JPS6228776A - Image forming device - Google Patents

Abstract

PURPOSE:To eliminate ineffective time and to minimize the picture-formation- impossible time, so as to extend the life of developing devices, by moving one of the developing devices after a copying button is depressed and copying operation starting designation is inputted and bringing a selected developing device closer to a photosensitive drum. CONSTITUTION:If the user of this image forming device depresses a color change-over switch on a console panel which is not shown in a figure when a developing device 10 is selected, the using mode of another developing device 11 is set. When the color change-over switch is again depressed under the developing device 11 using mode, the using mode of the developing device 10 is again set. When a copying button is depressed under the developing device 10 using mode, copying operations are started without turning on a pulse motor 79. On the other hand, when the copying button is depressed under the developing device 11 using mode, the pulse motor 79 is turned on and, at the point where the switch is turned off, the motor 79 is turned off and a photosensitive drum is rotated. Thus copying operations are started. Therefore, the movement of the developing devices whenever a user makes selection switching operations can be avoided and, as a result, ineffective operations can be eliminated.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to an image forming apparatus, such as a color copying machine, which has two developing units each capable of developing different colors, and is capable of two-color copying. Regarding equipment.

[Technical background of the invention and its problems] Recently, as this type of color copying machine, two developing units movable toward and away from the photosensitive drum, which is the developing area, are used, for example, a black developing device. A developing device containing a red developer and a developing device containing a red developer are arranged to face the photosensitive drum, and the user moves these developing devices according to a selection switching operation, and one developing device is used as a photosensitive drum. It has been considered that the electrostatic latent image on the photoreceptor drum is developed by a developing device placed close to the photoreceptor drum, thereby making a desired copy.

In this case, if the developer is moved every time the user changes the selection, for example, if the wrong selection is made due to an erroneous operation, the developer will move and must be returned to the original selection state, which is wasteful. This causes a problem in that the time during which copying is not possible is lengthened, and left-hand movements such as the movement of the developing device are also shortened due to unnecessary operations.

[Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to eliminate unnecessary operations, minimize the time during which image formation is not possible, and extend the life of the moving mechanism of the current device. An object of the present invention is to provide an image forming apparatus that can be used to improve the image quality.

In order to achieve the above object, the present invention is configured such that the developing unit is moved after the start of the image forming operation is instructed.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a two-color copying machine as an example of an image forming apparatus according to the present invention. That is, the reference numeral 1 denotes the back copying machine main body, and the upper part of this main body 1 is provided with a document table 2. On the right side of the main body 1 is a paper feed cassette 3,
4, and a paper discharge tray 5 is attached to the left side. Note that the cassette cover of the upper paper feed cassette 3 serves as a manual paper feed table 6 for manually feeding paper as appropriate. Further, a photoreceptor drum 7 is disposed approximately in the center of the main body 1, and around the photoreceptor drum 7 there is a charger 8 for charging, an exposure optical system 9, and a first optical system for two-color development.
．． Second developing devices io and ii, a transfer charger 12, a stripping charger 13, a cleaning device 14, a static elimination lamp 15, and the like are arranged in this order.

Further, in the lower part of the main body 1, a paper feed roller 16. ... and separation roller 1 to prevent double sheet removal.
7, . A paper transport path 20 leading to the paper output tray 5 via the section 19
is formed.

A registration roller 21 is provided on the upstream side of the image transfer section 19 of the paper conveyance path 20, and a heat roller 22 and a paper discharge roller 23 as a fixing device are provided on the downstream side.

The exposure optical system 9 includes an exposure lamp 24 that reciprocates along the lower surface of the document table 2 in the direction of the arrow in the figure and irradiates the document with light;
and a mirror 2 that reflects light reflected from the original in a predetermined direction.
5, and a mirror 27.5 that moves in the same direction at a speed of 17'2 in synchronization with the exposure lamp 24 and mirror 25, and reflects the reflected light from the mirror 25 toward the lens unit 26 side.
28, a mirror 29.30 that reflects the reflected light that has passed through the lens unit 26 in a predetermined direction, and this mirror 30.
and a fixed mirror 31 that reflects light reflected from the photoreceptor drum 7 toward the photoreceptor drum 7 side.

