WO2016009941A1

WO2016009941A1 - Inkjet printer

Info

Publication number: WO2016009941A1
Application number: PCT/JP2015/069765
Authority: WO
Inventors: 松井　康祐
Original assignee: コニカミノルタ株式会社
Priority date: 2014-07-18
Filing date: 2015-07-09
Publication date: 2016-01-21
Also published as: EP3170666A4; CN106536204A; EP3170666B1; JPWO2016009941A1; JP6365669B2; EP3170666A1; CN106536204B

Abstract

Provided is an inkjet printer, which limits reduction in work efficiency without deterioration of formed image quality. The inkjet printer is equipped with: a conveyor unit for conveying a print medium (P) on a conveyor surface in the conveyance direction; an ink-discharging section for discharging ink from nozzle openings on a nozzle surface that faces the conveyor surface; a vertical motion unit for changing the distance of the ink-discharging section from the conveyor surface; a measurement section (113) for measuring the floating distance of the print medium at a measurement position at a prescribed separation distance (L1) on the upstream side of the ink-discharging section in the conveyance direction; a vertical motion control section for causing, when the floating distance reaches at least a first distance (H1) and after a prescribed period from the floating detection timing has elapsed, the vertical motion unit to perform, on the basis of the separation distance and the print medium conveyance speed, a retracting motion of moving the ink-discharging section to a position (H3) where the nozzle surface does not contact the floating portion while said floating portion is conveyed into a range that faces the ink-discharging section; and a discharge control section for continuing ink discharge until the retracting motion start timing.

Description

Inkjet recording device

This invention relates to an ink jet recording apparatus.

Conventionally, there is an ink jet recording apparatus that forms an image by ejecting ink onto a recording medium. In an ink jet recording apparatus, an image is formed on a recording medium that is relatively wide with respect to the ink ejection surface by relatively moving the ejection section that ejects ink and the recording medium.

However, if there are wrinkles or the like on the recording medium, the distance between the ink ejection surface disposed opposite to the recording medium changes depending on the location, and the ink landing position is unevenly displaced, resulting in a decrease in image quality. There is a problem of doing. Furthermore, there is a problem that the convex portion of the recording medium comes into contact with the ink ejection surface, leading to a failure of the ink jet recording apparatus.

Therefore, conventionally, in an ink jet recording apparatus that sequentially ejects ink from a discharge unit to a recording medium to be conveyed, the recording is performed on the upstream side in the conveyance direction of the storage medium from the position where the ink is landed on the recording medium. A technique for protecting a surface provided with a nozzle opening when a sensor for detecting the height of the medium from the conveying surface is provided and the recording medium is detected to have a predetermined height or more (Patent Document 1) Control that prevents the deterioration of image quality by changing the amount of ejected ink according to the height of the recording medium or reducing the conveyance speed, or preventing printing from being stopped and forming a low-quality image The technique (patent document 2) which performs is disclosed.

Further, in Patent Document 3, sensors are provided at two locations, a paper feed unit and a transport unit, on the upstream side in the transport direction of the recording medium with respect to the position where the recording medium and the nozzle opening face each other. Ink jet recording is performed by determining whether image formation or paper feeding is possible according to the height of the recorded recording medium, and by urgently stopping the conveyance of the recording medium according to the height of the recording medium detected by the sensor of the conveyance unit. A technique for increasing the throughput of image formation while preventing device failure and low-quality image formation has been disclosed.

JP 2002-36525 A JP 2008-246879 A JP 2011-126131 A

However, when a large number of images are formed on a recording medium at high speed, it may be time-consuming to restore if the conveyance is stopped every time a partial convex portion is detected or if image formation is simply stopped. However, there is a problem that the working efficiency is lowered due to an increase in the number of portions where no image is formed on the recording medium.

An object of the present invention is to provide an ink jet recording apparatus capable of suppressing a decrease in work efficiency without causing deterioration in image quality of a formed image.

In order to achieve the above object, the invention described in claim 1
A transport unit that transports the recording medium on the transport surface in a predetermined transport direction;
An ink ejection unit that ejects ink droplets from a nozzle opening provided on a nozzle surface facing the transport surface;
An elevating unit that moves the ink ejection unit to change the distance between the nozzle surface and the transport surface;
A measurement unit that measures the flying distance of the recording medium from the conveyance surface at a measurement position that is a predetermined separation distance upstream of the ink ejection unit in the conveyance direction;
When the flying distance measured by the measurement unit is equal to or greater than a predetermined first distance, the distance is equal to or greater than the first distance based on the separation distance and the conveyance speed of the recording medium by the conveyance unit. After a predetermined time elapses from the floating detection timing, the ink rises until a timing at which the floating portion of the recording medium whose flying distance is equal to or greater than the first distance is transported within a range facing the ink discharge portion. An elevating control unit for causing the elevating unit to perform a retreat operation for changing the distance between the discharge unit and the transport surface to a predetermined retreat distance in which the nozzle surface and the floating portion do not contact;
An ejection control unit that causes the ink ejection unit to continue ejecting ink droplets at least halfway from the rising detection timing to the withdrawal operation start timing for starting the withdrawal operation;
An ink jet recording apparatus comprising:

According to a second aspect of the present invention, in the ink jet recording apparatus of the first aspect,
The elevating control unit is characterized in that the retreat distance is changed according to the flying distance.

The invention according to claim 3 is the ink jet recording apparatus according to

claim

1 or 2,
After the ascent distance becomes equal to or greater than the first distance, when the ascent distance falls below a second distance that is equal to or less than the first distance, the elevating control unit is configured such that the ascent distance is equal to or greater than the second distance. A return operation for changing the distance between the nozzle surface and the transport surface to a predetermined ink discharge distance for discharging ink from the nozzle opening after the portion has passed through the range facing the ink discharge portion; Let the elevator move,
The ejection control unit restarts ejection of the ink droplets related to image formation from the nozzle opening portion of the ink ejection unit where the restoration operation has been performed after the completion of the restoration operation.

According to a fourth aspect of the present invention, in the ink jet recording apparatus according to the third aspect,
The elevating control unit is characterized in that the return operation can be executed by the elevating unit when the second distance falls below a predetermined standby time.

According to a fifth aspect of the present invention, in the ink jet recording apparatus according to the fourth aspect,
The waiting time is equal to or longer than the time required for the nozzle surface to reciprocate at a predetermined elevation speed between the retreat distance and the ink ejection distance, and the recording medium is conveyed by the separation distance. It is characterized by being less than time.

The invention according to claim 6 is the ink jet recording apparatus according to any one of claims 3 to 5,
The ejection control unit is configured to perform an ink pre-ejection operation from the nozzle opening after completion of the return operation, and then restart ink ejection related to image formation from the nozzle opening.

The invention according to claim 7 is the ink jet recording apparatus according to claim 5 or 6,
The ejection control unit is characterized in that after the return operation is completed, the image to be formed is formed from the head of the image to be formed.

The invention according to claim 8 is the ink jet recording apparatus according to any one of claims 1 to 7,
Whether the ejection control unit can form all the images formed by the ink ejection unit at the floating detection timing before the retracting operation start timing when the flying distance is equal to or greater than the first distance. If it is determined that the ink cannot be formed, the ink ejection is stopped before the retracting operation start timing.

The invention according to claim 9 is the ink jet recording apparatus according to any one of claims 1 to 8,
Whether the ejection control unit can form all the images formed by the ink ejection unit at the floating detection timing before the retracting operation start timing when the flying distance is equal to or greater than the first distance. If it is determined whether or not formation is possible, the ejection of the ink is stopped after the timing when the formation is completed and before the start timing of the retracting operation.

The invention according to claim 10 is the ink jet recording apparatus according to any one of claims 1 to 7,
The ejection control unit ejects ink related to a target image of the formation that can be completed before the retracting operation start timing when the flying distance is equal to or more than the first distance. The ink ejection is stopped after the timing when the image formation is completed and before the retreat operation start timing.

The invention according to claim 11 is the ink jet recording apparatus according to any one of claims 1 to 10,
When the flying distance is larger than the maximum value of the retreat distance, the conveyance unit includes a conveyance control unit that stops conveyance of the recording medium.

The invention according to claim 12 is the ink jet recording apparatus according to any one of claims 1 to 11,
A plurality of the ink ejection units are arranged at different positions in the transport direction,
The elevating unit is configured to independently change the distance between the nozzle surface and the transport surface of the plurality of ink ejection units,
The elevating control unit performs the same elevating operation corresponding to the distance between the plurality of ink ejection units and the floating portion, and changes the distance between the nozzle surface and the transport surface to the retreat distance. It is characterized by.

The invention according to claim 13 is the ink jet recording apparatus according to any one of claims 1 to 12,
The recording medium is a fabric, and is continuous in the transport direction for longer than the separation distance.

According to the present invention, in the ink jet recording apparatus, there is an effect that it is possible to suppress a decrease in work efficiency without causing deterioration of the image quality of the formed image.

1 is an overall perspective view of an ink jet recording apparatus according to an embodiment of the present invention. It is a block diagram which shows the function structure of an inkjet recording device. It is a side view for demonstrating the height change of a recording medium. 3 is a flowchart illustrating a control procedure of image formation control processing executed in the ink jet recording apparatus according to the first embodiment. It is a flowchart which shows the control procedure of the image formation interruption process called by an image formation control process. It is a flowchart which shows the control procedure of the image formation return process called by an image formation interruption process. 6 is a time chart illustrating an example of timing for interrupting image formation. 12 is a flowchart illustrating a first modification of the image formation interruption process. 10 is a flowchart illustrating a control procedure of an image formation return process called up in an image formation interruption process according to Modification 1; 10 is a flowchart illustrating a second modification of the image formation interruption process. It is a flowchart which shows the control procedure of the image formation interruption process called in the image formation control process performed with the inkjet recording device of 2nd Embodiment. It is a figure which shows the example of a setting of the ink discharge interruption timing in the inkjet recording device of 2nd Embodiment. It is a figure which shows the example of a setting of the ink discharge interruption timing in the inkjet recording device of 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
FIG. 1 is an overall perspective view of an ink jet recording apparatus 100 according to a first embodiment of the present invention. FIG. 2 is a block diagram illustrating a functional configuration of the inkjet recording apparatus 100.

