JP2917332B2 - Image forming device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to a transfer material in one step based on an original or image information which is spatially or temporally close to each other. The present invention relates to an image forming apparatus that can form the image on both sides or a composite image thereof.

(Prior Art) Conventionally, a photoconductor that develops an electrostatic latent image to form a visible image, and a transfer belt that can transfer the visual image on the photoconductor,
2. Description of the Related Art There is known an image forming apparatus in which a composite image is formed by superposing and transferring a plurality of visible images on a transfer belt and retransferring the composite image to a transfer material.

Further, a transfer path of the transfer paper is arranged so as to pass through a transfer portion between the photoconductor and the transfer belt, the first image is transferred to the transfer belt, and the first image is transferred onto the photoconductor in synchronization with the image on the transfer belt. A second image is formed, and the transfer material is fed to the transfer section in synchronization with these images, so that the transfer material is formed once on both sides of the transfer material by passing the transfer material once through the conveyance path. Are known.

(Problems to be Solved by the Invention) However, in any of the above image forming apparatuses, the transfer belt must be rotated one revolution between the first image and the second image. When the original or image information that is the source of the second image is supplied in close proximity to space or time, it is not possible to form a composite image as it is or to form images on both sides at the same time. There was a problem that it had to be formed.

For example, in a copier, when a book is opened and the pages on both sides of the book are copied on both sides of the sheet, the original is scanned one page at a time, and the first scanned image is transferred to a transfer belt. Double-sided copying can be performed by feeding the transfer material in synchronization with the second scan image, but it is not possible to scan both-sided pages once with the book open and copy on both sides of the transfer material in one step. However, there is a problem that copying requires time and effort. A similar problem also occurs when printing image information for two leaves on both sides of a sheet.

Also, when a composite image is formed by a copying machine, the first document of the image to be combined is scanned and the image is transferred to a transfer belt, and then the second document is scanned and the image is transferred. It is necessary to transfer the image on the belt in a superimposed manner and re-transfer the image onto a transfer material. Since both originals to be combined are arranged in parallel and a combined image cannot be formed by one scan. However, there is a problem that it takes time and effort, and there is a similar problem when image information is synthesized and printed in the same manner as described above.

In view of the above conventional problems, the present invention forms those images on both sides of a transfer material in one step based on a document or image information located spatially or temporally close to each other, or forms a composite image thereof. It is an object of the present invention to provide an image forming apparatus that can be formed.

(Means for Solving the Problems) In order to achieve the above object, an image forming apparatus of the present invention
An image carrier that carries a visible image on the surface, a transfer belt that is disposed so as to be substantially in contact with the image carrier and is capable of transferring a visible image on the image carrier, and that is transferred between the image carrier and the transfer belt. A transfer path for transferring the transfer material disposed so that the material can be transferred substantially in contact with a part of the image carrier and a first support member that supports the transfer belt to be able to substantially contact the image carrier; A second supporting member for supporting the transfer belt such that the transfer material can be substantially abutted on the transfer belt from the first support member so that the transfer material can be transferred from the transfer belt.
A transfer belt supporting means having a support member and a third support member for supporting the transfer belt such that the transfer belt passes through a detour path detouring from the image carrier between the first support member and the second support member. This is a first feature.

An image carrier that carries a visible image on the surface thereof; a transfer belt that is disposed so as to be able to substantially abut on the image carrier at at least two positions to transfer a visible image on the image carrier; A transfer belt supporting means for supporting the transfer belt such that the transfer belt passes through the detour path between the respective substantially abutting positions with the image carrier, and the length of the detour path can be changed; and an image carrier. A transfer path for transferring the transfer material disposed such that the transfer material is substantially in contact with the transfer belt so that the transfer material can be transferred from the transfer belt at a position below the transfer belt in the moving direction of the transfer belt. Features.

(Operation) According to the configuration of the first aspect of the present invention, the transfer belt that is disposed so as to be substantially in contact with the image carrier and is capable of transferring a visible image on the image carrier is in this substantially abutted state. The visible image on the image carrier can be transferred, and when this approximate contact is released, the transfer material can be transferred between the image carrier and the transfer belt so that the transfer material can be transferred to a part of the image carrier. A state is obtained in which a normal one-sided image formation is not hindered in a transfer path of the transfer material disposed so as to pass in contact therewith. The first support member enables the transfer belt to be arranged so as to be substantially in contact with the image carrier, and the third support member includes a first support member and a second support positioned on the upper and lower sides in the moving direction of the transfer belt. By supporting the transfer belt so as to pass through a detour path detouring from the image carrier between the transfer belt and the member, the transfer belt and the transfer material are supported between the portions where the first and second support members support the transfer belt. Does not come into contact with the image carrier, and even when a visible image is transferred to the surface of the transfer belt in a state where the first support member is in good contact with the image carrier, it does not touch the transfer material that is simultaneously conveyed. The timing at which the previous visual image transferred at the position of the first support member reaches the position of the second support member, and the next visual image on the image carrier is transferred. Is transferred onto the material as described above and reaches the position of the second support member. In accordance with the timing of that the second support member is Hoboto contact to allow transfer of the transfer belt to the transfer material, visible to which the are sequentially formed on the image bearing member via the transfer belt,
Later visible images can be transferred directly to the front and back of the same transfer material to form image formation on both sides in less than one turn of the transfer belt. It is suitable for forming a two-sided image based on first and second originals that are spatially close to each other, or first and second image information that is temporally close to each other.

Further, according to the second aspect of the present invention, the transfer belt is disposed so as to be able to substantially abut on the image carrier at at least two places and can transfer a visible image on the image carrier. The transfer of the visualized image formed earlier by the approximate contact of the belt with the image carrier by the upper hand can be performed, and the belt can be directed to the substantially accessible position of the lower hand. Even when the transfer belt and the transfer material do not come into contact with each other, even if a visible image is transferred to the surface of the transfer belt at the above-mentioned substantially abutable position, the transfer belt does not come into contact with the image carrier. The timing at which the visible image transferred at the substantially abutable position of the upper hand can reach the substantially abutable position of the lower hand according to the length of the detour path, The next time the formed image reaches the position where the lower hand And the length of the detour path can be adjusted by the transfer belt supporting means that supports the transfer belt so that the length of the detour path can be changed, so that the timing can be matched. By making the substantially visible contact state at the lower substantially contactable position, the subsequent visualized image can be transferred onto the previous visualized image without displacement, and the image carrier and the transfer belt In the transfer path of the transfer material arranged such that the transfer material is substantially abuttable on the transfer belt so as to be transferable to the transfer belt at a position below the transfer belt in the moving direction of the transfer belt, the synthesized visual image is formed on one surface of the transfer material. The transferred image is sequentially transferred to the same portion of the transfer belt to synthesize the first visible image and the second visible image sequentially formed on the image carrier, and the resultant image is re-transferred to a transfer material to form a synthesized image. It can be formed in less than one round of the transfer belt In can be achieved, open the first and or the second document spatially close, such as a document or two consecutive originals sides pages of a first temporally close
This is suitable for forming a composite image based on the image information and the second image information.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 23.

In the first embodiment shown in FIGS. 1 to 8, reference numeral 1 denotes a platen glass on which a document is placed. Reference numeral 2 denotes a light source for illuminating the original, and reference numeral 3 denotes a movable optical system for projecting an image of the original on the photosensitive drum 5. Reference numeral 4 denotes a prism interposed in the optical system 3, which switches between a normal image and a mirror image by moving between a position interposed in the optical path and a retracted position.

Around the photoreceptor drum 5, a developing device 6, a transfer charger 10,
A photoreceptor cleaner 7, an eraser 8, a charger 9 and the like are provided. An endless transfer belt 11 is disposed between the developing device 6 and the photoconductor cleaner 7 so as to face the photoconductor drum 5 at two positions on both sides of the transfer charger 10 with the transfer charger 10 interposed therebetween. ing. The portion of the transfer belt 11 facing the photosensitive drum 5 is configured to be movable between a position substantially in contact with the photosensitive drum 5 and a position separated from the photosensitive drum 5. Further, the transfer belt 11 and the photosensitive drum 5
And a paper passing path is arranged between them.

