JP5371879B2 - Recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an energy-efficient recording apparatus that properly moisturizes a running recording head. <P>SOLUTION: The recording apparatus includes: a humidifier for generating humidified air; a first supply port for supplying a first humidified air to a sheet to be conveyed; a second supply port positioned closer to an inkjet recording head than the first supply port, for supplying a second humidified air to a space where the nozzles of the inkjet recording head are exposed; and a recovery duct for recovering a part of the first humidified air supplied from the first supply port, and sending back the recovered air to the humidifier. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a recording apparatus capable of suppressing drying of ink of an ink jet recording head.

  In Patent Document 1, in a printer in which a plurality of inkjet recording heads are arranged side by side in the sheet conveyance direction, the recording head is moisturized by supplying a humidified gas from the upstream side to the vicinity of the nozzles of the recording head and flowing the ink. A technique for suppressing drying is disclosed.

JP 2000-255053 A

  A sheet made of paper or the like has an equilibrium moisture content corresponding to the humidity (the moisture content of the sheet does not change any more). If the humidity is high, it absorbs moisture in the air, and if the humidity is low, it is in the sheet. Releases moisture. When the sheet is supplied in the vicinity of the recording head in a state where the humidity is increased due to the supply of humidified air, moisture adsorption by the sheet occurs. For this reason, the humidity of the atmosphere may decrease, and the recording head may not be properly moisturized. In particular, in a configuration in which a plurality of recording heads are provided side by side along the direction of introduction of humidified air, it takes time for the humidified gas supplied from the upstream to travel downstream, and moisture is adsorbed by the sheet during that time. Then, the moisture of the downstream recording head tends to be insufficient. Insufficient moisturization may cause ink ejection failure such as inability to eject ink or disorder in the ejection direction. Moreover, since generation of humidified air requires a large amount of energy, a device for efficient humidification is desired.

  The present invention has been made based on recognition of the above-described problems. An object of the present invention is to provide a recording apparatus that can appropriately maintain the moisture retention of the recording head, suppress ejection failure, and has high energy efficiency.

Recording apparatus of the present invention includes a recording unit including an ink jet recording head in which the nozzles are formed, and a humidifier for generating the humidified air, a first humidification generated by the humidifying section to the sheet to be conveyed Closer to the inkjet recording head than the first supply port for supplying the first supply port for supplying air and the second humidified air generated by the humidifying unit to the space where the nozzle is exposed. possess a second supply port provided at a position, and the collection duct for re-introduced into the humidifying unit to recover a portion of the first humidified gas supplied from the first supply port The absolute humidity of the first humidified air is higher than the absolute humidity of the second humidified air .

  According to the present invention, moisture adsorption by the sheet is suppressed by humidifying the sheet in advance before the recording unit, moisture retention of the recording head can be appropriately maintained, and ejection failure can be suppressed. At this time, a portion of the humidified air that has not been adsorbed to the sheet is recovered and reused, so that the device is highly efficient in using water and has high energy efficiency.

It is a figure which shows the hysteresis characteristic of a sheet | seat. It is a block diagram of embodiment of an inkjet recording device. It is the figure which looked at the recording part from the A direction. It is a block diagram of a humidified air production | generation part. It is a block diagram of a control system. It is a schematic diagram of a recorded image. FIG. 6 is an enlarged schematic diagram of a recording image writing unit when recording is performed.

  Prior to the description of embodiments of the present invention, hysteresis characteristics of a sheet as a recording medium, for example, inkjet glossy paper, will be described. FIG. 1 shows hysteresis characteristics regarding moisture adsorption and desorption. In paper such as inkjet glossy paper, the relationship between moisture adsorption and desorption due to changes in relative humidity is not linear. When the atmospheric humidity changes from point A having a low relative humidity to point B having a high relative humidity, the inkjet glossy paper adsorbs moisture in the atmosphere. On the other hand, when the relative humidity is lowered from point C having a higher relative humidity to the same relative humidity as point B, the amount of water contained in the inkjet glossy paper contains water up to the amount of point D higher than point B. That is, when the inkjet glossy paper is exposed to a certain relative atmospheric humidity, the inkjet glossy paper can contain more water when the relative humidity is changed from a lower relative humidity than when the relative humidity is changed from a lower relative humidity. Furthermore, when the relative humidity is changed from the point C having a higher relative humidity to the point D relative humidity, the amount of moisture released from the inkjet glossy paper is small. For this reason, when the inkjet glossy paper is exposed again to a relative humidity of point C or higher, the amount of moisture adsorbed by the inkjet glossy paper is smaller when changing from the D point than when changing from the B point.

