JPH06126975A - Ink jet printer - Google Patents

Abstract

PURPOSE:To provide an ink jet printer, inexpensive and of high reliability, for preventing the clogging by a simple mechanism and filling ink simply and quickly. CONSTITUTION:An ink passage 22 communicating with all sections from an ink feed section 2a through a nozzle 2b is formed on the upper face of a passage base 1, and the upper face of the passage 2 is sealed by cementing a vibration plate 3. Temperature detecing liquid absorbing resin 4 such as polyvinyl methyl ether is bonded on the bottom of the ink passage 2, and ink is filled in the state of absoring ink 5 at the transition temperature or under. Spaces are formed on the sectional area of the passage of the temperature detecing liquid absorbing resin 4 in the contacting and discharging state to flow the ink 5, while ink is infiltrated into the temperature detecting liquid absorbing resin 4 to swell and occupy the whole of the sectional area of the passage and form the state of sealing the nozzle 2b in the swelling and absorbing state. A piezoelectric element 6 for pressurizing the ink 5 and jetting ink drops out of the nozzle 2b, a heater 7 for controlling the temperature of the temperature detecting liquid absorbing resin 4 and a temperature, sensor 8 for sensing the temperature are stuck on the upper face of the vibration plate 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer for ejecting and recording ink droplets by an on-demand system or a bubble system.

[0002]

2. Description of the Related Art A conventional on-demand type ink jet printer has a plurality of nozzles, a common ink chamber, and an ink flow path connecting the nozzle and the common ink chamber. A pressurizing chamber is provided in the, and a piezoelectric element is arranged on the pressurizing chamber. Then, a voltage is applied to the piezoelectric element to deform the pressure chamber to pressurize the ink, and the pressure causes ink droplets to be ejected from the nozzle.

Further, in a conventional printer using the bubble jet system, a heating element is arranged in place of the above piezoelectric element. Then, a part of the ink in the ink flow path is heated by the heating element to generate minute bubbles in the ink, the ink is pressurized by the bubbles, and the pressure causes ink droplets to be ejected from the nozzles.

In any of the ink jet printers, in order to fill the ink flow path with ink, to prevent or remove clogging of nozzles, to remove minute dust and air bubbles mixed in the ink flow path, etc. A complicated mechanism such as a pump and a cap is provided as a cleaning mechanism.

[0005]

In any of the above ink jet printers, since the ink is always in contact with the air in the nozzle portion, the viscosity increases due to the drying of the ink and clogging due to the adherence of paper dust on the recording paper. In addition, air bubbles may be mixed in from the ink supply unit side or the nozzle unit. Due to the clogging and the inclusion of air bubbles, it becomes impossible to eject ink droplets, which is a serious problem. Further, since the cleaning mechanism and the nozzle protection mechanism are provided, there is a problem that the apparatus becomes large and the cost increases.

Further, when the ink in the ink flow path is pressurized, in order to reduce the backflow of the ink and not to affect the other flow paths, the ink which is commonly used with the pressurizing chamber is commonly used. A portion (restriction) with a reduced flow passage cross-sectional area is provided between the chamber and the chamber. However, if the cross-sectional area of the restriction is too small, the viscous resistance of the flow path will increase,
It takes too much time to refill the ink after the ink is ejected, and the printing speed is reduced, so that precision is required for manufacturing. In addition, since a large force is required for initial filling and cleaning, a large ink suction pump is required.

SUMMARY OF THE INVENTION An object of the present invention is to provide an inexpensive and highly reliable ink jet printer which prevents clogging with a simple mechanism and enables simple and quick ink filling.

[0008]

In order to achieve the above-mentioned object, an ink jet printer of the present invention comprises a nozzle for ejecting ink droplets, an ink flow path for communicating the nozzle with an ink supply section, and an ink flow path for the ink flow path. Placed at least in part,
The temperature-sensitive liquid absorbing resin that swells and absorbs below the transition temperature, and contracts and drains when exceeding the transition temperature, and is absorbed by the temperature-sensitive liquid absorbing resin below the transition temperature It is provided with an ink filled therein, a discharging means for discharging the ink from a nozzle, and a heating means for heating the temperature-sensitive liquid absorbing resin above the transition temperature.

The above-mentioned temperature-sensitive liquid absorbing resin may be arranged in the entire ink flow path or in the nozzle portion of the ink flow path.

A piezoelectric element or a heating element may be used as the above-mentioned ejection means.

Further, a temperature detector for detecting the temperature in the ink flow path may be provided.

