JP4434434B2 - Sheet conveying apparatus and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet conveying apparatus and an image forming apparatus having a function of conveying a sheet by a conveying belt.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an image forming apparatus, in particular, an electrophotographic method and an image forming apparatus provided with a plurality of image carriers, a sheet conveying apparatus provided with a conveying belt (hereinafter referred to as a transfer belt) at a transfer position. Is provided.
[0003]
In such an apparatus, a plurality of image forming units (magenta, cyan, yellow, black in the case of normal full color) are arranged for each color along the transfer belt.
[0004]
In addition to the image carrier (photosensitive drum, etc.), this image forming unit is provided with a developing device that performs development with toner of each color.
[0005]
With the configuration as described above, the toner images of the respective colors formed on the image carrier are sequentially transferred onto the sheet conveyed while being electrostatically attracted by the transfer belt, and thereafter, the image is not fixed on the sheet by the fixing device. The image is fixed.
[0006]
A registration roller is provided upstream of the transfer belt in the sheet conveyance direction to convey the sheet onto the transfer belt in a timely manner. The conveyance speed of the registration rollers is usually set to be higher than the conveyance speed of the transfer belt so that the sheet being conveyed is not pulled by the transfer belt.
[0007]
In order to reduce the size of the apparatus, the registration roller is disposed below the sheet conveyance surface of the transfer belt. In such a case, the conveyance direction of the sheet conveyed by the registration roller is changed. A guide to change is provided.
[0008]
[Problems to be solved by the invention]
However, in the case of the prior art as described above, the following problems have occurred.
[0009]
As described above, in an image forming apparatus in which a sheet is attracted to a transfer belt and an image is formed using a plurality of image carriers, a speed difference from a registration roller or a conveying force when the sheet is attracted to the transfer belt. Since problems such as color misregistration occur due to the difference and the like, it is necessary to avoid this.
[0010]
In view of this, some measures that have been conventionally employed are first arranged such that the distance between the registration roller having a conveying force and the transfer belt is longer than the conveying length of the corresponding material.
[0011]
In this case, it is necessary to secure a sufficient distance between the registration roller and the transfer belt, which not only increases the size of the image forming apparatus itself, but also reduces registration accuracy, which is disadvantageous in terms of cost. It is inevitable.
[0012]
Next, when the sheet to be conveyed passes through the registration roller and reaches the transfer belt, there is a mechanism that releases the nipping of the registration roller and avoids a speed difference between the registration roller and the transfer conveyance roller. In this case, it is necessary to estimate the mechanism required to release the registration roller and the cost of the mechanism, and depending on the combination of the sheet conveyance path in the vicinity and the size of the corresponding material, Further, it may be necessary to release the holding of the upstream roller.
[0013]
Usually, as a means for suitably placing the sheet on the sheet transfer belt, there are many cases where the nip position of the registration roller is above the transfer belt conveyance section (conveyance surface). In order to change the conveyance direction of the sheet sent from the sheet feeding cassette arranged below, it is necessary to have enough space to change the direction upstream of the registration roller conveyance direction. However, an increase in the size of the main body was inevitable.
[0014]
Further, there is a drive unit that can finely adjust the conveyance speed, although there is also a unit that adjusts the conveyance speed of the sheet conveyance unit immediately before the transfer belt to such an extent that no adverse effect occurs on the transfer belt. After endurance due to long-term use, etc., if the conveyance force decreases due to wear of the rollers of the conveyance means, it may be necessary to adjust the conveyance speed each time. There must be.
[0015]
In either case, the image forming apparatus is an obstacle to downsizing and cost reduction. Therefore, it is a problem to make the transport unit and other mechanisms just before the transfer belt compact.
[0016]
The present invention has been made in order to solve the above-described problems of the prior art, and an object of the present invention is to provide a sheet conveying apparatus and an image that enable stable sheet conveyance while reducing the size of the apparatus with a simple configuration. It is to provide a forming apparatus.
