JP2002265097A - Image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform accurate resist-matching without causing unevenness in every time paper feeding operation to contribute to the improvement of image quality. SOLUTION: A paper sheet 50 is fed while a solenoid 40 is turned on and nip parts of a pair of resist rollers 38 are separated from each other and a solenoid 46 is turned off and a knocking face 49b blocks a conveyance path of the paper sheet 50 to knock its tip against the knocking face 49b. After that, a pair of resist rollers 38 are pressurized, the knocking face 49b is retracted from a paper sheet conveyance path, and then a pair of resist rollers 38 are driven to convey the paper sheet 50 to an image transfer part at a predetermined timing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an analog copying machine,
The present invention relates to an image forming apparatus such as a digital copying machine, an analog color copying machine, a digital color copying machine, a printer, and a facsimile.

[0002]

2. Description of the Related Art A paper feeding and conveying system of an image forming apparatus which conveys a recording material such as paper and performs recording by an electrophotographic method or the like includes:
Generally, the following configuration is known. That is, sheet feeding means for sending out the stacked sheets one by one, a conveying unit before registration for conveying the sheet sent from the sheet feeding means to a pair of registration rollers, and a sheet fed from the pair of registration rollers. Transfer drum for transferring the image onto the paper, a fixing unit for fixing the image recorded on the paper, and control for controlling all operations in these devices. It is composed of means and the like.

The sheets stacked on the sheet feeding tray of the sheet feeding means are fed one by one in order from a top sheet by a sheet feeding roller, and sent to a pair of registration rollers. At this time, the registration roller pair has been stopped with the nip formed,
Even after the leading edge of the sheet abuts the nip portion of the pair of registration rollers, the sheet feeding roller continues to convey for a short time. Due to this excessive feeding, a loop (hereinafter, referred to as a pre-registration loop) is formed at the leading end of the sheet, and the leading end of the sheet is aligned along the nip line by the pressure of the pre-registration loop. This corrects the skew of the sheet. In this state, the pair of registration rollers rotates in synchronization with the image recording start signal, and sends out the sheet to the image transfer unit. An image can be formed at a predetermined position on the sheet by the predetermined timing operation.

[0004]

As described above, after the leading edge of the sheet abuts against the stopped registration roller pair, the sheet feeding roller is kept rotated for a short period of time, so that the sheet forms a pre-registration loop. The registration roller pair is rotated in synchronization with the image recording signal. However, the leading edge of the sheet always hits the same position of the registration roller pair, and a pre-registration loop of the same pressure is not always formed. Further, the slip amount at the leading end of the sheet when the registration roller pair starts rotating is not always the same every time. Depending on the state of formation of the pre-registration loop, it may happen that the leading end of the sheet is not properly clamped with the rotation. Therefore, it is difficult to perform accurate registration without any variation, and there is a case where an image is misaligned.

Accordingly, an object of the present invention is to provide an image forming apparatus capable of performing accurate registration without variation in each paper feeding operation and contributing to improvement of image quality.

[0006]

To achieve the above object, according to the first aspect of the present invention, a recording material conveyed and supplied from a recording material supply device is transferred to an image transfer unit at a predetermined timing by a pair of registration rollers. In an image forming apparatus for feeding and transferring a visible image formed on an image carrier to the recording material at the image transfer unit, a recording device is provided downstream of the pair of registration rollers in the recording material conveyance direction to detect the recording material. Material detecting means, and nip pressure releasing means for releasing the nip pressure of the pair of registration rollers to separate the nip portion. During the release of the nip pressure, the leading end of the supplied recording material passes through the pair of registration rollers. After a certain period of time from the detection by the recording material detecting means, the conveyance of the recording material is stopped, and then the pair of registration rollers is pressed to apply the recording material to the registration roller pair at the predetermined timing. Sent to transfer unit, it adopts a configuration that.

According to the second aspect of the present invention, the recording material conveyed and supplied from the recording material supply device is sent to the image transfer unit at a predetermined timing by a pair of registration rollers, and the visible image formed on the image carrier is converted. In the image forming apparatus for transferring to the recording material by the image transfer unit, a recording material detecting means provided downstream of the registration roller pair in the recording material conveyance direction for detecting the recording material, and releasing the nip pressure of the registration roller pair A nip pressure releasing means for separating the nip portion, and a butt surface provided further downstream of the recording material detecting means, against which the leading end of the recording material abuts, and wherein the butt surface is moved from the conveyance path of the recording material. A retractable leading edge aligning means, and a fixed time after the supplied leading edge of the recording material passes through the pair of registration rollers and is detected by the recording material detecting means during release of the nip pressure, Stopping the feeding and properly abutting the leading end against the abutting surface, then applying pressure to the pair of registration rollers, retreating the abutting surface from the transport path, and then removing the recording material by the pair of registration rollers. The configuration is such that the image data is sent to the image transfer unit at the predetermined timing.

