JP7163775B2 - Image forming device and program - Google Patents

Description

The present disclosure relates to an image forming apparatus, and more particularly to an image forming apparatus that forms an image on a recording medium by ejecting ink and control thereof.

2. Description of the Related Art Conventionally, various techniques have been proposed for controlling glossiness of an image formed by an image forming apparatus. For example, Japanese Patent Application Laid-Open No. 2012-184406 (Patent Document 1) discloses a technique of controlling the glossiness of an image to be formed by adjusting the type of wax in the ink used for image formation. Japanese Patent Application Laid-Open Nos. 2010-143073 (Patent Document 2) and 2014-043103 (Patent Document 3) disclose that the amount of a release agent applied to an intermediate transfer belt is adjusted in image formation by an intermediate transfer method. Accordingly, a technique for controlling the glossiness of the formed image is disclosed.

JP 2012-184406 A JP 2010-143073 A JP 2014-043103 A

On the other hand, in the image forming apparatus, there is a demand for a technique for further controlling the glossiness of the formed image as desired by the user.

The present disclosure has been conceived in view of such circumstances, and an object thereof is to provide a technique for more accurately controlling glossiness of an image formed in an image forming apparatus.

According to one aspect of the present disclosure, an ejection portion that forms an image by ejecting ink containing wax; and a controller that performs control for adjusting the degree of wax seepage in the ink on the recording medium when the pressing member comes into contact with the surface.

The controller may perform the control by controlling the temperature of the pressing member.
The controller may control the temperature of the pressure contact member to be higher as the predetermined glossiness is higher.

The pressure contact member includes an intermediate transfer belt, and the ejection unit ejects ink onto the intermediate transfer belt, and after the image ejected onto the pressure contact member is transferred to the recording medium, the temperature of the pressure contact member is adjusted. An adjustment unit may be further provided.

The ink ejected by the ejection section is ink that undergoes sol/gel transition, and the control section adjusts the temperature of the ink when the pressure contact member contacts the surface, thereby controlling the degree of wax seepage in the ink. may be adjusted.

The ink ejected by the ejection section may contain a first wax having a first melting point and a second wax having a second melting point lower than the first melting point. The second melting point may be lower than the temperature of the ink when the pressing member contacts the surface.

The viscosity of the ink ejected by the ejecting portion may be 400 mPa·s or more and 100000 mPa·s or less when the pressure contact member is in contact with the surface.

The image forming apparatus may further include a UV irradiating section for irradiating the recording medium onto which ink has been ejected by the ejection section with UV light before being pressed by the pressing member.

According to another aspect of the present disclosure, a program executed by a computer for controlling an image forming apparatus is provided. The program instructs the computer to read a target gloss level for an image to be formed on a recording medium, to form an image by ejecting ink containing wax, and to form an image of the ink on the recording medium. and a step of executing control for adjusting the degree of exudation of wax in the ink when the pressure contact member abuts against the surface.

According to the present disclosure, when an image is formed on a recording medium with ink, the amount of wax that seeps out from the ink is controlled. Thus, using the same type of ink, the glossiness of the image formed by the ink can be controlled.

FIG. 4 is a diagram schematically showing characteristics of ink ejected in the image forming apparatus of the present embodiment; FIG. 4 is a diagram schematically showing a state in which an ink layer on a recording medium is in contact with a pressure contact member; FIG. 10 is a diagram schematically showing a state in which the amount of wax exuding from the surface of the recording medium (ink) in contact with the pressing member is small; FIG. 10 is a diagram schematically showing a state in which the amount of wax exuding from the surface of the recording medium (ink) in contact with the pressing member is small; 2 is a diagram partially showing the configuration of an image forming section in an example of an image forming apparatus; FIG. 2 is a diagram illustrating an example of hardware blocks of an image forming apparatus; FIG. The results when images are formed in the image forming apparatus 1 under a plurality of conditions are shown. FIG. 4 is a diagram showing an example of the configuration of reference information used for controlling glossiness of an image; 4 is a flow chart of processing performed for image formation. FIG. 10 is a diagram showing a modification of the configuration of the image forming section in the image forming apparatus; The results when images are formed in the image forming apparatus 1 under a plurality of conditions are shown. FIG. 4 is a diagram showing an example of the configuration of reference information used for controlling glossiness of an image; FIG. 10 is a diagram showing a second modified example of the configuration of the image forming section in the image forming apparatus; 14 is a diagram showing the hardware configuration of the image forming apparatus of FIG. 13; FIG. The results when images are formed in the image forming apparatus 1 under a plurality of conditions are shown. FIG. 4 is a diagram showing an example of the configuration of reference information used for controlling glossiness of an image; FIG. 4 is a diagram representing information about the composition of ink; FIG. 4 is a diagram for explaining a mode of control according to the type of ink used; FIG. 4 is a diagram for explaining a mode of control according to the type of ink used;

An embodiment of an image forming apparatus will be described below with reference to the drawings. In the following description, identical parts and components are given identical reference numerals. Their names and functions are also the same. Therefore, these descriptions will not be repeated.

