JP7500975B2 - Image forming apparatus and temperature adjustment method - Google Patents

Description

The present invention relates to an image forming apparatus and a temperature adjustment method.

In recent years, inkjet image forming devices (hereinafter referred to as "inkjet image forming devices") that eject ink droplets from an inkjet head to form an image on a recording medium have become widely used as devices for forming (recording) high-definition images on various recording media such as paper and fabric.

In inkjet image forming devices, an intermediate transfer method has been proposed in which ink droplets ejected from an inkjet head are formed as an image on an intermediate transfer body such as an intermediate transfer belt, and the formed image is then transferred to a recording medium at a transfer nip (see, for example, Patent Document 1). With this intermediate transfer method, the amount of ink droplets can be reduced in advance, and the ink droplets can be crushed and expanded to the desired size (diameter) by the transfer pressure of the transfer nip. In other words, an image with high image coverage can be formed with a small amount of ink droplets.

In an inkjet image forming apparatus using an intermediate transfer method, in order to ensure transferability of an image to a recording medium, a configuration can be used in which an ink (containing a polymerizable monomer) that is cured (thickened) by active energy rays (e.g., ultraviolet rays) is used, and an intermediate transfer body that is transparent to active energy rays is used. In this configuration, the image (ink droplets) that are sandwiched and pressed (nipped) in the transfer nip are irradiated with active energy rays from the inner surface side of the intermediate transfer body to adjust the viscosity of the ink droplets. This makes it possible to improve transferability by ensuring a viscosity that does not crush the ink droplets while maintaining the wettability of the ink droplets that come into contact with the recording medium.

JP 2012-91342 A

In the inkjet image forming apparatus, the temperature of the intermediate transfer body needs to be controlled to a predetermined temperature in order to control the dot diameter on the recording medium to an appropriate size. However, when the ink droplets are cured (thickened) by irradiation with active energy rays, the temperature of the intermediate transfer body rises due to the amount of heat (curing reaction heat) generated during the curing reaction (polymerization reaction).

Here, if the amount of ink droplets ejected from the inkjet head (ink coverage rate) differs at multiple positions on the intermediate transfer body, the amount of heat generated during the curing reaction also differs. Specifically, at positions where the amount of ink droplets is large, the amount of heat generated during the curing reaction is large and the temperature rise of the intermediate transfer body is large, while at positions where the amount of ink droplets is small, the amount of heat generated during the curing reaction is small and the temperature rise of the intermediate transfer body is small. As a result, temperature unevenness occurs on the intermediate transfer body after transfer to the recording medium.

As a result, the next time ink droplets are ejected from the inkjet head, the diameter (dot diameter) of the ink droplets that land on the intermediate transfer body becomes uneven. Specifically, the diameter of the ink droplets that land on the intermediate transfer body becomes large at positions where the temperature is high, while the diameter of the ink droplets that land on the intermediate transfer body becomes small at positions where the temperature is low. If an image is transferred to the recording medium while the ink droplet diameter remains uneven, there is a problem in that the quality of the image is degraded.

The present invention aims to provide an image forming apparatus and a temperature adjustment method that can suppress deterioration in the quality of an image transferred to a recording medium.

The image forming apparatus according to the present invention comprises:
an image forming unit that forms an image on a transfer body by ejecting active energy ray-curable ink droplets from an inkjet head;
a curing unit that irradiates the ink droplets that have been discharged and landed on the transfer body with active energy rays to cure the ink droplets;
a temperature adjusting unit that adjusts the temperature of the transfer body based on a difference in the amount of heat generated when the ink droplets are cured;
a transfer section that transfers the image formed on the transfer body to a recording medium at a transfer nip;
a droplet amount acquisition unit that acquires an amount of the ink droplets on the transfer body at a plurality of positions on the transfer body,
The temperature adjustment unit is
a heating section provided downstream of the transfer nip in a moving direction of the transfer body and configured to heat the transfer body;
a cooling section provided downstream of the heating section in a moving direction of the transfer body and configured to cool the transfer body,
The heating section heats the transfer body so that the temperature of the transfer body after heating is uniform, and when the difference in the amount of ink droplets at the multiple positions is large, the heating amount of the transfer body is increased compared to when the difference is small.
Another image forming apparatus according to the present invention is
an image forming unit that forms an image on a transfer body by ejecting active energy ray-curable ink droplets from an inkjet head;
a curing unit that irradiates the ink droplets that have been discharged and landed on the transfer body with active energy rays to cure the ink droplets;
a temperature adjusting unit that adjusts the temperature of the transfer body based on a difference in the amount of heat generated when the ink droplets are cured;
a transfer section that transfers the image formed on the transfer body to a recording medium at a transfer nip;
a first temperature acquisition unit that acquires surface temperatures at a plurality of positions on the transfer body after the image is transferred and before heating by a heating unit;
The temperature adjustment unit is
a heating section provided downstream of the transfer nip in a moving direction of the transfer body and configured to heat the transfer body;
a cooling section provided downstream of the heating section in a moving direction of the transfer body and configured to cool the transfer body,
The heating section heats the transfer body so that the temperature of the transfer body after heating is uniform, and includes a plurality of heating elements that respectively heat multiple positions on the transfer body, and when there is a large difference in surface temperature at the multiple positions, the amount of heat applied to the transfer body is greater than when the difference is small.
Another image forming apparatus according to the present invention is
an image forming unit that forms an image on a transfer body by ejecting active energy ray-curable ink droplets from an inkjet head;
a curing unit that irradiates the ink droplets that have been discharged and landed on the transfer body with active energy rays to cure the ink droplets;
a temperature adjusting unit that adjusts the temperature of the transfer body based on a difference in the amount of heat generated when the ink droplets are cured;
a transfer section that transfers the image formed on the transfer body to a recording medium at a transfer nip;
a droplet amount acquisition unit that acquires an amount of the ink droplets on the transfer body at a plurality of positions on the transfer body,
The temperature adjustment unit is
a heating section provided downstream of the transfer nip in a moving direction of the transfer body and configured to heat the transfer body;
a cooling section provided downstream of the heating section in a moving direction of the transfer body and configured to cool the transfer body,
The heating section heats the transfer body so that the temperature of the transfer body after heating is uniform, and includes a plurality of heating elements that respectively heat a plurality of positions on the transfer body, and the amount of heat at positions where the amount of ink droplets is small is made greater than the amount of heat at positions where the amount of ink droplets is large.