  That is, if moisture is intentionally adsorbed on the sheet before it is conveyed into the recording unit, it is possible to suppress moisture adsorption on the sheet even in a state where the relative humidity in the recording unit is high. Therefore, even when the relative humidity around the recording head is increased so that the ink does not evaporate from the recording head, moisture adsorption by the sheet is suppressed, so that the relative humidity around the recording head is kept high. And drying of the ink can be suppressed. The present invention is based on such consideration.

  FIG. 2 is a configuration diagram of the ink jet recording apparatus according to the embodiment of the present invention, and FIG. 3 is a configuration diagram when the recording unit 9 of the ink jet recording apparatus of FIG. 2 is viewed from the A direction. The black arrows in the figure indicate the flow of humidified humidified air. In the present embodiment, humidified air is used, but humidified gas other than air may be used. In this specification, “air” is a general term for air and gases other than air. In this specification, the direction close to the sheet supply side at an arbitrary position in the sheet conveyance path is referred to as “upstream”, and the opposite side is referred to as “downstream”.

  The recording apparatus of this example is a so-called roll-to-roll system. The supply roller 41 supplies the sheet 2 that is a continuous sheet wound in a roll shape. The winding roller 42 winds up the sheet that has been recorded by the recording unit 9 in a roll shape.

  The recording unit 9 has a housing indicated by a dotted line in FIG. 2. The recording unit 9 is provided with a transport mechanism and a recording unit inside the housing, and is unitized. The transport mechanism includes a platen 7 that assists in supporting the sheet 2, and a plurality of roller pairs including a driving roller 6 and a driven roller 5. A part of the driving roller 6 is embedded in the platen 7 in a rotatable state, and is rotated by a driving source to convey the sheet. The driven roller 5 is supported by a support member 8 (holder), and is disposed at a position facing the driving roller 6 with the sheet 2 interposed therebetween. A recording head 1 that constitutes a recording unit is provided between a pair of rollers of the driving roller 6 and the driven roller 5. The recording head 1 is a fixed full-line type line-type inkjet recording head in which nozzles that eject ink over the maximum recording width in the width direction of the sheet 2 are formed. The ink jet method is a method using a heating element in this example, but is not limited thereto, and can be applied to a method using a piezo element, an electrostatic element, or a MEMS element. The recording heads 1 are arranged in the conveyance direction by the number of colors (six colors in FIG. 2) along the sheet conveyance direction, and the plurality of recording heads 1 are integrally held by the support member 8. Ink is supplied to the recording head 1 from ink supply means (not shown) such as an ink tank. Each recording head 1 may be a unit integrated with an ink tank that stores ink of the corresponding color. The recording unit 9 forms an image by applying ink of each color to the moving sheet 2 by the recording head 1 of each color by a line printing method. In this example, roll paper is used as the sheet 2, but there is no limitation on the type of continuous paper or cut paper folded for each unit length.

  A first humidification duct 4 and a recovery duct 43 are provided upstream of the recording unit 9 in the sheet conveyance path. The first humidification duct 4 ejects the humidified air produced by the humidified air generation unit 21 from the supply port 4a (first supply port) and blows it onto the sheet 2. The first humidification duct 4 supplies humidified air (first humidified air) to the sheet 2 before entering the recording unit 9 to increase the moisture content of the sheet. A blower fan 4b for generating an air flow is provided in the middle of the first humidification duct 4.

  Of the humidified air blown from the first humidifying duct 4 to the sheet 2, a part of the humidified air that has not been adsorbed to the sheet 2 is sucked and recovered from the recovery port 43 a of the recovery duct 43, The air is returned to the intake port 23 of the humidified air generation unit 21. In order to generate an airflow for returning, a blower fan 43b is provided in the middle of the recovery duct 43. The collection duct 43 may be located anywhere as long as the humidified air from the first humidification duct 4 that has not been adsorbed to the sheet 2 can be collected. The blower fan 4b and the blower fan 43 rotate so that the flow rate of the humidified air supplied from the supply port 4a and the flow rate of the humidified air recovered by the recovery duct 43 are equivalent (meaning equal or substantially equal). . The humidified air returned by the recovery duct 43 is introduced into the humidified air generation unit 21 and reused. Since the utilization efficiency of humidified air is increased by reuse, consumption of humidified water can be suppressed. Further, since the humid air is prevented from diffusing to another unit of the recording apparatus, troubles of the electric system due to condensation and corrosion of the metal part due to long-term use are unlikely to occur.