The inkjet recording apparatus 100 includes a transport unit 11, a plurality (eight in this case) of carriages 120, and a carriage lifting unit 13 (lifting unit) provided corresponding to each of the carriages 120. Each of the carriages 120 extends in the width direction (y direction) perpendicular to the conveyance direction (x direction) by the conveyance unit 11 and is disposed and conveyed so as to face the recording medium conveyance surface by the conveyance unit 11. The inkjet head 12 is fixed so as to be able to eject ink over the entire width of the recording medium to form a line head structure. The carriages 120 arranged in these eight rows are provided at different positions in the transport direction corresponding to the eight colors of ink, respectively. Hereinafter, the first column, the second column,..., The eighth column carriage 120 are sequentially described from the upstream side in the transport direction as necessary. The carriage 120 is provided so that the distance (z direction) from the conveyance surface can be changed by the carriage lifting / lowering unit 13, and the distance from the conveyance surface of the inkjet head 12 is also changed as the carriage 120 moves.

The ink jet recording apparatus 100 includes a transport unit 11, an ink jet head 12, a carriage lift unit 13, a control unit 14 (lift control unit, discharge control unit, transport control unit), an operation display unit 15, and a functional configuration. And a communication unit 16.

The transport unit 11 includes a transport motor 111, an encoder 112, a recording medium distance sensor 113 (measurement unit), a driving roller 114, a transport belt 115, and the like. The transport motor 111 rotates the drive roller 114 at a predetermined speed. An endless conveyance belt 115 is wound around the driving roller 114 together with a driven roller (not shown), and the conveyance belt 115 is moved around by the rotation of the driving roller 114. A recording medium is placed on the conveying surface with the outer circumferential surface of the conveying belt 115 as a conveying surface, and the recording medium is conveyed in the conveying direction as the conveying belt 115 rotates.

The encoder 112 is a rotary encoder that measures the rotation angle and rotation speed of the conveyance motor 111, and the moving speed of the conveyance belt 115, that is, the conveyance speed of the recording medium is calculated from the rotation speed of the conveyance motor 111.

The recording medium distance sensor 113 is a sensor for measuring the distance (flying distance) between the recording medium and the conveyance surface. The recording medium distance sensor 113 is a predetermined distance L1 (separation distance) further upstream from the upstream end in the transport direction on the surface (nozzle surface) facing the transport surface of the first inkjet head 12 (carriage 120) on the transport path. ) Is a measurement position for measuring the distance between the recording medium and the conveyance surface. As the recording medium distance sensor 113, for example, an optical sensor is used, and the distance between the transport surface and the recording medium surface is measured by detecting the presence or absence of reflected light or light shielding of the light emitted to the recording medium. . That is, if the measured distance is equal to or greater than the thickness of the recording medium, the recording medium is lifted by wrinkles or the like.

The inkjet head 12 includes a drive circuit 121 and an ink discharge unit 122. The ink discharge unit 122 has an ink channel that connects an ink supply unit (not shown) and the opening of each nozzle that discharges ink, and pressure is applied to the ink in the ink channel with a predetermined drive pattern. Ink droplets are ejected from the nozzle openings. The nozzle opening is provided on a surface (nozzle surface) facing the transport surface of the inkjet head 12, and ink is configured to fly and land substantially perpendicularly to the recording medium (transport surface). A plurality of nozzle openings are arranged on the nozzle surface of each inkjet head 12 at a predetermined interval (pitch) in the width direction. The arrangement pattern of the nozzle openings is not particularly limited, and may be a simple one-dimensional arrangement, or a staggered arrangement having a plurality of rows in the transport direction. In each carriage 120, when a plurality of inkjet heads 12 that discharge ink of the same color are arranged to form a line head, nozzle openings provided in adjacent inkjet heads 12 partially overlap in the width direction. Therefore, it is desirable that the ink is reliably discharged over the entire width of the recording medium.

The drive circuit 121 changes the pressure state of the ink in the ink flow path of the ink discharge unit 122 and outputs a drive signal for discharging ink from the nozzle opening at an appropriate timing. Various known methods are used as a method for changing the pressure state of the ink. For example, the ink flow path is deformed and compressed by applying a voltage with an appropriate waveform to a piezoelectric body provided along the ink flow path. The ink may be pressurized by energizing an electric heating element (resistive element) to heat the wall surface of the ink flow path and generating bubbles.
The drive circuit 121 is formed together with the ink discharge unit 122 in the inkjet head 12, but may be appropriately arranged.

The carriage elevating unit 13 includes a motor driver 131, an elevating motor 132, an electromagnetic brake 133, a beam member 134, and a support unit 135, and is fixed by changing the distance from the conveyance surface of the carriage 120. Two beam members 134 are provided approximately in parallel across the conveying direction at the upper part of the conveying belt 115 (on the conveying surface side of the recording medium), and two support portions 135 are fixed to both ends of the beam member 134, respectively. . The elevating motor 132, the electromagnetic brake 133, and the carriage 120 are attached to the support unit 135, and the motor driver 131 drives the elevating motor 132 and the electromagnetic brake 133 based on a control signal from the control unit 14, whereby the position of the carriage 120 is reached. Determine.

The elevating motor 132 moves the carriage 120 at a predetermined elevating speed according to a drive signal from the motor driver 131. As the lifting motor 132, for example, a servo motor or a stepping motor is used. By this lift motor 132, the nozzle surface of the inkjet head 12 fixed to the carriage 120 can be lifted and lowered within the range of the lift width H0 from the ink discharge distance Hn to the maximum retreat distance H3. .

The electromagnetic brake 133 releases the fixed state of the carriage 120 when an operation signal is received from the motor driver 131 and enables the carriage 120 to move by the lifting motor 132. That is, the electromagnetic brake 133 fixes the carriage 120 in a normal state including when the power is turned off. As the electromagnetic brake 133, for example, a disc brake is used.

The control unit 14 controls the overall operation of the ink jet recording apparatus 100 and operates each unit appropriately. The control unit 14 includes a memory 141, a CPU 142 (Central Processing Unit), a ROM 143 (Read Only Memory), a RAM 144 (Random Access Memory), a bus 145, and the like.

The memory 141 temporarily stores image data input from the outside via the communication unit 16. When the image data is processed for image formation by the inkjet recording apparatus 100, the processed image data is stored in the memory 141.

The CPU 142 performs various arithmetic processes related to operation control of the inkjet recording apparatus 100. In accordance with the program read from the ROM 143, the CPU 142 performs each process related to image formation based on image data, status signals of each unit, clock signals, and the like. The CPU 142 may centrally control all the operations of the ink jet recording apparatus 100 by one CPU, or a CPU for operation control and a dedicated CPU for other processing such as image data processing may be separately provided. You may hold and operate.

The ROM 143 stores a control program related to image formation and initial setting data. As the ROM 143, a mask ROM may be used, or a rewritable nonvolatile memory such as a flash memory may be used. The program and setting data in the ROM 143 are read by the CPU 142 as appropriate and executed and used.

The RAM 144 provides a working memory space to the CPU 142 and stores temporary data. The temporary data includes the position of the carriage 120 related to the operation of the lift motor 132, distance data related to the measurement operation of the recording medium distance sensor 113, and the like.

These memory 141, CPU 142, ROM 143, and RAM 144 are connected to each other via a bus 145 so that data can be exchanged. In addition, the transport unit 11, the inkjet head 12, the carriage lifting / lowering unit 13, the operation display unit 15, and the communication unit 16 are connected to the bus 145 from the outside of the control unit 14, and control signals and data are exchanged.

The operation display unit 15 receives an external input such as a user operation and outputs it as an input signal, and displays various statuses and operation menus of the ink jet recording apparatus 100 in accordance with a control signal from the CPU 142. The operation display unit 15 includes, for example, push button switches and operation keys as operation input means, a display screen such as an LCD (Liquid Crystal Display) as a display means, and a light emitting unit used as a display driver and an indicator thereof. Prepare. Further, a touch sensor can be provided on the display screen, and the display screen can be used as a touch panel.

The communication unit 16 is an interface for communication operation that receives commands and settings related to image data and print jobs from the outside, and transmits status signals related to image formation. The communication unit 16 is, for example, a NIC (Network Interface Card), and includes drivers based on various communication standards.

Next, an image forming operation in the inkjet recording apparatus 100 of the present embodiment will be described.
FIG. 3 is a side view for explaining the positional relationship among the recording medium P, the recording medium distance sensor 113, and the carriage 120 in the inkjet recording apparatus 100. FIG.

In the ink jet recording apparatus 100 of the present embodiment, a recording medium, particularly a fabric, that is continuous in the transport direction for longer than the distance L1 is used. Here, images based on image data arranged in the same or a predetermined pattern / order are sequentially formed on the recording medium at intervals (margins) appropriately set according to the conveyance of the fabric.