[0017]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, there are provided a first conveying roller that conveys a sheet, a conveying belt that conveys a sheet conveyed by the first conveying roller further downstream, and the conveying belt. A second conveyance roller that forms a nip therebetween and conveys the sheet while being nipped in cooperation with the conveyance belt, and a sheet conveyance direction by the first conveyance roller, and a sheet by the second conveyance roller In the sheet conveying apparatus in which the conveying direction of the first conveying roller is not collinear and the conveying speed of the first conveying roller is set to be higher than the conveying speed of the conveying belt, the sheet to be conveyed is the first conveying roller . A rigid guide for guiding a sheet to be conveyed while securing a space in which a loop can be formed between the first conveying roller and the second conveying roller; Deflection deformably provided on the sheet conveying surface of the rigid guide at the inner, the first conveying direction of the distal end of the sheet conveyed by the conveying roller abuts a flexural deformation in response to the stiffness of the sheet A flexible guide that guides the sheet onto the conveyance belt or a nip between the second conveyance roller and the conveyance belt, and the flexible guide has one end on the downstream side in the sheet conveyance direction with the rigidity. The guide is fixed to the sheet conveying surface side, and the upstream end is an open end .
[0018]
Accordingly, even when the sheet forms a loop while the abutting angle (contact angle) of the conveyed sheet is set to a desired angle, the formation of the loop is not hindered by bending deformation.
[0019]
The transported sheet includes a rigid guide that guides the transported sheet while ensuring a space in which a loop can be formed between the first transport roller and the second transport roller.
The flexible guide may be provided on the sheet conveying surface side of the rigid guide so as to be able to bend and deform to a position in contact with the inner peripheral surface of the rigid guide.
[0020]
In the flexible guide, one end on the downstream side in the sheet conveying direction is fixed to the sheet conveying surface side of the rigid guide, and the upstream end is preferably an open end.
[0021]
The rigid guide has a curved portion,
The flexible guide may have a curved portion having a radius of curvature larger than the radius of curvature of the curved portion of the rigid guide when the sheet is not in contact with the flexible guide.
[0022]
The flexible guide may be composed of an elastic body.
[0023]
The flexible guide may be arranged so as to cover a region through which both ends of all sheets that can be conveyed pass.
[0024]
The first conveying roller may be provided below a sheet conveying surface of the conveying belt.
[0025]
The transport speed of the first transport roller may be faster than the transport speed of the transport belt.
[0026]
Further, in the image forming apparatus of the present invention, the above sheet conveying device;
Image forming means for forming an image on a sheet conveyed by the conveyance belt.
[0027]
The conveyance belt may be a transfer belt that conveys a sheet while electrostatically adsorbing the sheet and transfers a toner image formed on the image carrier.
[0028]
The first conveying roller may be a registration roller that conveys a sheet while taking image formation timing.
[0029]
The second transport roller may be a suction roller having at least one of an auxiliary function for electrostatically attracting the sheet and a function for preventing misalignment before the electrostatic adsorption of the entire area of the sheet is completed.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Exemplary embodiments of the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.
[0031]
The present invention is applied to various sheet conveying apparatuses and various image forming apparatuses including the sheet conveying apparatus. In particular, an image is formed by adsorbing a sheet to a transfer belt and using a plurality of image carriers. It can be suitably applied to an image forming apparatus that performs the above.
[0032]
Further, even in such an image forming apparatus, in particular, in order to reduce the size of the apparatus, even when the distance between the image forming unit and the registration roller is short and the registration roller is below the sheet conveyance surface of the transfer belt, It is for conveying a sheet suitably and performing image formation suitably.
[0033]
(Embodiment)
A sheet conveying apparatus and an image forming apparatus according to an embodiment of the present invention will be described with reference to FIGS.
[0034]
First, the entire image forming apparatus will be described with particular reference to FIG. FIG. 1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention.
[0035]
The image forming apparatus selectively feeds a sheet on which an image is formed from the manual feed tray 1 or the supply cassette 2, places the sheet on the transfer belt 8 serving as a transport belt, and further transports the sheet to the image forming unit. Here, when a sheet is fed from the supply cassette 2, the sheet is fed by the feeding roller 25, and the sheet fed by the feeding roller 25 is further conveyed by the conveying roller 24.
[0036]
The transfer belt 8 is wound around a driving roller 20 and rotatable driven rollers 19, 21, and 22, and is configured to be rotated by the rotational driving of the driving roller 20. Further, the transfer belt 8 can be electrostatically adsorbed by being charged by the charging brush 23.
