JPS6194765A - Liquid-supplying device - Google Patents

Abstract

PURPOSE:To prevent dust from adhering to a nozzle part at non-printing time and prevent bubbles from being generated from the nozzle part, by using a cap roll comprising an elastic material having a specified rubber hardness and compressive set characteristic. CONSTITUTION:At non-printing time, the cap roll 10 is pressed to close a tip opening 19 of a nozzle 6. A roll surface layer 18 is formed of an elastic material having a compressive set of not larger than 12% and a hardness of 30-60 deg., and while maintaining the layer 18 in sufficient contact with the nozzle 6, the layer 18 is caused to eat into the nozzle 6 to close an injection port 19, thereby preventing generation of bubbles from the nozzle part which trouble is liable to occur due to variations in environment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid supply device, and particularly to a liquid supply device suitable for supplying ink in an inkjet printer.

[Conventional technology]

Conventionally, an inkjet printer records desired characters or figures on a recording material such as recording paper without applying an @ strike, and the nozzle opening of a recording ink jetting nozzle is sealed with a cap roll when not in use. Printers are known to get busy. Unlike conventional impact-type recording devices, these inkjet printers produce a desired information pattern by striking controlled recording ink droplets onto a recording material, and output from a computer or typewriter. It has even reached the point where it has been put into practical use as a recording device.

In such a printer, the nozzle (hereinafter, the unit including the nozzle is referred to as a print head, and the part that ultimately jets recording ink is referred to as a nozzle) has an ink ejection opening (nozzle opening) that is in contact with the outside air. have. In this case, even if the nozzle is installed inside the device,
It is inappropriate to leave it as it is when it is not marked.

This is because, if left in such a state, dust particles may adhere to the nozzle portion, bubbles may form in the nozzle portion, or drying may occur if the nozzle is left unused.

In particular, if dust (fine particles) adheres to the nozzle opening, a portion of the ejected ink will collide with the dust, making it impossible to maintain the constant amount of ink during flight. Moreover, in an apparatus in which straightness of the ejected ink is essential, the above-mentioned phenomenon has the undesirable effect of causing unexpected dots to be formed on the recording material and destroying the recorded image. Further, the UH ejected ink that hits the adhered dust K'fir travels over it and contaminates the front surface of the print head. In this case, if the print head is equipped with a plurality of nozzles (for example, seven nozzles in the vertical direction), the distance between the nozzles is extremely small, and other nozzles K will also be adversely affected. In other cases, the collided ink solidifies on the dust, and when it becomes large, it causes a condition in which the nozzle opening is blocked, and the recording operation is no longer possible.

We will also discuss the occurrence of bubbles and the undesirable consequences thereof. The nozzle opening is extremely small, but since recording ink is made of volatile substances whose main components are ethylene glycol, water, and pigments, if non-recording operations are continued for a long time, it will gradually vaporize and cause the nozzle to open. Air will be introduced inside.

Furthermore, air also enters the nozzle trap when environmental changes occur, especially temperature changes.For example, when the temperature drops, the ink inside the chamber (including the nozzle part) provided in the print head as described above At this time, since the opening of the print head exists only in the nozzle part, the ink surface in the nozzle is pulled back inside the chamber,
As a result, air is introduced. Although this amount of contraction is small in absolute value, the volume of the nozzle is even smaller, so even the slightest change as described above will cause air to enter. The air that has entered the inside of the busy nozzle is accelerated by the movement of the ink and becomes bubbles. Also, when the ink inside the nozzle evaporates,
If the pigment is left behind in the nozzle and hardens, this will cause bubbles to form during the next operation (in addition, if the print head is accidentally subjected to sudden shock or vibration, the ink may be ejected from the nozzle). In any case, when air bubbles generated for some reason reach the chamber, the 5 iWA dynamic energy is generated due to the volume conversion for easy ink ejection based on the control signal described above. is spent shrinking the air bubbles and cannot contribute to ink ejection.It will be readily understood that this is a fatal defect without needing any explanation.

