JP5200878B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that performs recording by discharging a liquid such as ink from a nozzle. Specifically, the cleaning liquid is supplied from a cleaning liquid tank to a cap member to clean the nozzle surface, the inside of the cap member, a suction path, and the like. The present invention relates to an image forming apparatus configured to be able to retain moisture.

In an inkjet image forming apparatus, if an ejection head is left exposed to air after an image forming operation (including the concept of a printing operation or a recording operation), the ink in the nozzle holes will be dried and solidified. There are nozzles that do not eject ink during image formation, and defects such as missing images occur.
In order to eliminate this problem, the nozzle surface of the ejection head is closely covered with a cap member during non-image formation, and the drying and solidification of ink due to the nozzle holes being directly exposed to the outside air is suppressed.

Since the nozzle hole is not reliable for preventing ink drying and solidification only by sealing with the cap member, when the image formation is started, the inside of the cap member is set to a negative pressure by the suction means connected to the cap member. The thickened ink is sucked and collected in the waste liquid tank.
Further, the cleaning liquid is sent from the cleaning liquid tank after ink suction into the cap member so that the suction path (tube) is not clogged by the increased viscosity of the sucked ink. Therefore, the suction of the ink in the nozzle hole is sucked together with the cleaning liquid, and the mixed liquid of the ink and the cleaning liquid is collected in the waste liquid tank.
The discharge of the cleaning liquid to the waste liquid tank leads to cleaning of the residual ink in the suction path, and also contributes to prevention of suction failure due to clogging of the suction path due to thickening of the residual ink.

If the cleaning liquid is supplied only to the nozzle hole, the ink in the nozzle hole does not touch the air, so that drying and solidification can be prevented. Due to the increase in the humidity in the cap member due to the presence of the cleaning liquid, it is possible to suppress drying and solidification of the ink.
In Patent Document 1, for the purpose of preventing clogging of the nozzle opening, the dissolving liquid is supplied from the dissolving liquid tank to the sealing space between the cap member and the nozzle to directly dissolve the clogging of the nozzle opening, A capping device for moisturizing the ink is disclosed.
In Patent Document 2, for the purpose of maintaining the discharge performance and improving the reliability, the capping means is provided with a negative pressure generating means and a valve means, and a nozzle array for suction recovery by selectively controlling the valve means. A technique for making it selective is disclosed.
In Patent Document 3, ink in the cap member and the drain tube is used by the operation after the completion of printing for the purpose of preventing the performance of the suction pump from being deteriorated or the clogging of the suction path due to thickening of the ink when left for a long time in the suction path. A control for changing the amount of suction is disclosed.

JP 2002-234174 A JP 2004-42446 A JP 2006-142658 A

In the conventional technology, since the cleaning liquid supplied up to the cap member is collected in the waste liquid tank by the ink suction operation, the cleaning liquid once supplied cannot be reused and a large amount of cleaning liquid is required. Inevitable increase in size.
On the other hand, since the amount of waste liquid corresponding to the cleaning liquid increases, a large waste liquid tank is required, and there is a problem that an increase in the size of the apparatus cannot be avoided.
In addition, when the conventional method is applied to a line printer instead of a serial printer, a large amount of cleaning liquid is required because ink is uniformly sucked and cleaning liquid is supplied to each head, and the above problem becomes significant.

  The main object of the present invention is to provide an image forming apparatus that can reduce the amount of cleaning liquid used, and thus contribute to downsizing of the apparatus, and is particularly suitable for a line printer.

