JPS6237163A - Droplet ejector - Google Patents

Abstract

PURPOSE:To prevent an ejecting port from being clogged and contrive a longer service life, by providing a pressurizing chamber partitioned from a small liquid chamber by an elastic member, storing an electrically insulating volatile liquid in the pressurizing chamber, and providing an evaporator for evaporating the liquid. CONSTITUTION:An electrically insulating volatile liquid 17 is stored in the pressurizing chamber 15, a heating element 18 as an evaporator is disposed in the state of being shielded by a protective film 19, and the heating element 18 generates heat when an pulse of voltage is applied to the heating element 18 from a heating power source 20. Based on the heat generation, the liquid 17 in the chamber 15 is evaporated with the result of volume expansion, whereby a diaphragm 16 is pushed upward, and a pulse of pressure is transmitted to the small liquid chamber 11. By the pulse of pressure, an appropriate amount of an ink 14 contained in the chamber 11 is ejected through the ejecting port 11a.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to an inkjet printer, and more particularly to a droplet ejection device that ejects ink.

(Prior Art) Conventionally, as shown in FIG. 7, in this type of droplet ejection device, a heating element 3 is provided on the wall surface of a pressurizing chamber 2 filled with ink supplied from a liquid reservoir 1, and the heating element 3 is installed on the wall of a pressurizing chamber 2 filled with ink supplied from a liquid reservoir 1. There is one in which a portion of the ink is rapidly vaporized by the heat generated by the heat generated by the element 3, and the ink is ejected using the resulting pressure.

(Problem to be Solved by the Invention) However, in this droplet ejecting device, the heating element 3 is exposed in the ink flow path, so if the ink contains pigment, etc., it repeatedly vaporizes due to heat. Over time, the pigment and the like solidify and accumulate around the heating element 3, causing clogging of the discharge port and shortening the life of the droplet discharge device.

SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide a droplet ejection device that prevents clogging of the ejection port and has a long life.

(Structure of the Invention (Means for Solving Problems)) In order to achieve the above object, the present invention provides an elastic member for a liquid chamber which is provided with a discharge port and whose liquid supply side is connected to a liquid reservoir. The gist is a droplet ejecting device that has a partitioned pressurized chamber, stores an electrically insulating and volatile liquid in the pressurized chamber, and is equipped with a vaporizer that vaporizes the liquid. be.

(Function) When the vaporizer vaporizes the electrically insulating and volatile liquid in the pressurizing chamber, volumetric expansion occurs, and the liquid chamber is pressurized via the elastic member due to the volumetric expansion. Based on this pressurization, the liquid in the liquid chamber is discharged from the discharge port.

Further, since the pressurizing chamber is partitioned from the liquid chamber by an elastic member, the liquid in the liquid chamber does not directly touch the vaporizer.

(Example) An example embodying the present invention will be described below with reference to the drawings.

In FIG. 1, a small liquid chamber 11 is supplied with ink 14 as a liquid from a liquid reservoir 13 via a connecting pipe 12. A pressurizing chamber 15 is formed on the lower surface of the liquid chamber 11, and the pressurizing chamber 15 is hermetically isolated from the liquid chamber 11 by a rubber diaphragm 16 as an elastic member.

The pressurized chamber 15 contains an electrically insulating and volatile liquid 1.
7 is stored, and a heating element 18 as a vaporizer
is arranged in a state where it is shielded by a protective film 19, and the heating element 18 generates heat by applying a pulse voltage from a heating power source 20 to the heating element 18.

Based on this heat generation, the liquid 17 in the pressurizing chamber 15 is vaporized and a volume of 1 is generated, and due to the volume expansion, the diaphragm 1
6 upward to transmit the same pulse pressure to the liquid chamber 11. This pulse pressure causes an appropriate amount of the ink 14 in the small liquid chamber 11 to be ejected from the ejection port 11a.

