JP3254447B2 - Color image recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a color printer,
The present invention relates to a color image recording apparatus applicable to a color copying machine, a color facsimile, and the like.

[0002]

2. Description of the Related Art As a conventional example, the inventors have filed Japanese Patent Application No. 5-1.
The configuration will be described using a color electrophotographic apparatus filed in Japanese Patent Application No. 78998. FIG. 5 is an overall configuration diagram of the conventional color electrophotographic apparatus.

In the center, four fan-shaped image forming units 101Bk, 1 for each color of black, cyan, magenta, and yellow
01C, 101M, and 101Y constitute an image forming unit group, and are arranged in an annular shape. 102 is a photoconductor, 103
Is a charger, 104 is a developer hopper, 105 is a cleaner,
106 is an electrode roller. Image forming units 101Bk, 101C, 101M, 101 arranged in an annular shape
Y is supported by a support (not shown), is driven by a moving motor 107 as a moving means as a whole, and is rotatable about a cylindrical fixed and non-rotating shaft 108. Each image forming unit can be sequentially positioned at the image forming position 111 facing the transfer roller 110 that supports the intermediate transfer belt 109. Image forming position 111
Is also the exposure position by the signal light 112. Reference numeral 113 denotes a laser exposure device which generates a signal beam 112 by a laser beam modulated by a signal input to the printer unit, and passes through an optical path formed between the image forming units 101M and 101Y in FIG. , A window 1 opened in a part of the shaft 108
The light enters the mirror 115 fixed inside the shaft 108 through 14a and 114b, is reflected, and is irradiated on the photosensitive member 102 of the image forming unit at the image forming position 111 to form a latent image. In the state of FIG. 5, the image forming unit 101Bk for black is used.
Act on.

Next, the operation of this apparatus when forming a color image will be described. First, the image forming unit is at a position as shown in FIG. 5, and the image forming unit 101Bk for black is used.
Are at the image forming position 111 as shown in the figure. A black signal light is input to the image forming unit 101Bk by the laser exposure device 113, and an image is formed with black toner. At the same time as the image is formed, the black toner image is transferred to the intermediate transfer belt by the action of the transfer roller 110. Immediately after all the black toner images have been transferred, the entire image forming unit groups 101Bk, 101C, 101M, and 101Y are driven by the moving motor 107 to rotate integrally, and
The image forming unit 101C is stopped at a position where the image forming unit 101C reaches the vicinity 111 of the image forming position by just rotating by 90 degrees. After the image forming unit 101C arrives at the image forming position 111, the laser exposure apparatus uses the cyan signal as before and the image forming unit 1
A signal light is input to 01C to form and transfer a cyan toner image. At this time, the timing of writing the cyan signal light is controlled such that the intermediate transfer belt 109 makes one rotation, and the next cyan toner image is positionally matched with the previously transferred black toner image. The same operation as above
For magenta and yellow, four color toner images are superimposed on the intermediate transfer belt in a position-matching manner to form a color image. After the transfer of the final yellow toner image, the four color toner images are printed on the paper 116 at the same time.
Batch transfer is performed by the operation of the transfer roller 117. The toner image transferred to the paper is fixed by the fixing device 118.

[0005]

With such a configuration, 2
When color printing was continued for about 00 sheets, the surface of the photoconductor 102 of each image forming unit 101 began to be damaged gradually, and streaks appeared in the image.

Further, in this configuration, the intermediate transfer belt 1
Since the maintenance is performed while keeping the photoconductor 09 and the photoconductor 102 in contact with each other, when the intermediate transfer belt 109 is replaced, the surface of the transfer belt rubs and damages the surface of the photoconductor, or light from the outside directly hits the photoconductor 102 to expose the photoconductor 102. Body 102
Has a problem of deteriorating. SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a color image recording apparatus which does not easily damage the surface of a photoreceptor and has good maintainability.