The temperature adjustment method according to the present invention comprises the steps of:
An image is formed on a transfer body by ejecting active energy ray-curable ink droplets from an inkjet head;
irradiating the ink droplets discharged and landed on the transfer body with active energy rays to cure the ink droplets;
adjusting the temperature of the transfer body based on the difference in the amount of heat generated when the ink droplets are cured;
When the difference in the amount of ink droplets at the multiple positions is large, the amount of heat applied to the transfer body is increased compared to when the difference is small.
Another temperature control method according to the present invention includes:
An image is formed on a transfer body by ejecting active energy ray-curable ink droplets from an inkjet head;
irradiating the ink droplets discharged and landed on the transfer body with active energy rays to cure the ink droplets;
adjusting the temperature of the transfer body based on the difference in the amount of heat generated when the ink droplets are cured;
When the difference in surface temperature among a plurality of positions on the transfer body is large, the amount of heat applied to the transfer body is made larger than when the difference is small.
Another temperature control method according to the present invention includes:
An image is formed on a transfer body by ejecting active energy ray-curable ink droplets from an inkjet head;
irradiating the ink droplets discharged and landed on the transfer body with active energy rays to cure the ink droplets;
adjusting the temperature of the transfer body based on the difference in the amount of heat generated when the ink droplets are cured;
The amount of heat applied to the positions on the transfer body where the amount of ink droplets is small is set to be greater than the amount of heat applied to the positions on the transfer body where the amount of ink droplets is large.

The present invention makes it possible to suppress deterioration in the quality of the image transferred to the recording medium.

1 is a diagram illustrating an overall configuration of an inkjet image forming apparatus according to a first embodiment. 1 is a block diagram showing a main functional configuration of an inkjet image forming apparatus; 5 is a flowchart illustrating an example of a temperature adjustment operation of the inkjet image forming apparatus according to the first embodiment. 6A and 6B are diagrams illustrating a temperature adjustment operation for adjusting the surface temperature of a transfer belt. 6A and 6B are diagrams illustrating a temperature adjustment operation for adjusting the surface temperature of a transfer belt. FIG. 13 is a diagram illustrating an overall configuration of an inkjet image forming apparatus according to a second embodiment. 10 is a flowchart illustrating an example of a temperature adjustment operation of an inkjet image forming apparatus according to a second embodiment. 6A and 6B are diagrams illustrating a temperature adjustment operation for adjusting the surface temperature of a transfer belt. 6A and 6B are diagrams illustrating a temperature adjustment operation for adjusting the surface temperature of a transfer belt.

The inkjet image forming apparatus according to the present embodiment will be described in detail below with reference to the drawings. FIG. 1 is a diagram showing an outline of the overall configuration of an inkjet image forming apparatus 1 according to the first embodiment. FIG. 2 is a block diagram showing the main functional configuration of the inkjet image forming apparatus 1.

As shown in FIG. 1, the inkjet image forming apparatus 1 includes a head unit 10 equipped with an inkjet head 102 (see FIG. 2), a transfer belt 20, driven rollers 21 and 22 that rotatably stretch the transfer belt 20, a transfer roller 23 as a drive roller, a transport drum 24 that transports a recording medium P, and a control unit 40 (see FIG. 2) that controls the entire apparatus. The head unit 10 functions as the "image forming unit" of the present invention. The transfer belt 20 functions as the "transfer body" of the present invention. The control unit 40 functions as part of the "temperature adjustment unit" of the present invention, as the "droplet volume acquisition unit", the "first temperature acquisition unit" and the "second temperature acquisition unit".

The inkjet image forming device 1 also includes a first irradiation unit 25 that adjusts the viscosity of the ink droplets ejected onto the transfer belt 20, a second irradiation unit 26 that hardens the ink transferred to the recording medium P, a heating unit 27 that heats the surface of the transfer belt 20, a temperature detection unit 28 that detects the surface temperature of the transfer belt 20, a cooling unit 29 that cools the surface of the transfer belt 20, and a transport drive unit 51 that drives the transfer roller 23 and the transport drum 24.

Although not shown, the inkjet image forming device 1 includes a feed section that loads the recording medium P and feeds it to the transport drum 24, a discharge section that discharges the recording medium P onto which the image has been transferred to the downstream side in the transport direction of the transport drum 24, a display section that displays the status of the device, and the like. These are well-known configurations, so illustrations and descriptions of them will be omitted.

In addition, the recording medium P can be any of a variety of media, including paper such as plain paper or coated paper, as well as fabric or sheet-like resin, onto which ink droplets that land on the surface of the transfer belt 20 can be transferred.

The transfer belt 20 is stretched over driven rollers 21 and 22 arranged above and a transfer roller 23 (drive roller) arranged below, and rotates (moves) in the clockwise direction in FIG. 1 as the driving force of a transfer motor (not shown) of the transport drive unit 51 is transmitted to the transfer roller 23.

In this embodiment, a heat source (e.g., a heater) is provided inside the driven roller 22. The temperature of the heat source is controlled by the control unit 40. The heat source heats the driven roller 22, and as a result, the temperature of the transfer belt 20 is heated to a target temperature. The target temperature is a temperature that is set so that the diameter of the ink droplets ejected onto the transfer belt 20 is a predetermined diameter.

In this embodiment, the transfer belt 20 is an endless belt that is transparent to active energy rays and has a polyimide (PI) base material, a silicone rubber elastic layer, a reflective layer vapor-deposited with aluminum (Al), and a polypropylene (PP) surface layer laminated thereon.

The transfer roller 23 is, for example, a rubber roller with a diameter of 100 mm and a rubber surface layer thickness of 10 mm. The base material may be a resin material such as polyimide (PI) or a stainless steel material.

In the inkjet image forming apparatus 1, the transfer belt 20 is driven to rotate in a clockwise direction by driving the transfer motor based on a control signal from the control unit 40 and rotating the transfer roller 23 in the clockwise direction in FIG. 1. In this embodiment, under the control of the control unit 40, the rotation speed of the transfer roller 23 is controlled so that the transfer belt 20 rotates at a speed (printing speed) of 600 mm/sec.

The transport drum 24 holds the recording medium P on its cylindrical outer curved surface (transport surface) and rotates around an axis of rotation extending in a direction perpendicular to the plane of the drawing in FIG. 1 (hereinafter referred to as the "orthogonal direction"), thereby transporting the recording medium P in a transport direction along the transport surface.

Specifically, the transport drum 24 is equipped with a transport drum motor (not shown), and rotates in the counterclockwise direction in FIG. 1 when the transport drum motor is driven under the control of the control unit 40. In this embodiment, a large metal drum (e.g., a triple cylinder for a printing press) is used as the transport drum 24.

The transfer belt 20, transfer roller 23 and transport drum 24 described above have a width, i.e., axial length, of 800 mm.

