JP2020066199A - Image forming apparatus and transport control method - Google Patents

Abstract

To provide an image forming apparatus that can more efficiently form an image, and a transport control method.SOLUTION: The image forming apparatus comprises: a transport part that moves a recording medium along a prescribed transport passage; a recording operation part that performs recording operation on the recording medium, across a recordable width of the recording medium in a direction crossing a direction along the transport passage, at a predetermined position on the transport passage; and a control part that controls transport operation and recording operation of the recording medium by the transport part. The control part, when causing the transport part to perform the transport operation at transport speed determined according to resolution of images to be formed and to form a plurality of images with different resolution, increases the transport speed to transport speed determined according to second resolution during recording operation related to a second image after recording operation related to a first image is finished if the second resolution of the second image to be formed subsequently to a first image is higher than first resolution of the first image to be formed.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an image forming apparatus and a conveyance control method.

  There is an image forming apparatus that forms an image by performing a recording operation on a recording medium. In recent years, in accordance with the demand for higher resolution, the frequency of operation of the recording operation unit has increased compared to the moving distance of the recording operation unit that performs the recording operation and the transport distance of the recording medium.

  In the image forming apparatus, it is possible to form an image with a plurality of types of resolutions by adjusting the operation frequency of the recording operation unit. However, there is an upper limit on the number of times the recording operation unit can operate per unit time (maximum frequency). In Patent Document 1, the conveyance speed is set so that the recording operation can be performed at the maximum resolution that can be set by the combination of the conveyance speed and the maximum frequency, and the operation frequency of the recording operation unit is changed according to the resolution of the formed image. Techniques for doing so are disclosed.

JP, 2003-48344, A

  However, in an image forming apparatus that forms an image while switching a plurality of resolutions, there is a problem that the image forming speed becomes unnecessarily slow when forming an image other than the maximum resolution, which is not efficient.

  An object of the present invention is to provide an image forming apparatus and a conveyance control method that can form an image more efficiently.

In order to achieve the above object, the invention according to claim 1 is
A transport unit that moves the recording medium along a predetermined transport path,
A recording operation unit that performs a recording operation on the recording medium over a recordable width of the recording medium in a direction intersecting a direction along the transportation path at a predetermined position on the transportation path,
A control unit that controls the recording medium conveyance operation by the conveyance unit and the recording operation;
Equipped with
When the control unit causes the transport unit to perform the transport operation at a transport speed determined according to the resolution of the image to be formed, and the plurality of images having different resolutions are to be formed, When the second resolution of the second image to be formed next to the first image is lower than the first resolution of the image, after the recording operation of the first image is completed, The image forming apparatus is characterized in that, during the recording operation for the second image, the conveyance speed is increased according to the second resolution.

According to a second aspect of the invention, in the image forming apparatus according to the first aspect,
The control unit controls the carrying operation so as to start increasing the carrying speed at a timing when the recording operation for the first image ends.

According to a third aspect of the invention, in the image forming apparatus according to the first or second aspect,
The transport speed is set to a maximum speed that can obtain the resolution of the image to be formed at the maximum drive frequency of the recording operation unit.

According to a fourth aspect of the invention, in the image forming apparatus according to any one of the first to third aspects,
The recording operation unit includes a plurality of recording units each having a different predetermined position,
The control unit increases the conveyance speed after the recording operation relating to the first image is completed by the recording unit having the predetermined position on the most downstream side of the conveyance path among the plurality of recording units. It is characterized by

According to a fifth aspect of the invention, in the image forming apparatus according to any one of the first to fourth aspects,
The control unit may cause the recording operation unit to form the plurality of images in the descending order of resolution when the control unit obtains a plurality of image formation commands having different resolutions.

According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects,
The control unit changes the transport speed so that an acceleration related to the change of the transport speed is equal to or less than a predetermined reference value.

The invention according to claim 7 is the image forming apparatus according to claim 6,
The control unit determines that the acceleration related to the transport speed in a second predetermined period from the start of the change of the transport speed to the end of the first predetermined period is after the first predetermined period and the first predetermined period. The conveyance speed is changed so as to be smaller than the acceleration before the predetermined period of 2.

The invention according to claim 8 is the image forming apparatus according to claim 7,
The control unit changes the transport speed so that the acceleration in the first predetermined period gradually increases and the acceleration in the second predetermined period gradually decreases.

According to a ninth aspect of the invention, in the image forming apparatus according to any one of the first to eighth aspects,
A drying unit is provided on the downstream side of the recording operation unit in the direction along the transport path,
The recording operation unit performs the recording operation by ejecting ink,
The drying unit is configured to dry the ink on the recording medium.

According to a tenth aspect of the invention, in the image forming apparatus according to any one of the first to ninth aspects,
It is characterized by comprising a medium supply unit for feeding the recording medium to the transport path.

