JPS60264255A - Liquid supply apparatus - Google Patents

Abstract

PURPOSE:To make it possible to miniaturize the whole of the titled apparatus and to enhance the durability thereof while enabling the stable injection of a liquid, by communicating a liquid jet head and a main tank by a liquid supply flexible tube and employing a spiral structure in the bent part of the tube. CONSTITUTION:A plurality of tubes 9 each having a spiral structure are integrated so as to form a flat band shape and arranged in one side of a carriage 1 in the reciprocal driving direction of said carriage 1 so as to position the flat surface thereof in the vertical direction. Because the flexible tubes 9 are rich in flexibility, the arbitrary arrangement requiring a min. space is enabled by arranging said tubes 9 in a concentric circular or tubular form. Each flexible tube 9 having the spiral structure is extremely large in the degree of freedom of motion to bending or the change in radius of curvature and enhanced in its durability. The generation and propagation of a pressure wave by the driving of the carriage are prevented to make it possible to reduce the adverse effect imparted to the injection of a liquid and the miniaturization and durability of the apparatus also become excellent.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a liquid supply device, and more specifically, in a liquid jet recording device in which a liquid jet head is mounted on a reciprocating carriage, a liquid such as ink is supplied to the liquid jet head. This invention relates to a liquid supply device that supplies liquid.

[Prior art]

Conventionally, in a liquid jet recording device, one or more liquid jet nozzles and a sub-tank for supplying liquid to each nozzle are mounted on a carriage that is driven back and forth, and these sub-tanks and a sub-tank are provided outside the carriage. A structure in which a flexible tube is used to connect the tank to the main tank is known.

The flexible tube used in this type of device is bent into a U-shape and placed inside the device so that it can freely follow the movement of the carriage.

That is, as the carriage moves, the flexible tube moves within the apparatus while changing the curvature of its bent portion.

Therefore, a very large space is required for the flexible tube to deform and move freely without getting caught in other driving parts or mechanical parts, which is an obstacle to downsizing the entire unit. Ta.

Therefore, as shown in Japanese Patent Application Laid-open No. 58-208061, for example, a plurality of flexible tubes are bundled into a flat band shape, and this flat surface is located in the vertical direction and is located on one side of the reciprocating direction of the carriage. It has been proposed that the structure be located at

FIG. 1 shows an example of this type of device.

That is, the reference numeral 1 in the figure is a carriage on which a sub-tank 3 is mounted, and a liquid injection nozzle (not shown) is attached to this carriage 1 so as to face the platen 4.

The carriage 1 is slidably fitted to two guide bars 2, 2, and is fixed in the middle of an endless belt 7 stretched between a driven pulley 5 and a driving pulley 6.

Since this drive pulley 6 is fixed to the output shaft 8a of the motor 8, it rotates in a positive direction as the motor 8 rotates.

The carriage 1 is rotated in the opposite direction, and the carriage 1 is driven back and forth along the platen 4.

On the other hand, one end of a plurality of flexible tubes 9 for supplying liquid into the sub-tank 6 is connected to the back surface 6a of the sub-tank 6. At this time, the plurality of flexible tubes 9 are held in a flat band shape near the end on the sub-tank 3 side by the support part 3b formed integrally with the sub-tank 3, and the other end side is not shown. Similarly, it is held in a flat band shape by a supporting portion 10 protruding from the frame of the device, and is connected to a main tank (not shown).

Between the support parts 3b and 10, the flexible tube 9 is integrated into a flat band shape by adhesion or welding, and the flat surface is located in the vertical direction, and the carriage 10
It is arranged so as to be bent in a U-shape on one side in the running direction.

This bent portion is indicated by reference numeral 9a.

The reference numeral 11 designates a flexible printed circuit board that communicates between the carriage 1 and a control circuit (not shown). It is constructed and arranged so that it can be moved.

In the above configuration, since the plurality of flexible tubes 9 are integrated into a band shape and their flat surfaces are located in the vertical direction, the vertical rigidity is increased and the space for accommodating the flexible tubes 9 is narrow. However, if the curvature of the bent portion 9a changes as the carriage travels, pressure fluctuations will occur in the liquid within the tube.
There was a drawback that the stability of the liquid jetting state was adversely affected.

In particular, if the liquid filling capacity in the sub-tank 3 is small, this pressure fluctuation may cause air to enter from the nozzle tip or cause more liquid to be ejected from the nozzle tip than necessary, resulting in a decline in the quality of the recording screen. Ta.

Therefore, as shown in FIG. 2, a method has been proposed in which the capacity of the sub-tank 3 is increased and pressure fluctuations are dispersed and absorbed into the liquid within the sub-tank 3.

In addition, in FIG. 2, the reference numeral 13 is a nozzle.
4 is a piezo element, 15 is a liquid flow path, 16 is a filter, 17
18 is a liquid such as ink, and 18 is a recording paper.

However, the capacity of the sub-tank O is increased and liquid light r is used.
) Increasing the filling capacity not only increases the size of the device, but also increases the load on the carriage 1 on which the sub-tank 3 is mounted and the motor 8 for driving the carriage, resulting in a problem that the durability of the motor decreases. .

Furthermore, since the straight flexible tube 9 is bent and its curvature constantly changes during use, the difference in curvature between the outside and inside of the flexible tube 9 causes a stress difference on the tube wall surface. Another disadvantage was that the durability of the flexible tube was reduced.

By the way, in general, the propagation velocity (sound velocity) Vl of a pressure wave in a fluid is given by the following equation.

■1-1//[Rho: fluid density, β: compressibility, that is, the propagation velocity v1 under a constant temperature is always constant for each fluid.

