JP2010158776A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make uniform an amount of foam applied to a recording medium by holding a bulk density constant by treating a surplus of foam generated at a foam applying part and making a foam amount of a foam storing part constant at all times. <P>SOLUTION: The image forming apparatus includes a foam applying means which makes a treatment agent of liquid or gel or a treatment agent of mixed liquid and gel foamy and applies it via a roller-shaped applying member, and a foam removing means which removes a surplus of the foamy treatment agent piled on a roller end of the applying member. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and in particular, a liquid or gel that can be in a foam state having a function as a set agent that suppresses bleeding such as feathering and bleeding and enables image formation with high density and high saturation, or The present invention relates to an image forming apparatus capable of uniformly applying liquid and gel to a recording medium in the form of fine bubbles.

  As an image forming apparatus such as a printer, a facsimile machine, a copying machine, and a composite machine of these, for example, a recording head composed of a liquid ejection head that ejects liquid droplets of recording liquid is used, and paper, thread, fiber, fabric, leather, There is a type in which an image is formed by adhering droplets to a medium while conveying a medium such as metal, plastic, glass, wood, and ceramics. Note that the image forming apparatus is an apparatus that forms an image by causing droplets to land on a medium. Image formation is not only the application of an image having a meaning such as characters or figures to a medium, but also a pattern. It also means that an image having no meaning is given to the medium. The recording liquid is not limited to ink, and any recording liquid can be used as long as it can form the image and form liquid droplets upon ejection.

  In such a liquid ejection type image forming apparatus, since a recording liquid (hereinafter referred to as ink) containing a coloring material is formed into droplets to form an image, the dots formed by the droplets are disturbed in a whisker shape. Rings, color bleed that causes colors to blur when the ink droplets of different colors are struck on the paper adjacent to each other, lack of color (density), show-through, glossiness, fixability, etc. In addition to the initial quality problem that it takes time for the droplets on the paper after printing to dry, there are problems related to fastness such as water resistance, light resistance, scratch resistance, and ozone resistance. ing.

  Therefore, as described in Patent Document 1, a pretreatment liquid that reacts with ink to prevent bleeding is applied by an application roller as described in the prior art, or the pretreatment liquid is ejected as described in Patent Document 2. It is performed by discharging from the head in the form of a mist. Further, Patent Document 3 describes that the treatment liquid for improving the fixing property of ink is applied before or after ink printing, and is not limited to the pretreatment, and there is a case where a posttreatment is performed.

JP 2002-137378 A Japanese Patent Laying-Open No. 2005-138502 JP 2003-205673 A

  However, as described in Patent Documents 1 to 3, when the pretreatment liquid or the posttreatment liquid is spouted by the application roller or the liquid discharge head, uneven coating occurs and the liquid is further on the paper for the liquid. There is a problem in the quick drying property after reacting with the ink, and in particular, there is a problem that the paper is likely to be wrinkled or curled, or to bend easily, so that jamming is likely to occur.

  Therefore, the present applicant has proposed to apply the treatment liquid to the recording medium in a bubble state as a means for solving these problems.

  Here, the foam coating apparatus is roughly configured to include a foam generating unit, a bubble refining unit, a foam spreading unit, and a foam coating unit. The foam generated in the foam generation unit is refined by the foam refinement unit, the refined foam is spread on the foam application unit by the foam spreading unit, and is applied to the recording medium by the foam application unit. Further, the foam application unit is composed of three rollers, a foam conveyance roller, a foam application roller, and a pressure roller, and the bubble conveyance roller and the pressure roller are in contact with the bubble application roller, respectively. . First, the foam supplied from the foam spreading unit on the foam transport roller becomes a foam of uniform thickness while creating a foam reservoir with the foam application roller, and is transported between the pressure roller and the foam application roller. It is uniformly applied to the surface of the recording medium. At this time, if there is not always a constant bubble in the bubble reservoir, the bulk density of the bubbles becomes non-uniform, and the amount applied to the recording medium also varies. Since it is difficult to control the supply amount of the foam to be constant, a large amount of foam is always supplied to the foam application part. Therefore, a mechanism for processing excess bubbles generated in the bubble pool is required.

  The present invention can process excess foam generated in the foam application part, and keep the bulk density constant by always keeping the foam amount in the foam reservoir part constant, so that the amount of foam applied to the recording medium can be made uniform. An object is to provide an apparatus.

