IMAGE FORMING APPARATUS

An image forming apparatus disclosed herein includes: a conveying section that is provided in an apparatus main body and conveys a recording medium; a liquid droplet ejection head that ejects liquid droplets onto the recording medium which is conveyed by the conveying section; a dew condensation member that is provided around the liquid droplet ejection head and allows moisture in air to condense thereon; and a discharge section that discharges water droplets, which are condensed onto the dew condensation member, to an outside of the apparatus main body.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

Hereinafter, referring to the accompanying drawings, an image forming apparatus according to a first embodiment of the present invention will be described in detail. It should be noted that, in the drawings, the members (components) having the same or corresponding functions will be represented by the same reference signs and numerals, and description thereof will be appropriately omitted.

FIG. 1is a schematic side view of an entire configuration of an inkjet recording apparatus, which is cut along a vertical plane, as an example of an image forming apparatus according to a first embodiment of the present invention.

An inkjet recording apparatus100is an impression cylinder direct-drawing type inkjet printing apparatus that forms an image by ejecting a plurality of color inks onto a recording surface of a sheet of paper P, which is held on a drawing drum170of a drawing section116, from inkjet heads172M,172K,172C, and172Y. Further, the inkjet recording apparatus100is an on-demand type image forming apparatus to which a two-liquid reaction (aggregation) method is applied. The two-liquid reaction method forms an image on a sheet of paper P by applying a processing solution (including an aggregating agent which aggregates components in an ink composition) to the sheet of paper P before the ink ejection and making the processing solution and an ink react with each other. It should be noted that hereinafter, all of the inkjet heads172M,172K,172C, and172Y are simply referred to as “inkjet heads172”.

The inkjet recording apparatus100mainly includes a sheet feeding section112, a processing solution applying section114, the drawing section116, a drying section118, a fixing section120, and a sheet discharging section122.

The sheet feeding section112is a mechanism that feeds sheets of paper P to the processing solution applying section114. The sheets of paper P, which are cut sheets for printing, are stacked in the sheet feeding section112. The sheet feeding section112is provided with a sheet feeding tray150, and feeds the sheets of paper P one by one from the sheet feeding tray150to the processing solution applying section114.

In the inkjet recording apparatus100of the present first embodiment, a plurality of kinds of sheets of paper P having different types or sizes (paper sizes) can be used as the sheets of paper P.

The processing solution applying section114is a mechanism that applies the processing solution onto the recording surface of the sheet of paper P. The processing solution contains the aggregating agent that aggregates the components of the ink composition applied by the drawing section116. When the processing solution comes in contact with the ink, the processing solution and the ink cause the aggregation reaction. As a result, since separation between a solvent and a color material of the ink is facilitated, the ink can be prevented from bleeding or from causing landing interference (mixture) or color mixture after the ink is landed, and thus a high-quality image can be formed.

The processing solution applying section114includes a sheet feeding cylinder152, a processing solution drum154, and a processing solution coating device156. The processing solution drum154is a drum that holds a sheet of paper P and conveys the sheet of paper P by being rotated. The processing solution drum154includes claw-shaped holding means (grippers)155on the outer peripheral surface thereof, and holds the leading end of the sheet of paper P by making the sheet of paper P be interposed between the claw of the holding means155and the peripheral surface of the processing solution drum154. Suction holes may be formed on the outer peripheral surface of the processing solution drum154, and suction means, which performs suctioning from the suction holes, may be connected thereto. Thereby, the sheet of paper P can be closely held on the peripheral surface of the processing solution drum154.

The processing solution coating device156is provided outside the processing solution drum154so as to face the peripheral surface thereof. The processing solution is coated on the recording surface of the sheet of paper P by the processing solution coating device156.

The sheet of paper P, to which the processing solution is applied by the processing solution applying section114, is delivered from the processing solution drum154to the drawing drum170of the drawing section116through an intermediate conveying section126(first delivery drum).

The drawing section116includes the drawing drum170and inkjet heads172.

The drawing drum170(conveying section) includes claw-shaped holding means (gripper)171on the outer peripheral surface thereof similarly to the processing solution drum154, and the holding means171holds and fixes the leading end portion of the recording medium. Further, the drawing drum170has a plurality of suction holes formed on the outer peripheral surface, and the sheet of paper P is adhered onto the outer peripheral surface of the drawing drum170through a negative pressure. Thereby, the contact between the sheet of paper and the heads caused by floating of the sheet of paper is avoided, and the sheet of paper is prevented from jamming. Further, image unevenness caused by change in clearance from the heads can be prevented.

As described above, the sheet of paper P fixed on the drawing drum170is conveyed such that the recording surface faces the outside, and the ink is ejected onto the recording surface from the inkjet head172as the liquid droplet ejection head.

Each of the inkjet heads172M,172K,172C, and172Y (liquid droplet ejection heads) is a full-line type inkjet recording head that has the length corresponding to the maximum width of an image forming area of the sheet of paper P. A nozzle array (the surface of the nozzle array is hereinafter referred to as a nozzle surface), which has a plurality of ink ejection nozzles arranged throughout the entire width of the image forming area, is formed on the ink ejection surface of each of the inkjet heads172M,172K,172C, and172Y. Each of the inkjet heads172M,172K,172C, and172Y is installed to extend in a direction orthogonal to the conveying direction of the sheet of paper P (the direction of rotation of the drawing drum170).

