JPH03132356A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To prevent certainly a bubble from generating without bringing about complication of structure of a head itself and complication of a control circuit by a method wherein a nozzle opening part is so constituted as to be sealed by being brought into contact with sealing liquid of a sealing liquid reservoir when the title ink jet recorder is stopped. CONSTITUTION:When a power source switch is disconnected at a position wherein a head 1 is outside recording start position, a heater switch 9 is disconnected and besides, the head 1 together with a carriage 7 is rotated taking a guide shaft 6 as a rotary fulcrum. A nozzle opening part 3 (an ink discharge opening) is dipped into liquid in a sealing liquid reservoir 10. A heating means is provided to the sealing liquid reservoir 10, and sealing liquid 11 consisting of oil boiling point of which is 120 deg.C or higher is warmed at a temperature which is higher than ordinary temperature and lower than approx. 120 deg.C. As time elapses since a power source is off, the ink 2 in the head 2 is solidified by cooling and is shrunk. Though the ink 2 starts retreating from the nozzle opening part 3, since the nozzle opening part 3 is in contact with the sealing liquid 11, the nozzle 3 sucks the sealing liquid 3 without attracting air, and bubbles are effectively prevented from being generated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an inkjet recording device, and particularly to a recording medium that can be handled using a so-called hot-melt ink that is solid at room temperature, is heated and melted during use, and is ejected from a nozzle opening. The present invention relates to a melt-type inkjet recording device that forms an image thereon.

Conventional technology Conventional hot-melt inkjet recording devices
When the apparatus is stopped, air bubbles are formed in the ink flow path (or inside the ink) in the ink jet head due to volume change during solidification of the ink, resulting in low reliability.

Therefore, in order to eliminate this drawback, various methods have been proposed (for example, Japanese Patent Laid-Open No. 62-73953).

Hereinafter, a conventional true melt type inkjet recording apparatus will be described with reference to FIGS. 6 to 8.

In the inkjet head of the recording apparatus shown in FIG. 6, when a switch 101 is closed and an electric signal is applied, melted hot melt ink is ejected from a nozzle opening 103. This inkjet head includes three heaters in addition to the heater 112 as heating means for melting the ink.
Four heaters 131, 132, and 133 are arranged in order along the flow path 102 toward the back of the nozzle opening 103 so that the molten ink enters the flow path 102 from the supply opening 106 and flows to the nozzle opening 103. It has become.

When the device is stopped (power off), the switch 141
．． 142, 143 are cut in this order, and the heaters 131, 132, and 133 are stopped in order from the side closer to the nozzle opening 103, thereby preventing the generation (intake) of air bubbles.

In addition to the above, the inkjet head of the recording apparatus shown in FIG. 7 is provided with a nozzle means for blowing cooling gas 134 into the nozzle opening 103 to more reliably prevent bubble generation.

In the inkjet head of the recording device shown in FIG. 8, in addition to the one shown in FIG. 6, a rubber camp 13 for cooling and sealing is used.
6 is provided to more reliably prevent the generation of bubbles.

Problems to be Solved by the Invention However, each of the above inkjet recording apparatuses has the following problems.

The heater for heating can be divided into multiple parts and installed in the head,
In addition, if cooling gas or rubber cap means are also provided, the structure of the head itself becomes complicated, and the configuration of the control circuit becomes complicated, resulting in an increase in cost. Moreover, the effect of preventing bubble generation is still not sufficient.

An object of the present invention is to provide a highly reliable inkjet recording device (printer) in which bubble generation can be reliably prevented without complicating the structure of the head itself or the configuration of the control circuit. .

Means for Solving the Problems In order to solve the above problems, the inkjet recording apparatuses (hereinafter simply referred to as "recording apparatuses") according to claims 1 to 6 are provided with hot-melt ink droplets from a nozzle opening in response to an electrical signal. The nozzle opening is provided with a sealing liquid reservoir for the opening in the inkjet head for ejecting, and when the apparatus is stopped, the nozzle opening comes into contact with the sealing liquid and is sealed.

The filter sealing liquid material used in this invention is usually one that is liquid at room temperature, as in the second aspect of the invention.

Further, the recording apparatus of the present invention may also include a heating means for increasing the temperature of the sealing liquid from room temperature to 120° C. or less, as in the third aspect of the invention. When providing the heating means, as in the invention of claim 4, the boiling point of the sealing liquid is 120°C.
It is preferable to set it to the above.

As a specific sealing fluid material, a hydrocarbon oil as in the sixth aspect of the invention or a silicone oil as in the sixth aspect of the invention is used.

