JPH06126958A - Inkjet printer - Google Patents

Abstract

(57) [Summary] [Object] To provide an inkjet printer capable of preventing nozzle clogging and print density unevenness and capable of continuously performing a print operation without interruption. A through hole is provided in the ink flow path plate 12, and a pumping unit 14 is bonded to the through hole. The pumping unit 14 is composed of a vibrating plate in which a piezoelectric element and an epoxy resin are bonded together, and mechanically vibrates by oscillating a drive circuit to pass the ink 3 in the low-side ink chamber 7 through the check valve 8 and high. It is moved to the side ink chamber 6. If the pumping unit 14 is further vibrated,
The ink 3 is sucked from the high-side ink chamber 6, and the array 15
Is returned to the low-side ink chamber 7 via.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer.

[0002]

2. Description of the Related Art Conventionally, in a liquid-type ink jet printer, ink stays in the vicinity of nozzle holes when the printer body is not operating, so that the ink density in that portion becomes high,
In some cases, the toner may be solidified, which causes uneven printing density or misjet due to clogging.

Therefore, in the printer, at the time of printing at the time of start-up and immediately after rest, the ink having a high density near the nozzle holes is absorbed by the ink absorber installed or discharged. , The defects at the start of printing were reduced.

Further, hot melt type ink jet printers have been developed in order to solve the drawbacks of liquid type ink jet printers, but in most of them, the main component of the ink is a paraffinic organic substance, and the pigment component is suspended therein. Therefore, if the molten state is kept for a long time, the pigment component is precipitated, which causes unevenness in printing density.

Furthermore, in order to prevent the precipitation of the pigment component, a print head comprising two ink chambers having a nozzle, a piezoelectric element, an ink circulation path, and a check valve is installed on a carriage installed in the printer. As a means for oscillating right and left and giving an acceleration at that time, there is also one that circulates the ink by imparting a height difference to the ink between the two ink chambers.

[0006]

However, in the method for preventing the precipitation of the pigment component in the conventional ink jet printer as described above, an operation different from printing such as rocking the print head left and right is periodically performed. However, there is a drawback that printing cannot be performed during that time.

The present invention has been made to solve the above-mentioned problems, and it is possible to prevent clogging of nozzles and uneven density of printing and to continuously perform printing without interruption. The present invention aims to provide a new inkjet printer.

[0008]

In order to achieve this object, an ink jet printer of the present invention comprises a nozzle plate for ejecting ink, an array having a first piezoelectric element for applying ejection pressure to the ink, An ink chamber that stores the ink and supplies the ink to the array, an ink flow path plate that connects the ink chamber and the array, and an ink voltage plate that is disposed in the ink flow path plate And a second piezoelectric element that circulates the ink in the ink flow path plate by vibrating with it.

[0009]

According to the ink jet printer of the present invention having the above construction, the ink is first introduced into the ink chamber, and the vibration of the second piezoelectric element due to the applied voltage causes the ink to flow through the ink flow path plate to the array. Is led. Then, the ink is ejected by the first piezoelectric element incorporated in the array, and the excess ink returns to the ink chamber through the ink flow path plate.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a main part of an ink jet printer to which the present invention is applied. In FIG. 1, an inkjet printer head 1 is fixedly disposed on a carriage (not shown), and is configured to move left and right on a carriage bar (not shown) together with the carriage.

An ink tank 2 is installed above the side of the ink jet printer head 1, and there is about 3 ink tanks.
0 cc of ink 3 is stored. The ink 3 is
An ink supply tube 4 having an inner diameter of 2 mm and made of a flexible polyamide resin is connected to the ink chamber 5 of the inkjet printer head 1.

The ink chamber 5 has a thickness of 1 to reduce the weight.
It is made of a 0 mm magnesium alloy, and is divided into a high-side ink chamber 6 and a low-side ink chamber 7 with a head difference. A check valve 8 using a metal ball having a diameter of 4 mm is arranged between these two chambers so as to prevent the backflow of the ink 3.

Further, the low-side ink chamber 7 has a built-in liquid level sensor 9 to which a glass-sealed thermistor is applied. When the low-side ink chamber 7 runs out of ink, the liquid level is lowered. By detecting that the ink is present and operating the control means (not shown) based on it, a predetermined amount of ink is supplied from the ink tank 2 through the ink supply tube 4. The ink chamber 5 is sealed by a cover plate 10 made of a magnesium alloy and having a thickness of 2 mm, and a filter unit 11 having a glass fiber HEPA filter for preventing dust from being mixed therein is arranged on an upper portion thereof. ing.

Although the check valve 8 is a metal ball valve in this embodiment, it may be a check valve using a metal or resin plate. Further, although the filter unit 10 uses the HEPA filter in this embodiment, a stainless mesh filter having an opening of about 5 μm may be used.

On the printing surface side of the ink chamber 5,
An ink flow path plate 12 made of magnesium alloy and having a thickness of 3 mm is arranged. The ink flow path plate 12 is formed with two ink flow paths 13, 13 having a depth of 1 mm as shown in the drawing, and this portion is always filled with ink. A through hole having a diameter of 12 mm is provided in an intermediate portion of each of the two ink flow paths 13 and 13, and a pumping unit 14 is provided therein. An array 15 of 30 mm × 40 mm, which controls the ink ejection mechanism, is arranged above the ink flow path plate 12.