As shown in FIG. 2, the transfer belt 11 has a conductive layer 1 made of a 600 μm-thick polystyrene base material (electric resistance of 10 ⁶ Ωcm or less) containing carbon black as a conductive filler.
On the surface of 2, a 50 μm thick polybutylene layer (electrical resistance 10 ¹⁴
(Ωcm or more).

The transfer belt 11 includes rollers 21, 22, 23, 24, 25, and 26.
It is preferable that each roller is conductive and grounded. Transfer charger 10
Rollers 21 and 22 on both sides of the
The roller 23, which is configured to be separable and located between the rollers 21 and 22, can change the length of the transfer belt 11 between the rollers 21 and 22 according to the length of the transfer paper or the toner image. It is configured to be movable. Also, this roller 23
The roller 25 also moves to prevent the transfer belt 11 from becoming loose due to the movement of the transfer belt 11. The roller 23 supports a side end of the transfer belt 11 so as not to contact the toner image on the transfer belt 11.

Around the transfer belt 11, a belt transfer charger 14 facing the transfer belt 11 near the roller 26, and a belt transfer charger 15 facing the transfer belt 11 near the roller 24.
And a belt cleaner 16 are provided. A register roller 17 for feeding the transfer paper 20 at a predetermined timing is provided on the paper feeding side of the paper passing path between the photosensitive drum 5 and the transfer belt 11, and the paper discharging side is sandwiched by the paper passing path. Upper fixing roller 18a and lower fixing roller 18b each having a built-in heater lamp 19
Is arranged.

A specific example of the structure of the support mechanism of the transfer belt 11 by the rollers 23 is shown in FIG. 3. As shown in FIG. 3, a support member 11a having holes 11b regularly formed on both sides of the transfer belt 11 is fixed. As shown in FIG. 4, the material 11a is wound around large-diameter portions 23a formed at both ends of the roller 23, and locking projections 23b projecting from the outer periphery thereof are fitted into the holes 11b to transfer the transfer belt.
11 prevents slack in the width direction.

Further, a specific configuration example of the moving mechanism of the roller 23 is shown in FIG. 4 and FIG.
Bearing members 33 fitted to both ends of 23c are movably supported by guide grooves 35 formed in both side plates 34, and driven by a feed screw 37 driven by a stepping motor 36. Like that.

As another specific configuration example of the support mechanism of the transfer belt 11 by the roller 23, as shown in FIG.
A thick supporting portion 11c having a triangular cross section may be formed on both sides of the roller 23, and the thick supporting portion 11c may be wound around and supported by tapered roller portions 23d formed at both ends of the roller 23. As shown in the figure, instead of forming the thick support portions 11c on both sides of the transfer belt 11, a support member 11d having a triangular cross section may be attached.

Next, the operation will be described. An original 30, which is a so-called book, in which a book is opened and placed, is placed on the original platen glass 1. The movable optical system 3 moves from right to left in FIG. First, a normal image of the surface A of the document 30 is projected on the photosensitive drum 5 charged to -600 V by the charger 9, and an electrostatic latent image is formed. At this time, prism 4
Is at a position interposed in the optical path. Next, when the optical system 3 comes to the B-side portion of the document 30, the prism 4 retreats out of the optical path, a mirror image of the B-side portion is projected on the photosensitive drum 5, and an electrostatic latent image is formed. . Each latent image on the photosensitive drum 5 is developed with a developing unit 6 having a developing bias of -150 V.

On the other hand, the difference between the distance on the transfer belt 11 and the distance on the photosensitive drum 5 is exactly equal to the length of the transfer paper 20 between the positions where the rollers 21 and 22 are substantially in contact with the photosensitive drum 5. The position of the roller 23 is adjusted in advance, and the transfer belt
11 is charged to −1000 V by the belt transfer charger 14.