[Means for Solving the Problems]

The color image recording apparatus of the present invention has a rotating body in which a plurality of individual units each having a toner storage section and a photoreceptor are removably assembled in a substantially annular shape and adjacent to each other. In a color image recording apparatus that transfers an image exposed and developed on a body to recording paper via an intermediate transfer belt housed in an intermediate transfer body unit, the rotating body has a cylindrical space at the center thereof. A plurality of individual unit storage spaces each having a substantially fan-shaped cross section. The individual units are removably accommodated in each of the divided storage spaces, and the optical path of the exposure laser light is provided in the cylindrical space. An optical path changing unit for exposing the photosensitive member by changing the position, the intermediate transfer belt is controlled to be movable to two positions: a retracted position not in contact with the photosensitive member, and a transfer position in contact with the photosensitive member. Is, the during the rotation operation of the rotating body, the intermediate transfer belt is positioned at the retracted position said photosensitive member and said intermediate transfer belt is to avoid contact.

Thus, it is possible to obtain a small, simple and easy-to-maintain color image recording apparatus. Also, the rotating body forms a cylindrical space in the center,
Since the individual units are collectively arranged adjacent to each other in a substantially annular shape, there is almost no wasted space. Also, during the rotation operation of the rotator, the intermediate transfer belt is located at the retracted position so that the photoconductor and the intermediate transfer belt do not come into contact with each other. Neither is hurt.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction and operation of a color electrophotographic apparatus which uses an intermediate transfer belt as an intermediate transfer member, which is an example of an apparatus for recording a color image, will be described below with reference to FIG. 1 is an outer casing of a color electrophotographic apparatus,
The right end side of the drawing is the front side. Reference numeral 1A denotes a printer front plate which can be freely opened and closed and raised and closed with respect to the printer outer casing 1 about a hinge shaft 1B on the lower side. A state where the front plate 1A is folded down and opened is indicated by a dashed line.
The operation of attaching / detaching the intermediate transfer unit 2 to / from the inside of the printer, maintenance inside the printer such as when a paper jam occurs, and the like are performed by opening the front plate 1A to open the printer largely. The mounting and dismounting operation of the intermediate transfer body unit 2 is designed to be in a direction perpendicular to the rotational axis generatrix direction of the photoconductor. The intermediate transfer unit 2 includes an intermediate transfer belt 3, a first transfer roller 4, a second transfer roller 5, a cleaning roller 6, a scraper 7, a waste toner reservoir 8, a waste toner full detector 9, a backup roller 10, a position detector. 11, a tension roller 12. Detail is,
It will be described later.

In the center of the printer, black, cyan, magenta,
Four fan-shaped image forming units 13 for each yellow color
Bk, 13Y, 13M, and 13C are image forming unit groups 14
And are arranged in an annular shape as shown in the figure. Each image forming unit is connected to the left side plate 1C of the printer shown in FIG.
It is openable around D and is detachable at a predetermined position of the image forming unit group 14. When the image forming unit 13 is properly mounted in the printer, the mechanical drive system and the electric circuit system on both the image forming unit side and the printer side are connected via a mutual coupling member (not shown). Mechanical
Electrically integrated.

Image forming unit 1 arranged in an annular shape
3Bk, 13C, 13M, 13Y is a support (not shown)
The image forming unit group is driven by a moving motor 15 as a moving unit as a whole, and is configured to be rotatable around a fixed and non-rotating cylindrical shaft 16. During image formation, each image forming unit can be sequentially positioned at an image forming position 17 facing the first transfer roller 4 that supports the above-described intermediate transfer belt 3 by rotational movement. The image forming position 17 is also an exposure position by the laser signal light 18.