In order to correct the above-mentioned problems, when performing a recording operation of the print head, a distance is placed between the nozzles provided at the tip of the print head, and after the recording operation is completed, the print head stops at a predetermined position. By disposing a cap means so as to be able to come into contact with the nozzle and cover the opening after recording, it is possible to prevent dust from adhering to the nozzle part during non-recording time, and also to prevent dust from adhering to the nozzle part, which is likely to occur due to changes in the environment. An inkjet printer has been proposed in which the generation of air bubbles from the nozzle portion can be eliminated.

A camp roll made of an elastic material is known as a cap means used in this printer.

In other words, when not recording, the nozzle opening is pressed against the cap roll and bites into the elastic surface of the cap roll to cut off contact with outside air, which prevents dust from adhering to the nozzle opening and air bubbles from forming. It is an effective means.

Various polymers, rubbers, etc. are used as the elastic body constituting the cap roll.

[Problem that the invention seeks to solve]

As mentioned above, the cap roll is an effective means for preventing dust adhesion and bubble generation at the nozzle opening, but sufficient effects cannot be obtained unless the properties of the elastic body constituting the cap roll are appropriate.

An elastic body suitable for the material of the cap roll must have the following properties.

(1) It must have appropriate elasticity to sufficiently seal the nozzle opening.

(2) Must have durability. That is, the cap roll is separated from the nozzle after the nozzle opening is sealed as described above, and the ink adhering to the surface of the cap roll is scraped off by a cleaning member (for example, a cleaning blade) K as described later.

At this time, the cap roll is required to have creep resistance (no distortion such as permanent deformation) and abrasion resistance (to withstand wear caused by the cleaning member).

As suitable elastic bodies constituting the cap roll, for example, JP-A-57-22066 discloses the use of silicone rubber, JP-A-54-68633 discloses the use of polyurethane; Gansho 58-8466
The specification of No. 5 discloses a cap roll constructed using ester-based urethane rubber.

The inventors of the present invention have investigated the cap rolls that have been disclosed or put into practical use, and have found that all of them have poor durability, and that this is mainly due to permanent deformation that occurs in the cap roll during use. did. In other words, when the printer is at rest, the tip of the ink jet nozzle is pressed against the cap roller surface with a certain amount of pressure, and the cap roller surface is recessed accordingly, sealing the nozzle tip.However, when the printer is operating, the nozzle tip is pressed against the cap roller surface. Even if the cap roller is separated from the cap roller surface, the dents will not completely recover due to the compression set of the elastic body that makes up the cap roller and will remain, so if used repeatedly, unevenness will occur on the cap roller surface.
Failures such as liquid leakage and clogging may occur.

An object of the present invention is to provide a liquid supply device that stably maintains a nozzle sealing effect for a long period of time without causing problems such as liquid leakage or clogging even when used repeatedly.

[Means to solve the problem]

The above problem has a liquid injection section that injects and supplies liquid, and a cap member that presses and seals the injection port when the liquid injection section is not in use, and the compression set is 12% or less. The problem has been solved by a liquid supply device characterized in that it is made of an elastic body with a hardness of 30' to 30'.

As mentioned above, in terms of the durability of the cap roller, it is clear that the compression set of the elastic body constituting the cap portion is as good as 71%. Generally, the higher the hardness of the rubber of the elastic body, the smaller the compression set, but if the hardness is too high, a large amount of pressure will be required to push the nozzle tip into the cap roller and seal it, which is not practical. becomes inappropriate.

As a result of various studies conducted by the present inventors, it has become clear that the best results can be obtained by using an elastic body with a rubber hardness in the range of 1 or less and a compression set of 12 inches or less.

If the rubber hardness is more than 6 (/'), the pressure required to seal the nozzle will be excessive, and if it is less than r, the sealing may become incomplete when the printer VC89 is applied during capping, which is not preferable.

It should be noted that the compression set and rubber hardness mentioned herein were both measured using the equipment and method specified in Japanese Standard (1ZS) K6301-1975.