[0037]
Then, it is formed on the surfaces of the electrophotographic image carriers 4, 5, 6 and 7 serving as the four image forming means in accordance with the electrical signal of the image information transmitted from a reader scanner, personal computer or the like (not shown). The toner image is sequentially transferred onto the sheet conveyed on the transfer belt 8 and then permanently fixed by the fixing device 9 so that the sheet on which the full color image is formed is placed on the discharge tray 14 mounted on the main body of the image forming apparatus. To discharge.
[0038]
In the present embodiment, LEDs (light emitting diodes) 10, 11, 12, independently controlled as light source devices for forming toner images on the surfaces of the image carriers 4, 5, 6, 7, respectively. 13 is configured to face the surface of each of the image carriers 4, 5, 6, and 7, but the light source device is not limited to the LED.
[0039]
Further, in the present embodiment, the transfer belt 8 is a film-like one and electrostatically adsorbs the sheet so that the toner images formed on the surfaces of the image carriers 4, 5, 6, and 7 are transferred. When sequentially transferring to a sheet, various problems due to sheet misalignment represented by color misregistration are avoided.
[0040]
Here, in the image forming apparatus according to the present embodiment, for the purpose of downsizing and cost reduction, the positions of the registration roller 3 as the first conveying roller having a relatively conveying force and the transfer belt 8 are close to each other. The distance between the registration roller 3 and the suction roller 15 as the second transport roller is configured to be short.
[0041]
Further, a means for absorbing a speed difference or a conveyance force difference between the registration roller 3 and the transfer belt 8 without providing a mechanism for releasing the holding of the registration roller 3 and without adjusting the rotation speed of the registration roller 3. Have The registration roller 3 is disposed below the sheet conveying surface of the transfer belt 8.
[0042]
The registration roller 3 includes a pair of rollers 3a and 3b that sandwich the sheet. Then, the leading edge of the sheet conveyed by the conveying roller 24 is abutted against the nip of the stopped registration roller 3 and is bent to correct skewing. Rotation is started at the timing synchronized with the image formation by 5, 6 and 7, and the sheet is conveyed.
[0043]
Under the above conditions, a configuration for suitably performing sheet conveyance and image formation will be described in more detail.
[0044]
First, the conveyance speed of the registration roller 3 is set to be about 1 to 3% higher than the sheet conveyance speed of the transfer belt 8. For example, when the sheet conveyance speed of the transfer belt 8 of the image forming apparatus in this embodiment is 100 mm / sec, the sheet conveyance speed of the registration roller 3 is set to 101 to 103 mm / sec.
[0045]
Next, in order to avoid the adverse effect of the sheet conveyance speed of the registration roller 3 being higher than the sheet conveyance speed of the transfer belt 8, the sheet is transferred to the transfer belt on the upstream side of the image carrier 4 on which the transfer is first performed. A sufficient pressing force is applied to the suction roller 15 for assisting the electrostatic chuck 8 so that the transfer of the registration roller 3 does not directly affect the transfer portion.
[0046]
For example, in the image forming apparatus according to the present embodiment, the pressure of the suction roller 15 is set to about 45N. Further, the sheet slack caused by the difference in the conveyance speed between the registration roller 3 and the transfer belt 8 is absorbed by providing a loop space in the conveyance section.
[0047]
Further, in order to make the image forming apparatus according to the present embodiment compact, as described above, the registration roller 3 that is the conveying means immediately before the transfer belt 8 is located below the conveying portion of the transfer belt 8. .
[0048]
Therefore, the conveyance direction of the transfer belt 8 is not collinear with the nip direction (conveyance direction) of the registration roller 3, and the sheet conveyance direction is changed in a loop space between the registration roller 3 and the suction roller 15. It has a path shape.
[0049]
Here, if the sheet if in an ideal state is conveyed, if less than 90 ° contact angle at the leading end of the conveyed sheet abuts against the suction roller before the guide 16, in theory Although it is possible to change the conveyance direction of the sheet, it is generally desirable to set the contact angle to 60 ° or less in order to suitably change the conveyance direction. The “contact angle” as used herein refers to a state in which the front end of the sheet material in the conveyance direction is in contact with the guide member, and the sheet material is conveyed more than the contact portion of the guide member with the front end of the sheet material in the conveyance direction. It refers to the angle formed by the portion on the side that comes in contact with the sheet material in contact. Hereinafter, this angle is referred to as “contact angle”.