When the device is stopped, the structure for bringing the nozzle opening of the head into contact with the sealing liquid is to move the head so that the nozzle opening is immersed in the liquid in a fixed sealing liquid reservoir, or, An example of such a structure is to move the sealing liquid reservoir so that it comes into contact with the nozzle opening so that it comes into contact with the liquid.

Function: In the recording apparatus of the present invention, the sealing liquid is in contact with the nozzle opening when the apparatus is stopped. On the other hand, as the apparatus is stopped, the ink that has been in a molten state solidifies over time at a speed corresponding to the liquid 81A. During this solidification process, the ink volume decreases within the nozzle opening, creating voids, but the sealing liquid is sucked in at any time to fill the voids, thereby reliably preventing the generation of bubbles.

Since the sealing liquid reservoir is separate from the inkjet head, there is no need for the head itself to have a complicated structure.
It may also lead to increased costs ().

Embodiments Next, embodiments of the recording apparatus of the present invention will be described in detail.

Embodiment 1 FIGS. 1(a) and 2(b) and FIG. 2 show the main structure of a recording apparatus (printer) according to a first embodiment.

In the recording apparatus of Example 1, the ink generator 1 is
It is placed and moved on a carriage T that can reciprocate along a guide axis e.

In FIGS. 1(a) and 1(b), the head 1 is in a position away from the recording start position (not shown), and in this case, the ink ejection signal switch 8 is always in the OFF state, and the ink ejection command is turned off. There is no signal.

When the power switch (not shown) of the recording apparatus is turned off in this state, the heater switch 9 is turned off and the head 1 is rotated by the rotating mechanism (
The carriage 7 is rotated by 90 degrees using the guide shaft 6 as a rotational fulcrum (not shown), and the nozzle opening 3 (ink ejection port) is immersed in the liquid in the sealing liquid reservoir 10 . Sealing liquid reservoir 1
0 is provided with a heating means (not shown), and a sealing liquid 11 made of hydrocarbon-based or silicone-based oil such as insulating oil or compressor oil with a boiling point of 120°C or higher is heated to a temperature higher than room temperature, about 120°C or higher. heated to a low temperature. This is because the nozzle opening 3 is heated to between room temperature and around 100°C, depending on the type of hot melt ink.
In order to prevent the nozzle opening 3 from being rapidly cooled when immersed in the sealing liquid, the nozzle opening 3 is heated to approximately the same temperature. If the liquid temperature is higher than 120°C, the sealing liquid will boil or evaporate, which is not preferable. Note that since the heating means for the sealing liquid reservoir 10 is also turned off at the same time as the power switch is turned off, it goes without saying that the temperature of the sealing liquid is also cooled at the same time as the nozzle opening 3 is cooled.

As time passes from 17:00 on the power source 01, as shown in FIG. 2, the ink 2 in the head 1 contracts as it cools and solidifies, and begins to retreat from the nozzle opening 3. Since the nozzle opening 3 is in contact with the sealing liquid 11, it sucks in the sealing liquid 11 without drawing air in. In this way, the gap created by the retreat of the ink 2 is filled with the sealing liquid 11. Bubble generation is effectively prevented.

When returning from this power supply 012F state to the power ON state again, the process is as follows.

When the power switch of the recording device is turned on, a rotating mechanism (not shown) is activated, and the head 1 moves as shown in FIG. 1(b).
At the same time, the heater switch 9 is turned on and heating of the ink 2 is started. The ink 2 expands as it melts, and most of the sealing liquid 11 that has been drawn into the head 1 is pushed out of the nozzle opening 3 as well. The extruded liquid 11 flows along the droplet guide plate 16 and falls into the sealing liquid reservoir 1o. Even if there is residual sealing liquid in the head 1, the residual sealing liquid is discharged together with unnecessary ink from the nozzle opening 3 into the unnecessary ink reservoir 17 in front of the head 1 by the cleaning discharge operation performed before the start of recording. and removed.

Note that the filter 16 in the recording apparatus of the first embodiment is for filtering out dust mixed in the ink 2.

Embodiment 2 FIGS. 3 to 6 show the main structure of a recording apparatus according to a second embodiment.

The parts of the second embodiment whose numbers are common to those of the first embodiment are the same, and therefore the description thereof will be omitted.

In the device of the second embodiment, when the power switch (not shown) is turned off, the heater switch 9 is turned off, and at the same time, the head 1 is automatically moved to the stop position 20 shown in FIG. It is now back to .