FIG. 2 shows the black image forming unit 13Bk in detail. Each image forming unit is made of the same components except for the developer put in the image forming unit. Therefore, the image forming unit 13Bk for black will be described for simplification of description, and other colors will be omitted. In addition, the same reference numerals are assigned to the same parts for each color, and when it is necessary to distinguish the configuration of each color, a letter indicating each color is added to the reference numeral. In this description, the inventors have used the developing method disclosed in Japanese Patent Application No. 4-50274. However, it goes without saying that any developing method can be used as long as it is a developing method used in a normal electrophotographic method. For example, there are a magnetic brush developing method, an elastic rubber roller developing method, a jumping developing method, an impression developing method, and the like.
In FIG. 2, reference numeral 19 denotes an organic photoreceptor mainly composed of a polycarbonate binder resin using phthalocyanine as a photosensitive material, reference numeral 20 denotes a non-rotating magnet fixed coaxially with the photoreceptor 19, and reference numeral 21 denotes a negative charge on the photoreceptor 19. A charging roller using conductive rubber, 18 is a laser signal light, 22 is an exposure window which is an opening of the image forming unit through which the laser beam enters the image forming unit, and 23 is a developer hopper.
In the developer hopper 23, a two-component developer 26Bk in which 10% of a ferrite carrier 24Bk having a particle diameter of 50 μm coated on the surface with a silicone resin and a negatively chargeable black toner 25Bk in which a black pigment is dispersed in a polyester resin is mixed.
And directly adhere to the surface of the photoconductor 19 by the magnetic force of the magnet 20. 27 is a rotatable aluminum collecting electrode roller, 28 is a non-rotating magnet coaxially fixed inside, 28 is a phosphor bronze scraper that scrapes the toner collected on the collecting electrode roller 27, and 30 is a collecting roller An AC high-voltage power supply that applies a voltage to the electrode roller 27. Reference numeral 31 denotes a cleaner for cleaning the toner remaining on the surface of the photoconductor 19 after the transfer. The photoreceptor 19 has a diameter of 30 mm and a peripheral speed of 60 mm.
The collection electrode roller 27 was rotated in the arrow direction at a speed of mm / s, and the collection electrode roller 27 was also rotated in the arrow direction at a peripheral speed of 60 mm / s with a diameter of 16 mm.

Next, the structure of the intermediate transfer unit 2 will be described with reference to FIG. The intermediate transfer body unit 2 includes, in a unit housing 2a, an intermediate transfer belt 3, a first transfer roller 4 made of an aluminum roller, and a second transfer roller made of a conductive elastic rubber roller.
A transfer roller 5, an aluminum cleaning roller 6 for cleaning the toner image remaining on the transfer belt, a scraper 7 for scraping the collected toner, a waste toner reservoir 8 for storing the scraped toner, and a toner in the waste toner reservoir 8 Waste toner full detector 9 for detecting that the amount is full, backup roller 10 made of conductive rubber facing cleaning roller 6, position detector 11 for detecting the transfer start position of intermediate transfer belt 3, intermediate transfer A tension roller 12 for adjusting the tension of the belt 3 to prevent meandering is included. The intermediate transfer body unit 2 is detachable from a predetermined storage portion in the printer outer casing 1 by opening the printer front plate 1A in FIG. The intermediate transfer belt 3 is made of an endless belt-like semiconductive (medium resistance) urethane having a thickness of 100 μm, and has a surface layer of PFA · P
It is made of a film having a thickness of 100 to 200 μm using a fluororesin such as TFE, and is wound around the first transfer roller 4, the second transfer roller 5, the backup roller 10, and the tension roller 12, and is configured to be movable in the arrow Y direction. You. The second transfer roller 5 and backup roller 10 have a medium resistance elastic layer made of silicon rubber, Teflon (registered trademark) rubber, chloroprene rubber, urethane rubber, EPDM.
It is made of a solid or foamed layer treated by mixing and dispersing carbon or metal oxide in an elastic material such as the above so as to have a medium resistance of an electric resistance value (volume resistivity) of 10 5 to 10 17 Ωcm. Here, the circumferential length of the intermediate transfer belt 3 is the length in the longitudinal direction of A4 paper (298 m
m) plus a length (62 mm) that is slightly longer than half the circumference of the photosensitive drum (diameter 30 mm) described later.
m. At this time, the second transfer roller 5 and the third
Intermediate transfer belt 3 from the contact portion of transfer roller 34 to the contact portion of cleaning roller 6 and backup roller 10
Is set to be shorter than the distance of 62 mm and 55 mm. The moving speed of the intermediate transfer belt 3 is set to the image forming speed of the image forming unit 13 (60 mm / equal to the peripheral speed of the photosensitive member) in order to prevent the hollow transfer of the toner image.
It is set to be 1.5% faster than s).