At the time of ink discharge related to image formation, the carriage 120 is fixed at a position (ink discharge position) where the distance between the nozzle surface and the transport surface is a predetermined ink discharge distance Hn.
When the recording medium P has wrinkles or the like and the recording medium P has a portion (floating portion) that is lifted from the conveyance surface, the gap between the nozzle surface and the surface of the recording medium P becomes narrow in the floating portion, and the ink The landing position deviates from a desired position by shortening the flight distance. Further, when the surface of the recording medium P is inclined or bent with respect to the nozzle surface, the ink landing position on the portion is narrowed in the transport direction, or an image is not formed. Further, the recording medium P contacts (collises) with the nozzle surface (inkjet head 12 or carriage 120). Therefore, the inkjet recording apparatus 100 stops image formation when the recording medium P detects a lift amount that is equal to or greater than the reference lift amount H1 (first distance) that is assumed to cause image degradation that exceeds a predetermined reference. The carriage lifting / lowering unit 13 is operated to move the position of the carriage 120 away from the conveyance surface and perform a retraction operation with the distance from the conveyance surface as a predetermined retraction distance. In addition, when the lifting of the carriage 120 over the maximum retraction distance H3 is detected, the conveyance of the recording medium by the conveyance unit 11 is urgently stopped.

Here, when the carriage 120 moves in the elevation width H0 at the elevation speed Va, the nozzle surface is retracted at the elevation time Ta = H0 / Va. On the other hand, after the floating of the recording medium P is detected by the recording medium distance sensor 113, the floating portion is in a range facing the carriage 120 (nozzle surface) (that is, a range having a length Lh in the transport direction below the carriage 120). The arrival time Tt indicating the time difference until the arrival depends on the conveyance speed Vt of the recording medium P by the conveyance unit 11, and Tt = L1 / Vt> Ta. Furthermore, when the conveyance speed Vt can be changed depending on the image forming mode or the like, the difference between the arrival time Tt and the elevation time Ta changes depending on the image forming mode.

Therefore, in the ink jet recording apparatus 100, after a predetermined margin time Tm is set and the reference lift amount H1 is detected by the recording medium distance sensor 113, the floating portion of the recording medium P is related to the carriage 120 in the first row. With respect to the timing at which the ink jet head 12 starts to face the nozzle surface, the discharge operation start timing is the sum of the up / down time Ta and the margin time Tm, and ink ejection related to image formation is stopped and the carriage 120 starts to be retracted. To do. That is, if the transport distance La when the recording medium P is transported during the lift time Ta = Vt × Ta and the margin Lm = Vt × Tm when the recording medium P is transported during the margin time Tm, then this floating portion After passing through the measurement position by the recording medium distance sensor 113, the carriage 120 starts to be retracted after a further distance (L1-La-Lm). Thus, after the floating portion is detected, the ink for image formation can be continuously discharged during the time (L1 / Vt−Ta−Tm) (remaining discharge time) and the distance (L1−La−Lm), and The carriage 120 has been completely retracted immediately before the floating portion of the recording medium P reaches the position of the carriage 120.

Further, in the carriages 120 in the Nth and subsequent rows (N ≧ 2), when the distance L2 is defined between the carriages 120 adjacent to each other in the transport direction, the flying portion of the recording medium P passes through the measurement position by the recording medium distance sensor 113. Further, after the distance (L1 + (N−1) × L2−Vt (Ta + Tm)) has been moved, the ink discharge is stopped and the carriage is retracted. Accordingly, for the portion of the recording medium P on which the ink related to image formation is ejected from the inkjet head 12 fixed to the carriage 120 in the first row, the recording medium P having a reference lift amount H1 or more by the recording medium distance sensor 113. Even after the lifting of the ink is detected, ink is ejected from the inkjet heads 12 associated with all the carriages 120 to form an image.

FIG. 4 is a flowchart showing a control procedure by the CPU 142 of the image formation control process executed in the inkjet recording apparatus 100 of the present embodiment.

In this image formation control process, for example, when the CPU 142 receives a print job via the communication unit 16 or an image formation command related to image data stored in the memory 141 is input from the operation display unit 15. Is started when the CPU 142 detects.

When the image formation control process is started, the CPU 142 outputs a control signal to the motor driver 131 as necessary, moves the carriage 120, and determines the distance between the nozzle surface and the transport medium P as the ink discharge distance during image formation. Set to Hn (step S101). When the movement of the carriage 120 is completed, the CPU 142 outputs a control signal to the drive circuit 121, outputs image data from the memory 141 at an appropriate timing, and starts image formation by ejecting ink from each nozzle. (Step S102).

The CPU 142 determines whether or not the image formation has been normally completed (step S103). If it is determined that the process has been completed normally (“YES” in step S103), the CPU 142 ends the image formation control process. If it is determined that the image formation has not been completed normally, that is, the image formation has not been completed (“NO” in step S103), the CPU 142 obtains the measurement value of the recording medium distance sensor 113, and the recording medium It is determined whether or not the lifting amount of the recording medium P at the measurement position by the distance sensor 113 is greater than or equal to the maximum retreat distance H3 (step S104).

If it is determined that the lift amount is equal to or greater than the maximum retreat distance H3 (“YES” in step S104), the CPU 142 outputs a control signal to the drive circuit 121 to stop the ink discharge and the transport motor 111. A signal is output to stop the conveyance before the floating portion reaches the range facing the carriage 120 in the first row (step S105). The CPU 142 displays an error end display on the operation display unit 15 (step S106), and ends the image formation control process.

If it is determined in step S104 that the lift amount is not equal to or greater than the maximum retreat distance H3 ("NO" in step S104), the CPU 142 calls and executes an image formation interruption process (step S120). When the image formation interruption process ends, the CPU 142 returns the process to step S103.

FIG. 5 is a flowchart showing a control procedure by the CPU 142 of the image formation interruption process called in the image formation control process.

When the image formation interruption process is called, the CPU 142 determines whether or not the lift amount of the recording medium P acquired in the process of step S104 is greater than or equal to the reference lift amount H1 (step S121). When it is determined that the amount is equal to or greater than the reference lifting amount H1 (“YES” in step S121), the CPU 142 determines whether or not the retraction flag of the carriage 120 is set (step S122). The retraction flag indicates that the retraction operation of the carriage 120 related to the lift is performed after the reference lift amount H1 is detected and the retraction operation is performed, and the nozzle surface of the ink jet head 12 related to the retracted carriage 120 is further moved. This is a flag that is set until returning to the position of the ink discharge distance Hn from the transport surface until ink discharge related to image formation is restarted, and is released in other cases. Here, the save flag is stored in the RAM 144.

If it is determined that the evacuation flag is not set (“NO” in step S122), the CPU 142 sets the evacuation flag (step S123), and the timing when the levitation exceeding the reference levitation amount H1 is detected (levitation) Measurement of elapsed time t1 from (detection timing) is started (step S124). Further, the CPU 142 acquires the rotation speed of the transport motor 111 from the encoder 112, and acquires the transport speed Vt by the transport unit 11 (step S125).

The CPU 142 determines whether or not the elapsed time t1 has become the retraction operation start timing of each carriage 120 (step S126). Specifically, the CPU 142 determines whether or not a carriage number N that satisfies the following conditional expression (1) (a number indicating the carriage 120 in the Nth column, where 1 ≦ N ≦ 8) newly exists. Is determined.
t1 ≧ (L1 + (N−1) L2) / Vt− (Ta + Tm) (1)
Here, the timing at which this determination processing is performed must be greatly delayed from the original retracting operation start timing, and the floating portion must not reach the range facing the carriage 120 before the retracting of the carriage 120 is completed. Therefore, the margin time Tm needs to be larger than the time interval Δt1 at which the determination process in step S126 is performed.

When it is newly determined that it is the timing for starting the retracting operation of the carriage 120 with the carriage number N (“YES” in step S126), the CPU 142 outputs a control signal to the drive circuit 121 to output the carriage number N. Ink ejection from the inkjet head 12 fixed to the carriage 120 is stopped, and a control signal is output to the motor driver 131 to operate the lifting motor 132 and the electromagnetic brake 133 related to the Nth carriage 120. The carriage 120 is moved at the ascending / descending speed Va to a position where the distance from the conveyance surface is the maximum retreat distance H3 (retreat position) (step S127). At this time, the margin time Tm may be set at a predetermined ratio before, after, or before and after the ascending / descending time Ta. However, as described above, the margin time Tm may be set before the carriage 120 is retracted due to a delay in the control operation timing. It is determined so that the floating portion does not reach the range facing the carriage 120. The CPU 142 determines whether or not the carriage 120 that has newly reached the retraction operation start timing is the carriage 120 in the eighth row (step S128). If it is determined that it is not in the eighth column (“NO” in step S128), the CPU 142 ends the image formation interruption process and returns the process to the image formation control process. If it is determined that the data is in the eighth column (“YES” in step S128), the CPU 142 ends counting the elapsed time t1 (step S129). Then, the CPU 142 ends the image formation interruption process and returns the process to the image formation control process.

If it is determined in the determination process in step S126 that there is no carriage 120 that has newly reached the retracting operation start timing (“NO” in step S126), the CPU 142 ends the image formation interruption process, and the process is performed as an image. Return to the formation control process.

When it is determined in the determination process in step S122 that the save flag is set (“YES” in step S122), the CPU 142 determines whether or not the elapsed time t2 is being counted (step S131). ). As will be described later, the elapsed time t2 determines the timing at which the carriage 120 is returned to a position where the distance between the nozzle surface of the retracted carriage 120 and the transport surface becomes the ink discharge distance Hn and the ink discharge is resumed. Is the time used for If it is determined that the elapsed time t2 is not being counted (“NO” in step S131), the CPU 142 determines whether or not the elapsed time t1 is being counted (step S132).

