JPS63256451A - Ink supply device - Google Patents

Abstract

PURPOSE:To inhibit the fluctuation of pressure in the ink contained in an ink supply tube which occurs when a head is scanning, accelerating, or decelerating and to prevent an ink drip from being unnecessarily discharged out of a nozzle and a bubble from being fed into a flow path, by providing a fluid control valve consisting of a film serving as an ink supply path closing valve and a spheroidal movable element having a function of deforming the film. CONSTITUTION:A fluid control valve 8 consists of a holder part 12 containing a spheroidal movable element 11 made of a rigid body and an ink flow path closing part 14 which is provided with an ink flow path and partially made of a deformable polyethylene film 13. When a head 5 is scanning at a constant speed, the movable element 11 is positioned at the center of the holder part 12, thus never closing the ink flow path. When the head in the quiescent condition starts scanning, or returns in the reciprocating scanning, an acceleration occurs in the head 5. Then, the movable element 11 presses the polyethylene film 13 and is held in this state, thus cutting off the ink flow path.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ink supply device for an inkjet recording device that records ink on a recording medium by scanning with a head.

(Prior Art) Conventionally, as a method for controlling pressure fluctuations occurring in an ink supply pipe, a method has been announced in which a solenoid valve is provided in the ink supply pipe to open and close the ink supply. In addition to being very expensive, it also had the drawbacks of being difficult to control.

(Problems to be Solved by the Invention) In an ink-on-demand type inkjet head, it is necessary to maintain the meniscus of the nozzle, which is an ink ejection opening, in a stable state at all times. When the ink supply tube connected to the head reciprocates as the head scans, ink pressure fluctuations occur within the ink supply tube. When this pressure fluctuation is propagated to the head, the meniscus of the nozzle becomes unstable, causing phenomena such as ejecting unnecessary ink droplets or drawing in air bubbles, resulting in the inability to print. In other words, when the ink pressure generated in the ink supply tube acts as a positive pressure on the head, the ink is pushed out from the nozzle and printed as unnecessary droplets on the recording paper. Conversely, if the ink pressure acting on the head becomes more negative than necessary, the meniscus is drawn into the flow path of the head and mixed into the pressure chamber as bubbles. If bubbles exist in the pressure chamber, the pressure waves of the ink generated by the piezoelectric element will be absorbed by the bubbles, and the pressure will not propagate to the ink, or cavities will occur, making it impossible to eject ink droplets. Therefore, the ink pressure applied to the head must always be kept constant.

(Means for Solving the Problems) The present invention provides a fluid control system comprising a film that fogs a valve that opens and closes an ink supply path, and a spherical movable rope made of a rigid body that deforms the film. A feature is that a valve is provided between the head and the ink supply pipe.

(Function) The object of the present invention is to determine the scanning adjustment of the head i1! The purpose of this invention is to suppress the pressure fluctuations of ink within the ink supply bacteria that sometimes occur, and to prevent unnecessary ink droplets from being ejected from the nozzle and air bubbles from entering the flow path.

(Example) Hereinafter, the details of the present invention will be explained based on the drawings.

FIG. 1 is a schematic diagram of an inkjet recording apparatus showing an embodiment of the present invention.

The timing belt 2 moves due to the rotation of the motor 1,
A carriage 4 supported by a support rod 3 moves in the scanning direction together with the head 5. Ink is in ink cartridge 6
The ink is supplied from the ink through the ink supply tube 7 to the head, and the ink is supplied by capillary action without applying pressure. In the present invention, a fluid control valve 8 is provided between the ink supply pipe 7 and the head 1, so that the ink supply path is closed during acceleration and deceleration of head scanning, and ink pressure fluctuations are prevented from propagating to the head. FIG. 2 is a cross-sectional view of the fluid control valve. A spherical movable element 11 made of a rigid body, a holder part 12 with a conical interior into which the movable element is placed, and a 20 to 50 μml holder with an ink flow path formed and partially deformable!
A fluid control valve is formed by the X-sized polyethylene film 13 and the ink flow path opening/closing part 14.

In this device, when the head is scanning at a constant speed, the movable element 11 is located at the center of the holder part 12 and does not close the ink supply path.When scanning starts from a state where the head is stationary, and When the head returns during reciprocating scanning, acceleration is always generated in the head. When acceleration occurs, a force acts on the movable element, and the spherical movable element 11 rolls on the slope of the holder and is held against the polyethylene film, thereby blocking the ink supply path. When the head scans at a constant speed, the spherical movable element rolls again on the slope of the holder due to the m force and returns to its original position. Assuming that the acceleration generated when the head scans is a, the angle θ of the slope that can be rolled due to the acceleration can be expressed by the following equation.

tan θ = α / g g: m force acceleration For example, considering a fluid control valve that shuts off the ink supply path when an acceleration of α = tg occurs, the angle θ of the holder slope is θ = 45°. do it.

The most important feature of this fluid control valve is that because the movable element is not directly in the ink, it is not affected by the fluid resistance and surface tension of the ink, and it can accurately respond to the forces generated by the acceleration and deceleration of the head. In response to this, the ink supply path could be reliably opened and closed, and the ink pressure fluctuations occurring in the ink supply pipe were propagated to the head.

In addition, by using a deformable film in a part of the ink supply path, it is possible to obtain a damper effect that suppresses minute pressure fluctuations caused by jitter and temporary vibrations of head scanning, and the pressure applied to the head is reduced. It can always be kept constant.

Further, in order to prevent the film from sticking to the opening/closing portion of the ink supply path, it is possible to provide a coil spring 16 or a plate spring, thereby allowing smoother opening/closing.

(Effects of the Invention) As explained above, the present invention forms a fluid control valve by combining the movable element of the ball and the elastically deformable film, and provides the fluid control valve between the head and the ink supply pipe. This ink supply device is characterized by opening and closing the ink supply path during acceleration and deceleration of head scanning, which sufficiently alleviates ink pressure fluctuations and enables stable printing.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an inkjet recording apparatus of the present invention, FIG. 2 is a sectional view of an ink supply device in an embodiment of the present invention, and FIGS. 3(a) and 3(b) are An enlarged view of the opening/closing part, (a) is a diagram showing the state when the ink flow path is closed, (
b) is a diagram showing when the ink flow path is open. 5... Head, 8... Fluid control valve, 9... Recording paper, 10... Platen, 11... Movable element,
13... Film, 15... Ink supply path, 16.
...Spring Figure 2. Figure 3

Claims (1)

[Claims] In an ink-on-demand type inkjet recording device, a fluid control valve is formed by combining a spherical movable element made of film and a rigid body at the connection between the ink supply pipe that supplies ink from an ink cartridge storing ink and the head. The fluid control valve is configured such that the movable element fuses with the film to close the ink supply path during acceleration and deceleration of the scanning operation of the head, and the movable element separates from the film and supplies the ink supply at constant speed. An ink supply device characterized in that it is controlled to open.