JP2000293003A - Color image forming equipment - Google Patents

Abstract

(57) Abstract: An object of the present invention is to provide an inexpensive color image forming apparatus that reliably switches drive between a color mode and a monochrome mode with low power consumption. A color image forming apparatus transmits a driving force of a driving motor to a black photoconductor via a driving pulley, a driving belt, a driving gear, and a photoconductor gear to rotate. When driven, the drive pulley 111, the photoconductor gear 107C,
The photoconductors 102C, 102M, and 102Y of the respective colors are rotationally driven via 107M and 107Y and connecting gears 116 and 117. When switching between the color mode and the monochrome mode, the driving force from the driving motor 112 is transmitted to the slide mechanism 130 for a predetermined time by the half-turn clutch 119, and the driving force from the driving motor 112 other than black is transmitted to the slide mechanism 130 by the slide mechanism 130. The transmission and the interruption to the photoconductors 102 </ b> Y to 102 </ b> C are switched, and the cam 134 is rotated to move the conveyance belt 105 and the photoconductors 102 </ b> Y to 102 </ b> C other than black.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a color image forming apparatus, and more particularly, to a color image forming apparatus for inexpensively switching between driving in a color mode and in a monochrome mode.

[0002]

2. Description of the Related Art In image forming apparatuses such as copiers and printers, colorization is progressing, but there are still many opportunities to output only black-and-white images, such as copying of document images, and black-and-white images account for a large proportion. I keep it.

Therefore, it is necessary to design a color image forming apparatus such as a color copying machine and a color printer in consideration of frequent black and white images.

For example, a color image forming apparatus has conventionally been
As in the full-color electrophotographic copying apparatus 1 shown in FIG. 6, a plurality of image forming units 2Y, 2M, 2C, and 2B that form images of each color of yellow, magenta, cyan, and black are transferred in the transfer paper transfer direction (see FIG. As shown by arrows in FIG. 6, the timing is adjusted by a pair of registration rollers 4 from a paper feed unit 3 and then fed to a transport belt 5 that is driven to rotate. Transfer belt 5
The image forming units 2Y, 2M, 2C, and 2
In B, the toner images of each color are sequentially transferred to a transfer sheet to form a color toner image on the transfer sheet. The full-color electrophotographic copying apparatus 1 transports the transfer paper on which the color toner image has been transferred to the fixing unit 6, and heats and presses the paper in the fixing unit 6 to fix the color toner image on the transfer paper. To be discharged.

That is, each of the image forming units 2Y, 2M, 2C, and 2B of the full-color electrophotographic apparatus 1 includes a drum-shaped photosensitive member 8Y, 8M, 8C, 8B, which functions as a latent image carrier.
The charging units 9Y, 9M, 9C, 9B, the exposure units 10Y, 10M, which are arranged around the photoconductors 8Y, 8M, 8C, 8B.
10C, 10B, developing units 11Y, 11M, 11C, 11
B and cleaning units 12Y, 12M, 12C, 12B
The photoconductors 8Y, 8M, 8C, and 8B are driven to rotate counterclockwise in FIG.

The full-color electrophotographic apparatus 1 includes a photoconductor 8
The surfaces of Y, 8M, 8C, and 8B are charged with charging units 9Y, 9M, 9C,
After uniformly charging at 9B, the exposed portions 10Y, 10M, 1
Exposure is performed with a pattern corresponding to an image to be output by the image forming units 0C and 10B to form electrostatic latent images on the surfaces of the photoconductors 8Y, 8M, 8C and 8B, and the developing units 11Y, 11M, 11C and 11
B to develop the electrostatic latent image to form photoconductors 8Y, 8M, 8C, 8B
A toner image is formed on the surface. The full-color electrophotographic apparatus 1 adjusts the timing from the paper feed unit 3 by the registration roller pair 4 and applies the photoconductors 8 of the image forming units 2Y, 2M, 2C, and 2B to the transfer paper conveyed by the conveyor belt 5.
The toner images are sequentially transferred from Y, 8M, 8C, and 8B, and a color toner image is formed on transfer paper. The full-color electrophotographic apparatus 1 is configured such that the photoconductors 8Y, 8M, 8C, 8
The toner remaining on the surface of B is cleaned by the cleaning units 12Y and 12Y.
M, 12C, and 12B, and the charging unit 9
After charging with Y, 9M, 9C, and 9B, the next image formation is performed in the same manner as described above.

The full-color electrophotographic apparatus 1 performs color conversion processing in an image processing unit (not shown) based on the intensity level of a color separation image signal sent from a personal computer or the like (not shown), and outputs black (B) and cyan (C). ), Magenta (M), and yellow (Y) color image data.
Exposure is performed using 0M, 10C, and 10B.