The liquid droplets of the corresponding color ink are ejected from each of the inkjet heads172M,172K,172C, and172Y onto the recording surface of the sheet of paper P closely held on the drawing drum170. Thereby, the ink comes in contact with the processing solution applied to the recording surface in advance by the processing solution applying section114. Then, the color material (pigment) distributed in the ink is aggregated, and a color material aggregate is formed. In such a manner, running of the color material and the like on the sheet of paper P are prevented, and an image is formed on the recording surface of the sheet of paper P.

The drawing section116configured as described above is able to draw on the sheet of paper P in a single pass. Thereby, high-speed recording and high-speed output is possible, and productivity can be increased.

The sheet of paper P, on which an image is formed by the drawing section116, is delivered to a drying drum176of the drying section118from the drawing drum170through an intermediate conveying section128(second delivery drum). That is, the drawing drum170, the intermediate conveying section128, and the drying drum176correspond to the conveying section.

The drying section118is a mechanism that dries moisture contained in a solvent separated due to color material aggregation action, and includes the drying drum176and a solvent drying device178(drying section), as shown inFIG. 1.

The drying drum176includes claw-shaped holding means (grippers)177on the outer peripheral surface thereof, like the processing solution drum154, and holds the leading end of the sheet of paper P by the holding means177. In addition, the outer peripheral surface of the drum has suction holes (not shown in the drawing). With such a configuration, the sheet of paper P can be adhered onto the drying drum176by a negative pressure.

The solvent drying device178is disposed at the position opposed to the outer peripheral surface of the drying drum176, and is configured such that a plurality of combinations of a IR heater182and a hot-air nozzle180is disposed. The temperature and volume of hot air blown toward the sheet of paper P from the hot-air nozzle180are appropriately adjusted, thereby achieving various drying conditions. The sheet of paper P is conveyed in a state where the sheet is fixedly adhered onto the outer peripheral surface of the drying drum176such that the recording surface thereof faces the outside, and the drying process is performed on the recording surface by using the IR heater182and the hot-air nozzle180.

Further, the drying drum176has suction means of which the outer peripheral surface has the suction holes and which performs suctioning through the suction holes. Thereby, the sheet of paper P can be closely held on the peripheral surface of the drying drum176. Further, by performing negative-pressure suctioning, the sheet of paper P can be fixed onto the drying drum176, and thus the sheet of paper P can be prevented from cockling.

The sheet of paper P, which is dried by the drying section118, is delivered to a fixing drum184of the fixing section120from the drying drum176through an intermediate conveying section130(third delivery drum).

The fixing section120includes the fixing drum184, a pressing roller188(smoothing means), and an in-line sensor190. The fixing drum184includes claw-shaped holding means (grippers)185on the outer peripheral surface thereof, like the processing solution drum154, and is able to hold the leading end of the sheet of paper P by the holding means185.

The sheet of paper P is conveyed by the rotation of the fixing drum184such that the recording surface of the sheet faces the outside, and the inks are fixed onto the recording surface through a smoothing process by a pressing roller188.

The pressing roller188makes the sheet of paper P smooth by pressing the sheet of paper P on which the inks are dried. Further, the in-line sensor190measures check patterns, the amount of moisture, the surface temperature, the gloss level, and the like of the sheet of paper P, and may appropriately employ, for example, a CCD line sensor.

The sheet discharging section122is provided subsequent to the fixing section120. The sheet discharging section122is provided with a sheet discharging unit192. A fourth delivery drum194and a conveying chain196are provided between the fixing drum184of the fixing section120and the sheet discharging unit192. The conveying chain196is wound around a tensioning roller198. The sheet of paper P, which passes the fixing drum184, is sent to the conveying chain196through the fourth delivery drum194, and is delivered from the conveying chain196to the sheet discharging unit192.

In addition, in the above-mentioned configuration of the inkjet recording apparatus100, an apparatus main body200is formed of the processing solution applying section114, the drawing section116, the drying section118, and the fixing section120. Further, “the inside of the apparatus main body200” to be described later means a space including the processing solution applying section114, the drawing section116, the drying section118, and the fixing section120. Furthermore, “the outside of the apparatus main body200” means not only the outside of the inkjet recording apparatus100but also a space, such as a separate space isolated from the space inside the inkjet recording apparatus100, that has no effect on dew condensation on the nozzle surface of the inkjet head172.

<Details of Apparatus Main Body200>

FIG. 2shows the apparatus main body200, which is a principal section of the inkjet recording apparatus100of the embodiment, in an enlarged manner, and the apparatus main body200will be described in further detail.

As shown inFIG. 2, in the apparatus main body200, the processing solution drum154, the intermediate conveying section126(first delivery drum), the drawing drum170, the intermediate conveying section128(second delivery drum), the drying drum176, the intermediate conveying section130(third delivery drum), and the fixing drum184are arranged. In the apparatus main body200, the sheet of paper P is conveyed by the respective drums, and during the conveying operation, processing solution applying, drawing, drying, and fixing (hardening) are performed thereon in this order.