[0050]
However, in actuality, the sheet is not necessarily conveyed in an ideal state, and there is a sheet that is slightly bent or curled at the end of the sheet. In particular, as shown in FIG. When a curl that is curved is formed and conveyed, the adsorbing roller as a rigid guide at the leading end of the sheet is secured with a sufficient loop space provided between the registration roller 3 and the adsorbing roller 15 It is extremely difficult to set the contact angle with respect to the front upper guide 16 to be 60 ° or less.
[0051]
For example, when curls having the same direction and the same curved state are formed in the entire front end of the sheet, the timing of reaching the suction roller 15 at the front end of the sheet differs depending on the curved state, and as a result, the drawing of the sheet The problem is that the leading edge margin of the captured image is different from the setting.
[0052]
On the other hand, if the curled state of the conveyed sheet can be predicted to some extent, it is not necessarily difficult to avoid the problem by controlling the shape and arrangement of the suction roller front upper guide 16 or the image writing timing. .
[0053]
However, curls (FIG. 6B) where only the corners of the sheet, which are often seen on the regenerated copy paper, are curved, or A4R feeding of ordinary A4 size copy paper (feeding in the longitudinal direction) Curl that is often seen when the sheet is conveyed at the left and right end portions of the sheet that are parallel to the conveyance direction (the front and rear end portions toward the image forming apparatus in FIG. 6) are curved (FIG. 6A). In the sheet leading edge, the contact angle between the central portion and the left and right ends with respect to the suction roller front upper guide 16 is different, and it is difficult to simply control the contact angle of the sheet by devising the guide shape and arrangement. .
[0054]
In the worst case, the corner portion of the sheet may be folded when the corner portion of the sheet contacts the upper guide 16 on the suction roller, and it is not easy to convey the sheet suitably.
[0055]
As shown in FIG. 7, when performing image formation on the second side of automatic duplex, the curl state is also unstable, and the curl shape varies greatly depending on the type of sheet and the image on the first side. It is very difficult to transport.
[0056]
Therefore, in the sheet conveying apparatus according to the present embodiment (or an image forming apparatus equipped with the sheet conveying apparatus), the leading edge of the sheet is preferably guided from the registration roller 3 to the suction roller 15, and at the same time, the conveyance speed of the registration roller 3 and In order to reliably absorb the slack of the sheet caused by the transfer speed difference of the transfer belt 8 in the loop space, an auxiliary guide film 17 as a flexible guide made of an elastic body is provided on the upper guide 16 of the suction roller.
[0057]
Hereinafter, the auxiliary guide film 17 will be described in detail with particular reference to FIGS. 2, 4 and 5 are schematic side views of the main part of the sheet conveying apparatus according to the embodiment of the present invention, and FIG. 3 is a guide constituting the sheet conveying apparatus according to the embodiment of the present invention ( It is a schematic plan view of a rigid guide and a flexible guide. In the figure, reference numeral 18 denotes a guide for guiding the sheet.
[0058]
The configuration of the auxiliary guide film 17 will be described in detail. The auxiliary guide film 17 is attached to the upper guide 16 on the suction roller with a double-sided tape only in the portion A in FIGS. 2 and 3 corresponding to the downstream side in the transport direction. . Therefore, the upstream end is an open end.
[0059]
In the present embodiment, the auxiliary guide films 17 are arranged in parallel so as to be aligned in a direction perpendicular to the conveyance direction, and the sheet size ( (The maximum width: 304.8 mm, the minimum width: 100 mm). FIG. 3 shows the passing positions at both ends in each sheet size.
[0060]
As a result, all the sheets that can be conveyed are guided with their both ends always in contact with the auxiliary guide film 17.
[0061]
For reference, the size of the auxiliary guide film 17 used here is about 36 mm in length in the conveyance direction and about 120 mm in width, the material of the film is PET, and the thickness is about 140 μm.
[0062]
Further, the adhesive region by the double-sided tape has a width of about 5 mm over the entire downstream end portion in the transport direction, and is set so as to form a curve having a larger curvature than the curved shape of the suction roller front upper guide 16.
