WO2017169237A1

WO2017169237A1 - Inkjet recording device and recording control method for inkjet recording device

Info

Publication number: WO2017169237A1
Application number: PCT/JP2017/005612
Authority: WO
Inventors: 直也駒田; 暢彦小山
Original assignee: コニカミノルタ株式会社
Priority date: 2016-03-28
Filing date: 2017-02-16
Publication date: 2017-10-05
Also published as: EP3437871A1; EP3437871A4; JPWO2017169237A1

Abstract

Provided are an inkjet recording device and a recording control method for an inkjet recording device with which it is possible to suppress degradation in the quality of a recorded image more appropriately. This inkjet recording device comprises: a recording means including an ink discharge unit that discharges ink from nozzles; a transportation means that transports a recording medium; a recording control means that causes the ink discharge unit to discharge ink onto the recording medium which has been transported by the transportation means and is in opposition to the nozzles; a transportation control means that changes a transportation speed of the recording medium by the transportation means; and a speed-corresponding information acquisition means that acquires speed-corresponding information related to the transportation speed. At least during a period in which the transportation speed is being changed, the recording control means causes the ink discharge unit to discharge the ink at a timing upon the lapse of a delay time from a discharge reference timing when a discharge target position on the recording medium has moved to a predetermined discharge reference position, said delay time being determined on the basis of the speed-corresponding information related to the transportation speed at said discharge reference timing.

Description

Inkjet recording apparatus and recording control method for inkjet recording apparatus

The present invention relates to an ink jet recording apparatus and a recording control method for the ink jet recording apparatus.

Conventionally, an image is printed on a recording medium by repeatedly ejecting ink from the nozzles by means of ink ejecting means in which the nozzles are arranged in a width direction intersecting the transporting direction with respect to the recording medium transported in the predetermined transporting direction by the transporting means. There is an ink jet recording apparatus that records In this ink jet recording apparatus, each ink is ejected at a timing when the ink ejection target position on the recording medium moves to a predetermined ejection reference position in the transport direction, so that the ink is landed at an appropriate interval in the transport direction. Appropriate images can be recorded.

In addition, in an ink jet recording apparatus, an image is usually recorded while a recording medium is conveyed at a constant speed. However, when the conveyance speed of the recording medium fluctuates, the timing when the ejection target position of the recording medium moves to the ejection reference position. In other words, there is a technique for suppressing deterioration in the image quality of a recorded image by adjusting the ejection timing of the ink so that the ink is ejected (for example, Patent Document 1 and Patent Document 2).

JP 2007-168226 A Japanese Patent No. 5303337

However, in an inkjet recording apparatus, for example, the user visually checks and confirms the image quality of the image being recorded while conveying the recording medium at a low speed and recording the image. There is a demand for changing the conveyance speed during the recording operation, such as increasing the recording speed and increasing the recording speed of subsequent images.
In such a case, if the conveyance speed of the recording medium is changed, the distance (in which the recording medium moves from when the ink is ejected from the nozzle to when it reaches the recording medium) according to the change in the conveyance speed ( The movement distance after discharge fluctuates. For this reason, the above-described conventional technique has a problem that the ink landing position is deviated by an amount corresponding to the change in the post-ejection movement distance according to the change in the conveyance speed, and the image quality of the recorded image is lowered.

An object of the present invention is to provide an ink jet recording apparatus and a recording control method for an ink jet recording apparatus that can more appropriately suppress a deterioration in image quality of a recorded image.

In order to achieve the above object, the invention of the ink jet recording apparatus according to claim 1 comprises:
A recording means having an ink discharge portion for discharging ink from the nozzle;
Conveying means for conveying the recording medium in a predetermined conveying direction;
Recording control means for causing ink to be ejected from the nozzles by the ink ejection unit to a recording medium conveyed by the conveyance means and facing the ink ejection ports of the nozzles;
A conveyance control means for changing the conveyance speed of the recording medium by the conveyance means;
Speed correspondence information obtaining means for obtaining speed correspondence information related to the transport speed;
With
The recording control means starts from an ejection reference timing at which an ink ejection target position on the recording medium has moved to a predetermined ejection reference position in the conveyance direction at least during a period when the conveyance control means is changing the conveyance speed. Ink is ejected by the ink ejection unit at a timing when a delay time determined based on the speed correspondence information related to the transport speed at the ejection reference timing has elapsed.

According to a second aspect of the present invention, in the ink jet recording apparatus according to the first aspect,
The recording unit includes a plurality of the ink ejection units arranged at different positions in the transport direction,
The recording control means includes a plurality of ejection reference timings based on a plurality of ejection reference timings in which the ejection target positions of the recording medium have moved to the plurality of ejection reference positions respectively corresponding to the plurality of ink ejection units. Ink is ejected by an ink ejection section corresponding to each of the plurality of ejection reference positions at a timing when a delay time determined based on the speed correspondence information relating to the transport speed in each of the plurality of ejection reference positions has elapsed.

The invention according to claim 3 is the ink jet recording apparatus according to claim 2,
The speed correspondence information acquisition unit acquires the speed correspondence information for the conveyance speed of the recording medium at a position facing each of the plurality of ink ejection units in the conveyance direction,
The recording control means includes a delay time determined by each of the plurality of ink ejection units based on the speed correspondence information relating to the conveyance speed of the recording medium at a position facing the ink ejection unit from the ejection reference timing. It is characterized in that ink is ejected at the timing when the time elapses.

The invention according to claim 4 is the ink jet recording apparatus according to any one of claims 1 to 3,
The delay time is determined based on a distance between the recording medium and an ink discharge port of the nozzle in the ink discharge direction from the nozzle and the speed correspondence information.

The invention according to claim 5 is the inkjet recording apparatus according to any one of claims 1 to 4,
The transport means operates in a plurality of transport modes for transporting recording media at different transport speeds,
The conveyance control means changes the conveyance speed over a predetermined time when switching the conveyance mode of the conveyance means.

