JPH0635261A - Image forming device - Google Patents

Abstract

(57) [Abstract] [Purpose] To increase the utilization rate of the recording material carrying means in the case of continuously passing the recording material on the endless recording material carrying means having a joint portion. [Structure] Recording material carrying belt 31 of A4 size recording material P
The length of the moving direction is 1, the distance between recording materials during continuous paper feeding is a,
When the natural number is n, the total circumferential length L of the recording material carrying belt 31 is determined so that L = n (l + a). now,
L = 81 when l = 210 mm, a = 60 mm, and n = 3
If 0 mm is determined, as shown in FIG. 1A, for example, if the first recording material P1 is supplied to the belt 31 from a position 40 mm away from the seam portion 31a of the belt 31, FIG.
2nd, 3rd ... recording material P2,
By supplying P3 ... At a distance of 60 mm from the trailing edge of the first recording material P1, these recording materials P2, P3 ...
Is not positioned on the joint portion 31a of the belt 31, and the utilization rate K of the belt 31 is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic system in which a visible image is formed on an image carrier and the visible image is transferred onto a recording material (recording medium) carried by a recording material carrying means.
With respect to an image forming apparatus such as an electrostatic recording method, but not limited to, for example, a plurality of image forming means are provided, and these image forming means form a plurality of visible images of different colors on an image carrier. The present invention is suitable for a color image forming apparatus such as a color copying machine or a color printer in which a visible image is sequentially transferred onto the same recording material carried and conveyed by a recording material carrying means.

[0002]

2. Description of the Related Art Conventionally, a plurality of image forming units are provided, and each image forming unit has a visible image (toner image) of a different color.
Various image forming apparatuses that form a toner image and sequentially transfer these toner images onto the same recording material, so-called color image forming apparatuses, have been proposed. Among them, electrophotographic color images are often used. It is a forming device. Such an electrophotographic color image forming apparatus includes a plurality of image forming units,
Generally, four image forming units are arranged side by side, and dedicated photoconductor drums are used as image bearing members of these image forming units.
A visible image of black, yellow, magenta, and cyan, that is, a toner image is separately formed on each photoconductor drum, and is sequentially formed on a recording material that is carried and conveyed by a recording material carrying means such as a dielectric belt. The toner images of the respective colors are superposed on each other, and the multiple toner images on the recording material are collectively heat-fixed by a fixing device to obtain a desired full-color image or multi-color image.

An example of such an electrophotographic color image forming apparatus, a color copying machine in this example, will be briefly described with reference to FIG. This color copying machine is capable of forming, for example, visible images (toner images) of black, yellow, magenta, and cyan in the main body of the apparatus.
-The fourth four image forming portions Pa, Pb, Pc and Pd are arranged linearly and each image forming portion Pa-P is arranged.
d is a dedicated photosensitive drum 1a, 1b as an image carrier,
1c and 1d, respectively, and each photosensitive drum 1a-1
Around the d, there are dedicated image forming process means, for example, latent image forming sections 2a, 2b, 2c, 2d, developing sections 3a, 3b, 3c, 3d, and cleaning sections 5a, 5a.
b, 5c, 5d, etc. are provided.

On the other hand, under the photosensitive drums 1a to 1d of the image forming sections Pa to Pd, an endlessly moving recording material carrying belt 8 is arranged in a stretched state between a pair of rollers 10 and 11. Inside the transfer parts 4a, 4b, 4c, 4d
Further, a sheet feeding device including a recording material cassette 60 for storing the recording material 6 is arranged on the right side of the recording material carrying belt 8 in the drawing. Further, a registration roller pair 13 for feeding the recording material 6 at a timing is arranged between the paper feeding device and the recording material carrying belt 8,
The recording material 6 is held on a recording material carrying belt 8 from a paper feeding device via a pair of registration rollers 13 and is sequentially conveyed to the image forming portions Pa to Pd as the belt 8 moves.

