JP4496136B2 - RECORDED MEDIUM CONVEYING DEVICE, TRANSFER DEVICE, AND IMAGE FORMING DEVICE - Google Patents

Description

  The present invention relates to a recording medium conveyance device that conveys a fed recording medium to a pair of rollers, a transfer device including the recording medium conveyance device, and an image forming apparatus.

Various devices have been proposed for conveying a recording medium to a photosensitive drum that carries a recorded image or a transfer roller that transfers the recorded image by pressing the intermediate transfer belt with a predetermined contact pressure. Has been.
For example, image formation is performed by pressing an elastic transfer roller having an elastic sponge layer on the surface of the transfer roller against the image carrier and passing the transfer material between them to transfer the toner image of the image carrier to the transfer material. In the apparatus, by setting the hardness of the transfer roller to 30 degrees (JIS A) or less and the pressure contact force to the image carrier to 300 gr / cm ² or less, transfer can be performed with a low bias without providing a special cleaning means. An image forming apparatus that cleans a roller is known (see Patent Document 1).
A rubber roller-like transfer roller formed by forming a semiconductive rubber layer on a conductive core is pressed against the image carrier to apply a voltage for toner image transfer, and the transfer material is passed through the nip portion. The toner image is transferred onto the transfer material, and the toner adhering to the transfer roller is transferred to the cleaning roller that is in contact with the transfer roller by mirror image force, and the toner transferred to the cleaning roller is removed by the blade. A roller transfer device in an image forming apparatus that does not require a dedicated power source for the cleaning roller for cleaning the transfer roller is also known (see Patent Document 2).
Transfer between the image forming medium, such as an image carrier or intermediate transfer body, on which the visible image is formed while rotating at a predetermined speed, and the image forming medium with a predetermined contact pressure. A transfer roll that transfers a visible image on the image forming medium to a recording medium that advances to the site, and supports the transfer roll so as to be able to swing in a predetermined direction, and when the recording medium enters the transfer site and transfer Movable means for absorbing a load variation applied to the image forming medium by the impact force by swinging the transfer roll in the predetermined direction in accordance with an impact force generated when the part exits from the site, The recording medium is supported so as to be able to swing in a direction substantially parallel to the direction in which the recording medium travels, and the speed fluctuation of the image carrier or the intermediate transfer member is suppressed, so that a good image free from image quality defects can be obtained. An image forming apparatus is also known (see Patent Document 3). Irradiation).
This is a system in which shock fluctuations that occur when the recording medium enters and exits the transfer portion are released by the swing mechanism of the secondary transfer roller.
However, since the secondary transfer roller oscillates, the state of entry of the optimized recording medium into the secondary transfer roller is disturbed, which may cause transfer defects such as transfer dust and pre-transfer.
In the paper guide to the secondary transfer unit, the nip-shaped roller biting amount and winding angle of the transfer roller pair, or the shape of the guide plate reaching the nip part, optimizes the pre-transfer and transfer dust during image transfer. It is also known to suppress (see Patent Documents 4 to 7).

An elastic body is fixed to the front end of the lower guide before transfer of the transfer guide, and the front end of the lower guide before transfer is positioned on the photosensitive drum side with respect to the transfer nip tangent at the transfer nip portion. By positioning the rush position of the transfer material that rushes into the transfer nip part through the elastic body of the transfer drum closer to the photosensitive drum side than the tangent line of the transfer, the occurrence of pre-transfer or discharge white spots at the time of transfer is prevented, An image forming apparatus that can obtain a good image is also known (see Patent Document 4).
A transfer roller that electrostatically transfers the toner image onto the recording paper is transferred to the intermediate transfer belt that carries the toner image. The end portion of the second guide member to be guided is positioned closer to the intermediate transfer belt than the straight line connecting the restriction portion of the first guide member and the transfer nip entrance. Further, the rear end side portion is curved convexly, and as a result, the adhesion between the area where pre-transfer can occur is ensured, and the image carrier and the transfer material adhere in the area where pre-transfer can occur. There is also an image forming apparatus capable of preventing pre-transfer by forming the property and forming an image free from transfer dust (see Patent Document 5).
When it is assumed that there is no secondary transfer roller, the secondary transfer roller is subjected to intermediate transfer so that the non-winding portion of the intermediate transfer belt with respect to the secondary transfer counter roller is partially brought into contact with the secondary transfer counter roller on the nip entrance side. The belt is pressed against the belt, the amount of biting of the secondary transfer counter roller to the secondary transfer roller is set to 0.2 mm or more and 3.0 mm or less, and the movement direction of the intermediate transfer belt is extended immediately before contacting the secondary transfer roller. The pre-transfer due to poor adhesion between the intermediate transfer belt and the transfer paper on the upstream side of the secondary transfer nip in the moving direction of the intermediate transfer belt is set by setting the angle between the line and the nip entrance tangent to 5 ° or more. There is also known an image forming apparatus that can effectively suppress a level that cannot be visually confirmed (see Patent Document 6).
The secondary transfer bias roller in the secondary transfer unit is disposed at a position upstream of the secondary transfer counter roller in the movement direction of the intermediate transfer belt, and is conveyed toward the transfer nip portion of the secondary transfer unit. The transfer material is brought into close contact with the intermediate transfer belt in the pre-transfer area in advance, and as a result, the occurrence of pre-transfer due to the gap between the transfer material and the intermediate transfer belt in the pre-transfer area reduces the complexity of the apparatus. It is possible to prevent pre-transfer at the transfer material entrance portion of the transfer nip portion when the toner image is transferred to the transfer material that has entered the transfer nip portion. An image forming apparatus including a transfer device having a different configuration is also known (see Patent Document 7).