  In addition to the first humidification duct 4, a second humidification duct 3 is provided for sending humidified air into a narrow space where the nozzles of the recording head 1 in the recording unit 9 are exposed. By the second humidification duct 3, humidified air (second humidified air) is sent from the sheet inlet of the recording unit 9 to increase the atmospheric humidity in a narrow space where the nozzles of the plurality of recording heads 1 are exposed. . Thereby, the nozzles of the plurality of recording heads are moisturized and drying is suppressed. The 2nd humidification duct 3 is provided with the ventilation fan 3b in the middle, and the humidification air produced | generated by the humidification air production | generation part 21 is ejected from the supply port 3a (2nd supply port). The supply port 3 a is provided in the vicinity of the sheet introduction port of the sheet 2 of the recording unit 9. The first humidifying duct 4 is located upstream of the supply port 4 a of the first humidifying duct 4, the recovery port 43 a of the collecting duct 43, and the supplying port 3 a of the second humidifying duct 3 as viewed from the recording unit 9.

  The humidified air supplied by the second humidifying duct 4 flows from upstream to downstream in the recording unit 9 in the conveyance path of the sheet 2 and a narrow space in the vicinity thereof. Specifically, at the position of the recording head 1, the recording head 1 passes through a gap (hereinafter referred to as “recording gap”) between the tip of the recording head 1 (surface on which the nozzle is formed) and the sheet 2. Further, between the adjacent recording heads 1, the humidified air passes through a gap formed between the support member 8 and the sheet 2. The humidified air is transmitted to the recording head 1 on the downstream side while passing through the two kinds of gaps. In the ink jet system, the recording gap is usually as narrow as about 1 mm. When the humidified air passes through the recording gap, the flow rate of the humidified air increases, which adversely affects the landing accuracy of the ejected droplets (main droplets and satellite droplets) ejected from the recording head 1 during recording. May affect. Therefore, it is desirable to set the humidified air supplied from the second humidifying duct 3 so that the flow velocity in the recording gap is 1 m / second or less.

  A reflux duct 44 is provided to collect a part of the humidified air that has flowed from the upstream to the downstream in the conveyance path of the recording unit 9 and the narrow space in the vicinity of the recording unit 9 and reintroduced into the humidified air generating unit 21. It has been. The reflux duct 44 is provided with a suction port 44a and a blower fan 44b for generating an air flow. The suction port 44a is provided in the vicinity of the sheet outlet port of the recording unit 9, and efficiently collects humidified air that flows from upstream to downstream along the sheet conveyance path. The humidified air returned by the reflux duct 44 is introduced into the humidified air generation unit 21 and reused. The two recovery mechanisms of the recovery duct 43 and the reflux duct 44 described above have very high utilization efficiency of the humidified air, consume less humidified water, and prevent the humidified air from diffusing to another unit of the recording apparatus. Is done.

