JP2007021723A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet image forming apparatus which is equipped with a degasifier that reduces dissolved oxygen from used ink by a simple constitution, and which is stable in printing quality. <P>SOLUTION: The inkjet recorder comprises an ink tank 1, a sub tank 4 which temporarily stores the ink before supplying to a printing head 6, the degasifier 3 which degasifies the ink in an ink passage that links the ink tank and the sub tank, a detecting part which detects a concentration of the dissolved oxygen of the ink, and a control part which operates the degasifier by the detected value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a deaeration device for an inkjet image forming apparatus that performs printing with a print head that ejects ink.

  An inkjet image forming apparatus that forms an image by ejecting ink from a print head onto a recording medium can form a highly accurate image with a small print head in which a plurality of nozzles are arranged at high density. Furthermore, by arranging a plurality of print heads and supplying different colors of ink to each head, a color image can be obtained with an inexpensive and small configuration. Alternatively, it has many advantages such as being able to print on a wide, large-format recording medium arranged in approximately one row.

  In such an ink jet image forming apparatus, it is important that ink discharge from the print head is stable. In particular, a certain amount of oxygen is usually dissolved in the ink (dissolved oxygen), and bubbles are formed in the ink flow path and the print head, preventing the flow of ink and causing an undischarge phenomenon in which the ink does not fly. Adverse effects.

For this reason, a configuration including a deaeration device for removing ink supplied to the print head is used, or specially packaged ink that has been degassed in advance is used.

However, a configuration in which a deaeration device is provided for a print head, such as the configuration proposed in Japanese Patent Application No. 2004-163730, requires deaeration devices for the number of print heads to be used. As described above, when a plurality of print heads are used, the cost is increased. In addition, the use of ink that has been degassed in advance is expensive in itself, and replenishment and management of the ink is a difficult task.
Japanese Patent Application No. 2004-163730

  In order to solve the conventional problems, an object of the present invention is to provide an ink jet image recording apparatus having a degassing device for reducing dissolved oxygen from ink used with a simple configuration and having stable printing quality.

  In order to solve the above-described problems, the present invention includes an ink tank and a sub-tank that is temporarily stored before supplying ink to the head, and a deaeration device that degass the ink in an ink flow path connecting the two. An ink jet image forming apparatus.

An ink jet image forming apparatus comprising an independent dedicated channel for degassing the ink sent from the ink tank and returning it to the ink tank again.

  An inkjet image forming apparatus comprising: a control unit for a deaeration device that deaerates the deaeration device over a predetermined time.

  An inkjet image forming apparatus comprising: a detection unit that detects a dissolved oxygen concentration of ink; and a control unit that operates a deaeration device according to the detected value.

  In addition, the control unit operates the deaeration device when the dissolved oxygen concentration of the ink exceeds a certain value with respect to the value detected by the detection unit, and the dissolved oxygen concentration of the ink decreases to a predetermined value. An inkjet image forming apparatus that is controlled to perform a deaeration operation.

In addition, the liquid feed pump for feeding ink, the deaeration device, the dissolved oxygen concentration detection unit, and the deaeration device control unit constitute an independent ink flow path, and this portion is configured as a unit and is added to the existing ink tank. An inkjet image forming apparatus that is detachable.

Further, the dissolved oxygen concentration detection unit and the deaeration device control unit may be provided in the configuration of the unit, or may be provided independently of each other.

  ADVANTAGE OF THE INVENTION According to this invention, the deaeration apparatus which reduces dissolved oxygen from the ink used for an inkjet image forming apparatus with simple structure can be provided, and the inkjet image forming apparatus with stable printing quality can be provided.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a basic configuration diagram of the present invention. A deaeration device is provided in the middle of sending ink in an ink tank to a sub-tank through an ink flow path, and even if the ink collected from the recovery device is returned to the ink tank, it is removed. An inkjet image forming apparatus showing that a stable ink can be supplied through an air device.

  The ink tank 1 is filled with ink, and is sucked up by the liquid feed pump 2 and sent to the deaeration device 3. Next, an example of the internal configuration of the deaeration device 3 will be described with reference to FIG.

  The deaeration device described as an example uses a hollow fiber filter 12 and a vacuum pump 13. The hollow fiber filter 12 is provided with connecting joints 15 and 16 for the inlet and outlet of the ink, respectively. Ink is fed from the inlet joint 15 to the hollow fiber filter 12 by the liquid feed pump 2.

