JP2001334685A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ink jet printer in which a transition can be made smoothly from stand-by mode to imaging mode by preventing a recording head from being clogged with ink during stand-by mode. SOLUTION: A recording head (52) is connected through a tube (53) with a solenoid valve (56) and the tube (53) is fed selectively with air, ink or cleaning liquid through the solenoid valve (56). At the time of imaging through the recording head (52), the recording head (52) ejects ink drops from nozzles controllably to an imaging medium within an imaging range thus imaging on the medium. The printer controller is preset with a stand-by time. The controller performs cleaning of the recording head (52) periodically during stand-by time, makes a transition to stand-by mode upon elapsing the stand-by time and collects ink from the recording head (52) and a sub-tank (54). When image data is received during this stand-by mode, the recording head (52) is cleaned and then a transition is made to imaging mode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet printer, and more particularly, to a sub-tank mounted on a recording head side, a main tank provided on a machine body side, and ink supplied in the main tank is supplied to the sub-tank. TECHNICAL FIELD The present invention relates to an ink jet printer that performs recording by a recording head of a mold type.

[0002]

2. Description of the Related Art In JP-A-10-86395 and others, an ink sub-tank is mounted on the recording head side, a main tank for ink is mounted on the machine body side, and ink is supplied from the main tank to the sub-tank. An ink jet printer has been disclosed which supplies ink from a sub tank to a recording head and discharges ink from the recording head to form an image on a sheet. Also. JP-A-5-29
Japanese Patent No. 4528 discloses an ink jet printer that guides a sheet on a large-diameter platen roller and forms an image with an ink jet recording head on the platen roller.

[0003]

Solvent ink is conventionally known as ink to be recorded on paper. This solvent ink has an advantage that the recording surface is hardly dropped because the ink dissolves in the paper. Therefore, it is not necessary to coat a protective film such as a laminate on the recording surface recorded on the paper with the solvent ink. However, the solvent ink has a high alcohol content and a high volatility, so that it is easier to dry than the water-based ink, but quickly solidifies. Further, there is a property that the pigment component is separated if left as it is. Therefore, when such a solvent ink or other ink that easily evaporates is used in an ink jet printer, when the controller executes printing from a printing standby state waiting for the printing data, the ink adheres to the recording head or the tube. When printing is performed in this state, there is a problem that ink may be clogged in the ink flow path of the recording head. An object of the present invention is to solve the above problems.

[0004]

In order to achieve the above object, the present invention provides a recording medium in which ink and cleaning liquid are selectively supplied to a recording head, and ink droplets are formed from nozzles of the recording head. In an inkjet printer that discharges in a controllable manner and prints on a drawing medium,
When image data is received during standby for image formation, a cleaning liquid is pressure-fed to the recording head to clean the inside of the recording head, and thereafter, shifts to the image formation mode. Further, the present invention provides an ink jet recording head and an ink sub-tank mounted on a Y cursor side capable of reciprocating in a Y-axis direction on a platen, providing a main tank for ink on a machine body side, and The ink in the main tank is supplied,
The recording head is configured to be supplied with the ink in the sub tank, the recording head is connected to an electromagnetic valve via a tube, and air, ink, and a cleaning liquid are selectively supplied to the tube through the electromagnetic valve. In the ink jet printer configured to discharge the ink droplets from the nozzles of the recording head onto the drawing medium in a controllable manner and perform drawing on the drawing medium, a drawing standby time is set in advance. The head is periodically cleaned, and after a printing standby time elapses, the printer shifts to a standby mode to collect ink from the print head and the sub-tank. It is intended to shift to. In the present invention, during the image forming standby, the ink blanking process of discharging ink from the nozzles of the recording head at the purge position and the head wiping process of wiping the nozzles of the recording head with a wiper at the wiping position are periodically performed. It is something to do. Also, in the present invention, the head cleaning includes an ink blanking process for purging and ejecting ink from nozzles of the recording head at a purge position, and closing the nozzles of the recording head with a cap and filling the ink in the recording head with a vacuum force in the cap. It is characterized in that it comprises an ink suction process for emptying the suction recording head and a head wiping process for wiping the nozzles of the recording head with a wiper at a wiping position. Also, the present invention
The cleaning of the recording head during the standby mode is characterized in that a cleaning liquid and air are alternately pressure-fed to the recording head at a purge position.

[0005]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In FIG.
(22) is a substrate (2) of the inkjet printer (24).
6) Legs (the other is not shown) arranged on the left and right sides, and a board (26) is fixed to the upper end of these legs. The legs (22) and the substrate (26) constitute the body of the inkjet printer (24).

A shaft holder (2) is provided on the upper part of the leg (22).
8) is fixed, and the shaft of the roll paper holder (32) is rotatably and detachably supported on the shaft holder (28). A roll portion (30a) of an image forming medium (30) wound in a roll shape is detachably held by the roll paper holder (32).

A platen (34) is provided on the substrate (26).
(Paper guide plate) is fixed, and near the upstream end of the platen (34), a guide roller (36) extending in the Y-axis direction and having substantially the same length as the width of the drawing medium (30) is arranged. .
The guide roller (36) is disposed above the roll portion (30a) of the roll paper (30), and both ends of the guide roller (36) are rotatably supported on the substrate (26) via a bracket. ing. (38) is a Y-axis rail, which is disposed horizontally above the platen (34),
Both ends are supported on the board (26) via brackets.

A Y-cursor (40) (carriage) is movably mounted on the Y-axis rail (38), and the Y-cursor (40) is a steel belt (42) endlessly stretched between pulleys. Through a Y-axis driving device (not shown) disposed on the substrate (26). A slit is formed in the platen (34) along the Y-axis direction, and a driving roller (44) is disposed in the slit.

Both ends of the driving roller (44) are rotatably supported on a substrate (26) via a bracket, and the driving roller (44) is connected to an X-axis driving device (shown in FIG. 1) provided on the substrate (26). (Omitted). The Y-axis rail (3
8), a pinch roller shaft (46) is attached to the pinch roller shaft (46) so as to be able to move up and down via an elastic mechanism (not shown), and is rotatably fitted to the pinch roller shaft (46).
8) is configured to be able to set one of a state of being separated from the surface of the drive roller (44) and a state of being in elastic contact with the surface horizontally.

A head base (50) is fixed to one side of the Y cursor (40), and four heads for four colors are provided on the head base (50).
Ink jet recording heads (5
2) is attached. The four rows of recording heads (5
2) The bottom surfaces arranged on the same plane as each other are elongated rectangles, and on the bottom surface, nozzles having a large number of ink ejection holes opened in a line are provided to protrude slightly.

Each of the four rows of recording heads (52) is arranged in parallel with each other at a predetermined distance from each other, and has a bottom surface with respect to an X-axis perpendicular to the Y-axis rail (38). Are arranged with a certain angle α. On the other side of the Y cursor (40), the same number of sub-tanks (54) for solvent ink of four colors (black K, cyan C, magenta M, and yellow Y) as the number of recording heads (52) are attached. The top lid of the sub-tank (54) has 3
One-way solenoid valve (56) is attached.

Each sub-tank (54) is provided with a sensor for detecting the ink level. The liquid supply surface of the sub-tank (54) corresponds to the recording head (52) such that the ink supply path, that is, the tube (53) between the recording head (52) and the corresponding sub-tank (54) is maintained at a negative pressure. 52) is disposed below the ink discharge port.

Reference numeral (58) denotes a main tank case provided on the substrate (26). The same number of main tanks (60) for four-color solvent ink as the sub-tanks (54) are provided (three are not shown). And a cleaning liquid tank (62) are detachably stored. Each tank (60) (62) is supported by a spring and sensors (136) (138) consisting of limit switches located below each tank (60) (62).
(See FIG. 8), the remaining amounts of the ink and the cleaning liquid are detected.

The main tank (60) and the sub tank (54) are connected via a solenoid valve to a tube cable (12).
It communicates by 2). Reference numeral (64) denotes a control box attached to the substrate (26), and the pump (66) and the solenoid valves (68) (70) (72) (7) shown in FIG.
4) (76) (78) (80) (82) (84) (8)
6) (88) (90) (92) (94) (96) (9)
8) Built-in (100) and (101), and further provided with an electronic control circuit for controlling these electronic devices.

A controller (not shown) for controlling the XY-axis driving device and the recording head (52) is attached to the substrate (26) of the printer (24).
(2) is a wiping device for cleaning the periphery of the nozzle on the bottom surface of the recording head (52) and the discharge port of the nozzle, and a rubber wiper reciprocates in the X-axis direction by the wiper motor (102) (see FIG. 8). It is configured to be driven. The wiper is provided with a V-groove. If the nozzle on the lower surface of the recording head (52) is positioned in the V-groove, the lower surface around the nozzle of the recording head (52) excluding the nozzle can be wiped by the wiper. When the recording head is moved to shift the V-groove from the nozzle, the nozzle can be wiped by the wiper.

(106) is a rubber cap (10) for covering the discharge port of the nozzle (52a) of the recording head (52).
8) and a purge box having a liquid discharge port (110) alternately. The purge box is disposed on the side of the substrate (26) outside the drawing range and in the moving range of the recording head (52). (See FIG. 8). The rubber cap (108) has an opening for receiving a fluid such as ink.

Each of the caps (108) and the discharge port (110) of the purge box (106) is connected to a collecting pipe (120) fixed to the substrate (26) via a tube and a solenoid valve.
Connected to (114) is a stirring motor for stirring the ink in the main tank (60), (116) is a waste liquid tank case attached to the leg (22), (1)
18) is a waste liquid tank.

The waste liquid tank (118) is provided with a case (1).
16) supported by a spring stored in the tank (11).
The waste liquid amount is detected by a sensor (134) (see FIG. 8) composed of a limit switch disposed between the bottom of 8) and the upper surface of the case (116).

At the bottom of each main tank (60),
A rotor made of a magnetic material is rotatably supported on a shaft, and the rotor is rotated by driving a motor (114) so that the ink in each main tank (60) is agitated. Each of the above components and devices is connected by a tube as shown in FIG. The recording head (52)
Is configured to be able to move out of the drawing range to just above the purge box (106) by moving the Y cursor (40) along the Y-axis rail (38).

Next, the operation of this embodiment will be described.
To set the drawing medium (30) on the platen (34), the pinch roller (48) is raised, and the roll (30) is set.
The drawing medium (30) is pulled out from a), inserted between the driving roller (44) and the pinch roller (48) via the guide roller (36), and then the pinch roller (48) is lowered, The pinch roller (48) is brought into elastic contact with the drive roller (44) from above the image forming medium (30).

Thus, the setting of the drawing medium is completed. When the setting of the drawing medium is completed and the printer enters the drawing mode, the controller performs an ink filling operation,
Thereafter, the operation proceeds to the drawing operation. When the drawing is started, the drawing portion of the drawing medium (30) is driven by the driving roller (4).
4) Due to the intermittent rotation in one direction, the sheet is conveyed on the platen (34) in the X-axis direction, that is, the arrow direction (C).

The recording head (52) is driven based on image information under the control of the controller, ejects ink from nozzles, and reciprocates along a Y-axis rail (38) of a Y cursor (40). , Is scanned along the Y-axis, and the image information developed in the memory of the controller is visualized on the drawing medium (30).

When the piezo element of the recording head (52) discharges ink, the piezo element automatically sucks the ink from the sub tank (54) accordingly. In this case, unless the sub tank (54) is set to a negative pressure, the recording head (52)
Means that ink is sucked too much and the ink flows out. In order to make the sub-tank (52) have a negative pressure, in the present embodiment, the level of the bottom surface of the sub-tank (54) is set lower than the ink ejection port of the recording head (52).

A standby transition sequence shown in FIG. 1 is stored in the controller, and a standby time is set in advance from the operation panel (step 1). The controller determines whether or not the mode is waiting for drawing data (step 2). If it is determined that the mode is not waiting for drawing data, the controller executes a drawing process (step 3), updates the standby time to H (step 4), and proceeds to step 2 Return to When the controller determines that the mode is waiting for image formation, it moves the recording head 52 onto the purge box (106) at predetermined time intervals, and purges and ejects ink from the nozzles of the recording head (52).
This purge discharge is performed by driving the nozzle drive actuator (piezo element) of the print head (52) at a frequency of 1 KHz.

Next, the controller operates the recording head (52).
Is moved to a position immediately above the wiping device (2), that is, to the wiping position, and the wiper motor (102) is driven to wipe around the nozzles of the recording head (52) with a rubber wiper (step 5). Next, the controller determines whether or not a predetermined time (for example, 20 minutes) has elapsed from the data waiting state (step 6). If the determination is affirmative, the controller shifts to head cleaning described later (step 7). Next, the controller determines whether or not the standby time H has elapsed (step 8). If the determination is negative, the controller returns to step 2, and if it determines affirmatively, the controller shifts to a standby mode described later (step 9).

