JPH0429548B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to an automatic ink replenishment method for an inkjet recording device and an automatic ink replenishment device thereof, and particularly to an automatic ink replenishment method that automatically replenishes ink accurately, and a simple ink replenishment method. The present invention relates to an automatic ink replenishing device having a configuration.

[Background of the invention]

An ink circulation system diagram in a conventional inkjet recording apparatus is generally as shown in FIG.

That is, 1 is a gutter, 2 is a nozzle related to an ink jet nozzle equipped with a charging electrode for charge modulation, 3 is an ink supply solenoid valve, 4 is a pressure gauge, and 5
1 is a regulator, 8 is an ink tank, 11 is an ink recovery pump, 12 is an ink supply pump, and 13 is a filter.

The flow of ink during normal operation is as shown by the arrow in the figure, which is ejected from the ink tank 8 by the ink supply pump 12, via the filter 13, the regulator 5, and the ink supply solenoid valve 3, and from the nozzle 2. be.

Further, ink that is not used for printing passes through the gutter 1, is recovered under negative pressure by the ink recovery pump 11, and is returned to the ink tank 8.

The regulator 5 regulates the pressure applied to the nozzle 2 at a constant level, and the ink supply solenoid valve 3 controls the ejection of ink from the nozzle 2.
It turns on and off.

In the normal usage state of the above-mentioned ink circulation system, the ink in the ink tank 8 is managed at a certain level. After the start of operation, ink is consumed by printing and by volatilization of ink solvent components, and it is necessary to replenish these consumptions.

In order to stabilize the ink components, it is better to keep this replenishment interval short, but if you use a 60μ nozzle (3.2cc ink ejection amount), the normal ink tank capacity is 500cc.
If the ink consumption after 8 hours of operation is 30 cc or less, replenishment management every 8 hours is sufficient.

Currently, this work is usually performed manually using ink and intensifier fluid replenishment bottles.

On the other hand, such automatic ink replenishment without manual intervention is generally performed by detecting the ink level in the ink tank 8 with a float sensor, and then supplying the ink from the replenishing ink tank to the main ink tank by turning on and off a solenoid valve. Ink is replenished into the ink tank 8, and intensification liquid is also automatically supplied.

For this reason, the float sensor requires ink resistance, and variations in the flow characteristics of the solenoid valve cause variations in the amount of ink replenishment.To deal with this, the structure becomes complex, and the amount of replenishment is inaccurate. It had the following drawbacks.

Therefore, if there is a variation in the amount of ink supplied to the ink tank, there will also be variation in the ink density ejected onto the printed matter, that is, the recording density.

[Purpose of the invention]

An object of the present invention is to provide an automatic ink replenishment method for an inkjet recording device, which not only automates the replenishment of ink and intensifier liquid to an ink tank, but also allows accurate management of the amount of ink and intensifier liquid to be replenished.
It is an object of the present invention to provide an automatic ink replenishing device with a simple structure that can be directly used in its implementation.

[Summary of the invention]

The key point of the method of the present invention is that an inkjet recording device always has a nozzle, which always has an orifice, and if the pressure is constant, the flow rate/time is also constant. The amount of replenishment is accurately managed by controlling the ink ejection time through the nozzle under a constant pressure.

Therefore, in an ink tank that has been replenished with the correct amount of ink as described above, the amount that has fallen below the specified level is the volatilized content of the intensifying fluid, so this decreased amount must be compensated for. By replenishing the intensification liquid, the amount of intensification liquid to be replenished in the ink tank can also be accurately managed.

In addition to the effects obtained by the method of the present invention described above, the main point of the device of the present invention is that it has a simple structure that does not require any sensor for detecting ink level when replenishing intensifying liquid to an ink tank. It is in.