Laser scanners are used as the exposure units 10Y, 10M, 10C, and 10B. The exposure units 10Y, 10M, 10C, and 10B apply laser beams from laser light sources to polygon scanners 13Y and 13B.
M, 13C, and 13B, and the fθ lens 14
The optical path is bent and the light diameter is reduced at Y, 14M, 14C and 14 and the surfaces of the photoconductors 8Y, 8M, 8C and 8B are exposed. Writing in the exposure units 10Y, 10M, 10C, and 10B is performed by the polygon scanners 13Y, 13M, 13C, and 1C.
The rotation of 3B causes the photoconductors 8Y, 8M, 8C, 8
A latent image is written in the axial direction of B (main scanning), and the photoconductor 8Y,
The rotation of 8M, 8C, 8B causes the photoconductors 8Y, 8M, 8 to rotate.
Writing is performed in the direction orthogonal to the C and 8B axes (sub-scan).

The full-color electrophotographic apparatus 1 adjusts the position of each color of the toner image formed on the recording paper by transferring the recording paper sent from the paper feed unit 3 from the registration roller pair 4 to the transfer position of each color by the transport belt 5. The exposure start time is set such that the timing at which the images on the photosensitive members 8Y, 8M, 8C, and 8B are moved to the transfer positions coincides with the timing at which the images are transferred to the transfer positions.

In the full-color electrophotographic apparatus 1, the image forming units 2Y, 2M, 2C, 2
Since all of B are driven, when forming an image of only a black and white image, driving other than the black and white image forming unit 2B is a wasteful operation, and the color image forming units 2Y and 2Y other than the black and white image forming unit 2B are driven. Useless driving of 2M and 2C causes shortening of the life of the photosensitive member and each consumable part, which is a factor of increasing running cost.

Therefore, in order to avoid unnecessary operation of the non-black image forming units 2Y, 2M, 2C when forming only a black and white image, only the black image forming unit 2B is conventionally driven at the time of forming a black and white image. , Non-black photoconductors 8Y, 8M, 8
In order to avoid sliding friction between the transfer belts 5C and 8B and the transfer belt 5, the transfer belt 5 is separated from the photoconductors 8Y, 8M and 8C other than black (Japanese Patent Application Laid-Open Nos. 6-258914 and 9).
146383).

In a conventional image forming apparatus,
Generally, as shown in FIGS. 7 and 8, in the case of recording only a black and white image, the photosensitive member other than black is separated from the transport belt. That is, in FIG. 7 and FIG.
Is a pair of transport rollers 22 attached to the transfer unit 21
a, 22b and a tension roller 23, and the photosensitive members 24 of each color
Y, 24M, 24C and 24B are provided. The gear 25B of the black photoconductor 24B meshes with the motor gear 27B of the black photoconductor drive motor 26B, and the gear 25C of the cyan photoconductor 24C meshes with the motor gear 27C of the color drive motor 26C. . The gear 25M of the magenta photoconductor 24M and the gear 25Y of the yellow photoconductor 24Y are driven to rotate by the rotation of the gear 25C of the cyan photoconductor 24C via the connecting gears 28 and 29. Therefore, the black photoconductor 24B is rotationally driven by the black photoconductor drive motor 26B, and the photoconductors 24Y to 24C of colors other than black are driven by the color drive motor 26B.
C is driven to rotate.

In this conventional image forming apparatus, a transfer unit contact / separation motor 30 and a cam 31 are provided, and a motor shaft of the transfer unit contact / separation motor 30 and a drive shaft of the cam 31 are connected by a drive belt 32. Then, the cam 31 is driven to rotate by the transfer unit contact / separation motor 30. The cam 31 includes a yellow photoconductor 24Y and a magenta photoconductor 24M.
Are disposed in contact with the lower end of the transfer unit 21 between
When the cam 31 is rotated by the transfer unit contact / separation motor 30, the transfer unit 21 moves the yellow photoconductor 24Y side up and down around the contact position with the black photoconductor 24B, and moves the transport belt 20 to the black position. Photoconductor 2
The photoconductors 24Y, 24M, and 24C other than the photoconductors 4B are separated from each other and are brought into contact only with the black photoconductor 24B.

In this conventional image forming apparatus, when a color mode, that is, when a color image is formed, as shown in FIG.
Is moved away from the lower end of the transfer unit 21, and the conveyor belt 20 is brought into contact with all the photoconductors 24Y to 24B. In this state, the black photoconductor 24B is rotationally driven by the black photoconductor drive motor 26B, and the other photoconductors 24Y
-24C are driven to rotate by the color drive motor 26C.

Further, in this conventional image forming apparatus, when a monochrome mode, that is, when a black and white image is formed, as shown in FIG. Is driven to rotate the cam 31 half a turn, and the transfer unit 21 is moved to the black photosensitive member 24.
The conveyor belt 20 is moved away from the photoconductors 24Y, 24M, and 24C other than the black photoconductor 24B by moving the yellow photoconductor 24Y side up and down around the contact position with the black photoconductor 24B. Make contact.

