JPH054337A - Hot melt ink jet recording device - Google Patents

Abstract

PURPOSE:To make ink fly in a state being law viscosity so as to obtain high quality image having excellent fixing property by providing means for heating air around nozzles of a nozzle plate. CONSTITUTION:A heater 16 is adhered on a passage plate 3 through a heat transfer member 18 and the heat transfer member 18 is provided creeping to a nozzle face. The heat transfer member 18 transfers the heat from the heater 16 to the passage plate 3 efficiently, melts hot melt ink in the passage, and conveys the heat from the heater 16 near the nozzle face so as to warm the air around the nozzle face. Although flying ink drops are cooled by the air around them, the air between the nozzle and a recording paper is warmed by the heat transfer member 18, so that quick lowering of the temperature is avoided and a low viscosity sufficient to permeate into the recording paper can be still maintained when they reach the recording paper.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a hot melt ink jet recording apparatus, and more particularly to a hot melt ink jet recording apparatus in which a recording medium is heated to store image information.

[0002]

2. Description of the Related Art Many proposals have hitherto been made regarding ink jet recording methods. These are so-called ink droplets of a recording liquid which are ejected and adhered to a recording medium to perform recording. In order to control the generation method of the recording liquid droplets and the flight direction of the droplets. Depending on the control method
There are several methods. The first system is disclosed in, for example, US Pat. No. 30,60429. This is called the Tele type method, in which droplets of the recording liquid are generated by electrostatic attraction, the generated droplets are controlled by an electric field according to the recording signal, and the droplets are selectively formed on the recording medium. The recording is performed by adhering to the. That is, an electric field is applied between the nozzle and the accelerating electrode to eject uniformly charged droplets of the recording liquid from the nozzle, and the ejected droplets can be electrically controlled according to a recording signal. The droplets are caused to fly between the electrodes, and the droplets are selectively deposited on the recording medium by the change in the strength of the electric field.

The second method is, for example, US Pat. No. 359.
No. 6,275, US Pat. No. 3,298,030 and the like. This is called the Sweet method, and the droplets of the recording liquid whose charge amount is controlled are generated by the continuous vibration generation method, and the droplets whose charge amount is controlled are deflected under a uniform electric field. Recording is performed on the recording medium by flying between the electrodes. Specifically, a charging electrode is arranged so that a recording signal is applied in front of an orifice (ejection port) of a nozzle, which is a part of a recording head provided with a piezoelectric vibrating element, for a predetermined distance. The piezoelectric vibrating element is mechanically vibrated by applying an electric signal of a constant frequency to the piezoelectric vibrating element, and a small droplet of the recording liquid is ejected from the orifice. At this time, charges are electrostatically induced in the ejected droplets by the charging electrode, and the droplets are charged with an amount of charge according to the recording signal. The droplets whose charge amount is controlled are deflected according to the added charge amount when flying between the deflection electrodes to which a constant electric field is uniformly applied, and only the droplets that carry the recording signal are the recording medium. Will adhere to the top.

The third method is, for example, US Pat. No. 341.
No. 6153 is disclosed. This is called a Hertz method, and is a method in which an electric field is applied between a nozzle and a ring-shaped charging electrode to generate and atomize small droplets of a recording liquid by a continuous vibration generation method for recording. That is, the atomization state of small droplets is controlled by modulating the electric field strength applied between the nozzle and the charging electrode in accordance with the recording signal, and the gradation of the recorded image is produced for recording.

The fourth method is, for example, US Pat. No. 374.
7120 specification. This is called the Stemme method, and its principle is fundamentally different from the first to third methods. That is, the first to third
In each of the methods, the droplets of the recording liquid ejected from the nozzles are electrically controlled during the flight, and the droplets carrying the recording signal are selectively adhered to the recording medium for recording. In contrast to this, in the Stemme method, a small droplet of the recording liquid is ejected and ejected from an ejection port according to a recording signal to perform recording.