The invention according to claim 6 is the ink jet recording apparatus according to any one of claims 1 to 5,
The transport means transports the recording medium by placing the recording medium on the transport surface of the transport member and moving the transport member,
The transport control means changes the transport speed of the recording medium by changing the moving speed of the transport member,
The speed correspondence information acquisition unit includes a movement detection unit that outputs a predetermined detection signal for each predetermined amount of movement of the transport member, and is required for a predetermined number of times of detection of the detection signal or per predetermined time. The speed correspondence information is acquired based on the number of detected signals detected.

The invention according to claim 7 is the inkjet recording apparatus according to claim 6,
The recording control means detects the ejection reference timing based on the detection signal.

In order to achieve the above object, an invention of a recording control method for an ink jet recording apparatus according to claim 8 comprises:
A recording control method for an ink jet recording apparatus comprising: a recording unit having an ink discharge unit that discharges ink from a nozzle; and a transport unit that transports a recording medium in a predetermined transport direction,
A recording step in which ink is ejected from the nozzles by the ink ejection unit with respect to a recording medium that is transported by the transport unit and is opposed to the ink ejection port of the nozzle;
A conveyance control step of changing a conveyance speed of the recording medium by the conveyance means;
A speed correspondence information obtaining step for obtaining speed correspondence information related to the transport speed;
Including
In the recording step, at least from a discharge reference timing at which an ink discharge target position on the recording medium has moved to a predetermined discharge reference position in the transport direction in a period in which the transport speed is changed in the transport control step. Ink is ejected by the ink ejecting section at a timing when a delay time determined based on the speed correspondence information related to the transport speed at the ejection reference timing has elapsed.

According to the present invention, there is an effect that the deterioration of the image quality of the recorded image can be more appropriately suppressed.

It is a figure which shows schematic structure of an inkjet recording device. It is a schematic diagram which shows the structure of a head unit. It is a block diagram which shows the main function structures of an inkjet recording device. FIG. 5 is a diagram illustrating a method for adjusting ink ejection timing in an inkjet recording apparatus. It is a flowchart which shows the control procedure of an image recording process. 6 is a flowchart illustrating a control procedure of ink ejection processing. It is a figure which shows schematic structure of the inkjet recording device which concerns on a modification.

Hereinafter, embodiments of an ink jet recording apparatus and a recording control method of the ink jet recording apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of an ink jet recording apparatus 1 according to an embodiment of the present invention.
The ink jet recording apparatus 1 includes a transport unit 10 (transport unit), a recording unit 20 (recording unit), a control unit 30, and the like.

The transport unit 10 includes a drive roller 11, a driven roller 12, a transport belt 13, a transport motor 14, a rotary encoder 15 (movement detection unit), a pressing roller 16, a peeling roller 17, and the like.
The drive roller 11 rotates around a rotation axis extending in the X direction of FIG. The conveyor belt 13 is a ring-shaped belt that is supported on the inner side by the driving roller 11 and the driven roller 12, and moves around as the driving roller 11 rotates. The driven roller 12 rotates around a rotation axis extending in the X direction as the conveying belt 13 rotates. As the conveyor belt 13, a material that is flexibly bent at the contact surface with the driving roller 11 and the driven roller 12 and that reliably supports the recording medium M is used. For example, a belt made of resin such as rubber, A steel belt or the like can be used. Since the conveyance belt 13 has a material and / or a configuration on which the recording medium M is adsorbed, the recording medium M can be more stably placed on the conveyance belt 13. The transport unit 10 rotates the drive roller 11 in a state where the recording medium M is placed on the transport surface of the transport belt 13 and the transport belt 13 rotates to move the recording medium M in the moving direction of the transport belt 13 ( Transport direction: Y direction in FIG.

The recording medium M is pulled out from the roll around which the recording medium M is wound and supplied onto the conveyance belt 13, and after the image is recorded by the recording unit 20, the recording medium M is taken up by another roll. The recording medium M may be a sheet cut to a certain size. In this case, after the recording medium M is supplied onto the conveying belt 13 by the paper feeding device and an image is recorded. The paper is discharged from the transport belt 13 to a predetermined paper discharge unit by the paper discharge device.
As the recording medium M, various media capable of fixing the ink ejected on the surface, such as paper, fabric, or sheet-like resin, can be used.
The transport unit 10 of the present embodiment is configured to be able to transport a large recording medium M having a width in the X direction of about 2 m. Note that the recording medium M having a width in the X direction smaller than 2 m may be transported by the transport unit 10. Further, the transport unit 10 may be configured to transport the recording medium M having a width in the X direction larger than 2 m (for example, about 4 m), and the maximum width in the X direction of the transportable recording medium M. May be smaller than 2 m.

The rotary encoder 15 is attached to the drive roller 11 and outputs a pulse signal (detection signal) to the control unit 30 and the recording head drive control unit 211 (FIG. 3) every time the drive roller 11 rotates by a predetermined angle. The configuration of the rotary encoder 15 is not particularly limited. For example, a code wheel that is provided with a plurality of slits arranged on a predetermined circumference and rotates together with the driving roller 11 and the slits of the code wheel are irradiated with light. And a light receiving unit that detects light emitted from the light emitting unit and passed through the slit, and outputs a pulse signal based on a detection result of the light by the light receiving unit to the control unit 30 and the recording head drive control unit 211. It can be. Here, for example, the pulse signal is output at the rising and falling timings in each of two rectangular groups (A phase and B phase) having the same period as the light receiving period of the light passing through the slit and having a phase difference of 90 degrees from each other. Can be. In such a configuration, the rotation direction of the drive roller 11 can also be detected from the phases of the A phase and the B phase.

The pressing roller 16 presses the recording medium M supplied to the conveying surface of the conveying belt 13 against the conveying surface to remove wrinkles and other lifts from the conveying surface.
The peeling roller 17 pulls the recording medium M that has been conveyed while being adsorbed to the conveying belt 13 with a predetermined pressure, thereby peeling the recording medium M from the conveying surface and sending it to a post-processing device (not shown).

