JP4586078B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus including a recording unit.

  In an image forming apparatus including an ink jet recording unit, for example, an ink jet printer, there are problems of initial image quality such as ink bleeding and show-through due to ink penetration, and problems of image fastness such as water resistance and light resistance. Need to be resolved.

As a means for solving them, a recording material in which a material for fixing the dye in the ink is fixed on the surface of the recording material, such as plain paper, or a recording material in which a white pigment or a water-soluble polymer is applied on the surface The technique using this is disclosed (for example, see Patent Documents 1, 2, and 3) . However, there is an inconvenience that it is necessary to purchase a dedicated recording material that has been coated, and there is a problem that the writing performance with a pencil or a pen is reduced for such a dedicated recording material.

As a countermeasure on the ink side, a technique is disclosed in which a surfactant is added to the ink to prevent bleeding and the permeability of the ink is increased (see, for example, Patent Document 4) . This is effective for bleeding between two colors and smearing (image contamination due to contact after image formation) because the ink penetrates the recording material at high speed, but show-through tends to occur.

Furthermore, as a countermeasure on the ink side, a method of adding a volatile solvent to the ink is disclosed (for example, see Patent Document 5) . This ink can provide the same effect as the ink with improved permeability described above, but the nozzle from which the ink is ejected is likely to be clogged.

  In addition, as a countermeasure on the ink side, the use of ink containing a pigment as a coloring material is increasing in order to improve water resistance and light resistance. However, ink containing a pigment has a reliability around the nozzle such as clogging. Difficult to maintain. In addition, when high color reproducibility such as photographic images and computer graphics is required, there is a problem that cyan and magenta colors are insufficiently developed and satisfactory images cannot be obtained.

Therefore, an ink jet recording method has been proposed in which an image is formed by ejecting a polymer solution onto the surface of a recording material and forming ink on the surface to which the polymer solution is adhered before forming an image by the ink jet method (for example, patents). Reference 6) . However, this method can improve the sharpness of the image, but the image has a low drying property, and a color image in which different color inks are superimposed does not show an image improvement effect.

Also disclosed is a method of spraying an image recording promoting liquid onto a recording material (see, for example, Patent Documents 7, 8, and 9) . However, this method has a problem in that the amount of moisture adhering at the two-color overlapping portion increases, so that bleeding at the color boundary cannot be sufficiently suppressed, and bleeding and show-through are large. Further, cockling (waving) of the recording material due to the moisture of the image recording promoting liquid occurs. Further, since the image recording accelerating liquid is stably ejected, there is a problem that the liquid composition such as the liquid viscosity and the surface tension and the nozzle diameter are restricted, and the degree of freedom is remarkably reduced.

On the other hand, a method of applying an image recording promoting liquid (pretreatment liquid) to the entire surface of a recording material using a roller is disclosed (for example, see Patent Document 10) . This is a method in which a pretreatment liquid for improving image quality is applied in advance to an image forming region with an application roller, and according to this publication, the viscosity is higher than the method of spraying the pretreatment liquid using an ejection head. The pretreatment liquid can be thinly applied, and image bleeding can be further reduced.

JP-A-56-86789 JP-A-55-144172 JP 52-53012 A JP 55-65269 A JP-A-55-66976 JP-A-56-89595 JP-A-64-63185 JP-A-8-20159 Japanese Patent Laid-Open No. 8-20161 JP 7-156538 A

  However, in the invention described in the above-mentioned publication, a conveying roller (platen) for conveying a recording material and an application roller (coating roller) for applying a pretreatment liquid are interlocked via the recording material to be conveyed. Rotate. For this reason, when the recording head is moving in the main scanning direction while ejecting ink and the conveyance of the recording material in the sub-scanning direction (direction orthogonal to the moving direction of the recording head) is temporarily stopped The application roller whose rotation has been stopped is pressed against the recording material whose conveyance has been stopped. As a result, a large amount of pretreatment liquid is applied to the portion of the recording material that has been pressed in a state where the application roller has stopped rotating, compared to the other portions, resulting in uneven application of the pretreatment liquid. As a result, the waviness and image quality unevenness of the recording material occur.

