JP3595107B2 - Color image forming apparatus capable of switching color modes - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a color image forming apparatus of four colors using a tandem system, and more particularly to a color image forming apparatus capable of switching between a full-color mode and a monochrome mode and capable of smoothly switching between color modes.
[0002]
[Prior art]
Primarily for the purpose of speeding up image output, image forming units of four colors of black (BK), magenta (M), yellow (Y), and cyan (C) are arranged in a line, and are arranged along the recording paper conveyance direction. There is a tandem type color image forming apparatus in which a color image is formed on a recording paper simply by passing the recording paper.
[0003]
FIG. 14 shows the color image forming apparatus 14. As shown, the color image forming apparatus 14 includes four image forming units 15BK, 15M, 15Y, and 15C of different colors and a position where the recording paper 17 from the paper feeding unit 16 is engaged with the image forming unit 15BK and the like. Transfer belt 18 and a laser scanner 21 for refracting a laser beam from a laser light source (not shown) by a polygon scanner 19 and a deflecting mirror 20 to be incident on a photoconductor side such as the image forming unit 15BK and exposing the surface thereof. , A fixing unit 22 and the like. In the laser scanner 21, the main scanning is performed in the direction of the central rotation axis of the photoconductor by the rotation of the polygon scanner 19, and the rotation of the photoconductor causes a sub scanning in the direction orthogonal to the center rotation axis of the photoconductor. A scan is performed.
[0004]
The image forming units 15BK, 15M, 15Y, and 15C include the photoconductors 23BK, 23M, 23Y, and 23C, the laser scanner 21, which is the above-described exposure device, the developing devices 24BK, 24M, 24Y, and 24C, and the charging devices 25BK, 25M, and 25C. 25Y, 25C, toner cleaning devices 26BK, 26M, 26Y, 26C, transfer devices 27BK, 27M, 27Y, 27C, etc., respectively. Reference numeral 28 denotes a reading scanner, and reference numeral 29 denotes an image processing circuit.
[0005]
After the surface of the photoconductor 23BK or the like is uniformly charged by the charging device 25BK or the like, the surface is exposed to a pattern corresponding to an image to be output by the laser scanner 21 to form an electrostatic image on the surface of the photoconductor 23BK or the like. You. This electrostatic image is developed by the developing device 24BK or the like to form a toner image.
This toner image is transferred onto the recording paper 17. The toner remaining on the surface of the photoconductor 23BK or the like after the transfer is removed by the cleaning device 26BK. The transferred recording paper 17 is sequentially fed along the transfer belt 18, separated from the transfer belt 18 by the separation claw 41 at the end of the transfer belt 18, fixed by the fixing unit 22, and then to the paper discharge unit (not shown). Conveyed.
[0006]
The alignment of each color is determined by the timing at which the transfer belt 18 sends the photosensitive paper 23BK, 23M, 23Y, 23C to the photosensitive position of the recording paper 17 and the image on the photosensitive body 23BK, 23M, 23Y, 23C is transferred to the transfer position. This is performed by setting the exposure start time so that the movement timing is the same for all colors. For this reason, each of the photoconductors 23BK, 23M, 23Y, and 23C needs to be driven uniformly.
[0007]
As a drive transmission mechanism connected to each of the photoconductors 23BK, 23M, 23Y, and 23C for achieving the above object, the one shown in FIGS. 15 to 17 has been filed by the same applicant. Driven gears 31BK, 31M, 31Y, 31C of the same shape are connected to central rotating shafts 30BK, 30M, 30Y, 30C for rotating and driving the photoconductors 23BK, 23M, 23Y, 23C.
[0008]
In this example, the four driven gears 31BK and the like arranged in the order of BK, M, Y, and C along the transfer belt conveying direction are odd-numbered driven gears 31BK and 31Y and even-numbered driven gears 31BK. The driven gears 31BK and 31Y and the driven gears 31M and 31C of these groups are arranged stepwise along the axial direction of the center rotation shaft 30BK and the like as shown in FIGS. Is done. The center rotation shafts 30BK and the like are supported by the main body side plate 32.
