JP2006103920A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of increasing the quality of printing and preventing jamming from occurring. <P>SOLUTION: A sheet material jumping prevention roller 14 is disposed near the downstream side of a resist roller 13 and rotatingly driven so as to carry a sheet material in a sheet material carrying direction while coming into contact with the image forming side surface of the sheet material. The sheet material jumping prevention roller 14 guides the sheet material so that the sheet material can be carried in a specified state while coming into contact with the surface of the sheet material on which an image is transferred. A damage prevention roller 17 is disposed on the downstream side of the sheet jumping prevention roller 14 and on the upstream side of a second transfer roller 18, and installed so as to be rotatably driven according to the movement of the sheet material in the sheet material carrying direction. The damage prevention roller 17 guides the sheet material so that the sheet material can be carried in the specified state while coming into contact with the image forming side of the sheet material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a printer, a copying machine, and a facsimile machine that forms an image on a transfer material such as paper or a plastic sheet material, and more particularly to a sheet material transport mechanism in the vicinity of a registration roller.

  In the conventional image forming apparatus, the toner image formed in the image forming unit is temporarily transferred to a transfer belt as an intermediate transfer member, and the toner image transferred to the transfer belt is further transferred to the side opposite to the support roller of the transfer belt. In some cases, the transfer roller and the transfer belt of the transfer section positioned sandwich the sheet material conveyed by the registration roller, thereby transferring the toner image on the transfer belt to the sheet material.

  In this case, for the purpose of positioning the sheet material and the toner image and preventing the skew of the sheet material, the registration roller is arranged upstream of the transfer portion in the sheet material conveyance direction. Normally, the registration roller is set to a positive rotation speed (faster) than the transfer roller rotation speed in consideration of the transfer roller slip and the like in order to ensure image magnification and image quality on the sheet material. ing.

Further, as an image forming apparatus other than the conventional image forming apparatus described above, an image forming apparatus provided with a pressing member (conveying guide made of a guide plate) that conveys and guides a transfer material to a transfer position portion with the traveling image carrier. A bias having a polarity different from the transfer bias is applied to the transfer material at a position before the transfer material reaches the transfer portion (FIG. 1 of the device (Patent Document 1) and (Patent Document 3)). An image forming apparatus that includes a potential control unit that controls the potential so that the toner is unlikely to fly to the transfer material, and thus the toner scatters and adheres to the transfer material that arrives at the transfer site from the photosensitive member side. (Patent Document 2) is known.
JP-A-1-236141 JP-A-3-267971 JP 2000-233845 A

  However, in the conventional image forming apparatus in which the speed of the registration roller is set to a positive value (faster) than the speed of the transfer roller, the speed (rotation speed) of the registration roller is set to a positive value from the speed (rotation speed) of the transfer roller. When (faster), the sheet material is bent between the registration roller and the transfer roller.

  For this reason, when the trailing edge of the sheet material leaves the registration roller, the sheet material temporarily stops at the position of the transfer roller due to the deflection of the sheet material described above, but the intermediate transfer member on the opposite side of the transfer roller is Since the sheet rotates as usual, there is a problem that the toner image is blurred on the sheet material (an equal interval is lost where it should be an equal interval and the interval becomes nectar).

  Further, in order to suppress the deflection of the sheet material between the transfer roller and the registration roller, a method of narrowing the gap (gap) between the upper and lower (upper and lower members) of the sheet guide member located between the transfer roller and the registration roller as much as possible. However, in this method, when the sheet material enters the sheet guide member from the registration roller, the leading edge of the sheet material hits the end surface or notch of the sheet guide member, and there is a high probability that jamming will occur. It was. For this reason, the problem that jam frequently occurs has occurred.

  Furthermore, in the image forming apparatus described in the above (Patent Documents 1 to 3), the sheet material (transfer material) can be guided using a plate-shaped guide member, but the sheet material (transfer) in a stable state. Therefore, the image disturbance due to the impact of the collision between the guide member and the rear end portion of the conveyed sheet material cannot be completely eliminated.

  That is, in the conventional image forming apparatus including the image forming apparatus described in the above (Patent Documents 1 to 3), a printing defect occurs at the rear end portion of the sheet material, so that the image quality of the printing result (output image) is increased. Had fallen. In addition, due to the occurrence of the jam, the sheet material is wasted due to the occurrence of the jam, and the resource of the sheet material cannot be effectively used. Furthermore, the occurrence of a jam requires a work (maintenance work) for eliminating the jam, which is troublesome.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can improve print quality and prevent jamming.