  Further, when a line head having the length dimension of the image forming area in the main scanning direction is used as the recording head, it is not necessary to move the line head in the main scanning direction during image formation. It is possible to carry at a stable speed in the sub-scanning direction. However, in order to improve productivity, the conveyance speed of the recording material in the sub-scanning direction is changed depending on the presence or absence of the image forming area. In other words, when the image forming area exists in the portion of the recording material facing the line head, the conveyance speed of the recording material is decreased, and the image forming area does not exist in the portion of the recording material facing the line head. In the case of (a blank portion), the conveyance speed of the recording material is increased. Then, with such a change in the conveyance speed, the application speed of the pretreatment liquid by the application roller also changes, and the pretreatment liquid cannot be uniformly applied.

The present invention was made in view of the above, in an image forming apparatus having a recording unit, to provide an image forming apparatus for evenly at a constant speed application of the pretreatment liquid to the recording medium Objective.

Another object of the present invention is to provide an image forming apparatus provided with a recording unit, which stably feeds a recording material coated with a pretreatment liquid to the recording unit at a small interval .

In order to solve the above-described problems and achieve the object, an image forming apparatus according to a first aspect of the present invention includes a recording material storage portion for stacking and holding recording materials, and applying a liquid to the recording materials. A coating unit that performs pre-processing, a reversing tray that is exposed to the outside from the apparatus main body and into which the pre-processed recording material is fed, and a recording unit that forms an image on the recording material fed from the reversing tray And the recording material is fed to the reversing tray with the pretreated surface coated with the liquid as an upper surface, and the feeding direction is reversed by the reversing tray and sent to the recording unit, An image is formed by the recording unit . According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, at least one of a preceding recording material fed from the reversing tray and a subsequent recording material fed to the reversing tray. The part is superimposed on the reversing tray, and the transport speed of the fed recording material is a predetermined transport speed determined up to the reversing tray, and thereafter the transport speed is variable. It is characterized by being.

Here, in the present invention and the following invention, the “pretreatment liquid” means that the ink ejected from the recording unit is attached to the recording material in advance to form an image before the ink is attached to the recording material. The liquid which can improve the quality of the image formed by apply | coating is meant. For example, the colorant contained in the ink is agglomerated and retained on the recording material, and has a function of promoting the penetration of only the ink solvent into the recording material . 10 is disclosed. By applying such a pretreatment liquid, the ink adhering to the recording medium has less variation in dot size and higher roundness, and consequently the quality of the image formed on the recording medium. Will improve.

Therefore, the recording materials stacked and held in the recording material storage unit are separated and fed one by one and conveyed to the recording unit through the feeding conveyance path, and the pretreatment liquid is applied in the coating unit during the conveyance. Then, the recording material coated with the pretreatment liquid is once sent to the reverse tray. The recording material fed into the reversing tray is switched back by the recording material reversing means and fed into the recording unit, and an image is formed on the recording material. Since the pretreatment liquid is applied to the surface of the recording material sent to the recording unit, the quality of the image formed on the recording material is improved.

According to a third aspect of the present invention, in the image forming apparatus according to the second aspect of the present invention, the recording material that has been fed is opened and the fed recording material is switched back and sent out. A recording material reversing unit that can be switched between a feeding state and a recording material reversing unit is further provided. When the recording material reversing unit is in an open state, the preceding recording material fed from the reversing tray and the reversing tray are provided. It is characterized in that at least a part of the subsequent recording material to be fed is superposed.

According to a fourth aspect of the present invention, there is provided the image forming apparatus according to any one of the first to third aspects, wherein the recording material is intermittently fed in a direction in which the recording material is fed to the inlet / outlet side of the recording material to the reversing tray. And a reversing roller that is rotationally driven.

