JPS59101370A - Ink-suppy pump - Google Patents

Abstract

PURPOSE:To damp ink pressure pulsation and miniaturize the device, by actuating a pump supplying ink to an ink jet head with electrostrictive vibrator. CONSTITUTION:Employing an electrostrictive vibrator 21 onto a pump 2 for supplying ink from an ink tank 1 to an ink jet head 5 with pressure, a portion of an ink-pressurizing chamber is formed by the electrostrictive vibrator 21. For example, when the pressurizing chamber is formed by closing both ends of the cylindrical electrostrictive vibrator 21, and a driving powder source 23 is connected to its driving electrodes 22a, 22b, the electrostrictive vibrator 21 is deprived of radial pulsating vibration and by installing check valves 13, 14, ink is allowed to be fed under pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ink supply pump that is small in size, has little pressure fluctuation, and has a long life for use in a charge amount control type inkjet recording apparatus.

First, FIG. 1 shows a schematic configuration diagram of a charge amount control type inkjet recording apparatus. In the figure, 1 is an ink tank, 2
is an ink supply pump, 3 is an air chamber, 4 is a nozzle, 5 is a vibrator attached to the nozzle 4, 6 is a charging electrode,
7II and 7b are deflection electrodes to which a constant voltage is applied, 8 is a gutter, 9 is an ink droplet array, and 10 is a recording sheet. next,
To explain its operation, the ink in the ink tank 1 is pressurized by the ink supply pump 2, and the air chamber 3 is pressurized by the ink supply pump 2.
After removing the pulsation, the liquid is injected from the nozzle 4.

The ejected ink is given vibration by the vibrator 5,
A regular train of ink droplets 9 with a period identical to the vibration period is generated. Next, this ink droplet is selectively charged according to the recording information by the charging electrode 6, and further deflected according to the amount of charge by a constant electric field between the deflection electrodes 7a, 7b, so that it is placed at a predetermined position on the recording paper 10. Collision with and record.

Furthermore, unnecessary ink droplets that are not used for recording are not charged by the charging electrode 6, but go straight and are collected by the gutter 8, returned to the ink tank 1, and reused.

The ink supply pump 2 used for such charge amount control type inkjet recording has an ink pressure of 3 to 4 kg.
A high-pressure, low-flow pump with an ink flow rate of about 1ce10 is required for A-m2, and a plantar pump as shown in FIG. 2 has conventionally been used. In FIG. 2, 11 is a reciprocating planter, 12 is an ink pressurizing chamber, 13 is a discharge check valve, 14 is a suction check valve, and 15 is a seal.

Next, to explain the operation of the plansha pump, when the plunger 11 is moved in the direction of the arrow ■ by a drive source (not shown), the ink in the ink pressurizing chamber 12 is pumped by the plansha 11.
The discharge check valve 13 is opened and the air is discharged into the air chamber 3 (see FIG. 1).

On the other hand, when the plunger 11 is moved in the direction of the arrow ■, negative pressure is generated in the ink pressurizing chamber 12, the suction check valve 14 opens, and the ink in the ink tank 1 (see Fig. 1) is suctioned. Ru. In this way, by reciprocating the plunger 11, the ink in the ink tank 1 is pressurized and ejected to be supplied to the nozzle 4.

Here, the drive source for reciprocating the syringe 11 may be a combination of a rotary motor 16 and a cam 17, as schematically shown in FIG. 3, or a drive source that is schematically shown in FIG. Conventionally, a magnet coil 2o that directly drives the plunger 11 has been used. In FIGS. 3 and 4, the same functional parts as in FIG. 2 are given the same reference numerals. Reference numeral 18 indicates a pressure adjustment spring, and 19 indicates a pressure adjustment screw. However, in these plant pumps, the ink ejection cycle is from several Hz to several tens of Hz, and therefore the amount of ink ejection is large, resulting in large ink pressure pulsations.In order to reduce this, large air pumps are required. It had the disadvantage of requiring a chamber, etc. Furthermore, since the drive source and the ink pressurizing chamber are separate, there is a drawback that the entire apparatus becomes large when a plurality of ink supply pumps are required, such as in color recording. Furthermore, since mechanical sliding motion such as reciprocating motion of the plunger is required, it is difficult to extend the service life due to wear of parts.

In order to reduce the pulsation of ink pressure, the plunger pump applies pressure and
Although an ink supply pump capable of ejecting ink has been proposed, the ink ejection frequency is at most twice as high, making it difficult to significantly downsize the air chamber 3.

Furthermore, in order to eliminate pulsations in ink pressure, an ink supply pump has been proposed in which the planter 11 of the planter pump is driven continuously during recording, but it is difficult to maintain the ink pressure constant. There was a certain drawback.