[0009]
The idle gears 34BK · Y and 34M · C are supported by a rotation shaft 36 supported by a drive unit side plate 33 that supports the drive mechanism 35 and a rotation shaft 37 supported by the main body side plate 32, respectively. The idle gears 34BK and Y mesh with the driven gears 31BK and 31Y, and the idle gears 34M and C mesh with the driven gears 31M and 31C.
[0010]
On the other hand, a drive gear 40 is connected to a drive shaft 39 of a motor 38 serving as a drive source of a rotation mechanism 35 supported by the drive unit side plate 33. The drive gear 40 is driven by driven gears 31BK and 31M as shown in FIG. Mesh with.
[0011]
With the above structure, the driven gear 31BK and the driven gear 31M rotate via the driving gear 40 by driving the motor 38, and the idle gears 34BK • Y and 34M • C meshing with the driven gear 31BK and the driven gear 31BK rotate. When the idle gears 34BK • Y and 34M • C rotate, the driven gears 31Y and 31C meshing therewith rotate simultaneously. Therefore, the photoconductors 23BK, 23M, 23Y, and 23C are simultaneously driven to rotate.
[0012]
In this example, since the group of the odd-numbered driven gears 31BK and 31Y and the group of the even-numbered driven gears 31M and 31C are arranged stepwise, all of the driven gears 31BK, 31M, 31Y and 31C are photosensitive. It is formed larger than the distance between the axes of the bodies 23BK and 23M and the like. Therefore, the banding cycle can be made finer, and higher image quality can be achieved.
[0013]
In the color image forming apparatus 1 having the above structure, full-color images of four colors are formed as described above. However, the color image forming apparatus 1 does not always require full-color image formation. A mode (black and white) is often required.
In this case, only the photoreceptor necessary for the monochrome mode, specifically, the photoreceptor 23BK needs to operate, and the other 23M, 23Y, and 23C are desirably stopped. In particular, since the cleaning device 26BK and the like are always in contact with the photoconductor 23BK, the abrasion is large. When the cleaning device 26BK and the like wear, the deterioration of the photoconductor 23BK and the like progresses, and a high-quality image cannot be obtained. Therefore, it is important to stop the rotation of the photoconductor except when necessary.
[0014]
A conventional technique for switching between a full-color mode and a monochrome mode based on the above request has already been disclosed, and JP-A-7-181773 is mentioned as an example. This "photosensitive drum driving mechanism" is provided with a drive selecting member (4) which does not transmit the rotation to the photoconductor side when the drive motor for driving the photoconductor receives a rotation limiting force exceeding a predetermined value. It rotates to the first or second position in the mode and the full-color mode, and selectively transmits the rotation of the drive motor to the photoconductor side, and includes a complicated gear transmission mechanism and a belt transmission mechanism.
[0015]
[Problems to be solved by the invention]
The switching between the full-color mode and the monochrome mode is smoothly performed by the above-described known technology, but as described above, the transmission path is complicated and long, so that each photoconductor is difficult to rotate at the same rotation speed, and the gear transmission is performed. The provision of a mechanism and a belt transmission mechanism causes a transmission loss, which causes a problem of uneven rotation. When rotation unevenness occurs, banding (striped light and shade unevenness) occurs, and it is particularly remarkable in a halftone image.
15 and the like shown in FIG. 15 have a lower degree of banding than that of the above-mentioned known technology, but are not provided with a mechanism for switching between a full-color mode and a monochrome mode.
Means for not rotating other driven gears in the monochrome mode include, for example, an electromagnetic force between the central rotation shafts 30M, 30Y, 30C of the photoconductors 23M, 23Y, 23C and the driven gears 31M, 31Y, 31C. Means for interposing an attachment / detachment mechanism such as a clutch is conceivable. However, at least three electromagnetic clutches and the like are required, which increases the cost, increases the length of the central rotating shaft in the axial direction, and plays back the gear between the electromagnetic clutch shaft and the gear. Also, there is a concern about the influence on rotation unevenness.
[0016]
The present invention has been made in view of the above circumstances, has a transmission mechanism that does not cause rotation unevenness, can smoothly switch between a full-color mode and a monochrome mode, can be implemented at low cost, and has a switching mechanism. It is an object of the present invention to provide a color image forming apparatus capable of switching between color modes with less adverse effect on rotation unevenness due to image formation.