Here, the delivery drums126,128, and130respectively include guide members127,129, and131each of which has a rib attached thereto, and are rotated by rotation of the rotation shaft in a state where holding claws133,135, and137provided at the leading end portions of the arms extending in a direction in which the arms face each other at180degrees with the rotation shaft interposed therebetween grip the leading end portions of the sheets of paper P, thereby conveying the sheets of paper P along the guide members (127,129,131) such that the back side of the recording surface is convex in a state where the tailing end portions of the sheets of paper P are free.

It should be noted that each of the delivery drums126,128, and130may grip the sheet of paper P by using a chain gripper, and may convey the sheet in a state where the back side is convex.

In each of the delivery drums126,128, and130, there is provided a heated-air drying unit202which blows heated air to the recording surface (top surface) of the sheet of paper P facing the inside during the conveying.

In the vicinity of the entrance of the drawing drum170through which the sheet of paper P dried by the drying unit202is delivered from the first delivery drum126to the drawing drum170, there is provided a medium pressing roller204which presses the sheet of paper P toward the medium holding surface of the drawing drum170in order to smooth the cockling of the sheet of paper P conveyed to the drawing drum170.

In addition to the medium pressing roller204, a drum temperature sensor206, which detects a temperature of the drum, is provided around the drawing drum170or the drying drum176(in the embodiment, below each drum).

Further, an air temperature sensor208as a temperature sensor is provided above the second delivery drum128between the inkjet head172and the solvent drying device178which is provided on a downstream side of the inkjet head172in the conveying direction D. The air temperature sensor208detects a temperature (hereinafter referred to as an air temperature) of the air between the inkjet head172and the solvent drying device178.

A dew condensation member210, which allows moisture in air to condense and attach thereto, is provided between the inkjet head172and the solvent drying device178on each of both sides of the upstream side and the downstream side of the air temperature sensor208in the conveying direction D.

A dew condensation member210A, which is one of the two dew condensation members210, is provided above the second delivery drum128on the drawing drum170side. A dew condensation member210B, which is the other one of the two dew condensation members210, is provided above the second delivery drum128on the drying drum176side.

Axial flow fans212(air blowing sections), which blow air onto the dew condensation members210A and210B, are provided above the respective dew condensation members210A and210B.

Next, the dew condensation member210A will be described in detail.FIG. 3is a perspective view of the dew condensation member210A used in the inkjet recording apparatus100according to the first embodiment of the present invention. It should be noted that the dew condensation member210B has the same configuration as the dew condensation member210A to be described as follows, and thus a description thereof will be omitted.

The dew condensation member210A has a plate214on which the moisture in air flowing from the drying section118to the drawing section116is condensed and which is formed in a rectangular plate shape. A material, which has a higher thermal conductivity than the constituent material of the inkjet head172, is used as the constituent material of the plate214in order to increase the cooling effect of the plate214to be described later.

The plate surface214A of the plate214is long in a right-left direction (inFIG. 2, a front-back direction) as viewed from the conveying direction D of the image forming apparatus10, and the lengthwise direction L is orthogonal to the conveying direction D. Further, a widthwise direction S of the plate surface214A is at a right angle to an installation surface IS (refer toFIG. 1) of the apparatus main body200.

Inside the plate214, a coolant passage216is formed as a cooling section which cools down the plate214by flowing water as a coolant over the entire plate214. In the present embodiment, the coolant passage216extends through the plate214in a staggered manner.

An inlet216A of the coolant passage216is provided on one side surface of the plate214orthogonal to the lengthwise direction L. The inlet216A is connected to an inlet tube218A (inlet pipe) through which water flows into the coolant passage216. On the other hand, an outlet216B of the coolant passage216is provided on the other one side of the plate214orthogonal to the lengthwise direction L. The outlet216B is connected to an outlet tube218B (outlet pipe) through which water flows out from the coolant passage216.

The inlet tube218A and the outlet tube218B are connected to a cooling device33(refer toFIG. 4) as a cooling section including a pump, a water storage section, and the like. The cooling device33causes water to flow from the water storage section not shown in the drawing to the inlet tube218A and to discharge from the outlet tube218B to the water storage section again by using a pump. Further, the cooling device33constantly cools down the water stored in the water storage section.

A wiper220is disposed along the widthwise direction S of the plate214on each of both plate surfaces214A of the plate214(inFIG. 3, only the front side plate surface and wiper are shown). The wiper220has a rubber blade222which scrapes off the water droplets condensed on the plate surface214A of the plate214and drops the water droplets to a receptacle to be described later.

Further, the wiper220is connected to a support rod224which is slidably fixed onto a not-shown internal frame of the image forming apparatus10, thereby tightly pressing the blade222onto the plate surface214A of the plate214with balance.

Supporting/fixing sections226, each of which supports the wiper220and has a plate shape, are fixed onto both ends of the wiper220, respectively. One supporting/fixing section226pinches an endless belt232of a wiper driving mechanism228to be described later between the supporting/fixing section226and the wiper220, and is fixed onto the endless belt232. The other supporting/fixing section226pinches an endless belt238of a wiper driving mechanism234to be described later between the supporting/fixing section226and the wiper220, and is fixed onto the endless belt232.

The wiper driving mechanism228has a power source not shown in the drawing, a pair of pulleys230, and the endless belt232.