Further, the invention according to claim 11 is
A transport unit that moves the recording medium along a predetermined transport path, and a recordable width of the recording medium in a direction intersecting a direction along the transport path at a predetermined position on the transport path with respect to the recording medium. A recording operation unit that performs a recording operation over the entire area, and a conveyance control method for an image forming apparatus,
A transport operation step of causing the transport unit to transport the recording medium at a transport speed determined according to the resolution of the image to be formed,
In the case of forming a plurality of images having different resolutions, the second resolution of the second image to be formed next to the first image is set to be higher than the first resolution of the first image to be formed. When it is lower, after the recording operation for the first image is completed, a speed change is performed during the recording operation for the second image to increase to the transport speed determined according to the second resolution. Step,
It is characterized by including.

  According to the present invention, there is an effect that an image can be formed more efficiently in the image forming apparatus.

It is a front view explaining the outline of the whole composition of an ink jet recording device. FIG. 6 is a bottom view showing an ink ejection surface of the head unit. FIG. 3 is a block diagram showing a functional configuration of an inkjet recording device. It is a figure which shows typically the time change of a resolution and conveyance speed. It is a flow chart which shows the control procedure of image recording control processing. It is a figure which shows the modification of the relationship regarding the resolution and conveyance speed which concern on image formation. 9 is a modification of the flowchart showing the control procedure of the image recording control process.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a front view illustrating the outline of the overall configuration of an inkjet recording apparatus 100 that is the image forming apparatus according to this embodiment.

  The inkjet recording apparatus 100 includes a medium supply unit 10, a recording operation unit 20, a drying unit 30, a medium discharge unit 40, and the like.

  The medium supply unit 10 includes a medium roll 11 and a delivery roller 12. A continuous recording medium M, such as roll paper or cloth, is wound around the medium roll 11. The medium roll 11 rotates at a speed according to the transport speed of the transport unit and sends the recording medium M to the transport path of the transport unit 70. The delivery roller 12 delivers the recording medium M to the transport unit 70 (recording operation unit 20) while stretching the recording medium M with an appropriate tension. The recording medium M is stretched for wrinkles, slack, and the like and sent horizontally to the recording operation unit 20.

  The recording operation unit 20 includes a drive roller 21, a driven roller 22, a conveyor belt 23, an encoder 24, a head unit 25 (recording unit), and the like.

  The drive roller 21 rotates according to the operation of a drive motor (not shown), and moves the conveyor belt 23 at a predetermined speed. The conveyor belt 23 is an endless (annular) belt member, and is stretched between the drive roller 21 and the driven roller 22. The conveyor belt 23 moves around in accordance with the rotation operation of the drive roller 21. Along with this, the recording medium M placed in a predetermined range on the outer peripheral surface (conveying surface) of the conveying belt 23 is conveyed and moved. The outer peripheral surface of the transport belt 23 may be coated with an adhesive or the like so that the recording medium M can adhere thereto. Further, a pressing roller (not shown) for adhering the recording medium M to the outer peripheral surface may be provided. The driven roller 22 rotates according to the circular movement of the transport belt 23.

  The encoder 24 is a rotary encoder and detects the rotation of the drive roller 21. The encoder 24 outputs a detection signal corresponding to the rotation direction to the control unit 50 (see FIG. 3) for each rotation of a predetermined angle.

  The head unit 25 moves the recording medium M in a width direction perpendicular (intersecting) to the recording medium M placed on the conveyor belt 23 in the conveying direction of the recording medium M (direction along the conveying path). It has a line head in which the recording element 20a (see FIG. 3) is provided over the recordable width (including the entire width or predetermined margins at both ends). The recording element 20a ejects ink to perform a recording operation in a strip shape (linear shape), and forms an image to be formed (two-dimensional image) in combination with the conveying operation. A plurality of head units 25, here four head units 25, may be sequentially provided at different positions (predetermined positions) in the transport direction. The head units 25 may be set to eject inks of different colors, and for example, inks of C (cyan), M (magenta), Y (yellow), and K (black) are ejected. To be done.

  The drying unit 30 dries and fixes the ink on the recording medium M downstream of the head unit 25 (recording operation unit 20) in the transport direction. The drying unit 30 includes conveyance rollers 31 and 32, a drying operation unit 35, and the like.

  The transport rollers 31 and 32 move the recording medium M sent from the recording operation unit 20 in the drying unit 30. The transport rollers 32 are two transport rollers that hold the recording medium M after the ink is dried. The transport roller 32 generates a force to pull the recording medium M, and the recording medium M is placed on the transport belt 23, in particular, the adhesive recording medium M is peeled from the transport belt 23 and drawn into the drying unit 30.

  The drying operation unit 35 performs an operation for drying and fixing the ink on the recording medium M. Here, the drying operation unit 35 performs heating and / or blowing to evaporate the water content of the water-based ink. Although not particularly limited, the drying unit 30 has a housing, and the drying operation unit 35 has a structure provided inside the housing to easily maintain the heat generated by the drying operation unit 35. . The internal air containing water vapor may be naturally discharged from the gap between the housings (including air blown by the wind generated by the movement of the recording medium M or the transport belt 23) or may be forcedly discharged by an exhaust fan or the like. Good.