The first transfer roller 4 is movable between a transfer position 4a and a retreat position 4b. When the first transfer roller 4 is positioned at the transfer position 4a by a driving source (not shown) controlled by an electric signal, the intermediate transfer is performed. The belt 3 can transfer the toner image formed by contacting the photoconductor 19,
When the intermediate transfer belt 3 is located at the position b, the intermediate transfer belt 3 moves away from the photoconductor 19 to a non-contact position. When transferring the toner image on the photoconductor 19, a voltage of about +2.5 kV (100 μA) is applied to the first transfer roller 4 and the tension roller 12 by the high voltage power supply 32. When the first transfer roller 4 is brought into direct contact with the photoconductor 19 to transfer the toner image to the intermediate transfer belt 3, a so-called “front jump” phenomenon occurs before the intermediate transfer belt 3 comes into contact with the photoconductor 19, and the image is disturbed. In addition, it becomes difficult to uniformly adjust the contact pressure between the first transfer roller 4 and the photoconductor 19. However, when the first transfer roller 4 is moved and the intermediate transfer belt 3 stretched between the two rollers is brought into contact with the photosensitive drum 19 as in the present invention, these problems do not occur.

When the intermediate transfer unit 2 is mounted on the main body of the printer, the first transfer roller 4 is at the retracted position 4b in FIG. The intermediate transfer unit 2 is mounted on the printer body,
When the image forming operation is started, the first transfer roller 4 moves to the transfer position 4a, and the intermediate transfer belt 3 is pressed against the photoconductor 19 with a force of about 1.0 kg.

The second transfer roller 5 and the backup roller are both made of conductive rubber, and are grounded via a resistor 33 of 20 MΩ to prevent scattering during transfer of the color toner image.

The third transfer roller 34 made of aluminum is
It is in pressure contact with the second transfer roller 5 via the intermediate transfer belt 3. During the formation of the color image on the intermediate transfer belt 3, in order not to disturb the toner image on the belt,
A voltage of -1 kV is applied by the high voltage power supply 35a. When transferring the color toner image onto the image receiving paper 36, a voltage of +3 kV is applied by the high voltage power supply 35b. Reference numeral 37 denotes a static elimination needle for preventing the toner image from being disturbed when the paper 36 is separated from the intermediate transfer belt 3. The third transfer roller 34 is configured to be rotatable 1.5% slower than the intermediate transfer belt 3 in order to prevent a dropout phenomenon when transferring a toner image.

The cleaning roller 6 cleans the intermediate transfer belt 3. During the formation of a color image on the intermediate transfer belt 3, a voltage of the same polarity as the toner, that is, a negative voltage in this case, is applied to the cleaning roller 6 from the high voltage power supply 38 a in order to prevent the toner from transferring from the intermediate transfer belt 3. Has been applied. When cleaning the toner remaining on the intermediate transfer belt 3, a positive voltage is applied by the high-voltage power supply 38b to electrostatically attract the toner.

FIG. 4 is a perspective view showing the structure of the position detector 11 using a photo interrupter provided inside the intermediate transfer unit 2. A detection hole 39 is provided at an end of the intermediate transfer belt 3, and the position detector 11 determines the leading end position of the toner image by optically detecting the passage of the detection hole 39, and This is a configuration for performing color image alignment.