The pair of pulleys230is provided on the two corners on the upper side of the inkjet recording apparatus100among the four corners of the plate surface214A of the plate214, and both the pulleys are rotated by the power source in the same direction. The single endless belt232can be wound around the pair of pulleys230, and thus the single endless belt232is stretched between the pair of pulleys230along the lengthwise direction L.

Similarly to the wiper driving mechanism228, the wiper driving mechanism234has a power source not shown in the drawing, a pair of pulleys236, and the endless belt238.

The pair of pulleys236is provided on the two corners on the lower side of the inkjet recording apparatus100among the four corners of the plate surface214A of the plate214, and both the pulleys are rotated by the power source in the same direction, and are rotated in an opposite direction to the pair of pulleys230. The single endless belt238can be wound around the pair of pulleys236, and thus the single endless belt238is stretched between the pair of pulleys236along the lengthwise direction L.

With such a configuration, the wiper driving mechanisms228and234circulate the endless belts232and238in directions opposite to each other, and switch the movement directions. Thereby, the wiper220reciprocates along the lengthwise direction L, with the supporting/fixing sections226which are in direct contact with the endless belts232and238.

A discharge section240, which discharges the water droplets condensed on the plate surface214A of the plate214to the outside of the apparatus main body200, is provided below the wiper220.

The discharge section240has a receptacle242, a discharge hose244(discharge pipe), a pump246, and a reservoir can248.

The receptacle242has a tray shape. That is, the receptacle242has a rectangular parallelepiped shape extending along the lengthwise direction L, in which an opening section242A is formed on the wiper220side.

The outer surface of the receptacle242other than the side of the opening section242A is covered with a heat insulation material250such as glass wool. Further, a receiving surface242B, which receives water droplets separated from the plate surface214A of the plate214, that is, water droplets condensed on the plate surface214A and running down from the plate surface214A or water droplets scraped off by the wiper220, is formed on the bottom of the opening section242A.

The lower end of the plate214is inserted into the opening section242A and is connected to the receiving surface242B such that the receptacle242is also indirectly cooled down by the cooling of the plate214. Thus, a material with a high thermal conductivity is used as a material of the receptacle242in a similar manner to the plate214.

The receiving surface242B is inclined downward from the center to both ends in the lengthwise direction L. Discharge spouts252are provided on the lower portions of the inclinations at both ends of the receiving surface242B, respectively. Each discharge spout252is connected to a discharge hose244which discharges the water droplets of the receiving surface242B to the outside of the apparatus main body200.

The discharge hoses244, which are connected to the respective discharge spouts252, merge into one in the course of the path extending to the outside of the apparatus main body200, and are subsequently connected to the pump246. The pump246suctions water droplets on the receiving surface242B from the discharge spouts252through the discharge hoses244, and discharges the water droplets to the reservoir can248provided outside the apparatus main body200.

The reservoir can248stores the water droplets which are discharged from the discharge hose244, and disposes of the stored water droplets by releasing the connection with the pump246.

Next, the effects of the inkjet recording apparatus100according to the first embodiment of the present invention will be described.

In the inkjet recording apparatus100according to the first embodiment, the moisture in air around the inkjet head172within the apparatus main body200is condensed on the dew condensation member210. Thereby, dew condensation is inhibited from occurring on the nozzle surface of the inkjet head172. Then, the water droplets, which are condensed on the dew condensation member210, are discharged to the outside of the apparatus main body200by the discharge section240. Thereby, the condensed water droplets are inhibited from remaining on the dew condensation member210and being vaporized again. Accordingly, compared with a case where the discharge section240is not provided, it is possible to inhibit dew condensation from occurring on the nozzle surface of the inkjet head172.

In particular, in the inkjet recording apparatus100according to the first embodiment, the solvent drying device178dries the sheet of paper P onto which the ink is ejected. At this time, there is a concern that air, which includes moisture vaporized from ink or the sheet of paper P, may flow into the inkjet head172in a state where an amount of moisture of the air is larger than that of air on the upstream side of the inkjet head172in the conveying direction D.

Accordingly, in the present embodiment, the dew condensation member210is provided between the inkjet head172and the solvent drying device178. Thereby, before the air, which includes moisture vaporized from ink or the sheet of paper P, flows up to the inkjet head172, a large amount of the moisture in the air can be condensed on the dew condensation member210, and can be removed.

In the dew condensation member210, the plate214of the dew condensation member210, on which the water droplets are condensed, is cooled down by the water flowing through the coolant passage216. Hence, the moisture in air around the inkjet head172is condensed on the plate214. In addition, the water droplets, which are condensed on the plate214, are received by the receptacle242, are discharged to the outside of the apparatus main body200through the discharge hose244, and do not become stagnant in the apparatus main body200.

The inkjet recording apparatus100has the wiper220that scrapes off the water droplets, which are condensed on the surface of the plate214, and drops the water droplets to the receptacle242. Therefore, it is possible to inhibit the condensed water droplets from remaining on the plate214and being vaporized again.

