JPH0380432B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an inkjet recording device, and relates to an effective ink and solvent replenishment technique for preventing ink deterioration.

[Background of the invention]

Ink and solvent replenishment in conventional inkjet recording devices involves counting the number of ink droplets used for dot recording and reaching a predetermined value, as described in Japanese Patent Laid-Open No. 54-50330. This method replenishes a certain amount of new ink when the ink is removed, and then replenishes the missing amount with solvent. With this method, when the printing frequency is low, it takes a very long time for the number of ink particles used for dot recording to reach a predetermined count value, so the replenishment cycle of ink and solvent is long, and the printing frequency is also low. If it is very high, the predetermined value will be reached in a short time, so new ink and solvent will be replenished in a very short time. Therefore, the period of replenishment will vary greatly depending on the frequency of printing. However, the amount of solvent volatilized is proportional to the ejection time of the ink, regardless of the frequency of printing. Therefore, if the frequency of replenishment of ink and solvent changes depending on the frequency of printing as in the past, the balance between the solvent phase and solid phase within the ink container may be temporarily disrupted. Depending on the type of ink, if the ratio between the solvent phase and the solid phase falls outside of a certain range, it may not return to its original state even if the solvent is replenished, resulting in the drawback that stable ink jet recording cannot be maintained. .

[Purpose of the invention]

An object of the present invention is to provide an inkjet recording device that prevents ink deterioration and can perform stable recording over a long period of time by periodically replenishing the solvent volatilized during ink circulation and the ink used for recording. Our goal is to provide the following.

[Summary of the invention]

To achieve this objective, the present invention calculates the ink ejection time from the nozzle and replenishes the ink and solvent at predetermined intervals, thereby preventing ink deterioration and achieving stable ink jet recording over a long period of time. It is something to do. When refilling at regular intervals, the amount of ink consumed varies depending on the printing frequency, and therefore an accurate variable measuring means is required to replenish the correct amount. supply ink to the nozzle,
By counting the number of collected ink particles at this time,
An accurate variable metering means is realized with a simple configuration by accurately replenishing an amount of ink equal to the consumed amount.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention. First, the overall configuration will be explained. In FIG. 1, numeral 1 denotes a nozzle which turns ink supplied under pressure into particles. 2
is an electrostrictive element that vibrates the nozzle 1 at a constant period to regularize the generation of ink particles. Reference numeral 3 denotes a charging electrode, which applies an electric charge to the ink particles.
4 is an ink particle, 5 is an anode-side deflection electrode for deflecting the ink particle 4, 6 is a negative-side deflection electrode used as a pair with this deflection electrode 5, and 7 is a non-recording ink particle that is not used for recording. A gutter 8 collects the information, and 8 is a recorded object for recording. 9 is an excitation amplifier that applies an excitation voltage to the electrostrictive element 2; 10 is a charging amplifier that applies a charging signal to the charging electrode 3; 11
is a high voltage power supply for applying high voltage to the deflection electrodes 5 and 6. 12 is an ink valve for intermittent ink supply to the nozzle 1; 13 is a pressure regulating valve for adjusting ink pressure; 14 is a pressure gauge for measuring ink pressure; 15 is for recording inside the main ink container 22. An ink pump 16 is used to pump ink to the nozzle 1, a collection pump 16 is used to collect ink from the gutter 7 and a main ink container 22, and 17 is a collection pump that supplies recording ink from the main ink container 22 to the nozzle 1. 18 is a switching valve for supplying replenishment ink from the auxiliary ink container 23 to the nozzle 1; 19 is a solvent valve for allowing the solvent from the solvent container 24 to be supplied to the main ink container 22; 20 21 is a solvent pump for supplying solvent to the main ink container 22, and 21 is a main ink container 2.
2 is a main ink container for storing recording ink used for normal printing; 23 is an auxiliary ink container for storing new replenishment ink; 24 is for storing a solvent. This is a solvent container to keep it in. 25 is a level sensor amplifier that binarizes the signal from the level sensor; 26
29 are drivers for driving various valves, and 30 is a PIO (peripheral input/output) for driving the various drivers 26 to 29, driving the amplifier, and taking in level sensor signals via the amplifier 25. 31 is an MPU (microprocessing unit) for controlling the entire inkjet recording device, 32 is a read-only memory element (ROM) in which programs and various data are stored, and 33 is a read/write memory element (RAM). ), 34 is a bus line. And, the timing means to measure the ink ejection time from the nozzle is
It is configured by software in MPU31,
An ink particle counting circuit 36 that counts recording ink particles and non-recording ink particles is connected to the PIO 30.

