JPH06336028A - Ink delivery device - Google Patents

Abstract

PURPOSE:To obtain superior productivity and durability and to perfectly prevent a counterflow of ink to an ink supply tube. CONSTITUTION:In an ink delivery device melting ink in a solid state at an ordinary temperature and delivering the ink out of a delivery nozzle 6 by a delivery force application means 5, a thermally controllable heating element 2 is provided in an ink supply tube 1 supplying liquid ink to the delivery nozzle 6, and a heat release element 3 is provided near the heating element 2. When liquid ink is delivered out of the delivery nozzle 6 by the delivery force application means 5, the heat generation of the heating element 2 is brought to a stop or controlled to a temperature lower than the melting point of the ink, and the heat is released outside through the heat release element 3. In this manner, the liquid ink is set to close the ink supply tube 1 to prevent a counterflow of ink. On the other hand, when ink is replenished to the ink delivery tube 6 through the ink supply tube 1, the heating element 2 is heated to a temperature higher than the melting point of the ink to melt the solid ink, thereby allowing the ink to flow forward.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink ejection device for printing or image recording. More specifically, the present invention relates to an ink ejection device that melts ink in a solid state at room temperature and ejects the ink from an ejection nozzle by an ejection force applying unit.

[0002]

2. Description of the Related Art As an ink ejecting device of a type for ejecting ink using an ejecting force applying means, conventionally, a charge control (multi-value deflection) type ink jet, a drop-on-demand (Kaiser) type ink jet, a bubble jet type ink jet, Examples include a multi-orifice head. This type of ink ejecting device supplies molten ink to the ink ejecting nozzle side through an ink supply pipe, and ejecting force is applied to the ink by ejecting force applying means such as a piezo element in the vicinity of the ejecting nozzle. It is configured to discharge. The ejected ink is solidified at room temperature and fixed on paper or the like.

However, in such an ink ejecting device, an ejecting force is applied to the ink, and at the same time, a force for causing the ink to flow backward is applied to the ink supply pipe side. When a backflow occurs on the ink supply pipe side, a proper ink ejection pressure cannot be obtained, and problems occur such that the ink is not ejected at all, or an amount less than a predetermined amount is ejected.

Therefore, each of the ink jet heads of this type requires a backflow prevention means in the ink supply pipe portion between the ejection force applying means near the ejection nozzle and the ink supply source (tank). For example, as shown in FIG. 8, the barrier plate 1 for narrowing the ink flow rate in the ink supply pipe 101
04 is provided so as to become a resistance against the pressure (ejection pressure) instantaneously applied by the ejection force imparting means 103 and reduce the reverse flow rate (Japanese Patent Publication No. 54-1).
9294). Further, as shown in FIG. 9, a backflow prevention rectification is provided to the ink supply pipe 101 side of the pressure chamber 204 formed between the ink discharge nozzle 202 and the ink supply pipe 201 by the piezo element (ejection force applying means) 203. Valve 2
05 is provided, and the fluid resistance element 206 is provided on the ink ejection nozzle 202 side. According to this backflow prevention mechanism, the backflow at the time of ink ejection is completely prevented by the rectifying valve 205, and the backflow from the ink ejection nozzle 202 side at the time of ink supply due to the restoration of the piezo element 203 is suppressed by the fluid resistance element 206. There is.

[0005]

However, according to the partition plate 104 as shown in FIG. 8, the backflow cannot be completely prevented, and a part of the partition plate 104 is backflowed.
There is also a problem that the partition plate 104 becomes a resistance when ink is supplied to the ink ejection nozzle 102 side. Further, although the use of the rectification valve 105 as shown in FIG. 9 can completely prevent the backflow, the formation of such a microvalve in the ink supply pipe 101 complicates the structure, and thus the productivity is increased. It is inferior and there is a problem that durability is inferior because it has a mechanical operating part.