That is, in the Stemme system, an electric recording signal is applied to a piezoelectric vibrating element attached to a recording head having an ejection port for ejecting a recording liquid to convert it into mechanical vibration of the piezoelectric vibrating element. A small droplet of the recording liquid is ejected and ejected from the ejection port according to mechanical vibration to adhere to the recording medium. As a similar recording system, Japanese Patent Publication No. 61-5
Some are disclosed in Japanese Patent Publication No. 9914. This is to form flying droplets of the liquid ejected from the ejection port by heating part of the liquid in the liquid passage communicating with the ejection port for ejecting the liquid in a predetermined direction to cause film boiling. Then, the droplets are made to adhere to the recording medium for recording.

However, as the ink composition used for these ink jet recording layers, a liquid ink composition based on water or the like is used. However, since the ink composition is recorded by bleeding into paper, bleeding occurs in recording on paper where ink easily bleeds into, and there is the drawback that the periphery of the recording dots is unclear and print quality deteriorates. is doing. On the other hand, as a means for obtaining good print quality regardless of paper quality, a hot melt type ink composition based on a wax that is solid at room temperature is used to heat and melt a solid ink at high temperature to fly. 2. Description of the Related Art A hot melt ink recording apparatus is known which forms a recording dot by cooling and solidifying on a recording paper.

However, when recording is performed using hot melt ink, a phase change from liquid to solid occurs on the recording medium. That is, the ink that has reached the recording medium is cooled rapidly and solidifies before sufficiently penetrating into the recording medium. Therefore, as shown in FIG. 4, the toner adheres in a raised state on the recording medium. In such a state, the fixing strength of the ink on the recording medium is weak, and the ink is easily peeled off or scratched by an external force, so that there is a drawback that the image quality is significantly deteriorated.

As a means for solving the above-mentioned drawbacks, US Pat. No. 4,751,528 discloses "PLATENARRANGMENT FOR HOT".
"MELT INKJET APPARATUS" discloses a recording apparatus that keeps the temperature of a recording medium constant in order to fix ink to the recording medium. Specifically, the recording medium is vacuum-sucked and adsorbed by the platen, the temperature of the recording medium is detected, and the recording medium is heated and cooled by a heat pump using a heater and a thermoelectric element based on the detection signal. It has means for controlling the temperature of the.

Further, in the "hot melt ink jet printer" of Japanese Patent Laid-Open No. 1-278361, in the feeding direction of a recording medium (recording paper), from a position immediately before a printing position by the ink jet head on the recording medium. It has been proposed that a heating means for heating the recording medium be provided at any position in the downstream area to ensure ink fixing to the recording medium.

Further, in the "hot melt ink jet recording apparatus with fixing mechanism" disclosed in Japanese Patent Laid-Open No. 63-205241, the recording medium is fed while keeping the distance between the ink jet head and the recording medium constant. In the platen of
A heating means is provided to liquefy the printed hot melt ink and fix it on the recording medium, and the ink raised on the recording medium is pressed by a roller to mechanically remove the ink. A recording device having a fixing means for permeating and fixing is disclosed.

The above-mentioned hot melt ink jet recording apparatus is excellent in improving the fixability of the hot melt ink, but it still has problems to be solved. That is, conventionally, a method for improving the fixed image quality (hereinafter, fixability) of the hot melt ink is to achieve by heating or pressurizing the paper surface. In this case, the platen or roller is heated. Therefore, a large-powered heater is required, which results in a large power consumption. Further, since the platen or roller has a large volume and a large heat capacity, it takes time to rise to a desired temperature even when heated, and there is a drawback that the warm-up time is long.

[0013]

The present invention has been made in view of the above problems, and achieves high image quality, obtains fixing means with low power consumption, and further, hot melt ink jet recording having a short warm-up time. The purpose is to provide a device.

[0014]

In order to achieve the above object, the present invention provides (1)
A hot melt ink that is solid at room temperature and is liquid at a temperature higher than room temperature is heated by a heating unit to make the hot melt ink into a liquid state and ejected from a nozzle of a recording head to form an image on a recording medium. In the ink jet recording apparatus, the nozzle plate is provided with heating means for heating the air in the vicinity of the nozzle portion, and (2) the recording head has a heater on the flow path plate via a heat transfer member. It is characterized in that the heat transfer member is arranged and extended on the nozzle plate. Hereinafter, description will be given based on examples of the present invention.