The transfer roller 23 is disposed opposite the upper portion of the transport drum 24 and presses the transport drum 24 via the transfer belt 20. The transport drum 24 is pressed against the transfer roller 23 with the transfer belt 20 sandwiched therebetween, forming a transfer nip NP that transfers an image from the transfer belt 20 to the recording medium P. In this embodiment, the value of the transfer load or pressure contact force (hereinafter referred to as "transfer pressure") at the transfer nip NP is set to 80 N. The transfer belt 20, the transfer roller 23 and the transport drum 24 function as the "transfer section" of the present invention.

The head unit 10 ejects ink droplets onto the transfer belt 20 from nozzle openings provided on the ink ejection surface facing the transfer belt 20, forming an image on the transfer belt 20. The transport drum 24 transports the recording medium P so that the image formed on the transfer belt 20 is transferred to a predetermined position on the recording medium P at the transfer nip NP.

In the inkjet image forming device 1 of this embodiment, four head units 10 corresponding to the four colors of ink, yellow (Y), magenta (M), cyan (C), and black (K), are arranged at predetermined intervals from the upstream side in the rotation direction (movement direction) of the transfer belt 20 in the order of Y, M, C, and K.

Each head unit 10 is equipped with an inkjet head 102 (see FIG. 2). The inkjet head 102 is provided with a number of recording elements, each of which has a pressure chamber for storing ink, a piezoelectric element provided on the wall of the pressure chamber, and a nozzle. When a drive signal is input to deform the piezoelectric element, the pressure chamber is deformed by the deformation of the piezoelectric element, changing the pressure within the pressure chamber, and ink droplets are ejected from the nozzle connected to the pressure chamber.

The nozzle arrangement range in the orthogonal direction of the inkjet head 102 covers the orthogonal width of the area on the recording medium P transported by the transport drum 24 where an image is formed. The head unit 10 is used with its position fixed relative to the rotation axis of the transport drum 24 when forming an image. In other words, the inkjet image forming device 1 is a single-pass type inkjet image forming device.

In this embodiment, the ink ejected from the inkjet head 102 onto the transfer belt 20 is an ultraviolet-curable ink that is cured by exposure to ultraviolet light. More specifically, ink is used whose viscosity changes depending on the amount of active energy rays supplied to the transfer belt 20 (the amount of ultraviolet (UV) light output from the first irradiation unit 25). The greater the amount of active energy rays irradiated from the first irradiation unit 25, the higher the viscosity of the ink used. In other words, the image forming unit of this inkjet image forming device 1 employs a UV-curable inkjet method.

The first irradiation unit 25 is disposed on the inner peripheral surface side of the transfer belt 20, and under the control of the control unit 40, when the ink droplets ejected onto the transfer belt 20 are sandwiched and pressed (nipped) in the transfer nip NP, the first irradiation unit 25 irradiates the ink droplets with active energy rays to harden the ink droplets. The first irradiation unit 25 functions as the "hardening unit" of the present invention.

1, the dotted arrow extending from the first irradiation unit 25 indicates the active energy rays irradiated from the front side of the transfer belt 20 to the ink droplets ejected onto the transfer belt 20. In this embodiment, the first irradiation unit 25 includes a UV light source that outputs UV light with a wavelength of 395 nm, and the default value of the irradiation intensity for a normal print job is set to 3 mW/ ^cm2 .

The second irradiation unit 26 is disposed so as to irradiate the recording medium P transported downstream of the transfer nip NP with active energy rays, and fully cures the image (ink droplets) transferred by the transfer nip NP under the control of the control unit 40. In the present embodiment, the second irradiation unit 26 includes a UV light source that outputs UV light with a wavelength of 395 nm, and the default value of the irradiation intensity for a normal print job is set to 10 mW/ ^cm2 .

The heating unit 27 is a heating roller 27A that is disposed in contact with the surface of the transfer belt 20 downstream of the transfer nip NP in the movement direction (rotation direction) of the transfer belt 20 and heats the surface of the transfer belt 20 under the control of the control unit 40. The heating roller 27A has a width, i.e., an axial length, of 800 mm.

Heating roller 27A may be formed to a predetermined outer diameter, with the surface of a metal base such as aluminum covered with an elastic layer of silicone rubber or the like. Heating roller 27A is internally provided with a heating source such as a 300-350 W halogen lamp, and is configured to heat from the inside so that the surface temperature of heating roller 27A reaches a predetermined temperature.

The heating roller 27A uses a known mechanism to change the amount of heat applied to the surface of the transfer belt 20 by changing the contact pressure against the surface of the transfer belt 20 to change the contact area (heating nip width), by moving away from the surface of the transfer belt 20, or by changing the surface temperature of the heating roller 27A.

The heating unit 27 may heat the surface of the transfer belt 20 by blowing hot air or by irradiating infrared rays from an IR (infrared) heater.

The temperature detection unit 28 is a temperature sensor that is disposed facing the surface of the transfer belt 20 downstream of the heating unit 27 and upstream of the cooling unit 29 in the movement direction of the transfer belt 20, and detects the surface temperature of the transfer belt 20 after it has been heated by the heating unit 27. The temperature detection unit 28 outputs the detected surface temperature of the transfer belt 20 to the control unit 40.

The cooling unit 29 is a cooling roller 29A that is disposed in contact with the surface of the transfer belt 20 downstream of the temperature detection unit 28 and upstream of the driven roller 21 in the direction of movement of the transfer belt 20, and cools the surface of the transfer belt 20 under the control of the control unit 40. The cooling roller 29A has a width, i.e., an axial length, of 800 mm.

The cooling roller 29A is made of, for example, a metal with high thermal conductivity, and is cooled by a built-in heat pipe (not shown) or by cooling air sent into the roller by a fan (not shown), so that the surface temperature of the cooling roller is cooled from the inside to a predetermined temperature.

The cooling roller 29A uses a known mechanism to change the contact pressure against the surface of the transfer belt 20 to change the contact area (cooling nip width), to move away from the surface of the transfer belt 20, or to change the surface temperature of the cooling roller, thereby changing the amount of cooling applied to the surface of the transfer belt 20.

The cooling unit 29 may cool the surface of the transfer belt 20 by blowing cooling air from a cooling fan or by contacting a cooling element made of a Peltier element.

Next, other main functional configurations of the inkjet image forming device 1 will be described mainly with reference to FIG. 2. The inkjet image forming device 1 includes a head drive section 101 and an inkjet head 102 in the head unit 10, a control section 40, a transport drive section 51, and an input/output interface 52.