  FIG. 4 is a configuration diagram showing a detailed structure of the humidified air generating unit 21. In the humidified air generating unit 21, a first humidifying chamber 21a and a second humidifying chamber 21b are connected in series, and the first humidifying chamber 21a and the second humidifying chamber 21b are housed and integrated in one housing. . The first humidification chamber 21a and the second humidification chamber 21b are partitioned by a wall 30 inside the housing. The first humidification chamber 21a is provided with an introduction port 23a, a heating element 24a (heater), a humidification filter 26a, a fan 27a, and a jet outlet 27. The first humidifying chamber 21a further includes a temperature sensor 28a for detecting the temperature in the first humidifying chamber 21a and controlling the amount of heat generated by the heating element 24a, and temperature and humidity for measuring the gas humidity in the first humidifying chamber 21a. A sensor 29a is provided. The second humidifying chamber 21b is provided with a heating element 24b, a humidifying filter 26b, a fan 27b, and a jet outlet 23b. The second humidifying chamber 21b further includes a temperature sensor 28a for detecting the temperature in the second humidifying chamber 21b and controlling the amount of heat generated by the heating element 24b, and a temperature / humidity for measuring the gas humidity in the second humidifying chamber 21b. A sensor 29b is provided. Humidification water 25 for humidification is accumulated at the bottoms of the first humidification chamber 21a and the second humidification chamber 21b. The humidified water 25 is supplied from a tank (not shown). The first humidification chamber 21a and the second humidification chamber 21b are connected at the bottom, and the humidified water 25 accumulated at the bottom is shared by the first humidification chamber 21a and the second humidification chamber 21b. There is a wall 30 for partitioning the room between the first humidifying chamber 21a and the second humidifying chamber 21b in a state where the humidifying water 25 is accumulated. The water 25 is shared by the first humidification chamber 21a and the second humidification chamber 21b. As another form, the first humidifying chamber 21a and the second humidifying chamber 21b may be all partitioned by the wall 30, and the portions below both water surfaces may be connected by a tube. By sharing in this way, the water surface height of the humidifying water 25 is the same in the first humidifying chamber 21a and the second humidifying chamber 21b, and one of them does not disappear first. The humidified water 25 is water (for example, tap water) that can be easily supplied at a low cost, but is not limited to this, and may be a solution containing a component that prevents the ink of the recording head from drying.

  The humidified air generating unit 21 is a hybrid type vaporizing humidification system. Both the humidifying filters 26a and 26b are hollow cylindrical (roller-shaped) rotating bodies made of a material that has high water absorption and allows gas to pass through. The lower portions of the humidifying filters 26a and 26b are immersed in the humidifying water 25, and the whole is wet by rotating. When the heated gas is blown onto the humidifying filter, the gas passes through one humidifying filter from the outside to the inside, then passes from the inside to the outside, and is humidified by passing twice in total. Since each of the humidifying filters 26a and 26b passes twice, it passes a total of four times. Both the humidifying filters 26a and 26b rotate in the same direction. The rotation direction is counterclockwise in FIG. 3, that is, when the hollow cylinder of the humidification filter is divided into left and right, the side (right side) closer to the introduction port (heating element) to the humidification chamber is above the surface of the humidification water 25. The rotation direction is such that the far side (left side) sinks below the water surface. Immediately after coming out of the surface of the water, the amount of water retained in the filter is larger and gradually decreases with rotation. Therefore, since the higher-temperature gas immediately after being heated by the heating element passes through the filter having a higher moisture retention amount (the state on the right side), the humidification efficiency is increased. Since both the first humidification chamber 21a and the second humidification chamber 21b are humidified with high efficiency, extremely high humidification efficiency is obtained as a whole. By operating the fan 27a and the fan 27b at the same time, outside air is introduced into the first humidification chamber 21a from the introduction port 23a, passes through the inside, and humidified air humidified to high humidity is ejected from the ejection port 23b. The rotation speed of the fans 27a and 27b, the heat generation amount of the heating elements 24a and 24b, and the rotation speed of the humidifying filters 26a and 26b can be controlled to be variably set. With these controls, the operating capacity of the humidified air generating unit 21 is variably adjusted.

  If a humidified gas having a humidity in the above numerical range is generated in one humidifying chamber, a humidifying portion larger than the two-chamber structure of this example is required. If the same humidified gas is generated in one humidification chamber, the flow rate of the air passing through the humidification filter must be slowed in order to increase the vaporization efficiency. Therefore, in order to ensure a desired flow rate, it is necessary to increase the passage area of the humidifying filter, and as a result, the size of the humidifying filter becomes very large. According to this example, by dividing the humidification chambers and connecting them in series, the number of times of passage through the humidification filter can be increased, so that the humidification efficiency is high, and a small humidification filter is sufficient, so the whole is compact. . As a result, a recording apparatus excellent in size, cost, and energy efficiency of the entire apparatus is realized.

  Chalk components, fine dust, and the like contained in the humidified water are unnecessary components that cause clogging and the like for the ink nozzles, and thus are not preferable when introduced into a narrow space. Since the humidifying filters 26a and 27b are vaporization type, components other than water are trapped in the water absorbing body of the humidifying filter, and scattering into the space is suppressed. That is, vaporization type humidification using a filter as in this example is suitable for moisture retention of an ink jet recording head. In other words, by adopting vaporization-type humidification, it is possible to use tap water that has many unnecessary components but is inexpensive and easy to supply as humidified water.

