JP2936682B2 - Ink jet recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, and more particularly, to an improvement in an ink supply system.

[Conventional technology]

A pressure pulse control type ink jet recording apparatus that applies a pulse voltage using an electromechanical pressure conversion element such as a piezoelectric element as a pressing means and discharges ink from an ink discharge nozzle to record a desired character on a recording medium is known. Generally known.

This type of ink jet recording apparatus directly changes the volume of the ink and discharges the ink from a discharge nozzle. Therefore, if a gas such as air is mixed into the ink, the above-described change in volume is absorbed by the gas in the ink, resulting in an ink ejection failure. In order to prevent such a discharge failure, ink is conventionally used as an ink supply means (an ink container is used. A blind plug made of an elastic member such as rubber is provided at an ink outlet). The recording head is supplied to the recording head through an ink supply pipe by inserting a hollow needle into the recording medium, so that air or the like is not mixed during the supply of the ink.

[Problems to be solved by the invention]

However, this type of conventional ink jet recording apparatus has a serious problem that ink leaks into the apparatus when the ink container is replaced or the apparatus body is transported. That is, the ink forms a meniscus in the nozzle portion provided in the print head, and a force for holding the ink in the print head is generated in a certain direction.
When the hollow needle side is lower than the print head, the print head has a holding force of about 300 to 400 mm, and there is no problem in this case. However, in the case opposite to that described above, that is, when the hollow needle side is at a higher position than the print head, the above-described ink holding force hardly occurs in the print head. Therefore, when transporting the apparatus main body with the ink container pulled out from the hollow needle, it is impossible to control the apparatus attitude, and ink leaks from the print head side.

There has also been proposed an ink supply system in which an ink holding material such as a polyurethane foam is incorporated in an ink container. In this case, since the ink container has the ink holding power, the ink container can be arranged at a higher position with respect to the print head, and therefore, the layout can be freely selected.

However, when the ink container is pulled out of the hollow needle, the hollow needle is located at a higher position than the print head, and ink leaks from the print head side. Further, the leakage of ink from the print head side not only causes soiling of the apparatus, but also causes the same amount of air to be mixed in from the hollow needle side due to the leakage of ink in the ink supply path. There was a major problem that this would cause trouble due to air bubbles in the head.

A description will be given of a case where the above problems are to be solved using a conventional hollow needle. Conventionally proposed hollow needles have the shape of an injection needle whose tip 51 is simply cut diagonally as shown in FIG. 5, or a needle-like pointed tip 52 as shown in FIG. Is integrally formed with the hollow tube portion 55 by the shibo processing. In the case of the injection needle shape shown in FIG. 5, the process is inexpensive because the shape is simple, and an ink holding force can be obtained by reducing the inner diameter. However, on the other hand, when piercing into the outlet of the ink container, since the outlet is formed by a blind plug made of an elastic member such as dust, the shavings of the blind plug 12 scraped off by the sharp shape of the distal end portion 51. Is mixed in from the front end portion 51, causing a problem such as clogging of a hole. As a solution to the problem shown in FIG. 5, a hollow needle 53 having a needle-like pointed end 52 shown in FIG. 6 has been conventionally proposed and used. The hollow needle 53 shown in FIG.
54 is formed near the needle-shaped point 52. In this case, the point 52 and the hollow tube 55 are made of the same member and the point
52 is formed by special shibo processing. Therefore, it is very expensive. Further, in order to obtain the holding power of the ink, the inner diameter of the hollow tube portion 55 may be reduced. In addition, the ink holding force F is obtained from the equation of the capillary force as follows: Even if the calculated cross-sectional area is the same, the holding force can be increased when the circumferential length is long. Conversely, in the case of a circular shape, the holding force is the smallest. In other words, in the case where a conventionally proposed hollow needle has an ink holding force, it is necessary to make the inner diameter of the hollow tube portion 55 extremely small. Further, if the inner diameter is small, there is a problem that the flow path resistance of the ink flow path becomes large. Hollow tube for that
A hollow needle 53 having a smaller diameter of the horizontal hole 54 and a plurality of hollow needles 53 has been proposed while keeping the inner diameter of the hole 55 large, but not only is the processing complicated but also the ink holding force is generated only in the horizontal hole 54 part. However, once the meniscus in the lateral hole 54 breaks, there is a problem that the holding power of the ink in the hollow needle 53 is lost.

Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to prevent ink from leaking from the print head side even when the ink container is pulled out, so that the ink inside the apparatus main body due to ink leakage can be prevented. There is no dirt.
Another object of the present invention is to provide a highly reliable ink jet recording apparatus in which air does not enter the ink flow path system.

[Means for solving the problem]

In order to solve the above problems, the present invention provides an ink jet recording apparatus in which a hollow needle is inserted into an ink container to supply ink from the ink container to a print head. The shaft and the hollow tube are formed of a separate member, and the shank is provided on the hollow tube side of the pointed end to form a deformed flow path.

[Action]

According to the present invention, since a deformed flow path can be formed in the hollow needle, a force for holding ink can be generated in the hollow needle.