Next, the transfer operation of the toner image on the photosensitive drum 5 is performed in the eighth
Description will be made based on the drawings. First, as shown in FIG. 8 (a), the charged transfer belt 11 is substantially brought into contact with the photosensitive drum 5 by the roller 21, and the normal image of the A side of the document 30 is transferred to the transfer belt 11. . At this time, the roller 22 is
11 is separated from the photosensitive drum 5 so as not to be stained.
Next, when the leading end of the mirror image of the surface B of the document 30 reaches the roller 21, the roller 21 is separated from the photosensitive drum 5, and the roller 22 is moved to the photosensitive drum 5 as shown in FIG. The transfer paper 20 is fed by the register roller 17 such that the leading end of the transfer paper 20 coincides with the leading end of the mirror image of the surface B. Thereafter, as shown in FIG.
The transfer charger 10 applies a charge having a polarity opposite to that of the toner from the back surface and is charged. The toner image on the surface B on the photosensitive drum 5 is transferred to the surface of the transfer paper 20. Next, transfer paper 20
When the leading edge of the toner image reaches the roller 22, the leading edge of the toner image on the surface A on the transfer belt 11 also reaches the roller 22.
Further, when the leading end of the transfer paper 20 and the leading end of the toner image on the surface A on the transfer belt 11 reach the belt transfer charger 15, the transfer paper 20 is separated from the surface by the belt transfer charger 15 (−5 kV). The toner image on the surface A is transferred to the back surface of the transfer paper 20 by applying the charge of the opposite polarity and charged. Thus, the toner image on the surface B is transferred to the front surface of the transfer paper 20, and the toner image on the surface A is transferred to the back surface.

The transfer paper 20 on which the toner image has been transferred is separated from the transfer belt 11 at the roller 24, and the toner is fixed by the fixing rollers 18a and 18b, and is discharged.

In the above description, the leading end of the transfer paper 20 and the toner image on the A surface portion are synchronized. However, by adjusting the movement of the roller 23, a binding margin can be formed on the side of the transfer paper 20.

Further, in this embodiment, an example is shown in which the dielectric type transfer belt 11 in which the dielectric layer 13 is provided on the conductive layer 12 is used,
Instead of the dielectric layer, a photoconductor type transfer belt provided with a photoconductor layer may be used.

Next, a second embodiment of the present invention will be described with reference to FIGS. The same components as those described in the first embodiment are denoted by the same reference numerals, and the description including the operation is omitted, and the second embodiment is different from the first embodiment. Only the points that are described will be described.

In the second embodiment, a pre-transfer eraser 31 is provided between the developing device 6 and the roller 21 so that the toner image on the photosensitive drum 5 is easily transferred, and the transfer charger 10 is eliminated. Further, the belt cleaner 16 is disposed near the roller 26, and the rollers 21 and 22 are fixedly disposed at positions substantially in contact with the photosensitive drum 5.

Next, the transfer operation of the toner image on the photosensitive drum 5 in this embodiment will be described with reference to FIG. First, the tenth
As shown in FIG. 1A, the original is placed on the charged transfer belt 11.
The transfer of the normal image of the 30 A side portion is the same as in the first embodiment. Next, the tip of the mirror image of the B side of the original 30 is a roller.
As shown in FIG. 10 (b), the transfer paper 20 is fed by the register roller 17 so that the leading end of the transfer paper 20 coincides with the leading end of the mirror image on the side B, as shown in FIG. The transfer paper 20 is placed on the transfer belt 11 which is charged to the opposite polarity, and the transfer paper 20 is transferred to the transfer paper 20 at the portion between the rollers 21 and 22. At this time, since the negative charge of the photosensitive drum 5 has been erased by the pre-transfer eraser 31, the electrostatic attraction between the toner and the photosensitive drum 5 is weakened, and the toner is easily transferred. Next, as shown in FIG. 10 (c), when the leading end of the transfer paper 20 reaches the roller 22, the leading end of the toner image on the surface A on the transfer belt 11 reaches the roller 22. Thereafter, the toner image on the surface A is transferred to the back surface of the transfer paper 20 by the belt transfer charger 15.