FIG. 7 is an explanatory diagram of a main part of a conventional recording medium conveyance device 100, a transfer device 110 including the recording medium conveyance device 100, and an image forming apparatus 150.
An image forming apparatus 150 as a color printer shown in FIG. 7 includes a yellow image forming unit 151 (Y), a magenta image forming unit 151 (M), a cyan image forming unit 151 (C), and a black image forming unit of the image forming unit 151. 151 (Bk), and the photoconductor 151a ₁ of the image carrier 151a is arranged in a tandem type.
Each primary transfer roller 111 is disposed opposite to each yellow image forming unit 151 (Y), magenta image forming unit 151 (M), cyan image forming unit 151 (C), and black image forming unit 151 (Bk). . The toner recording image transferred by the primary transfer roller 111 to the intermediate transfer belt 151a ₂ stretched between the driving roller 151a ₂₁ and the driven roller 151a ₂₂ is opposed to the secondary transfer roller 112 and the secondary transfer roller 112. At the position of the arranged secondary counter transfer roller 112a, the recording medium (P) is a thick recording sheet fed from the recording medium feeding unit 152 and conveyed from the registration roller of the recording medium conveying apparatus 100. Secondary transfer is performed.

When the leading edge or the trailing edge of the thick recording paper enters the pair of transfer rollers of the secondary transfer roller 112 and the secondary opposing transfer roller 112a, or when it exits the registration roller of the recording / conveying apparatus 100, Load fluctuations that occur at the positions where the secondary transfer between the secondary transfer roller 112 and the secondary counter transfer roller 112a are propagated to the intermediate transfer belt 151a ₂ and to the drive roller 151a ₂₁ .
The shaft 151a ₂₁₁ of the drive roller 151a ₂₁ is connected to a DC motor or a pulse motor of the drive motor 151a ₂₁₂ after passing through a rotary joint mechanism and a speed reduction mechanism.
The intermediate transfer belt 151a ₂ is wound around the driving roller 151a ₂₁ and a slight movement amount is controlled by the friction driving force.
If the load fluctuation generated at the position where the secondary transfer is performed by the secondary transfer roller pair cannot be controlled and buffered by the drive roller 151a ₂₁ as described above, a slight movement position error may cause the photosensitive member 151a located upstream thereof. Propagation to the primary transfer portion of the primary transfer roller 111 facing ₁ causes a transfer position error, which disturbs the formed image and lowers the quality.
There are several fluctuation factors in the drive roller 151a ₂₁ portion and the transmission system for controlling the movement of the intermediate transfer belt 151a ₂ . This is a slight slip or elongation of the intermediate transfer belt 151a ₂ due to load fluctuation. This is because of a bend at the time of rotation transmission in the gear portion which is a joint mechanism or a speed reduction mechanism, or a reason that the holding force of the motor loses load fluctuation.
Japanese Patent No. 2652180 JP-A-8-63009 Japanese Patent No. 3505969 JP 2001-117375 A JP 2001-356538 A JP 2002-14550 A JP 2002-72709 A

In the conventional recording medium conveying apparatus, transfer apparatus, and image forming apparatus, when the leading edge or the trailing edge of the recording sheet of the recording medium enters or exits the nip portion of the transfer roller pair, the roller pair A problem has arisen that the image quality formed due to the rapid load fluctuations generated in the above is propagated to the related drive system, causing position errors, pre-transfer, transfer dust, and the like.
Therefore, an object of the present invention is to solve such problems. That is, when the leading edge or the trailing edge of the recording sheet of the recording medium enters or exits the nip portion of the transfer roller pair, a sudden load fluctuation generated in the roller pair propagates to the associated drive system. A recording medium transport apparatus that suppresses the occurrence of position errors, pre-transfer, transfer dust, and the like so as to form a high-quality recorded image, and a transfer apparatus including the recording medium transport apparatus, An object of the present invention is to provide an image forming apparatus.

In order to achieve the above object, the invention described in claim 1 is a recording medium conveyance device having a conveyance roller pair for conveying a recording medium to a transfer roller pair.
A transport roller pair that retracts the transport roller pair in a direction opposite to the transport direction of the recording medium when the leading end of the recording medium enters the pair of transfer rollers or the trailing end of the recording medium exits the pair of transport rollers. characterized in that it has a retracting means.
According to a second aspect of the present invention, in the recording medium conveyance device according to the first aspect, the pair of conveyance rollers is held by a conveyance roller unit .
According to a third aspect of the present invention, in the recording medium conveyance device according to the second aspect, the conveyance roller pair retracting unit is a rotatable holding member that rotatably holds the conveyance roller unit about a rotation center. It is characterized by having.
According to a fourth aspect of the present invention, in the recording medium conveying apparatus according to the third aspect, the rotatable holding member includes a shaft member and a hole member engaged with the shaft member. And
According to a fifth aspect of the present invention, in the recording medium conveyance device according to the third or fourth aspect , the conveyance medium pair includes a fixed drive gear and a rotation driven gear that transmit a drive from a drive source to the conveyance roller pair, and the rotation The rotation center of the possible holding member is arranged on a straight extension line connecting the rotation center of the fixed drive gear and the rotation center of the rotation driven gear .
According to a sixth aspect of the present invention, in the recording medium conveyance device according to the fifth aspect , the fixed drive gear and the rotation driven gear are arranged so that the extension line is substantially perpendicular to the recording medium conveyance direction. characterized in that it.
According to a seventh aspect of the present invention, in the recording medium conveyance device according to any one of the first to fifth aspects, a timing belt that transmits a rotational drive to the conveyance roller pair and a drive that stretches the timing belt. A pulley and a driven pulley, and a tensioner that absorbs fluctuations in the circumference of the timing belt are provided .
According to an eighth aspect of the present invention, in the recording medium conveying apparatus according to any one of the second to seventh aspects, the conveying roller pair retracting unit holds the conveying roller unit so as to be movable in parallel. A member is provided.
According to a ninth aspect of the present invention, in the recording medium conveyance device according to the eighth aspect, the parallel movable holding member is engaged with the pin member and the pin member, and is a long hole member that is long in the recording medium conveyance direction. It is characterized by comprising.
The invention of claim 10 is the recording medium transport device according to any one of 請 Motomeko 2 to 9, the upper Symbol conveying roller unit, the stopper from moving in the conveying direction of the recording medium from the mounting position It is suppressed by .

