JPH06211376A - Image forming device - Google Patents

Abstract

PURPOSE:To form a good recording image on a recording sheet by preventing external force, which acts on a belt member in the case of transcribing an image from the belt member to the recording sheet, from propagating in a peripheral surface direction of this belt member, in various image forming devices for forming an image by using the belt member. CONSTITUTION:A recording sheet 30 held to a belt member 20 is conveyed facing to image forming means 10Bk,..., and by assuming an image forming device, forming a recording image in accordance with image information relating to this recording sheet 30, as a premise, a belt vibration damping member 40 for preventing vibration or torsion of the belt member 20 from propagating in its peripheral surface direction is provided between a conveying start position of holding the recording sheet 30 to the belt member and the image forming means 10Bk and/or between a conveying end position of separating the recording sheet 30 from the belt member 20 and the image forming means 10C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a laser printer, an ink jet printer or the like, and more specifically, a belt-shaped photoconductor, an intermediate transfer body or a sheet conveying means. The present invention relates to an improvement in an image forming apparatus that forms a recorded image.

[0002]

2. Description of the Related Art As a conventional color electrophotographic copying machine,
For example, the one shown in FIG. 6 is known. Specifically, the recording sheet 101 is attracted to and conveyed by the belt member 100 that is stretched and rotated by a plurality of rolls, and the image forming unit 102 that forms a toner image according to image information is set to black B
The recording sheet 10 is provided for each color of k, yellow Y, magenta M, and cyan C, and these image forming means 102, 102, ... Are arranged along the conveyance path of the recording sheet 101 and are conveyed.
1 is configured to continuously transfer the toner images of the respective colors.

Further, in such an apparatus, a registration process exists before the transfer process of the toner image by the belt member, and the registration roll 103 sends the recording sheet to the conveyance start position 104 of the belt member 100 at a predetermined timing. It has become. In addition, there is a fixing step after the transfer step, and the recording sheet 101 separated from the belt member 100 at the conveyance end position 105 is sent to a fixing device 106, and the fixing device 106 forms an unfixed toner image on the recording sheet 101. Is fixed in.

[0004]

However, the distance L ₁ between the registration step and the transfer step and the distance L ₂ between the transfer step and the fixing step are set in the recording sheet 101 because of the demand for downsizing of the image forming apparatus. The reality is that it must be shorter than the length in the transport direction. Therefore, in this type of image forming apparatus, the recording sheet 101 is transported across the registration process and the transfer process, or is transported across the transfer process and the fixing process at the boundary of each process.

As a result, the registration roll 103
Due to a minute error between the peripheral speed of the belt member 100 and the peripheral speed of the belt member 100, or a minute error between the peripheral speed of the belt member 100 and the peripheral speed of the fixing roll 106, a tensile force or a compressive force in the conveying direction of the recording sheet 101 is generated. The external force acts on the belt member 100 via the recording sheet 101, and this external force hinders the faithful transfer of the toner image in the transfer process, and causes image shift, expansion, or contraction. Therefore, it is important to control the conveyance speed of the recording sheet in these three steps, and as disclosed in JP-A-2-284170, the conveyance speeds of the registration step, the transfer step and the fixing step have a tolerance range. It is strictly defined.

However, even in the direction orthogonal to the recording sheet conveying direction, a tensile force or a compressive force acts on the belt member via the recording sheet, and these external forces have a great influence on the transfer of the toner image. I knew that.
The generation of such external force is due to the fact that the traveling direction of the recording sheet is slightly different in each process. That is, as shown in FIG. 7, there are three directions: the direction A in which the belt member 100 conveys the recording sheet 101, the direction B in which the registration roll 103 conveys the recording sheet 101, and the direction C in which the fixing roll 106 conveys the recording sheet. They do not match perfectly. The cause is that there is a mounting tolerance of each component in the assembly of the apparatus, and that the tangents of the registration roll 103 and the fixing roll 106 to the recording sheet 101 are not exactly orthogonal to the conveyance direction A of the belt member 100. .

