JPH0385565A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the accumulation of toner and carrier to the surface of a transfer device the degradation of image quality the generation of jamming, and the shortening of service life of a fixing roll by providing splattering sources of the toner or the carrier such as a developing device, a toner replenishing device and an image carrier on the lower or the front direction of the transfer device, and constructing the developing device so as to be able to move in a transverse direction. CONSTITUTION:The developing unit 101 is carried by a mobile base 120 and the base is moved in the direction of tangent of the image carrier surface of developing action range toward the surface of the image carrier. The mobile base 120 is guided in the direction of movement by a guiding means 121. The developing unit 101 is positioned with specified spacing from the image carrier when the developing unit 101 is moved to a developing action position by the mobile base 120 by a positioning means 103. The mobile base 120 is held by holding means 122 and 123 when the developing unit 101 is positioned to the image carrier by the positioning means 103. Further, the mobile base 120 can be attached to/detached to/from the device main body by moving it along the guiding means 121. Thus, the accumulation of the toner and the carrier to the surface of the transfer device, the gradation of the image quality, the gradation of jamming, and the shortening of the life span of the fixing roll can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) The present invention relates to an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus.

FIG. 14 shows an image forming apparatus that is currently being commercialized and is expected to expand, such as a full-color electrophotographic copying machine.

This copying machine includes a transfer drum 5 that holds a transfer paper P by a gripper 5a on its circumferential surface, and above the transfer drum 5, a photosensitive drum 1, and a plurality of developing units 101Y, IOIM,
A rotary developing device 1 that stores and rotates 10IC11oIB
00, and each developing unit 10IY that stores toner.
, IOIM, and 101C1101B are disposed.

The photosensitive drum 1 and the rotary developing device 100 arranged above the transfer drum 5 are both sources of toner scattering, and the carrier (iron powder) in the two-component developer used is also scattered. Therefore, these scattered toners and carriers tend to accumulate on the surface of the transfer drum 5 located below.

The toner deposited on the surface of the transfer drum 5 causes stains on the back side of the transfer paper P, and also weakens the electrostatic attraction between the transfer sheet 5b wound around the transfer drum 5 and the transfer paper P. As a result, it causes various problems such as deterioration of image quality, occurrence of paper jams, and shortened lifespan of the fixing roller.

Therefore, large-scale equipment is required to collect and collect the toner and carrier accumulated on the surface of the transfer drum 5 and keep the surface of the transfer drum clean, and these equipment can become a source of noise and increase the cost of the equipment. This was hindering low prices.

Furthermore, since the rotary developing device is constructed by housing a plurality of developing units in a rotary body, the overall size of the copying machine cannot be avoided.

Therefore, an object of the present invention is to provide a developing device, a toner replenishing device,
By arranging a toner and carrier scattering source such as an image bearing member such as a photosensitive drum below or in front of the transfer device, and configuring the developing device to be movable laterally, toner and carrier scattering onto the surface of the transfer device can be carried out. It is an object of the present invention to provide an image forming apparatus that can prevent the accumulation of paper, reduce image quality, cause paper jams, and shorten the life of a fixing roller.

Another object of the present invention is to provide an image forming apparatus that allows the entire apparatus to be miniaturized, promotes a reduction in the cost of the apparatus, and minimizes noise.

The above-mentioned various quantities for achieving this can be achieved by the image forming apparatus according to the present invention. In summary, the present invention provides an image carrier on which a latent image is formed, and at least one image carrier disposed close to the surface of the image carrier to visualize the latent image on the image carrier. a movable base supporting the developing units and moving the movable base toward the surface of the image carrier in a direction substantially tangential to the surface of the image carrier in the development operation area; a guide means for guiding in a moving direction; a positioning means for positioning the developing unit at a predetermined gap with respect to the image carrier when the developing unit is moved to a developing operation position by the movable base; holding means for fixedly holding the movable base when the developing unit is positioned with respect to the image carrier by means, and the movable base moves along the guide means. The image forming apparatus is characterized in that it can be attached to and detached from the apparatus main body by moving it in a moving direction.

Oitoyo 1 Next, the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

FIG. 2 shows a full color electrophotographic copying machine which is an embodiment of the image forming apparatus according to the present invention.