According to a third aspect of the present invention, in the image forming apparatus of the second aspect, the leading end aligning means includes a rotating shaft extending in a width direction orthogonal to a recording material conveying direction, and an integral part of the rotating shaft. An abutting plate provided with the abutting surface and a driving means for driving the rotating shaft are provided.

According to the fourth aspect of the present invention, the first to third aspects are provided.
Wherein the registration roller pair has a conveyance guide pair having a start end upstream in the recording material conveyance direction and a termination end near the abutting surface. ing.

According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the transport guide pair is provided such that the front end has a wide frontage and the terminal end has a narrow frontage. The configuration is adopted.

According to a sixth aspect of the present invention, in the image forming apparatus of the fifth aspect, the terminal ends of the pair of transport guides come into contact with each other by elastic force, and the recording material is sandwiched from both front and back sides when transported. The recording material is provided with a braking action.

According to the seventh aspect of the invention, there is provided the fourth to sixth aspects.
In the image forming apparatus described in any one of the above, a configuration is adopted in which a plurality of the conveyance guide pairs are provided at intervals in a width direction orthogonal to the conveyance direction of the recording material.

[0013] In the invention according to claim 8, claims 1 to 7 are provided.
In the image forming apparatus according to any one of the above, the registration roller pair is configured by a plurality of rollers provided at intervals in a width direction orthogonal to the conveying direction of the recording material, I am taking it.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. First, a schematic configuration and operation of a digital color copying machine as an image forming apparatus will be described with reference to FIG. The copying machine obtains a color image by superimposing and transferring a plurality of images of different colors from four photosensitive drums as image carriers on paper as a recording material. When a power switch (not shown) is turned on and the copy start key 3 is pressed while the original 2 is set on the contact glass 1, a copy operation starts. In this copying operation, first, the two lamps 4 that emit the reading light L are driven by a drive system (not shown) together with the moving mirror 5 and the two reflectors 6, and start moving rightward in the figure. In addition, the moving mirrors 7 and 8 are driven by a drive system (not shown) to start moving in the moving direction at half the speed of the moving mirror 5.

The reading light L emitted from the two lamps 4 moves rightward in the figure while irradiating the original 2 on the contact glass 1 directly or via two reflectors 6. Then, the light is sequentially reflected on the original 2 and the moving mirrors 5, 7, 8 and transmitted through the lens 9. Further, the light enters the dichroic mirror 10 and is separated into three primary colors. The blue light, green light, and red light obtained by the color separation form a blue separation image, a green separation image, and a red separation image on the CCDs 11B, 11G, and 11R, respectively. CCD11
Each of B, 11G, and 11R outputs a signal of a voltage value according to the light amount of the formed decomposed image.

FIG. 2 is a block diagram showing a flow of an image signal of the copying machine. In the figure, the CCDs 11B, 11
The minute output signals from G and 11R are amplified and
After being amplified for each pixel in the / D conversion circuits 12B, 12G, and 12R, an analog signal is converted into, for example, an 8-bit digital signal. These digital signals are temporarily stored in the synchronous memories 15B, 15G, and 15R in synchronization with the clock signal 14 from the block generation circuit 13, and become image signals. Synchronous memory 15B, 15
These blue, green, and red image signals stored in G and 15R are sent to the image processing unit 16 at timings such that images of the same area can be combined.

The image processing unit 16 subjects the transmitted blue, green, and red image signals to γ by a known γ correction circuit, masking processing circuit, and UCR processing circuit.
Processing such as correction, color turbidity removal, undercolor removal correction, and black signal extraction is performed to obtain yellow, magenta, cyan, and black image signals. The yellow, magenta, cyan, and black (hereinafter, also referred to as each color) image signals are supplied to the laser driver circuits 18Y, 1
Send to 8M, 18C, 18K. The laser driver circuits 18Y, 18M, 18C and 18K perform time-modulation processing for each pixel according to the size of the received image signal of each color, and emit a semiconductor laser for image exposure. Devices 19Y, 19M, 19
C, 19K are driven. By this driving, laser beams 20Y, 20M, 20C, and 20K are emitted from the laser exposure devices for image exposure 19Y, 19M, 19C, and 19K.
The image data is sent to image forming units 33Y, 33M, 33C, and 33K as image forming means described later, which are shown in FIG.