Returning to FIG. 1, the description will be continued. Reference numeral 40 denotes a laser exposure device disposed on the upper side of the inside of the printer outer casing 1, and includes a semiconductor laser, a scanner motor 40a, and a polygon mirror 4.
0b, a lens system 40c, and the like. The pixel laser signal light 18 corresponding to the time-series electrical pixel signal of the image information from the laser exposure device 40 is applied to the image forming unit 1 shown in FIG.
Through an optical path window 41 formed between 3Bk and 13C, the light enters a mirror 43 fixed in the shaft 16 through a window 42 opened in a part of the shaft 16 and is reflected to the image forming position 17. A developer hopper 23 and a cleaner 3 which enter the image forming unit 13Bk from the exposure window 22 of the certain image forming unit 13Bk and are disposed vertically in the image forming unit 13Bk.
The light enters the exposure unit on the left side surface of the photosensitive drum 19 through the passage between the first and second photosensitive drums 19 and is scanned and exposed in the generatrix direction.

Here, since the optical path from the optical path window 41 to the mirror 43 uses the gap between the adjacent image forming units 13Bk and 13C, the image forming unit group 1
4 has little wasted space. Also, mirror 4
Since 3 is provided at the center of the image forming unit group 14, it can be constituted by a single fixed mirror, and has a simple configuration and easy alignment.

Reference numeral 34 denotes a third transfer roller disposed inside the printer front plate 1A and above the feed roller 44. The nip portion where the intermediate transfer belt 3 and the third transfer roller 34 are pressed against each other is provided with a printer. A paper transport path is formed so that paper is fed by a paper feed roller 44 provided below the front plate 1A. The configuration of the third transfer roller 34 may be a conductive elastic roller such as the second transfer roller 5, but the use of a metal roller having a smooth surface synthesizes a color image on the intermediate transfer belt 3. This is more preferable because the surface of the toner image is not disturbed during the operation.

Reference numerals 45a and 45b denote fixing rollers provided on the upper inside of the printer. A halogen lamp 46 is provided inside the fixing roller 45a. A polyimide film 47 is stretched between the fixing roller 45a and the fixing roller 45b. This film 47 is used for the purpose of giving a gloss of a color print. Reference numeral 48 denotes a backup roller provided to face the fixing roller 45a, and reference numeral 49 denotes a paper discharge roller pair provided on the paper exit side. The above is the description of the main configuration of the electrophotographic apparatus of the present invention.

Next, a configuration and an operation when the image forming unit 13 and the intermediate transfer unit 2 are replaced will be described. The state shown in FIG. 1 is a state in which an image is being formed. This is a state in which the first transfer roller 4 has moved to the position 4a in FIG. 3 in order to transfer the toner image formed on the photoconductor 19 to the intermediate transfer belt 3. The first transfer roller 4 is retracted to the position 4b when the image forming unit group 14 rotates or when the printer is stopped. In this state, the photoconductor 19 does not contact the intermediate transfer belt 3. In this retracted state, the printer stops the printing operation, and by opening the printer front plate 1A, the replacement of the intermediate transfer unit 2 can be taken out. Even if the intermediate transfer body unit 2 is moved in and out in this state, the photoconductor 19 and the intermediate transfer belt 3 are not strongly pressed against each other during the operation, and both are not damaged. At the same time, by opening the printer left face plate 1C, replacement of each image forming unit 13 can be taken out. When replacing another image forming unit 13,
The image forming unit group 14 stops after being rotated by 90 ° from this state.