In order to achieve the above object, according to the first aspect of the present invention, a plurality of heads that discharge liquid from a nozzle toward a recording medium, and the plurality of heads are provided corresponding to each of the plurality of heads. A plurality of cap members for sealing each nozzle surface and sucking liquid from the nozzle surface; a suction means connected to each of the plurality of cap members for forming a negative pressure in the cap member; and the suction And a waste liquid tank in which liquid sucked from the plurality of cap members is discharged, and a path between each of the plurality of cap members and the suction means, and the plurality of cap members can be selectively sucked. A plurality of cap on-off valves for opening and closing the path, a cleaning liquid tank for storing a cleaning liquid supplied to each of the plurality of cap members,
A cleaning liquid supply means for supplying the cleaning liquid in the cleaning liquid tank to each of the plurality of cap members, and disposed downstream of the cap on-off valve in the suction path of the suction means, and with respect to the plurality of cap on-off valves A switching valve that connects one of the waste liquid tank and the cleaning liquid tank and disconnects the other, and when the liquid is sucked from the nozzle surface , the switching valve is switched to clean the cleaning liquid in the cap members The switching valve is controlled so that the liquid is sucked from the nozzle surface and then the liquid sucked from the nozzle surface is guided into the waste liquid tank .

In the invention described in claim 2, in the image forming apparatus described in claim 1, when there is a nozzle that detects whether or not liquid is discharged from the nozzle and there is a nozzle that does not discharge, The liquid suction operation and the cleaning liquid supply operation are performed only on the head having the nozzle.
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the cleaning liquid in the plurality of cap members has a humidity detection unit that detects humidity, and according to a detection value of the humidity detection unit. The amount is controlled so as to be variable.

According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the head unit integrally including the plurality of heads;
A maintenance unit that has at least the cap member and the cap opening and closing valve and maintains and recovers the performance of the head, and the head unit is movable in a direction perpendicular to the conveyance surface of the recording medium; The maintenance unit is movable in parallel with the transport surface, and when the recording operation is performed, the maintenance unit is separated from the head unit from a capping position facing the head unit. A liquid level detecting unit configured to move in parallel to the surface and set to a standby position and detect a liquid level height of the cleaning liquid in the plurality of cap members, and the liquid level height exceeds a predetermined value; In this case, the maintenance unit is moved to the standby position with the liquid level lowered.

According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the image forming apparatus further comprises means for detecting the concentration of the cleaning liquid in the cleaning liquid tank, and the concentration of the cleaning liquid in the cleaning liquid tank is predetermined. When the value is exceeded, the switching valve is controlled so that the cleaning liquid in the plurality of cap members is discharged to the waste liquid tank without returning to the cleaning liquid tank .
According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the means for detecting the concentration of the liquid in the path on the path between the cap on-off valve and the switching valve. When the concentration of the liquid in the path exceeds a predetermined value, the switching valve is controlled so that the cleaning liquid in the plurality of caps is discharged to the waste liquid tank without returning to the cleaning liquid tank. It is characterized by that.
According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, the suction unit also serves as the cleaning liquid supply unit .

According to the present invention, it is possible to reduce the amount of the cleaning liquid used, thereby contributing to downsizing of the apparatus.
Especially when applied to line printers, the degree of miniaturization is large.

Embodiments of the present invention will be described below with reference to the drawings.
First, an outline of the configuration of an ink jet printer (line printer) as an image forming apparatus according to the present embodiment will be described with reference to FIG. The ink jet printer 100 is configured to maintain / recover ink ejection performance of a paper transport unit 30 that transports a paper as a recording medium (not shown), a head unit 1 disposed on the upper surface side of the paper transport unit 30, and the head unit 1. Maintenance unit 80 and the like.
The paper transport unit 30 includes two support rollers 32 and 33, one of which is a driving roller, and a transport belt 31 that is wound around these rollers.
A sheet P fed from a sheet feeding means (not shown) is formed on an ink image by the head unit 1 positioned at a recording position (position shown in FIG. 6) while being conveyed on the conveyance belt 31 at a predetermined timing. The paper is discharged and stacked by a paper discharge means on a paper discharge tray (not shown).