According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the application unit rotates in contact with the image forming surface of the recording material to be conveyed. And a coating roller for coating the pretreatment liquid.

According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the reversing tray is a recording target in which recording materials fed to the recording unit are stacked and held. It has a function as a material storage part.

According to an eighth aspect of the present invention, in the image forming apparatus according to the third aspect, the recording material reversing unit separates and feeds the recording materials stacked and held on the reversing tray one by one. It has a function as a sheet feeding means.

According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the first to eighth aspects, a conveyance speed V1 of a recording material conveyed from the recording material storage unit to the reversing tray is set. The recording material is set so as to be faster than the average conveying speed V2 of the recording material conveyed through the recording unit.

According to the present invention, the conveyance of the recording material from the recording material storage unit to the reversing tray can be performed at a constant speed (predetermined conveyance speed) independently of the conveyance of the recording material in the recording unit. Therefore, the application of the pretreatment liquid to the recording material while the recording material is being conveyed from the recording material storage unit to the reversing tray is performed at a constant speed regardless of the recording material conveyance speed at the recording unit. Can improve the quality of the image formed on the recording material by preventing the waviness of the recording material and the occurrence of uneven image quality caused by uneven application of the pretreatment liquid. it can.

Further, according to the present invention, the recording material after the pretreatment liquid is applied is sent to the reversing tray, switched back, and sent to the recording unit, thereby drying the pretreatment liquid applied to the recording material. Can be ensured, and the quality of the image formed on the recording material can be further improved.

Further, according to the present invention, when the recording material reversing means is opened, at least a part of the preceding recording material fed from the reversing tray and the subsequent recording material fed to the reversing tray. By controlling the feeding speed of the recording material into the reversing tray, the feeding speed of the recording material from the reversing tray, the timing of feeding the recording material from the reversing tray, etc. The interval between the recording materials that are switched back and sent to the recording unit can be reduced, so that when the interval between the recording materials fed from the recording material storage unit is reduced, the recording material storage unit Even if there is a variation in the feeding timing from the sheet or a variation in the conveyance speed during the conveyance to the reversing tray, it is possible to prevent the recording materials before and after overlapping from being overlapped. The feeding of the recording material to the parts to a smaller interval can be accurately maintained, it is possible to increase the productivity of the image forming operation in the image forming apparatus.

In addition, according to the present invention, the application unit includes the application roller that applies the pretreatment liquid by rotating in contact with the image forming surface of the recording material to be conveyed. A liquid having a high viscosity can be used, and the pretreatment liquid can be applied thinly.

Further, according to the present invention, the reversing tray has a function as a recording material storage unit for stacking and holding recording materials fed to the recording unit. When using the recording material, the recording material can be stacked and held on the reversing tray and fed from the reversing tray to the recording unit. There is no need to separately provide a dedicated tray for feeding such a recording material, and the types of recording materials that can be used while maintaining a compact configuration can be increased.

Further, according to the present invention, the recording material reversing unit functions as a separation paper feeding unit that separates and feeds the recording materials stacked and held on the reversing tray one by one. In the case of feeding the recorded recording material, it is possible to prevent double feeding without providing a separate feeding unit.

Further, according to the present invention, the conveyance speed V1 of the recording material conveyed from the recording material storage unit to the reverse tray is set higher than the average conveyance speed V2 of the recording material conveyed through the recording unit. , It becomes possible to take much waiting time of the recording material in the reversing tray, and even if there is a change in the conveying speed in the recording unit or a delay in conveying to the reversing tray due to the existence of this waiting time, High productivity can be maintained by maintaining a constant interval between recording materials fed into the recording unit.

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the structure of an image forming apparatus provided with an ink jet recording unit, and FIG . 2-1 is an explanatory diagram of the operation of the recording material reversing means in the open state. FIG. 2B is an explanatory diagram of the operation of the recording material reversing means in the delivery state.

  As shown in FIG. 1, the image forming apparatus includes a paper feed tray 1 that is a recording material storage unit in which recording materials are stacked and held, and an ink jet recording unit 2 that forms an image on the fed recording material. A paper discharge tray 3 and the like for discharging the recording material on which the image is formed are provided. Further, the image forming apparatus is provided with a paper feed conveyance path 4 from the paper feed tray 1 to the ink jet recording unit 2, and a reversing tray 5 is connected in the middle of the paper feed conveyance path 4. Yes. Further, on the upstream side of the reversing tray 5 on the paper feed conveyance path 4, a pretreatment liquid application unit 6 for applying a pretreatment liquid to the recording material conveyed on the paper feed conveyance path 4 is provided. It has been.

  The paper feed tray 1 is detachably attached to the image forming apparatus. In the vicinity of the mounting position of the paper feed tray 1 in the image forming apparatus, recording materials stacked and held in the paper feed tray 1 are placed. A feed roller 7 that feeds out and a separation pad 8 that is in contact with the outer peripheral surface of the feed roller 7 and prevents double feeding of recording materials are provided.

  The inkjet recording unit 2 includes a recording head 9 that ejects ink droplets according to image data, a conveyance roller 10 that conveys a recording material, and a paper discharge that discharges the recording material after image formation onto a paper discharge tray 3. A roller 11 is provided.

  On the paper feed transport path 4, transport rollers 12 a and 12 b that transport the recording material fed from the paper feed tray 1, and the recording material transported on the paper feed transport path 4 are placed in the reverse tray 5. A switching claw 13 is provided that can be switched between a position where the recording material is fed back to the inkjet recording unit 2 and a position where the recording material switched back in the reversing tray 5 is directed to the inkjet recording unit 2. The switching claw 13 is connected to switching means such as a solenoid that rotates to each switching position. Further, as a configuration for rotating the switching claw 13 to each switching position, the switching claw 13 is moved by a spring to the conveying roller 12a side (a position where the recording material switched back in the reversing tray 5 is directed to the inkjet recording unit 2). When the recording material is fed into the reversing tray 5, the recording material passing between the conveying roller 12a and the switching claw 13 resists the urging force of the spring. It is good also as a structure which pushes up.

  In the reverse tray 5, the recording material fed from the paper feed tray 1 and transported through the paper feeding transport path 4 is once sent, and the once fed recording material is switched back toward the ink jet recording unit 2. In addition to being a part that is sent out again onto the paper feed conveyance path 4, it is a part that has a function as a recording material storage unit that stacks and holds a large number of recording materials fed to the inkjet recording unit 2.

On the inlet / outlet side of the recording material to the reversing tray 5, there are provided recording material reversing means 14, a pickup roller 15, a bottom plate (not shown) that can be moved up and down, and the like. As shown in FIGS. 2A and 2B , the recording material reversing unit 14 is intermittently rotated by a stepping motor (not shown) so as to feed the recording material from the reversing tray 5. And a counter roller 17 disposed at a position where the outer peripheral surface comes into contact with the outer peripheral surface of the reverse roller 16. A part of the outer peripheral portion of the reversing roller 16 is formed with a notch 16 a that forms a gap with the outer peripheral surface of the opposing roller 17 when facing the opposing roller 17. The rotating shaft of the opposing roller 17 is provided with a clutch (not shown) and a torque limiter (not shown). When the clutch is on, the rotating roller 16 has the same direction as the reverse roller 16. Is transmitted.

  The recording material reversing means 14 switches back the recording material fed to the reversing tray 5 and feeds it to the paper feed conveyance path 4, and reverses the preceding recording material fed from the reversing tray 5. It is provided so as to be switchable to an open state in which at least a part of the subsequent recording material fed into the tray 5 is allowed to overlap.

2 -2, reversing roller 16 and the outer peripheral surface in contact with the outer peripheral surface and the opposed roller 17 of the reversing roller 16 is rotated in the arrow direction, and the state feed the opposing roller 17 is rotated together in the direction of the arrow It is. As a result, the recording material fed into the reversing tray 5 is sandwiched between the reversing roller 16 and the opposing roller 17, switched back, and fed onto the paper feed conveyance path 4.

2 -1, notch 16a is rotated driving of the reversing rollers 16 while facing the opposing roller 17 is stopped, an open state in which a gap is formed between the reverse roller 16 and the opposed roller 17. As a result, the preceding recording material is fed out from the reversing tray 5 and the subsequent recording material is fed into the reversing tray 5 at the same time, and at least a part of the preceding recording material and the succeeding recording material. Are superimposed in the reverse tray 5. When the recording material is fed into the reversing tray 5 and the recording material is switched back in the reversing tray 5, that is, to the recording material fed from the paper feed tray 1. When the image formation is performed, the clutch provided on the rotating shaft of the facing roller 17 is turned off.

  When a large number of recording materials are stacked and held on the reversing tray 5, the pickup roller 15 abuts on the uppermost recording material raised by raising the bottom plate and directs the recording material to the ink jet recording unit 2. It is a roller to send out. When the recording materials stacked and held on the reversing tray 5 are sent out toward the ink jet recording unit 2, the recording material reversing means 14 prevents separation of the recording materials and separates and feeds them one by one. It functions as a paper feeding means. That is, the clutch is turned on, and the counter roller 17 is transmitted with a rotational force in a direction to return the recording material onto the reverse tray 5. As a result, when two or more recording materials enter between the reversing roller 16 and the opposing roller 17, only one recording material (the highest recording material) in contact with the reversing roller 16 is present. The recording material is fed toward the ink jet recording unit 2, and the other recording material is returned onto the reverse tray 5 by the rotational force of the opposing roller 17. When only one recording material exists between the reverse roller 16 and the counter roller 17, the counter roller 17 is rotated by the reverse roller 16 due to slippage at the torque limiter.

  Of the paper feed conveyance path 4, a portion from the reversing tray 5 to the inkjet recording unit 2 is formed in a straight shape. Thus, a thick recording material can be stacked and held on the reversing tray 5, and the recording material can be separated and conveyed to the inkjet recording unit 2, and it is difficult to bend it during conveyance. Image formation on the recording material can be performed.

  Further, the reverse tray 5 is open at the rear end portion in the paper feeding direction. Accordingly, even a long recording material that cannot be stored in the paper feed tray 1 can be stacked and held on the reversing tray 5, and image formation on such a long recording material is performed. Will be able to.

  The pretreatment liquid application unit 6 includes a pretreatment liquid tank 19 that contains the pretreatment liquid 18, a pumping roller 20 that pumps up the pretreatment liquid 18 while stirring, and an application that transfers the pumped pretreatment liquid to the outer peripheral surface. A roller 21, a film thickness control blade 22 for controlling the pretreatment liquid 18 transferred onto the outer peripheral surface of the application roller 21 to a uniform film thickness, and a recording material fed from the paper feed tray 1. And a counter roller 23 that assists in applying the pretreatment liquid 18 to the recording material. The pretreatment liquid 18 contains a compound that agglomerates the colorant contained in the ink and keeps it on the recording material, and is a liquid that accelerates the penetration of only the ink solvent into the recording material.

  The recording material conveyed through the ink jet recording unit 2 stops when the recording head 9 is moving in the main scanning direction while performing the image forming operation, and also when the recording head 9 is a line head and the image forming operation is performed. Even when the recording material does not move in the main scanning direction, the conveyance speed of the recording material changes depending on the presence or absence of an image area on the recording material. Here, in this image forming apparatus, the conveyance speed V1 of the recording material conveyed from the paper feed tray 1 to the reverse tray 5 is set to be higher than the average conveyance speed V2 of the recording material conveyed through the inkjet recording unit 2. Has been. This average conveyance speed V2 assumes a case of a 6% sheet (a sheet on which image formation is performed in an area of 6% of the total sheet area) having the highest frequency of image formation.