It is an object of the present invention to provide an ink ejection device which is excellent in productivity and durability and which can completely prevent ink backflow to the ink supply pipe.

[0007]

In order to achieve the above object, the present invention provides a liquefied ink in an ink ejecting apparatus that melts an ink in a solid state at room temperature and ejects the liquefied ink from an ejection nozzle by an ejection force applying means. A temperature controllable heating element provided in the ink supply tube for supplying the ink to the ejection nozzle side, and a heat radiating element provided in the vicinity of the heating element,
When the ink is ejected, the ink in the ink supply pipe is solidified and closed by cooling by the radiator, and when the ink is supplied to the ejection nozzle side, the heating element is heated to melt the solidified ink in the ink supply pipe. Are distributed.

[0008]

Therefore, when the ink is ejected from the ink ejection nozzle by the ejection force imparting means, the heat generation of the heat generating element is stopped or the temperature is controlled to be lower than the melting point of the ink so that the heat is released from the heat radiating element to the outside. After solidifying, the inside of the ink supply pipe is blocked with a block of ink and plugged. The solid ink blocking the ink supply pipe prevents the ink from flowing back to the ink supply pipe due to the discharge pressure when the ink is discharged. On the other hand, when replenishing the ink to the ink ejection nozzle side through the ink supply pipe, the heating element is heated to a temperature higher than the melting point of the ink to melt the ink, and the ink block that has blocked the ink supply pipe is completely removed. Alternatively, at least the surface portion is redissolved to allow the ink to flow.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described in detail below with reference to the embodiments shown in the drawings.

1 to 5 show an embodiment of the ink ejection device of the present invention. This ink ejection device is provided with an ink supply tube 1
A heating element 2 provided in the ink supply tube 1, a radiator 3 provided in the vicinity of the heating element 2, and a head that accommodates the ink supplied from the ink supply tube 1 and has a variable volume. The head 4 includes a portion 4, an ejection force imparting means 5 such as a piezo element for imparting an ejection force to the liquid ink 10r contained in the head portion 4, and one ink ejection nozzle 6 provided in the head portion 4. Has been done.

The heating element 2 is made of a conductive metal such as tungsten (W). The heating element 2 is provided on the inner peripheral surface of a tubular radiator 3 connected to the ink supply tube 1 in this embodiment. The heating element 2 is preferably provided so that the inner peripheral surface of the heating element 2 is formed into a rough surface and solidifies to solidify the ink 10s.
The radiator 3 is formed of a material having excellent thermal conductivity, such as an aluminum alloy or alumina ceramics. Further, heat insulating layers 7 and 7 are interposed at the boundary between the heat radiator 3 having the heat generating element 2 formed on the inner peripheral surface thereof and the ink supply tube 1, and the heat generating element 2 and the heat radiator 3 are heated from the ink supply tube 1. It is provided so that the ink is solidified and redissolved only in a portion surrounded by the heat generating element 2 and the heat radiating element 3 by being blocked. The heat generating element 2 and the heat radiating element 3 constitute a thermal valve 8 for selectively liquefying or solidifying the ink to open / close the ink supply tube 1. The thermal valve 8 is preferably installed in the vicinity of the head section 4, and opens and closes the ink supply tube 1 to minimize backflow from the head section 4 without delaying ink supply. Heating element 2 and ejection force applying means 5
Is controlled by a suitable control means such as a microcomputer (not shown) with a certain relationship, and is turned on / off according to the timing of ink supply or ink ejection.
It is designed to be FF controlled.

A pressure chamber 9 is formed in the head portion 4 to change the inner volume by a recess for storing ink and the ejection force applying means 5.
Are formed. The inside of the pressure chamber 9 is constantly heated by, for example, a heater (not shown) formed on the bottom surface or the like to keep the liquid ink 10r in a molten state. Even in the ink supply pipe 1, the ink is always kept at the melting point or higher due to the heat retaining effect of the pipe.

