JP2000172041A - Color image recording device - Google Patents

Abstract

(57) [Problem] To provide a color electrophotographic apparatus which is small, can perform all operations from the front, and has low maintenance. SOLUTION: A plurality of image forming units 21Y, M, C,
Bk, an image forming unit group 22, a laser exposure device 44 disposed outside the image forming unit group 22, and a toner image formed on the photoconductor 27 at the image forming position 25 to receive a color image. An intermediate transfer belt unit 2 having an intermediate transfer belt 4 to be formed therein, and a retransfer roller 43 as a retransfer unit for transferring a color image formed on the intermediate transfer belt 4 to a recording sheet 42 at a retransfer position. And a laser exposure device 44 having at least three sides formed by the image forming unit group 22, the intermediate transfer belt unit 2, and a paper guide 54 as a paper transport path for transporting the recording paper 42 from the paper feeding position to the retransfer unit. It is provided with a configuration to be arranged in an enclosed space.

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 an example of a conventional color image recording apparatus,
The configuration will be described with reference to JP-A-7-36246. FIG. 7 is an overall configuration diagram of the conventional color image recording apparatus. The intermediate transfer belt unit 101 includes a transfer belt 102, a first transfer roller 103, and a second transfer roller 10.
4. A cleaner roller 105, a waste toner reservoir 106, and the like are included, and a color image is superimposed on the belt 102.
In the center of the printer, four fan-shaped image forming units 107 of the same size for each color of black, cyan, magenta, and yellow.
Bk, 107Y, 107M, and 107C constitute the image forming unit group 108, and are arranged in an annular shape as shown in the figure.

When the image forming unit 107 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, and the And electrical integration. Image forming unit 107B arranged in an annular shape
k, 107Y, 107M, and 107C are supported by a support, are driven by a moving motor as a whole, and are configured to be rotatable about a fixed, non-rotating cylindrical shaft 109. At the time of image formation, each image forming unit can be sequentially positioned at an image forming position 110 facing the first transfer roller 103 that supports the intermediate transfer belt 102 by rotational movement. The image forming position 110 is the laser light 1
11 is also the exposure position.

Reference numeral 112 denotes a laser exposure device disposed on the lower side of the printer. The laser signal light 111 is supplied to an optical path window 11 formed between the image forming units 107M and 107C.
3, the light enters a fixed mirror 114 in the shaft 109 through a window opened in a part of the shaft 109, is reflected and is reflected from the exposure window 115 of the image forming unit 107Bk at the image forming position 110 to the image forming unit. 107Bk, and the developing device 1 disposed vertically in the image forming unit
The light passes through an optical path between the photoconductor 16 and the cleaner 117 and is incident on an exposure portion on the left side surface of the photosensitive drum 118, and is scanned and exposed in the generatrix direction.

The toner image formed on the photoreceptor 118 is transferred to the transfer belt 102, and then the image forming unit group 10
8 rotates 90 degrees, and the yellow image forming unit 107
Y is replaced with the image forming position 110. The same operation as in the previous black step is performed, and the yellow toner image is superimposed on the black toner image on the intermediate transfer belt 102. The same operation is further performed using magenta and cyan image forming units, and after a full-color image is completed on the intermediate transfer belt 102, the third operation is performed.
The color image is transferred to the paper by the transfer roller 119, and is fixed by the fixing device 120. This is the configuration of JP-A-7-36246.

[0006]

With the recent spread of personal computers and the like, this color image recording apparatus is required to be able to be used on a desktop without taking up space.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a color image recording apparatus which is compact, can perform all operations from the front, and has low maintenance.

[0008]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention provides a plurality of image forming units each including a developing unit, a charging unit, and a photosensitive member for each color, and a printer including the plurality of image forming units. While holding detachably to the main body,
An image forming unit group which is arranged in an annular shape and is rotatable to an image forming position and other positions, a laser exposure device arranged outside the image forming unit group, and a substantially central portion of the image forming unit group. An intermediate transfer belt unit having a center mirror disposed therein, an intermediate transfer belt for receiving a toner image formed on the photoreceptor at the image forming position and forming a color image, and an intermediate transfer belt formed on the intermediate transfer belt Retransfer means for transferring the formed color image to recording paper at the retransfer position, and at least three of the laser exposure devices are used to move the image forming unit group, the intermediate transfer belt unit, and the recording paper from the paper feed position. It is provided with a configuration in which it is arranged in a space surrounded by a paper transport path for transporting to the retransfer unit.

Further, according to the present invention, there is provided a paper feed unit for storing recording paper, and the laser exposure device is arranged in a space surrounded by the image forming unit group, the intermediate transfer belt unit, the paper transport path, and the paper feed unit. It is provided with such a configuration.

Further, according to the present invention, at the time of image recording, a laser beam is reflected from a center mirror to interpose a path to an image forming position, and a laser beam is applied from a side opposite to a developing device acting on a photoconductor at the image forming position. It has a configuration in which light enters a center mirror.

Further, the present invention provides a laser exposure apparatus comprising a polygon mirror, wherein a rotation surface of the polygon mirror is inclined with respect to a horizontal plane, and the inclination angle is 60 degrees or less. It is.

Further, according to the present invention, a belt cleaning means for removing the toner remaining on the intermediate transfer belt is provided inside the intermediate transfer belt unit, and the laser light emission window of the laser exposure device is provided in the image forming unit in the side view of the printer body. The image forming apparatus has a configuration in which it is disposed between a vertical line on the image forming position side with respect to the outermost envelope of the group and a vertical line from the cleaning position of the intermediate transfer belt by the belt cleaning unit.

Further, according to the present invention, the intermediate transfer belt unit is configured to be detachable from the printer main body, the retransfer means is a retransfer roller provided on the printer main body, and the intermediate transfer belt unit is stored in a predetermined storage space. A belt unit guide means for guiding the intermediate transfer belt unit to a position, and a backup roller for contacting the intermediate transfer belt unit with a retransfer roller. The configuration is such that the direction of the pressing force when the transfer roller contacts the backup roller is substantially perpendicular to the direction of the pressing force.

Further, the present invention is configured such that the intermediate transfer belt unit has a sectional shape narrowing toward the center mirror.

Further, the present invention includes an intermediate mirror that folds the laser light toward the center mirror, so that the intermediate mirror and the center mirror make the laser light applied to the photosensitive member at the image forming position substantially Z-shaped. It is provided with a configuration to be folded back.