[0012]

The temperature-sensitive liquid absorbing resin is used in at least a part of the ink flow path. In an operating environment below a predetermined transition temperature, the liquid is confined in a network structure of polymer (polymer) to the outside. It is a resin that makes it difficult to discharge to the outside, but in the operating environment exceeding the transition temperature, on the contrary, the polymer contracts and discharges the liquid trapped in the network structure to the outside. Unlike a resin such as a sponge or felt that sucks a liquid into a physical inner space, this resin absorbs and drains a liquid at a molecular level. Therefore, the resin volume increases in the liquid absorbing state, and the resin volume decreases in the liquid discharging state.
The volume reversibly changes depending on the state. Examples of the temperature-sensitive liquid absorbing resin include polyvinyl methyl ether, methyl cellulose, polyethylene oxide, etc. For example, in the case of polyvinyl methyl ether gel, it is known that the transition temperature at which the state changes is 37 ° C., and 37 ° C. Below, it will be in a swollen / liquid absorbing state, and above 37 ° C will be in a contracted / drained state.

When this temperature-sensitive liquid absorbing resin is used in the ink flow path, the resin occupies only a part of the cross section of the flow path when the ink is in the contracted / drained state.
In the swollen and liquid-absorbing state, the resin absorbs the ink and swells, occupies the entire cross section of the flow channel, and becomes a state in which the flow channel is plugged, and the ink becomes difficult to flow. Further, in this state, since the ink is incorporated in the temperature-sensitive liquid absorbing resin at the molecular level, the ink is in a very stable state against external changes.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. As shown in FIG. 1A, an ink channel 2 is formed on the upper surface of a channel substrate 1 made of glass or the like by etching or the like. The ink flow path 2 communicates from the ink supply unit 2a to the plurality of nozzle units 2b. A pressure chamber 2c is provided in a part of the ink flow path 2,
A restriction 2d is formed between the pressure chamber 2c and the ink supply unit 2a. A vibration plate 3 is bonded to the surface of the flow path substrate 1 on which the ink flow path 2 is formed, and seals the upper surface of the ink flow path 2.

In filling the ink in the ink flow path 2, in the present invention, the ink is filled in the temperature-sensitive liquid absorbing resin. That is, the ink supply unit 2a
To the entire bottom of the ink flow path 2 from the nozzle portion 2b to
A temperature-sensitive liquid absorbing resin 4 such as polyvinyl methyl ether is adhered. In the contracted / drained state, the temperature-sensitive liquid absorbing resin 4 does not block the ink flow path 2 and creates a space in the cross-sectional area of the flow path so that the ink 5 can flow, as shown in FIG. As shown in FIG. 1B, the upper half of the nozzle portion 2b is filled with the liquid ink 5. In the swollen and liquid-absorbing state, as shown in FIG. 2 (a), the ink is taken into the temperature-sensitive liquid absorbing resin 4 and swells to occupy the entire cross-sectional area of the flow path, as shown in FIG. 2 (b). As described above, the nozzle portion 2b is like a plug.

Since the temperature-sensitive liquid absorbing resin 4 has a large liquid absorbing property in a swollen and liquid absorbing state, it absorbs ink from the ink supply portion 2a without using an external pump or the like, and the nozzle 2b.
Can be reached and the entire flow path can be filled. Further, even when air bubbles are mixed in the flow path, it is possible to remove the air bubbles by swelling the temperature-sensitive liquid absorbing resin 4.

A piezoelectric element 6, which is a pressurizing means for pressurizing the ink 5 to eject an ink droplet from the nozzle 2b, is attached to a position on the upper surface of the vibrating plate 3 facing the pressure chamber 2c. Further, a heater 7 for controlling the temperature of the temperature-sensitive liquid absorbing resin 4 and a temperature detector 8 for detecting this temperature are provided at a position facing the flow path 2 on the upper surface of the vibration plate 3. There is.

In the non-operating state where the printer is not used, the temperature of the temperature-sensitive liquid absorbing resin 4 is controlled by the heater 7 to be below the transition temperature. As a result, the temperature-sensitive liquid absorbing resin 4 is in a swollen and liquid-absorbing state, and the ink 5 is taken into the temperature-sensitive liquid absorbing resin 4 as shown in FIG. 2 and is in a stable storage state.

In an operating state in which the printer is used, the heater 7 raises the temperature of the temperature-sensitive liquid absorbing resin 4 above the transition temperature. As a result, the temperature-sensitive liquid absorbing resin 4 is in a contracted / drained state, and as shown in FIG.
Contracts to reduce its volume, and the ink 5 is discharged into the created space. Therefore, when a recording signal is supplied to the piezoelectric element 6, the piezoelectric element 6 bends according to the signal and presses the diaphragm 3. The vibrating plate 3 pressurizes the ink 5 in the pressurizing chamber 2c, and the pressure causes the ink droplets to be ejected from the nozzle portion 2b.
During the operating state, the temperature detector 8 monitors the temperature of the temperature-sensitive liquid absorbing resin 4, and the heater 7 controls the temperature so that the temperature does not fall below the transition temperature.

When the temperature-sensitive liquid absorbing resin 4 having a transition temperature higher than room temperature is used, the temperature-sensitive liquid absorbing resin 4 naturally swells and absorbs the ink at room temperature when the printer is not operating. Is in a stable storage state without being altered.