Therefore, the exposure lamp 24 and the mirror 25 are
At the same time, the mirrors 27 and 28 move in the same direction at half the speed in synchronization with this movement, so that the rough stone on the document table 2 is scanned with light and rotated in advance. An electrostatic latent image corresponding to the image of the document is formed on the photosensitive drum 7 which is uniformly charged by the charging device 8. The static N latent image thus formed is the first. A sheet of paper that is opposed to one of the second developing devices 10 and 11 selected and developed into a developer image is sent to the image transfer section 19 and fed by the registration rollers 21. A developer image is transferred thereon. The sheet to which this developer image has been transferred is peeled off from the surface of the photoreceptor drum 7 by a peeling charger 14, and then led to a heat roller 22 through an inter-sheet feeding path 20, where the transferred developer image is After the agent image is fixed, the paper is discharged to the paper discharge tray 5 by the paper discharge roller 23. On the other hand, after the developer image has been transferred onto the paper, the surface of the photoreceptor drum 7 is cleaned of residual developer by facing the cleaning device 14, and the afterimage is roughly erased by the static elimination lamp 15, and the next copy is made. Ready for action.

Said 1st. The second developing devices 10 and 11 are each provided with a developing roller 33 in a casing 32, and the first developing device 10 located on the lower stage side stores, for example, a black developer Da.
For example, a red developer Db is stored in the second developing device 11 located on the upper stage side. Note that the developer [1a, [)b] is a two-component developer consisting of a 1-ner and a carrier.

As shown in FIGS. 2 and 3, the developing roller 33 fits into a magnet roller 34 installed between both side walls of the casing 32 and the outer periphery of the magnet roller 34, and is connected to the magnet roller 534. The rotary sleeve 35 is rotatably supported by the rotary sleeve 35. The magnet roller 34 has a holder 3 on the outer peripheral side of the shaft 36.
7 through a plurality of magnetic poles 38. ...Rotating sleeve 35
These magnetic poles 38,...
The developer Da is applied to the outer circumferential surface of the rotating sleeve 35 due to the action of
A magnetic brush is formed by (Db). One end of the shaft 36 passes through one side wall of the casing 32, and is rotated by a support plate 40 attached to the outer surface of the casing 32 via screws 39, as shown in FIGS. 4 and 5. The other end is fixed to the other side wall of the casing 32 via a screw 41. The rotary sleeve 35 is rotatably supported via the shaft 36 and has a protruding tube 42 on one end surface, which overlaps the outer periphery of the shaft 36 to form one side wall of the casing 32. A drive gear 43 is attached to the penetrating end thereof. The drive gear 43 is connected to a developing device drive mechanism (not shown).

Also, 1st. Each casing 32 of the second developer 10.11
．． 32, as shown in FIG.
．． 48 are arranged, and openings 49° 49 are formed in these frames 48.48, and these openings 48.
At 9.49, both ends of the casings 32, 32 are loosely engaged.

Guides 51, 52, 53, 54 each having an elongated guide hole 50 are attached to the frames 48, 48. One end of the shaft 36, 36 protruding from one end surface of the casing 32° 32, and the casing 3
A bin 46.46 disposed on one side of the guide 51, 52, 53, 54 of each guide hole 50.・・・
・Each M is fitted in a movable manner. Also, adjacent to each frame 48°48 is a lever 60.61.62.63.
, and links 64, 65, 66, 67 rotatably connected to these levers 60, 61, 62, 63 are provided. The said levers 60.62 and 61.63
are connected to each other by drive shafts 68°68, and the rotation of these drive shafts 68°68 causes the links 64,
66, B and 65°67 are designed to reciprocate integrally. As shown in FIGS. 7 and 8, each of the links 64 to 67 is slidably joined to the side surface of the frame 48, and a sliding hole 70 is provided in the -i section along the longitudinal direction. A support hole 71 is formed in the side surface of the frame 48 in correspondence with the slide hole 70 . The guide bushing core 2 is slidably fitted across the sliding hole 70 and the support hole 71, and the guide bushing 72 is held in the sliding hole 70 by a spring 73.
is elastically biased towards the tip side. In this way, each link 64-67 has a guide bush 72. ... are provided, and these guide bushes 72. ...Casing 3
Bins 45, 45.47° 47 provided at 2.32 are rotatably fitted.