FIG. 8 shows a recording sheet for the belt member 100.
The mechanism in which an external force acts in a direction orthogonal to the transport direction of 101 is shown. Recording sheet 101 as described above
When the recording sheet 101 is conveyed over the transfer step and the fixing step, the trailing end of the recording sheet 101 is still adsorbed by the belt member 100, even though the leading end of the recording sheet 101 has entered the fixing device. At this time, the ideal conveyance direction of the recording sheet 101, that is, the recording sheet 101 when the conveyance direction A of the recording sheet 101 by the belt member 100 and the conveyance direction C of the recording sheet 101 by the fixing device 106 are completely matched. The transporting posture of is indicated by a broken line in FIG. However, in many cases, the conveyance direction A of the recording sheet 101 by the belt member 100 and the fixing device 1
Since the conveyance direction C of the recording sheet 101 by 06 does not completely match, the leading end portion of the recording sheet 101 is displaced in the axial direction of the fixing roll 106 at the time of entering the fixing device, and the recording sheet 1
The transport posture of 01 is shown by the solid line in FIG.

At this time, since the rear end of the recording sheet 101 is still adsorbed to the belt member 100, the recording sheet 101
When the leading end of the sheet plunges into the fixing device, a rotational moment or a shearing force acts on the belt member 100 with respect to the conveying surface of the recording sheet 101. This external force is quite large, and it has been clarified from the measurement results that even in the extreme case, even the support frame 107 of the roll around which the belt member 100 is stretched is distorted by this external force.

Therefore, the belt member 100 is attached to the recording sheet 101.
Of the recording sheet that is attracted to the belt member at this time because it is displaced in the direction orthogonal to the conveying direction of the recording sheet or twists on the conveying surface supporting the recording sheet 101.
The toner images could not be accurately transferred to 101, and, for example, as shown in FIG. 9, toner images 108 and 109 of two colors, which should have been supposed to be completely overlapped with each other, were sometimes transferred while being shifted from each other. Further, when a recording sheet having a large grammage is used, a larger rotational moment or shearing force acts on the belt member as compared with the case where a normal recording sheet is used, so that the problems such as the above-mentioned transfer deviation are more remarkable. . Such a shift in the transfer position of the toner image has occurred even in the conventional black-and-white machine, but in the case of a single color, it is difficult to visually pose a problem.
However, in the color image forming apparatus, the displacement of the transfer position is recognized as a serious image quality defect such as the color displacement of the toner images of the respective colors, which is an important problem that cannot be overlooked.

In the above description, the case where the recording sheet is conveyed over the transfer step and the fixing step has been described as an example. However, when the recording sheet is conveyed over the registration step and the transfer step. However, the above problem also occurs.

Further, such a problem is shown in FIGS. 10 (a) and 10 (b).
It also occurs in each image forming apparatus shown in FIG. In this image forming apparatus, the toner image formed by the image forming means 110 is primarily transferred to a belt-shaped intermediate transfer member 111 stretched around a plurality of rolls, and the toner image that is primarily transferred is further transferred to the intermediate transfer member 11.
It is configured to perform secondary transfer from 1 to the recording sheet 112. Therefore, when the recording sheet 112 is conveyed over the secondary transfer position 113 and the fixing device 114 as shown in the figure, a rotational moment or shearing force acts on the intermediate transfer member 111 at the secondary transfer position 113, and The external force is propagated to the primary transfer position 115. In continuous copying, while the secondary transfer of the toner image is performed on the recording sheet 112, the next toner image is transferred to the intermediate transfer member.
There is also a case where primary transfer is performed to 111, and in such a case, a transfer position shift of the toner image occurs at the primary transfer position 115. In particular, such a color image forming apparatus using the intermediate transfer body 111 is configured so that toner images of a plurality of colors are superposed on the intermediate transfer body 111 and primary transfer is performed, and these toner images are collectively transferred to the recording sheet 112. So
If the transfer position shift of the toner image occurs at the primary transfer position 115, the color shift still occurs in the completed recorded image.