1A and 1B are configuration diagrams of a recording head which is an embodiment of a hot melt ink recording apparatus according to the present invention. FIG. 1A is a sectional view and FIG. a) a
FIG. 7 is an enlarged view taken along line A-A. In the figure, 1 is a substrate, 2 is a piezoelectric element, 3 is a flow path plate, 3a is an ink flow path, 3b is a wall portion, 4 is a common liquid chamber constituent member, 4a is a common liquid chamber, 5 is an ink supply pipe, 6 Is a nozzle plate, 6a is a nozzle, 7 is a drive circuit printed board (PCB), 8 is a lead wire, 9 is a drive electrode, 10 is a filler, 11 is a protective plate, 12 is a fluid resistance, 1
3, 14 are electrodes, 15 is an upper partition wall, 16 is a heater, 17
Is a heater power source, 18 is a heat transfer member, and 19 is a recording head. 2 is an exploded view of the recording head.

In the integrated head, the electrodes 13,
The laminated piezoelectric element 2 having 14 is grooved in the direction of the flow path 3a corresponding to the flow path 3a, and is divided into the groove 10, the driving piezoelectric element 2b, and the non-driving piezoelectric element 2a. Groove 1
Filler is enclosed in 0. The flow path plate 3 is bonded to the grooved piezoelectric element 2 through the upper partition wall 15. That is, the upper partition 15 is formed of the non-driving piezoelectric element 2.
It is supported by a and a wall portion 3b that separates the adjacent flow path. The width of the driving piezoelectric element 2b is slightly narrower than the width of the flow path 3a,
When a pulse-shaped signal voltage is applied to the drive piezoelectric element 2b selected by the drive circuit on the drive circuit printed board (PCB), the drive piezoelectric element 2b changes in the thickness direction and the flow path 3a passes through the upper partition wall 15. Changes, and as a result, ink droplets are ejected from the nozzles 6a of the nozzle plate 6.

Heaters 16 are adhered to the flow path plate 3 via heat transfer members 18, respectively. The heat transfer member 18 is provided around the nozzle surface. The heat transfer member 18 efficiently transfers the heat from the heater 16 to the flow path plate 3, melts the hot melt ink in the flow path, and
The purpose is to carry the heat from the nozzle to the vicinity of the nozzle surface to warm the air in the vicinity of the nozzle surface. Therefore, a material having a high thermal conductivity is used. For example, metals such as aluminum, iron, nickel, copper, stainless steel, or SiC, B
Ceramics such as eO and AlN are preferable materials.

The head is heated to a predetermined temperature by the heater 16 and the hot melt ink is melted.
The heating temperature at this time is determined by the melting point of the hot melt ink, the heat capacity of the head and the hot melt ink, etc., but is usually set to a temperature 5 to 20 ° C. higher than the melting point. In order to eject hot melt ink from the nozzle as ink droplets, it is preferable that the viscosity in the molten state is as low as possible, usually 20 cp or less, preferably 10 cp or less.

When the piezoelectric element is driven in a liquid state of the hot melt ink, the piezoelectric element is displaced in a direction perpendicular to the longitudinal direction of the flow path, and the volume of the flow path is changed. Ink droplets are ejected. The piezoelectric element is constantly given a signal to hold it so that the volume of the flow channel shrinks, and after the displacement of the selected flow channel in the direction of increasing the volume of the flow channel, the displacement of the volume of the flow channel is reduced again. By applying the given pulse signal, the hot melt ink is ejected as ink droplets from the nozzle corresponding to the flow path.

