JPS60239779A - Image forming device - Google Patents

Abstract

PURPOSE:To control the concn. of a developer well with high precision by starting discrimination of the developer concn. based on the output of a developer concn. detecting means when a prescribed time spent in stabilization of flow of the developer to the developer concn. detecting means elapses after supply of the developer onto a developer carrying means is started by driving a developing device. CONSTITUTION:A developing mechanism part 331 is provided in the upstream side of a developing roll 311 and the part, where a developer magnetic brush 351 formed on the surface of the developing roll 311 rubs against a photosensitive drum 7, and is provided in the downstream side of a doctor 371, which controls the thickness of the developer magnetic brush 351, and a developing position 361. A scraper 391 which scrapes the developer magnetic brush 351 on the surface of the developing roll 311 and leads it to a developer storage part 381 and a developer agitating body 401 stored in the developer storage part 381 are stored in a casing 411. A developer concn. detector 421 which detects magnetically the variance of the permeability of a developer G1 to detect the developer concn. is attached to the position, which faces a position above the developing roll 311, of the casing 411.

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 capable of making color copies of a plurality of colors.

[Technical background of the invention and its problems] In recent years, for example, color copying machines have become more popular, and two-color color copying machines that can produce images in colors other than black have been put into practical use.

However, in the past, for this kind of color copying, multiple cartridges were prepared in which a developing device and a photoreceptor were integrated, and the cartridges were selectively replaced, which caused the problem that the operation was extremely troublesome. .

Recently, however, it has become possible to make color copies of various colors by installing a plurality of removable developing devices each capable of developing different colors, and by selecting one or more of the developing devices. A color copying machine is being considered. By the way, in this type of copying machine, the concentration of the developer in the developing device is detected by a concentration detector, and the developer replenishment means is operated according to the detection result, so that the concentration of the developer is always maintained at a constant value. It is automatically controlled so that However, in general, after the developing device is driven, it takes several seconds from when the supply of developer onto the developing roller serving as a developer conveying means is started until the flow of the developer to the concentration sensor becomes stable. Therefore, if the detection of the developer concentration is started in such an unstable state, the developer concentration cannot be detected accurately, and it is impossible to control the developer concentration with high accuracy.

[Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and its purpose is to accurately detect the concentration of developer in a developing device and to control the concentration of developer with high precision. An object of the present invention is to provide an image forming apparatus that enables image forming.

[Summary of the Invention] In order to achieve the above-mentioned object, the present invention detects the supply of developer to the developer concentration detecting means after the developing device is driven and the supply of the developer onto the developer conveying means is started. After a predetermined period of time when the flow becomes stable, the developer concentration is determined based on the output of the developer concentration detection means.

[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, 1 is a main body of a copying machine, and a document table 2 is provided on the upper surface of the main body 1 and is movable back and forth in the left-right direction (in the direction of arrow a in the figure). Also,
A paper feed cassette 3 is attached to the right side of the main body 1, and a paper discharge tray 4 is attached to the left side. The cassette cover 5 of the paper feed cassette 3 serves as a manual feeding table 6 for manually feeding paper P2 as appropriate. Further, a photosensitive drum 7 is disposed approximately in the center of the main body 1. The photosensitive drum 7 is surrounded by a charging device 8, an optical system 9, and a two-color developing device 1, which will be described later.
0, transfer charger 11, peeling charger 12, cleaning device 1
3, a static elimination lamp 14, etc. are arranged in this order.

Further, in the lower part of the main body 1, a sheet Pi automatically taken out from the paper feed cassette 3 via the paper feed roller 15 or a paper P2 manually fed from the manual feed table 6 is charged for transfer to the photoreceptor drum 7. A paper conveyance path 17 is formed that leads to the paper discharge tray 4 via the image forming section 16 between the paper feeder 11 and the paper discharge tray 4 . A registration roller 18 is disposed on the upstream side of the image transfer section 16 of the paper conveyance path 17, and a heat roller 19 and a paper discharge roller 20 as a fixing device are disposed on the downstream side.

Here, the optical system 9 has an exposure lamp 22 whose back portion is surrounded by a reflector 21, mirrors 23 to 26, and a lens 27.

The photosensitive drum 7 is driven by a drive mechanism (not shown) in the direction indicated by the arrow in the drawing in synchronization with the document table 2. First, the exposure lamp 2 is uniformly charged by the charging device 8.
The image of the document uniformly irradiated with light by the optical system 9 is formed on the photoreceptor drum 7 to form an electrostatic latent image. This formed electrostatic latent image is developed into a developer image by the developing device 1o, and is sent to the transfer charger 11 side. On the other hand, the automatically or manually fed paper P1 or P2 is fed by a registration roller 18, and a developer image previously formed on the photosensitive drum 7 is transferred by a transfer charger 11.

The paper Pi (P2) to which this developer image has been transferred is separated from the photoreceptor drum 7 by a separation charger 12, passes through a paper conveyance path 17, and is guided to a heat roller 19, where the transferred image is melted. After being fixed, the paper is discharged to the paper discharge tray 4 by the paper discharge roller 20.

On the other hand, after transferring one image of developer onto paper PI (P2),
The residual toner remaining on the photoreceptor drum 7 is cleaned by a cleaning device 13, and the residual image on the photoreceptor drum 7 is roughly erased by a static elimination lamp 14, so that the photoreceptor drum 7 can be used for the next copying operation.

In the main body 1, an upper frame and a lower frame (not shown) are pivotally supported at one end via a support shaft (not shown), and the other ends of both frames are rotated at a desired angle, for example, about 30 degrees. It is configured so that it can be opened to Each device such as a charging device 8, an optical system 9, an exposure lamp 22, a developing device 10, a cleaning device 13, and a defrosting lamp 14 are attached to the upper frame around the photosensitive drum 7 by appropriate means. Furthermore, the document table 2 and paper feed roller 15 are also attached to the upper frame, and the upper unit 1A
It consists of The lower frame also includes a paper feed cassette 3, a transfer charger 11, a peeling charger 12. Heat roller 19, paper ejection roller 20, paper ejection tray 4, etc. 1j
The lower unit 1B is constructed by attaching the main motor 28 and the like by appropriate means. After the front cover of the main body 1 is rotated and removed, it is configured so that it can be opened and closed substantially along the paper transport path 17 of the paper PI (P2) via a housing opening/closing device (not shown).

In addition, 29 is the cleaning blade 30 of the cleaning device @13.
This is a blade solenoid for bringing the photoconductor drum 7 into contact with and separating it from the photoreceptor drum 7.

Next, details of the developing device 10 will be explained. Second
In the figure, a first developing roller 311 and a second developing roller 312 are included in the group, and these developing rollers 311.
312 can be selectively driven to perform color development of black or one color other than black, such as red, yellow, blue, or green.

