JP3432792B2 - Color image recording device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention 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 In a general color electrophotographic method, a method of forming a color image by superposing toner images of yellow, magenta, cyan and black on a transfer material is adopted. As the color image forming method, a toner image of each color is sequentially formed on a single photoconductor, the transfer material wound around a transfer drum is rotated to repeatedly face the photoconductor, and each of the sequentially formed colors of the respective colors is formed. A transfer drum system in which toner images are transferred in a superimposed manner and a plurality of image forming units are arranged side by side,
A continuous superposition method is generally used in which toner images of respective colors are sequentially transferred to a transfer material conveyed by a belt through respective image forming portions, and color images are superposed.

A color image forming apparatus using the former transfer drum system is disclosed in Japanese Patent Application Laid-Open No. 1-252982. FIG. 8 shows an outline of the overall configuration of this conventional example, and the configuration and operation will be briefly described below. In FIG. 8, reference numeral 101 denotes a photoconductor, and the charging device 10 faces the photoconductor
2, developing unit 103, transfer drum 104, cleaner 1
05 is provided. The developing unit 103 includes a Y developing device 106 for forming a yellow toner image and a magenta M image.
Developing device 107, cyan C developing device 108, black Bk
The developing device 109 and the developing device 109 rotate so that each developing device sequentially faces the photoconductor 101 and is ready for development. While the transfer drum 112 and the photoconductor oppose each other during operation, they rotate in the direction of the arrow at a constant speed.

When the image forming operation is started, the photosensitive member 101 rotates in the direction of the arrow and the surface thereof is uniformly charged by the charger 102. Thereafter, the surface of the photoconductor is irradiated with a laser beam 110 modulated with a signal for forming a yellow image of the first color to form a latent image. Next, this latent image is first developed by the Y developing device 106 facing the photoconductor.
Is developed, and a yellow toner image is formed. The yellow toner image formed on the photoconductor is transferred to the transfer drum 104.
By the time it moves to the position facing the
On the outer periphery of 04, one sheet of paper as a transfer material sent from the sheet feeding section 111 is wrapped around with its front end grasped by the claw section 112, and a yellow toner image on the photoconductor is placed at a predetermined position on the sheet. Are timed so that they will meet face to face.

After the yellow toner image on the photoconductor is transferred to the sheet by the action of the transfer charger 113, the surface of the photoconductor is cleaned by the cleaner 105 to prepare the image formation of the next color. Subsequently, magenta, cyan, and black toner images are also formed in the same manner, but at that time, the developing unit 103 makes each developing device used according to the color face the photoconductor to be in a developable state. The diameter of the transfer drum is large enough so that the longest sheet of paper can be wound and the developing unit can be exchanged between images of each color.

Laser beam 110 for image formation of each color
The irradiation is performed with a timing such that the toner images of the respective colors on the photoconductor and the toner images already transferred to the sheet on the transfer drum are aligned and face each other as the toner rotates. In this way, the four color toner images are transferred to the transfer drum 10.
4 is transferred onto the paper in a superimposed manner to form a color image on the paper. After the toner images of all colors have been transferred, the sheet is peeled from the transfer drum 104 by the peeling claw 114, the toner image is fixed by the fixing unit 116 via the conveyance unit 115, and the sheet is discharged outside the apparatus.

On the other hand, as an example of a color image forming apparatus using a continuous transfer system, there is JP-A-1-250970. In this conventional example, four image forming stations each including a photoconductor, an optical scanning unit, and the like are arranged to form an image of four colors, and a sheet conveyed on a belt passes under the respective photoconductors to form a color image. The toner images are overlaid.

Furthermore, as another method for forming a color image by superimposing toner images of different colors on a transfer material, the toner images of respective colors sequentially formed on the photoconductor are once superposed on the intermediate transfer material, and finally. Japanese Patent Application Laid-Open No. 2-212867 discloses a method of collectively transferring the toner images on the intermediate transfer material onto a transfer paper.

[0009]

In the transfer drum system,
A transfer drum is used to align and superimpose toner images of different colors. The transfer drum is rotated at the same speed with respect to the photoconductor, and the timing of the leading edge of the image is adjusted to match the mutual positions of the toner images of the respective colors when a color image is formed. However, in the above configuration, since it is necessary to wind the paper around the transfer drum, the diameter of the transfer drum needs to be a certain size or more, and the structure is very complicated and high accuracy is required. Was large and expensive. Also, strong paper such as postcards and thick paper could not be used because it could not be wound around the transfer drum.