[Ink temperature characteristics]
FIG. 1 is a diagram schematically showing characteristics of ink ejected in the image forming apparatus of this embodiment. In the graph of FIG. 1, the horizontal axis represents the ink temperature, and the vertical axis represents the ink viscosity. As indicated by line L1, the viscosity of the ink decreases as the temperature of the ink increases. In FIG. 1, the temperature Tt at which the viscosity of the ink changes significantly with temperature changes is set as the sol/gel transition temperature. At temperatures higher than the temperature Tt, the ink has liquid properties. At temperatures below the temperature Tt, the ink has solid properties.

It is preferable that the viscosity of the ink is relatively low so that the ink lands at a desired position until it lands on the recording medium after being ejected.

On the other hand, it is preferable that the viscosity of the ink is relatively high when it comes into contact with a pressure contact member such as an intermediate transfer member. This is because when the contact with the pressure contact member is released, the ink layer is divided and formed by the ink unless the "cohesive force inside the ink" is greater than the "adhesive force of the ink surface to the pressure contact member". This is because it is expected that the resulting image will be severely damaged.

As described above, the viscosity of the ink decreases as the temperature of the ink increases. As described above, in the image forming apparatus, the viscosity of the ink is lowered when the ink is ejected, and the viscosity is raised when the ink is in contact with the pressure contact member. After landing on the medium), the temperature of the ink is lowered. In FIG. 1, the temperature of the ink when the contact is released after the ink layer contacts the pressure contact member is indicated as the "separation temperature."

In this embodiment, the amount of wax in the ink that seeps out from the contact surface with the pressure contact member is adjusted. As a result, the ease with which the ink layer separates from the pressure contact member is adjusted, thereby controlling the surface smoothness (that is, glossiness) of the ink layer. As described above, the temperature of the ink is lower when it comes into contact with the pressure contact member than when it is ejected, but the melting point of the wax needs to be even lower than the temperature after it is lowered. Otherwise, in the ink layer after landing on the recording medium, the wax cannot seep out to the contact surface with the pressure contact member.

[Surface condition of recording medium]
(State in which the ink layer is in contact with the pressure contact member)
FIG. 2 is a diagram schematically showing a state in which an ink layer on a recording medium is in contact with a pressure contact member. In FIG. 2, a layer of ink 20 is formed on the recording medium 30, and the layer of ink 20 is in contact with the pressing member. As an example, FIG. 2 shows a state in which ink formed on an intermediate transfer belt is transferred to a recording medium. In another example, FIG. 2 shows that ink is ejected onto a recording medium, and an image formed by the ink is fixed onto the recording medium by bringing a roller into contact with the ink on the recording medium.

In FIG. 2, wax 21 contained in ink 20 is shown. In the present embodiment, the amount of wax 21 exuding to the contact surface with pressure contact member 10 is adjusted. As a result, the ease with which the ink 20 comes off from the pressing member 10 is adjusted, and the glossiness of the image formed by the ink 20 on the recording medium 30 is controlled. 3 and 4, the difference in image gloss due to the difference in the amount of wax exuding will be described.

(When the amount of wax exuding from the contact surface is small)
FIG. 3 is a diagram schematically showing a state when the amount of wax exuding from the surface of the recording medium (ink) in contact with the pressing member is small. FIG. 3 shows a state in which the recording medium is in contact with the pressure contact member ((A) in contact) and a state in which the recording medium is separated from the pressure contact member ((B) contact cancellation). .

In the example of FIG. 3, in the ink 20, the amount of the wax 21 that seeps out to the contact surface is small. As a result, as shown in state (B) in particular, the ease with which the surface of the ink 20 comes off from the pressure contact member 10 is uneven. Therefore, the state of the surface of the ink 20 after the contact is canceled is not uniform. As a result, the glossiness of the surface of the ink 20 is relatively low.

(When there is a large amount of wax exuding from the contact surface)
FIG. 4 is a diagram schematically showing a state when a large amount of wax oozes out from the surface of the recording medium (ink) in contact with the pressing member. Similar to FIG. 3, FIG. 4 shows two states ((A) during contact, (B) contact released).