[0017]
[Means for Solving the Problems]
In order to achieve the above object, a color image forming apparatus capable of switching between color modes according to claim 1 provides a four-color image forming apparatus of black (BK), magenta (M), yellow (Y), and cyan (C). Forming sections are arranged along the direction of conveyance of the recording paper, and driven gears supported on the central rotation axis of the photosensitive member of each of the image forming apparatuses, an odd-numbered group of driven gears (BK · Y) and an even number And the group of the driven gears (M, C) is displaced stepwise in the axial direction, and the driven gears in each of the groups are connected via idle gears. A color image forming apparatus comprising: a driven gear of one group and a driving gear meshing with one of the even-numbered driven gears adjacent to the driven gear and a driving mechanism including the driving source. The device, wherein the odd number A swing unit that is swingably supported by the central rotation axis of one of the driven gears of the eye group, holds the drive mechanism, and supports the idle gear that meshes with the driven gear; A swing mechanism for swinging the swing unit so as to engage and disengage the mechanism and the idle gear with another driven gear.
[0018]
The color image forming apparatus capable of switching between color modes according to claim 2, wherein the idle gear is interlocked with the other driven gear between the swing unit and a stationary side of the apparatus. A spring for rotating the unit in a direction approaching the other driven gear side is interposed.
[0019]
According to a third aspect of the present invention, in the color image forming apparatus capable of switching between color modes, the swing mechanism is a solenoid interposed between the swing unit and a stationary side of the apparatus. , And is turned on in a direction in which the swing unit is rotated against the spring force of the spring.
[0020]
Further, in the color image forming apparatus capable of switching the color mode according to claim 4, the swing mechanism section engages with the driven gear on a center rotating shaft on which the swing unit is supported, and rotates the driven gear. Characterized in that it is provided with a restraining means for restraining or canceling.
[0021]
According to a fifth aspect of the present invention, in the color image forming apparatus capable of switching between color modes, the oscillating mechanism includes a one-way clutch-equipped clutch gear that meshes with a driven gear on a central rotating shaft that supports the oscillating unit. The clutch gear is formed one-way in a direction that does not restrict the rotation of the driven gear in the normal recording paper feed direction, and the drive source of the drive mechanism supported by the swing unit is It is characterized in that it is formed to be rotatable in forward and reverse directions.
A replaceable color image forming apparatus.
[0022]
Further, in the color image forming apparatus capable of switching between color modes according to claim 6, the swing unit detects a rotation amount of the swing unit by detecting a rotation amount of the swing unit, and detects the rotation position at the position. A position detecting and holding means for holding the swinging unit is provided.
[0023]
In the case of the full-color mode in which the swinging unit is not operated, the rotation of the drive source of the drive mechanism unit is one of a group of odd-numbered driven gears, for example, a group of BK driven gears and even-numbered driven gears. It is transmitted to the driven gear of M adjacent to the driven gear of BK. These driven gears transmit rotation to another driven gear in the group via an idle gear. Thereby, all the driven gears rotate simultaneously. In addition, the diameter of the driven gear can be made larger than the distance between the axes in the adjacent photoconductors, and the value of (photoconductor diameter × π / number of teeth of the driven gear) is reduced, rotation unevenness is reduced, and banding does not occur. .
[0024]
On the other hand, when the swing unit is operated, the drive gear and the BK / Y idle gear mesh with the driven gear of BK, but the mesh between the driven gear of M and the drive gear adjacent to the driven gear of BK is released. Then, the meshing between the odd-numbered other Y driven gear and the BK · Y idle gear is released.
Therefore, the rotation from the drive source is transmitted only to the driven gear of BK, and is not transmitted to the remaining driven gears.
The above operation is easily performed by the rotation of the swing unit of the present invention, and the mode can be switched smoothly. In addition, since the swing mechanism of the swing unit does not use a mechanism such as a gear that easily causes backlash, occurrence of rotation unevenness is prevented.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a color image forming apparatus capable of switching color modes according to the present invention will be described in detail with reference to the drawings. In this example, the arrangement of the driven gears of BK, M, Y, and C, the idle gear, the photosensitive member, and the like, and the base of the transmission mechanism thereof are those shown in FIG. That is, in this example, the drive transmission mechanism shown in FIG. 15 and the like is provided with a swing unit and a swing mechanism unit.