Further, such a problem also occurs in the image forming apparatus shown in FIG. This image forming apparatus forms toner images of a plurality of colors on the latent image carrier 116,
The toner images are collectively transferred to the recording sheet 117 to form a color image on the recording sheet 117. In the figure, reference numeral 118 is a latent image writing means such as a laser light generating means, and reference numeral 119 is a developing device containing toner such as black Bk and yellow Y. In this image forming apparatus, the recording sheet 117 is moved to the transfer position 118 as shown in the figure.
And the fixing device 119, the transfer position 118
At, a rotational moment or shearing force acts on the latent image carrier 116, and these external forces are propagated to the latent image writing position 120. As a result, if the next electrostatic latent image is written while the toner image is being transferred to the recording sheet, a deviation occurs in the writing position of this latent image. The images could not be superposed exactly.

The present invention has been made in view of the above problems, and an object thereof is to transfer an image from a belt member to a recording sheet in various image forming apparatuses for forming an image using the belt member. Provided is an image forming apparatus capable of preventing an external force acting on the belt member from propagating in the circumferential surface direction of the belt member at the time of forming, thereby forming a good recorded image on a recording sheet. Especially.

[0014]

That is, the first image forming apparatus of the present invention conveys the recording sheet held by the belt member facing the image forming means, and sends the recording sheet according to the image information. Based on the image forming apparatus for forming a recorded image, a recording sheet is held between the belt member and a conveyance start position and / or a recording sheet is separated from the belt member between a conveyance end position and the image forming unit. Further, a belt damping member for preventing the vibration or twist of the belt member from propagating in the circumferential direction is provided.

In the second image forming apparatus of the present invention, the recorded image formed by the image forming means is primarily transferred to the belt member, and the recorded image is secondarily transferred from the belt member to the recording sheet again. Assuming an image forming apparatus that forms an image on the recording sheet, a belt vibration damping device that prevents the vibration or twist of the belt member from propagating in the circumferential surface direction between the primary transfer position and the secondary transfer position. It is provided with a member.

Further, in the third image forming apparatus of the present invention, the electrostatic latent image formed on the surface of the belt member is developed to form a toner image, and this is repeated to form a plurality of toner images on the belt member. Of the electrostatic latent image on the above-mentioned belt member and the above-mentioned belt member. A belt damping member is provided between the toner image transfer position and the belt member to prevent the vibration or twist of the belt member from propagating in the circumferential direction.

In such technical means, as the image forming means for forming an image on the recording sheet or the belt member, a well-known device may be appropriately selected as long as it forms a visible image based on image information. Alternatively, for example, a means for forming a toner image by an electrophotographic process and transferring the toner image onto a recording sheet or a belt member may be used, or ink may be directly ejected onto the recording sheet or the belt member to form an ink image. It may be an inkjet head that does.

As the belt member, for example, a recording sheet conveying member, an intermediate transfer member or a latent image carrier, its material, structure, etc., depending on the function required of the belt member for each image forming apparatus. The design may be changed appropriately.

[0019]

According to the above technical means, the belt damping member prevents the vibration and twist of the belt member from propagating in the circumferential surface direction. Even if an external force acts on the belt member in the vicinity of the conveyance end position and the belt member is displaced (deflected) or twisted in the direction orthogonal to the conveyance direction, this runout or twist is caused along the circumferential surface direction of the belt member. Does not propagate to the position where the image forming unit is provided.

Further, according to the second aspect of the invention, even if an external force acts on the belt member at the secondary transfer position and the belt member is displaced (deflected) or twisted in the direction orthogonal to the conveying direction, it is suppressed. Due to the function of the vibrating member, this vibration or twist does not propagate to the primary transfer position along the circumferential surface direction of the belt member.

Further, according to the third aspect of the invention, even if an external force acts on the belt member at the transfer position of the toner image and the belt member is displaced (deflected) or twisted in the direction orthogonal to the conveying direction, Due to the function of the vibration damping member, this vibration or twist does not propagate to the writing position of the electrostatic latent image along the circumferential direction of the belt member.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The image forming apparatus of the present invention will be described in detail below with reference to the accompanying drawings. First Embodiment First, FIG. 1 shows an embodiment of an image forming apparatus to which the first invention is applied. This image forming device is black,
4 corresponding to each color of yellow, magenta and cyan
Basic image forming means 10Bk, 10Y, 10M, 10C are provided, and toner images of respective colors formed by these image forming means 10Y ... are sequentially transferred onto a recording sheet 30 conveyed by a transfer conveying belt (belt member) 20 to form color images. It is configured to form an image.