Conventionally, as shown in FIG. 9, there is an image forming apparatus in which an electromagnetic crack is provided and a single driving motor rotates and stops the rotation of a photoconductor other than black.
In FIG. 9, the same components as those in FIGS. 7 and 8 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 9, a gear 25B of the black photosensitive member 24B has a motor gear 34 of the photosensitive member driving motor 33 attached thereto.
The drive gear 36 of the electromagnetic clutch gear 35 meshes with the gear 25C of the cyan photoconductor 24C. The drive shaft of the photoconductor drive motor 33 and the electromagnetic clutch gear 35 are connected by a drive belt 37, and the electromagnetic clutch gear 35 is driven to rotate by the photoconductor drive motor 33. The electromagnetic clutch gear 35 is driven by a photoconductor drive motor 33 transmitted via a drive belt 37 during excitation.
Is transmitted to the drive gear 36, and the cyan photoconductor 24C
Of the photoconductor drive motor 33 transmitted via the drive belt 37 to the drive gear 36 when the non-excitation is performed, so that the cyan photoconductor 24 is rotated.
The rotation of the gear 25C of C is stopped.

Therefore, this conventional image forming apparatus has:
In black mode, de-energize the electromagnetic clutch gear,
In the color mode, when excited, one photoconductor drive motor 33 can rotate and non-drive each of the photoconductors 24 </ b> Y to 24 </ b> B.

[0019]

However, such a conventional image forming apparatus needs improvement in order to reduce the cost and stabilize the operation.

That is, in the conventional image forming apparatus shown in FIGS. 7 and 8, the monochrome mode and the color mode are switched to rotate the photoconductors 24Y to 24B and make contact / non-contact with the conveyor belt 20. In this case, three motors 26B, 26C, and 30 are required, and the cost of the image forming apparatus is increased and the size of the image forming apparatus is increased.

In the conventional image forming apparatus shown in FIG. 9, the two motors 33 and 30 and the electromagnetic clutch gear 35 are used to switch between the monochrome mode and the color mode, and the photosensitive members 24Y to 24B. In the color mode, the electromagnetic clutch gear 35 is always energized, so that the power consumption increases, and energy saving is called for today. , There was a need for improvement. In addition, the motor 30 and the cam 31 are required to separate and contact the conveyor belt 20 and the photoconductors 24Y to 24B, which causes a problem that the cost of the image forming apparatus is increased and the image forming apparatus is enlarged.

Therefore, according to the first aspect of the invention, the driving force of one driving source is transmitted to the latent image carrier of the black image forming unit by the black driving force transmitting mechanism to be rotated, and the color driving force is transmitted. The transmission mechanism transmits and rotates the latent image carrier of the image forming unit of a color other than black to the latent image carrier, and when the mode is switched between the color mode and the monochrome mode, the driving force from a predetermined driving source of the color image forming apparatus is used. The driving force is transmitted to the cam mechanism for a predetermined time by the driving force transmitting / blocking mechanism, and the switching member is operated by the cam mechanism so that the driving force from the driving source that rotationally drives the latent image carrier carries the latent image in a color other than black. By switching between transmission to the body and blocking,
With a simple configuration, one driving source switches the rotation driving operation of the latent image carrier in the color mode and the monochrome mode, and the driving force transmission / shut-off mechanism is operated only for a predetermined time at the time of switching, so that it is inexpensive. It is another object of the present invention to provide a color image forming apparatus that can stably switch operation modes with low power consumption.

According to a second aspect of the present invention, the driving force transmitted from the driving force transmitting / blocking mechanism to the cam mechanism from the predetermined driving source is used to bring the transport belt into contact with a latent image carrier of a color other than black. A dedicated drive source is provided by transmitting to / separating the transport belt contact / separation mechanism to separate / contact the transport belt with a latent image carrier of a color other than black according to the color mode and the monochrome mode. Without switching between the color mode and the monochrome mode, the transport belt is brought into contact with / separated from the latent image carrier of a color other than black, so that the operation mode can be switched more stably at lower cost and with lower power consumption. It is an object of the present invention to provide a color image forming apparatus for performing the above.

[0024]

According to a first aspect of the present invention, there is provided a color image forming apparatus, which is disposed along a transport belt for transporting a recording medium, and is provided with black and other color images on each latent image carrier by an electrophotographic method. A plurality of image forming units that form toner images of the respective colors, and the latent image carriers of the image forming units of the respective colors are rotated in accordance with the color mode and the monochrome mode, and the toner images are formed on all the latent image carriers. Forming a color image by sequentially transferring the toner images on all the latent image carriers to the recording medium conveyed by the conveyance belt, and forming only the latent image carrier of the black image forming unit. To form a black toner image on the black latent image carrier and transfer the toner image on the black latent image carrier to the recording medium conveyed by the conveyance belt. A color image forming apparatus for forming a monochrome image, comprising: a black driving force transmission mechanism for transmitting a driving force of a predetermined one driving source to a latent image carrier of the black image forming unit to rotate the black image forming unit; A color driving force transmitting mechanism for transmitting the driving force of the source to the latent image carrier of the image forming unit of a color other than the black color and rotating the same. A switching member that switches between transmitting and blocking the transmission of the driving force from the driving source to the latent image carrier of a color other than black,
The color image forming apparatus is driven by a driving force from a predetermined driving source, rotates by a predetermined amount with respect to the shaft on which the switching member is mounted, and moves the switching member to a transmission side and a blocking side of the driving force. A cam mechanism, and a driving force transmission / interruption mechanism for transmitting a driving force from the predetermined driving source to the cam mechanism only while the cam mechanism rotates by the predetermined amount when switching between the color mode and the monochrome mode. The above purpose is achieved by providing.

According to the above configuration, the driving force of one driving source is transmitted to the latent image carrier of the black image forming unit by the black driving force transmitting mechanism and is driven to rotate, and the black driving force is transmitted by the color driving force transmitting mechanism. In addition to transmitting the rotation to the latent image carrier of the image forming unit of a color other than the above, the driving force from a predetermined driving source of the color image forming apparatus is transmitted and transmitted at the time of switching between the color mode and the monochrome mode. The interruption mechanism transmits the driving force to the cam mechanism for a predetermined time, and the cam mechanism operates the switching member to transmit the driving force from the driving source that rotationally drives the latent image carrier to the latent image carrier of a color other than black. The switching between the rotational driving operation of the latent image carrier in the color mode and the monochrome mode can be performed by a single driving source with a simple configuration. It can only be operated a drive force transmission-interrupting mechanism between, it is possible to perform inexpensive and stable switching of the operation mode saving power consumption.

In this case, for example, as set forth in claim 2, in the color image forming apparatus, the transport belt contact / separation mechanism for contacting / separating the transport belt from / to the latent image carrier of a color other than black. And transmitting the driving force from the predetermined driving source transmitted from the driving force transmitting / blocking mechanism to the cam mechanism to the transport belt contacting / separating mechanism, and performing the transport according to the color mode and the monochrome mode. The belt contacting / separating mechanism may further include a conveying belt contact / separation force transmitting mechanism for contacting / separating the conveying belt from / to the latent image carrier of a color other than the black.

According to the above configuration, the driving force transmitted from the driving force transmitting / blocking mechanism to the cam mechanism from the predetermined driving source is used to cause the transport belt to contact / contact the latent image carrier of a color other than black.
It is transmitted to the transport belt contacting / separating mechanism to separate, and the transport belt is contacted / separated with the latent image carrier of a color other than black according to the color mode and the monochrome mode, so that a dedicated driving source is not provided. According to the switching between the color mode and the monochrome mode, the transport belt can be brought into contact with / separated from the latent image carrier of a color other than black, so that the operation mode can be switched more stably at lower cost and with lower power consumption. It can be performed.

[0028]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. It should be noted that the embodiments described below are preferred embodiments of the present invention, and therefore, various technically preferable limitations are added. However, the scope of the present invention is not limited to the following description. The embodiments are not limited to these embodiments unless otherwise specified.

FIGS. 1 to 5 show an embodiment of the color image forming apparatus of the present invention. FIG. 1 shows a color image forming apparatus to which the embodiment of the color image forming apparatus of the present invention is applied. FIG. 2 is a front schematic configuration diagram of a transfer unit 101 as a latent image carrier and photoconductors 102Y, 102M, 102C, and 102B of the apparatus 100. These photoconductors 102Y and 102
M, 102C, and 102B form toners of respective colors of yellow, magenta, cyan, and black on the surfaces of the photoconductors 102Y, 102M, 102C, and 102B by electrophotography, and form color toner images on transfer paper. It is a part of the image forming unit for each color.

This embodiment is applied to a color image forming apparatus similar to the full-color electrophotographic copying apparatus shown in FIG.

In FIG. 1, a color image forming apparatus 100
Are photoconductors 102Y of each color along the transfer portion 101,
102M, 102C and 102B are disposed at predetermined intervals in the transfer direction of the transfer paper (left direction in FIG. 1). The transfer unit 101 is stretched over a pair of transfer rollers 103a and 103b and a tension roller 104. Transport belt 105
Are arranged. The transport belt 105 is a transport roller 1
When the drive motors 03a and 103b are driven to rotate by a drive motor (not shown), they are driven to rotate clockwise in FIG.

The transfer unit 101 is provided with the black photosensitive member 1
When the yellow belt 102B and the conveyor belt 105 are in contact with each other, the end on the side of the yellow photoconductor 102Y is connected to the support members 106a and 106b shown in FIG. 2 via the shaft of the conveyor roller 103a as shown by a solid line and a two-dot chain line in FIG. Are supported so as to be able to swing up and down.