That is, the developing device 10 includes a first developing device 321 including a first developing roller 311 and a second developing device 321 including a second developing roller 312.
The developing unit 322 is divided into two parts, and these first and second developing units are divided into two parts.
The developing units 321 and 322 are both removable from the main body 1. In this case, the first developing device 321 in the upper stage is configured to be easily attached and detached so that the user can pull it out upward in the figure, and the second developing device 322 in the lower stage is designed to be maintained and inspected by a service person. It is configured so that it can be attached to and detached from the main body 1 when carrying out this operation. The frequently used black developer is used in the second developing device 322 in the lower stage, and the color developer is used in the first developing device 32r in the upper stage.

The first developing device 321 includes a developing mechanism section 331 and a developer replenishing section 341. The above development i structure section 33
1 is provided at the sliding contact portion between the developing roller 311 and the photosensitive drum 7 of the developer magnetic brush 351 formed on the surface of the developing roller 311, that is, on the upstream side of the development position @361, and the developer magnetic A doctor 371 that regulates the thickness of the brush 351 and a developer magnetic brush 35 provided downstream from the development position 361 and on the surface of the development roller 311.
1 and guides it to the developer storage section 381.
1 and a developer agitating body 4 accommodated in the developer accommodating section 381.
01 is housed in a casing 411. Note that a developer concentration detector 421 is installed at a position above the developing roller 31s of the casing 411, which detects the developer at 41 degrees by magnetically detecting changes in the permeability of the developer G1. It is worn.

The developing roller 311 is a magnetic roll whose center is located on a straight line L2 that passes through the center of rotation of the photosensitive drum 7 and forms an angle α (approximately 51°) with respect to the horizontal IL1. 431, and a sleeve 441 that is fitted onto the magnetic roll 431 and rotates clockwise in the figure. The magnetic roll 431 has five l 1
1 part 451 to 491, of which the magnetic pole part 451,
471.491 is N tff! , magnetic pole part 46t, 48
t is the S pole, and the angle θ1 between the magnetic pole parts 451 and 461 is about 50'! The angle θ2 between the i-pole portions 461 and 471 is approximately 71°, the angle θ3 between the magnetic pole portions 471 and 481 is approximately 60°, and the angle θ4 between the magnetic pole portions 481 and 491 is approximately 60°. It is set.

Further, the developer replenishment section 341 includes a developer replenishment port 501.
The developing mechanism section 33! A hopper 511 facing the developer storage section 381 , and a developer replenishment roller 5 provided within the hopper 511 to close the developer replenishment port 501 .
2, and the developer G on this developer supply roller 521 side.
The developer G in the hopper 51 is transported so as to convey 1! The structure includes a pair of stirring rollers 531.53t for stirring.

Further, the second developing device 322 is similar to the first developing device 322 described above.
It has almost the same basic configuration as 1, and the developer supply section 34
2, the shape of the hopper 512, the arrangement structure of the m poles of the magnetic roll 432 of the developing roller 312, the mounting position of the developer concentration detector 422, and the accompanying narrow width (approximately 50 mm) with an approximately 20° inclination. The difference is that a scraper 54 is added. Therefore, other identical components will be designated by reference numerals with the suffix character changed from "1" to "2", and detailed explanations will be omitted. The developer concentration detector 422 is attached to the rear surface of the casing 412 with its detection surface vertical within the casing 412. Further, the scraper 54 scrapes the developer scraped from the developing roller 312 to a developer concentration detector 422.
This is a guide member for guiding the sensor to the detection surface of the sensor. Further, the magnetic roll 432 of the developing roller 312 has four magnetic pole parts 452 to 482, of which magnetic pole parts 452 and 47
2 is the N pole, the magnetic pole parts 462 and 482 are S↑l, and the angle θ5 between the magnetic pole parts 452 and 462 is about 78°,
The angle θ6 between the magnetic pole parts 462 and 472 is set to about 70°, and the angle θ7 between the magnetic pole parts 472 and 482 is set to about 80'. Further, the magnetic roll 432 passes through the rotation center of the photoreceptor drum 7 and makes an angle β with respect to the horizontal line L1.
(approximately 1°) with the center located on the straight line IL3.

On the other hand, each of the magnetic rolls 431 and 432 of the first developing device 321 and the second developing device 322 is configured to be able to rotate at a rotation angle of approximately 25 degrees. Along with the displacement operation, the developing roller 3'll,
Developer magnetic brushes 351 and 352 can be formed and removed on the surface of 312. Then, the magnetic rolls 431 and 432 of the first developing device 321 and the second developing device 322 are switched to predetermined positions by magnetic roll driving means, which will be described later.
Alternatively, the developer magnetic brush 351 .is applied only to the surface of the developing roller 311 .
352 is formed.

That is, when operating the first developing device 321 side,
As shown in FIG. 2, the magnetic roll 4 on the first developing device 321 side
31 with the magnetic pole portion 47t facing the development position 361, and the doctor 3 placed approximately halfway between the magnetic pole portions 451 and 461.
While setting the γ-work to the position, 2.1i! The magnetic roll 432 on the imager 322 side is connected to the magnetic pole part 452 by the doctor 3.
72. Then, the first developing device 321
The developer magnetic brush 3 is applied only to the surface of the side developing roller 311.
51 is formed.

In addition, when operating the second developing device 322 side, the third developing device 322 side is operated.
As shown in the figure, the first modern device 32! Side magnetic roll 431
is rotated approximately 25 degrees clockwise from the position shown in FIG. 2 so that the magnetic pole part 451 faces the doctor 371, and the magnetic roll 432 of the second developing device 322 is moved counterclockwise from the position shown in FIG. Rotate about 25 degrees to t*#
The doctor 372 is positioned approximately midway between the upper part 522 of the A part 45. The developer magnetic brush 352 is formed only on the surface of the developing roller 312 on the second developing device 322 side.

In addition, the magnetic pole part 451.4 of the magnetic roll 431.4'32
The reason why the developer magnetic brushes 35r and 352 are not formed on the surface of the developing roller 311, 312 when the developer roller 311, 312 is opposed to the doctor blades 371 and 372 made of non-magnetic material is because the magnetic pole portions 451, 452 are Since the density is in a slender state, the power to adsorb the developer Gt, G2 is weak.
This is because it can be easily regulated by the doctor blades 371, 372, and even if the sleeve 44, 1, 442 rotates, the developer Gt will not be released.

G2 never passes through the doctor part 371 and 372.

By the way, each drive unit of the first developing device 321, that is, the developing roller 31! Sleeve 44! , developer stirring body 401,
A driving force is transmitted to the developer replenishing roller 521 via a first driving force transmission system 61, which will be described later.

