CN104290455B - An ink supply device and a method for forming a meniscus on the surface of a printing ink head - Google Patents

Abstract

The present invention provides a kind of ink-feeding device, including supplying ink reservoir, print nozzles and being connected to for the ink tube between ink reservoir and print nozzles, wherein, described ink-feeding device also includes air pressure feed unit, its atmospheric pressure value in also regulating for ink reservoir for the air pressure stable for ink reservoir offer, to ensure that ink supplies to print nozzles via ink tube from for ink reservoir, the described liquid level being less than in print nozzles for the liquid level in ink reservoir, to ensure that the surface of print nozzles forms meniscus.Correspondingly, it is provided that the forming method of print nozzles surface meniscus in a kind of above-mentioned ink-feeding device.Ink-feeding device of the present invention can make up the insufficient pressure in existing gravity ink supply mode, and can preferably regulate the meniscus on print nozzles surface.

Description

An ink supply device and a method for forming a meniscus on the surface of a printing ink head

technical field

The invention relates to the technical field of inkjet printing, in particular to an ink supply device and a method for forming a meniscus on the surface of a printing ink head.

Background technique

Digital printing is a printing technology that has developed rapidly in recent years. It adopts the working method of directly inputting, processing and printing data. Inkjet printing is a branch of digital printing. Many existing inkjet printing equipment of manufacturers use press Electric print head (also known as print head) technology. As shown in Figure 1-2, in the actual printing process of the inkjet printing equipment, in order to ensure the printing quality, the ink is not expected to form small ink droplets 11 on the surface of the printing ink head 1, but the ink is expected to be formed on the surface of the printing ink head 1. The surface forms a concave liquid surface, that is, the meniscus 12, because the formation of the meniscus ensures that the ink droplets will be ejected only when the printing ink head is compressed, so that there will be no expected ink on the printing medium (such as paper). The outer ink droplets appear, which ensures the cleanliness of the printing medium and improves the printing quality. At the same time, since the shape of the meniscus on the surface of the printing ink head will also affect the final printing quality of the inkjet printing device, there are also high requirements on the shape of the meniscus. In order to ensure that the meniscus can be well formed, high requirements are often placed on the ink supply system responsible for ink supply, and the ink supply system is one of the most important parts of the entire inkjet printing system.

At present, there are many ink supply methods for the ink supply system, among which the gravity ink supply method controls the formation of the meniscus on the surface of the ink head by maintaining the pressure generated by the height difference between the ink head and the ink supply tank. The above ink supply method reduces the difficulty of controlling the meniscus on the surface of the printing ink head, and the pressure can be adjusted more conveniently by changing the height difference of the liquid level. However, due to space constraints, the height difference between the ink head and the ink supply tank can only be maintained at about 10cm. 3/8 inch, inner diameter <1/4 inch) can work well in the ink supply system, that is to say, the ink supply system of this structure requires that the distance between the printing ink head and the ink supply pool should not be too far, the supply The diameter of the ink pipe should not be too large, because once the distance between the ink head and the ink supply tank is too far or the diameter of the ink supply pipe is too large, the pressure obtained by the height difference of the liquid level may not be good enough The ink is supplied to the print ink head in a stable manner; at the same time, when the pressure is adjusted, due to the existence of the ink supply pipe between the print ink head and the ink supply pool, even if the height difference of the liquid level is greatly increased, the surface of the print ink head bends The adjustment of the liquid level is also difficult to control, for example, the adjustment time is too long, the adjustment accuracy is too poor, and the shape of the meniscus does not meet the requirements. Moreover, in actual production, sometimes the print ink head and the ink supply tank cannot be very close, and the diameter of the ink supply pipe may be relatively thick. In this case, the pressure generated by the ink supply system using the existing gravity ink supply method There is no guarantee at all of a good supply of ink to the print head, nor a good formation of the meniscus on the surface of the print head.