Further, an interlocking arm 75 is attached to one end of the drive shaft 68.68.
．． 76 are attached, and these interlocking arms 7
An interlocking cam 77 is provided opposite to 5.76. A gear 78 is attached to this interlocking cam 77, and an output shaft 80 of a pulse motor 79 meshes with this gear 78. As shown in FIGS. 9 and 10, the interlocking cam 77 includes a cam body 83 formed by integrally forming a convex portion 82 on a part of the peripheral surface of a disk, and a cam body 83 that extends along the circular surface of this cam body 83. It is integrally constructed with a guide wall 85 which is arranged as shown in FIG. A microswitch 86 as a detector for detecting the position of the developing device is provided at a predetermined portion on the outside of the guide wall 85.

This switch 86 is turned on at the moment when the first developer 10 is completely moved toward the photoreceptor drum 7 side by the rotation of the interlocking cam 77, and when the interlocking cam 77 further rotates, the second developer 11 is moved toward the photoreceptor drum 7. It has a structure that turns it off the moment it moves to the side. Furthermore, rotating rollers 87 and 88 are provided at each end of the series VJ7-mem 75 and 76, and these rotating rollers 87 and 88 are fitted into the groove 84 at a constant interval so as to be freely movable. ing.

In addition, 1. Each casing 32 of the second developer 10.11
, 32 includes a stirring body 90 for stirring the developer, a scraper 91 for scraping off the developer on the developing roller 33, and a developer (
A replenishment mechanism 92 for replenishing toner is provided.

When the developing operation is on standby, as shown in FIG. The developing rollers 33, 33 of the second developing device 10.11 are respectively retracted from the photosensitive drum 7, and there is a relatively large gap between them! , L2, and faces the photosensitive drum 7. At this time, the first. Second
Each bin 46, 46 and shaft 3 of developing device 10°11
There is a slight play G between 6.36 and the rear edge of the guide hole 50, . . . of each guide 51, 52, 53, 54.

... are left, and each guide bush 72. ...is spring 73. The sliding hole 70. ...
1. Further, the convex portion 82 of the interlocking cam 77 faces a position away from the rotating rollers 87 and 88.

In this state, when the user performs a selection switching operation for the first developing device 10, the pulse motor 79 operates, the interlocking cam 77 rotates, and the convex f
The rotary roller 87 is pressed by the rotary roller 87, and the motion cam 77 stops rotating at this pressed position.The interlocking arm 75 rotates clockwise in response to the pressure on the rotary roller 87, and this operation is driven. It is transmitted to the links 64, 66 via the shaft 68 and the lever 60° 62, and these links 64, 66 move toward the side where the photosensitive drum 7 is disposed. The protruding height of the convex portion 82 is determined by the h1 interlocking arm 75.
When the length of the lever is 21 and the length of the lever 60°62 is ℃2, the G1 direction is (21/λ2)h.