The head unit 1 includes a plurality of heads 11, a holder plate 12 that integrally holds these heads, a base plate 71, and the like.
As shown in FIG. 8, each head 11 has a plurality of nozzles 11b that eject ink droplets, and the ejection side of the nozzle 11b is a nozzle surface 11a.
As shown in FIG. 6, the head unit 1 can be moved in the vertical direction (in this case, the up-down direction) indicated by the arrow V with respect to the paper transport surface of the transport belt 31 by the head unit moving means 1 a (see FIG. 3). Thus, a recording position (also referred to as an image forming position or a printing position) shown in FIG. 6 and a retracted position described later are selectively set.
The maintenance unit 80 includes a plurality of cap members 81 corresponding to the number of the heads 11, a support member 91 that supports these cap members, and the like. The plurality of cap members 81 can move in the vertical direction independently of the support member 91, and the vertical movement is performed by a cap vertical means 104a (see FIG. 3) described later.
The maintenance unit 80 can be moved in a parallel direction (here, a horizontal direction) as indicated by an arrow H with respect to the paper conveyance surface of the conveyance belt 31 by a maintenance unit driving means 80a (see FIG. 3), as shown in FIG. A standby position and a capping position described later are selectively set.

The operation after the end of the printing operation will be described with reference to FIG.
When the printing operation is completed, the head unit 1 moves up to the retracted position (FIG. 7A), and then the maintenance unit 80 moves horizontally and is set to a capping position that faces the lower surface of the head unit 1 (FIG. 7). (B)).
In this state, a gap g exists between the nozzle surface 11a of each head 11 of the head unit 1 and the cap member 81 of the maintenance unit 80, and is separated (decapped).
Thereafter, each cap member 81 is raised by the cap lifting means 104a (see FIG. 3) of the cap device 104, and each nozzle surface 11a is sealed (FIG. 7C).
When performing the printing operation, the cap member 81 is lowered from the state shown in FIG. 7C to the decap state shown in FIG. 7B by the cap up-and-down means 104a, and the maintenance unit 80 moves to the standby position in this state. The head unit 1 is lowered to the recording position. During these operations, an ink suction operation and a cleaning liquid supply operation are performed, which will be described later.

The operation of the inkjet printer 100 is controlled by a control unit (control means) 100 shown in FIG.
A control unit 100 as a microcomputer includes a ROM 101, a CPU 102, a RAM 103, and the like. The CPU 102 controls the operation of the image forming apparatus main body based on detection signals from various sensors provided in the image forming apparatus main body and an operation program called from the ROM 101.
The ROM 101 stores an operation program for the entire image forming apparatus main body, and this operation program is appropriately called by the CPU 102. The RAM 103 has a function of temporarily storing calculation results of the CPU 102, a function of storing data signals and ON / OFF signals set and input from various sensors as needed.

The maintenance unit driving unit 80a moves the maintenance unit 80 from the capping position in the horizontal direction to the standby position in a decap state where the cap member 81 and the nozzle surface 11a are separated from each other at the start of printing.
The cap up-and-down means 104a of the cap device 104 moves the cap member 81 to a position for sealing the nozzle surface 11a after the maintenance unit 80 is set at the capping position. Further, the cap member 81 is driven to be separated from the nozzle surface 11a during decap.
In the head unit moving means 1a, the head unit 1 moves upward during capping, the maintenance unit 80 moves downward, takes the capping position, and during printing, the maintenance unit 80 moves horizontally while maintaining the decap. Then, after reaching the standby position, the head unit 1 is controlled to move downward to the printing position.
In the present embodiment, the cap member 81 is brought into contact with and separated from the nozzle surface 11a by the vertical movement of the cap member 81, but the head unit 1 may be moved up and down.

  The temperature / humidity sensor 105 a serving as the temperature / humidity detection means 105 can measure the temperature / humidity near the head unit 1 and is configured to send measurement data to the control unit 100.