The hollow fiber filter has innumerable minute holes through which only gas passes. The hollow fiber filter is installed inside the housing 14 and air suction holes 17 and 18 are provided in the housing. A vacuum pump 13 is connected to the air suction holes 17 and 18, thereby sucking and depressurizing air around the hollow fiber filter 12 inside the housing 14.

The ink that passes through the hollow fiber filter 12 escapes out of the hollow fiber filter from the minute holes through which only the gas of the hollow fiber filter passes because the dissolved oxygen dissolved in the ink drops in the surrounding atmospheric pressure. It passes through the suction holes 17 and 18 and is discharged to the outside air by the vacuum pump 13.

As described above, the ink fed from the inlet joint is discharged from the outlet joint with a greatly reduced dissolved oxygen concentration.

  Ink that has passed through the deaeration device is stored in the sub tank 4 in order to supply ink to the print head 6. On the other hand, in order to drive and control the data for printing an image by the print head, and for that purpose, the head supply pump 5, the print head drive substrate 9, and the liquid feed pumps 2, 8 are electrically It is connected to the drive control unit 10 by a cable. The drive control unit is connected to the PC 11 for sending print data and controlling print head drive. (Fig. 8)

  In the inkjet image forming apparatus, a recording medium 21 to be printed is placed on a conveyance belt 24 disposed between a conveyance roll 22 and a conveyance drive roll 23 driven by a drive mechanism (not shown). Normally, although not shown here, a suction chamber is provided inside the transport belt, and is sucked and transported by the numerous suction holes provided in the transport belt 24.

When the recording medium 21 enters the print area, the print head 6 is operated by a signal from the drive control unit 10, and ink is ejected from the print head 6 to print an image.

The activated print head 6 performs a recovery operation by the recovery unit 7 in order to maintain the state of the print head according to a signal from the drive control unit as necessary or periodically. The ink collected in the recovery operation is collected in the ink tank 1 without being discharged to the outside by the ink collection pump 8. The collected ink passes again through the deaeration device 3 and is sent to the sub tank, where it is used for the next printing operation.

  The above is the basic explanation, but in order to explain the effect of the invention in more detail, FIG. 3 shows it. FIG. 3 is a schematic diagram of an ink jet image forming apparatus configured to supply degassed ink from two ink heads 1 to two print heads 6 and 6.

As shown in FIG. 3, by arranging the print heads in a staggered manner, the print corresponding to twice the image formation width of FIG. 1 can be used as the recording medium. At this time, the ink supplied to the print heads 6 and 6 · 1 passes through the deaeration device 3 from the ink tank 1 and is supplied to the sub-tanks 4 and 4 · 1.

With such a configuration, even if the number of print heads to be installed increases, a single deaeration device installed near the ink tank can cope with a deaeration device that degass the ink to be fed.

FIG. 4 shows an ink jet image forming apparatus comprising a degassing device for degassing ink in an ink tank independently of an ink flow path for supplying ink from an ink tank to a print head, and an ink feeding means. It is the schematic of an ink flow path. The flow of ink supply to the print head is the same as in the first embodiment. Degassing of the ink in the ink tank will be described below.

The ink in the ink tank is pumped up from the ink tank by the liquid feed pump 2. At this time, the ink is sent through the detection unit 20 that detects the dissolved oxygen concentration in the ink.

The detection unit 20 sends the detected data to the deaeration device control unit 21. The deaerator control unit 21 incorporates a program for maintaining a predetermined dissolved oxygen concentration. When the dissolved oxygen concentration of the ink passing through the detection unit 20 exceeds a predetermined value, the deaerator 3 The vacuum pump 13 is operated, and dissolved oxygen is sucked from the ink passing through the deaeration device 3.

The ink whose dissolved oxygen concentration has decreased returns to the ink tank 1. In this way, the liquid feed pump 2.1 continues to send ink to the deaeration device 3 until the dissolved oxygen concentration when the ink in the ink tank passes through the detection unit 20 falls to a predetermined value. 3 continues the deaeration work by continuing to operate the vacuum pump. (Fig. 7)

As described above, the liquid feed pump 2 that supplies ink from the ink tank 1 to the sub tank 4 connected to the print head 6 can supply ink having a dissolved oxygen concentration lower than a predetermined value for printing.

