JPH09106186A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the height of a development part and to securely replenish a developing device with toner without any irregularity by mixing new toner with used toner. SOLUTION: A toner hopper 336 as a toner storage part is arranged above a toner mixing part 331a provided outside the unit case 331 of the developing device. Then the new toner from the toner hopper 336 is supplied to the position where the used toner carried out of the unit case 331 by a paddle wheel (1st conveyance member) 332 is delivered to a mixing roller (2nd conveyance member) 333 in the toner mixing part 331, and the used toner and new toner are mixed and carried in the unit case 331 again by the mixing roller 333.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine, and more particularly to an image forming apparatus having a developing device and a toner containing portion for containing toner to be supplied to the developing device. Regarding the device.

[0002]

2. Description of the Related Art Generally, an image forming apparatus such as an electrophotographic copying apparatus or a laser printer is provided with a developing device which develops an electrostatic latent image formed on a photosensitive member by adhering toner of a developer onto the electrostatic latent image. For example, a toner hopper or a toner cartridge is provided above the developing device as a toner containing part, and the toner is sequentially dropped from the toner containing part to the developing device to be replenished.

Further, in an image forming apparatus for performing two-color copying such as black and red, a black developing device and a black toner accommodating portion for performing black developing, and a color developing device and color for performing color developing. And a toner storage portion. In the conventional image forming apparatus for performing such two-color copying, the same developing device and toner storing section are used, and the color of the toner stored in the toner storing section is only changed at the end. Even if the shapes and structures of the two sets of the developing device and the toner containing portion are slightly changed, it is common to provide a toner containing portion such as a toner hopper above the developing device.

Therefore, there is a disadvantage in that the space in the height direction occupied by the developing unit in the image forming apparatus becomes large, resulting in an increase in size of the image forming apparatus. Therefore, there is also one in which a toner storage portion such as a toner hopper or a toner cartridge is provided near the outer portion of the developing device, and from there, the toner is transported into the developing device by a transporting means such as a screw to replenish the toner. By doing so, the height of the developing unit can be reduced to reduce the required space, and the image forming apparatus can be downsized.

[0005]

However, when the toner is replenished into the developing device from the outer portion of the developing device, the replenishment becomes more unreliable than the replenishment from the upper portion, and the developing device is replenished. The used toner remaining in the toner (mixed with the carrier in the case of a two-component developer) and the new toner replenished from the toner storage section are not sufficiently mixed and are likely to become non-uniform, As a result, uneven density may occur in the developed image.

The present invention has been made in order to solve such a problem, and lowers the height of the developing unit in the image forming apparatus to reduce the required space, and further, the toner in the developing apparatus is reduced. It is an object of the present invention to reliably replenish the toner, and to ensure that the used toner and the new toner are mixed and uniformly replenished.

[0007]

To achieve the above object, in an image forming apparatus having a developing device and a toner containing part for containing toner to be supplied to the developing device, the toner containing part is developed. A first conveying member which is provided near the outer portion of the apparatus and carries out used toner from the developing device to the outer portion of the developing device, and a second conveying member which carries in toner from the outer portion of the developing device into the developing device. And a member configured to supply the toner in the toner containing portion to a position where the first carrying member and the second carrying member transfer the toner outside the developing device. It is preferable that the position where the toner is delivered is inside the mixing unit that mixes the used toner carried out by the second transport member and the new toner supplied from the toner storage unit.

With this arrangement, since the toner storage portion is located outside the developing device, the height of the developing portion can be reduced to reduce the required space, and the image forming apparatus can be miniaturized. It will be possible. Moreover, the first transport member and the second
By supplying the toner in the toner container to the position where the conveying member transfers the toner on the outside of the developing device, the new toner can be securely stored together with the used charged toner or mixed toner with the carrier. Since the used toner and new toner are mixed and replenished evenly in the developing device, uneven density in the developed image does not occur.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a specific description will be given based on an embodiment of the present invention. FIG. 1 is an external configuration diagram showing an example of a copying apparatus as an image forming apparatus embodying the present invention.

This copying apparatus includes a copying apparatus main body 1 for executing an image forming process, and an inversion feeding type automatic document feeder (ADF) 2 for automatically feeding an original placed on the upper surface of the copying apparatus main body 1. A sorter 3 for sorting or collating the sheets discharged from the copying apparatus main body 1, a sheet feeding / composing / duplexing unit 4 for re-feeding and reversing the transfer sheets for performing synthetic copying and duplex copying, and a copying apparatus. A manual feed tray 5 and a paper feed cassette 6 for feeding paper to the main body 1 from the outside are provided.