On the other hand, the continuous transfer system has an image forming position corresponding to the number of colors, and it suffices to pass the paper one by one therethrough. Therefore, such a transfer drum is unnecessary, but this system is used. In this case, a plurality of latent image forming means such as a laser optical system for forming a latent image on the photoconductor are required corresponding to the number of colors, and the structure is very complicated and expensive. Furthermore,
Since there are multiple image forming positions, relative misalignment of the image forming parts for each color, eccentricity of the rotation axis, deviation of the parallelism of each part, etc. directly affect the color misregistration, and it is difficult to stably obtain high image quality there were. In particular, it is necessary to accurately align the positions of the latent images by the latent image forming means.
As disclosed in the publication, there is a problem that the image exposure system, which is a latent image forming means, requires considerable devise and a complicated structure.

Further, Japanese Patent Laid-Open No. 2-2 using an intermediate transfer material
In the example of 12867, a plurality of developing devices must be arranged around a single photoconductor in order to form toner images of respective colors on the same photoconductor, and the shape of the photoconductor is inevitable. Became large, and the photoreceptor became a belt shape that was difficult to handle. Also, if each developing device is replaced during maintenance, matching adjustment with the characteristics of the photoconductor is necessary,
Since it was necessary to adjust the position between the photoconductors and the developing devices when the photoconductors were replaced, it was difficult to maintain the color developing devices and the photoconductors.

In view of the above problems, an object of the present invention is to provide a color image recording apparatus in which the structure of the intermediate transfer portion is small and simple, the maintainability is good, the transfer is stable, and the color misregistration does not occur.

[0013]

In order to achieve the above object, a color image recording apparatus of the present invention transfers an image formed on a photoconductor onto an intermediate transfer belt and further is provided on the apparatus side. In a color image recording apparatus for forming an image by transferring after being transferred to a recording sheet by a retransfer roller, an intermediate transfer belt which sequentially transfers color images of respective colors from the photoconductor, and a roller which gives a tension to the intermediate transfer belt. ,
And an intermediate transfer belt unit that has a pair of rollers that holds the nip amount between the intermediate transfer belt and the photosensitive member in contact with the end portion of the photosensitive member and that holds the intermediate transfer belt and the photosensitive member. A color image is transferred by repeating contact / separation with the body, and at the time of the contact / separation, the roller is prevented from bending while maintaining tension on the intermediate transfer belt. The nip amount between the intermediate transfer belt and the photoconductor is kept constant, and the roller is rotated through the rotary shaft to perform the intermediate transfer.
It is fixed to the side plate of the transfer belt unit, and
The second transfer roller, which is arranged opposite to the roller,
It is fixed to the side plate of the intermediate transfer belt unit .

As a result, even when the user attaches or detaches the intermediate transfer belt unit during maintenance, image formation can be started without special adjustment.
In addition, since the contact / separation is performed while the tension of the intermediate transfer belt is kept stable, and the pressure nip amount at the time of transfer is always constant, the contact between the photoconductor and the intermediate transfer belt is prevented.
The transfer performance does not change even with the separated structure. Well
Also, the rollers are the side plates of the intermediate transfer belt unit via the rotary shaft.
The second transfer roller, which is fixed to the
The image transfer roller is also mounted on the side plate of the intermediate transfer belt unit via the rotary shaft.
Fixed to. This also allows the second transfer roller and its
Correct placement of the retransfer roller facing the
The placement position is chained by this roller centering on the photoconductor
It is decided to be stable.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structures of a color image recording apparatus and an intermediate transfer belt unit of the present invention will be described with reference to FIG. 1 is an exterior casing of the color electrophotographic printer,
The right end face side in the drawing is the front face. Reference numeral 1A denotes a printer front plate, and the front plate can be freely opened and closed as shown by a dotted line with respect to the hinge shaft 1B on the lower side with respect to the printer outer casing 1, and raised and closed as shown by a solid line. The operation of attaching / detaching the intermediate transfer belt unit 2 to / from the printer and the inspection / maintenance of the inside of the printer at the time of paper jam are performed by tilting the front plate 1A open to largely open the inside of the printer.
The attachment / detachment operation of the intermediate transfer belt unit 2 is designed so as to be perpendicular to the direction of the rotation axis generatrix of the photoconductor.

The structure of the intermediate transfer belt unit 2 is shown in FIG. The intermediate transfer belt unit 2 includes a unit housing 2a, an intermediate transfer belt 3 and a first conductive elastic member.
The transfer roller 4, the second transfer roller 5 made of an aluminum roller, the tension roller 6 for adjusting the tension of the transfer belt, the belt cleaner roller 7 for cleaning the toner image remaining on the transfer belt, and the toner collected on the cleaner roller 7 It includes a scraping scraper 8, waste toner reservoirs 9a and 9b for storing the collected toner, and a position detector 10 for detecting the position of the transfer belt. This intermediate transfer belt unit 2 is shown in FIG.
A can be attached to and detached from a predetermined storage portion in the printer outer casing 1 by tilting and opening A as shown by a dotted line.

The intermediate transfer belt 3 is made of an endless belt-like film having a thickness of 100 μm and made of semi-conductive urethane as a base material, and is formed of a urethane foam having a low resistance treatment so as to have a resistance of 10 7 Ωcm in the periphery. It is configured to be wound around the first transfer roller 4, the second transfer roller 5, and the tension roller 6 so as to be movable in the arrow direction. Here, the peripheral length of the transfer belt is a length (62 mm) slightly longer than a half of the peripheral length of a photosensitive drum (diameter 30 mm), which will be described later, in the length (298 mm) in the longitudinal direction of A4 paper, which is the maximum paper size. Is set to 360 mm.

When the intermediate transfer belt unit 2 is mounted on the printer main body, the first transfer roller 4 is attached to the photosensitive member 11 (shown in FIG. 1) through the intermediate transfer belt 3 at about 1.0.
The second transfer roller 5 is pressed by a force of kg, and the second transfer roller 5 is pressed by a third transfer roller 12 (shown in FIG. 1) having the same structure as the first transfer roller 4 through the intermediate transfer belt 3. . The third transfer roller is configured to be driven and rotatable by the intermediate transfer belt 3.

The cleaner roller 7 is a roller of a belt cleaner section for cleaning the intermediate transfer belt 3. This is a configuration in which an AC voltage that electrostatically attracts toner is applied to a metallic roller. The cleaner roller 7 may be a rubber blade or a conductive fur brush to which a voltage is applied.

FIG. 3 is a perspective view showing the structure of the position detector 10 using a photo interrupter provided inside the intermediate transfer belt unit 2. There is a detection hole 13 at the end of the intermediate transfer belt 3, and the position detector 10 optically detects the passage of the detection hole 13 to position the color image on the intermediate transfer belt 3. Is.

FIG. 4 shows a structure for fixing three rollers of the intermediate transfer belt unit. 4 is a first transfer roller (diameter 30 mm), 5 is a second transfer roller (diameter 30 mm), 6
Is a tension roller (diameter 12 mm), 14 is those 3
It is a side plate for fixing the rollers of the book. Tension roller 6
Always applies tension to the intermediate transfer belt by the spring 15. As shown in the perspective view of FIG. 5, a diameter 28 smaller than the diameter of the first transfer roller by 2 mm is provided at both ends of the first transfer roller 4.
Two mm rollers 16 are attached. FIG. 6 shows how the intermediate transfer belt unit contacts the photoconductor. Reference numeral 11 denotes a photoconductor of the image forming unit, which is pressed against the first transfer roller 4 via the intermediate transfer belt 3. The degree of pressure contact at this time is defined by the roller 16, and the pressure contact is always performed with a constant value of the nip amount without being too strong or too weak. At this time, the intermediate transfer belt 3 is attached to the photoreceptor 1
Loosening is more likely to occur than when 1 is not in contact, but since the tension roller 6 is pushed up by the spring 15, it is possible to always maintain a constant tension even if the image forming unit changes. Therefore, it is possible to stably transfer the toner image on the photoconductor to the intermediate transfer belt, and it is possible to prevent the occurrence of color misregistration due to the bending of the intermediate transfer belt.