〔Example〕

An embodiment of the present invention will be described with reference to the drawings. First
FIG. 1 is a sectional view showing an embodiment of the ink jet recording apparatus of the present invention. A print head 3 is provided integrally with a carriage 2 reciprocating along the platen 1 in the vicinity of the platen 1. Above the print head 3, there is provided an ink tank 7 in which a foam 6 made of a porous member such as polyurethane foam is housed. The ink tank 7 has a cover 8 provided with a vent hole 9 for allowing air to be taken in, and a trapezoidal projection 10 formed on the bottom surface for tight contact with the foam 6. . An ink chamber 11 for taking out and holding the ink in the foam 6 from the center of the projection 10 downward is formed. An end of the ink chamber 11 is sealed by a blind plug 12 made of an elastic member such as rubber. The ink impregnated in the ink tank is supplied to the print head 3 by inserting the hollow needle 5 communicating with the print head 3 through the blind plug 12 through the filter chamber 4. The ink chamber 11 is in a closed chamber state by the blind plug 12 and the foam 6.

FIG. 2 is a side view of the hollow needle 5 used in the present embodiment, and FIG. 3 is an explanatory view of the pointed tip of the needle. FIG. 4 is a sectional view of the hollow needle 5 as viewed from the axial direction.

The hollow needle 5 is composed of a hollow tube 15 and a pointed end 16 as shown in the figure. A side hole 18 is provided in a side wall of the hollow tube portion 15, and serves as an ink inlet. Point 16
Can be easily processed from a round material by lathing or the like. The pointed end 16 is made up of a needle-like portion 16a, a straight portion 16b, a press-fit portion 16c, and a shaft portion 17. The shank 17 and the inner wall of the hollow tube 15 form a deformed flow path 19. The hollow tube portion 15 is obtained by cutting a hollow tube material, and has a sharp end portion.
16 is integrated by press-fitting the press-fit portion 16c along the inner shape of the hollow tube portion 15. Further, the lateral hole 18 is processed before the above-described press-fitting because of removing burrs and the like generated during processing. The outer side of the lateral hole 18 is chamfered.

When the press-fitting method is not appropriate, for example, when the inner diameter of the hollow tube portion 15 is not high in accuracy, the groove 16d in FIG. 3 is provided in the press-fit portion 16c of the pointed end 16, and the hollow is aligned with the groove 16d. Even when the tube 15 is crimped, the pointed end 16 can be securely fixed to the hollow tube 15. As another method, it may be fixed by spot welding or an adhesive. In this embodiment, the hollow needle 5 is made of stainless steel and has an outer diameter of 0.8 to 1.3 mm.

The modified flow path 19 used in the present embodiment has an inner diameter of the hollow tube portion 15 of φ.
A desired ink holding power was obtained by setting the outer diameter of the shaft 17 to 0.7 to 1.0 mm and φ 0.3 to 0.7 mm. The shaft 17 and the side hole 18
It is needless to say that the irregularly shaped hole formed with the side portion can generate a greater ink holding force.

Further, according to the present embodiment, it was also confirmed that the shavings of the blind plug 12 were hard to enter into the hollow needle 5 pushed back by the shaft portion 17, and it was more blind than the conventional hollow needle 5 having a lateral hole shown in FIG. plug
It has a great effect on the mixing of 12 shavings.

〔The invention's effect〕

According to the present invention, the hollow needle is formed of the hollow tube portion and the tip end with separate members, and the ink container is pulled out by forming a deformed flow path between the tip end and the hollow tube portion. In this state, an ink holding force can be generated in the hollow needle. This prevents ink leakage even when the hollow needle is at a higher position than the print head, and also when transporting the main body of the ink jet recording apparatus, and prevents dirt in the apparatus and air from entering the ink flow path. It is possible to provide an extremely reliable ink jet recording apparatus that can prevent the ink jet recording apparatus. Further, since the hollow tube portion and the pointed end portion of the hollow needle are formed by different members, no special processing is required, so that the hollow needle can be provided at low cost. Further, there is a great effect that the outer diameter of the hollow needle can be freely selected.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the ink jet recording apparatus of the present invention. FIG. 2 is a side view of the hollow needle. FIG. 3 is an explanatory view in which a hollow tube portion of the hollow needle shown in FIG. 2 is cut. FIG. 4 is a sectional view of the hollow needle as viewed in a direction perpendicular to the axial direction. 5 and 6 are perspective views illustrating a conventional hollow needle. DESCRIPTION OF SYMBOLS 1 ... Platen 2 ... Carriage 3 ... Print head 5 ... Hollow needle 7 ... Ink tank 11 ... Ink chamber 12 ... Blind plug 15 ... Hollow tube part 16 ... Pointed end part 17 ... Shaft part 18 ... Side hole

Claims (1)

(57) [Claims] 1. An ink jet recording apparatus in which a hollow needle is inserted into an ink container to supply ink from the ink container to a print head, wherein the hollow needle has a hollow tube portion and a pointed end which are separate members. An ink jet recording apparatus, characterized in that a shaft portion is provided on the hollow tube portion side of the pointed end, and a deformed flow path is formed by the shaft portion and the hollow tube portion.