The surface of the intermediate transfer belt 3 gradually deteriorates due to sticking of toner or the like as it is used for a long time. If the belt is significantly deteriorated, the image is partially chipped or white or black stripes are generated in the image. Therefore, it is desirable to replace the intermediate transfer belt 3 before the intermediate transfer belt 3 deteriorates and an image is affected. However, it is extremely difficult to automatically detect the deterioration phenomenon of the intermediate transfer belt 3 in the printer. In the present invention, as shown in FIG. 3, the intermediate transfer belt 3 is integrated with a waste toner reservoir 8 to form a unit, and the waste toner is simultaneously discarded when the intermediate transfer belt 3 is replaced. In such a configuration, it is preferable to design the size of the intermediate transfer belt 3 to a small eye volume so that the waste toner reservoir is filled with the waste toner before the end of the life of the intermediate transfer belt 3. In this case, before the intermediate transfer belt 3 is deteriorated and an image defect occurs, the waste toner full detector 9 installed inside the waste toner reservoir detects that the toner is full, and instructs the user to replace the intermediate transfer body unit 2. can do. Such a configuration is not only effective for an intermediate transfer belt on which a toner image is directly formed, but is also effective for an intermediate transfer body having a configuration in which an image receiving paper is wound around.

With the above arrangement, the photosensitive member 19 of the image forming unit does not come into contact with the intermediate transfer belt 3 during the rotational movement of the image forming unit group, so that the photosensitive member 19 is not damaged. Further, since the intermediate transfer belt 3 does not come into direct contact with the photoconductor 19 when the intermediate transfer unit 2 is replaced, the photoconductor 19 is not damaged during maintenance. Further, in this method, the exposure position on the photoreceptor 19 is smaller than in the configuration in which the position of the intermediate transfer belt 3 is fixed and the image forming unit 13 is moved to the transfer position during image formation and is brought into contact with the intermediate transfer belt. This has the effect of stabilizing and improving the color registration accuracy during color image synthesis.

Hereinafter, the operation of the color electrophotographic apparatus according to one embodiment of the present invention will be described with reference to the drawings.

The printer shown in FIG. 1 is in an image forming state. The operation of the image forming unit 13Bk will be described with reference to FIG.
The photoconductor 19 was charged to −450 V by the charging roller 21. The photosensitive member 19 was irradiated with the laser signal light 18 to form an electrostatic latent image. At this time, the exposure potential of the photoconductor 19 is -50.
V. On the surface of the photoconductor 19, a two-component developer 2
6Bk was applied by magnetic force in the developer hopper 23.
Next, the surface of the photoconductor 19 was passed in front of the collection electrode roller 27. When the photosensitive member 19 passes through an uncharged area, the electrode roller 27 is superimposed with a DC voltage of +100 V by an AC high-voltage power supply 30 to 750 V0-p (peak-to-peak 1.
5 kV) (a rectangular wave having a frequency of 2 kHz) was applied. After that, when passing through the surface of the photoconductor 19 on which the electrostatic latent image has been written and charged to -450 V, the electrode roller 27 is 750 V0-p (peak-to-peak) in which a DC voltage of -250 V is superimposed by the AC high voltage power supply 30. 1.5kV peak)
(A rectangular wave having a frequency of 2 kHz) was applied. Then, the developer on the photoconductor 19 and the toner adhering to the non-image portion were collected by the electrode roller 27, and a negative-positive toner image was left on the photoconductor 19 only in the image portion. The developer and toner adhering to the electrode roller 27 rotating in the direction of the arrow were scraped off by the scraper 29, returned to the developer hopper 23 again, and used for the next image formation. Thus, the photoconductor 1
A black toner image was obtained on No. 9. Similar operations are performed for the other image forming units 13C, 13M, and 13Y other than black.