Further, driving force is transmitted to each drive unit of the second developing device 322, that is, the sleeve 442 of the developing roller 312, and the developer stirring body 402 via a second driving force transmission system 62, which will be described later. . The first and second driving force transmission systems 61
．． Reference numeral 62 has a configuration as shown in FIGS. 4 to 6, and the first and second developing units 32 are operated by rotating a rotatable motor 63 as a common driving source in the forward or reverse direction.
Only one of the drive systems of 1.322 is selectively operated.

Hereinafter, the driving force transmission system will be explained in detail with reference to FIGS. 4 to 6. The first driving force transmission system 61 includes an intermediate gear 65 that meshes with a driving gear 64, a first driven gear 66 that meshes with this intermediate gear 65, an intermediate gear 67 that meshes with this driven gear 66, and this intermediate gear 67. The second meshing with
It has a driven gear 68. Further, the second driving force transmission system 62 includes a third driven gear 69 that meshes with the driving gear 64.
, an intermediate gear 70 that meshes with this driven gear 69 , and a fourth driven gear 71 that meshes with this intermediate gear 70 . Then, when the drive gear 64 rotates normally, that is, in the direction of the solid line arrow in FIG.
71 rotate in the direction of the solid line arrow, and the drive gear 64 rotates in the reverse direction, that is, in the direction of the broken line arrow B in FIG. Each of the gears 69 to 71 of the system 62 rotates in the direction of the dashed arrow.

Further, the first driven gear 66 is connected to the drive shaft 721 that is integrated with the sleeve 441 of the first developing roller 311, and the second driven gear 68
are attached to the drive shafts 731 of the developer agitating body 40 via one-way clutches 74 and 74, respectively, and the drive shafts 721 and 731 have gears 66 and 68 that rotate in the direction of the solid line arrow, that is, are driven. The driving force is transmitted only when the gear 64 rotates in the normal direction, and the gear 64 rotates in the direction of the dashed line arrow. Further, the third driven gear 69 is connected to the drive shaft 722 which is integrated with the sleeve 442 of the second developing row 5312, and the fourth driven gear 71 is connected to the drive shaft 722 of the developer stirring body 402.
2 through one-way clutches 75, 75, and each drive shaft 722, 732 is connected to a gear 69.
．． 71 respectively rotate in the direction of the dashed line arrow, that is, only when the drive gear 64 is reversed, the driving force is transmitted and the drive gear 64 rotates in the direction of the dashed-dotted line arrow.

Further, the driving gear 64 has a bearing 7 as shown in FIG.
The drive shaft 78 of the reversible motor 63 is rotatably supported via the gear mechanism 77.
It is attached to a rotating shaft 79 that interlocks with the. That is,
A gear 80 is attached to the rotating shaft 79, and the gear 80 is rotatably mounted on a support shaft 83 installed between a motor mounting frame 81 and a stay 82 integrated therewith via bearings 84 and 84. It meshes with the attached gear 85. A gear 86 having a larger diameter than the gear 85 is integrally formed with the gear 85, and the gear 86 is attached to the oscillator motor 63.
The gear 87 is in mesh with the gear 87 attached to the drive shaft 78. Thus, the rotation of the drive shaft 78 of the reversible motor 63 in both forward and reverse directions is transmitted to the rotation shaft 79 via the gears 87, 86, 85, 80, thereby causing the first and second developing units 321 and 322 to rotate. It is possible to selectively operate the reversible motor 63 by simply switching between forward and reverse rotation.

Note that switching between forward and reverse rotation of the reversible motor 63 is performed by pressing a color selection key on the operation panel, which will be described later, and at this time, the non-operating magnetic roll 43s, The magnetic pole portions 45s and 452 of 432 can be switched to face the doctors 37r and 372.

Further, an intermediate gear 65 that meshes with the driving gear 64 and the first driven gear 66 is rotatably attached to a support shaft 89 via a bearing 88.

The support shaft 89 is a bearing 76°76 that pivotally supports the rotating shaft 79.
It is attached to an arm 91 that can swing around a housing 90 holding the housing 90 as a center of rotation, and its position can be changed so that it can reliably mesh with the drive gear 64 and the first driven gear 66. ing.

Further, one stirring roller 531 of the first developing device 321 is
The stirring roller 531 is intermittently driven via a first operating mechanism 921 shown in FIG.
The other stirring roller 531 and developer replenishing roller 521 are simultaneously driven in conjunction with the movement. That is, one stirring roller 53 of the first developing device 321
A ratchet gear 941 is attached to one end of the shaft 931, and this ratchet gear 941 is connected to the solenoid 9.
It is intermittently driven at predetermined intervals via a ratchet pawl 971 attached to a swinging arm 961 that rotates and displaces in conjunction with the on and off operations of the switch 51. Further, sprockets (not shown) are attached to the shafts 931 and 98 of the stirring rollers 531 and 531 and the shaft 991 of the developer replenishing roller 521, respectively. An endless chain (not shown) is wrapped around the stirring roller 531 and 53 via this driving force transmission system (not shown).
1 and developer supply roller 521 are driven together.

Further, the stirring roller 532 and the developer replenishing roller 522 of the second developing device 322 are simultaneously driven intermittently through a second operating mechanism 922 having the same configuration as the first operating mechanism 921 and a driving force transmission system having approximately the same configuration. It is now possible to do so. Note that the first actuating mechanism 921 and the same two constituent parts are designated by reference numerals with the suffix character changed from "1" to "2", and detailed explanation thereof will be omitted.

Next, the structure of the magnetic roll driving means 1001 (1002) for rotationally displacing the magnetic roll 431 (432) in order to form or remove the developer magnetic brush 351 (352) on the surface of the developing roller 311 (312). will be explained with reference to FIGS. 7 to 9(a) and (b). The shaft 101t (101
2) One end is attached to the bearing 1 attached to the 7Lz-mem 102.
03, and a lever 10 is attached to the tip of the shaft.
4 is installed. The tip of this lever 104 is connected to an arm 106 rotatably attached via a support shaft 105.
It is in a state where it is engaged with the engagement groove 107 of. moreover,
Support part 1 formed at the lower part of the pivot end side of the arm 106
08 is connected to a plunger 110 of a solenoid 10.9, and one end of a tension spring 112 is connected to a support portion 111 formed at the upper portion of the pivot end side.

Therefore, when the solenoid 109 is off, the arm 106 is moved to the eighth position by the biasing force of the tension spring 112.
The magnetic pole portion 451 (452) is moved to the position indicated by the two-dot chain line in the figure, that is, as shown in FIG.
The lever 104 is held in a position facing the lever 72). Therefore, when the solenoid 109 is off, the developer magnetic brush 351 (352) is not formed on the surface of the developing roller 311 (312). In addition, when the solenoid 109 is in the ON state, the arm 106 is moved to the position shown by the solid line in FIG. 8 due to the biasing force of the tension spring 112, that is, the position shown in FIG.
As shown in
The lever 104 is rotated to a position facing (372). Therefore, solenoid 1
09, a developer magnetic brush 351 (352) is formed on the surface of the developing roller 311 (312).

By the way, as shown in FIGS. 2 and 3, the doctor 372 described above includes a doctor body 1132 made of a non-magnetic material, and a magnetic body 114 made of a band-shaped iron plate provided along the longitudinal direction of this doctor body 1132. , doctor body 113
A magnetic body 1152 consisting of an iron plate provided at both ends of the magnetic body 1152.
1152 (only one is shown). The magnetic bodies 114, 1152, and 1152 have magnetic pole portions 452 facing the doctor 372 and the developing roller 3.
When removing the developer G2 on the surface of the magnetic pole part 4
The configuration is such that lines of magnetic force are formed between the developer G2 and the developer G2 to more reliably prevent the developer G2 from being taken out. Also, Doctor 3
71 has a structure including a doctor body 113 made of a non-magnetic material and magnetic bodies 1151.115t (only one shown) made of iron plates provided at both ends of this doctor body 1131, and has Similarly to the case of the doctor 372, removal of the developer G1 is prevented. This doctor 371 is not provided with a magnetic body along the longitudinal direction of the doctor body 1131 like the doctor 372 described above, and the 141 pole part 451 of the developing roller 311 facing the doctor 371 and the magnetic pole part of the developing roller 312 482 to prevent the developer G1 from being taken out.

Further, a magnetic plate 116 is provided between the developing roller 311 and the developing roller 312, as shown in FIGS. 2 and 3, to control the magnetic flux density and polar distribution of the other magnetic roller 431 (432). This weakens the influence and enables good developer transport operation.

Note that 1172 shown in FIGS. 2 and 3 is a developer remaining amount detection device that detects when the amount of developer G2 in the hopper 512 of the second developing device 322 has fallen below a predetermined value. A configuration in which a permanent magnet 120 attached to an actuator 119 integrated with a detection lever 118 that rotates according to the movement of the hopper is activated when it approaches a reed switch 121 as a detector provided on the outside of the hopper 512. It has become. Further, although not shown, a developer remaining amount detecting device 1171 having a configuration similar to the developer remaining amount detecting device 1172 is provided for the hopper 511 of the first developing device 321 as well.

Further, as shown in FIGS. 2, 3, and 10, a hopper cover 131 that forms part of the upper surface of the main body 1 is provided on the upper surface side of the developing device 10 so as to be openable and closable. A lid 1331 that opens and closes the top opening 1321 for replenishing the developer of the first developing device 321 when opened and the top opening 1322 of the second developing device 322 for replenishing the developer.
A lid body 1332 that opens and closes is exposed.

By opening the lids 1331 and 1332, the developer G1. G2 can be easily replenished from the top side. In addition, the above-mentioned lid body 1331.1332
are provided with color display sections 1341 and 1342, and the developer G1. The color of G2 can be easily distinguished, and developer of a different color is not mixed in by mistake.

Further, 135 shown in FIGS. 2 and 3 is a cover opening/closing detection device for detecting opening/closing of the hopper cover 131, and a permanent magnet 13 attached to the tip of the hopper cover 131
6, and a reed switch 137 as a detector which is provided on the main body 1 side and turns on when the magnet 136 approaches when the hopper cover 131 is closed.

In addition, as shown in FIGS. 10 and 11 (a), (b) k, the hoppers 511 of the first and second developing devices 321 and 322
, 512, the top surface 138t, 1382, and the lid 133r.
, 1332 are each equipped with an integrated time meter 1391.13 as a life indicator that displays the developer life.
92, and a developer out indicator 140 that indicates that the amount of developer in the hoppers 511 and 512 is below a predetermined amount.
1.1402 is provided. The above cumulative time meter 139
s.

1392, for example, displays the life of the developer by measuring the amount of rotation (time) of the sleeves 44r and 442 that constitute the developing rollers 311 and 312, respectively. An electrolytic type integrating time meter (trade name: FC timer) is used.

On the other hand, a first developing device 321 containing color developer G1
is a cartridge type that can be freely attached to and detached from the main body 1, and can be easily removed by pulling up the handle 141 (see FIG. 10) in an upright position. That is, the developer supply section 341 of the first developing device 321
Positioning members 142 and 142 (only one is shown) are attached to both the front and rear walls of the
Both end support parts 144, 144 of the handle 141 are rotatably attached to 2.142 via support shafts 143.143. Hooks 145 that are rotatable around a support shaft 143 are integrally attached to the support portions 144 and 144 of the handle 141, respectively, as shown in FIGS. 12 and 13(a), (b) (l). It is configured to engage with a locking pin 146 provided on the main body 1 side to restrict upward movement.Also, a first positioning portion formed on the lower end side of the positioning member 142 The engagement groove 147 as a second positioning portion and the end surface 148 as a second positioning portion are adapted to engage and abut positioning pins 149 and 150 provided on the main body 1 side, and hold the first developing device 321 in a predetermined position. When the handle 141 is raised up, the engagement between the hook 145 and the locking pin 146 is released, and the handle 141 is placed in a substantially horizontal state. When pushed down, the hook 14 will be released as shown in Figure 13(b).
5 is engaged with the locking bottle 146, and by further pushing it from the horizontal position, the hook 145 and the locking bottle 146 are connected to the first developing device 32, as shown in FIG. 13(C).
It is designed to engage reliably in a state where it is pressed downward. Therefore, if the handle 141 is in an upright state, the first developing device 321 can be attached and detached, and if the handle 141 is folded down after inserting the first developing device 321, the first developing device 321 can be attached and removed.
can be fixed and its operation is extremely easy.

Next, the developing operation of the developing device 10 will be explained. First, when the first developing device 321 side is selected to operate using the color selection key, the magnetic rolls 43s and 432 enter the state shown in FIG. The sleeve 441 rotates clockwise in the state shown in FIG. 2 to form a developer magnetic brush 351 on the surface of the sleeve 441. Developing is performed using the developer G1. In this way, when the development of the electrostatic latent image is completed, the magnetic roll 431 is rotated by about 251 degrees, and the magnetic pole part 451 faces the doctor 37s, so that the sleeve 441 New formation of the developer magnetic brush 351 on the upper side is stopped, and in this state, the sleeve 441 is further rotated by a predetermined amount to remove the developer magnetic brush 35.
1 is removed. Note that at this time, the second developing roller 312
Since the developer magnetic brush 352 is not formed in either of the developer devices 321 and 322, problems such as color mixing will not occur even if any of the developer devices 321 and 322 is selected next.

Further, when the second developing device 322 is selected for black color development, the magnetic rolls 431 and 432 are brought into the state shown in FIG. rotates clockwise in the state shown in FIG. 3, forming a developer magnetic brush 352 on the surface of the sleeve 442. After the electrostatic latent image on the photosensitive drum 7 is developed to black in the manner described above, the developing operation is completed with the developer magnetic brush 352 removed from the surface of the sleeve 442.