In the example of FIG. 4, in the ink 20, the amount of the wax 21 exuding to the contact surface is large. As a result, as shown in state (B) in particular, the ease with which the surface of the ink 20 is peeled off from the pressure contact member 10 is uniform. Therefore, the state of the surface of the ink 20 after the abutment is canceled is uniform. Thereby, the glossiness of the surface of the ink 20 becomes relatively high.

As described above with reference to FIGS. 3 and 4, the glossiness of the image formed on the recording medium is controlled by adjusting the amount of wax that seeps out from the surface of the ink.

[Configuration of Image Forming Apparatus]
FIG. 5 is a diagram partially showing the configuration of an image forming section in an example of an image forming apparatus. The image forming apparatus is realized by, for example, a printer such as an MFP (Multi-Functional Peripheral) that forms an image using an inkjet method.

In the example of FIG. 5 , the image forming apparatus includes an ink unit 210 , rollers 510 , 511 and 512 and an intermediate transfer belt 900 . Rollers 510, 511, and 512 transport the recording medium on paper path 920 in the direction indicated by arrow DR1. The ink unit 210 ejects ink onto the intermediate transfer belt 900 . An image formed by ink on the intermediate transfer belt 900 is transferred onto a recording medium at the transfer section 990 .

During image transfer, the recording medium is pressed against the intermediate transfer belt 900 . In this sense, in the example of FIG. 5, the intermediate transfer belt 900 is an example of the pressing member.

The image forming apparatus includes rollers 901 , 902 and 903 for rotating the intermediate transfer belt 900 . Heaters 250 and 240 for adjusting the temperature of the intermediate transfer belt are built inside the rollers 901 and 903, respectively. The transfer section 990 is provided with a heater 260 for adjusting the ambient temperature when the image on the intermediate transfer belt 900 is transferred to the recording medium. A cooling roller 980 is provided between the rollers 902 and 903 . Contact with roller 980 can reduce the temperature of intermediate transfer belt 900 . Thereby, the temperature of the intermediate transfer belt 900 at the position facing the ink unit 210 can be controlled to be lower than the temperature of the intermediate transfer belt 900 inside the transfer section 990 .

The image forming apparatus further includes an irradiation section 230 . In one example, the irradiation unit 230 is implemented by a UV light irradiation device.

When UV light is irradiated from the irradiation unit 512, the polymerization initiator starts polymerization of a monomer, which is a component of the ink, within the ink on the recording medium, thereby solidifying the ink.

[Control Block of Image Forming Apparatus]
FIG. 6 is a diagram illustrating an example of hardware blocks of the image forming apparatus. Referring to FIG. 6, image forming apparatus 1 includes a control section 1A that controls the operation of each element in image forming apparatus 1 .

The control unit 1A includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and the like. The CPU 101 reads out a program corresponding to the processing content from the ROM 102, develops it in the RAM 103, and centrally controls the operation of each block of the image forming apparatus 1 in cooperation with the developed program.

The image forming apparatus 1 further includes a storage device 620 . Storage device 620 is implemented by, for example, a hard disk drive. Storage device 620 may store programs executed by CPU 101 and/or various data (for example, a “gloss level table” described later) that is referred to in the execution of the programs.

The image forming apparatus 1 has a communication interface 610 . Control unit 1A transmits and receives various data to and from an external device (for example, a personal computer) connected to a communication network such as LAN (Local Area Network) or WAN (Wide Area Network) via communication interface 610. conduct. Communication interface 610 is realized by, for example, a communication control card such as a network card.

The image forming apparatus 1 includes operation buttons 111 and a display 112 . The CPU 101 receives input of information via the operation button 111 . The execution result of the program is displayed on the display 112 .

The CPU 101 acquires data (image data) of an image to be formed on a recording medium, and forms an image on the recording medium based on the acquired image data. The image data may include information specifying the glossiness of the image to be formed. Note that the CPU 101 may acquire information specifying the gloss level of the image to be formed via the communication interface 610 separately from the image data, or via the operation button 111 .

The ink unit 210 includes four cartridges 211-214. Each of the cartridges 211 to 214 ejects yellow (Y), magenta (M), cyan (C), and black (K) ink. The CPU 101 controls the ink ejection mode of each of the cartridges 211-214.

The image forming apparatus 1 includes a drive motor group 220 . Drive motor group 220 includes a plurality of motors that respectively drive a plurality of rollers in image forming apparatus 1 . CPU 101 controls the operation of each of the motors of drive motor group 220 .