Contents of the invention

The technical problem to be solved by the present invention is to provide an ink supply device that can compensate for the lack of pressure in the existing gravity ink supply method and can better adjust the meniscus on the surface of the printing ink head in view of the above-mentioned defects in the prior art. And a method for forming a meniscus on the surface of a printing ink head.

The technical solution adopted to solve the technical problems of the present invention:

The ink supply device includes an ink supply tank, a printing ink head, and an ink supply tube connected between the ink supply tank and the printing ink head, wherein the ink supply device also includes an air pressure supply unit, which is used to supply the ink supply tank Provide stable air pressure and can adjust the air pressure value in the ink supply pool to ensure that the ink is supplied from the ink supply pool to the print ink head through the ink supply tube, and the liquid level in the ink supply pool is lower than the liquid level in the print ink head, so as to Ensure that the surface of the print head forms a meniscus.

Preferably, the air pressure supply unit includes an air source and a pressure adjustment sub-unit; the air source is used to provide stable air pressure to the ink supply pool; the pressure adjustment sub-unit is used to adjust the direction of the air source when the ink supply device is working. The air pressure value provided by the ink supply pool, so as to adjust the air pressure value in the ink supply pool, and make the ink supply pool communicate with the atmosphere when the ink supply device stops working.

Preferably, the pressure regulating subunit includes a pressure regulating valve and a three-way valve.

Preferably, the ink supply device further includes a first pressure monitoring unit, which is used for real-time monitoring of the air pressure value provided by the air source to the ink supply pool.

Preferably, the ink supply device further includes a filter unit, and the filter unit is arranged between the air source and the ink supply tank.

Preferably, the filtering precision of the filtering unit is <20 μm.

Preferably, the ink supply device further includes a second pressure monitoring unit, which is used to monitor the air pressure in the ink supply tank in real time.

Preferably, the liquid level in the ink supply pool is 8mm-10mm lower than the liquid level in the printing ink head.

The present invention also provides a method for forming the meniscus on the surface of the printing ink head in the above-mentioned ink supply device, comprising the following steps:

1) Turn on the air pressure supply unit, and gradually increase the air pressure provided by the air pressure supply unit to the ink supply pool;

2) Monitor the printing ink head in real time until small ink droplets are formed on the surface of the printing ink head, control the air pressure supply unit to stop pressurizing, and maintain the current pressure;

3) Adjust the liquid level in the ink supply tank so that it is lower than the liquid level in the print ink head to form a meniscus on the surface of the print ink head.

Preferably, in the step 3), the liquid level in the ink supply tank is adjusted to be 8mm-10mm lower than the liquid level in the printing ink head.

Beneficial effect:

Compared with the prior art, the ink supply device of the present invention has added an air pressure supply unit that can provide stable air pressure for the ink supply tank and can adjust the air pressure value in it, which solves the problems caused by the liquid level between the printing ink head and the ink supply tank. The problem that the pressure generated by the height difference is not enough to supply the ink to the printing ink head well, that is, it makes up for the insufficient pressure in the existing gravity ink supply method. The air pressure supply unit cooperates with the printing ink head and the ink supply unit The height difference between the liquid levels between the pools can better supply the ink to the printing ink head without providing a large pressure, and form a good meniscus on the surface of the printing ink head. At the same time, it can also pass through Adjusting the height difference of the liquid level between the printing ink head and the ink supply pool realizes good adjustment to the shape of the meniscus on the surface of the printing ink head. Therefore, even if the ink supply device of the present invention is applied to long-distance and thick pipe diameters (that is, the distance between the printing ink head and the ink supply pool is relatively long, and the diameter of the ink supply pipe is relatively large), it can also be supplied by air pressure. The unit adjusts the air pressure in the ink supply pool to quickly and effectively supply the ink to the printing ink head, and can better adjust the meniscus on the surface of the printing ink head, which saves the adjustment time and improves the efficiency compared with the prior art. Adjusting the accuracy improves the printing quality and can be more conveniently and stably applied to actual production.