Further, according to the present invention, an intermediate transfer belt unit is configured to be detachable from a printer main body, an openable and closable front plate, an opening opening when the front plate is opened, an intermediate transfer belt unit, Belt unit guide means for guiding the intermediate transfer belt unit to a predetermined storage position by engaging the belt. The guide direction of the intermediate transfer belt unit by the belt unit guide means is from the horizontal direction around the center mirror to the upper end of the opening. It is provided with a configuration to be a range.

Further, the present invention includes an image forming unit guide, and an image forming unit guide means for engaging the image forming unit with the image forming unit and guiding the image forming unit to a predetermined position of the image forming unit group. The configuration is such that the guide direction of the image forming unit by the guide means is in a range of 30 degrees or more and 90 degrees or less with respect to the guide direction of the intermediate transfer belt unit.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

(Embodiment 1) The structure of a color electrophotographic apparatus according to the present invention will be described with reference to FIGS. 1
Denotes a printer main body of the color electrophotographic apparatus, and the right end side of the drawing is the front of the apparatus. 1A is a printer front plate,
The front plate 1A can be freely opened and closed and raised and closed with respect to the printer exterior housing 1D about the hinge shaft 1B on the lower side. FIG. 2 shows a state where the front plate 1A is folded down and opened.
Maintenance inside the printer, such as when a paper jam occurs, is performed by opening the front plate 1A to open the printer greatly. FIG. 3 shows the intermediate transfer belt unit 2. The intermediate transfer belt unit 2 includes a unit case 3,
Transfer belt 4, transfer guide roller 9, retransfer backup roller 6, drive roller 8, tension roller 5, waste toner reservoir 10, waste toner full detector 11, position detector 1
2. Consists of a cleaner unit 15.

The intermediate transfer belt unit 2 has a center mirror 4 formed by two surfaces 3A and 3B of a unit case 3.
It has a cross-sectional shape narrowing toward 9. The driving roller 8 is disposed above the transfer guide roller 9, the re-transfer backup roller 6, and the tension roller 5, and obtains a driving force by a driving unit (not shown) of the printer main body 1.
The intermediate transfer belt 4 is configured to be driven in the direction of arrow Y. Further, the drive roller 8 is disposed so as to protrude forward (to the right in the drawing) from the retransfer backup roller 6 so as to form an overhang portion 4A on the intermediate transfer belt 4 from the retransfer backup roller 6 toward the drive roller 8. I have. The cleaner unit 15 includes a cleaning blade 7, a toner receiver 17, and a cam follower 16, and is mounted to be swingable around a swing shaft 18.

The cleaner unit 15 is arranged such that the cleaning blade 7 is brought into contact with the drive roller 8 via the intermediate transfer belt 4 by means such as a spring (not shown).
It is configured to receive an urging force. Printer body 1
The intermediate transfer belt unit 2 is provided with a cam follower 16 when the intermediate transfer belt unit 2 is mounted on the printer body 1.
And is configured to engage with. Cleaner unit 1
5 and the waste toner reservoir 10 are communicated through a communication port 19, and the waste toner scraped off by the cleaning blade 7 by a known means such as a screw shaft is disposed on the inner peripheral side of the intermediate transfer belt 4. It is configured to be transported to the reservoir 10.

The intermediate transfer belt 4 is made of an endless belt-like semiconductive (medium resistance) urethane having a thickness of 100 μm, and the surface layer is made of a fluororesin such as PFA / PTFE and has a total thickness of 100 to 500 μm. It consists of a film.

The intermediate transfer belt 4 is set so that the circumferential length of the transfer belt is set to the maximum length of the A4 image receiving paper (297 mm) in the longitudinal direction (297 mm) in order to perform A4 size or letter size full color printing. Length (80m) that is slightly longer than half the circumference of the body drum (diameter 30mm)
m) plus 377 mm. At this time, the peripheral length of the intermediate transfer belt 4 from the retransfer position of the retransfer backup roller 6 to the contact portion of the drive roller 8 with the cleaning blade 7 is shorter than the distance of 80 mm, and is 75 m.
m.

The moving speed of the intermediate transfer belt 4 is 1.5 times lower than the image forming speed of the image forming unit (100 mm / s which is equal to the peripheral speed of the photosensitive member) in order to prevent the transfer of the toner image into the center.
% Faster.

When transferring the toner image on the photosensitive member, a voltage of about +2.5 kV (100 μA) is applied to the transfer guide roller 9 and the tension roller 5 by a high-voltage power supply (not shown). At this time, if the transfer guide roller 9 is brought into contact with the photosensitive member to transfer the toner image to the intermediate transfer belt 4, a so-called "front jump" phenomenon occurs before the intermediate transfer belt 4 contacts the photosensitive member, and the image is disturbed. In addition, it becomes difficult to uniformly adjust the contact pressure between the transfer guide roller 9 and the photosensitive member. However, such a problem does not occur in the configuration in which the intermediate transfer belt 4 stretched between the transfer guide roller 9 and the tension roller 5 is brought into contact with the photosensitive drum as in the present embodiment.

The diameter of the drive roller 8 and the retransfer backup roller 6 is 30 mm. The diameter of the tension roller 5 and the transfer guide roller 9 is 15 mm. The peripheral length of the intermediate transfer belt 4 is configured to be an integral multiple of the outer peripheral length of each roller, thereby preventing color shift of each color. Reference numeral 20 shown in FIG. 4 is a detection hole for detecting the position of the belt. The position detector 12 is configured to optically detect the passage of the detection holes 20 to determine the position of the leading end of the toner image, and to position the color image on the intermediate transfer belt 4.

Here, a transmission type position detecting means is used as the position detecting means, but it goes without saying that a detecting means other than the optical type, such as a mechanical type, an electric type or a magnetic type may be used.

On both sides of the intermediate transfer belt unit 2,
As shown in FIG. 2, rib-shaped guide grooves 61 and 62 are provided as guide means for mounting on the printer main body 1. Guide pins 63 and 64, which are guide means, are provided on the printer body 1 side.
The intermediate transfer belt unit 2 guides the intermediate transfer belt unit 2 in the direction of arrow R by engaging with 62. Reference numeral 71 denotes an opening that is opened when the front plate 1A is folded down and opened. The opening 71 also serves as an insertion opening for the intermediate transfer belt unit 2. 65 is a horizontal line drawn from the center mirror 49, 66 is the center mirror 4
9 is a line connecting 9 to the upper end 57 of the opening 71. The intermediate transfer belt unit 2 is configured to be inserted into the printer main body 1 from between the horizontal line 65 and the line 66.