The head driving unit 101 outputs a driving signal to the recording element of the inkjet head 102 based on the control of the control unit 40 to deform the piezoelectric element in accordance with the image data at an appropriate timing, thereby ejecting an amount of ink droplets according to the pixel value of the image data from the nozzle of the inkjet head 102.

The control unit 40 has a CPU 41 (Central Processing Unit), a RAM 42 (Random Access Memory), a ROM 43 (Read Only Memory), and a memory unit 44.

The CPU 41 reads out various control programs and setting data stored in the ROM 43, stores them in the RAM 42, and executes the programs to perform various arithmetic processing. The CPU 41 also controls the overall operation of the inkjet image forming device 1.

RAM 42 provides working memory space for CPU 41 and stores temporary data. Note that RAM 42 may also include non-volatile memory.

The ROM 43 stores various control programs and setting data executed by the CPU 41. Note that instead of the ROM 43, a rewritable non-volatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory may be used.

The storage unit 44 stores print jobs (specifically, image formation instructions including various user setting information such as the number of copies) input from the external device 2 via the input/output interface 52, and image data related to the print jobs. As the storage unit 44, for example, a HDD (Hard Disk Drive) is used, and a DRAM (Dynamic Random Access Memory) may also be used in combination.

The transport drive unit 51 supplies a drive signal to the transport drum motor of the transport drum 24 based on a control signal supplied from the control unit 40, causing the transport drum 24 to rotate at a predetermined speed and timing. The transport drive unit 51 also supplies a drive signal to the motor of the transfer roller 23 based on a control signal supplied from the control unit 40, causing the transfer belt 20 to rotate at a predetermined speed and timing.

The input/output interface 52 mediates the transmission and reception of data between the external device 2 and the control unit 40. The input/output interface 52 is, for example, composed of any one of various serial interfaces, various parallel interfaces, or a combination of these.

The external device 2 is, for example, a personal computer, and supplies print jobs, image data, etc. to the control unit 40 via the input/output interface 52.

Incidentally, when the ink droplets are cured (thickened) by irradiation with active energy rays from the first irradiation section 25, the surface temperature of the transfer belt 20 increases due to the amount of heat (curing reaction heat) generated during the curing reaction (polymerization reaction).

Here, if the amount of ink droplets ejected from the inkjet head 102 (ink coverage rate) differs at multiple positions on the transfer belt 20, the amount of heat generated during the curing reaction also differs. Specifically, at positions where the amount of ink droplets is large, the amount of heat generated during the curing reaction is large and the amount of temperature rise on the transfer belt 20 is large, while at positions where the amount of ink droplets is small, the amount of heat generated during the curing reaction is small and the amount of temperature rise on the transfer belt 20 is small. As a result, temperature unevenness occurs on the transfer belt 20 after transfer to the recording medium P.

As a result, the next time ink droplets are ejected from the inkjet head 102, the diameter (dot diameter) of the ink droplets that land on the transfer belt 20 will be uneven. Specifically, the diameter of the ink droplets that land will be large at positions where the temperature is high, while the diameter of the ink droplets that land will be small at positions where the temperature is low. If an image is transferred to the recording medium P with uneven ink droplet diameters, the quality of the image will be reduced.

Therefore, in this embodiment, the inkjet image forming device 1 adjusts the temperature (surface temperature) of the transfer belt 20 based on the difference in the amount of heat generated when the ink droplets are cured by irradiation with active energy rays, through the operation of the heating unit 27, the cooling unit 29, and the control unit 40, which function as the "temperature adjustment unit" of the present invention.

An example of the temperature adjustment operation (corresponding to the "temperature adjustment method" of the present invention) of the inkjet image forming device 1 will be described with reference to the flowchart in Figure 3. Note that the process shown in Figure 3 is executed each time image data related to a print job is supplied to the control unit 40 and an amount of ink droplets corresponding to the pixel values of the image data is ejected from the nozzles of the inkjet head 102.

First, the control unit 40 acquires (estimates) the amount of ink droplets at multiple positions on the transfer belt 20 based on image data (step S100). Next, the control unit 40 determines whether the difference in the amount of ink droplets at the multiple positions acquired in step S100 is large (step S120).

If the result of the determination is that the difference in the amount of ink droplets is large (step S120, YES), the control unit 40 performs control to bring the heating roller 27A (heating unit 27) into contact with the surface of the transfer belt 20 (step S140). The heating roller 27A heats the surface of the transfer belt 20 to a target temperature equal to or greater than the temperature rise of the transfer belt 20 according to the amount of heat generated during the curing reaction of the ink droplets, so that the surface temperature of the transfer belt 20 after heating becomes uniform. Thereafter, the process transitions to step S180.

On the other hand, if the difference in the amount of ink droplets is not large, i.e., is small (step S120, NO), the control unit 40 performs control to separate the heating roller (heating unit 27) from the surface of the transfer belt 20 (step S160). In other words, the heating roller 27A does not heat the surface of the transfer belt 20. After that, the process proceeds to step S180.

As is clear from the difference in processing in steps S140 and S160, when the difference in the amount of ink droplets at multiple positions is large, the heating roller 27A heats the transfer belt 20 by a larger amount than when the difference is small.

In step S180, the control unit 40 obtains the surface temperature of the transfer belt 20 after it has been heated by the heating unit 27 as the detection result of the temperature detection unit 28.

Finally, the control unit 40 controls the cooling unit 29 (specifically, the surface temperature of the cooling roller 29A) to cool the surface of the transfer belt 20 based on the surface temperature acquired in step S180 (step S200). In this embodiment, when the difference between the surface temperature acquired in step S180 and the set temperature set as the surface temperature of the transfer belt 20 before the ink droplets are ejected is large, the cooling unit 29 increases the amount of cooling of the transfer belt 20 compared to when the difference is small. Completion of the process of step S200 causes the inkjet image forming apparatus 1 to end the process in FIG. 3.

Next, referring to Figure 4, a specific example of a temperature adjustment operation for adjusting the surface temperature of the transfer belt 20 will be described. Figure 4A is a view of the transfer belt 20 seen from below, and shows how the transfer belt 20 passes through the heating unit 27, temperature detection unit 28, and cooling unit 29 after transfer when there is a large difference in the amount of ink droplets ejected from the nozzles of the inkjet head 102 in a direction perpendicular to the movement direction of the transfer belt 20. In Figure 4A, the amount of ink droplets ejected onto area 60 on the transfer belt 20 is large, and the amount of ink droplets ejected onto area 62 is small.

