JPH07205448A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To simply prevent an ink density from being excessively lowered in an ink jet recorder. CONSTITUTION:A title recorder comprises an air pump 18 for ventilating the inside of an ink holding container 1 and a controller 30 for actuating the air pump 18 when an ink density in the ink holding container is lowered. An ink density is raised by accelerating the volatilization of a solvent in the ink holding container 1. The reduction of an ink density is estimated by detecting the rise of a liquid level of ink in the ink holding container by a detection electrode 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, and more particularly to ink density control.

[0002]

2. Description of the Related Art An ink jet recording apparatus pressurizes ink in an ink holding container to supply it to a print head, and when the ink is ejected from the print head, the ink is charged and deflected to control ink particles. The print position is controlled by controlling the adhesion position. An ink circulation system is provided so that ink particles not used for printing are collected by a collector and collected in the ink holding container for reuse.

Since the circulating ink has a higher concentration due to volatilization of the solvent, a solvent replenishing system for replenishing the solvent in the ink holding container by detecting or estimating the concentration of the ink is provided.

On the other hand, in this type of ink jet recording apparatus, a solvent is supplied to the ink circulation system in order to prevent clogging of the ink circulation system or to wash the ink circulation system at the time of operation stop or maintenance. Then, this solvent is collected in the ink holding container after use and is effectively used for thinning the thickened ink.

In an ink jet recording apparatus used in a printing system that continuously operates for a long time,
This used solvent is effective for adjusting (thinning) the ink density, but in an inkjet recording device used in a printing system that has a short operating time, the amount of solvent volatilized is small, so the used solvent is an ink. Would be too thin, which would be an obstacle to ink density adjustment. In order to return the excessively diluted ink to a predetermined density, it is sufficient to replenish the ink with a darker color, but the device becomes complicated and large, and the management of the ink for replenishment is troublesome. If the adjustment by replenishing this new ink is repeated, there is a problem that the amount of ink in the ink holding container increases and overflows.

[0006]

As described above, when the conventional ink jet recording apparatus is used in a printing system having a short operating time, the solvent supplied to the ink circulation system for preventing clogging or cleaning is used to retain the ink. There is a problem that the ink in the container is excessively diluted.

An object of the present invention is to easily prevent an excessive decrease in ink density in such an ink jet recording apparatus.

[0008]

According to the present invention, there is provided a nozzle head for ejecting ink particles for printing, an ink supply means for pressurizing ink in the ink holding container to supply the ink to the nozzle head, and a solvent holding container. Solvent supply means for supplying solvent to the nozzle head, recovery means for recovering ink and solvent not used for printing from the nozzle head to the ink holding container, and ink supply for supplying new ink to the ink holding container In an ink jet recording apparatus provided with a means and a control means for controlling these means, the ventilation means for ventilating the inside of the ink holding container, and the ventilating means for operating when the concentration of ink in the ink holding container decreases A ventilation control means is provided.

[0009]

The upper space in the ink holding container is filled with the solvent vapor evaporated from the ink. By ventilating the solvent vapor and lowering the vapor pressure in the space, volatilization of the solvent from the ink becomes active.

The ventilation control means operates the ventilation means so as to ventilate the inside of the ink holding container when the density of the ink inside the ink holding container is lowered, thereby promoting the volatilization of the solvent from the ink and thereby the concentration of the ink. Increase.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the ink and solvent circulation system of an ink jet recording apparatus according to the present invention. The ink used for printing is contained in the ink holding container 1, and is sucked and pressurized by the electrically driven ink supply pump 2 through the electromagnetic valve 3, filtered by the filter 4, and the pressure regulator 5 After the pressure is adjusted by, the ink is supplied to the ink ejection nozzle 7 of the print head through the ink supply control solenoid valve 6. The ink ejecting nozzle 7 ejects the ink to form ink particles, and the ink particles are electrically charged and deflected to a target printing position. Ink particles not used for printing are captured by the collector 8 and collected in the ink holding container 1 via the collection control solenoid valve 9 and the electrically driven collection pump 10.

The replenishment ink having the reference density stored in the ink replenishing container 11 is sucked into the ink supply pump 2 through the electromagnetic valve 12 and is pressurized in the same manner as the ink.

The solvent contained in the solvent holding container 13 is sucked and pressurized by an electrically driven solvent supply pump 14,
The ink is supplied to the ink ejection nozzle 7 via a solvent supply control solenoid valve 15, and the recovery pump 10 is supplied via a solenoid valve 16.
Is supplied to.

Further, a discharge passage is formed for collecting the ink or solvent supplied from the ink jet nozzle 7 to the collecting pump 10, and a discharge control solenoid valve 17 is provided in this discharge passage.

As shown in FIG. 2, the ink holding container 1 has a container air supply port 19 into which external air is sent from an air pump 18, and a container exhaust port 20 for discharging solvent vapor in the ink holding container 1. And an ink liquid level initial level detection electrode 21 and an ink thinning upper limit level detection electrode 22.

The controller 30 controls each pump and solenoid valve to control the supply and recovery of ink and solvent to the print head, and controls the charging of ink particles in the print head. Ink replenishment and air pump operation control are executed with reference to the signals of the level detection electrode 21 and the ink thinning upper limit level detection electrode 22.

FIG. 4 is a flowchart of the control process executed by the control device 30 in order to prevent the ink density from excessively decreasing, which is the object of the present invention. In process 41, it is confirmed whether or not the ink thinning upper limit level detection electrode 22 is in contact with the ink liquid surface, and if it is in contact, it is estimated that the ink in the ink holding container 1 has reached the thinning limit value and the process 42 is performed. Then, the air pump 18 is operated. The stop of the operation of the air pump 18 may be controlled by monitoring the operation time by a timer or the detection signal of the initial level detection electrode 21 and monitoring the liquid level until the ink level drops.

In this embodiment, the decrease in the ink density is estimated by referring to the ink liquid level in the ink holding container 1. This is because the ink is consumed by the printing in the normal printing operation. This is based on the presumption that the liquid level tends to decrease, and the increase in the liquid level is a phenomenon due to excessive mixing of the solvent. In detecting the ink density, it is also possible to detect the decrease in the ink density by other ink density detecting means and execute the operation control of the air pump 18.

Further, in this embodiment, the air pump 18 for ventilating the inside of the ink holding container 1 is installed on the air supply side in order to avoid deterioration due to contact with solvent vapor. does not change.

[0020]

As described above, according to the present invention, the concentration of the ink is increased by promoting the volatilization of the solvent by controlling the ventilation in the ink holding container. Therefore, it is easy to prevent the concentration of the ink from being excessively lowered. It can be prevented by a simple configuration.

[Brief description of drawings]

FIG. 1 is a circulation system of ink and solvent of an inkjet recording apparatus according to the present invention.

FIG. 2 is a vertical sectional side view of an ink holding container of the inkjet recording apparatus according to the present invention.

FIG. 3 is a block diagram of a control system of the inkjet recording apparatus according to the present invention.

FIG. 3 is a flowchart of an ink density reduction prevention control process executed by the control device shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Ink holding container, 7 ... Ink ejection nozzle, 18 ... Air pump, 19 ... Container air supply port, 20 ... Container exhaust port,
21 ... Ink liquid surface initial level detection electrode, 22 ... Ink thinning upper limit level detection electrode, 30 ... Control device.

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[Procedure amendment]

[Submission date] July 8, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a circulation system of ink and solvent of an inkjet recording apparatus according to the present invention.

FIG. 2 is a vertical sectional side view of an ink holding container of the inkjet recording apparatus according to the present invention.

FIG. 3 is a block diagram of a control system of the inkjet recording apparatus according to the present invention.

FIG. 4 is a flowchart of an ink density reduction prevention control process executed by the control device shown in FIG.

[Explanation of Codes] 1 ... Ink holding container, 7 ... Ink ejection nozzle, 18 ... Air pump, 19 ... Container air supply port, 20 ... Container exhaust port,
21 ... Ink liquid surface initial level detection electrode, 22 ... Ink thinning upper limit level detection electrode, 30 ... Control device.

Claims (4)

[Claims] 1. A print head for ejecting and printing by ejecting ink particles, an ink supply means for pressurizing ink in the ink holding container to supply the ink to the print head, and a solvent from the solvent holding container to the print head. Solvent supply means, recovery means for recovering ink and solvent not used for printing from the print head to the ink holding container, ink supply means for supplying new ink to the ink holding container, and control for controlling these In the ink jet recording apparatus provided with a means, a ventilation means for ventilating the inside of the ink holding container, and a ventilation control means for operating the ventilation means when the concentration of ink in the ink holding container is reduced are provided. Characteristic inkjet recording device. 2. The ventilation control means according to claim 1,
An ink jet recording apparatus characterized in that the ink liquid level of the ink holding container is monitored and the ventilation means is operated when the ink liquid level rises to a preset position. 3. The ventilating means according to claim 1, further comprising an air pump for externally requesting external air in the ink holding container, and an exhaust port for discharging the air in the ink holding container to the outside. Inkjet recording device. 4. The ventilation control means according to claim 1,
The ink liquid level of the ink holding container is monitored, and when the ink liquid level rises to a preset position, the ventilation unit is operated, and when the ink liquid level falls to the preset position, the operation of the ventilation unit is stopped. An ink jet recording apparatus characterized by: