JP2013103474A - Transfer device and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer device which has an intermediate transfer body to which ink is imparted by an ink discharge head and transfers the ink on the intermediate transfer body to a material to be recorded while securing the contact area of the intermediate transfer body with the material, and an applied pressure in the contact area, and to provide an image formation device provided therewith.SOLUTION: At least one of the intermediate transfer body 37 to which the inks discharged by the heads 61Y, 61M, 61C and 61BK are imparted, and a transfer member 38 forming a conveyance path 31 transferring the inks on the intermediate transfer body 37 while conveying the material S to be recorded along an A1 direction, is a strip-shaped belt member. There are used a plurality of support members 71, 72 on which the belt member is wound so that the conveyance path 31 is nonlinear, and a pressure application member 74 for making the belt member in a pressed state from inside so that the material S to be recorded conveyed on the conveyance path 31 is pressed between the intermediate transfer body 37 and the transfer member 38 in the conveyance path 31.

Description

  The present invention is provided in an image forming apparatus having an intermediate transfer body to which ink is applied by an ink discharge head, and a transfer apparatus for transferring the ink on the intermediate transfer body to a recording material such as paper, and such an image including the transfer apparatus. The present invention relates to a forming apparatus.

  2. Description of the Related Art Conventionally, there has been an inkjet image forming apparatus such as an inkjet printer that includes a head that ejects ink using a movable actuator method typified by a piezo method, a heated film boiling method typified by a thermal method, and the like. It is known (for example, see [Patent Document 1] to [Patent Document 5]).

  In the inkjet method, in a configuration in which ink is directly ejected from a head to a recording material such as recording paper, the head and the recording material are close to each other, so paper dust, dust, etc. adhering to the recording material adhere to the nozzle. It's easy to do. When paper dust or the like adheres to the nozzle, the flying direction of droplets ejected from the nozzle is disturbed, or the nozzle is blocked, resulting in a reduction in image quality and reliability. As a measure for avoiding such a problem, priority is given to the ejection stability from the nozzle, and ink having a low viscosity is generally used. However, ink having a low viscosity lands on the recording material. Bleeding easily occurs.

  Due to such circumstances, an intermediate transfer type inkjet image provided with a transfer device having an intermediate transfer member that carries ink discharged from the head and a transfer member that transfers the ink on the intermediate transfer member to a recording material. A forming apparatus has been proposed (see, for example, [Patent Document 1] to [Patent Document 5]).

  In an intermediate transfer type inkjet image forming apparatus, high-efficiency transfer of ink from an intermediate transfer member to a recording material is an essential condition for obtaining a high-quality image. In addition, if the transfer rate is improved, the time and number of cleaning operations for the intermediate transfer member can be reduced in the subsequent steps, leading to a reduction in the space for collecting waste ink, and the deterioration of the intermediate transfer member due to the cleaning operation is also reduced. There are great advantages.

  As a technique to improve the transfer rate from the intermediate transfer member to the recording material, the intermediate transfer member is made into a belt shape, and the intermediate transfer member is stretched by a plurality of members from the inside, and this stretched linear area is used. Thus, a technique for increasing the contact time between the ink on the intermediate transfer member and the recording material has been proposed (for example, see [Patent Document 1] and [Patent Document 2]).

  On the other hand, both the intermediate transfer member and the transfer member are configured in a roller shape (see, for example, [Patent Document 3] and [Patent Document 4]), or the intermediate transfer member is wound from the inner side in a belt shape. In the configuration in which the transfer is performed at a different position (for example, see [Patent Document 5]), the pressurizing portion that is the contact portion between the intermediate transfer member and the recording material is linear along the width direction of the intermediate transfer member. Therefore, the contact time between the intermediate transfer member and the recording material is shorter and the transfer rate is lower than that of the above-described technique. The same applies to the case where the intermediate transfer member and the transfer member are elastic bodies.

  In recent years, high productivity has been demanded, and in order to realize this, there is a tendency to increase the transfer speed of the transfer paper S, and thus the contact time has become shorter. On the other hand, in the development of ink, in order to achieve high image quality while supporting high-speed output, quick drying and high viscosity are being promoted, and at the same time, high penetration is being promoted. It is a fact.

  In view of these circumstances, in order to improve the transfer rate from the intermediate transfer member to the recording material, it is necessary to increase the contact time between the intermediate transfer member and the recording material as described above, that is, the intermediate transfer. It is preferable to lengthen the contact area between the body and the recording material.

  However, in order to improve the transfer rate, it is necessary to secure a pressing force in the contact area in addition to lengthening the contact time and the contact area. In this regard, in the configuration in which a belt-shaped member is stretched by a plurality of members from the inside and transfer is performed in a linear contact area as in the above-described technique, the contact time of the recording material becomes long, but in the contact area There is concern about insufficient pressure. Also, in the linear contact area, depending on the tension and feed speed of the belt-shaped member, this member may flutter, and the recording material may be momentarily separated. There is also. Ensuring the pressure is particularly important for good transfer to paper with poor hygroscopicity.

  In addition, in recent years, for high image quality and high reliability, there are various types of ink, such as changing the viscosity of the ink by chemical or electrical methods, or using solid ink that melts at high temperatures. The state of each ink drop on the intermediate transfer member is not always uniform. In order to reliably transfer these inks and reduce the amount of ink remaining on the intermediate transfer member, it is desirable that the transfer conditions can be further optimized.

  The present invention includes an intermediate transfer body to which ink is applied by an ink discharge head, and the ink on the intermediate transfer body is placed while ensuring the contact area between the intermediate transfer body and the recording material and the pressurizing force in the contact area. It is an object of the present invention to provide a transfer device for transferring to a recording material and an image forming apparatus provided with the transfer device.

  In order to achieve the above object, an invention according to claim 1 is directed to an intermediate transfer member to which ink ejected by an ink ejection head is applied and which moves in a predetermined direction, and a recording material along the predetermined direction. A transfer member that forms a conveyance path for transferring the ink on the intermediate transfer member to the recording material while being conveyed, and at least between the intermediate transfer member and the transfer member. One is a belt-shaped belt member, and a plurality of support members wound around the belt member from the inside so that the conveyance path is non-linear, and a recording material conveyed through the conveyance path are conveyed in the same way. The transfer apparatus includes at least one pressing member for pressing the belt member from the inside so as to be pressed between the intermediate transfer member and the transfer member in the path.

  The present invention provides an intermediate transfer body that is applied with ink discharged by an ink discharge head and moves in a predetermined direction, and the intermediate transfer to the recording material while conveying the recording material along the predetermined direction. A transfer path formed between the intermediate transfer body and a transfer path for transferring ink on the body, and at least one of the intermediate transfer body and the transfer member is a belt-like belt member, A plurality of support members wound around the belt member from the inside so that the conveying path is non-linear, and a recording material conveyed along the conveying path are the intermediate transfer member and the transfer member in the conveying path. So that the belt member is pressurized from the inside so as to be pressed between the intermediate transfer member and the recording material. Area and this contact area High transfer efficiency can be achieved by transferring the ink on the intermediate transfer member to the recording material while ensuring the pressure applied in the recording medium, and forming a pressure distribution in the transport path using the pressure member. It is possible to provide a transfer device that can be realized and contribute to high-quality image formation.