Also in the second embodiment, a dielectric type transfer belt is used.
Instead of 11, a photoconductor type transfer belt can be used.

Next, third to fifth embodiments of the present invention will be described with reference to FIGS. Note that the same components as those described in the above embodiments are denoted by the same reference numerals, and description thereof including the operation thereof will be omitted. This also applies to the following embodiments.

The first and second embodiments are examples in which the dielectric belt shown in FIG. 2 is used for the transfer belt 11, but the third to fifth embodiments use semiconductors as shown in FIG. This is an embodiment in the case of using a type belt.

The In Figure 11, the transfer belt 41, the surface of the semiconductor substrate 42 made of 600μm thick urethane rubber substrates (electric resistance 10 ⁹ to 10 ¹¹ [Omega] cm), 20 [mu] m thick polytetrafluoroethylene (electric resistance 10 ¹⁰ Semiconductor layer 43 composed of 1010 ¹² Ωcm)
Is formed of a semiconductor-type belt formed with.

The third embodiment shown in FIG. 12 has a basic structure corresponding to that of the first embodiment, and a semiconductor type transfer belt 41.
Some configurations have changed in response to the change to. Twelfth
In the figure, the belt transfer charger 14 is eliminated, and instead the roller 21 is constituted by a conductive brush roller or a conductive rubber roller, and is connected to a transfer bias power supply 44.

The operation of the third embodiment is based on the point that a transfer bias is applied to the roller 21 and the toner image is transferred to the transfer belt 41 when the normal toner image on the surface A of the document 30 comes to the roller 21 portion. Except for this, the configuration is the same as that of the first embodiment.

The fourth embodiment shown in FIG. 13 has a basic structure corresponding to that of the second embodiment, and a belt transfer charger corresponding to the change to the semiconductor type transfer belt 41 as in the third embodiment. Instead of 14, roller 21 is used for transfer bias power supply 44
The operation of the third embodiment is the same as that of the third embodiment.

The fifth embodiment shown in FIG. 14 is a modification of the fourth embodiment shown in FIG. 13, in which another roller 27 is provided near the photosensitive drum 5 at an interval from the roller 21. roller
A transfer charger 28 is arranged between 21 and 27. In this case, the rollers 21 and 27 do not necessarily need to be conductive. The transfer operation in this embodiment is performed by the transfer charger 28.
And the transfer paper 20 from the photosensitive drum 5 to the transfer belt 41
This is the same as the second and fourth embodiments except that the toner image is transferred to the second embodiment.

In the third to fifth embodiments, the example in which the transfer belt 41 made of a semiconductor is used has been described, but a transfer belt made of a dielectric material may be used instead of the transfer belt 41.

Next, a sixth embodiment of the present invention will be described with reference to FIGS. Each of the above embodiments is an example in which a dielectric type belt shown in FIG. 2 or a semiconductor type belt shown in FIG. 11 is used as the transfer belt.
This is an embodiment in which a photoconductive type belt as shown in FIG. 16 is used.

In FIG. 15, a transfer belt 51 is formed by forming a layer of a photoconductor 53 on a conductive support 52. Further, instead of the single-layer photoconductor 53, as shown in FIG. 16, a charge generation layer 54 on a conductive support 52 and a charge transport layer 55 formed thereon may be used.

The sixth embodiment shown in FIG. 17 has a basic structure corresponding to the second embodiment, and is a photoconductive type transfer belt.
In response to the change to 51, a belt eraser 56 is disposed between the rollers 21 and 22.

Further, in this embodiment, the roller 21 is disposed at a position substantially in contact with the photosensitive drum 5, but the roller 22 is disposed so as to face the paper passing path at a position separated from the photosensitive drum 5, and A guide plate 57 that forms a paper passage is disposed between the rollers 21 and 22.

