JP2021079660A - Inkjet recording device and method for controlling temperature of the same - Google Patents

Abstract

To provide an inkjet recording device that can accurately detect temperature of a transfer body to control the temperature of the transfer body, record a high-quality image and extend a life of the transfer body.SOLUTION: An inkjet recording device includes: a rotating transfer body; a recording head for discharging ink to the transfer body to form an image; heating means for heating the transfer body formed with an image; and multiple detection means for respectively detecting temperatures of multiple locations in the transfer body. The inkjet recording device performs such the control of selecting a detection means from the multiple detection means which can detect temperature of a location in the transfer body which corresponds to a region on which transferred recording medium abuts and to which ink is not discharged by the recording head at a surface of the transfer body, and controls the heating means to heat on the basis of the temperature detected by the selected detection means.SELECTED DRAWING: Figure 8

Description

The present invention relates to an inkjet recording device and a temperature control method thereof, and more particularly to an inkjet recording device and a temperature control method thereof, in which an image formed by ejecting ink onto an intermediate transfer body is transferred to a recording medium and recorded.

Conventionally, in a recording device that records according to an inkjet method, an ink is ejected from a recording head to an intermediate drum, an image is formed on the intermediate drum, and the image is transferred to a recording medium to record the image. There is. For example, in Patent Document 1, a transfer type inkjet in which ink is ejected from a recording head according to an inkjet method to an intermediate drum (transfer body) to form an intermediate image (ink image), and the formed intermediate image is transferred to a recording medium. The recording device is disclosed. Since the ink viscosity of the intermediate image is important for good transfer, the intermediate image formed on the transfer body is heated with a heater or the like to evaporate the ink solvent to increase the viscosity. Further, in the recording apparatus disclosed in Patent Document 1, the surface of the transfer body is cooled by applying a cooling liquid to the transfer unit after transfer. As described above, in the transfer type inkjet recording apparatus, the image formation on the recording medium is repeated with a series of processes of intermediate image formation, heating, transfer, and cooling as one recording cycle.

Now, in order to record various images by the above series of processes, it is necessary to detect the temperature of the transfer body with high accuracy and execute appropriate feedback for heating control of the heater. Further, when the transfer body and the intermediate image formed on the transfer body are heated, if the heating temperature is lower than the desired temperature, the transfer performance from the transfer body to the recording medium is deteriorated. On the other hand, when the heating temperature is higher than the desired temperature, heat damage to the transfer material becomes a problem.

Further, Patent Document 2 discloses a technique for maintaining the transferability of a recording medium such as plain paper by detecting the temperature of the transfer body and adjusting it to a desired temperature range.

Japanese Unexamined Patent Publication No. 2009-045885 Japanese Unexamined Patent Publication No. 2015-150789

However, in the above-mentioned conventional example, since the temperature of the image forming region on the transfer body cannot be detected with high accuracy, the temperature of the region where the recording medium comes into contact with the transfer body is lower than that of the region where the temperature is not, or the image is inked. In the formed region, the temperature of the transfer body decreases due to the latent heat of the ink moisture. This causes a problem that the color of the transferred image is different.

The present invention has been made in view of the above problems, and is an inkjet recording apparatus capable of detecting the temperature of a transfer body with high accuracy, controlling the temperature of the transfer body appropriately, and recording a high-quality image. It is intended to provide a temperature control method.

In order to achieve the above object, the inkjet recording apparatus of the present invention has the following configuration.

That is, the rotating transfer body, the recording head that ejects ink to the transfer body to form an image, the heating means for heating the transfer body on which the image is formed, and the recording medium are conveyed to the transfer body. A region where the transport means, a plurality of detection means for detecting the temperatures of the plurality of places of the transfer body, and the recording medium transported by the transfer means are brought into contact with each other on the surface of the transfer body. Further, by the selection means for selecting the detection means capable of detecting the temperature of the location of the transfer body corresponding to the region where the ink is not ejected by the recording head from the plurality of detection means, and the detection means selected by the selection means. It is characterized by having a control means for controlling heating by the heating means based on the detected temperature.

Looking at the present invention from another aspect, a rotating transfer body, a recording head that ejects ink to the transfer body to form an image, and a heating means for heating the transfer body on which the image is formed. A temperature control method in an inkjet recording apparatus including a transport means for transporting a recording medium to the transfer body and a plurality of detection means for detecting temperatures at a plurality of places of the transfer body, respectively, on the surface of the transfer body. The detection means capable of detecting the temperature of the location of the transfer body corresponding to the region where the recording medium transported by the transport means is in contact with the recording medium and the region where the ink is not ejected by the recording head is described. Temperature control including a selection step of selecting from a plurality of detection means and a control step of controlling heating by the heating means based on the temperature detected by the detection means selected in the selection step. Provide a method.

According to the present invention, the temperature of the transfer body can be detected with high accuracy and the temperature of the transfer body can be appropriately controlled, so that high-quality image recording can be realized and the durability of the transfer body can be improved. is there.

It is a schematic diagram of the recording system which is a typical embodiment of this invention. It is a perspective view of a recording unit. It is explanatory drawing of the displacement mode of the recording unit of FIG. It is a block diagram of the control system of the recording system of FIG. It is a block diagram of the control system of the recording system of FIG. It is explanatory drawing of the operation example of the recording system of FIG. It is explanatory drawing of the operation example of the recording system of FIG. It is a figure which shows typically the component provided around the transfer body for performing the temperature control of the transfer body. It is a figure which shows the relationship between _{T 3} which shows the temperature just before a nip obtained by an experiment, and transferability. It is a schematic diagram when the transfer body in which the intermediate image was formed is seen from the heating unit side. It is a figure which showed the image formed on the transfer body before the image was transferred to the B2 + size recording medium. It is a flowchart which showed the detection of the surface temperature of the transfer body and the control of a heating unit according to Example 1. FIG. It is a figure which shows the simulation result which showed the temperature transition of the surface temperature of a transfer body. It is the figure which plotted the average value of the detected temperature of three temperature sensors while the transfer cylinder of a recording apparatus goes around. It is a figure which added the temperature profile of three temperature sensors shown in FIG. 14, and the temperature change of three temperature sensors after DUTY switching of an infrared heater based on the temperature profile. It is a flowchart which showed the detection of the surface temperature of the transfer body and the control of a heating unit according to Example 2. FIG. It is a figure which shows an example of the relationship between the ink-applied region and the non-ink-applied region. It is a flowchart which showed the detection of the surface temperature of the transfer body and the control of a heating unit according to Example 3. It is a figure which shows the division method of the image effective area. It is a figure explaining the definition of duty in duty calculation. It is a figure which shows the example of the calculated average duty of each area.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. The following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiment, not all of the plurality of features are essential to the invention, and the plurality of features may be arbitrarily combined. Further, in the attached drawings, the same or similar configurations are designated by the same reference numbers, and duplicate explanations are omitted. Further, in each figure, the arrows X and Y indicate the horizontal direction and are orthogonal to each other. Arrow Z indicates the vertical direction.

<Explanation of terms>
In this specification, "record" (sometimes referred to as "print") is not limited to the case of forming significant information such as characters and figures, and may be significant or unintentional. Furthermore, regardless of whether or not it is manifested so that it can be visually perceived by humans, it also refers to the case where an image, a pattern, a pattern, etc. is widely formed on a recording medium, or the medium is processed.

The term "recording medium" refers not only to paper used in general recording devices, but also to a wide range of materials such as cloth, plastic film, metal plate, glass, ceramics, wood, and leather that can accept ink. Shall be.

Further, "ink" (sometimes referred to as "liquid") should be broadly interpreted as in the definition of "recording (printing)" above. Therefore, by being applied onto the recording medium, it is used for forming images, patterns, patterns, etc., processing the recording medium, or processing ink (for example, coagulation or insolubilization of the colorant in the ink applied to the recording medium). It shall represent a liquid that can be produced. The components of the ink are not particularly limited, but in the present embodiment, it is assumed that a water-based pigment ink containing a pigment, water, and a resin as coloring materials is used.