The recording unit 20 includes four head units 21 (ink ejection units). Each head unit 21 records an image by ejecting ink from the nozzles on the recording medium M conveyed by the conveyance unit 10 based on the image data. In the ink jet recording apparatus 1 according to the present embodiment, four head units 21 corresponding to four colors of ink of yellow (Y), magenta (M), cyan (C), and black (K) respectively are transported in the recording medium M. They are arranged so as to be arranged at predetermined intervals in the order of Y, M, C, and K colors from the upstream side.

FIG. 2 is a schematic diagram showing the configuration of the head unit 21. This figure is a plan view of the head unit 21 as viewed from the side facing the conveyance surface of the conveyance belt 13.
The head unit 21 includes eight recording heads 212 arranged in a direction in which a plurality of recording elements that eject ink intersect the transport direction of the recording medium M (in this embodiment, a direction orthogonal to the transport direction, that is, the X direction). Prepare. FIG. 2 shows the position of the ink ejection port of the nozzle 213 which is a component of the recording element. In the head unit 21, the eight recording heads 212 are staggered so that the ranges in which the ink can be ejected from the nozzles 213 are continuously connected in the X direction so that the arrangement ranges in the X direction partially overlap each other. Arranged in a grid.
The arrangement range in the X direction of the nozzles 213 included in the head unit 21 covers the width in the X direction of an area in which an image can be recorded in the recording medium M conveyed by the conveyance belt 13. When recording an image, the position is fixed and used. That is, the inkjet recording apparatus 1 is a single-pass inkjet recording apparatus using a head unit 21 having a line head.

Each recording element of the recording head 212 has a pressure chamber for storing ink, a piezoelectric element provided on the wall surface of the pressure chamber, and a nozzle 213. When a drive signal for deforming the piezoelectric element is input to the recording element, the pressure chamber is deformed by the deformation of the piezoelectric element, the pressure in the pressure chamber is changed, and ink is ejected from a nozzle communicating with the pressure chamber.

FIG. 3 is a block diagram showing the main functional configuration of the inkjet recording apparatus 1.
The ink jet recording apparatus 1 includes a transport driving unit 101 and a rotary encoder 15 provided in the transport unit 10, a recording head drive control unit 211 and a recording head 212 provided in the head unit 21, a control unit 30, and an operation display unit. 41, an input / output interface 42, a bus 43, and the like. Among these, the control unit 30 includes a CPU 31 (Central Processing Unit) (transport control means), a RAM 32 (Random Access Memory), a ROM 33 (Read Only Memory), and a storage unit 34. In the present embodiment, the CPU 31 and the recording head drive control unit 211 constitute a recording control unit.

The transport driving unit 101 supplies a driving signal to the transport motor 14 based on a control signal supplied from the CPU 31 to rotate the driving roller 11 at a predetermined rotational speed, thereby moving the transport belt 13 at a predetermined moving speed. Let Further, the transport driving unit 101 changes the rotation speed of the driving roller 11, that is, the moving speed of the transport belt 13 based on a control signal supplied from the CPU 31.

The recording head drive control unit 211 supplies a driving signal for deforming the piezoelectric element according to the image data at an appropriate timing to the recording element of the recording head 212, so that the image data of the recording head 212 is output from the nozzle 213. An amount of ink corresponding to the pixel value is ejected. Further, the recording head drive control unit 211 calculates the moving speed of the conveying belt 13, that is, the conveying speed of the recording medium M, based on the pulse signal output from the rotary encoder 15. Further, the recording head drive control unit 211 calculates a delay time of the ink ejection timing based on the calculated conveyance speed.
In the present embodiment, a total of four recording head drive control units 211 are provided for each two adjacent recording heads 212 of the eight recording heads 212 in each head unit 21. The recording head drive control unit 211 includes, for example, a circuit board connected to the two recording heads 212 and a semiconductor integrated circuit such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuits) mounted on the circuit board. It can be set as the structure containing these. The four print head drive control units 211 calculate the transport speed and the delay time independently of each other, adjust the ink ejection timing by the print head 212, and supply a drive signal to the print head 212. A method for adjusting the ink ejection timing by the recording head drive control unit 211 will be described later. In the present embodiment, the rotary encoder 15 and the recording head drive control unit 211 constitute a speed correspondence information acquisition unit.
Note that the number of recording heads 212 to which one recording head drive control unit 211 corresponds is not limited to two. For example, the recording head drive control unit 211 may be provided for each recording head 212, or a head unit. One recording head drive control unit 211 may be provided for all the recording heads 212 in FIG.

The CPU 31 reads various control programs and setting data stored in the ROM 33, stores them in the RAM 32, and executes the programs to perform various arithmetic processes. The CPU 31 controls the overall operation of the inkjet recording apparatus 1. For example, the CPU 31 operates each unit of the transport unit 10 and the recording unit 20 based on the image data stored in the storage unit 34 to record an image on the recording medium M. Further, the CPU 31 operates the transport unit 10 in a plurality of transport modes in which the recording medium M is transported at different transport speeds.

The RAM 32 provides a working memory space to the CPU 31 and stores temporary data. The RAM 32 may include a nonvolatile memory.

The ROM 33 stores various control programs executed by the CPU 31, setting data, and the like. Instead of the ROM 33, a rewritable nonvolatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory may be used.

The storage unit 34 stores a print job (image recording command) input from the external apparatus 2 via the input / output interface 42 and image data related to the print job. As the storage unit 34, for example, an HDD (Hard Disk Drive) is used, and a DRAM (Dynamic Random Access Memory) or the like may be used in combination.

The input / output interface 42 mediates data transmission / reception between the external device 2 and the control unit 30. The input / output interface 42 is configured by, for example, one of various serial interfaces, various parallel interfaces, or a combination thereof.

The bus 43 is a path for transmitting and receiving signals between the control unit 30 and other components.

The external device 2 is a personal computer, for example, and supplies a print job, image data, and the like to the control unit 30 via the input / output interface 42.