  The medium discharging unit 40 includes a discharging roller 41, and shakes off the recording medium M sent from the drying unit 30 after the ink is dried and fixed to a tray (not shown) at the bottom. The discharged recording medium M may be appropriately sent to a post-processing device or the like to be cut.

FIG. 2 is a bottom view showing the ink ejection surface of the head unit 25.
Here, the head unit 25 has 16 recording heads 251, and a set of two recording heads 251 ejects ink to a predetermined range in the width direction. Each recording head 251 is provided with an array of nozzle openings 27a extending in the width direction at two locations in the transport direction. The nozzle openings 27a arranged at four locations in the recording heads 251 of each set are provided so as to be displaced by a uniform width in the width direction, and form a predetermined nozzle pitch arrangement as a whole. The number, size, and positional relationship of the nozzle openings 27a shown here are merely examples for explanation, and do not reflect the actual number, size, and positional relationship.

FIG. 3 is a block diagram showing the functional configuration of the inkjet recording apparatus 100.
The inkjet recording apparatus 100 includes a control unit 50, a storage unit 60, a conveyance unit 70, a communication unit 81, a display unit 82, and an operation reception unit 83, in addition to the recording operation unit 20 and the drying unit 30 described above. , Bus 90 and the like.

  The recording operation unit 20 includes a head drive unit 26. The head drive unit 26 outputs a drive signal for ejecting ink from each nozzle 27 of the head unit 25. The drive signal is output to, for example, an electromechanical conversion element 28 (piezoelectric element) that deforms an ink flow path (particularly, an ink chamber) communicating with the nozzle 27. The electromechanical conversion element 28 to which the voltage of the drive signal is applied is deformed, and the ink flow path is deformed according to the deformation, so that pressure fluctuation occurs in the ink in the ink flow path, and the ink droplets are ejected from the nozzle 27. Is discharged. The output frequency of the drive signal can be adjusted within a range equal to or lower than a predetermined maximum drive frequency. Each nozzle 27, the corresponding ink flow path, and the electromechanical conversion element 28 form a recording element 20a. The recording elements 20a do not have to be arranged in a line in the width direction as long as the ink can be ejected over the recordable width in the width direction.

  The drying unit 30 includes a drying operation driving unit 36. The drying operation drive unit 36 outputs a drive signal to the drying operation unit 35 to perform a heating operation, a blowing operation, or the like. Whether or not the heat generation operation is performed may be controlled by the control unit 50 according to the temperature inside the housing measured by a temperature sensor (not shown).

  The transport unit 70 includes a transport driving unit 76, an encoder 24, and the like. The transport drive unit 76 rotates the medium roll 11, the delivery roller 12, the drive roller 21, the transport roller 32, the discharge roller 41, and the like. As a result, the transport unit 70 performs a transport operation to move the recording medium M along a predetermined transport path. The rotation speed of each roller is synchronized according to the set transport speed, but may be finely adjusted under the control of the control unit 50. For example, the rotation speed of the medium roll 11 changes according to the radius of the recording medium M wound around. Further, these speeds can be changed according to the image quality accuracy of the recorded image by the head unit 25 and the like. Rewinding the recording medium M by synchronously rotating them in reverse (rotation speed is set to a negative value) usually takes time and is not easy. In particular, when an adhesive is applied to the outer peripheral surface of the transport belt 23, it is difficult to peel the recording medium M from the transport belt 23 and rewind the recording medium M on the upstream side in the transport direction. Further, the change of the transport speed cannot be instantaneously performed, and a predetermined change time is required.

  The control unit 50 includes a CPU 51 (Central Processing Unit), a RAM 52 (Random Access Memory), and the like, performs various arithmetic processes, and integrally controls the operation of each unit of the inkjet recording apparatus 100. The control unit 50 reads out and executes a control program or the like stored in the storage unit 60, and controls the carrying operation, the recording operation, the drying operation, and the like. The control unit 50 particularly adjusts the transport speed appropriately according to the resolution of the formed image.

  The storage unit 60 stores various programs, setting data, image data related to an image forming command, and the like. The storage unit 60 may include a volatile memory such as a DRAM and a non-volatile memory such as a flash memory, and may also include an auxiliary storage device such as an HDD (Hard Disk Drive). Image data of an image to be formed is stored in a volatile memory, subjected to high-speed processing, and erased after the processing is completed. Programs, setting data, and the like are stored in the nonvolatile memory and are retained regardless of whether or not power is supplied to the inkjet recording apparatus 100. The program includes a transport control program 61, and the setting data includes a resolution correspondence speed table 62. The resolution-corresponding speed table 62 stores the transport speeds of the transport unit 70 of the recording medium M which are predetermined corresponding to the resolution of the image to be formed.

  The communication unit 81 controls communication with an external device via a network. The communication unit 81 has, for example, a network card, and controls communication via a LAN (Local Area Network) or the like. The external device includes a computer such as a PC (Personal Computer) or an image forming server (print server), and receives image data and setting data of an image to be formed from these computers as job data together with an image forming instruction. . Further, the communication section 81 transmits status information of image formation (recording operation) under the control of the control section 50.