Description of drawings

Fig. 1 is the schematic diagram that the surface of printing ink head forms small ink drop;

Fig. 2 is the schematic diagram that the surface of printing ink head forms meniscus;

3 is a schematic structural view of the ink supply device according to Embodiment 1 of the present invention;

Fig. 4 is a schematic structural diagram of the ink supply device according to Embodiment 2 of the present invention.

In the figure: 1-printing ink head; 11-small ink droplet; 12-meniscus; 2-ink supply pipe; 3-ink supply pool; 4-three-way valve; 5-pressure regulating valve; 6-first pressure Gauge; 7-filter; 8-second pressure gauge.

detailed description

In order to enable those skilled in the art to better understand the technical solution of the present invention, the ink supply device and the method for forming the meniscus on the surface of the printing ink head according to the present invention will be further described in detail below with reference to the drawings and embodiments.

Example 1:

As shown in FIG. 3 , this embodiment provides an ink supply device, including an ink supply pool, an ink supply tube, a printing ink head and an air pressure supply unit.

The ink supply pool is used to store ink, and by adjusting the height of the ink supply pool, the relative height of its internal liquid level can be changed, thereby changing the height difference between the printing ink head and the ink supply pool, and the inside of the ink supply pool The fluid level should be lower than the fluid level in the print head. The ink supply pipe is connected between the ink supply tank and the printing ink head, and is used for supplying the ink in the ink supply tank to the printing ink head. The printheads are used to eject ink onto a print medium, such as paper, as desired to form a printed document. Preferably, the liquid level in the ink supply pool is 8mm-10mm lower than the liquid level in the printing ink head.

The air pressure supply unit is used to provide stable air pressure for the ink supply tank and can adjust the air pressure value in the ink supply tank to ensure that the ink is supplied from the ink supply tank to the print ink head through the ink supply tube, and at the same time cooperate with the print ink head and the ink supply The height difference of the liquid level between the pools (the liquid level in the ink supply pool is lower than the liquid level in the printing ink head) can form a good meniscus on the surface of the printing ink head, and can also be adjusted by adjusting the distance between the printing ink head and the ink supply pool. The height difference of the liquid level is used to adjust the shape of the meniscus on the surface of the printing ink head.

Preferably, the air pressure supply unit includes an air source and a pressure adjustment sub-unit. The air source is used to deliver air to the ink supply pool (compressed air can be generated by an air compressor) to provide stable air pressure to the ink supply pool. The pressure regulating subunit is used to adjust the air pressure value provided by the air source to the ink supply pool when the ink supply device is working, thereby adjusting the air pressure value in the ink supply pool, and to communicate the ink supply pool with the atmosphere when the ink supply device stops working , so as to unload the pressure in the ink supply pool, so as to avoid that when the ink supply device stops working, because there is still pressure in the ink supply pool (that is, the air pressure in the ink supply pool is greater than the atmospheric pressure), the printing ink head will continue to drop ink and cause printing media contamination Case. As for the range of the air pressure value, those skilled in the art can according to the actual situation, such as the distance between the printing ink head and the ink supply tank, the pipe diameter of the ink supply pipe, the height difference of the liquid level between the printing ink head and the ink supply tank, etc. The situation is self-selected. The pressure regulating subunit includes a pressure regulating valve and a three-way valve. More preferably, the ink supply device further includes a first pressure monitoring unit, which is used to monitor the air pressure value provided by the air source to the ink supply tank in real time, so that the pressure adjustment sub-unit can better quantify the air pressure value when performing pressure adjustment , to ensure the adjustment accuracy; the first pressure monitoring unit can adopt the existing pressure gauge. Currently there is an oil-water separator on the market, which combines the functions of oil-water separation, air pressure adjustment and pressure display, so the oil-water separator can be used to replace the pressure regulating valve and the first pressure monitoring unit in the pressure regulating subunit.