The inkjet recording apparatus100has an axial flow fan212that blows air on the dew condensation member210. Thereby, in a similar manner to the water flowing through the coolant passage216, the blown air cools down the dew condensation member210, and the moisture in air flowing to the inkjet head172is condensed on the plate214. Further, the air, which is indirectly cooled down by the cooling device33, and the air within the apparatus main body200are circulated by the axial flow fan212, and thus a large amount of air flows to the plate214. Thereby, it is possible to promote dew condensation on the plate214. Furthermore, the axial flow fan212blows air onto the plate214after the moisture is condensed on the plate214, and is then able to blow the water droplets, which are condensed onto the plate214, down onto the receptacle242. Thereby, it is possible to inhibit the condensed water droplets from remaining on the plate214and being vaporized again.

The cooling device33is cooled down, whereby the receptacle242is also indirectly cooled down through the plate214. Thereby, it is possible to inhibit the water droplets, which are collected on the receptacle242, from being vaporized again by an increase in the temperature of the receptacle242. Further, the outer surface of the receptacle242is covered with a heat insulation material250. Therefore, dew condensation does not occur on the surface of the heat insulation material250, and thus it is possible to inhibit the water droplets from dropping down to the sheet of paper P.

The receiving surface242B for the water droplets is inclined, and the discharge hose244is configured to discharge the water droplets from a lower portion of the receiving surface242B by using a pump246. Thereby, the water droplets, which are received on the receiving surface242B, flow and drop down to the lower portion due to the inclination of the receiving surface242B, and flow toward the discharge hose244. Then, by causing the pump246to suction the water droplets flowing toward the discharge hose244, it is possible to promptly discharge the water droplets within the receptacle242through the discharge hose244.

One of the two dew condensation members210is provided above the second delivery drum128on the drawing drum170side, on which the air flowing to the inkjet head172is concentrated, between the inkjet head172and the solvent drying device178. Hence, it is possible to further condense the moisture in the air, which flows to the inkjet head172, on the dew condensation member210.

The water as a coolant flows through the coolant passage216formed inside the plate214, thereby cooling down the area from the inside to the surface of the plate214.

The plate surface214A of the plate214is at a right angle to the installation surface IS of the apparatus main body200. Hence, when the installation surface IS of the apparatus main body200is parallel with the ground surface, the installation surface IS is at a right angle to the plate surface214A or the ground surface. Thus, it is possible to promote dropping of the water droplets which are condensed onto the plate214.

Second Embodiment

Hereinafter, referring to the accompanying drawings, an image forming apparatus according to a second embodiment of the present invention will be described in detail. It should be noted that, in the drawings, the members (components) having functions, which are the same as or correspond to the first embodiment, will be represented by the same reference signs and numerals, and description thereof will be appropriately omitted.

In the image forming apparatus according to the second embodiment of the present invention, a configuration of a control system of the inkjet recording apparatus100, which is described in the first embodiment, will be described.

FIG. 4is a principal block diagram illustrating a configuration of a control system of an inkjet recording apparatus100according to the second embodiment of the present invention.

The inkjet recording apparatus100has a communication interface12and a system control section (system controller)14that is connected to the communication interface12.

The communication interface12is an interface section that receives image data sent from a host computer10. A serial interface such as a universal serial bus (USB), IEEE1394, Ethernet (registered trademark), wireless network, or a parallel interface such as a Centronics can be used as the communication interface12.

The system control section14is constituted of a central processing section (CPU) and peripheral circuits thereof, and the like, and the system control section14functions as a control device for controlling the whole of the inkjet recording apparatus100in accordance with a predetermined program, as well as a calculation device for performing various calculations. That is, the system control section14controls the various sections, such as the communication interface12, a sensor group30to be described later, and a device driver32, and generates control signals for controlling a heater21and a cooling device33.

The system control section14is electrically connected to an image memory16, a motor driver18, a heater driver20, a print control section22, a maintenance control section24, an image processing section26, and an EEPROM28.

The image memory16is storage means for temporarily storing the images inputted through the communication interface12, and data is written and read through the system control section14.

The image memory16stores the program executed by the CPU of the system control section14and the various types of data which is necessary for control.

The motor driver18drives a motor19in accordance with instructions from the system control section14. InFIG. 4, the motors (actuators), which are disposed in the respective sections of the inkjet recording apparatus100, are collectively represented by the reference numeral19. For example, the motor19shown inFIG. 4includes the motors which drive the intermediate conveying sections126and128, the delivery drum152, the processing solution drum154, the drawing drum170, the drying drum176, the fixing drum184, and the like, which are shown inFIG. 1.

The heater driver20drives the heater21in accordance with instructions from the system control section14. InFIG. 4, a plurality of heaters arranged in the inkjet recording apparatus100are collectively represented by the reference numeral21. For example, the heater21shown inFIG. 4includes the heater of the processing solution applying section114, the halogen heaters of the drying section118, and the like shown inFIG. 1.

The print control section22has a signal processing function for carrying out various processing, such as shaping and correction, and the like, in order to generate a print control signal from the image data in the image memory16, in accordance with the control of the system control section14. Prior to the start of printing, the print control section22also controls a processing solution applying driver22A so as to apply the processing solution onto the sheet of paper P from the processing solution coating device156, as well as supplying the generated print data (dot data) to a head driver22B. Predetermined signal processing is carried out in the print control section22, and the volume of ejected ink droplets (ejection volume) and the ejection timing of the ink droplets in the inkjet head172are controlled through the head driver22B on the basis of the image data. Thereby, the desired dot size and dot arrangement are achieved.