Each of the image forming means 10Bk ... Arranges a charging device 12, a latent image writing means 13, a developing device 14 and a cleaner 15 around the photoconductor drum 11, and the photoconductor drum according to image information of each color. A toner image is formed on 11. Then, this toner image is electrostatically transferred to the recording sheet 30 carried on the transfer / transport belt 20 by the function of the transfer corotron 16.
In this embodiment, the latent image writing means 13 is a laser beam scanning device equipped with a laser light source, a polygon mirror, a lens, etc., and the photosensitive image is transferred in response to an image signal transmitted from an image processing unit (not shown). The surface of the body drum 11 is exposed.

On the other hand, the transfer / transport belt 20 has a thickness of 0.1 mm.
It is made of PET film and is wound around a driving roller 21, a driven roller 22, a peeling roller 23 and the like. The drive roller 21 is connected to a motor (not shown) and rotates the transfer / conveyance belt in the direction of arrow A. In addition, the driven roller 22
Is biased and supported so that the transfer / transport belt 20 is stretched with a constant tension. The transfer / transport belt 20 is not always PET.
It does not need to be formed of a film, and any material having a resistance value that satisfies the transfer condition of a toner image can be appropriately used. Further, the thickness of the transfer / conveying belt at that time may be in a range that causes no practical problem (for example, about 0.05 mm to 0.15 mm).

Recording sheet 30 by this transfer belt 20
The suction roll 24 is disposed at the transport start position of the recording sheet 30 and the recording sheet 30 enters between the suction roll 24 and the transport transfer belt 20. Further, an adsorbing corotron 25 is disposed at a position facing the adsorbing roll 24 with the transport transfer belt 20 interposed therebetween, and the recording sheet 30 is discharged by the electric discharge of the adsorbing corotron 25.
Is electrostatically attracted to the transfer transfer belt 20. Meanwhile, recording sheet
At the transport end position of 30, the transport transfer belt 20 is stretched around a small-diameter peeling roll 26, and the recording sheet 30 transported to this position is peeled from the transport transfer belt 20 due to the strength of its own waist.

Also, in this embodiment, the recording sheet 30
A belt damping roll (belt damping member) 40 is arranged between the conveyance end position (that is, the disposition position of the peeling roll 23) and the transfer position of the cyan toner image by the image forming unit 10C. The belt member 20 is wound around the belt damping roll 40 at a predetermined wrap angle (about 5 ° to 90 °), and is pressed against the belt damping roll by the tension given by the driven roll. Therefore, even if an external force is applied to the belt member on the conveyance end position side with respect to the belt damping roll in a direction orthogonal to the conveyance direction of the recording sheet (perpendicular to the paper surface), the belt member and the belt damping roll are The external force is canceled by the frictional force of.

In the color image forming apparatus of the present embodiment constructed as described above, the color image is formed as follows. First, the color image signal sent to the image processing unit is black Bk, yellow in the image processing unit.
After being converted into image signals of respective colors of Y, magenta M and cyan C, they are stored in the internal memory of the image processing unit. The image signals of the respective colors accumulated in the image processing section are sequentially transferred to the laser beam scanning device 13 of the corresponding image forming means 10Bk, and the laser beam scanning device 13 exposes the photosensitive drum 11 based on this image signal. To form an electrostatic latent image. Further, in each of the image forming means 10Bk ..., the developing device 14 develops the electrostatic latent image, and a toner image corresponding to the image signal of each color is formed on each photoconductor drum 11.

On the other hand, the recording sheet 30 on which these four color toner images are transferred is carried out from a supply tray (not shown), and is registered by the registration roller 31 in a predetermined manner in synchronization with the image writing timing in each image forming means 10Bk. It is sent between the suction roll and the transfer transfer belt 20 at the timing,
The transfer belt 20 is electrostatically attracted.