Next, the operation of this inkjet recording apparatus will be explained. The ink ejected from nozzle 1 becomes particles,
It is synchronized with the vibration of the electrostrictive element 2 incorporated in the nozzle 1, and therefore the number of ink particles 4 generated is the same as the frequency of the excitation amplifier 9. A recording signal for printing is supplied from the MPU 31 to the charging amplifier 10, and the charging amplifier 10 amplifies this signal and supplies it to the charging capacitor 3, thereby selectively charging the ink particles 4 generated from the nozzle 1. and,
The charged ink particles 4 are deflected in proportion to the amount of charge by the electrostatic field generated by the anode side deflection electrode 5 and the negative side deflection electrode 6, and reach the moving printing object 8 to form characters. The non-recording ink particles 4 that are not used for printing are stored in the gutter 7.
It is captured and recovered.

The recording ink 35 is pressure-fed from the main ink container 22 via the switching valve 17 to the pressure regulating valve 13 by the ink pump 15, the pressure of which is regulated, and then guided to the nozzle 1 via the ink valve 12. and,
After being collected by the gutter 7, the collection pump 1
6 and returns to the main ink container 22, and this collected recording ink 35 is again led to the nozzle 1 through the above-mentioned path and is used repeatedly.

Basically, in order to create the ink particles, it is necessary to maintain the physical properties of the ink itself, such as viscosity, surface tension, specific gravity, and specific resistance for imparting conductivity to the ink, within predetermined ranges.
However, in the type of inkjet recording device mentioned above, in which the recording ink is recycled and reused, the physical properties of the ink depend on the circulation process,
In particular, during the jet flight and during the process of being collected from the gutter 7, some of the ink solvent components volatilize and fluctuate.

In order to suppress this fluctuation as much as possible and extend the life of the recording ink, various methods have been adopted in the past.

This may be a little confusing, but in general, ink is made up of a solid content such as a resin or dye, and a solvent.The solvent component in this ink is often composed of multiple components, and the ratio of the solvent components to which some of them have volatilized is is different from the solvent component ratio of the elemental ink. The volatile components could be determined by rough calculations based on the vapor pressure of each solvent or by analyzing the volatile components. One way to extend the life of the ink is to replenish the ink used for printing and then replenish the solvent corresponding to the volatile components.

Since the circulatory system for realizing the above-mentioned replenishment is also included in FIG. 1, this will be explained. First, replenish the ink as follows. During normal recording operation (non-replenishment operation), the switching valve 17 is open (ON), but it is closed (OFF) and at the same time, the switching valve 18 is turned ON. As a result, the refill ink in the auxiliary ink container 23 is guided to the nozzle 1 through the ink pump 15. Then, non-recording ink particles 4 ejected from the nozzle 1 and collected by the gutter 7 without being used for recording are counted. This ink replenishment is performed until this count reaches the count of the ink particles 4 used for recording and consumed during the previous non-replenishment cycle. A time chart regarding these replenishments is shown in FIG. 2, and will be explained in more detail next using this chart. R.O.
At this timing, a time counter for measuring ink ejection time and a printing dot counter for counting recording ink particles 4 are precleared. After that, the ink ejection time is accumulated. Detects that H1 (time) has elapsed and enters ink replenishment mode. At this time, it is assumed that the print dot counter has incremented to N1 as shown in the figure. At this point, the ink ejection time counter is pre-cleared and at the same time an instruction to replenish new replenishment ink is issued. This instruction corresponds to turning off the switching valve 17 and turning on the switching valve 18 in FIG.

As a more detailed operation, an example of clock pulse input to the print dot counter will be shown. FIG. 3 shows clock waveforms when ink is not replenished (D) and when ink is replenished (E). FIG. 4 shows a detailed diagram of the ink particle counting circuit 36 that realizes this. A, B, C, D, E in Figure 4 and A, B,,C, in Figure 3.
D and E mean the same signal. Also, the signal means the inverted version of signal B. A is an ink droplet generation timing signal, and it is assumed that ink droplet 4 is always generated in this one cycle. B is a recording signal, which is a signal to be printed when it is "1". The pulse width of this recording signal B is equal to one period of the signal A. C is a new replenishment ink replenishment instruction signal, which becomes "1" when ink is replenished.

