JPH11254676A - Ink jet head and ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent ink jet performance from deteriorating by providing a channel member with a part for heating the region of a member relating to a plurality of channels touching the channel member thereby moderating temperature variation of a head. SOLUTION: The ink jet head comprises a nozzle 10 formed at a thin part 111, a nozzle plate 11 arranged with electrodes 14a, 14b on the opposite sides of the thin part, a cavity plate 12, and a wiring plate 13. Since ink is jetted utilizing pressure oscillation of ink, viscosity of ink has a significant effect on the in jet performance especially at the time of low temperature when the viscosity increases significantly. In order to moderate increase of viscosity at the time of low temperature, temperature of ink is raised in the pressure chamber by providing a heating part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ink jet head in an ink jet printer.

[0002]

2. Description of the Related Art A conventional bubble jet head has been used as an ink jet head of an ink jet printer.
This is a structure having a heater in the ink flow path for each nozzle that discharges ink. The heater is intended to vaporize ink by heat generated by the heater, generate bubbles, and eject ink by pushing out ink in a flow path from a nozzle. In the bubble jet head, ink is repeatedly ejected by generation of air bubbles due to heat generated by a heater for each nozzle and shrinkage due to heat radiation, but efficient heat radiation is required in order to repeatedly eject at high speed.

[0003]

In an ink jet head, changes in physical properties such as ink viscosity, surface tension, density, etc., and thermal expansion, pressure changes, etc., of the ink, depend on the environmental temperature around the head and the temperature of the head itself. In addition, there has been a problem that the ink ejection performance changes and printing and image expression deteriorate.

The present invention is intended to alleviate the above-mentioned temperature change and prevent the ink discharge performance from deteriorating.

[0005]

Means for Solving the Problems The present invention has solved the above-mentioned problems by means listed below.

(1) A heat-generating portion is provided in the flow path member of the ink jet head for heating regions of the flow path member relating to a plurality of flow paths in contact with the flow path member.

(2) The heat generating portion is formed integrally with the flow path member.

(3) The flow path member is provided with a temperature detecting means.

(4) The heating section is heated in accordance with the temperature detected by the temperature detecting means, and the temperature of the flow path member is maintained substantially at a set temperature.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings. FIG. 1 is an outline view of the ink jet head. In this ink jet head, the nozzle 10 is formed in the thin portion 111, and the electrode a14a is provided on one side of the thin portion and the electrode b14 is provided on the other side.
It is composed of a nozzle plate 11 in which b is formed, a cavity plate 12, and a wiring board 13.

In the present embodiment, the nozzle plate 11 is an example of the flow path member.

FIG. 2 is a sectional view taken in the direction of arrow 15 in FIG. A pressure chamber 16 is formed in the cavity plate 12, one of which is connected to the nozzle 10 and the other is connected to the supply port 17, and a vibrating plate 18 is integrally formed in another of the pressure chambers. The cavity plate 12 and the vibration plate 18 are conductors whose surfaces are covered with an insulator.

The vibrating plate 18 is bent by the electrostatic attraction force generated by the voltage applied to the electrode 19 and the vibrating plate 18, and the bending is restored when the application of the voltage is stopped. Pressure vibration occurs in the ink flowing into the ink 16. Due to the pressure oscillation, the nozzle 10
The ink is further extruded and the ink droplet 20 is ejected.

As described above, in the ink jet head, the ink is ejected by utilizing the pressure vibration of the ink, so that the viscosity of the ink has a great influence on the ejection.
In particular, the increase in the viscosity of the ink at a low temperature is more remarkable than at a high temperature, and has a large effect on the ejection performance. A feature of the present invention resides in that a heat generating portion for increasing the temperature of the ink in the pressure chamber is provided for the purpose of alleviating an increase in ink viscosity at a low temperature.

Next, the heating section will be described in detail with reference to FIG. FIG. 3 is an explanatory view showing only the nozzle plate 11. As shown in FIG. 3A, the nozzle plate 11
Is the thickness C of the thin portion, which is thinner than the thickness B of the nozzle plate.
Is formed, for example, by etching so as to have a thin portion length A. As shown in FIG. 3B, the nozzles 10 are formed in the thin portion 111 in a row.

When the nozzle plate 11 thus constructed is made of, for example, silicon single crystal, it has a resistance value corresponding to the specific resistance value inherent to the material, so that the resistance value of the thin portion 111 is larger than that of the other portions. In particular, the heat generating portion 112 around the portion where the nozzle 10 is formed has a larger resistance value.

The electrode 14 provided on such a nozzle plate 11
When a potential difference is applied to a and b, a current flows between the electrodes, and the nozzle plate generates heat according to the resistance value.

If a silicon single crystal plate having a specific resistance of 10 Ωcm or more is used as a material for the nozzle plate, the thickness B of the nozzle plate is set to 0.1.
When the thickness is 15 mm or more and the thickness C of the thin portion is 0.08 mm or less, the heat generating portion 112 can efficiently generate heat.