In the center of the left side of the printer, yellow, magenta,
Four substantially fan-shaped image forming units 21Y, 21M, 21C, and 21Bk for the respective colors of cyan and black form an image forming unit group 22, and are arranged in an annular shape as shown in the figure.
Each image forming unit is detachable at a predetermined position of the image forming unit group 22 by opening the printer upper plate 1C of FIG. 2 and opening the insertion port 72 of the image forming unit 21.

When the image forming unit 21 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). To combine mechanically and electrically. As shown in FIG. 2, guide pins 67 and 68 are provided on both sides of the image forming unit 21 as guide means for mounting the image forming unit 21 on the printer main body 1. A support (not shown) for supporting the image forming unit 21 is provided on the printer body 1 side, and the support is provided with guide grooves 69 and 70 as guide means. The guide pins 67 and 68 engage with the guide grooves 69 and 70 to guide the image forming unit 21 in the direction of arrow T.

Image forming unit 2 arranged in an annular shape
1Y, 21M, 21C and 21Bk are supported by a support, and are driven by a moving motor 23 as a moving means as a whole of the image forming unit group 22, and are rotatable around a fixed and non-rotating cylindrical shaft 24. Is configured. At the time of image formation, each image forming unit is rotated by a transfer guide roller 9 for sequentially supporting the intermediate transfer belt 4.
The image forming position 25 can be located at the image forming position 25 opposite to the transfer position between the roller and the tension roller 5. The image forming position 25 is also an exposure position by the pixel laser signal light 26, and the image forming unit performs an image forming operation only at this position, and does not operate at other positions.

FIG. 5 shows a black image forming unit 21Bk and yellow, magenta and cyan image forming units 21Y and 21B.
M and 21C are shown. Each image forming unit differs only in the developer contained therein. Since the other components are the same, the image forming unit 21B for black is used to simplify the description.
k will be described 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 FIG. 5, 26 is a pixel laser signal light also shown in FIG. 1, 27 is an organic photoreceptor mainly composed of a polycarbonate-based binder resin using phthalocyanine as a photosensitive material, and 28 is a negatively charged photoreceptor. A corona charger, 29 is a grid for controlling the charging potential of the photosensitive member to be constant, 30 is an exposure window which is an opening of the image forming unit through which the laser beam enters the image forming unit, and 31Bk is a black developing device. The developing device 31 includes a toner hopper 32 and a developing roller 3.
3, a magnet 34, a doctor blade 35 and the like. In the toner hopper 32, a black toner 36Bk of negative charge having a black pigment dispersed in a polyester resin is contained.

This black toner is mixed with a ferrite carrier having a particle diameter of 50 μm, the surface of which is coated with a silicone resin, and is carried as a two-component developer 37Bk on the surface of the developing roller 33 to develop the photoreceptor 27. 38 is a photoreceptor 2 after transfer
7 is a cleaner for cleaning toner remaining on the surface, and includes a cleaning blade 39 made of rubber and a waste toner reservoir 40 for storing waste toner. The photoreceptor 27 has a diameter of 30 mm and rotates in the direction of the arrow at a peripheral speed of 100 mm / s, and the developing roller 33 has a diameter of 16 mm and rotates at a peripheral speed of 140 mm / s. The fan-shaped spread angle of the image forming unit 21 is 90 degrees, which includes a cleaner section 38 of about 30 degrees and a developing unit 31 of about 6 degrees.
0 degrees.

Next, returning to FIG. Reference numeral 41 denotes a static elimination needle for preventing a toner image from being disturbed when the recording paper 42 is separated from the intermediate transfer belt 4. Reference numeral 43 denotes a retransfer roller serving as a retransfer unit, which is configured to abut on the retransfer backup roller 6 via the intermediate transfer belt 4. The retransfer roller 43 is configured to be rotatable 1.5% slower than the intermediate transfer belt 4 in order to prevent a dropout phenomenon when transferring a toner image. The arrow S indicates the contact direction of the retransfer roller 43 with the retransfer backup roller 6. The direction of the arrow S is configured to be perpendicular to the direction of the arrow R. For this reason, the guide groove 6
If the clearance between the first and second guide rollers 63 and 64 is set appropriately, the intermediate transfer belt 4 and the photosensitive member 2 at the transfer position can be used even if the re-transfer roller 43 is separated or moved during the image forming operation.
7 is hardly displaced.

Reference numeral 53 denotes a paper feed unit which stores the recording paper 42 and is mounted on the lower part of the main body. Reference numeral 54 denotes a paper guide as a paper transport path for transporting the recording paper 42 from the paper feed unit 53 to the retransfer roller 43. 50 is a feeding roller.

Reference numeral 44 denotes a laser exposure device, which includes a semiconductor laser (not shown), a polygon mirror 45, a lens system 46,
It is composed of an intermediate mirror 47, a laser light emission window 55 and the like. The laser exposure device 44 is arranged such that the rotation surface of the polygon mirror 45 is positioned relative to a horizontal plane in a space surrounded by the image forming unit group 22, the intermediate transfer belt unit 2, the paper supply unit 53, and the paper guide 54 in the printer outer housing 1D. 4
It is arranged in a posture tilted twice. The intermediate mirror 47 is mounted so that its reflection surface faces downward by 12 degrees from the horizontal direction. 56C shows the outermost envelope when the image forming unit group 22 rotates and moves, and 56A shows the outermost envelope 56
A vertical line on the image forming position 25 side with respect to C is shown.

Reference numeral 56B denotes a vertical line from the contact position of the cleaning blade 7. Laser light emission window 5
5 is configured to be disposed between the vertical line 56A and the vertical line 56B. Reference numeral 49 denotes a center mirror, which is fixed in the shaft 24 such that its reflection surface faces down three degrees from the horizontal direction. The pixel laser signal light 26 corresponding to the time-series electrical pixel signal of the image information from the laser exposure device 44 enters the intermediate mirror 47 at an elevation angle of 42 degrees. The pixel laser signal light 26 reflected by the intermediate mirror 47 passes through the optical path window 48 formed between the cleaner 38Y of the yellow image forming unit 21Y and the developing device 31M of the magenta image forming unit 21M, and passes through the shaft 24. Incident on the center mirror 49 at an elevation angle of 18 degrees through a window opened in a part of
The image forming unit 21Y that is reflected and is at the image forming position 25
From the exposure window 30 into the image forming unit 21Y, and passes through a passage between the developing device 31Y and the cleaner 38Y which are disposed vertically in the image forming unit to the exposed portion on the left side surface of the photoreceptor 27Y. It is incident at an elevation angle of 12 degrees and is scanned and exposed in the generatrix direction.