An image carrier, that is, in this embodiment, a photosensitive drum 1 having an electrophotographic photosensitive layer on its surface is rotationally driven in the direction of arrow X. On the left side of the photosensitive drum 1, there is a primary charger 2 and a photosensitive drum 1.
A surface electrometer 3 for measuring the potential on the surface of the photosensitive drum 1 is located diagonally below the left side of the photosensitive drum 1, and a plurality of developing units are located directly below the photosensitive drum 1, that is, developing units 101M and 101C1 in this embodiment.
A developing device 100 is loaded with 101Y and 101B and moves in the left-right direction, and a transfer device 5 is installed diagonally above and to the right of the photosensitive drum 1.
, a pre-static eliminator 6 and a photosensitive drum 1 are installed approximately directly above the photosensitive drum 1 to reduce the adhesion force of toner remaining on the surface of the photosensitive drum 1 after transfer to the drum to facilitate cleaning.
A cleaning device 7 is disposed diagonally above and to the left of each.

Further, an optical system 10 is disposed in the upper part of the copying machine, and the original image on the platen 8 is transferred to the charger 2 and the surface electrometer 3.
The image is projected onto the photosensitive drum 1 at an exposure section 9 located between the two. Although any optical system can be used as the optical system 10, in this embodiment, the first scanning mirror 11, the first
second and third scanning mirrors 12 and 13 that move in the same direction at half the speed of the scanning mirror 11; an imaging lens 14;
And a CCD 15 integrated with B, G, and R filters, a laser scanner unit 16, and a fixed mirror 17.18
It consists of Here, the scanner unit 16 is a well-known device that deflects laser light using a rotating polygon mirror.
Detailed explanation will be omitted.

Further, in the optical system 10, the original illumination light source 20 is configured to move together with the first scanning mirror 11. Therefore, the reflected light image of the original scanned by the first to third scanning mirrors 11, 12, 13 passes through the lens 14, and then the BG
The CCD 15 equipped with an R4 color separation filter separates the colors and converts them into electrical signals, and this document information signal is sent to the A/D.
After undergoing information processing such as conversion, the video signal is converted into a microprocessor unit (hereinafter referred to as MP) that controls the entire copying machine.
U). Based on this signal, the MPU oscillates a laser beam from the laser unit via the laser driver,
This laser light is turned on to the photosensitive drum 1, /OF F L
start the copy sequence while

Furthermore, in this embodiment, a fixing device 20 is provided on the right side of the copying machine.
and a paper feeding device 30 are arranged, and transfer paper conveying systems 25 and 35 are arranged between the transfer drum 5, the fixing device 20, and the paper feeding device 30, respectively.

In the above configuration, the photosensitive drum 1 includes a primary charger 2, an optical system 10, a developing device 4, a transfer device 5, and a cleaning device for charging, exposing, developing, transferring, and cleaning processes for each color separated by the CCD 45. Performed by 7.

The developing device 100 includes a developing unit IOIM (magenta developing unit), a cyan developing unit 101Y (yellow developing unit), and a cyan developing unit 101Y (yellow developing unit), which are detachably held on a movable stage 120 (FIG. 1), as will be described in more detail later. 101B (black developing unit), and the color-separated latent images of each color are visualized by the corresponding developing units.

The transfer device 5 typically includes a transfer drum 5b equipped with a gripper 5a for gripping a transfer material, that is, a transfer paper P, on its circumferential surface. The transfer device 5 receives transfer paper P fed from a transfer paper cassette 31 or 32 of a paper feeding device 30 via a transfer paper conveyance system 35.
The tip of the photosensitive drum 1 is gripped by a gripper 5a and rotated to transfer a visible image of each color on the photosensitive drum 1. A transfer charger 5c is arranged inside the transfer drum 5 in the transfer area.

The transfer paper P on which the toner image of each color has been sequentially transferred is released from the gripper 5a and peeled off from the transfer drum 5b by the separation charger 8 and the separation claw 8'. Next, the transfer paper P is sent to the fixing device 20 by the transfer paper transport system 25. The toner image on the transfer paper P is fixed onto the transfer paper by the fixing device 20, and then the transfer paper is discharged onto the tray 23.

Next, the developing device 100 according to the present invention will be explained.

The developing device 100 is configured to be movable in the left-right direction as described above by means of a guide means to be described later, and the individual developing units are positioned directly below the photosensitive drum 1 and close to the photosensitive drum 1 with a predetermined gap therebetween. On the other hand, it is desirable that the developing unit be held directly below the photosensitive drum, that is, at a position retracted from the photosensitive drum 1 except when it is in the developing operation position.