As is apparent from the schematic diagram of FIG. 4, the liquid feed pump 2.1 for degassing the ink in the ink tank, the degassing device 3, the dissolved oxygen concentration detection unit 20, and the degassing device control unit 21 are Since an independent dedicated ink flow path is formed, this portion can be formed as an independent unit (FIG. 5) and can be attached to and detached from an existing ink tank at any time.

  In the first embodiment, a deaeration device is provided in the middle of the ink flow path between the ink tank and the sub tank, and deaeration is performed when ink is supplied to the sub tank. When necessary, the ink is circulated so that it can be deaerated.

  The dissolved oxygen concentration detector 20 is provided in the independent deaerator unit, but may be provided in the ink tank or in the ink flow path between the ink tank and the deaerator, and is detected at each position. Based on the dissolved oxygen concentration data, the degassing device 3 can be operated to supply the degassed ink to the print head.

  The deaerator control unit 21 is provided in the independent deaerator unit, but may be provided alone other than the unit.

An inkjet image forming apparatus that forms an image by ejecting ink droplets from a print head onto a recording medium can form a highly accurate image with a small print head in which a plurality of nozzles are arranged at high density.

Furthermore, by providing a deaeration device that reduces dissolved oxygen from the ink used in the inkjet image forming apparatus with a simple configuration, by arranging a plurality of print heads and supplying different colors of ink to each head, There are many advantages such that a color image can be obtained with an inexpensive and small configuration, or printing can be performed on a wide large recording medium arranged in a line.

Basic schematic diagram of ink flow path according to the present invention FIG. 1 is a detailed view of a deaeration filter having an internal configuration of a deaeration device showing an example of the present invention Schematic diagram of an inkjet image forming apparatus in which two print heads of the present invention are arranged. Schematic of ink flow path by independent degassing unit of the present invention Three-dimensional view of deaerator unit of the present invention Flow diagram of basic schematic diagram of ink flow path according to the present invention Flow diagram of schematic diagram of ink flow path by independent degassing unit of the present invention Electrical block diagram of the present invention

Explanation of symbols

1. 1. Ink tank Liquid feed pump (Same as 2.1)
3. Deaerator 4. Sub tank (4.1 same)
5. Head supply pump (Same for 5.1)
6). Print head (same for 6.1)
7). Recovery unit (same as 7.1)
8). Ink recovery pump (8.1 same)
9. Print head drive substrate 10. Drive controller 11. PC for control
12 Hollow fiber filter 13. Vacuum pump 14. Storage housing 15. Entrance joint 16. Outlet joint 17. Air suction hole 18. Air suction hole 20. Dissolved oxygen concentration detector 21. Recording medium 22. Transport roll 23. Transport drive roll 24. Transport belt 25. Deaerator control unit

Claims (7)

  An ink-jet image forming apparatus comprising: an ink tank and a sub-tank that is temporarily stored before supplying ink to a head; and a deaeration device for deaerating ink in an ink flow path connecting the two. An ink jet image forming apparatus comprising an independent dedicated flow path for degassing ink sent from an ink tank and returning it to the ink tank again.   The inkjet image forming apparatus according to claim 1, further comprising a control unit of a deaeration device that causes the deaeration device to deaerate for a predetermined time.   The inkjet image forming apparatus according to claim 1, further comprising: a detection unit that detects a dissolved oxygen concentration of the ink; and a control unit that operates the deaeration device based on the detected value. The control unit operates the deaeration device when the dissolved oxygen concentration of the ink exceeds a certain value with respect to the value detected by the detection unit, and removes it until the dissolved oxygen concentration of the ink falls to a predetermined value. The inkjet image forming apparatus according to claim 4, wherein the inkjet image forming apparatus is controlled so as to perform a gas motion. Liquid feed pump for feeding ink, deaeration device, dissolved oxygen concentration detection unit, deaeration device control unit constitutes an independent ink flow path, this part is configured as a unit and can be attached to and detached from an existing ink tank The inkjet image forming apparatus according to claim 2, wherein: The inkjet image forming apparatus according to claim 6, wherein the dissolved oxygen concentration detection unit and the degassing device control unit may be provided in the configuration of the unit, or may be provided independently of each other. .

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