The image forming apparatus 1 includes a temperature sensor group 290 including a plurality of temperature sensors that measure temperatures of a plurality of parts within the image forming apparatus 1 . The CPU 101 acquires measured temperature information from each of the plurality of temperature sensors.

The CPU 101 controls the operations of the heaters 219, 240, 250, 260 according to the temperatures measured by the temperature sensors. The heater 219 is a heater for controlling the temperature of ink ejected from each of the cartridges 211 to 214 in the ink unit 210 . Also, the CPU 101 controls the operation of the irradiation unit 230 .

[Control result]
In the present embodiment, as described with reference to FIGS. 3 and 4, by adjusting the easiness of peeling of the image from the pressure contact member when contact with the pressure contact member is released, the image is is controlled. In order to adjust the ease of peeling, the degree of seepage of the wax in the ink to the surface is adjusted.

In one example, two waxes are included in the ink. Of the two types of wax, one mainly contributes to adjusting the sol/gel transition temperature of the ink. The other mainly contributes to bleeding onto the surface of the image.

In the present embodiment, the ease of peeling is further adjusted by adjusting the temperature at which the recording medium is pressed by the pressing member (the temperature at which the image is transferred from the intermediate transfer belt 900 to the recording medium). .

FIG. 7 shows results when images are formed in the image forming apparatus 1 under a plurality of conditions. The table in FIG. 7 shows results for three types of ink (Example 1-1, Comparative Example 1-2, Comparative Example 1-3). The compositions of Example 1-1, Comparative Example 1-2, and Comparative Example 1-3 are shown in FIG. 17, which will be described later. The table shows five types of items: "wax type", "transfer temperature", "ink viscosity", "glossiness", and "judgment".

"Wax type" represents the type of wax contained in the ink. In the example of FIG. 7, the ink contains at least one of waxes A, B, and C. In the example of FIG. Waxes A, B, and C have different melting points, as shown in FIG. 17, which will be described later. Wax A mainly contributes to adjusting the sol/gel transition temperature of the ink. Waxes B and C mainly contribute to bleeding onto the surface of the image.

In the example of FIG. 7, the ink of Example 1-1 contains waxes A and B among waxes AC. Comparative Example 1-2 contains only wax A among waxes A to C. Comparative Examples 1-3 contain only wax B among waxes A to C.

“Transfer temperature” represents the temperature at which the image on the intermediate transfer belt 900 is transferred to the recording medium. In one example, the transfer temperature is the ambient temperature within the transfer station 990 .

“Ink viscosity” represents the assumed ink viscosity at the transfer temperature.
"Glossiness" represents the measurement result of the glossiness of the image formed under the conditions shown in FIG. FIG. 7 shows a gloss level of 60 degrees.

“Judgment” represents the content of the judgment regarding the quality of the formed image.
The example of FIG. 7 shows the results of image formation at two types of transfer temperatures (73° C. and 63° C.) for each of Comparative Examples 1-2 and 1-3. No measurement results were obtained.

In the "judgment" of Comparative Example 1-2, it is described as "improper transfer because there is no release agent between the surface of the ink and the intermediate transfer belt." The ink of Comparative Example 1-2 did not contain wax B, and it is believed that this caused insufficient bleeding of the wax from the image surface when the image on the intermediate transfer belt 900 was transferred to the recording medium. More specifically, the sol/gel transition temperature of the ink of Comparative Example 1-2 is about 78° C., but the ink of Comparative Example 1-2 does not contain “wax B” that contributes to wax exudation. , there is no wax having a releasing action between the surface of the ink and the pressing member. For this reason, in Comparative Example 1-2, it is considered that poor separation occurred.

In the "judgment" of Comparative Example 1-3, it is described as "improper transfer because gel transfer does not occur and the ink viscosity at the transfer nip is low." The inks of Comparative Examples 1-3 did not contain Wax A, which is believed to have not increased the sol/gel transition temperature of the inks. As a result, the ink does not gel at the transfer nip (pressed by the intermediate transfer belt 900), and the viscosity of the ink does not increase at the transfer nip. The image may have been distorted.

On the other hand, the "judgment" of Example 1-1 states that "glossiness can be controlled" at any transfer temperature. Further, in Example 1-1, the higher the transfer temperature, the lower the ink viscosity and the higher the gloss of the image. As the transfer temperature increases, the viscosity of the ink decreases and the fluidity of the ink increases. This makes it easier for the wax in the ink to seep out to the contact surface of the image with the intermediate transfer belt 900 . As a result, the contact surface is easily separated from the intermediate transfer belt 900, and the surface of the image becomes smooth after the pressure contact is released. As a result, the higher the transfer temperature, the higher the glossiness.