This is because when each developing unit is moved close to the photosensitive drum 1, even when returning to its original position (home position) after development of all four colors is completed, each developing unit remains close to the photosensitive drum 1. 1, and as a result, all the toner standing on the developing sleeve in each developing unit comes into contact with the photosensitive drum, causing unnecessary toner to adhere to the photosensitive drum.

If unnecessary toner adheres to the photosensitive drum, all or all of the toner adhered to the photosensitive drum may be removed because there is no transfer paper between the photosensitive drum 1 and the transfer drum 5b during non-development. A part of it flies to the transfer drum 5b, resulting in contamination of the transfer drum 5b.

Further, near the developing operation position of the photosensitive drum 1, it is necessary to arrange a surface electrometer 3 and a partition plate to prevent foreign matter such as paper powder from falling from above onto the developing sleeve of each developing unit. . In order to maintain a predetermined distance between each of these members and the developing sleeve and to prevent them from coming close to each other, each developing unit must be located at a position retracted from the photosensitive drum 1 except during development.

In other words, the laterally moving developing device 100 configured in accordance with the present invention brings each developing unit close to the photosensitive drum 1 only during development (when it is directly below the drum), and retreats from the photosensitive drum 1 during other non-development times. It is configured so that it is located at the position shown in the figure.

Next, the developing device 100 will be described in more detail with reference to FIG. 1 and FIGS. 3 to 13.

In this embodiment, the developing unit 101 (101M,
l0IC, l0IY, 101 B) have the same configuration,
The only difference is the color of the developer supplied inside.

Referring to FIG. 4, the developing unit in this embodiment includes an elongated developing container 106 whose cross section is approximately rectangular.
A developing sleeve 102 having a built-in magnet (not shown) is rotatably supported in the developing container 106. A photosensitive drum 1 is mounted on both end shaft portions of the developing sleeve 102.
Abutment roller 103 for securing a predetermined gap between
is provided. Further, a driving gear 104 of the developing sleeve 102 is fixed to one shaft end of the developing sleeve 102.
The driving force of the motor 125 (FIG. 10) is transmitted to the developing sleeve 102 by a drive train described later.

Further, the magnet within the developing sleeve 102 is positioned at an appropriate position within the developing sleeve 102 by a positioning plate 190 disposed on the other end shaft portion of the developing sleeve.

A developing unit 101 is installed at both ends of the developing container 106.
Support shafts 105F and 105R for mounting and positioning on a moving base 120 (FIG. 1), which will be described later, are attached to the developing sleeve 10.
2 and coaxially parallel to each other.

Further, inside the developer container 106, there is a screw 107.1 (only the shaft part is shown) that stirs and transports the developer contained therein.
08, and the screws 107 and 108 are driven by a drive gear 104 of the developing sleeve 102 via a gear train (not shown). The end of one of the screws, the screw 107 in this embodiment, protrudes toward the front from the developer container 106 and passes through a conveying vibrator 106a that is connected to a toner replenishing device to be described later. Transport vibe 10
A replenishing port 106a' for connecting to the toner replenishing device 200 is opened in the upper part of the toner replenishing device 6a.

That is, as can be understood from FIG. 5, the toner replenishing device 20
Supply port 24 of shutter 241 of supply pipe 202 of 0
1a. Therefore, when the developing unit 101 moves, the replenishing port 241 follows the lateral movement of the developing unit 101.
a is guided to the replenishment port 106a' of the developing unit, and the replenishment pipe 202 swings to enable constant replenishment of toner.

An embodiment of such a toner supply bag device 200 is shown in FIG.

FIG. 6 is a perspective view showing a simplified overall view of the toner replenishing device 200 with detailed parts omitted. The toner replenishing device 200 develops each color of magenta, cyan, and yellow black.
Containers 201M, 201C, 201Y, 20 for storing the agent
1B, and a developing unit IOIM, 101 from each container.
A supply pipe 202M-B containing a built-in screw for supplying toner to the C1IOIY and 101B is swingably connected to the toner container 201M-B. As described above, the replenishment port 241a of the shutter 241 of the replenishment pipe 202 is located in a part of the developing unit, that is, the replenishment port 106.
a to supply toner to the developer container 106.

The toner container, the replenishment pipe, and other components of the toner replenishing device 200 are attached to the replenishment support plate 203 . Further, the supply support plate 203 is rotatably supported by support shafts 205a and 205b with respect to a support stand 204 fixedly provided on the front side plate 73 (FIG. 1) of the copying machine. During the copying operation, the supply support plate 203 is rotated toward the front plate, and the end opposite to the rotational fulcrum is fixed to the front plate with screws or the like and set.