Recording sheet adsorbed on the transfer / transport belt 20
First, 30 passes through the black image forming means 10Bk, and the black toner image is transferred to the recording sheet 30 at the contact position with the photosensitive drum 11. Next, the recording sheet 30 passes through the yellow image forming means 10Y, and the yellow toner image is transferred onto the recording sheet 30 so as to be superimposed on the black toner image. After that, the recording sheet 30 passes through the magenta and cyan image forming means 10M and 10C, and the magenta and cyan toner images are sequentially transferred onto the recording sheet 30 in a multiplex manner. When the transfer of the cyan toner image is completed, the recording sheet 30 moves to the belt member 20 up to the conveyance end position where the peeling roll 23 is arranged.
The belt member 20 is conveyed to the belt member 20 at the end position of this conveyance.
It is peeled off and rushes into the fixing device 32.

At this time, the leading end of the recording sheet 30 is fixed to the fixing device 32.
When the belt member 20 conveys the recording sheet 30 and the fixing device 32 do not completely coincide with each other,
An external force acts on the belt member 20 via the recording sheet 30 in a direction orthogonal to the conveyance direction of the recording sheet 30. However, as described above, since this external force is canceled by the frictional force between the belt member 30 and the belt damping roll 40, the vibration or twist of the belt member 20 generated at the position where the external force acts is not detected by the belt damping roll. 40 is absorbed, and these shakes and twists do not propagate to the transfer position of the toner image by each image forming unit 10Bk, ....

Therefore, according to the image forming apparatus of this embodiment, it is possible to effectively prevent the transfer position shift of the toner image in each image forming means and form a good color image without color shift. You can

In the above embodiment shown in FIG. 1, the recording sheet 2
Although the belt damping roll 40 is provided only on the side of the conveyance end position of 0, as described above, the external force that causes the belt member 20 to shake or twist is also applied to the belt member 20 even on the side of the conveyance start position of the recording sheet 30. Therefore, preferably, as shown in FIG. 3, the belt damping roll 40 is also arranged between the conveyance start position (that is, the position where the suction roll 24 is disposed) and the transfer position of the black toner image by the image forming unit 10Bk. It is good to set up.

Further, the belt damping roll 40 of the above embodiment
Can be replaced with a belt damping plate 41 as shown in FIG. 2, for example. In this case, the belt damping plate 41 may have any shape, but it is necessary that the belt member 20 can be laid around at a predetermined wrap angle and that the sliding resistance with the belt member 20 is small. Is.

Second Embodiment Next, FIG. 4 shows an embodiment of an image forming apparatus corresponding to the second invention. The image forming apparatus includes an image forming unit.
The toner image formed by 50 is primarily transferred to the belt-shaped intermediate transfer body 60, and the unfixed toner image is secondarily transferred from the intermediate transfer body 60 to the recording sheet 70 to form a desired image on the recording sheet 70. Is configured.

Similar to the above embodiment, the image forming means 50
Is a charger 52 around the photosensitive drum 51 and a latent image writing means.
53, a developing unit 54, and a cleaner 55 are arranged, and a toner image is formed on the photosensitive drum 51 according to image information sent from an image processing unit (not shown). The developing device 54 is a rotary type in which four developing devices corresponding to each color of black, yellow, magenta, and cyan are radially arranged, and the developing of the optimum color for the image information supplied to the latent image writing means 53 is performed. The container is set at the developing position facing the photosensitive drum 51.

On the other hand, the intermediate transfer member is wound around a drive roll 61, a primary transfer roll 62 and a secondary transfer roll 63, and rotates in the direction of arrow B as the drive roll 61 rotates.
The primary transfer roll 62 and the secondary transfer roll 63 are bias rolls, and when a voltage having a polarity opposite to the charging polarity of the toner is applied to these rolls 62 and 63, the toner image on the photosensitive drum 51 is transferred to the intermediate transfer body 60. Primary transfer, intermediate transfer 60
The upper toner image is secondarily transferred to the recording sheet 70.

Further, in this embodiment, a belt is provided between the secondary transfer position of the toner image (that is, the disposition position of the secondary transfer roll 63) and the primary transfer position (that is, the disposition position of the primary transfer roll 62). A damping roll (belt damping member) 64 is provided, and the intermediate transfer body 60 is also stretched around the belt damping roll 64 at a predetermined wrap angle (about 5 ° to 90 °).