Here, the optical path window 48 to the center mirror 4
Since the optical path up to 9 utilizes the gap in the wall surface between the image forming units 21Y and 21M, the image forming unit group 22 has little wasted space. In addition, since the center mirror 49 is provided at the center of the image forming unit group 22, it can be constituted by a single fixed mirror, and has a simple configuration and easy alignment. In addition, the laser exposure device 44 arranges the rotation surface of the polygon mirror 45 in a space surrounded by the image forming unit group 22, the intermediate transfer belt unit 2, the paper supply unit 53, and the paper guide 54 with the rotation surface inclined with respect to the horizontal plane. Therefore, the configuration is easy to reduce the size by effectively utilizing the space in the device.

Further, since the laser light emission window 55 is disposed between the vertical line 56A and the vertical line 56B, even if toner spills from the image forming position 25 or the cleaning position during the image forming operation, the laser light is emitted. The emission window 55 is configured not to be easily contaminated with toner.

It is desirable that the inclination of the rotating surface of the polygon mirror 45 be large because the laser exposure device 44 can be arranged closer to the image forming unit group 22. However, tilting by 60 degrees or more can prevent the pixel laser signal light 2
It is not desirable because it becomes difficult to make the angle of incidence of 30 or less 30 degrees.

Intermediate mirror 47 and center mirror 49
It is desirable that the incident angle of the pixel laser signal light 26 with respect to When the angle is 30 degrees or more, the aberration of the laser beam on the reflection surface becomes large, and the image quality may be deteriorated. Also,
Since the image forming position 25 and the laser exposure device 44 must be arranged separately, it is difficult to reduce the size.

Intermediate mirror 47 and center mirror 49
The direction of the reflection surface is not limited, but it is preferable that the reflection surface is below a horizontal plane in order to minimize contamination by toner.

The pixel laser signal light 26 enters the center mirror 49 from a gap in the wall between the image forming units 21Y and 21M. That is, the developing device 3 of the image forming unit 21Y is sandwiched by the optical path of the pixel laser signal light 26 that is reflected by the center mirror 49 and enters the photoconductor 27Y (the path between the developing device 31Y and the cleaner 38Y).
The configuration is such that the pixel laser signal light 26 enters the center mirror 49 from the side opposite to 1Y. This is because, for example, in order to make the capacity of the frequently used black image forming unit 21Bk larger than that of other colors, the fan-shaped spread angle of the black image forming unit 21Bk is set to 120 degrees, yellow, magenta, and cyan. Even if the fan-shaped spread angles of the image forming units 21Y, 21M, and 21C are each 80 degrees, the breakdown is that the developing unit 31Bk is 90 degrees, the cleaner 38Bk is 30 degrees, and the developing units 31Y, 31M, and 31C are 50 degrees. When the cleaners 38Y, 38M, and 38C are 30 degrees, the capacity of the toner hopper 32Bk of the black image forming unit 21Bk can be increased without changing the arrangement of the other components described above.

Reference numeral 51 denotes a fixing device provided on the upper inside of the printer body 1. The operation of the color electrophotographic apparatus configured as described above will be described below.

First, the full-color image forming step will be described.
1 is in an image forming state. First, the yellow image forming process is performed. FIG. 5 shows the operation of the image forming unit 21Y.
This will be described with reference to FIG. The photoconductor 27 was charged to −450 V by the charger 28 that applied a voltage of −450 V to the grid 29. The photosensitive member 27 was irradiated with the pixel laser signal light 26 to form an electrostatic latent image. After passing through the lens system 46, the pixel laser signal light 26 is reflected twice by the intermediate mirror 47 and the center mirror 49 in a Z-shape (rearward in FIG. 1) and reaches the photoconductor 27. At this time, the exposure potential of the photoconductor was -50V.

This photoreceptor 27 is used as a two-component yellow developer 3
The developing was performed by a developing roller 33 carrying 7Y. When the photosensitive member 27 passed through the uncharged area, a DC voltage of +100 V was applied to the developing roller 33 by a high-voltage power supply. Thereafter, a DC voltage of -250 V was applied to the developing roller 33 by a high-voltage power supply when passing through the surface of the photoconductor 27 on which the electrostatic latent image was written by being charged to -450 V. As a result, a yellow-positive yellow toner image was formed only on the image portion on the photoconductor 27. At this time, the image forming unit group 22 is at the position shown in FIG.
Is at the image forming position 25 as shown in FIG.
Reference numeral 7 is in contact with the intermediate transfer belt 4.

In the image forming step of the image forming unit described above, an image was formed with yellow toner. At this time, the moving speed of the intermediate transfer belt 4 is set to be 1.5% faster than the speed of the photoconductor 27 in order to prevent the hollow transfer of the toner image. The image is transferred onto the transfer belt 4. At this time, the transfer guide roller 9 and the tension roller 5
V DC voltage was applied.

After all the yellow toner images have been transferred, the entire image forming unit group 22 is driven by the moving motor 23 and rotated exactly 90 degrees in the direction of arrow Q in FIG. 1 to move the image forming unit 21M to the image forming position. He stopped at 25.

When the rotation of the image forming unit group 22 is completed and the image forming unit 21M reaches the image forming position 25, the laser exposure device 44 irradiates a signal light to the image forming unit 21M with a magenta signal as before. Then, formation and transfer of a magenta toner image are performed. By this time, the intermediate transfer belt 4 has made one rotation, the timing of writing the magenta signal light is controlled based on the signal from the position detector 12, and the previously transferred yellow toner image is replaced with the next magenta toner image. Are superimposed so as to coincide in position. During this time, the re-transfer roller 43 is retracted to a position where it is not in contact with the intermediate transfer belt 4, so that the toner image on the transfer belt 4 is not disturbed.

Further, the cleaning unit 15 is provided as shown in FIG.
2, the cam follower 16 is pushed by the separation / contact cam 52 of the printer body 1 and rotates in the direction of the arrow P with the pivot 18 as a fulcrum, so that the cleaning blade 7 and the toner receiver 17 separate from the intermediate transfer belt 4. Therefore, the toner image on the transfer belt 4 is not disturbed. Further, the cleaning blade 7 is in contact with the overhang portion 4A of the intermediate transfer belt 4, and the toner receiver 17 is located closer to the intermediate transfer belt 4 than the tip of the cleaning blade 7 even when the cleaning blade 7 is separated. The waste toner adhering to the cleaning blade 7 does not spill out when the blade 7 is moved away.