The maintenance control section24controls a maintenance driving section25, which drives a maintenance unit (not shown) including a cap and a cleaning blade, through the system control section14.

The image processing section26performs various kinds of image processing on the image data.

The EEPROM28is a storage section that stores various control programs and threshold values of the amount of liquid droplets, the humidity, and the temperature to be described later. The various control programs are read out from the EEPROM28, and are executed, in response to the instruction from the system control section14.

Other than the above-mentioned elements, the system control section14is electrically connected to the sensor group30, the device driver32, and a cooling control section34.

The sensor group30includes the in-line sensor190, the drum temperature sensor206, and the air temperature sensor208.

The device driver32is a driver that drives the cooling device33, the wiper driving mechanisms228and234, the axial flow fan212, and the pump246in accordance with the instruction from the system control section14.

The cooling control section34performs switching between the start and the stop of the cooling which is performed by the cooling device33, on the basis of the amount of ink which is ejected from the inkjet head172, the air temperature which is detected by the air temperature sensor208, and the drum temperature which is detected by the drum temperature sensor206. That is, the cooling control section34causes the cooling device33to start or stop flowing water into the coolant passage216.

The cooling control section34also performs switching between start and stop of driving of the wiper driving mechanisms228and234, the axial flow fan212, and the pump246, on the basis of the amount of ink, the air temperature, and the drum temperature. That is, the cooling control section34also corresponds to the wiper control section.

FIG. 5is a flowchart illustrating a flow of a process of a cooling control section34executed at predetermined intervals (for example, every 0.1 seconds) in the inkjet recording apparatus100. It should be noted that, in the following description, respective steps of the drawing are bracketed.

(S10) The cooling control section34determines whether or not a print job is input. Then, the cooling control section34advances to the process of step S12if the determination result is positive, and advances to the process of step S16if the determination result is negative.

(S12) The cooling control section34acquires the amount of ink V, which is ejected from the inkjet head172, from the image information relating to the print job. Then, the cooling control section34determines whether or not the acquired amount of ink V is greater than the threshold value Vt. The cooling control section34advances to the process of step S24if the determination result is positive, that is, if V>Vt, and advances to the process of step S14if the determination result is negative.

(S14) The cooling control section34acquires the air temperature T1 between the inkjet head172and the solvent drying device178. The air temperature T1 is detected by the air temperature sensor208. Then, the cooling control section34determines whether or not the acquired air temperature T1 is greater than the threshold value Tt1. The cooling control section34advances to the process of step S24if the determination result is positive, that is, if T1>Tt1, and advances to the process of step S16if the determination result is negative.

(S16) The cooling control section34acquires the drum temperature T2 (the highest temperature of the drum temperatures) of the drawing drum170or the drying drum176. The drum temperature T2 is detected by the drum temperature sensor206. Then, the cooling control section34determines whether or not the acquired drum temperature T2 is greater than the threshold value Tt2. The cooling control section34advances to the process of step S24if the determination result is positive, that is, if T1>Tt2, and advances to the process of step S18if the determination result is negative.

(S18) The cooling control section34causes the cooling device33to stop cooling if the cooling device33is cooling down the dew condensation member210, and advances to the process of step S20. Further, the cooling control section34directly advances to the process of step S20if the cooling device33has stopped cooling.

(S20) The cooling control section34stops the driving of the axial flow fan212if the axial flow fan212is being driven, and advances to the process of step S22. Further, the cooling control section34directly advances to the process of step S22if the driving of the axial flow fan212is stopped.

(S22) The cooling control section34stops the driving of the wiper driving mechanism228and the pump246if the wiper driving mechanism228and the pump246are being driven, and terminates the series of processes. Further, the cooling control section34directly terminates the series of processes if the driving of the wiper driving mechanism228and the pump246are stopped.

In addition, even after the cooling is stopped, the dew condensation member210is colder than the ambient air during a certain period of time, and thus dew condensation may occur on the dew condensation member210. Consequently, it is preferable that the cooling control section34stop the driving of the wiper driving mechanism228and the pump246after an interval from the stop of the cooling.

(S24) The cooling control section34causes the cooling device33to start cooling if the cooling of the cooling device33is stopped, and advances to the process of step S26. Thereby, water flows through the coolant passage216, the dew condensation member210is cooled down, and the moisture in air within the apparatus main body200is condensed on the plate214of the dew condensation member210. In addition, at a timing at which the print job is input, that is, at a timing at which an image is formed on the sheet of paper P, the series of processes may be performed. In this case, the cooling control section34causes the cooling device33to start cooling before the solvent drying device178dries the sheet of paper P.

Further, the cooling control section34directly advances to the process of step S26if the cooling device33is performing cooling.

(S26) The cooling control section34starts the driving of the axial flow fan212if the driving of the axial flow fan212is stopped, and advances to the process of step S28. Thereby, the water droplets, which are condensed onto the plate214, are blown down onto the receptacle242through the air blowing of the axial flow fan212, and the plate214is further cooled down.

Further, the cooling control section34directly advances to the process of step S28if the axial flow fan212is being driven.