In the above structure, first, the recording material 6 delivered from the recording material cassette 60 is temporarily stopped when its front end is slightly sandwiched by the pair of registration rollers 13, and the recording material 6 of the first image forming portion Pa is stopped. It is sent out at the same timing as the image forming process, and is fed onto the recording material carrying belt 8. In the first image forming portion Pa, the photosensitive drum 1 uniformly charged by the latent image forming portion 2a.
Image information of the black component color in the original image is scanned with respect to a by a laser beam or the like to form an electrostatic latent image of the black component color. Black toner is attached to the electrostatic latent image at the developing unit 3a to form a black visible image.

On the other hand, the recording material 6 is carried on the recording material carrying belt 8 and conveyed, and in the transfer area below the photosensitive drum 1a of the first image forming portion Pa, the operation of the transfer charging means of the transfer portion 4a is performed. As a result, the black visible image formed on the photosensitive drum 1a, that is, the toner image is transferred onto the recording material 6. While the black toner image is transferred onto the recording material 6 in this way, an electrostatic latent image of a yellow component color is formed in the second image forming portion Pb, and this electrostatic latent image is developed.
To form a yellow toner image, and when the recording material 6 is conveyed to the transfer area below the photosensitive drum 1b of the second image forming portion Pb, the yellow toner image moves to the transfer area,
By the action of the transfer charging means of the transfer portion 4b, the black toner image on the recording material 6 is transferred in an overlapping state.

Hereinafter, the third and fourth image forming portions Pc and Pd will be described.
In the same manner as in the first and second image forming portions Pa and Pb, toner images of magenta color and cyan color are sequentially formed, and these are sequentially formed on the recording material 6 conveyed by the recording material carrying belt 8. Toner images are multi-transferred.

When the image forming process is completed, the recording material 6 is separated from the recording material carrying belt 8 and fixed to the fixing device 7.
Then, the desired full-color image is obtained by batch fixing. Further, the residual toner is removed from the photosensitive drums 1a to 1d of the image forming portions Pa to Pd after the transfer is completed by the cleaning portions 5a to 5d to prepare for the subsequent latent image formation.

The recording material carrying belt 8 is a film sheet made of a dielectric resin such as polyethylene terephthalate resin or polyvinylidene fluoride resin. Both ends thereof are superposed and joined to each other to form an endless shape (endless shape). It has a seam portion 8a. Since the seam portion 8a is different in characteristics from the surroundings, there is a disadvantage that when the image is transferred onto the recording material 6 via the seam portion 8a, the transfer is not sufficiently performed and an image defect occurs. Therefore, when the recording material 6 is held by the recording material carrying belt 8, the recording material 6 is supplied to the recording material carrying belt 8 so as to avoid the joint portion 8a of the carrying belt 8.

[0010]

However, when the recording material 6 is continuously supplied to the recording material supporting belt 8 to form an image (hereinafter, referred to as a continuous mode), it depends on the length of the recording material supporting belt 8. Causes the following problems.

According to the results of the investigations and studies conducted by the present inventors, it is found that the apparatus user most frequently forms an image on A4 size.
It has been found to be of size (297 x 210 mm). Therefore, for example, the entire circumference of the recording material carrying belt 8 is set to 10
If the length in the moving direction of the recording material carrying belt 8 of the A4 size recording material 6 is set to 210 mm, it is shown in FIG.
As shown in (a), the seam portion 8 a of the recording material carrying belt 8
To avoid this, for example, the first recording material 61 is fed from a position 40 mm away from the seam portion 8a, and the next recording material 6 is supplied.
As shown in FIG. 6B, when 2 is continuously supplied with a predetermined paper distance, for example 60 mm, from the rear end of the first recording material 61, the first recording material 61 is included. When the fourth recording material 64 is supplied to the recording material supporting belt 8 as shown in FIG. 6C, the fourth recording material 64 is positioned on the joint portion 8 a of the recording material supporting belt 8. Inconvenience that it is held in.