Returning to the developing device 100 again, the bottom of the developing container 106 is provided with a guide leg 106b.

106c (see FIGS. 4 and 11) is formed to slidably engage with a slide guide 121 attached to a movable base 120, which will be described later.

FIG. 1 is a perspective view of the entire developing device 100 seen from diagonally above and to the left in front of the copying machine. In this figure, each developing unit 101 is omitted.

The developing device 100 has a movable base 120 on which each developing unit 101 is loaded and moved, and the base 120 has a slide guide 121 (121M) that engages and holds the guide legs 106b and 106c of each developing unit 101. , 12
1C1121Y, 121B) are attached with stepped screws (not shown) so as to be slidable in the six directions of the arrows.

Further, the base 120 is provided with a back support plate 122 and a front support plate 123 corresponding to each slide guide 121.

The back support plate 122 is the rotation support shaft 105 of the developing unit 101.
The front support plate 123 has a hole 122' that fits with the rotation support shaft 105F of the developing unit 101.
'have. The front support plate 123 supports the developing unit 10
1 along the slide guide 121, and rotate the pivot shaft 1.
After fitting 05R into the hole 122' of the back support plate 122,
The rotation support shaft 105F and the hole 123' of the front support plate 123 are fitted, and then screwed to the base 120.

Here, the back support plate 1 provided for each developing unit of each color.
22 and the hole 122123' of the front support plate 123 are adjusted using a jig or the like during assembly so that they share the same axis parallel to the axis of the photosensitive drum 1.

In this embodiment, the back support plate 122 is screwed to a drive board 124 that supports a drive gear, a clutch, etc., which will be described later, and the drive board 124 is screwed to the base 120. Further, a support plate 126 for supporting a DC motor 125 is fixed to the base 120 with screws.

The movable base 120 is guided in the moving direction by a guide means. As can be understood by referring also to FIG. 3, the guide means includes a rail 127 at the rear end of the base 120, and the rail 127 is attached to the rear side plate 50 fixed to the bottom plate 60 of the copying machine. The rail abutment 128 is slidably engaged with the rail support 128 . On the other hand, a roller 1 with a built-in ring is attached to the front end of the base 120 via a support plate 130.
29 is rotatably supported. The roller 129 is the bottom plate 6
It is possible to roll on 0.

With this configuration, the movable base 120 is movable with respect to the bottom plate 60 and the rear side plate 50.

The movable base 120 is driven by the driving force of a stepping motor 132 mounted on the bottom plate 60 by suitable support means (not shown) and gears 133 and 134 also mounted on the same support means. .135 to a rack 131 fixed to the base 120.

According to the present invention, the developing device 100 is moved toward the photosensitive drum 1 on the base 120 in a direction substantially tangential to the photosensitive drum, and is positioned relative to the photosensitive drum at the developing operating position, that is, at a position approximately directly below the photosensitive drum. It is positioned with a predetermined gap.

FIG. 7 is a perspective view showing a developing unit lifting mechanism for positioning each developing unit 101 by lifting it toward the photosensitive drum 1 at the developing operating position. In this figure, in order to make the internal parts arrangement easier to understand, the movable base 120 and the slide guide 121M for the developing unit 101M are shown by two-dot chain lines, and the slide guides 121C and 121Y for the other developing units are shown.

121B is omitted.

There are short rack teeth 14 on the back side of the slide guide 121M.
Similarly, the rack teeth 140 are fixed to the slide guides 121C, 121Y, 1 of each developing unit.
21B is also provided. Furthermore, long rack teeth 141 are fixed to the back side of the base 120.

On the other hand, a rotating shaft 142 rotatably supported by a support plate 143 is provided on the bottom plate 60 . A clutch gear 144 is attached to the rotating shaft 142 at a position that engages with the rack 141 on the back side of the base 120, and when a voltage is applied to the clutch gear 144, the rotation of the gear is transmitted to the shaft 142. ing.

Further, a gear 145 is provided on the rotating shaft 142 at a position that engages with the rack 140M on the back surface of the slide guide 121. Here, the number of teeth Z144 of the clutch gear 144 is set smaller than the number of teeth 214 of the gear 145. The reason for this will be explained in detail later.