  In order to solve this problem, an image forming apparatus of the present invention is an image forming apparatus that transfers an image formed by an image forming unit onto a sheet material conveyed from a sheet material storing unit that stores a sheet material by a transfer unit. And a registration roller that conveys the sheet material conveyed from the sheet material storage unit to the transfer unit in synchronization with a transfer timing of the transfer by the transfer unit, and a downstream side of the registration roller in the sheet material conveyance direction. And a first roller that is disposed in the vicinity of the registration roller and guides the sheet material to be conveyed in a prescribed state by contacting a surface to which the image of the conveyed sheet material is transferred. It is what.

  In a preferred embodiment of the present invention, the first roller is rotationally driven in the sheet material conveyance direction.

  In a further preferred aspect of the present invention, the sheet is disposed on the downstream side of the first roller in the sheet material conveyance direction and on the upstream side of the transfer unit, and the surface of the conveyed sheet material is transferred to the surface. There is provided a second roller that abuts and guides the sheet material to be conveyed in a specified state.

  In a further preferred aspect of the present invention, the second roller is rotatably arranged following the movement of the abutted sheet material in the sheet material conveyance direction.

  In a further preferred aspect of the present invention, the image forming unit is disposed corresponding to a plurality of different colors from an image carrier on which an electrostatic latent image is formed, and the corresponding color toner is supplied to the image carrier. A plurality of developing means for forming a toner image by supplying to the electrostatic latent image formed thereon, an intermediate transfer body on which the toner images formed on the image carrier are sequentially color-transferred, and the plurality of developing means And a first transfer unit that transfers the toner image of a predetermined color formed on the image carrier to the intermediate transfer member, and the transfer unit transfers the image formed on the intermediate transfer member to the sheet material. This is a second transfer portion to be transferred.

In order to solve this problem, the image forming apparatus of the present invention sandwiches a sheet material conveyed between the image carrier and a toner image formed on the image carrier to the sheet material. A transfer roller for transferring, a registration roller for transferring the sheet material conveyed from the sheet material storage unit to a predetermined transfer position, and disposed between the transfer roller and the registration roller, and conveyed from the registration roller. An image forming apparatus including a sheet material guide portion that guides the sheet material to be transferred to the predetermined transfer position, in the vicinity of an end portion on the registration roller side and an end portion on the transfer roller side of the sheet material guide portion. It is configured to have a roller that is disposed so as to be rotatable so as to contact the surface to which the toner image of the conveyed sheet material is transferred.

  According to the present invention, it is possible to obtain an effective effect that it is possible to improve printing quality by preventing printing bleeding due to splashing of the rear end portion of the sheet material and to prevent occurrence of jam.

  In addition, according to the present invention, the trailing edge of the sheet material immediately before the image is transferred by the transfer means does not come into contact with other members, so that the sheet material can be prevented from being damaged and printed. It is possible to obtain an effective effect that quality can be improved and jamming can be prevented.

  Furthermore, according to the present invention, a rotatable roller is disposed at the end of the sheet material guide portion on the registration roller side, so that printing blur is prevented by splashing of the rear end portion of the sheet material. In addition, the occurrence of jam can be prevented, and a rotatable roller is arranged at the end of the sheet material guide portion on the transfer roller side. Since it does not come into contact with the end portion on the transfer roller side, an effective effect of preventing the sheet material from being damaged can be obtained.

  Invention of Claim 1 of this invention is an image forming apparatus which transfers the image formed in the image formation part to the sheet material conveyed from the sheet material storage part which stores a sheet material by a transfer means, Synchronously with the transfer timing of the transfer by the transfer means, a registration roller that conveys the sheet material conveyed from the sheet material storage unit to the transfer means, and a downstream side of the registration roller in the sheet material conveyance direction and in the vicinity of the registration roller. And an image forming apparatus having a first roller that contacts a surface on which an image of the conveyed sheet material is transferred and guides the sheet material to be conveyed in a specified state. This has the effect of preventing printing bleeding due to splashing at the rear end portion and improving the print quality and preventing jamming.

