JP2624699B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention] (Field of Industrial Application) The present invention relates to an image forming apparatus applied to, for example, a laser printer, an electronic copier, and the like.

(Prior Art) In recent years, a charged photosensitive member (image carrier) is irradiated with laser light corresponding to an image signal to form an electrostatic latent image, and the latent image is developed by a developing device (developing means). A laser printer capable of forming an image by transferring a toner image (developer image) formed on the image support to an image support has been put to practical use.

By the way, some laser printers of this type include an automatic toner device that automatically replenishes toner in accordance with a change in the density of toner consumed by a toner image forming operation, for example. This automatic toner device automatically detects a decrease in toner concentration in a developer and performs a toner replenishing operation on the developing device from a toner cartridge (supply means). That is, in the state of the reference toner density, the voltage value by the toner density detector (density detector) provided in the developing device is set as a reference (voltage) value. When the voltage value increases and reaches a certain voltage value, toner is supplied from the toner cartridge. Then, when the toner is agitated and the toner concentration becomes the reference value, the toner supply is stopped.

A cleaning device (removal device) for removing toner remaining on the photoreceptor after transferring the toner image to the image support; and a toner return device for returning the toner collected by the cleaning device to the developing device for reuse. (Conveying means) have been developed. As described above, in the laser printer in which the toner collected by the cleaning device is returned to the developing device and is reused, the consumption of the toner is small, and it is extremely economical. Maintenance and the like are easy, for example, the number of times can be reduced, and the labor involved in the disposal of the toner collected by the cleaning device can be reduced.

However, in a laser printer provided with an automatic toner device and a toner return unit, when setting a reference value for the toner concentration of the developing device (at the time of initialization)
Then, the toner returning means is driven to return the toner from the cleaning device to the developing device.
The toner collected from the cleaning device and the toner in the developing device are mixed, and the toner concentration in the developing device becomes unstable. The voltage value from the toner concentration detector fluctuates and the reference value is incorrect. There was a disadvantage that it would be.

(Problems to be Solved by the Invention) According to the present invention, when a reference value for the toner density of the developing device is set, the toner density in the developing device is unstable in the conventional device that drives the toner return means. This eliminates the disadvantage that the reading of the reference value by the toner concentration detector is inaccurate because the toner concentration detector is in an inaccurate state. It is an object of the present invention to provide an image forming apparatus capable of controlling a developer concentration in a developing unit correctly and obtaining a high-quality image.

[Structure of the Invention] (Means for Solving the Problems) In the image forming apparatus of the present invention, an image forming means for forming an electrostatic latent image on an image carrier is detachably configured,
A developing device having a developer accommodating portion for accommodating a developer and developing the electrostatic latent image on the image carrier formed by the image forming means by supplying the developer from the developer accommodating portion; Means, a density detecting means provided in the developing means, for detecting the density of the developer in the developer accommodating portion,
New and old detecting means for detecting the new and old of the developing means, and referring to the detection result of the density detecting means when the new and old detecting means detects that the developing means is new,
Setting means for setting the developer density detected at this time as a reference density; comparing the reference density set by the setting means with the density of the developer detected by the detection means; When the density is lower than the reference density, a replenishing unit that replenishes the developer accommodating portion of the developing unit with the developer, and the developer image on the image carrier that is developed by the developing unit. Transfer means for transferring onto a recording medium, removing means for removing the developer remaining on the image carrier after being transferred onto the recording medium by the transfer means, from the image carrier,
Transport means for transporting the developer removed by the removing means at least partially to the developer accommodating portion of the developing means, and setting operation of the reference density by the setting means And a prohibition unit for prohibiting the developer conveyance operation of the conveyance unit during the execution of the operation.

(Operation) The present invention is to prevent the developer from being conveyed by the removing unit and to prevent the developer from being mixed in when the reference value for the developer concentration of the developing unit is set. The reading is performed in a state where the density is stable.