A main operation panel 7 provided with various keys and a display for operating the copying apparatus is provided on the front side of the upper surface of the copying apparatus main body 1, and a copying machine is always provided on the upper front by a hidden door system. A sub operation panel 8 housed in the main body 1 is provided. Further, on the lower part of the front surface of the copying apparatus main body 1, two stages of upper sheet feeding cassette 9 and lower sheet feeding cassette 10 for feeding sheets from inside the copying apparatus main body 1 are mounted.

As shown in FIG. 2, the sub operation panel 8 is rotatably supported on the upper front surface of the front frame 85 of the main body, and is rotatably biased to the front side by a spring (not shown). A latch 87 is provided which is attached to the top and locks the support plate 86. The sub operation panel 8 is normally held by the latch 87 in the state shown by the solid line and hidden inside the main body of the copying apparatus.
Is pushed from the outside to the inside, the latch 87 is unlocked, and is rotated by the urging force of a spring (not shown) to the position shown in the phantom line for use. Then, by closing the support plate 86 again after use, the support plate 86 is locked by the latch 87.

FIG. 3 is an overall schematic diagram showing a mechanical portion of the copying apparatus main body 1. In the copying apparatus main body 1, when the start key provided on the main operation panel 7 is pressed, the main motor 100 is rotated and the photoconductor drum 101 is rotated.
Rotates in the direction of arrow P, and a high voltage is applied to the charging charge 102 provided with the charge voltage adjusting grid electrode 102a to uniformly charge the surface of the photosensitive drum 101. On the other hand, a moving optical system (scanner) including an exposure lamp 105 and a first mirror 106 attached to a later-described first scanner, and a second mirror 107 and a third mirror 108 attached to a second scanner drives a scanner to be described later. Driven by the mechanism.

A document S is set on the contact glass 115 by the automatic document feeder 2 or manually. The automatic document feeder 2 calls the document placed on the document table 2A with a call roller 2B,
The separation roller 2C and the pull-out roller 2D separate the sheets one by one and feed them via the guide 2E to the lower side of the conveyor belt 2F which rotates in the arrow direction, and the original S is placed on the contact glass 115 at a predetermined position by the conveyor belt 2F. Transport to and set.

The moving optical system turns on the exposure lamp 105 at a predetermined timing and irradiates the document S set on the contact glass 115, while moving forward in the direction of the arrow Q to the position shown by the imaginary line. Move back in the direction indicated by R. At this time, the reflected light from the document S irradiated by the exposure lamp 105 is the first mirror 106, the second mirror 107, the third mirror 108, the through lens 109, the fourth mirror 110, the fifth mirror 111, and the sixth mirror 112. In addition, it is incident on the charged photosensitive drum 101 through the dustproof glass 113 to be exposed, and an electrostatic latent image corresponding to the image of the original is formed on the photosensitive drum 101.

Then, the charge of the non-transfer area of the charged area on the photosensitive drum 101 becomes a light emitting diode (LE).
After being erased by the erase lamp 116 composed of D), the electrostatic latent image on the photosensitive drum 101 is developed by the developing sleeve 120 of the color developing device 118 or the black developing device 11.
Color toner or black toner is attached by the developing sleeve 121 of No. 9 and visualized.

On the other hand, the upper paper cassette 9 mounted inside
The transfer paper stored in the lower sheet feeding cassette 10 is fed through the feed roller 124 and the intermediate roller 125, and the transfer paper stored in the lower sheet feeding cassette 10 is fed through the feed roller 124 and the relay roller 126.
The transfer sheet fed from the manual feed tray 5 shown in FIG. 1 via the intermediate roller 125 and the intermediate roller 125, the transfer sheet stored in the sheet feeding cassette 6 via the feed roller 127 and the intermediate roller 125 is not shown. Depending on the selection result of the paper selection key provided on the main operation panel 7 from the paper path through the intermediate roller 125, any one of these transfer papers is fed to a position where it is sandwiched between the registration rollers 130. There is.