The four image forming units 33Y, 33M, 3
In 3C and 33K, the configuration other than the color of the toner to be used is almost the same, so the configuration will be described using the yellow image forming unit 33Y located on the rightmost side in the drawing as an example. Note that, regarding the structure of the other image forming units, the same reference numerals as those in the yellow image forming unit 33Y with the suffixes M, C, and K are shown in the drawings as the corresponding members, and description thereof is omitted. I do.

As shown in FIG. 1, the yellow image forming section 3
In 3Y, the laser beam 20Y is reflected on a polygon mirror 24Y that is driven to rotate by a scanner motor 25Y. The f · θ lens 7 performs an optical correction process so that the reflected laser beam 20Y can be scanned at a constant speed.
7Y. The writing light 26Y modulated by the optical correction process scans the surface of a photosensitive drum 27Y as an image carrier which is driven to rotate clockwise in the figure by a drive system (not shown) in a direction perpendicular to the rotation direction. I do. About 11 m in the rotation direction of the polygon mirror 24Y from the optical writing start position on the photosensitive drum 27Y.
m on the upstream side. D sensor (photo sensor) is provided, and when the writing light 26Y is detected with the rotation of the polygon mirror 24Y, B.D is sent to a control circuit (not shown). Transmit the D signal.

Around the photosensitive drum 27Y, a charging device 28Y for uniformly charging the surface of the photosensitive drum 27Y,
Developing device 29Y, static elimination lamp 30Y, transfer electrode 31Y,
A cleaning device 32Y and the like are provided. The above-described image exposure laser emitting device 19Y, charging device 28Y, and developing device 29Y constitute a toner image forming unit that forms a toner image on the photosensitive drum 27Y. The surface of the photosensitive drum 27Y, which has moved to a position facing the charging device 28Y with the rotation, is uniformly charged by the charging device 28Y, and then moves to a position facing the polygon mirror 24Y. At this facing position, the above-described writing light 2
6Y is irradiated, and a yellow electrostatic latent image is formed on the surface of the writing light 26Y. In this yellow electrostatic latent image,
When the photosensitive drum 27Y is rotated and moved to a developing position which is a position facing the developing device 29Y, the developing device 29
The yellow toner moving from Y adheres and is visualized (developed) as a yellow toner image. The developing device 29Y that uses yellow toner as a developer causes the yellow toner to adhere to the yellow electrostatic latent image by a so-called magnetic blade method.

The surface of the photosensitive drum 27Y, which has been developed into a yellow toner image, discharges the charge of the yellow electrostatic latent image when passing through a position facing the charge removing lamp 30Y, and then contacts the transfer electrode 31Y. It moves to the transfer position (image transfer section) which is the opposing position. At the lower side of the main body of the copying machine, a transport belt 36 stretched around a driving roller 35 driven by a motor 52 (see FIG. 3) in a counterclockwise direction and a driven roller 34 is disposed. The conveying belt 36 that rotates in the counterclockwise direction in the drawing has a rotation path of the image forming units 33Y, 33M, 33C, and 33K of the respective colors.
Are transferred through the respective transfer positions.

As shown in FIG. 1, on the right side of the conveyor belt 36, a paper supply device 54 as a recording material supply device, and the paper 50 fed from the paper supply device 54 are transferred at a predetermined timing. Registration roller pair 38 to be sent to the position and paper 50
Sensor 39 as recording material detecting means for detecting
And a leading edge aligning means 56 for aligning the leading edge of the sheet 50 (claim 2).

The right-hand configuration of the conveyor belt 36 will be described in detail with reference to FIGS. The paper feeding device 54 includes a paper feeding cassette 41 in which the papers 50 are stored in a stacked state, a paper feeding roller 43 that feeds the papers 50 one by one in order from the uppermost one. The registration roller pair 38 can release the nip pressure by the nip pressure release means 58 to separate the nip portion. The nip pressure releasing means 58 includes a support shaft 4 fixed to a device side plate (not shown).
2, a central portion of which is rotatably supported by the support shaft 42 and one end of which is provided on the upper rotation shaft 38a of the registration roller pair 38.
A lever 41 rotatably supported by the lever 41, and a solenoid 40 as a driving means whose movable rod is locked at the other end of the lever 41. Registration roller pair 38
Is rotationally driven by a motor 60 as shown in FIG. A drive gear 62 is fixed to a rotation shaft of the motor 60, and the drive gear 62 meshes with a gear 64 fixed to an end of the lower rotation shaft 38 b of the registration roller pair 38. The gear 64 meshes with a gear 66 fixed to an end of the upper rotating shaft 38a, and the torque of the motor 60 is transmitted.