Each photoconductor 102Y, 102M, 102C,
102B is its axis 102Ya, 102Ma, 102C
a, 102Ba (see FIG. 2) to the photoreceptor gears 107Y, 1
07M, 107C and 107B are attached, and a drive gear 108 meshes with the black photoconductor gear 107B. Also, the cyan photoconductor gear 107C has
The color driving gear 109 meshes with the driving gear 108.
Pulley 110 and collar drive gear 109 connected to
A drive belt 115 is stretched over a drive pulley 111 connected to the drive pulley 111, a drive pulley 113 attached to a drive shaft of the drive motor 112, and a tension pulley 114. Each photoconductor 102Y, 102M, 102C, 102B
Are the axes 102Ya, 102Ma, 102Ca, 10
2Ba is rotatably supported by the support members 106a, 106b, 106c.

The photoconductor gear 107C for cyan, the photoconductor gear 107M for magenta, and the photoconductor gear 107M for magenta
And the yellow photoconductor gear 107Y are connected via connection gears 116 and 117, respectively.

Accordingly, when the drive pulley 113 is driven to rotate by the drive motor 112, the black photoconductor 1 is driven via the drive belt 115, the drive pulley 110, the drive gear 108 and the black photoconductor gear 107B.
02B is rotationally driven, and the cyan photosensitive member 102C is rotationally driven via the drive belt 115, the drive pulley 111, the color drive gear 109, and the cyan photosensitive member gear 107C. When the cyan photoconductor gear 107C is driven to rotate, the coupling gear 116 and the magenta photoconductor gear 1 are rotated.
07M, connecting gear 117 and yellow photoconductor gear 10
The magenta photoconductor 102M and the yellow photoconductor 102Y are respectively driven to rotate via 7Y.

The drive pulley 110 and the drive pulley 11
3. The tension pulley 114, the drive belt 115, the drive gear 108, and the photoreceptor gear 107B apply the driving force of the drive motor 112 as one drive source to the black photoreceptor 10.
The drive pulley 110, the drive pulley 111,
Drive pulley 113, tension pulley 114, drive belt 115, drive gear 109, photoconductor gear 107C, 10
The 7M and 107Y and the coupling gears 116 and 117 function as a color driving force transmission mechanism that transmits the driving force of the driving motor 112 as one driving source to the photoconductors 102C, 102M, and 102Y of each color other than black and rotationally drives them. are doing.

As shown in FIG. 2 which is a bottom view of FIG. 1, a gear 118 fixed to the shaft 102Ba of the black photosensitive member 102B is provided with a gear 12 of a half-turn clutch 119.
0 meshes with each other, and a pulley 121 is fixed to a shaft to which the half-turn clutch 119 is attached.

As shown in FIGS. 3 and 4, the half-turn clutch 119 includes a solenoid 122, a switch 123 and a claw 124. When the solenoid 121 is not excited, the switch 123 is caught by the claw 124 and the gear 1 is disengaged.
No rotational force is transmitted from the motor 20 to the pulley 121 via the shaft. Further, the half-turn clutch 119 includes a solenoid 121
Is excited for a very short time, the switch 123 is disengaged from the pawl 124, torque is transmitted from the gear 120 to the shaft on which the pulley 121 is mounted, and the shaft rotates half a
4, when the switch 123 is caught, the gear 120
From the shaft to the shaft. That is, in a normal state where the motor is not excited, the gear 120 is in a state of idling with respect to the shaft, and is in a state where torque is not transmitted to the pulley 121.

The pulley 121 is provided with a belt 128 stretched over a pulley 125, a pulley 126, and a tension pulley 127 (see FIG. 1).
Is the shaft 12 to which the drive pulley 111 is attached.
9 attached.

A slide mechanism 130 is arranged on the shaft 129 between the pulley 125 and the driving pulley 111. As shown in FIG. 5, the slide mechanism 130 has a pulley 125, a slide member 131, a color drive gear 109, and a drive pulley 111 mounted on the shaft 129 in this order, and presses the slide member 131 and the drive pulley 111. A spring 132 and the like are provided. The slide member 131 has a shaft 129 formed in a substantially D-shaped cross section, and a shaft hole of the slide member 131 formed in a shape corresponding to the cross-sectional shape of the shaft 129, so that the slide member 131 moves in the rotational direction with respect to the shaft 129. Is regulated, and is attached to the shaft 129 so as to be movable only in the axial direction (thrust direction). In the thrust member 131, a cylindrical portion 131a is formed on one surface in the axial direction of the shaft 129, and the collar driving gear 109 is attached with the cylindrical portion 131a inserted in the shaft hole. It is rotatable with respect to the slide member 131. The pulley 125 has a pair of protrusions 125 a formed on a surface on the slide member 131 side.
A slide protrusion 131b that engages with the protrusion 125a of the pulley 125 when rotating in one direction is formed.

Driving pulley 1 of the color driving gear 109
A pair of slide projections 109a are formed on the surface on the 11th side, and a pair of projections 111a are formed on the surface of the drive pulley 111 on the side of the color drive gear 109.

The pressing spring 132 penetrates through the shaft hole of the color driving gear 109 and the cylindrical portion 1 of the slide member 131.
The slide member 131 and the drive pulley 111 are pressed in a direction in which the slide member 131 and the drive pulley 111 are separated from each other.