Then, the transfer sheet fed to the registration roller 130 is rotated at an accurate timing by the rotation of the registration roller 130, so that the photosensitive drum 10 is rotated.
1 and the toner image on the photosensitive drum 101 is transferred. At this time, the transfer charger 131 is applied with a high DC voltage at an accurate timing so that the photosensitive drum 101
The upper toner image is attracted toward the transfer paper. Thereafter, an AC high voltage is applied to the separation charge 132 to remove static electricity on the transfer paper, and the transfer paper is separated by the separation claw 133.
1 from above.

After the transfer and separation of the photosensitive drum 101 is completed in this manner, the cleaning blade 135 removes the residual toner, and the static elimination lamp 136 formed of an LED is used.
The residual electric charge is erased by the preparation for the next copying step. The residual toner stripped off the photosensitive drum 101 by the cleaning blade 135 is collected in the toner collecting tank 138 by the toner collecting shaft 137.

On the other hand, the transfer sheet separated from the photosensitive drum 101 is fixed by the fixing device 142 by the conveyor belt 141.
And the heater roller 1
The toner image is thermally roll-fixed by 43 and the pressure roller 144, and then discharged by the fixing paper discharge rollers 145, 146. Then, the transfer sheet discharged from the fixing device 142 is discharged into the sorter 3 via the space between the discharge rollers 149 and 149 when the discharge switching member 148 is located on the discharge side.

When the paper discharge switching member 148 is located on the composite / double-sided side (state shown in the figure), it is sent between the rollers 151 and 152 through the guide 150. Then, in the case of one-sheet composite copy, it is guided by the direction switching member 153 in the state shown by the solid line and is sent to the inside of the composite / double-sided conveyance unit 156 through between the rollers 151 and 154. After the posture is corrected in accordance with the
Paper is fed to 0.

Further, during the continuous composite copy or the continuous double-sided copy, the direction switching member 15 in the state shown by the phantom lines is shown.
Guided by 3 and sent into the composite / double-sided unit 4,
When merging, the currently copied surface becomes the next copy surface as it is, and at the time of double-sided copying, the surface opposite to the currently copied surface becomes the next copy surface. Sent into 1,
It is sent to the inside of the composite / double-sided conveyance unit 156 via the rollers 151 and 154, and after the posture is corrected, it is fed again to the registration rollers 130 at a predetermined timing. Then, after the next image on the photosensitive drum 101 is transferred,
In the same manner as described above, after fixing, the sheet is discharged or is fed into the composite / double-sided conveying unit 156 or is fed into the composite / double-sided unit 4.

4 and 5 are a front sectional view and a plan view showing the drum unit and the cleaning unit of the copying apparatus main body 1, respectively. First, the configuration of the drum unit will be described. The drum unit case 251 is a cylindrical casing formed by forming an upper attachment / detachment guide 251a, a lower attachment / detachment guide 251b, and a bracket 251c when attaching and detaching the drum unit, and opening the portions required for charging, exposure, development, transfer, and cleaning. It is the body.

The drum unit case 251
A photosensitive drum 101 having a shaft 252 integrally formed on the front side and a lid 253 fixed to the rear end is rotatably mounted therein, and the shaft 252 on the front side of the photosensitive drum 101 is attached to the inside thereof. The ground leaf spring 254 is pressed into contact with the bracket 251c, two separation claws 133 are mounted on the bracket 251c, and the sensor bracket 256 is fixed and the P sensor 257 is mounted. Therefore, the photoconductor drum 101, the separation claw 133 and the P sensor 257 can be integrally attached and detached by attaching and detaching the drum unit case 251.

A drum rotary shaft 2 rotatably inserted in a sleeve 261 rotatably mounted on a rear frame 260B in a lid 253 at the rear end of the photosensitive drum 101.
62 is fitted, a timing pulley 263 is fixed to the rear end of the drum rotation shaft 262, and a timing belt 264 is stretched between the timing pulley 263 and a timing pulley (not shown) attached to the main motor 100. Then, the main motor 100 causes the photosensitive drum 101
Is driven to rotate.

The rotating shaft 2 of the photosensitive drum 101
A sprocket 265 that is rotatably driven by a main motor 100 via a chain (not shown) is fixed to the rear end of the sleeve 261 that rotatably inserts 62, and the rear frame 206B and the photosensitive drum 101 are also connected.
Between the color developing device 118 and the black developing device 119
A developing gear 266 for transmitting the rotation is fixedly attached. Further, on the front side in the drum rotation direction of the transfer charger 131 provided below the photosensitive drum 101, for example, an LED
Is provided.