  According to a second aspect of the present invention, in the first aspect of the invention, the first roller is an image forming apparatus that is rotationally driven in the sheet material conveying direction, and the splash of the rear end portion of the sheet material. This prevents printing blurring and improves printing quality and prevents jamming.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the sheet is disposed and conveyed downstream of the first roller in the sheet material conveyance direction and upstream of the transfer means. An image forming apparatus including a second roller that abuts on a surface on which an image of the sheet material is transferred and guides the sheet material to be conveyed in a specified state, immediately before the image is transferred by the transfer unit Since the rear end portion of the sheet material does not come into contact with other members, it is possible to prevent the sheet material from being scratched and to improve the printing quality and to prevent the occurrence of jamming. Has an effect.

  According to a fourth aspect of the present invention, in the third aspect of the invention, the second roller is rotatably arranged following the movement of the abutted sheet material in the sheet material conveyance direction. Since the rear end portion of the sheet material immediately before the image is transferred by the transfer means does not come into contact with other members, the sheet material can be prevented from being damaged, and The print quality can be improved and jamming can be prevented.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the image forming unit includes a plurality of image carriers different from the image carrier on which the electrostatic latent image is formed. A plurality of developing units arranged corresponding to colors and supplying toner of a corresponding color to an electrostatic latent image formed on the image carrier to form a toner image; and a toner image formed on the image carrier And an intermediate transfer member to which the color images are sequentially transferred, and a first transfer unit that transfers a toner image of a predetermined color formed on the image carrier to the intermediate transfer member by a plurality of developing units. Is an image forming apparatus which is a second transfer unit that transfers an image formed on an intermediate transfer body to a sheet material, and has the effect of improving print quality and preventing jamming. .

  According to a sixth aspect of the present invention, there is provided a transfer roller for nipping a sheet material conveyed between the image carrier and transferring a toner image formed on the image carrier to the sheet material. A registration roller that conveys the sheet material conveyed from the sheet material storage unit to a predetermined transfer position, and a sheet material that is disposed between the transfer roller and the registration roller and that is conveyed from the registration roller to the predetermined transfer position. An image forming apparatus including a sheet material guide unit that guides the sheet material to a registration roller side end and a transfer roller side end of the sheet material guide unit. An image forming apparatus having a roller that is rotatable so as to be in contact with a surface onto which a toner image is transferred, and upstream of the sheet material guide portion provided between the registration roller and the transfer roller, that is, the end on the registration roller side Since a rotatable roller is arranged, it is possible to prevent printing bleeding due to splashing at the rear end of the sheet material and improve the print quality, and also to prevent the occurrence of jamming. Since a rotatable roller is disposed on the downstream side of the guide portion, that is, on the end portion on the transfer roller side, a plastic sheet material such as OHP contacts the end portion on the transfer roller side of the sheet material guide portion. Therefore, the sheet material can be prevented from being damaged.

  Hereinafter, the best mode for carrying out the present invention will be described more specifically with reference to the drawings. Here, in the accompanying drawings, the same reference numerals are given to the same members, and duplicate descriptions are omitted. In addition, since description here is the best form by which this invention is implemented, this invention is not limited to the said form.

(Embodiment 1)
1 is a schematic diagram showing the configuration of an image forming apparatus according to Embodiment 1 of the present invention, FIG. 2 is a diagram showing a gear drive system of a registration roller used in the image forming apparatus, and FIG. 3 is a transfer used in the image forming apparatus. FIG. 4 is a view of the arrangement of the transfer roller, the sheet material guide member, and the registration roller used in the image forming apparatus as viewed from above.

  The color laser printer shown in FIG. 1 has a photosensitive drum as an image carrier for each of four colors of yellow, magenta, cyan and black, and a cartridge in which the photosensitive drum and the developing means are integrated is an intermediate transfer member. The toner images of the respective colors arranged on the belt and formed on the photosensitive drum are sequentially transferred onto the intermediate transfer belt (first transfer) and then transferred onto the sheet material at the second transfer portion. A so-called tandem color laser printer is shown.

  In FIG. 1, a laser unit 1 irradiates a laser beam for exposure. The four process cartridges (image carrier, developing means) 2 are cartridges including at least a photosensitive drum (image carrier) 2a and a developing roller (developing means) 2b. One process cartridge 2 is yellow, A toner corresponding to any one of magenta, cyan, and black is included.

  Each of the four toner cartridges (developing means) 3 stores toner, and is provided corresponding to the four process cartridges 2. When the remaining amount of toner in the process cartridge 2 decreases, the toner is stored in the process cartridge 2. Supply. The toner cartridge 3 and the developing roller 2b correspond to the developing means described above.

  The intermediate transfer member belt (intermediate transfer member) 4 is stretched around at least two rollers and rotated. Around the intermediate transfer belt 4, process cartridges 2 of four colors of yellow, magenta, cyan and black are arranged so that the photosensitive drum 2 a and the intermediate transfer belt 4 are in contact with each other.

  Further, on the inner side of the intermediate transfer belt 4 facing the photosensitive drum 2a, a first transfer roller (first transfer portion) 4a for transferring the toner image on the photosensitive drum 2a onto the intermediate transfer belt 4. Are arranged for each of the four colors. The first transfer roller 4a corresponds to the first transfer portion described above.

  The laser unit 1, four process cartridges (image carrier, developing means) 2, four toner cartridges (developing means) 3, an intermediate transfer body belt (intermediate transfer body) 4, and a first transfer roller (first transfer roller) The transfer section) 4a constitutes the image forming section described above.

  The sheet material storage unit 5 stacks and stores the sheet material 6. The paper feed roller 7 and the separation roller 8 are for separating and feeding only the uppermost part of the sheet material 6 stacked in the sheet material storage unit 5 one by one.

  The transport roller 9 is for transporting the sheet material 6 fed by the paper feed roller 7 and the separation roller 8 to the above-described image forming unit.

  The color laser printer according to the first embodiment has a multi-purpose tray (MPT) corresponding to special paper such as cardboard or postcard as a paper feeding unit other than the sheet material storage unit 5. The separation friction member 10 is a component that constitutes a part of the MPT. The paper feed roller 11 feeds the sheet material on the MPT stacking plate that accommodates the sheet material (special paper). The separation roller 12 is for separating sheets into one sheet, and feeding sheet materials (special paper) one by one.

  The registration roller 13 temporarily transfers the sheet material 6 conveyed by the conveyance roller 9 to the second transfer unit, which will be described later, in synchronization with the image forming status in the image forming unit. This is for stopping the conveyance.

  The registration roller 13 and the registration pinch roller 24 arranged so as to be able to rotate in the direction opposite to the conveying direction of the sheet material 6 constitute a pair of rollers.

  The sheet material splash prevention roller (first roller) 14 is disposed in the vicinity of the downstream side of the registration roller 13 and is in contact with the image forming portion side surface (surface on which the sheet material image is formed) of the sheet material 6. The sheet material 6 is rotationally driven so as to be conveyed (contacted) and conveyed in the forward conveyance direction (sheet material conveyance direction). The sheet material splash prevention roller 14 is in contact with the surface on which the image of the conveyed sheet material 6 is transferred and guides the sheet material 6 to be conveyed in a specified state.

Here, the prescribed state of the sheet material 6 conveyed by the guide by the sheet material splash prevention roller 14 is that a sheet material guide member whose leading end portion of the sheet material 6 will be described later when the sheet material 6 passes the registration roller 13. 16 includes a state in which the registration roller 13 side end portion (end surface or notch portion) does not contact (collision) and a state in which the rear end portion of the sheet material 6 does not jump up.

  The sheet material guide members (sheet material guide portions) 15 and 16 are plate-like members that form a conveyance path for the sheet material 6 from the registration roller 13 to a second transfer portion described later. That is, the sheet material 6 conveyed from the registration roller 13 is guided to a predetermined transfer position of the second transfer unit. In the sheet material guide members 15 and 16, at least a portion close to the second transfer portion is formed of a resin or sheet metal member.

  The scratch prevention roller (second roller) 17 is disposed downstream of the sheet jump prevention roller 14 and upstream of the second transfer unit, and is conveyed to the sheet of the sheet material 6 being conveyed. Attached so as to be able to rotate following the movement in the material conveying direction. The scratch prevention roller 17 is in contact (contact) with the image forming unit side (the surface on which the image of the sheet material is transferred) of the sheet material 6 and guides the sheet material 6 to be conveyed in a specified state. is there.

  Here, when the sheet material 6 passes through the sheet material guide members 15 and 16 when the sheet material 6 is conveyed by the guide by the scratch preventing roller 17, the rear end portion of the sheet material 6 is the sheet material. This includes a state in which the guide member 16 does not come into contact (collision) with an end portion (a portion formed of a resin or sheet metal member) on the second transfer portion side to be described later.

  The second transfer roller (transfer means, second transfer portion) 18 is disposed opposite to the intermediate transfer body belt 4 and transfers the color toner image formed on the intermediate transfer body belt 4 onto the sheet material 6. It is. The second transfer roller 18 corresponds to a second transfer portion that performs transfer while sandwiching the sheet material 6 with the intermediate transfer belt 4.

  The fixing device 19 is for heating and fixing the toner image (toner image) on the sheet material 6 to which the toner image is transferred. For example, the fixing device 19 is a so-called IH fixing device using electromagnetic induction. A roller 21 is provided.

  The fixing device (IH fixing device) 19 is configured to fix the toner image by holding the sheet material 6 between the fixing belt 20 and the pressure roller 21 in order to fix the toner image on the sheet material 6. Yes. The heat source is a method of heating the fixing belt 20 using electromagnetic induction.

  The paper discharge roller 22 is for discharging the sheet material 6 on which the toner image is fixed by the fixing device 19 to the outside of the color laser printer main body. The paper discharge roller 22 is provided with a reversing function for conveying the sheet material 6 with the toner image fixed on one side to the inside of the apparatus again by the switchback method at the time of duplex printing.

  The double-sided printing conveyance roller 23 is provided in the double-sided printing conveyance path for conveying the sheet material 6 into the apparatus (image forming unit) again during double-sided printing. In this double-sided printing conveyance path, the sheet material 6 conveyed by the double-sided printing conveyance roller 23 is reversed so that the back side faces the image forming unit side, and is again returned to the normal conveyance path in the upstream area near the registration roller 13. A conveyance path is formed so as to join.

  Next, the gear drive system of the registration roller 13 will be described with reference to FIG. FIG. 2 shows the rotational movement of the sheet material jump prevention roller 14 on the sheet material guide member 16 so that the rotation drive is transmitted from the registration roller drive gear 25 in consideration of the rotational direction. The arranged gear train configuration is shown.

The registration roller drive gear 25 and the rotation gear 26 are arranged coaxially with the registration roller 13 and the sheet material jump prevention roller 14, respectively.
The driving force is transmitted from 5 to the rotating gear 26 (see FIGS. 2 and 3).

  In this way, the rotation gear 26 meshes with the registration roller driving gear 25 to transmit the driving force, so that the rotation of the sheet material jump prevention roller 14 arranged coaxially with the rotation gear 26 is the rotation of the registration roller 13. Can be linked faithfully.

  Next, operations for feeding the sheet material 6, forming an image on the sheet material 6, and discharging the sheet material 6 to the outside of the apparatus in the color laser printer described above will be described with reference to FIG.

  Sheet materials 6 serving as transfer materials stacked and accommodated in the sheet material accommodating portion 5 are fed one by one by a paper feed roller 7 and a separation roller 8.

  The fed sheet material 6 is transported by the transport roller 9, passes through the transport roller 9, and is sent to the registration roller 13. This is because the position of the toner image on the intermediate transfer belt 4 and the position of the sheet material 6 are determined in order to accurately transfer the toner image formed by the image forming unit to a predetermined position on the sheet material 6. This is because the two transfer portions (second transfer roller 18) match.

  When the leading edge of the sheet material 6 is temporarily held by the registration roller 13, the timing according to the image forming state in the image forming unit is measured. At the same time, in the image forming unit, the surface of the photosensitive drum 2a is charged to a predetermined potential by a charging unit (not shown), and then exposed to a laser beam emitted from the laser unit 1 to form a latent image. The written latent image is converted into a toner visible image by the developing roller 2b.

  Note that when the remaining amount of toner in the image forming unit decreases, the toner is supplied from the toner cartridge 3 to the developing unit of the process cartridge 2. As a result, the toner image visualized on the sheet material 6 always maintains a constant toner density.

  In the above-described toner visualization, images are sequentially formed in the same manner in the process cartridges 2 of four colors of yellow, magenta, cyan, and black.

  The toner images developed on the photosensitive drums 2a of the respective colors are intermediately transferred by a first transfer roller 4a disposed inside the intermediate transfer body unit so as to face each photosensitive drum 2a with the intermediate transfer belt 4 interposed therebetween. The images are sequentially transferred onto the body belt 4. As a result, a color toner image is formed on the intermediate transfer belt 4.

  The color toner image thus transferred onto the intermediate transfer belt 4 is conveyed to the second transfer portion (second transfer roller 18) to be transferred to the sheet material 6 by the rotation of the intermediate transfer belt 4. Is done.