Examples of the elastic material used in the present invention include ethylene propylene terpolymer rubber, phthyl rubber, caprolactone urethane rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, nitrile rubber, isoprene rubber, styrene-butadiene rubber, chloroprene rubber, and fluororubber. Among them, ethylene propylene terpolymer rubber and styrene butadiene rubber are preferred.

The effects of the present invention will be specifically explained below using examples.

〔Example〕

FIG. 1 is a perspective view showing the configuration of the printer, and FIG. 2 is a sectional view thereof.

Wrap recording paper P around platen 1. Also, tension spring 2
The paper press roller 4 biased by the tension spring 3 and the paper press roller 5 biased by the tension spring 3 are pressed against the platen 1, respectively, and bring the recording paper P into close contact with the platen l. The platen 1 has a motor etc. (as shown).

) to transport the recording paper P.

A print head 7 having an ink ejection nozzle surface 6 is mounted on a carriage 8 and is driven by a wire (not shown) and a motor (not shown) connected to the carriage 8.
9a, 9b along arrow A
, H direction directional movement.

Ink is ejected from the ink ejection nozzle surface 6 toward the recording paper P in accordance with a recording signal to perform printing on the recording paper P.

In order to obtain good printing on the paper P, it is necessary to perform ink jetting in a stable manner, and stable ink jetting keeps the ink jet nozzle surface 6 clean. This can be obtained from K. For this reason, in this printer, before starting the printing operation, the carriage 8 is moved in the direction of the cap roll 10 provided in the axial direction of the platen l, and the ink jet nozzle surface 6 and the outer peripheral surface of the cap roll 10 are aligned. Bring them into close contact. FIG. 3 shows a cross-sectional view of this state.

The cap roll 10 has a core metal 17 such as KA13 around the rotating shaft 16, and an elastic layer 18 is integrally provided around the entire circumference of the core metal. When the nozzle 6 is not in use (not recording) as shown in FIG.
9, a cap roll 10 is pressed as shown in an enlarged view in FIG. At this time, since the roll surface groove is made of an elastic material, it elastically bites into the trap and nozzle 6 while being in close contact with the trap, and the injection port 19 is completely sealed. For example, the cap roll 10 is suppressed by 300.9/c++ with respect to the nozzle 6, and it is appropriate that the amount of bite during this suppression is Q, about 6 mrtr.

The structure of the cap roll 10 can be obtained by disposing a core metal 17 previously molded by die-casting or the like in a mold, injecting the composition of each glaze rubber component into the molding space, and curing it. In this case, the adhesive strength of the elastic layer 18 to the core bar 17 can be increased by applying an adhesive to the outer circumferential surface of the core bar 17 in advance or by roughening the outer circumferential surface appropriately.

Further, the outer circumferential surface of the elastic layer 18 is preferably finished with a surface roughness of 1.0 .mu.s or less (preferably a mirror surface) in order to improve cleaning performance during cleaning, which will be described later.

On the other hand, the ink ejection nozzle surface 6 is treated to have ink-repellent properties. For example, when using water-based ink, water-repellent treatment may be applied to the ink jet nozzle surface for 6 km. When ink is also ejected from the ink ejection nozzle surface 6, an ink column C is formed between the ink ejection nozzle surface 6 and the cap roll 10 as shown in FIG.

At this time, the overflowing ink flows into a purge nozzle IIC connected to a suction pump (not shown). Ink column C
After the cap roll 10 is formed, turn the cap roll 10 counterclockwise (arrow).
When rotated in the direction, the ink comb 2 C moves to the lower side of the ink jet nozzle surface 6 and is attracted by the purge nozzle IIK, so that the ink jet nozzle surface 6 becomes busy with cleaning.

The ink that is sucked into the purge nozzle 11 and not cleaned by these operations tends to adhere to the outer peripheral surface of the cap roll 10, which has good hydrophilicity, and the adhered ink is removed by polyacetal, etc. The ink is scraped off by the synthetic resin doctor blade 12, the scraped ink is absorbed by the pad 13, and the outer peripheral surface of the cap roll 10 is cleaned.