The invention of claim 11, the recording medium transport device smell as claimed in any one of claims 2 to 10 Te, the conveying roller unit, the biasing means providing a biasing force to the conveying direction of the recording medium It is characterized by comprising.
According to a twelfth aspect of the present invention, in the recording medium conveying apparatus according to any one of the second to eleventh aspects, the conveying roller pair retreating unit is configured to vibrate the conveying roller unit when the conveying roller unit is retracted. It is characterized by comprising a load applying member to be suppressed .
A thirteenth aspect of the present invention is a transfer apparatus for transferring an image onto a recording medium to be conveyed , comprising the recording medium conveying apparatus according to any one of the first to twelfth aspects .
The invention according to claim 14 is the transfer apparatus according to claim 13, wherein the pair of transfer rollers is a pair of secondary transfer rollers opposed to each other with an intermediate transfer belt on which a toner image is transferred from a photoreceptor. And
According to a fifteenth aspect of the present invention, in an image forming apparatus including an image forming unit that forms an image on a conveyed recording medium, the recording medium conveying device according to any one of the first to twelfth aspects is provided. It is characterized by that.
According to a sixteenth aspect of the present invention, in the image forming apparatus according to the fifteenth aspect, the image forming unit forms a toner image by an electrophotographic image forming process .

Since the present invention is configured as described below, according to the first aspect of the present invention, the position of the roller pair when the leading or trailing edge of the recording medium to be conveyed enters or exits. It is possible to provide a recording medium transporting apparatus that suppresses generation and propagation of an abrupt load fluctuation acting force that occurs in an image to prevent occurrence of a position error and the like so as to form a high-quality recorded image. I can do it now .
According to the third aspect of the present invention, when the leading or trailing end of the recording medium to be transported enters or exits due to the rotation by the simple structure of the pivotable holding member of the transport roller pair retracting means. A recording medium transporting device that suppresses generation and propagation of an abrupt load fluctuation acting force generated at the position of a pair of rollers to prevent occurrence of a position error and the like so as to form a high-quality recorded image. Can now be offered.
According to the fourth aspect of the present invention, the rotating unit has a minimum wasteful configuration, and the distance between the gear pitches by the rotatable holding member of the conveying roller pair retracting means is minimized and the rotating unit is rotated. When the leading or trailing edge of the recording medium to be conveyed enters or exits, the rotation that optimizes the starting direction of the recording medium generates a sudden load fluctuation acting force that occurs at the position of the roller pair. It has become possible to provide a recording medium conveying apparatus that suppresses propagation and prevents occurrence of a position error or the like to form a high-quality recorded image.
According to the fifth aspect of the present invention, the rotating unit has a minimum wasteful configuration, and the distance between the gear pitches by the rotatable holding member of the conveying roller pair retracting means is minimized and the rotating unit is rotated. The start direction of the recording medium is further optimized and smoothly rotated, so that a sudden load fluctuation occurs at the position of the roller pair when the leading edge or trailing edge of the recording medium to be conveyed enters or exits. It has become possible to provide a recording medium conveying apparatus that suppresses the generation and propagation of force to prevent the occurrence of position errors and the like so as to form a high-quality recorded image.

According to the sixth aspect of the present invention, the rotating unit has a minimum wasteful configuration, and smooth drive transmission is achieved by absorbing the peripheral length variation of the timing belt by the rotatable holding member of the conveying roller pair retracting means. Position error by suppressing the generation and propagation of a sudden load fluctuation acting at the position of the roller pair when the leading or trailing edge of the recording medium to be conveyed enters or exits Thus, it is possible to provide a recording medium conveying apparatus that prevents the occurrence of the above and the like and forms a high-quality recorded image.
According to the seventh aspect of the present invention, the position of the roller pair when the leading end or the trailing end of the recording medium to be transported enters or exits due to the parallel movement of the parallel movable holding member of the transport roller pair retracting means. It is possible to provide a recording medium transporting apparatus that suppresses generation and propagation of an abrupt load fluctuation acting force that occurs in an image to prevent occurrence of a position error and the like so as to form a high-quality recorded image. I can do it now.
According to the eighth aspect of the present invention, when the leading end or the trailing end of the recording medium to be transported enters or exits due to the parallel movement by the simple structure of the parallel movable holding member of the transport roller pair retracting means. A recording medium transporting device that suppresses generation and propagation of an abrupt load fluctuation acting force generated at the position of a pair of rollers to prevent occurrence of a position error and the like so as to form a high-quality recorded image. Can now be offered.
According to the invention of claim 9, the conveyance roller unit that integrally holds the conveyance roller pair is positioned at an accurate position at the time of entry of the recording medium to be conveyed, and the leading end of the recording medium to be conveyed, Or, when the rear end enters or exits, formation of high-quality recorded images by preventing the occurrence of position errors by suppressing the generation and propagation of a sudden load fluctuation acting at the position of the roller pair It is now possible to provide a recording medium conveying apparatus that performs the above.

According to the tenth aspect of the present invention, the transport roller unit that integrally holds the transport roller pair is positioned accurately at the time of entry of the recording medium to be transported, and the transport of the recording medium to be transported is performed. A high-quality recorded image that prevents the occurrence of position errors by suppressing the generation and propagation of a sudden load fluctuation acting at the position of the roller pair when the front end or rear end enters or exits. Thus, it is possible to provide a recording medium transporting apparatus that can perform the formation of the recording medium.
According to the eleventh aspect of the present invention, the transport roller unit that integrally holds the transport roller pair rotates or translates and suppresses vibration until it returns to the original position, and is transported. High quality by preventing the occurrence of position errors by suppressing the generation and action of sudden load fluctuation acting at the position of the roller pair when the leading edge or trailing edge of the recording medium enters or exits. It is now possible to provide a recording medium transporting apparatus that can form a recorded image.
According to the twelfth aspect of the present invention, it is possible to prevent the occurrence of position error, pre-transfer, transfer dust and the like by suppressing the generation and the propagation of the abrupt load fluctuation acting force generated at the position where the transfer is performed by the transfer roller pair. Thus, it is possible to provide a transfer apparatus including a recording medium conveying apparatus that can form a high-quality recorded image.
According to the thirteenth aspect of the present invention, it is possible to suppress the generation and the propagation of the abrupt load fluctuation acting force generated at the position where the secondary transfer of the secondary transfer roller and the secondary opposing transfer roller of the transfer roller pair is performed. It has become possible to provide a transfer device including a recording medium transporting device that prevents the occurrence of errors, pre-transfer, transfer dust, and the like so as to form a high-quality recorded image.
According to the fourteenth aspect of the present invention, it is possible to generate and propagate the acting force of a sudden load fluctuation that occurs at the position of the roller pair when the leading or trailing end of the recording medium to be conveyed enters or exits. It is possible to provide an image forming apparatus including a recording medium conveying apparatus that suppresses the occurrence of position error, pre-transfer, transfer dust, and the like and forms a high-quality recorded image. It was.