1 is a schematic front view of an example of an image forming apparatus to which the present invention is applied. FIG. 2 is a schematic diagram illustrating a state in which a recording liquid is applied from a head to an intermediate transfer member in the image forming apparatus illustrated in FIG. 1. FIG. 2 is a schematic front view of an example of a transfer device provided in the image forming apparatus illustrated in FIG. 1. FIG. 6 is a conceptual diagram illustrating an example of a pressure distribution between an intermediate transfer member and a transfer member. FIG. 2 is a conceptual diagram illustrating a state where pigments in a conductive recording liquid discharged from a head in the image forming apparatus illustrated in FIG. 1 are aggregated via protons. FIG. 2 is a conceptual diagram showing a state of a liquid column by a conductive recording liquid formed between a cathode and an anode in the image forming apparatus shown in FIG. It is a conceptual diagram for explaining an example of optimizing the pressure distribution between the intermediate transfer member and the transfer member according to the characteristics of the recording liquid. FIG. 10 is a schematic front view of a first modification of the transfer device provided in the image forming apparatus shown in FIG. 1. FIG. 10 is a schematic front view of a second modification of the transfer device provided in the image forming apparatus shown in FIG. 1. FIG. 10 is a schematic front view of a third modification of the transfer device provided in the image forming apparatus shown in FIG. 1. FIG. 10 is a schematic front view of a fourth modification of the transfer device provided in the image forming apparatus shown in FIG. 1. FIG. 10 is a schematic front view of a fifth modification of the transfer device provided in the image forming apparatus shown in FIG. 1. It is a schematic front view of the 6th modification of the transfer apparatus with which the image forming apparatus shown in FIG. 1 is equipped. It is a schematic front view of the 7th modification of the transfer apparatus with which the image forming apparatus shown in FIG. 1 is equipped. It is a schematic front view of the 8th modification of the transfer apparatus with which the image forming apparatus shown in FIG. 1 is equipped. It is a schematic front view of the 9th modification of the transfer apparatus with which the image forming apparatus shown in FIG. 1 is equipped. It is a schematic front view of the 10th modification of the transfer apparatus with which the image forming apparatus shown in FIG. 1 is equipped. It is a schematic front view of the 11th modification of the transfer apparatus with which the image forming apparatus shown in FIG. 1 is equipped. It is a schematic front view of the 12th modification of the transfer device with which the image forming apparatus shown in FIG. 1 is equipped. It is a schematic front view of the 13th modification of the transfer device with which the image forming apparatus shown in FIG. 1 is equipped. 6 is a flowchart illustrating an example of control in a case where a pressure distribution between an intermediate transfer member and a transfer member is changed according to various conditions.

  FIG. 1 shows an outline of an image forming apparatus to which the present invention is applied. The image forming apparatus 100 is a printer as an ink jet printer and can perform full-color image formation. The image forming apparatus 100 performs an image forming process based on an image signal corresponding to image information received from the outside.

  The image forming apparatus 100 can form an image on a sheet-like recording medium using not only plain paper generally used for copying, but also OHP sheets, cardboard, cardboard, cardboard, and envelopes. It is. The image forming apparatus 100 is a single-sided image forming apparatus capable of forming an image on one side of a transfer sheet S as a recording material, which is a recording medium. Also good.

  The image forming apparatus 100 ejects a recording liquid, which is a conductive recording liquid as ink of that color, capable of forming an image as an image corresponding to each color separated into yellow, magenta, cyan, and black. The recording heads 61 </ b> Y, 61 </ b> M, 61 </ b> C, and 61 </ b> BK are recording heads that are ink discharge heads as recording liquid discharge bodies.

  The heads 61Y, 61M, 61C, and 61BK are arranged on a drum-shaped intermediate transfer body 37 as an intermediate transfer member that is an intermediate transfer drum that is a first rotating member disposed in a substantially central portion of the main body 99 of the image forming apparatus 100. It is arrange | positioned in the position facing an outer peripheral surface. The heads 61Y, 61M, 61C, 61BK are arranged in this order from the upstream side in the A1 direction, which is a predetermined direction in which the intermediate transfer member 37 moves and is clockwise in FIG. In the drawing, Y, M, C, and BK added after the numerals of the reference numerals indicate members for yellow, magenta, cyan, and black.

  The heads 61Y, 61M, 61C, and 61BK are respectively ink ejection devices 60Y, 60M, which are recording liquid ejection devices for forming yellow (Y), magenta (M), cyan (C), and black (BK) images. It is provided in 60C and 60BK. Each of the heads 61Y, 61M, 61C, and 61BK is provided in the ink ejection devices 60Y, 60M, 60C, and 60BK in such a manner that a plurality of the heads 61Y, 61M, 61C, and 61BK are arranged in parallel in the direction perpendicular to the paper surface of FIG.

  The intermediate transfer body 37 is rotated in the A1 direction and is recorded in yellow, magenta, cyan, and black from the heads 61Y, 61M, 61C, and 61BK in an area facing the heads 61Y, 61M, 61C, and 61BK. The liquids are ejected and applied in such a manner that they are sequentially superimposed, and an image is formed on the surface. As described above, the image forming apparatus 100 has a tandem structure in which the heads 61Y, 61M, 61C, and 61BK are opposed to the intermediate transfer member 37 and are arranged in parallel in the A1 direction.

  The recording liquid is ejected or applied to the intermediate transfer member 37 by the heads 61Y, 61M, 61C, 61BK upstream of the A1 direction so that the image areas of yellow, magenta, cyan, and black are overlapped at the same position on the intermediate transfer member 37. The timing is shifted from the side toward the downstream side.

  The image forming apparatus 100 includes ink discharge devices 60Y, 60M, 60C, and 60BK that are provided with heads 61Y, 61M, 61C, and 61BK, and an intermediate transfer member 37 that is transferred as the intermediate transfer member 37 rotates in the A1 direction. A transport unit 10 serving as a paper transport unit for transporting the paper S, and a feeding unit that can load a large number of transfer sheets S and feeds only the top transfer sheet S among the stacked transfer sheets S toward the transport unit 10. It has a paper unit 20 and a paper discharge tray 25 on which a large number of printed transfer papers S that have been transported by the transport unit 10 can be stacked.

  In the image forming apparatus 100, as shown in FIG. 2B, the liquid column of the recording liquid immediately after being ejected from the heads 61Y, 61M, 61C, 61BK is changed to the heads 61Y, 61M, 61C, 61BK, the intermediate transfer body 37, and the like. The electrode oxidation reaction is performed inside the recording liquid in such a liquid column so that a potential difference is formed between the intermediate transfer member 37 and the heads 61Y, 61M, 61C, 61BK in a state where the space between the intermediate transfer body 37 and the head 61Y, 61M, 61C, 61BK. Alternatively, it has energization means 33 as voltage application means for energizing the recording liquid in a state where the current component resulting from the electrode reduction reaction is applied and promoting aggregation of the colorant contained in the recording liquid as described later.

  As shown in FIG. 1, the image forming apparatus 100 also includes a carriage 50 as a head support that integrally supports the heads 61Y, 61M, 61C, and 61BK, a CPU that controls the overall operation of the image forming apparatus 100, a memory, and the like. A control unit 40 including control means, an operation panel (not shown), and temperature / humidity detection means for measuring the temperature / humidity environment in which the image forming apparatus 100 is used.

  The transport unit 10 guides the transfer device 64 serving as a transfer unit including the intermediate transfer body 37 and the transfer sheet S fed from the paper supply unit 20 to the transfer device 64, and passes through the transfer device 64. A guide plate 39 that guides the paper S to the paper discharge tray 25 and a motor or the like as a driving unit (not shown) that rotationally drives the intermediate transfer body 37 in the A1 direction. As described above, the image forming apparatus 100 is an indirect image forming apparatus that indirectly forms an image on the transfer sheet S using the intermediate transfer body 37.

  As shown in FIG. 1 or FIG. 3, the transfer device 64 is a belt member that is a belt-like transfer member that is a second rotating member disposed opposite to the intermediate transfer member 37 in addition to the intermediate transfer member 37. , A plurality of, in this embodiment, three support rollers 71, 72, 73, which are roller-shaped support members, an intermediate transfer body 37, and a transfer member 38. And the pressure roller 74 as a roller-shaped pressure member that is in contact with the transfer member 38 in the transfer portion 31 that is the contact area of the contact portion, and the pressure roller 74 is pressed against the transfer member 38 so that the transfer member 38 is pressed. And a pressing spring 75 as a pressing unit that is a biasing unit pressurized from the inside.

  The transfer device 64 is also provided with a release claw 76 as a release member for peeling the transfer sheet S, which is provided opposite to the intermediate transfer body 37 on the downstream side of the transfer member 38 in the A1 direction, and passes through the intermediate transfer body 37. The intermediate transfer after the recording liquid or the like is provided on the transfer paper S, which is provided on the downstream side of the peeling claw 76 in the A1 direction and upstream of the heads 61Y, 61M, 61C, 61BK and facing the intermediate transfer body 37. A cleaning member 34 serving as a cleaning unit for removing the recording liquid remaining on the intermediate transfer member 37 from the body 37 and cleaning, and a support roller 72 are driven to rotate so as to function as a driving roller. And a motor as drive means (not shown) that moves and rotates 38 in a driven manner along the B1 direction along the A1 direction.

  The support roller 71 is located on the upstream side of the transfer unit 31 in the movement direction B1 of the transfer member 38 along the A1 direction, and forms the entrance of the transfer unit 31. In this regard, the support roller 71 functions as an entrance roller that is a roller-like entrance member. The support rollers 71 and 73 are driven rollers that are driven and rotated by the transfer member 38 that rotates in the B1 direction by the rotation of the support roller 72 that is a drive roller.

  The support roller 72 is located on the downstream side of the transfer unit 31 in the B1 direction, and forms an outlet of the transfer unit 31. In this respect, the support roller 72 functions as an exit roller that is a roller-shaped exit member.

  As long as the transfer member 38 can be driven to rotate, one of the support rollers 71, 73 out of the support rollers 71, 72, 73 may be a drive roller, and the other support rollers may be driven rollers.

  The support rollers 71 and 72 are rotated at a fixed position separated from the intermediate transfer body 37. The positions where the support rollers 71 and 72 are provided are such that the portion of the transfer member 38 that is stretched between the support roller 71 and the support roller 72 is pressed against the intermediate transfer body 37 to form the transfer unit 31. It is considered as a position.

  The transfer unit 31 is brought into close contact with the intermediate transfer body 37 while transporting the transfer paper S along the A1 direction, and serves as a transport path for transferring an image formed by the recording liquid carried on the intermediate transfer body 37 onto the transfer paper S. ing.

  The transfer member 38 forms the transfer portion 31 between the intermediate transfer member 38. A portion of the transfer member 38 that is stretched between the support roller 71 and the support roller 72 is pressed against the intermediate transfer member 37, and the transfer unit 31 is curved along the peripheral surface of the intermediate transfer member 37. It has a shape and is non-linear. The support rollers 71 and 72 have their arrangement positions adjusted so that the transfer unit 31 is thus non-linear.

  Therefore, the transfer member 38 functions as a pressure belt that is a belt-like pressure member that presses the transfer sheet S against the intermediate transfer body 37 in the entire transfer portion 31. Therefore, the flapping of the transfer member 38 is prevented, and the transfer sheet S stably adheres to the intermediate transfer body 37 over the entire area of the transfer portion 31, and the recording liquid on the intermediate transfer body 37 and the intermediate transfer body 37 and the transfer sheet S are transferred. The contact time and the contact area become longer, and the transfer efficiency of the recording liquid from the intermediate transfer body 37 to the transfer paper S is increased.

  Further, by improving the transfer rate, for example, as described later, the contact pressure of the cleaning blade provided in the cleaning unit 34 to the intermediate transfer body 37 can be lowered, and the intermediate transfer body 37 is deteriorated by the cleaning operation. In addition to being able to reduce the time and frequency of the cleaning operation of the intermediate transfer member 37, and the like, it is possible to reduce the recovery space for the recovered recording liquid.

  The pressure roller 74 is urged by the urging force of the pressing spring 75 so that the transfer sheet S conveyed through the transfer unit 31 is pressed between the intermediate transfer body 37 and the transfer member 38 in the transfer unit 31. A pressure state, which is a state where the transfer member 38 is pressed from the inside, is formed.

  As described above, the transfer member 38 functions as a pressure belt that is a belt-like pressure member that presses the transfer sheet S against the intermediate transfer body 37 in the entire transfer unit 31. At a position where the pressurization state is formed, the transfer sheet S is pressed against the intermediate transfer body 37 with a high pressure. As described above, the transfer portion 31 has a non-uniform distribution of the applied pressure along the A1 direction and the B1 direction. Hereinafter, the pressure distribution of the transfer portion 31, in other words, the pressure distribution between the intermediate transfer body 37 and the transfer member 38 in the transfer portion 31 is referred to as a pressure profile.

  For example, when the recording liquid and the transfer paper S are a highly permeable combination, the pressure profile increases as soon as the transfer paper S enters the transfer unit 31 as shown in FIG. Is desirable. In this pressure profile, the recording liquid is pressed and spread before being applied to the transfer paper S, thereby preventing the recording liquid droplets from penetrating while spreading unevenly. Since the recording liquid stays shallow in the vicinity of the surface, the image density is also secured. Thus, by using an appropriate pressure profile, it is possible to achieve both high quality transfer images and high-efficiency transfer. Details of the pressure profile suitable for the image forming apparatus 100 will be described later.

  At least one of the transfer member 38, the support rollers 71, 72, 73 and the pressure roller 74 may include a heater for fixing the image transferred onto the transfer paper S to the transfer paper S. Further, the transport unit 10 may include fixing means for fixing the image transferred from the intermediate transfer body 37 to the transfer paper S by the transfer member 38 on the transfer paper S.

  As shown in FIG. 2, the intermediate transfer member 37 includes a support 37a made of aluminum, which is a conductive substrate, and a surface layer 37b made of silicone rubber formed on the support 37a. The material of the support 37a is not limited to aluminum, and may be formed of a metal such as an aluminum alloy, copper, or stainless steel as long as it has mechanical strength. The material of the surface layer 37b is not limited to silicone rubber. For the advantage of high releasability of the recording liquid, any elastic material having low surface energy and high followability to the transfer paper S may be used. You may form with rubber | gum, fluororubber, nitrile butadiene rubber, etc.

The surface layer 37b is a conductive rubber in which metal fine particles such as carbon, platinum, and gold as a conductive agent are dispersed and mixed in the rubber material in order to impart conductivity to the intermediate transfer member 37. It has become. However, when the number of conductive fine particles is increased, the conductivity is improved, but since there is a trade-off relationship in which the releasability is lowered, adjustment is necessary as appropriate. As will be described later, in order to form a desired potential difference in the liquid column of the recording liquid temporarily bridged by the heads 61Y, 61M, 61C, 61BK and the intermediate transfer body 37, the volume resistivity of the conductive rubber is 10 ^3. It is preferably less than Ω · cm, and preferably smaller than the volume resistivity of the recording liquid.

  The thickness of the surface layer 37b is preferably about 0.1 to 1 mm, and preferably 0.2 to 0.6 mm. However, the surface layer 37 b is not an essential component, and only the support 37 a may be used as the intermediate transfer member 37. Further, the intermediate transfer body 37 is not in a drum shape, but may be in an endless belt shape or in a sheet shape if possible.

  As shown in FIG. 1, the paper feeding unit 20 transports only the uppermost transfer paper S among the paper feed tray 21 on which a large number of transfer papers S can be stacked and the transfer paper S stacked on the paper feed tray 21. The sheet feeding roller 22 fed toward the unit 10, the casing 23 supporting the sheet feeding tray 21 and the sheet feeding roller 22, and the sheet feeding roller 22 are ejected from the recording liquid in the heads 61Y, 61M, 61C, 61BK. A motor or the like as a driving means (not shown) that rotates and feeds the transfer paper S in time with the timing, and a paper type detection means (not shown) that detects the type of the transfer paper S loaded on the paper feed tray 21 are provided. doing. Examples of paper type detection items by the paper type detection means include glossiness, thickness, bending strength, and the like.

  The carriage 50 can be replaced with a new one when the heads 61Y, 61M, 61C, 61BK are deteriorated, and in order to facilitate maintenance, the heads 61Y, 61M, 61C, 61BK can be replaced. And can be attached to and detached from the main body 99. Each of the heads 61Y, 61M, 61C, 61BK can be independently attached to and detached from the main body 99 so that it can be replaced with a new one when deterioration or the like occurs and for easy maintenance. ing. This facilitates replacement work and maintenance work.

  The ink discharge devices 60Y, 60M, 60C, and 60BK have substantially the same configuration with respect to the other points although the colors of the recording liquid to be used are different. Each of the ink ejection devices 60Y, 60M, 60C, and 60BK includes a plurality of heads 61Y, 61M, 61C, and 61BK that are arranged in the main scanning direction. The ink ejection devices 60Y, 60M, 60C, and 60BK, and the image forming apparatus 100 are heads. It is a fixed full line type.

  The ink ejection devices 60Y, 60M, 60C, and 60BK are ink cartridges 81Y, 81M, and 81C that are recording liquid cartridges as main tanks that store the recording liquids of the corresponding colors supplied to the plurality of heads 61Y, 61M, 61C, and 61BK. , 81BK, a pump (not shown) as a supply pump for pumping and feeding the recording liquid stored in the ink cartridges 81Y, 81M, 81C, 81BK toward the heads 61Y, 61M, 61C, 61BK, and a pump Is a distributor as an ink supply unit that is a recording liquid supply unit that distributes and supplies the recording liquid supplied from the ink cartridges 81Y, 81M, 81C, and 81BK to the heads 61Y, 61M, 61C, and 61BK. With distributor tank

  The ink ejection devices 60Y, 60M, 60C, and 60BK are also inks (not shown) as ink amount detection means that are recording liquid amount detection means for detecting the recording liquid amount in order to detect a shortage of the recording liquid amount in the distributor tank. An amount detection sensor, a pipe (not shown) that forms a feeding path for the recording liquid between the ink cartridges 81Y, 81M, 81C, 81BK and the distributor tank together with a pump; a distributor tank and each head 61Y, 61M, 61C; And a pipe (not shown) that forms a recording liquid feeding path between the unit and 61BK.

  The ink cartridges 81Y, 81M, 81C, 81BK are replaced with new ones when the internal recording liquid is consumed and the remaining amount is low or no longer used, and in order to facilitate maintenance. 99 is removable.

  The operation of the pump is controlled by the control unit 40. Specifically, on the condition that the ink amount detection sensor detects the shortage of the recording liquid amount in the distributor tank, it is driven until this shortage is not detected, and the recording in the ink cartridges 81Y, 81M, 81C, 81BK is performed. Supply liquid to distributor tank. In this respect, the control unit 40 functions as an ink supply control unit that is a recording liquid supply control unit. The control unit 40 controls the driving of the image forming apparatus 100 even when not specifically described.

  The recording liquid contains at least a colorant corresponding to yellow, magenta, cyan, and black, an anionic dispersant that is a dispersant for the colorant, and a solvent. Due to the colorant and the dispersant, the ink component of the recording liquid has an anionic group. The solvent contains water from the viewpoint of safety and the conductivity from the viewpoint of causing electrolysis to be described later, and the recording liquid is a water-soluble recording liquid that is a conductive ink and a water-soluble ink. The recording liquid is desirably alkaline from the viewpoint of storage stability.

The pigment that is a colorant used in the recording liquid is not particularly limited, but as a pigment for orange or yellow, C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 180, C.I. I. And CI Pigment Yellow 185.
Further, as a pigment for red or magenta, C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.
Further, as a pigment for green or cyan, C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.
Further, as a pigment for black, C.I. I. Pigment black 1, C.I. I. Pigment black 6, C.I. I. Pigment black 7 and the like.
The content of the pigment in the recording liquid is usually 0.1 to 40% by mass, preferably 1 to 30% by mass, and more preferably 2 to 20% by mass.

  Examples of the anionic dispersant include, but are not limited to, fatty acid salt, alkyl sulfate ester salt, alkyl benzene sulfonate, alkyl naphthalene sulfonate, dialkyl sulfosuccinate, alkyl phosphate ester salt, naphthalene sulfonate formalin condensate, poly Examples thereof include oxyethylene alkyl sulfate esters, and two or more of them may be used in combination.

From the viewpoint of transferability, the recording liquid preferably further contains a resin having an anionic group in which a carboxyl group, a sulfonic acid group, a phosphonic acid group or the like is neutralized with a base.
The recording liquid may further contain a solvent soluble in water. Solvents that are soluble in water are not particularly limited, but are polyvalent such as ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,5-pentanediol, 1,2,6-hexanetriol, and glycerin. Alcohols: ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, ethylene oxide adduct of diglycerin Polyhydric alcohol derivatives such as pyrrolidone, N-methyl-2-pyrrolidone, Nitrogen-containing solvents such as hexylpyrrolidone and triethanolamine; alcohols such as ethanol, isopropyl alcohol, butyl alcohol and benzyl alcohol; sulfur-containing solvents such as thiodiethanol, thiodiglycerol, sulfolane and dimethyl sulfoxide; propylene carbonate, ethylene carbonate and the like These may be used in combination of two or more.

  As shown in FIG. 2, each of the heads 61Y, 61M, 61C, 61BK includes a conductive nozzle plate 61a disposed on the recording liquid discharge side facing downward in the drawing and a nozzle 61b formed on the nozzle plate 61a. And an ink chamber 61c supplied with the recording liquid from the distributor tank and filled with the recording liquid, and an ink discharge means (not shown) for discharging the recording liquid in the ink chamber 61c from the nozzle 61b. The nozzle plate 61a, the nozzle 61b, the ink chamber 61c, and the ink discharge means are provided as a set, and each head 61Y, 61M, 61C, 61BK is provided in large numbers, but only one of them is shown in FIG. Is illustrated. The nozzle plate 61a is provided in each of the heads 61Y, 61M, 61C, 61BK, and is common to all the nozzles 61b in each of the heads 61Y, 61M, 61C, 61BK.

  Although detailed illustration is omitted, the nozzle plate 61 a includes a conductive substrate and a water repellent film formed on the surface of the substrate facing the intermediate transfer body 37. The water-repellent film may be formed by applying a fluorine-based water repellent or a silicon-based water repellent, or may be formed by plating a fluorine-based polymer or a fluorine-metal compound eutectoid, Any film having water repellency is not particularly limited. The nozzle plate 61a includes a surface on the ink chamber 61c side as an interface forming portion that forms an interface with the recording liquid in the ink chamber 61c, and functions as a cathode as will be described later.

  The entire nozzle plate 61a may be conductive, or may be a member in which only the surface on the ink chamber 61c side is subjected to conductive treatment, or an intermediate member between the conductive member disposed on the ink chamber 61c side. You may comprise by the insulating member arrange | positioned by the transfer body 37 side.

  Since the conductive portion of the nozzle plate 61a is provided as a cathode as will be described later, it does not have to be made of a material having resistance to metal elution, and if it is made of a highly conductive material such as metal or carbon. Good.

  The nozzle plate 61 a is set so that the gap with the intermediate transfer member 37 is 50 to 200 μm. If the gap is less than 50 μm, it may be difficult to maintain the gap between the intermediate transfer member 37, which is a rotating body, and the nozzle plate 61a. If the gap exceeds 200 μm, the liquid injection described later may be performed. This is because it may be difficult to form a bridge. However, if the gap can be maintained, there is no particular problem even if it is less than 50 μm, and even if it is 200 μm or more, there is no problem if a stable liquid column bridge is formed.

  The ink ejecting means has a piezoelectric element as an actuator for ejecting the recording liquid from each nozzle 61b to be ejected and landed on the transfer paper S, and responds to a voltage pulse applied to the piezoelectric element under the control of the control unit 40. Thus, the recording liquid is discharged from the nozzle 61b. In this regard, the control unit 40 functions as an ink ejection control unit. The control unit 40 functioning as an ink ejection control unit generates a voltage pulse for driving the piezoelectric element based on image data to be formed, and inputs the voltage pulse to each of the piezoelectric elements with a predetermined signal waveform.

  The actuator of the ink discharge means may be a movable actuator of another method that is a shape deformation element method such as a piezo method, or the recording liquid is discharged from the nozzle 61b by a heater method such as a thermal method. Also good.

  The energizing means 33 is realized as a part of the function of the power source 33a, a not-shown electric circuit in which the power source 33a is connected to the support 37a and the nozzle plate 61a, and a part of the function of the control unit 40. Voltage application control means for controlling time. The controller 40 as voltage application control means also functions as voltage changing means for changing the voltage of the power supply 33a.

  The power source 33a has an anode connected to the support 37a and a cathode connected to the nozzle plate 61a. Therefore, the energizing unit 33 includes the intermediate transfer member 37 as an anode and the nozzle plate 61a as a cathode. The power source 33a is provided in each of the heads 61Y, 61M, 61C, 61BK.

  As shown in FIG. 1, the cleaning means 34 is constituted by a cleaning blade as a cleaning member formed of rubber as an elastic body, which is in contact with the intermediate transfer body 37 in a so-called counter contact manner. . The cleaning unit 34 may include a cleaning roller as a cleaning member together with the cleaning blade.

  In the image forming apparatus 100 having such a configuration, the intermediate transfer body 37 rotates in the A1 direction while facing the heads 61Y, 61M, 61C, 61BK in response to the input of a predetermined signal indicating the start of image formation. In the process, the yellow, magenta, cyan, and black recording liquids are transferred from the heads 61Y, 61M, 61C, and 61BK so that the image areas of the respective colors of yellow, magenta, cyan, and black overlap with the same position on the intermediate transfer body 37. The images are ejected in such a manner that they are sequentially overlapped from the upstream side toward the downstream side in the A1 direction, and an image is temporarily carried on the intermediate transfer member 37.

At this time, the energizing unit 33 is driven by the control unit 40 as the voltage application control unit, and a voltage is applied between the support 37a and the nozzle plate 61a from the power source 33a.
In this state, the recording liquid is applied from the heads 61Y, 61M, 61C, 61BK onto the intermediate transfer body 37. At that time, first, the heads 61Y, 61M, 61C, 61BK are used as shown in FIG. As shown in FIG. 2B, the recording liquid forming a meniscus in the nozzle 61b moves toward the intermediate transfer body 37 as shown in FIG. 2B, and the recording liquid is recorded between the nozzle 61b and the intermediate transfer body 37. A bridge of a liquid column made of liquid is temporarily formed, and then, as shown in FIG. 2C, the bridge of the liquid column made of recording liquid is divided so as to be carried on the intermediate transfer body 37, and the intermediate transfer. An image of the recording liquid is formed on the body 37.

In the state where the liquid injection bridge made of the recording liquid is formed as shown in FIG. 2B, the colorant component in the recording liquid is subjected to an aggregating action by the energizing means 33. Specifically, the voltage application of the energizing means 33 causes the following electrode reactions to occur in the nozzle plate 61a serving as the cathode and the intermediate transfer member 37 serving as the anode, respectively, and the water contained in the bridge of the liquid column of the recording liquid. Electrolyzed.
^{_{Cathode: 4H 2 O + 4e - →}} 2H 2 + 4OH - ··· reaction formula (1)
_{^{Anode: 2H 2 O → 4H + +}} O 2 + 4e - ··· reaction formula (2)

  As a result, the water contained in the bridge of the liquid column of the recording liquid is oxidized on the surface of the intermediate transfer member 37 functioning as the anode to generate protons (H +), and as shown in FIG. The pigment P dispersed by D aggregates via protons. Thereby, the occurrence of bleeding between adjacent dots is suppressed, and a high-definition image is formed. In addition, there is an advantage that clogging of the nozzle 61b is prevented by such voltage application. The time for forming such a bridge can be controlled by the peak voltage and pulse width of the electromagnetic pulse applied to the piezoelectric element.

Here, the bridge of the liquid column formed between the cathode and the anode will be described with reference to FIG. Inside the bridge B of the liquid column, cations and anions move in the vicinity of the cathode C and the anode A, respectively. As a result, the surface of the cathode C and the anode A, the electric double layer E _C and E _A respectively is formed, the charging speed of the electric double layer E _C and E _A is the conductivity of the bridge B of the liquid column, recording It is almost determined by the concentration of ions contained in the liquid. At this time, when the voltage of the electric double layer E _A reaches several V, Faraday current flows water is electrolyzed. As a result, on the surface of the anode A, water is oxidized to generate protons, and the pigment dispersed by the anionic dispersant is aggregated. That is, at the moment when such a bridge is formed, ions that cause an aggregation action of the pigment are efficiently generated in the bridge, so that the pigment is aggregated simultaneously with the landing of the recording liquid on the intermediate transfer body 37. As a result, pigment bleeding does not occur between adjacent recording liquid dots, and a very high-definition solute image is formed.

  As described above, the energizing means 33 includes the intermediate transfer body 37 and the heads 61Y, 61M, 61C, 61BK, specifically the nozzle plate 61a for electrolyzing the recording liquid forming the bridge B of the liquid column. It is the structure for performing the voltage application between.

  The time from the formation of the bridge B of the liquid column to the separation is usually several microseconds to several tens of microseconds, and the conductivity of the recording liquid is usually several tens mS / m to several hundreds mS / second. m. For this reason, in order to form an image of the recording liquid on the intermediate transfer member 37, the voltage applied by the energizing means 33 is 1.23 V, which is the theoretical decomposition voltage of water, or a number that is a general condition for electrolysis of water. V to several tens of volts is insufficient, and it is preferably several tens of volts to several hundreds of volts.

  In accordance with the timing when the leading edge of the image carried on the intermediate transfer body 37 reaches the transfer unit 31, one sheet of transfer paper S fed from the paper supply unit 20 is supplied to the transfer unit 31 and transferred to the transfer member 38. The image carried on the intermediate transfer body 37 is transferred to the transfer paper S passing through the transfer section 31 while rotating in the B1 direction, and an image is formed on the surface of the transfer paper S. The transfer sheet S on which the image is formed is guided to the paper discharge tray 25 and stacked on the paper discharge tray 25.

  When the image is transferred to the transfer paper S in this way, the recording liquid containing the aggregation component is transferred to the transfer paper S. Therefore, by forming an image with the colorant aggregated by the above-described aggregation action, even when the transfer paper S is plain paper, high image density can be achieved at high speed while preventing or suppressing feathering and bleeding. High-quality image formation is possible.

  In order to perform high-speed image formation, since the recording liquid needs to be quick-drying, the recording liquid generally has high absorbability to the transfer paper S. In this case, the recording liquid is deep in the transfer paper S. Penetrating to the surface and causing so-called offset, making it unsuitable for double-sided image formation. However, since the aggregating action reduces the absorbability of the recording liquid onto the transfer paper S, such a set-off is prevented or suppressed, which is suitable for double-sided image formation. Furthermore, since the absorbability of the recording liquid to the transfer paper S is reduced, deformation of the transfer paper S such as cockling and curling is suppressed or prevented, and thereby the transfer paper S carrying an image is conveyed. The handling of the transfer sheet S is facilitated, for example, the property is improved and jamming is prevented or suppressed.

  Further, since the transfer portion 31 is non-linear, the transfer sheet S is pressed against the intermediate transfer member 37 for a long time, and the image on the intermediate transfer member 37 is transferred to the transfer sheet S with high efficiency as described above. Thus, even when the transfer sheet S is conveyed at high speed, high-quality image formation is performed. In addition, since the pressure profile is set as shown in FIG. 7A or a pressure profile which will be described later, the transfer efficiency is high and high-quality image formation is performed.

  The pressure profile shown in FIG. 7A has a plurality of, specifically two peaks, from the entrance to the exit of the transfer section 31, in other words, from the upstream side to the downstream side in the A1 direction. . The reason for this is as follows.

  According to the reaction formulas (1) and (2), since the viscosity of the recording liquid on the intermediate transfer member 37 increases when it contacts the intermediate transfer member 37, as shown in FIG. Among the droplets, the viscosity of the portion in contact with the intermediate transfer member 37 is high, and the viscosity decreases as the distance from the intermediate transfer member 37 increases. Therefore, using the pressure profile shown in FIG. 7A, immediately after the recording liquid and the transfer sheet S come into contact with each other, the pressure is increased and the low viscosity portion is transferred. And high transfer efficiency is achieved by reliably transferring ink with high viscosity.

  In recent years, recording liquids used in recent years use solid ink that changes the viscosity of the ink by chemical or electrical methods after ejection or melts at high temperatures for high image quality and high reliability. The types are also diversified. Under such circumstances, the state in each droplet of the recording liquid is not necessarily uniform, and it is necessary to continuously cope with the recording liquid in a plurality of states during the transfer.

  In the image forming apparatus 100, in order to adjust the viscosity of the recording liquid in contact with the intermediate transfer body 37, high-quality and high-efficiency transfer is realized by using the figure (a) or a pressure profile described later. . As described above, the ink characteristics vary depending on the image forming apparatus. By using a complex pressure profile that combines multiple pressure profiles, high image quality and high-efficiency transfer can be realized in various image forming apparatuses. It becomes.

  Due to the high-efficiency transfer in the transfer unit 31, almost no component due to the recording liquid remains on the intermediate transfer member 37 that has passed through the transfer unit 31, but the intermediate transfer member 37 is cleaned by the cleaning means 34. Thus, even if the recording liquid offset is highly prevented or suppressed and repeated image formation is performed, background contamination due to the offset is prevented or suppressed, and image deterioration and deterioration of the intermediate transfer member 37 are suppressed or prevented. It is possible to perform excellent image formation.

  In the image forming apparatus 100 as described above, the intermediate transfer body 37 has a drum shape, the transfer member 38 has a belt shape, and the transfer unit 31 is formed by support members 71 and 72 around which the transfer member 38 that is a belt member is wound. The transfer member 38 is wound from the inside so as to be non-linear, but in order to improve the transfer efficiency by obtaining a stable pressure as described above by making the transfer portion 31 non-linear, intermediate transfer is possible. At least one of the body 37 and the transfer member 38 may be a belt-like belt member, and the belt member may be wound from the inside by a plurality of support members so that the transfer part 31 is non-linear.

  Among the intermediate transfer member 37 and the transfer member 38, the configuration in which only the transfer member 38 is a belt member includes, for example, the configurations shown in FIGS. 10 to 14 and 19 in addition to the configurations shown in FIGS. Is mentioned. Examples of the configuration in which both the intermediate transfer member 37 and the transfer member 38 are belt members include the configurations shown in FIGS. Of the intermediate transfer member 37 and the transfer member 38, the configuration in which only the intermediate transfer member 37 is a belt member includes, for example, the configuration shown in FIG.

  If the intermediate transfer body 37 is a belt member, the mechanism is likely to be complicated, such as requiring a support member for supporting the belt. However, since the degree of freedom in layout is high, the size of the transfer portion 31 can be reduced even when the length is long. In addition, for example, as shown in FIG. 8, FIG. 9, FIG. 15 to FIG. 18 and FIG. 61C, 61BK can be arranged side by side, and there is an advantage that the space required for providing the heads 61Y, 61M, 61C, 61BK can be easily reduced. The former advantage is often obtained when both the intermediate transfer member 37 and the transfer member 38 are belt members, as shown in FIGS.

  It is sufficient that at least one pressurizing member 74 is provided so as to pressurize the belt member from the inside to obtain an appropriate pressure profile. For example, specifically, in order to obtain the pressure profile shown in FIG. 7A, two pressurizing members 74 may be provided so that pressurization by the pressurizing member 74 is performed at the pressure peak position. . The number of pressing members 74 corresponding to the number of peaks in the pressure profile may be provided.

  In this way, the position and number of contact of the pressure member 74 with the belt member are used to optimize the pressure profile as will be described later, such as the characteristics of the recording liquid to be used, so that the necessary pressure profile can be obtained. It can be appropriately changed according to various conditions used for the above. The number of the pressure members 74 may be greater than the number of peaks in the pressure profile.

  In the configuration in which the intermediate transfer member 37 and the transfer member 38 are both belt members, the pressure member 74 is configured to press the transfer member 38 from the inside as shown in FIGS. Alternatively, as shown in FIGS. 15 to 17, the intermediate transfer body 37 may be pressurized from the inside, or as shown in FIG. 18, the intermediate transfer body 37 and the transfer member You may make it pressurize both from 38 inside.

  The pressure member 74 is not limited to a roller shape, and may be a sled shape where the position of contact with the belt member is an arc shape. However, in reality, there is load and wear during sliding, so durability is improved. In consideration of this, a roller shape is preferable even if the transfer rate is somewhat sacrificed. On the other hand, a warp shape is more suitable for applying pressure according to the target pressure profile with the transfer rate as the highest priority. The same applies to the support member. In this article, the pressure member 74 is described as having a roller shape.

In the configuration shown in FIGS. 8 and 9, a sled support member is provided.
Specifically, in the configuration shown in FIG. 8, among the plurality of support members 91, 92, 93 around which the intermediate transfer body 37, which is a belt member, is wound, the support member 93 is warped, and the transfer unit 31. Is a non-linear guide member. The support members 91 and 92 have a roller shape, and face the portions of the intermediate transfer body 37 that are linearly stretched between the support member 91 and the support member 92, so as to face the heads 61Y, 61M, 61C, and 61BK. Is provided. The transfer member 38 side has the same configuration as that shown in FIG.

  In the configuration shown in FIG. 9, as a configuration on the transfer member 38 side, in addition to the configuration shown in FIG. 3, there is a warped support member 77 in which the transfer portion 31 is formed. Further, as a configuration on the intermediate transfer body 37 side, in place of the support member 93 shown in FIG. 8, there are warped support members 94 and 95 in which the transfer portions 31 are formed on both sides of the support member 77. The support members 77, 94, and 95 are guide members that make the transfer portion 31 non-linear. As described above, the shape, position, number, and the like of the support member and the guide member can be used in various combinations.

  As shown in FIGS. 10 and 11, the pressure member 74 may function as a position changing member whose position is changed and the pressure profile can be changed thereby. By using the pressure member 74 as the position varying member, various pressure profiles as described later can be realized with fewer pressure members 74. The configuration shown in FIG. 10 and the configuration shown in FIG. 11 are different from each other in the manner in which the pressure member 74 moves as described below. However, these movement modes may be used in combination. As the driving means for changing the position of the pressing member 74, a known mechanism can be used.

  In the configuration shown in FIG. 10, the pressure member 74 is provided as a position varying member that can move along the peripheral surface of the intermediate transfer body 37, and the position where the pressure is applied can be changed in the transfer unit 31. The position is changed so that the position where the pressurized state is formed can be arbitrarily changed.

  In the configuration shown in FIG. 11, there are a plurality of, specifically two, pressure members 74, and selectively, in other words, the intermediate transfer member so that each of the pressure states can be released independently. 37 is provided as a position changing member whose position is changed in a direction in which it contacts and separates from 37. The pressurizing member 74 can be changed in its position in a direction in which the pressurizing member 74 is brought into contact with and separated from the intermediate transfer member 37.

  Since the pressure member 74 is provided as the position variation member in this way, the pressure profile can be changed. However, in the transfer device 64, the pressure profile is the same as that of the transfer sheet S as shown in FIG. It can be changed and optimized depending on the physical properties and / or the amount of recording liquid applied to the intermediate transfer member 37 and / or the environment related to the greenhouse. By switching the pressure profile, transfer is performed under an optimum pressure profile in accordance with a change in physical properties of the recording liquid due to environmental conditions, a combination of the recording liquid and the transfer paper S, etc., and high transfer efficiency is obtained.

  FIG. 4A shows an example in which the pressure profile is changed on the condition of the physical properties of the transfer paper S. FIG. 4B shows the pressure profile on the condition of the amount of recording liquid applied to the intermediate transfer body 37. FIG. 4C shows an example of changing the pressure profile with the environment related to the greenhouse temperature as a condition. However, two or all of these conditions are used in combination. Also good.

  The change of the pressure profile is performed by the control unit 40 by selecting a pressure profile according to such conditions. In this respect, the control unit 40 functions as a pressure profile changing unit and a pressure profile selecting unit. The control unit 40 changes the position of the pressing member 74 so as to match the selected and changed pressure profile. In this regard, the control unit 40 functions as a pressure profile setting unit.

  The pressure profile change and selection operations performed in the control unit 40 functioning as a pressure profile change means and a pressure profile selection means in each case shown in FIGS.

  In the case shown in FIG. 5A, the control unit 40 acquires the type, thickness, and the like of the transfer sheet S used for image formation. This acquisition is detected based on the paper type specified by the setting on the operation panel or the print setting by an external input device such as a PC connected to the image forming apparatus 100 (S11), or detected by the paper type detecting means. This is performed based on the type of paper (S12).

  Based on the paper type acquired in this way, the control unit 40 functioning as a pressure profile changing unit and a pressure profile selecting unit determines and selects a paper type to be used for changing and selecting the pressure profile ( In step S13, an optimum pressure profile is selected and changed (S14). The control unit 40 functioning as the pressure profile setting means changes the position of the pressure member 74 and changes the applied pressure so as to form the selected and changed pressure profile (S15).

  For example, as the transfer paper S, in addition to plain paper, paper having better permeability than plain paper such as dedicated coated paper, and conversely, paper having poor permeability may be used. In addition, the permeability of the recording liquid varies depending on the unevenness of the surface of the transfer paper S, the constituent material, and the moisture absorption characteristics. Therefore, by controlling to change the pressure profile according to such physical properties of the transfer sheet S, an optimum pressure profile is set for each of the various transfer sheets S, and high-quality and high-efficiency transfer is realized.

  As will be described later, the pressurizing member 74 may be provided as a member common to the support member. Therefore, when the pressurizing member 74 constitutes a support member, the movement of the pressurizing member 74 is caused by the movement thereof. Along with the change, at least a part of the travel position of the transfer member 38 and the intermediate transfer body 37 which are belt members is changed, and the position of the transfer unit 31 is changed. This also applies to the cases shown in FIGS.

  In addition, the shorter the pressurization time, the lower the deterioration of these members when using the intermediate transfer body 37 and the pressurization member 74, particularly the warped pressurization member 74. Therefore, the pressurization time while ensuring transfer efficiency is reduced. If a pressure profile that shortens is selected, high image quality and high-efficiency transfer can be realized while minimizing the burden on the member. This also applies to the cases shown in FIGS.

  In the case shown in FIG. 5B, the control unit 40 acquires the amount of the recording liquid ejected from the heads 61Y, 61M, 61C, 61BK and applied to the intermediate transfer body 37. This acquisition is performed by the control unit 40 functioning as the ink ejection control unit based on the print data used when generating the voltage pulse for driving the piezoelectric element in the control unit 40 functioning as the ink ejection control unit (S21). This is done by calculating the amount of recording liquid ejected from the heads 61Y, 61M, 61C, 61BK (S22).

  The control unit 40 functioning as a pressure profile changing unit and a pressure profile selecting unit selects and changes to an optimal pressure profile based on the recording liquid amount thus acquired (S23). The control unit 40 functioning as the pressure profile setting means changes the position of the pressure member 74 and changes the applied pressure so as to form the selected and changed pressure profile (S24).

  The time for which the recording liquid penetrates the transfer paper S depends on the amount of the recording liquid. For example, when the recording liquid amount is small and the image density is sparse, the pressurization time may be relatively short. When there are many, it is necessary to take long pressurization time. Therefore, by analyzing the print data, the amount of recording liquid, that is, the amount of recording liquid adhering to the transfer paper S is calculated, and control is performed so that the pressure profile is changed according to the calculation result, which is optimal for recording each print data. A high pressure profile is set to achieve high image quality and high-efficiency transfer.

  In the case shown in FIG. 5C, the control unit 40 acquires the temperature and humidity of the environment where the image forming apparatus 100 is placed. This acquisition is performed by detecting the temperature and humidity by the temperature / humidity detection means (S31) and inputting environmental data relating to the temperature and humidity to the control unit 40.

  The control unit 40 functioning as a pressure profile changing unit and a pressure profile selecting unit determines whether or not the environment is used for selecting and changing the pressure profile, for example, at a low temperature, based on the recording liquid amount thus obtained. Whether or not the humidity is high is determined and selected (S32), and the pressure profile is changed and selected (S33). The control unit 40 functioning as the pressure profile setting means changes the position of the pressure member 74 and changes the applied pressure so as to form the selected and changed pressure profile (S34).

  For example, in a low temperature environment, the viscosity of the recording liquid becomes high and does not easily permeate and spread on the transfer paper S. Therefore, in order to improve the fixability and image density, the applied pressure at the entrance of the transfer unit 31 is compared with that in the normal temperature environment. The pressure profile is selected and changed from the viewpoint of increasing the length of the transfer unit 31 and increasing the pressurization time so as to increase it. The environment in which the image forming apparatus 100 is used varies, and the physical properties and behavior of the recording liquid differ depending on the temperature and humidity environment. Therefore, by controlling to change the pressure profile according to the temperature and humidity environment, the optimum pressure for transfer A profile is set to achieve high image quality and high-efficiency transfer. However, the pressure profile may be set using only one of temperature and humidity.

  As shown in FIGS. 12 to 19, the pressure member 74 may be used as a support member and a member common to the support member. If the intermediate transfer member 37 and the transfer member 38 are belt members, the mechanism tends to be complicated because a member for winding the belt member is required. However, the function of the pressure member 74 and the function of the support member are ensured by using both of them. However, such complication is suppressed.

  In the configuration shown in these drawings, the pressure member 74 provided as a member common to the support member has a roller shape, so that the running performance of the belt member is improved and the durability of the belt member is further improved. . The pressurizing member 74 may be a member provided at a fixed position, or may be provided as a position varying member.