The pulley 125 has the belt 1
28, and the belt 1
15 are wound.

When the pulley 125 is rotated by 90 degrees by the belt 128, the slide mechanism 130 moves the protrusion 125a of the pulley 125 to the slide protrusion 13 of the slide member 131.
1b, the slide member 131 is slid in the direction of the color drive gear 109 along the shaft 129, and the slide of the slide member 131 causes the color drive gear 109 to slide.
Also slides in the direction of the pulley 111, and the color drive gear 1
09 slide projection 109a is connected to projection 11 of pulley 111.
1a. In this state, the pulley 111
5, the rotation of the pulley 111 is transmitted to the color drive gear 109, and the cyan photoreceptor gear 107C is rotated by the color drive gear 109.
Is rotated, and the cyan photoconductor 102C is rotationally driven.

In this state, the pulley 125 is
When further rotated by 90 degrees, the protrusion 125 a of the pulley 125 is
b, the slide member 131 and the color drive gear 109 are urged in the direction of the pulley 125 by the pressing spring 132, and the slide protrusion 1 of the color drive gear 109
09 is disengaged from the projection 111a of the pulley 111, and the transmission of the rotation of the pulley 111 to the collar drive gear 109 is released.

The slide mechanism 130 functions as a cam mechanism incorporating a slide member 131 as a switching member.

Referring again to FIG. 1 and FIG.
A pair of cams 134 that abut the bottom of the transfer unit 101 and swing the transfer unit 101 are fixed to the shaft 133 to which the unit 6 is fixed. The cam 134 is rotated by the pulley 126 by 180 degrees. By swinging the transfer unit 101 upward,
In addition, swing downward.

Next, the operation of the present embodiment will be described. The color image forming apparatus 100 according to the present embodiment includes a transfer unit 101 and a photoconductor 102 in a monochrome mode and a color mode.
Y, 102M, 102C, and 102B can be stably and detachably connected to the semi-rotating clutch 119 by the operation of the solenoid 122 for a short time and the operation of the slide mechanism 130 in an inexpensive configuration and with reduced power consumption. There is a feature.

Accordingly, the pulley 126, the shaft 133 and the cam 134 function as a transport belt contact / separation mechanism, and the belt 128 functions as a transport belt contact / separation force transmission mechanism.

That is, the color image forming apparatus 100
In the color mode as an initial state, in the color mode, the cam 134 is located below the transfer unit 101, and the transfer unit 101 is located at a state position indicated by a solid line in FIG. Body 102Y, 102M, 102C,
The transport belt 105 that transports along the 102B is in contact with all the photoconductors 102Y, 102M, 102C, and 102B.

That is, in a normal state, the solenoid 121 of the half-turn clutch 119 is not energized,
In this state, the half-turn clutch 119 is
Is idle with respect to the shaft, and the pulley 12
1 is not transmitting torque.

At this time, the slide mechanism 130 causes the protrusion 125a of the pulley 125 to ride on the slide protrusion 131b of the slide member 131, and causes the slide member 131 to slide the color drive gear 109 in the direction of the pulley 111, as shown in FIG. The slide projection 109a of the collar drive gear 109 and the projection 111a of the pulley 111 are engaged.

In this state, when the drive motor 112 rotates, the pulleys 110 and 111 are driven to rotate by the drive belt 115, and the drive gear 108
And the black photoconductor 10 via the photoconductor gear 107B
2B is driven to rotate.

When the pulley 111 is driven to rotate, now
As described above, the rotation of the pulley 111 is
09, the pulley 111
, The color drive gear 109 is rotated, and the rotation of the color drive gear 109 causes the cyan photoconductor gear 107C to rotate.
, The cyan photoconductor 102C is rotationally driven. The rotation of the cyan photoconductor gear 107C is sequentially transmitted to the magenta photoconductor gear 107M and the yellow photoconductor gear 107Y via the connection gear 116 and the connection gear 117, and the magenta photoconductor 102M and the yellow photoconductor 102Y is driven to rotate.

Accordingly, in the color mode, all the photosensitive members 102Y and 102 are driven by one drive motor 112.
M, 102C, and 102B can be rotationally driven.

Next, when the monochrome mode is designated by the operation unit or the like of the color image forming apparatus 100, the color image forming apparatus 100 drives the drive motor 112 to rotate for a predetermined time, and the solenoid 121 of the half-turn clutch 119.
Is energized for a very short time to excite. Half-turn clutch 11
9 is a gear rotated by a gear 118 fixed to a shaft 102Ba of a black photosensitive member 102B that is rotationally driven by a drive motor 112 when a solenoid 121 is excited for a very short time and a switch 123 is disengaged from a claw 124. When the torque is transmitted from 120 to the shaft on which the pulley 121 is attached, and the shaft rotates a half turn to catch the switch 123 on the next claw 124, the state is not again transmitted from the gear 120 to the shaft. .