  The humidity of the 1st humidification air supplied from the 1st humidification duct 4 and the 2nd humidification air supplied from the 2nd humidification duct 3 is demonstrated. The atmosphere around the recording head 1 needs to be an atmosphere in which ink does not easily evaporate from the recording head 1. For example, if the temperature is 30 to 40 ° C., the relative humidity is about 60 to 70%. Therefore, in the second humidification duct 3, it is preferable to set the relative humidity to about 60 to 70%, but this is not limited as long as the ink can be prevented from evaporating from the recording head 1. In the 1st humidification duct 4, it is preferable to make a sheet | seat 2 adsorb | suck a water | moisture content so that it may become an equilibrium moisture content. Since the amount of water that can be adsorbed varies depending on the type of the sheet 2, as a guideline, air that has been humidified to an absolute humidity equal to or higher than the absolute humidity of the humidified air supplied from the second humidifying duct 3 is used as the first standard. What is necessary is just to supply to the sheet | seat 2 from the humidification duct 4 of this.

  FIG. 5 is a block diagram of a control system of the ink jet recording apparatus of this example. Character or image data to be recorded is input from the host computer 10 to the reception buffer 11 of the ink jet recording apparatus. Further, data for confirming whether the data is correctly transferred, and data for notifying the operation state of the ink jet recording apparatus are output from the ink jet recording apparatus to the host computer 10. The data in the reception buffer 11 is transferred to the memory unit 13 and temporarily stored in the RAM under the control of the CPU 12 as a control unit. The mechanical control unit 14 drives a mechanical unit (mechanical unit) 15 such as a line head carriage, a cap, and a wiper in response to a command from the CPU 12. The sensor / SW (switch) control unit 16 sends a signal from the sensor / SW unit 17 including various sensors and SW (switch) to the CPU 12. The display element control unit 18 controls the display element unit 19 composed of an LED of a display panel, a liquid crystal display element, and the like according to a command from the CPU 12. The humidification control unit 20 controls the humidified air generation unit 21 according to a command from the CPU 12. At this time, the CPU 12 determines the amount of moisture to be supplied to the sheet 2 from various information, for example, the environmental temperature, the type and thickness of the sheet 2, the temperature of the line head, and the amount of image data to be recorded. The humidification condition of the humidified air generation unit 21 is set. The recording head control unit 22 drives and controls the recording head 1 according to a command from the CPU 12, detects temperature information indicating the state of the recording head 1, and transmits the detected temperature information to the CPU 12.

  In the above configuration, the first humidification duct 4 is provided on the upstream side of the sheet conveyance path from the recording unit 9, and supplies the first humidified air to the sheet before entering the recording unit 9. Thereby, the moisture content of the sheet is increased before entering the recording unit 9. The second humidification duct 3 supplies the second humidified air from the sheet introduction port so that the humidified air flows from the upstream to the downstream in the sheet conveyance path of the recording unit 9. In the recording unit 9, the second humidified air is sent in advance before the sheet is introduced to increase the atmospheric humidity in a narrow space where the nozzles of the recording head 1 are exposed, and the recording head is moisturized. Here, when the sheet for recording passes through the recording portion, the sheet is already in a state in which the moisture content is increased by the first humidification duct 4, so the sheet 2 adsorbs moisture in a narrow space. It is suppressed. Therefore, high humidity is maintained in the narrow space from the upstream recording head 1 to the downstream recording head 1, and the recording head is reliably moisturized (inhibition of water evaporation of ink). As a result, it is possible to suppress the occurrence of ink discharge defects such as ink being unable to be discharged or the discharge direction being disturbed.