FIGS. 3A and 3B are views for explaining how hot melt ink is ejected as ink droplets. FIG. 3A is a sectional view of the head portion, and FIG. FIG. 6 is a plan view of a nozzle plate. In the figure, 20 is a recording medium (recording paper), 21 is hot melt ink droplets, 22a to 22j are nozzles, and 23 is a platen. The hot melt ink droplets 21 ejected from the nozzles 22 fly and adhere to the recording paper 20. The flying ink droplets are cooled by the surrounding air, but the heat transfer member 18 causes the nozzles 22 and the recording paper 20 to flow.
Since the air between them is warmed, the temperature does not drop sharply, and when it reaches the recording paper, the viscosity is still low enough to penetrate the recording paper 20. On the other hand, the recording paper 20 in the vicinity of the printing portion is warmed by the heat from the heat transfer member 18 of the head. Therefore, the ink adhering to the recording paper 20 sufficiently penetrates into the recording paper 20 to form an image that does not rise on the paper surface. Obtainable. From the above, if the distance between the heat transfer member 18 and the recording paper 20 is too large, the air in the vicinity of the nozzles or the recording paper 20 in the printing section cannot be heated sufficiently, so it is usually 2 mm or less, preferably 1 mm. The optimum value is 0.8 mm or less.

Next, the test results of the image quality printed by using the above-mentioned hot melt ink jet recording apparatus according to the present invention will be described below. The test conditions are as follows. Recording density 300dpi Piezoelectric element drive voltage 25V Drive frequency Maximum 4KHZ Recording paper PPC paper Xerox 4024 (A4) Ink Dataproducts SI480 ink head heating temperature 110 ℃ Distance between heat transfer member and recording paper 0.5mm, 2mm Comparative example 1 : The above recording head, which has a structure in which a heat transfer member is not provided. Comparative Example 2 : The recording head of the specific example, in which the distance between the heat transfer member and the recording paper is 3 mm. The image printed with these is 500g / cm with sand eraser
^When the load of ² was applied and the presence or absence of dirt after 20 times of rubbing was observed and the height of the printing dot was measured, both of 0.5 mm and 2 mm in the recording head of the specific example were stained by sand eraser. In contrast, the height of the printing dot was 10 μm or less, whereas the recording heads of Comparative Example 1 and Comparative Example 2 were stained 10 times or less, and the height of the printing dot was 20 μm or more. Met.

[0022]

As is apparent from the above description, according to the present invention, the nozzle plate is provided with the means for heating the air in the vicinity of the nozzle portion. Therefore, when the ink reaches the recording paper, the ink flying that maintains a low viscosity state is achieved. It was possible to obtain a high image quality with good fixability.

[Brief description of drawings]

FIG. 1 is a configuration diagram for explaining an embodiment of a hot melt inkjet recording apparatus according to the present invention.

FIG. 2 is an exploded configuration diagram of a recording head.

FIG. 3 is a diagram for explaining how hot melt ink is ejected as ink droplets.

FIG. 4 is a diagram showing a state of being solidified before sufficiently penetrating into a recording medium.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Piezoelectric element, 3 ... Flow path plate, 3a ... Ink flow path, 3b ... Wall part, 4 ... Common liquid chamber constituent member, 4a ... Common liquid chamber, 5 ... Ink supply pipe, 6 ... Nozzle plate , 6a
... Nozzle, 7 ... Drive circuit printed board (PCB), 8 ...
Lead wire, 9 ... Drive electrode, 10 ... Filler, 11 ... Protective plate, 12 ... Fluid resistance, 13, 14 ... Electrode, 15 ... Upper partition wall, 16 ... Heater, 17 ... Heater power supply, 18 ... Heat transfer member, 19 … Recording head.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location 8804-2C B41J 29/00 H

Claims (2)

[Claims] 1. A hot melt ink, which is solid at room temperature and liquid at a temperature higher than room temperature, is heated by a heating means to liquefy the hot melt ink and eject it from a nozzle of a recording head to form an image on a recording medium. In the hot-melt ink jet recording apparatus for forming a sheet, the nozzle plate is provided with heating means for heating air in the vicinity of the nozzle portion. 2. The recording head is characterized in that a heater is arranged on a flow path plate via a heat transfer member, and the heat transfer member is also extended and provided on the nozzle plate. The hot melt ink jet recording apparatus according to claim 1.