Next, a method for adjusting the ink ejection timing in the inkjet recording apparatus 1 of the present embodiment will be described.
In the ink jet recording apparatus 1 of the present embodiment, the conveyance speed of the recording medium M can be changed while an image is recorded on the recording medium M. For example, first, an image is recorded and recorded while the recording medium M is transported in the first transport mode in which the transport speed of the recording medium M is a first transport speed at which the image quality of the image being recorded can be visually recognized. After the user confirms that there is no abnormality in the image quality of the image, the subsequent image is changed to the second transport mode in which the transport speed of the recording medium M is the second transport speed larger than the first transport speed. Can be recorded at high speed. Here, when the transport mode is switched from the first transport mode to the second transport mode, and the transport speed is gradually changed between the first transport speed and the second transport speed over a predetermined time. The image recording is continued. By enabling such an operation, it is possible to suppress the amount of the recording medium M that is used for confirming the image quality of the recorded image and becomes waste paper.
In the ink jet recording apparatus 1 of the present embodiment, in order to record an image with an appropriate image quality when the conveyance speed of the recording medium M is changed, the conveyance speed of the recording medium M is calculated, and the calculated conveyance speed and The ink ejection timing is adjusted according to the distance between the nozzle 213 and the recording medium M in the ink ejection direction (Z direction) (hereinafter also referred to as the ejection distance). Hereinafter, a method for adjusting the ink ejection timing will be described.

FIG. 4 is a diagram for explaining a method for adjusting the ink discharge timing in the inkjet recording apparatus 1.
A pulse signal output from the rotary encoder 15 is shown in FIG.
4B shows a speed corresponding value corresponding to the conveyance speed of the recording medium M calculated by the recording head drive control unit 211.
4C, the CPU 31 outputs the ink ejection target position on the recording medium M to the recording head drive controller 211 at every timing (ejection reference timing) when the ink ejection target position moves to a predetermined ejection reference position in the transport direction. A discharge reference signal is shown.
In FIG. 4D, an ejection start signal indicating the ejection start timing of the ink is shown.
The outline of the adjustment method of the ink discharge timing of this embodiment is as follows. That is, first, based on the pulse signal of the rotary encoder 15 (A in FIG. 4), the conveyance speed of the recording medium M (here, the speed correspondence value (speed correspondence information) corresponding to the conveyance speed) (B in FIG. 4) is obtained. Calculated. Also, a discharge reference signal (C in FIG. 4) is output at the discharge reference timing when the discharge target position of the recording medium M has moved to a predetermined discharge reference position. From the output timing of this discharge reference signal, the conveyance speed and discharge distance are set. An ejection start signal (D in FIG. 4) is generated at the timing when the delay time calculated based on the elapsed time. Then, supply of a drive signal to the recording head 212 is started at the generation timing of the discharge start signal, and ink is discharged from the nozzle 213.
The discharge reference position is determined in correspondence with each of the four head units 21, and each head unit 21 has a discharge reference in which the discharge target position of the recording medium M has moved to the discharge reference position corresponding to the head unit 21. Ink is ejected at the timing when the delay time elapses from the timing.
Hereinafter, a method for calculating the conveyance speed of the recording medium M and a method for setting the delay time of the ink ejection timing will be described.

First, a method for calculating the conveyance speed of the recording medium M will be described.
The conveyance speed of the recording medium M is based on the time required for detecting a number N (N = 70 in this embodiment) of pulse signals corresponding to the ink discharge interval in the conveyance direction from the rotary encoder 15. Calculated. Specifically, the reciprocal of the time required to detect N pulse signals is calculated as a speed corresponding value (speed corresponding information) corresponding to the conveyance speed of the recording medium M. This speed-corresponding value is proportional to the moving speed of the conveying belt 13, that is, the conveying speed of the recording medium M, during a period in which N pulse signals are detected (hereinafter also referred to as a pulse detecting period). Further, in the present embodiment, a speed correspondence value obtained by averaging and smoothing the speed correspondence values related to the latest predetermined number n (in this embodiment, n = 64) pulse detection periods is used.
The speed correspondence information is calculated by dividing the moving distance of the conveyor belt 13 corresponding to the N pulse signals by the time required to detect the N pulse signals, instead of the speed correspondence value. The conveyed conveyance speed itself may be used.
Also, table data in which the length of the pulse detection period is associated with the speed correspondence value (or transport speed) is prepared, and the speed correspondence information (with reference to the table data based on the detected length of the pulse detection period ( Alternatively, the conveyance speed) may be acquired.
The number N can be changed as appropriate according to the configuration of the rotary encoder 15 and the like. The number n can be appropriately changed according to the magnitude of variation in the calculation result of the conveyance speed for each pulse detection period, the variation amount of the conveyance speed per predetermined time, and the like.

As described above, in the ink jet recording apparatus 1, a speed corresponding value corresponding to the transport speed of the recording medium M is calculated for each pulse detection period. In FIG. 4B, speed corresponding values V1, V2 (> V1), V3 (> V2), V4 (in the time t1 to t5 for each pulse detection period in the period in which the conveyance speed of the recording medium M is increasing, respectively. > V3), V5 (> V4) are calculated.
The speed correspondence values are calculated by the four recording head drive control units 211 in the head unit 21, respectively. However, since the same pulse signal from the rotary encoder 15 is distributed and inputted to each recording head drive control unit 211, the calculation result of the conveyance speed is the same as long as there is no error in the calculation process.

Next, a method for setting the delay time of the ink ejection timing will be described.
The discharge reference signal shown in C of FIG. 4 is output from the CPU 31 to the recording head drive control unit 211 every time N pulse signals are detected from the rotary encoder 15. In other words, in the inkjet recording apparatus 1, the ejection target position of the recording medium M becomes the ejection reference position every time the conveying belt 13 moves (that is, the recording medium M is conveyed) by a distance corresponding to N pulse signals. It is supposed to be located. Note that the output timing of the discharge reference signal may be different from the calculation timing of the speed corresponding value described above.