The sol/gel transition temperature of Example 1-1 is 78°C. By controlling the transfer temperature below the sol/gel transition temperature of the ink and above the melting point of the wax (wax B) that oozes out from the ink surface, the glossiness of the image can be controlled.

[Reference information]
FIG. 8 is a diagram showing an example of the configuration of reference information used for controlling the glossiness of an image. FIG. 8 shows three types of glossiness and the transfer temperature corresponding to each glossiness.

After acquiring the target glossiness of the image to be formed, the CPU 101 acquires the transfer temperature corresponding to the target glossiness according to the reference information. Then, the CPU 101 controls the temperature of the transfer section 990 to the obtained transfer temperature.

Transfer temperatures corresponding to glossinesses other than those shown in FIG. 8 are acquired based on the relationships shown in FIG. In one example, the CPU 101 generates a linear function (or a quadratic or higher function) of the transfer temperature with respect to the glossiness from the relationship shown in FIG. Get the transfer temperature.

[Process flow]
FIG. 9 is a flow chart of processing performed for image formation. In one example, the processing in FIG. 9 is implemented by the CPU 101 executing a given program.

At step S10, the CPU 101 acquires the target glossiness from the image data or from the data input in association with the image data.

At step S20, the CPU 101 sets the pressure contact temperature. In the examples with reference to FIGS. 1 to 8, the pressure contact temperature is treated as the "transfer temperature." The CPU 101 sets the transfer temperature corresponding to the target glossiness as the pressure contact temperature.

In step S30, CPU 101 forms an image on the recording medium. In the image formation, as shown in FIG. 5, the temperature of the ink ejected from the ink unit 210 is controlled at 90.degree. C., and the temperature of the intermediate transfer belt 900 is controlled at 50.degree. The temperature of the transfer section 990 is controlled to the pressure contact temperature set in step S20.

In the image forming apparatus 1 described above, the temperature of the transfer unit 990 is adjusted to control the amount of wax seeping in the image on the recording medium, thereby controlling the glossiness of the formed image. be.

[Configuration of image forming apparatus (2)]
FIG. 10 is a diagram showing a modification of the configuration of the image forming section in the image forming apparatus. In the example of FIG. 10 , the ink unit 210 ejects ink directly onto the recording medium on the paper path 920 . The recording medium then passes through rollers 960 . Thereby, the image on the recording medium is pressed by the roller 960 . Roller 960 is an example of a pressing member. Arrow DR3 represents the direction of rotation of roller 960 . After that, the irradiation unit 230 irradiates the recording medium with UV light. As a result, the ink ejected onto the recording medium starts to polymerize. After that, the recording medium passes through rollers 512 and is discharged out of the image forming apparatus.

The temperature of ink ejected from the ink unit 210 (ink ejection temperature) is controlled at 85°C. The temperature of the recording medium passing on the paper path 920 is controlled at 40.degree.

[Control result (2)]
In the image forming apparatus including the image forming unit shown in FIG. 10, the glossiness of the image is increased by adjusting the ease with which the image is separated from the pressure contact member when the contact with the pressure contact member is released. controlled. In order to adjust the ease of peeling, the degree of seepage of the wax in the ink to the surface is adjusted.

FIG. 11 shows results when images are formed in the image forming apparatus 1 under a plurality of conditions. The table of FIG. 11 includes items similar to those of the table of FIG. 7 except for "pressing temperature". “Pressing temperature” represents the temperature of the portion (surface) where the roller 960 presses the image on the recording medium. In the example of FIG. 10, heater 260 is enclosed in roller 960 . FIG. 11 shows the results for three types of ink (Example 2-1, Comparative Example 2-2, Comparative Example 2-3). The compositions of Example 2-1, Comparative Example 2-2, and Comparative Example 2-3 are shown in FIG. 17, which will be described later. The ink of Example 2-1 contains waxes A and C among waxes A to C. Comparative Example 2-2 contains only wax A among waxes A to C. Comparative Example 2-3 contains only wax B among waxes A to C.

In the example of FIG. 11, the results of image formation at two pressure contact temperatures (65° C. and 55° C.) are shown for each of Comparative Examples 2-2 and 2-3. No measurement results were obtained.

The 'judgment' of Comparative Example 2-2 states, 'Image disturbance. Because there is no release agent between the ink surface and the pressure contact member.' The ink of Comparative Example 2-2 did not contain Wax C, and it is believed that due to this, the wax did not exude insufficiently from the image surface when the image on the recording medium was pressed against the roller 960 .