Furthermore, unless otherwise specified, the "recording element (or nozzle)" shall collectively refer to the ejection port, the liquid passage communicating with the ejection port, and the element that generates energy used for ink ejection.

The element substrate (head substrate) for a recording head used below does not indicate a mere substrate made of a silicon semiconductor, but indicates a configuration in which each element, wiring, or the like is provided.

Further, the term “on the substrate” means not only the top of the element substrate but also the surface of the element substrate and the inside side of the element substrate in the vicinity of the surface. Further, the term "build-in" as used in the present invention does not mean that each element of a separate body is simply arranged as a separate body on the surface of a substrate, but that each element is manufactured as a semiconductor circuit. It indicates that it is integrally formed and manufactured on an element plate by a process or the like.

In the inkjet recording apparatus described below, ink is ejected from a recording head onto a transfer body to form an ink image, and the ink image after removing the liquid component of the ink from the ink image by the liquid removing apparatus is transferred to a recording medium. It is a transfer type inkjet recording device. As the inkjet recording device, in addition to the transfer type inkjet recording device, there is also a direct drawing type inkjet recording device that directly ejects ink to a recording medium to record an image.

Next, a recording system using a transfer type inkjet recording device will be described.

<Recording system>
FIG. 1 is a front view schematically showing a recording system 1 according to an embodiment of the present invention. The recording system 1 is a single-wafer inkjet printer that produces a recorded material P'by transferring an ink image to a recording medium P via a transfer body 2. The recording system 1 includes a recording device 1A and a transport device 1B. In the present embodiment, the X direction, the Y direction, and the Z direction indicate the width direction (total length direction), the depth direction, and the height direction of the recording system 1, respectively. The recording medium P is conveyed in the X direction.

<Recording device>
The recording device 1A includes a recording unit 3, a transfer unit 4, peripheral units 5A to 5E, and a supply unit 6.

<Recording unit>
The recording unit 3 includes a plurality of recording heads 30 and a carriage 31. See FIGS. 1 and 2. FIG. 2 is a perspective view of the recording unit 3. The recording head 30 ejects liquid ink to the transfer body (intermediate transfer body) 2 to form an ink image of a recorded image on the transfer body 2.

In the case of the present embodiment, each recording head 30 is a full-line head extended in the Y direction, and nozzles are arranged in a range covering the width of the image recording area of the maximum usable recording medium. There is. The recording head 30 has an ink ejection surface having a nozzle opened on the lower surface thereof, and the ink ejection surface faces the surface of the transfer body 2 through a minute gap (for example, several mm). In the case of the present embodiment, since the transfer body 2 is configured to move cyclically on the circular orbit, the plurality of recording heads 30 are arranged radially.

Each nozzle is provided with a discharge element. The ejection element is, for example, an element that generates pressure in the nozzle to eject ink in the nozzle, and a technique of an inkjet head of a known inkjet printer can be applied. As the ejection element, for example, an element that ejects ink by causing a film to boil in the ink by an electrothermal converter to form bubbles, an element that ejects ink by an electromechanical converter (piezo element), and an element that uses static electricity are used. Examples thereof include an element that ejects ink. From the viewpoint of high-speed and high-density recording, a discharge element using an electrothermal converter can be used.

In the case of this embodiment, nine recording heads 30 are provided. Each recording head 30 ejects different types of ink from each other. The different types of ink are, for example, inks having different coloring materials, such as yellow ink, magenta ink, cyan ink, and black ink. Although one recording head 30 ejects one type of ink, one recording head 30 may be configured to eject a plurality of types of ink. When a plurality of recording heads 30 are provided in this way, ink (for example, clear ink) in which some of them do not contain a coloring material may be ejected.

The carriage 31 supports a plurality of recording heads 30. The end of each recording head 30 on the ink ejection surface side is fixed to the carriage 31. As a result, the gap between the ink ejection surface and the surface of the transfer body 2 can be maintained more precisely. The carriage 31 is configured to be displaceable while mounting the recording head 30 by the guidance of the guide member RL. In the case of the present embodiment, the guide members RL are rail members extending in the Y direction, and are provided in pairs separated in the X direction. Slide portions 32 are provided on each side portion of the carriage 31 in the X direction. The slide portion 32 engages with the guide member RL and slides in the Y direction along the guide member RL.

FIG. 3 shows the displacement mode of the recording unit 3, and is a diagram schematically showing the right side surface of the recording system 1. A recovery unit 12 is provided at the rear of the recording system 1. The recovery unit 12 has a mechanism for recovering the ejection performance of the recording head 30. Examples of such a mechanism include a cap mechanism that caps the ink ejection surface of the recording head 30, a wiper mechanism that wipes the ink ejection surface, and a suction mechanism that sucks ink in the recording head 30 from the ink ejection surface under negative pressure. be able to.

The guide member RL extends from the side of the transfer body 2 to the recovery unit 12. The recording unit 3 can be displaced between the discharge position POS1 whose solid line indicates the recording unit 3 and the recovery position POS3 whose recording unit 3 is indicated by the broken line by the guidance of the guide member RL, and is a drive mechanism (not shown). Moved by.

The ejection position POS 1 is a position where the recording unit 3 ejects ink to the transfer body 2, and is a position where the ink ejection surface of the recording head 30 faces the surface of the transfer body 2. The recovery position POS3 is a position retracted from the discharge position POS1 and is a position where the recording unit 3 is located on the recovery unit 12. The recovery unit 12 can execute the recovery process for the recording head 30 when the recording unit 3 is located at the recovery position POS3. In the case of the present embodiment, the recovery process can be executed even during the movement before the recording unit 3 reaches the recovery position POS3. There is a preliminary recovery position POS2 between the discharge position POS1 and the recovery position POS3, and the recovery unit 12 is a preliminary to the recording head 30 at the preliminary recovery position POS2 while the recording head 30 is moving from the discharge position POS1 to the recovery position POS3. Recovery processing can be executed.

<Transfer unit>
The transfer unit 4 will be described with reference to FIG. The transfer unit 4 includes a transfer drum 41 and an impression cylinder 42. These bodies are rotating bodies that rotate around a rotation axis in the Y direction, and have a cylindrical outer peripheral surface. In FIG. 1, the arrows shown in the figures of the transfer drum 41 and the impression cylinder 42 indicate the rotation directions thereof, and the transfer drum 41 rotates clockwise and the impression cylinder 42 rotates counterclockwise.

The transfer drum 41 is a support that supports the transfer body 2 on its outer peripheral surface. The transfer body 2 is provided continuously or intermittently in the circumferential direction on the outer peripheral surface of the transfer drum 41. When continuously provided, the transfer body 2 is formed in an endless band shape. When intermittently provided, the transfer body 2 is formed by dividing it into a plurality of segments in an endless band shape, and each segment can be arranged in an arc shape at an equal pitch on the outer peripheral surface of the transfer drum 41.

Due to the rotation of the transfer drum 41, the transfer body 2 moves cyclically on the circular orbit. The position of the transfer body 2 can be distinguished by the rotation phase of the transfer drum 41 into a discharge pretreatment region R1, a discharge region R2, a discharge post-treatment region R3 and R4, a transfer region R5, and a transfer post-treatment region R6. The transcript 2 circulates through these regions.

The ejection pretreatment region R1 is an region in which the transfer body 2 is pretreated before the ink is ejected by the recording unit 3, and is a region in which the peripheral unit 5A performs the treatment. In the case of this embodiment, the reaction solution is applied. The ejection region R2 is a forming region in which the recording unit 3 ejects ink to the transfer body 2 to form an ink image. The post-ejection processing areas R3 and R4 are processing areas for processing the ink image after the ink is ejected, the post-ejection processing area R3 is an area for processing by the peripheral unit 5B, and the post-ejection processing area R4 is the peripheral unit 5C. This is the area where the processing is performed. The transfer region R5 is a region in which the ink image on the transfer body 2 is transferred to the recording medium P by the transfer unit 4. The post-transcriptional treatment region R6 is a region in which the transcript 2 is post-treated after transcription, and is a region in which the peripheral unit 5D performs the treatment.