Returning again to FIG. Black in the center of the printer,
Four sets of fan-shaped image forming units 17Bk, 17C, 17M, and 17Y for each color of cyan, magenta, and yellow constitute an image forming unit group 18, and are arranged in an annular shape as shown in the drawing. Each image forming unit is attachable to and detachable from a predetermined position of the image forming unit group 18 by opening the printer top plate 1C of FIG. 1 around the hinge shaft 1D. Image forming unit 1
7 is properly installed in the printer so that the mechanical drive system and the electric circuit system on both sides of the image forming unit side and the printer side are mechanically coupled by mutual coupling members (not shown). Electrically integrated.

Image forming unit 1 arranged in an annular shape
7Bk, 17C, 17M and 17Y are supports (not shown)
A cylindrical shaft 2 which is supported by a moving motor 19 which is a moving means as a whole and which is fixed and does not rotate.
It is configured to be rotatable around 0. Each image forming unit has an image forming position 2 facing the second transfer roller 4 which supports the intermediate transfer belt 3 in sequence by rotational movement.
Can be located at 1. The image forming position 21 is also an exposure position by the laser signal light 22.

Since each image forming unit is composed of the same constituent members except the developer contained therein, the image forming unit 17Bk for black will be described and the other colors will be omitted for simplification of description. For each color,
The same portions are denoted by the same reference numerals, and when it is necessary to distinguish the configurations of the respective colors, the reference numerals are assigned with the letters indicating the respective colors. FIG. 7 shows the black image forming unit 17Bk in detail. In this explanation, the developing method disclosed by the inventors in Japanese Patent Application No. 4-50274 is used, but it goes without saying that any developing method may be used as long as it is used in a normal electrophotographic method. In FIG. 7, 11 is an organic photoconductor in which phthalocyanine is dispersed in a polycarbonate binder resin, 23 is a non-rotating magnet fixed coaxially with the photoconductor 11, 24 is a charging roller for negatively charging the photoconductor, and 22 is a laser signal. Light, 25 is an exposure window through which a laser beam enters the image forming unit, and 26 is a developer hopper. Developer hopper 26
The inside has a particle size of 50μ with the surface coated with silicone resin.
m of ferrite carrier 27Bk and two-component developer 29Bk in which black toner 28Bk in which black pigment is dispersed in polyester resin are mixed, and the magnetic force of magnet 23 is applied to photoreceptor 11
Attach to the surface. Reference numeral 30 is a rotatable collection electrode roller made of aluminum, 31 is a non-rotating magnet fixed coaxially therein, 32 is a scraper made of polyphenylene sulfide that scrapes off the toner on the collection electrode roller, 3
Reference numeral 3 is an AC high-voltage power supply that applies a voltage to the recovery electrode roller. Reference numeral 34 is a cleaner for cleaning the toner remaining on the surface of the photoconductor after the transfer. The diameter of the photoconductor 11 is 30 mm, and the recovery electrode roller 30 is rotated at a peripheral speed of 60 mm / s in the direction of the arrow.
Had a diameter of 16 mm and was rotated in the direction of the arrow at a peripheral speed of 60 mm / s.

Returning to FIG. 1, the description will be continued. Reference numeral 35 denotes a laser exposure device arranged in the lower side of the printer outer casing 1, which includes a semiconductor laser, a scanner motor 35a, and a polygon mirror 3.
5b, a lens system 35c and the like. The pixel laser signal light 22 corresponding to the time series electric pixel signal of the image information from the laser exposure device 35 is the image forming unit 1 of FIG.
After passing through the optical path window 36 formed between 7Bk and 17Y, the light enters the fixed mirror 38 in the shaft 20 through the window 37 opened in a part of the shaft 20, and is reflected to be in the image forming position 21. The photoconductor enters the image forming unit 17Bk from the exposure window 25 of the image forming unit 17Bk substantially horizontally, and passes through the passage between the developer hopper 26 and the cleaner 34 which are vertically arranged in the image forming unit. It is incident on the exposed portion of the left side surface of 11 and is scanned and exposed in the generatrix direction.