  Here, when the sheet material 6 timed in the registration roller 13 reaches a predetermined position of the second transfer roller 18 via the sheet material guide members 15 and 16, the second transfer roller 18 is in the middle. A color toner image is transferred from the intermediate transfer body belt 4 to the sheet material 6 by conveying the sheet material 6 while sandwiching the sheet material 6 with the transfer body belt 4.

  The sheet material 6 to which the color toner image is transferred in this manner is sandwiched between the fixing belt 20 and the pressure roller 21 of the fixing device 19 and passes through these members, whereby the color toner image is formed on the sheet material 6. Heat-fixed. Thereafter, the paper is discharged to a paper discharge tray by a paper discharge roller 22 via a conveyance roller in the fixing device 19.

  Next, the operation when the sheet material 6 passes in the vicinity of the registration roller 13 will be described with reference to FIGS.

  The registration roller 13 temporarily registers the conveyed sheet material 6 in order to align the toner image on the intermediate transfer belt 4 formed in the image forming unit with a predetermined position of the sheet material 6. 13 and waits at a predetermined position, and is re-driven (starts rotating in the forward direction in which the sheet material 6 is conveyed) according to a signal from a control means (not shown), and the waiting sheet material 6 is transferred to the second transfer roller 18. Send out (see FIG. 3).

  At this time, when the rear end portion of the sheet material 6 leaves the registration pinch roller 24 that faces and forms a pair with the registration roller 13 (see FIG. 3), the speed difference between the registration roller 13 and the second transfer roller 18. Thus, the rear end of the sheet material 6 tries to jump up. The speed difference is such that the speed value of the speed at which the registration roller 13 tries to send out is larger than the speed value of the transport speed of the second transfer roller 18 in the second transfer section.

  However, in the first embodiment, the sheet jump prevention roller 14 that rotates in conjunction with the rotation of the registration roller 13 is provided immediately after the registration pinch roller 24 (a pair of rollers with the registration roller 13). (See FIG. 3), the rear end of the sheet material 6 is prevented from jumping up.

  For this reason, the sheet material 6 is reliably secured by the second transfer roller 18 without causing a delay in feeding the sheet material 6 due to the cooperation of the second transfer roller (second transfer portion) 18 and the intermediate transfer body belt 4. Therefore, printing defects such as printing bleeding at the rear end portion of the sheet material 6 do not occur.

  By the way, in a color laser printer, various types of sheet materials are often used. For example, thick paper such as postcards, thin paper, label sheet materials, recycled paper that has been increasing in recent years in relation to the environment, and OHP sheet materials that are often used for presentations.

  In particular, since the OHP sheet material is based on plastic, the surface is soft and the transparency is high. Further, since the OHP sheet material is projected and used for its intended use, the value of the OHP sheet material is lowered when the surface of the sheet material is damaged.

  In the first embodiment, as shown in FIGS. 3 and 4, the sheet material guide member 16 is formed of an end (resin or sheet metal member) on the second transfer roller 18 side (intermediate transfer body belt 4 side). The scratch-preventing roller 17 that is freely rotatable is disposed on the upper side. For this reason, since the sheet material 6 (the rear end portion of the sheet material 6) does not hit the rear end portion of the sheet material guide member 16 in the vicinity of the second transfer roller 18, the surface of the OHP sheet material as the sheet material is not affected. The occurrence of scratches can be prevented.

  By the way, in the above-described conventional image forming apparatus, the scratch preventing roller 17 is disposed above the end of the sheet material guiding member 16 on the second transfer roller 18 side (portion formed by a member such as resin or sheet metal). Therefore, when the OHP sheet material as the sheet material passes through the sheet material guide member 16, the rear end portion of the OHP sheet material rubs the edge of the end portion of the sheet material guide member 16. Scratches are likely to occur.

  In the first embodiment, in addition to disposing the scratch preventing roller 17 above the end of the sheet material guiding member 16 on the second transfer roller 18 side, the sheet material is conveyed or guided. By arranging the sheet material in a necessary place in the sheet material passing portion, it is possible to further prevent the sheet material from being damaged.

  As described above, according to the first embodiment, the rotatable sheet jump prevention roller 14 is disposed on the upstream side of the sheet material guide member 16, that is, on the registration roller 13 side and on the upper side of the sheet material guide member 16. Since it did in this way, the printing bleeding by the splash of the rear-end part of the sheet | seat material 6 can be prevented, and a printing quality can be improved, As a result, the image quality of a printing result (output image) can be improved. Further, since jamming can be prevented, the resources of the sheet material 6 can be used effectively, and the work for eliminating jamming can be greatly reduced.