[0026]
1 to 3 show one embodiment of a swing unit and the like of the present invention. The drive unit side plate 3 of the swing unit 1 is swingably supported by the central rotation shaft 30BK of the photoconductor 23BK. The drive unit side plate 3 is composed of a first drive unit side plate 3 ′ also serving as the drive unit side plate 33 shown in FIGS. 16 and 17 and a second drive unit side plate 3 ″ of the same shape arranged opposite to the first drive unit side plate 3 ′. The two are connected by a central rotation shaft 30BK of the photoconductor 23BK.
The first drive unit side plate 3a supports a motor 38 and a drive gear 40 as a drive source of a drive mechanism 35, and also supports an idle gear 34BK · Y by a rotating shaft 36.
[0027]
The movable unit 5 of the solenoid 2 which is one of the swing mechanism units is fixed to the drive unit side plate 3, and the main body 6 of the solenoid 2 is fixed to the immobile side 4 of the device, for example, the main body side plate 32.
Further, a spring 7 is provided between the drive unit side plate 3 and the immovable side 4, and biases the drive unit side plate 3 in a direction to rotate counterclockwise to the center rotation shaft 30BK. A positioning member 8 engages and disengages with a position where it engages with the side surface of the drive unit side plate 3.
[0028]
The movable part 5 of the solenoid 2 is engaged with the main body 6 so as to be able to move in and out, and the drive unit side plate 3 is pulled by the spring 7 and moves in the projecting direction from the main body 6 in a state shown in FIG. As shown in FIGS. 4, 5 and the like, the driving gear 40 meshes with both the driven gear 31BK and the driven gear 31M, and the idle gears 34BK and Y mesh with the driven gear 31BK and the driven gear 31Y. This state corresponds to the OFF state of the solenoid 2.
[0029]
Next, when the solenoid 2 is turned on, the movable part 5 is pulled into the main body 6 side. Since the movable portion 5 is fixed to the swing unit side plate 3, the swing unit side plate 3 rotates clockwise around the central rotation shaft 30 </ b> BK against the spring force of the spring 7 as shown in FIG. 6.
Therefore, the contact between the positioning member 8 and the swing unit side plate 3 is released. Since the motor 38, the driving gear 40, and the idle gears 34BK and Y of the driving mechanism 35 are supported by the swing unit side plate 3, the drive gear 40 is driven even when the swing unit side plate 3 rotates clockwise. The gear 31BK and the idle gears 34BK and Y mesh with the driven gear 31BK.
[0030]
However, as shown in FIG. 6, the rotation of the swing unit side plate 3 releases the engagement between the driving gear 40 and the driven gear 31M, and releases the engagement between the idle gears 34BK and Y and the driven gear 31Y. At this time, since the spring force of the spring 7 is weaker than the electric force for holding the solenoid 2 in the ON state, the swing unit side plate 3 is set at the position shown in FIG.
In the state shown in FIG. 6, the driven gears 31M, 31Y, and 31C do not rotate, but only the driven gear 31BK rotates, and only image formation in the monochrome mode is performed. Here, when the solenoid is turned off, the movable portion 5 is extended by the spring force of the spring 7, and the swinging unit side plate 3 rotates counterclockwise until the swinging unit side plate 3 comes into contact with the positioning member 8, and FIG. Returns to the state. Therefore, the mode is switched to the full-color mode, and all the driven gears 31BK, 31M, 31Y, and 31C rotate, and image formation in the full-color mode is performed.
[0031]
7 and 8 show another swing unit 1a. As the swing mechanism, a restraining means 2a for restraining the rotation of the driven gear 31BK in place of the solenoid 2 is provided, and specifically, a brake mechanism 9 is employed. The brake mechanism 9 is fixed to the main body side plate 32 and engages with the driven gear 31BK. When the brake mechanism 9 is operated, the driven gear 31BK is pinched and its rotation is restricted.