According to the fifteenth aspect of the present invention, it is possible to suppress the generation and propagation of the acting force of the sudden load fluctuation that occurs at the position of the roller pair when the leading or trailing end of the recording medium to be conveyed enters or exits. Thus, it is possible to provide an image forming apparatus provided with a recording medium transport apparatus that can form a high-quality recorded image at a high speed by preventing occurrence of position error, pre-transfer, transfer dust and the like. became.
According to the sixteenth aspect of the present invention, the acting force of a sudden load fluctuation generated at the position of the transfer roller pair when the leading edge or the trailing edge of the recording medium conveyed to the transfer roller pair enters or exits. Providing an image forming apparatus equipped with a recording medium conveying device that suppresses occurrence and propagation and prevents occurrence of position error, pre-transfer, transfer dust, etc., and high-speed and high-quality recorded images are formed. I was able to do that.

Next, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory diagram of a recording medium transport device 0 showing an embodiment of the present invention.
In FIG. 1, a recording medium conveyance device 0 that conveys a recording medium to be fed to a roller pair 4 is provided on an upstream side that conveys a recording sheet of a recording medium (P) to the roller pair 4 in the arrow X direction. The closest transport roller pair 1, the transport roller unit 2 that holds the transport roller pair 1, and the transport roller pair retracting unit 3 that retracts the transport roller unit 2 in the direction opposite to the transport direction in the arrow X direction of the recording medium. It has.
The transport roller pair 1 is held by the transport roller unit 2 and includes a shaft member 3a ₁ of the rotatable holding member 3a of the transport roller pair retracting means 3 and a hole member 3a ₂ engaged with the shaft member 3a ₁ . Due to the engagement structure, the transport roller unit 2 can be rotated around the rotation center (A) and retracted.
A conveyance roller unit 2 that integrally holds the conveyance roller pair 1 is engaged with a rotation center (A) so as to be rotatable, and is moved in the direction of the arrow (E) via a spring or the like of the urging means 2b. A constant urging force is applied in the clockwise direction, and the stopper 2a ensures positioning at an accurate position when the recording medium to be conveyed enters.
The conveying roller pair retracting means 3 includes a load applying member 3c that applies a load of 100 g · cm or more and 3000 g · cm or less that suppresses vibration during rotation.
The load applying member 3c is arranged at an engaging portion between the shaft member 3a ₁ and the hole member 3a _{2 so} as to apply a predetermined load.
Specifically, a load is applied by interposing a friction member between the outer peripheral surface of the shaft member 3a ₁ and the hole member 3a2, or setting a dedicated hinge (not shown) having a constant torque on the outer peripheral surface.
Accordingly, it is possible to suppress vibrations from the time when the conveyance roller unit 2 that integrally holds the registration roller pair as the conveyance roller pair 1 rotates or translates and returns to the original position.
Accordingly, the conveyance roller unit 2 that rotatably holds the registration roller pair as the conveyance roller pair 1 rotates or translates around the rotation center (A) and returns to the original position. When the leading edge or trailing edge of the recording medium (P) to be conveyed enters the roller pair 4 or exits the conveying roller pair 1, abruptly generated at the position of the roller pair 4. Generation of position fluctuations and the like are prevented by suppressing the generation and propagation of load fluctuation acting force.

FIG. 2 is an explanatory diagram of a main part of the recording medium conveyance device 0, the transfer device 10 including the recording medium conveyance device 0, and the image forming apparatus 50 according to the embodiment of the present invention. .
In FIG. 2, an image forming apparatus 50 includes yellow image forming units 51 (Y), magenta image forming units 51 (M), cyan image forming units 51 (C), and black image forming units 51 ( consists bk), each unit is a color printer of a tandem type electrophotographic recording system which includes a photoconductor 51a ₁ of the image bearing member 51a.
At the position of the secondary transfer roller 11b of the transfer roller pair 11 which is the roller pair 4 of the transfer device 10 and the secondary counter transfer roller 11b ₁ arranged to face the secondary transfer roller 11b, each image forming unit (Y) (M) (C) (Bk) The transfer image of the toner transferred to the intermediate transfer belt 51a ₂ (stretched between the drive roller 51a ₂₁ and the driven roller 51a ₂₂ ) by the primary transfer roller 11a of the transfer roller pair 11 is transferred. Secondary transfer is performed on the recording medium conveyed in the arrow X direction from the recording medium conveying apparatus 0.
Accordingly, when the recording medium (P) is thick paper, the leading edge or the trailing edge of the recording medium (P) enters the secondary transfer roller 11b and the secondary counter transfer roller 11b ₁ or exits the conveying roller pair 1. Occasionally, the generation of a sudden load fluctuation acting at the position where the secondary transfer of the secondary transfer roller 11b and the secondary counter transfer roller 11b ₁ (transfer roller pair 11) is performed and the propagation thereof are suppressed, and the position error, Generation of pre-transfer, transfer dust and the like can be prevented.