Therefore, like the first recording material 61, the fourth recording material 64 must be supplied to the recording material carrying belt 8 from a position 40 mm away from the seam portion 8a, and the recording material carrying belt 8 must be supplied. The utilization rate K is K = 210 × (3/1000) × 100 = 63.0%, which is inefficient, and when images are formed in the continuous mode, the number of copies per hour is greatly reduced. There was an inconvenience that it would end up.

However, this problem does not become so great except for the A4 size recording material. That is, 1000
A3 size for the recording material carrying belt 8 having a circumference of mm (the size in the moving direction of the recording material carrying belt 8 is 420 mm)
In the case of supplying the recording material of No. 2, even if the two recording materials 61 and 62 are supplied over the circumference of the recording material supporting belt 8 as shown in FIG. 7, the second recording material 62 carries the recording material. The belt 8 is not located on the joint portion 8a, and a sufficient paper distance (about 80 mm in this case) can be secured.

Utilization rate K of the recording material carrying belt 8 in this case
Becomes K = (420 × 2/1000) × 100 = 84.0%, which is considerably higher than that in the case of A4 size, so that the inconvenience as in the case of A4 size hardly occurs.

Therefore, an object of the present invention is to hold a recording material on an endless recording material carrying means having a joint portion and to form a visible image of a plurality of colors on the recording material by a plurality of image forming means. An object of the present invention is to provide an image forming apparatus capable of increasing the utilization rate of the recording material carrying means during continuous sheet feeding, even when transferring sheets.

[0016]

The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention is, in a first aspect, an image forming unit having an image carrier and a unit for forming a visible image on the image carrier,
A recording material holding means for carrying a recording material, which is formed in an endless shape having a seam portion and on which a visible image formed by the image forming means is transferred, and is conveyed to a transfer position of the image forming means, and the transfer position. And a transfer means for transferring a visible image on the image carrier to the recording material, the recording material carried by the recording material carrying means being conveyed to a transfer position of a plurality of image forming means. In an image forming apparatus capable of forming a multicolor image thereon and using recording materials of at least a plurality of sizes, a movement of the recording material holding means for one size of the usable recording materials When the length in the direction is 1, the proper inter-recording material distance when continuously passing the recording material is a, and the natural number is n, the total circumferential length L of the recording material holding means is L = n (l + a ) Image formation characterized by It is the location.

In a second aspect, the present invention provides
Recording in which an image forming unit having an image carrier and a unit for forming a visible image on the image carrier, and an endless shape having a joint portion, to which the visible image formed by the image forming unit is transferred A recording material carrying means for carrying a material and conveying it to a transfer position of the image forming means; and a transfer means for transferring a visible image on the image carrier to the recording material at the transfer position. Image formation capable of using a recording material supported by a material supporting means to transfer positions of a plurality of image forming means to form a multicolor image on the recording material and using recording materials of at least a plurality of sizes In the apparatus, among the usable recording materials, the length of the recording material carrying means of one size of the recording material in the moving direction is l, and the appropriate distance between the recording materials when continuously passing the recording material is a, Natural number n
And the total circumferential length L of the recording material carrying means is L =
The image forming apparatus is characterized in that it is 2n (l + a).

[0018]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the following examples, the case where the present invention is applied to a color image forming apparatus of an electrophotographic system will be described. However, the present invention is an image of various configurations such as an electrophotographic system and an electrostatic recording system other than the examples. It is equally applicable to forming devices.

First, a first embodiment of the present invention will be described with reference to FIG.
~ It demonstrates with reference to FIG.

FIG. 3 shows the overall construction of an electrophotographic color image forming apparatus to which the present invention is applied. The color image forming apparatus is provided with a first, a second, a third and a fourth in a main body of the apparatus.
Four image forming sections Pa, Pb, Pc and Pd
Further, a sheet feeding unit is provided on one side thereof, that is, the right side in FIG. 3, and a fixing device 30 is provided on the opposite side, that is, the left side in FIG. Further, below the path from the paper feeding section to the fixing device 30 in the apparatus main body, an endless recording material carrying means for carrying and carrying a recording material, for example, a recording material carrying belt 31.
Are stretched between a plurality of rollers in a known manner. The recording material carrying belt 31 is driven in the direction shown by the arrow in FIG. 3 to carry the recording material P fed through the paper feeding section,
The image forming units Pa, Pb, Pc and Pd are sequentially conveyed.