[0063]
Next, the effect of providing the auxiliary guide film 17 will be described in detail with reference to FIGS. 4 and 5. 4 shows a state at the moment when the leading edge of the conveyed sheet contacts the auxiliary guide film 17, and FIG. 5 shows a state where the conveyance by the registration roller 3 and the conveyance by the suction roller 15 are performed simultaneously. ing.
[0064]
As a first step, as shown in FIG. 4, the leading edge of the sheet sent from the registration roller 3 comes into contact with a position on the sheet passing surface side of the auxiliary guide film 17, and then adsorbs while sliding on the sheet passing surface. It is sent to the roller 15.
[0065]
That is, this makes it possible to make the contact angle of the front end of the sheet in the conveyance direction smaller than when directly contacting the upper guide 16 of the suction roller (the definition of the contact angle is as described above). Therefore, it is possible to change the transport direction. (Based on differences in radius of curvature and fixed angles)
That is, in the case of only the suction roller front upper guide 16 having no flexibility (stiffness), the setting of the angle has a limit in order to fulfill the function of a guide for changing the sheet conveyance direction. (There is a limit even if you want to set the contact angle as acute as possible.)
In contrast, in the case of the auxiliary guide film 17, since it has flexibility , the contact angle with the auxiliary guide film 17 when the leading end of the sheet in the conveying direction hits is set to be as acute as possible. However, by performing the bending deformation thereafter (in some cases, by bending to a position where the suction roller front upper guide 16 abuts on the inner peripheral surface), it can be guided in a desired conveyance direction.
[0066]
As the second stage, the registration roller 3 has a sheet conveyance speed higher than that of the transfer belt 8 (actually, mainly the suction roller 15). Therefore, as shown in FIG. It becomes larger while being conveyed between the suction rollers 15.
[0067]
At that time, the enlarged loop pushes up the entire auxiliary guide film 17 in the direction of the suction roller front upper guide 16 so that the sheet can be transported suitably without hindering the original purpose of absorbing the loop in the loop space. It becomes possible.
[0068]
Of course, it is necessary to pay attention to the conditions for the conveyed sheet to push up the auxiliary guide film 17. However, if the auxiliary guide film 17 is made of the material described above or its equivalent, there is a problem. Absent.
[0069]
Here, in the present embodiment, the reason why the auxiliary guide film 17 is attached to the downstream side with respect to the sheet conveyance direction and the area A portion is provided is that the conveyance is performed in the first stage described above. This is to avoid the influence of the strength (hardness) of the waist of the coming sheet as much as possible.
[0070]
That is, the effect of the waist (here, elastic force) of the auxiliary guide film 17 is greater near the adhesive portion which is the A portion, and even when a relatively thin film is used as the auxiliary guide film 17, the leading edge of the sheet is In the vicinity of the adsorbing roller 15, the auxiliary guide film 17 is not easily pushed in the direction of the adsorbing roller front upper guide 16, and the leading end of the sheet can be preferably guided to the adsorbing roller 15, and the conveying direction of the sheet is preferably changed. It becomes possible.
[0071]
If the auxiliary guide film 17 is attached on the upstream side with respect to the conveyance direction, the leading edge of the auxiliary guide film 17 is the auxiliary guide film in the case of a sheet with low waist strength (here, hardness). In the case of a sheet having a strong waist (here, hardness), the leading edge pushes up the auxiliary guide film 17 in the direction of the suction roller front upper guide 16. When the sheet is conveyed, the conveyance distance at the leading edge of the sheet differs accordingly, and the margin of the image drawn as a result may vary depending on the strength (hardness) of the sheet waist.
[0072]
Therefore, it is better to set the attachment position of the auxiliary guide film 17 on the downstream side with respect to the sheet conveying direction.
[0073]
The reason why a relatively thin film is used for the auxiliary guide film 17 is that the auxiliary guide film 17 is reversed when the sheet pushes up the auxiliary guide film 17 to form a loop in the second stage described above. This is because the sheet is preferably conveyed by reducing the action of pushing back the sheet.