In the "judgment" of Comparative Example 2-3, it is described that "image disturbance. Gel transition does not occur and the ink viscosity at the press nip is low." The inks of Comparative Examples 2-3 did not contain Wax A, which is believed to have not increased the sol/gel transition temperature of the inks. As a result, the ink was not gelled at the pressure nip (pressure contact by the roller 960), and the pressure contact by the roller 960 distorted the image formed on the recording medium.

On the other hand, the "judgment" of Example 2-1 states that "gloss control is possible" for any pressure contact temperature. In addition, in Example 2-1, the higher the pressure contact temperature, the lower the ink viscosity and the higher the glossiness of the image. As the pressure contact temperature rises, the viscosity of the ink decreases, which makes it easier for the wax in the ink to seep out to the contact surface of the image with the roller 960 . As a result, the contact surface is easily separated from the roller 960, and the surface of the image becomes smooth after the pressure contact is released. As a result, the higher the pressure contact temperature, the higher the glossiness.

The sol/gel transition temperature of Example 2-1 is 72°C. The glossiness of the image can be controlled by controlling the pressure contact temperature below the sol/gel transition temperature of the ink and above the melting point of the wax (wax C) that oozes out from the surface of the ink.

[Reference information (2)]
FIG. 12 is a diagram showing an example of the configuration of reference information used for controlling the glossiness of an image. FIG. 12 describes three types of glossiness and the pressure contact temperature corresponding to each glossiness.

After acquiring the target glossiness of the image to be formed, the CPU 101 acquires the pressure contact temperature corresponding to the target glossiness according to the reference information. Then, the CPU 101 controls the temperature of the roller 960 to the obtained pressure contact temperature.

Pressure contact temperatures corresponding to glossinesses other than the glossinesses shown in FIG. 12 are acquired based on the relationships shown in FIG. In one example, the CPU 101 generates a linear function (or a quadratic or higher function) of the pressure contact temperature with respect to the glossiness from the relationship shown in FIG. Get the welding temperature.

In the example described with reference to FIGS. 10 to 12, CPU 101 executes the same process as in FIG. 9 as the image forming process.

[Configuration of image forming apparatus (3)]
FIG. 13 is a diagram showing a second modification of the configuration of the image forming section in the image forming apparatus. 5, the image forming apparatus in the example of FIG. 13 includes a first irradiation section 231 and a second irradiation section 232 . The first irradiation unit 231 irradiates the image formed on the intermediate transfer belt 900 with UV light before being transferred to the recording medium. The second irradiation unit 232 irradiates the image transferred onto the recording medium with UV light.

In the example of FIG. 13, the viscosity of the ink ejected by the ink unit 210 is increased by the UV light emitted from the first irradiation section 231 before being transferred onto the recording medium. The temperature of the ink ejected from the ink unit 210 (ink ejection temperature) is controlled at 80.degree. The temperature of the intermediate transfer belt 900 is controlled at 40.degree.

FIG. 14 is a diagram showing the hardware configuration of the image forming apparatus of FIG. 13. As shown in FIG. As shown in FIG. 14, the control unit 1A controls operations of the first irradiation unit 231 and the second irradiation unit 232. As shown in FIG.

[Control result (3)]
FIG. 15 shows results when images are formed in the image forming apparatus 1 under a plurality of conditions. FIG. 15 shows the results for three types of ink (Example 3-1, Comparative Example 3-2, Comparative Example 3-3). The compositions of Example 3-1, Comparative Example 3-2, and Comparative Example 3-3 are shown in FIG. 17, which will be described later. The inks of Example 3-1 and Comparative Example 3-2 contain wax C among waxes A to C. Comparative Example 3-3 does not contain any of Waxes AC.

The table in FIG. 15 includes the item "UV curing" in addition to the items in the table in FIG. “UV curing” represents the presence or absence of UV light irradiation by the first irradiation unit 231 and the second irradiation unit 232 . In the example of FIG. 15, UV light was irradiated by both the first irradiation section 231 and the second irradiation section 232 when the inks of Example 3-1 and Comparative Example 3-3 were used. When the ink of Comparative Example 3-2 was used, the UV light from the first irradiation section 231 was not irradiated, and only the UV light from the second irradiation section 232 was irradiated.

In FIG. 15, the ink viscosity represents the viscosity of the ink on the recording medium before it passes through the first irradiation section 231 and is introduced into the transfer section 990 . The inks of Example 3-1 and Comparative Example 3-3 have a higher viscosity than the ink of Comparative Example 3-2 due to the irradiation of the UV light from the first irradiation section 231 .