Next, returning to FIG. 1, the operation of the apparatus when forming a color image will be described. The image forming unit group 14 is at the position shown in FIG. 1, and the black image forming unit 13Bk is at the image forming position 17 as shown. At this time, the photoconductor 19 is in contact with the intermediate transfer belt 3. In the image forming step of the image forming unit described above, the black signal light is input to the image forming unit 13Bk by the laser exposure device 40, and the image is formed by the black toner. At this time, the intermediate transfer belt 3
Is set to be 1.5% faster than the speed of the photoreceptor 19 in order to prevent the center transfer of the toner image, and is applied to the first transfer roller 4 and the tension roller 12 simultaneously with the image formation. The black toner image is transferred onto the intermediate transfer belt 3 by the action of the applied voltage. At this time, +2.5 k is applied to the first transfer roller 4 and the tension roller 12 as described above.
V DC voltage was applied.

Immediately after all the black toner images have been transferred, the first transfer roller 4 moves from the position 4a shown in FIG.
And the intermediate transfer belt 3 returns to a position where it does not come into contact with the image forming unit 13Bk. Next, the entire image forming unit group 14 is driven by the moving motor 15 to
, And stops at the position where the image forming unit 13C reaches the image forming position 17 by rotating exactly 90 °. Toner hopper 23 other than the photoreceptor of the image forming unit
And the portion of the cleaner 31 are located inside the rotational arc indicated by the dotted line at the tip of the photoconductor 19. The retreat position 4b of the first transfer roller 4 is located outside the dotted arc.
Therefore, the intermediate transfer belt 3 does not come into contact with the image forming units during the rotational movement of the image forming unit group.

When the rotation of the image forming unit group 14 is completed and the image forming unit 13C reaches the image forming position 17, the laser exposure device 40 inputs signal light to the image forming unit 13C with a cyan signal as before. Then, formation and transfer of a cyan toner image are performed. By this time, the intermediate transfer belt 3 has made one revolution, and the signal from the position detector 11 shown in FIG. The timing of writing the cyan signal light is controlled based on the timing. During this time, the third transfer roller 34 is in contact with the intermediate transfer belt 3, but as described above, the surface of the third transfer roller is smooth and a voltage of -1 kV is applied to prevent the toner from adhering. Therefore, the toner image on the intermediate transfer belt 3 is not disturbed. Although the cleaning roller 6 is also in contact with the intermediate transfer belt 3, the surface of the cleaning roller 6 is also smooth,
In addition, since a voltage of -1 kV is applied to prevent the toner from adhering, the toner image on the intermediate transfer belt 3 is not disturbed.

The same operation as above was performed for magenta and yellow, and a color image was formed by superimposing four color toner images on the intermediate transfer belt 3 so as to coincide with each other. After the transfer of the last yellow toner image, the toner images of the four colors were collectively transferred to a sheet (not shown) fed from a sheet feeding cassette in a timely manner by applying a voltage of +3 kV to the third transfer roller 34. The toner image transferred to the paper was fixed by fixing rollers 45a and 45b, and then discharged.

Thereafter, the third transfer roller 34 is again charged by -1k.
After applying the voltage of V to transfer the toner directly adhered to the surface of the third transfer roller to the intermediate transfer belt 3, the cleaning roller 6 is applied with +3 kV together with the transfer residual toner remaining on the intermediate transfer belt 3. And the toner was stored in a waste toner reservoir 8 in the intermediate transfer unit 2.

When such a printing operation was repeated for about 30,000 sheets, the waste toner reservoir 8b became full, and the waste toner full detector 9 constituted by an optical sensor output a signal indicating that it was full. At this time, the intermediate transfer belt 3 was in a state where it could be used for about 10,000 prints, but the user was prompted to replace the intermediate transfer unit 2 based on the signal from the waste toner full detector 9.