(S28) The cooling control section34starts the driving of the wiper driving mechanism228and the pump246if the result is positive in step S12and if the driving of the wiper driving mechanism228and the pump246is stopped, and terminates the series of processes. Thereby, the water droplets, which are condensed onto the plate214, are scraped off and dropped onto the receptacle242by the movement of the wiper220, and are discharged from the receptacle242to the outside of the apparatus main body200through the discharge hose244by the suctioning of the pump246.

Further, the cooling control section34directly terminates the series of processes if the wiper driving mechanism228and the pump246are being driven.

As described above, according to the inkjet recording apparatus100of the second embodiment of the present invention, when the amount of ink V is greater than the threshold value Vt, the cooling device33is switched to start cooling before the solvent drying device178dries the sheet of paper P. Thereby, before the air, which contains the moisture vaporized from the sheet of paper P or the ink, begins to flow to the inkjet head172, the dew condensation member210is cooled down. As a result, compared with the case where the switching is made to start cooling after the sheet of paper P is dried, the air does not flow to the inkjet head172before the dew condensation on the dew condensation member210.

In contrast, when the amount of ink V is equal to or less than the threshold value, the cooling device33is switched to stop cooling. Therefore, the cooling, which is performed by the cooling device33, does not interfere with an increase in temperature of the drawing drum170facing the inkjet head172.

Further, the driving of the wiper driving mechanisms228and234is started when the amount of ink V is greater than the threshold value Vt, and the driving of the wiper driving mechanisms228and234is stopped when the amount of ink V is less than the threshold value Vt. Thereby, compared with the case where the wiper220is constantly being driven, it is possible to inhibit wear of the wiper220, particularly, the blade222. Furthermore, even when the air temperature T1 or the drum temperature T2 is greater than each threshold value, the driving of the wiper driving mechanisms228and234is not started, and thus it is possible to further inhibit wear of the blade222.

Further, when the air temperature T1 is greater than the threshold value Tt1, the cooling device33is switched to start cooling. Thereby, the high-temperature air flows from the solvent drying device178side to the inkjet head172side, and it is possible to inhibit drying of the nozzle surface of the inkjet head172.

In contrast, when the air temperature T1 is less than the threshold value Tt1, there is less concern about the drying of the nozzle surface, and thus the cooling device33is switched to stop cooling. Thereby, it is possible to reduce energy consumed in the cooling.

Further, when the drum temperature T2 is greater than the threshold value Tt2, the cooling device33is switched to start cooling. Thereby, it is possible to cool down the drum when the drum is overheated. In addition, the temperature of the drawing drum170may be intended to be aggressively increased. In such a case, even when the drum temperature T2 is exceptionally greater than the threshold value Tt2, the cooling device33does not have to be switched to start cooling.

In contrast, when the drum temperature T2 is less than the threshold value Tt2, the cooling device33is switched to stop cooling. Thereby, it is possible to reduce energy consumed in the cooling.

Third Embodiment

Hereinafter, referring to the accompanying drawings, an image forming apparatus according to a third embodiment of the present invention will be described in detail.

The image forming apparatus according to the third embodiment of the present invention has the same configuration as the inkjet recording apparatus100, which is described in the first embodiment, except the dew condensation member.

FIG. 6is a perspective view of a dew condensation member210C used in the image forming apparatus according to the third embodiment of the present invention.

The dew condensation member210C has the plate214and the coolant passage216, similarly to the dew condensation member210A. Further, the wiper220is disposed on one plate surface214A of the plate214. The wiper220is reciprocated along the lengthwise direction L by the wiper driving mechanisms228and234.

A discharge section260, which discharges the water droplets condensed on the plate214to the outside of the apparatus main body200, is provided below the wiper220.

The discharge section260has a receptacle262, the discharge hose244, the pump246, and the reservoir can248.

In the receptacle262, the plate member is formed in an L shape so as to extend from the lower end of the plate surface214A, and the opening section262A is formed on the wiper220side.

The outer surfaces of the receptacle242other than the opening section242A side and the surfaces other than one plate surface214A of the plate214are covered with a heat insulation material264.

As described above, according to the dew condensation member210C of the third embodiment of the present invention, the wiper220is disposed on only one plate surface214A of the plate214. Therefore, compared with the dew condensation member210A in which the wipers220are disposed on both plate surfaces214A, it is possible to reduce the entire size of the dew condensation member210C, and it is possible to provide the dew condensation member210C even at a location with a narrow space.

Further, the surfaces other than one plate surface214A of the plate214are covered with the heat insulation material264. Hence, the water droplets are inhibited from flowing and dropping down from the other surfaces.

Fourth Embodiment

Hereinafter, referring to the accompanying drawings, an image forming apparatus according to a fourth embodiment of the present invention will be described in detail.

The image forming apparatus according to the fourth embodiment of the present invention has the same configuration as the inkjet recording apparatus100, which is described in the first embodiment, except a part of the apparatus main body.

FIG. 7is an enlarged side view of an apparatus main body300as a principal part of the image forming apparatus according to the fourth embodiment.