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

FIG. 4 and FIG. 5 show a laser printer as an image forming apparatus of the present invention, which has the following configuration. That is, in the figure, 1 is a laser printer, 5
Denotes a printer main body of the laser printer 1. The rear portion of the upper surface of the printer main body 5 is one step higher, and a corrugation 6 as a paper discharge portion is formed at the center of the upper surface. A paper discharge tray 8 movably supported by a jogger 7 is mounted in the recess 6, and an operation panel display section 9 and an operation panel switch section 10 are provided on the right side of the recess 6.
On the left side, three IC card insertion slots 11 are provided.

Further, a paper output tray 12 is provided on the front side of the printer body 5.
However, a manual feed tray 13 is mounted on the rear side.

A drum-shaped photoreceptor 15 as an image carrier is provided at a substantially central portion of the printer body 5, and a charging device 16, a laser optical system 17, Developing device (developing unit) as developing means
18, transfer device 19, peeling device 20, cleaning device (photoreceptor unit) 21 as cleaner means, and static eliminator
22 are sequentially arranged.

Further, in the printer main body 5, a photosensitive device 15 and a transfer device 19 are provided.
An image support transporting path 24 extending in the forward direction through an image transfer unit 23 is formed between the paper transferring cassette 23 and a paper feed roller 28 and a transfer roller 29 from a paper feed cassette 25 housed in the bottom of the printer body 5. The paper P automatically fed through the printer and the paper P manually supplied from the manual tray 13 are guided to the image transfer unit 23.

An aligning roller pair 30 is disposed upstream of the image transfer section 23 of the image support transport path 24, and a fixing device (fuser unit) 31, a discharge selector 32 and a discharge roller pair 33 are disposed downstream. Is arranged.

At the end of the image support transport path 24, a branch transport path 35 having a pair of paper discharge rollers 34 for guiding the paper P sorted by the paper discharge selector 32 to the concave portion 6 as a paper discharge section.
Are formed.

In FIG. 4, 40 is a lower cover, 41 is a front cover,
42 is an upper cover, 43 is an openable right cover (door), 44 is a left cover, 45 is a right cover open / close lever, 46 is an upper unit open / close lever, and 47, 48 ..., 49 shown in FIG. It is a control board which comprises a control part.

Thus, in the image forming operation, the photosensitive member 15 is driven and is uniformly charged by the operation of the charging device 16,
Next, an exposure corresponding to an image signal is performed on the photoconductor 15 by the laser optical system 17 to form an electrostatic latent image. The electrostatic latent image on the photoconductor 15 is developed by using a two-component developer D including a toner X and a carrier Y.
The image is developed by 18 and sent to the image transfer unit 23 side as a developer image.

On the other hand, in synchronization with this developer image forming operation,
The paper P taken out from the paper feed tray 25 or the paper P manually fed from the manual feed tray 13 is fed through the pair of aligning rollers 30, and the developer image previously formed on the photoconductor 15 is transferred by the transfer device 19. The image is transferred to paper P.
Next, the paper P is peeled off from the photoconductor 15 by the peeling device 20, passes through the image support transport path 24, and is sent to the fixing device 31. After passing through this, the developer image is fused and fixed on the paper P, and then the discharge direction is sorted by the paper discharge selector 32 and discharged onto the upper paper discharge tray 8 or the front paper discharge tray 12. Is done.

The photoconductor 15 after the transfer of the developer image onto the sheet P
In the state, the remaining toner remaining on the surface is cleaned by the cleaning device 21, and the residual image is erased by the charge removing device 22, so that the next copying operation can be performed.

The photosensitive member 15, the cleaning device 21, and the developing device 18 shown in FIG. 6 are, as shown in FIG. 15 and FIG.
Guides slidably supported via slide rails 50 and 50 by grip handles 87 and 88, respectively, with a shaft portion 201 extending the center axis of the developing roller 59 at both ends and a shaft 202 of the photoconductor 15 as a guide. The right cover 43 is mounted on the frame 51 as shown in FIGS. 7 and 14.
By pulling out the guide frame 51 in a state where is opened, these can be pulled out to the right part of the printer main body 5.

Further, the photoconductor 15 and the cleaning device 21 are unitized (photoconductor unit), and are configured to be detachable integrally with the guide frame 51 and the developing device 18 alone. The developing device 18 is mounted horizontally with respect to the printer main body 5 and can be checked in a state where the upper unit is opened by the upper unit opening / closing lever 46 (see FIG. 5). Level
A printer 203 is attached, and the printer main body 5 and the developing device 18 are configured to be corrected by a rubber foot 160 as needed to maintain a horizontal state.

The developing device 18 has a configuration as shown in detail in FIG. That is, the developing device 18 includes a developing mechanism unit 55 and a developer stirring unit 56.

The developing mechanism 55 includes a developing roller 59 (see FIG. 21) disposed opposite the opening 58 of the developing device main body 57, and a developer magnetic brush D ′ formed on the surface of the developing roller 59.
A doctor 61 provided upstream of the developing unit 60 to regulate the thickness of the developer magnetic brush D ', and a developing roller provided downstream of the developing unit 60 And a scraper 62 for peeling off the developer magnetic brush D 'formed on the surface of the developer 59 and guiding it to the developer stirring section 56.

Further, the developer stirring section 56 includes first and second developer stirring bodies 64 and 65 (developer conveying augers) housed in a developer housing section 63 formed behind the arrangement section of the developing roller 59. (See FIG. 17). The developing roller 59, as shown in FIG. 21, a magnetic roll 59a having a plurality of magnetic pole parts 89,
A non-magnetic sleeve 59b is fitted around the magnetic roll 59a and rotates clockwise in the figure.

Further, a toner receiving portion 66 as a developer receiving portion is formed at a position opposite to the developer stirring portion 56 of the developing device main body 57, and a toner as a developer replenishing cartridge of a developer replenishing mechanism 150 described later. Cartridge (supply means)
The toner X supplied from the cleaning device 21 and the toner X returned from the cleaning device 21 are received via a toner return device 68 serving as a developer return device.

A toner concentration detector 70 as a developer concentration detector for detecting the developer concentration is provided at a position facing the scraper 62.
And a toner supply shaft 71 as a developer supply member incorporated in the toner cartridge 67 based on a voltage conversion value as a detection signal from the toner concentration detector 70.
(See FIG. 8) is driven as needed (by driving separately from the printer main body 5).

Thus, on the surface of the non-magnetic sleeve 59b, the developer D rises due to the lines of magnetic force generated from the respective magnetic pole portions and is attracted in a brush shape to form a developer magnetic brush D '. The toner X in the magnetic brush D 'is sequentially conveyed to the developing unit 60 by the rotation of the sleeve 59b, and the toner X
The toner adheres to the upper electrostatic latent image and is developed.

On the other hand, the developer stirring body 6 provided in the developer accommodating section 63
By the rotation of 4, 65, the developer D is agitated, and the toner X and the carrier Y are frictionally charged well.

The structure of the developer stirring bodies 64 and 65 will be described with reference to FIGS. 17 and 18. FIG. 17 shows the developer D in the developer container 63.
Is shown. FIG. 18 shows a developer stirring body.
Only 64 and 65 are shown.

That is, the toner X supplied from the toner receiving unit 66
Is sent to the stirring body 64 side by the plate-shaped U-turn blade 20, is immediately conveyed by the conveying blade 205, is sufficiently stirred by the stirring blade 69 on the way, and is flat-plated U-turn blade 204 '.
To the stirring body 65 side. After that, the flow of the developer D is changed on the blade 74 having a small outer shape at the center. Utilizing this flow, density detection described below is performed. The developer agitating bodies 64 and 65 are provided horizontally with respect to the developing device 18, that is, the developing unit, so that the transport of the developer D is not adversely affected (transfer abnormality due to the inclination). In the vicinity of the developer agitator 64 corresponding to the toner receiving section 66, in order to prevent delay in toner detection and toner jam, only the transport blade 205 is provided without providing the stirring blade 69. I have.