If it is determined that the elapsed time t1 is not being counted (“NO” in step S132), the CPU 142 ends the image formation interruption process and returns the process to the image formation control process. If it is determined that the elapsed time t1 is being counted (“YES” in step S132), the CPU 142 shifts the process to step S126.

If it is determined in the determination process in step S131 that the elapsed time t2 is being counted (“YES” in step S131), the CPU 142 determines whether or not the elapsed time t2 is equal to or longer than a predetermined standby time (2Ta + Tp). Is determined (step S133). This condition is determined in a later-described image formation return process whether the return operation for moving the carriage 120 from the retracted position to the ink discharge position has already been started, the startable condition for the return operation is satisfied, or none. To do. When it is determined that the elapsed time t2 is equal to or longer than the standby time (2Ta + Tp) (“YES” in step S133), the CPU 142 calls and executes an image formation return process (step S135). Thereafter, the CPU 142 shifts the process to step S136.

When it is determined that the elapsed time t2 is not equal to or longer than the standby time (2Ta + Tp) (“NO” in step S133), the CPU 142 stops counting the elapsed time t2 and performs the return operation of the carriage 120 before the start. (Step S134). Thereafter, the CPU 142 shifts the process to step S136.

When the process proceeds to step S136, the CPU 142 determines whether or not the elapsed time t1 is being counted (step S136). If it is determined that the elapsed time t1 is being counted (step S136, “ YES "), the process proceeds to step S126. If it is determined that the elapsed time t1 is not being counted (“NO” in step S136), the CPU 142 shifts the process to step S124.

If it is determined in step S121 that the lifting amount of the recording medium P is not greater than or equal to the reference lifting amount H1 (“NO” in step S121), the CPU 142 calls and executes an image formation return process (step S121). Step S140). When the image formation return process ends, the CPU 142 determines whether or not the elapsed time t1 is being counted (step S137). If it is determined that the elapsed time t1 is not being counted (“NO” in step S137), the CPU 142 ends the image formation interruption process and returns the process to the image formation control process.

If it is determined that the elapsed time t1 is being counted (“YES” in step S137), the process of the CPU 142 proceeds to step S126.

FIG. 6 is a flowchart showing a control procedure by the CPU 142 of the image formation return process called in the image formation interruption process.

When the image formation return process is called in the process of step S135 or step S140, the CPU 142 determines whether or not the save flag is set (step S141). If it is determined that the retraction flag is not set (“NO” in step S141), image formation is normally performed by all the inkjet heads 12, and the CPU 142 ends the image formation return processing. The process returns to the image formation interruption process.

If it is determined that the evacuation flag is set (“YES” in step S141), the CPU 142 determines whether a lift above the return lift H2 (second distance) smaller than the reference lift H1 is detected. Is determined (step S142). Here, the detection of the lift of the return lift amount H2 or more includes the case where the lift of the reference lift amount H1 or more is detected in step S121 and the image formation return process is called in step S135.

If it is determined that the lift of the return lift amount H2 or more is not detected (“NO” in step S142), the CPU 142 determines whether or not the elapsed time t2 is being counted (step S143). If it is determined that the elapsed time t2 is being counted (“YES” in step S143), the CPU 142 shifts the process to step S148. If it is determined that the elapsed time t2 is not being counted (“NO” in step S143), the CPU 142 starts counting the elapsed time t2 (step S144), and then shifts the processing to step S148.

If it is determined in the determination process in step S142 that a lift amount equal to or greater than the return lift amount H2 is detected (“YES” in step S142), the CPU 142 determines whether or not the elapsed time t2 is being counted. (Step S145). If it is determined that the elapsed time t2 is not being counted (“NO” in step S145), the CPU 142 ends the image formation return process because the process related to the return operation of the carriage 120 is not currently performed. Then, the process returns to the image formation interruption process.

When it is determined that the elapsed time t2 is being counted (“YES” in step S145), the CPU 142 determines whether or not the elapsed time t2 is equal to or longer than the standby time (2Ta + Tp) (step S146). That is, the CPU 142 operates the carriage elevating unit 13 to change the distance between the transport surface and the nozzle surface from the maximum retreat distance H3 to the ink discharge distance Hn and then return to the maximum retreat distance H3 again. It is determined whether or not the total time of 2Ta and the time that can be maintained at the ink ejection position, that is, the predetermined recording time Tp that can eject ink has elapsed.

If it is determined that the elapsed time t2 is equal to or longer than the standby time (2Ta + Tp) (“YES” in step S146), the process of the CPU 142 proceeds to step S148. If it is determined that the elapsed time t2 is not equal to or greater than the standby time (2Ta + Tp) (“NO” in step S146), the carriage 120 is moved again without the time for ejecting ink at the ink ejection position for a time sufficient for image formation. Since it may be necessary to return to the retracted position from the transport surface or it may be necessary to return, the CPU 142 stops counting the elapsed time t2 (step S147), ends the image formation return processing, and performs the image formation interruption processing. Return to. In other words, the determination condition in step S146 is a requirement that the carriage 120 can start the return operation.

When one of the processes in steps S143, S144, and S146 is shifted to the process in step S148, the CPU 142 newly moves any one of the carriages 120 whose elapsed time t2 is N rows to the ink ejection position (return operation). It is determined whether or not (start timing) has been reached (step S148).
In the ink jet recording apparatus 100 of the present embodiment, when the portion of the recording medium P in which the lift amount of the recording medium P is less than the return lift amount H2 satisfies the above-described requirements for starting the return operation, the recording medium P The return operation of the carriage 120 is started at a timing when the portion passes through the range facing the inkjet head 12 (out of the range facing the inkjet head 12).
That is, the conditional expression is expressed by the following expression (2).
t2 ≧ (L1 + (N−1) L2 + Lh) / Vt (2)

At this time, the elapsed time t2 ≧ (L1 + Lh) / Vt satisfying the expression (2) for the carriage 120 in the first row is equal to or longer than the standby time (2Ta + Tp) compared in step S146 described above. By disposing the distance sensor 113, the return operation is started without delay at the timing when the portion of the recording medium P where the lifting amount of the recording medium P is less than the returning lifting amount H2 passes through the range facing the inkjet head 12. I can do it.

When it is determined that none of the carriages 120 in the N columns has newly reached the return operation start timing (“NO” in step S148), the CPU 142 ends the image formation interruption process, and performs the process for the image. Return to the formation control process. If it is determined that any of the carriages 120 has newly reached the return operation start timing (“YES” in step S148), the CPU 142 sends a control signal to the motor driver 131 to turn the lifting motor 132 and the electromagnetic brake 133 on. The operation is started to change the distance between the nozzle surface of the N-th carriage 120 and the transport surface from the maximum retreat distance H3 to the ink discharge distance Hn (step S149).

The CPU 142 further determines whether or not the operation for returning any one of the N rows of carriages 120 to the ink ejection position has come to a new end timing (return operation end timing) (step S150). Specifically, the CPU 142 determines whether or not the total time of the ascending / descending time Ta and the margin time Tm has further elapsed from the timing represented by the expression (2). If it is determined that the return operation end timing for any of the carriages 120 is not reached (“NO” in step S150), the CPU 142 ends the image formation interruption process and returns the process to the image formation control process. . When it is determined that the return operation end timing for any of the carriages 120 is reached (“YES” in step S150), the CPU 142 drives all the inkjet heads 12 fixed to the carriage 120 in the Nth column. A control signal is output to 121, and a discharge operation (pre-discharge operation) for discharging ink from all nozzle openings is performed. Then, at a timing when a predetermined time elapses thereafter, the CPU 142 restarts the ink ejection operation for image formation from the N-th row of nozzles on the recording medium P (step S151). Here, the ink ejection operation is controlled to be output from the head of the image data regardless of the position of the image data output when the ink ejection is stopped.

The CPU 142 determines whether or not the carriage number N of the carriage 120 to which the inkjet head 12 that has resumed ink ejection related to image formation is fixed is 8 (step S152). If it is determined that the carriage number N is not 8 (“NO” in step S152), the CPU 142 ends the image formation interruption process and returns the process to the image formation control process. If it is determined that the carriage number N is 8 (“YES” in step S152), the return operation for all the carriages 120 is completed, and the CPU 142 ends counting the elapsed time t2, Further, the save flag is released (step S153). Then, the CPU 142 ends the image formation interruption process and returns the process to the image formation control process.

FIG. 7 is a time chart showing an example of timing for interrupting image formation.
Here, the detection result of the recording medium distance sensor 113 shows the change in the status of the carriage 120 (inkjet head 12) in the 1st to 4th and 8th rows, the set status of the retreat flag, and the count status of the elapsed times t1 and t2. 2 is a schematic diagram showing a lift position of the recording medium with a solid line with respect to a position in the transport direction (x direction) with reference position “0”.

At timing u1, initially, in a situation where the recording medium distance sensor 113 has not detected lift above the reference lift amount H1, ink is ejected from the inkjet heads 12 of all the carriages 120 ("NO" in step S121). “NO” in step S141).

When the lift of the reference lift amount H1 or more is detected at the timing u2, the retreat flag is set, and the counting of the elapsed time t1 is started. Further, the transport distance La during lift is calculated from the transport speed Vt and the lift time Ta of the carriage 120 (“YES” in step S121, “NO” in step S122, steps S123 to S125).

When the lifted portion of the recording medium P reaches the retracting operation start position corresponding to the retracting operation start timing for the first row (N = 1) carriage 120 (timing u3), the retracting operation of the first row carriage 120 is started. ("YES" in step S121, "YES" in step S122, "NO" in step S131, "YES" in step S132, "YES" for N = 1 in step S126, step S127).