A peripheral unit 5E is provided between the discharge pretreatment region R1 and the transfer post-treatment region R6, and the transfer body 2 is cooled by air blowing from the peripheral unit 5E.

In the case of the present embodiment, the discharge region R2 is a region having a certain section. The other regions R1 and R3 to R6 have a narrower section than the discharge region R2. In the case of the present embodiment, the discharge pre-processing area R1 is approximately 10 o'clock, the discharge area R2 is approximately 11 o'clock to 1 o'clock, and the discharge post-processing area R3 is approximately 10 o'clock. It is the position at 2 o'clock, and the post-discharge processing area R4 is the position at about 4 o'clock. The transfer region R5 is at approximately 6 o'clock, and the post-transcriptional processing region R6 is approximately 8 o'clock.

The transfer body 2 may be composed of a single layer, or may be a laminated body having a plurality of layers. When composed of a plurality of layers, for example, three layers of a surface layer, an elastic layer, and a compression layer may be included. The surface layer is the outermost layer having an image forming surface on which an ink image is formed. By providing the compression layer, the compression layer can absorb the deformation, disperse the fluctuation with respect to the local pressure fluctuation, and maintain the transferability even at the time of high-speed recording. The elastic layer is the layer between the surface layer and the compression layer.

As the material of the surface layer, various materials such as resin and ceramic can be appropriately used, but a material having a high compressive elastic modulus can be used in terms of durability and the like. Specific examples thereof include an acrylic resin, an acrylic silicone resin, a fluorine-containing resin, and a condensate obtained by condensing a hydrolyzable organosilicon compound. The surface layer may be subjected to surface treatment in order to improve the wettability of the reaction solution, the transferability of the image, and the like. Examples of the surface treatment include frame treatment, corona treatment, plasma treatment, polishing treatment, roughening treatment, active energy ray irradiation treatment, ozone treatment, surfactant treatment, silane coupling treatment and the like. A plurality of these may be combined. Further, any surface shape can be provided on the surface layer.

Examples of the material of the compression layer include acrylonitrile-butadiene rubber, acrylic rubber, chloroprene rubber, urethane rubber, silicone rubber and the like. At the time of molding such a rubber material, a predetermined amount of a vulcanizing agent, a vulcanization accelerator, etc. are blended, and further, a foaming agent, hollow fine particles, a filler such as salt, etc. are blended as necessary, and the porous rubber material is blended. May be. As a result, since the bubble portion is compressed with a volume change in response to various pressure fluctuations, deformation in directions other than the compression direction is small, and more stable transferability and durability can be obtained. Porous rubber materials include those having a continuous pore structure in which each pore is continuous with each other and those having an independent pore structure in which each pore is independent, but any structure may be used, and these structures may be used in combination. You may.

As the member of the elastic layer, various materials such as resin and ceramic can be appropriately used. Various elastomer materials and rubber materials can be used in terms of processing characteristics and the like. Specific examples thereof include fluorosilicone rubber, phenylsilicone rubber, fluororubber, chloroprene rubber, urethane rubber, nitrile rubber and the like. Further, ethylene propylene rubber, natural rubber, styrene rubber, isoprene rubber, butadiene rubber, ethylene / propylene / butadiene copolymer, nitrile butadiene rubber and the like can be mentioned. In particular, silicone rubber, fluorosilicone rubber, and phenylsilicone rubber are advantageous in terms of dimensional stability and durability because they have a small compression set. In addition, the change in elastic modulus with temperature is small, which is advantageous in terms of transferability.

Various adhesives or double-sided tape can also be used between the surface layer and the elastic layer, and between the elastic layer and the compression layer to fix them. Further, the transfer body 2 may include a reinforcing layer having a high compressive elastic modulus in order to suppress lateral elongation when mounted on the transfer drum 41 and to maintain elasticity. Further, the woven fabric may be used as a reinforcing layer. The transfer body 2 can be produced by arbitrarily combining each layer made of the above-mentioned material.

The outer peripheral surface of the impression cylinder 42 is pressed against the transfer body 2. At least one grip mechanism for holding the tip of the recording medium P is provided on the outer peripheral surface of the impression cylinder 42. A plurality of grip mechanisms may be provided so as to be separated from each other in the circumferential direction of the impression cylinder 42. The recording medium P is conveyed in close contact with the outer peripheral surface of the impression cylinder 42, and when it passes through the nip portion between the impression cylinder 42 and the transfer body 2, the ink image on the transfer body 2 is transferred.

A drive source such as a motor for driving the transfer drum 41 and the impression cylinder 42 is common to these, and the driving force can be distributed by a transmission mechanism such as a gear mechanism.

<Peripheral unit>
Peripheral units 5A to 5E are arranged around the transfer drum 41. In the case of the present embodiment, the peripheral units 5A to 5E are, in order, an imparting unit, an absorption unit, a heating unit, a cleaning unit, and a cooling unit.

The applying unit 5A is a mechanism for applying the reaction liquid onto the transfer body 2 before ejecting the ink by the recording unit 3. The reaction liquid is a liquid containing a component that increases the viscosity of the ink. Here, increasing the viscosity of the ink means that the coloring material or resin constituting the ink chemically reacts or is physically adsorbed by coming into contact with a component that increases the viscosity of the ink, thereby causing the ink to become highly viscous. An increase in the viscosity of the ink is observed. The increase in viscosity of the ink is not only when an increase in the viscosity of the entire ink is observed, but also when a part of the components constituting the ink such as a coloring material or a resin aggregates to cause a local increase in the viscosity. Is also included.

The component that increases the viscosity of the ink is not particularly limited, such as metal ions and polymer flocculants, but a substance that causes a change in the pH of the ink and aggregates the coloring material in the ink can be used, and an organic acid can be used. Can be used. Examples of the reaction liquid application mechanism include a roller, a recording head, a die coating device (die coater), and a blade coating device (blade coater). If the reaction solution is applied to the transfer body 2 before the ink is ejected to the transfer body 2, the ink that has reached the transfer body 2 can be immediately fixed. As a result, bleeding in which adjacent inks are mixed with each other can be suppressed.

The absorption unit 5B is a mechanism for absorbing a liquid component from the ink image on the transfer body 2 before transfer. By reducing the liquid component of the ink image, bleeding of the image recorded on the recording medium P can be suppressed. Explaining the decrease of the liquid component from a different viewpoint, it can be expressed as concentrating the ink constituting the ink image on the transfer body 2. Concentrating the ink means that the liquid component contained in the ink is reduced, so that the content ratio of the solid content such as the coloring material and the resin contained in the ink to the liquid component is increased.

The absorption unit 5B includes, for example, a liquid absorption member that comes into contact with the ink image to reduce the amount of liquid components in the ink image. The liquid absorbing member may be formed on the outer peripheral surface of the roller, or the liquid absorbing member may be formed in the shape of an endless sheet and travel in a cyclic manner. In terms of protecting the ink image, the liquid absorbing member may be moved in synchronization with the transfer body 2 by making the moving speed of the liquid absorbing member the same as the peripheral speed of the transfer body 2.

The liquid absorbing member may include a porous body that comes into contact with the ink image. In order to suppress the adhesion of ink solids to the liquid absorbing member, the pore size of the porous body on the surface in contact with the ink image may be 10 μm or less. Here, the pore diameter indicates an average diameter, and can be measured by a known means such as a mercury intrusion method, a nitrogen adsorption method, an SEM image observation, or the like. The liquid component is not particularly limited as long as it does not have a certain shape, has fluidity, and has a substantially constant volume. For example, water, organic solvent, etc. contained in ink or reaction liquid can be mentioned as liquid components.