Thereafter, the entire image forming unit group 22 is driven by the moving motor 23 again, rotates 90 degrees in the direction of arrow Q, and stops at the position where the image forming unit 21C reaches the image forming position 25. The same operation as for yellow magenta was performed for cyan.

Finally, the entire image forming unit group 22 is indicated by an arrow Q.
The image forming unit 21Bk was rotated 90 degrees in the direction, the image forming unit 21Bk was replaced with the image forming position 25, and an image was formed using black toner.
The four color toner images were superimposed on the intermediate transfer belt 4 in a position-matching manner, and a full-color image was formed. After the transfer of the last black toner image, the retransfer roller 43 is pressed against the retransfer backup roller 6, and a voltage of +3 kV is applied.
The four color toner images were collectively transferred onto the recording paper 42 fed from the paper feeding unit 53 to the paper guide 54. The toner image transferred to the paper was fixed by the fixing device 51.

Thereafter, the entire forming unit group 22 is driven by the moving motor 23 and further rotated by 90 degrees in the direction of arrow Q in FIG. 1, and the yellow image forming unit 21Y reaches the image forming position 25 again and is newly formed. The process of creating a full-color image has begun.

In this way, 2.5 full-color A4 size prints were obtained in one minute.

Next, the attachment / detachment operation of the intermediate transfer belt unit 2 and the image forming unit 21 will be described. When the front plate 1A is turned down as shown in FIG. 2, the opening 71 is opened.
When the intermediate transfer belt unit 2 is inserted toward the opening 71, the guide grooves 61 and 62 and the guide pins 63 and 64 are inserted.
And the intermediate transfer belt unit 2 is guided to a predetermined storage position while being guided in the direction of arrow R.

Since the opening 71 for the paper jam processing also serves as the insertion port of the intermediate transfer belt unit 2, the insertion port of the intermediate transfer belt unit 2 having a large projected area from above is separately provided on the upper surface of the printer main body 1. It is a configuration that does not need to be provided. The direction of the guide is obliquely forward and downward when viewed from the operator, so that the guide can be easily mounted in a natural posture.
Further, since the insertion direction is toward the center mirror 49, the intermediate transfer belt 4 comes into contact with the photoconductor 27 from its normal direction, so that the photoconductor 27 does not need to be retracted when it is attached or detached. The body 27 and the intermediate transfer belt 4 are not damaged. Since the intermediate transfer belt unit 2 has a cross-sectional shape narrowing toward the center mirror 49, it can be easily inserted into the opening 71. It is possible to increase the capacity of the waste toner reservoir 10 while reducing the center distance between the transfer guide roller 9 and the tension roller 5 so that the positioning of the intermediate transfer belt 4 with respect to the photoconductor 27 and the contact pressure can be easily set appropriately. It is a configuration that can be done.

In conjunction with the insertion operation, the separation / contact cam 52 of the printer main body 1 and the cam follower 16 are engaged, and the cleaning blade 7 is separated from the intermediate transfer belt 4. In a normal stop or standby state, the cleaning blade 7 is separated from the intermediate transfer belt 4. Then, only when cleaning is necessary, the separating / contacting cam 52 rotates to bring the cleaning blade 7 into contact with the intermediate transfer belt 4.

When the intermediate transfer belt unit 2 is removed, the engagement between the separation / contact cam 52 and the cam follower 16 is released.
The cleaning blade 7 is in contact with the intermediate transfer belt 4 to prevent scattering of waste toner. The angle between the direction of removal (opposite to the arrow R) and the direction of pressing of the separating / contacting cam 52 shown by the arrow V in FIG. 1 is 90 degrees or less, so that the removal can be performed smoothly without giving unnecessary resistance.

Further, the image forming unit 21 is opened by opening the printer top plate 1C, and is located at a unit other than the image forming position 25 (here, the black image forming unit 21B located above.
k). For this reason, it is possible to attach / detach without damaging the photosensitive member 2 and the intermediate transfer belt 4 without performing an operation of retracting the photosensitive member 27 when attaching / detaching. In the present embodiment, it is configured to be inserted substantially in the direction of gravity. Since the projected area from above is smaller than that of the intermediate transfer belt unit 2, the operation is easy even from the front of the apparatus. This attaching / detaching direction is desirably 30 degrees or more and 90 degrees or less with respect to the attaching / detaching direction of the intermediate transfer belt unit 2. If the angle is less than 30 degrees, the capacity of the toner hopper 32 of the developing device 31 at the image forming position 25 cannot be sufficiently secured, and if the angle is more than 90 degrees, the operator inserts from the back to the front, which is very convenient. Is worse.

As described above, according to the first embodiment, the laser exposure device 44 is disposed in a space surrounded by the image forming unit group 22, the intermediate transfer belt unit 2, the paper transport path 54, and the paper supply unit 53. With such a configuration, a compact color electrophotographic apparatus can be realized by effectively utilizing the space in the apparatus.

At the time of image recording, the pixel laser signal light 2
6 is reflected by the center mirror 49 and sandwiches the path leading to the image forming position 25, and the photosensitive member 27 at the image forming position 25 is separated.
From the side opposite to the developing unit 31 acting on the pixel laser signal light 2
6 is incident on the center mirror 49,
It is possible to realize a small-sized color electrophotographic apparatus capable of increasing the capacity of the toner hopper 32 of the frequently used color developing unit 31 without changing the arrangement of other components.

Further, by arranging the rotation surface of the polygon mirror 45 of the laser exposure device 44 at an angle of 60 degrees or less with respect to the horizontal plane, the space in the device can be more effectively used, and a compact color electrophotographic device can be used. Can be realized.

Further, a cleaning blade 7, which is a belt cleaning means for removing toner remaining on the intermediate transfer belt 4, is provided inside the intermediate transfer belt unit 2.
The laser light emission window 55 of the laser exposure device 44 is connected to the vertical line 56A on the image forming position 25 side with respect to the outermost envelope 56C of the image forming unit group 22 in the side view of the printer 1.
And between the cleaning blade 7 and the vertical line 56B from the cleaning position of the intermediate transfer belt 4, so that even if toner spills from the image forming position 25 or the cleaning position during the image forming operation, the laser light exit window It is possible to realize a small-sized color electrophotographic apparatus in which the toner 55 is not easily contaminated with toner.