When the conveyance speed of the recording medium M is constant, even when ink is ejected at the ejection reference timing when the ejection reference signal is output, the ink lands at equal intervals in the transport direction, so that an appropriate image recording is performed. It can be performed.
However, when the conveyance speed of the recording medium M is changing, the distance that the recording medium M moves from the time when the ink is ejected from the nozzle 213 until the ink reaches the recording medium M (movement distance after ejection) is conveyed. Varies with speed. For this reason, when ink is ejected at the ejection reference timing, the distance between the position of the recording medium M facing the ink ejection port of the nozzle 213 at the ejection reference timing and the position where the ink ejected from the nozzle 213 lands is the ejection distance. This differs depending on the conveyance speed at the reference timing. For example, when the transport speed of the recording medium M is increasing, the ink ejected from the Y, M, C, and K head units 21 at the same ejection target position of the recording medium M is the downstream head unit 21. That is, as the ink is ejected by the head unit 21 that ejects at a timing at which the transport speed is relatively large, the amount of deviation from the appropriate landing position increases. As a result, the landing positions of the inks ejected from the four-color head units 21 are shifted, resulting in poor image quality such as color mixing and color unevenness.
In particular, in the ink jet recording apparatus 1 that performs recording on a large recording medium M as in the present embodiment, since the interval between the head units 21 in the transport direction is large, there is a difference in transport speed at the position of each head unit 21. It becomes large and the above-mentioned trouble tends to be remarkable. In addition, the longer the ejection distance in the head unit 21, the greater the post-ejection movement distance.

Therefore, in the present embodiment, an appropriate delay time (the number of cycles of the clock signal) is calculated based on the conveyance speed (speed corresponding value) of the recording medium M and the discharge distance, and the delay is calculated from the timing at which the discharge reference signal is output. An ejection start signal that triggers the start of ink ejection is generated at the timing when the time has elapsed (D in FIG. 4). That is, the larger the conveyance correspondence value and the ejection distance, the shorter the distance between the position facing the ink ejection port of the nozzle 213 and the position where the ink lands is constant regardless of the conveyance speed at the output timing of the ejection reference signal. A delay time is set and a discharge start signal is generated. The delay time is calculated in each print head drive control unit 211 based on a function having the speed correspondence value and the ejection distance as variables.
4D, the discharge start signal is generated at the timing when the delay time T1 has elapsed from the discharge reference signal when the speed corresponding value is V1, and the delay time T2 from the discharge reference signal when the speed corresponding value is V2. A discharge start signal is generated at the timing when (<T1) has elapsed, and when the speed corresponding value is V3, the discharge start signal is generated at the timing when the delay time T3 (<T2) has elapsed from the discharge reference signal, and the speed response is generated. When the value is V4, a discharge start signal is generated at the timing when the delay time T4 (<T3) has elapsed from the discharge reference signal, and when the speed corresponding value is V5, the delay time T5 (<T4) A discharge start signal is generated at the timing when elapses.

When the ejection start signal is generated, the recording head drive control unit 211 starts supplying a driving signal from the drive circuit to the recording head 212 at the timing of the ejection start signal, and ejects ink from the nozzles 213 of the recording head 212. .

Subsequently, a control procedure by the CPU 31 of the image recording process executed by the inkjet recording apparatus 1 and a control procedure by the recording head drive control unit 211 of the ink ejection process will be described.

FIG. 5 is a flowchart showing a control procedure by the CPU 31 for image recording processing.
This image recording process is executed when a print job and image data are input from the external device 2 to the control unit 30 via the input / output interface 42.
Prior to the start of the image recording process, the CPU 31 outputs a drive signal from the transport driving unit 101 to the transport motor 14 to start the circular movement operation of the transport belt 13. Further, the CPU 31 outputs a control signal to the rotary encoder 15 to start output of a pulse signal to the control unit 30 and the recording head drive control unit 211. Further, the CPU 31 outputs a control signal to the recording head drive control unit 211 to start the calculation process of the speed corresponding value of the recording medium M for each pulse detection period.

When the image recording process is started, the CPU 31 acquires ejection distance information indicating the ejection distance in the print job to be executed (step S101). That is, the CPU 31 causes the operation display unit 41 to perform a display prompting the user to input discharge distance information, and acquires the discharge distance information input by the user's input operation to the operation display unit 41. The acquisition of the discharge distance information may be performed by acquiring the discharge distance information included in the print job data, for example.

CPU31 discriminate | determines whether input operation which changes the conveyance speed of the recording medium M was performed with respect to the operation display part 41 (step S102). When it is determined that the input operation has not been performed (“NO” in step S102), the CPU 31 shifts the process to step S104.

When it is determined that an input operation for changing the conveyance speed of the recording medium M has been performed ("YES" in step S102), the CPU 31 outputs a control signal to the conveyance drive unit 101, and the drive roller 11 Is rotated to a speed corresponding to the input transport speed (step S103: transport control step). The conveyance drive unit 101 gradually increases or decreases the rotation speed of the drive roller 11 over a predetermined time so that the rotation speed of the drive roller 11 becomes a specified speed.

The CPU 31 determines whether or not the discharge target position of the recording medium M is at a predetermined discharge reference position (that is, whether or not it is a discharge reference timing) (step S104). Here, the CPU 31 determines whether or not N pulse signals are output from the rotary encoder 15 after it is detected that the recording medium M has been transported to the ejection reference position most recently. When the first ink ejection is performed in the print job being executed, the CPU 31 detects a predetermined number of times from the rotary encoder 15 after the end of the recording medium M is detected or after the end of the previous print job. When the pulse signal is output, it is determined that the ejection target position of the recording medium M is at the ejection reference position.
When it is determined that the ejection target position of the recording medium M is not at the ejection reference position (“NO” in step S104), the CPU 31 shifts the process to step S102.

If it is determined that the ejection target position of the recording medium M is at the ejection reference position (“YES” in step S104), the CPU 31 outputs an ejection reference signal to the recording head drive control unit 211 to drive the recording head. Ink ejection processing is executed by the control unit 211 (step S105).

CPU 31 determines whether or not the recording of the image to be recorded has been completed (step S106). If it is determined that the image recording is not completed (“NO” in step S106), the CPU 31 shifts the process to step S102.

If it is determined that image recording has been completed (“YES” in step S106), the CPU 31 determines whether or not there is a new print job execution command (obtained) (step S107). . If it is determined that it has been acquired (“YES” in step S107), the CPU 31 shifts the processing to step S101.
If it is determined that there is no execution command for a new print job (“NO” in step S107), the CPU 31 ends the image recording process.