Therefore, in the method of the present invention, the ink sent out from the ink tank through the ink pressure system is pressurized and supplied to the ink jet nozzle to be ejected onto the printed object, and the unnecessary ink from the ink jet nozzle is removed from the gutter of the ink recovery system. The ink of the charge modulation type inkjet recording device is collected again into the ink tank by the ink tank, and repeats the above cycle, while replenishing ink from the replenishment ink tank to the ink tank, and replenishing intensification liquid from the intensification liquid tank to the ink tank. In the automatic replenishment method, the replenishment of ink to the ink tank is introduced into an ink pressurizing system upstream of an ink jet nozzle forming a part of the ink circulation system, with the ink jet nozzle as a reference. After that, the ink is introduced into an ink recovery system through an ink jet nozzle.

The apparatus of the present invention also includes an ink tank, an ink pressurizing system, an ink ejecting nozzle that pressurizes and supplies ink sent out through the ink pressurizing system and ejecting it onto a printed object, and an ink ejecting nozzle that removes unnecessary ink from the ink ejecting nozzle. An ink recovery system including a gutter for recovering the ink to the ink tank again, a means for replenishing ink from the replenishment ink tank to the ink tank, and a means for replenishing intensification liquid from the intensification liquid tank to the ink tank. In an automatic ink replenishment device of a modulating inkjet recording device, ink is replenished into the ink tank by ink processing upstream of the ink jet nozzle that forms part of the ink circulation system. It has a means for introducing the intensifying liquid into the ink recovery system via an ink jet nozzle after being introduced into the pressure system, and further replenishes the intensifying liquid into the ink tank upon receiving the replenishment completion signal after replenishing the ink to the ink tank. As a means, an automatic opening/closing valve for replenishing the intensifying liquid is installed in the middle of a pipe extending from the intensifying liquid tank, and the tip of this pipe is installed inside the ink tank, so that the end surfaces of the pipe are inside the ink tank. The present invention is characterized by comprising means for opening the automatic opening/closing valve to cause the intensifying liquid to drip until the ink level is blocked.

The details are as follows.

Since inkjet recording devices form characters and the like by forming ink into particles and controlling their charging, the ink components must always be stable under certain conditions. However, the charge modulation type inkjet recording device, also called a continuous jet, pumps ink from a nozzle.
The ink particles are constantly ejected and turned into particles, and the ink particles are used only when necessary for printing, and the unused ink particles are collected from the gutter and returned to the ink tank for reuse. Note that the amount recovered from the gutter is greater than the amount used for printing.

For this reason, ink wears out and deteriorates over time, and the factors that cause this wear and tear include the following.

(1) Ink consumption due to printing.

(2) Volatilization of ink solvent components in the parts of the circulation system that come into contact with the outside air (during the period from the nozzle to the gutter, inside the gutter, inside the ink tank, etc.).

(3) Reaction between the ink and the surrounding atmosphere in the parts of the circulation system that come into contact with the outside air (moisture in the air, etc.)
reaction).

(4) Dust in the surrounding atmosphere is inhaled from the ink collection gutter and mixed into the ink.

These issues are being dealt with as follows.

For item (1), ink is replenished for printing consumption, and for item (2), an intensifying liquid made of the same solvent component as the solvent volatile component of the evaporated ink is created. The same amount of ink as evaporated and transpired is replenished separately from the amount of ink consumed for printing to maintain a balance.

Regarding item (3), since there is no way to recover, the solution is to replace the ink with new ink after a certain period of time (for example, one month) has passed since the start of use.

Item (4) is addressed by installing a filter in the circulation circuit.

When using an industrial inkjet recording device, items (3) and (4) are handled by monthly maintenance in terms of ink management, and items (1) and (2) are handled by monthly maintenance. This is carried out as daily maintenance work.

Therefore, as mentioned above, the present invention provides the above (1),
In addition to automating the maintenance work (replenishment) of ink and intensifier liquid in item (2), an automatic ink replenishment method for an inkjet recording device that can accurately manage the amount of ink and intensifier liquid to be replenished to an ink tank; It is an object of the present invention to provide an automatic ink replenishing device with a simple structure that can be directly used in its implementation.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an automatic ink replenishment method for an inkjet recording apparatus according to the present invention will be described together with an embodiment of the automatic ink replenishment device with reference to the respective figures.