The heating unit 5C is a mechanism for heating the ink image on the transfer body 2 before transfer. By heating the ink image, the resin in the ink image is melted, and the transferability to the recording medium P is improved. The heating temperature can be equal to or higher than the minimum film forming temperature (MFT) of the resin. MFT can be measured by generally known methods such as JIS K 6828-2: 2003 and ISO2115: 1996 compliant devices. From the viewpoint of transferability and image fastness, heating may be performed at a temperature higher than MFT by 10 ° C. or higher, and further, heating may be performed at a temperature higher than 20 ° C. or higher. As the heating unit 5C, known heating devices such as various lamps such as infrared rays and a hot air fan can be used. Infrared heaters can be used in terms of heating efficiency.

The cleaning unit 5D is a mechanism for cleaning the transfer body 2 after transfer. The cleaning unit 5D removes ink remaining on the transfer body 2, dust on the transfer body 2, and the like. For the cleaning unit 5D, for example, a known method such as a method of bringing a porous member into contact with the transfer body 2, a method of rubbing the surface of the transfer body 2 with a brush, a method of scraping the surface of the transfer body 2 with a blade, or the like is appropriately used. Can be done. Further, as the cleaning member used for cleaning, a known shape such as a roller shape or a web shape can be used.

The cooling unit 5E is a blower mechanism that cools the transfer body 2 cleaned by the cleaning unit 5D by air blowing. As will be described later, the amount of air blow is controlled by the temperature detected by a plurality of temperature sensors provided around the transfer body 2. This controls the cooling effect.

As described above, in the present embodiment, the imparting unit 5A, the absorption unit 5B, the heating unit 5C, the cleaning unit 5D, and the cooling unit 5E are provided as peripheral units. The invention is not limited. For example, the imparting unit 5A or the cleaning unit 5D may be provided with a cooling function equivalent to that of the cooling unit 5E of the transfer body 2. In the present embodiment, the temperature of the transfer body 2 may rise due to the heat of the heating unit 5C. If the ink image exceeds the boiling point of water, which is the main solvent of the ink, after the ink is ejected to the transfer body 2 by the recording unit 3, the absorption performance of the liquid component by the absorption unit 5B may deteriorate. By cooling the transfer body 2 so that the ejected ink is maintained below the boiling point of water, the absorption performance of the liquid component can be maintained.

In addition to the ventilation mechanism, the cooling unit 5E may be provided with a configuration in which a member (for example, a roller) is brought into contact with the transfer body 2 and the member is cooled by the ventilation mechanism. Further, a mechanism for cooling the cleaning member of the cleaning unit 5D by the cooling unit 5E may be provided. The cooling timing may be the period after the transfer and before the application of the reaction solution.

<Supply unit>
The supply unit 6 is a mechanism for supplying ink to each recording head 30 of the recording unit 3. The supply unit 6 may be provided on the rear side of the recording system 1. The supply unit 6 includes a storage unit TK for storing ink for each type of ink. The storage unit TK may be composed of a main tank and a sub tank. Each storage unit TK and each recording head 30 communicate with each other through a flow path 6a, and ink is supplied from the storage unit TK to the recording head 30. The flow path 6a may be a flow path for circulating ink between the storage unit TK and the recording head 30, and the supply unit 6 may include a pump or the like for circulating ink. A degassing mechanism for degassing air bubbles in the ink may be provided in the middle of the flow path 6a or in the storage portion TK. A valve for adjusting the hydraulic pressure of the ink and the atmospheric pressure may be provided in the middle of the flow path 6a or in the storage portion TK. The heights of the storage unit TK and the recording head 30 in the Z direction may be designed so that the ink liquid level in the storage unit TK is lower than the ink ejection surface of the recording head 30.

<Transport device>
The transport device 1B is a device that feeds the recording medium P to the transfer unit 4 and discharges the recorded material P'with the ink image transferred from the transfer unit 4. The transport device 1B includes a feed unit 7, a plurality of transport cylinders 8, 8a, two sprockets 8b, a chain 8c, and a recovery unit 8d. In FIG. 1, the inner arrow of the figure of each configuration of the transport device 1B indicates the rotation direction of the configuration, and the outer arrow indicates the transport path of the recording medium P or the recorded object P'. The recording medium P is transported from the feeding unit 7 to the transfer unit 4, and the recorded material P'is transported from the transfer unit 4 to the recovery unit 8d. The feeding unit 7 side may be referred to as the upstream side in the transport direction, and the recovery unit 8d side may be referred to as the downstream side.

The feeding unit 7 includes a loading unit on which a plurality of recording media P are loaded, and also includes a feeding mechanism for feeding the recording media P one by one from the loading unit to the most upstream transport cylinder 8. Each of the transport cylinders 8 and 8a is a rotating body that rotates around a rotation axis in the Y direction, and has a cylindrical outer peripheral surface. At least one grip mechanism for holding the tip of the recording medium P (or the recording object P') is provided on the outer peripheral surface of each of the transport cylinders 8 and 8a. The gripping operation and the releasing operation of each grip mechanism are controlled so that the recording medium P is passed between the adjacent transport cylinders.

The two transport cylinders 8a are transport cylinders for reversing the recording medium P. When recording on both sides of the recording medium P, after the transfer to the surface, the recording medium P is passed to the transport cylinder 8a without being passed from the impression cylinder 42 to the transport cylinder 8 adjacent to the downstream side. The front and back of the recording medium P are reversed via the two transport cylinders 8a, and the recording medium P is passed to the impression cylinder 42 again via the transport cylinder 8 on the upstream side of the impression cylinder 42. As a result, the back surface of the recording medium P faces the transfer drum 41, and the ink image is transferred to the back surface.

The chain 8c is wound between the two sprockets 8b. One of the two sprockets 8b is the driving sprocket and the other is the driven sprocket. The rotation of the drive sprocket causes the chain 8c to travel cyclically. The chain 8c is provided with a plurality of grip mechanisms separated from each other in the longitudinal direction thereof. The grip mechanism grips the end of the recorded object P'. The recorded material P'is passed from the transport cylinder 8 located at the downstream end to the grip mechanism of the chain 8c, and the recorded material P'gripped by the grip mechanism is transported to the recovery unit 8d by the traveling of the chain 8c, and the grip is released. To. As a result, the recorded material P'is loaded in the collection unit 8d.

<Post-processing unit>
The transport device 1B is provided with post-processing units 10A and 10B. The post-processing units 10A and 10B are arranged on the downstream side of the transfer unit 4 and are a mechanism for performing post-processing on the recorded material P'. The post-processing unit 10A processes the front surface of the recorded material P', and the post-processing unit 10B processes the back surface of the recorded material P'. Examples of the processing contents include a coating on the image recording surface of the recorded object P'for the purpose of protecting the image, polishing the image, and the like. Examples of the content of the coating include application of a liquid, welding of a sheet, laminating and the like.

<Inspection unit>
The transport device 1B is provided with inspection units 9A and 9B. The inspection units 9A and 9B are arranged on the downstream side of the transfer unit 4 and are a mechanism for inspecting the recorded material P'.

In the case of the present embodiment, the inspection unit 9A is an imaging device that captures an image recorded on the recorded object P', and includes, for example, an image pickup device such as a CCD sensor or a CMOS sensor. The inspection unit 9A captures a recorded image during a continuous recording operation. Based on the image taken by the inspection unit 9A, it is possible to confirm the change with time such as the color tone of the recorded image and determine whether or not the image data or the recorded data can be corrected. In the case of the present embodiment, the inspection unit 9A has an imaging range set on the outer peripheral surface of the impression cylinder 42, and is arranged so that the recorded image immediately after transfer can be partially captured. All recorded images may be inspected by the inspection unit 9A, or may be inspected at predetermined intervals.

In the case of the present embodiment, the inspection unit 9B is also a photographing device that captures an image recorded on the recorded object P', and includes, for example, an image pickup device such as a CCD sensor or a CMOS sensor. The inspection unit 9B captures a recorded image in the test recording operation. The inspection unit 9B captures the entire recorded image, and can make basic settings for various corrections related to the recorded data based on the image captured by the inspection unit 9B. In the case of the present embodiment, it is arranged at a position where the recorded object P'carried by the chain 8c is photographed. When the recorded image is taken by the inspection unit 9B, the running of the chain 8c is temporarily stopped and the whole is taken. The inspection unit 9B may be a scanner that scans on the recorded object P'.

