JP5752954B2 - Inkjet printer - Google Patents

Description

  The present invention relates to an ink jet printer using water-based ink.

  Conventionally, when printing directly on an ink jet printer using water-based ink on plastic printing paper such as PVC film or PET film, the discharged ink does not have an absorbing layer on the printing paper. However, the dot size is reduced, and there is a problem that ink is not filled when printing a solid image. Further, since the ink repels and does not spread on the printing paper, there is a problem that the thickness of the ink increases and it becomes difficult to dry. In order to solve this problem, for example, the surface of the printing paper is modified by corona discharge or plasma treatment to improve the hydrophilicity, thereby improving the wettability of the ink and increasing the dot size. Further, a method for improving the drying property is known. Recently, an example in which a plasma processing unit is built in a printer is described in Patent Document 1. For example, Patent Document 1 describes a configuration in which a discharge electrode corresponding to the width of a printing paper is provided in the front stage of an ink jet head to perform a hydrophilic treatment.

JP 2009-299796 A

  However, since the conventional method requires a discharge electrode that is longer than the width of the printing paper, a high voltage power source having a large power capacity is required to drive the electrode to generate corona discharge. For example, even when an electrode for A4 size printing paper is mounted, an electrode of 210 mm or more is required, and a high-voltage power source of 100 watts to 300 watts is required to drive the electrode. For this reason, when it is going to incorporate a corona discharge unit in an inkjet printer, there existed the subject that an apparatus became complicated and large, and the apparatus cost became expensive. In addition, a large amount of ozone is generated due to corona discharge, and a ventilation device for discharging ozone is required. Further, the device is complicated and large, and the device cost is high.

The present invention relates to a mobile in order to solve the above problems, an inkjet head that ejects ink toward the printing paper, a carriage that reciprocates in a main scanning direction by mounting the inkjet Tsu Toheddo, to the carriage in the same direction A discharge electrode unit including a discharge electrode for performing corona discharge on the surface of the printing paper, a counter electrode serving as a discharge destination of the corona discharge of the discharge electrode, and applying a high voltage to the discharge electrode unit In an inkjet printer having a high-voltage power supply, the electrode shape of the discharge electrode is a sawtooth shape, the length of the discharge electrode is equal to or less than the nozzle arrangement length of the inkjet head, and is an integral multiple of the conveyance width of the printing paper equally, the discharge electrode side of the nozzle arrangement of the ink jet head from the ink jet head side end of the discharge electrode Intervals in the transport direction of the printing paper to the nozzle end is an integral multiple of the transport width, the discharge electrode is disposed on the upstream side in the transport direction of the printing paper relative to the inkjet Tsu Toheddo, the inkjet The printer controls a discharge unit controller that controls the timing at which the high voltage is applied to the discharge electrode, and controls the discharge timing of the ink from the inkjet head according to image data, and adjusts the main timing according to the discharge timing. A print control unit that controls the movement of the carriage in the scanning direction to form an image on the print paper;
The discharge electrode and the inkjet head are moved in the main scanning direction in synchronization, and the corona discharge is simultaneously applied to the printing paper by the discharge electrode in synchronization with printing on the printing paper by the inkjet head. An ink jet printer characterized by

  According to the present invention, since a short electrode can be used without using a discharge electrode that is longer than the width of the printing paper, it is possible to configure a corona discharge treatment unit with a small and inexpensive power source, and high-quality printing is possible. A jet printer that uses water-based ink that is capable of generating less ozone and can be provided at low cost. In addition, since the interval from corona treatment to ink ejection can be made very short, it becomes possible to eject ink onto printing paper while suppressing the attenuation of the hydrophilic effect due to corona treatment. There is also an effect that the spreading ratio can be made uniform.

FIG. 1 is a schematic view of an ink jet printer of the present invention as viewed from above. FIG. 2 is a schematic view of the ink jet printer of the present invention as seen from the side. FIG. 3 is a control block diagram of the present invention. FIG. 4 is a comparative view of the discharge electrode of the present invention and an inkjet head.