  In the above configuration, the first humidification duct 4 is provided on the upstream side of the sheet conveyance path from the recording unit 9, and supplies the first humidified air to the sheet before entering the recording unit 9. Thereby, the moisture content of the sheet is increased before entering the recording unit 9. The second humidification duct 3 supplies the second humidified air from the sheet introduction port so that the humidified air flows from the upstream to the downstream along the conveyance path of the recording unit 9. In the recording unit 9, the second humidified air is sent in advance before the sheet is introduced to increase the atmospheric humidity in a narrow space where the nozzles of the recording head 1 are exposed, and the recording head is moisturized. Further, when viewed as an operation, in the first step, the first humidified air is supplied from the first supply port to the conveyed sheet to increase the moisture content of the sheet. At the same time, in the second step, the second humidified air is supplied from a second supply port provided closer to the recording head than the first supply port to the narrow space where the nozzles are exposed, thereby reducing the atmosphere in the narrow space. Increase the humidity and keep the nozzle moist. In the third step, the portion of the sheet whose water content is increased in the first step is entered into the narrow space where the atmospheric humidity is increased in the second step, and recording is performed with the ink jet recording head.

  As a result, when the sheet passes through the space during recording, the sheet is in a state where the moisture content has been increased by the first humidified air in advance, so that the sheet absorbs the moisture of the second humidified air. Is suppressed. Therefore, high humidity is maintained in the narrow space from the upstream recording head to the downstream recording head, and the nozzle is reliably moisturized. As a result, it is possible to suppress the occurrence of ink discharge defects such as ink being unable to be discharged or the discharge direction being disturbed.

  In addition, the humidified air returned by the recovery duct 43 is returned to the humidified air generating unit 21 and reused. Further, part of the humidified air is also returned to the humidified air generating unit 21 for reuse by the reflux duct 44. For this reason, utilization efficiency of humidified air increases and consumption of humidified water is suppressed. Further, since the humid air is prevented from diffusing to another unit of the recording apparatus, troubles of the electric system due to condensation and corrosion of the metal part due to long-term use are unlikely to occur.

  In addition, the humidified air generator 21 has a structure in which a plurality of humidification chambers are connected in series, so that the humidification efficiency is high, and a small humidification filter is sufficient, so that the whole is compact. Further, the humidified air generating unit 21 is shared by the first humidifying duct 4 and the second humidifying duct 3. As a result, a recording apparatus excellent in size, cost, and energy efficiency of the entire apparatus is realized.

  Below, the example experimented using the inkjet recording device of the above-mentioned structure is demonstrated.

Example 1
The recording head 1 has six colors of black, cyan, photocyan, magenta, photomagenta, and yellow having a recording width of 6 inches. As sheet 2, glossy roll paper for ink jet having a width of 5 inches was set, and continuous image recording with an image size of 5 × 7 inches was performed. At this time, the atmosphere around the ink jet recording apparatus was a temperature of 25 ° C. and a relative humidity of 55%. Regarding the moisture content of the roll paper which is the sheet 2, when the moisture content of the roll paper was measured using an electric moisture meter (main body: MR-200, probe: KG-PA) manufactured by Sanko Electronics Laboratory Co., Ltd. About 6%. Prior to image recording, the ink in the nozzles was refreshed by performing “disposal discharge” of the recording head 1 in the cap, and then the cap was retracted and the recording head 1 was moved to the image recording position.

  In parallel with the series of operations, the humidified air produced by the humidified air generating unit 21 and having a temperature of 30 ° C. and a relative humidity of 85% is passed through the second humidifying duct 3 into the recording unit 9 at a speed of 0.2 m / s. I started sending out. At this time, the wind speed under the recording head 1 is 0.9 m / s, and the flow rate does not cause the problem of deteriorating the landing system of the main droplets and the harmful effect on the image due to the landing of the satellite droplets separated from the main droplets. Met. Since the dew point of air at a temperature of 30 ° C. and a relative humidity of 85% is 27 ° C., the temperature inside the recording apparatus exceeds 27 ° C. after the operation of the ink jet recording apparatus is started, and then the second humidifying duct 3 is used. The supply of humidified air was started. A specific atmosphere in the recording apparatus was a temperature of 32 ° C. and a relative humidity of 37%. In the ink jet recording apparatus, the temperature inside the apparatus rises by adjusting the temperature of the recording head 1 or using a dryer, etc. However, if the temperature outside the apparatus is low, such as in winter, it takes time until the apparatus warms up. A heating means such as a heater may be provided separately.