Figure 4B shows the change in temperature over time on the transfer belt 20 from when the ink droplets ejected from the inkjet head 102 land, when the ink droplets are hardened by irradiation with active energy rays, when the ink droplets (image) are transferred at the transfer nip NP, when the ink droplets are heated by the heating section 27 and cooled by the cooling section 29, until when the next ink droplets are ejected from the inkjet head 102 and land.

In FIG. 4B, dotted line L1 indicates the change over time in surface temperature in region 60 on transfer belt 20, and solid line L2 indicates the change over time in surface temperature in region 62 on transfer belt 20.

As shown in FIG. 4B, in positions where the amount of ink droplets is large (region 60), the amount of heat generated during the curing reaction is large and the temperature rise on the transfer belt 20 is large, whereas in positions where the amount of ink droplets is small (region 62), the amount of heat generated during the curing reaction is small and the temperature rise on the transfer belt 20 is small. As a result, temperature unevenness (temperature difference) occurs on the transfer belt 20 after transfer to the recording medium P.

In this embodiment, the control unit 40 controls the contact of the heating roller 27A (heating unit 27) with the surface of the transfer belt 20. The heating roller 27A heats the surface of the transfer belt 20 to a target temperature T1 (see FIG. 4B) that is equal to or greater than the temperature rise of the transfer belt 20 according to the amount of heat generated during the curing reaction of the ink droplets, so that the surface temperature of the transfer belt 20 after heating is uniform.

Then, the control unit 40 obtains the surface temperature of the transfer belt 20 after being heated by the heating unit 27 as the detection result of the temperature detection unit 28. Then, the control unit 40 controls the cooling unit 29 (specifically, the surface temperature of the cooling roller 29A) to cool the surface of the transfer belt 20 based on the obtained surface temperature. Specifically, the cooling unit 29 cools the surface of the transfer belt 20 so that the difference between the obtained surface temperature and the set temperature T2 (see FIG. 4B) set as the surface temperature of the transfer belt 20 before the ink droplets are ejected becomes small until the next ink droplets are ejected.

By performing the temperature adjustment control by heating and cooling as described above, the next time ink droplets are ejected from the inkjet head 102, it is possible to prevent temperature unevenness on the transfer belt 20 and to prevent unevenness in the diameter (dot diameter) of the ink droplets that land on the transfer belt 20. As a result, an image is transferred to the recording medium P without unevenness in the diameter of the ink droplets, thereby suppressing deterioration in the quality of the image.

A specific example of a temperature adjustment operation for adjusting the surface temperature of the transfer belt 20 will be described with reference to FIG. 5. FIG. 5A is a view of the transfer belt 20 seen from below, and shows how the transfer belt 20 passes through the heating unit 27, temperature detection unit 28, and cooling unit 29 after transfer when the difference in the amount of ink droplets ejected from the nozzles of the inkjet head 102 in a direction perpendicular to the movement direction of the transfer belt 20 is small. In FIG. 5A, the amount of ink droplets ejected onto areas 60 and 62 on the transfer belt 20 is small.

Figure 5B shows the change in temperature over time on the transfer belt 20 from when the ink droplets ejected from the inkjet head 102 land, when the ink droplets are hardened by irradiation with active energy rays, when the ink droplets (image) are transferred at the transfer nip NP, when the ink droplets are cooled by the cooling section 29, until the next ink droplets are ejected from the inkjet head 102 and land.

In FIG. 5B, dotted line L1 indicates the change over time in surface temperature in area 60 on transfer belt 20, and solid line L2 indicates the change over time in surface temperature in area 62 on transfer belt 20.

As shown in FIG. 5B, in positions where the amount of ink droplets is small (areas 60, 62), the amount of heat generated during the curing reaction is small, and the amount of temperature rise on the transfer belt 20 is small and approximately the same. Therefore, no temperature unevenness (temperature difference) occurs on the transfer belt 20 after transfer to the recording medium P.

In this embodiment, the control unit 40 performs control to separate the heating roller 27A (heating unit 27) from the surface of the transfer belt 20, i.e., not to heat the surface of the transfer belt 20. In FIG. 5A, the heating roller 27A is shown by a dotted line to indicate the state in which the heating roller (heating unit 27) is separated from the surface of the transfer belt 20.

Then, the control unit 40 obtains the surface temperature of the transfer belt 20 after the temperature rises according to the amount of heat generated during the curing reaction of the ink droplets as the detection result of the temperature detection unit 28. Then, the control unit 40 controls the cooling unit 29 to cool the surface of the transfer belt 20 based on the obtained surface temperature. Specifically, the cooling unit 29 cools the surface of the transfer belt 20 so that the difference between the obtained surface temperature and the set temperature T2 (see FIG. 5B) set as the surface temperature of the transfer belt 20 before the ink droplets are ejected becomes small until the next ink droplets are ejected.

By performing the above-described temperature adjustment control by cooling, the next time ink droplets are ejected from the inkjet head 102, there is no temperature unevenness on the transfer belt 20, and there is no unevenness in the diameter (dot diameter) of the ink droplets that land on the transfer belt 20. As a result, an image is transferred to the recording medium P without unevenness in the diameter of the ink droplets, thereby suppressing deterioration in the quality of the image.

As described above in detail, in this embodiment, the inkjet image forming apparatus 1 (image forming apparatus) includes a head unit 10 (image forming section) that forms an image on a transfer belt 20 (transfer body) by ejecting active energy ray-curable ink droplets from an inkjet head 102, a first irradiation section 25 (curing section) that irradiates the ink droplets that have been ejected and landed on the transfer belt 20 with active energy rays to cure the ink droplets, and a temperature adjustment section (heating section 27, cooling section 29, and control section 40) that adjusts the temperature of the transfer belt 20 based on the difference in the amount of heat generated when the ink droplets cure.

According to the present embodiment configured in this manner, the surface temperature of the transfer belt 20 is adjusted based on the difference in the amount of heat generated when the ink droplets harden. Therefore, the next time ink droplets are ejected from the inkjet head 102, it is possible to prevent temperature unevenness from occurring on the transfer belt 20, and ultimately to prevent unevenness from occurring in the diameter (dot diameter) of the ink droplets that land on the transfer belt 20. As a result, by transferring an image to the recording medium P without unevenness occurring in the diameter of the ink droplets, it is possible to suppress deterioration in the quality of the image.

Figure 6 is a schematic diagram showing a modified example of the overall configuration of the inkjet image forming apparatus 1 according to the second embodiment. In this embodiment, the inkjet image forming apparatus 1 further includes a temperature detection unit 30 that detects the surface temperature of the transfer belt 20, as compared to the first embodiment.