Note that the developer stirring body 401 (402) and the stirring roller 53 of the developing device 321 (322) in the developing operation state
1 (532) is always operating, and the developer supply roller 521 (522) is the developer concentration detector 421.
The developer Gl (G2) is appropriately replenished by a control signal based on the output signal of (422), so that a good developing operation is maintained.

FIG. 14 shows the operation panel, including a copy key 151 for executing a copy operation, an interrupt key 152 for specifying an interrupt mode for interrupt copying, and an interrupt key 152 for specifying an interrupt mode for interrupt copying. 153, a numeric keypad 154 for setting the number of copies, a number display section 155 for displaying the number of copies, a color selection key 156 for selecting the copy color (for example, black, red, blue, green), and the selected color. Color display units 157 to 160 for displaying information, a liquid crystal display unit 161 for displaying operating status, etc., a density setting unit 162 for setting copy density, and the like are provided. In the liquid crystal display section 161, 163 is a symbol for indicating that copying is possible, 164 is a symbol for indicating that copying is not possible, and 165 is for developing device 10. This symbol indicates that there is no developer left in the hopper. Note that the color selection by the color selection key 156 can be alternately selected each time the color selection key 156 is pressed. That is, for example, if the first developing device 321 is red and the second developing device 322 is black, when the power is turned on, the black copy mode is automatically selected, the second developing device 322 is selected, and the color display 157 is displayed. Light. When the color selection key 156 is pressed in this state, the red copy mode is set, the first developing device 321 is selected, and the color display 158 lights up. If the color selection key 156 is pressed again in this state, the black copy mode is set again. In this way, each time the color selection key 156 is pressed, the black copy mode and the red copy mode can be selected alternately.

FIG. 15 shows the overall control circuit.

That is, 171 is a microcomputer (hereinafter simply referred to as microcomputer) as a main control section, which controls the entire copying machine. Inputs to the microcomputer 171 include, via an input interface circuit 172, input switches 173 such as various keys on the operation panel, other various switches necessary for copying operations, sensors 174, and the developing device of the first developing unit 321. Agent concentration detector 421 and developer remaining amount detection device 1171. The developer concentration detector 422 of the second developing device 322, the developer remaining amount detector 1172, the cover opening/closing detector 135, and the like are connected.

In addition, a memory device @175 is connected to the microcomputer 171, and this memory device 175 is connected to a backup power source such as a battery. 176. On the other hand, an output interface circuit 177 is connected to the output of the microcomputer 171.
Display devices 178 such as various indicators and display sections of the operation panel, pole position switching solenoids 109, 109 of the first developer 321 and second developer 322,
an integrated time meter 1391 for the reversible motor 63 and the first developing device 321; The integrated time meter 1392 of the second developing device 322, the developing bias power supply 179, the charging charge 180 of the charging charger 8, the transfer charge 1181 of the transfer charger 11. What is the peeling amount of the peeling charger 12? ! ! 1
82, the static elimination lamp 14, the developer-free indicator 14;
01.1402, the main motor 28, other various solenoids 183, a document table driving device [184 for driving the document table 2, an exposure lamp control circuit 185, etc.] are connected. The exposure lamp control circuit 185 controls the exposure lamp 2
The exposure lamp 22 is controlled according to an output signal from an automatic exposure sensor 186 that detects light from the exposure lamp 2 and a signal from the microcomputer 171.

Note that the first developing device 321 and the second developing device 322 each have a developing device presence/absence signal generating means 18 that indicates the presence or absence of the developing device.
7t, 1872 and identification information generating means 188s and 18B2 for generating an identification code unique to the developer (which also represents the color of the stored developer), and the signals from these and the li-specific code are also input to the input interface circuit. 17
2 to the microcomputer 171. The developing device presence/absence signal generating means 1871, 1872 and the identification information generating means 188s, 1882 each utilize a developing device connector for electrically connecting the developing device to the control circuit, as shown in FIG. It is designed to generate a signal and an identification code. That is, 191 is the above-mentioned connector, which is composed of a jack 192 and a plug 193. The jack 192 is provided on the developer side, and the plug 193
is connected to the control circuit shown in FIG. 15 via a cable.

In the jack 192, the terminal 1941 is set as a common, and a developing device presence/absence signal is generated by connecting this terminal 1941 and a terminal 1945, and also connecting the terminal 1941 and terminals 1942 to 1944 according to the developing device. By doing this, a 3-bit identification code is generated. On the other hand, in the plug 193, the terminal 195! is grounded on the control circuit side, and the terminals 1952 to 1955 are connected to the input interface circuit 172.
Connect to. However, jack 192 and plug 193
When connected, each terminal is connected correspondingly.
As a result, a 3-bit identification code corresponding to the connection state of the terminals in the jack 192 is obtained from the terminals 1952 to 1954 of the plug 193, and a developing device presence signal is obtained from the terminal 1955. Therefore, if the jack 192 and the plug 193 are not connected,
Since the developing device presence signal is not obtained from the terminal 1955 of the plug 193, it can be determined that there is no developing device (the developing device is not installed).

Further, the storage device 175 is, for example, a CM O8RA
M (random access memory) is used as a counter to count the number of copies (number of copying operations), and its details will be explained below.

That is, in this embodiment, for example, a plurality of separate developing sheet number counters for counting the number of sheets for each developing device and one total sheet number counter for counting the total number of sheets are provided, and these counters are provided for each developing device. They are selected by addressing according to their identification codes, and count data is stored in each one. The count data of each of the sheet number counters is composed of, for example, 4 pips 1-.times.5, and is stored in a BCD code. Further, the count data of the total number counter is composed of, for example, 4 bits x 6, and is stored in a BCD code.

Next, the operation in the above configuration will be explained. First, the operation when the power is turned on will be explained using the flowchart shown in FIG. When the power is turned on, the process proceeds to step A1. In step A1, the second developing device 322 containing black developer as a reference color is selected, and the automatic n-light mode is selected, and the process proceeds to step A2. In step A2, the heater lamp of the heat roller 19 is turned on, and the process proceeds to step A3. In step A3, the pole position switching solenoid 109 of the second developing device 322 is turned off and the reversible motor 63 is reversed, and the process proceeds to step A4. In step A4, the reversible motor 63 is stopped, and the process proceeds to step A5.

In step A5, the pole position switching solenoid 109 of the first developing device 321 is turned off, and the reversible motor 63 is turned off.
Turn forward and proceed to step 86. In step 86, the reversible motor 63 is stopped, and the process proceeds to step A7. In this way, when NR is input, steps A3 to A
7, the second developing device 322 and the first developing device 321 are operated in order to remove the developer on each of the developing rollers 31t, 3.12. Next, in step A7, the main motor 28 is turned on for a certain period of time, and the process proceeds to step 88. In step 88, it is checked whether or not the warming up of one heat roller is completed, and if it is completed, the symbol 163 for indicating that copying is possible on the operation panel is lit and the printer enters the standby state.
At step A9, key operations on the operation panel are accepted.