FIG. 2 is a circulation circuit diagram of the automatic ink replenishment device of the ink jet recording apparatus of the present invention, FIG. 3 is an enlarged sectional view showing the intensification liquid replenishment circuit, and FIG.
A circulation circuit diagram of ink and intensification liquid from each tank to an ink tank, FIG. 5 is an explanatory diagram of the ink replenishment operation in FIG. 2, and FIG. Figure 7 is a circulation operation mode diagram,
FIG. 8 is a block diagram of the control unit configuration, which also shows the control method for automatic ink and intensification liquid replenishment, and FIG.
FIG. 9 is an explanatory diagram of signal timing in FIG. 8;

In each figure, the same reference numerals as in FIG. 1 indicate equivalent parts.

First, in FIG. 2, 6 is an intensification liquid tank, 7 is an intensification liquid replenishment solenoid valve related to a two-way solenoid valve, 8A is an ink tank, and 10 is a three-way ink tank switching solenoid valve.

Thus, the ink tank 8A, the ink tank switching three-way solenoid valve 10, the ink supply pump 12,
The filter 13, regulator 5, ink supply solenoid valve 3, and nozzle 2 form an ink pressurizing system, and the gutter 1, ink recovery pump 11, and ink tank 8A
This ink pressurization and recovery system forms an ink circulation system, and the intensification liquid replenishment solenoid valve 7 and intensification liquid tank 6 form an intensification liquid replenishment system. It is.

The inkjet recording device according to this embodiment is of a charge modulation type and is related to character printing.

First, referring to FIGS. 2 to 7, a description will be given of a portion related to the automatic replenishment of ink and intensification liquid, which is added to the above-mentioned ink circulation system.

First, the ink circulation system will be briefly explained.

That is, in FIG. 2, the flow of ink during normal operation is as shown by the arrow in the ink tank 8.
From A, the ink is ejected from the nozzle 2 via the ink tank switching three-way solenoid valve 10, the ink supply pump 12, the filter 13, the regulator 5, and the ink supply solenoid valve 3 related to the two-way solenoid valve.

Ink that is not used for printing passes through the gutter 1, is recovered under negative pressure by the ink recovery pump 11, and is returned to the ink tank 8A.

Thus, the regulator 5 regulates the pressure applied to the nozzle 2 to a constant level, and the ink supply solenoid valve 3 turns on and off the ejection of ink from the nozzle 2 via, for example, a separate switch. .

Next, a section added to this ink circulation system related to automatic supply of ink and intensification liquid will be explained.

First, as shown in FIG. 2, a three-way solenoid valve 10 for switching ink tanks as described above is provided between the ink tank 8A and the ink supply pump 12.

First, connect the ports EXH, IN, and OUT of this three-way solenoid valve 10 for ink tank switching.
Port EXH is connected to the ink tank 8A, and port OUT is connected to the ink supply pump 12. When the ink tank switching three-way solenoid valve 10 is de-energized, the ink tank 8A and the ink supply pump 12 are connected. It is in a state of

Further, a replenishing ink tank 9 is provided, and a port IN of a three-way solenoid valve 10 for switching the ink tank is connected to the ink tank 9 for replenishment. Thereby, ink is supplied from the replenishment ink tank 9 when the ink tank switching three-way solenoid valve 10 is energized.

That is, as described above, in the normal operating state, the pressure is regulated by the regulator 5 from the nozzle 2, and ink is ejected according to the predetermined particle creation conditions. Operate the valve 10 and open the ink tank 8A.
There is no problem in switching the ink tank 9 to the replenishment ink tank 9. While the electromagnetic valve 10 is operated and switched, the same amount of ink as the amount ejected from the nozzle 2 is pumped out from the replenishment ink tank 9.

Since ink particles having a constant volume are ejected from the nozzle 2 whose diameter is controlled while the pressure is kept constant by the regulator 5, the amount is accurately proportional to time.

That is, the following relationship exists.

(Time during which the 3-way solenoid valve 10 for switching ink tanks is operating) × (Amount of ejection from the nozzle 2 per hour) = (Amount of replenishment)...(1) Next, supplementary force is applied to the upper part of the ink tank 8A. A liquid tank 6 is provided, a pipe is led from the intensifying liquid tank 6 to an ink tank 8A, and the end of the pipe is set at a determined liquid level in the ink tank 8A.