FIG. 3 shows another embodiment, in which the temperature-sensitive liquid absorbing resin 14 is arranged only in the nozzle portion 12b in the ink flow passage 12, and in the ink flow passage 12 inside the nozzle portion. The liquid ink 15 is filled as it is.
The heater 17 is arranged on the upper surface of the nozzle portion 12b, and the temperature detector 18 is arranged on the ink flow path 12 behind it.
The other structures are the same as those in the example of FIG. 1, and the same reference numerals are given.

In this embodiment, in the non-operating state, the temperature-sensitive liquid absorbing resin 14 of the nozzle portion 12b is in a swollen and liquid absorbing state to take in the ink, and the nozzle portion 12b is plugged as in FIG. 2 (b). However, the ink 15 in the internal ink flow path 12 is stored in a liquid state. In the operating state, the temperature is raised above the transition temperature by the heater 17 to bring the temperature-sensitive liquid absorbing resin 14 into the contracted / drained state. Therefore, as in FIG. 1B, the upper half of the nozzle portion 12b is liquid ink. 15 is filled, and ink droplets are ejected in the same manner as described above.

The means for ejecting ink droplets is not limited to the above-mentioned piezoelectric element, but may be one that heats and boils ink by a heating element to use it as a pressure source. It may be one that ejects ink droplets, and is applicable to any inkjet printer that uses liquid ink and nozzles.

[0024]

As described above, the ink jet printer of the present invention uses the temperature-sensitive liquid absorbing resin in at least a part of the ink flow path, and the ink becomes the temperature-sensitive liquid absorbing resin below the transition temperature. Since it is not trapped and does not come into contact with air, there is no increase in viscosity at the nozzle part due to drying of ink, clogging due to adhesion of paper dust on recording paper, inclusion of bubbles, etc. Since the ink is discharged and the ink droplets are ejected by heating the ink over that temperature, it is possible to provide an inexpensive and highly reliable printer without causing ejection failure of the ink droplets. Further, in the swollen / liquid absorbing state of the temperature-sensitive liquid absorbing resin, the liquid absorbing property is large, so that the ink can be filled easily and quickly. Moreover, since a clogging prevention mechanism and the like are not required, the structure is simplified and an inexpensive device can be provided.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, (a) is a sectional view of a main part of a temperature-sensitive liquid absorbing resin in a contracted / drained state, and (b) is an enlarged front view of a nozzle part thereof. It is a figure.

FIG. 2 (a) is a cross-sectional view of a main part of the same temperature-sensitive liquid absorbing resin in a swollen / liquid absorbing state, and FIG. 2 (b) is an enlarged front view of a nozzle portion thereof.

FIG. 3 shows another embodiment of the present invention and is a cross-sectional view of a main part of the temperature-sensitive liquid absorbing resin in a contracted / drained state.

[Explanation of symbols]

 2, 12 Ink flow path 2a Ink supply section 2b, 12b Nozzle 4,14 Temperature-sensitive liquid absorbing resin 5,15 Ink 6 Discharging means 7,17 Heating means 8,18 Temperature detector

Front page continuation (72) Inventor Yasunari Kanda 4-1-1 Taihei, Sumida-ku, Tokyo Incorporated in Seikosha Ltd. (72) Inventor Hirokazu Ono 4-1-1 Taihei, Sumida-ku, Tokyo Inside the house (72) Iwao Hirayama 4-1-1 Taihei, Sumida-ku, Tokyo Inside the Seikosha Co., Ltd.

Claims (6)

[Claims] 1. A nozzle for ejecting an ink droplet, an ink flow path communicating between the nozzle and an ink supply unit, and at least a part of the ink flow path, which are in a swelling / liquid absorbing state below a transition temperature. , The temperature-sensitive liquid absorbing resin which contracts and drains when the temperature exceeds the transition temperature, and the ink which is absorbed by the temperature-sensitive liquid absorbing resin at a temperature below the transition temperature and is filled in the ink flow path. An ink jet printer comprising: a discharging unit configured to discharge the ink from the nozzle; and a heating unit configured to heat the temperature-sensitive liquid absorbing resin above the transition temperature. 2. The ink jet printer according to claim 1, wherein the temperature-sensitive liquid absorbing resin is provided in the entire ink flow path. 3. The ink jet printer according to claim 1, wherein the temperature-sensitive liquid absorbing resin is provided in a nozzle portion of the ink flow path. 4. The method according to any one of claims 1 to 3,
An ink jet printer characterized in that the ejection means is a piezoelectric element. 5. The method according to any one of claims 1 to 3,
An inkjet printer, wherein the discharging means is a heating element. 6. The method according to any one of claims 1 to 5,
An ink jet printer comprising a temperature detector for detecting the temperature in the ink flow path.