  In the configuration shown in FIG. 12, in the configuration shown in FIGS. 1 and 3, the pressure member 74 is provided at the position of the support roller 71, the support roller 71 is omitted, and the pressure member 74 is used as the inlet member of the transfer unit 31. It is provided as.

  In the configuration shown in FIG. 13, in the configuration shown in FIGS. 1 and 3, a pressure member 74 is provided instead of the support roller 71 and two pressure members 74 are provided. The provided pressure member 74 is used as an inlet member of the transfer unit 31.

  In the configuration shown in FIG. 14, in the configuration shown in FIGS. 1 and 3, the pressure member 74 is provided at the position of the support rollers 71 and 72, the support rollers 71 and 72 are omitted, and the pressure members 74 are transferred. It is provided as an inlet member and an outlet member of the portion 31.

  In the configuration shown in FIG. 15, the pressure member 74 is provided as a member that is commonly used as a support member around which the intermediate transfer member 37 that is a belt member is wound. Specifically, in the configuration shown in FIG. 9, the pressure member 74 is provided at the position of the support member 94 in the configuration shown in FIG. It is provided as an inlet member. In addition, as compared with the configuration shown in FIG. 9, the support member 77 is enlarged, and the support member 95 has a roller shape and is provided at a position away from the support member 77, and the support roller 73 is omitted. ing.

  In the configuration shown in FIG. 16, in addition to the configuration shown in FIG. 15, the configuration includes a pressure member 74 provided inside the intermediate transfer body 37, which is a belt member, and includes two pressure members 74. It is said.

  In the configuration shown in FIG. 17, in the configuration shown in FIG. 15, the pressure member 74 is provided instead of the support member 95, the support member 95 is omitted, and the pressure member 74 is provided as an outlet member.

  In the configuration shown in FIG. 18, in the configuration shown in FIG. 15, a pressure member 74 is added inside the intermediate transfer member 37 that is a belt member, so that three pressure members 74 in the intermediate transfer member 37 are provided. At the same time, the support member 77 is omitted, and two pressure members 74 located inside the transfer member 38, which is a belt member, are provided at two positions between the three pressure members 74 in the intermediate transfer body 37. The transfer unit 31 is provided only on the peripheral surface of the pressure member 74. As described above, by increasing the number of the pressure members 74, it is possible to increase the distance of the transfer unit 31 without increasing the size of the transfer device 64 and to increase the pressure time of the transfer paper S.

  In the configuration shown in FIG. 19, the diameter of the pressure member 74 on the outlet side of the two pressure members 74 forming the inlet and the outlet of the transfer unit 31 in the configuration shown in FIG. It is larger than the diameter of the pressure member 74 on the side, and the support roller 73 is omitted.

  Thus, by making the curvature radius of the part forming the transfer part 31 on the end side of the transfer part 31 larger than the curvature radius of the part forming the transfer part 31 on the start side of the transfer part 31, A pressure profile in which the pressure fluctuation at the outlet of the transfer unit 31 is gentle is formed. Due to this pressure profile, the speed at which the transfer sheet S passing through the transfer section 31 and the intermediate transfer body 37 are separated from each other becomes slow, and the recording liquid on the intermediate transfer body 37 is easily attracted to the transfer sheet S side by surface tension. As a result, the transfer efficiency is improved, and there are obtained advantages such that the remaining recording liquid on the intermediate transfer member 37 is reduced.

  Such a relationship between the radii of curvature can be applied even when the support member is not a pressure member, and can also be applied to a support member in the intermediate transfer body when the intermediate transfer body is a belt member. Thus, the same advantage as this advantage can be obtained. Further, in the case where one member serves both as the inlet side and the outlet side as in the supporting member 77 shown in FIGS. 15, 16, and 17, and the supporting member 93 shown in FIG. The curvature radius may be adjusted so as to satisfy this relationship between the inlet side and the outlet side of the two support members.

  In the configuration shown in FIG. 20, only the intermediate transfer member 37 is a belt member, and the belt member and the drum-shaped member are related to the configurations shown in FIGS. The relationship with is reversed. Even when only the intermediate transfer member 37 is a belt member as in the configuration shown in FIG. 20, the pressurization modes shown in FIG. 1, FIG. 3, FIG. 10 to FIG. Is possible. This is the same in a configuration different from the configuration shown in FIG. 20, and other configurations can be used in appropriate combination.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments, and the present invention described in the claims is not specifically limited by the above description. Various modifications and changes are possible within the scope of the above.

  For example, the image forming apparatus to which the present invention is applied is not limited to the above-mentioned type of image forming apparatus, but may be another type of image forming apparatus, that is, a shuttle type with respect to the head, and may be a copying machine, a facsimile , Plotters, printing presses alone or their combined machines, monochrome machines related to them, other image forming apparatuses used for forming electric circuits, and images used to form predetermined images in the biotechnology field It may be a forming device. The number of heads is increased or decreased according to the application of the image forming apparatus, and may be one or plural.

The pigment in the recording liquid may be dispersed by a cationic dispersant and aggregated via hydroxide ions generated on the surface of the intermediate transfer member functioning as a cathode.
The intermediate transfer member does not need to be conductive as a whole, and at least the surface may be conductive.

  The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

Reference Signs List 31 Conveyance path 37 Intermediate transfer member, belt member 38 Transfer member, belt member 61Y, 61M, 61C, 61BK Recording liquid discharge head 64 Transfer device 71, 72, 73, 74, 77 Plural support members for transfer member as belt members 74, 91, 92, 93, 94, 95 A plurality of support members for the intermediate transfer member as a belt member 74 Pressure member, position variation member, pressure roller 71, 74, 93 Support member 72, 74, 94 on the inlet side Support member on exit side 100 Image forming apparatus A1 Movement direction of intermediate transfer member S Recording material

JP 2008-80656 A JP 2010-253727 A JP-A-6-155725 Japanese Patent No. 3211845 JP 2000-326559 A

Claims (8)

An intermediate transfer member that is applied with ink ejected by an ink ejection head and moves in a predetermined direction;
A transfer member that forms a conveyance path for transferring the ink on the intermediate transfer member to the recording material while conveying the recording material along the predetermined direction;
At least one of the intermediate transfer member and the transfer member is a belt-like belt member,
A plurality of support members wound around the belt member from the inside so that the transport path is non-linear;
The belt member is pressed from the inside so that the recording material transported through the transport path is pressed between the intermediate transfer member and the transfer member in the transport path. A transfer device having at least one pressure member; The transfer apparatus according to claim 1, wherein
At least one of the pressurizing members is a position changing member whose position is changed so that the state can be released and / or a position where the state is reached can be changed in the transport path. The transfer device. The transfer device according to claim 2.
The pressure distribution between the intermediate transfer member and the transfer member in the transport path is a pressure corresponding to the physical properties of the recording material and / or the amount of ink applied to the intermediate transfer member and / or the environment relating to temperature and humidity. The transfer device, wherein the position of the position changing member is changed so as to be distributed. The transfer apparatus according to any one of claims 1 to 3,
At least one of the pressure members is a member common to the support member. The transfer device according to claim 4, wherein
The transfer device, wherein the pressure member in common with the support member is a pressure roller. In the transfer device according to any one of claims 1 to 5,
Among the plurality of support members, which are located on the same side of the transport path and form the entrance and the exit of the transport path, form the transport path of the support member on the outlet side The transfer apparatus, wherein the radius of curvature of the portion is larger than the radius of curvature of the portion of the support member on the inlet side that forms the transport path. The transfer device according to any one of claims 1 to 6,
The transfer device, wherein the pressure distribution between the intermediate transfer member and the transfer member in the transport path has a plurality of peaks.   An image forming apparatus comprising the transfer device according to claim 1.

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