A recording medium conveyance device 0 is arranged on the upstream side in the conveyance direction in the arrow X direction of the transfer roller pair 11 that is the roller pair 4 of the transfer device 10.
Further, the recording mediums separated and fed one by one on the upstream side (not shown) of the recording medium conveying apparatus 0 reach the nip portion of the stopped conveying roller pair 1, where a certain amount, preferably After being bent about 2 mm to 3 mm, when the registration roller pair of the conveyance roller pair 1 is driven to rotate, it is conveyed to the downstream side, that is, to the transfer roller pair 11 of the transfer device 10.
The rotation driving timing of the registration roller pair of the conveying roller pair 1 and the writing timing by the optical system of the latent image forming means 51c are synchronized, thereby optimizing the position of the image formed on the recording medium. ing.
The recording medium conveyance device 0 is the hole member 3a ₂ that engages the shaft member 3a ₁ and the shaft member 3a ₁ with the conveyance roller pair 1 that is closest on the upstream side in the conveyance direction of the transfer roller pair 11 and has a large conveyance force. Thus, the conveyance roller unit 2 can be rotated and retracted about the rotation center (A).
As shown in the figure, the conveyance roller unit 2 holding the conveyance roller pair 1 is engaged with the rotation center (A) so as to be rotatable, and the arrow shown in the drawing is provided via a spring or the like of the urging means 2b. A constant urging force is applied in the clockwise direction (E), and the stopper 2a ensures positioning at an accurate position.
Usually, the conveyance speed of the registration roller when the conveyance roller pair 1 is a registration roller pair is slightly higher than or equal to the conveyance speed of the transfer roller pair 11 so that the recording medium (P) is not stressed. The diameter and the number of rotations of each roller are set so as to achieve speed.
For this reason, when the recording medium (P) enters the position of the transfer roller pair 11, it is easy to push in by the speed difference. In particular, in the case of thick paper, this becomes an impact force, and each image forming unit (Y ) (M) (C) (Bk) The transfer roller pair 11 of the primary transfer roller 11a in the primary transfer portion may cause a slight position fluctuation shock jitter.
However, in the transfer device 10 having the recording medium transport device 0 of the present invention, the resist roller pair of the transport roller pair 1 held by the transport roller unit 2 is moved by the arrow (E) shown in FIG. It is rotated counterclockwise in the opposite direction.
Thereby, since the impact force is absorbed, it is possible to suppress the occurrence of the above-described shock fluctuation due to position fluctuation.
The conveyance roller unit 2 holding the conveyance roller pair 1 is when the recording medium fed from the upstream side of the recording medium in the arrow X direction is bent by a certain amount, preferably about 2 mm to 3 mm. In addition, an acting force is received from the recording medium in the conveyance direction of the arrow X direction of the recording medium, that is, it is pushed in the clockwise direction of the arrow (E) in the figure, but the arrow ( E) is configured to be unable to rotate in the clockwise direction, so that the recording roller medium 2 is rotated by the conveyance roller unit 2 that integrally holds the registration roller pair of the conveyance roller pair 1. There will be no image displacement.

FIG. 3 is an explanatory diagram of a main part of the recording medium transport apparatus 0 showing an embodiment of the present invention. The same parts as those in the above embodiment will be described with the same reference numerals.
In the recording medium conveyance device 0 of FIG. 3, the rotation center (A) for rotating the conveyance roller unit 2 by the shaft member 3 a ₁ and the hole member 3 a ₂ is a conveyance roller pair held integrally with the conveyance roller unit 2. 1 in the direction of the arrow (B) shown in FIG. ₁ and the fixed drive gear 1c ₁ to which the rotation drive gear train 1c for rotating the conveying roller pair 1 is fixed is rotated and the rotation is driven. common tangent arrow driven gear 1c ₂ (C) is arranged at a position to be the same direction.
Fixed driving gear 1c ₁ the conveying rollers 1 driven rotation, and a motor (not shown) for rotating the fixed drive gear 1c ₁ is fixed to the body separately from the conveying roller unit 2, the fixed driving gear 1c ₁ is It is rotationally driven clockwise in the direction of arrow (F).
A rotating driven gear 1c ₂ is coaxially and integrally provided on the extension of the lower conveying roller 1b, and meshes with the fixed drive gear 1c ₁ at an optimum pitch distance, so that the lower conveying roller 1b is moved in the direction of the arrow (G). Drive transmitted in a counterclockwise direction.
A common tangent at a arrow (C) direction of the rotation driven gear 1c ₂ for fixing the drive gear 1c ₁ and the driven to the conveying roller pair 1 is driven rotated, starting direction of the conveyance roller pair 1 of rotation (B) approximately A rotation center (A) for rotating the transport roller unit 2 is provided so as to match.
By providing a rotation center (A) for rotating the transport roller unit 2 on an extension line in the direction of the arrow (D) shown in the figure connecting the centers of both the fixed drive gear 1c ₁ and the rotation driven gear 1c ₂ , The rotating conveyance roller unit 2 has a minimum necessary configuration without waste, and the rotation of the conveyance roller unit 2 that integrally holds the registration roller pair as the conveyance roller pair 1 while minimizing fluctuations in the distance between the gear pitches. The starting direction of motion can be optimized.
In FIG. 3, both the fixed drive gear 1c ₁ and the rotary driven gear 1c ₂ are provided obliquely for easy understanding.
Further, preferably, both the gears are arranged so that the extension line in the direction of arrow (D) connecting the centers of both the fixed drive gear 1c ₁ and the rotation driven gear 1c ₂ is vertical, and the pair of transport rollers 1 is configured such that the rotation start direction in the direction (B) is horizontal, the rotating conveyance roller unit 2 has no waste, and the variation in the distance between the gear pitches is minimized. The recording medium (P) can be evacuated while smoothly rotating in accordance with the right horizontal direction of the direction of the action force generated when entering the position of the transfer roller pair 11 of the thick paper transfer device 10 of the recording medium (P).