  Further, according to the first embodiment, the rotatable scratch preventing roller 17 is disposed on the downstream side of the sheet material guiding member 16, that is, on the second transfer roller 18 side and on the upper side of the sheet material guiding member 16. Therefore, the sheet material 6 made of plastic such as OHP (rear end portion) does not come into contact with (rub against) the end portion of the sheet material guide member 16, thereby preventing the sheet material 6 from being damaged. it can.

  According to the present invention, a rotatable roller is provided on a sheet material guide member between a registration roller and a transfer roller. By arranging the roller, printing sag at the rear end of the sheet material or OHP Such an effect can prevent the surface of the soft sheet material from being scratched, and can be applied to uses such as PPC, facsimile, ink jet printer, and rotary press.

1 is a schematic diagram illustrating a configuration of an image forming apparatus according to Embodiment 1 of the present invention. The figure which shows the gear drive system of the registration roller used for the image forming apparatus The figure which shows the mode of arrangement | positioning of the transfer roller used for the image forming apparatus, a sheet material guide member, and a registration roller View of the transfer roller, sheet material guide member, and registration roller used in the image forming apparatus as viewed from above

Explanation of symbols

1 Laser unit 2 Process cartridge (image forming part, image carrier, developing means)
3 Toner cartridge (image forming unit, developing means)
4 Intermediate transfer belt (image forming unit, intermediate transfer member)
4a First transfer roller (first transfer section)
5 Sheet material storage unit 13 Registration roller 14 Sheet material splash prevention roller (first roller)
15, 16 Sheet material guide member (sheet material guide part)
17 Scratch prevention roller (second roller)
18 Second transfer roller (transfer means, second transfer section)
24 Registration Pinch Roller 25 Registration Roller Drive Gear 26 Rotation Gear

Claims (6)

An image forming apparatus that transfers an image formed by an image forming unit to a sheet material conveyed from a sheet material storage unit that stores a sheet material by a transfer unit,
In synchronization with the transfer timing of the transfer by the transfer unit, a registration roller that conveys the sheet material conveyed from the sheet material storage unit to the transfer unit;
Located downstream of the registration roller in the sheet material conveyance direction and in the vicinity of the registration roller, the sheet material is conveyed in a prescribed state by contacting the surface to which the image of the conveyed sheet material is transferred. And an image forming apparatus comprising: a first roller for guiding the image forming apparatus. The image forming apparatus according to claim 1, wherein the first roller is rotationally driven in the sheet material conveyance direction. The sheet material is disposed downstream of the first roller in the sheet material conveyance direction and upstream of the transfer unit and is in contact with a surface to which an image of the conveyed sheet material is transferred. The image forming apparatus according to claim 1, further comprising: a second roller that guides the sheet so as to be conveyed in the state. 4. The image forming apparatus according to claim 3, wherein the second roller is rotatably disposed following the movement of the contacted sheet material in the sheet material conveyance direction. The image forming unit includes:
An image carrier on which an electrostatic latent image is formed;
A plurality of developing units arranged corresponding to a plurality of different colors, and supplying toner of the corresponding color to the electrostatic latent image formed on the image carrier to form a toner image;
An intermediate transfer member to which toner images formed on the image carrier are sequentially color-transferred; and
A first transfer unit that transfers a toner image of a predetermined color formed on the image carrier by the plurality of developing units to the intermediate transfer member;
The image forming apparatus according to claim 1, wherein the transfer unit is a second transfer unit that transfers an image formed on the intermediate transfer member to a sheet material. A transfer roller for nipping the sheet material conveyed between the image carrier and transferring the toner image formed on the image carrier to the sheet material;
A registration roller that conveys the sheet material conveyed from the sheet material storage unit to a predetermined transfer position;
An image forming apparatus comprising: a sheet material guiding portion disposed between the transfer roller and the registration roller and guiding a sheet material conveyed from the registration roller to the predetermined transfer position;
A roller that is disposed in the vicinity of the registration roller side end and the transfer roller side end of the sheet material guide, and is rotatable so as to contact the surface on which the toner image of the conveyed sheet material is transferred. An image forming apparatus comprising:

Images