  The display unit 82 displays on the display screen under the control of the control unit 50. The display screen is not particularly limited, but for example, a liquid crystal display screen or the like is used. On the display screen, an operation acceptance menu and status display are displayed. In addition, the display unit 82 may include an LED lamp or the like, and may indicate whether or not power is being supplied or whether or not an abnormality has occurred.

  The operation receiving unit 83 receives an input operation from the outside and outputs an input signal according to the operation content. The operation reception unit 83 has, for example, a touch sensor, and operates as a touch panel by being provided over the display screen. Further, the operation receiving unit 83 may have a push button switch, a rocker switch, or the like for switching on / off of the main power supply.

Next, a recording operation and a conveying operation in the inkjet recording device 100 will be described.
In the inkjet recording apparatus 100, ink is ejected from each head unit 25 onto the recording medium M while moving the recording medium M along the transport path, thereby forming an image in a single pass. The resolution in the width direction of the image depends on the nozzle pitch of each head unit 25, and the resolution in the carrying direction is the interval in the carrying direction on the recording medium M on which the recording operation is performed in a band shape by the head unit 25. Therefore, it depends on the relationship between the transport speed of the recording medium M and the ink ejection frequency (that is, the output frequency of the drive signal). In the inkjet recording apparatus 100, as described above, the transport speed is defined for the resolution in the resolution correspondence speed table 62, and the ejection frequency is adjusted in the range of the maximum drive frequency or less, so that the resolution can be adjusted according to the resolution. Image formation (recording operation) is performed at different intervals.

  In order to increase the image forming efficiency without reducing the image forming speed, it is preferable that the conveying speed is high. On the other hand, the ejection frequency has an upper limit (maximum drive frequency) that can generate a pressure wave capable of ejecting ink suitably according to the characteristics of the ink, the shape of the ink flow path, etc. After that, it is not possible to obtain an image with a resolution higher than the maximum drive frequency. Here, the ejection frequency is the maximum drive frequency (if the settable frequency is a discrete value, the maximum frequency among them may be used. If it can be set continuously, the ejection frequency is actually generated. It is possible to obtain an image with the desired resolution while keeping the carrier speed at a maximum frequency that does not exceed the theoretical maximum drive frequency in consideration of blurring, error, margin, etc.) or slightly lower than this. Maximum speed (If the speed that can be set is a discrete value, the maximum speed is acceptable. If continuously settable, consider possible shake, error, margin, etc. with respect to the setting. Then, the maximum speed that does not exceed the theoretical maximum speed may be used) or adjusted to a speed slightly lower than this. That is, the higher the resolution, the smaller the transport speed is adjusted.

FIG. 4 is a diagram schematically showing temporal changes in resolution and transport speed.
In the case where a plurality of images having different resolutions, here, a high-resolution image, a low-resolution image, and a medium-resolution image are sequentially formed, as shown in FIG. 4A, depending on the conveyance position of the recording medium M. As a result, the formation period of each image is shifted among the plurality of head units 25. That is, the formation start timing ul of each image by the most downstream head unit 25 is delayed with respect to the formation start timing uf of each image by the most upstream head unit 25 in accordance with the transport speed.

  In this inkjet recording apparatus 100, as shown in FIG. 4B, when the image formation of a relatively high resolution is changed to the image formation of a low resolution, the head unit 25 on the most downstream side is a formation target first. After the formation of the high-resolution image (first image) is completed, the second image can be formed while forming the low-resolution image (second image) to be formed next. Speed up. On the other hand, when the image formation on the relatively low resolution side is shifted to the image formation on the high resolution side, before the head unit 25 on the most upstream side shifts to the high resolution side image formation, The conveyance speed is changed in advance during image formation on the low resolution side so that the reduction to the conveyance speed at which the next image can be formed is completed.

  The time required for speed change depends on the speed difference. Further, since the conveyance speed during image formation on the low resolution side varies depending on the resolution, the length (predetermined distance) of the remaining image according to the remaining time until the image formation by the head unit 25 on the upstream side is completed is naturally. different. Therefore, when the timing to start the reduction of the transport speed is acquired at the position on the recording medium M, the length of the remaining image may be calculated in advance based on these conditions. As a result, it is not necessary to provide a blank space between the first image and the second image on the recording medium M (a necessary minute space may be provided), and a blank space is taken. There is no need for waiting time between them.