Further, the intermediate transfer belt unit 2 is configured to be detachable from the printer main body 1, the retransfer means is a retransfer roller 43 provided in the printer main body 1, and the intermediate transfer belt unit 2 Guide grooves 61 and 62 and guide pins 63 and 64, which are belt unit guide means for guiding to the storage position, and an intermediate transfer belt unit 2
And a re-transfer backup roller 6 with which the re-transfer roller 43 is in contact, and a guide groove 61 at a predetermined storage position.
The configuration in which the guide direction of the intermediate transfer belt unit 2 by the guide pin 62 and the guide pins 63 and 64 is substantially perpendicular to the direction of the pressing force when the retransfer roller 43 contacts the retransfer backup roller 6 is used. By making the belt unit replaceable from the front, it is possible to realize a small-sized color electrophotographic apparatus with less misalignment for each color while improving maintainability.

Further, since the intermediate transfer belt unit 2 has a sectional shape narrowing toward the center mirror 49, the intermediate transfer belt unit 2 is
1 while reducing the distance between the axes of the transfer guide roller 9 and the tension roller 5 while keeping the waste toner reservoir 1
Therefore, a small color electrophotographic apparatus having a long maintenance interval can be realized.

Further, there is provided an intermediate mirror 47 which folds the pixel laser signal light 26 toward the center mirror 49, and irradiates the photosensitive member 27 at the image forming position 25 with the intermediate mirror 47 and the center mirror 49.
Is folded back so as to form a substantially Z-shape, the image forming position 25 and the laser exposure device 44 can be arranged close to each other, and a compact color electrophotographic apparatus can be realized.

Further, the angle of incidence of the pixel laser signal light 26 on the intermediate mirror 47 and the center mirror 49 is set to 30
With the configuration of not more than the degree, the aberration of the laser beam on each reflecting surface can be suppressed, and the image forming position 25 and the laser exposure device 44 can be arranged close to each other, so that a compact color electrophotographic apparatus can be realized. .

Further, the intermediate transfer belt unit 2 is configured to be detachable from the printer main body 1, and the opening 71 of the intermediate transfer belt unit 2 is engaged with the intermediate transfer belt unit 2 so that the intermediate transfer belt unit 2 is attached. It is provided with guide grooves 61 and 62 and guide pins 63 and 64 which are belt unit guide means for guiding from the opening 71 to a predetermined storage position, and the guide grooves 61 and 62 and the guide pins 63 and 64 are provided.
, The guide direction of the intermediate transfer belt unit 2 is in a range from the horizontal direction around the center mirror 49 to the upper end 57 of the opening, so that the intermediate transfer belt unit 2 can be easily mounted in a more natural posture than the front surface. In addition, it is possible to realize a small-sized color electrophotographic apparatus in which the photosensitive member 27 and the intermediate transfer belt 4 are not damaged even if the photosensitive member 27 is not evacuated during attachment / detachment.

Further, the insertion port 72 of the image forming unit 21
And the image forming unit 21 engaged with the image forming unit 21.
Of the image forming unit 21 by the guide pins 67, 68 and the guide grooves 69, 70, which are image forming unit guide means for guiding the image forming unit 21 to a predetermined position of the image forming unit group 22. The configuration in which the guide direction is in a range of 30 degrees or more and 90 degrees or less with respect to the guide direction of the intermediate transfer belt unit 2 ensures a sufficient capacity of the toner hopper 32 and is small in color with good operability from the front. An electrophotographic apparatus can be realized.

(Embodiment 2) FIG. 6 shows the configuration of a color electrophotographic apparatus according to Embodiment 2 of the present invention.

The difference from the configuration of FIG.
3 is provided so as to protrude from the front surface of the printer body 1;
The rotation surface of the polygon mirror 45 is inclined by 18 degrees with respect to the horizontal plane, and the laser exposure device 44 is disposed in a space surrounded by the image forming unit group 22, the intermediate transfer belt unit 2, and the paper guide 54 on three sides. It is. In this case, the reflection surface of the intermediate mirror 47 is oriented in the horizontal direction.

Other structures and operations are the same as those of the first embodiment. As described above, according to the second embodiment, the actual installation area is larger than that of the first embodiment by an amount corresponding to the protrusion of the sheet feeding unit 53, but the height of the printer main body 1 can be kept low. .

In the above description, an example is described in which the four color image forming units 21 of black, yellow, magenta, and cyan are used. However, the type and number of colors are not limited. Further, image forming units having different capacities may be used.

The diameter of the photosensitive member 27 is 30 mm and the peripheral speed is 100 mm / s, but the diameter and the peripheral speed of the photosensitive member are not limited. Further, the process conditions such as the developing method, the applied voltage, and the peripheral speed of the intermediate transfer belt 4 are not limited to those in the embodiment, and for example, a non-magnetic one-component developing process may be used.

The configuration of the intermediate transfer belt unit 2 is not limited to the configuration shown in the embodiment. Center mirror 4
As long as it has a shape narrowing toward 9, the shape is arbitrary. Further, the number and diameter of the rollers that stretch the intermediate transfer belt 4 are not limited. Further, the belt cleaning means is the cleaning blade 7, but the belt cleaning means and its position are also arbitrary. When the intermediate transfer belt 4 does not need to be replaced, such as when the life of the intermediate transfer belt 4 is about the same as the life of the printer main body 1, the intermediate transfer belt unit 2 is detachable from the printer main body 1. You don't have to.

Although the retransfer means is the retransfer roller 43, other transfer means such as a corona charger may be used.

In the first embodiment, the guide direction (arrow R) of the intermediate transfer belt unit 2 is linear, but the guide direction may be curved. In this case, the direction of the tangent to the guide direction is the horizontal line 65 and the line 6
It is good if it is between 6. Further, the guide direction (arrow T) of the image forming unit 21 is also linear, but it may be curved like the intermediate transfer belt unit 2.
Also in this case, the tangent of the image forming unit 21 in the guide direction may be 30 degrees or more and 90 degrees or less with respect to the guide direction of the intermediate transfer belt unit 2. However, the guide direction at the time of positioning with respect to the image forming unit group 22 is arbitrary. For example, the image forming unit 21 is inserted in the direction of arrow T, and finally the image forming unit 21 is
May be rotated to bring the guide pin 68 into contact with the positioning reference.

The contact direction (arrow S) of the retransfer roller 43 with the retransfer backup roller 6 is perpendicular to the guide direction (arrow R) of the intermediate transfer belt unit 2. May be perpendicular to the guide direction when the intermediate transfer belt unit 2 is at the predetermined storage position. The direction during which the intermediate transfer belt unit 2 is inserted and guided to a predetermined storage position is not limited.

