIG. 2 is a sectional view showing details of the structure, and FIG. FIG. 7 is a cross-sectional view illustrating a state in which the droplet appearance changes when droplets are ejected without heating and when droplets are ejected with a heat generation signal supplied. DESCRIPTION OF SYMBOLS 1... First heating element, 3... Channel, 4... Fluid, 5... Air bubble, 6... Orifice, 7.7A, 7B... Droplet, 9... Air Chamber IO...Flexible thin film 11...Second heating element. 2nd figure

Claims (1)

[Scope of Claims] A liquid jet recording head that performs recording by supplying energy to the recording liquid in the flow path by energy generating means provided in the flow path of a nozzle to eject droplets from an orifice, comprising: a flexible membrane provided on the wall of the air chamber; an air chamber isolated from the flow path by the flexible membrane; a thermal energy generating means for supplying thermal energy to the gas in the air chamber; means for controlling an electrical signal to control the gas in the gas chamber, and the control means controls the expansion operation of the flexible membrane into the flow path by changing the amount of thermal energy supplied to the gas in the gas chamber, and the gas is discharged. A liquid jet recording head characterized in that the amount of liquid droplets can be changed.