<Control unit>
Next, the control unit of the recording system 1 will be described. 4 and 5 are block diagrams of the control unit 13 of the recording system 1. The control unit 13 is communicably connected to the host device (DFE) HC2, and the host device HC2 is communicably connected to the host device HC1.

The host device HC1 may be, for example, a PC which is an information processing device or a server device. Further, the communication method between the host device HC1 and the host device HC2 may be either wired or wireless, and is not particularly limited.

In the host device HC1, the original data that is the source of the recorded image is generated or saved. The manuscript data here is generated in the form of an electronic file such as a document file or an image file, for example. This manuscript data is transmitted to the higher-level device HC2, and the higher-level device HC2 converts the received manuscript data into a data format (for example, RGB data expressing an image in RGB) that can be used by the control unit 13. The converted data is transmitted from the host device HC2 to the control unit 13 as image data, and the control unit 13 starts the recording operation based on the received image data.

In the case of the present embodiment, the control unit 13 is roughly classified into a main controller 13A and an engine controller 13B. The main controller 13A includes a processing unit 131, a storage unit 132, an operation unit 133, an image processing unit 134, a communication I / F (interface) 135, a buffer 136, and a communication I / F 137.

The processing unit 131 is a processor such as a CPU, executes a program stored in the storage unit 132, and controls the entire main controller 13A. The storage unit 132 is a storage device such as a RAM, ROM, hard disk, SSD, etc., stores programs and data executed by the CPU 131 (processing unit), and provides a work area to the CPU 131. In addition to the storage unit 132, an external storage unit may be further provided. The operation unit 133 is, for example, an input device such as a touch panel, a keyboard, and a mouse, and receives a user's instruction. The operation unit 133 may have, for example, a configuration in which an input unit and a display unit are integrated. The user operation is not limited to the input via the operation unit 133, and may be configured to receive instructions from the host device HC1 or the host device HC2, for example.

The image processing unit 134 is, for example, an electronic circuit having an image processing processor. The buffer 136 is, for example, a RAM, a hard disk, or an SSD. The communication I / F 135 communicates with the host device HC2, and the communication I / F 137 communicates with the engine controller 13B. In FIG. 4, the broken line arrow illustrates the flow of image data processing. The image data received from the host device HC2 via the communication IF135 is stored in the buffer 136. The image processing unit 134 reads image data from the buffer 136, performs predetermined image processing on the read image data, and stores the read image data in the buffer 136 again. The image data after image processing stored in the buffer 136 is transmitted from the communication I / F 137 to the engine controller 13B as recorded data used by the print engine.

As shown in FIG. 5, the engine controller 13B includes the engine control units 14, 15A to 15E, and acquires and controls the drive of the detection results of the sensor group and the actuator group 16 included in the recording system 1. Each of these control units includes a processor such as a CPU, a storage device such as a RAM or ROM, and an interface with an external device. Note that the division of control units is an example, and some controls may be executed by a plurality of further subdivided control units, or conversely, a plurality of control units may be integrated to combine the control contents. It may be configured to be performed by one control unit.

The engine control unit 14 controls the entire engine controller 13B. The recording control unit 15A converts the recorded data received from the main controller 13A into a data format suitable for driving the recording head 30, such as raster data. The recording control unit 15A controls the discharge of each recording head 30.

The transfer control unit 15B controls the imparting unit 5A, the absorption unit 5B, the heating unit 5C, the cleaning unit 5D, and the cooling unit 5E.

The reliability control unit 15C controls the supply unit 6, controls the recovery unit 12, and controls the drive mechanism that moves the recording unit 3 between the discharge position POS1 and the recovery position POS3.

The transfer control unit 15D controls the drive of the transfer unit 4 and the transfer device 1B. The inspection control unit 15E controls the inspection unit 9B and the inspection unit 9A.

Among the sensor group and the actuator group 16, the sensor group includes a sensor for detecting the position and speed of a movable portion, a sensor for detecting temperature, an image sensor, and the like. The actuator group includes a motor, an electromagnetic solenoid, an electromagnetic valve and the like.

<Operation example>
FIG. 6 is a diagram schematically showing an example of a recording operation. While the transfer drum 41 and the impression cylinder 42 are rotated, the following steps are cyclically performed. As shown in the state ST1, the reaction solution L is first applied onto the transcript 2 from the application unit 5A. The portion of the transfer body 2 to which the reaction solution L is applied moves with the rotation of the transfer drum 41. When the portion to which the reaction solution L is applied reaches the bottom of the recording head 30, ink is ejected from the recording head 30 to the transfer body 2 as shown in the state ST2. As a result, the ink image IM is formed. At that time, the ejected ink mixes with the reaction liquid L on the transfer body 2, thereby promoting the aggregation of the coloring material. The ejected ink is supplied to the recording head 30 from the storage unit TK of the supply unit 6.

The ink image IM on the transfer body 2 moves as the transfer body 2 rotates. When the ink image IM reaches the absorption unit 5B, the liquid component is absorbed from the ink image IM by the absorption unit 5B as shown in the state ST3. When the ink image IM reaches the heating unit 5C, the ink image IM is heated by the heating unit 5C as shown in the state ST4, the resin in the ink image IM is melted, and the ink image IM is formed into a film. The recording medium P is conveyed by the transfer device 1B in synchronization with the formation of such an ink image IM.

As shown in the state ST5, the ink image IM and the recording medium P reach the nip portion between the transfer body 2 and the impression cylinder 42, the ink image IM is transferred to the recording medium P, and the recording material P'is manufactured. .. After passing through the nip portion, the image recorded on the recorded object P'is taken by the inspection unit 9A, and the recorded image is inspected. The recorded material P'is transported to the collection unit 8d by the transport device 1B.

When the portion of the transfer body 2 on which the ink image IM is formed reaches the cleaning unit 5D, it is cleaned by the cleaning unit 5D as shown in the state ST6. After cleaning, the transfer body 2 has made one rotation, and the ink image is repeatedly transferred to the recording medium P in the same procedure. Before the state of the transfer body 2 returns from the state ST6 to the state ST1, the surface of the transfer body 2 is sufficiently cooled by the cooling unit 5E. In the above description, in order to facilitate understanding, it has been described that the ink image IM is transferred to one recording medium P once by one rotation of the transfer body 2, but it is described by one rotation of the transfer body 2. The ink image IM can be continuously transferred to a plurality of recording media P.

If such a recording operation is continued, maintenance of each recording head 30 is required.

FIG. 7 shows an operation example during maintenance of each recording head 30. The state ST11 indicates a state in which the recording unit 3 is located at the discharge position POS1. The state ST12 indicates a state in which the recording unit 3 has passed the preliminary recovery position POS2, and the recovery unit 12 executes a process of recovering the ejection performance of each recording head 30 of the recording unit 3 during the passage. After that, as shown in the state ST13, with the recording unit 3 located at the recovery position POS3, the recovery unit 12 executes a process of recovering the ejection performance of each recording head 30.

<Temperature control of transcript>
FIG. 8 is a diagram schematically showing components provided around the transfer body in order to perform temperature control of the transfer body. Note that, in FIG. 8, among the various components of the recording system shown in FIG. 1, the portion that is not directly related to the temperature control of the transfer body is not shown. Further, in FIG. 8, the same reference numbers are given to the components already described with reference to FIG. 1, and the description is not repeated.

As shown in FIG. 8, the temperature sensor 111 is provided on the downstream side of the imparting unit 5A and the temperature sensor 112 is provided on the downstream side of the heating unit 5C with respect to the rotation direction of the transfer body 2. By arranging the two temperature sensors in this way, the temperature of the transfer body 2 cooled by the cleaning unit 5D, the cooling unit 5E, and the imparting unit 5A is detected, and the temperature of the transfer body 2 heated by the heating unit 5C is detected. Is detected. The temperature sensors 111 and 112 are non-contact sensors that detect the temperature of the transfer body 2 by detecting infrared rays radiated from the surface of the transfer body 2.

With such a configuration, the temperature of the transfer body 2 is maintained at _{T 1 to} T _{2 ° C. directly under the recording unit 3.} On the other hand, the nip portion between the transfer drum 41 and the impression cylinder 42 on which the image is transferred is held at _{T 3 to} T _{4 ° C.}

The imparting unit 5A includes a reaction solution accommodating unit 103a for accommodating the reaction solution L to be applied to the transfer body 2, a roller 103b for taking out the reaction solution L contained in the reaction solution accommodating unit 103a, and a reaction solution impregnated in the roller 103b. It includes a roller 103c that imparts L to the transfer body 2. The reaction solution accommodating unit 103a includes a cooling mechanism that cools and holds the reaction solution L below a certain temperature. The reaction solution accommodating portion 103a is provided with a temperature sensor 113 for measuring the temperature of the reaction solution L.

Further, the cleaning unit 5D includes a CL liquid accommodating portion 109a for accommodating a cleaning liquid (CL liquid) used for cleaning the transfer body 2 and a roller 109b for applying the CL liquid contained therein to the transfer body 2. Including. The CL liquid accommodating portion 109a includes a cooling mechanism that cools and holds the CL liquid below a certain temperature. The CL liquid accommodating portion 109a is provided with a temperature sensor 114 for measuring the temperature of the CL liquid.

As can be seen from the above configuration, the transfer body 2 is cooled to some extent by the application of the reaction solution L by the application unit 5A and the application of the CL solution by the cleaning unit 5D. Therefore, it can be said that the imparting unit 5A and the cleaning unit 5D have a liquid-cooled cooling function. The temperature sensor 113 and the temperature sensor 114 may be provided in the liquid storage portion as in the configuration of the present embodiment, or may be provided in a liquid supply flow path (not shown) or in a liquid cooling circulation flow path.

In addition to this, as described above, a cooling unit 5E is provided between the granting unit 5A and the cleaning unit 5D. The cooling unit 5E includes a fan that blows air to the transfer body 2 and a control boosting that controls the amount of the blown air. As described above, it can be said that the cooling unit 5E in this embodiment has an air-cooled cooling function.

As described above, the recording system in this embodiment includes a cooling mechanism that cools the transfer body 2 in the order of liquid cooling, air cooling, and liquid cooling in the rotation direction of the transfer body 2. Such an order is determined to achieve an efficient cooling effect on the transcript 2.

Further, as can be seen from the above configuration, the temperature control of the transfer body 2 is performed based on the temperature detected by the four temperature sensors.

Now, T ₁ and T ₃ is the lower limit value of the temperature T ₁ through T ₃ are determined by the transfer performance.

FIG. 9 is a diagram showing the relationship between _{T 3} indicating the temperature immediately before the nip and transferability obtained by the inventor's experiment.

As shown in FIG. 9, the transferability of the image tends to decrease _{, especially when the temperature T 3 immediately before the nip is low.} On the other hand, the temperature T ₁ is determined by adding the temperature cooled by the rotation time from the outlet of the heating unit 5C to the nip portion of the transfer drum 41 and the impression cylinder 42 with respect to the rotation direction of the transfer body 2 to the temperature T _3. .. In the recording device 1A, the temperature T ₁ = 100 ° C. and the temperature T ₃ = 90 ° C.

On the other hand, the temperature T ₂ is determined by the durability of the transcript 2.

The recording apparatus 1A uses a reaction solution using an organic acid, and after the reaction solution is applied to the surface layer of the transfer body 2, the surface layer is formed by repeatedly applying high-temperature heating in the heating unit 5C. It becomes hard and brittle. Further, since the hardness and brittleness of the surface layer become more remarkable as the applied temperature is higher, the outlet temperature of the heating unit 5C is assumed to be set at the _{upper limit temperature T 2.}

The recording device 1A controls the heating unit 5C so that the outlet temperature of the heating unit 5C is in the range of 100 to 120 ° C. Considering the in-plane variation of the infrared heater, there is a fluctuation of ± 10 ° C. with respect to the target temperature, so the set temperature of the infrared heater is 110 ° C.

On the other hand, the following factors hinder the highly accurate temperature detection of the transfer body 2. That is, (1) the duty difference of the ink formed on the transfer body, (2) the color difference of the ink, and (3) heat dissipation by the nip. In the case of (1), the temperature is detected low due to the latent heat of vaporization of the liquid component (for example, water) which is the main component of the ink. In the case of (2), when an infrared heater or the like is used, the absorption characteristics differ depending on the color, so that a temperature difference occurs. In the case of (3), when the size of the recording medium changes during transfer in the recording process, only a part of the transfer body 2 is nipped.

FIG. 10 is a schematic view of the transfer body on which the intermediate image is formed when viewed from the heating unit side.

As shown in FIG. 10, the temperature sensor 112 includes three sensors, 112F from the front side to the back side, 112C in the center, and 112R on the back side in the rotation axis direction of the transfer drum 41. The temperature sensor 112C is located at the center of the transfer body 2 in the direction of the rotation axis, and the temperature sensors 112F and 112R are installed at a distance of 384 mm to the left and right from the temperature sensor 112C. This is because the transfer of the recording medium in the recording device 1A executes the transfer in which the center of the transfer surface of the transfer drum 41 and the center of the width of the recording medium are aligned, and the maximum paper size that can be passed is B2 + (width 788 mm × length). This is to match the contact positions of the left and right ends (600 mm).

In FIG. 10, 115 indicates a contact region of a B2 + size recording medium. Further, it is assumed that the temperature sensor 111 also has three temperature sensors installed in the rotation axis direction of the transfer drum 41 like the temperature sensor 112.

FIG. 11 is a diagram showing an image formed on the transfer body before the image is transferred to a B2 + size recording medium.

As shown in FIG. 11, it is assumed that the image transferred to the B2 + size recording medium fits within the image effective area 116. There are margin areas of 20 mm and 30 mm, respectively, at the front and rear ends, and here, temperature detection is performed by aiming at the position of the transfer body 2 corresponding to the margin positions. Further, the temperature sensors 112F and 112R are installed 384 mm to the left and right from the temperature sensor 112C in order to detect the left and right margin areas. On the other hand, since the temperature sensor 112C passes through the image effective region 116 of the transfer body 2 regardless of the size of the recording medium to be transferred, the temperature is detected by aiming at the regions corresponding to the front and rear margin regions of the transfer image in the transport direction of the recording medium. To execute.

Next, in the recording system having the above configuration, some controls are performed to effectively cool and heat the surface temperature of the transfer body 2, maintain the temperature of the transfer body 2 appropriately, and detect the transfer body 2 with high accuracy. Examples will be described.

<Example 1>
FIG. 12 is a flowchart showing the detection of the surface temperature of the transfer body and the control of the heating unit according to the first embodiment.

First, in step S110, the size of the recording medium used for printing is read. This reading may be specified by the operation unit 133 of the recording system 1, or may be received by receiving the size information from the host device HC1. In any case, the information is transmitted from the main controller 13A to the transport control unit 15D, and the control is started. Next, in step S120, a temperature sensor capable of detecting the margin portion of the image effective area 116 is selected based on the size of the recording medium to be printed. Here, in order to print a B2 + size recording medium, all three temperature sensors 112F, 112C, and 112R are used. When recording on a recording medium having a size smaller than the B2 + size, the temperature sensors 112F and 112R may be outside the contact area 115 of the recording medium, so the temperature is detected using only the temperature sensor 112C. ..

In step S130, the detection timing of the temperature sensor is determined. The transfer drum 41 is divided into 28329 regions around it by an encoder slit. In order to detect at a position corresponding to the margin area of the tip, it is desirable to detect the temperature at the 1100th slit from the origin, assuming that the tip of the transfer body 2 is the origin. On the other hand, in order to detect at a position corresponding to the margin area at the rear end, it is desirable to perform temperature detection at the 6000th slit. Here, the temperature detection timing is determined from the displacement information depending on the encoder position, but the temperature detection timing may be set based on the rotation speed and the elapsed time from the origin.