The operation of the sixth embodiment is the same as that of the second embodiment, except that the toner image of the surface A is transferred onto the transfer belt 51 by the roller 21 and the toner image of the surface B is transferred to the transfer paper. Transferred to 20 surfaces. Then, while the toner image on the surface A reaches the roller 22, the transfer belt is transferred by the belt eraser 56.
Since the charge on the surface of the transfer belt 51 is erased, the toner image on the surface A on the transfer belt 51 is transferred to the transfer paper by the belt transfer charger 15.
It is easily transferred when transferred to the back side of 20.

In the first to fifth embodiments, similarly to the sixth embodiment, the roller 22 can be disposed at a position separated from the photosensitive drum 5 and at a position facing the paper passing path. For example, when applied to the fourth embodiment shown in FIG. 13, it is configured as in the seventh embodiment shown in FIG. The transfer belt 11 in the seventh embodiment has a thickness of 30 μm on the conductive layer 12 having a thickness of 600 μm.
A dielectric type belt having a dielectric layer 13 made of a polybutylene layer having a thickness of μm is used.

Next, an eighth embodiment of the present invention will be described with reference to FIGS. 19 and 20.

The first to seventh embodiments show examples in which an image is formed in one step on both sides of the transfer paper 20 from the book original 30. In the eighth embodiment, the two sheets are arranged in parallel. This is an example of a case where a composite image of a document is formed on transfer paper.

In FIG. 19, only the positive images of the originals 60a and 60b placed in parallel on the original platen glass 1 are projected onto the photosensitive drum 5 with respect to the configuration of the first embodiment. , One mirror is added and the prism 4 is not arranged. Further, a paper passage path is not provided between the photosensitive drum 5 and the rollers 21 and 22, and a paper passage path for the transfer paper 20 is provided close to the roller 24, and between the rollers 21 and 22. A belt transfer charger 29 is provided so as to eliminate the transfer charger 10 and replace the belt transfer charger 15 so as to face the roller 24 with the paper passing path interposed therebetween. Roller 21,
Of the rollers 22, at least the roller 21 on the upper side in the rotation direction of the transfer belt 11 is configured to be able to approach and separate from the photosensitive drum 5, and the belt cleaner 16 is arranged near the roller 26.

Next, a transfer operation in this embodiment will be described with reference to FIG. First, as shown in FIG.
The toner image A of a is transferred to the transfer belt 11 charged by the belt charger 14 at the roller 21 portion. next,
When the leading end of the toner image B of the original 60b reaches the roller 21, the roller 21 separates from the photosensitive drum 5, as shown in FIG.
Of the toner image A on the transfer belt 11
20 and reaches the toner image B as shown in FIG.
Is transferred onto the transfer belt 11 and the two toner images A and B are superimposed on the transfer belt 11 to be synthesized. Thereafter, the synthesized toner images are transferred to the transfer paper 20 by the belt transfer charger 29 at the roller 24. The image is transferred and a composite image is formed on the transfer paper 20.

Also in this embodiment, a photoconductor type transfer belt can be used instead of the dielectric type transfer belt 11.

Next, ninth and tenth embodiments, which are modified examples of the eighth embodiment, will be described.
An embodiment will be described with reference to FIGS. 21 and 22.

In the ninth embodiment shown in FIG. 21, a semiconductor type transfer belt 41 is used as the transfer belt in the same manner as in the third to fifth embodiments.
In order to transfer the toner image on the photosensitive drum 5 to the transfer belt 41 instead of the belt charger 14, the transfer bias power supply is applied to the rollers 21 and 22, respectively.
44 is connected. The transfer operation in this embodiment is the eighth
This is the same as the embodiment. In this embodiment, a transfer belt made of a dielectric material can be used instead of the transfer belt 41 made of a semiconductor.