Next, the controller determines whether or not the mode is waiting for the drawing data (step 10), and if not, shifts to the head cleaning described later (step 11).
This head cleaning is for the purpose of flushing out the ink adhering to the inner wall of the recording head (52) and the tube (53) connected thereto, and for the purpose of moistening the recording head (52) with the cleaning liquid to facilitate the suction of the ink. is there. When the head cleaning is completed, the controller next fills the sub tank (54) with ink from the main tank (60),
Next, the recording head (52) is moved right above the cap (108). Next, the pump solenoid valves (68) and (70) are switched to the suction direction, and the pump-waste liquid tank solenoid valve (72) is switched.
(101) is switched to the suction direction.

Next, the motor (112) is driven to raise the purge box (106), the cap (108) is pressed against the lower surface of the recording head (52) where the nosle is opened, and the recording head is pressed by the cap (108). Close the nozzle of (52). Next, the controller drives the pump (66) to bring the waste liquid tank (118) to a negative pressure. This allows
The recording head (52) sucks the ink in the sub tank (54). Next, the controller detects the amount of ink in the sub-tank (54), and when a predetermined amount of ink has been supplied from the sub-tank (54) to the recording head (52), stops suction of the pump (66) and sucks ink. To stop. This completes the filling of the recording head (52) with the ink (step 12).

At this time, the solenoid valve (9) for the discharge port (110)
2) is closed. After stopping the suction of the pump (66), the controller drives the motor (112) to lower the purge box (106), remove the cap (108) from the recording head (52), and move the Y cursor (40). Is Y
It moves to the drawing position along the axis rail (38). next,
Next, the controller controls the waste liquid tank solenoid valve (101) and the cap solenoid valves (92) (94) (96) (98) (10).
Release 0) to the atmosphere. Thereby, the cap (10
The ink in 8) falls freely on the collecting pipe (120).

Next, the controller executes drawing (step 13), updates the standby time to H (step 1).
4) Return to step 2. The controller proceeds to step 1
If the judgment is affirmative at 0, the recording head (5
2) is moved to the head wiping position, and the recording head (5) is moved.
Wiping around the nozzle of 2) (Step 1)
5). The purpose of performing wiping at a predetermined time interval even in the standby mode is to prevent drying around the head nozzle. Next, the controller turns off the power switch.
It is determined whether it is F or not. If it is not OFF, the process returns to step 10, and if it is OFF, the power of the printer is turned off (step 17).

Next, the head cleaning operation will be described with reference to FIG.
This will be described with reference to the flowchart shown in FIG. The characteristic of this cleaning operation is that the ink is purged and ejected from the nozzles of the recording head, and then the ink is forcibly sucked by the capping suction operation, and then the nozzle at the bottom of the recording head is removed.
Wiping (wiping) around the nozzle. When the controller starts the cleaning operation, the controller moves the recording head (52) to the purge position, that is, the discharge port (11).
0), and position the nozzle (52a) immediately above the discharge port (110) (Step 1).

Next, the controller operates the sub tank (54).
Is detected by a sensor signal as to whether or not the ink amount is at the high level (step 2). If it is determined that the ink amount is not at the high level, ink is supplied from the main tank (60) to the sub tank (54) (step 2). Step 3). If the controller determines that the ink amount in the sub-tank (54) is at the high level, the controller then moves the recording head (52) immediately above the cap (108) (step 4). Next, the controller purges and ejects about 100 shots of ink from the nozzles (52a) of the recording head (52) at high speed (step 4). Next, the controller switches the pump solenoid valves (68) and (70) in the suction direction, and switches the pump-waste liquid tank solenoid valves (72) and (101) in the suction direction.

Next, the controller drives the motor (112) to raise the purge box (106). When the rise of the purge box (106) approaches the top dead center, first, the cap (108) is pressed against the bottom surface around the nozzle of the recording head (52) by the elastic force of the coil spring, and the nozzle is sealed by the cap (108). (Step 6).
When the purge box (106) reaches its highest position, this position is detected by a sensor, and the controller detects the position of the motor (1).
The driving of 12) is stopped. In this state, the cap (108) resiliently contacts the bottom surface of the recording head (52) in a state in which the cap (108) is slightly retracted from the upper plate portion of the purge box (106) from the initial projecting position against the elasticity of the coil spring (not shown). .

In this state, the cap solenoid valve (94)
(96), (98) and (100) open and the outlet solenoid valve (9
2) is closed. Next, the controller operates the pump (6).
6) is driven to make the pressure in the waste liquid tank (118) negative (step 7), and the ink in the recording head (52) is discharged from the tube (53) between the recording head (52) and the solenoid valve (56). The ink including the ink in the parentheses is sucked into the waste liquid tank (118) several times at intervals of 10 seconds continuously and 20 seconds intermittently (step 8).

This ink suction is continued until the ink amount in the sub-tank (54) reaches the low level (step 9). When the ink level reaches the low level, the controller stops driving the pump (66) and the recording head (52). ) And the operation of sucking ink from the sub tank (54) is stopped (step 10). Thereby, the inside of the recording head (52) and the inside of the tube (53) become empty. Next, the controller opens the waste liquid tank solenoid valve (101) and the cap solenoid valves (92), (94), (96), (98), and (100) to the atmosphere to collect the ink in the cap (108) into the collecting pipe ( 1
Drop freely on 20) (step 11).

Next, the controller operates the purge box (1).
06) to lower the recording head (52) with the cap (10).
8), the nozzle (52a) of the recording head (52)
Is in an open state. Next, the controller moves the Y cursor (40) along the Y-axis rail (38), and moves the bottom surfaces of the four rows of the first recording heads (52) to just above the wiper movement passage (step 13). . At this time, since the wiper (14) is located at one end of the wiper moving passage in advance, the recording head (52) can move right above the wiper moving passage without colliding with the wiper.

Next, the controller drives the motor (102) to rotate the feed screw. By the rotation of the feed screw, the wiper moves from one standby position to the recording head (52) along the wiper moving path. When the wiper reaches the recording head (52), the upper edge of the wiper collides with the bottom of the recording head (52), the wiper bends due to its elasticity, and the upper edge elastically contacts the bottom surface of the recording head (52). At this time, the relief formed by the V-groove of the wiper is located at the nozzle, and the ink discharge surface of the nozzle remains open.

Further, the wiper moves in the scanning direction of the bottom surface while elastically contacting the bottom surface of the recording head (52) (step 1).
4). After the wiper (14) scans substantially the entire area of the bottom surface of the recording head (52) and removes ink, dust, and the like adhering to the bottom surface, the wiper comes off the recording head (52), and the wiper moves. Move to the other standby position in the passage.
When the bottom surface of the recording head (52) is wiped with the wiper, the nozzle portion does not contact the wiper due to the escape of the wiper.
For this reason, dust, lint or the like, or a mass of ink adhering to the nozzle is not pushed into the ejection hole of the nozzle by the wiper, and thus clogging of the nozzle can be prevented.

Next, the controller moves the Y cursor (4) along the Y-axis rail (38) by a predetermined amount, and moves the bottom surface of the recording head (52) in the second row to just above the wiper moving passage. Next, the motor (102) is driven in the reverse rotation direction, and the wiper moves in the direction of the original standby position along the wiper moving path, and the nozzles of the second row of recording heads (52) are removed, excluding the nozzles. Wipe off substantially the entire area of the surrounding bottom surface with the upper edge of the wiper.

In the manner described above, the wiping of the bottom surfaces of the recording heads (52) in the third and fourth rows is sequentially performed to complete the wiping operation. Next, the controller sets the recording head (5
2) is moved to the purge position (step 15), and the ink is purged (step 16). As shown in FIG. 2, the standby mode includes an ink recovery operation (step 1) and a head cleaning operation (step 2). Next, the ink collecting operation will be described with reference to the flowchart of FIG.

First, the controller operates the pump solenoid valve (6).
8) (70) is switched to the suction direction (step 1), and the pump-main tank solenoid valve (76) is switched to the suction direction (step 2). Further, the sub tank atmospheric release solenoid valve (90) is released to the atmosphere (step 3). Further, the main tank-sub tank solenoid valves (80), (82), (8)
4) (86) is opened (step 4), and the pump (66) is driven to suck the ink in the sub tank (54) into the main tank (60) (step 5). Next, after a lapse of a predetermined time, the controller determines whether or not there is ink in the sub tank (54) (step 6).

When it is determined that there is ink, an error is displayed on the display unit of the controller (step 7), and the process proceeds to error processing (step 8). If it is determined that there is no ink in the sub-tank (54), the pump (66) is driven for a predetermined time to suck the ink in the sub-tank (80) into the main tank (60). 6
6) is stopped (step 9). In this state, ink in the sub tank (54) and the tube cable (122) between the sub tank and the main tank are removed from the main tank (6).
0). Next, the solenoid valve (56) and the sub-tank air release valve (90) are shut off (step 10). Next, the motor (114) is driven, the magnet is rotated, and the rotor in the main tank (60) is rotated by magnetic force to agitate the ink in the main tank (60) for a predetermined time (step 11). .

Next, a capping suction operation described later is performed (step 12). Next, the cap (108) is released from the recording head (52) (Step 13), and the waste liquid tank solenoid valve (101) and the cap solenoid valves (92), (94), (9)
6) Release (98) and (100) to the atmosphere (Step 1)
4). Thus, the ink in the cap (108) is allowed to freely fall to the collecting pipe (120) (Step 15), and the ink collecting operation is completed.

Next, the above capping operation will be described with reference to the flowchart of FIG. First, the controller determines whether or not the waste liquid tank (118) is full based on a signal from the sensor (134) (step 1). If the determination is affirmative, the waste liquid tank full is displayed (step 2). ), And shifts to error processing (step 3). When a negative determination is made, the recording head (52) is closed with the cap (1).
08) (step 4). Next, the pump solenoid valves (68) and (70) are switched to the suction direction (step 5), and the pump-waste liquid tank solenoid valves (72) and (101) are switched.
Is switched to the suction direction (step 6).

Next, the motor (112) is driven to raise the purge box (106), and the cap (108)
Is pressed against the recording head (52), and the cap (108) is pressed.
To close the nozzle of the recording head (52). In this state, the solenoid valve (56) is switched to the sub tank direction,
The cap solenoid valves (94), (96), (98) and (100) are open, and the outlet solenoid valve (92) is closed.

Next, the controller drives the pump (66) to make the pressure in the waste liquid tank (118) negative, and the ink in the sub tank (54) and the recording head (52) is transferred to the recording head (52). The ink including the ink in the tube (53) between the solenoid valve (56) and the ink is sucked out to the waste liquid tank (118) side (step 7). When the ink in the sub-tank (54) reaches the LOW level (step 8), the controller stops driving the pump (66) and stops the operation of sucking ink from the recording head (52) (step 9). As a result, the inside of the recording head (56) and the inside of the tube (53) become empty.

Next, the head cleaning operation will be described with reference to the flowchart of FIG. First, the controller of the printer determines whether or not there is a remaining amount in the cleaning liquid tank (62) based on a signal of the sensor (138) (step 1). The remaining of the cleaning liquid tank is displayed (not shown) (step 2), and error processing is performed (step 3).

If it is determined that there is a residual amount, pressurization of the cleaning liquid tank (62) is started (step 4), and air is fed to the cleaning liquid tank (62) to increase the pressure in the cleaning liquid tank (62). Pressure is applied (step 5). This pressurizing operation switches the pump-main tank solenoid valves (72), (74) and (76) in the direction of the washing liquid tank with the solenoid valve (78) closed, and drives the pump (66) to operate the washing liquid tank. (6
2) Send air into the chamber. Next, as shown in FIG. 9, the controller moves the recording head (52) to a position immediately above the discharge port (110) of the purge box (106), that is, to the purge position (step 6). FIG. 9 shows one recording head (52) out of four recording heads for convenience of explanation.
Only a part of the purge box (106) is shown.

Next, the controller opens the solenoid valve (78) and switches the solenoid valve (88) and the solenoid valve (56) of the target first row recording head (52) in the direction of the cleaning liquid tank. A high-pressure cleaning solution is applied to the nozzles of the target recording head (52) and the corresponding tubes (53) at a high speed of about 1 KHz by driving the nozzle drive actuator (piezo element) of the recording head (52) at a frequency of 1 KHz.
For 2 seconds (step 7). Next, the controller closes the solenoid valve (78) and sets the head air solenoid valve (74) (8).
8) is switched to the air feeding direction, and the solenoid valve (56) of the target recording head (52) is switched to the air feeding direction, and the driving force of the pump (66) causes the recording head to target the air at a high pressure. The nozzle (52) and the corresponding tube (53) are pressure-fed for about 10 seconds while the nozzle drive actuator of the recording head (52) is driven at a high frequency of 1 KHz (step 8).

By the alternately high-pressure cleaning liquid supply and high-pressure air supply, the remaining ink in the recording head (52) and in the tube wall of the ink passage of the tube (53) is peeled off, and the ink is pushed down in the ink passage and discharged from the nozzle. Is discharged. Next, the controller determines whether or not a predetermined number of times (in the present embodiment, once) of alternately performing the high-pressure cleaning liquid pressure-feeding and the high-pressure air pressure-feeding to the target recording head (52) (step 9). If the number has not reached, the process returns to step 7, and if the number has reached the predetermined number, the target recording head (52) is positioned just above the cap (108) of the purge box (106), that is, at the capping position (step 10). ).