When the pulley 121 is rotated half a way in this manner, the pulley 121, the pulley 125, and the pulley 126
Of the pulley 1 is rotated
The rotation of 26 rotates the cam 126 by 180 degrees, and causes the transfer unit 101 to swing upward as shown by a two-dot chain line in FIG. By the upward swing of the transfer unit 101, the transport belt 105 provided in the transfer unit 101 causes the color photoconductors 102Y and 102Y other than the black photoconductor 102B.
M, move away from 102C.

The rotation of the belt 128 causes the pulley 1 to rotate.
When the lever 25 is rotated by 90 degrees, the slide mechanism 130 causes the protrusion 125 a of the pulley 125 to descend from above the slide protrusion 131 b of the slide member 131, and the pressing spring 132
As a result, the slide member 131 and the color drive gear 109 are urged in the direction of the pulley 125, and the engagement between the slide protrusion 109a of the color drive gear 109 and the protrusion 111a of the pulley 111 is released, and as shown in FIG.
Is transmitted to the color drive gear 109.

In this state, the color image forming apparatus 100 rotates the drive motor 112 to form a monochrome image. That is, when the drive motor 112 is rotationally driven, the pulley 110 and the pulley 111 are rotated by the drive belt 115, and the drive gear 108 and the photosensitive member gear 1 are rotated.
The black photosensitive member 102B is rotationally driven via the switch 07B. However, even if the pulley 111 is driven to rotate, the rotation of the pulley 111 is not transmitted to the gear 109, and the pulley 111 is idle. Therefore, the color photoconductors 102Y, 102M, and 102C are in a stopped state.

When the monochrome mode is switched to the color mode, the color image forming apparatus 100 again
The solenoid 120 of the half-turn clutch 119 is energized for a very short time to rotate the pulley 121 by half a turn. When the pulley 121 rotates a half turn, the cam 134 rotates downward as shown by the solid line in FIG. 1 to release the upward swing of the transfer unit 101. Further, the pulley 125 rotates 90 degrees, the slide protrusion 109a of the color drive gear 109 of the slide mechanism 130 engages with the protrusion 111a of the pulley 111, and the rotation of the pulley 111 is transmitted to the color drive gear 109, Color photoconductors 102Y, 102M, 10
2C is rotationally driven.

As described above, the color image forming apparatus 100 of the present embodiment has the drive motor 112 as one drive source.
Is transmitted to the photoreceptor 102B of the black image forming unit by the black driving force transmitting mechanism and is rotated, and the photoreceptor of the image forming unit of colors other than black is transmitted by the color driving force transmitting mechanism. 102Y, 1
02M and 102C to be driven to rotate,
At the time of switching between the color mode and the monochrome mode, the drive motor 112 which is a predetermined drive source of the color image forming apparatus 100
Is transmitted to the slide mechanism 130 for a predetermined time by the half-turn clutch 119, and the slide mechanism 131 is operated by the slide mechanism 130, so that the drive motor 11
2, the photoreceptors 102Y of a color other than black with a driving force of 2
The transmission to 102M and 102C and the interruption are switched.

Accordingly, it is possible to switch the rotation driving operation of the latent image carrier between the color mode and the monochrome mode with a simple configuration and one driving source (drive motor 112), and to perform a predetermined operation at the time of the switching. It is only necessary to operate the solenoid 120 of the half-turn clutch 119 only for the time,
The operation mode can be switched stably at low cost and with low power consumption.

The driving force from the driving motor 112 transmitted from the half-turn clutch 119 to the slide mechanism 130 causes the conveyor belt 105 to contact / separate from the photoconductors 102Y, 102M, 102C of colors other than black. The transport belt 105 is brought into contact with / separated from the photoconductors 102Y, 102M, and 102C of colors other than black in accordance with the color mode and the monochrome mode.

Therefore, without providing a dedicated driving source, the transport belt 105 is switched to the photosensitive member 102 of a color other than black in accordance with switching between the color mode and the monochrome mode.
Y, 102M, and 102C can be contacted / separated from each other, so that the operation mode can be switched more stably at lower cost and with lower power consumption.

Although the invention made by the inventor has been specifically described based on the preferred embodiments, the invention is not limited to the above-described embodiment, and various modifications may be made without departing from the spirit of the invention. It goes without saying that it is possible.

[0066]

According to the color image forming apparatus of the present invention, the driving force of one driving source is transmitted to the latent image carrier of the black image forming unit by the black driving force transmitting mechanism and rotated. The color image forming unit is driven by a color driving force transmission mechanism and transmitted to the latent image carrier of an image forming unit of a color other than black to be rotationally driven. The driving force from the driving source is transmitted to the cam mechanism for a predetermined time by the driving force transmitting / blocking mechanism, and the switching mechanism is operated by the cam mechanism, so that the driving force from the driving source for rotating and driving the latent image carrier is black. Since the transmission and blocking of the other colors to the latent image carrier are switched, the rotation driving operation of the latent image carrier in the color mode and the monochrome mode can be switched with a simple configuration and with one driving source. It is, it is possible to operate the driving force transmission-interrupting mechanism only predetermined time switching,
The operation mode can be switched stably at low cost and with low power consumption.