Next, the cleaning unit will be described. A toner recovery tank 138 is detachably attached to the cleaning unit case 271, a toner recovery shaft 137 is rotatably attached to the inlet of the toner recovery tank 138, a cleaning blade 135 and a discharge lamp 136 are further attached, and charging is further performed. The charger 102 is detachably attached. A mylar 138a is attached to the entrance of the toner recovery tank 138 to prevent the toner from dropping and scattering. Further, in the rear portion of the cleaning unit case 271, an integrally formed two-stage gear 2 that meshes with a gear 272 fixed to the toner recovery shaft 137.
73 and 274 are rotatably supported.

Then, the cleaning unit case 27
Attach the trumpet-shaped duct 275 to the upper part of 1,
A sensor mounting frame 276 is formed on the duct 275, and a toner over sensor plate 277 made of rubber or the like mounted vertically movable in the toner recovery tank 138 is sandwiched between the sensor mounting frame 276 and a light emitting element and a light receiving element facing each other. A toner over sensor 278 formed of a transmissive photo sensor is attached.

The duct 275 has an air inlet 28 therein.
External air taken in by a centrifugal fan 281 is sent from a duct 280 forming 0a, and the air flow is blown from the duct 275 to the periphery of the photoconductor drum 101 via the charging charger 102. The fan 281 is fixed to one output shaft 100a of the main motor 100 having both shafts. A gear head 282 is attached to the other rotating shaft of the main motor 100.
The rotation axis of the drive output shaft 100 such as the photosensitive drum 101
b.

6 to 9 are front sectional views of the color developing device 118 and the black developing device 119 of the developing unit, a plan view of the black developing device 119, a plan view of the color developing device 118 and a toner replenishing section of the color developing device 118. FIG.

First, the black developing device 119 will be described. The unit case 301 of the black developing device 119
As shown in FIG. 7, a long hole 301b is formed in a front end portion 301a projecting on the photosensitive drum 101 side.
01b is engaged with and held by a pin 303 planted in the front frame 302, and a rear end 301c is supported by a sub-frame 302a fixed to the front frame 302 by a shaft 304 which is swingably supported by a support plate 305 and a shaft 306. Is rotatably supported by
The developing sleeve 121 against the surface of the photosensitive drum 101
Are arranged so that they can be separated from each other.

Although not shown, the unit case 301 of the black developing device 119 cannot be independently pulled out by engaging the drum unit case 251 described above at the rear part to separate the black developing device 119 from the photosensitive drum 101. I am trying. This is because a black copy is normal and the black developing device 119 is not scheduled to be replaced for color change unlike the color developing device 118, so that the user can pull out the photosensitive drum 101 and the developing sleeve 1 independently.
This is for maintaining the image quality by preventing the positional deviation from 21 and the like. Also, unit case 3
The back and forth movement of 01 can be performed, for example, via a solenoid and a clutch.

Above the rear part of the unit case 301, as shown in FIG.
1. A toner replenishing portion including a toner hopper 312 and a toner replenishing roller 313, which are toner accommodating portions for accommodating toner to be supplied into the unit 1, is integrally mounted, and a toner replenishing portion including the toner hopper 312 and the toner replenishing roller 313 is integrated with the unit case 301. To be able to move.

In the unit case 301,
A developing sleeve 121 that supplies toner to the photosensitive drum 101, a paddle wheel 310 that supplies toner to the developing sleeve 121, and a toner hopper 31.
A mixing roller 315 in which a wire (or a band) 314 is spirally wound around the outer periphery of a paddle wheel 311 that supplies toner or the like supplied from inside 2 via a toner replenishing roller 313 to a paddle wheel 310 is rotated. It is installed as possible.

Further, inside the unit case 301, a doctor blade 316 for regulating the amount of toner supplied onto the developing sleeve 121 is provided, and the paddle wheel 31 is provided.
A toner return guide plate 318 provided with a deflection plate 317 for sending the toner regulated by the doctor blade 316 back to the mixing roller 315 one pitch at a time in the drum axis direction and returning the toner to the rear side. . The toner return guide plate 318 has a toner return screw 319 for returning the toner sent to the innermost end to the frontmost end.
The toner return screw 319 forms an opening 320 through which the toner returned to the front end is dropped onto the paddle wheel 310.