Due to such movement of the links 64 and 66, the first developing device 1o moves to the side where the photosensitive drum 7 is disposed, and its shaft 36 and the bin 46 come into contact with the leading edges of the guide holes 50 and 50, and the developing roller 33 approaches the photoreceptor drum 7. The above links 64 and 66 are the shaft 36 of the @1 developer 10.
Even after the bottle 46 comes into contact with the tip edge of the guide hole 50.50, it continues to move slightly, and due to this D action, the guide bush 72.72 is linked with the first current device 1o in a state where it is stopped integrally. 64.66 opens against its guide bushing 72.72 against the spring 73.73, that is, while compressing the spring 73.73, thereby causing the distal edges of the sliding holes 70, 70 and the guide bushing to open. A gap G2 is formed between 72 and 72. i.e. link 64.6
6's movement stroke G+ and the movement stroke of the first developing device 10
- There is a relationship [Ql > G3] between the springs 73.73 and the Roku G3, and based on this, the springs 73.73 are compressed, and the elastic force of these springs 73.73 causes the first current (S unit 10
The shaft 36 and the bottle 46 of the guide hole 50.50 are pressed so as to reliably abut on the leading edge of the guide hole 50.50, thereby ensuring the positioning of the first developing device 10 and the developing roller 3
3 faces the circumferential surface of the photoreceptor drum 7 in close proximity with a predetermined width. Then, as the rotating sleeve 35 rotates, the acid-N latent image on the photoreceptor drum 7 is developed by the magnetic brush rim of the developer [)a formed on the outer peripheral surface of the rotating sleeve 35 by the action of the magnet roller 34. , visualized. At this time, since the developing roller 33 of the second developing device 11 is retracted at a large distance from the photoreceptor drum 7, the developer Db on this developing roller 33 is inadvertently transferred to the photoreceptor drum 7.
Therefore, the first developing device 1
Accurate development can be performed with 0.

On the other hand, when the user performs a selection switching operation for the second developing device 11, the pulse motor 79 operates and the interlocking cam 77 rotates, causing the convex portion 82 to separate from the rotating row 587, as shown in FIG. At the same time, the interlocking cam 77 comes into contact with and presses the other rotating roller 88, and the interlocking cam 77 stops rotating at this pressed position. As the convex portion 82 separates from the rotating roller 87, the rotating roller 87 is forcibly pulled by the groove 84, and the interlocking arm 75 rotates counterclockwise. It moves in the direction away from the body drum 7 and retreats. Also,
As the convex portion 82 presses the rotary row 588, the interlocking arm 76 rotates clockwise, and this movement is transmitted to the links 65, 67 via the drive shaft 68 and the lever 61°63, .67 moves to the side where the photosensitive drum 7 is placed.

Due to such movement of the links 65 and 67, the second developing device 11 moves to the side where the photosensitive drum 7 is disposed, and its shaft 36 and bin 46 come into contact with the leading edges of the guide holes 50 and 50, and the developing roller 33 approaches the photoreceptor drum 7. At this time, as in the case of the first developing device 10, the link 65.6
7 continues to move slightly even after the shaft 36 and bottle 46 of the second developing device 11 come into contact with the leading edge of the guide hole 50, 50, and this action causes the springs 73, 73 to be compressed. With an elastic force of 73.73, the shaft 36 of the second developing device 11 and the bottle 46 move into the guide hole 50.
．． 50, thereby ensuring the positioning of the second developing device 11, so that the developing roller 33 approaches the circumferential surface of the photoreceptor drum 7 with a predetermined width. opposite. Then, the electrostatic latent image on the photoreceptor drum 7 is developed by the magnetic brush B using the developer Db formed on the outer peripheral surface of the rotating sleeve 35, and is made into a visible image.

At this time, since the developing roller 33 of the first developing device 10 is retracted at a large distance from the photoreceptor drum 7, the developer [)a on this developing roller 33 may inadvertently adhere to the photoreceptor drum 7. Therefore, the second developing device 11
Accurate development can be carried out.