Also, when high or low pressure suddenly occurs in a part of a pipe filled with a certain fluid, this pressure fluctuation becomes a pressure wave that propagates inside the pipe. The velocity (2) is expressed by the following equation, taking into account the elasticity of the fluid and the elasticity of the pipe wall material.

ρ: Fluid density, K: Bulk elastic modulus of fluid E: Longitudinal elastic modulus of tube wall material D: Inner diameter of tube, S: Thickness of tube wall, that is, increase the inner diameter of the tube and decrease the thickness S of the tube wall. For example, the propagation speed V2 of the pressure wave is reduced, and the influence of pressure fluctuations in the liquid inside the tube due to rapid bending or curvature changes of the flexible tube on liquid jetting can be reduced.

By the way, the amount of liquid ejected from the liquid ejecting head is 1×
When the flow rate is about 10-41 m/sec or less and the inner diameter of the liquid supply tube is about 1 crn or less, the liquid flowing inside the tube becomes a laminar flow, so the Hagen-Poiseuille law is satisfied as shown by the following equation. holds true.

D: inner diameter of the pipe, μ: viscosity coefficient l: pipe length, ΔP: pressure difference between both ends of the pipe, that is, when the inner diameter of the pipe is increased, the propagation speed v2 of the pressure wave decreases as described above, At the same time, the pressure fluctuation causes an increase in the amount of liquid flowing inside the pipe, resulting in a problem that stable liquid jetting cannot be obtained.

Therefore, attempts have been made to reduce the flow rate Q by increasing the pipe length l, but in reality, when the carriage moves back and forth, excess flexible tubes concentrate near the carriage. In order not to interfere with the operation of the mechanical parts of the device, a large space is required, resulting in an increase in the size of the device.

Further, when the thickness of the tube wall of the flexible tube is reduced, the propagation speed of pressure waves is reduced, but there is also the drawback that the durability of the flexible tube itself against bending motion is reduced.

〔the purpose〕

The present invention was made in order to eliminate the above-mentioned drawbacks of the conventional device, and it realizes miniaturization of the entire device, improves the durability of the flexible tube and motor, and provides a liquid supply that enables stable liquid jetting. The purpose is to provide equipment.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 3 illustrates one embodiment of the present invention. In this figure, the same or corresponding parts as in FIGS. 1 and 2 are denoted by the same reference numerals, and the explanation thereof will be omitted.

In the present invention, the bent portion 9b of the flexible tube 9
Adopts a spiral structure.

In this embodiment, the plurality of flexible tubes 9 having a spiral structure are integrated into a flat band shape.
The flexible tube 9 of the present invention, which has a helical structure and is arranged on one side of the reciprocating drive direction of the carriage 1 with its flat surface positioned in the vertical direction, has more flexibility than a straight tube. Therefore, it is possible to arrange them in any way that requires a minimum amount of space, such as in a circular or tubular arrangement.

Note that the reference numeral 12 is a main tank that supplies liquid to the flexible tube 9.

Flexible tube 9 having a spiral structure according to the present invention
The degree of freedom of movement with respect to bending and curvature changes is extremely greater than that of straight tubes, and the curvature changes accompanying the movement of the carriage 1 and the load applied to the flexible tube 9 itself during movement are due to the movement of the coil spring in the helical structure part. Since it is converted into a smaller size, durability can be improved.

In addition, by adopting a spiral structure, it is possible to obtain flexibility even for multi-layered tubes and thick-walled tubes, which could not be used in the past due to their lack of flexibility, resulting in even more durable flexible tubes. be able to.

Furthermore, by employing the spiral structure in the flexible tube 9, pressure fluctuations applied to the tube can be absorbed to some extent, and at the same time, the propagation speed of the pressure (10) waves can be reduced.

Even if the inner diameter of the flexible tube is increased to a certain extent, the spiral structure allows the tube to be sufficiently long, making it possible to maintain the liquid flow rate to a certain degree.

In addition, by adopting a spiral structure for the flexible tube 9 and giving the tube a gentle curvature,
Separation of streamlines from the inner wall surface of the tube, friction on the wall surface, and generation of secondary flow are promoted for the liquid in the tube, and the energy of the pressure wave propagating in the fluid is absorbed, producing a bullet wave effect. be able to.

As described above, it is possible to suppress the generation and propagation of pressure waves due to external shocks and the reciprocating drive of the carriage 1.
Stable liquid injection can be obtained without increasing the capacity of sub-tank B.

Therefore, the sub-tank 3 mounted on the carriage 1 can be extremely downsized or even eliminated, and the load on the carriage drive motor 8 can be reduced and the device can be downsized.

〔effect〕

As is clear from the above description, according to the present invention, a spiral structure is adopted for the bent part of the flexible tube that supplies liquid to the liquid jet. Therefore, it is possible to obtain a liquid supply device that is small in size and has excellent durability, which can prevent the adverse effects on liquid jetting and effectively utilize a narrow space.

[Brief explanation of the drawing]

1 and 2 illustrate a conventional structure; FIG. 1 is a perspective view; FIG. 2 is a vertical cross-sectional side view of a sub-tank and a liquid jet head; and FIG. 3 is a perspective view illustrating an embodiment of the present invention. It is a diagram. 1... Carriage 3... Sub-tank 5...-driven pulley 6... Drive pulley, 7... Belt 8...
・Motor 9...Flexible tubes 9a, 9b...Bending portion 293

Claims (1)

[Claims] In a liquid supply device used in a liquid jet recording device that has a liquid jet head mounted on a reciprocating carriage,
The liquid ejecting head and the main tank are connected by one or more flexible tubes for liquid supply, and a spiral structure is adopted in a portion of the flexible tube that bends when the carriage is driven back and forth. liquid supply device.