Then, when the heating power source 20 is turned off and the heat generation stops,
As the heat generated in the pressurizing chamber 15 diffuses throughout the apparatus, the temperature within the pressurizing chamber 15 decreases, and the previously vaporized gas liquefies again. As a result, the pressure inside the pressurizing chamber 15 decreases, and the diaphragm 16, which had been pushed upward, returns to its original state and generates the next generation of heat. Based on the return of the diaphragm 16, the pressure inside the small liquid chamber 11 decreases, and this pressure decrease causes the discharge hole 11a to decrease.
The ink 14 is replenished from the liquid reservoir 13 by the amount of ink discharged from the ink.

In this embodiment, by controlling the amplitude and duration of the pulse voltage from the heating power source 20, the liquid chamber 1 is heated.
The magnitude and duration of the pressure transmitted to 1, i.e.
The amount and ejection speed of the ink 14 to be ejected can be controlled.

A check valve 21 is disposed on the liquid replenishment passage 11b on the base end replenishment side of the liquid small chamber 11. The check valve 21 is a disc 2 having a plurality of holes 22 formed therein as shown in FIGS. 2 and 3.
3, and the hole 22 is formed in a tapered shape so that the inner diameter thereof becomes wider toward the liquid reservoir 13 side. Therefore, due to the pressure loss characteristics of the ink 14 flowing through the hole 22 of the disk 23, the ink in the liquid reservoir 13 smoothly flows toward the liquid chamber 11, and conversely, the ink 14 in the liquid chamber 11 flows toward the liquid reservoir 13. It becomes difficult.

As a result, part of the pulse pressure transmitted to the small liquid chamber 111 tends to become a force that causes part of the ink 14 in the small liquid chamber 11 to flow back toward the liquid reservoir 13, but the check valve 21 restricts backflow, all of the energy is consumed for ink ejection.

On the contrary, the ink 1 from the liquid reservoir 13 to the liquid chamber 11 when the diaphragm 16 returns to its original state.
4 will be resupplied smoothly.

In this way, in this example, the pressurization chamber 15 was filled with an electrically insulating and volatile liquid, so that the volume expansion due to vaporization of the liquid is very large, so even a weak heating energy is sufficient. It is possible to generate a large amount of pressure, keep power consumption low, and also reduce the
can be made smaller.

Further, the pressurizing chamber 15 has a diaphragm 16 with respect to the liquid chamber 11.
Since the heating element 18 is sealed and isolated in order to prevent it from coming into contact with the ink 14, this can shorten the life of the droplet ejecting device when the ink 14 contains pigments, etc., as in the conventional case. There is no risk that the pigment or the like will be solidified due to the exothermic vaporization, and the life of the droplet ejecting device will not be shortened.

Moreover, in this embodiment, since the check valve 21 is provided between the small liquid chamber 11 and the liquid reservoir 13, the ink 14 will not flow back toward the liquid reservoir 13, and the pressure applied to the small liquid chamber 11 will be reduced. Since all of the energy is consumed for discharge, the discharge amount relative to the pressure applied to the liquid chamber 11,
The ejection speed can be easily determined, and the ejection amount, ejection speed, etc. of the ink 14 can be easily controlled.

Furthermore, in this embodiment, the diaphragm 16 is made of rubber, so when a print head is constructed by combining a large number of droplet discharge devices, the diaphragm 16 in one droplet discharge device
The vibration of 6 is not transmitted to other droplet ejection devices adjacent to each other, and there is no risk that the ink 14 filled in the small liquid chamber 11 of the other droplet ejection device will ooze out from the ejection port 11a due to the vibration.

In addition, in this embodiment, two discs 23 are installed together to form the check valve 21.
However, the present invention is not limited to this, and the number of sheets may be increased or decreased as appropriate.

In this case, when the number of sheets is increased, backflow of the ink 14 can be more effectively prevented.