The temperature detection unit 30 is a temperature sensor that is disposed facing the surface of the transfer belt 20 downstream of the transfer nip NP and upstream of the heating unit 27 in the movement direction of the transfer belt 20, and detects the surface temperature of the transfer belt 20 after an image is transferred to the recording medium P at the transfer nip NP. The temperature detection unit 30 outputs the detected surface temperature of the transfer belt 20 to the control unit 40.

In this embodiment, the heating unit 27 is a plurality of heating rollers 27A, 27B, and 27C that are disposed in contact with the surface of the transfer belt 20 downstream of the transfer nip NP in the movement direction (rotation direction) of the transfer belt 20 and heat a plurality of positions on the transfer belt 20 under the control of the control unit 40 (see FIG. 8A). Specifically, as shown in FIG. 8A, the plurality (three) heating rollers 27A, 27B, and 27C are divided and disposed along a direction perpendicular to the movement direction of the transfer belt 20 and heat a plurality of positions in the perpendicular direction. The heating rollers 27A, 27B, and 27C function as the "heating members" of the present invention.

Heating rollers 27A, 27B, and 27C may be formed to a predetermined outer diameter, with the surface of a metal base such as aluminum covered with an elastic layer of silicone rubber or the like. Heating rollers 27A, 27B, and 27C are internally provided with a heating source such as a 300-350 W halogen lamp, and are configured to heat from the inside so that the surface temperature of heating rollers 27A, 27B, and 27C reaches a predetermined temperature.

The heating rollers 27A, 27B, and 27C use known mechanisms to change the contact pressure against the surface of the transfer belt 20 to change the contact area (heating nip width), to move away from the surface of the transfer belt 20, and to change the surface temperature of the heating rollers 27A, 27B, and 27C, thereby changing the amount of heat applied to the surface of the transfer belt 20.

An example of the temperature adjustment operation (corresponding to the "temperature adjustment method" of the present invention) of the inkjet image forming device 1 will be described with reference to the flowchart in FIG. 7. Note that the process shown in FIG. 7 is executed each time image data related to a print job is supplied to the control unit 40 and an amount of ink droplets corresponding to the pixel values of the image data is ejected from the nozzles of the inkjet head 102.

First, the control unit 40 acquires the surface temperatures at multiple positions on the transfer belt 20 based on the detection results of the temperature detection unit 30 (step S300). Next, the control unit 40 determines whether the difference in the surface temperatures at the multiple positions acquired in step S300 is large (step S320).

If the result of the determination is that the difference in surface temperature is large (step S320, YES), the control unit 40 performs control to bring the heating rollers 27A, 27B, and 27C (heating unit 27) into contact with the surface of the transfer belt 20 (step S340). The heating rollers 27A, 27B, and 27C heat the surface of the transfer belt 20 to a target temperature equal to or greater than the temperature rise of the transfer belt 20 according to the amount of heat generated during the curing reaction of the ink droplets so that the surface temperature of the transfer belt 20 after heating is uniform. The heating rollers 27A, 27B, and 27C heat the surface of the transfer belt 20 to a target temperature equal to or greater than the temperature rise of the transfer belt 20 according to the amount of heat generated during the curing reaction of the ink droplets so that the surface temperature of the transfer belt 20 is uniform at multiple positions by increasing the amount of heat at positions with low surface temperatures compared to the amount of heat at positions with high surface temperatures. Then, the process transitions to step S380.

On the other hand, if the difference in surface temperature is not large, i.e., is small (step S320, NO), the control unit 40 performs control to separate the heating rollers 27A, 27B, and 27C (heating unit 27) from the surface of the transfer belt 20 (step S360). In other words, the heating rollers 27A, 27B, and 27C do not heat the surface of the transfer belt 20. After that, the process proceeds to step S380.

As is clear from the difference in processing in steps S340 and S360, when the difference in surface temperature between multiple positions is large, heating rollers 27A, 27B, and 27C increase the amount of heat applied to transfer belt 20 compared to when the difference is small.

In step S380, the control unit 40 obtains the surface temperature of the transfer belt 20 after being heated by the heating unit 27 as the detection result of the temperature detection unit 28.

Finally, the control unit 40 controls the cooling unit 29 (specifically, the surface temperature of the cooling roller 29A) to cool the surface of the transfer belt 20 based on the surface temperature acquired in step S380 (step S400). In this embodiment, when the difference between the surface temperature acquired in step S380 and the set temperature set as the surface temperature of the transfer belt 20 before the ink droplets are ejected is large, the cooling unit 29 increases the amount of cooling of the transfer belt 20 compared to when the difference is small. Completion of the process of step S400 causes the inkjet image forming apparatus 1 to end the process in FIG. 7.

Next, referring to Figure 8, a specific example of a temperature adjustment operation for adjusting the surface temperature of the transfer belt 20 will be described. Figure 8A is a view of the transfer belt 20 seen from below, and shows how the transfer belt 20 passes through the temperature detection unit 30, the heating unit 27, the temperature detection unit 28, and the cooling unit 29 after transfer when there is a large difference in the amount of ink droplets ejected from the nozzles of the inkjet head 102 in a direction perpendicular to the movement direction of the transfer belt 20. In Figure 8A, the amount of ink droplets ejected onto area 60 on the transfer belt 20 is large, and the amount of ink droplets ejected onto area 62 is small.

Figure 8B shows the change in temperature over time on the transfer belt 20 from when the ink droplets ejected from the inkjet head 102 land, when the ink droplets are hardened by irradiation with active energy rays, when the ink droplets (image) are transferred at the transfer nip NP, when the ink droplets are heated by the heating rollers 27A, 27B, and 27C, when they are cooled by the cooling section 29, until when the next ink droplets are ejected from the inkjet head 102 and land.

In FIG. 8B, dotted line L1 shows the change over time in surface temperature in area 60 on transfer belt 20, and solid line L2 shows the change over time in surface temperature in area 62 on transfer belt 20.

As shown in FIG. 8B, in positions where the amount of ink droplets is large (region 60), the amount of heat generated during the curing reaction is large and the temperature rise on the transfer belt 20 is large, whereas in positions where the amount of ink droplets is small (region 62), the amount of heat generated during the curing reaction is small and the temperature rise on the transfer belt 20 is small. As a result, temperature unevenness (temperature difference) occurs on the transfer belt 20 after transfer to the recording medium P.

Therefore, in this embodiment, the control unit 40 obtains the surface temperatures at multiple positions (areas 60, 62) of the transfer belt 20 based on the detection results of the temperature detection unit 30, and detects the occurrence of temperature unevenness (temperature difference).