When a material having a small specific resistance or an insulator is used as the material of the nozzle plate 11, the nozzle plate 11
A thin film of a high-resistance material is formed on the surface of the substrate, and the thin film can be used as a heating element. An example is tantalum nitride.

As shown in FIG. 2, a pressure chamber 16 is provided below the heating section 112, and the heat generated in the heating section 112 can heat the ink in the pressure chamber 16.

Next, the control procedure will be described with reference to FIG.
The outside air temperature for the ink jet head is mainly the temperature inside the housing of the ink jet printer, and particularly the air temperature near the ink jet head. Therefore, the outside air temperature is substantially equal to the temperature of the ink supplied to the inkjet head. The head temperature is the temperature of the inkjet head itself, that is, the temperature near the heat generating portion 112. The head temperature is detected by a temperature detecting means 21 provided on the nozzle plate 11 shown in FIG. As the temperature detecting means 21, for example, a thermistor is suitable.

The temperature detecting means 21 can detect the temperature by providing it on another member constituting the pressure chamber other than the nozzle plate 11, but it is preferable to provide the temperature detecting means 21 on a member having a heat generating portion from the viewpoint of detection accuracy. desirable.

At the initial stage of starting the printer, the outside air temperature and the head temperature are substantially equal. This temperature is detected by the temperature detecting means 21, and the predetermined temperature is compared with the detected temperature by the temperature comparing means. If the detected temperature is lower than the predetermined temperature, a predetermined current is applied between the electrodes 14a and 14b by the heating part driving means. sink,
Generate heat from the heat generating part. As a result of causing the heat generating portion to generate heat, the temperature of the ink in the nozzle plate 11 and the ink in the pressure chamber 16 rises and approaches the predetermined temperature.

That is, the ink in the pressure chamber 16 which was lower than the predetermined temperature at the initial stage of starting the printer is heated to the predetermined temperature.
The viscosity of the ink is reduced, and the decrease in the ink ejection performance due to the high viscosity of the ink can be alleviated.

The temperature comparing means and the heating section driving means may be provided on other members of the ink jet printer in addition to the ink jet head of the present invention.

[0026]

By providing the heat generating portion of the present invention, an increase in the viscosity of the ink at a low temperature can be mitigated.
The printing quality in a low-temperature environment can be improved.

Since the heat generating portion is formed integrally with the nozzle plate, the heat generating portion can be provided without adding components, that is, without increasing the cost.

Since the temperature of the ink in the pressure chamber can be accurately detected by providing the temperature detecting means on the nozzle plate integrated with the heat generating portion, the printing quality can be maintained with high accuracy.

In addition, by controlling the ink temperature to a predetermined temperature, an ink jet printer which could not be used below 0 ° C. can be used up to about −7 ° C. which is the freezing point of the ink according to the present invention. it can. This has the effect of expanding the possibilities of using the ink jet printer outdoors or in a car.

[Brief description of the drawings]

FIG. 1 is an explanatory view of the outline of an ink jet head of the present invention.

FIG. 2 is an explanatory sectional view of an inkjet head according to the present invention.

FIG. 3 is an explanatory view of a heat generating portion according to the present invention.

FIG. 4 is an explanatory diagram of a control procedure according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Nozzle 11 Nozzle plate 111 Thin part 12 Cavity plate 13 Wiring board 14a Electrode a 14b Electrode b 15 Arrow 16 Pressure chamber 17 Supply port 18 Vibration plate 19 Electrode 20 Ink droplet 21 Temperature detecting means A Thin part length B Nozzle plate thickness C Thin part thickness D Thin part width

Claims (4)

[Claims] An ink jet head used in an ink jet printer is provided with a heat generating portion for heating a region of the flow path member related to a plurality of flow paths in contact with the flow path member in a flow path member having a plurality of nozzles. An ink jet head, characterized in that: 2. In an ink jet head used in an ink jet printer, an area of the flow path member, which is formed integrally with a flow path member having a plurality of nozzles and is in contact with the flow path member, is heated. An ink jet head having a heat generating portion. 3. In an ink jet head used in an ink jet printer, a region of the flow path member, which is formed integrally with a flow path member having a plurality of nozzles and is in contact with the flow path member, is heated. An ink-jet head comprising: a heat generating portion; and a temperature detecting means provided in the flow path member. 4. In an ink jet head used in an ink jet printer, a region of the flow path member, which is formed integrally with a flow path member having a plurality of nozzles and is in contact with the flow path member, is heated. Providing a heat generating part, providing a temperature detecting means in the flow path member, comparing the temperature detected by the temperature detecting means with a set temperature, and causing the heat generating part to generate heat when the detected temperature is lower than the set temperature. An ink jet printer, wherein the flow path member is maintained at substantially the set temperature.