Adjacent to the gear 145, a ring 1 is attached to the rotating shaft 142.
46 is fixed, and a coil spring 147 is inserted between the gear 145 and the ring 146. The coil spring 147
One end of the ring 146 is hooked into a groove (not shown) provided in the ring 146, and the other end is hooked into a hole 145a made in the side surface of the gear 145, as shown in FIG. The gear 145 has a fan-shaped parallel bottle groove 145b, and the gear 145 is biased in the direction of the arrow by the coil spring 147, so that one end of the fan-shaped groove abuts against the parallel bottle.

Next, the drive train from the DC motor 125 to the developing sleeve 102 will be explained with reference to FIGS. 9 and 10. 9 is a view of the drive train viewed from the direction of arrow D in FIG. 1, that is, the front direction of the rack 131, and FIG. 10 is a plan view thereof.

The output of the DC motor 125 is transmitted to its output gear 150 and an idler gear 152 provided on the drive board 124, and furthermore, the output of the DC motor 125 is transmitted to the output gear 150 and the idler gear 152 provided on the drive board 124 and the support board 155.
54 is rotatably supported, and is transmitted to a clutch gear 153M that transmits drive to the developing sleeve 102 at 0N10FF. Further, the driving force from the clutch gear 153M is transmitted to the drive board 1 via its rotating shaft 154 and output gear 158.
The signal is transmitted to a gear 157 attached to 24.

On the other hand, as can be better understood by referring also to FIGS. 1 and 4, for example, the magenta developing unit I
When the OIM is inserted along the slide guide 121M,
The rotating support plate 105R on the back side of the developer container 106 is the back support plate 1.
By fitting into the hole 122' of No. 22, the gear 157 and the drive gear 104 of the developing sleeve 102 mesh with each other, as shown in FIG.

Each of the other developing units 10IC and 10IY.

Clutch gear 153G for 101B as well as above
, 153Y, and 153B, each drive train is connected by a relay gear 159 provided on the drive board 124, and the driving force is transmitted from the DC motor 125.

Further, when each developing unit 101 is inserted into the slide guide 121, a contact portion (not shown) provided on the base 120 for applying a high voltage to the developing sleeve 102 is also connected to the developing unit 101. The developing sleeve 10 is electrically connected to the provided contact portion (not shown) during development.
2, but since such a configuration is well known to those skilled in the art, further detailed explanation will be omitted.

With the above configuration, when the main body of the copying machine is turned on, whether or not the base 120 is at the home position can be determined by the light emitting element and light receiving element fixed to the bottom plate 60, as shown in FIG. When the base 120 is not at the home position, the stepping motor 132 rotates and the light from the sensor 181 is detected by the light shielding plate 80 which is adjustable on the base 120.
The base 120 is moved until it is blocked by the base 80, that is, until it reaches the home position.

To explain further, referring to FIGS. 11 and 12,
At the home position, the magenta developing unit 101M is located directly below the photosensitive drum 1, and g (I2
．． indicates the position of the rotational support shaft 105F when the developing sleeve 102 is directly below the photosensitive drum l to the position of the rotational support shaft 105F at the home position, which is at a distance equal to the interval between each development unit. The position is set by adjusting the light shielding plate 180.

Next, when the copy button is operated to start the copying operation, the microprocessor unit (MPU) that controls the operation of the copying machine body sends the pulse generator of the stepping motor 132 that drives the base 120 to the developing unit of the magenta developing unit. A signal is sent to move the base 120 at a predetermined speed until the sleeve 102 is directly below the photosensitive drum 1.

As the base 120 moves, the magenta developing unit 10
1M is lifted upward and approaches the photosensitive drum 1.

This lifting operation will be explained in detail next.

In FIG. 7, at the home position of the base 120, the rack 141 and the clutch gear 144 are in an engaged state. Further, since the clutch of the clutch gear 144 is turned ON immediately before the base 120 starts moving, the rotating shaft 142 and the gear 145 rotate as the base moves. Then, while the base 120 is moving, the rack 140 fixed to the bottom of the slide guide 121 is rotated by the gear 145.
Engage with each other.

The number of teeth 2144 of the clutch gear 144 is as described above.
Number of teeth of gear 145: 214. For example, the point where the rack 140 starts to engage the gear 145 is n+(I!
, +<β, the state shown in FIG.
Flood, only rotate. Converting this to the rotation angle of the rotating shaft 142, a==42+ / r +44 (r a
d) (r+44 is the pitch circle radius of clutch gear 144)
becomes.

Therefore, the rotational length of the gear 145 on the pitch circumference, that is, the moving distance i of the slide guide 121M integrated with the rack 140 that meshes with the gear 145! , 2 is At=αXr+4g =β+X (r 148 / r+44)(r+4s
is the pitch circle radius of the gear 145).