When the control unit 40 detects the occurrence of temperature unevenness (temperature difference), it controls the heating rollers 27A, 27B, and 27C (heating unit 27) to come into contact with the surface of the transfer belt 20. Specifically, the heating rollers 27A, 27B, and 27C heat the surface of the transfer belt 20 to a target temperature T1 (see FIG. 8B) that is equal to or greater than the temperature rise of the transfer belt 20 according to the amount of heat generated during the curing reaction of the ink droplets, so that the surface temperature of the transfer belt 20 after heating becomes uniform.

In the example shown in FIG. 8, heating rollers 27A, 27B, and 27C heat multiple positions (regions 60 and 62) such that the amount of heat in the position (region 62) where the surface temperature is low is greater than the amount of heat in the position (region 60) where the surface temperature is high. In other words, the amount of heat in region 62 heated by heating roller 27C is greater than the amount of heat in region 60 heated by heating roller 27A. In this way, by individually controlling the amount of heat in heating rollers 27A, 27B, and 27C, the surface temperatures in multiple positions (regions 60 and 62) can be made more uniform and closer to the target temperature than in the first embodiment (see FIG. 8B).

Then, the control unit 40 acquires the surface temperature of the transfer belt 20 after being heated by the heating rollers 27A, 27B, and 27C as the detection result of the temperature detection unit 28. Then, the control unit 40 controls the cooling unit 29 to cool the surface of the transfer belt 20 based on the acquired surface temperature. Specifically, the cooling unit 29 cools the surface of the transfer belt 20 so that the difference between the acquired surface temperature and the set temperature T2 (see FIG. 8B) set as the surface temperature of the transfer belt 20 before the ink droplets are ejected becomes small until the next ink droplets are ejected.

By performing the temperature adjustment control by heating and cooling as described above, the next time ink droplets are ejected from the inkjet head 102, it is possible to prevent temperature unevenness on the transfer belt 20 and to prevent unevenness in the diameter (dot diameter) of the ink droplets that land on the transfer belt 20. As a result, an image is transferred to the recording medium P without unevenness in the diameter of the ink droplets, thereby suppressing deterioration in the quality of the image.

A specific example of a temperature adjustment operation for adjusting the surface temperature of the transfer belt 20 will be described with reference to FIG. 9. FIG. 9A is a view of the transfer belt 20 seen from below, and shows how the transfer belt 20 passes through the temperature detection unit 30, the heating unit 27, the temperature detection unit 28, and the cooling unit 29 after transfer when the difference in the amount of ink droplets ejected from the nozzles of the inkjet head 102 in the direction perpendicular to the movement direction of the transfer belt 20 is small. In FIG. 9A, the amount of ink droplets ejected in areas 60 and 62 on the transfer belt 20 is small.

Figure 9B shows the change in temperature over time on the transfer belt 20 from when the ink droplets ejected from the inkjet head 102 land, when the ink droplets are hardened by irradiation with active energy rays, when the ink droplets (image) are transferred at the transfer nip NP, when the ink droplets are cooled by the cooling section 29, until the next ink droplets are ejected from the inkjet head 102 and land.

In FIG. 9B, dotted line L1 shows the change over time in surface temperature in area 60 on transfer belt 20, and solid line L2 shows the change over time in surface temperature in area 62 on transfer belt 20.

As shown in FIG. 9B, in positions where the amount of ink droplets is small (areas 60, 62), the amount of heat generated during the curing reaction is small, and the amount of temperature rise on the transfer belt 20 is small and approximately the same. Therefore, no temperature unevenness (temperature difference) occurs on the transfer belt 20 after transfer to the recording medium P.

The control unit 40 acquires the surface temperatures at multiple positions (areas 60, 62) of the transfer belt 20 based on the detection results of the temperature detection unit 30, and does not detect the occurrence of temperature unevenness (temperature difference).

In this embodiment, when the control unit 40 does not detect the occurrence of temperature unevenness (temperature difference), it separates the heating rollers 27A, 27B, and 27C (heating unit 27) from the surface of the transfer belt 20, i.e., it performs control not to heat the surface of the transfer belt 20. In FIG. 9A, the heating rollers 27A, 27B, and 27C (heating unit 27) are shown by dotted lines to show the state in which the heating rollers 27A, 27B, and 27C (heating unit 27) are separated from the surface of the transfer belt 20.

Then, the control unit 40 obtains the surface temperature of the transfer belt 20 after the temperature rises according to the amount of heat generated during the curing reaction of the ink droplets as the detection result of the temperature detection unit 28. Then, the control unit 40 controls the cooling unit 29 to cool the surface of the transfer belt 20 based on the obtained surface temperature. Specifically, the cooling unit 29 cools the surface of the transfer belt 20 so that the difference between the obtained surface temperature and the set temperature T2 (see FIG. 9B) set as the surface temperature of the transfer belt 20 before the ink droplets are ejected becomes small until the next ink droplets are ejected.

By performing the above-described temperature adjustment control by cooling, the next time ink droplets are ejected from the inkjet head 102, there is no temperature unevenness on the transfer belt 20, and there is no unevenness in the diameter (dot diameter) of the ink droplets that land on the transfer belt 20. As a result, an image is transferred to the recording medium P without unevenness in the diameter of the ink droplets, thereby suppressing deterioration in the quality of the image.

In the second embodiment, the temperature detection unit 30 does not necessarily have to be provided. In this case, the control unit 40 acquires (estimates) the amount of ink droplets at multiple positions (areas 60, 62) on the transfer belt 20 based on image data related to the print job.

Next, when the difference in the amount of ink droplets at the acquired positions (areas 60, 62) is large, the control unit 40 performs control to bring the heating rollers 27A, 27B, 27C (heating unit 27) into contact with the surface of the transfer belt 20. Here, the heating rollers 27A, 27B, 27C increase the amount of heat at the position with the lower surface temperature (area 62) in the multiple positions (areas 60, 62) more than the amount of heat at the position with the higher surface temperature (area 60).

In the above first and second embodiments, examples have been described in which the amount of ink droplets ejected from the nozzles of the inkjet head 102 differs in the direction perpendicular to the moving direction of the transfer belt 20 (see Figs. 4A and 8A), but the present invention is not limited to this. For example, the present invention can also be applied to cases in which the amount of ink droplets ejected from the nozzles of the inkjet head 102 differs in the moving direction of the transfer belt 20. In this case, the heating unit 27 heats the surface of the transfer belt 20 to a target temperature T1 that is equal to or greater than the temperature rise of the transfer belt 20 according to the amount of heat generated during the curing reaction of the ink droplets, so that the surface temperature of the transfer belt 20 in the moving direction of the transfer belt 20 is uniform.