Next, the process proceeds to step A10, and it is checked whether or not the interrupt key 152 has been turned on. If it has not been turned on, the process proceeds to step A11, and if it has been turned on, the process proceeds to step A12. In step AI2, it is checked whether the current mode is interrupt mode, and if it is not interrupt mode, step A13 is performed.
Proceed to. In step A13, the copy conditions immediately before the interrupt key 152 is turned on, that is, the copy density, copy color, and set number of copies, are saved, and the second developer and first developer 322 containing black developer are saved, and the automatic exposure mode, set the number of copies to 1j, set the interrupt mode, and proceed to step A14.In this way, when the interrupt mode is set, the previous copy conditions are saved and the standard This is to switch to the black copy mode as the color.Next, in step A14, the interrupt display 153 on the operation panel is turned on, and the process proceeds to step A11.On the other hand, if the mode is in the interrupt mode in step A12, Proceed to step A15. In step A15, the copy conditions saved in step A13 are restored, and
The selection of the developer and exposure mode is returned to the selection state immediately before starting the interrupt mode, the interrupt mode is canceled, and step A1
Proceed to step 6. In step A16, the interrupt indicator 153 on the operation panel is turned off, and the process proceeds to step A11.

In step A11, it is checked whether the second developing device 322 is installed based on the developing device presence/absence signal from the second developing device 322, and if it is not installed, the process advances to step A17. In step A17, it is checked whether or not the first developing device 321 is installed based on the developing device presence/absence signal from the first developing device 321. If the first developing device 321 is not installed, step A17 is performed.
Proceed to step 18. In step A18, the color indicators 157 to 160 and the copy permission display symbol 163 on the operation panel are displayed.
turn off and return to standby mode.

In this way, the first developing device 321 and the second developing device 32
2 is not installed at all, color indicators 157 to 16
This prohibits the display of colors based on 0. On the other hand, in step A11, if the second phenomenon device 322 is attached, the process advances to step A19. In step A19, it is checked whether the first developing device 321 is installed, and if it is installed, the process advances to step A20. In step A20, it is checked whether the color selection key 156 is turned on, and if it is turned on, the process advances to step A21. In step A21, it is checked whether the second developing device 322 is currently selected, and if it is not selected, the process advances to step A22. In step A22, the second current □□□ device 322 is selected, and the process proceeds to step A23. If the first developing device 321 is not installed in step A19, step A20. Jump to step A21 and proceed to step A22. Further, in step A20 above,
If the color selection key 156 is not turned on, step A
21. Jump to A22 and proceed to step A23. On the other hand, if the first developing device 321 is installed in step A17, or if the second developing device 322 is selected in step A21, step A
Proceed to step 24. In step A24, the first developing device 32t is selected, and the process proceeds to step A23. In this manner, if the first developing device 321 and/or the second developing device 322 is not installed, selection of that developing device is prohibited. In step A23, the color of the selected developer is displayed.

That is, the color of the stored developer is determined based on the identification code output from the selected developer, and a color indicator on the operation panel corresponding to the determined color is turned on. For example, if the discrimination color is black, the color display 157 is turned on, and if the discrimination color is red, the color display 158 is turned on.

After color display is performed in this way, the process advances to step A25. In step A25, the developer remaining amount detection device @1171.117
2, the first and second developing units 321 and 322
It is checked which of the developing devices is out of developer or not, and if neither is out of developer, the process advances to step A26. In step A26, the first and second developing devices 321, 32
2, each of the developer-free indicators 1401 and 1402 is turned off.
Proceed to step A27. On the other hand, in step A25, if one of the developing devices is out of developer, the process proceeds to step A28. In step A28, it is checked whether or not the hopper cover 131 of the developing device 10 is closed based on the signal from the cover opening/closing detection device 135. If it is closed, the process advances to step A26, and if it is not closed, step A28 is performed.
Proceed to step 29.

In step A29, the developer empty indicator 1401 or 1402 of the corresponding developing device (developing device without developer) is turned on, and the process advances to step A27. In this way, the first and second
Developer G1. If G2 is missing, its top opening 132
1. No developer indicator 14 provided near 1322
01.1402 is lit. At this time, if the hopper cover 131 is closed, the developer empty indicator 1
401.1402 does not light up, but lights up only when opened. In step A27, it is checked whether the developing device selected at this time is out of developer, and if not, the process proceeds to step A30. In step A30, the symbol 165 for displaying the absence of developer on the operation panel is turned off, and the process proceeds to step A31. On the other hand, in step A27, if the selected developing device is out of developer, the process proceeds to step A32. Step A32
Now, the symbol 165 for displaying no developer on the operation panel.
is turned on and the process proceeds to step A31. In this way, only when the selected developing device runs out of developer, this is displayed on the operation panel.

In step A31, it is checked whether or not there is an abnormality in the copying machine. If there is an abnormality, the abnormality is dealt with, and if there is no abnormality, the process advances to step A33.

In step A33, it is checked whether or not it is the manual paper feeding mode using the single manual feeding table 6, and if it is not the manual paper feeding mode, the process proceeds to step A34.

In step A34, it is checked whether or not there is paper P1 in the paper feed cassette 3. If there is not, the process returns to the standby state, and if there is, the process proceeds to step A35. On the other hand, the above step A
33, if the manual paper feed mode is selected, step A3 is selected.
4 and proceed to step A35. Step A3
In step 5, it is checked whether the developer has been attached or detached based on the developer presence/absence signals from the first and second developer units 321 and 322, and if the developer has been attached or detached, the process advances to step A36. Step A
At step 36, it is checked based on the signal from the cover opening/closing detection device 135 whether or not the developing device is securely attached. In this case, hippo! Opening/closing detection device [135 is the hopper cover 131
If it detects a blank state, it is determined that it is attached. When it is determined that the developing device is attached, the process advances to step A37. Step A
At step 37, the developer on the sleeve of the detached developing device is removed by performing the above-described operations, and the developing device returns to the standby state. In this way, when a developing device is attached or detached while the power is on, the device operates to remove the developer on the sleeve of the detached developing device after the developing device is securely attached. It is. On the other hand, if the developing device is not attached or detached in step A35, the process advances to step A38. In step A38, it is checked whether or not the copy key 151 on the operation panel is turned on. If it is turned on, the process proceeds to a copying operation to be described later. If it is not turned on, the process proceeds to step A39. In step A39, it is checked whether or not any key operation has been performed on the operation panel for a certain period of time. If any operation has been performed, the process returns to the standby state, and if no operation has been performed, the process advances to step A40. In step A40, it is checked whether or not the current interrupt mode is set, and if it is not the interrupt mode, the process proceeds to step A41. In step A41, the M2 developer 322 containing black developer and the automatic exposure mode are selected, and the constant number of copies 82 is set to 1J, and the state returns to standby. In this way, after the normal copying operation is completed, If no operation is performed for a certain period of time, the mode is switched to the black copying mode as the reference color and the automatic exposure mode.On the other hand, if it is the interrupt mode in step A40, the process advances to step A42.In step A42,
In addition to restoring the copy conditions saved when setting the interrupt/mode, the interrupt indicator 153 on the operation panel is turned off.
Return to standby state. In this way, if no operation is performed for a certain period of time after interrupt copying is performed in interrupt mode, the state is returned to the state immediately before starting interrupt mode.