The configuration and function of the maintenance unit 80 will be described in detail with reference to FIG.
As described above, the maintenance unit 80 serves as a maintenance and recovery mechanism that maintains and recovers the performance of the plurality of heads 11 that eject ink droplets as liquid.
The maintenance unit 80 is a plurality of cap members 81 for covering the nozzle surface 11a of the head while maintaining high airtightness, a suction unit for sucking and discharging the thickened ink from the nozzles 11b, and a cleaning liquid for supplying a cleaning liquid A pump 82 as supply means, a switching valve 83a connected to the downstream side of the suction path of the pump 82, a waste liquid tank 84 connected to one of the switching valves 83a, a cleaning liquid tank 85 connected to the other, and the like. .
The waste liquid tank 84 and the cleaning liquid tank 85 are made of, for example, a resin such as polyethylene and are sealed. The waste liquid tank 84 and the cleaning liquid tank 85 are provided with air release valves 84a and 85a. The pump 82 is composed of a tube pump capable of forward and reverse rotation, and operates to suck liquid from the cap member 81 during forward rotation, and can feed liquid from the cleaning liquid tank 85 toward the cap member 81 during reverse rotation. It has a configuration like this.

Although not shown, a conventionally known wiper member (wiper, wiper blade) for wiping and removing ink adhering to the nozzle surface 11a, a wiper cleaner (wiper cleaning member) for cleaning the wiper member, and the like are provided.
Under the plurality of cap members 81, cap opening / closing valves 86 a, 86 b, 86 c, 86 d, 86 e that open and close the suction paths 87 of the plurality of cap members 81 are provided, and the suction paths of the plurality of cap members 81 are provided. 87 can be selectively opened and closed.
As the maintenance unit 80, the whole of the above components may be moved horizontally, but in the present embodiment, the cap unit 81 and the cap opening / closing valve 86 are formed by utilizing the flexibility of the path 87 made of a soft tube. Only the unit is moved horizontally, and the waste liquid tank 84 and the cleaning liquid tank 85 are fixed in position.

  As shown in FIG. 2, pumps 82 a and 82 b may be provided in the waste liquid tank 84 on the downstream side of the suction path 87 of the switching valve 83 a and the supply path 88 of the cleaning liquid tank 85, respectively. However, since the number of pumps 82 is larger than the configuration shown in FIG.

The maintenance / recovery operation by the maintenance unit 80 in this embodiment will be described.
[Ink discharge operation]
As shown in FIG. 1, the space 81a sealed between the nozzle surface 11a and the cap member 81 is filled with the cleaning liquid to such an extent that the cleaning liquid does not contact the nozzle surface 11a.
The control unit 100 drives the switching valve 83a so that the cleaning liquid flows into the waste liquid tank 84, and opens the air release valve 84a provided in the waste liquid tank 84. The switching valve 83a and the atmosphere release valve 84a are configured by electromagnetic valves or the like.
Thereafter, the cap opening / closing valve 86 a downstream of the cap member 81 is released, and the pump 82 is driven forward so that the cleaning liquid is discharged to the waste liquid tank 84.

When the pump 82 continues to be driven forward, the pressure in the cap member 81 becomes negative, and ink can be sucked from the nozzles 11 b of the head 11.
After sucking a certain amount of ink from the nozzle 11b, the pump 82 is stopped. Thereafter, the cap up-and-down means 104a is operated to separate the cap member 81 from the nozzle surface 11a (decap), and the pump 82 is driven to rotate forward again, whereby the ink remaining in the suction path 87 in the cap member 81 is removed. Discharge to the waste liquid tank 84.

[Cleaning liquid supply operation]
After the ink discharging operation is completed, the air release valve 84a of the waste liquid tank 84 is closed so that the ink in the waste liquid tank 84 does not dry and solidify. The switching valve 83 a is driven by the control unit 100 so as to communicate with the cleaning liquid tank 85. When the air release valve 85a provided in the cleaning liquid tank 85 is opened and the pump 82 is driven in reverse, the cleaning liquid in the cleaning liquid tank 84 is sucked up and passes through the supply path 88, the switching valve 83a, and the suction path 87. , And supplied into the cap member 81.
When the supply of the cleaning liquid is finished, the maintenance unit 80 is moved horizontally to the standby position, the head unit 1 is lowered to the recording position, and the printing operation is started.
When the printing operation is completed and the control unit 100 issues a capping command, the above-described capping operation is performed.
A path on the cap member 81 side from the switching valve 83 a in the suction path 87 is shared as a supply path 88.