Next, the controller sends air to the target recording head (52) under pressure for about 10 seconds, and blows air from nozzles of the recording head (52) to clean the cap portion (step 11). Next, the controller returns the target recording head (52) to the purge position (Step 12). Next, the controller alternates between high-pressure cleaning liquid pumping for about 5 seconds (step 13) and high-pressure air pumping for about 10 seconds (step 14) while driving the nozzle drive actuator of the recording head at a high frequency of 1 KHZ. The pumping operation is performed. The residual ink in the target recording head (52) and the tube (53) is swept away by this pressure feeding operation.

Next, the controller sets the target recording head (5
It is determined whether or not the alternate pumping operation of the high-pressure cleaning liquid pumping and the high-pressure air pumping for 2) has been performed a predetermined number of times (once in this embodiment) (step 15). When it is determined, the operations of steps 13 and 14 for the target recording head (52) are completed. The operations of steps 13, 14, and 15 are performed for each of the four recording heads (52), and when the high-pressure feeding operations of steps 13, 14, and 15 are completed for all the recording heads (52). Next, the controller sets the waste liquid tank (118) to a negative pressure, and collects waste liquid such as cleaning liquid accumulated in the collecting pipe (120) into the waste liquid tank (118) (step 16).

Next, the controller sends high-pressure air to one target recording head (52) for about 40 seconds (step 17), moves the recording head (52) to the capping position, and immediately purges. Return to position (Step 1
8). This operation is performed by the four recording heads of KCMY (52).
Run every time. When air is ejected from the nozzles of the recording head (52), the droplets adhering to the lower surface of the recording head (52) are dried to reduce the number of droplets, and the discharge port (11)
The area around 0) is cleaned.

Thereafter, the recording head (52) moves from the purge position to the capping position, and returns to the purge position instantaneously, whereby the inertia of the recording head (52) removes the ink remaining on the lower surface of the recording head (52). The mixed droplets are shaken off, and the droplets are removed from the purge box (10
The liquid falls into the liquid discharge port (110) or the receptacle of the cap (108) and is stored in the collecting pipe (120).

Next, the controller determines whether or not the above-mentioned drop-off operation has been performed a predetermined number of times (two times in this embodiment) for each of the four recording heads (52) (step 1).
9) If the judgment is negative, the process returns to step 17, and if the judgment is affirmative, the controller turns on a vacuum device (not shown) for generating an intake force on the platen (34).
Then, the sheet is brought into close contact with the platen (34) (step 20). Next, the controller moves the recording head (52) to a position immediately above the wiping device (2), that is, to the wiping position (Step 21).

Next, air is pressure-fed to the target recording head (52), and while bleeding air from the nozzles of the recording head (52), the wiper motor (102) is driven to make the rubber wiper one-way. , And wipe the nozzle portion of the target recording head (52) with the wiper (step 22). Next, the controller stops pneumatic feeding to the target recording head (52). Next, the controller slightly shifts the target print head (52) with respect to the wiper, and reciprocates the wiper with respect to the target print head (52) by driving the motor (102). Recording head (52)
The wiping is performed on the periphery of the nozzle excluding the nozzle (step 23).

The controller performs the wiping operation as described above.
This is executed for each of the KMCY recording heads (52).
Next, the controller switches the solenoid valve (76) to the atmosphere side, and opens the cleaning liquid tank (62) to the atmosphere (step 24). Next, the controller decompresses the waste liquid tank (118), collects the waste liquid in the waste liquid tank (118) (Step 25), and collects the waste liquid in the cap portion of the purge box (106) (Step 26).

Next, the controller switches the solenoid valve (101) to the atmosphere side, opens the waste liquid tank (118) to the atmosphere (step 27), and completes the cleaning operation of the recording head (52). During the first stage of steps 5 to 16 and the second stage of steps 17 to 19, the sub-tank (54) is not released to the atmosphere.
This is to prevent the high-pressure cleaning liquid or high-pressure air from flowing back to the tube on the sub-tank (54) side when the head-sub-tank solenoid valve (56) is switched. Note that the high-pressure pumping of the cleaning liquid and air is performed while driving the piezo element, which is the nozzle drive actuator of the recording head, with a high-frequency drive signal as described above, while driving the piezo element with a high-frequency drive signal. Is not particularly limited to the pressure feeding.

In the operation of the second stage of the above embodiment, the recording head (52) is moved between the purge position and the cap position in order to shake off the droplets adhering to the lower surface of the recording head (52). The operation of dropping the droplet is not particularly limited to the above-described embodiment. As shown in FIG. 10, the recording head (52) is vibrated at the purge position, and the droplet is discharged to the liquid outlet (110). May be dropped.