Furthermore, the intensifying liquid tank 6 and the ink tank 8
An intensification fluid replenishment solenoid valve 7 is disposed between A and A.

FIG. 3 shows the details of the configuration of this part.

That is, in this part, intensification liquid is replenished, and the structure for replenishing intensification liquid and its operation will be explained with reference to FIG.

The intensifier fluid replenishment solenoid valve 7 is normally in an OFF state and is turned on only when replenishing intensifier fluid.

The intensification fluid replenishment structure shown in FIG. 3 is a so-called "bird drinking" system as described below.

That is, the intensification liquid tank 6 has a structure that can be sealed by the tank cap A14 and the tank gasket 15 after the intensification liquid is injected.

Therefore, if the end surface of the pipe 19 is far from the ink liquid level in the ink tank 8A,
When the intensifying liquid replenishing solenoid valve 7 is turned ON, the intensifying liquid is dripped until the end of the pipe 19 is blocked by the ink liquid level.

In addition, in Fig. 3, 16 is a pipe fixing band, 17
18 is a valve body, 18 is a solenoid, 20 is a pipe holder, 21 is a tank cap B, and 22 is a recovery pipe.

Next, a replenishment operation for automating the replenishment operation of the ink and intensification liquid described above will be described.

This is done by the operation of the control section which will be described later, but first, as shown in FIGS. 4, 5 and 6,
The basic operation will be explained.

In the circulation system shown in FIG. 4, first, a control section, which will be described later, determines the operating time (T) from the start of operation,
Check the amount of ink used (M).

Both the operating time (T) and the amount of ink used (M) are data that can be easily obtained in terms of control, and various methods can be selected to obtain these data.

For example, the operating time (T) can be easily obtained using a timer, and the amount of ink used (M) can be easily obtained by counting the number of bits used for printed characters.

Then, a management time (for example, 8 hours as described in the related art) is determined, and a replenishment operation is performed every time that time elapses.

In operation, after the management time has expired, the ink tank switching three-way solenoid valve 10 is opened according to the amount of ink used (M) checked by the control section, based on the relationship of equation (1) above.

FIG. 5 shows this operating state.

As a result, the replenishment ink portion 23 shown in FIG.
is replenished into the ink tank 8A along the path indicated by the arrow in the figure.

Here, the amount of ink replenished can be considered to be an accurate amount corresponding to the ink used for printing.

Therefore, the remaining amount is due to the volatilization of the ink solvent component to be replenished, that is, the amount to be replenished with the intensifying liquid.

Accordingly, after the above ink replenishment operation, the intensifier liquid replenishment solenoid valve 7 is turned on to replenish the replenishment intensifier liquid portion 24.

FIG. 6 shows this operating state.

That is, as described above, the intensifying liquid is poured into the ink tank 8 by the "bird drinking" method described earlier.
The ink is replenished to the level set in the pipe 19 of A.

At this time, the ON time management of the intensifying fluid replenishment solenoid valve 7 is based on the "bird drinking" method, and the replenishment automatically stops when the pipe 19 comes into contact with the liquid surface, so that sufficient replenishment is achieved. It is enough to set it roughly within the time available.

FIG. 7 shows each mode related to the ink circulation operation described above.

Next, the configuration of the above-mentioned control section and the method for checking the amount of ink used (M) will be explained with reference to FIGS. 8 and 9.

In FIG. 8, 25 is a main control circuit, 26 is a non-volatile memory circuit (ROM), 27 is a solenoid valve drive circuit, 2
8 is a latch circuit, 29 is a volatile memory circuit (RAM), 30A is a solenoid valve related to the three-way ink tank switching solenoid valve 10, and 30B is a solenoid valve related to the intensification liquid supply solenoid valve 7. , 31 is a shift register, 32 is a D/A converter, 33 is a synchronous timing circuit, 34 is an amplifier, and 35 is a charging electrode in the nozzle 2.