  At this time, if the speed change (acceleration) per unit time is too large, a large force is applied to each part of the inkjet recording apparatus 100, and a problem such as blurring of a formed image is likely to occur. In addition, since the ink ejection timing is determined based on the detection signal of the encoder 24 (that is, the conveyance speed), if there is a velocity change (acceleration) after the latest detection signal, the ink ejection timing, that is, the landing time The position is misaligned. Therefore, the transport speed is gradually changed without being rapidly changed in a short time. That is, the acceleration (the amount of change in speed within the unit time when the speed change is discretely performed for each unit time) is kept within a predetermined upper limit value (less than or equal to a reference value). The reference value may be set according to an allowable amount of the deviation of the landing position (such as an upper limit of the deviation with respect to the interval in the original transport direction). As a result, the landing position does not deviate more than the distance corresponding to the upper limit value. Further, by setting the upper limit value on the basis of the allowable amount of the landing position shift, the image quality is not adversely affected.

  Further, as shown in FIGS. 4 (c) and 4 (d), from the start to the predetermined period t1 (first predetermined period) and the end so as not to cause a rapid speed change at the start and end of the speed change. The acceleration (speed change) in the predetermined period t3 (second predetermined period) of the above is the acceleration (speed change) in the period t2 during the speed change other than these (that is, the period after the predetermined period t1 and before the predetermined period t3). By making it smaller than this, the speed change can be started and ended gradually. Here, the magnitude of the acceleration (absolute value) is gradually increased in the first predetermined period, and the magnitude of the acceleration is gradually decreased in the second predetermined period, so that the speed changes smoothly.

  FIG. 5 is a flowchart showing a control procedure by the control unit 50 of the image recording control process executed by the inkjet recording apparatus 100. The image recording control process is started when an image forming command is acquired from the outside via the communication unit 81 or via the operation receiving unit 83. Multiple instructions may be acquired. When accepting a command via the operation acceptance unit 83, image data of each resolution may be stored in the storage unit 60 in advance.

  When the image recording control process is started, the control unit 50 (CPU 51) acquires image data and setting data related to the image forming command (step S101). The control unit 50 acquires the resolution of the image data, acquires the transportation speed corresponding to the resolution from the resolution correspondence speed table 62, and causes the transportation unit 70 to start the transportation operation of the recording medium M at the acquired transportation speed. (Step S102; conveyance operation step). The control unit 50 causes the recording operation unit 20 to start the recording operation (step S103).

  The control unit 50 operates the transport unit 70 based on the transport speed (resolution) that is currently set, and determines whether or not image formation based on the last image data in the acquired image formation command is being performed. It is determined (step S104). When it is determined that the image formation based on the last image data is not being performed (“NO” in step S104), the control unit 50 determines that the image data of the next image of the formation target is the image of the image of the current formation target. It is determined whether the resolution is lower than the data (including the same resolution) (step S105). When it is determined that the resolution is lower (“YES” in step S105), the control unit 50 determines whether or not the image formation of the current target image by the most downstream head unit 25 is completed. Is determined (step S106). When it is determined that the processing is not completed (“NO” in step S106), the control unit 50 repeats the process of step S106.

  When it is determined that the image formation of the current target image is completed (“YES” in step S106), the control unit 50 sets the transport speed of the next target image based on the resolution correspondence speed table 62. A process for increasing the speed according to the resolution is performed (step S107; speed changing step). The speed change is a gradual change as described above. The control unit 50 lowers the ink ejection frequency once according to the change of the resolution, and then raises it again according to the change (increase) of the transport speed. When the resolution is not changed, the change amount of the transport speed is zero, and the control unit 50 immediately ends the process of step S107. Then, the process of the control unit 50 returns to step S104.

  In the determination processing of step S105, when it is determined that the image data of the next formation target does not have a lower resolution (higher resolution) than the image data of the current formation target (“NO” in step S105). ), The control unit 50 determines whether or not the image formation (recording operation) is performed at a position that is a predetermined distance before the position where the image formation of the current formation target image by the most upstream head unit 25 ends. S116). When it is determined that the recording operation is not yet performed at the position before the predetermined distance (“NO” in step S116), the control unit 50 repeats the process of step S116.

  When it is determined that the image formation (recording operation) is performed at a position that is a predetermined distance before the position at which the formation of the current image to be formed ends (“YES” in step S116), the control unit 50 proceeds to the next step. Based on the resolution of the image to be formed and the resolution-corresponding speed table 62, a process of reducing the transport speed to a speed corresponding to the next resolution is performed (step S117). Since the decrease of the transport speed is started at the position before the predetermined distance, the decrease of the transport speed is ended immediately before the image formation of the next target image is started by the head unit 25 on the most upstream side. Then, the process of the control unit 50 returns to step S104.

  When it is determined in the determination process of step S104 that the current image to be formed (image formation) is based on the last image data (“YES” in step S104), the control unit 50 determines It is determined whether or not the image formation of the target image by the head unit 25 is completed (step S121). When it is determined that the processing is not completed (“NO” in step S121), the control unit 50 repeats the process of step S121. When it is determined that the image formation of the target image is completed by the most downstream head unit 25 (“YES” in step S121), the control unit 50 stops the transport operation by the transport unit 70 (step S122). . If necessary, the control unit 50 may continue the conveyance of the recording medium M after the last image is formed until the image is ejected to the medium ejection unit 40.