The apparatus main body300has the same configuration as the apparatus main body200, but does not have the dew condensation member210B and the axial flow fan212, compared with the apparatus main body200. Further, the apparatus main body300has a temperature and humidity sensor302, which detects the humidity and the temperature between the inkjet head172and the solvent drying device178, instead of the air temperature sensor208.

In the apparatus main body300, in addition to the dew condensation member210A, a dew condensation member310, which condenses the moisture in air, is provided between the inkjet head172M and the inkjet head172K.

Likewise, the dew condensation members310are also provided between the inkjet head172K and the inkjet head172C and between the inkjet head172C and the inkjet head172Y.

As described above, according to the image forming apparatus of the fourth embodiment of the present invention, the moisture in air is condensed on the dew condensation member310. Here, the moisture contains the moisture vaporized immediately after the ink ejection. Therefore, it is possible to further inhibit dew condensation on the nozzle surface of the inkjet head172.

Further, the apparatus main body300has the temperature and humidity sensor302. With such a configuration, the cooling control section34, which is described in the second embodiment, may perform switching between the start and the stop of the cooling of the cooling device33, on the basis of the humidity which is detected by the temperature and humidity sensor302, instead of the amount of ink which is ejected from the inkjet head172.

Modified Example

It should be noted that, although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the embodiments mentioned above, it will be readily apparent to those skilled in the art that various embodiments can be made without departing from the scope of the present invention. In addition, the above-mentioned plural embodiments and modified examples can be appropriately combined.

For example, the first embodiment described the case where the wiper220is provided, but the wiper220may be removed. The reason is that the water, which is condensed on the plate214, can be blown down onto the receptacle242by the axial flow fan212without the wiper220.

Further, the axial flow fan212may also be removed together with the wiper220. The reason is that, even in such a case, the condensed water droplets separate and drop from the plate surface214of the plate214when the plate surface214A of the plate214has high water repellency or high hydrophilicity. The material of the plate214does not have to have water repellency or hydrophilicity, and the plate214may be coated with a water-repellent material or a hydrophilic material.

Furthermore, in order to regulate the direction in which the water droplets flow and drop, a vertical groove may be provided on the plate214.

Moreover, the cooling device33may be removed. Even in such a case, when the plate214is formed of a material which has a higher thermal conductivity than the inkjet head172and by which dew condensation tends to occur, the moisture in air is condensed on the plate214, thereby inhibiting dew condensation on the nozzle surface of the inkjet head172. When the material of the inkjet head172is plastic, glass, ceramic, or silicone, the available material of the plate214is a material, which has a higher thermal conductivity than the above-mentioned materials, for example a metal material such as aluminum or copper.

In addition, in the above description, the receptacle242is indirectly cooled down by the cooling of the cooling device33, but may be directly cooled down. That is, the coolant passage216may be provided inside the receptacle242.

Further, in the above description, the wiper220may be reciprocated along the lengthwise direction L, but the wiper220may be rotated.

Furthermore, in the above description, one or two dew condensation members210are provided between the inkjet head172and the solvent drying device178(refer toFIGS. 2 and 7), but three or more dew condensation members210may be provided. Further, the dew condensation member210does not have to be provided between the inkjet head172and the solvent drying device178as long as the member is provided around the inkjet head172. For example, the dew condensation member210may be provided upstream of the inkjet head172in the conveying direction D.

Moreover, examples of the cooling section, which cools down the dew condensation member210, include water cooling means using the coolant passage216, air cooling means including the axial flow fan212, a Peltier device, and the like.

In addition, as the air blowing section which blows air onto the dew condensation member210, a blowing section such as a centrifugal fan or a blower other than the axial flow fan212may be used. In addition, a compressed-air source, an air tube, an air blowing nozzle, a spray device, or the like may be used.

Further, the discharge section240, which discharges the water droplets condensed on the dew condensation member210to the outside of the apparatus main body200, may be configured such that the receptacle242or the pump246is removed from the configuration shown inFIG. 3.

Furthermore, as the conveying section which conveys the sheet of paper P, other than the cylinder (drum), a conveying roller or an electrostatic adsorption conveying belt, which keeps the sheet of paper P elestrostatically attached thereon and conveys the sheet of paper P, may be used.

In the above description, the cooling control section34controls not only the cooling device33, but also controls all of the wiper driving mechanisms228and234, the fan212, and the pump246. However, the cooling control section34may control only the cooling device33. In this case, each device may be individually provided with a control section.

Further, the embodiment exemplifies the configuration of CMYK standard colors (four colors), but a combination of color numbers or ink colors is not limited to the embodiment, and a tint color ink, a concentrated ink, and a special color ink may be added as necessary. For example, a configuration, in which the inkjet head ejecting the light inks such as light cyan and light magenta may be added, is possible, and the order of arrangement of respective color heads is also not particularly limited.

Furthermore, the embodiment describes the example of the inkjet recording apparatus100, which is the inkjet type using inks, as the image forming apparatus. However, the ejection liquid is not limited to inks for printing images and characters, and various ejection liquids (liquid droplets) may be applicable if the liquids use solvents or dispersion media capable of soaking into the sheet of paper P.

Moreover, in the embodiment, as the recording medium, the sheet of paper P is exemplified, but a recording medium such as yarn, fiber, textile, leather, metal, plastic, glass, wood, or ceramics, etc., and e.g., OHP may be used.