The main control circuit 25, nonvolatile memory circuit (ROM) 26, latch circuit 28, shift register 31, volatile memory circuit (RAM) 29, D/A
The converter 32, the synchronization timing circuit 33, the amplifier 34, and the like constitute means for supplying the charging electrode 35 with a video signal based on the pattern data of the code to be printed and the video signal creation data, and also constitute a main control circuit. 25. The ink particle number counter in the volatile memory circuit (RAM) 29 is
The main control circuit 25 and the electromagnetic valve driving circuit 27 constitute a means for counting electromagnetic valve driving means.

That is, in the above, the main control circuit 25:
Of the printed character pattern data stored in the non-volatile memory circuit (ROM) 26, one vertical column of pattern data (8 bit data) for the next character to be printed is written into the latch circuit 28 (in FIG. 9, The data of the latch circuit 28 is sent to the shift register 31 as parallel data (a pattern consisting of a matrix of 5 dots horizontally and 7 dots vertically).

The shift register 31 converts this into serial data related to pulses and sends it to the synchronous timing circuit 33.
Enter. B in FIG. 9 shows the timing of the input signal.

On the other hand, the main control circuit 25 creates and stores video signal creation data (digital step wave signal) in a volatile memory circuit (RAM) 29 in advance,
According to the operation of the shift register 31, the video signal creation data (digital step wave signal) is input to a D/A converter (digital/analog converter) 32.

Next, this D/A converter 32 converts this into an analog step wave signal and inputs it to the synchronous timing circuit 33.

A in FIG. 9 shows the analog step wave signal waveform.

Then, the synchronization timing circuit 33 receives the signal indicated by B from the shift register 31 and the D/A.
From the signal shown at A from the converter 32, a video signal shown at C in FIG. 9 is created.

This video signal is voltage amplified by an amplifier 34 and applied to the ink droplets by a charging electrode 35 in the previous nozzle 2.

However, the relationship between the video signal and the printed characters is
As shown in C of FIG.

Ink particles charged by the video signal are ink particles that contribute to printing, and the number of charged ink particles is the number of pulses of the output signal shown in B of the shift register 31.

The number of pulses is detected by counting in the main control circuit 25, and each time one vertical column of printed characters is output from the shift register 31, the number of pulses is stored in an ink droplet counter in the volatile memory circuit (RAM) 29. The purpose is to ensure that

When the operating time of the apparatus reaches 8 hours, the main control circuit 25 causes the solenoid valve drive circuit 27 to turn on the solenoid valve 30A for a time corresponding to the number of ink particles counted.
It outputs an ON signal and supplies ink via the nozzle 2.

After this ink replenishment operation, the solenoid valve 30B is turned on after a certain time delay to replenish the intensifying fluid.

As described above, according to the automatic replenishment of ink and intensifier fluid according to the present embodiment, the following effects can be expected in summary.

(1) For fixed amount replenishment of ink,
Since a nozzle that ejects ink particles with a constant particle volume is used, accurate replenishment is possible at low cost.

Therefore, in an ink tank that has been replenished with the correct amount of ink as described above, the amount that has fallen below the specified level is the volatilized content of the intensifying fluid, so this decreased amount must be compensated for. By replenishing the intensification liquid, the amount of intensification liquid to be replenished in the ink tank can also be accurately managed.

(2) Adjust the amount of intensifier fluid replenishment using the “bird drinking” method.
Since it is controlled by the liquid level, no sensor is used to detect the ink level.

Therefore, it has great effects in terms of structure, material quality, and cost, as well as the corrosivity of the ink.

(3) Since the opening time of the solenoid valve for replenishing the intensifier fluid can be managed very roughly, the control section can be configured easily.

(4) Replenishment can be performed even while the equipment is in operation, so it can also be applied to continuously operating equipment.

Although the above embodiments relate to character printing, the present invention is not limited to this.
It is a general-purpose product that can be used for printing a wide variety of codes including characters, such as display codes and graphics.

Further, instead of counting ink particles in the above embodiment, other means such as a timer can be used.

〔Effect of the invention〕

The present invention is as described above, and according to the present invention, there is provided an inkjet recording device that not only automates the replenishment of ink and intensifier liquid to an ink tank, but also can accurately manage the amount of ink and intensifier liquid to be replenished. It is possible to provide an automatic ink replenishment method and an automatic ink replenishment device with a simple configuration that is directly used for implementing the method.