The image forming portions Pa, Pb, Pc, and Pd have substantially the same structure, and the photosensitive drum 21a, which is an image bearing member, which is normally driven to rotate in the direction of the arrow in the drawing,
Image forming means are provided around the respective photosensitive drums including 21b, 21c and 21d. These image forming means may be arbitrary means, but in this example, the primary chargers 22a, 22b, 2 for uniformly charging the photosensitive drums are used.
2c and 22d, developing devices 24a, 24b, 24c and 24d for developing the electrostatic latent image formed on the photosensitive drum,
Transfer chargers 27a, 27b, 27c and 27d for transferring the developed visible image (toner image) to the recording material P, a cleaner 28a for removing the toner remaining on the photosensitive drum,
28b, 28c and 28d are sequentially arranged in the drum rotation direction. In addition, the photosensitive drums 21a, 21b, 2
Image exposure devices 23a and 23b are provided above 1c and 21d.
23c and 23d are provided.

The developing device 24a contains black toner and the developing device 24b contains yellow toner.
4c contains magenta toner, and the developing device 24d contains cyan toner. The image exposure devices 23a, 23b, 23c and 23d are, in this example, a semiconductor laser, a polygon mirror, an fθ lens, etc.
The primary charger 22 receives the laser beam L modulated by the input of the electric digital pixel signal in response to this signal.
a, 22b, 22c and 22d and developing devices 24a and 24
b, 24c and 24d are scanned in the photoconductor drum generatrix direction to expose the drum surface, and the photoconductor drums 21a to 21c are exposed.
An electrostatic latent image is formed on d. The image exposure device 23a receives a pixel signal corresponding to a black component image of a color image, the image exposure device 23b receives a pixel signal of a yellow component image, and the image exposure device 23c receives a pixel signal of a magenta component image. Then, the pixel signals corresponding to the cyan component image are input to the image exposure device 23d.
Further, an appropriate recording material suction means (not shown) is installed between the first image forming portion Pa and the paper feeding portion, and the recording material P supplied from the paper feeding portion is transferred to the recording material carrying belt 31. Make sure it is adsorbed. On the other hand, a charge eliminating charger 29 is provided between the fourth image forming portion Pd and the fixing device 30, and the charge eliminating charger 29 is attached to the recording material carrying belt 31. An alternating voltage is applied to separate the two.

The recording material carrying belt 31 is made of polyurethane resin, PVdF (polyvinylidene fluoride) resin, PET.
The end portions of a film sheet made of a dielectric resin such as (polyethylene terephthalate) resin, polycarbonate resin, or polyether sulfone resin are endlessly joined by means such as ultrasonic welding, and the driving rollers 32 at both ends are 32 drives endlessly at a constant speed (for example, 100 mm / s) in the direction of the arrow in FIG. The intermediate roller 33 is a tension roller for adjusting the tension of the belt 31.

Further, the paper feeding section has two paper feeding cassettes 34 and 35 for accommodating recording materials P having different sizes, a paper feeding roller 36 for feeding the recording materials P one by one from these paper feeding cassettes, And a registration roller 37 for feeding the recording material P onto the recording material carrying belt 31 at a predetermined timing.
It consists of and.

