JPS5894473A - Ink-supplying device for ink jet recorder - Google Patents

Abstract

PURPOSE:To reduce the difference in ink pressure exerted on an ink jet head at the time of turning a carriage at both ends, by a method wherein a T-shaped branch pipe for supplying an ink is mounted on a carriage, an end of a rectangular part of the branch pipe is connected to an ink jet head, and the other two ends are connected respectively to ink tanks. CONSTITUTION:The T-shaped branch pipe 38 for supplying the ink is mounted on the carriage 15 of an ink jet printer, the end of the rectangular branch pipe 17 is connected to the ink jet head 16 mounted on the carriage 15, and the ends 18, 19 of other parts of the pipe 38 are connected respectively to ink-supplying tanks 20, 21 (or to an ink-supplying tank 25). The ends of the parts 18, 19 may be connected to separate ink tanks or connected to the same ink tank. When the separate ink tanks 20, 21 are used, it is preferable to provide a connecting pipe 24 for connecting the tanks directly to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ink supply device for an ink jet recording apparatus.

A typical type of inkjet head is an on-demand type inkjet head as shown in FIG. 1st
The figure shows an example of an inkjet head in which ink droplets are controlled by reducing the volume of a pressure chamber, and the ink droplet 1 is produced by a piezo element that mechanically vibrates in response to electrical input from an electrical signal source 3. It can only be controlled by 2. The ink chamber in the inkjet head has two divided ink liquid chambers, one outer chamber 4 and one inner chamber 6, and these chambers are connected to each other by a connecting passage 6. . The ink inlet passage 7 communicates with the outer chamber 4, and the outer chamber 4 is provided with an ink nozzle 8.

When the piezo element 2 is actuated by an electric impulse, the metal diaphragm 9 connected to the piezo element 2 is slightly displaced, causing ink to pass from the inner chamber 6 through the coupling passage 6 and into the ink liquid layer in the outer chamber 4. 9 and further extruded through an ink nozzle 8 to form an ink droplet 1. 1o is an air layer through which air is emitted from the nozzle 11. The effect of air flow is described in detail in Japanese Patent Application Laid-Open No. 109738/1983, and since it is not directly related to the present invention, the explanation will be omitted.

Ink supply in a flat scanning type recording device that scans an inkjet head having such a configuration within a plane and records one line or multiple lines in the horizontal direction is usually carried out by the second inkjet head.
The method shown in the figure is used. In the figure, 16 is a carriage that moves in the horizontal direction, and an inkjet head 16 is fixed on the carriage. Ink is supplied to the inkjet head 16 through a single pipe 19 led from the ink tank 2o. However, the horizontal movement speed of this type of recording device is 0.6 to 111 I/s.
high speed is required. Furthermore, when the carriage 16 is located at both ends, the speed must of course be set to zero.

For this reason, rapid acceleration is applied when turning back at both ends. Due to this acceleration, a pressure change occurs in the ink in the ink pipe 19 due to inertial force, and the ink pressure change is positive at one end and negative at the other end in the inkjet head 16, as shown in FIG. occurs. If the positive pressure change amount is large, there is a drawback that ink droplets are ejected from the nozzles 8 of the inkjet head 16 and remain on the recording paper surface as noise. On the other hand, if the amount of negative pressure change is large, air will enter the nozzle 8 of the inkjet head, causing problems such as unstable ink droplet ejection or inability to eject.

Furthermore, even if the amount of pressure change is small, it has a large effect on the ejection characteristics of ink droplets, causing fluctuations in the amount of ink ejection and changes in the state of ink droplet formation.

FIG. 4 shows a conventional method for alleviating the inertial force of ink within an ink pipe.

That is, the ink piping 19 is branched into two paths for the inkjet head 16, and two U-shaped pipings are combined to form a ring and arranged in a symmetrical shape, with the right end being longer than the left end of the ink piping 19. The distance is greater than the range of movement of the inkjet head 16. The opposite side of the inkjet head 16 is connected to the ink tank 2o. In such an ink supply system, it is said that the inertial force of the ink in the annular portion of the pipe 19 is canceled out on the left and right sides, so that changes in ink pressure are reduced. However, in reality, the pressure change generated in the annular portion 19 tends to remain within the annular portion 19, and since there is no place to absorb this pressure change, the pressure change is eventually transferred outward through the branch 13.14. It has the disadvantage that the pressure change from the branch part 14 is transmitted to the inkjet head 16,
At present, even the ink supply system shown in FIG. 4 has not been able to achieve sufficient effects.