FIG. 6 is a flowchart showing a control procedure by the recording head drive control unit 211 in the ink ejection process.

When the ink ejection process is started, the recording head drive control unit 211 calculates the conveyance speed (speed corresponding value) of the recording medium M by the above-described method (step S201: speed correspondence information acquisition step).

The recording head drive control unit 211 calculates a delay time of the ink ejection timing based on the calculated speed correspondence value and the ejection distance acquired in step S101 of the image recording process (step S202).

The recording head drive control unit 211 generates an ejection start signal at the timing when the delay time elapses from the timing at which the ejection reference signal is input, and converts the image data from the drive circuit to the recording head 212 at the timing of the ejection start signal. Supply of the corresponding drive signal is started and ink is ejected from the nozzle 213 of the recording head 212 (step S203: recording step).
When the process of step S203 ends, the recording head drive control unit 211 ends the ink ejection process.

As described above, the inkjet recording apparatus 1 according to the present embodiment includes the recording unit 20 including the head unit 21 that ejects ink from the nozzles 213, the transport unit 10 that transports the recording medium M in a predetermined transport direction, and the rotary. The encoder 15, the CPU 31, and the recording head drive control unit 211 are provided, and the CPU 31 and the recording head drive control unit 211 are for the recording medium M that is transported by the transport unit 10 and is opposed to the ink ejection port of the nozzle 213. The ink is ejected from the nozzles 213 by the head unit 21 (recording control means), and the CPU 31 changes the conveyance speed of the recording medium M by the conveyance unit 10 (conveyance control means), and the rotary encoder 15 and the recording head drive control unit 211. Obtains a speed correspondence value related to the conveyance speed of the recording medium M (speed correspondence information acquisition procedure). ), The CPU 31 and the recording head drive control unit 211 move the ink ejection target position on the recording medium M to a predetermined ejection reference position in the conveyance direction at least during the period when the CPU 31 as the conveyance control unit changes the conveyance speed. Ink is ejected by the head unit 21 at a timing when a delay time determined based on the speed corresponding value related to the conveyance speed at the ejection reference timing has elapsed from the ejected reference timing. As a result, the distance between the position of the recording medium M facing the ink ejection port of the nozzle 213 at the ejection reference timing and the position where the ink ejected from the nozzle 213 lands varies depending on the conveyance speed of the recording medium M. Problems can be suppressed. Therefore, it is possible to appropriately record an image during a period in which the conveyance speed of the recording medium M is changed.

In addition, the recording unit 20 includes a plurality of head units 21 that are arranged at different positions in the transport direction, and the CPU 31 and the recording head drive control unit 211 are arranged such that the ejection target positions of the recording medium M are set to the plurality of head units 21. From a plurality of discharge reference timings respectively moved to a plurality of corresponding discharge reference positions, at a timing at which a delay time determined based on a speed correspondence value related to a conveyance speed at each of the plurality of discharge reference timings has passed, Ink is ejected by the head unit 21 corresponding to each ejection reference position (recording control means). According to such a configuration, ink can be landed from each of the plurality of head units 21 at an appropriate position related to the ejection reference position corresponding to the head unit 21. Thereby, it is possible to suppress variation in the landing positions of inks related to the same ejection target position of the recording medium M by the plurality of head units 21, and recording is performed by the plurality of head units 21 during a period in which the conveyance speed is changed. It is possible to suppress deterioration in image quality of the image.

Further, the delay time is determined based on the discharge distance and the conveyance speed in the Z direction between the recording medium M and the ink discharge port of the nozzle 213. According to such a configuration, when the ejection distance is changed, the ink can be landed at an appropriate landing position regardless of the conveyance speed of the recording medium M. Therefore, in the inkjet recording apparatus 1 in which the discharge distance can be changed, an image can be appropriately recorded during a period in which the conveyance speed of the recording medium M is changed.

Further, the transport unit 10 operates in a plurality of transport modes in which the recording medium M is transported at different transport speeds, and the CPU 31 changes the transport speed over a predetermined time when switching the transport mode of the transport unit 10. (Transport control means). Thereby, it is possible to continuously record an appropriate image before and after the transfer mode is switched.

Further, the conveying unit 10 conveys the recording medium M by placing the recording medium M on the conveying surface of the conveying belt 13 and moving the conveying belt 13, and the CPU 31 changes the moving speed of the conveying belt 13. As a result, the conveyance speed of the recording medium M is changed (conveyance control means), and the rotary encoder 15 outputs a predetermined detection signal for every predetermined amount of movement of the conveyance belt 13, and the rotary encoder 15 and the recording head drive control unit 211. Acquires a speed-corresponding value based on the time required to detect a predetermined number of detection signals (speed-corresponding information acquisition means). According to such a configuration, the speed corresponding value can be acquired with a simple configuration and processing without directly measuring the speed of the recording medium M.

Further, the CPU 31 and the recording head drive control unit 211 detect the ejection reference timing based on the detection signal of the rotary encoder 15 (recording control means). According to such a configuration, the ejection reference timing can be accurately detected with a simple configuration and processing.

Further, in the recording control method of the inkjet recording apparatus 1 according to the present embodiment, ink is supplied from the nozzle 213 by the head unit 21 to the recording medium M that is conveyed by the conveying unit 10 and is opposed to the ink discharge port of the nozzle 213. A recording step for discharging, a transport control step for changing the transport speed of the recording medium M by the transport unit 10, and a speed correspondence information acquiring step for acquiring a speed corresponding value related to the transport speed. In the recording step, at least the recording medium M From the ejection reference timing at which the ink ejection target position on the recording medium M has moved to a predetermined ejection reference position in the transportation direction during the period in which the transportation speed is changed, the speed correspondence information relating to the transportation speed at the ejection reference timing At the timing when the delay time determined based on 21 by ejecting the ink. Thereby, it is possible to appropriately record an image during a period in which the conveyance speed of the recording medium M is changed.

(Modification)
Then, the modification of the said embodiment is demonstrated. In this modification, the conveyance speed of the recording medium M is calculated at each of the four head units 21, and the delay time of the ink ejection timing is calculated based on the calculation result of the individual conveyance speeds in each head unit 21. This is different from the above embodiment. Hereinafter, differences from the above embodiment will be described.