  The image forming apparatus for forming an image on the recording medium of the present invention applies a liquid or gel processing agent or a processing agent mixed with liquid and gel to the recording medium in the form of foam and applies it through a roller-shaped application member. And a foam removing unit that removes excess foam processing agent deposited on the roller end of the coating member. Therefore, it is possible to keep the amount of foam applied to the recording medium constant by recovering the excessive amount of the foam processing agent supplied excessively to the foam application means.

  In addition, by providing a collection tray for collecting excess foam removed by the foam removing means, the amount of foam applied to the recording medium can be reduced by collecting excess foam supplied to the foam applying means. It becomes possible to keep it constant and to reuse the treatment agent.

  Further, the bubble removing means has a blade that is close to or abuts the surface of the roller end of the roller-shaped application member, and thereby recovers excess foam supplied to the foam application means, thereby recording the recording medium. It is possible to keep the amount of foam applied to the surface constant.

  Further, the blade is brought close to or in contact with the surface of the roller-shaped application member whose roller end is obliquely chamfered. Therefore, it is possible to keep the amount of foam applied to the recording medium constant by efficiently recovering the excessive amount of foam supplied to the foam application means.

  Further, the bubble removing means has a heating body in the vicinity of the roller end portion of the roller-shaped application member. Therefore, by heating the surplus foam with the heating body, the foamy processing agent returns to the liquid, and the storage portion can be made compact and the processing agent can be reused.

  Further, since the heating body is disposed so as not to contact the roller surface, the heat of the heating body is hardly transmitted to the application member, and the foam of the foam-like treatment agent is not easily broken.

  Furthermore, it is preferable that the collection tray is disposed below the blade or the heating body.

  The bubble removing means has a suction nozzle communicated with a suction pump in the vicinity of the roller end of the roller-shaped application member, and is deposited on the roller end of the roller-shaped application member using the suction nozzle. Aspirate excess foam. Therefore, it is possible to keep the amount of foam applied to the recording medium constant by recovering the excessive amount of foam supplied to the foam applying means, and to reuse the processing agent. It becomes possible.

  Furthermore, by having a regulating member that regulates the width in the roller axial direction of the foam processing agent applied to the roller surface in proximity to or in contact with the roller surface of the roller-shaped coating member, the roller shape is regulated by the regulating member. The excess foam deposited on the roller end of the applying member is removed by the foam removing means.

  According to the image forming apparatus of the present invention, it is possible to keep the amount of foam applied to the recording medium constant by recovering the excessive amount of foam supplied excessively in the foam application means.

1 is a schematic cross-sectional view illustrating a configuration of an image forming apparatus of the present invention. It is a perspective view which shows the structure of the foam range control mechanism in the foam application part of FIG. It is a figure which shows the structure of the foam collection | recovery mechanism in the foam application part of FIG. It is a figure which shows another structure of the foam collection | recovery mechanism in the foam application part of FIG. It is a figure which shows another structure of the foam collection | recovery mechanism in the foam application part of FIG. It is a figure which shows another structure of the foam collection | recovery mechanism in the foam application part of FIG.

  FIG. 1 is a schematic cross-sectional view showing the configuration of the image forming apparatus of the present invention. An image forming apparatus 100 according to the present invention shown in FIG. 1 includes a recording head unit 101 as an image forming unit that discharges droplets onto a sheet 300 that is a recording medium and forms an image, and a conveyance belt 102 that conveys the sheet 300. A paper feed tray 103 that accommodates the paper 300, a paper discharge tray 104 that discharges the paper 300 on which an image is formed, and a paper 300 that is a member to be coated on the upstream side of the recording head unit 101 in the paper transport direction. And a foam application device 200 for applying a foam liquid. The recording head unit 101 is composed of a line type liquid discharge head having a nozzle row in which a plurality of nozzles for discharging liquid droplets are arranged in a length corresponding to the paper width, and yellow (Y) and magenta (M), respectively. , Cyan (C), and black (K) ink droplets are provided in recording heads 101y, 101m, 101c, and 101k. Note that the recording head can be mounted on the carriage as a serial type image forming apparatus.

  Further, the conveyance belt 102 is an endless belt, and is configured to be looped around the conveyance roller 105 and the tension roller 106. The sheet 300 can be held on the conveyance belt 102 by, for example, a configuration that performs electrostatic adsorption, adsorption by air suction, or other known conveyance means. The paper 300 stored in the paper feed tray 103 is separated one by one by the pickup roller 107, fed by the pair of transport rollers 108, and further transported through the transport path 111 by the pair of transport rollers 109 and 110, and the foam coating device After the foam application by 200, it is fed onto the conveyor belt 102 and held. Then, droplets of each color are ejected from the head unit 101 while being transported by the transport belt 102 to form an image on the paper 300 on which bubbles are applied, and then the paper 300 is discharged to the paper discharge tray 104.