The present invention has been made in order to solve the above-mentioned drawbacks, and provides an ink supply device with little pressure change to an inkjet head to obtain a stable recording state.
The porpose is to do.

FIG. 6 shows a first embodiment according to the invention.

The inkjet head 16 mounted on the carriage 16 is equipped with an ink supply pipe 17, and an ink pipe 18.1 branches left and right at right angles to the ink supply pipe 17.
There is a connection between 9 and 9. The ink pipes 18 and 19 are aligned in the direction of movement of the carriage 16 and partially bent into a U-shape to smooth the movement of the ink pipes. Ink piping 18.
19 has the same inner diameter, and the piping length, routing, etc. are symmetrical with respect to the ink supply pipe 17. (Other accessories are omitted in the figure.) With this configuration, if the carriage 16 is suddenly decelerated after moving in the C direction, the ink in the ink pipes 18 and 19 will be A directional inertial force acts, causing the ink to flow to the left. The pressure change caused by the flow of ink in the ink pipe 18 is transmitted to the end in the flow direction, and this flow acts to reduce the pressure in the ink supply pipe 1, but the ink flow in the ink pipe 19 acts to cancel out this drop, and the pressure change in the ink supply pipe 17 as a whole becomes extremely small. In order to allow the ink in the ink pipe 19 to flow quickly into the ink pipe 18, the inner diameters of the ink pipe 18 and the ink pipe 19 are designed to be the same and on a straight line. The ink supply pipe 17 is connected to the ink pipe 18
and 19 at right angles.This is because the pressure on the ink supply pipe 17 caused by the ink flow as mentioned earlier acts as static pressure, and conversely when the carriage 16 moves in the direction C. This is because similar pressure (static pressure) acts. Even if the inertial force is large, the static pressure is extremely small δ and remains approximately constant, so stability can be expected.

Therefore, pressure changes to the ink supply pipe 17 can be suppressed to a minimum, and the inkjet head 16 can also be kept stable.

By the way, in order to exhibit such an effect even more strongly, it is important to make the ink flow smoothly in the ink pipes 18 and 19, and to properly handle the ink flowing in one direction. For this reason, in the configuration shown in FIG. 6, the inflator 2Q is connected to the end of the ink pipe 19 to compensate for the ink flow due to inertial force when the carriage 16 moves in the direction C, for example. In this way, the ink flow can be sufficiently compensated for. On the other hand, an ink tank 21 is connected to an end of the ink pipe 18.

Since the capacity of the ink tank 21 is large, the speed of the ink flow transmitted through the ink pipe 18 due to inertial force is sufficiently reduced at this point and becomes stable. The ink tank 21 functions to buffer the ink flow.

When the carriage 16 moves in the C direction, the ink tanks 20, 21 perform opposite roles.

In this way, since the ink piping 18, 19 is not annular unlike the conventional one, pressure changes occurring in the ink piping will not remain in the annular portion and have an adverse effect. In addition, since ink tanks 20 and 21 can be connected to the ink piping on both sides, the ink flows.

Pressure changes are also completely absorbed here, and much better effects can be expected than before. In addition, both ink piping 19.18
Any number of inverters 20, 21 may be connected to the inverter 20, 21. In addition, the ink tanks 20 and 21 include the carrier IJ and the carrier IJ.
Regardless of the movement of 6, it remains fixed at a fixed location. Alternatively, only one of the ink pipes 19, 18 may be connected to the ink tank, and the other may be connected to the ink reservoir. The ink reservoir and ink tank are either in direct contact with the air, or are housed in an extremely soft bag so that the ink flows easily, and are also fixed in a fixed location. It is preferable. Note that the heights of the ink tanks 20° and 21 are the same. This is because if the heights of the ink tanks 20 and 21 are different, the ink will move to one side due to the head difference, and in extreme cases, the ink tank on the rich side will be nearly empty, and the ink tank on the lower side will be full. The ink tank's role is halved. This problem can be prevented by making the heights of the ink tanks 20 and 21 equal.

FIG. 6 shows another embodiment of the invention. Ink tank 21.20 connected to ink pipe 18.19
This is an example in which the two are connected by a thin tube 24.

For example, if one ink tank 2o is low on ink, and when replacing it with a new ink tank, if one ink tank 2o is replaced, the left and right ink tanks 2o
The ink amount of 0.21 is lost. thin tube 2
4 has the effect of quickly bringing such a state into a stable state.