Preferably, the ink supply device further includes a filter unit, which is arranged between the air source and the ink supply tank, so as to prevent impurities in the air provided by the air source from entering the ink supply tank and contaminating the ink; the filter unit Filtration accuracy <20μm. Wherein, the filtration accuracy refers to the pore size of the filter element of the filter unit, that is, the size of the largest particle allowed to pass through the filter when the solution containing impurities passes through the filter. The filter unit can adopt an existing filter.

Preferably, the ink supply device further includes a second pressure monitoring unit, which is used to monitor the air pressure in the ink supply tank in real time, so as to determine whether the current state of the ink supply device is normal. For example, when the ink supply device stops working, the air pressure value in the ink supply pool should be zero, and when the ink supply device is working normally, the air pressure value in the ink supply pool should be positive; Unstable, when the air pressure value in the ink supply pool is not zero after the ink supply device stops working, the air pressure values monitored by the second pressure monitoring unit are not normal, so the staff observe the air pressure detected by the second pressure monitoring unit The fault can be found at the first time, and the fault can be eliminated in time; the second pressure monitoring unit can also use the existing pressure gauge.

This embodiment also provides a method for forming the meniscus on the surface of the printing ink head in the above-mentioned ink supply device, including the following steps:

s101. Turn on the air pressure supply unit, and gradually increase the air pressure provided by the air pressure supply unit to the ink supply pool;

s102. Monitor the printing ink head in real time, until small ink droplets are formed on the surface of the printing ink head, control the air pressure supply unit to stop pressurizing, so that the pressure in the ink supply pool (this pressure is positive pressure) will not continue to increase, and maintain the current pressure;

s103. Adjust the liquid level in the ink supply pool so that it is lower than the liquid level in the print ink head, thereby forming a negative pressure in the ink supply pool to offset the original positive pressure in the ink supply pool (which is used to form a pressure on the surface of the print ink head) Small ink droplets), and make the small ink droplets formed on the surface of the printing ink head suck back to the inside of the printing ink head under the action of the negative pressure, so as to form a meniscus on the surface of the printing ink head.

Since the meniscus is formed on the surface of the printing ink head, the surface of the printing ink head is clean and smooth without ink drops, which ensures the cleanliness of the printing medium and improves the printing quality.

In the present invention, the small ink drop refers to the ink drop formed when ink first appears on the surface of the printing ink head.

Preferably, in step s103 , the liquid level in the ink supply pool is lower than the liquid level in the printing ink head by 8mm-10mm.

Example 2:

As shown in Figure 4, this embodiment provides an ink supply device, including a printing ink head 1, an ink supply pipe 2, an ink supply pool 3, an air source, a three-way valve 4, a pressure regulating valve 5, and a first pressure gauge 6 , filter 7 and second pressure gauge 8.

The ink supply pipe 2 is connected between the ink supply tank 3 and the print ink head 1; the air source is used to provide stable air pressure to the ink supply tank 3; the pressure regulating valve 5 is used for Adjust the air pressure value provided by the air source to the ink supply pool 3, thereby increasing the air pressure in the ink supply pool 3, and the three-way valve 4 is used to communicate the ink supply pool 3 with the atmosphere when the ink supply device stops working, so as to unload The pressure in the ink supply pool 3; the first pressure gauge 6 is used to monitor the air pressure value provided by the air source to the ink supply pool 3 in real time; the filter 7 is arranged between the air source and the ink supply pool 3; the The second pressure gauge 8 is used to monitor the air pressure in the ink supply tank 3 in real time. Here, the pressure regulating valve 5 and the first pressure gauge 6 can be replaced by an oil-water separator.