  On the other hand, the foam application apparatus 200 includes a container 202 containing a liquid or gel or a liquid and gel treatment agent 201 that can be made into a foam state, a pump 203 that pumps the treatment agent 201 from the container 202, and a pump 203. The first foam generation unit 206 that generates the foam processing agent 205 having a large bubble from the processing agent 201 supplied via the supply path 204 and the route that sends the foam processing agent 205 from the first foam generation unit 206. A foam supply path 207, a second foam generation unit 209 that shears the foam treatment agent 205 conveyed in the foam supply path 207 a plurality of times to generate a foam treatment agent 208 having a small foam, and a foam treatment An extending member 210 that extends the agent 208 in the paper width direction and a foam application unit 211 that applies the foam treatment agent 208 to the paper 300 are provided.

  Here, the processing agent 201 that can be in a foam state is a modifying material that modifies the surface of the paper 300 by being applied to the surface of the paper 300. For example, the processing agent 201 is applied to the paper 300 in a uniform manner so that the moisture of the ink can quickly penetrate the paper 300, the viscosity of the color component is increased, and the drying is also accelerated, thereby fading and bleeding. It is a set agent that prevents bleeding and show-through and the like, and can increase productivity (number of images output per unit time).

  In terms of composition, this treatment agent 201 is, for example, cellulose that promotes moisture permeation with respect to a surfactant (any one of anionic, cationic, nonionic, or a mixture of two or more thereof). And the like (hydroxypropylcellulose and the like) and a base added with a base such as talc fine powder. Furthermore, fine particles can be contained.

  The first foam generation unit 206 supplies the high-pressure air 214 from the high-pressure air supply unit 213 to the processing agent 201 in the foam generation container 212 via the high-pressure air supply path 215, thereby generating a large foam shape. A processing agent 205 is generated. When the foam treatment agent 205 is generated and filled in the foam generation container 212, the foam processing agent 205 is supplied toward the foam application unit 211 via the foam transport path 207 by the pressure. Note that the pump 203 closes the supply path 204 so that the bubbles 205 and the processing agent 201 do not flow back through the supply path 204 for supplying the processing agent 201 during the generation of bubbles.

  Also, the foam application unit 211 includes a foam transport roller 216 that transports the foam supplied from the spreading member 210, an application roller 217 that applies the foam to the recording medium, a cleaner 218 of the application roller 217, and an application roller 217. And a pressure roller 219 for pressing the recording medium. Further, in the present invention, the blade 220 has a blade 220 that scrapes off excess foam of the foam transport roller 216 and a collection tray 221 that collects the recovered surplus foam. The blade 220 scrapes off excess foam on the foam transport roller 216. It is taken and collected in the collection tray 221.

Here, the “bubble” refers to a state in which a large amount of bubbles are dispersed in the liquid and the liquid is compressible. In other words, the liquid is rounded by containing a gas such as air, and is formed by the surface tension of the liquid that encloses the gas, and can maintain a three-dimensional shape for a certain period of time. The foam having such shape-retaining properties preferably has a bulk density of 0.05 g / cm ³ or less, a foam diameter distribution range of 10 μm to 1 mm, and an average foam diameter of 100 μm or less. In addition, although a bubble is formed in a round shape by itself, when a plurality of bubbles are combined, the shape of each bubble takes a polyhedral shape due to surface tension. Such a foam is not a liquid but a semi-solid, and exhibits physical properties close to a solid in terms of fluidity.

Compared to a liquid or mist-like treatment liquid, the treatment agent in such a foam state has the following advantages.
1. Since the foam contains a large amount of air, a small amount of liquid can be applied.
2. Since the foam is almost solid, the coating thickness can be easily adjusted by applying and scraping, etc., and it can be evenly applied because it has good releasability from the coating means when applied from paper to paper. It is.
3. Bubbles are less likely to cause water to penetrate into the fibers of the paper, so that the paper is less likely to wrinkle or curl.

  Further, the use of a foam-like treatment agent for the recording medium in this manner has a special effect during high-speed recording / processing, as compared with a liquid or mist-like treatment liquid. For example, when printing on continuous paper at a high speed like a continuous book machine, it is necessary to rotate the roller or the like at high speed in order to catch up with the recording operation. When such a recording speed exceeds about 100 m / min, the centrifugal force generated by the high-speed rotation of the roller becomes extremely large, and the liquid processing agent is separated from the roller surface and scattered, which is applied to the recording medium. There is a problem that the amount to be reduced is significantly reduced. In order to solve such problems with a liquid processing agent, it may be possible to increase the viscosity of the liquid and make it difficult to scatter from the roller surface. However, it is difficult to apply such a high viscosity liquid as a thin film. In addition, the load of the liquid supply / drainage operation is large, leading to an increase in the size of the transport pump and the complexity of the apparatus.