Here, the developer concentration detection and control will be described. First, as shown in FIG. 19, the developing device 18 is connected with a substrate 39 and a toner density detector 70 as means for recognizing the new or old device or the serial number of the device. The case of a new developing device 18 will be described. The developer D has a constant concentration in advance, and when it is mounted on the printer body 5,
Recognition of new or old is performed by the board 39, and only when the new is recognized, the use count in the main body 57 of the developing device 18 is reset in a storage device (memory) (not shown) of the printer main body 5. After that, the developer D
Only the drive of the printer 57 starts, and after about 2 minutes and 30 seconds when the flow of the developer D is stabilized, the voltage value converted into the voltage is read from the toner density detector 70 to the storage device (not shown) of the printer body 5. I will. The density control of the developing device 18 is started based on the read voltage value (reference value).

FIG. 22 shows a characteristic diagram of a toner density detector for performing density control. In this case, the horizontal axis represents the density, and the vertical axis represents the voltage value. Here, if the reference voltage V [V] with respect to the constant concentration A [%], and to affect the image if the concentration is the concentration A ₁ [%] or less reduced, the voltage to the concentration A '[%] When the value is around V '[V], a toner supply signal is output, and toner is supplied by the toner cartridge 67.
When the agitated and stable voltage value in the vicinity of V becomes close to V '[V], the toner supply is stopped.

In this way, the toner value is repeatedly
Even if the toner supply signal is output at V ₁ [V], the voltage value is V
When it does not return to [V], the supply shaft of the toner cartridge 67
Forcibly rotate 71. Still, the voltage value is V [V]
Is not displayed, "toner empty" indicating that the toner cartridge 67 is empty is displayed on the operation panel display section 9 of the printer body 5. At this time, the voltage value V ₁ [V] is
Assuming that V ₁ = a ₁ × V, a ₁ is an arbitrary constant.

Here, depending on the use conditions of the developing device 18 and the printer main body 5, the constant density A [%] is not the characteristic line O but the 23rd.
As shown in the figure, the characteristic lines P and Q may occur. At this time, if it is impossible to form a normal image because the characteristic diagram fluctuates greatly, a message indicating that the image cannot be used is displayed on the operation panel display section 9 of the printer body 5 as described above. The activation of the main body 5 is stopped.

In addition, when it is recognized that the fluctuation of the characteristic diagram a is small and that the density control is possible, the voltage value for the density control is the 23rd voltage.
In the figure, V ₂ = a ₂ × V ₂ ′ and V ₃ = a ₃ × V ₃ ′, respectively. At this time, a ₂ and a ₃ are arbitrary constants, and always have the concentration A ₁
Let [%] be the density for toner absence detection. As described above, the density control method is changed according to the read voltage value.

Next, when the use count of the developing device 18 reaches a certain count number, it is displayed on the operation panel display section 9 that the replacement time is near, and when the predetermined amount has been counted, the operation panel display section 9 should be replaced. At the same time, the toner X contained in the separately driven toner return means 68 attached to the cleaning device 21 and the right cover 43, which will be described later, is collected by the developing device 18 to be replaced. As a result, the toner X is not left in the cleaning device 21 and the toner return means 68, and after the toner X is collected in the developing device 18, the developing device 18 is replaced.

Further, even when the new developing device 18 is started without using the developing device 18 up to the replacement count for some reason, only the printer main body 5 is driven, and the toner return means 68 is not driven. Therefore, the cleaning device
21 has a temporary storage section 27 for the toner X in the cleaner device 2 and stores it in that portion. Then, two and a half minutes after the printer body 5 is driven, the converted voltage value is read into the printer body 5 and the density control is started. After the start of the density control, the carrier Y is counted by a certain count.
May change over time, making it difficult for the toner X to be transferred. For one toner supply signal, the number of rotations of the toner supply shaft 71 in the toner cartridge 67 is forcibly increased. The supply amount is changed.