When the raised portion of the recording medium P reaches the range facing the carriage 120 with N = 1 (timing u4), the retracting operation of the carriage 120 in the first row has already been completed, and the ink ejection is stopped and the standby state is maintained. It has become. Further, the retraction operation of the carriage 120 in the second row is newly started (“NO” in step S121, “YES” in step S137, “YES” for N = 2 in step S126)). At this time, the recording medium distance sensor 113 detects a distance less than the return lift amount H2, and the elapsed time t2 is counted in the image formation return processing called in step S140 (in step S141). “YES”, “NO” in step S142, “NO” in step S143, step S144).

The elapsed time t2 is the standby time (2Ta + Tp), that is, the recording distance Lp = Tp × Vt in which the recording medium P moves at the conveyance speed Vt during the recording time Tp, while it does not continue for the time corresponding to the distance (2La + Lp). When the lift of the return lift amount H2 or more is detected again on the recording medium P (timing u5), the count of the elapsed time t2 is stopped in the image formation return process called in the process of step S140 (step S140). “YES” in S141, “YES” in Step S142, “YES” in Step S145, “NO” in Step S146, Step S147).
Here, when the lift amount detected again is equal to or larger than the reference lift amount H1, counting of the elapsed time t2 is stopped in the process of step S134 based on the determination process of steps S131 and S133.

When the lift amount of the recording medium P becomes less than the return lift amount H2 again (timing u6), the counting of the elapsed time t2 starts again from the beginning (t2 = 0) (“NO” in steps S142 and S143, step S144). ).

When the flying portion of the reference lifting amount H1 or more passes through the range facing the carriage 120 in the first row (timing u7), the elapsed time t2 is not counted with reference to the tail end of the flying portion. The carriage 120 in the row does not move to the ink ejection position yet and waits (“YES” in step S141, “NO” in step S142, “YES” in step S143, “NO” in step S148)).

After that, when a floating portion that is equal to or greater than the return lift amount H2 passes through a range facing the carriage 120 in the first row (timing u8), the ink ejection position of the carriage 120 in the first row is reached based on the elapsed time t2. Movement (return operation) is started (“YES” in step S148, step S149).

When the lifting / lowering time Ta elapses after the start of the return operation and the carriage 120 in the first row moves to the ink discharge position (timing u9), the ink discharge related to image formation is performed after the ink discharge operation is performed. The data is resumed from the beginning (“YES” in step S150, step S151).

At this time, the carriage 120 in the eighth row provided on the most downstream side in the transport direction has not yet entered the retreating operation with respect to the floating portion of the reference lift amount H1 or more, and ink is being ejected (step) In S126, “NO” for N = 8). During this time, the save flag continues to be set, and the elapsed time t1 continues to be counted.
In this situation, if a lift of the reference lift amount H1 or more is detected again on the recording medium P, the elapsed time t1 related to the previous lift and the elapsed time t1 related to the current lift in the image formation interruption process. The processes for each are executed in parallel. If the new lift is detected, the process branches to “YES” in the determination process in step S133, and the image restoration process is called in step S135. The lift determines the measurement position of the recording medium distance sensor 113. After the deviation, the image formation return process is called in step S140, and the elapsed time t2 related to the previous lifting is maintained as it is (“YES” in step S146), and the previous elapsed time t2 and the current time Processing for each of the elapsed time t2 related to the floating is executed in parallel.

Then, when the retraction operation start timing, which is the timing at which the floating portion of the reference lift amount H1 or more reaches the retraction operation start position of the eighth row carriage 120 (timing u10), the retraction operation of the eighth row carriage 120 is started. Is done. Thus, the retraction operation of all the carriages 120 is started, and the counting of the elapsed time t1 is finished (“YES” for N = 8 in step S126, “YES” in steps S127 and S128, Step S129).
Here, after the counting of the elapsed time t1 is completed, when the lifting of the reference lifting amount H1 or more is detected again before the return operation of all the carriages 120 is completed (before the retraction flag is released), Counting of the elapsed time t1 is newly started while the save flag is set (“YES” in steps S121, S122, S131, and S133, “NO” in step S136, and step S124).

Further, when the floating portion of the return lift amount H2 passes through the range facing the carriage 120 in the eighth row (timing u11), the return operation of the carriage 120 with N = 8 is started. When the return operation of the N = 8 carriage 120 is completed (timing u12), ink ejection is resumed on the carriage 120 in the eighth row, and the counting of the elapsed time t2 is completed and the save flag is set. Release ("YES" in step S152, step S153).

As described above, the ink jet recording apparatus 100 according to the present embodiment is provided on the transport unit 11 that transports the recording medium P on the transport surface in the predetermined transport direction (x direction) and the nozzle surface that faces the transport surface. An ink discharge unit 122 that discharges ink droplets from the nozzle opening, and an ink discharge unit 122 at a predetermined ascending / descending speed Va, that is, a nozzle surface provided with at least a nozzle opening from which ink is discharged from the inkjet head 12 is provided. The lifting / lowering unit 13 that changes the distance between the nozzle surface and the transport surface by moving the head chip portion including the head surface, and the distance from the transport surface at the measurement position that is a predetermined distance L1 upstream of the ink discharge unit 122 in the transport direction. The recording medium distance sensor 113 that measures the amount of lift of the recording medium P, and the amount of lift measured by the recording medium distance sensor 113 is the reference lift. When the amount is equal to or greater than the amount H1, based on the distance L1, the transport speed Vt of the recording medium P by the transport unit 11, and the elevation speed Va, the timing at which the lift amount becomes equal to or greater than the reference lift amount H1 (elapsed time t1). = 0), after a predetermined time has elapsed, the timing at which the floating portion of the recording medium P whose lift amount is equal to or greater than the reference lift amount H1 is transported within the range facing the ink discharge portion 122 (elapsed time t1 = reached) Until the time Tt), the lifting / lowering unit 13 is caused to perform a retreat operation for changing the distance between the ink discharge unit 122 and the transport surface to the maximum retreat distance H3 so that the nozzle surface does not come into contact with the floating portion. The CPU 142 as the lifting control unit and the ink at least halfway from the timing of the elapsed time t1 = 0 to the retracting operation start timing for starting the retracting operation. Provided on the outlet portion 122 and the CPU142 of the ejection control unit to continue the ejection of droplets, the.
Therefore, when the image quality of the formed image can be deteriorated, the interruption period can be shortened as compared with the conventional one while the image formation is interrupted, so that a reduction in work efficiency can be suppressed.
In addition, since the image formation continues for a while after the floating portion is detected, the possibility of completing the formation of the image currently being formed increases. It can be used more effectively to increase the throughput.

Further, when the lift amount of the recording medium P becomes equal to or greater than the reference lift amount H1, and the lift amount falls below the return lift amount H2 smaller than the reference lift amount H1, the CPU 41 determines that the lift amount is equal to or greater than the return lift amount H2. The distance between the nozzle surface and the transport surface after the portion that has passed through the range (length Vh) facing the ink discharge portion 122 is an ink discharge distance Vn that is set when ink is discharged from the nozzle opening. The CPU 122 causes the elevating unit 13 to perform a return operation that changes so that, after the return operation is completed, the CPU 122 discharges ink droplets related to image formation from the nozzle opening portion of the ink discharge unit 122 for which the return operation has been performed. To resume.
Therefore, the ink ejection operation can be promptly restarted based on the information related to the end position of the wrinkles that can be acquired in advance. Further, the determination accuracy is improved by setting the return lift amount H2 as a reference when resuming ink discharge to be lower than the reference lift amount H1, and it is now possible to form an image on the recording medium P with high accuracy. The ink ejection operation can be resumed.

In addition, the CPU 142 enables the return operation to be executed particularly when the return lift amount H2 falls below the predetermined standby time (2Ta + Tp), so that the ink can be discharged even though the return operation is started. It is possible to avoid waste such as retreating again. In addition, since it is possible to evacuate the recording medium P in a continuous manner and to evacuate the ink ejection unit 122 intermittently, the operation can be made more efficient.

Further, in particular, when the return operation is started by setting the distance between the transport surface and the nozzle surface to be longer than the time required for the reciprocating operation between the retreat distance and the ink ejection distance, At least some ink ejection can be performed on the recording medium P. Further, by setting the standby time to be equal to or shorter than the time during which the recording medium P is transported the distance L1, the flying part passes through the position facing the nozzle surface, and the next flying part is not detected. By not returning to the ink ejection position, it is possible to prevent the recording medium and time from being wasted.

In addition, after the return operation is completed, the CPU 142 performs an ink discharge operation from the nozzle opening, and then restarts the image formation of the image to be formed, so that after the irregular image formation is interrupted, the ink is discharged. When resuming the discharge of the ink, it is possible to promptly and efficiently form an image without causing an ink discharge failure from each nozzle opening.

Also, since the CPU 142 forms the image to be formed from the top of the image to be formed after the return operation is completed, it is possible to prevent the formation of a half-finished image that cannot be used at the beginning of ink ejection restart.

Further, when the lifting amount of the recording medium P is larger than the maximum retreat distance H3, the CPU 142 promptly stops the conveyance of the recording medium P by the conveyance unit 11, thereby making contact with the nozzle surface and the inkjet head 12. In order to avoid the collision, it is possible to perform the minimum necessary stop operation.