FIG. 6 is a diagram showing a modified example of the relationship between the resolution related to image formation and the transport speed.
Here, the order of image formation is arranged so that the resolution monotonically decreases, and accordingly, the transport speed monotonically increases. When it is possible to rearrange the images in descending order of resolution (in descending order of resolution) to perform image formation when a plurality of commands related to image formation with different resolutions are acquired, the image formation is performed in descending order in this way. By doing so, it is standardized that all changes in the transport speed are performed after the image formation by the downstream head unit 25 is completed.

  FIG. 7 is a modification of the flowchart showing the control procedure by the control unit 50 of the image recording control process. This modified example corresponds to that shown in FIG. 6, the process of step S151 is added to the image recording control process shown in FIG. 5, and the processes of steps S105, S116, S117, and S121 are deleted. In addition, the order of the processes after step S104 is partially changed. The same processing contents are designated by the same reference numerals and detailed description thereof will be omitted.

  After the processing of step S101, the control unit 50 (CPU 51) sorts the acquired plurality of image data to be formed in descending order by resolution, and determines the order of image formation (step S151). Then, the processing of the control unit 50 moves to step S102.

  After the processing of step S103, the control unit 50 proceeds to the processing of step S106, and determines whether or not the image forming operation of the current formation target is completed by the most downstream head unit 25 (step S106). When it is determined that the image forming operation by the most downstream head unit 25 is completed (“YES” in step S106), the process of the control unit 50 proceeds to step S104.

  When it is determined in the determination processing of step S104 that the formation target image related to the current image formation corresponds to the last image data (“YES” in step S104), the processing of the control unit is The process moves to S122. When it is determined that the image data does not correspond to the last image data (“NO” in step S104), the process of the control unit 50 proceeds to step S107. In the process of step S107, the control unit 50 increases the transport speed, and then returns the process to step S106.

As described above, in the inkjet recording apparatus 100, which is the present embodiment of the image forming apparatus, the transport unit 70 that moves the recording medium M along the predetermined transport path, and the predetermined location on the transport path with respect to the recording medium M. A recording operation unit 20 that performs a recording operation by a recording element 20a that is provided over a recordable width of the recording medium M in a direction that intersects the direction along the conveyance path at a position, and a conveyance operation of the recording medium M by the conveyance unit 70. And a control unit 50 that controls the recording operation. The control unit 50 causes the transport unit 70 to perform the transport operation at a transport speed determined according to the resolution of the image to be formed, and when forming a plurality of images having different resolutions, the first image to be formed. When the second resolution of the second image to be formed next is lower than the first resolution of the first image, the recording operation for the second image is completed after the recording operation for the first image is completed. Increase the transport speed.
As described above, by changing the transport speed according to the resolution, it is possible to determine that the image recording operation is performed in the vicinity of the upper limit drive frequency, so that it does not take more time than necessary. Therefore, the inkjet recording apparatus 100 can efficiently form an image. Further, by performing the recording operation while changing the conveying speed, it is not necessary to stop the recording operation while changing the conveying speed, and unnecessary waiting time is not required. Moreover, since the recording medium M is not moved unnecessarily during the waiting time, an unnecessary margin is not created on the recording medium M and the recording medium M is not wasted.
In particular, when a small number of sample images are formed while switching at a plurality of resolutions, the time required for switching, the margin of the recording medium at the time of switching, and the like may be larger than the sample image forming time and the consumption of the recording medium. It was large in the past, but these can be efficiently suppressed and removed.

  Further, the control unit 50 controls the carrying operation so as to start increasing the carrying speed at the timing when the recording operation for the high-precision image ends. As a result, the conveyance speed is not maintained slower than necessary, so that the conveyance speed can be quickly increased without waste and the image can be formed more efficiently.

  The transport speed is set to the maximum speed at which the resolution of the image to be formed can be obtained at the maximum drive frequency of the recording operation unit 20. That is, since the conveyance speed is set so that the image having the desired resolution can be obtained at the highest speed in the inkjet recording apparatus 100, the image formation can be performed with maximum efficiency.

  Further, the recording operation unit 20 has a plurality of head units 25 at different positions on the transport path where the recording operation is performed. After the recording operation for the high-resolution first image is completed by the head unit 25 on the downstream side, the transport speed is increased. In other words, since the transport speed is increased after the recording operation at the resolution for which the transport speed needs to be lowered is completed, an image is appropriately formed at the transport speed that does not cause any problem in image formation at each resolution. . Further, when the image formation by the head unit 25 on the most downstream side is completed and then the image formation by the head unit 25 on the most upstream side is started after the conveyance speed is converted, the time lag is very large, and Although the margin of the recording medium becomes long, these can be eliminated, so that the efficiency of image formation is greatly improved.

In addition, when the control unit 50 receives a command to form a plurality of images with different resolutions, the recording operation unit 20 causes the recording operation unit 20 to form a plurality of images in descending order of resolution.
In this way, since images of a plurality of resolutions are sequentially formed in the direction of decreasing the resolution, the transport speed change timing according to the resolution change can be easily performed based on only the operation of the head unit 25 on the most downstream side. It is set and the control becomes simple.