The cleaning device 21 has a configuration as shown in FIG. That is, reference numeral 75 in the drawing denotes a cleaning device main body having an opening 76 at a portion facing the photoconductor 15, and the cleaning blade 77 is housed in the cleaning device main body 75.

The cleaning blade 77 is rotatable by a support shaft 78, and is held at its upper end by a blade holder 80 constantly urged counterclockwise in the state of FIG. 6 by a weight 79 as an urging body. The tip of the lower end is photoconductor 15
In a state of being pressed against the peripheral surface.

Then, the residual toner X adhered to the photoreceptor 15 is scraped off by the cleaning blade 77.

Also, a collecting blade is provided at the lower edge of the opening 76.
The cleaning blade 77 collects the toner X scraped off by the cleaning blade 77 into the cleaning device main body 75.

Further, a toner collecting auger 82 for transferring the toner X in the cleaning device main body 75 to a toner discharging portion 83 protruding outside to transfer the toner X in the cleaning device main body 75 to a toner returning device 68 as a developer returning device is provided at a bottom portion in the cleaning device main body 75. Is arranged.

As shown in FIG. 9, a toner discharge port 84 as a developer discharge port is formed on the lower surface of the toner discharge section 83, and the toner discharge port 84 has a multiple shutter, that is, a rotary shutter. The shutter 86 and the slide shutter 85 can be closed twice.

Also, as shown in FIGS. 6 and 20, elastic members 72 and 73 are provided at openings 58 of the developing device 18 at the image forming portions of the developing device 18 and the cleaning device 21 so that the developer D
(X <Y) is prevented from scattering. Also, the sixth
As shown in FIG. 14 and FIG. 14, the guide frame 51 is provided with a tray 200 for preventing the developer D (X <Y) from scattering when the developing device 18 and the cleaning device 21 are mounted. Thereby, the consumption amount of the toner X can be greatly reduced,
It is extremely economical, and the number of times of replenishment of the toner X from the toner cartridge 67 can be reduced, which facilitates maintenance. In addition, the toner supply amount is appropriate, a good developing operation can always be performed, and a cartridge can be formed.

Further, the developer unit and the photoreceptor unit having different lifespans can be freely bonded, and the developer unit and the photoreceptor unit can be replaced without any priorities.

On the other hand, as shown in FIG. 7 and FIG.
Inside, the toner return means 68 for returning the toner X collected by the cleaning device 21 to the developing device 18 is attached.

As shown in detail in FIGS. 10 and 11, the toner return means 68 includes a toner receiving portion (joining portion) 90 as a developer receiving portion and a toner discharging portion (joining portion) 91 as a developer discharging portion. And a toner transfer section 92 as a developer transfer section for transferring the toner X received in the toner receiving section 90 to the toner discharge section 91. When the right cover 43 is closed, the toner receiving portion 90 is located on the lower surface side of the toner discharging portion 83 of the cleaning device 21 and faces the toner discharging port 84, and the toner discharging portion 91 is
It is located above the developer accommodating section 63 and faces the toner receiving section 66.

The toner receiving section 90 has a toner receiving port 94 formed opposite to the toner discharging port 84 of the cleaning device 21 and a slide shutter 85 provided on the toner discharging portion 83 of the cleaning device 21 for pushing and opening. The shutter opening / closing portion 95 and a rotary shutter opening / closing gear 97 that meshes with a gear 96 integral with the rotary shutter 86 to rotate the rotary shutter 86 are arranged.

Further, a cartridge mounting portion 98 for mounting the toner cartridge 67 of the developer supply mechanism 150 is provided on the upper surface at a position corresponding to the toner discharging portion 91, and a toner discharging port 100 opened and closed by a rotary shutter 99 is provided on the lower surface side. Is formed.