FIG. 7 shows yet another embodiment of the present invention. This is an example in which the ends of ink pipes 18 and 19 are connected to the same ink tank 26. As already mentioned, the role of the ink tank 26 is to smoothly flow ink due to inertial force within the ink pipes 18 and 19, and to act as a buffer to absorb the flow of ink into the ink pipe 26. , compared to the capacity of the ink tank 26, the amount of ink flowing through the ink piping 18, 19 is extremely small. For this reason, even if the ink pipes 18 and 19 are connected to the same ink tank 26, the ink flows independently, and the problem of mutual interference does not actually occur.

If the distance between the connection ports of the ink pipes 18 and 19 connected to the ink tank 26 is made wider, there will be no problem of mutual interference, and the ink can be used independently of each other as in the embodiment shown in FIGS. 6 and 6. You can expect the same effect as if you M the tank.

By the way, if the fluid supply element of the prior application by the present applicant as shown in FIG. 8 is used for the branching part 38 of the ink supply device in FIGS. 6 and 7, the effect of reducing pressure fluctuations to the head 16 will be further It increases. The fluid supply element includes a first liquid passage 27, a second liquid passage 28, a narrow tube 29 connecting these liquid passages, and a supply passage 30 provided as a branch pipe on the path of the thin tube 29. Depending on the configuration, the cross-sectional area of the thin tube 29 near the supply path 30 is the same as the cross-sectional area of the ink pipe 18, 19,
Similar effects can be expected from the fluid supply element of the prior application filed by the present applicant as shown in FIG. In this fluid supply element, a first liquid chamber 31 and a second liquid chamber 32 having at least one opening are divided by two plates 33.34 facing each other, and a perforation is formed in the two plates 33.34. The first liquid chamber 31 and the second liquid chamber are connected through the gap 3B formed by the orifice 35.36 and the two plates 33. 32 are connected, and the gap 38 is in communication with at least one opening 37 of the orifice 35, 369% (D).

As described above, in the ink supply device of the inkjet recording apparatus according to the present invention, the ink supply pipe connected to the inkjet head is connected at right angles to the ink pipes branching in the left and right direction, and the ends of the left and right ink pipes have ink tanks, respectively. (One side may be an ink reservoir) is connected, and the inkjet head and part of the ink piping move as the carriage moves, so the ink inertia in the ink pipe as the carriage moves. Pressure changes due to force can be sufficiently alleviated within the ink tank, and pressure changes to the inkjet head can also be kept extremely low. Therefore, it is possible to provide an inkjet recording device that can perform stable recording even in a plane scanning type recording device or the like in which the carriage moves at an extremely high speed.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an inkjet head used in the present invention, FIG. 2 is a schematic configuration diagram of a conventional ink supply device, FIG. 3 is an explanatory diagram of the change in pressure, and FIG. FIGS. 6 and 7 are block diagrams showing embodiments of the ink supply device according to the present invention, and FIGS. 8 and 9 are schematic diagrams showing the fluid supply used in the present invention, respectively. FIG. 3 is a cross-sectional view of the element. 16...Charge, 16...Inkjet head, 17...Ink supply pipe, 18,1
9... Ink piping, 20, 21. 26...
...Ink tank, 24...-tube. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 7 Figure 2 Figure 3 Tomo, Shoulder-EI Figure 4 Figure 8 Figure 9

Claims (1)

[Scope of Claims] (1) An ink supply pipe connected to an inkjet head fixed to a carriage is connected at right angles to ink piping that branches left and right, and as the carriage moves, the inkjet head and the ink piping are connected at right angles. 1. An ink supply device for an inkjet recording device, characterized in that a part of the ink supply device is configured to move. (2) At least one ink tank is connected to one ink pipe, and at least one ink tank or ink reservoir is connected to the other ink pipe, and the ink tank and ink reservoir are fixedly installed. An ink supply device for an inkjet recording apparatus according to claim 1, characterized in that: @) The ink supply device for an inkjet recording apparatus according to claim 2, wherein each ink tank or the ink tank and the ink reservoir are installed at the same height. (4) The ink of the inkjet recording device according to claim 2 or 3, characterized in that each ink tank or an ink tank and an ink reservoir are connected by a thin tube. Feeding device. (5) An inkjet recording apparatus according to claim 1, wherein the ink pipes branching to the left and right are connected to the same ink pipe.