Then, as shown in FIG. 7, a sleeve gear 322 which meshes with the developing gear 266 of the drum unit described above is fixed to the developing sleeve 121, and the paddle wheel 310 meshes with this sleeve gear 322 via a gear (not shown). The paddle gear 323 is fixed to the mixing roller 3
15, a roller gear 324 meshing with the paddle gear 323 via a gear (not shown) is fixed, and a gear meshing with the roller gear 324 is fixed to the toner return screw 319, and the paddle wheel 310 and the mixing roller 315 are fixed.
Are rotated in opposite directions. The mixing roller 315 can be rotated in the same direction as the paddle wheel 310. The unit case 30
A handle 326 used for attaching and detaching the black developing device 119 together with the photosensitive drum 101 (drum unit) is fixed to the front end portion of 1.

The black developing device 11 thus configured
9, the new toner supplied from the toner hopper 312 via the toner replenishing roller 313 is supplied onto the mixing roller 315, and the unused toner is supplied to the mixing roller 315 via the toner return guide plate 318. By rotating the mixing roller 315 in the direction of the arrow in FIG. 6, these toners are sent to the paddle wheel 310 side. On the other hand, of the toner supplied to the photosensitive drum 101 by the developing sleeve 121, the used toner that has not been used for developing is returned to the paddle wheel 310 by the rotation of the developing sleeve 121 in the direction of the arrow in FIG. .

As a result, the used toner returned from the developing sleeve 121 and the new toner supplied from the mixing roller 315 are mixed by the rotation of the paddle wheel 310 in the direction of the arrow in FIG. 6, and the paddle wheel 310 is mixed. Is newly supplied to the developing sleeve 121. At this time,
Unused toner regulated by the doctor blade 316 is supplied onto the paddle wheel 310 from the opening 320 of the return guide plate 318.

Next, the color developing device 118 will be described mainly with reference to FIGS. This color developing device 1
18 unit case 331 is also the black developing device 1 described above.
19, the developing sleeve 1
20 is disposed so as to be able to come into contact with and separate from the surface of the photosensitive drum 101. Unlike the unit case 301 of the black developing device 119, this unit case 331 does not engage with the drum unit case 251 and the color developing device 1
18 is separated from the photosensitive drum 101 so that it can be independently pulled out in the axial direction of the developing sleeve 120, so that color change or the like can be easily performed.

In the unit case 331, a developing sleeve 1 for supplying toner to the photosensitive drum 101.
21, a paddle wheel 332 that is a first conveying member that supplies toner to the developing sleeve 121, collects the used toner, and conveys the used toner to the outside of the unit case 331 of the developing device. The used toner and the new toner are rotatably attached to the mixing roller 333 which is a second conveying member that conveys the used toner and the new toner into the unit case 331 from the outside.

The developing sleeve 120 of the color developing device 118 is the developing sleeve 12 of the black developing device 119.
The diameter is smaller than 1. In other words, the developing capacity is largely determined by the ratio of the diameter of the developing sleeve to the diameter of the drum, but when comparing black and color, the former is used more frequently and particularly high image quality is required. However, the latter is less frequently used, and it is considered that there is no big problem even if the image quality is relatively low compared to black, and it is desirable to downsize the device. Therefore, the color developing device 118
The diameter of the developing sleeve 120 is smaller than the diameter of the developing sleeve 121 of the black developing device 119, so that the color developing device is downsized.

The paddle wheel 332 is formed by winding a wire or a strip around the outer periphery of the paddle wheel in a counterclockwise spiral shape in the same manner as the mixing roller 315 of the black developing device 119, and the mixing roller 333 is also the same. In addition, a wire or strip is wound in a clockwise spiral pattern on the outer periphery of the paddle wheel.

Then, a part of the unit case 331 on which the paddle wheel 332 and the mixing roller 333 are mounted is extended to the front side of the front frame 302 to form a toner mixing section 331a as shown in FIG. A toner hopper 336, which is a toner accommodating portion of the toner replenishing portion 335, is integrally formed and provided on the upper side of 331a, and accordingly, the paddle wheel 332 and the mixing roller 333 are provided.
Is also extended to the lower part of the toner hopper 336 of the toner supply section 335, that is, to the inside of the toner mixing section 331a.

That is, the toner hopper 336, which is the toner accommodating portion of the color developing device 118, has the black developing device 119.
The toner hopper of the color developing device 118 has the same shape as the toner hopper of the black developing device 119 by providing a different shape from the toner hopper 312 of FIG. In comparison with the above case, the space occupied by the developing unit particularly in the height direction is reduced, and the image forming apparatus can be downsized.