Further, in the second embodiment, the laser exposure device 44 is disposed on the three sides in a space surrounded by the image forming unit group 22, the intermediate transfer belt unit 2 and the paper guide 54. Only needs to include two thirds or more of the above space.

[0081]

As described above, according to the present invention, a plurality of image forming units each having a developing unit, a charging unit, and a photoreceptor for each color, and the plurality of image forming units can be attached to and detached from a printer main body. And an image forming unit group arranged in an annular shape and rotatably movable to an image forming position and other positions, a laser exposure device arranged outside the image forming unit group, and an image forming unit group An intermediate transfer belt unit including an intermediate transfer belt for receiving a toner image formed on a photoconductor at an image forming position and forming a color image therein; Retransfer means for transferring the color image formed on the transfer belt to the recording paper at the retransfer position, and at least three of the laser exposure devices have an image forming unit group and an intermediate transfer belt unit. And a paper transport path for transporting the recording paper from the paper feed position to the retransfer unit, thereby realizing a compact color electrophotographic apparatus by effectively utilizing the space in the apparatus. The remarkable effect that can be obtained is obtained.

Further, according to the present invention, there is provided a paper feed unit for accommodating recording paper, and the laser exposure device is provided in a space surrounded by the image forming unit group, the intermediate transfer belt unit, the paper transport path, and the paper feed unit. This arrangement has a remarkable effect that a small-sized color electrophotographic apparatus having a smaller installation area can be realized.

Further, according to the present invention, when recording an image,
The laser light is reflected by the center mirror and interposes the path to the image forming position, and the laser light is incident on the center mirror from the side opposite to the developing device acting on the photoconductor at the image forming position. A remarkable effect is obtained that a small-sized color electrophotographic apparatus capable of increasing the capacity of the toner hopper of a frequently used color developing device without changing the arrangement of the components can be obtained.

Further, according to the present invention, the laser exposure apparatus includes a polygon mirror, and the rotation surface of the polygon mirror is inclined with respect to the horizontal plane, and the inclination angle is 60 degrees or less. A remarkable effect is obtained that a small-sized color electrophotographic apparatus can be realized by more effectively utilizing the internal space.

Further, according to the present invention, a belt cleaning means for removing the toner remaining on the intermediate transfer belt is provided inside the intermediate transfer belt unit, and the laser light emission window of the laser exposure device is connected to the image in the side view of the printer main body. The image forming unit is disposed between a vertical line on the image forming position side with respect to the outermost envelope of the forming unit group and a vertical line from the cleaning position of the intermediate transfer belt by the belt cleaning unit. Even if toner spills from the cleaning position, a remarkable effect that a small-sized color electrophotographic apparatus in which the laser beam emission window is hardly contaminated with toner can be realized.

Further, according to the present invention, the intermediate transfer belt unit is configured to be detachable from the printer main body, the re-transfer means is a re-transfer roller provided on the printer main body, and The belt unit guide means for guiding to the storage position, the intermediate transfer belt unit, a backup roller is provided with a re-transfer roller abuts, the guide direction of the intermediate transfer belt unit by the belt unit guide means at a predetermined storage position, With a configuration in which the direction of the pressing force when the retransfer roller abuts the backup roller is substantially perpendicular, the intermediate transfer belt unit can be replaced from the front, thereby improving maintainability and maintaining the positional deviation for each color. A remarkable effect is obtained that a small-sized color electrophotographic apparatus with less noise can be realized.

Further, according to the present invention, since the intermediate transfer belt unit has a sectional shape narrowing toward the center mirror, the intermediate transfer belt unit can be easily inserted into the opening, and the transfer guide roller and the tension roller can be easily inserted. A remarkable effect is obtained that the capacity of the waste toner reservoir can be increased while the distance between the shafts is reduced, and a small-sized color electrophotographic apparatus having a long maintenance interval can be realized.

Further, according to the present invention, there is provided an intermediate mirror which folds the laser light toward the center mirror, and the intermediate mirror and the center mirror convert the laser light to be applied to the photosensitive member at the image forming position into a substantially Z-shape. With this configuration, the image forming position and the laser exposure device can be arranged close to each other, and a remarkable effect that a small-sized color electrophotographic apparatus can be realized can be obtained.

Further, according to the present invention, the intermediate transfer belt unit is configured to be detachable from the printer main body.
A belt unit comprising: a front plate that can be opened and closed; an opening that opens when the front plate is opened; and a belt unit guide that engages with the intermediate transfer belt unit and guides the intermediate transfer belt unit to a predetermined storage position. With the configuration in which the guide direction of the intermediate transfer belt unit by the guide means is in the range from the horizontal direction around the center mirror to the upper end of the opening, the intermediate transfer belt unit can be easily mounted in a more natural posture than the front surface, and A remarkable effect is obtained that a small-sized color electrophotographic apparatus having high maintainability can be realized without damaging the photoconductor and the intermediate transfer belt without having to evacuate the photoconductor at the time of attachment / detachment.

Further, according to the present invention, there is provided an image forming unit guide means for guiding the image forming unit to a predetermined position of the image forming unit group by engaging with the image forming unit and the image forming unit. With the configuration in which the guide direction of the image forming unit by the forming unit guide means is in the range of 30 degrees or more and 90 degrees or less with respect to the guide direction of the intermediate transfer belt unit, the capacity of the toner hopper is sufficiently ensured, and A remarkable effect is obtained that a small-sized color electrophotographic apparatus with good operability can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a color electrophotographic apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a method for attaching and detaching each unit of the color electrophotographic apparatus according to the embodiment of the present invention;

FIG. 3 is a cross-sectional view illustrating a configuration of an intermediate transfer belt unit used in the color electrophotographic apparatus according to one embodiment of the present invention.

FIG. 4 is a perspective view showing a configuration of an intermediate transfer belt used in the color electrophotographic apparatus according to one embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a configuration of an image forming unit used in a color electrophotographic apparatus according to an embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating a configuration of a color electrophotographic apparatus according to Embodiment 2 of the present invention.