FIG. 4 is an explanatory diagram of a main part of the recording medium transport apparatus 0 showing another embodiment of the present invention.
The conveyance roller pair 1 in the recording medium conveyance device 0 includes a timing belt 1d that transmits rotation driving, a fixed driving pulley 1d ₁ that fixes the timing belt 1d, and a rotation driven pulley that is rotated and driven. 1 d _2, and a tensioner 1 d ₃ that absorbs fluctuations in the circumference of the timing belt 1 d stretched between the fixed drive pulley 1 d ₁ and the rotation driven pulley 1 d ₂ .
That is, the fixed drive pulley 1d ₁ fixed to the main body side and the rotation driven pulley 1d ₂ provided in the rotatable transport roller unit 2 are in the same direction as the arrow (H) direction shown in the figure via the timing belt 1d. Rotational drive is transmitted to.
In order to keep the tension of the timing belt 1d, the tensioner 1d ₃ is provided on the slack side of the timing belt 1d during rotation is adapted to be pressurized by the illustrated arrows (I) direction of the left direction in the spring. This spring is provided separately from the spring that urges the transport roller unit 2 itself.
Therefore, when the thick paper of the recording medium (P) enters the position of the transfer roller pair 11, the conveyance roller unit 2 that holds the registration roller pair as the conveyance roller pair 1 has a minimal waste configuration. Although the impact is absorbed by rotating in the counterclockwise direction opposite to the conveyance direction (X) of the recording medium (P), the tensioner 1d ₃ can absorb the variation in the circumferential length of the timing belt 1d. It is possible to provide the recording medium conveyance device 0 that performs smooth drive transmission without dynamic fluctuations.

FIG. 5 is an explanatory diagram of a main part of the recording medium transporting apparatus 0 showing another embodiment of the present invention.
In FIG. 5, the conveyance roller pair retraction means 3 in the recording medium conveyance device 0 translates the conveyance roller unit 2 that rotatably holds the registration roller pair as the conveyance roller pair 1 in the direction of the arrow (J) shown in the figure. A parallel-movable holding member 3b is provided to hold it.
Translatable holding member 3b has a pin member 3b _1, a parallel movement of the conveyor roller unit 2 for holding a simple structure comprising the elongate hole member 3b ₂ that engages the pin member 3b ₁ of the conveying roller pair 1 integrally Hold it possible.
In other words, the parallel movable holding member 3b is configured to hold the transport roller unit 2 that integrally holds the registration roller pair of the transport roller pair 1 so that the transport roller unit 2 can be moved in parallel and to retreat by a parallel movement operation.
The upper and lower pin members 3b ₁ provided on the front and rear side plates (not shown) protruding from the transport roller unit 2 are engaged with and held by the upper and lower long hole members 3b ₂ provided on the main body side so as to be movable in the left and right directions. The
Of course, the unit provided with the pin member 3b ₁ and the long hole member 3b ₂ may have the opposite configuration.

The conveyance roller unit 2 that integrally holds the registration roller pair of the conveyance roller pair 1 is provided with an urging force in the conveyance direction (X) of the recording medium (P) by the springs of the upper and lower urging means 2b. The stopper 2a ensures positioning at an accurate position.
Accordingly, when the thick paper of the recording medium (P) enters the position of the transfer roller pair 11, the transporting roller unit 2 that holds the transporting roller pair 1 has the transport direction of the recording medium (P) in the arrow X direction. Since the impact force is absorbed by the parallel movement in the opposite right direction, the occurrence of the above-described shock fluctuation due to position fluctuation can be suppressed.
The conveying roller pair retracting means 3 includes a load applying member 3c that suppresses vibration during parallel movement and is 100 g · cm or more and 3000 g · cm or less.
The load applying member 3c is arranged at an engaging portion between the pin member 3b ₁ and the elongated hole member 3b ₁ of the parallel movable holding member 3b so as to apply a predetermined load.
Specifically, a load is applied by bringing a friction member into contact with the outer peripheral surface of the pin member 3b ₁ or setting a dedicated hinge having a constant torque on the outer peripheral surface.
As a result, the recording medium conveyance device that suppresses vibrations between the rotation or parallel movement of the conveyance roller unit 2 that integrally holds the registration roller pair of the conveyance roller pair 1 and returns to the original position. 0 can be provided.

FIG. 6 is an explanatory diagram of the image forming apparatus 50 including the recording medium transport device 0 according to the embodiment of the present invention.
In FIG. 6, an image forming apparatus 50 that forms a recorded image on a transported recording medium forms an image forming unit 51 that forms a recorded image on the transported recording medium, and the image forming unit 51 forms a recorded image. The recording medium transport device 0 described in each of the above embodiments for transporting the recording medium (P) is provided.
Therefore, the position error can be suppressed by suppressing the generation and propagation of the abrupt load fluctuation acting force generated at the position of the roller pair when the leading or trailing end of the recording medium (P) to be conveyed enters or exits. Further, it is possible to provide the image forming apparatus 50 including the recording medium transporting apparatus 0 that prevents the occurrence of pre-transfer, transfer dust, and the like and forms a high-quality recorded image.
The image forming unit 51 is configured to form a toner recording image on a recording medium at high speed and with high quality by an electrophotographic image forming process.
The image forming apparatus 50 includes an image forming unit 51 that forms a toner recording image on a recording medium, and a recording target that supports the image forming unit 51 below and feeds the recording medium in the direction indicated by an arrow (K). This is a full-color printer that forms a full-color recorded image including a medium feeding unit 52 and a paper discharge tray 53 that discharges and stores a recording medium formed on the side surface of the image forming unit 51.
The recording medium feeding unit 52 includes a paper feed cassette 52a ₁ and a paper feed cassette 52a ₂ of the paper feed cassette 52a at each stage. Furthermore, if necessary, another sheet feeding device (not shown) can be installed.
In the image forming apparatus 50, four image forming units (Y), (M), (C), and (Bk) are detachably mounted on the image forming unit 51, and a recording medium is formed by an image forming process of an electrophotographic method. In addition, a toner recording image can be formed.
In the image forming unit 51, the driving roller 51a ₂₁ and the driven roller 51a ₂₂ of the support rollers the intermediate transfer belt 51a ₂ are endlessly along a predetermined running path of the intermediate transfer member has a belt-shaped which is an image bearing member 51a It is stretched and is rotationally driven by the driving roller 51a ₂₁ in the direction indicated by the arrow (Y).