In this example, the sensor 11 for detecting the amount of rotation of the swing unit side plate 3 is arranged on the stationary side, and the solenoid 10 is fixed to the main body side plate 32. The solenoid 10 moves the pin 10a in and out by ON and OFF, and the pin 10a is fitted into the positioning holes 10b and 10c of the second swing unit side plate 3 ".
The state in which the pin 10a fits in the positioning hole 10b corresponds to the full color mode, and the state in which the pin 10a fits in the positioning hole 10c corresponds to the monochrome mode.
[0032]
To change from the full color mode state to the monochrome mode in FIG. 7, first, the brake mechanism 9 is operated to restrict the rotation of the driven gear 31BK. Even in this state, the rotational force of the drive source motor 38 is transmitted to the driven gear 31BK via the drive gear, so that the swing unit side plate 3 itself rotates counterclockwise as shown in FIG. When it comes into contact with the swing unit side plate 3 and the sensor 11 and it is detected that the motor has been rotated by a predetermined amount of rotation, the solenoid 10 is turned off, the rotation of the motor 38 is stopped, and the pin 10a of the solenoid 10 is turned on as shown in FIG. Thus, the swing unit side plate 3 is fixed at the rotation position.
[0033]
Here, when the operation of the brake mechanism 9 is released, the rotation of the motor 38 is transmitted only to the driven gear 31BK, and the other driven gears 31M, 31Y, 31C do not rotate.
On the other hand, when the full color mode is set, the solenoid 10 is turned on and the pin 10a is pulled out from the positioning hole 10b. The swing unit side plate 3 rotates clockwise by the spring force of the spring 7, and the pin 10a fits into the pin 10b. In this state, the driving gear 40 meshes with the driven gears 31BK and 31M, and the idle gears 34BK and Y mesh with the driven gear 31BK and the driven gear 31Y, so that all the driven gears 31BK, 31M, 31Y and 31C rotate simultaneously. It becomes full color mode.
[0034]
FIG. 10 shows a detailed structure of the solenoid 10, which includes a solenoid body 10d, a spring 10e which engages with the pin 10a, and the like, but the structure itself is a known technique.
[0035]
FIGS. 11 and 12 show still another swinging unit 1b. This oscillating unit 1b employs a clutch gear 2b having a clutch as an oscillating mechanism in place of the brake mechanism 9, and specifically employs a clutch gear 2b having a one-way clutch 12. The clutch gear 2b is supported by the main body side plate 32 as shown in FIG. The one-way clutch 12 rotates the gear 2b following the driven gear 31BK in the full-color mode, and acts to restrain the rotation of the gear 2b when the driven gear 31BK rotates in the reverse direction.
[0036]
In this example, the motor 38 is configured to be capable of rotating forward and reverse for mode switching. Also, the sensor 13, the solenoid 10 having the pin 10a, and the positioning holes 10b and 10c are the same as those described above, and the duplicate description will be omitted.
[0037]
As shown in FIG. 11, when the motor 38 is rotating forward and backward in the direction of arrow A, the one-way clutch 12 does not restrict the rotation of the clutch gear 2b, so that the driven gear 31BK rotates smoothly, and all other driven gears rotate. The gears 31M, 31Y, and 31C rotate to perform full-color mode image formation.
[0038]
On the other hand, when switching to the monochrome mode, the motor 38 is rotated in the reverse direction as shown by the arrow B as shown in FIG. As a result, the driven gear 31BK tries to rotate, or the one-way clutch 12 of the clutch gear 2b acts to restrict the rotation of the driven gear 31BK. Therefore, the swing unit side plate 3 rotates clockwise, and the mesh between the drive gear 40 and the driven gear 31M and the mesh between the idle gears 34BK and Y and the driven gear 31Y are released.
The amount of rotation of the swing unit side plate 3 is detected by the sensor 13 in the same manner as described above, and the solenoid 10 acts at a position of a predetermined amount of rotation, and its pin 10a fits into the positioning hole 10b and is fixed at a predetermined position. Is done.
As described above, the monochrome mode image is formed.