A piezo element is used as the ejection force applying means 5 in the present embodiment, but it is not particularly limited to this, and a bubble is generated in the ink by a pressurizing means such as an ultrasonic element or a vibrating element or by heating. It may be a bubble type to generate or other pressure generating means.

The ink ejecting apparatus constructed as described above performs the ink ejecting operation as follows.

FIG. 1 shows a discharge applying means 5 composed of a piezo element.
When the pressure chamber 9 is distorted as shown in FIG. 5, an ejection force is applied to the liquid ink 10r in the pressure chamber 9, and the liquid ink 10r is ejected from the ink ejection nozzle 6. On the other hand, the pressure applied by the ejection force applying means 5 applies a pressure to the ink in the pressure chamber 9 so that the ink flows back to the ink supply pipe 1 side. However, at the time of this ink ejection, as shown in FIG. 2, the heat generating element 2 is turned off to stop the heat generation, and the heat of the ink in the ink supply tube 1 escapes to the outside air via the heat radiating element 3. Part of the ink is solidified and adheres to the inner peripheral surface of the heating element 2. Then, the ink supply pipe 1 is closed by the solid ink 10s that is solidified at the thermal valve 8 portion, and the reverse flow of the ink in the direction of the arrow A is completely prevented, and at the same time, the ink ejection nozzle 6 (see FIG. 1) ejects the ink. The power is appropriate.

Next, after the ink is ejected, the ejection force applying means 5 is distorted toward the outside of the pressure chamber 9 as shown in FIG. 3, and the liquid ink 10r is replenished into the head portion 4 from the ink supply pipe 1 side. . At this time, before the ejection force applying means 5 is distorted, the heating element 2 is turned on and generates heat above the melting point of the ink, and the solid ink 10s inside the heating element 2 is heated and redissolved. Therefore, the ink supply pipe 1 has returned to a state in which it can flow, and ink is replenished to the pressure chamber 9 of the ink tank 4 shown in FIG. 3 via the ink supply pipe 1.

Although the solid ink 10s is entirely melted as shown in FIG. 4 in this embodiment, it is not always necessary to melt the solid ink 10s.
That is, as shown in FIG.
If only the surface layer of 0 is dissolved, the solid ink 10s is separated from the heating element 2 and the ink supply pipe 1, so that the liquid ink 10r can flow through by pushing the solid ink 10s. The solid ink 10s is swept away by the liquid ink 10r and enters the pressure chamber 9 shown in FIG. 9, but there is no problem because it is melted by the heater in the pressure chamber 9 and a large amount of the liquid ink 10r. When the ink is solidified inside the heating element 2, it is sufficient to melt the surface of the solid ink 10s by heat generation for a short time, so that faster response can be realized. For example, the surface of the solid ink 10s can be melted by about 0.3 μm by energizing for about 0.2 ms. As a result, the solid ink 10s is transferred to the pressure chamber 9
Easily flows to the side.

6 and 7 show another embodiment of the ink discharge device of the present invention. This ink ejection device is of a multi-nozzle type in which a plurality of ink ejection nozzles 6 are provided, and heat is generated in the ink supply pipe 1 of such a multi-nozzle type ink ejection device as in the embodiment shown in FIG. Body 2
A heat valve 8 including a heat radiator 3 is provided.

Further, in the case of the ink ejection device of this embodiment,
A heating element 11 is provided for each of the ink ejection nozzles 6, and the temperature of the heating element 11 is selectively controlled to selectively remelt and eject the solidified ink mass inside the heating element 11. It is provided in. On the other hand, the head unit 4, the ejection force applying unit 5, and the ink supply pipe 1 are common to all the ink ejection nozzles 6.