According to the second aspect of the present invention, the driving force transmitted from the driving force transmitting / blocking mechanism to the cam mechanism from the driving force transmitting / blocking mechanism of the color image forming apparatus is applied to the conveying belt so that the conveying belt carries latent images of colors other than black. It is transmitted to a conveyor belt contact / separation mechanism for contacting / separating from the body, and according to the color mode and the monochrome mode, the conveyor belt is brought into contact / separation with the latent image carrier of a color other than black. , The conveyance belt can be brought into contact with / separated from the latent image carrier of a color other than black in accordance with the switching between the color mode and the monochrome mode, so that it is more inexpensive and stable with less power consumption. The operation mode can be switched.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a transfer section and a photosensitive member of a color image forming apparatus to which an embodiment of the color image forming apparatus of the present invention is applied.

FIG. 2 is a bottom view of the color image forming apparatus of FIG.

FIG. 3 is an enlarged view of a half-turn clutch and a slide mechanism of FIG. 2 in a monochrome mode.

FIG. 4 is an enlarged view of a half-turn clutch and a slide mechanism of FIG. 2 in a color mode.

FIG. 5 is an exploded perspective view of the slide mechanism of FIG. 2;

FIG. 6 is a schematic front view of a conventional color image forming apparatus.

FIG. 7 is a schematic front view of a conventional transfer unit and a photosensitive member in a color mode.

FIG. 8 is a schematic front view of the conventional transfer unit and photosensitive member in FIG. 7 in a monochrome mode.

FIG. 9 is a front schematic configuration diagram of another example of a conventional transfer unit and a photosensitive member portion.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 color image forming apparatus 101 transfer unit 102Y, 102M, 102C, 102B photoreceptor 102Ya, 102Ma, 102Ca, 102Ba shaft 103a, 103b transport roller 104 tension roller 105 transport belt 106a, 106b, 106c support member 107Y, 107M, 107C, 107B Photoreceptor gear 108 Drive gear 109 Color drive gear 109a Slide projection 110, 111, 113 Drive pulley 111a Projection 112 Drive motor 114 Tension pulley 115 Drive belt 116, 117 Connection gear 118 Gear 119 Half-rotation clutch 120 Gear 121 Pulley 122 Solenoid 123 Switch 124 Claw 125, 126 Pulley 125a Projection 127 Tension pulley 128 Belt 129 Shaft 130 Slur Guide mechanism 131 Slide member 131a Cylindrical part 131b Slide protrusion 132 Press spring 133 Shaft 134 Cam

Claims (2)

[Claims] A plurality of image forming units disposed along a conveyor belt for conveying a recording medium and forming black and other color toner images on respective latent image carriers by electrophotography; In accordance with the mode and the monochrome mode, the latent image carriers of the image forming units of the respective colors are rotated to form toner images on all the latent image carriers, and all of the latent image carriers are transferred to the recording medium conveyed by the conveyance belt. The toner images on the latent image carrier are sequentially transferred to form a color image, and only the latent image carrier of the black image forming unit is rotated to form a black toner image on the black latent image carrier. A color image forming apparatus for forming a monochrome image by transferring a toner image on the black latent image carrier to the recording medium formed and conveyed by the conveyance belt, A black driving force transmitting mechanism for transmitting the driving force of the two driving sources to the latent image carrier of the black image forming unit to rotate the image forming unit, and the driving force of the driving source to the image forming units of colors other than black A color driving force transmission mechanism that transmits the latent image carrier to the latent image carrier to rotate the color driving force transmission mechanism, and the color driving force transmission mechanism moves in a predetermined axial direction and transmits the driving force from the driving source other than the black color. A switching member for switching between transmission and blocking of the color to the latent image carrier, and a predetermined amount with respect to the shaft on which the switching member is mounted, driven by a driving force from a predetermined driving source of the color image forming apparatus. A cam mechanism that rotates to move the switching member to the transmission side and the cutoff side of the driving force; and, when switching between the color mode and the monochrome mode, the cam mechanism rotates from the predetermined drive source only during the predetermined amount of rotation. Driving force Serial color image forming apparatus characterized by comprising a driving force transmission-interrupting mechanism for transmitting to the cam mechanism. 2. The color image forming apparatus according to claim 1, further comprising: a conveyance belt contact / separation mechanism for bringing the conveyance belt into contact with / separating from the latent image carrier of a color other than black; A drive force from the predetermined drive source transmitted to a mechanism is transmitted to the transport belt contact / separation mechanism, and the transport belt is attached to the transport belt contact / separation mechanism according to the color mode and the monochrome mode, except for the black belt. 2. The color image forming apparatus according to claim 1, further comprising: a conveying belt contact / separation force transmission mechanism for contacting / separating the latent image carrier of another color.