If there is ink remaining on the outer peripheral surface of the cap roll 10, the ink dries and solidifies. This solidified ink clogs the ink ejection port 19 (see FIG. 4) of the ink ejection nozzle surface 6 and has an adverse effect. Therefore, the outer peripheral surface of the cap roll 10 must be kept clean at all times. For this reason, the cleaning device comprising the doctor blade 12 and the pad 13 has a structure in which the cleaning device is pressed against the circumferential surface of the cap roll 10 by a compression spring 15 utilizing the wall surface of the roll cover 14.

Since the roll 10 has appropriate surface hardness and elasticity, it can elastically return to its original shape from its deformed state after being separated from the nozzle 6, allowing the next cleaning to be performed satisfactorily. Cap rolls made of various materials with a structure that can withstand wear and tear over 12 hours were prototyped, and their nozzle sealing performance and deformation due to compression set (liquid leakage caused by compression set) were evaluated.

For sealing performance, attach the nozzle tip to the unused elastic layer surface at 300fi/
Evaluate the state of liquid leakage when pressed with the pressure of Cld.A is the case where there is no liquid leakage, B is the case where there is a slight liquid leakage, or liquid leakage is occasionally observed during repeated experiments, and B is the case where the sealing is incomplete. Items that constantly leak liquid are designated as C.

To prevent liquid leakage due to deformation, press the nozzle tip against the elastic layer surface and leave it in a constant temperature room at ω℃ for 7 days, then remove the nozzle and leave it at room temperature for 1 hour. Ink leakage was observed (see Figure 6, dots a indicate nozzle marks). A sample with no liquid leakage was graded A, a sample with slight liquid leakage was graded 81, and a sample with severe liquid leakage was graded C. When printers equipped with each prototype roller were used for a long period of time, it became clear that the printers that received results B and C in this experimental method had early button fluid leakage and clogging, and had low practical durability. On the other hand, those that received an A rating were confirmed to be able to withstand long-term practical use.

Test (The elastic materials used were urethane rubber (OR), sterene butadiene rubber (SBR), chlorophytyl rubber (CBR), and ethylene propylene rubber (EPT). The results of the test are shown in Table 1. Mid-term exam, exam number 1.
2.3 is an example of the present invention, and 4.5°6.7 is a comparative example.

Test No. 1 using the elastic body according to the present invention as shown in Table 1.
It was confirmed that only sample No. 2.3 had excellent sealing properties and resistance to deformation.

〔Effect of the invention〕

By using the cap roll made of an elastic body with specific rubber hardness and compression set characteristics according to the present invention, liquid sealing during rest is ensured, and it is durable enough to last even in long-term use. A high liquid supply device can be obtained.

Note that the present invention is applicable not only to the above-mentioned inkjet printer but also to the supply of liquids such as ink that easily cause clogging.

[Brief explanation of the drawing]

Figure 1 is a perspective view of the main parts of an inkjet printer, Figure 2 is a right side view of Figure 1, Figure 3 is a sectional view showing the positional relationship between the print head and the cap roll during non-recording, and Figure 4 (A ) is an enlarged cross-sectional view of the main part during the third rotation, Figure 4 (B) is a longitudinal cross-sectional view of the cap roll, Figure 5 is a cross-sectional view similar to Figure 3 during cleaning, and Figure 6 shows the liquid due to deformation. It is a figure which shows the position of a nozzle at the time of a leakage test. ■...Platen 6...Nozzle (surface) 7...Print head 10...Cap roll 11...Purge nozzle 12...Cleaning field 18...Elastic layer 19...Ink ejection Opening Agent Patent Attorney No. 1) Parent-in-law Figure 1 Figure 2 Figure 3 Figure 71 Power Shield Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] It has a liquid ejecting section that injects and supplies liquid, and a cap member that presses and seals the ejection port when the liquid ejecting section is not in use, and at least a surface area of the cap member on the side of the liquid ejecting section. , or the compression set at least in the vicinity of the inside of the surface is 12% or less and the hardness is 30
A liquid supply device comprising an elastic body having an angle of 60° to 60°.