  In such a configuration, first, a case where a recording material is continuously fed from the paper feed tray 1 and an image is formed on the recording material will be described.

  When the print start key is pressed after the continuous image forming mode is set, recording materials are fed one after another from the paper feed tray 1, and these recording materials are conveyed on the feeding conveyance path 4. In the middle, the pretreatment liquid application unit 6 is sandwiched between the application roller 21 and the counter roller 23, and the pretreatment liquid 18 is applied to the surface of the recording material (the surface on the image forming side). When the pretreatment liquid 18 is applied, the application roller 21 is used, so that the pretreatment liquid 18 having a high viscosity can be used and the pretreatment liquid 18 can be applied thinly.

  The recording material coated with the pretreatment liquid 18 in the pretreatment liquid application unit 6 is once sent into the reversing tray 5, and the recording material sent into the reversing tray 5 is switched back by the recording material reversing means 14. Then, it is sent out to the paper feed transport path 4 and sent from the paper feed transport path 4 to the ink jet recording unit 2 to form an image on the recording material. Since the pretreatment liquid 18 is applied to the surface of the recording material sent to the ink jet recording unit 2, the quality of the image formed on the recording material is improved.

  Here, the recording material is fed into the reversing tray 5 after being applied with the pretreatment liquid 18 in the pretreatment liquid coating unit 6, switched back in the reversing tray 5, and fed into the inkjet recording unit 2. Even in the case where the conveyance speed of the recording material in the inkjet recording unit 2 varies depending on the presence or absence of the image forming area on the recording material, the conveyance of the recording material to the reversing tray 5 is performed in the inkjet recording unit 2. It can be performed at a constant speed independently of the conveyance of the recording material. Accordingly, the recording material passing through the pretreatment liquid application unit 6 can be passed at a constant speed, and the pretreatment liquid 18 can be applied to the recording material at a constant speed without any unevenness. It is possible to prevent the recording material from being wavy and image quality unevenness due to the uneven application of the liquid 18.

  The recording material after the pretreatment liquid 18 is applied is fed into the reversing tray 5 and then switched back and sent to the ink jet recording unit 2 to dry the pretreatment liquid 18 applied to the recording material. Can be secured.

  In addition, since the preceding recording material that is switched back from the reversing tray 5 and sent out is at least partially overlapped with the succeeding recording material that is fed into the reversing tray 5, By controlling the feeding speed of the recording material, the feeding speed of the recording material from the inside of the reversing tray 5, the feeding timing of the recording material from the inside of the reversing tray 5, etc., the material to be switched back and fed to the inkjet recording unit 2 The interval between recording materials can be reduced. As a result, when the interval between the recording materials fed from the paper feed tray 1 is narrowed, there are fluctuations in the paper feed timing from the paper feed tray 1, fluctuations in the conveyance speed during conveyance to the reverse tray 5, and the like. Even if it occurs, the feeding of the recording material to the inkjet recording unit 2 can be accurately maintained at a small interval, and the productivity of the image forming operation in the image forming apparatus can be increased.

  Further, since the conveyance speed V1 of the recording material conveyed from the paper feed tray 1 to the reversing tray 5 is set faster than the average conveyance speed V2 of the recording material conveyed through the inkjet recording unit 2, the reversing tray 5 It is possible to increase the waiting time of the recording material within the recording medium. Furthermore, when the conveyance speed in the ink jet recording unit 2 is changed, for example, when image formation of the preceding recording material is completed in a short time, it is possible to prevent the interval with the subsequent recording material from being greatly widened. Even in the case where slippage occurs during paper feeding from the paper feeding tray 1 and paper feeding timing is delayed, the interval between the preceding recording material and the succeeding recording material in the inkjet recording unit 2 is greatly increased. Can be prevented.

  Next, a case where a recording material is stacked and held on the reversing tray 5 and the recording material is fed to the inkjet recording unit 2 will be described. As the recording material fed from the reversing tray 5, the surface treatment (application of the pretreatment liquid) has already been performed, and the recording material which does not require the application of the pretreatment liquid 18 in the pretreatment liquid application unit 6. Or a thick recording material that is difficult to bend, or a long recording material that cannot be stored in the paper feed tray 1.

  When feeding the recording material from the reverse tray 5, the clutch provided on the rotating shaft of the opposing roller 17 is turned on, and the opposing roller 17 is driven to rotate in a direction to return the recording material into the reverse tray 5. Let As a result, the recording material picked up by the pickup roller 15 is separated and fed one by one by the separation feeding unit 14 and sent to the inkjet recording unit 2 to form an image.

  Here, when image formation is performed on a recording material that has already undergone surface treatment (application of a pretreatment liquid), a thick recording material, or a long recording material, those recording materials It is not necessary to provide a dedicated tray for feeding paper, and the number of recording materials that can be used while maintaining a compact configuration can be increased.

1 is a schematic diagram illustrating a structure of an image forming apparatus according to a first embodiment. It is explanatory drawing of operation | movement of the to-be-recorded material inversion means in an open state. It is explanatory drawing of operation | movement of the to-be-recorded material inversion means in a sending-out state.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording material storage part 2 Inkjet recording part 4 Feeding conveyance path 5 Reversing tray, recording material storage part 6 Pretreatment liquid application part 14 Recording material reversing means, separation paper supply means 18 Pretreatment liquid 21 Application roller

Claims (9)

A recording material storage unit for stacking and holding recording materials;
An application unit for applying a liquid to the recording material and performing a pretreatment;
A reversing tray that is exposed to the outside from the apparatus main body and into which the preprocessed recording material is fed;
A recording unit that forms an image on a recording material sent from the reversing tray ,
The recording material is fed into the reversing tray with the pretreated surface coated with the liquid as an upper surface, and the feeding direction is reversed by the reversing tray and fed to the recording unit, and an image is formed by the recording unit. An image forming apparatus.   At least a part of the preceding recording material fed from the reversing tray and the subsequent recording material fed to the reversing tray are superimposed on the reversing tray, and the transport speed of the fed recording material 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is controlled so that the conveying speed is variable after that until the reverse tray reaches a predetermined conveying speed. A recording material reversing means that is switchable between an open state that allows the recording material to be fed into the reversing tray and a sending- out state in which the fed recording material is switched back and sent out;
When the recording material reversing means is opened, at least a part of the preceding recording material fed from the reversing tray and the succeeding recording material fed to the reversing tray are superposed. The image forming apparatus according to claim 2 . The entrance side of the recording material to the reversing tray, according to any one of claims 1 to 3, further comprising a reversing roller which is intermittently rotated in a direction of feeding the recording material Image forming apparatus. The application part, according to any one of claims 1 to 4, characterized in that it has a coating roller for applying the pretreatment liquid by rotating in contact with the image forming surface of the recording material conveyed Image forming apparatus.   The image forming apparatus according to claim 1, wherein the reversing tray has a function as a recording material storage unit that stacks and holds recording materials fed to the recording unit. apparatus.   The image forming apparatus according to claim 1, wherein a portion from the reverse tray to the recording unit is formed in a straight shape. The image forming apparatus according to claim 3, wherein the recording material reversing unit functions as a separation feeding unit that separates and feeds the recording materials stacked and held on the reversing tray one by one. apparatus. The conveyance speed V1 of the recording material conveyed from the recording material storage unit to the reversing tray is set to be faster than the average conveyance speed V2 of the recording material conveyed through the recording unit. the image forming apparatus according to any one of claims 1-8 to.

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