  Further, the control unit 50 changes the transport speed so that the acceleration related to the change of the transport speed becomes equal to or less than a predetermined reference value. As a result, it is possible to avoid applying a force that is too strong as compared with the structure of the inkjet recording apparatus 100, and it is possible to keep the displacement of the ink ejection position due to abrupt acceleration / deceleration within a range that does not cause deterioration of image quality. Further, the speed changes of the front and rear drying unit 30 and the medium supply unit 10 can be easily interlocked, and the recording medium M can be stably transported.

  Further, the control unit 50 determines that the acceleration related to the transport speed in the second predetermined period t3 from the start of the change of the transport speed to the end of the first predetermined period t1 is after the first predetermined period t1. Further, the conveyance speed is changed so as to be smaller than the acceleration in the period t2 before the second predetermined period t3. In this way, by providing the switching portion where the speed change is small at the start and end of the speed change, it is possible to more stably maintain the image quality during the change of the transport speed.

  Further, the control unit 50 changes the transport speed so that the acceleration in the first predetermined period gradually increases and the acceleration in the second predetermined period gradually decreases. That is, since the speed change is performed more smoothly, the inkjet recording apparatus 100 can better maintain the image quality during the change of the conveyance speed.

  In addition, a drying unit 30 is provided on the downstream side of the recording operation unit 20 in the direction along the transport path. The recording operation unit 20 performs the recording operation by ejecting ink from the recording element 20a. The ink on the recording medium M is dried. As described above, in the case where the inkjet recording apparatus 100 has a configuration related to drying after image formation, it is difficult to move the continuous recording medium M in the reverse direction, and it takes time and labor. By changing the speed so as not to generate an unnecessary margin, it is possible to easily and efficiently waste the recording medium. In addition, it is possible to prevent the consumption of time by sandwiching the operation of reversing.

  In addition, the recording medium M is provided with a medium supply unit 10 that supplies the recording medium M to the conveyance path. In this way, it is difficult and time-consuming to reversely move the recording medium M that has been advanced once, especially when a continuous recording medium M is sent out from the medium supplying unit 10 separately from the transport unit 70. By changing the transport speed while transporting and not generating an unnecessary margin, it is possible to more efficiently and efficiently waste the recording medium.

Further, the transport control method according to the present embodiment is configured such that a transport operation step that causes the transport unit 70 to transport the recording medium M at a transport speed determined according to the resolution of an image to be formed, and a plurality of images having different resolutions. When forming, when the second resolution of the second image to be formed next to the first image is lower than the first resolution of the first image to be formed, the first image And a speed changing step of increasing the transport speed determined according to the second resolution during the recording operation related to the second image after the recording operation related to (3) is completed.
By using such a conveyance control method, it is possible to determine that the image recording operation is performed near the upper limit drive frequency for images of any resolution, so that it does not take more time than necessary. . Therefore, it is possible to efficiently form an image. Further, by performing the recording operation while changing the conveying speed, it is not necessary to stop the recording operation while changing the conveying speed, and unnecessary waiting time is not required. Further, since it is possible to eliminate unnecessary movement of the recording medium M during the waiting time, an unnecessary margin is not created on the recording medium M, and the recording medium M is not wasted.

The present invention is not limited to the above embodiment, and various modifications can be made.
For example, in the above-described embodiment, the ink ejection operation is performed at the maximum drive frequency, and the control is performed such that the conveyance is performed at the maximum speed according to the desired resolution, but the conveyance speed is slower than this. May be. For example, the upper limit transportation speed may be separately determined according to the structural strength of the inkjet recording apparatus 100, and the transportation operation may be performed at this transportation speed or less. In addition, if the image quality cannot be obtained at a certain level by ejecting ink at the maximum drive frequency, ink is ejected at a drive frequency lower than the maximum drive frequency depending on the high-resolution image formation or the image quality setting separately. There may be cases where

  Further, in the above-described embodiment, the four head units 25 for respectively ejecting CMYK four color inks are provided, but the present invention is not limited to this. One head unit 25 may be provided, or two or more arbitrary head units 25 may be provided.

  Further, in the above-described embodiment, the inkjet recording apparatus 100 includes the drying unit 30 that dries the recording medium M on which the ink has landed due to heat and / or air flow, but may not include the drying unit 30. In addition, another method, for example, in the case of using ink that is cured by ultraviolet rays or the like, an irradiation unit that irradiates ultraviolet rays may be provided instead of the drying unit 30. Further, the disposition of the drying operation unit 35 inside the housing may be appropriately determined. Alternatively, the drying operation unit 35 may be provided outside the housing, and the heated dry air may be sent into the housing by a fan via a pipe.

  Further, the configuration relating to the supply and discharge of the recording medium M to the transport path is not limited to the one described in the above embodiment.