On the other hand, a sealing liquid tube 24 rotatably supported by a fulcrum shaft 27 is provided near the stop position 2o. This tube 24 is in a state in which the tube tip 24a is pulled diagonally upward by the spring 28 when the head 1 is not at the stop position 2o.

When the head 1 is at the stop position 20, it is driven by the lever 23 that is pressed against the head 1, and as shown in broken lines in FIG. An elastic member cap 25 with a hole in the center is attached to the tube tip 24a so that the tube tip 24a and the nozzle opening 3 are in close contact.Tube 24
The rear end of is connected to the sealing liquid container 10 via a tube 26.

The liquid level in this container 1o is set to be higher than the nozzle opening 3 of the head 1 at the stop position 2o. Therefore, when the tube 24 is in contact with the nozzle opening 3,
As shown in FIG. 6, the sealing liquid 11 moves toward the nozzle opening 3 and comes into contact with it.

As time passes from the time when the power is 01"F, the ink 2 in the head 1 cools and solidifies, and the ink 2 contracts, and the nozzle opening 3 also begins to retreat, but the nozzle opening 3 is still sealed. Since it is in contact with the liquid 11, the voids caused by the retreat of the ink 2 are filled with the sealing liquid 11, and the generation of bubbles is effectively prevented, as in Example 1.

When returning from this power OFF state to the power ON state again, the process is as follows. Turn on the power switch of the recording device (O
N), the head 1 moves to the standby position (recording start position) 29 as shown in FIG. 4(b), and at the same time,
The heater switch 9 is turned on, heating of the ink 2 is started, and the printer waits until it is ready for use. The ink 2 expands as it melts, and most of the sealing liquid 110 drawn into the head 1 is also pushed out of the nozzle opening 3. The extruded seals o and 11 pass through the droplet guiding plate 16 and form the unnecessary ink reservoir 3.
It drops to 0. Even if there is some residual sealing liquid remaining in the head 1, the cleaning discharge operation performed prior to the start of recording will remove the residual sealing liquid from the nozzle opening 3 together with unnecessary ink.
The ink is ejected into the unnecessary ink reservoir 17 in front of the head 1 and removed.

In addition, as the throat 1 moves away from the stop position, the drive of the rotor tube 24 is released by the first collar 23, so the tube 24 also moves away from the throat 1 and is pulled upward by the spring 28 and returned to its original position. It goes without saying that he must return to his position.

Further, it goes without saying that the recording apparatus according to the present invention is not limited to the above-mentioned example. For example, in sealing liquid.
Compounds other than those exemplified may also be used.

Effects of the Invention] As described in 2, in the recording apparatus of claims 1 to 6, the nozzle opening of the head comes into contact with the sealing liquid when the apparatus is stopped, and the generation of bubbles is reliably prevented. Since the structure itself is not complicated, it is low cost, highly reliable, and highly practical.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are cross-sectional views showing the main structure of a first embodiment of a recording apparatus according to the present invention, and FIG.
l indicates the state when the power is turned on, and (bl is the power supply 01")
FIG. 2 is a partial enlarged sectional view of FIG. 1 (I), and FIGS. 3 and 6 are main part configurations of a second embodiment of the recording apparatus according to the present invention. 4(a) and (b) are explanatory diagrams of the position of the head in the device of this second embodiment, and the figure (al is when the power supply is OI"F"). Figure (b) shows the state when the power is turned on. Figures 6, 7, and 8 are sectional views of the main parts of the conventional recording apparatus. 1... Inkjet head, 2... Ink, 3.
...Nozzle opening, 1o...Sealing liquid reservoir, 11...
Sealing liquid, 24...Sealing liquid Q.

Claims (6)

[Claims] (1) A sealing liquid reservoir is provided at the opening in the inkjet head that receives an electric signal and ejects hot melt ink particles from the nozzle opening, and when the apparatus is stopped, the nozzle opening comes into contact with the sealing liquid and is sealed. Inkjet recording devices are becoming more and more popular. (2) The inkjet recording apparatus according to claim 1, wherein the sealing liquid material is liquid at room temperature. (3) The inkjet recording apparatus according to claim 1, further comprising a heating means for controlling the temperature of the sealing liquid in a range of room temperature to 120°C. (4) The inkjet recording device according to claim 3, wherein the sealing liquid has a boiling point of 120° C. or higher. (5) The inkjet recording apparatus according to claim 2, wherein the sealing liquid material is a hydrocarbon oil. (6) The inkjet recording apparatus according to claim 2, wherein the sealing liquid material is silicone oil.