Unfortunately, as another method to eliminate ink pressure pulsations, an ink supply pump that uses compressed gas has been proposed, but it is small and requires separate installation of a compressed gas cylinder and pressure adjustment valve. There was a drawback that it was difficult to convert.

In order to eliminate such conventional drawbacks, the present invention uses an electrostrictive vibrator as a drive means for the pump, and is configured such that the electrostrictive vibrator forms a part of the ink pressurizing chamber. This is designed to reduce pressure pulsation and downsize the pump. An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 5 is a sectional view showing an embodiment of the ink supply pump of the present invention, and the same functional parts as in FIG. 2 are given the same reference numerals. In the figure, 21 is a cylindrical electrostrictive vibrator, 22a, 2
2b is a driving electrode of the cylindrical electrostrictive vibrator 21, 23 is a driving power source, and 24 is an ink (5) pressurizing chamber housing.

Next, to explain its operation, when the driving power source 23 is connected to the driving electrodes 22a and 22b of the cylindrical electrostrictive vibrator 21, the cylindrical electrostrictive vibrator 2 moves as shown by the arrow in FIG. Perform breathing vibrations in the radial direction. At this time, the side surface of the ink pressurizing chamber housing 24 that is in contact with the inside of the cylindrical electrostrictive vibrator 21 also vibrates, so that the vibrator 21 moves in the direction of the arrow (■).
Tsumashi ink pressure chamber 12. When the ink is vibrated to reduce the ink, the ink in the ink pressurizing chamber 12 is pressurized and is ejected through the ejection check valve 13. Conversely, when the vibrator 21 vibrates in the direction of the arrow ■, negative pressure is created in the ink pressurizing chamber 12.
Ink flows in from the suction check valve 14 . In this embodiment, since the ink pressurizing chamber 12 is provided inside the cylindrical electrostrictive vibrator 21, the size of the entire pump is approximately the same as that of the vibrator 21.
becomes. In addition, the electrostrictive vibrator 21 can be easily driven at several hundred Hz or more, and the ink ejection period can be reduced, so the amount of ejection per time can be reduced, and the ink pressure pulsation can be reduced. A small one is sufficient (6).

FIG. 6 shows another embodiment of the present invention, in which the same functional parts as in FIG. 5 are given the same reference numerals.

□ In the figure, 25 is a flat electrostrictive vibrator whose longitudinal ends are fixed, and 26 is a fixed plate. It is located inside. To explain its operation, when the flat electrostrictive vibrator 25 is driven by the drive power source 23 so as to extend in the longitudinal direction, the vibrator 25 bends because both ends are fixed. In this case, since the fixed plate 26 is provided on one side of the vibrator 25, the vibrator 25 is bent in the direction of the arrow ■ in the figure, so the ink in the ink pressurizing chamber 12 is pressurized, and as shown in the figure. It is discharged through a specific discharge check valve. Well, when you stop driving the vibrator 25,
Since the vibrator 25 returns to its original state, there is no negative pressure in the ink pressurizing chamber 12, and ink is sucked into the ink tank via a suction check valve (not shown). In this way, ink can be pressurized and ejected by repeatedly driving the flat electrostrictive vibrator 25.

As explained in detail above, in the present invention, a part of the ink pressurizing chamber is formed by an electrostrictive vibrator, which is a driving element of the pump, so that the pump can be made compact, and
By reducing the ink ejection period, pulsations in ink pressure can be significantly reduced, and the air chamber can be made smaller.

Because we use an electrostrictive vibrator as the drive element of the pump, the ink pressure determines the amplitude of the vibrator.7
The ink pressure can be easily controlled by the pulse width or pulse voltage, and since there are no mechanical sliding parts, there is no wear and tear, resulting in a long service life. It has effects such as being easily realized.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a charge amount control type inkjet recording device, FIGS. 2, 3, and 4 are schematic configuration diagrams of a conventionally used plunger pump, and FIG. 5 is an ink supply pump of the present invention. FIG. 6 is a sectional view showing one embodiment of the present invention, and FIG. 6 is a perspective view showing another embodiment of the present invention. 12... Ink pressurizing chamber, 13... Discharge check valve, 1
4... Check valve for suction, 2... Cylindrical electrostrictive vibrator, 2
2a. 22b... Drive electrode, 23... Drive power source, 24
... Ink pressurization chamber housing, 25 ... Flat electrostrictive vibrator, 26 ... Fixing plate. (9)

Claims (1)

[Claims] In an ink supply pump used in a charge amount control type ink jet recording device that performs recording by selectively charging and deflecting ink droplets ejected from a nozzle according to recording information,
1. A device for supplying ink, characterized in that an electrostrictive vibrator is used as a pump driving means, and the electrostrictive vibrator is provided so as to form a part of an ink pressurizing chamber. pump.