Next, the first humidifying duct 4 made by the humidified air generating unit 21 and humidified to a temperature of 30 ° C. and a relative humidity of 85% (absolute humidity of 25.8 g / m ³ ) is 150 × 40 mm at a speed of 1.3 m / s. To the surface of the roll paper. At this time, the amount of water supplied to the roll paper is about 0.2 g / sec, and the amount of water supplied increases to about 720 g per hour. However, of the air supplied from the first humidification duct 4, the air that is not adsorbed by the roll paper is returned to the intake port of the humidified air generation unit 21 through the recovery duct. The water recovery rate at this time is approximately 95%, and the amount of water consumed in the working system is reduced to 36 g per hour. When the moisture content of the roll paper humidified by blowing humidified air through the first humidifying duct 4 was measured, it was about 13%.

  In this way, the temperature and relative humidity in the vicinity of the front end of the recording head 1 in the state where the humidified air produced by the humidified air generating unit 21 is supplied via the first humidifying duct 4 and the second humidifying duct 3. Was measured. As a result, the most upstream recording head 1 has a temperature of 30 ° C. and a relative humidity of 80%, and the most downstream recording head 1 has a temperature of 30 ° C. and a relative humidity of 75%. It was found that humidification was performed over the entire area where the was placed.

  In this state, conveyance of glossy roll paper as a sheet was started, and as shown in FIG. 6, a plurality of types of recorded images 32 including a recorded image having an image size of 5 × 7 inches were recorded. “Discarded discharge 31” was performed between the recorded images 32, and continuous recording was performed at a speed of 1.5 inches per second. As a result, also in the writing unit 34 of the recorded image 32 when the unused nozzle is suddenly used, the landing accuracy and density from the first shot of the recording dot are the same as in the writing unit 33 of the recorded image 32 of the used nozzle. In both cases, an image having no problem was obtained (see FIG. 7A).

(Example 2)
In Example 1, the humidified air produced by the humidified air generating unit 21 is applied to the sheet in the same manner as in Example 1 except that the temperature is 40 ° C. and the relative humidity is 60% (absolute humidity 30.6 g / m ³ ). Recorded. In addition, the moisture supply amount to the roll paper at this time is 0.24 g / sec. When the moisture content of the roll paper blown with humidified air by the first humidifying duct 4 was measured, it was about 15%.

  Further, the temperature and relative humidity in the vicinity of the front end of the recording head 1 were measured in a state where the humidified air produced by the humidified air generating unit 21 was supplied via the first humidifying duct 4 and the second humidifying duct 3. . As a result, the most upstream recording head 1 has a temperature of 30 ° C. and a relative humidity of 95%, and the most downstream recording head 1 has a temperature of 30 ° C. and a relative humidity of 90%. It turned out that it was humidified over a long time.

  In this state, an image was recorded in the same manner as in Example 1. As a result, the recording dot landing accuracy from the first shot of the recording dot is the same as in the writing unit 33 of the recording image 32 of the nozzle used in the writing unit 34 of the recording image 32 when the unused nozzle is suddenly used. As a result, an image having no problem in density was obtained (see FIG. 7A).

(Comparative Example 1)
In Comparative Example 1, unlike Example 1, the humidification air was not blown onto the roll paper by the first humidification duct 4, and recording was performed on the roll paper in the same manner as in Example 1 except that. That is, the conditions are almost the same as those of the prior art (Patent Document 1).

  The temperature and relative humidity in the vicinity of the tip of the recording head 1 were measured in a state where the humidified air produced by the humidified air generating unit 21 was supplied only through the second humidifying duct 3. As a result, the most upstream recording head 1 had a temperature of 30 ° C. and a relative humidity of 70%, and the most downstream recording head 1 had a temperature of 30 ° C. and a relative humidity of 45%.

  In Comparative Example 1, since the humidified air is not blown onto the roll paper by the first humidification duct 4, moisture in the air in the recording unit 9 is absorbed by the roll paper, and before the recording starts. The humidity in the vicinity of the tip of the recording head 1 is lower than that in the first and second embodiments. In particular, the tendency is remarkable near the tip of the recording head 1 on the most downstream side.

  In this state, an image was recorded in the same manner as in Example 1. As a result, an image (see FIG. 7A) having no problem was obtained when it was placed in the writing portion 33 of the recorded image 32 of the nozzle used. However, in the writing unit 34 of the recorded image 32 when the unused nozzle is suddenly used, as shown in FIG. 7B, the landing accuracy of the recorded dots is lowered and the density is not constant.