FIG. 7 is a cross-sectional view showing a configuration of a conventional color electrophotographic apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Printer main body 1A Front plate 1B Hinge shaft 1C Top plate 1D Printer outer casing 2 Intermediate transfer belt unit 3 Unit case 3A Surface defining cross-sectional shape 3B Surface defining cross-sectional shape 4 Transfer belt 4A Overhang portion 5 Tension roller 6 Re Transfer backup roller 7 Cleaning blade 8 Drive roller 9 Transfer guide roller 10 Waste toner reservoir 11 Waste toner full detector 12 Position detector 15 Cleaner unit 16 Cam follower 17 Toner receiver 18 Oscillating shaft 19 Communication port 20 Detection hole 21 Image forming unit 22 Image forming unit group 23 Moving motor 24 as a moving means of image forming unit group 22 Axis 25 Image forming position 26 Pixel laser signal light 27 Organic photoreceptor 28 Corona charger 29 Grid 30 Exposure window 31 Developing device 32 Toner hot Par 33 developing roller 34 magnet 35 doctor blade 36 toner 37 two-component developer 38 cleaner 39 cleaning blade 40 waste toner reservoir 41 static elimination needle 42 recording paper 43 retransfer roller as retransfer means 44 laser exposure device 45 polygon mirror 46 lens system 47 Intermediate mirror 48 Optical path window 49 Center mirror 50 Feeding roller 51 Fixing device 52 Separation / contact cam 53 Paper feed unit 54 Paper guide as a paper conveyance path 55 Laser light emission window 56A Image formation position 25 side with respect to outermost envelope 56C Vertical line 56B Vertical line 56C from the contact position of the cleaning blade 7 56C Outermost envelope when the image forming unit group 22 rotates and moves 57 Upper end of the opening 71 61 Guide groove as a guide means of the intermediate transfer belt unit 2 62 Intermediate transfer belt Guide groove as guide means for knit 2 63 Guide pin as guide means for intermediate transfer belt unit 2 64 Guide pin as guide means for intermediate transfer belt unit 2 65 Horizontal line drawn from center mirror 49 66 Opening from center mirror 49 A line connecting the upper end 57 of the image forming unit 71 with a guide 67 A guide pin 68 as a guide for the image forming unit 21 A guide pin 69 as a guide for the image forming unit 21 A guide groove 70 as a guide for the image forming unit 21 70 Guide groove 71 as a guide means Opening opening when front plate 1A is folded down 72 Insertion opening of image forming unit 101 Intermediate transfer belt unit 102 Intermediate transfer belt 103 First transfer roller 104 Second transfer roller 105 Cleaner roller 106 Waste Tona Reservoir 107 image forming unit 108 image forming unit group 109 shaft 110 image forming position 111 laser beam 112 laser exposure device 113 the optical path window 114 mirror 115 exposure window 116 developing device 117 cleaner 118 photosensitive drum 119 third transfer roller 120 fuser

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Masahiro Aizawa 1006 Kadoma, Kazuma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (11)

[Claims] 1. A plurality of image forming units each having a developing unit, a charging unit, and a photoreceptor for each color, the plurality of image forming units being detachably held in a printer main body, and arranged in an annular shape. An image forming unit group rotatable to an image forming position and other positions; a laser exposure device disposed outside the image forming unit group; and a laser exposure device disposed substantially at the center of the image forming unit group. A center mirror, an intermediate transfer belt unit internally provided with an intermediate transfer belt for receiving a toner image formed on the photoconductor at the image forming position and forming a color image, and formed on the intermediate transfer belt. Retransfer means for transferring the transferred color image to recording paper at a retransfer position, and at least three of the laser exposure devices are provided with the image forming unit group and the intermediate transfer belt unit. A color image recording apparatus, wherein the color image recording apparatus is arranged in a space surrounded by a sheet and a paper transport path for transporting the recording paper from a paper feeding position to the retransfer unit. 2. A paper feed unit for storing recording paper, wherein a laser exposure device is disposed in a space surrounded by an image forming unit group, an intermediate transfer belt unit, a paper transport path, and the paper feed unit. The color image recording apparatus according to claim 1. 3. When recording an image, the laser beam is reflected from a center mirror and passes through a path leading to an image forming position. 2. The color image recording apparatus according to claim 1, wherein the color image recording apparatus is configured to be incident on a center mirror. 4. The laser exposure apparatus according to claim 1, further comprising a polygon mirror, wherein the rotation surface of the polygon mirror is inclined with respect to a horizontal plane, and the inclination angle is 60 degrees or less. Color image recording device. 5. An intermediate transfer belt unit, wherein a belt cleaning means for removing toner remaining on the intermediate transfer belt is provided, and a laser light emission window of the laser exposure device is provided at the outermost side of the image forming unit group in a side view of the printer body. 2. The color image recording apparatus according to claim 1, wherein the apparatus is arranged between a vertical line on an image forming position side with respect to an entanglement line and a vertical line from a cleaning position of the intermediate transfer belt by the belt cleaning unit. 6. An intermediate transfer belt unit is configured to be detachable from a printer main body, a retransfer unit is a retransfer roller provided on the printer main body, and moves the intermediate transfer belt unit to a predetermined storage position. A guide unit for guiding the intermediate transfer belt unit, and a backup roller for contacting the intermediate transfer belt unit with the retransfer roller, and a guide direction of the intermediate transfer belt unit by the belt unit guide unit at the predetermined storage position. 2. The color image recording apparatus according to claim 1, wherein the direction is substantially perpendicular to the direction of the pressing force when the retransfer roller contacts the backup roller. 7. The color image recording apparatus according to claim 1, wherein the intermediate transfer belt unit has a sectional shape narrowing toward a center mirror. 8. An intermediate mirror for turning a laser beam toward a center mirror, wherein the intermediate mirror and the center mirror fold a laser beam irradiated on a photoconductor at an image forming position so as to be substantially Z-shaped. 2. The color image recording apparatus according to claim 1, wherein: 9. The color image recording apparatus according to claim 8, wherein the angle of incidence of the laser beam on the intermediate mirror and the center mirror is 30 degrees or less. 10. An intermediate transfer belt unit configured to be detachable from a printer main body, and a front plate that can be opened and closed,
An opening that opens when the front plate is opened; and a belt unit guide that engages with the intermediate transfer belt unit and guides the intermediate transfer belt unit to a predetermined storage position. 2. The color image recording apparatus according to claim 1, wherein the guide direction of the intermediate transfer belt unit is configured to range from a horizontal direction around a center mirror to an upper end of the opening. 11. An image forming unit guide, comprising: an insertion opening of the image forming unit; and image forming unit guide means for engaging the image forming unit and guiding the image forming unit to a predetermined position in the image forming unit group. 11. The color image recording apparatus according to claim 10, wherein a guide direction of the image forming unit by means is in a range of 30 degrees or more and 90 degrees or less with respect to a guide direction of the intermediate transfer belt unit. .