The intermediate transfer unit 2 in a state where the waste toner reservoir 8b is full with waste toner is replaced as follows. The image forming unit group 14 is in the state shown in FIG.
The first transfer roller 4 is retracted to the position 4b shown in FIG. Therefore, the photoconductor 19 of the image forming unit 13Bk is
The apparatus has been stopped by moving to the retracted position where the intermediate transfer body unit 2 does not contact the intermediate transfer belt 3. The user opens the front plate 1A located at the front of the apparatus body, and takes out the intermediate transfer unit 2 therefrom. Next, a new intermediate transfer unit 2 in which the previously prepared position detector, waste toner full detector and the like have been adjusted is mounted. Therefore, after the unit is mounted, image formation can be started without any adjustment. When the new intermediate transfer unit 2 is mounted on the main body, the photoconductor 19 of the image forming unit 13Bk does not hit the intermediate transfer belt 3 or the first transfer roller 4 and is not damaged.

The above is the description of the configuration and operation of the embodiment.
In the above embodiment, a specific structure of the image forming unit is used. However, the essence and the function and effect of the present invention are also applicable to an image forming unit having a structure using a conventional developing method or a charging method. Does not change. Further, such a configuration is not only effective for an intermediate transfer belt on which a toner image is directly formed, but is also effective for an intermediate transfer body having a configuration in which an image receiving paper is wound around. Nor.

[0037]

According to the present invention, the intermediate transfer member (intermediate transfer belt 3 in the embodiment) does not collide with the image forming unit when the image forming unit group is rotated. Do not hurt. Further, when the intermediate transfer body unit is replaced, the intermediate transfer body does not collide with the photoconductor and does not damage the photoconductor. A color image recording apparatus having a simple, compact configuration and good maintainability can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a positional relationship during image formation of a color electrophotographic apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating a configuration of an image forming unit used in a color electrophotographic apparatus according to an embodiment of the present invention.

FIG. 3 is a configuration diagram of an intermediate transfer body unit of the present invention.

FIG. 4 is a configuration diagram showing a configuration of a position detector of the intermediate transfer body unit of the present invention.

FIG. 5 is a configuration diagram of a conventional color electrophotographic apparatus.

[Explanation of symbols]

 2 Intermediate Transfer Unit 3 Intermediate Transfer Belt 4 First Transfer Roller 5 2nd Transfer Roller 6 Cleaning Roller 10 Backup Roller 12 Tension Roller 13 Image Forming Unit 14 Image Forming Unit Group 17 Image Forming Position 18 Laser Signal Light 19 Photoconductor 34 3 transfer roller 40 laser exposure device 43 mirror

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-138742 (JP, A) JP-A-62-296078 (JP, A) JP-A-62-287264 (JP, A) 72866 (JP, A) JP-A-4-199164 (JP, A) JP-A-4-110871 (JP, A) JP-A-3-191368 (JP, A) (58) Fields investigated (Int. ^7, DB name) G03G 15/01 - 15/01 117 G03G 15/16 G03G 15/00 550 G03G 21/16 - 21/18

Claims (2)

(57) [Claims] 1. A rotating body in which a plurality of individual units each having a toner storage section and a photoreceptor are arranged in a substantially annular shape and adjacent to each other in a detachable manner, and are exposed and developed on the photoreceptor. A color image recording apparatus that transfers the image to recording paper via an intermediate transfer belt housed in an intermediate transfer body unit, wherein the rotating body has a cylindrical space in the center thereof, and
Divided into a plurality of individual unit storage spaces with a substantially fan-shaped cross section,
The individual unit is detachably accommodated in each of the divided storage spaces, and optical path changing means for exposing the photoconductor by changing the optical path of the exposure laser beam is disposed in the cylindrical space. The belt is controlled to be movable to two positions, a retreat position not in contact with the photoconductor, and a transfer position in contact with the photoconductor, and when the rotating body rotates, the intermediate transfer belt is moved to the retreat position. A color image recording apparatus, wherein the photoconductor and the intermediate transfer belt are positioned so as not to contact with each other. 2. An individual unit used only in the color image recording apparatus according to claim 1, wherein the individual unit has a substantially fan-shaped cross section, and is detachably attached to the rotating body only from a direction perpendicular to a rotation axis of the rotating body. An individual unit characterized by the following.