Further, the check valve 21 may be implemented in place of the check valve 21 shown in FIGS. 4 and 5. This check valve 21 includes a circular valve seat 24 having a plurality of through holes 24a therethrough, and each of the through holes 2.
It is composed of an annular thin plate valve body 25 formed by extending a lead part 25a that closes one side of the valve body 4a toward the center, and is arranged so that the valve seat 24 is on the liquid reservoir 13 side. When the ink 14 flows from the valve seat 24 side, that is, from the liquid reservoir 13 side to the liquid chamber 11 side, the ink 14 flowing through the through hole 24a of the valve seat 24 is transferred to the lead portion 2 of the thin plate valve body 25.
5a floats up and easily flows to the liquid chamber 11 side.

On the other hand, the ink 14 on the liquid chamber 11 side is connected to the lead portion 25a.
Since the through hole 24a of the valve seat 24 is closed, the liquid reservoir 1
It will not flow to the third side.

Alternatively, as shown in FIG. 6, a cooling body 31 may be disposed below the heating element 18 in the pressurizing chamber 15.

The cooling body 31 is an electronic cooling body that applies the Beltier effect, and when the heating element 18 is generating heat, that is, when the heating element 18 is generating heat,
1! so that it does not operate when voltage is applied from 32, and operates for cooling when the heating element 18 is at rest! source 3
The drive is controlled so that a voltage is applied from 2 to 2.

In this case, the heat generated by the heating element 18 is transferred to the cooling element 31.
Since the gas is forcibly cooled, the vaporized gas is quickly liquefied, and the heat generating operation for the next pressurization can be performed quickly, making it possible to create a droplet ejecting device with a constant driving speed.

In the above embodiment, the electrically insulating and volatile liquid 17 was vaporized using the heating element 18 that generates heat electrically, but the present invention is not limited to this. Anything that vaporizes is fine. Therefore, for example, by disposing discharge electrodes in the pressurizing chamber 15 and causing discharge between the discharge electrodes, the heat generated by the discharge is used to make the liquid 17
may be vaporized.

Effects of the Invention As detailed above, according to the present invention, a pressurized chamber partitioned by an elastic member is provided for a small liquid chamber which is provided with a discharge port and whose liquid supply side is connected to a liquid reservoir. The pressurized chamber stores an electrically insulating and volatile liquid and is equipped with a vaporizer that vaporizes the liquid, which prevents clogging of the discharge port and extends the life of the droplet discharge device. have an effect.

[Brief explanation of drawings]

Fig. 1 is a side sectional view of a droplet discharge device embodying the present invention, Fig. 2 is a front view of the check valve, Fig. 3 is a side sectional view of the same check valve, and Fig. 4 is a side sectional view of the check valve. FIG. 5 is a side sectional view of the same check valve, FIG. 6 is a side sectional view showing another example of the droplet discharge device of the present invention, and FIG. 7 is a conventional droplet discharge device. FIG. 2 is a cross-sectional view of the device. In the figure, 11 is a small liquid chamber, 11a is a discharge port, 13 is a liquid reservoir, 14 is ink, 15 is a pressurizing chamber, 16 is a diaphragm, 17 is a liquid, 18 is a heating element, 20 is a heating power source, and 21 is a non-return check. The valve 31 is a cooling body. Patent applicant: Toyoda Automatic Machinery Co., Ltd.
Hide Be 3rd Patent Attorney On 1) Hironobu Figure 1 Figure 7

Claims (1)

[Claims] 1. A pressurized chamber partitioned by an elastic member is provided for a small liquid chamber that is equipped with a discharge port and whose liquid supply side is connected to a liquid reservoir, and the pressurized chamber is electrically insulated. A droplet ejection device that stores a volatile and volatile liquid and is equipped with a vaporizer that vaporizes the liquid. 2. The droplet ejecting device according to claim 1, wherein the vaporizer is a heating element. 3. The droplet ejecting device according to claim 2, wherein the heating element is shielded with a protective film. 4. The droplet discharge device according to claim 1, wherein a check valve is provided on the liquid supply side of the liquid chamber.