Ideally, the conveyor belt 13 does not expand or contract during the revolving operation, but it is difficult to configure the conveyor belt 13 with a member that can be regarded as a rigid body, and it is inevitable that the conveyor belt 13 expands and contracts to some extent. In particular, in the ink jet recording apparatus 1 that performs recording on a large recording medium M, the amount of expansion and contraction of the transport belt 13 cannot be ignored with respect to the image recording resolution.
In addition, since the amount of expansion / contraction of the conveyance belt 13 usually varies depending on the position in the conveyance direction, the movement speed of the conveyance belt 13 in each of the four head units 21, that is, conveyance of the recording medium M due to the variation in the expansion / contraction amount. The speed may be different from each other. For this reason, when the ejection timing is adjusted by the conveyance speed calculated based on the detection signal from the single rotary encoder 15 as in the above embodiment, the deviation of the ink ejection position in each head unit 21 cannot be sufficiently suppressed. There is.
Therefore, in the inkjet recording apparatus 1 of the present modification, the conveyance speed of the recording medium M is calculated independently at a position facing each of the four head units 21 in the conveyance direction.

FIG. 7 is a diagram showing a schematic configuration of the inkjet recording apparatus 1 according to the present modification.
The ink jet recording apparatus 1 of this modification includes a belt encoder 18 instead of the rotary encoder 15. The belt encoder 18 is provided on the conveyor belt 13 and has a magnetic scale 182 arranged so that N poles and S poles alternately appear at predetermined intervals along the conveyance direction, and four magnetic poles for reading the magnetic pole surfaces of the magnetic scale 182. This is a magnetic linear encoder including a pickup 181. The four magnetic pickups 181 are respectively arranged at the positions of the four head units 21 in the transport direction. Each magnetic pickup 181 detects the change of the magnetic pole of the magnetic scale 182 at the position of the magnetic pickup 181 according to the circular movement of the transport belt 13 independently of each other, and outputs a pulse signal according to the detection result to the control unit. 30 and the recording head drive control unit 211.

The recording head drive control unit 211 of each head unit 21 calculates the conveyance speed of the recording medium M based on the pulse signal output from the magnetic pickup 181 corresponding to the head unit 21. In other words, in the inkjet recording apparatus 1 of this modification, the conveyance speed of the recording medium M at the position facing each head unit 21 in the conveyance direction is calculated separately, and each head unit 21 is independent from each other based on the calculation result. Then, the delay time of the ink ejection timing is calculated and ink is ejected.

In addition, it is good also as a structure using a rotary encoder instead of the structure using the belt encoder 18 as mentioned above. In this case, for example, driven rollers that rotate as the conveyor belt 13 moves are provided at the positions of the four head units 21 in the conveying direction, and a rotary encoder is attached to each of the four driven rollers. it can.

As described above, in the inkjet recording apparatus 1 according to the present modification, the rotary encoder 15 and the recording head drive control unit 211 have the conveyance speed of the recording medium M at the position facing each of the plurality of head units 21 in the conveyance direction. The CPU 31 and the recording head drive control unit 211 respectively acquire speed correspondence information (speed correspondence information acquisition means), and the recording medium at a position facing the head unit 21 from the ejection reference timing by each of the plurality of head units 21. Ink is ejected at the timing when a delay time determined based on the speed correspondence information relating to the M transport speed has elapsed (recording control means). According to such a configuration, in the case where the conveyance speeds of the recording medium M in each of the plurality of head units 21 are different from each other due to the variation in the amount of expansion / contraction of the conveyance belt 13, Ink can be discharged at an appropriate discharge timing according to the conveyance speed at the position. Therefore, an image can be recorded more appropriately during a period in which the conveyance speed of the recording medium M is changed.

The present invention is not limited to the above-described embodiments and modifications, and various modifications can be made.
For example, in the above-described embodiment and modification, the description has been made using the example in which the recording head drive control unit 211 calculates the delay time each time ink is ejected, but the present invention is not limited to this. For example, table data in which the delay time is associated with each possible combination of the conveyance speed and the discharge distance of the recording medium M is stored in the ROM 33 or the storage unit 34, and the delay time is acquired by referring to the table data. Also good.

Further, in the above-described embodiment and the modification, the description has been given using the example in which the recording head drive control unit 211 calculates the conveyance speed (speed correspondence information) and the delay time, but instead, at least the conveyance speed and the delay time are calculated. One may be calculated or acquired by the CPU 31.

In the embodiment and the modification described above, the example in which the delay time is calculated based on the conveyance speed and the discharge distance of the recording medium M has been described. However, the present invention is not limited to this. For example, when the discharge distance is constant or when a mechanism for adjusting the discharge distance to a predetermined value by moving the head unit 21 in the Z direction is provided, the delay time is based only on the conveyance speed of the recording medium M. May be calculated.

In the above-described embodiment and the modification, the description has been given using the example in which the delay time is calculated based on the calculated value of the conveyance speed and the discharge timing is adjusted even during the period in which the conveyance speed is not changed. It is not the purpose. For example, in a period in which the transport unit 10 operates in a predetermined transport mode and the transport speed of the recording medium M is constant, a delay determined in advance in association with the transport mode according to the transport speed of the transport mode. The discharge timing may be adjusted based on the time.

In the above-described embodiment and the modification, the speed correspondence information is acquired from the time when the predetermined number of detection signals are detected from the rotary encoder 15 (belt encoder 18). The speed correspondence information may be acquired from the number of detection signals output per time.

In the above-described embodiment and modification, the configuration in which the rotation amount of the driving roller 11 is detected by the rotary encoder 15 has been described as an example. Instead, the rotation amount of the driven roller 12 is detected by the rotary encoder 15. Alternatively, the rotation amount of the transport motor 14 may be detected.

In the above-described embodiment and the modification, the description has been given using the example in which the conveyance speed of the recording medium M is calculated based on the pulse signal output from the rotary encoder 15 (belt encoder 18). The conveyance speed may be detected by a device that directly measures the speed of the recording medium M or the conveyance belt 13 such as a Doppler velocimeter.