[0039]
Switching to the full-color mode is performed by turning off the solenoid 10 and pulling out the pin 10a from the positioning hole 10b, whereby the swing unit side plate 3 rotates counterclockwise by the spring force of the spring 7 and returns to the original position. Here, when the motor 38 rotates forward, all the driven gears 31BK, 31M, 31Y, and 31C rotate, and the one-way clutch 12 does not restrain the rotation of the driven gear 31BK, so that the one-way clutch 12 rotates smoothly, and the image in the full-color mode is obtained. The formation takes place.
[0040]
Although the above-mentioned several embodiments have been described as the swing mechanism, the present invention is not limited to these embodiments, and any mechanism may be used as long as the swing unit swings in the full color mode and the monochrome mode.
[0041]
【The invention's effect】
1) According to the color image forming apparatus capable of switching between color modes according to the first aspect of the present invention, a swing unit is provided, and when the mode is switched, the swing unit is rotated to mesh the drive gear with the idle gear. Switching between the full-color mode and the monochrome mode can be easily performed by a simple method simply by changing the form. The oscillating unit is made compact and the device can be reduced in size and weight, and the switching does not use a group of gears as in the prior art, so that there is no rotation unevenness due to switching.
[0042]
2) According to the color image forming apparatus capable of switching the color mode according to the second aspect of the present invention, since the spring is used to return the swinging unit to the original position, the full color mode can be reliably returned. And smoothly.
[0043]
3) According to the color image forming apparatus capable of switching the color mode according to the third aspect of the present invention, since the ON / OFF of the solenoid is used as the swing mechanism, a large actuator is not required, and the apparatus can be downsized. And lighter weight.
[0044]
4) According to the color image forming apparatus capable of switching the color mode according to the fourth aspect of the present invention, the rotation of the driven gear connected to the central rotation shaft that supports the swing unit in a swingable manner as the swing mechanism. Is used. As a result, the swing unit is reliably rotated, the switching between the full-color mode and the monochrome mode is smoothly performed without using a special actuator, and the apparatus is downsized because a complicated gear mechanism and the like are not used. Lighter weight can be achieved.
[0045]
5) According to the color image forming apparatus capable of switching the color mode according to the fifth aspect of the present invention, since the one-way clutch is used as the swing mechanism, the swing unit is reliably rotated.
[0046]
6) According to the color image forming apparatus capable of switching the color mode according to the sixth aspect of the present invention, the rotation position of the swinging unit is accurately determined by the position detection and holding means, so that the mode switching is reliably and reliably performed. Performance can be improved.
[Brief description of the drawings]
FIG. 1 is a front view showing an embodiment of a swing mechanism for swinging a swing unit of the present invention.
FIG. 2 is a top view of FIG. 1;
FIG. 3 is a side view of FIG. 1;
FIG. 4 is a partial front view for explaining the operation of the swinging mechanism shown in FIG. 1;
FIG. 5 is a side view of FIG. 4;
FIG. 6 is a partial front view showing a swing state of the swing unit shown in FIG. 4;
FIG. 7 is a partial front view showing another embodiment of the swing mechanism of the swing unit of the present invention.
FIG. 8 is a side view of FIG. 7;
FIG. 9 is a partial front view showing the swinging operation of the swinging mechanism shown in FIG. 7;
10 is an enlarged partial sectional view showing a detailed structure of a solenoid for positioning the swing unit shown in FIG. 7 and the like.
FIG. 11 is a partial front view showing still another embodiment of the swing mechanism of the swing unit of the present invention.
FIG. 12 is a side view of FIG. 11;
FIG. 13 is a partial front view showing the swinging operation of the swinging mechanism shown in FIG. 11;
FIG. 14 is a configuration diagram illustrating the overall structure of a tandem-type color image forming apparatus that forms an image in a full-color mode of four colors.
FIG. 15 is a front view showing one embodiment of a drive transmission mechanism of the color image forming apparatus applied to the invention.