When a single color image is formed in this image forming apparatus, the toner image primarily transferred to the intermediate transfer member 60 is immediately secondarily transferred to the recording sheet 70. However, toner images of a plurality of colors are superposed. When forming a color image, the steps of forming a toner image on the photosensitive drum 51 and primary transferring the toner image are repeated for the number of colors. For example, when forming a full-color image in which toner images of four colors are superimposed, black, yellow, magenta, and cyan toner images are formed on the photosensitive drum 51 for each rotation, and these toner images are sequentially transferred by intermediate transfer. It is primarily transcribed on body 60. On the other hand, the intermediate transfer body 60 rotates in the same cycle as the photosensitive drum 51 while holding the black toner image that was primarily transferred first, and on the intermediate transfer body 60, yellow, magenta, and cyan are rotated for each rotation. Toner image is transferred over the black toner image. Then, the toner images thus multi-transferred on the intermediate transfer body 60 are collectively transferred to the recording sheet 70 at the secondary transfer position, and then the recording sheet 70 is transferred.
70 enters the fixing device 65.

At this time, the leading edge of the recording sheet 70 is fixed to the fixing device 65.
When the recording sheet 70 enters the secondary transfer position, the conveyance direction of the recording sheet 70 at the secondary transfer position and that of the fixing device 65 do not completely coincide with each other.
An external force acts in a direction orthogonal to the conveyance direction of. But,
In this embodiment, since the belt damping roll 64 is arranged between the secondary transfer position and the primary transfer position, the vibration or twist of the belt member 20 generated at the position where the external force is applied causes the belt damping roll 40 to move. Are absorbed by these components, and these shakes and twists do not propagate from the secondary transfer position to the primary transfer position.

Therefore, according to the image forming apparatus of this embodiment, it is possible to effectively prevent the transfer position shift of the toner image at the primary transfer position and form a good color image without color shift. it can.

Third Embodiment Next, FIG. 5 shows an embodiment of the image forming apparatus according to the third invention. This image forming apparatus is configured to form a plurality of toner images on the surface of the belt-shaped photosensitive member 81 in a superimposed manner and transfer the stacked toner images to the recording sheet 80 at one time to obtain a color image.

A charging device 82, a latent image writing means 83, a developing device 84 and a cleaner 85 are arranged around the belt-shaped photosensitive member 81, and are arranged in accordance with image information sent from an image processing section (not shown). A toner image is formed on the photosensitive drum 51. As the developing device 84, four developing devices corresponding to each color of black Bk, yellow Y, magenta M, and cyan C are arranged in parallel, and the optimum color for the image information supplied to the latent image writing means 83. Developing device develops the electrostatic latent image written on the photoconductor 81.

On the other hand, the belt-shaped photosensitive member 81 is a drive roll.
It is wound around 86, a bias roll 87, and a driven roll 88, and rotates in the direction of arrow D as the drive roll 86 rotates. Further, between the position where the toner image on the photoconductor 81 is transferred to the recording sheet 80 (that is, the position where the bias roll 87 is arranged) and the electrostatic latent image writing position (that is, the position where the latent image writing means 83 is arranged). Belt damping roll (belt damping member) 9
0 is provided, and the photoconductor 81 also has a predetermined wrap angle (5 ° to 9 °).
It is wound around this belt damping roll 90 at about 0 °.

In the image forming apparatus of this embodiment having the above-described structure, the black toner image, the yellow toner image, the magenta toner image, and the cyan toner image are formed on the surface of the photoconductor 81 every one rotation of the belt-shaped photoconductor 81. Are sequentially formed on the photoconductor
On the surface of 81, a synthetic toner image in which toner images of respective colors are stacked is formed. When the development of the cyan toner image is completed, a voltage having a polarity opposite to the charging polarity of the toner is applied to the bias roll 87, and the synthetic toner image is recorded on the recording sheet.
The recording sheet 80 is transferred to the fixing unit 92.