FIG. 2 is a front view of an ink jet printer head used in the ink jet printer of the present invention. In FIG. 2, the array 15 has a nozzle plate 16 made of nickel and having 48 nozzle holes with a hole diameter of 50 μm, which are formed at an equal pitch at a predetermined angle. There is a furniture.

FIG. 3 is a side view of an ink jet printer head to which the present invention is applied. In FIG. 3, the array 15 is composed of the nozzle plate 16 and an array plate 17 made of 42 alloy and a first piezoelectric element 18 made of PZT ceramics. The array plate 17 is a laminated body composed of several solder-plated plates, and the nozzle plate 16 and the first piezoelectric element 18 are joined together by using heating means to form the array 15. ing. Grooves are formed in each plate constituting the array plate 17 by etching or punching, and the ink 3 is supplied or circulated in the grooves.

The first piezoelectric element 18 has a mechanism capable of mechanically displacing when a signal is applied by a drive circuit (not shown) to generate a pressure enough to eject an ink droplet. 2 and 3, the pumping unit 14 is bonded to the through hole of the ink flow path plate 12 so that the second piezoelectric element 20 is on the outer side and the vibration plate 21 is on the inner side. In the pumping unit 14, the second piezoelectric element 20 made of PZT-based ceramics having a thickness of about 150 μm is displaced when a voltage is applied by a drive circuit (not shown) different from the first piezoelectric element 18, and The vibration plate 21 made of brass and having a thickness of about 150 μm, which is bonded to the second piezoelectric element 20 by an epoxy resin, has a mechanism in which its displacement is magnified and the ink 3 is circulated.

Next, the operation of the main part of the ink jet printer according to the present invention will be described using the above components.

First, the ink 3 in the ink chamber 5 is supplied from the ink tank 2 to the low side ink chamber 7 via the ink supply tube 4. At this time, the ink flow path plate 12
The ink flow path 13 is filled with the ink 3 in advance. Then, the drive circuit oscillates to mechanically vibrate the pumping unit 14, and the ink 3 in the low-side ink chamber 7 moves to the high-side ink chamber 6 through the check valve 8. Further, by vibrating the pumping unit 14, the ink 3 is sucked from the high side ink chamber 6 and returned to the low side ink chamber 7 via the array 15. In this way, once the head difference of the ink 3 has been established, the ink 3 will naturally start to circulate thereafter by the siphon principle.

Although the circulation speed of the ink 3 is very small, the head difference of the ink 3 between the high-side ink chamber 6 and the low-side ink chamber becomes small with the passage of time. A signal is sent to the pumping unit 14 to make the head difference of the ink 3 again between the high side ink chamber 6 and the low side ink chamber 7.

By printing, the ink 3 in the high-side ink chamber 6 and the low-side ink chamber 7 decreases at the same time. At this time, since the liquid level sensor 9 detects the liquid level of the ink 3 as needed, the ink 3 is supplied from the ink tank 2 to the low side ink chamber 7 via the ink supply tube 4 in an appropriate amount.

The vibration waveform applied to the pumping unit 14 may be a sine wave or a step function pulse, and the frequency ranges from low frequency (1 Hz or less) to high frequency (20 k).
Hz or more) can be selected. Further, the phase between the two pumping units 14, 14 can be freely selected. Furthermore, the present invention is not limited to the type of ink, and can be implemented not only in liquid type inkjet printers but also in hot melt type inkjet printers.

[0025]

As is apparent from the above description, the ink jet printer of the present invention is provided with a nozzle plate for ejecting ink and a first ejecting pressure for the ink.
An array having piezoelectric elements, an ink chamber that stores the ink and supplies the ink to the array, an ink flow path plate that connects the ink chamber and the array, and an ink flow path plate. By being provided with a second piezoelectric element that oscillates with the applied voltage to circulate the ink in the ink flow path plate, it is possible to prevent clogging of nozzles and uneven density of printing. Moreover, the printing operation can be continuously performed without interruption, and the printing can be performed very efficiently.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment embodying a configuration of a main part of an inkjet printer of the present invention.

FIG. 2 is a front view of a print head mounted on the inkjet printer of the present invention.

FIG. 3 is a side view of the print head shown in FIG.

[Explanation of symbols]

 3 Ink 5 Ink Chamber 12 Ink Channel Plate 15 Array 16 Nozzle Plate 18 First Piezoelectric Element 20 Second Piezoelectric Element

Claims (1)

[Claims] 1. A nozzle plate that ejects ink, an array having a first piezoelectric element that applies ejection pressure to the ink, an ink chamber that stores the ink and supplies the ink to the array. An ink flow path plate that connects the ink chambers to the array; and an ink flow path plate that is disposed in the ink flow path plate and vibrates with an applied voltage to circulate the ink in the ink flow path plate. An ink jet printer comprising a second piezoelectric element.