In the color image forming apparatus having the above structure,
When the recording material P is fed by the paper feed guide and is fed onto the recording material carrying belt 31, the recording material P is electrostatically placed on the recording material carrying belt 31 by the action of the recording material suction means in this example. Is surely adsorbed on. FIG. 3 of the recording material carrying belt 31
Along with the movement in the arrow direction, a black visible image is formed on the photosensitive drum 21a of the first image forming portion Pa,
The visible image of yellow color is formed on the photoconductor drum 21b of the image forming portion Pb of the second photoconductor drum 2b of the third image forming portion Pc.
A magenta visible image is formed on 1c, and a cyan visible image is formed on the photosensitive drum 21d of the fourth image forming portion Pd. These visible images are
By moving the recording material carrying belt 31, the recording material P is
Photoreceptor drums 21a-2 of the fourth image forming portions Pa-Pd
The transfer chargers 27a, 27 of the respective image forming portions are sequentially transferred to the fixing device 30 by sequentially passing the lower part of 1d.
b, 27c and 27d are sequentially transferred onto the recording material P so that a color image is synthesized. The recording material P is the fourth
After passing through the image forming portion Pd, the charge is removed by the charge removing charger 29 to which an AC voltage is applied and separated from the recording material carrying belt 31. The recording material P separated from the recording material carrying belt 31 is sent to the fixing device 30.
After the multiple composite image transferred inside is fixed, it is discharged from the recording material discharge port onto the discharge tray 38, and thus one copy cycle is completed.

As shown in FIG. 1, the recording material carrying belt 31 has a joint portion 31a. As described above, when the recording material P is positioned on the joint portion 31a, the recording material P is transferred to the recording material P. Inconvenience occurs in the transfer of the toner image. For this reason,
When the recording material P is supplied to the recording material carrying belt 31, it is necessary to supply the recording material P so that the recording material P is not positioned on the joint portion 31a.

In this case, if the entire circumference of the recording material carrying belt 31 is arbitrarily determined, particularly in the case where an image is formed on the recording material P of a size which is frequently used by the user of the apparatus, it will be described in the section of the prior art. As described above, when the recording material P is continuously supplied to the recording material carrying belt 31 to form an image, the recording material P is placed at an appropriate distance between the recording materials.
The inconvenience of not being able to supply above occurs.

Therefore, in this embodiment, as described above, the recording material carrying belt 31 of the recording material P of the A4 size recording material P, which is the most frequently used size by the user of the apparatus, has been found out by the study of the present inventors. When the length in the moving direction is 1, the distance between recording materials when continuously fed is a, and the natural number is n,
The total circumferential length L of the recording material carrying belt 31 is determined so that L = n (l + a) so that the above-mentioned inconvenience does not occur. In this case, the inter-recording material distance a needs to be at least 50 mm or more so that a jam or the like does not occur.

Therefore, according to this embodiment, l = 210 m
If m = a = 60 mm and n = 3, and L = 810 mm is determined, as shown in FIG.
In order to avoid the one seam portion 31a, for example, the seam portion 31a
When the first recording material P1 is supplied from the position 40 mm away from the recording material carrying belt 31, as shown in FIG. 1 (b), the subsequent second, third, ... Recording materials P2, P
By supplying the recording materials P3, ... At a distance of 60 mm from the trailing edge of the first recording material P1, these recording materials P2, P3,
... are not positioned on the joint portion 31a of the recording material carrying belt 31.

Therefore, the recording material carrying belt 31 in this case
The utilization rate K of the recording material P is K = (210 × 3/810) × 100≈77.8%, and the recording material carrying belt 31 can be effectively used, and the recording material P per hour is also obtained in the continuous mode.
It is possible to increase the number of image formations, that is, the number of copies.

Further, by improving the utilization factor K of the recording material carrying belt 31, the image forming speed in the image forming portions Pa to Pd including the rotational speed of the recording material carrying belt 31 can be made small, and the apparatus Miniaturization and cost reduction can be achieved.

Further, the recording material carrying belt 31 of the present embodiment.
In addition to the A4 size recording material, the distance a between recording materials is set to 5 in the continuous mode not only for the letter size (8.5 × 11 inch) recording material which is often used in the US etc.
By setting the thickness to 4.0 mm, the utilization factor K of the recording material carrying belt 31 can be kept sufficiently high.

Next, a second embodiment of the present invention will be described.

As a result of further research conducted by the present inventors, when determining the circumference of the recording material carrying belt, the recording material P
When the length of the recording material carrying belt in the moving direction is 1, the distance between the recording materials when continuously fed is a, and the natural number is n, the total circumferential length L of the recording material carrying belt 31 is L It was found that even more preferable results can be obtained when the determination is made so that = 2n (l + a).