Here, since the optical path from the optical path window 36 to the mirror 38 utilizes the space between the adjacent image forming units 17Bk and 17Y, the image forming unit group 1
In 8 there is almost no wasted space. Also, mirror 3
Since the image forming unit group 8 is provided at the center of the image forming unit group 18, the image forming unit group 8 can be formed by a single fixed mirror, and the structure is simple and easy to align.

Reference numeral 12 denotes a third transfer roller provided inside the printer front plate 1A and above the feeding roller 39. The nip portion where the intermediate transfer belt 3 and the third transfer roller 12 are in pressure contact with each other is a printer. A sheet conveying path is formed so that the sheet is fed by the sheet feeding roller 39 provided below the front plate 1A.

Reference numeral 40 denotes a paper feed cassette provided on the lower side of the printer front plate 1A so as to project outward, and a plurality of papers S can be set at the same time. 41a and 41b are paper conveyance timing rollers, 42a and 42b are fixing roller pairs provided on the upper inside of the printer, 43 is a paper guide plate provided between the third transfer roller 12 and fixing roller pairs 42a and 42b, and 44a.
44b is a paper discharge roller pair arranged on the paper exit side of the fixing roller pairs 42a and 42b, 45 is a fixing oil reservoir for storing silicone oil 46 to be supplied to the fixing roller 42a, and 47 is silicone oil 46 applied to the fixing roller 42a. It is an oil supply roller. The above is the description of the main configuration of the electrophotographic apparatus of the present invention.

With the above structure, the intermediate transfer belt portion having a complicated structure can be unitized, so that when the intermediate transfer belt is deteriorated, the user can replace the entire unit and the maintainability becomes excellent.

Further, in a color image recording apparatus in which the photoconductor and the intermediate transfer belt repeat contact and separation as in the present invention, the intermediate transfer belt is liable to bend during contact and separation, but in the present invention, the intermediate transfer is always performed by the tension roller. The belt is tensioned so that color deviation due to bending does not occur.

Further, in the color image recording apparatus in which the photosensitive member and the intermediate transfer belt are repeatedly brought into contact with and separated from each other as in the present invention,
It is difficult to keep the pressure contact between the intermediate transfer belt and a plurality of different photoconductors constant, but in the present invention, since the roller is provided on the side of the first transfer roller to contact the photoconductor, the pressure contact nip amount is always constant. With the configuration, the transfer performance does not change for each color.

The operation of the color image recording apparatus of one embodiment of the present invention will be described below with reference to FIGS. 1 and 7.

First, the operation of the image forming unit will be described with reference to FIG. The photoconductor 11 is charged by the charging roller 24 at -500V.
Charged to. Laser beam scanning light 2 is applied to the photoconductor 11.
2 was irradiated to form an electrostatic latent image. At this time, the exposure potential of the photoconductor was -100V. On the surface of this photoreceptor 11,
The two-component developer 29Bk was attached in the developer hopper 26 by magnetic force. Next, the surface of the photoconductor 11 is covered with the collecting electrode roller 3.
Passed in front of 0. When passing through the uncharged area of the photoconductor 11, the AC high voltage power supply 33 causes the electrode roller 30
An AC voltage of 750 V 0-p (peak-to-peak 1.5 kV) superimposed with a DC voltage of 00 V (rectangular wave of frequency 3 kHz) was applied. After that, when the surface of the photoconductor 11 charged with −500V and having the electrostatic latent image written thereon is passed, 750V 0-p (peak-to-peak) in which a DC voltage of −300V is superposed on the electrode roller 30 by an AC high-voltage power supply 33. AC voltage with a peak of 1.5kV (rectangular wave with a frequency of 3kHz)
Was applied. Then, the developer on the photoconductor 11 and the toner attached to the non-image portion were collected by the electrode roller 30, and the negative-positive inverted toner image remained only on the image portion on the photoconductor 11. The developer and toner attached to the electrode roller 30 rotating in the direction of the arrow are scraped off by the scraper 32,
It was returned again to the developer hopper 26 and used for the next image formation. Thus, a black toner image was obtained on the photoconductor 11. The same operation was performed for the image forming units 17C, 17M, and 17Y other than black.