DESCRIPTION OF SYMBOLS 1 Recording head 2 Sheet | seat 3 2nd humidification duct 4 1st humidification duct 9 Recording part 21 Humidified air production | generation part 43 Collection | recovery duct

Claims (9)

A recording unit including an inkjet recording head in which nozzles are formed; and
A humidifying section for generating humidified air;
A first supply port for supplying the first humidified air generated by the humidifying unit to the conveyed sheet;
A second supply port provided at a position closer to the ink jet recording head than the first supply port for supplying the second humidified air generated by the humidifying unit to a space where the nozzle is exposed; ,
A recovery duct for recovering a part of the first humidified air supplied from the first supply port and reintroducing the humidified part;
I have a,
The recording apparatus according to claim 1, wherein the absolute humidity of the first humidified air is higher than the absolute humidity of the second humidified air . A recording unit including an inkjet recording head in which nozzles are formed; and
A humidifying section for generating humidified air;
A first supply port for supplying the first humidified air generated by the humidifying unit to the conveyed sheet;
A second supply port provided at a position closer to the ink jet recording head than the first supply port for supplying the second humidified air generated by the humidifying unit to a space where the nozzle is exposed; ,
A recovery duct for recovering a part of the first humidified air supplied from the first supply port and reintroducing the humidified part;
Have
The recording apparatus, wherein the sheet is humidified until the equilibrium moisture content is reached by the first humidified air. In the recording unit, a plurality of the inkjet recording heads are held side by side from upstream to downstream along the direction in which the sheet is conveyed,
A part of the second humidified air supplied from the second supply port flows in a narrow space including a space between the nozzles and sheets of the plurality of recording heads from the upstream toward the downstream. The recording apparatus according to claim 1 , wherein the recording apparatus is characterized. Characterized by further comprising a reflux duct for re-introduced into the humidifying unit to recover a portion of the second humidified air supplied to said space from said second supply port from claim 1 4. The recording apparatus according to any one of items 3 . The recording apparatus according to claim 1 , wherein the sheet is humidified until the equilibrium moisture content is reached by the first humidified air. A recording unit including an inkjet recording head in which nozzles are formed; and
A humidifying section for generating humidified air;
A first supply port for supplying the first humidified air generated by the humidifying unit to the conveyed sheet;
A second supply port provided at a position closer to the ink jet recording head than the first supply port for supplying the second humidified air generated by the humidifying unit to a space where the nozzle is exposed; ,
A recovery duct for recovering a part of the first humidified air supplied from the first supply port and reintroducing the humidified part;
Have
The humidifying unit includes a first humidifying chamber for generating humidified air and a second humidifying chamber connected to the first humidifying chamber, and the humidified gas generated in the first humidifying chamber is the second humidifying chamber. A humidified gas introduced into the chamber and further humidified in the second humidifying chamber is generated,
The humidifying portion includes the said first humidification chamber partitioned by a wall within the housing second humidification chamber is provided in the bottom of the second humidification chamber and the first humidification chamber, and the first humidification chamber recording apparatus characterized by humidifying water for humidifying shared by the second humidification chamber is accumulated. Each of the first humidifying chamber and the second humidifying chamber includes a heating element, a humidifying filter, and a fan, and the gas introduced from the inlet provided in the housing is raised by the heating element in the first humidifying chamber. It is heated and humidified by the humidifying filter, and sent to the second humidifying chamber by the fan, and then heated by the heating element in the second humidifying chamber and further humidified by the humidifying filter, and then by the fan. The recording apparatus according to claim 6 , wherein the recording apparatus ejects from an ejection port provided in the housing. The humidifying filters provided in the first humidifying chamber and the second humidifying chamber each have a hollow cylindrical rotating body made of a material that has water absorption and allows gas to pass through, and a part of the rotating body is the humidifying filter. It rotates while immersed in water,
8. The recording according to claim 7 , wherein the gas heated by the heating element and blown to the humidifying filter passes through the hollow cylindrical shape from the outside to the inside and then passes from the inside to the outside to be humidified. apparatus. In each of the first humidifying chamber and the second humidifying chamber, the rotating body rises upward from the surface of the humidifying water on the side closer to the heating element, and the side farther from the heating element is below the surface of the humidifying water. The recording apparatus according to claim 8 , wherein the recording apparatus has a rotational direction that sinks into the recording medium.

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