The tenth embodiment shown in FIG. 22 is an example in which a photoconductive type transfer belt 51 is used as the transfer belt in the same manner as the sixth embodiment, and the transfer belt 51 is located at a position farther in the rotation direction of the transfer belt 51 of the roller 24. Bell toiletrs 56 are provided. In this embodiment, the transfer belt 51 is
Since the surface charge of the transfer belt 51 is erased by the belt eraser 56 before the upper toner image is transferred onto the transfer paper 20, the transfer from the transfer belt 51 to the transfer paper 20 is easily performed.

In the case of the image synthesis of the eighth to tenth embodiments, the developing device 6
It is needless to say that multi-color composition may be performed by disposing a plurality of colors and making two originals have different colors.

Further, if the transfer belt is supported so that the contact position of the transfer belt with the photoconductor is approximately three, three images can be synthesized.

Next, the sheet passing paths shown in the first to seventh embodiments and the eighth to
In the tenth embodiment, both of the paper passing paths shown in the embodiment are provided, and by selecting one of the paper passing paths, the duplex image and the composite image can be arbitrarily selected and formed. An eleventh embodiment will be described with reference to FIG.

The eleventh embodiment is an embodiment in which a semiconductor type transfer belt 41 is used, and is configured based on the ninth embodiment in FIG. In FIG. 23, a transfer bias power supply 44 is connected to the rollers 21 and 22, and the roller 24 is
The feeding path 70 for forming a composite image is connected to a position on the upper side in the moving direction of the transfer belt 41. Reference numeral 71 denotes a two-sided image forming paper feed cassette, 72 denotes a paper feed roller thereof, 73 denotes a composite image forming paper feed cassette, 74 denotes the paper feed roller, 75 denotes a transport roller, and 76 denotes a registration roller. The operation in this embodiment is the same as that in the above embodiment, except that only the two-sided image and the composite image can be switched.

Further, a single image can be formed on one side of the transfer paper 20 by feeding paper from a paper feed cassette 71 for forming a double-sided image or a paper feed cassette 73 for forming a composite image. When the paper is fed from the transfer drum 20, the surface of the transfer paper 20 depends on which of the photosensitive drum 5 and the transfer belt 41 is used for the transfer.
The image can be formed on any of the back surfaces, and the transfer paper 20 can be discharged in any of the face-up and face-down states.

Incidentally, in the embodiment of FIG. 23, the transfer belt 41 of the semiconductor type is used.
However, it is needless to say that the present invention can be similarly applied to a transfer belt of a dielectric type or a photoconductive type.

In each of the above embodiments, the transfer paper 20
Of the transfer belts 11, 41, and 51, the transfer charger 10, the belt transfer charger 14, and the belt transfer Charger 15, transfer charger 28, belt transfer charger 29, transfer bias power supply 44
For example, it is preferable to increase the charging potential of the transfer belts 11, 41, 51 and the transfer paper 20 to prevent poor transfer at high humidity.

In the above-described embodiment, only the case of original copying has been described. However, in an image forming apparatus such as a printer, temporally close or continuous image information is printed on both sides of the transfer paper in one step, or the image is synthesized. It can also be printed.

Further, in the above-described embodiment, an example in which the photosensitive drum is used as the image carrier has been described, but a dielectric drum may be used.

(Effects of the Invention) According to the image forming apparatus of the present invention, as is apparent from the above description, according to the first feature of the present invention, a visible image formed on an image carrier is directly transferred to a transfer material. In addition to transferring and forming an image, the first visible image sequentially formed on the image carrier is passed through a transfer belt, and the later visible image is directly transferred to the front and back of the same transfer material to form an image on both sides. Can be achieved in the course of less than one rotation of the transfer belt, and the first and second originals which are spatially close to each other, such as originals on both sides of an open book, continuous originals, etc. It is suitable for forming a double-sided image based on the first and second image information adjacent to each other.

According to the second feature of the present invention, the first visual image and the subsequent visual image sequentially formed on the image carrier are sequentially transferred to the same portion of the transfer belt and synthesized, and this is transferred. Re-transferring to a material to form a composite image can be achieved in less than one turn of the transfer belt, and the first and second spatially close originals such as an original on both sides of an open book or a two-sheet continuous original. This is suitable for forming a combined image based on two originals or first and second image information that are close in time.