Therefore, by selectively turning on / off the predetermined heating element 11 according to the control information input to the head, the heated ink discharge nozzle 6 and the unheated ink discharge nozzle 6 are selected. When the ejection force applying means 5 is distorted in the head portion 4, ink is ejected from the heated ink ejection nozzle 6 as shown in FIG. 7A, but as shown in FIG. 7B. The ink is not ejected because the ink is solidified and blocked at the ink ejection nozzle 6 that is not heated. The operation of the ejection force imparting means 5 and the temperature control of the heating element 2 of the thermal valve 8 are performed at the same timing, and the ink supply pipe 1 is opened and closed as in the case of the single nozzle embodiment of FIG. .

The above embodiment is one example of the preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiments, the heating element 2 is
Although N / OFF control is performed, HIGH / LOW control may be performed at a temperature at which the solid ink 10 can be melted or at a temperature lower than that. Further, the heat radiator 3 and the heat generator 2 are formed in a tubular shape similar to the ink supply pipe 1, but are not particularly limited thereto, and may be radially embedded so as to penetrate the ink supply pipe 1 in the radial direction. . Further, the radiator 3 and the heating element 2 are formed by piercing a large number of holes corresponding to the number of discharge nozzles in the plate-shaped radiator 3 made of ceramic or the like having conductive metal films formed on both sides thereof. The film-shaped heating element 2 may be formed on the surface. In this case, the ink supply pipes 1 are connected to the plate-shaped radiator 3, respectively.

[0022]

As is apparent from the above description, in the ink ejection device of the present invention, the temperature controllable heating element provided in the ink supply tube for supplying the ink to the ejection nozzle side and the vicinity of this heating element. A heat radiator provided in the heat sink is controlled to stop the heat generation of the heat generating element at the time of ink ejection or to control the temperature below the melting point of the ink, and the heat is released from the heat radiator to solidify the ink and supply the solidified ink. The solid ink that adheres to the inner surface of the tube and blocks this ink supply tube prevents backflow of the ink to the ink supply tube, while at the time of replenishing the ink to the ink discharge tube side, set the heating element above the melting point of the ink. Since it heats up to melt the ink and allows the ink to flow, it has a simple structure and is superior in terms of productivity. It also has excellent durability with no mechanical operating parts, and ink backflow to the ink supply pipe. It can be completely prevented.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an ink ejection state of an embodiment of an ink ejection device of the present invention.

FIG. 2 is an enlarged view of a heat valve portion in a closed state.

FIG. 3 is a vertical cross-sectional view showing an ink supply state of the ink discharge device of FIG.

FIG. 4 is an enlarged view of a thermal valve portion in a communication state of FIG.

FIG. 5 is an enlarged view showing an ink replenishment state in the case where the re-dissolution of the solid ink in the heat valve portion is not complete.

FIG. 6 is a vertical cross-sectional view showing another embodiment of the ink ejection device of the present invention.

7A and 7B are enlarged cross-sectional views of the ink ejection nozzle portion of the ink ejection device of FIG. 6, where FIG. 7A is a state in which the nozzle is opened and ink is ejected, and FIG. 7B is a state in which the nozzle is blocked and ink is not ejected. Indicates.

FIG. 8 is a principle view of an ink backflow prevention device in a conventional ink ejection device using a barrier plate.

FIG. 9 is a principle diagram of an ink backflow prevention device in a conventional ink ejection device using a rectifying valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink supply pipe 2 Heating element 3 Radiator 4 Head section 5 Ejection force applying means 6 Ink ejection nozzle 8 Thermal valve

Claims (1)

[Claims] 1. A temperature provided in an ink supply pipe for supplying liquefied ink to the ejection nozzle side in an ink ejection device that melts ink in a solid state at room temperature and ejects the ink from an ejection nozzle by ejection force applying means. A controllable heating element and a radiator provided in the vicinity of the heating element are provided, and when ink is ejected, the ink in the ink supply tube is solidified and blocked by cooling by the radiator and ink is ejected to the ejection nozzle side. When supplying the ink, the ink discharge device is characterized in that the heating element is caused to generate heat to melt the solidified ink in the ink supply pipe to circulate the ink.