In the embodiment and the modification described above, the discharge reference signal is generated by the CPU 31 and output to the recording head drive control unit 211. However, the discharge reference signal is a pulse signal from the rotary encoder 15. Based on this, the print head drive control unit 211 may generate the print head.

In the above-described embodiment and modification, the delay time is calculated based on the discharge distance information input from the outside. However, instead of this, the ink discharge port of the nozzle 213, the recording medium M, and the like. A distance measuring unit that measures the distance may be provided, and the discharge distance measured by the distance measuring unit may be used.

In the above-described embodiment and the modification, the example in which the conveyance speed of the recording medium M is changed according to the input operation on the operation display unit 41 by the user has been described, but instead, according to a preprogrammed sequence. A mode in which the CPU 31 controls the change of the conveyance speed may be employed.

Moreover, although the said embodiment and the modification demonstrated using the example which conveys the recording medium M by the conveyance part 10 provided with the conveyance belt 13, it is not the meaning limited to this, For example, the conveyance part 10 is conveyance to rotate. The recording medium M may be held and conveyed on the outer peripheral surface of the drum. Further, for example, the roll paper may be conveyed while being brought into contact with and sliding on the surface of a member whose relative position to the head unit is fixed.

Although several embodiments of the present invention have been described, the scope of the present invention is not limited to the above-described embodiments, and includes the scope of the invention described in the claims and equivalents thereof. .

The present invention can be used for an ink jet recording apparatus and a recording control method for an ink jet recording apparatus.

DESCRIPTION OF SYMBOLS 1 Inkjet recording apparatus 2 External apparatus 10 Conveyance part 101 Conveyance drive part 11 Drive roller 12 Driven roller 13 Conveyance belt 14 Conveyance motor 15 Rotary encoder 16 Pressing roller 17 Peeling roller 18 Belt encoder 181 Magnetic pickup 182 Magnetic scale 20 Recording part 21 Head unit 211 Recording Head Drive Control Unit 212 Recording Head 213 Nozzle 30 Control Unit 31 CPU
32 RAM
33 ROM
34 Storage Unit 41 Operation Display Unit 42 Input / Output Interface 43 Bus M Recording Medium

Claims

A recording means having an ink discharge portion for discharging ink from the nozzle;
Conveying means for conveying the recording medium in a predetermined conveying direction;
Recording control means for causing ink to be ejected from the nozzles by the ink ejection unit to a recording medium conveyed by the conveyance means and facing the ink ejection ports of the nozzles;
A conveyance control means for changing the conveyance speed of the recording medium by the conveyance means;
Speed correspondence information obtaining means for obtaining speed correspondence information related to the transport speed;
With
The recording control means starts from an ejection reference timing at which an ink ejection target position on the recording medium has moved to a predetermined ejection reference position in the conveyance direction at least during a period when the conveyance control means is changing the conveyance speed. An ink jet recording apparatus, wherein the ink ejecting section ejects ink at a timing when a delay time determined based on the speed correspondence information related to the transport speed at the ejection reference timing has elapsed.
The recording unit includes a plurality of the ink ejection units arranged at different positions in the transport direction,
The recording control means includes a plurality of ejection reference timings based on a plurality of ejection reference timings in which the ejection target positions of the recording medium have moved to the plurality of ejection reference positions respectively corresponding to the plurality of ink ejection units. The ink is ejected by an ink ejection section corresponding to each of the plurality of ejection reference positions at a timing when a delay time determined based on the speed correspondence information relating to the transport speed in each of the plurality of ejection reference positions has elapsed. 2. An ink jet recording apparatus according to 1.
The speed correspondence information acquisition unit acquires the speed correspondence information for the conveyance speed of the recording medium at a position facing each of the plurality of ink ejection units in the conveyance direction,
The recording control means includes a delay time determined by each of the plurality of ink ejection units based on the speed correspondence information relating to the conveyance speed of the recording medium at a position facing the ink ejection unit from the ejection reference timing. The ink jet recording apparatus according to claim 2, wherein the ink is ejected at a timing when the time elapses.
The delay time is determined based on a distance between the recording medium and an ink discharge port of the nozzle in the ink discharge direction from the nozzle and the speed correspondence information. The ink jet recording apparatus according to any one of the above.
The transport means operates in a plurality of transport modes for transporting recording media at different transport speeds,
The inkjet recording apparatus according to any one of claims 1 to 4, wherein the conveyance control unit changes the conveyance speed over a predetermined time when the conveyance mode of the conveyance unit is switched.
The transport means transports the recording medium by placing the recording medium on the transport surface of the transport member and moving the transport member,
The transport control means changes the transport speed of the recording medium by changing the moving speed of the transport member,
The speed correspondence information acquisition unit includes a movement detection unit that outputs a predetermined detection signal for each predetermined amount of movement of the transport member, and is required for a predetermined number of times of detection of the detection signal or per predetermined time. The inkjet recording apparatus according to any one of claims 1 to 5, wherein the speed correspondence information is acquired based on the number of detected signals detected.
The inkjet recording apparatus according to claim 6, wherein the recording control unit detects the ejection reference timing based on the detection signal.
A recording control method for an ink jet recording apparatus comprising: a recording unit having an ink discharge unit that discharges ink from a nozzle; and a transport unit that transports a recording medium in a predetermined transport direction,
A recording step in which ink is ejected from the nozzles by the ink ejection unit with respect to a recording medium that is transported by the transport unit and is opposed to the ink ejection port of the nozzle;
A conveyance control step of changing a conveyance speed of the recording medium by the conveyance means;
A speed correspondence information obtaining step for obtaining speed correspondence information related to the transport speed;
Including
In the recording step, at least from a discharge reference timing at which an ink discharge target position on the recording medium has moved to a predetermined discharge reference position in the transport direction in a period in which the transport speed is changed in the transport control step. A recording control method for an ink jet recording apparatus, wherein ink is ejected by the ink ejecting section at a timing when a delay time determined based on the speed correspondence information relating to the transport speed at the ejection reference timing has elapsed.