Here, Z 145 > Z 144 %, that is, r 1
Since 48 > r +44, Shinobi 2>β1.

That is, while the base 120 moves by 1, the slide guide 121M slides relative to the base 120 by a distance of (2-β1). This slide guide 121M is connected to the base 120 (Q2-
g+), the slide guide 121M moves to the fulcrum 1 on the base 120, as shown in FIG.
The foot 106b of the developer 22) 101M, which can be rotated about 05F1105R as a rotational fulcrum, is pushed in the direction of arrow A.

As a result, the magenta developing unit 101M
0 is lifted in the direction of arrow B and comes to rest at a position directly below the photosensitive drum 1 and close to the photosensitive drum 1 via the abutment rollers 103.

During this lifting, the feet 106C of the developer container 106 move away from the slide guide 121M as shown in the figure, so as shown in FIG. Notch 121M'
etc. are formed.

Also, since the abutting roller 103 needs to be pressed against the photosensitive drum 1 with a predetermined force, if d is the distance between the abutting roller 103 and the surface of the photosensitive drum at the home position, then
The lifting amount of the developing unit 101M in the B direction is d+α
(α: positive number). Therefore, in order to achieve such a lifting amount, the number of teeth of the gears 145 and 144 is appropriately determined from the relationship with the moving distance.

On the other hand, when the developing unit IOIM is close to the photosensitive drum 1 via the abutment roller 103 directly below the photosensitive drum 1, it receives a reaction force from the photosensitive drum 1 corresponding to the distance α, and the developing unit's own weight is In addition to this, it will be pushed back. This force causes the developing unit IOIM to rotate clockwise around its pivot points 105F and 105R, so the slide guide 121M is now pushed to the left (in the opposite direction of arrow A) by the feet 106b of the developer container. As a result, the rack 140M engaged with the slide guide 121M tries to rotate the gear 145 counterclockwise. The gear 145 is connected to the coil spring 14 as described above.
Although the photosensitive drum l is biased in the direction of the arrow by
The reaction force from and the movement of the developing unit balance the biasing force of the coil spring, causing the gear 145 to rotate between the fan-shaped parallel bin grooves 145b while the coil spring is deflected.

At this time, the coil spring 147 receives a reaction force from the photosensitive drum 1,
In other words, the abutment member 71 of the abutment roller 103.
The wire diameter and the number of turns are appropriately determined so that the pressing force against the wire 72 (described later with reference to FIG. 13) becomes a desired value. Further, the rotation shaft 142 is connected to the stepping motor 1 via a clutch gear 143, a rack 141, and a rack 131.
32, and the self-holding force of this stepping motor 132 acts on the rotating shaft 142, so accurate movement of the base is achieved without being affected by the rotation of the gear 145 mentioned above. .

As described above, when the developing unit IOIM is lifted up, the abutting roller 103 comes into pressure contact with the abutting members 71 and 72 corresponding to the surface of the photosensitive drum 1 with a predetermined force, as shown in FIG. The sleeve 102 comes close to the photosensitive drum 1 with a required gap.

Here, FIG. 13 is a simplified cross-sectional view of the main body of the copying machine, in which the abutment member 72 is fixed to the rear side plate 50 of the main body, and the abutment member 71 is detachably attached to the front side plate 73. It is fixedly provided to the centering member 70 of the photosensitive drum 1 . From this state, the clutch gear 15 shown in FIG.
Since 3M turns on at a predetermined timing, developing sleeve 1
02 is driven by a DC motor 125 via the drive system shown in the figure, and visualizes the latent image on the photosensitive drum 1.

Further, as explained in FIG. 8, the developing unit 101M
Even if it rotates around its pivot points 105F and 105R and lifts up, the gear 157 that transmits drive to the sleeve gear 104 is coaxial with the pivot points 105F and 105R, so even during the lifting operation, there is no interference from the motor. It is ready to be driven. Therefore, this embodiment has the advantage that the timing for rotationally driving the developing sleeve 102 can be freely set regardless of the lifting operation position.

When the magenta developing process is completed as described above, the clutch gear 144 (Fig. 7) and the clutch gear 153M (first
(Figure 0) is turned off. As a result, the rotating shaft 142 becomes free to rotate, and the gear 146 integrated therewith also becomes free to rotate. Therefore, the reaction force from the photosensitive drum 1 and the weight of the developing unit 101M cause the slide guide 121 to move into the developing container. 106, the developing unit IOIM returns to the lowered position shown in the left diagram of FIG. 11 and separates from the photosensitive drum 1.