Next, the copying operation will be explained using the flowchart shown in FIG. When the copy key 151 on the operation panel is turned on, the process advances to step B1.

In step B1, the pole position switching solenoid 109 of the selected developing device is turned on, and the process proceeds to step B2. In step B2, the reversible motor 63 is rotated in the direction of the selected developing device, and the process proceeds to step B3. In step B3, the blade solenoid 29 of the cleaning device 13, the static elimination lamp 14, the main motor 28, the transfer power source 181 (transfer charger 11), and the stripping power source 182 (peeling circular charger 12)
Then, the developing bias power supply 179 is turned on, and the process proceeds to step B4. In step B4, the paper feeding operation from the paper feeding cassette 3 is started, and the process proceeds to step B5. In step B5, it is checked whether or not the document table 2 is in the normal position. If it is not in the normal position, step B6 is selected and the document table 2 is returned to the normal position. When the document table 2 is returned to the normal position, the process proceeds to step B7. In step B7, the exposure lamp 22 is turned on, and in step B8
Proceed to. In step B8, the charging electric fi 180 (charging device 8) is turned on to start charging the photosensitive drum 7, and at the same time, the document table 2 is advanced to start scanning the document, and the process proceeds to step B9. In step B9, the registration roller 18 is rotated to send the paper P1 to the image transfer section 16,
Proceed to step B10.

In step BIO, the sheet number display section 155 on the operation panel
"1" is subtracted from the display content of the storage device 175.
1 is added to the total number of sheets counter and the number of sheets counter of the selected developing device, and the process proceeds to step B11. In step B11, the charging power source 180 is turned off to stop charging the photosensitive drum 7, and the process proceeds to step B12. In step B12, the exposure lamp 22 is turned off, and the process proceeds to step B13. In step B13, the document table 2 is moved backward, and the process proceeds to step B14. In step B14, it is checked whether the document table 2 has returned to the normal position, and if it has returned to the normal position, the process proceeds to step B15. In step B15, the rotation of the registration roller 18 is stopped, and the backward movement of the document table 2 is also stopped, and the process proceeds to step B16. Step B
In step 16, it is checked whether or not the set number of copies have been completed, and if the copying has been completed, the process advances to step 817. In step B17, it is checked based on the signal from the developer concentration detector of the selected developer whether the developer concentration in the selected developer is at least the lower limit concentration level, and if it is at least the lower limit concentration level, step 818 If the concentration level is not higher than the lower limit concentration level, the process advances to step B19. In step 819, it is checked whether or not the developer has been continuously replenished for a certain period of time. If not, the process returns to step B17 and the above operation is repeated. If the developer has been continuously replenished for a certain period of time, step 8
Proceed to step 18. In other words, in automatic developer concentration control,
It has an appropriate concentration level and a lower limit concentration level for not changing the flow characteristics of the developer, and drives the developing device until the developer concentration reaches the lower limit concentration level at the end of the copying operation,
It continues to replenish the developer. Next, step 81
In step 8, the pole position switching solenoid 109 is turned off and the process proceeds to step B20. In step 820, the reversible motor 63 is stopped, and the process proceeds to step B21. in this way,
When the copying operation is completed, the polar position switching solenoid 109 is turned off and the dust-bashable motor 63 is stopped, thereby removing the developer on the developing roller of the selected (that is, the currently used) developing device. It is. Next, in step B21, the blade solenoid 29, the main motor 28, the static elimination lamp 14, the transfer voltage 1181, the stripping power source 182, and the developing bias power source 179 are turned off, and the process returns to the standby state.

On the other hand, if the set number of copies have not been completed in step B16, the process advances to step B22. Step B
In step B22, the life of the developer is checked by checking whether the value of the number counter for each development in the storage device 175 is a predetermined value set in advance, and if the life has not expired, step B23 Proceed to. In step B23, the color change request flag, which will be described later, is set to "1".
It is checked whether there is a color change request by checking whether the flag is
) Returning to step B4, the above-described operation is repeated, and if there is a color change request (flag=1), the process proceeds to step B24. In step B24, the selection of the developing device is changed, and the process proceeds to step B25.

In step B25, the pole position switching solenoid of the previously selected developer is turned off, and step B261. :move on.

In step B26, the 6 reversible motor 63 is stopped, and the process returns to step B1 to repeat the above-described operation. In this manner, when there is a request to change the selection of a developer during a copying operation, the developer to be used is switched at least after the development of the image being copied is completed. On the other hand, in step B22, if the developer has reached the end of its life, the process proceeds to step 827. In step B27, it is checked whether there is another developer of the same color. If not, the process returns to step B4 and the above-described operation is repeated. If there is another developer of the same color, the process advances to step B28. In step 828, the developer of the same color is selected, and the process proceeds to step 825. In this manner, when the developer in the developing device in use reaches the end of its life, if there is another developing device, that is, a developing device containing developer of the same color, it is preferentially switched to that developing device.

Next, interrupt processing will be explained using the flowchart shown in FIG. This interrupt processing is set to be repeated at predetermined intervals. Once the interrupt processing is started, the process advances to step C1.

In step C1, it is checked whether the reversible motor 63 is rotating (the developing device is in operation), and if it is rotating, the process advances to step C2. In step C2, the integrated time meter 1391 or 1392 of the selected developing device is energized, and the process proceeds to step C3. In step C3, it is checked whether the A flag is set to 1, and if it is not set to IIIII, the process proceeds to step C4. In step C4, timer A starts counting, and the process proceeds to step C5.

In step C5, it is checked whether or not the timer A has counted 5 seconds, and if the timer A has counted 5 seconds, step C
Proceed to step 6. In step C6, the flag is set to 111 +1.
is set, and the process proceeds to step C7. In step C5, if 5 seconds have not been counted, step C6 is jumped and the process proceeds to step C7. On the other hand, if the flag is set to 1' in step C3, the process proceeds to step C8. In step C8, it is checked whether the developer concentration of the selected developer is lower than a predetermined value based on the signal from the developer concentration detector 421 or 422 of the selected developer. , if it is low, proceed to step C9. In step C9, a developer replenishment operation is performed by driving the developer replenishment roller 52 or 522 of the selected developing device, and the process proceeds to step C7. In step C8, if the value is higher than the predetermined value, step C9 is jumped and the process proceeds to step C7. In this way, after starting the copying operation, the magnetic rolls 43t, 432
After a predetermined period of time (for example, from about 5 sec to the developer concentration sensor 421.422 after the developer supply to the developer concentration sensor 421.422 is stabilized)
The density is checked based on the output of 422.