This embodiment also provides a method for forming the meniscus on the surface of the printing ink head in the above ink supply device, specifically: according to the distance between the printing ink head 1 and the ink supply pool 3, the diameter of the ink supply tube 2 and other parameters Select a pressure value so that the three-way valve 4 is in the NC direction (that is, only the left and right ports of the three-way valve 4 are connected, that is, the ports connected to the air source and the ink supply pool are respectively connected, and the ports connected to the atmosphere are closed. ), adjust the pressure regulating valve 5 slowly based on the pressure value, so that the air source starts to provide air pressure to the ink supply pool 3, and gradually increase the air pressure provided by the air source to the ink supply pool 3, so as to gradually increase the pressure in the ink supply pool 3 Adjust the pressure regulating valve 5 until the surface of the printing ink head 1 forms small ink droplets so that the air source stops increasing the pressure to the ink supply pool 3, and keep the current pressure constant. At the same time, adjust the pressure in the ink supply pool 3 The liquid level is lowered by 10 mm than the liquid level in the printing ink head 1 to form a meniscus on the surface of the printing ink head 1 . Then the ink supply unit starts working (printing). When the ink supply device stops working, it is necessary to make the three-way valve 4 in the NO direction (that is, only the lower and right two ports of the three-way valve 4 are connected, that is, the port connected to the ink supply pool 3 and the port connected to the atmosphere are connected. , and the port connected to the air source is closed), so that the ink supply pool is communicated with the atmosphere, thereby unloading the pressure in the ink supply pool 3, so as to prevent the ink head 1 from continuing to drip ink.

Other structures and functions in this embodiment are the same as in Embodiment 1, and will not be repeated here.

It can be understood that, the above embodiments are only exemplary embodiments adopted for illustrating the principle of the present invention, but the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims (9)

1. A method for forming a meniscus on the surface of a printing ink head in an ink supply device, the ink supply device comprising an ink supply tank, a printing ink head and an ink supply tube connected between the ink supply tank and the printing ink head, the The ink supply device also includes an air pressure supply unit, which is used to provide stable air pressure for the ink supply tank and can adjust the air pressure value in the ink supply tank, so as to ensure that ink is supplied from the ink supply tank to the print ink head through the ink supply tube. In that, the forming method includes the following steps: 1) Turn on the air pressure supply unit, and gradually increase the air pressure provided by the air pressure supply unit to the ink supply pool; 2) Monitor the printing ink head in real time until small ink droplets are formed on the surface of the printing ink head, control the air pressure supply unit to stop pressurizing, and maintain the current pressure; 3) Adjust the liquid level in the ink supply tank to make it lower than the liquid level in the printing ink head, so as to form a meniscus on the surface of the printing ink head. 2 . The forming method according to claim 1 , wherein in the step 3), the liquid level in the ink supply pool is adjusted to be 8 mm to 10 mm lower than the liquid level in the printing ink head. 3 . 3 . The forming method according to claim 1 , further comprising step 4): when the ink supply device stops working, the ink supply tank is communicated with the atmosphere, thereby unloading the pressure in the ink supply tank. 4 . 4. The forming method according to claim 1, wherein the air pressure supply unit comprises an air source and a pressure regulating sub-unit; the air source is used to provide stable air pressure to the ink supply pool; the pressure regulating sub-unit The unit is used to adjust the air pressure value provided by the air source to the ink supply pool when the ink supply device is working, thereby adjusting the air pressure value in the ink supply pool, and to communicate the ink supply pool with the atmosphere when the ink supply device stops working. 5. The forming method according to claim 4, wherein the pressure regulating subunit comprises a pressure regulating valve and a three-way valve. 6 . The forming method according to claim 4 , wherein the ink supply device further comprises a first pressure monitoring unit, which is used for real-time monitoring of the air pressure value provided by the air source to the ink supply pool. 7. The forming method according to claim 4, wherein the ink supply device further comprises a filter unit, and the filter unit is arranged between the air source and the ink supply pool. 8. The forming method according to claim 7, characterized in that, the filtering accuracy of the filtering unit is <20 μm. 9. The forming method according to any one of claims 1-8, characterized in that, the ink supply device further comprises a second pressure monitoring unit, which is used to monitor the air pressure in the ink supply pool in real time.