Consider a normal record (not being replenished).
As shown in Fig. 3, ink particle generation timing signal A
A regular pulse is output, and a signal of "1" is output in the recording signal B only in the portion necessary for printing. Since the ink replenishment instruction signal C is "0", the ink replenishment instruction signal C in FIG.
As the output signal D of the NAND gate 36a, the third
As shown in the figure, a clock pulse D for counting up is generated and the print dot counter 36b is counted up as shown in FIG. Next, when the cumulative ink jetting time passes H1 as shown in FIG. 2, the input signal C in FIG. 4 becomes "1". Then, in Figure 4
NAND gate 36a closes and NAND gate 36
a is opened, and a clock pulse E is generated as shown in FIG. 3, which causes the print dot counter 36b to count down. This clock pulse E is the recording signal B.
It is generated in synchronization with the ink droplet generation timing signal A when the clock pulse E is "0". Therefore, by counting this clock pulse E, the number of ink droplets 4 that are collected without being used for recording, that is, the replenishment ink The amount of replenishment can be measured. Then, when the value of the print dot counter 36b reaches the same value as in the case of RO as shown in FIG. 2 by this clock pulse E, replenishment of new ink is completed. After this, as shown in FIG. 2, a solvent replenishment instruction signal is issued.

When refilling with new ink is completed, the switching valve 18 is turned OFF again, and at the same time as the switching valve 17 is turned ON, the solvent valve 19 is turned ON and the supply of solvent from the solvent container 24 to the main ink container 22 is started. At the same time, the level sensor 21 is operated to start checking the liquid level in the main ink container 22.
Almost the same amount of solvent as the solvent volatilization amount is in the main ink container 2.
When the liquid level reaches a predetermined level, the level sensor 21 operates and outputs a signal. This signal is binarized by the level sensor amplifier 25 and PIO
Tell 30. The MPU 31 recognizes this and stops the solvent replenishment operation.

In addition, as shown in the second cycle of Fig. 2, even if ink jetting is stopped midway, the ink jetting time and the count value of the print dot counter are stored in the RAM 33, and the accumulated value is calculated when ink jetting starts again. continue. Therefore, H2 in the second cycle
+H3 is the same time as H1 in the first cycle.

〔Effect of the invention〕

According to the present invention, it is possible to replenish new replenishment ink in the same amount as the amount of ink used for printing at regular intervals, and also to replenish the solvent that volatilized during ink circulation. The balance of the solid phase is not disrupted, and therefore deterioration of the ink can be prevented. Moreover, the amount of replenishment ink is measured by the number of non-recording ink particles ejected from the nozzle and collected by the gutter.
This has the effect of easily replenishing ink accurately in an amount equal to the amount of consumed ink.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is a block diagram showing the overall configuration, FIG. 2 is a timing chart for ink and solvent replenishment, FIG. 3 is a timing chart for clock pulses, and FIG. 4 is a timing chart for replenishing ink and solvent. FIG. 3 is an ink particle counting circuit diagram. 1... Nozzle, 3... Charged electrode, 4... Ink particle, 5, 6... Deflection electrode, 7... Gutter, 8...
...Printed object, 15...Ink pump, 16...Recovery pump, 17, 18...Switching valve, 19...
...Solvent valve, 20...Solvent pump, 21...Level sensor, 22...Main ink container, 23...Auxiliary ink container, 24...Solvent container, 31...
MPU, 33...RAM, 35...recording ink,
36...Ink particle counting circuit.

Claims (1)

[Scope of Claims] 1. A main ink container containing recording ink; a nozzle that ejects the recording ink supplied from the main ink container to generate ink particles at a constant cycle;
A charger that selectively charges ink particles ejected from a nozzle according to a recording information signal, and a charger that deflects the recording ink particles charged according to the recording information signal in proportion to the amount of charge to create a target surface for recording. a deflector to be attached to a position, a collection means for collecting non-recording ink particles that are not charged according to a recording information signal and collecting them in the main ink container, an auxiliary ink container for storing replenishment ink, and an ink replenishing means for replenishing a main ink container with an amount of refill ink commensurate with the counted value; a solvent container for accommodating a solvent; In an inkjet recording device comprising a solvent replenishment means for replenishing the main ink container with solvent until the amount of ink in the main ink container reaches a predetermined value, the ink replenishment means selects recording ink and replenishment ink. a switching valve that supplies replenishment ink to the nozzle; a replenishment amount counting means that counts non-recording ink particles collected by the collecting means when replenishing ink is supplied; and a timer that times the time the ink is ejected from the nozzle. Then, when the time value of the timer reaches a predetermined time, the switching valve is controlled to supply replenishment ink to the nozzle, and the count value of the replenishment amount counting means becomes equal to the value of the recording ink particle timer. An inkjet recording apparatus characterized by comprising: switching control means for supplying recording ink to the nozzle when a count value is reached. 2. In claim 1, the recording ink droplet counting means and the timing means store the measured value when ink ejection from the nozzle is stopped, and add the measured value when ejection resumes. An inkjet recording device characterized by: