JP2003063033A - Method for refreshing printing head of liquid ejection printing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable movement of a printing head in a short time which is required for refreshing operation for the restoration of printing head ejection and wiping operation of a nozzle surface so as to minimize the reduction in the output velocity of the printing device, and to secure the restoration of the ejection. SOLUTION: A liquid absorption medium having a hole for passing the nozzle part of the printing head is arranged between a plurality of line type printing heads and the printing media, and poor ejection is detected by an optical measuring device or the like, so that the refreshing operation can be surely performed in a short time and the printing media are not consumed by refreshing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid droplet ejection printing apparatus for ejecting a liquid to perform printing, and more particularly, to a liquid to be printed from the print head on a print medium moving along one or more line type print heads. The present invention relates to a droplet ejection printing apparatus that ejects droplets to perform printing.

[0002]

2. Description of the Related Art A droplet discharge printing apparatus which prints characters and images by discharging droplets from a print head onto a print medium is widely known.

Paper, a film, a plastic material or the like is mainly used as a printing medium of a printing apparatus of this kind, and particularly, the operation noise is small as compared with other printing methods, and the basic mechanical structure is simple and inexpensive. Since it can be configured, it is widely used for computer data output.

There is a line head type as a droplet discharge printing apparatus, but a line head in which the nozzles of the print head are installed so as to correspond to the width direction of the print medium is mounted, and this print head is arranged in the conveying direction of the print medium. A single medium or a plurality of mediums are arranged at a predetermined interval, and the medium to be printed is held and conveyed by a conveying means using a method such as air suction or electrostatic adsorption. The line head type has advantages such as high-speed color printing.

In the print head of a droplet discharge printing apparatus, in order to reliably discharge droplets, a refresh operation, that is, a blank discharge is generally performed before printing. In particular, in a droplet discharge device that employs water-based ink, when bubbles or minute dust enter the nozzle, it becomes difficult to discharge droplets. If printing is performed while the ejection of droplets is insufficient, dot dropouts and uneven density occur on the print.

The normal refresh operation is performed by ejecting droplets onto a droplet absorbing material provided in a cap mechanism that prevents the nozzle portion of the print head from drying. After that, the print head is moved, printing is performed on the print medium, the ejection state is confirmed, and if there is a problem, the refresh operation is performed again to eliminate the droplet ejection failure. Printer is power supply OF
In the F state, the nozzle portion of the print head is sealed by the cap mechanism to prevent it from drying, but the cap mechanism is opened from the nozzle after the power is turned on or when printing is started.

However, the ejection failure of the nozzle may occur during the printing for a while.
In the case of a line head type droplet discharge printing device, it is particularly necessary to prevent discharge failure in advance.Therefore, an optical sensor such as a laser beam system is provided to discharge droplets at all times to constantly monitor the discharge state. When an abnormality occurs, it is necessary to move the line head to the cap mechanism and perform the refresh operation.

When droplets are ejected from the print head onto the print medium, minute droplets generated by the droplets colliding with and dispersed on the print medium bounce back toward the nozzle of the print head and adhere to the vicinity of the nozzle. Then, the phenomenon of accumulation occurs.
Furthermore, when the print medium is continuously conveyed, the paper dust adhering to the print medium floats near the print head,
It adheres to and accumulates on the nozzles of the print head. Accumulation of these droplets and paper powder easily causes droplet ejection failure of the print head and bending of the droplet ejection direction. Therefore, when printing is performed to remove these, it is necessary to periodically wipe and clean the nozzle surface of the print head.

[0009]

SUMMARY OF THE INVENTION In order to prevent defective ejection of droplets from a nozzle during printing, it is necessary to periodically perform a refresh operation or a wiping and cleaning of the nozzle surface of a print head after performing ejection for a certain period of time. In the meantime, printing must be stopped during that time, which reduces the output speed of the printer. In the current refresh operation, idle discharge cannot be performed unless the line head is moved to the cap mechanism after being separated from the print medium by the head moving means by a required distance. If there is a problem with the ejection, the cap is moved again to the refreshing operation. Further, also in the wiping and cleaning operation of the nozzle surface of the print head, the line head is moved to the cap mechanism by the head moving means, and the wiping blade attached to the cap mechanism is brought into contact with the line head,
It is necessary to move the cap mechanism in the direction along the nozzle surface of the line head for wiping. Since the wiping blade is brought into contact with the nozzle surface of the line head, a rubber material or the like is often used.

In order to move the print head and the cap mechanism, a relatively long time of about several seconds is required, and further, the refresh operation and the wiping and cleaning operation of the nozzle surface are completed, and the print head is moved to the original print position. You also need time to let it work. Printing is stopped during the total time of the three types of time of the print head separation movement time, the refresh operation or the wiping and cleaning operation of the nozzle surface, and the print head position reset time.

Under these circumstances, in order to minimize the decrease in the output speed of the printing apparatus, the print head movement required for the refresh operation for the ejection recovery of the print head and the wiping operation of the nozzle surface can be performed in a short time. The purpose is to ensure the recovery of discharge.

[0012]

In order to achieve the above object, in the present invention, droplets are ejected from the print head onto a print medium that moves along the arrangement direction of one or more line type print heads. In a droplet discharge printing apparatus in which printing is performed by performing printing, a print head moving unit that separates the print head from the print medium by a desired distance, and a control unit that controls the drive of the print head moving unit and the print head And a droplet absorbing medium that moves in parallel with the moving direction of the printing medium while being separated from the printing medium by a desired distance, and the droplet absorbing medium penetrates the droplet discharging section of the print head. The holes having the size that can be formed are formed at the arrangement intervals of the print heads, and the control means preliminarily separates the print heads from the print medium by a desired distance. When the head prints on the print-receiving medium, when the droplet discharge unit of the print head is installed in a state of penetrating the hole of the droplet absorbing medium and the idle discharge operation of the print head is performed, , Returning to a position where the print head moving means separates a desired distance from the liquid drop absorbing medium, and moving the hole of the liquid drop absorbing medium from the front surface of the print head to interrupt discharge to the print medium. Then, the liquid droplets are ejected onto the print medium, and the ejection result formed on the liquid droplet absorbing medium by the idle ejection operation of the print head is checked by an optical measuring device or the like for the presence or absence of ejection failure. It is characterized by detecting.

Further, a window frame for visually confirming the droplet discharge failure on the droplet absorbing medium is provided on the droplet discharge printer cover.

[0014]

DETAILED DESCRIPTION OF THE INVENTION An example of the present invention will be described below with reference to FIGS.

FIG. 1 is a side view showing the printing mechanism of this example.

Here, 1 is a print head, and nozzles for ejecting liquid droplets are provided at intervals of 600 dots / inch. The print head 1 corresponds to four color inks of black, cyan, magenta, and yellow, and has a four-row array configuration.

FIG. 2 is a perspective view showing the printing mechanism of this embodiment.

In each print head 1, the print head moving means 6 is arranged so that the distance between the nozzles in the print medium conveyance direction is constant.
It is held at. Further, the print head 1 is moved relative to the print head moving means 6 by a rack and pinion mechanism or the like so that the print head 1 can move in the vertical direction relative to the print medium 2 relative to the print head moving means 6. It can be moved vertically.

The droplet absorbing medium 3 is arranged so as to be sandwiched between the print head 1 and the print medium 2.
The droplet absorbing medium 3 is formed with an elongated hole 5 in the width direction of the print-receiving medium 3 so that the nozzle portion 4 of the print head 1 can penetrate therethrough. The elongated holes 5 are formed at a distance corresponding to the arrangement interval of the four rows of print heads 1, and when printing is performed by the four rows of print heads 1, all nozzle portions 5 penetrate at the same time, and the desired print medium 2 and the desired print medium 2 are formed. The print head 1 is moved up to the distance.

When the print head 1 is refreshed, the print head moving means 6 is used to move the print head 1.
Is moved in the direction perpendicular to the print-receiving medium 2 up to several mm above the liquid-drop absorbing medium 3, and then the liquid-drop absorbing medium 3 is moved a distance corresponding to one arrangement interval of the print head 1. When you do this,
Since the droplet ejection from the print head 1 is masked to the print medium 2, the droplets are ejected from the print head 1 in this state to perform the refresh operation.

When the surface of the nozzle portion 4 is wiped and cleaned, the print head moving means 6 moves the print head 1 to a position aligned with the surface of the liquid drop absorbing medium 3, and then the liquid drop absorbing medium. The droplet absorbing medium 3 is brought into contact with the nozzle portion 4 and wiped off by moving the nozzle portion 3 by a required distance.

After that, the ejection result on the droplet absorbing medium is detected by using the optical measuring device 7, and when the ejection is not performed, it is recognized by the panel or the like and the ejection is performed again. The droplet absorbing medium 3 can be sequentially wound by a winding means (not shown) by forming a long sheet. To drive the winding means, a motor is connected to the shaft on the winding side to control the winding amount and drive timing.

When printing is performed again after the refreshing operation or the wiping / cleaning operation of the surface of the nozzle portion 4, the droplet absorbing medium 3 is moved again by a distance corresponding to one arrangement interval of the print head 1 so that the droplet absorbing medium 3 is removed. The long hole 5 is aligned with the position where the nozzle portion 4 of each print head 1 can penetrate, and the print head moving mechanism 6
The print head 1 is fixed to the print medium 2 by a desired distance.

[0024]

As described above, according to the present invention, droplets are ejected from a plurality of print heads onto a print medium that moves along the arrangement direction of a plurality of line type print heads to perform printing. In the droplet discharge printing apparatus described above, there are provided a print head moving means for separating the plurality of print heads from the print medium by a desired distance, and a control means for driving the print head moving means and the plurality of print heads. However, the control means previously separates the plurality of print heads from the print medium by a desired distance,
Further, a position is provided between the print head and the print medium, the drop absorbing medium having a hole through which a nozzle portion of the print head can pass is disposed, and the print head moving means removes the print head from the drop absorbing medium. Immediately after the separation, the droplet absorbing medium is moved so that the droplets discharged by the print head are absorbed by the droplet absorbing medium, or the liquid on the nozzle surface of the print head is controlled. By controlling to wipe off the drops and paper dust, the refresh operation during printing and the wiping and cleaning operation on the nozzle surface can be performed in a short time, and the decrease in printing speed of the printing device can be suppressed to a minimum. it can.

Further, since the refreshing operation of the line type print head and the wiping and cleaning of the nozzle surface can be easily performed in a short time, the frequency can be increased and the reliability of droplet ejection can be improved. Becomes

Further, by detecting the discharge result formed on the liquid drop absorbing medium by the idle discharge operation of the print head by an optical measuring device or the like, the refresh operation can be surely performed, and the print medium is refreshed. It becomes possible not to consume.

[Brief description of drawings]

FIG. 1 is a side view showing an example of the present invention.

FIG. 2 is a perspective view showing an example of the present invention.

[Explanation of symbols]

1 is a print head, 2 is a print medium, 3 is a droplet absorbing medium,
4 is a nozzle portion, 5 is an elongated hole, 6 is a print head moving means, and 7
Is an optical measuring device.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Makoto Watabiki             Hitachiko, 1060 Takeda, Hitachinaka City, Ibaraki Prefecture             Machine Co., Ltd. F-term (reference) 2C056 EA14 EA16 EA27 EB25 EB40                       EC07 EC24 EC33 EC54 FA13                       JB05 JC11 JC23

Claims (2)

[Claims] 1. A droplet discharge printing apparatus in which droplets are discharged from the print head onto a print medium that moves along the arrangement direction of one or more line-type print heads to perform printing. A print head moving unit that separates the head from the print medium by a desired distance, a control unit that controls the drive of the print head moving unit and the print head, and a print unit that separates the print medium by the desired distance. It has a droplet absorbing medium that moves in parallel with the moving direction of the print medium, and the droplet absorbing medium has holes of a size that allows the droplet discharge section of the print head to penetrate therethrough at the arrangement intervals of the print head. However, the control means preliminarily separates the print head from the print medium by a desired distance, and when the print head prints on the print medium, When the droplet discharge part of the character head is installed in a state of penetrating the hole of the droplet absorbing medium and the idle discharge operation of the print head is performed, the print head moving means moves the droplet absorbing medium to a desired position. Returning to a position for separating the distance, the hole portion of the droplet absorbing medium is moved from the front surface of the print head to interrupt the ejection to the print medium, and to perform the idle ejection of the droplet to the print medium. A droplet discharge printing apparatus, characterized in that the presence or absence of droplet discharge failure is detected by an optical measuring device or the like based on the discharge result formed on the droplet absorbing medium by the idle discharge operation of the print head. 2. The droplet ejection printing apparatus according to claim 1, wherein a window frame for visually confirming the droplet ejection failure on the droplet absorbing medium is provided on the droplet ejection printing apparatus cover. Droplet discharge printing device.