The registration roller pair 38 is composed of a plurality of small-width rollers 38c provided at both upper and lower sides of the registration roller 38 at intervals in the sheet width direction orthogonal to the sheet conveying direction. Although not shown in FIG. 5, the nip pressure releasing means 58 is provided on both sides of the pair of registration rollers 38, and when the solenoid 40 is turned on, the pair of registration rollers 38 is opened so that the nip portion is separated. When the switch is off, a pressure is applied by a spring (not shown) and its own weight, and a nip portion is formed. Registration sensor 39
Is provided downstream of the pair of registration rollers 38 in the sheet transport direction, and has a light emitting diode 39a and a light receiving element 39b.

The leading end aligning means 56 includes a rotating shaft 70 extending in a sheet width direction orthogonal to the sheet conveying direction, and two L-shaped abutting plates 4 provided integrally with the rotating shaft 70.
9 and 49, and a solenoid 46 as a driving means for driving the rotary shaft 70. Rotating shaft 70
Is fixed to one end of a lever 72.
A movable rod of a solenoid 46 is locked to the other end of the second lever 2. Although not shown in FIG. 5, the drive configuration of the rotary shaft 70 is also provided on both sides of the rotary shaft 70. The abutment plate 49 includes a base 49 a having one end fixed to the rotation shaft 70.
And an abutment surface 49b that rises upward from the leading end of the base 49a in the paper transport direction. Butt surface 49
b is located further downstream of the registration sensor 39. When the solenoid 46 is off, the abutting surface 49b
Closes the transport path of the sheet 50, and when turned on, the abutting surface 49b retreats from the transport path.

Also, three transport guide pairs 48 are provided at intervals in the paper width direction orthogonal to the paper transport direction (claim 7). Each transport guide pair 48 has an upper guide 48a and a lower guide 48b, and is configured to have a start end upstream of the registration roller pair 38 in the paper transport direction and an end end near the abutting surface 49b ( Claim 4). Further, each of the conveying guide pair 48 is provided so as frontage frontage wide and terminating the starting end side is narrowed (claim 5). More specifically, the upper guide 48a and the lower guide 48b are provided so as to come into contact with each other toward the terminal end by elastic force. A braking operation (braking operation) is applied to the motor (claim 6).

Next, the paper feeding operation in the above configuration will be described. FIG. 6 shows a state before paper feeding. In this state,
The solenoid 40 of the nip pressure releasing means 58 is on, and the nip portion of the registration roller pair 38 is open. Also, the solenoid 46 of the tip aligning means 56 is off and the abutting surface 4
9b blocks the conveyance path of the sheet 50. When a paper feed command is issued by control means (not shown), as shown in FIG.
The feed roller 43 is driven to rotate by a motor (not shown), and the uppermost sheet 50 is separated and fed. The fed sheet 50 passes between the pair of registration rollers 38 with the nip portion opened, and passes through the pair of conveyance guides 48 while pressing them apart. The paper feed roller 43 is stopped a predetermined time after the leading edge of the paper 50 is detected by the registration sensor 39.

The "constant time" here is not the time during which only a part of the leading end of the paper 50 abuts against the abutting surface 49b, but the state in which the leading end of the paper 50 follows the abutting surface 49b over the entire width direction. It is time until it becomes. Overfeed is performed as in the conventional case. Since the sheet 50 is sandwiched between the pair of conveyance guides 48 between the registration roller pair 38 and the abutting surface 49b, the sheet 50 is held substantially linearly.
Therefore, the conventional loop due to excessive feeding is formed as a pre-registration loop 50a upstream of the registration roller pair 38 in the sheet conveying direction, as in the conventional case. In other words, the skew of the sheet 50 is corrected downstream of the registration roller pair 38 in the sheet conveying direction.

After the predetermined time has elapsed, as shown in FIG. 8, the solenoid 40 of the nip pressure releasing means 58 is turned off, and the pair of registration rollers 38 is pressed by a spring (not shown) and its own weight. After the registration roller pair 38 sandwiches the sheet 50, the solenoid 46 of the leading end aligning means 56 is turned on, and the abutting surface 49b is retracted from the conveyance path of the sheet 50 as shown in FIG.

The photosensitive drum 2 moved to near the transfer position
As shown in FIG. 4, the yellow toner image on 7Y contacts the paper 50 conveyed by the pair of registration rollers 38 at the same timing as the toner image, and the high voltage applied to the conveyance belt 36 by the transfer electrode 31Y. Is transferred onto the sheet 50 by the transfer bias. When the surface of the photosensitive drum 27Y that has passed through the transfer position passes through a position facing the cleaning device 32Y, residual toner that has not been transferred onto the sheet 50 is scraped off. Then, it moves again to a position facing the charging device 28Y, is uniformly charged, and shifts to the next image forming step.

Other image forming units 33M, 33C, 33K
The magenta toner image, the cyan toner image, and the black toner image are formed on the photosensitive drums 27M, 27C, and 27K by performing the image forming operation in the same manner as the image forming unit 33Y. Transfer electrode 31
By M, 31C, and 31K, the images are transferred so as to be superimposed on each other together with the yellow toner image, and become a full-color image. Further, after the transfer of the toner image, the paper 50 on the transport belt 36 is transported between the pressure roller 37a and the heating roller 37b in the fixing device 37 to perform the fixing process of the full-color image. Is discharged to

[0032]

According to the first aspect of the present invention, a recording material detecting means provided downstream of the registration roller pair in the recording material conveyance direction to detect the recording material, and the nip pressure of the registration roller pair is released. Nip pressure releasing means for separating the nip portion, and during the nip pressure release, the recording material is supplied a predetermined time after the leading end of the supplied recording material passes through the registration roller pair and is detected by the recording material detecting means. Since the conveyance of the recording material is stopped, and then the registration roller pair is pressed and the recording material is sent to the image transfer section at a predetermined timing by the registration roller pair, slip at the start of rotation of the registration roller pair is reduced. As a result, it is possible to obtain a uniform feed to the image transfer unit.

According to the second aspect of the present invention, a recording material detecting means provided downstream of the registration roller pair in the recording material conveyance direction to detect the recording material, and a nip portion for releasing the nip pressure of the registration roller pair Nip pressure releasing means for separating
The nip pressure release means is provided further downstream of the recording material detecting means, has a contact surface against which the leading end of the recording material abuts, and the contact surface has leading end aligning means capable of retreating from the conveyance path of the recording material. During a certain period of time after the leading end of the supplied recording material passes through the registration roller pair and is detected by the recording material detecting means, the conveyance of the recording material is stopped and the leading end is brought into contact with the abutting surface. The recording material is sent to the image transfer section at a predetermined timing by the registration roller pair after the registration roller pair is pressed properly, and then the registration roller pair is pressed and the contact surface is retracted from the conveyance path. In addition, there is no slip at the start of rotation of the registration roller pair, and accurate registration without variation can be performed, which can contribute to improvement in image quality.

According to the third aspect of the present invention, the leading end aligning means includes a rotating shaft extending in the width direction orthogonal to the recording material conveying direction, and a butting plate integrally provided with the rotating shaft and having a butting surface. And a driving means for driving the rotating shaft, it is possible to correct the abutting of the leading end of the recording material (correction of oblique displacement) with a simple configuration and a small driving force.

According to the fourth aspect of the present invention, since there is provided a pair of transport guides having a starting end upstream of the registration roller pair in the recording material conveying direction and an end near the abutting surface, excessive feeding is achieved. Can be avoided on the downstream side of the pair of registration rollers.

According to the fifth aspect of the present invention, the pair of transport guides is provided so that the front end has a wide frontage and the front end has a narrow frontage. What can be done downstream of the pair can be avoided.

According to the sixth aspect of the present invention, the trailing end of the pair of transport guides is brought into contact with the elastic force, and the recording material is sandwiched from both front and back sides to apply a braking action to the recording material during transport. Therefore, it is possible to avoid with high accuracy that a loop due to excessive feeding is formed on the downstream side of the registration roller pair.

According to the seventh aspect of the present invention, a plurality of conveyance guide pairs are provided at intervals in the width direction orthogonal to the conveyance direction of the recording material. As compared with the case, it is possible to efficiently avoid a loop caused by excessive feeding from being formed on the downstream side of the registration roller pair at a low material cost.

According to the eighth aspect of the present invention, the pair of registration rollers is constituted by a plurality of rollers provided at intervals in a width direction orthogonal to the recording material conveyance direction. Compared with the configuration, the function of holding and conveying the recording material based on the predetermined timing can be efficiently performed at a low material cost.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a color copying machine as an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a control block diagram.

