JPH0225339A - Ink jet printer - Google Patents

Abstract

PURPOSE:To suppress an increase in cost due to an accessory for cleaning a nozzle to a minimum limit and to perform further higher cleaning effect by providing control means for bringing closing means in a state that a pump is operated into contact with the nozzle and then relatively releasing the contact state. CONSTITUTION:When a controller 17 first rotates a motor 4 in a cleaning mode to reverse a moving base 2 to a predetermined position, a solenoid 16 is energized to move down a thin plate 15, which is set in an ink liquid trajectory. Then, a motor 7 is operated, the motor 4 is reversibly rotated to move forward the base 2 until it is brought into contact with the plate 15 under a predetermined pressure. Since the plate 15 has flexibility, a nozzle 5 is completely closed. Thereafter, the motor 4 is again operated to reverse the base 2, its closed state is released, and the ink liquid is injected at a speed higher than its normal speed by the pressure in the ink passage stored by the motor 7 while the nozzle 5 is closed, thereby cleaning the interiors of the nozzle 5 and the ink passage.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to inkjet printers, and particularly relates to an inkjet printer having a function of preventing clogging of nozzles that are included in the printer and eject ink liquid onto a recording medium.

Recently, with the remarkable progress in image processing technology, various printers have come into use that process electrically read images using computers and reproduce these images on various recording media. It has become.

One of these printers is an inkjet printer.

This inkjet printer has a nozzle that ejects the ink liquid used for image reproduction onto the recording medium at high speed, but in order to obtain good image quality, the particle size of the ink liquid ejected from this nozzle must be is required to be small, so the orifice diameter of this nozzle is, for example, 1
It is necessary to use a very small diameter of 5μ, and furthermore, since the image forming speed is very high, the ink liquid used is quick-drying, so the ink does not reach the nozzle. Easy to solidify, the nozzle always reduces its diameter,
It can be said that it is exposed to conditions where clogging and the like are likely to occur.

In this way, if the diameter of the nozzle is reduced or clogged, the directionality of the ink ejected from the nozzle deteriorates, significantly affecting the image quality, or requiring the nozzle to be replaced. .

In order to eliminate such problems, various efforts have been made in the past.
In the device disclosed in Publication No. 2, a pump device and a valve device dedicated to nozzle cleaning are provided in order to forcefully blow out the ink liquid from the nozzle. The device is suddenly closed to cause water hammer, which removes air bubbles and clogging in the ink liquid. In this way, conventionally, nozzle clogging and the like have been prevented by a device consisting of a pump device exclusively used for nozzle cleaning.

Problems to be Solved by the Invention However, in conventional inkjet printers equipped with such a cleaning device, the provision of a dedicated pump or valve device for nozzle cleaning naturally increases costs. .

Furthermore, during cleaning, ink is vigorously blown onto the recording medium or its holding device, so it is necessary to provide a special device to collect the ink liquid. Furthermore, a device that cleans the nozzle by vigorously blowing ink liquid out of the nozzle has the disadvantage that although it is effective in cleaning the inside of the ink path and the inner surface of the nozzle, it cannot be expected to be effective in cleaning the outer peripheral surface of the nozzle tip. be.

The present invention has been made in order to eliminate the various drawbacks of the conventional technology as described above, and it minimizes the cost increase due to the attached device for cleaning the nozzle, and also achieves higher cleaning efficiency. The purpose of the present invention is to provide an inkjet printer with a clogging prevention function that provides excellent performance.

To achieve the above object, the present invention includes a nozzle that ejects ink liquid pressurized by a pump toward a recording medium, and a nozzle tip that is closed from the outside to inject the ink liquid. a flexible closing means for forcibly blocking the injection of the nozzle; the closing means and the nozzle are brought into contact with each other while the pump is in operation; and a control means for moving at least one of the nozzle or the closing means along the ink jetting direction to relatively release the contact state.

Ikitsuki:The inkjet printer of the present invention having such a configuration operates as follows.

First, when the control means brings the closing means into contact with the nozzle and closes the tip of the nozzle from the outside, and a contact state is established, the pressure within the ink path will inevitably increase due to the pump. The control means moves at least one of the nozzle or the closing means along the ink ejection direction. At this time, since the pressure within the ink path is rising, the ink liquid is vigorously jetted toward the closing means. This results in
In addition to cleaning the inner surface of the nozzle and the inside of the ink path, the outer circumferential surface of the nozzle tip is also cleaned at the same time by the rebound of the ink liquid jetted very close to the closing means from the closing means. . Furthermore, since the closing means blocks the flight path from the nozzle, the ink liquid jetted to clean the nozzle naturally falls to the lower part of the closing means.