In the present embodiment, in order to reduce the amount of the cleaning liquid used as much as possible, a nozzle with clogging is specified, and the ink suction operation and the cleaning liquid supply operation are performed only on the head having the nozzle.
The clogged nozzle is specified by the nozzle discharge detection means 106 (see FIG. 3).
As shown in FIG. 11, the nozzle discharge detection means 106 includes a nozzle discharge detection sensor 106a. For example, a laser light source 106a-1 that can generate a laser beam LB, and a laser light receiving element 106a-2 that receives the laser light. It is made up of. In this embodiment, the nozzle discharge detection means 106 is provided on the base plate 71 of the head unit 1, but it can also be provided on the maintenance unit 80 side.

The nozzle clogging check is performed by performing idle ejection in a state where the nozzle surface 11a and the cap member 81 are separated from each other (including the decap in FIG. 7B) before suction.
When performing idle ejection from the nozzle 106a, a laser beam is applied to the ink droplets ejected from the nozzle 11b. If there is a nozzle that has not ejected ink droplets, the laser beam does not strike the ink droplets, so that the laser beam is received by the laser receiving element 106a-2 and the level of the detection signal from the laser receiving element 106a-2 changes. By this level change, clogging of the nozzle 11b can be detected. By performing this with a plurality of heads 11, the clogged head 11 can be identified.
The target head may be specified by printing a nozzle check pattern.

The suction recovery may be performed only for the head 11 that is clogged. By opening the cap opening / closing valve 86 for only the target head, the suction recovery operation is performed only for the target head. This reduces the amount of cleaning liquid used. That is, the amount of waste liquid is also reduced.
FIG. 10 shows a control flow of the suction recovery. Although not shown in FIG. 10, after discharging to the waste liquid tank, the cleaning liquid is supplied to the cap member 81 corresponding to the head that has sucked ink as described above.

Based on FIG. 9, variable control of the supply amount of the cleaning liquid to the cap member 81 will be described.
The supply amount of the cleaning liquid is determined based on information from the temperature / humidity detection means 105 (see FIG. 3). When the atmospheric humidity around the image forming apparatus is lower than a predetermined value (threshold value) Hm, the cleaning liquid level 90 (see FIG. 8) in the cap member 81 is set to be high, and conversely when the atmospheric humidity is high. The liquid level 90 is set low.
This is because when the atmospheric humidity is low, the ink surface of the nozzle 11b is likely to dry, and there is a high possibility that normal ejection will not be achieved. By adjusting the amount of the cleaning liquid for maintaining a normal discharge state, it is possible to reduce the cleaning liquid discharged to the waste liquid tank 84 as compared with the case where the liquid is uniformly filled.

In the image forming apparatus as shown in FIG. 6, the maintenance unit 80 moves horizontally to the capping position and the standby position as described above. If the maintenance unit 80 moves while the liquid level 90 in the cap member 81 is high, the cleaning liquid in the cap member 81 may leak out due to an impact accompanying the movement.
Therefore, when the liquid level detection sensor 107a as the liquid level detection means 107 (see FIG. 3) provided in each cap member 81 is ON, the pump 82 is driven to rotate forward so that the liquid level is lowered. By discharging the cleaning liquid, the cleaning liquid in the cap 81 does not leak even in the impact of movement. The amount of cleaning liquid used can be reduced compared to when the entire amount is removed during movement.
FIG. 4 shows a flow of liquid level adjustment control.