An embodiment for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view of an ink jet printer according to an embodiment of the present invention as viewed from above. FIG. 2 is a schematic view of the ink jet printer according to the embodiment of the present invention as viewed from the side. The inkjet heads 1 to 4 are heads that eject ink toward the printing paper 8. The inkjet head 1 ejects magenta, the inkjet head 2 cyan, the inkjet head 3 black, and the inkjet head 4 ejects yellow ink. The carriage 5 carries the inkjet heads 1 to 4 and reciprocates in the main scanning direction. The main scanning direction is a direction that intersects the conveyance direction of the printing paper 8 and is a vertical direction in this embodiment. The printing paper 8 is a recording medium such as paper or a resin film. The discharge electrode unit 6 is a unit on which an electrode for corona discharge is mounted, and generates a corona discharge to the counter electrode 7 by applying a high voltage to the electrode. The counter electrode 7 is a discharge destination for corona discharge, and is connected to the ground. When the corona discharge is generated between the discharge electrode unit 6 and the counter electrode 7, the surface of the print paper is modified by the corona discharge by passing the print paper 8 therebetween, and the hydrophilicity is improved. The discharge electrode unit 6 is a unit that can move in the main scanning direction. By moving in synchronization with the carriage 5, the discharge electrode unit 6 can perform corona treatment on the printing paper 8 immediately before printing. The printing paper 8 is a recording medium such as paper or a resin film. The paper driving roller 9 is a roller that conveys the printing paper 8. The high-voltage power supply 10 is a power supply for applying an alternating high voltage to the discharge electrode unit 6.

  FIG. 4 shows an example of the discharge electrode used in this embodiment. The length of the sawtooth electrode 11 was made equal to the width of the nozzle array of the inkjet heads 1 to 4. The length direction of the sawtooth electrode 11 is used along the conveying direction of the recording paper 8. Accordingly, corona discharge processing for one band can be performed by performing corona discharge processing corresponding to the width of the nozzle array of the inkjet head while scanning in the main scanning direction. Here, one band is an area where the inkjet head can print in one scan. The shape of the sawtooth electrode 11 is a sawtooth shape, and discharge can be efficiently performed from a sharp tooth tip, and stable discharge with high discharge efficiency is possible. For this reason, the high voltage power supply 10 used in the present embodiment is capable of corona discharge with a low power supply of about 10 watts. The output specification of the high-voltage power supply 10 was 10 kilovolts as the effective value of voltage, and the output waveform was a sine wave of 1 kilohertz.

  FIG. 3 is a control block diagram for carrying out this embodiment. The print control unit 21 is a block that controls the inkjet heads 1 to 4 and the carriage 5. The print control unit 21 controls ink ejection timing according to image data, moves the carriage 5 in the main scanning direction according to the ejection timing, and prints paper. 8 forms an image. The discharge unit controller 22 moves the discharge electrode unit 6 in the main scanning direction and controls the application timing of the high-voltage power supply 10. The high voltage power supply 10 applies an alternating high voltage to the discharge electrode 25. The sequence control unit 23 gives an operation command to the print control unit 21 and the discharge unit control unit 22 to control the sequence of the entire printer. The print head unit 24 includes ink jet heads 1 to 4.

  Next, the printing operation will be described with reference to FIG. 1, FIG. 2, and FIG. Under the control of the print control unit 21, the paper driving roller 9 sequentially and intermittently feeds the printing paper 8 every distance corresponding to the head width, and performs the printing operation with the printing paper 8 stopped. The conveyance width of the printing paper 8 differs depending on the number of passes in the case of multi-pass printing, but here, in order to simplify the explanation, one-pass printing is performed, and the conveyance width is equal to the head width, that is, printing. This will be described as a width. First, in a state where the printing paper 8 is stopped, a high voltage is applied to the discharge electrode unit 6 from the high voltage power source 10 under the control of the discharge unit control unit 22, and the printing paper 8 is moved in the main scanning direction while performing corona discharge. Then, corona discharge treatment for the head width is performed. Thereafter, the printing paper 8 is fed by the head width by the paper driving roller 9 and stopped. The ink jet head ejects ink while moving in the main scanning direction, and at the same time one band is printed, the discharge electrode unit 6 simultaneously moves on the printing paper 8 in the main scanning direction upstream of the printing paper 8. While applying corona discharge. As described above, the number of times corresponding to the number of bands required for one surface while the printing operation and the corona discharge processing are simultaneously performed by the control of the sequence control unit 23, the print control unit 21, and the discharge unit control unit 22. By repeating only this, it is possible to obtain a printed matter on one side.