In the "judgment" of Comparative Example 3-2, there is described "improper transfer. Because the ink viscosity at the transfer nip is low." When the ink of Comparative Example 3-2 was used, UV light was not applied after the ink was ejected onto the recording medium and before it was introduced into the transfer section 990 . Therefore, it is considered that the image composed of the ink was not sufficiently transferred because the viscosity of the ink on the recording medium was too low when it was pressed against the intermediate transfer belt 900 at the transfer portion 990 .

The 'judgment' of Comparative Example 3-3 states, 'Transfer failure, because there is no release agent between the surface of the ink and the intermediate transfer belt.' The ink of Comparative Example 3-3 does not contain wax C, so that the wax does not bleed sufficiently onto the surface of the ink when pressed by the intermediate transfer belt 900 , so that the image is sufficiently removed from the intermediate transfer belt 900 . It is considered that the image was not sufficiently transferred because the image was not peeled off easily.

On the other hand, the "judgment" of Example 3-1 states that "gloss control is possible" for any pressure contact temperature. In addition, in Example 3-1, the higher the transfer temperature, the lower the ink viscosity and the higher the glossiness of the image. As the pressure contact temperature increases, the viscosity of the ink decreases, so that the wax in the ink tends to seep out to the contact surface with the intermediate transfer belt 900 . As a result, the contact surface is easily separated from the roller 960, and the surface of the image after transfer (after pressure contact is released) becomes smooth. As a result, the higher the transfer temperature, the higher the glossiness.

[Reference information (3)]
FIG. 16 is a diagram showing an example of the configuration of reference information used for controlling the glossiness of an image. FIG. 16 describes three types of glossiness and the transfer temperature corresponding to each glossiness.

After acquiring the target glossiness of the image to be formed, the CPU 101 acquires the transfer temperature corresponding to the target glossiness according to the reference information. Then, the CPU 101 controls the temperature of the transfer section 990 to the acquired transfer temperature.

Transfer temperatures corresponding to glossinesses other than the glossinesses shown in FIG. 16 are obtained based on the relationships shown in FIG. In one example, the CPU 101 generates a linear function (or a quadratic or higher function) of the transfer temperature with respect to the glossiness from the relationship shown in FIG. Get the transfer temperature.

[Ink Information]
FIG. 17 is a diagram representing information regarding the composition of the inks used in the above examples. FIG. 17 shows three types of examples (Examples 1-1, 1-2, 1-3) and six types of comparative examples (Comparative Examples 1-2, 1-3, 2-2, 2-3, 3-2 and 3-3) are shown in 100% ratio.

FIG. 17 shows three types of waxes A, B, and C having different melting points. As polymerizable compounds (monomers), three types of compounds (polymerizable compounds (1), (2), and (3)) are shown. Furthermore, FIG. 17 shows polymerization inhibitor (1), polymerization initiator (1), and pigment dispersion.

[Treatment according to type of wax]
In FIG. 17, wax B and wax C are waxes that are expected to seep out to the contact surface with the pressure contact member. As shown in FIG. 17, wax B and wax C have different melting points. At a given temperature, a difference in fluidity can occur between wax B and wax C. Therefore, when an image is pressed under the same conditions, the amount of wax oozing out to the surface to be pressed differs depending on whether the wax contained in the ink together with wax A is wax B or wax C. is expected.

In this sense, in the present embodiment, the temperature at which the image (ink) is pressed is changed depending on whether the wax contained in the ink together with the wax A is the wax B or the wax C. , the glossiness of the image can be controlled.

18 and 19 are diagrams for explaining control aspects according to the type of ink used. FIG. 18 shows the relationship between the target glossiness and the pressure contact temperature (set temperature) for each type of wax contained in ink together with wax A. In FIG. For example, when the target glossiness is 40, the contact temperature is set to 64° C. when ink containing wax A and wax B is used, and the contact temperature is set to 64° C. when ink containing wax A and wax C is used. is set to 52°C.

FIG. 19 shows a flow chart of processing executed by the CPU 101 . The process of FIG. 19 further includes control of step S12 as compared with the process of FIG. More specifically, CPU 101 advances the control to step S12 after acquiring the target glossiness in step S10.

In step S12, CPU 101 acquires the type of ink used for image formation (the type of wax contained in ink together with wax A). An example of a method for obtaining the type of ink is inputting information via the operation button 111 . Another example is input from other devices via communication interface 610 .

Yet another example is reading information attached to cartridges 211-214. Information specifying the type of ink (for example, a bar code) is attached to the surfaces of the cartridges 211-214. The image forming apparatus includes equipment for reading information (eg, barcode reader). The CPU 101 acquires the type of ink by acquiring the information read by the device.

In step S20, the CPU 101 sets the pressure contact temperature based on the target glossiness and the type of ink.