Normally, a resin tube or the like is used for the suction path 87. At the time of suction, all the ink in the suction path 87 is sucked, so that only the ink attached to the inner wall of the tube remains. Therefore, since a small amount of ink remains in the cap member 81 and the suction path 87, the mixed liquid of the remaining ink and the cleaning liquid can be used again as the cleaning liquid.
Therefore, in the present embodiment, in the ink suction operation, the switching valve 83a is first switched to the cleaning liquid tank 85 side, and the mixed liquid of the remaining ink and the cleaning liquid in the tube is returned to the cleaning liquid tank 85, and then the switching valve 83a. Is switched to the waste liquid tank 84 side, the ink is sucked from the nozzle 11b, and the ink is discharged to the waste liquid tank 84 side. As a result, the amount of cleaning liquid can be reduced (saved).

As shown in FIG. 1, a concentration sensor 108 a serving as a waste liquid concentration detecting means 108 is provided in the cleaning liquid tank 85. The concentration of the cleaning liquid in the cleaning liquid tank 85 is detected by the concentration sensor 108a so that the cleaning liquid in the cleaning liquid tank 85 does not lose its cleaning effect. If the concentration is less than a predetermined value (threshold value) N, the switching valve 83a is set to the cleaning liquid tank 85. When the threshold value is exceeded, the switching valve 83a is switched to the waste liquid tank 84 side, and the cleaning liquid is controlled to return to the waste liquid tank 84 side. This control flow is shown in FIG.
By doing so, as long as there is a cleaning effect, the amount of the cleaning liquid can be reduced by repeatedly using the cleaning liquid. That is, the amount of waste liquid can be reduced. This effect can be obtained even when the ink suction / cleaning liquid supply is performed on all the heads as in the prior art.
The concentration sensor 108a is constituted by, for example, an optical reflection type sensor, and when the concentration of the cleaning liquid changes, the reflected signal changes, so that it can be determined whether the cleaning effect remains at that level.

In the present embodiment, the concentration sensor 108a is provided in the cleaning liquid tank 85. However, as shown in FIG. 1, the concentration sensor 108b is provided in the suction path 87, specifically on the upstream side (cap member 81 side) of the switching means 83a. You may make it provide. In FIG. 1, the density sensor 108a and the density sensor 108b are displayed simultaneously, but either one is provided.
When the concentration of the cleaning liquid is lower than the threshold value, the cleaning liquid is returned to the cleaning liquid tank 85, and when the threshold value is exceeded, the switching valve 83a is switched to the waste liquid tank 84 side and the cleaning liquid is discharged to the waste liquid tank 84 side. To do.
Compared with the configuration in which the concentration sensor 108a is provided in the cleaning liquid tank 85, the cleaning liquid having a high concentration is not returned to the cleaning liquid tank 85, and the life of the cleaning liquid can be extended. Therefore, the cleaning liquid replacement cycle can be lengthened. This effect can be obtained even when the ink suction / cleaning liquid supply is performed on all the heads as in the prior art.
In the concentration sensor 108b, the suction path 87 is formed of a transparent resin tube, and an optical reflective sensor may be used, but a transmissive optical sensor or the like may be used.

FIG. 3 is a diagram illustrating a configuration of a maintenance unit with respect to a head unit of the image forming apparatus according to the embodiment of the present invention. It is a figure which shows the modification of a maintenance unit. It is a control block diagram. It is a flowchart of control of liquid level adjustment in the case of moving a maintenance unit. It is a flowchart of control which changes a waste liquid path | route according to the value of a waste liquid density | concentration. 1 is a schematic diagram illustrating a main part of an image forming apparatus. It is process drawing which shows a capping operation | movement. It is sectional drawing of the head and cap member in a capping state. It is a flowchart of control which changes the liquid level in a cap member according to the value of humidity. 10 is a flowchart in a case where ink suction / cleaning liquid supply is performed only for a head having a non-ejection nozzle. It is a figure which shows the structure of a nozzle discharge detection means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Head unit 11 Head 11a Nozzle surface 11b Nozzle 80 Maintenance unit 81 Cap member 82 Pump as suction means and cleaning liquid supply means 83a Switching valve 84 Waste liquid tank 85 Cleaning liquid tank 86 Cap on-off valve 105 Temperature / humidity detection means 106 as humidity detection means Nozzle discharge detection means 107 Liquid level detection means 108a Means for detecting the concentration of the cleaning liquid in the cleaning liquid tank 108b Means for detecting the concentration of the liquid in the path P Paper as a recording medium