Furthermore, from this state, the user starts the first developing device 1 again.
When the selection switching operation for 0 is performed, as shown in FIG. 1. Both the second developing devices 10 and 11 are held in a position where they are retracted from the -H photoreceptor drum 7. In this state, the photosensitive drum 7 rotates clockwise by a certain angle. This is because the developer Db that has unnecessarily adhered to the photoreceptor drum 7 is removed from the first developing device 1.
This is to prevent the developer from being mixed into the developer [)a. That is, when the border roller 33 of the second developing device 11 is disposed close to the photoreceptor drum 7, the photoreceptor drum 7
In some cases, the developer Db may unnecessarily adhere to the portion a facing the developing roller 33. Therefore, if the second developer 11 is retracted by selecting the first developer 10 and the first developer 10 is brought close to the photoreceptor drum 7 in this state, the photoreceptor drum 7 will rotate and the aRA will increase. When the first developing device 10 moves to a position facing the river edge roller 33, the developer Db of the second developing device 11 may accidentally mix into the developer Da of the first developing device 10. Therefore, after retracting the second developing device 11, the photosensitive drum 7 is rotated at a certain angle.
In other words, the rotation is performed by an angle θ or more until the portion a passes the portion facing the first developing device 10. The developer Db that has attached to the photoreceptor drum 7 needlessly is removed by the cleaning device @14 during the above rotation or subsequent rotation of the photoreceptor drum 7.
removed by

In this way, after the second developing device 11 is retracted from the photoreceptor drum 7 and the photoreceptor drum 7 has rotated by a certain angle, the movement cam 77 further rotates, and the convex portion 82 moves to the area where the rotation roller 87 is arranged. , the rotating roller 87 is rotated by this convex portion 82.
is pressed, and in response, the first developing device 10 is opened in the same manner as described above.
The developing roller 33 faces the photoreceptor drum 7 closely,
Development is performed by the magnetic brush B of the developing roller 33.

Note that when the second developing device 11 is selected and switched from the driving state of the first developing device 10, the second developing device 11 follows the first developing device 1o in the rotational direction of the photosensitive drum 7. Since it is located on the side, even if the developer [)a of the first developing device 10 is unnecessarily attached to the photosensitive drum 7, there is no risk that this will mix into the developer Db of the second developing device 11. Therefore, it is not necessary to apply the above-mentioned rotation to the photosensitive drum 7.

FIG. 14 shows the main parts of the eleven subcircuits of the copying machine constructed as described above. That is, 101 is a main control unit that controls the entire printing press, and is mainly composed of a CPU (Central Processing Unit) 102, and includes at least a counter means 103 and a memory means 104.

The main control unit 101 receives signals from the switch 86, various operation switches on an operation panel (not shown), and signals from other input devices 1.5 such as various sensors. Further, the pulse motor 79 is connected to the main control unit 101 via a drive circuit 106, and other outputs such as the exposure lamp 24, a main motor (not shown), a solenoid, and various display lamps on the operation panel are connected to the main control unit 101. Device 107 is connected.

Next, the operation in such a configuration will be explained.

FIG. 15 is a timing chart showing when the power is turned on, when the switch 86 happens to be on.

First, the pulse motor 79 is turned on. When the switch 86 is turned off as the interlocking cam 77 rotates (point a), the main control [171ffl101] starts counting reference clock pulses by the counter means 103. And switch 8
6 turns on again (point b), the pulse motor 79 is turned off and the counter means 103 stops counting. In this way, the monarch system ilO section 101 starts from the second developing device 11 side to the first developing device 11 side.
The travel time T to the developing device 10 side can be known, and the measured travel time T is stored in the memory means 104.

FIG. 16 shows the timing chart 1- when the power is turned on, especially when the switch 86 happens to be off, and the moving time T
The measurement method is the same as in the above case.

Next, the selection switching operation of the developing device will be explained.

First, according to the timing chart shown in FIG.
Switching from the developing device 10 to the second developing device 11 will be explained. When the first developing device 10 is selected, the user can select the second developing device 11 by pressing a color changeover switch (developing device selection changeover switch) on the operation panel (not shown).
mode of use. At this time, when the color changeover switch is pressed again, the mode returns to the use mode of the first developing device 10, and by pressing the copy button here, the pulse motor 7
9, and proceed directly to the copying operation. Second
When the copy button is pressed in the use mode of the developing device 11, as shown in FIG. 17, the pulse motor 79 is first turned on,
At the point when the switch 86 is turned off (that is, when the switch is switched to the second developing device 11), the pulse motor 79 is turned off, the photosensitive drum 7 is rotated, and the copying operation is started.