Next, the operation of the apparatus of FIG. 1 when forming a color image will be described. Initially, the image forming unit group 18 is in the position shown in FIG. 1 and the black image forming unit 17Bk is in the image forming position 21 as shown. At this time, the photoconductor 11 is in contact with the first transfer roller 4 via the intermediate transfer belt 3 so as to face the first transfer roller 4. As for the contact state at this time, the surface of the first transfer roller 4 as shown in FIG. 6 is dented by the photoconductor 11, and the roller 16 is in contact with the side end portion of the photoconductor 11. The bending of the intermediate transfer belt 3 at this time was absorbed by the tension roller 6. Return to FIG. 1 again. In the image forming process of the image forming unit described above, the black signal light is input to the image forming unit 17Bk by the laser exposure device 35, and the image is formed by the black toner. At this time, the image forming unit 17B
k image forming speed (60 mm / equal to the peripheral speed of the photoconductor)
s) and the moving speed of the intermediate transfer belt 3 are set to be the same, and the black toner image is transferred to the intermediate transfer belt 3 by the action of the first transfer roller 4 simultaneously with the image formation. At this time, a DC voltage of +1 kV was applied to the first transfer roller. Immediately after all the black toner images have been transferred, the image forming units 17Bk, 17C, 17M, and 17Y are wholly driven by the moving motor 19 as the image forming unit group 18 and rotationally move in the arrow direction of FIG. The image forming unit 17C rotates 90 degrees and stops at the position where it reaches the image forming position 21. During this time, the portions of the developer hopper 26 and the cleaner 34 other than the photoconductor of the image forming unit are located inside the rotation arc of the tip of the photoconductor 11, so that the intermediate transfer belt 3 does not contact the image forming unit. .

After the image forming unit 17C arrives at the image forming position 21, the laser exposure device 35 inputs the signal light to the image forming unit 17C by the cyan signal as before, and the cyan toner image is formed and transferred. Done. By this time, the intermediate transfer belt 3 has rotated once, so that the next cyan toner image is positionally aligned with the previously transferred black toner image.
The writing timing of the cyan signal light is controlled based on the signal from the position detector 10 shown in FIG. During this time,
The third transfer roller 12 and the cleaner roller 7 are slightly apart from the intermediate transfer belt 3 and are configured so as not to disturb the toner image on the transfer belt.

The same operation as described above was performed for magenta and yellow, and toner images of four colors were positionally superposed on each other on the intermediate transfer belt 3 to form a color image. After the final transfer of the yellow toner image, the four color toner images were collectively transferred onto the paper fed from the paper feed cassette 40 at the same timing by the action of the third transfer roller 12. At this time, the second transfer roller 5 is grounded, and the third transfer roller 12 is
A DC voltage of +1.5 kV was applied to. The toner image transferred onto the sheet was fixed by the pair of fixing rollers 42a and 42b. The sheet is then discharged to the outside of the apparatus via the pair of discharge rollers 44a and 44b. The transfer residual toner remaining on the intermediate transfer belt 3 is cleaned by the action of the cleaner roller 7 to prepare for the next image formation.

Next, the operation in the monochromatic mode will be described. In the single color mode, the image forming unit of a predetermined color first moves to the image forming position. Next, as in the previous case, image formation of a predetermined color and transfer to the intermediate transfer belt 3 are performed, and this time, after the transfer, the operation is continued as it is, and the next third transfer roller 12 causes the paper feed cassette 40
I transferred it to the paper sent from and fixed it as it was.

Next, the maintenance of this device will be described. When the developer of a specific color is consumed and maintenance is performed, first, the image forming unit group 18 is rotated by the action of the moving motor 19 so that the image forming unit of the color of interest is located at the upper position (image of FIG. 1). Position of forming unit 17C)
Move to. And the cover 1D located on the upper part of the device body
Open, and the image forming unit of interest is taken out of the apparatus. Next, a new image forming unit whose image density has been adjusted in advance is attached. As a result, after mounting the image forming unit, image formation can be started without any adjustment.

The intermediate transfer belt 3 has a life of about 30,000 pages. The waste toner accumulated up to this time is stored in the waste toner reservoirs 9a and 9b. The user opens the cover 1A located on the front surface of the apparatus main body, and takes out the intermediate transfer belt unit 2 from the apparatus. Next, a new unit whose cleaner has already been adjusted is mounted as an intermediate transfer belt unit. Therefore, after mounting the unit, image formation can be started without any adjustment.