[0074]
That is, if the force of pushing back the sheet by the auxiliary guide film 17 is too large, the conveyance direction will be caused if the auxiliary guide film 17 pushes the loop in a state where the leading end of the sheet that has passed through the suction roller 15 is not sufficiently attracted to the transfer belt. The sheet is being transferred, the transfer sheet is partially faster than the set conveyance speed, and the positions of the images transferred by the image carriers 4, 5, 6, and 7 do not match. This leads to a problem of so-called color misregistration.
[0075]
Therefore, it is better to use a relatively thin film as the auxiliary guide film 17.
[0076]
【The invention's effect】
As described above, the present invention is a simple configuration in which a flexible guide is provided, and the conveyance means is provided below the sheet conveyance surface by the conveyance belt in order to reduce the size of the apparatus. Even if it exists, it becomes possible to perform the stable sheet conveyance.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic side view of a main part of a sheet conveying apparatus according to an embodiment of the present invention.
FIG. 3 is a schematic plan view of guides (a rigid guide and a flexible guide) constituting the sheet conveying apparatus according to the embodiment of the present invention.
FIG. 4 is a schematic side view (showing a state of sheet conveyance) of a main part of the sheet conveyance apparatus according to the embodiment of the present invention.
FIG. 5 is a schematic side view of the main part of the sheet conveying apparatus according to the embodiment of the present invention (showing how the sheet is conveyed).
FIG. 6 is a perspective view showing a curled state (mode) of a sheet.
FIG. 7 is a schematic side view illustrating a state where a curled sheet is conveyed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tray 2 Supply cassette 3 Registration roller 4, 5, 6, 7 Image carrier 8 Transfer belt 9 Fixing device 14 Paper discharge tray 15 Adsorption roller 16 Adsorption roller front upper guide 17 Auxiliary guide film

Claims (9)

A first conveying roller for conveying a sheet;
A conveying belt for conveying the sheet conveyed by the first conveying roller further downstream;
A second conveyance roller that forms a nip with the conveyance belt and conveys the sheet while nipping in cooperation with the conveyance belt, and a conveyance direction of the sheet by the first conveyance roller; In the sheet conveying apparatus in which the conveying direction of the sheet by the two conveying rollers is not collinear and the conveying speed of the first conveying roller is set to be higher than the conveying speed of the conveying belt ,
A rigid guide for guiding the conveyed sheet while ensuring a space in which the conveyed sheet can form a loop between the first conveying roller and the second conveying roller;
The rigid guide is provided on the sheet conveying surface side of the rigid guide so as to be able to bend and deform in the space, and the leading edge in the conveying direction of the sheet conveyed by the first conveying roller comes into contact with it , and the waist strength of the sheet a flexible guide deflection while deformation leads the sheet into the nip between the conveyor belt and the conveyor belt or the second conveyor roller according to,
With
One end of the flexible guide on the downstream side in the sheet conveyance direction is fixed to the sheet conveyance surface side of the rigid guide, and an upstream end is an open end . Together with the rigid guide having a curved portion, said flexible guide, in a state where the sheet is not in contact, characterized in that it has a curved portion having a rigid guide radius of curvature larger than the radius of curvature of the curved portion of the The sheet conveying apparatus according to claim 1 . It said flexible guide sheet conveying apparatus according to claim 1 or 2, characterized in that it is constituted by an elastic body. Said flexible guide sheet conveying apparatus according to any one of claims 1-3, characterized in that it is arranged to cover an area where both ends of all the sheet can be conveyed to pass through. Wherein the first conveying roller, a sheet conveying apparatus according to any one of claims 1-4, characterized in that provided below the sheet conveyance surface of the conveyor belt. A sheet conveying device according to any one of claims 1 to 5 ,
An image forming apparatus comprising: an image forming unit that forms an image on a sheet transported by the transport belt. The image forming apparatus according to claim 6 , wherein the conveyance belt is a transfer belt that conveys a sheet while electrostatically attracting the sheet and transfers a toner image formed on the image carrier onto the sheet . The image forming apparatus according to claim 6, wherein the first conveying roller is a registration roller that conveys a sheet while taking an image forming timing. The second conveying roller is an adsorption roller having at least one of an auxiliary function for electrostatically adsorbing a sheet and an anti-shift function before electrostatic adsorption of the entire area of the sheet is completed. The image forming apparatus according to any one of claims 6 to 8 .

Images