In step S140, the temperature of the transfer body 2 is detected at the detection timing determined in step S130, and in step S150, the heater duty (DUTY) of the heating unit 5C is calculated based on the detected temperature. Generally, the larger the DUTY, the larger the heating capacity. Therefore, it is calculated that the lower the temperature of the transfer body 2, the larger the DUTY. In this embodiment, the infrared heater built in the heating unit 5C is PWM-controlled to heat. Therefore, increasing the PWM duty increases the amount of heat generated by the infrared heater.

As described in FIG. 6, in the recording device 1A, four images are continuously transferred by one rotation of the transfer drum 41. In other words, the transfer body 2 is divided into four regions (hereinafter, referred to as surfaces) in the rotation direction thereof, and temperature detection is performed on each surface. Ideally, the DUTY switching of the infrared heater is controlled for each surface, but high-speed control is difficult. Therefore, it is assumed that the cycle is 4.5 seconds, which is the same as the time required for one rotation of the transfer drum 41. Assuming that the four surfaces of the transfer body 2 are the A surface, the B surface, the C surface, and the D surface, the temperature of one rotation of the transfer cylinder 2, that is, the detection temperature of each surface of A to D is used in the next circuit. The duty of the infrared heater applied to the surfaces A to D is determined.

FIG. 13 is a diagram showing a simulation result showing the temperature transition of the surface temperature of the transfer material. FIG. 13 is an excerpt of the temperature transition from heating in the heating unit 5C to transfer to the recording medium. As shown in FIG. 13, when the target temperature in the heating unit 5C was changed by 10 ° C., a calculation result was obtained in which the temperature immediately before transfer changed by 5 to 10 ° C.

FIG. 14 is a diagram plotting the average value of the detected temperatures of the temperature sensors 112F, 112C, and 112R while the transfer cylinder of the recording device goes around.

In FIG. 14, the solid line is the temperature of the portion where the edge portion, which is the non-image region of the recording medium, abuts, the broken line is the detection temperature of the portion where the amount of ink applied is large in the image region, and the alternate long and short dash line is outside the abutting region 115 of the recording medium. This is the detection temperature (the temperature at which a recording medium having a size smaller than B2 + is printed). It is assumed that the temperature of the blank paper without ink is detected on the A side in the broken line and the alternate long and short dash line. Therefore, the detected temperature shows a numerical value equivalent to that shown by the solid line.

The temperature detection cycle is 500 milliseconds, and the temperature is detected by each temperature sensor at two locations on each surface of the transfer drum 41. Therefore, in FIG. 14, the detection points are shown as A1, A2, B1, B2, C1, C2, D1, and D2.

Since the broken line has a high recording duty (a large amount of ink is applied), it is detected to be lower than the actual temperature due to the latent heat of vaporization of the liquid component (moisture) of the ink. On the other hand, the alternate long and short dash line is detected at a temperature higher than the actual temperature because it does not dissipate heat due to contact with the recording medium. Further, since an infrared heater is used, the detection temperature varies depending on the color of the intermediate image on the transfer body due to the difference in the absorption characteristics of infrared light. In the recording device 1A, experimental results were obtained in which the maximum detection error due to the amount of ink applied was 10 ° C, the maximum was 7 ° C due to the ink color, and the maximum was 5 ° C due to the contact / non-contact of the recording medium. Has been done.

FIG. 15 adds the temperature profile of the temperature sensor 112 (the average value of the temperature sensors 112F, 112C, 112R) shown in FIG. 14 and the temperature change of the temperature sensor 112 after switching the DUTY of the infrared heater based on the temperature profile. It is a figure shown by. Here, the duty of the infrared heater is determined based on the average value of the detected temperatures for one round of the transfer drum 41.

According to FIG. 15, since the temperature average value for one round of the solid transfer drum 41 is 109.4 ° C., the DUTY after one round of the transfer drum 41 is substantially maintained. On the other hand, since the average temperature value for one round of the broken line transfer drum 41 is 102.4 ° C., which is lower than the set temperature 110 ° C. of the infrared heater, the DUTY after one round of the transfer drum 41 is controlled to be high. Further, since the temperature average value for one round of the alternate long and short dash line transfer drum 41 is 116 ° C., which is higher than the set temperature 110 ° C. of the infrared heater, the DUTY after one round of the transfer drum 41 is controlled to be low.

As a result, when there is a blank sheet without ink, as shown by the solid line, the temperature of the A side is maintained at a temperature close to the infrared sensor set temperature. On the other hand, when detecting a portion having a high recording duty, as shown by the broken line, the temperature of the A surface rises sharply, and the risk of damage due to high temperature and a decrease in durable life increases. Further, when detecting the outside of the contact region 115 of the recording medium, as shown by the alternate long and short dash line, the temperature of the A surface drops sharply, and when forming an image, the transferability deteriorates due to the low temperature, that is, transfer failure occurs. The risk increases.

Therefore, in step S170, it is determined whether or not the detection temperature is within a desired range (110 ° C. ± 10 ° C.), and if it is out of the range, it is determined that the recording operation can be continued, and the process returns to step 140. However, if it is out of the range, the recording operation is stopped.

As can be seen from the above studies, in order to detect the surface temperature of the transfer body 2 with high accuracy, it is necessary to detect a non-image region (blank paper portion) that the recording medium is in contact with during transfer and is not applied to the ink. It can be said that it is essential.

Therefore, according to the above-described embodiment, when the image is transferred, the temperature is detected with higher accuracy by detecting the temperature of the transfer body corresponding to the region where the recording medium is in contact and the ink is not applied. Can be done.

<Example 2>
Here, an example of detecting a non-image region in the image effective region 116 within the contact region of the recording medium with reference to the image data will be described.

FIG. 16 is a flowchart showing the detection of the surface temperature of the transfer body and the control of the heating unit according to the second embodiment. In FIG. 16, the same process step as described in the first embodiment with reference to FIG. 12 is assigned the same step reference number, and the description thereof will be omitted.

According to FIG. 16, after executing steps S110 to S120, in step S122, the image data used for image recording is read into the buffer 136. Next, in step S124, the buffer 136 is accessed, and based on the image data, it is determined whether or not there is a non-image region directly under the temperature sensor 112C, that is, in the central portion of the image effective region 116.

Here, if it is determined that there is no non-image region in the central portion of the image effective region 116, there is no region in which ink is not applied in the detectable range by the temperature sensor 112C, so the process proceeds to step S128. Then, in step S128, at least one of the temperature sensors 112F and 112R is selected so as to detect the temperature of the outer edge portion of the image effective region 116, and the detection operation is enabled. On the other hand, if it is determined that there is a non-image area in the central portion of the image effective area 116, the process proceeds to step S132, and the temperature sensors 112F, 112C, 112R are selected to enable the detection operation. At that time, the timing for detecting the temperature sensor selected from the position of the non-image region is determined.

FIG. 17 is a diagram showing an example of the relationship between the ink-applied region and the non-ink-applied region. FIG. 17 shows a state in which the transfer body 2 is viewed in the Z-axis direction, and the A side and the D side of the transfer body 2 are shown. Further, between each surface, there is a band-shaped non-inking region (non-image region) along the rotation axis of the transfer body 2, and the temperature is set at the timing of the 3500th encoder slit from the origin which is the tip of the transfer body 2. The temperature of the sensor 112C is detected.

After that, the processes of steps S140 to S170 are executed in the same manner as described in the first embodiment.

According to the embodiment described above, based on the input image data, a non-image region to which ink is not applied on the transfer body and a non-image region in the contact region of the recording medium is specified, and the non-image region is specified. Since the temperature of the place where the image is formed is detected, the temperature of the transfer material can be detected with high accuracy. Then, by performing the duty control of the infrared heater of the heating unit based on the detected temperature, the temperature of the surface of the transfer body can be maintained satisfactorily, and high-quality image recording can be performed.