In the above first and second embodiments, the active energy rays irradiated by the first irradiating unit 25 are ultraviolet rays, but the present invention is not limited to this. For example, the active energy rays may be electron beams. In this case, it is preferable to use ink whose viscosity changes depending on the electron beam.

Furthermore, the above-mentioned embodiments are merely examples of the implementation of the present invention, and the technical scope of the present invention should not be interpreted in a limiting manner based on these. In other words, the present invention can be implemented in various forms without departing from its gist or main features.

REFERENCE SIGNS LIST 1 Inkjet image forming apparatus 2 External device 10 Head unit 20 Transfer belt 21, 22 Driven roller 23 Transfer roller 24 Transport drum 25 First irradiation section 26 Second irradiation section 27 Heating section 27A, 27B, 27C Heating roller 28, 30 Temperature detection section 29 Cooling section 29A Cooling roller 40 Control section 41 CPU
42 RAM
43 ROM
44 Memory unit 51 Transport driving unit 52 Input/output interface 60, 62 Area 101 Head driving unit 102 Inkjet head NP Transfer nip P Recording medium

Claims (10)

an image forming unit that forms an image on a transfer body by ejecting active energy ray-curable ink droplets from an inkjet head;
a curing unit that irradiates the ink droplets that have been discharged and landed on the transfer body with active energy rays to cure the ink droplets;
a temperature adjusting unit that adjusts the temperature of the transfer body based on a difference in the amount of heat generated when the ink droplets are cured;
a transfer section that transfers the image formed on the transfer body to a recording medium at a transfer nip;
a droplet amount acquisition unit that acquires an amount of the ink droplets on the transfer body at a plurality of positions on the transfer body,
The temperature adjustment unit is
a heating section provided downstream of the transfer nip in a moving direction of the transfer body and configured to heat the transfer body;
a cooling section provided downstream of the heating section in a moving direction of the transfer body and configured to cool the transfer body,
the heating unit heats the transfer body so that the temperature of the transfer body after heating becomes uniform, and when a difference in the amount of the ink droplets at the multiple positions is large, the heating amount of the transfer body is increased compared to when the difference is small.
Image forming device. an image forming unit that forms an image on a transfer body by ejecting active energy ray-curable ink droplets from an inkjet head;
a curing unit that irradiates the ink droplets that have been discharged and landed on the transfer body with active energy rays to cure the ink droplets;
a temperature adjusting unit that adjusts the temperature of the transfer body based on a difference in the amount of heat generated when the ink droplets are cured;
a transfer section that transfers the image formed on the transfer body to a recording medium at a transfer nip;
a first temperature acquisition unit that acquires surface temperatures at a plurality of positions on the transfer body after the image is transferred and before heating by a heating unit;
The temperature adjustment unit is
a heating section provided downstream of the transfer nip in a moving direction of the transfer body and configured to heat the transfer body;
a cooling section provided downstream of the heating section in a moving direction of the transfer body and configured to cool the transfer body,
the heating unit heats the transfer body so that the temperature of the transfer body after heating becomes uniform, and includes a plurality of heating members that heat a plurality of positions on the transfer body, respectively, and when a difference in surface temperature at the plurality of positions is large, the heating amount of the transfer body is increased compared to when the difference is small.
Image forming device. the heating unit increases the amount of heat at the positions where the surface temperatures are low compared to the amount of heat at the positions where the surface temperatures are high.
The image forming apparatus according to claim 2 . an image forming unit that forms an image on a transfer body by ejecting active energy ray-curable ink droplets from an inkjet head;
a curing unit that irradiates the ink droplets that have been discharged and landed on the transfer body with active energy rays to cure the ink droplets;
a temperature adjusting unit that adjusts the temperature of the transfer body based on a difference in the amount of heat generated when the ink droplets are cured;
a transfer section that transfers the image formed on the transfer body to a recording medium at a transfer nip;
a droplet amount acquisition unit that acquires an amount of the ink droplets on the transfer body at a plurality of positions on the transfer body,
The temperature adjustment unit is
a heating section provided downstream of the transfer nip in a moving direction of the transfer body and configured to heat the transfer body;
a cooling section provided downstream of the heating section in a moving direction of the transfer body and configured to cool the transfer body,
the heating unit heats the transfer body so that the temperature of the transfer body after heating becomes uniform, and includes a plurality of heating members that heat a plurality of positions on the transfer body, respectively, and the amount of heat applied to the positions where the amount of ink droplets is small is made larger than the amount of heat applied to the positions where the amount of ink droplets is large.
Image forming device. a second temperature acquisition unit that acquires a temperature of the transfer body after the transfer body is heated by the heating unit;
The cooling unit cools the transfer body based on the temperature acquired by the second temperature acquisition unit.
The image forming apparatus according to any one of claims 1 to 4. the cooling unit increases the amount of cooling of the transfer body when a difference between the temperature acquired by the second temperature acquisition unit and a preset temperature that is set as the temperature of the transfer body before the ink droplets are ejected is large, compared to when the difference is small.
The image forming apparatus according to claim 5 . a temperature detection unit that detects the temperature of the transfer body after the image is transferred;
The image forming apparatus according to any one of claims 1 to 6. An image is formed on a transfer body by ejecting active energy ray-curable ink droplets from an inkjet head;
irradiating the ink droplets discharged and landed on the transfer body with active energy rays to cure the ink droplets;
adjusting the temperature of the transfer body based on the difference in the amount of heat generated when the ink droplets are cured;
When the difference in the amount of the ink droplets at the plurality of positions is large, the amount of heat applied to the transfer body is increased compared to when the difference in the amount of the ink droplets at the plurality of positions is small.
Temperature adjustment method. An image is formed on a transfer body by ejecting active energy ray-curable ink droplets from an inkjet head;
irradiating the ink droplets discharged and landed on the transfer body with active energy rays to cure the ink droplets;
adjusting the temperature of the transfer body based on the difference in the amount of heat generated when the ink droplets are cured;
When a difference in surface temperature among a plurality of positions on the transfer body is large, the amount of heat applied to the transfer body is increased compared to when the difference is small.
Temperature adjustment method. An image is formed on a transfer body by ejecting active energy ray-curable ink droplets from an inkjet head;
irradiating the ink droplets discharged and landed on the transfer body with active energy rays to cure the ink droplets;
adjusting the temperature of the transfer body based on the difference in the amount of heat generated when the ink droplets are cured;
a heating amount at a position where the amount of the ink droplets is small among a plurality of positions on the transfer body is set to be larger than a heating amount at a position where the amount of the ink droplets is large;
Temperature adjustment method.

Images