Next, the stepping motor 132 rotates by a predetermined amount, the clutch gear 144 is turned on, and the cyan developing unit 101C is lifted directly below the photosensitive drum. Further, the clutch gear 153C (FIG. 9) is turned ON to rotate the cyan developing sleeve 102C to perform cyan development.

Thereafter, when the development of yellow and black colors and the overlapping transfer of each color image onto a sheet of transfer paper are completed in the same manner, the transfer paper is separated from the transfer drum 5 by the separation charger 8 and the separation claw 8'. The image is fixed by the fixing device 20 and then delivered to the paper output tray 2.
3, and the copying operation ends.

Furthermore, the image forming apparatus according to the present invention has a characteristic configuration as described below.

That is, as can be understood by referring to FIG. 1, an opening 508' is provided in the rear plate 50 so as not to inhibit movement of the movable base 120 of the developing device 100 in the direction of arrow E. Furthermore, the rail 127 is configured such that its inner member and outer member can be separated from each other in the direction of arrow E. When assembling them, either one of the inner member and outer member is first attached to the rear side plate. It is screwed to the rail abutment 128 that is attached. Further, the other member is similarly screwed to the movable base 120.

Here, to explain the configuration of the front side plate 73 of the apparatus main body, the movable base 120 is located inside the front side plate 73, and therefore, the front side plate does not respond to the movement of the movable base 120 in the direction of arrow E. However, since the toner replenishing vibrator 106a of the developing unit 101 loaded on the movable base 120 protrudes from the base 120, the front lower plate also has an open lower part 3a correspondingly. is provided.

Since the developing device 100 is configured as described above, when assembling the movable base 120 to the device main body, or when removing the movable base 120 from the device main body for maintenance etc., the movable base 120 can be easily attached to and detached from the main body of the apparatus by attaching and detaching each member of the outer member and inner member of the rail 127 in the direction of arrow E.

Furthermore, since the movable base 120 is removably attached to the main body of the apparatus, a lifting mechanism is provided directly below the movable base 120 and lifts each developing unit 101 toward the surface of the photosensitive drum. Another advantage is that maintenance is extremely easy.

On the other hand, according to the above configuration, as described above, the rail 127
The outer member and the inner member are configured to be able to separate from each other in the direction of arrow E, but in this case, so-called ball creep (ball creep) of the ball rollers interposed between the outer member and the inner member during the copying operation. The difference between the amount of slippage and amount of rolling) is not corrected,
For this reason, it is conceivable that as the copy operation time increases, the amount of ball creep increases, and the load when moving the moving base 120 increases accordingly. However, this is a problem that can be easily solved by taking into account the driving torque of the stepping motor 132, and does not become an obstacle to realizing the present invention.

Further, special consideration must be given to the problem that the strength of the main body of the apparatus is reduced due to the widening of the opening 50a' of the rear side plate 50, but this problem can also be solved by adding a stay or the like as appropriate.

As explained above, according to the present invention, there is less scattering of toner carrier than in conventional full-color electrophotographic copying machines, so it is possible to eliminate various harmful effects caused by scattering of toner carriers seen in conventional devices, and Furthermore, it has become possible to commercialize a small, inexpensive full-color copying machine, which will greatly benefit users.

Furthermore, the developing device does not consist of multiple developing units as rotary bodies as in the past, but instead moves horizontally in the left-right direction. The behavior of the developer is stabilized, and as a result, the mixing ratio of toner and carrier (T/C ratio) can be controlled more accurately than before. Therefore, it is possible to always obtain stable image quality, which is of great benefit to the user.

Furthermore, when the movable base 120 returns to the home position, if the clutch of the clutch gear 144 is turned OFF, the developing unit will not be lifted toward the photosensitive drum 1, so unnecessary toner will be removed when the movable base 120 returns to the home position. This method is also excellent in that it prevents particles from scattering from the developing sleeve onto the photosensitive drum.

Although the above embodiments have been explained using a full-color electrophotographic copying machine as an example, it goes without saying that the present invention can also be applied to a monochrome copying machine equipped with one or more developing units.

Further, in this embodiment, a rack and a pinion gear are used to lift the developing unit toward the photosensitive drum, but the lifting mechanism is not limited to this. The developing unit may be lifted toward the photosensitive drum by this cam.