Therefore, according to this embodiment, l = 210 m
When m = a = 60 mm and n = 2 and L = 1080 mm is determined, the utilization factor K of the recording material carrying belt 31 when the recording material P of A4 size is used is K = (210 × 4/1080) × 100 ≅77.8%, which is completely the same as that of the first embodiment described above.

On the other hand, when the recording material P of A3 size is used, L = 810 mm in the first embodiment, and therefore the recording material distance a must be set to 390 mm. The utilization factor K of the recording material carrying belt 31 was as low as K = (420/810) × 100≈51.9%, but in this embodiment L = 1080 mm, so if the distance a between recording materials is 120 mm. As shown in FIG. 2, two recording materials of A3 size can be used per one revolution of the recording material carrying belt 31. Therefore, the utilization factor K of the recording material supporting belt 31 in this case is K = (420 × 2/1080) × 100≈77.8%, which is the same as the utilization efficiency of the recording material of A4 size and A3. The preferable results were obtained such that the recording material carrying belt 31 can be effectively used for a recording material of a size and the number of images formed on the recording material P per time can be increased.

Next, a third embodiment of the present invention will be described with reference to FIG.
Will be described with reference to. In FIG. 4, parts and members having the same functions as those of the color image forming apparatus of FIG. 3 are designated by the same reference numerals and the description thereof will be omitted unless necessary.

FIG. 4 schematically shows the structure of the main part of an electrophotographic color image forming apparatus according to the third embodiment of the present invention. The recording material carrying means has a cylindrical shape instead of an endless belt. Of the transfer drum 40, and the four image forming portions Pa, Pb, Pc of the first, second, third and fourth of black, yellow, magenta and cyan described above are provided along the outer periphery of the transfer drum 40. It has a configuration in which Pd is sequentially arranged. A film sheet 41 made of a dielectric resin similar to that of the first and second embodiments is wound around the transfer drum 40 as a recording material carrier in a drum shape, and both end portions of the film sheet 41 are formed. Are joined endlessly by means such as ultrasonic welding, and thus have a seam portion 41a. A paper feed cassette 34, a paper feed roller 36, a registration roller 37, a suction charger 42, and a suction auxiliary roller 43 are provided on the paper feed side of the transfer drum 40. On the side, a charge removing charger 29, a separating claw 44, and a fixing device 30 are provided, respectively.

The operation of the color image forming apparatus will be briefly described.
The recording material P supplied to the transfer drum 40 side via the registration roller 37 is electrostatically adsorbed and held on the outer peripheral surface of the transfer drum 40 via the adsorption auxiliary roller 43 while being charged by the adsorption charger 42. Then, as the transfer drum 40 rotates, the image forming portions Pa, Pb, and P are formed on the recording material P.
The black, yellow, magenta, and cyan toner images are multi-transferred on c and Pd, and when the transfer of the toner images is completed, the recording material P is discharged by the discharging charger 29 while being separated by the separation claw 44. It is separated from the transfer drum 40 and sent to the fixing device 30.

As described above, on the outer peripheral portion of the transfer drum 40, the film sheet 41 made of the same dielectric resin as the recording material carrying belt 31 of the first and second embodiments.
Is wound endlessly with the seam portion 41a, and the recording material P is conveyed while being sucked and held on the film sheet 41. Therefore, it is necessary to supply the recording material P onto the transfer drum 40 so that the recording material P is not positioned on the joint portion 41a of the film sheet 41.

Therefore, also in this embodiment, as in the case of the first embodiment, the length of the transfer material 40 of the recording material P of the maximum size that can be used in the rotation direction is 1 and the paper is continuously fed. When the distance between recording materials is a and the natural number is n, the total circumferential length L of the film sheet 41 of the transfer belt 40 is determined to be L = n (l + a), and the transfer drum 40, that is, the film sheet 41. And the number of images formed on the recording material P per time, that is, the number of copies can be increased even in the continuous mode.