Two agitators 337 and 338 are rotatably mounted in the toner hopper 336, and the toner replenishing roller 3 is placed between these agitators 337 and 338.
39 is rotatably mounted on the toner supply roller 33.
As shown in FIG. 9, seals 341 and 342 forming a toner replenishing port are pressed against the sheet 9. A lid 344 that can be opened and closed with the shaft 343 as a fulcrum is attached to the upper portion of the toner hopper 336. Also, the toner hopper 3
A color toner end sensor 345, which is a vibration sensor that detects the toner end, is attached to the side surface of 36.

Then, as shown in FIG.
20, the sleeve gear 346 that meshes with the developing gear 266 of the drum unit described above is fixed, and the paddle wheel 3
A paddle gear 347 that meshes with the sleeve gear 346 via a gear (not shown) is fixed to 32, and a roller 348 that meshes with the paddle gear 347 via a gear (not shown) is fixed to the mixing roller 333.
32 and the mixing roller 333 rotate in opposite directions.

Further, integrally formed gears 351 and 352 are fixed to an agitator 337 in the toner hopper 336, and a gear 353 and an agitator 338 meshing with one gear 351 via two gears (not shown). A gear 354 formed integrally with the gear 351 is fixed, and the toner replenishing roller 339 is also provided with a gear 354 not shown.
A gear 355 that meshes with the gear 351 is fixed via the individual gears.

The color developing device 1 thus configured
In FIG. 18, two agitators 337 and 338 in the toner replenishing section 335 rotate in the direction of the arrow in FIG. 9, and the toner replenishing roller 339 rotates while stirring the toner filled in the toner hopper 336. Then, new toner is supplied onto the paddle wheel 332 in the toner mixing unit 331a.

On the other hand, of the toner supplied to the photosensitive drum 101 by the developing sleeve 120, the used toner which has not been used for developing is the developing sleeve 121 shown in FIG.
Is returned to the paddle wheel 332 by rotation in the direction of the arrow. Then, by rotating the paddle wheel 332 in the direction of the arrow shown in FIG. 9, the used toner returned from the developing sleeve 121 moves in the direction of the arrow C of FIG. Toner mixing unit 331
The toner is discharged into the inside a, where it is mixed with the new toner supplied from the toner hopper 336 described above.

The toner in the toner mixing section 331a is
When the mixing roller 333 is rotated in the direction of the arrow shown in FIG. 9, it is fed in the direction of arrow D of FIG. 18, again carried into the developing device, supplied to the paddle wheel 332, and fed to the developing sleeve 120. In this way, the used toner is once transferred to the toner mixing section 33 outside the developing device by the paddle wheel 332.
1a, and the toner hopper 3 in the toner mixing section 331a provided at the position where it is delivered to the mixing roller 333.
After being mixed with new toner supplied from the developing device 36, the toner is surely replenished even if the toner hopper 336 is provided on the outer side of the developing device as described above by transferring the toner again into the developing device by the mixing roller 333. be able to.

This is because the used toner is charged, and in the case of a two-component developer, it is also mixed with a carrier. Therefore, by mixing the new toner with the carrier and carrying it, the carrying performance is improved. Because. In addition, it becomes easy to uniformly mix the used toner and the new toner in the developing device, and the density unevenness does not occur in the developed image.

The color developing device 118 and the black developing device 119 are arranged so as to be able to come into contact with and separate from the photoconductor drum 101 as described above. The developing device 118 is brought into contact with the black developing device 119 in the separated state, the color developing device 118 is brought into contact with the black developing device 119 during black development, and the color developing device 118 is brought into contact when the copying operation is not performed. Both the black developing device 119 and the black developing device 119 are set to the separated state.

It should be noted that the color developing device 118 can be pulled out separately from the photoconductor drum 101 as described above, although it is possible to maintain the same state as in the copying operation even when the copying operation is not being performed. In this case, the surface of the photoconductor drum 101 is not damaged when the color developing device 118 is attached or detached by keeping the color developing device 118 in the separated state. When the black developing device 119 is also separated from the photoconductor drum 101 so that it can be pulled out, the surface of the photoconductor drum 101 can be prevented from being damaged when the black developing device 119 is detached similarly.