As shown in FIG. 13, a slide shutter 1 for opening and closing the toner discharge port 100 is provided on the cartridge mounting portion 98.
01 is provided. The slide shutter 101 has an opening 102 for discharging toner and an engagement projection 103 protruding from an opening edge of the opening 102, and the toner cartridge 67 is mounted on the cartridge mounting section 98. Then, the engagement protrusion 103 engages with the engagement recess 105 formed on the lower surface side of the slide shutter 104 of the toner cartridge 67.

The engagement recess 105 has an opening 1 for toner supply.
06 is formed and is in communication with the opening 102, and the slide shutter 101 is automatically rotated by rotating a pinion 109 of an opening / closing mechanism including a rack 108 and a pinion 109 by driving means 107 described later. The opening 102 slides to a position facing the toner discharge port 100.

Further, the rotary shutter 99 is rotated by driving the gear 110 via the driving unit 107 to rotate and rotate the toner discharge port 1.
00 is opened.

Further, the toner transfer section 92 includes a communication pipe 111 that connects the toner receiving section 90 and the toner discharge section 91, and a communication pipe 1 connected to the communication pipe 111.
It has a spiral member 112 that is accommodated in the housing 11 and transports the toner X with rotation. The spiral member 112 is configured to rotate when the gear 113 is driven by the driving means 107.

Next, the driving means 107 of the toner returning means 68
This will be described with reference to FIG. 1 and FIG. In the drawing, reference numeral 114 denotes a motor as a drive source, and the driving force of the motor 114 is, as shown in FIG. 12, a first spring through a speed reduction mechanism including a first gear group 115 and a second gear group 116. The transmission is transmitted to a shaft 118 via a clutch (slip occurs when the motor 114 rotates in the reverse direction and interrupts the transmission of the driving force).

Further, a first driving force transmission system 130 for driving the slide shutter 101 via the shaft 118, a second driving force transmission system 13 for driving the rotary shutter 99, and a rotary shutter 86 of the cleaning device 21. Are transmitted to a third driving force transmission system 132 for driving the motor.

The first driving force transmission system 130 includes a spring clutch 1
The pinion 109 that meshes with a rack 108 integrated with the slide shutter 101 via 33 is driven,
The second driving force transmission system 131 includes a spring clutch 134
Also, the gear 110 integrated with the rotary shutter 99 is driven via a plurality of gear groups 135.

The third driving force transmission system 132 includes gears 136 and 137 meshing with each other, a spring clutch 138, bevel gears 139 and 140,
The power is transmitted to the rotary shutter opening / closing gear 97 via a pulley 141, a belt 142, and a pulley 143 in this order.

On the other hand, the gear 113 integrated with the spiral member 112 housed in the communication pipe 111 meshes with the gear 145 that is interlocked with the gear 144 of the first gear group 115 constituting the reduction mechanism via a one-way clutch 146. It is in a state.

When the motor 114 rotates in the forward direction, the shutters 85, 86, 99, and 101 open, and the spiral member 112 rotates to return the toner X.

When the motor 114 rotates in the reverse direction, the shutters 85, 86, 9
9, 101 is closed and the spiral member 112
Is stopped.

As shown in FIGS. 7 and 8, the right cover 43
The driving means 107 of the toner return means 68 and the toner replenishing mechanism 1
50, a guide member 122, a safety switch operating claw 123, a cover lock claw 124, a guide member 125 for positioning the photoconductor 15 and the developing device 18, and the like are attached.

Incidentally, reference numeral 190 shown in FIG.
Is a slide shutter that opens and closes. When the right cover 43 is closed, the slide shutter is pushed by the toner discharging section 91 to slide and open the toner receiving section 66. Reference numeral 191 denotes a handle for pulling out a slide rail 51 on which a unit device including the developing device 18, the photoconductor 15 and the cleaning device 21 is detachably mounted.

FIG. 1 shows a main part of the configuration. That is, a CPU (Central Processing Unit) 300 as a control unit for controlling the whole, a main motor 301 for driving the developing device 18 having the toner density detector 70, a toner return unit 68, a rotary shutter 99, and a storage circuit , And the like.