<Example 3>
Here, an example will be described in which the image effective area 116 is divided into a plurality of areas, the average duty of each area is calculated, and the temperature of the area having a relatively low duty is detected.

FIG. 18 is a flowchart showing the detection of the surface temperature of the transfer body and the control of the heating unit according to the third embodiment. In FIG. 18, the same process steps as those described in Examples 1 and 2 with reference to FIGS. 12 and 16 are assigned the same step reference numbers, and the description thereof will be omitted.

According to FIG. 18, after executing steps S110 to S122, in step S131, the buffer 136 is accessed and it is checked whether or not there is a non-image area in the image effective area 116 based on the image data. Here, if it is determined that the image effective area 116 has a non-image area, the process proceeds to step S132. Then, in step S132, the process described in the second embodiment is executed. On the other hand, when it is determined that there is no non-image area, the process proceeds to step S134, and the average duty is calculated for each area in which the image effective area 116 is evenly divided into a predetermined number of divisions.

FIG. 19 is a diagram showing a method of dividing the image effective region.

According to FIG. 19, the detection area by the temperature sensors 112F, 112C, 112R is divided into four areas in the transport direction of the recording medium, and the image is taken for each of the 12 areas indicated by F1 to F4, C1 to C4, and R1 to R4. Calculate the average duty based on the data.

Returning to FIG. 18 and continuing the description, in step S136, an area having a low average duty based on the image data obtained by accessing the buffer 136 from each of F1 to F4, C1 to C4, and R1 to R4. Is extracted.

FIG. 20 is a diagram illustrating a definition of duty in duty calculation.

As shown in FIG. 20, forming four dots by ink droplets on a grid having a resolution of 600 dpi is defined as 100% duty. Therefore, if one dot is formed, the duty is 25%, if two dots are formed, the duty is 50%, and if three dots are formed, the duty is 75%.

FIG. 21 is a diagram showing an example of the calculated average duty of each area.

In step S136, in the case of the average duty of each area as shown in FIG. 21, the temperature sensor 112F selects the F1 area, the temperature sensor 112C selects the C3 area, and the temperature sensor 112R selects the R4 area. Then, the temperature is detected at the timing indicated by the predetermined encoder value.

After that, the processes of steps S140 to S170 are executed in the same manner as described in the first embodiment.

Therefore, according to the above-described embodiment, the image effective region on the transfer body is divided into a plurality of areas based on the image data, the average duty of each area is calculated, and the temperature of the region having a relatively low duty is calculated. Can be detected. As a result, the temperature of the surface of the transfer body can be detected with high accuracy even when there is no non-image region in the contact region of the recording medium such as borderless printing.

In the above-described embodiment, the temperature sensors 112F, 112C, and 112R have been described on the premise that they are fixed, but the present invention is not limited thereto. For example, it may be movable in the direction of the rotation axis of the transfer body. In this case, more accurate temperature detection is possible by moving each temperature sensor to a position where more temperature detection can be performed in the non-image area according to the size of the recording medium used and the image data. It becomes.

Further, the inspection unit 9A that inspects the image captures the image transferred to the recording medium, but the image on the transfer body is installed in a place where the image can be captured, and the imaging result is low in the non-image region or the recording duty. A region may be specified and temperature detection may be performed. For example, the photographable place is between the absorption unit 5B and the heating unit 5C.

<Other Embodiments>
In the above embodiment, the recording unit 3 has a plurality of recording heads 30, but may have one recording head 30. The recording head 30 does not have to be a full-line head, and may be a serial system that forms an ink image while scanning the recording head 30 in the Y direction.

The transport mechanism of the recording medium P may be another method such as a method in which the recording medium P is sandwiched and conveyed by a pair of rollers. In a method of transporting the recording medium P by a pair of rollers, a roll sheet may be used as the recording medium P, or the roll sheet may be cut after transfer to produce a recorded material P'.

In the above embodiment, the transfer body 2 is provided on the outer peripheral surface of the transfer drum 41, but another method such as a method in which the transfer body 2 is formed in an endless band shape and is circulated to run may be used.

The present invention is not limited to the above embodiments, and various modifications and modifications can be made without departing from the spirit and scope of the invention. Therefore, a claim is attached to make the scope of the invention public.

2 Transcript, 3 Recording unit, 4 Transcription unit, 5A granting unit,
5B absorption unit, 5C heating unit, 5D cleaning unit, 5E cooling unit,
30 recording head, 41 transfer drum, 42 impression cylinder, 111-114 temperature sensor,
103a reaction liquid storage part, 103b-103c roller, 109a cleaning liquid storage part,
109b roller, P recording medium

Claims (13)

With a rotating transcript,
A recording head that ejects ink to the transfer body to form an image,
A heating means for heating the transfer body on which the image is formed, and a heating means.
A transport means for transporting the recording medium to the transfer body, and
A plurality of detecting means for detecting the temperature of each of the plurality of places of the transfer body, and
On the surface of the transfer body, the temperature of the location of the transfer body corresponding to the area where the recording medium conveyed by the transfer means is in contact and the area where the ink is not ejected by the recording head is detected. A selection means for selecting a possible detection means from the plurality of detection means, and a selection means.
An inkjet recording apparatus comprising: a control means for controlling heating by the heating means based on a temperature detected by the detection means selected by the selection means. The inkjet recording apparatus according to claim 1, further comprising a transfer means for transferring an image from the transfer body heated by the heating means to the recording medium conveyed by the transfer means. The inkjet recording apparatus according to claim 1 or 2, wherein the selection means makes the selection based on the image data forming the image. The inkjet recording according to claim 3, wherein the selection means identifies a region on the surface of the transfer body where ink is not ejected by the recording head, based on the size of the recording medium and the image data. apparatus. Further, it has a calculation means for dividing the surface of the transfer body into a plurality of regions and calculating the recording duty for causing ink ejection to be performed in each of the divided regions based on the image data.
The inkjet according to claim 3, wherein the selection means selects a detection means for detecting a region having a low recording duty calculated by the calculation means from the plurality of detection means. Recording device. The inkjet recording apparatus according to any one of claims 1 to 5, wherein the region in which ink is not ejected by the recording head also includes a margin of the recording medium. Each of the plurality of detection means is a temperature sensor.
The inkjet recording apparatus according to any one of claims 1 to 6, wherein a plurality of the temperature sensors are provided along the rotation axis of the transfer body. The inkjet recording apparatus according to claim 7, wherein the plurality of temperature sensors are fixedly provided along the rotation axis of the transfer body. The inkjet recording apparatus according to claim 7, wherein the plurality of temperature sensors are provided so as to be movable along a rotation axis of the transfer body. The heating means includes a heater and includes a heater.
The control means according to any one of claims 1 to 9, wherein the control means heats the heater by PWM control and controls the heating capacity of the heating means by changing the duty of the PWM control. Inkjet recording device. The inkjet recording apparatus according to claim 10, wherein the control means controls the heating capacity of the heating means so that the temperature of the transfer body falls within a predetermined temperature range. The inkjet recording apparatus according to claim 11, wherein the control means controls to stop the recording operation when the temperature of the transfer body is out of the predetermined temperature range. .. A rotating transfer body, a recording head that ejects ink to the transfer body to form an image, a heating means for heating the transfer body on which the image is formed, and a transfer means for transporting a recording medium to the transfer body. It is a temperature control method in an inkjet recording apparatus including a plurality of detecting means for detecting the temperature of each of a plurality of places of the transfer body.
On the surface of the transfer body, the temperature of the location of the transfer body corresponding to the area where the recording medium conveyed by the transfer means comes into contact with the recording medium and the area where the ink is not ejected by the recording head is detected. A selection step of selecting a possible detection means from the plurality of detection means, and
A temperature control method comprising: a control step of controlling heating by the heating means based on the temperature detected by the detection means selected in the selection step.

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