The fact that the utilization factor K is improved by determining the total length L of the film sheet 41 of the transfer belt 40 as described above is as described in the first embodiment, and therefore its explanation is omitted here. To do.

In the above embodiment, the case where the present invention is applied to the electrophotographic color copying machine has been described.
The present invention is not limited to this, and is equally applicable to electrophotographic color or monochromatic (black and white) image forming apparatuses of various configurations and electrostatic recording type image forming apparatuses. Needless to say.

[0044]

As described above, according to the image forming apparatus of the present invention, since the total circumferential length L of the recording material carrying means is set to the length according to the predetermined formula, the recording material of at least one size is formed. For, while avoiding the seam of the recording material carrying means,
A plurality of recording materials can be continuously supplied to the recording material holding means at a predetermined distance a, and therefore, there is an effect that the utilization rate of the recording material holding means can be increased. Further, in the case of the continuous mode, there is an effect that the number of images formed on the recording material per time, that is, the number of copies can be increased.

Further, by improving the utilization rate of the recording material carrying means, the image forming speed in the image forming section including the moving speed of the recording material carrying means can be made small, and the size and cost of the apparatus can be reduced. There is also an effect that can be achieved.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a supply state of a recording material to a recording material carrying belt in a first embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a diagram for explaining a supply state of a recording material to a recording material carrying belt in a second embodiment of the image forming apparatus according to the present invention.

FIG. 3 is a schematic cross-sectional view showing the overall configuration of an electrophotographic color image forming apparatus according to the first embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view showing a configuration of a main part of an electrophotographic color image forming apparatus according to a third embodiment of the present invention.

FIG. 5 is a schematic sectional view showing an example of a conventional electrophotographic color image forming apparatus.

FIG. 6 is a diagram for explaining a supply state of a recording material to a recording material carrying belt in the conventional image forming apparatus of FIG.

FIG. 7 is a diagram for explaining a supply state of the recording material to the recording material carrying belt in the conventional image forming apparatus of FIG.

[Explanation of symbols]

 Pa to Pd Image forming unit 21a to 21d Photoreceptor drum 22a to 22d Primary charger 23a to 23d Image exposure device 24a to 24d Developing device 27a to 27d Transfer charger 28a to 28d Cleaner 30 Fixer 31 Recording material carrying belt 31a Seam portion 40 Transfer Drum 41 Film Sheet 41a Seam P Recording Material

Claims (2)

[Claims] 1. A visible image formed by the image forming unit, the image forming unit having an image bearing member, a unit for forming a visible image on the image bearing member, and an endless shape having a joint portion. A recording material carrying means for carrying a recording material to be transferred to a transfer position of the image forming means, and a transfer means for transferring a visible image on the image carrier to the recording material at the transfer position. A recording material having at least a plurality of sizes is provided, which is capable of conveying the recording material carried by the recording material carrying means to a transfer position of a plurality of image forming means and forming a multicolor image on the recording material. In the usable image forming apparatus, of the usable recording materials, the length of the recording material of one size in the moving direction of the recording material carrying means is 1, and the appropriate recording material when continuously passing this recording material. The distance is a and the natural number is n At this time, the image forming apparatus is characterized in that the total circumferential length L of the recording material carrying means is L = n (l + a). 2. A visible image formed by the image forming means, which is formed in an endless shape having a seam and an image forming means having an image bearing body and means for forming a visible image on the image bearing body. A recording material carrying means for carrying a recording material to be transferred to a transfer position of the image forming means, and a transfer means for transferring a visible image on the image carrier to the recording material at the transfer position. A recording material having at least a plurality of sizes is provided, which is capable of conveying the recording material carried by the recording material carrying means to a transfer position of a plurality of image forming means and forming a multicolor image on the recording material. In the usable image forming apparatus, of the usable recording materials, the length of the recording material of one size in the moving direction of the recording material carrying means is 1, and the appropriate recording material when continuously passing this recording material. The distance is a and the natural number is n At this time, the image forming apparatus is characterized in that the total circumferential length L of the recording material carrying means is L = 2n (l + a).