At step S30, CPU 101 forms an image on the recording medium according to the setting at step S20.

Each embodiment disclosed this time should be considered as an illustration and not restrictive in all respects. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims. In addition, the inventions described in the embodiments and modifications are intended to be implemented either singly or in combination as much as possible.

Reference Signs List 1 image forming apparatus 1A control section 10 pressing member 20 ink 21 wax 30 recording medium 101 CPU 102 ROM 103 RAM 111 operation button 112 display 210 ink unit 211, 214 cartridge 219, 240,250,260 heater, 220 drive motor group, 230 irradiation unit, 231 first irradiation unit, 232 second irradiation unit, 290 temperature sensor group, 510,511,512,901,902,903,960,980 roller, 610 communication interface, 620 storage device, 900 intermediate transfer belt, 920 paper feeding path, 990 transfer section.

Claims (9)

an ejection unit that forms an image by ejecting ink containing wax;
a pressure contact member that contacts the surface of the recording medium on which the ink image is formed;
a control unit that performs control for adjusting the degree of wax seepage in the ink on the recording medium when the pressure contact member comes into contact with the surface according to a predetermined glossiness.,
The ink ejected by the ejection unit is an ink that undergoes sol/gel transition,
The control unit adjusts the degree of wax exudation in the ink by adjusting the temperature of the ink when the pressure contact member contacts the surface,
The ink ejected by the ejecting part includes a first wax having a first melting point and a second wax having a second melting point lower than the first melting point,
the second melting point is lower than the temperature of the ink when the pressure contact member contacts the surface; Image forming device. an ejection unit that forms an image by ejecting ink containing wax;
a pressure contact member that contacts the surface of the recording medium on which the ink image is formed;
a control unit that performs control for adjusting the degree of wax seepage in the ink on the recording medium when the pressure contact member contacts the surface according to a predetermined glossiness ;
The control unit performs the control by controlling the temperature of the pressure contact member,
The pressing member includes an intermediate transfer belt,
An image forming apparatus , wherein an image is formed on the surface by transferring ink formed on the intermediate transfer belt . 3. The image forming apparatus according to claim 2, wherein said controller controls the temperature of said pressure contact member to be higher as said predetermined glossiness is higher. The pressing member includes an intermediate transfer belt,
The ejector ejects ink onto the intermediate transfer belt,
4. The image forming apparatus according to claim 2, further comprising an adjustment section that adjusts the temperature of said pressure contact member after the image ejected onto said pressure contact member is transferred to a recording medium. The ink ejected by the ejection unit is ink that undergoes sol/gel transition,
5. The controller according to any one of claims 2 to 4, wherein the controller adjusts the degree of wax seepage in the ink by adjusting the temperature of the ink when the pressure contact member contacts the surface. 2. The image forming apparatus according to item 1. 6. The ink according to any one of claims 1 to 5 , wherein the viscosity of the ink ejected by the ejecting portion is 400 mPa·s or more and 100000 mPa·s or less when the pressure contact member is in contact with the surface. Image forming device. 7. The apparatus according to any one of claims 1 to 6 , further comprising a UV irradiation section for irradiating UV light onto the recording medium on which ink has been discharged by the discharge section before being pressed by the pressure contact member. The image forming apparatus according to . A program executed by a computer that controls an image forming apparatus,
The program causes the computer to:
reading a target gloss level for an image formed on a recording medium;
forming an image by ejecting ink containing wax;
According to the predetermined glossiness, executing control for adjusting the degree of exudation of the wax in the ink when the pressure contact member is in contact with the surface of the recording medium on which the ink image is formed;
run,
The ink ejected in the step of forming an image is ink that undergoes sol/gel transition, and includes a first wax having a first melting point and a second wax having a second melting point lower than the first melting point. and
the second melting point is lower than the temperature of the ink when the pressure contact member contacts the surface;
The step of executing the control adjusts the degree of wax exudation in the ink by adjusting the temperature of the ink when the pressure contact member is in contact with the surface. program. A program executed by a computer that controls an image forming apparatus,
The program causes the computer to:
reading a target gloss level for an image formed on a recording medium;
forming an image by ejecting ink containing wax;
According to the predetermined glossiness, executing control for adjusting the degree of exudation of the wax in the ink when the pressure contact member is in contact with the surface of the recording medium on which the ink image is formed;
The program that causes the to run.
the step of performing the control includes performing the control by controlling the temperature of the pressure contact member;
The pressing member includes an intermediate transfer belt,
An image is formed on the surface by transferring ink formed on the intermediate transfer belt. program.

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