EXAMPLE Below, one example of the present invention will be described in detail based on the drawings.

FIG. 1 shows a schematic diagram of the main parts of an inkjet printer according to the present invention.

As shown in the figure, a head moving table 2 is attached to a base 1 of the printer so as to be movable in the direction of A-B in the figure, and this movement is performed by a gear mechanism 3 by a head moving motor 4.
It is done through. This head moving table 2 has a nozzle 5.
An ink tube 8 is connected to the head portion 6, which communicates the nozzle 5 with an ink pump (not shown) driven by an ink pump drive motor 7. The ink pump is connected to an ink bottle 9 in which ink liquid is stored, and the ink liquid is drawn from the ink bottle 9 by the ink pump and pressurized as the ink pump drive motor 7 operates, and the ink tube 8 is pumped. It is force-fed through the nozzle 5 and is vigorously sprayed. The path from this ink pump to the nozzle 5 forms an ink path, and a pressure sensor 18 is provided within the ink pump to detect the pressurized pressure of the ink liquid within this ink path. Further, an electrode 13 is provided on the base 1 via a support 11 to control the flight of the ink liquid ejected from the nozzle 5, and the state of the flight of the ink liquid to the recording paper 12, which is the recording medium, is Inkjet modulation circuit]-4, the electrode 13
and a voltage applied to an electrode (not shown) provided in the nozzle 5. Furthermore, a space above the nozzle 5 is provided to block the flight path of the ink liquid from the nozzle 5 to the recording paper 12, and to close the ink ejection port of the nozzle 5 when the nozzle 5 comes into contact with the ink liquid. A thin plate 15 as a closing means made of a flexible polyester film or the like for forcibly blocking the injection is movably provided, and this movement is effected by a cylinder 10 whose actuation is controlled by a solenoid 16. ing. Therefore, when the solenoid 16 is turned on, the cylinder 10 is actuated and the thin plate 15 is lowered to a position where the flight path is blocked, and when the solenoid 16 is turned off, the thin plate 15 is raised.

In addition, the above-mentioned head moving motor 4. The ink pump drive motor 7, the pressure sensor 18 for detecting the pressure of the pressurized ink liquid in the ink path, the inkjet modulation circuit 14, and the solenoid 16 are connected to a control device 17,
The control device 17 performs these controls in general. Also,
This control device 17 includes one function switch for selecting a cleaning mode for cleaning the nozzle 5, a print switch 20 that is pressed when forming an image on the recording paper 12, and a function switch that turns on the power of the inkjet printer. A main switch 21 that turns off is connected. In addition, the head moving motor 4. solenoid 1
6 and the control device 17 constitute a control means.

When the main switch 21 of the inkjet printer configured as described above is turned on and the function switch 19 is turned on, the printer enters the cleaning mode.
Roughly speaking, each part operates as follows.

First, the head moving motor 4 rotates and the head moving table 2
When the head moving table 2 retreats to a predetermined position, the solenoid 16 turns on and the cylinder 1
0 is activated, the thin plate 15 is lowered and set at a predetermined position along the flight path of the ink liquid. Next, the ink pump drive motor 7 is activated, and the head moving motor 4 rotates in the opposite direction to the above, moving the head moving table 2 forward until it comes into contact with the thin plate 15 with a certain amount of pressure (B in the figure). Since the thin plate 15 has a certain degree of flexibility, the nozzle 5 is completely closed. After this closed state is maintained, the head moving motor 4 is operated again to move the head moving table 2 backward, and the closed state is released.While the nozzle 5 is closed, the ink pump drive motor 7
Due to the pressure accumulated in the ink path, the ink liquid is ejected at a faster speed than usual, cleaning the inside of the nozzle 5 and the ink path, and the rebound of the ink liquid from the thin plate 15 causes the outer peripheral surface of the nozzle tip to be damaged. Cleaning will also be done at the same time. after that,
As the thin plate 15 rises, the head moving table 2 moves forward, returning them to their original positions, and the ink pump driving motor 7 stops, ending the cleaning mode.

Next, FIG. 2 shows a block diagram of a specific connection state around the control device 17.