FIG. 16 is a top view of FIG. 15;
FIG. 17 is a side view of FIG. 15;
[Explanation of symbols]
1 swing unit
1a Swing unit
1b Swing unit
2 solenoid
2a restraining means
2b Clutch gear
3 Side plate of swing unit
3 'first swing unit side plate
3 "second swing unit side plate
4 Immobile side
5 Moving parts
6 Body
7 Spring
8 Positioning members
9 Brake mechanism
10 Solenoid
10a pin
10b Positioning hole
10c Positioning hole
11 Sensor
12 One-way clutch
13 Sensor
14 Color Image Forming Apparatus
15BK Image forming unit (black)
15M image forming unit (magenta)
15Y image forming unit (yellow)
15C Image forming unit (cyan)
16 Paper feed unit
17 Recording paper
18 Transfer belt
19 Polygon Scanner
20 Deflection mirror
21 Laser Scanner
22 Fixing unit
23BK photoreceptor (black)
23M photoconductor (magenta)
23Y photoreceptor (yellow)
23C photoconductor (cyan)
24BK developing device (black)
24M developing device (magenta)
24Y developing device (yellow)
24C developing device (cyan)
25BK charging device (black)
25M charging device (magenta)
25Y charging device (yellow)
25C charging device (cyan)
26BK Cleaning device (Black)
26M cleaning device (magenta)
26Y cleaning device (yellow)
26C cleaning device (cyan)
27BK transfer device (black)
27M transfer device (magenta)
27Y transfer device (yellow)
27C transfer device (cyan)
28 Scanner for reading
29 Image processing circuit
30BK center rotation axis (black)
30M center rotation axis (magenta)
30Y center rotation axis (yellow)
30C center rotation axis (cyan)
31BK driven gear (black)
31M driven gear (magenta)
31Y driven gear (yellow)
31C driven gear (cyan)
32 Body side plate
33 Drive unit side plate
34BK ・ Y idle gear (black / yellow)
34MC idle gear (magenta cyan)
35 Drive mechanism
36 rotation axis
37 Rotation axis
38 motor
39 Drive shaft
40 drive gear
41 separation claw

Claims (6)

Image forming units of four colors, black (BK), magenta (M), yellow (Y), and cyan (C), are arranged along the recording paper conveyance direction, and the center rotation of the photosensitive member of each image forming apparatus is performed. A driven gear supported by a shaft, a group of odd-numbered driven gears (BK · Y) and a group of even-numbered driven gears (M, C) are staggered in the axial direction, and are respectively shifted. And one of the odd-numbered group of driven gears and one of the even-numbered group of driven gears adjacent thereto. A color image forming apparatus comprising: a driving gear meshed with a driven gear; and a driving mechanism section including the driving source, wherein the driving mechanism can swing about the center rotation axis of one of the odd-numbered driven gears. , And holds the drive mechanism A swing unit for supporting the idle gear meshed with the driven gear; and a swing mechanism for swinging the swing unit to engage and disengage the drive mechanism and the idle gear with another driven gear. And a color image forming apparatus capable of switching between color modes. A spring for rotating the swing unit in a direction approaching the other driven gear side to mesh the idle gear with the other driven gear is provided between the swing unit and the stationary side of the device. 2. The color image forming apparatus according to claim 1, wherein the color image forming apparatus is interposed. The swing mechanism is a solenoid interposed between the swing unit and a stationary side of the device, and the solenoid is configured to rotate the swing unit against a spring force of the spring. The color image forming apparatus according to claim 2, wherein the color image forming apparatus is configured to be turned on at the time of the color image formation. 3. The collar according to claim 2, wherein the swing mechanism is provided with a restraining means for engaging with the driven gear on a central rotation shaft on which the swing unit is supported to restrain or release the rotation. A color image forming apparatus capable of mode switching. The swing mechanism portion includes a clutch gear with a one-way clutch that meshes with a driven gear on a central rotation shaft that supports the swing unit, and the clutch gear includes the driven gear in a normal recording paper feed direction. The drive source of the drive mechanism supported by the swinging unit is formed so as to be rotatable in forward and reverse directions. A color image forming apparatus capable of switching the color mode described in the above. The swing unit is provided with position detection and holding means for detecting the amount of rotation of the swing unit and detecting its rotational position, and for holding the swing unit at that position. A color image forming apparatus capable of switching between color modes according to claim 4.

Images