The above is the description of the configuration and operation of the embodiment.
In the above embodiments, the specific structure of the image forming unit was used. However, the essence and effects of the present invention may be changed even in the case of an image forming unit having a structure using a conventional developing method. Absent.

[0041]

As described above, the present invention can provide an intermediate transfer belt unit used in a color image recording apparatus having a small and simple structure of the intermediate transfer portion and having good maintainability. In addition, since the contact / separation is performed while the tension of the intermediate transfer belt is kept stable and the pressure contact nip amount at the time of transfer is always constant, the transfer performance can be improved even when the photosensitive member and the intermediate transfer belt are contacted / separated. It never changes. In addition, the roller is connected to the intermediate transfer belt unit via the rotary shaft.
Fixed to the side plate and facing the retransfer roller
The second transfer roller is also connected to the intermediate transfer belt unit via the rotary shaft.
It is fixed to the side plate, and the second transfer roller and
The correct position of the transfer roller in the color device is
Stable in a chained manner with this body centered on the body
To be done.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a color image recording apparatus using an intermediate transfer belt unit of the present invention.

FIG. 2 is a configuration diagram of an intermediate transfer belt unit of the present invention.

FIG. 3 is a perspective view showing a configuration of a position detector of the intermediate transfer belt unit of the present invention.

FIG. 4 is a configuration diagram showing how to apply tension to the intermediate transfer belt of the intermediate transfer belt unit of the present invention.

FIG. 5 is a perspective view showing rollers at an end portion on the transfer roller side used in the intermediate transfer belt unit of the present invention.

FIG. 6 is an explanatory diagram showing how to apply tension when the intermediate transfer belt and the photosensitive member of the intermediate transfer belt unit of the present invention are in contact with each other.

FIG. 7 is a configuration diagram showing a configuration of an image forming unit used in a color image recording apparatus according to an embodiment of the present invention.

FIG. 8 is a configuration diagram of a conventional color image forming apparatus.

[Explanation of symbols]

2 Intermediate transfer belt unit 3 Intermediate transfer belt 4 First transfer roller 5 Second transfer roller 6 Tension roller 11 photoconductor 12 Third transfer roller 15 spring 16 roller 17Bk / 17C / 17M / 17Y Image forming unit 18 Image forming unit group 21 Image formation position 22 Laser signal light 35 Laser exposure device 38 mirror

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-3-191368 (JP, A) JP-A-4-110871 (JP, A) JP-A-1-316774 (JP, A) JP-A-63- 75773 (JP, A) JP 5-158361 (JP, A) JP 5-53410 (JP, A) (58) Fields investigated (Int.Cl. 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 color image recording apparatus for transferring an image formed on a photoconductor to an intermediate transfer belt, further transferring to a recording sheet by a retransfer roller provided on the apparatus side, and then fixing the image to form an image. In which the intermediate transfer belt that sequentially transfers color images of the respective colors from the photoconductor and a roller that applies tension to the intermediate transfer belt are housed, and the intermediate transfer belt contacts the end of the photoconductor and the intermediate transfer belt and the intermediate transfer belt. An intermediate transfer belt unit having a pair of rollers for making the nip amount with the photosensitive member constant is provided, and a configuration is performed in which the contact and separation between the intermediate transfer belt and the photosensitive member are repeated to transfer a color image, At the time of contact / separation, the roller prevents the intermediate transfer belt from being bent while maintaining tension, while at the time of contact, the rollers cause the intermediate transfer belt and The nip amount with the photoconductor is kept constant, and the roller is rotated through the rotation shaft to the intermediate transfer belt unit.
It is fixed to the side plate and is placed facing the retransfer roller.
The second transfer roller is rotated and the intermediate transfer belt is
A color image recording device, characterized in that it is fixed to the side plate of the unit. 2. An intermediate transfer belt unit used only in the color image recording apparatus according to claim 1, wherein the intermediate transfer belt unit is arranged so as to face the photoconductor and sequentially transfers color images of respective colors from the photoconductor. A roller for applying a tension to the intermediate transfer belt, and a pair of rollers for contacting the end portion of the photosensitive member to keep the nip amount between the intermediate transfer belt and the photosensitive member constant. Intermediate transfer belt unit.