At this time, the leading end of the recording sheet 80 is fixed to the fixing device 92.
When the sheet is rushed into, the conveyance direction of the recording sheet 80 at the transfer position and that of the fixing device 92 do not completely coincide with each other.
An external force acts in a direction orthogonal to the conveyance direction of. But,
In this embodiment, since the belt damping roll 90 is disposed between the transfer position and the electrostatic latent image writing position, the belt-shaped photosensitive member 81 is shaken or twisted at the position where the external force acts. It is absorbed by the vibration suppression roll 90, and these shakes and twists do not propagate from the transfer position to the electrostatic latent image writing position.

Therefore, according to the image forming apparatus of the present embodiment, it is possible to effectively prevent the writing position of the electrostatic latent image on the photoconductor 81 from being deviated, and a plurality of photoconductors 81 are formed on the surface of the photoconductor 81. Even when the color toner images are superposed, it is possible to form a good color image without color misregistration.

[0047]

As described above, according to the image forming apparatus of the present invention, the belt damping member prevents the vibration and twist of the belt member from propagating in the circumferential direction. In that case, it is possible to effectively prevent the formation position deviation of the recorded image on the recording sheet, and particularly when forming the color image by superposing the recorded images of a plurality of colors on the recording sheet, the image quality is deteriorated due to the color deviation. And a good color image can be formed.

Further, in the second invention, it is possible to effectively prevent the formation position deviation of the recorded image with respect to the intermediate transfer body at the primary transfer position, and particularly to superpose the recorded images of a plurality of colors on the intermediate transfer body. When forming a color image, it is possible to prevent deterioration of image quality due to color misregistration and form a good color image.

Further, according to the third aspect of the present invention, it is possible to effectively prevent the writing position deviation of the electrostatic latent image on the belt-shaped latent image carrier, and especially toner images of a plurality of colors are formed on the latent image carrier. When forming a color image by superimposing, it is possible to prevent deterioration of image quality due to color shift and form a good color image.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of main parts showing a modified example of the image forming apparatus according to the first embodiment.

FIG. 3 is an enlarged view of main parts showing a modified example of the image forming apparatus according to the first embodiment.

FIG. 4 is a schematic view showing an image forming apparatus according to a second embodiment of the present invention.

FIG. 5 is a schematic view showing an image forming apparatus according to a third embodiment of the present invention.

FIG. 6 is a schematic front view showing an example of a conventional image forming apparatus.

FIG. 7 is a schematic plan view of the conventional image forming apparatus shown in FIG.

FIG. 8 is a diagram illustrating a conveyance state of a recording sheet in the conventional image forming apparatus illustrated in FIG.

FIG. 9 is a diagram illustrating a problem of an image recorded by the conventional image forming apparatus shown in FIG.

FIG. 10 is a schematic view showing another example of a conventional image forming apparatus.

FIG. 11 is a schematic view showing another example of a conventional image forming apparatus.

[Explanation of symbols]

10Bk, 10Y, 10M, 10C ... Image forming means, 20 ... Conveying transfer belt
(Belt member), 30 ... Recording sheet, 40 ... Belt damping roll
(Belt damping member)

Claims (3)

[Claims] 1. An image forming apparatus which conveys a recording sheet held on a belt member toward an image forming means and forms a recorded image according to image information on the recording sheet, wherein the recording sheet is the belt member. Between the conveyance start position held at and / or the conveyance end position where the recording sheet is peeled from the belt member and the image forming means, and the propagation of the shake or twist of the belt member in the circumferential direction is prevented. An image forming apparatus comprising: 2. An image forming method in which a recorded image formed by an image forming unit is primarily transferred to a belt member, and the recorded image is secondarily transferred from the belt member to a recording sheet to form an image on the recording sheet. In the image forming apparatus, a belt damping member is provided between the primary transfer position and the secondary transfer position to prevent the vibration or twist of the belt member from propagating in the circumferential direction. . 3. A toner image is formed by developing an electrostatic latent image formed on the surface of a belt member, and the toner image is repeated to form a plurality of toner images on the belt member. In an image forming apparatus for collectively transferring an image to a recording sheet to form a recorded image on the recording sheet, the belt is provided between a writing position of the electrostatic latent image on the belt member and a transfer position of the toner image. An image forming apparatus comprising a belt damping member for preventing the vibration or twist of the member from propagating in the circumferential direction.