  Further, in the above-described embodiment, all the images to be image-formed are first acquired, but the image data to be formed next may be added during the image formation. In this case, it suffices that the image data be acquired within a range in time for the start of the process of changing the transport speed. Further, the image data set as the image forming target may be sequentially re-sorted in the order of resolution.

  Further, in the above-described embodiment, the image data of each resolution is described as being acquired and stored externally, but one type of original data (vector image data, etc.) is acquired and stored, and a plurality of set data is set. The bitmap image (raster image) corresponding to the resolution of may be generated by the control unit 50.

Further, in the above embodiment, the image forming apparatus that performs the recording operation of ejecting ink has been described, but the present invention is not limited to this. A recording operation is performed within a predetermined maximum drive frequency by arranging other types of recording elements such as an LED printer, or by another mechanism that forms an image extending in the width direction row by row. Good.
In addition, the specific details such as the configuration, the structure, the control content and the procedure thereof described in the above-described embodiment can be appropriately changed without departing from the spirit of the present invention.

10 medium feeding section 11 medium roll 12 sending roller 20 recording operation section 20a recording element 21 driving roller 22 driven roller 23 transport belt 24 encoder 25 head unit 251 recording head 26 head driving section 27 nozzle 27a nozzle opening 28 electromechanical conversion element 30 dry Part 31 Conveyor Roller 32 Conveyor Roller 35 Drying Operation Unit 36 Drying Operation Drive Unit 40 Medium Ejection Unit 41 Ejection Roller 50 Control Unit 51 CPU
52 RAM
60 Storage Unit 61 Transport Control Program 62 Resolution Corresponding Speed Table 70 Transport Unit 76 Transport Drive Unit 81 Communication Unit 82 Display Unit 83 Operation Receiving Unit 90 Bus 100 Inkjet Recording Device M Recording Medium

Claims (11)

A transport unit that moves the recording medium along a predetermined transport path,
A recording operation unit that performs a recording operation on the recording medium over a recordable width of the recording medium in a direction intersecting a direction along the transportation path at a predetermined position on the transportation path,
A control unit that controls the recording medium conveyance operation by the conveyance unit and the recording operation;
Equipped with
When the control unit causes the transport unit to perform the transport operation at a transport speed determined according to the resolution of the image to be formed, and the plurality of images having different resolutions are to be formed, When the second resolution of the second image to be formed next to the first image is lower than the first resolution of the image, after the recording operation of the first image is completed, An image forming apparatus, characterized in that during the recording operation for the second image, the conveyance speed is set to a value determined according to the second resolution.   The image forming apparatus according to claim 1, wherein the control unit controls the carrying operation so as to start increasing the carrying speed at a timing when the recording operation for the first image ends.   3. The image forming apparatus according to claim 1, wherein the transport speed is set to a maximum speed at which the resolution of the image to be formed can be obtained at the maximum drive frequency of the recording operation unit. The recording operation unit includes a plurality of recording units each having a different predetermined position,
The control unit increases the conveyance speed after the recording operation relating to the first image is completed by the recording unit having the predetermined position on the most downstream side of the conveyance path among the plurality of recording units. The image forming apparatus according to claim 1, further comprising:   5. The control unit causes the recording operation unit to form the plurality of images in descending order of resolution when the control unit obtains a plurality of image formation commands having different resolutions. The image forming apparatus according to item 1.   The image forming apparatus according to claim 1, wherein the control unit changes the transport speed so that an acceleration related to the change of the transport speed is equal to or less than a predetermined reference value. .   The control unit determines that the acceleration related to the transport speed in a second predetermined period from the start of the change of the transport speed to the end of the first predetermined period is after the first predetermined period and the first predetermined period. 7. The image forming apparatus according to claim 6, wherein the conveyance speed is changed so as to be smaller than the acceleration before the predetermined period of 2.   The image forming apparatus according to claim 7, wherein the control unit changes the conveyance speed so that the acceleration in the first predetermined period gradually increases and the acceleration in the second predetermined period gradually decreases. apparatus. A drying unit is provided on the downstream side of the recording operation unit in the direction along the transport path,
The recording operation unit performs the recording operation by ejecting ink,
The image forming apparatus according to claim 1, wherein the drying unit dries the ink on the recording medium.   The image forming apparatus according to any one of claims 1 to 9, further comprising a medium feeding unit that feeds the recording medium to the transport path. A transport unit that moves the recording medium along a predetermined transport path, and a recordable width of the recording medium in a direction intersecting a direction along the transport path at a predetermined position on the transport path with respect to the recording medium. A recording operation unit that performs a recording operation over the entire area, and a conveyance control method for an image forming apparatus,
A transport operation step of causing the transport unit to transport the recording medium at a transport speed determined according to the resolution of the image to be formed,
In the case of forming a plurality of images having different resolutions, the second resolution of the second image to be formed next to the first image is set to be higher than the first resolution of the first image to be formed. When it is lower, after the recording operation for the first image is completed, a speed change is performed during the recording operation for the second image to increase to the transport speed determined according to the second resolution. Step,
A transport control method comprising:

Images