  On the other hand, the foam-like treatment agent has a normal low viscosity at the time of transportation, has a small transportation load, and exhibits a semi-solid property in the foamed state in the form of a roller. Will not follow and scatter. It is also advantageous for applying a thin film to a recording medium. Further, residual foam after application can be easily recovered as a low-viscosity treatment agent by defoaming by heating with a heater or the like, and all the problems associated with high-speed application of the liquid treatment agent can be solved.

  FIG. 2 is a perspective view showing a configuration of a foam range regulating mechanism in the foam application unit of FIG. In the figure, the same reference numerals as those in FIG. 1 denote the same components. As shown in the figure, when foam is supplied from the extending member 210 in the foam application unit, a bubble reservoir is formed at the tangential upper part of the foam transport roller 216 and the application roller 217. Since it is difficult to keep the amount of foam supplied constant, the amount of foam supplied is always larger than the required amount. Bubbles formed in a thin film shape on the application roller 217 are applied to the recording medium from the bubble reservoir. If a constant amount is always accumulated in the bubble reservoir, the bulk density of the bubbles is constant, and the amount of bubbles applied to the recording medium is also constant. However, since the foam is always in an excessive supply state, it is necessary to process surplus foam. Therefore, the range of the bubble accumulation is fixed by the side fence 222 as the bubble range regulating mechanism, and the bubbles overflowing from this range are recovered by the bubble recovery means described later. The side fence 222 is movable in the roller axis direction by a transfer shaft 223.

  FIG. 3 is a diagram showing a configuration of a foam recovery mechanism in the foam application unit of FIG. (A) of the figure is a front view, (b) of the figure is a side view, and (c) of the figure is a partial plan view. In the figure, the same reference numerals as those in FIG. 1 denote the same components. As shown in the figure, the corners of the bubble transport roller 216 are formed in a diagonally chamfered shape, and the blades 220 are pressed against the diagonal portions to scrape excess bubbles and collect in the recovery tray 221. Here, in the roller to which the liquid is applied, the excess liquid hangs down on the end surface of the roller and does not reach the chamfered portion, but the bubble hangs down at the end of the roller because it is in a semi-solid state. Instead, the chamfered portion reaches the shaft. The foam is collected at the chamfered portion at the end of the roller by utilizing the feature of the foam. Although it is possible to collect by applying a blade to the roller surface instead of the oblique portion, it is necessary to lengthen the roller for the length of pressing the blade 220, and in the roller parallel portion, the amount of bubbles is made as constant as possible. Although it is desired to keep it, the amount of bubbles is affected by applying the blade 220 to the roller surface. Therefore, the amount of foam on the roller surface can be kept constant and the machine size can be made more compact by applying the blade to the chamfered oblique portion and collecting the foam as in the present invention. In FIG. 3, the bubble transport roller 216 is shorter in the axial direction than the application roller 217, but as a result, surplus bubbles gather at the end of the bubble transport roller 216, and the surplus bubbles there. As a result, it is difficult for excess bubbles to stick to the application roller 217. This shape is desirable because excessive foam on the application roller 217 causes the amount applied to the recording medium to be non-uniform. The surplus foam scraped off from the foam transport roller 216 travels down the support 224 and falls into the collection tray 221. For example, the foam is liquefied by providing a heater near the connecting portion between the blade 220 and the support 224. Therefore, it can be recovered in a liquid state. A waste liquid pipe 225 is connected to the bottom surface of the collection tray 221 and the accumulated liquid is discarded therefrom. It is also possible to reuse the liquid by providing a filter or the like at the end of the waste liquid pipe 225.