[0059]

Since the present invention is constructed as described above, it is possible to prevent clogging of the ink in the recording head even if the ink has a high image forming volatility and the ink component is easily separated, thereby achieving high quality. You can draw.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an operation of a standby shift sequence.

FIG. 2 is a flowchart showing an operation in a standby mode.

FIG. 3 is a flowchart illustrating an ink collecting operation.

FIG. 4 is a flowchart showing a capping suction operation.

FIG. 5 is a flowchart showing a cleaning operation.

FIG. 6 is a flowchart illustrating a head cleaning operation.

FIG. 7 is an external view of an inkjet printer.

FIG. 8 is an explanatory diagram of piping showing an ink supply system of the plotter.

FIG. 9 is an explanatory diagram showing a drop-off operation of a recording head.

FIG. 10 is an explanatory diagram showing another embodiment of the dropping operation of the droplet of the recording head.

[Explanation of symbols]

 2 Wiping Device 22 Leg 24 Inkjet Printer 26 Substrate 28 Shaft Holder 30 Drawing Medium 30a Roll 32 Roll Paper Holder 34 Platen 36 Guide Roller 38 Y-Axis Rail 40 Y Cursor 42 Steel Belt 44 Drive Roller 46 Pinch Roller Shaft 48 Pinch Roller 50 Head base 52 Ink jet recording head 53 Tube 54 Sub tank 56 Solenoid valve 58 Main tank case 60 Main tank 62 Cleaning liquid tank 64 Supply controller 66 Solenoid valve 68 Solenoid valve 70 Solenoid valve 72 Solenoid valve 74 Solenoid valve 76 Solenoid valve 78 Solenoid valve 80 Solenoid valve 82 solenoid valve 84 solenoid valve 86 solenoid valve 88 solenoid valve 90 solenoid valve 92 solenoid valve 94 solenoid valve 96 solenoid valve 98 solenoid valve 100 solenoid valve 101 solenoid valve 102 wiper motor 10 Purge box 108 cap 110 fluid outlet 112 motor 114 motor 116 waste tank case 118 waste liquid tank 120 collection tube 122 tube cable 134 sensor 136 Sensor 138 Sensor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C056 EA14 EA16 EA27 EC04 EC08 EC54 EC56 EC57 FA10 JB04 JC20 JC23 KB04 KB08 KB15 KB21 KB37 KD01

Claims (5)

[Claims] An ink and a cleaning liquid are selectively supplied to a recording head, and ink droplets are controllably ejected from a nozzle of the recording head to an image forming medium to form an image on the image forming medium. Inkjet printer
An ink jet printer, wherein, when image data is received during image forming standby, a cleaning liquid is pressure-fed to the recording head to wash the inside of the recording head, and thereafter, shifts to an image forming mode. 2. An ink jet type recording head and a sub tank for ink are mounted on a Y cursor side which can reciprocate in the Y axis direction on a platen, and a main tank for ink is provided on a body side, and the main tank is provided in the sub tank. The ink in the tank is supplied, the recording head is supplied with the ink in the sub-tank, the recording head is connected to an electromagnetic valve via a tube, and air and ink are supplied to the tube through the electromagnetic valve. The cleaning liquid is selectively supplied, the ink droplets are ejected from the nozzles of the recording head to the image forming medium in a controllable manner, and the image forming standby time is set in advance in the ink jet printer. Set and perform regular head cleaning during this print standby time. An ink jet printer, wherein ink is collected from a recording head and a sub tank, and when image data is received during the standby mode, the recording head is washed and then the mode shifts to an image forming mode. 3. An ink ejection process for discharging ink from nozzles of a recording head at a purge position and a head wiping process for wiping the nozzles of the recording head with a wiper at a wiping position are periodically performed during the image formation standby. 3. An ink jet printer according to claim 2, wherein: 4. The head cleaning includes an ink blanking process for purging and ejecting ink from nozzles of a recording head at a purge position, and closing the nozzles of the recording head with a cap and sucking out ink in the recording head into the cap with a vacuum force. 3. The ink jet printer according to claim 2, comprising an ink suction process for emptying the print head and a head wiping process for wiping a nozzle of the print head with a wiper at a wiping position. 5. The ink jet printer according to claim 2, wherein the cleaning of the recording head during the standby mode is performed by alternately feeding a cleaning liquid and air to the recording head at a purge position. .