As described above, in the color developing device 118, the used toner is once moved to the external toner mixing section 331a by the paddle wheel 332 and mixed with new toner, and then the toner is again mixed by the mixing roller 333. Mixing part 3
Since it is sent out from 31a and supplied to the developing sleeve 120 via the paddle wheel 332, the developing device can be downsized without impairing the developing performance.

Regarding the color developing device 118 among the color developing device 118 and the black developing device 119, when the toner end sensor 345 detects the toner end, the toner replenishing roller 339 is rotationally driven to perform a fixed amount. Toner is replenished, and in the black developing device 119, the toner replenishing roller 313 is rotationally driven according to the detection result of the density detection by the P sensor 257 to replenish toner. Therefore, the toner density detection using the P sensor will be described with reference to FIGS. 10 and 11.

To detect the toner density using this P sensor, as shown in FIG. 10, a P sensor pattern 360 is attached to the lower surface of the contact glass 115 on the left side of the document leading edge position, and the leading edge erase timing is turned on (full face erase).
→ A5R size erase → ON → Size-specific erase, and as shown in FIG. 11, a P sensor pattern image 362 is formed on the surface of the photosensitive drum 101 in front of the original image. Then, the P sensor pattern image 362 is moved to the position of the P sensor 257 without performing transfer to the transfer paper by controlling the transfer paper feeding timing, and the P sensor pattern image 362 is illuminated by the light emitting element of the P sensor 257. And the reflected light is received by the light receiving element, the density of the P sensor pattern image 362 is detected, and the toner replenishment amount is controlled according to the detection result.

The toner concentration detection using the P sensor is performed, for example, for the first sheet after the power is turned on and every 10 sheets thereafter, and when it is detected that the toner concentration is low, 10 sheets until the next toner concentration detection timing are detected. The toner replenishing roller 313 is turned on and off for each sheet until the eye continues to replenish toner. Further, for the color toner to be supplied in a fixed amount, it is possible to make an abnormality determination based on the toner density detection result by the P sensor 257.

Next, the operation timing of the developing device will be described with reference to FIG. The bias is turned on at a time point T1 when a predetermined time has elapsed from a time point T3 at which the start key provided on the main operation panel 7 shown in FIG. 1 is turned on.
State. The bias at this time is set to a constant bias (non-image portion) regardless of the notch of the density key, and then set bias (image portion) based on the data of the automatic density adjustment system (ADS) after a lapse of a predetermined time. Also, the bias is returned to a constant value after a lapse of a predetermined time from the scanner return, and the bias is turned off after a predetermined time from the fixing detection OFF.

Then, for example, when the toner density becomes low, a time T when a predetermined time has elapsed since the scanner returned.
In step 2, the toner supply solenoid is turned on, and this state is continued until the next toner density check. In addition, since the type of color toner of the color developing device 118 is displayed at the time T3 when the start key is turned on and the color toner end is detected by the vibration sensor, a predetermined time or more is elapsed from the time T4 when the vibration starts. When vibration continues, color toner end is set.

Next, the control of the developing bias will be described. The developing bias can be adjusted by adjusting the bias output together with the lamp voltage using the density key provided on the main operation panel 7, or by reading the background density of the document by ADS and adjusting the bias output according to the value. is there. Note that FIG. 13 shows the relationship between the notch and the bias voltage when using the density key, and FIG. 14 shows the relationship between the ADS data and the bias voltage in the ADS mode.

Next, the black developing device 1 which is made by the control unit having the microcomputer of this copying machine built therein.
The toner density control of No. 19 will be described with reference to FIG. First, whether the number of copies has reached (10n + 1)
That is, it is determined whether or not 10 copies have been completed since the last check, and when the number of copies becomes (10n + 1), a P sensor pattern image is created and the front and rear of the P sensor pattern image are sensed. The output VSG of the P sensor 257 when the P sensor 257 is present and the output VSP of the P sensor 257 when the P sensor pattern image is sensed are obtained.

If 0.5 <VSP, the process directly returns to the copy number determination process, and if 0.5≤VSP≤0.9, the process returns to the copy number determination process after toner supply.
If 0.9 <VSP, it is determined whether or not the maximum replenishment rate is reached, and if not, the determination processing of the number of copies after replenishing the toner set to the maximum replenishment rate Return to. On the other hand, if the maximum replenishment rate is reached, after the toner end indicator blinks, it is determined whether the number of copies exceeds 50 in that state, and if the number of copies is 50 or less, copying is possible. When the number of sheets exceeds 50, the toner end indicator is turned on and the start key 14 is set to red (copy not possible).