  FIG. 4 is a diagram showing another configuration of the foam recovery mechanism in the foam application unit of FIG. (A) of the figure is a front view, (b) of the figure is a side view. In the figure, the same reference numerals as those in FIG. 3 denote the same components. As shown in the figure, a heat insulator 226 is wound around the roller shaft in the vicinity of the shaft ends at both ends of the bubble transport roller 216, and a ring-shaped heater 227 is attached as a heating body around the heat insulator 226. As described with reference to FIG. 3, due to the characteristics of the foam as a semi-solid, surplus foam overflowing from the foam pool gathers at both ends as the foam transport roller 216 rotates, passes through the chamfered portion, and further reaches the shaft. . Therefore, the foam is changed to liquid by the heater 227 provided on the shaft, and the liquid is recovered by the recovery tray 221. Also, a sensor (not shown) for detecting the presence or absence of bubbles is provided near the end of the roller shaft or the roller surface, and the heater 227 is turned on only when excess bubbles are generated by monitoring the generation of excess bubbles. Such control becomes possible. Note that the example shown in FIG. 4 uses a ring-shaped heater, but it is also possible to implement the heater in the vicinity of the shaft end. At this time, the liquefied bubbles are collected in the collection tray through the support by placing the heater support in the collection tray. It is difficult to implement such a configuration in which bubbles are liquefied and collected by a heater because it affects the quality of the foam applied in the vicinity of the area where the foam is applied, but the foam is retained by providing a heater on the shaft. The heater can be provided apart from the surface of the roller to be performed, and efficient collection is possible.

  FIG. 5 is a diagram showing another configuration of the foam recovery mechanism in the foam application unit of FIG. (A) of the figure is a front view, (b) of the figure is a side view, and (c) of the figure is a partial plan view. In the figure, the same reference numerals as those in FIG. 3 denote the same components. As shown in the figure, surplus bubbles gathering at both ends of the bubble conveying roller 216 are sucked and collected from the collection nozzle 229 by using a pump 228. The liquid discharged from the pump 228 is discarded, but can be reused through a filter or the like.

  FIG. 6 is a diagram showing another configuration of the foam recovery mechanism in the foam application unit of FIG. (A) of the figure is a front view, (b) of the figure is a side view, and (c) of the figure is a partial plan view. In the figure, the same reference numerals as those in FIGS. 3 and 5 denote the same components. As shown in the drawing, the blade 220 attached to the support 224 scrapes off the foam transport roller 216, and the collected foam is sucked and collected from the collection nozzle 229 using the pump 228.

  The present invention is not limited to the above-described embodiments, and various modifications, substitutions, and applications are possible as long as they are described within the scope of the claims. For example, without disturbing fine particles containing resin such as toner on a medium such as paper, and after applying a foamy fixing solution to the medium to which the fine resin particles are attached, the fine resin particles are quickly fixed to the medium, Furthermore, the present invention can also be applied to a fixing method and a fixing device, and an image forming method and an image forming apparatus that use a fixing solution of resin fine particles that can be applied in a minute amount that does not cause a feeling of residual oil on the medium.

100; Image forming apparatus, 200; Foam coating apparatus, 201; Treatment agent,
202; container, 203, 228; pump, 204; supply path,
205, 208; foam treatment agent, 206; first foam generation unit,
207; foam supply path, 209; second foam generation unit,
210; spreading member; 211; foam application unit; 212; foam generation container;
213; high-pressure air supply unit; 214; high-pressure air;
215; high-pressure air supply path, 216; foam conveying roller,
217; coating roller, 218; coating roller, 219; pressure roller,
220; blade, 221; collection tray, 222; side fence,
223; transfer shaft, 224; support, 225; waste pipe,
226; insulator, 227; heater, 229; recovery nozzle.

Claims (9)

In an image forming apparatus for forming an image on a recording medium,
A foam application means for applying a liquid or gel treatment agent on the recording medium, or a treatment agent in which a liquid and a gel are mixed, in a foam form and applied via a roller-shaped application member;
An image forming apparatus comprising: a foam removing unit that removes excess foam-like processing agent deposited on a roller end of the coating member.   The image forming apparatus according to claim 1, further comprising a collection tray that stores excess foam processing agent removed by the foam removing unit.   The image forming apparatus according to claim 1, wherein the bubble removing unit includes a blade that approaches or abuts a surface of a roller end portion of the application member.   The image forming apparatus according to claim 3, wherein the blade is close to or abuts on a surface where the roller end portion of the coating member is obliquely chamfered.   The image forming apparatus according to claim 1, wherein the bubble removing unit includes a heating body in the vicinity of a roller end portion of the application member.   The image forming apparatus according to claim 5, wherein the heating body is disposed so as not to contact the roller surface.   The image forming apparatus according to claim 2, wherein the collection tray is disposed below the blade or the heating body.   The foam removing means has a suction nozzle communicated with a suction pump in the vicinity of the roller end of the application member, and the excess foam deposited on the roller end of the application member using the suction nozzle. The image forming apparatus according to claim 1, wherein the processing agent is removed by suction.   9. The apparatus according to claim 1, further comprising a regulating member that regulates a width in a roller axial direction of the foam treatment agent applied to the roller surface in proximity to or in contact with the roller surface of the application member. The image forming apparatus described.

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