  In this embodiment, since the carriage 2 and the discharge electrode unit 6 can be moved separately, there is an advantage that the speeds of the carriage 5 and the discharge electrode unit 6 do not necessarily match. However, the carriage 5 and the discharge electrode unit 6 are integrated. By doing so, a more inexpensive structure is possible.

  In this embodiment, the four-color ink jet printer has been described. However, the present invention can be similarly applied to an ink jet printer having four or more colors and a monochrome monochrome printer.

  Further, although the discharge electrode 25 has been described as the nozzle arrangement width of the inkjet heads 1 to 4, it can be made equal to the conveyance width of the printing paper 8. At this time, the interval between the discharge electrode 25 and the nozzles of the ink jet heads 1 to 4 is made equal to an interval that is an integral multiple of the conveyance width, so that the time interval from the corona discharge treatment to printing can be made constant. Quality can be made constant. In addition, when the transport width can be selected from a plurality of types, the discharge electrodes 25 may be divided and used in accordance with the transport width, and a plurality of small electrodes may be used. Then, a smaller electrode can be used.

DESCRIPTION OF SYMBOLS 1 Inkjet head which ejects magenta ink 2 Inkjet head which ejects cyan ink 3 Inkjet head which ejects black ink 4 Inkjet head which ejects yellow ink 5 Carriage 6 Discharge electrode unit 7 Counter electrode 8 Printing paper 9 Paper driving roller 10 High voltage power supply 11 Sawtooth electrode 21 Print control unit 22 Discharge unit control unit 23 Sequence control unit 24 Print head unit 25 Discharge electrode

Claims (3)

Applying an inkjet head that ejects ink toward the printing paper, a carriage that reciprocates in a main scanning direction by mounting the inkjet Tsu Toheddo, a corona discharge to the surface of the printing paper moving in the same direction and the carriage In an inkjet printer having a discharge electrode unit including a discharge electrode unit, a counter electrode serving as a discharge destination for corona discharge of the discharge electrode, and a high-voltage power source for applying a high voltage to the discharge electrode unit,
The electrode shape of the discharge electrode is a sawtooth shape,
The length of the discharge electrode is equal to or less than the nozzle arrangement length of the inkjet head, and is equal to an integral multiple of the conveyance width of the printing paper,
Wherein the distance between the conveying direction of the printing paper from the edge of the ink jet head side to the nozzle of the discharge electrode side end of the nozzle array of the inkjet head of the discharge electrodes is an integral multiple of the transport width, the discharge electrode is disposed on the upstream side in the transport direction of the printing paper relative to the inkjet Tsu Toheddo,
The ink jet printer controls the discharge timing of the ink from the ink jet head according to image data according to image data and a discharge unit controller that controls the timing of applying the high voltage to the discharge electrode. A print control unit that performs control to move the carriage in the main scanning direction and form an image on the print paper;
The discharge electrode and the inkjet head are moved in the main scanning direction in synchronization, and the corona discharge is simultaneously applied to the printing paper by the discharge electrode in synchronization with printing on the printing paper by the inkjet head. Inkjet printer characterized by.   2. The ink jet printer according to claim 1, wherein power of the high voltage power source is 20 watts or less.   The inkjet printer according to claim 1, wherein the discharge electrode is fixed to the carriage.

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