In addition, a plurality of carriages 120 to which the inkjet heads 12 including the ink discharge units 122 are fixed are arranged at different positions in the transport direction, and the lifting unit 13 includes the nozzle surfaces and the transport surfaces of the ink discharge units 122 related to the plurality of carriages 120. The CPU 142 causes the nozzle surface and the transport surface to move in the same manner, by performing the same lifting and lowering operation according to the relative distance between the plurality of ink ejection units 122 and the floating portion of the recording medium P. The distance is changed to the maximum evacuation distance H3 at an appropriate timing. That is, even when a plurality of carriages 120 are provided at different positions in the transport direction at the time of outputting a color image, the ink ejection related to image formation from the ink ejection unit 122 associated with each carriage 120 is different from each other. Since only the detected portion is interrupted, the image formation is stopped only in a much shorter range than when all image formation is stopped at the same time when wrinkles are detected, and the waste of the recording medium P is greatly suppressed. I can do it.

In addition, when a fabric is used as the recording medium P, and particularly when an image is repeatedly formed on a recording medium P that is continuous longer than the distance L1, the inkjet recording apparatus 1 is operating normally. However, it is possible to efficiently form an image while minimizing the influence of fabric wrinkles that cannot be avoided to some extent.

[Modification 1]
FIG. 8 is a flowchart showing a first modification of the image formation interruption process shown in the first embodiment. FIG. 9 is a flowchart showing the control procedure of the image formation return process called in the image formation interruption process of the first modification.

In the image formation interruption process and the image formation return process of the first modification, control is performed based on the conveyance distance by the conveyance unit 11 instead of the determination at the elapsed times t1 and t2.
In the image formation interruption process, the processes in steps S124 to S126, S129, S131 to S136, and S140 are respectively replaced with steps S124a to S126a, S129a, S131a to S136a, and S140a. In the image formation restoration process, steps S143 to S148, The processes of S150 and S153 are replaced with steps S143a to S148a, S150a, and S153a, respectively. The other processes are the same as the processes of the image formation interruption process and the image formation return process of the first embodiment, and the same reference numerals are given and detailed descriptions thereof are omitted.

In the image formation interruption process of FIG. 8, when the save flag is set in the process of step S123, the CPU 142 acquires the rotation speed and / or rotation position of the transport motor 111 from the encoder 112, and the recording medium P from this point in time. The process of measuring the transport amount is started (step S124a). Further, the CPU 142 acquires the transport speed Vt, and calculates the transport distance La during lifting within the lift time Ta based on the transport speed Vt and the lift time Ta of the carriage 120 by the lift motor 132 (step S125a). ).

The CPU 142 newly sets the transport distance Lt1 from when the lift of the reference lift amount H1 or more is detected to a position where the carriage 120 in the Nth row is newly retracted from the measurement position of the recording medium distance sensor 113 in any of the carriages 120. It is discriminated whether or not the distance has been exceeded (step S126a). This condition is expressed by the following equation (3).
Lt1 ≧ (L1 + (N−1) L2) −La−Lm (3)
Here, the margin Lm is a distance transported at the transport speed Vt within the margin time Tm, but a fixed value may be set regardless of the transport speed Vt.

When it is determined that the carriage newly determined to have reached the retreat operation start position in the determination process in step S126a is in the eighth row (step S128), the CPU 142 ends the measurement of the conveyance distance Lt1 ( Step S129a).

In addition to these, in each process of steps S132a, S136a, and S137a, the CPU 142 determines whether or not the conveyance distance Lt1 is being measured. In the process of step S131a, the CPU 142 determines whether or not the conveyance distance Lt2 at the conveyance speed Vt at the elapsed time t2 is being measured.

If it is determined in step S131a that the conveyance distance Lt2 is being measured (“YES” in step S131a), the CPU 142 determines whether or not the conveyance distance Lt2 is equal to or greater than the distance (2La + Lp). It discriminate | determines (step S133a). Here, Lp may be determined regardless of the conveyance speed Vt. When it is determined that the transport distance Lt2 is not greater than or equal to the distance (2La + Lp) (“NO” in step S133a), the CPU 142 stops measuring the transport distance Lt2 (step S134a). If it is determined that the distance is equal to or greater than the distance (2La + Lp), the CPU 142 calls and executes the image formation return processing of the first modification shown in FIG. 9 (step S135a).

In the image formation return process of FIG. 9, when it is determined in the determination process in step S142 that no lift greater than the return lift amount H2 has been detected (“NO” in step S142), the CPU 142 measures the transport distance Lt2. It is determined whether it is in the middle (step S143a). If it is determined that the measurement is not in progress ("NO" in step S143a), measurement of the transport distance Lt2 by the transport unit 11 from this timing is started (step S144a). Then, the process of the CPU 142 proceeds to step S148a. If it is determined that the conveyance distance Lt2 is being measured, the process of the CPU 142 proceeds to step S148a.

If it is determined in the determination process in step S142 that a lift greater than the return lift amount H2 has been detected ("YES" in step S142), the CPU 142 determines whether or not the conveyance distance Lt2 is being measured. (Step S145a). If it is determined that the measurement is not in progress (“NO” in step S145a), the CPU 142 ends the image formation return processing and returns to the image formation interruption processing.

When it is determined that the transport distance Lt2 is being measured (“YES” in step S145a), the CPU 142 determines whether or not the transport distance Lt2 is equal to or greater than the distance (2La + Lp) (step S146a). If it is determined that the distance is not greater than (2La + Lp) (“NO” in step S146a), the CPU 142 stops measuring the transport distance Lt2 (step S147a), ends the image formation return process, and performs the process. Return to the image formation interruption process.

If it is determined that the transport distance Lt2 is greater than or equal to the distance (2La + Lp) (“YES” in step S146a), the process of the CPU 142 proceeds to step S148a.

When the process proceeds from step S143a, S144a, or S146a to step S148a, the CPU 142 newly increases the transport distance Lt2 to a distance (L1 + (N−1) L2 + Lh) with respect to any of the eight rows of carriages 120. It is determined whether or not (step S148a). This distance is the distance from the measurement position of the recording medium distance sensor 113 to the downstream end position in the transport direction of the Nth carriage 120. That is, the CPU 142 causes the recording medium distance sensor 113 to have a return lift amount H2 or more. After no longer being detected, it is determined whether or not the portion of the recording medium P at the position has passed the range facing the carriage 120 in the Nth row.

When it is determined that the portion of the recording medium P in which the lifting of the return lifting amount H2 or more has been detected is not more than the distance to the downstream end position in the transport direction of any carriage 120 (step S148a). The CPU 142 ends the image formation return process and returns to the image formation interruption process.

If it is newly determined that the distance to the downstream end position in the transport direction of the N-th carriage 120 is greater (“YES” in step S148a), the process of the CPU 142 proceeds to step S149. When the processing in step S149 is completed, the CPU 142 determines whether or not the transport distance Lt2 is newly greater than or equal to the distance (L1 + (N−1) L2 + Lh + La + Lm) with respect to any of the eight rows of carriages 120 (step S149). S150a). This distance includes the elevation time Ta related to the return operation of the carriage 120 to the ink ejection position started at the downstream end position in the conveyance direction of the carriage 120 in the Nth row after the measurement of the conveyance distance Lt2 is started. It is determined whether or not the return operation of the carriage 120 in the Nth row is completed, that is, the distance until the recording medium P is transported and moved within the margin time Tm related to the return operation.

If it is determined that there is no carriage 120 that has newly exceeded this distance (“NO” in step S150a), the CPU 142 ends the image formation return processing and returns the processing to the image formation interruption processing. If it is determined that there is a carriage 120 that has newly exceeded this distance (“YES” in step S150a), the CPU 142 executes the process of step S151.

In the determination process of step S152, when it is determined that the carriage 120 newly determined to be greater than or equal to the above-described distance in the process of step S150a is in the eighth row, the CPU 142 measures the conveyance distance Lt2. And the save flag is canceled (step S153a).

[Modification 2]
FIG. 10 is a flowchart illustrating a second modification of the image formation interruption process.

In the image formation interruption process of the modification 2, the process of step S160 is further added to the image formation interruption process of the modification 1. Except for this point, the image formation interruption process of the modification 2 is the same as the image formation interruption process of the modification 1, and the same processes are denoted by the same reference numerals and detailed description thereof is omitted.

In the image formation interruption process of the second modification, the process proceeds from the process of any of steps S132, S136, and S125a to the process of step S160 in a state where the lift of the recording medium P that is greater than the reference lift amount H1 is detected. The CPU 142 acquires the lifting distance H at this time, and sets the retreat distance H4 based on the lifting distance H. Then, the CPU 142 determines the ascending / descending time Ta and the ascending / descending time Ta based on the ascending / descending width H0 = H4−Hn and the ascending / descending speed Va when the distance from the transport surface to the nozzle surface changes from the ink ejection distance Hn to the retracted distance H4. The transport distance La during elevation is calculated (step S160). Then, the process of the CPU 142 proceeds to step S126a.

As a method for setting the retreat distance H4, a fixed retreat distance H4 may be set based on the maximum value of the lift distance H acquired in the lift portion where the lift of the reference lift amount H1 or more is detected. A retreat distance H4 that is followed by applying a predetermined low-pass filter to the transition of the lift distance H may be set.

As described above, in the image formation interruption process according to the first and second modifications, the process related to the interruption and return of the image formation is directly controlled based on the measurement data of the encoder 112 instead of the measurement time. I can do it.

Further, in the image formation interruption process in the inkjet recording apparatus 100 according to the second modification, the CPU 142 can change the retreat distance according to the amount of lifting of the recording medium P. As the evacuation distance increases, the ascending / descending time for the evacuation operation also becomes longer and the time for interrupting ink ejection becomes longer.Therefore, only the necessary ascending / descending time is ensured by not increasing the evacuation distance more than necessary, thereby efficiently forming an image. Can be done.