FIG. 3 is a perspective view of an image forming unit.

FIG. 4 is a schematic front view around a sheet feeding device as a recording material supply device.

FIG. 5 is a schematic perspective view of the periphery of a pair of registration rollers.

FIG. 6 is a schematic front view of the periphery of a pair of registration rollers, showing a state before sheet feeding.

FIG. 7 is a schematic front view of the periphery of a pair of registration rollers, showing a state in which paper is fed and the leading edge of a recording material is aligned.

FIG. 8 is a schematic front view of the periphery of a pair of registration rollers, showing a state where the registration roller pair is pressurized after paper is fed and the leading edge of a recording material is aligned.

FIG. 9 is a schematic front view of the periphery of a pair of registration rollers, showing a state in which the registration roller pair is pressurized after the paper is fed and the leading edge of the recording material is adjusted, and then the abutting surface is retracted from the conveyance path of the recording material. FIG.

[Explanation of symbols]

27Y, 27M, 27C, 27K Photoreceptor drum as image carrier 38 Registration roller pair 39 Recording material detecting means 46 Solenoid as driving means 48 Transport guide pair 49a Butting plate 49b Butting surface 50 Sheet as recording material 54 Recording Paper feeder as material supply device 56 Tip alignment means 58 Nip pressure release means 70 Rotary shaft

Claims (8)

[Claims] A recording material conveyed and supplied from a recording material supply device is sent to an image transfer unit at a predetermined timing by a pair of registration rollers, and a visible image formed on an image carrier is transferred to the image transfer unit by the image transfer unit. In an image forming apparatus for transferring to a recording material, a recording material detecting means provided downstream of the registration roller pair in the recording material conveyance direction to detect the recording material, and a nip pressure of the registration roller pair is released to separate the nip portion. A nip pressure releasing means for causing the recording material to be conveyed a predetermined time after the leading end of the supplied recording material passes through the pair of registration rollers and is detected by the recording material detecting means while the nip pressure is released. The recording material is fed to the image transfer section at the predetermined timing by the pair of registration rollers by pressing the pair of registration rollers. 2. A recording material conveyed and supplied from a recording material supply device is sent to an image transfer unit at a predetermined timing by a pair of registration rollers, and a visible image formed on an image carrier is transferred to the image transfer unit by the image transfer unit. In an image forming apparatus for transferring to a recording material, a recording material detecting means provided downstream of the registration roller pair in the recording material conveyance direction to detect the recording material, and a nip pressure of the registration roller pair is released to separate the nip portion. Nip pressure releasing means for causing the recording material to be provided further downstream of the recording material detecting means, and a leading end aligning means having a contact surface against which the leading end of the recording material abuts, and the contact surface being retractable from the conveyance path of the recording material. During the release of the nip pressure, the conveyance of the recording material is stopped after a certain period of time from when the leading end of the supplied recording material passes through the registration roller pair and is detected by the recording material detecting means, and Butting After properly abutting the tip against the surface, and then pressing the pair of registration rollers to retract the abutting surface from the conveyance path, the image transfer of the recording material is performed by the pair of registration rollers at the predetermined timing. And an image forming apparatus. 3. An image forming apparatus according to claim 2, wherein said tip alignment means comprises a rotary shaft extending in the widthwise direction perpendicular to the transport direction of the recording material, the abutment surface is provided integrally with the rotating shaft An image forming apparatus, comprising: an abutment plate having: a driving means for driving the rotating shaft. 4. The image forming apparatus according to claim 1, wherein the pair of registration rollers has a starting end upstream of the pair of registration rollers in a recording material conveying direction and an end near the abutting surface. An image forming apparatus comprising: 5. The image forming apparatus according to claim 4, wherein the pair of transport guides is provided such that the front end has a wide frontage and the terminal end has a narrow frontage. apparatus. 6. The image forming apparatus according to claim 5, wherein said trailing ends of said pair of conveying guides contact each other with elastic force, and said recording material is sandwiched from both front and back surfaces thereof to exert a braking action on said recording material during conveyance. And an image forming apparatus. 7. The image forming apparatus according to claim 4, wherein a plurality of the conveyance guide pairs are provided at intervals in a width direction orthogonal to a conveyance direction of the recording material. An image forming apparatus comprising: 8. The image forming apparatus according to claim 1, wherein the registration roller pair includes a plurality of registration rollers arranged at intervals in a width direction orthogonal to a recording material conveyance direction. An image forming apparatus comprising a roller.