Along the running surface of the upper of the intermediate transfer belt 51a _2, each of the four image forming portions, each image forming unit (Y) (M) (C ) (Bk) are arranged to be detachably mounted.
In each image forming unit of the four image forming units (Y) (M) (C ) (Bk), around the image bearing member 51a, a charging means 51b for performing charge processing on the surface 51a ₁₁ of the image bearing member 51a latent image forming means 51c for irradiating a laser beam image information on the surface 51a ₁₁ of the image bearing member 51a, and the electrostatic latent image formed is exposed on the surface 51a ₁₁ of the image bearing member 51a is developed A developing unit 51d and a photosensitive member cleaning unit 51e ₁ of a cleaning unit 51e that removes and collects toner remaining on the surface 51a ₁₁ of the image carrier 51a are arranged. As an image forming process, an intermediate transfer belt 51a _{2 is provided.} However, one color image is formed by one rotation.
First, yellow (Y) toner is developed by the developing means 51d in the image forming section where the yellow image forming unit 51 (Y) is arranged, and the intermediate transfer is performed by the primary transfer roller 11a of the transfer roller pair 11 of the transfer device 10. transferred to the transfer belt 51a _2.
Next, magenta (M) color toner is developed by the developing means 51d in the image forming section where the magenta image forming unit 51 (M) is arranged, and the intermediate transfer is performed by the primary transfer roller 11a of the transfer roller pair 11 of the transfer device 10. transferred to the transfer belt 51a _2.
Next, cyan (C) color toner is developed by the developing means 51 d in the image forming section where the cyan image forming unit 51 (C) is arranged, and the intermediate transfer is performed by the primary transfer roller 11 a of the transfer roller pair 11 of the transfer device 10. transferred to the transfer belt 51a _2.
Finally, the black (Bk) toner is developed by the developing unit 51d in the image forming unit in which the black image forming unit 51 (Bk) is arranged, and the toner is intermediated by the primary transfer roller 11a of the transfer roller pair 11 of the transfer device 10. It is transferred to the transfer belt 51a _2.

The image forming portions of the four image forming units (Y), (M), (C), and (Bk) run on the lower side of the intermediate transfer belt 51a ₂ different from the upper running surface of the adjacent intermediate transfer belt 51a _2. On the surface, a pair of transfer rollers 11 of the transfer device 10 for secondary transfer of the four color toner recording images transferred onto the intermediate transfer belt 51a ₂ onto the recording medium, and the intermediate transfer belt after the secondary transfer. The intermediate transfer belt cleaning unit 51e _{2 of} the cleaning means 51e for removing and collecting the toner remaining on the surface 51a ₂ is disposed.
The toner recording image is transferred to the downstream side of the conveyance path that is conveyed in the direction of arrow X through which the recording medium that has undergone the secondary transfer of the superimposed toner recording image is passed by the transfer roller pair 11 of the transfer device 10. A heating roller 51f ₁ and a pressure roller 51f ₂ of a fixing unit 51f for performing heat fixing processing are disposed.
Then, the recording medium that has passed through the heating roller 51f ₁ and the pressure roller 51f ₂ of the fixing unit 51f is discharged and stored in the discharge tray 53 by the discharge roller 51g.
In the recording medium feeding unit 52, an unused recording medium in the paper cassette 52a ₁ and the paper feed cassette 52a ₂ of the sheet feeding cassette 52a is housed, the bottom plate of the rotatably supported bottom plate 52b 52b ₁ and the bottom plate 52b ₂ raise the uppermost recording medium to a position where the pickup roller 52c ₁ of the pickup roller 52c and the pickup roller 52c ₂ can contact each other.
By the rotation of the pickup roller 52c ₁ or the pickup roller 52c ₂ of the pickup roller 52c, the uppermost recording medium is sent out from the paper cassette 52a ₁ or the paper cassette 52a _{2 of the} paper cassette 52a. The recording medium is fed to the recording medium conveyance device 0 described in the claims.

The recording medium conveyed in the direction of the arrow X from the recording medium conveyance device 0 is a secondary counter transfer that is disposed opposite to the secondary transfer roller 11b and the secondary transfer roller 11b of the transfer roller pair 11 of the transfer device 10. High-quality recorded images are formed at the secondary transfer position of the roller 11b ₁ by suppressing the generation and propagation of an abrupt load fluctuation acting force to prevent the occurrence of position error, pre-transfer, transfer dust and the like. So that it is conveyed.
The registration roller pair of the conveyance roller pair 1 held integrally with the conveyance roller unit 2 temporarily stops conveyance of the recording medium, and records the superimposed toner on the intermediate transfer belt 51a ₂ and the leading edge of the recording medium. Are controlled so that the rotational drive is started at a timing so that the positional relationship of the two coincides with a predetermined position.
Therefore, the position error can be suppressed by suppressing the generation and propagation of the abrupt load fluctuation acting force generated at the position of the roller pair when the leading or trailing end of the recording medium (P) to be conveyed enters or exits. Further, it is possible to provide the image forming apparatus 50 including the recording medium conveying apparatus 0 that prevents the occurrence of pre-transfer, transfer dust, and the like, and forms a high-quality recorded image at a high speed. It became so.
The recording medium conveying apparatus of the present invention can be applied to an image forming apparatus such as a copying machine, a facsimile machine, a printer, or a complex machine of these, which forms a recorded image of toner in an image forming process of an electrophotographic method.

It is explanatory drawing of the recording medium conveying apparatus which shows the embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of a main part of a recording medium conveyance device, a transfer device including the recording medium conveyance device, and an image forming apparatus according to an embodiment of the present invention. It is explanatory drawing of the principal part of the recording medium conveying apparatus which shows the embodiment of this invention. It is explanatory drawing of the principal part of the recording medium conveying apparatus which shows the other embodiment of this invention. It is explanatory drawing of the principal part of the recording medium conveying apparatus which shows the other embodiment of this invention. FIG. 3 is an explanatory diagram of an image forming apparatus including a recording medium conveyance device according to an exemplary embodiment of the present invention. FIG. 6 is an explanatory diagram of a main part of a conventional recording medium conveyance device, a transfer device including the recording medium conveyance device, and an image forming apparatus.