[Second Embodiment]
Next, the ink jet recording apparatus according to the second embodiment will be described.
The internal configuration of the ink jet recording apparatus 100 according to the second embodiment is the same as the internal structure of the ink jet recording apparatus 100 according to the first embodiment, and the description thereof will be omitted by assigning the same reference numerals.

In the operation related to image formation of the ink jet recording apparatus 100 of the present embodiment, only the processing content of the image formation interruption processing called and executed in the image formation control processing shown in FIG. 4 is different. Therefore, the description other than the contents of the image formation interruption process is omitted.

FIG. 11 is a flowchart showing a control procedure by the CPU 142 of the image formation interruption process called in the image formation control process executed by the inkjet recording apparatus 100 of the present embodiment.
In this image formation interruption process, the processes of steps S161 to S164 are added, and the first process including the contents of the image formation return process (FIG. 6) to be called is included except that the process of step S127 is changed to step S127b. This is the same as the image formation interruption processing (FIG. 5) executed in the embodiment, and the same reference numerals are used for the same processing, and detailed description thereof is omitted.

When the conveyance speed Vt is acquired in the process of step S125, the CPU 142 further outputs the output image length Le that is the length in the conveyance direction of the output image F that is currently being image-formed, and the image is repeatedly formed. The image interval Ld and the output distance x1e from the head of the currently captured image are acquired (step S161).

CPU142 is by an ink-jet head 12 mounted on the carriage 120 of the N columns, calculates the remaining distance LR _N to the rear end of the finished possible output image F to escape operation before the start of the carriage 120 due to the floating is detected (Step S162). Remaining distance LR _N according to the carriage 120 is expressed by the following equation (4).
LR _N = B (Le−x1e) + k (Ld + Le) + (N−1) L2 (4)
Here, the discriminant value B is a value indicating whether or not an image can be formed at a distance (Le-x1e) to the rear end of the output image F formed by the inkjet head 12 related to the carriage 120 in the first row. It is expressed by either of the following formulas (5a) and (5b) depending on the conditions.
B = 0 (Le−x1e) / Vt <L1 / Vt− (Ta + Tm) (5a)
B = 1 (Le−x1e) / Vt ≧ L1 / Vt− (Ta + Tm) (5b)
Further, the total number of output sheets k indicates the number of output images F that can be output over the entire output image length Le by the inkjet head 12 of the carriage 120 in the first row, in addition to the above-described intermediate image. That is, the total number of output sheets k is expressed by the following formula (6).
k = int ((L1- (Le-x1e) -Vt (Ta + Tm)) / (Ld + Le)) (6)
Here, int represents a quotient of division (an integer greater than or equal to 0).
In the inkjet recording apparatus 100, when the distance L1 is not larger than the output image length Le so that k ≧ 1, the process may be simplified by fixing k = 0 from the beginning.

For example, the output distance x1e may be used for calculation by holding in advance a time difference between the data transmission timing from the memory 141 and the ink ejection timing from the ink ejection unit 122 based on the transmitted data, or It may be indirectly calculated from an elapsed time from the output timing of the head of each image.
Further, in the case where an imaging unit is provided for inspection of the output image, the calculation may be performed based on imaging data obtained by the imaging unit.
The output distance x1e may be an approximate value.

The CPU 142 determines whether or not there is an N-row carriage 120 whose elapsed time t1 is newly equal to or greater than LR _N / Vt (step S163). If it is determined that there is (“YES” in step S163), the CPU 142 outputs a control signal to the drive circuit 121 to stop ink ejection from the inkjet head 12 related to the N-th carriage 120. (Step S164). Then, the process of the CPU 142 proceeds to step S126. When it is determined that there is no new elapsed time t1 that is equal to or greater than LR _N / Vt (“NO” in step S163), the process of the CPU 142 proceeds to step S126.

When it is determined in the determination process in step S126 that there is a new start timing for the retracting operation of the carriage 120 in the Nth column (“YES” in step S126), the CPU 142 The operation of moving the carriage 120 to the retracted position is started (step S127b). At this time, the ink ejection from the inkjet head 12 related to the carriage 120 in the Nth row has already been stopped by the process of step S164. Then, the process of the CPU 142 proceeds to step S128.

12A and 12B are diagrams illustrating an example of setting the ink discharge interruption timing in the inkjet recording apparatus 100 of the present embodiment.

As shown in FIG. 12A, the output image F of the output image length Le is output by the inkjet head 12 fixed to the carriage 120 in the first row at the timing when the recording medium distance sensor 113 detects the lift of the reference lift amount H1 or more. Of these, when the image is formed up to the position of length x1e, the length of the remaining output image F is the distance (Le-x1e), and this length is one row from the measurement position by the recording medium distance sensor 113. It is shorter than the distance (L1-La-Lm) until the eye carriage 120 starts to retract. On the other hand, the length necessary to form the next output image F over the entire output image length (Le + Ld) is longer than the distance to the retracting operation start position of the carriage 120 in the first row. Therefore, here, B = 1 and k = 0 are set, and ink ejection is interrupted when image formation is performed up to the end of the currently output image.

Ink ejection by the inkjet head 12 fixed to the carriage 120 in the second row is a length obtained by adding a distance L2 in the transport direction between the carriage 120 in the first row and the carriage 120 in the second row to this length. Ink is discharged over the course. Accordingly, ink is discharged from the inkjet head 12 fixed to the second row carriage 120 to the recording medium P to the same position as the ink is discharged from the inkjet head 12 fixed to the first row carriage 120. Done.

On the other hand, as shown in FIG. 12B, the remaining output image length (Le-x1e) of the current output image F by the inkjet head 12 related to the carriage 120 in the first row is the first row from the measurement position by the recording medium distance sensor 113. The output image F cannot be completed if the distance is longer than the distance (L1-La-Lm) until the carriage 120 is retracted, so that B = 0 and k = 0 and the carriage 120 in the first column The ink ejection by the inkjet head 12 is immediately stopped at the current position.

In this case, the ink discharge length before the movement to the retracted position by the inkjet head 12 related to the carriage 120 in the second row is set to a length (L2 + Lh) that is the sum of the interval between the carriages and the width of the carriage 120. I can do it.
In addition, for the output image F in which ink was not completely discharged by the ink jet head 12 related to the carriage 120 in the first row, ink was discharged from the ink jet head 12 related to the carriage 120 in the second row and thereafter. May be omitted. That is, the ink ejection length by the inkjet head 12 related to the carriage 120 in the second row in this case may be set to the length (Le-x2e).

As described above, in the inkjet recording apparatus 100 according to the second embodiment, the CPU 142 displays an image in the middle of being formed by the ink ejection unit 122 at the floating detection timing when the floating amount is equal to or greater than the reference floating amount H1. It is determined whether or not all can be formed before the retracting operation start timing, and if it is determined that the formation is not possible, the ink ejecting unit before the retracting operation start timing, particularly at the time when this determination is performed. Since the ink ejection is stopped at 122, for the portion where the entire image is not formed even when the ink is ejected until the start timing of the evacuation operation, the image formation is abandoned from the beginning to suppress the ink consumption and increase the efficiency. I can do it.

On the contrary, if it is determined that all the images currently being formed can be formed before the retracting operation start timing, the CPU 142, after the completion of the formation, before the retracting operation start timing, In particular, by stopping the ink ejection at the timing when the formation of the image in the middle of the formation is completed, it is possible to reduce the waste of the recording medium P and the ink due to the image formation being performed halfway and being discarded.

In addition, when the CPU 142 can form not only an image that is currently being formed but also one or more images before the start timing of the evacuation operation, the CPU 142 discharges ink related to the image that can be formed. After the completion of the formation of all these images, the discharge unit 122 cancels the ink discharge at the timing before the evacuation operation start timing, particularly at the completion of the formation of all the images. It is possible to reduce the recording medium P and the amount of wasted ink.

The present invention is not limited to the above-described embodiment, and various modifications can be made.
For example, in the above-described embodiment, the recording medium has been described by taking the cloth continuous in the conveyance direction as an example. However, recording paper or other materials may be used. The present invention is more preferably applied. Further, it is not limited to a continuous recording medium (continuous book medium), and cut paper may be used. In this case, for example, the technique according to the present invention can be used more preferably when a plurality of images are arranged in a pattern at least in the conveying direction on one cut sheet.

Further, if the nozzle surface of the inkjet head 12 can be variably set from the conveyance surface by the operation of the lifting motor 132, the type of the lifting motor 132, the mounting arrangement and structure of the inkjet head 12 and the lifting motor 132 are as follows. It is determined arbitrarily. For example, a plurality of ink jet heads 12 may be directly attached to the carriage, or a plurality of ink jet heads 12 may be formed together in an ink jet head unit and the ink jet head unit attached to the carriage.
Further, the number and size of the inkjet heads 12 are arbitrarily determined.

Also, the nozzle surface does not have to be a complete plane. In this case, the operation may be performed based on the case where the distance between the transport surface and the nozzle surface is the smallest. Further, the movement of each part of the inkjet head 12 may be slightly varied as long as the position of the nozzle surface facing the conveyance surface can be accurately moved. For example, when FPC (Flexible Printed Circuit) or the like is used, the distance in the z direction between the FPC and the nozzle surface does not necessarily have to be kept constant.

In the above embodiment, the lifting / lowering speed of the carriage 120 is constant, but there may be a plurality of lifting / lowering speeds. For example, there is a difference between the speed at which the carriage 120 is moved (raised) to the retracted position and the speed at which the carriage 120 is moved (lowered) to the ink ejection position according to the type of the lifting motor 132 and the like. Also good.