The CPU 17A built in the control device 17 includes a function switch 19 for outputting a signal, which selects the leaning mode as described above;
When the pressure sensor 18 that detects the pressurized pressure of the ink liquid in the ink path and the print switch 20 that causes the printer to perform normal printing operations are connected, and the cleaning mode is selected by the function switch 19, the CPU 17A When the cleaning mode program is executed and the pressure in the ink path becomes equal to or higher than a predetermined value (approximately 1.5 times the normal pressure) as determined by the pressure sensor 18, the CPU 17A rotates the ink pump drive motor 4 at a low speed. This is because in the cleaning mode, the pressure resistance of each part constituting the ink path is taken into consideration. Further, when the print switch 20 is pressed while the cleaning mode is not selected by the function switch 19, the CPU 17A is instructed to print and executes a print-related program, and the printer performs normal image formation on the recording paper 12. will be carried out.

Furthermore, the CPU 17A has an ink pump drive motor 7 which sucks ink liquid from an ink bottle 9, pressurizes it, and jets this ink liquid from a nozzle, and a head moving table 2, which input signals from the CPU 17A. A head moving motor 4 that moves the nozzle 5 back and forth when operated, a solenoid 16 that raises and lowers the thin plate 15, and a recording paper 1 for ink jetted from the nozzle 5.
When the inkjet modulation circuit 1-4 that controls the flight to the ink jet 2 is connected and the cleaning mode is set by the function switch 19, the CPU 17A controls the ink pump drive motor 7, the head movement motor 4, and the solenoid 16. and print switch 20
When a printing operation is commanded by , the ink pump drive motor 7 and the inkjet modulation circuit 14 are controlled.

FIG. 3 shows an example of an operation flowchart when the inkjet printer of the present invention executes the cleaning mode.

This operation flowchart is shown below in Figures 4 (A) to (C).
).

This operation flowchart is executed when the main switch 21 is turned on to start up the printer and the cleaning mode is selected by the function switch 19.

First, when the cleaning mode is set, the CPU 17
A rotates the head moving motor 4 and moves the head moving table 2.
At the same time, the head portion 6 is retreated to a predetermined position (direction A in FIG. 1), and then the solenoid 16 is turned on to lower the thin plate 15 to a predetermined position. In other words, the head portion 6 and the thin plate 1
5 is set from the initial state of FIG. 4 (A>) to the state of FIG. 4 (B) (step 1.2). Next, the CPU 17A
While driving the ink pump drive motor 7, the head moving motor 4 is rotated in the opposite direction to move the head section 6 forward (direction B in FIG. 1), so that the nozzle 5
The head moving motor 4 is stopped at the position where the head is brought into contact with a predetermined pressing force.

That is, the state shown in FIG. 4(C) is set. As mentioned above, since the thin plate 15 is flexible, when the thin plate 15 is in contact, the thin plate 15 forcibly forces the ink liquid jetting opening of the nozzle 5 with the reaction force caused by the flexure. As a result, the ejection of ink liquid from the nozzle 5 is forcibly blocked (steps 3 and 4).
). If this state is maintained, the pressurized pressure of the ink liquid in the ink path will increase with time, but the CPU 17A will be able to
When it is detected that the pressurized pressure in the ink path has increased by 1.5 times or more, the ink pump drive motor 7 is rotated at a low speed to prevent the pressure in the ink path from increasing more than necessary. Therefore, the ink pump drive motor 7 rotates at the normal speed until the pressurized pressure in the ink path becomes 1.5 times the normal speed, and rotates at a low speed when the pressure increases to 1.5 times or more. The purpose of controlling in this manner is to avoid adversely affecting each component that constitutes the ink path (step 5.6). Then, the CPU 17A causes the solenoid 16 to perform an inching operation to slightly move the thin plate 15 against the nozzle 5I while maintaining the state of contact between the nozzle 5 and the thin plate 15, that is, while maintaining the state shown in FIG. 4(C). become. This slight movement makes it easier to remove solidified ink, dust, foreign matter, etc. adhering to the vicinity of the ink ejection opening of the nozzle 5. Note that this slight movement can be realized by causing the CPU 17A to turn on and off the solenoid 16 in extremely short periods (step 7). If this slight movement continues for a few seconds (step 8)
), the CPU 17A rotates the head moving motor 4 to move the head section 6 together with the head moving table 2 back to a predetermined position (in the direction A in FIG. 1). That is, the head portion 6 and the thin plate 15 are set from the state shown in FIG. 4(C) to the state shown in FIG. 4(B). In this step, from the moment the contact state of the nozzle 5 with the thin plate 15 is weakened, the ink liquid is vigorously jetted toward the thin plate 15, thereby eliminating dust, foreign matter, and other substances on the inner surface of the nozzle 5 and in the ink path. The solidified ink and the like are ejected from the nozzle 5 together with the ejected ink liquid.

At the same time, the outer peripheral surface of the tip of the nozzle 5 is also cleaned by the rebound of the ink liquid from the thin plate 15. This cleaning effect on the outer circumferential surface is very effective in an area where the distance between the ink jetting port of the nozzle 5 and the thin plate 15 is small. (Step 9).

Next, the CPU 17A turns off the solenoid 16, raises the thin plate 15 to a predetermined position, and moves the head section 6 forward again to set it at the initial position. That is, the head section 6 and the thin plate 15 are set from the state shown in FIG. 4(B) to the initial state shown in FIG. (step 12).

In this way, in the inkjet printer of this embodiment, when performing nozzle cleaning, the existing ink pump is used to pressurize the ink, and the thin plate 15 is brought into contact with the ink to prevent the ink liquid from being ejected from the nozzle 5. The ink that is forcefully ejected is forcibly blocked, and then the thin plate 15 is slightly moved while blocking this ejection to easily remove the deposits on the inner and outer peripheral surfaces of the nozzle. The deposits are removed together with the liquid.

Therefore, compared to conventional cleaning, the cleaning effect is higher and the frequency of nozzle replacement can be reduced, in other words, the life of the nozzle can be improved. The thin plate 15 serves to increase the pressure within the ink path, to act as a valve body to prevent the ink liquid from being ejected from the nozzle 15, and to block the flight path of the ink liquid from the nozzle 15 to the recording paper 12. It has the role of cleaning the outer circumferential surface of the nozzle tip by changing the direction of the ink liquid that is ejected. In this embodiment, the cleaning mode is executed when the function switch 19 is selected, but the cleaning mode is not limited to this, for example, when the main switch 21 is turned on or turned off. This mode may be executed when the printing operation is performed, or it may be executed when the printing operation is performed a predetermined number of times or every time the print switch 20 is pressed. Furthermore, when releasing the contact state between the nozzle 5 and the thin plate 15, the contact state is released by moving the nozzle 5 linearly parallel to the ink jetting direction and in the opposite direction. Of course, the present invention is not limited to this, and the contact state may be released by moving only the thin plate 15 or both the nozzle 5 and the thin plate 15. Also in this case,
It is sufficient that the nozzle 5 and the thin plate 15 are moved in a state where they are separated from each other in the ink jetting direction, and in parallel to the ink jetting direction,
Nor does it need to be moved in a straight line.

Furthermore, in this embodiment, the ink pump driving motor is stopped after the head section and the thin plate are set to the initial position, but after the head section is retreated (step 9 in FIG. 3), the ink pump drive motor is stopped after the head section and thin plate are set to the initial position. Stop the drive motor, then
The head portion and the thin plate may be set at initial positions. In this way, while the ink liquid is being ejected from the nozzle, the flight path to the recording paper is reliably blocked, and the ink liquid can also be easily recovered.

As is clear from the above description, according to the present invention, when the pump is in operation, the nozzle tip is forcibly closed from the outside by the closing means, and the ink pressure is increased. Since the ink liquid is jetted after cleaning the nozzle, it is possible to clean the inner and outer surfaces of the nozzle while minimizing the increase in cost due to the provision of an accessory device exclusively for nozzle cleaning. The ejected ink liquid can be easily recovered without the need for a special device.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of main parts of an inkjet printer according to the present invention, FIG. 2 is a block diagram around the control device shown in FIG. 1, and FIG. 3 is a cleaning mode of the inkjet printer according to the present invention. FIG. 4 is a diagram for explaining the operation of the operation flowchart shown in FIG. 3. 2... Head moving table, 4... Head moving motor (control means), 5... Nozzle, 6... Head section, 7... Ink pump drive motor (pump), 12... Recording Paper (recording medium), 15... Thin plate (closing means), 16... Solenoid (control means), 17... Control device (control means), 17A... CPU (control means).

Claims (1)

[Scope of Claims] A nozzle that ejects ink liquid pressurized by a pump toward a recording medium, and a flexible closing means that closes the tip of the nozzle from the outside to forcibly prevent the ink liquid from being ejected. The closing means and the nozzle are brought into contact with each other while the pump is in operation, and after the contact state has passed, at least either the nozzle or the closing means is closed with ink. An inkjet printer comprising: a control means that moves along a jetting direction to relatively release the contact state.