Next, according to the timing chart shown in FIG.
Switching from the developing device 11 to the first imager 10 will be explained. When the second developer 11 is selected, the user presses the color changeover switch to select the first developer 11.
mode of use.

At this time, when the color changeover switch is pressed again, the mode returns to the use mode of the second developing device 11, and by pressing the copy button here, the copying operation is directly performed without turning on the pulse motor 79. When the copy button is pressed in the use mode of the first developing device 10, the pulse motor 79 is first turned on for a time T/2, as shown in FIG. This time T/2 is calculated from the travel time stored in the memory means 104. Here, the first and second current @
Both containers 10 and 11 are separated from the photoreceptor drum 7. Next, the photosensitive drum 7 is rotated for a predetermined period of time to clean the residual developer from the second developing device 11. Next, the pulse motor 79 is turned on again, and at the point where the switch 86 is turned on (that is, the point where it is switched to the first current f% unit 1Q), the pulse motor 79
is turned off, the photosensitive drum 7 is rotated, and the copying operation begins.

In this way, when the developer is selected using the color selection switch, the developer is not moved, but after the copy button is pressed and an instruction to start copying is input, the developer is moved and the selected developer is selected. (9 is placed close to the photoreceptor drum 7. Therefore, the developing device does not move every time the user selects a selection, eliminating unnecessary operations, minimizing the time when copying is not possible, and It is possible to extend the life of the moving mechanism of the container.

In the above embodiment, the case where there are two developing devices has been described, but the present invention is not limited to this, and can be similarly applied to a case where there are, for example, three or four developing devices.

[Effect of Explanation] As detailed above, according to the present invention, image formation is possible that eliminates unnecessary operations, minimizes the time during which image formation is not possible, and extends the life of the developing device transfer mechanism. equipment can be provided.

[Brief explanation of drawings]

The drawings are for explaining one embodiment of the present invention, and FIG. 1 is a vertical cross-sectional front view of a two-color copying rack, FIG. 2 is a cross-sectional view of the developing roller, and FIG. 3 is a vertical cross-sectional view of the developing roller. Figure 4 is a front view of the shaft support part of the magnet roller, Figure 5 is a perspective view of the shaft support part of the magnet roller, and Figure 6 is a front view of the shaft support part of the magnet roller.
The figure is an exploded perspective view of the VJ structure of the developing unit, FIG. 7 is a sectional view of the link support part, and FIG. 8 is a front view of the link support part.
FIG. 9 is a front view of the interlocking cam, FIG. 10 is a cross-sectional view of the interlocking cam, FIGS. 11, 12, and 13 are side views showing the moving states of the developing device in order, and FIG. 14 is a diagram of the control circuit. A configuration diagram showing the main parts, Figures 15 and 16 are timing charts explaining the operation when the power is turned on, and Figure 17 is a timing chart 1 explaining the switching operation from the first developer to the second developer.
-1 FIG. 18 is a timing chart illustrating the switching operation from the second developing device to the first developing device. 2... Document table, 7... Photosensitive drum (developed area), 9... Exposure optical system, 10...
...First developing device, 11... Second developing device, 77
......Interlocked cams, 7...Pulse motors, 86...Switches, 101...Main control section. Applicant's representative Patent attorney Takehiko Suzue Figure 8 Figure 9 Figure 10 v: ; yakuza
111 Figure 16

Claims (3)

[Claims] (1) It has a plurality of developing devices that are disposed opposite to the developing portion and are movable in directions toward and away from the developing portion, and by moving these developing devices, one developing device can be applied to the developing device. An image forming apparatus that forms an image by bringing the developing unit close to the developing unit and developing the area to be developed using the developing unit, wherein the developing unit is moved after an instruction to start the image forming operation is given. . (2) The image forming apparatus according to claim 1, wherein the development target portion is a photoreceptor on which an electrostatic latent image is formed. (3) The image forming apparatus according to claim 1, wherein the number of developing units is two.