[Brief explanation of drawings]

FIG. 1 is an ink circulation circuit diagram of an inkjet recording apparatus according to the prior art, FIG. 2 is a circulation circuit diagram of an automatic ink replenishment device of an inkjet recording apparatus of the present invention, and FIG. 3 is an intensification liquid replenishment circuit thereof. FIG. 4 is an enlarged cross-sectional view showing the ink and intensification liquid from each tank to the ink tank, and FIG.
2 is an explanatory diagram of the ink replenishment operation, FIG. 6 is an explanatory diagram of the intensification liquid replenishment operation in FIG.
8 is a diagram of the circulation operation mode, FIG. 8 is a block diagram of the configuration of the control section showing a control method for automatic ink and intensification liquid replenishment, and FIG. 9 is a timing diagram of signals in FIG. 8. 1... Gutter, 2... Nozzle, 3... Ink supply solenoid valve, 4... Pressure gauge, 5... Regulator,
6...Intensification liquid tank, 7...Intensification liquid replenishment solenoid valve,
8A... Ink tank, 9... Ink tank for replenishment, 10... 3-way solenoid valve for switching ink tank,
11... Ink recovery pump, 12... Ink supply pump, 13... Filter, 14... Tank cap A, 15... Tank gasket, 16... Piping fixing band, 17... Valve body, 18... Solenoid, 19...pipe, 20...pipe holder, 2
1...Tank cap B, 22...Recovery pipe,
23... Replenishment ink portion, 24... Replenishment intensification liquid portion, 25... Main control circuit, 26... Non-volatile memory circuit, 27... Solenoid valve drive circuit, 28... Latch circuit, 29... Volatile Memory circuit, 30A, 30B
... Solenoid valve, 31 ... Shift register, 32 ...
D/A converter, 33... Synchronous timing circuit, 3
4...Amplifier, 35...Charged electrode.

Claims (1)

[Claims] 1. Ink sent from an ink tank via an ink pressure system is pressurized and supplied to an ink ejection nozzle to be ejected onto a printed object, and unnecessary ink from the ink ejection nozzle is removed by a gutter of an ink recovery system. While collecting the ink again into the ink tank and repeating the above cycle,
In an automatic ink replenishment device of a charge modulation type inkjet recording device that replenishes ink from a replenishment ink tank to an ink tank and also replenishes intensification liquid from an intensification liquid tank to an ink tank, replenishment of ink to the ink tank is performed. The ink is introduced into the ink pressurizing system upstream of the ink ejection nozzle, which forms part of the ink circulation system, and then introduced into the ink recovery system via the ink ejection nozzle. 1. An automatic ink replenishment method for an inkjet recording device, characterized in that: 2. An ink tank, an ink pressure system, an ink jet nozzle that pressurizes and supplies the ink sent out through the ink pressure system and ejects it onto the printed object, and collects unnecessary ink from the ink jet nozzle back into the ink tank. A charge modulation type inkjet recording device comprising an ink recovery system including a gutter, a means for replenishing ink from a replenishment ink tank to an ink tank, and a means for replenishing intensification liquid from an intensification liquid tank to an ink tank. In the automatic ink replenishment device, ink is supplied to the ink tank through an ink pressurizing system upstream of the ink ejection nozzle that forms part of the ink circulation system, with the ink ejection nozzle forming part of the ink circulation system as a reference. After replenishing ink into the ink tank, the intensifier liquid is introduced into the ink recovery system via an ink jet nozzle. An automatic opening/closing valve for replenishing intensifier liquid is installed in the middle of the pipe extending from the tank, and the tip of this pipe is installed inside the ink tank, so that the ends of the pipe are kept away from the ink liquid level in the ink tank. An automatic ink replenishing device for an inkjet recording apparatus, characterized in that the automatic ink replenishing device for an inkjet recording apparatus is provided with means for opening the automatic opening/closing valve until the automatic opening/closing valve is blocked to cause the intensifying liquid to drip.