Explanation of symbols

0 recording medium transport device 1 transport roller pair,
1a Upper conveying roller,
1b Lower transport roller,
1c rotational drive gear train,
1c ₁ fixed drive gear,
1c ₂ rotation driven gear,
1d timing belt,
1d ₁ fixed drive pulley,
1d ₂ rotation driven pulley,
1d ₃ tensioner 2 transport roller unit,
2a stopper,
2b Energizing means 3 Conveying roller pair retracting means,
3a rotatable holding member,
3a ₁ shaft member,
3a ₂ hole member,
3b A parallel movable holding member,
3b ₁ pin member,
3b ₂ slot member,
3c Load applying member 4 Roller pair 10 Transfer device 11 Transfer roller pair,
11a Primary transfer roller,
11b Secondary transfer roller,
11b ₁ Secondary counter transfer roller 50 Image forming apparatus 51 Image forming unit,
51 (Y) Yellow imaging unit,
51 (M) Magenta imaging unit,
51 (C) Cyan imaging unit,
51 (Bk) Black imaging unit,
51a image carrier,
51a ₁ photoreceptor,
51a ₁₁ surface,
51a ₂ intermediate transfer belt,
51a ₂₁ drive roller,
51a ₂₂ driven roller,
51b charging means,
51c latent image forming means,
51d developing means,
51e cleaning means,
51e ₁ photoreceptor cleaning unit,
51e ₂ intermediate transfer belt cleaning unit,
51f fixing means,
51f ₁ heating roller,
51f ₂ pressure roller,
51g paper discharge roller,
52 Recording medium feeding section,
52a paper cassette,
52a ₁ paper cassette,
52a ₂ paper feed cassette,
52b bottom plate,
52b ₁ bottom plate,
52b ₂ bottom plate,
52c Pickup roller,
52c ₁ pickup roller,
52c ₂ pickup roller 53 paper discharge tray 100 recording medium transport device 110 transfer device,
111 Primary transfer roller,
112 Secondary transfer roller,
112a Secondary opposing transfer roller 150 Image forming apparatus 151 Image forming unit,
151 (Y) Yellow imaging unit,
151 (M) Magenta imaging unit,
151 (C) Cyan imaging unit,
151 (Bk) Black imaging unit,
151a an image carrier,
151a ₁ photoreceptor,
151a ₂ intermediate transfer belt,
151a ₂₁ drive roller,
151a ₂₁₁ axes,
151a ₂₁₂ drive motor,
151a ₂₂ driven roller 152 recording medium feeding unit

Claims (16)

In a recording medium conveyance device having a conveyance roller pair for conveying a recording medium to a transfer roller pair,
When time or that the recording medium rear end the recording medium tip enters the said transfer roller pair exits the pair of conveying rollers, that enables retracting said pair of conveying rollers in a direction opposite to the conveying direction of the recording medium A recording medium conveying apparatus comprising a conveying roller pair retracting means. The recording medium carrying device according to claim 1,
The recording medium conveyance device , wherein the conveyance roller pair is held by a conveyance roller unit . The recording medium transport apparatus according to claim 2,
The recording medium conveying apparatus, wherein the conveying roller pair retracting means includes a rotatable holding member that rotatably holds the conveying roller unit about a rotation center . 4. The recording medium transport apparatus according to claim 3, wherein the rotatable holding member includes a shaft member and a hole member engaged with the shaft member. . 5. The recording medium conveying apparatus according to claim 3, further comprising : a fixed driving gear that transmits driving from a driving source to the conveying roller pair, and a rotation driven gear, and a rotation center of the rotatable holding member. Is arranged on a linear extension line connecting the rotation center of the fixed drive gear and the rotation center of the rotation driven gear . 6. The recording medium conveyance device according to claim 5 , wherein the fixed drive gear and the rotation driven gear are arranged so that the extension line is substantially perpendicular to the recording medium conveyance direction. Recording medium transport device. 6. The recording medium conveying apparatus according to claim 1, wherein a timing belt that transmits rotational driving to the pair of conveying rollers, a driving pulley and a driven pulley that stretch the timing belt, and A recording medium conveying apparatus comprising: a tensioner that absorbs variation in the circumference of the timing belt . 8. The recording medium conveying apparatus according to claim 2, wherein the conveying roller pair retracting unit includes a parallel movable holding member that holds the conveying roller unit in a movable manner. A recording medium conveying apparatus. 9. The recording medium transport apparatus according to claim 8, wherein the parallel movable holding member includes a pin member and a long hole member that engages with the pin member and is long in the recording medium transport direction. Recording medium transporting apparatus. In the recording medium conveying apparatus according to any one of 請 Motomeko 2 to 9, the upper Symbol conveying roller unit, that it is suppressed by the stopper from moving in the conveying direction of the recording medium from the mounting position A recording medium conveying apparatus characterized by the above. Recording medium transport device smell as claimed in any one of claims 2 to 10 Te, the conveying roller unit is characterized by comprising biasing means for applying a biasing force to the conveying direction of the recording medium Recording medium transport device. 12. The recording medium conveying apparatus according to claim 2, wherein the conveying roller pair retracting unit includes a load applying member that suppresses vibration of the conveying roller unit when the conveying roller unit is retracted. A recording medium conveying apparatus characterized by the above . A transfer apparatus for transferring an image to a recording medium to be transported , comprising the recording medium transport apparatus according to claim 1 . 14. The transfer device according to claim 13, wherein the transfer roller pair is a secondary transfer roller pair facing each other with an intermediate transfer belt on which a toner image is transferred from a photoreceptor . 13. An image forming apparatus comprising an image forming unit for forming an image on a recording medium to be transported, comprising the recording medium transporting apparatus according to any one of claims 1 to 12. apparatus. 16. The image forming apparatus according to claim 15, wherein the image forming unit forms a toner image by an electrophotographic image forming process .

Images