Further, the type and arrangement of the recording medium distance sensor 113 are arbitrarily determined. For example, it is good also as measuring the distance to the recording medium surface using the reflected light of the irradiated light provided opposite to the recording medium P, or the light is irradiated from the side and the floating part The shading state by may be detected. Further, not only visible light, but also electromagnetic waves having wavelengths that can be detected with a required accuracy and each wavelength of the scattering rate may be used.

Further, it is not necessary to directly acquire the conveyance speed from the encoder 112, and a set speed stored in advance in the memory 141 or the like may be acquired and used. When the speed and the transport distance are acquired from the encoder 112, the measurement value can be acquired flexibly and accurately even if the transport speed changes during the measurement of the elapsed time or the transport distance.

In the above-described embodiment, a case has been described in which the determination of interruption and return of image formation is performed using the distance (flying distance) between the conveyance surface and the surface of the recording medium based on the lifting of the recording medium due to wrinkles or the like. The lift shown in the specification is not limited to the case where the recording medium and the conveyance surface are actually separated from each other, and includes unevenness on the surface due to non-uniform thickness of the recording medium. It may be determined whether the image formation is interrupted or restored in accordance with the change in the thickness of the recording medium.

In the above embodiment, after the interruption of image formation and the retracting operation of the carriage 120, the time when the measured value of the lift amount becomes less than the return lift amount H2 smaller than the reference lift amount H1 is equal to or longer than a predetermined standby time (2Ta + Tp). If it is continued, the carriage 120 is returned to resume image formation. However, the same determination and operation may be performed with the return lift amount H2 set equal to the reference lift amount H1. Further, as long as the reference lift amount H1 is less than the maximum retreat distance H3, the reference lift amount H1 is appropriately set according to the material of the recording medium P and the like.
Further, after a lift amount less than the return lift amount H2 is detected once, even if a lift greater than the return lift amount H2 is detected during the subsequent standby time (2Ta + Tp), the lift amount is not less than a predetermined distance not more than the reference lift amount H1. If not, image formation may be resumed.
Further, the recording time Tp in the standby time (2Ta + Tp) is set to “0”, and further, the standby time is not set, so that the lift amount less than the return lift amount H2 over the standby time (2Ta + Tp) does not continue. Alternatively, the carriage 120 may be simply returned. In this case, although the discrimination process is facilitated, the carriage 120 is returned halfway, but before the movement to the position where the distance from the conveyance surface to the nozzle surface becomes the ink discharge distance Hn, that is, the ink is discharged. There may be a case where the carriage 120 is moved again to the retracted position without restarting the ejection.

Further, in the above embodiment, the image after the interruption of the ink ejection is formed from the top. However, when the recording medium portion of the image before the interruption and the recording medium portion of the image after the interruption can be connected and processed. The image formation may be resumed from the image position where the ink ejection is interrupted.

In the above-described embodiment, the line head type ink jet recording apparatus using eight colors of ink has been described as an example. However, the number of colors is not limited to this, and for example, ink jet recording in which only monochrome image formation is performed. It may be a device. Even when the ink jet recording apparatus 100 does not have a line head type structure, the technology according to the present invention can be applied while taking into consideration the moving speed of the ink jet head 12 in the width direction.

In the above embodiment, the same image is repeatedly formed. However, the image may not be the same as long as the image is repeatedly formed. For example, different serial numbers may be formed at the corners of the image every time, or a predetermined number of images may be circulated to repeatedly form images.

In the above embodiment, the conveyance speed is measured by the encoder 112, and the distance L1 is a fixed value. However, the conveyance speed may be a fixed value and / or the distance L1 may be variable. In the case of a fixed value, it can be appropriately stored in the ROM 143 or a storage unit (not shown) of the control unit 14, and when the distance L1 is variable, for example, the distance can be measured with a linear encoder or the like. I can do it.
In addition, specific details such as configuration, arrangement, control contents, and control procedure shown in the above embodiment can be appropriately changed without departing from the gist of the present invention.

The present invention can be used for an ink jet recording apparatus.

11 transport unit 111 transport motor 112 encoder 113 recording medium distance sensor 114 drive roller 115 transport belt 12 inkjet head 120 carriage 121 drive circuit 122 ink ejection unit 13 carriage lift unit 131 motor driver 132 lift motor 133 electromagnetic brake 134 beam member 135 support unit 14 Control unit 141 Memory 142 CPU
143 ROM
144 RAM
145 Bus 15 Operation display unit 16 Communication unit 100 Inkjet recording apparatus B Discrimination value F Output image H0 Lifting width H1 Reference lift amount H2 Return lift amount H3 Maximum retraction distance H4 Retraction distance Hn Ink discharge distance k Total number of output sheets L1 Distance L2 Interval La Elevating transport distance Ld Interval Le Output image length Lm Margin Lp Recording distance Lt1 Conveying distance Lt2 Conveying distance P Recording medium t1 Elapsed time t2 Elapsed time Ta Elevating time Tm Margin time Tp Recording time Tt Arrival time Va Elevating speed Vt Conveying speed x1e Output distance

Claims

A transport unit that transports the recording medium on the transport surface in a predetermined transport direction;
An ink ejection unit that ejects ink droplets from a nozzle opening provided on a nozzle surface facing the transport surface;
An elevating unit that moves the ink ejection unit to change the distance between the nozzle surface and the transport surface;
A measurement unit that measures the flying distance of the recording medium from the conveyance surface at a measurement position that is a predetermined separation distance upstream of the ink ejection unit in the conveyance direction;
When the flying distance measured by the measurement unit is equal to or greater than a predetermined first distance, the distance is equal to or greater than the first distance based on the separation distance and the conveyance speed of the recording medium by the conveyance unit. After a predetermined time elapses from the floating detection timing, the ink rises until a timing at which the floating portion of the recording medium whose flying distance is equal to or greater than the first distance is transported within a range facing the ink discharge portion. An elevating control unit for causing the elevating unit to perform a retreat operation for changing the distance between the discharge unit and the transport surface to a predetermined retreat distance in which the nozzle surface and the floating portion do not contact;
An ejection control unit that causes the ink ejection unit to continue ejecting ink droplets at least halfway from the rising detection timing to the withdrawal operation start timing for starting the withdrawal operation;
An ink jet recording apparatus comprising:
2. The ink jet recording apparatus according to claim 1, wherein the elevation control unit changes the retreat distance according to the flying distance.
After the ascent distance becomes equal to or greater than the first distance, when the ascent distance falls below a second distance that is equal to or less than the first distance, the elevating control unit is configured such that the ascent distance is equal to or greater than the second distance. A return operation for changing the distance between the nozzle surface and the transport surface to a predetermined ink discharge distance for discharging ink from the nozzle opening after the portion has passed through the range facing the ink discharge portion; Let the elevator move,
The ejection control unit restarts ejection of the ink droplets related to image formation from the nozzle opening portion related to the ink ejection unit on which the restoration operation has been performed after the completion of the restoration operation. Item 3. The ink jet recording apparatus according to Item 1 or 2.
4. The ink jet recording apparatus according to claim 3, wherein the elevating control unit allows the returning operation to be executed by the elevating unit when the second distance falls below the second distance for a predetermined waiting time.
The waiting time is equal to or longer than the time required for the nozzle surface to reciprocate at a predetermined elevation speed between the retreat distance and the ink ejection distance, and the recording medium is conveyed by the separation distance. The inkjet recording apparatus according to claim 4, wherein the inkjet recording apparatus is shorter than the time.
The discharge control unit, after completion of the return operation, causes an ink pre-discharge operation from the nozzle opening, and then restarts ink discharge related to image formation from the nozzle opening. Item 6. The ink jet recording apparatus according to any one of Items 3 to 5.
The inkjet recording apparatus according to claim 5 or 6, wherein the discharge control unit forms the image to be formed from the top of the image to be formed after the return operation is completed.
Whether the ejection control unit can form all the images formed by the ink ejection unit at the floating detection timing before the retracting operation start timing when the flying distance is equal to or greater than the first distance. The ink ejection is stopped before the retracting operation start timing when it is determined that the ink cannot be formed. 2. An ink jet recording apparatus according to 1.
Whether the ejection control unit can form all the images formed by the ink ejection unit at the floating detection timing before the retracting operation start timing when the flying distance is equal to or greater than the first distance. The ink ejection is stopped after the timing when the formation is completed and before the retracting operation start timing when it is determined whether or not the formation is possible. The ink jet recording apparatus according to any one of 1 to 8.
The ejection control unit ejects ink related to a target image of the formation that can be completed before the retracting operation start timing when the flying distance is equal to or more than the first distance. 8. The ink jet recording apparatus according to claim 1, wherein the ink ejection is stopped before the retracting operation start timing after the timing at which the image forming is completed. .
11. The conveyance control unit according to claim 1, further comprising a conveyance control unit that stops conveyance of the recording medium when the flying distance is larger than a maximum value of the retraction distance. The ink jet recording apparatus described.
A plurality of the ink ejection units are arranged at different positions in the transport direction,
The elevating unit is configured to independently change the distance between the nozzle surface and the transport surface of the plurality of ink ejection units,
The elevating control unit performs the same elevating operation corresponding to the distance between the plurality of ink ejection units and the floating portion, and changes the distance between the nozzle surface and the transport surface to the retreat distance. The inkjet recording apparatus according to any one of claims 1 to 11, wherein:
The ink jet recording apparatus according to any one of claims 1 to 12, wherein the recording medium is a cloth and is continuous in the transport direction for longer than the separation distance.