In step C7, it is checked whether the color selection key 156 on the operation panel is turned on, and if it is turned on, the process advances to step C10. In step C10, the color change request flag is set to '1', and the process proceeds to step C11. In step C7, if the color selection key 156 is not turned on, step C10 is skipped and step C
Proceed to step 11.

On the other hand, in step C1, the reversible motor 6
If 3 is not rotating, the process advances to step C12. In step C12, the A flag is set to 11014, timer 8 is reset, and the cumulative time counter 1391 is set to 11014.
Alternatively, the power supply to 1392 is turned off and the process proceeds to step C11. In step C11, it is checked whether there is a request to display the total number of copies (entered in code using the numeric keypad 154 on the operation panel), and if there is a request to display, the process advances to step C13. In step C13, the storage device 175
The content of the total number of sheets counter is displayed on the number of sheets display section 155 on the operation panel, and the process proceeds to step C14. In step C11, if there is no request to display the total number of copies, the process advances to step C'15. In step C15, it is checked whether there is a request to display the number of copies made by the first developing device 321 (inputted in code using the numeric keypad 154), and if there is a request to display, the process proceeds to step C16.

In step C16, the first developing device 3 in the storage device 175
The contents of the sheet number counter corresponding to No. 21 are displayed in the sheet number display section 155.
is displayed, and the process proceeds to step C14.

In step C15, if there is no display request, the process advances to step Cj7. In step C17, the second developing device 3
22 to display the number of copies made (numeric keypad 15)
If there is a display request, the process advances to step C18. In step 018, the contents of the sheet number counter corresponding to the second developing device 322 in the storage device 175 are displayed on the sheet number display section 155, and the process proceeds to step C14. In step C17, if there is no display request, the process advances to step C19.

In step C19, the normal number of copies is displayed on the number display section 155, and the process proceeds to step CI4. In step C14, a request for clearing the number of copies for each developer (on the numeric keypad 154)
If there is no clear request, the interrupt process ends here, and if there is a clear request, the process proceeds to step C20. In step C20, the contents of the sheet number counter corresponding to the designated developer in the storage device 175 are cleared, and the interrupt processing is ended.

With the configuration described above, after the developer is driven, the supply of developer onto the developing roller (sleeve) is started, and then the flow of developer to the detection surface of the developer temperature detector is controlled. Since the developer concentration is determined based on the output of the developer concentration detector several seconds after it stabilizes (approximately 5 seconds in the example), the developer concentration can be accurately detected, resulting in high precision. Good concentration control of the developer becomes possible. Therefore, a clear copy image can always be obtained. Furthermore, at the end of the copying operation, the developer is driven until the output of the developer concentration detector reaches the preset lower limit concentration level, and developer replenishment is continued, so the flow characteristics of the developer can be prevented from changing. . Therefore, more accurate concentration detection and highly accurate concentration control are possible.

In the above embodiment, a case was explained in which the present invention is applied to a monochromatic color copying machine, but the present invention is not limited to this. The present invention can be applied to any image forming apparatus that forms an image using a developing device.

[Effects of the Invention] As detailed above, the present invention provides an image forming apparatus that can accurately detect the concentration of the developer in the developing device and can control the concentration of the developer with high precision. can.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which Fig. 1 is a schematic configuration diagram of a color copy view, Fig. 2 is a schematic vertical side view of a developing device, and Fig. 3 shows different operating states of the developing device. 4 to 6 show the configuration of the driving force transmission system, FIG. 4 is a front view showing the meshing state of the gear group, and FIG. 5 is a cross-sectional view showing the developed state. 6 is a sectional view showing the state of driving force transmission to the drive gear, FIG. 7 is a partially sectional plan view of the magnetic roll driving means, and FIG. 8 is a side view of the magnetic roll driving means. 9 is an explanatory diagram showing the operating state of the magnetic roll drive means, FIG. 10 is a schematic perspective view of the developing device section, FIG. 11 is a plan view showing the top surface of each developing device, and FIG.
Figure 2 is a front view showing the fixing structure of the prototype, Figure 13 is an explanatory diagram showing the relationship between the handle and the hook, Figure 14 is a plan view of the operation panel, and Figure 15 is the overall control circuit. FIG. 16 is an explanatory diagram for explaining the developer presence/absence signal generation means and identification information generation means; FIG. 17 is a block diagram schematically showing the
18 is a flowchart for explaining the operation when the power is turned on, FIG. 18 is a flowchart for explaining the copying operation, and FIG. 19 is a flowchart for explaining the interrupt processing operation. Pl, P2...paper, 2...document stand, 7...photosensitive drum, 10...developing device, 311.312...
Developing roller (developer conveying means), 321, 322...
Developing device, 341.342...Developer supply section, 421.
422...Developer concentration detector, 441.442...
Sleeve, 521.522...Developer supply roller, 5
4...Scraper (guide member), 171...Microcomputer. Applicant's agent Patent attorney Takehiko Suzue Figure 7 Figure 8 1υS Figure 9 (a) (b) Figure 10 Figure 11 (a) (b) Ijj2 1Jt52 Figure 16 Figure 17 Figure 17 (C ) Figure 18 Figure 19 (a)

Claims (5)

[Claims] (1) In an image forming apparatus that performs image formation using a developing device that is equipped with a developer conveying means that conveys the developer to a developing area, the developer that detects the concentration of the developer contained in the developing device a concentration detecting means, a time measuring means for measuring time when the developing device is driven, a concentration determining means for determining the developer concentration based on the output of the developer concentration detecting means when the time measuring means measures a predetermined time; An image forming apparatus comprising: a developer replenishing means for replenishing the developer to the developing device according to the determination result of the concentration determining means. (2) The developer concentration detection means includes a developer concentration detector whose detection surface is installed vertically in the developing device, and a developer concentration detector whose detection surface is placed on the developer conveying means along the detection surface of the developer concentration detector. The image forming apparatus according to claim 1, further comprising a guide member that guides the developer so that it falls. (3) Image formation according to claim 2, wherein the developer concentration detector detects the concentration of the developer by magnetically detecting a change in the 'S magnetic property of the developer. Device. (4) The developer replenishing means replenishes the developer until the output of the developer concentration detecting means reaches a predetermined level at the end of the image forming operation. The image forming apparatus according to item 1. (5) The image forming apparatus according to claim 1, wherein the developer conveying means is a developing row that conveys the developer while rotating.