Furthermore, in this embodiment, the abutting roller 10 of the developing unit
3 was configured to abut against a member corresponding to the drum surface provided firmly on the main body to secure a gap between the drum and the developing sleeve, but the abutment roller was configured to directly abut against the photosensitive drum. It goes without saying that it is okay to do so.

Further, in this embodiment, the holding force of the stepping motor is used to maintain the developing unit positioned relative to the photosensitive drum, that is, in the lifted state. In order to
An arm rotatably fixed to the main body can also be engaged with the movable base at a predetermined timing by a drive source such as a solenoid.

As described above, the image forming apparatus according to the present invention is configured to move toner and carrier scattering sources such as a developing device, a toner replenishing device, and an image bearing member such as a photosensitive drum below or in front of a transfer device. In addition, by configuring the developing device to be movable laterally, it prevents toner and carrier from accumulating on the surface of the transfer device, reducing image quality, jamming, and even fixing. It has the advantage of being able to solve problems such as reduced roller life.

Further, according to the present invention, a plurality of developing units for each color can be quickly moved and replaced, and the developing unit can be positioned relative to the image carrier using an extremely simple developing unit lifting mechanism with a small number of parts. For example, a single motor (stepping motor) can move the development unit transport base and lift the development unit, making it compact, inexpensive, and capable of minimizing noise. An image forming apparatus with high operational reliability can be provided.

Furthermore, according to the image forming apparatus of the present invention, since the developing device is configured to move from side to side instead of the rotary body as in the conventional example, it is possible to downsize the entire device, and unlike the rotary developing device, Since the developer container does not turn upside down due to the rotation of the rotating body, the behavior of the developer in the developer container is stable, and as a result, the mixture ratio of toner and carrier (
It is also possible to control the T/C ratio more accurately than before, and stable image quality can be obtained.

Furthermore, it can be said that the developing device configured according to the present invention has a structure that is more excellent in terms of toner and carrier scattering from each developing unit than a rotating body.

Further, in the image forming apparatus of the present invention, the rail of the movable base is configured to be separable into an outer member and an inner member, and the opening of the rear side plate is widened so that the movable base is arranged so that the paper feeding and conveying device can be arranged. Since it is constructed so that it can be attached and detached in the opposite direction, the movable base can be more easily assembled and maintained than an image forming apparatus using a conventional rotary developing device. .

[Brief explanation of drawings]

FIG. 1 is a perspective view of a developing device constructed according to the present invention, with each developing unit omitted. FIG. 2 is a sectional view of a color electrophotographic copying machine showing an embodiment of the image forming apparatus according to the present invention. FIG. 3 is a front view seen from the direction of arrow B in FIG. 1. FIG. 4 is a perspective view of the developing unit. FIG. 5 is a perspective view showing the connection structure between the developing unit and the toner replenishing device. FIG. 6 is a perspective view of the toner supply device. FIG. 7 is a perspective view of a developing unit lifting mechanism of the developing device. FIG. 8 is a front view showing the driving means of the developing unit lifting mechanism. FIG. 9 is a front view showing the drive system of the developing sleeve.
It is a view seen from the direction of the arrow in the figure. FIG. 10 is a plan view of the drive system of the developing sleeve. 11 and 12 are schematic front views of the developing device, illustrating the operation of the developing unit lifting mechanism. FIG. 13 is a schematic cross-sectional view showing the positional relationship between the photosensitive drum and the developing sleeve. FIG. 14 is a sectional view of a conventional electrophotographic copying machine. 1: Image carrier 5: Transfer device 50: Rear side plate 73: Front side plate 100: Developing device 101: Developing unit 102: Developing sleeve 120: Moving base 121 Ni Ride guide 125: Developing sleeve drive motor Fig. 3 06a 10 Figure 11

Claims (1)

[Claims] 1) An image carrier on which a latent image is formed, and at least one developing unit installed close to the surface of the image carrier to visualize the latent image on the image carrier. a movable base that carries the developing unit and moves it toward the surface of the image carrier in a direction substantially tangential to the surface of the image carrier in the development operation area; and a movable base that guides the movable base in the direction of movement. a guide means, a positioning means for positioning the developing unit at a predetermined gap with respect to the image carrier when the developing unit is moved to the developing operation position by the moving base; holding means for fixedly holding the movable base when positioned with respect to the image carrier, and the movable base is moved in the moving direction along the guide means. An image forming apparatus characterized in that the image forming apparatus is detachably attached to an apparatus main body.