[Brief description of the drawings]

1 to 8 show a first embodiment of the present invention. FIG. 1 is an overall schematic diagram, FIG. 2 is a sectional view of a dielectric type transfer belt, and FIG. FIG. 4 is a plan view, FIG. 5 is a side view of a moving mechanism of the roller, and FIG. 6 is another supporting structure of the transfer belt by a movable roller. FIG. 7 is a cross-sectional view of a transfer belt in a modified example of the supporting configuration example of FIG. 6, FIGS. 8 (a) to 8 (c) are explanatory views of a transfer operation,
9 and 10 show a second embodiment of the present invention. FIG. 9 is an overall schematic diagram, FIGS. 10 (a) to 10 (c) are explanatory diagrams of a transfer operation, and FIG. 11 is a semiconductor type. Sectional view of a transfer belt of
FIGS. 12 to 14 are schematic structural views of main parts of the third to fifth embodiments of the present invention, FIGS. 15 and 16 are cross-sectional views of a photoconductive type transfer belt, and FIG. FIG. 18 is a schematic configuration diagram of a main part of a sixth embodiment of the present invention, FIG. 18 is an overall schematic configuration diagram of a seventh embodiment of the present invention, and FIGS. 19 and 20 show an eighth embodiment of the present invention.
19 is an overall schematic configuration diagram, FIGS. 20 (a) to (c) are explanatory diagrams of a transfer operation, and FIGS. 21 and 22 are schematic configuration diagrams of main parts of the ninth and tenth embodiments of the present invention. FIG. 23 is an overall schematic configuration diagram of an eleventh embodiment of the present invention. 5 photosensitive drum 10 transfer charger 11 dielectric transfer belt 14 belt charging charger 15 belt transfer charger 20 transfer paper 21-26 roller 28 transfer charger 29 … Belt transfer charger 41… Semiconductor type transfer belt 44 …… Transfer bias power supply 51 …… Photoconductive type transfer belt

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuyoshi Hara 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka Osaka International Building Minolta Camera Co., Ltd. (72) Inventor Masayasu Haga Azuchi, Chuo-ku, Osaka-shi, Osaka 2-3-3, Osaka-cho, Osaka International Building Minolta Camera Co., Ltd. (56) References JP-A-60-156071 (JP, A) US Patent 4,688,925 (US, A) (58) Fields investigated (Int. Cl. ^6, DB name) G03G 15/00 106 G03G 13/14 - 13/16 G03G 15/14 - 15/16 103

Claims (2)

(57) [Claims] An image bearing member for carrying a visible image on a surface thereof; a transfer belt disposed so as to be substantially in contact with the image carrier and capable of transferring a visible image on the image carrier; and an image bearing member and a transfer belt. And a transfer path for the transfer material, which is disposed so that the transfer material substantially abuts on a part of the image carrier so as to be able to transfer, and supports the transfer belt so as to be able to abut the image carrier. A first support member, a second support member for supporting the transfer belt such that the transfer material can substantially abut the transfer belt from the transfer belt below the first support member in the moving direction of the transfer belt, and a first support member and a second support member. A transfer belt supporting means having a third support member for supporting the transfer belt such that the transfer belt passes through a detour path detouring from the image carrier between the second support member and the second support member. 2. An image carrier for carrying a visible image on a surface thereof, a transfer belt disposed at at least two positions on the image carrier so as to be substantially in contact with the image carrier, and capable of transferring a visible image on the image carrier. Transfer belt supporting means for supporting the transfer belt so that the transfer belt passes through the detour path between the respective substantially abutting positions of the transfer belt and the image carrier, and the length of the detour path can be changed; And a transfer path for the transfer material disposed so that the transfer material is substantially in contact with the transfer belt such that the transfer material can be transferred from the transfer belt at a position below the transfer belt in the moving direction of the transfer belt. Characteristic image forming apparatus.