Claims (7)

A plurality of heads for discharging liquid from nozzles toward a recording medium;
A plurality of cap members provided corresponding to each of the plurality of heads, sealing the nozzle surfaces of the plurality of heads, and sucking liquid from the nozzle surfaces;
A suction means connected to each of the plurality of cap members to form a negative pressure in the cap member;
A waste liquid tank from which the liquid sucked from the plurality of cap members by the suction means is discharged;
A plurality of cap opening / closing valves provided in respective paths between each of the plurality of cap members and the suction means, for opening and closing the paths so as to selectively suck the plurality of cap members;
A cleaning liquid tank for storing a cleaning liquid supplied to each of the plurality of cap members;
Cleaning liquid supply means for supplying the cleaning liquid in the cleaning liquid tank to each of the plurality of cap members;
A switching valve disposed downstream of the cap opening / closing valve in the suction path of the suction means, connecting either the waste liquid tank or the cleaning liquid tank to the plurality of cap opening / closing valves and disconnecting the other; ,
With
When sucking the liquid from the nozzle surface , the switching valve is switched to control the cleaning liquid in the plurality of cap members to be returned to the cleaning liquid tank, and then the liquid is sucked from the nozzle surface, An image forming apparatus , wherein the switching valve is controlled to guide the liquid sucked from the nozzle surface . The image forming apparatus according to claim 1.
A nozzle discharge detecting means for detecting whether or not the liquid is discharged from the nozzle, and when there is a nozzle that has not discharged, the liquid suction operation and the cleaning liquid supply operation are performed only on the head having the nozzle; An image forming apparatus. The image forming apparatus according to claim 1 or 2,
An image forming apparatus comprising: a humidity detection unit that detects humidity; and controlling the amount of the cleaning liquid in the plurality of cap members in accordance with a detection value of the humidity detection unit. The image forming apparatus according to claim 1,
A head unit integrally having the plurality of heads;
A maintenance unit that has at least the cap member and the cap on-off valve, and maintains and recovers the performance of the head,
The head unit is movable in a direction perpendicular to the conveyance surface of the recording medium, and the maintenance unit is movable in parallel to the conveyance surface;
When a recording operation is performed, the maintenance unit moves from the capping position facing the head unit in parallel with the transport surface while being separated from the head unit, and is set to a standby position.
A liquid level detecting means for detecting a liquid level height of the cleaning liquid in the plurality of cap members;
2. The image forming apparatus according to claim 1, wherein when the liquid level exceeds a predetermined value, the maintenance unit is moved to the standby position with the liquid level lowered. The image forming apparatus according to claim 1,
Means for detecting the concentration of the cleaning liquid in the cleaning liquid tank;
When the concentration of the cleaning liquid in the cleaning liquid tank exceeds a predetermined value, the switching valve is controlled so that the cleaning liquid in the plurality of cap members is discharged to the waste liquid tank without returning to the cleaning liquid tank. An image forming apparatus. The image forming apparatus according to claim 1,
The path between the cap on-off valve and the switching valve is provided with means for detecting the concentration of the liquid in the path ,
When the concentration of the liquid in the path exceeds a predetermined value, the switching valve is controlled so that the cleaning liquid in the plurality of caps is discharged to the waste liquid tank without returning to the cleaning liquid tank. Image forming apparatus. The image forming apparatus according to claim 1,
An image forming apparatus, wherein the suction unit also serves as the cleaning liquid supply unit .

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