As a fixed amount of color toner, the fixed amount of supply is stopped when the output VSP of the P sensor 257 becomes lower (darker) than a predetermined reference value.
For the black toner, the output V of the P sensor 257
When SG falls below a predetermined reference value, it is determined that the toner concentration control is abnormal, and the toner supply amount is shifted to a fixed amount replenishment mode. When the color toner falls below another reference value, the toner replenishment amount is halved. In the above embodiment, an example in which the present invention is applied to a copying apparatus has been described, but the present invention can be similarly applied to a printing apparatus such as a laser printer.

[0064]

As described above, according to the present invention, it is possible to reduce the height of the entire developing section including the toner storing section for storing the replenishing toner to reduce the required space. Therefore, the image forming apparatus can be downsized. Moreover, the first carrying member and the second carrying member are located outside the developing device at a position where the toner is delivered.
By supplying the toner in the toner storage portion, the new toner is surely carried into the developing device along with the used charged toner or mixed toner with the carrier even in the lateral conveyance, and the used toner and the new toner are newly supplied. Since the toner is mixed and replenished without unevenness, unevenness in density does not occur in the developed image.

[Brief description of the drawings]

FIG. 1 is an external view showing an example of a copying apparatus as an image forming apparatus embodying the present invention.

FIG. 2 is a schematic sectional view showing a mounting structure of a sub operation panel 8 shown in FIG.

FIG. 3 is an overall schematic configuration diagram showing a mechanical unit of the copying apparatus main body 1 shown in FIG.

FIG. 4 is a front sectional view showing details of the drum cleaning unit.

FIG. 5 is a plan view showing details of the drum cleaning unit.

6 is a front sectional view showing details of a color developing device 118 and a black developing device 119 shown in FIG.

FIG. 7 is a plan view of the black developing device 119.

FIG. 8 is a plan view of the color developing device 118.

FIG. 9 is a front sectional view of the toner supply unit of the color developing device 118;

FIG. 10 is an explanatory diagram for explaining the toner density detection by the P sensor.

FIG. 11 is an explanatory diagram for explaining toner concentration detection by the P sensor.

FIG. 12 is a timing chart illustrating operation timings of the developing device.

FIG. 13 is a diagram showing a relationship between a notch of a density key and a bias voltage.

FIG. 14 is a diagram showing a relationship between ADS data and a bias voltage.

[Explanation of symbols]

 1: Copying device main body 2: ADF 3: Sorter 4: Synthetic / duplex unit 5: Manual feed tray 6: Paper feed cassette 7: Main operation panel 8: Sub operation panel 9, 10: Paper feed cassette 101: Photosensitive drum 102: Charging charger 105: Exposure lamp 118: Color developing device 119: Black developing device 131: Transfer charger 120, 121: Developing sleeve 132: Separation charger 136: Static elimination lamp 135: Cleaning blade 141: Conveying belt 142: Fixing device 149: Paper discharge Roller 331: Unit case 331a: Toner mixing portion 332: Paddle wheel (first conveying member) 333: Mixing roller (second conveying member) 335: Toner replenishing portion 336: Toner hopper (toner accommodating portion) 337, 338: Agitator 339: Toner supply roller

[Procedure amendment]

[Submission date] September 17, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] FIG.

[Correction method] Added

[Correction contents]

FIG. 15 is a flowchart showing a toner density control process of the black developing device by the control unit.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Masayuki Takashima 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (2)

[Claims] 1. An image forming apparatus comprising: a developing device; and a toner containing portion for containing toner to be supplied to the developing device, wherein the toner containing portion is provided near an outer portion of the developing device. A first conveying member that conveys the used toner from the outside to the outside of the developing device, and a second conveying member that conveys the toner into the developing device from the outside of the developing device. The image forming apparatus is characterized in that the toner in the toner accommodating portion is supplied to a position where the toner is transferred between the second conveying member and the second conveying member outside the developing device. 2. The used toner carried out by the second transport member and the toner accommodating portion are located at a position where the first transport member and the second transport member transfer the toner outside the developing device. The image forming apparatus according to claim 1, wherein the image forming apparatus is in a mixing unit that mixes with new toner supplied from.