The CPU 300 drives the respective parts of the printer main body 5 to perform the above-described image forming operation, and at the same time, the substrate 39 of the developing device 18.
The identification number (or information indicating new or old) supplied from a not-illustrated developing device 18 (not shown)
Is stored in the memory 302 as a new identification number, and when a new (different) identification number is supplied, it is determined that the developing device 18 has been replaced, that is, a new developing device 18 has been mounted.

Further, when the CPU 300 determines that a new developing device 18 is mounted, the CPU 300 performs an initial process to store a reference voltage value corresponding to a reference developer concentration in the memory.
It is set to 302. In this case, the driving means 1
The drive of the toner return means 68 is stopped by the motor 114 (none of which is shown), the rotary shutter 99 is closed, and only the developing device main body 57 is driven by the main motor 301 to flow the developer D. Is set to a stable state, the voltage value converted by the toner density detector 70 is set in the memory 302 as a reference value.

Further, the CPU 300 drives the toner return unit 68 by the motor 114 (not shown) of the driving unit 107 in accordance with the execution of the image forming operation, and opens the rotary shutter 99 and the like, thereby the cleaning device. twenty one
The recycling operation of returning the collected toner X to the developing device 18, the reference voltage value from the memory 302 and the voltage value from the density detector 70 of the developing device 18 are compared, and based on the comparison result, the toner supply shaft 71 ( (Not shown), the toner supply operation from the toner cartridge 67 to the developing device 18 is controlled.

Next, an operation (initial processing) when the developing device 18 having the above configuration is mounted will be described with reference to a flowchart shown in FIG. For example, it is assumed that a new developing device 18 is mounted on the printer main body 5 by the above-described setting method. Then, the CPU 300 compares the identification number supplied from the substrate 39 of the new developing device 18 with the identification number stored in the memory 302, and
Judge 18 sets. At this time, the storage content of the memory 302 is updated with the identification number corresponding to the new developing device 18.

In this state, the CPU 300
While the drive of the toner return means 68 is stopped by 14,
The rotary shutter 99 is closed.

Further, only the developing device main body 57 is driven by the main motor 301, and the developer D is agitated by the rotation of the developer agitating bodies 64 and 65, thereby stabilizing the flow of the developer D. At this time, it takes about 2 minutes and 30 seconds for the developer D in the developing device 18 to be sufficiently stirred and the toner concentration becomes uniform (stable). That is, as shown in FIG. 3, for example, the developer D in the developing device 18 has a non-uniform toner concentration (indicated by a and b in the figure). Therefore, the stirring operation is continued until the developer D is stabilized (indicated by c in the figure).

Then, when 2 minutes and 30 seconds have elapsed (indicated by d in FIG. 3), the converted voltage value is read by the toner concentration detector 70, and this is set in the memory 302 as a reference value.

Thereafter, the toner replenishing operation is performed in accordance with the comparison between the reference value and the toner density of the developer D (voltage value converted by the toner density detector 70 according to the toner density changed during the image forming operation). Is controlled.

As described above, when the reference value for the developer concentration of the developing unit is set, the developer returning operation by the developer returning unit is stopped to prevent the developer from being mixed in from the cleaner unit, so that the development in the developing unit is prevented. The agent concentration can be read in a stable state.

That is, when a new set of developing devices is determined,
By stopping the driving of the toner returning unit and closing the rotary shutter, the toner collected by the cleaning device is prevented from being mixed into the developing device. Then, after the developer in the developing device is sufficiently stirred, the reference value is read by the toner concentration detector. Therefore, as shown by the broken line e in FIG. 3, it is possible to prevent the toner concentration from being stabilized at an incorrect value due to the mixing of the collected toner into the developing device. As a result, the reference value is not set to an incorrect value, and thus the toner density can be correctly controlled by the accurate reference value. Therefore, it is possible to prevent the image from becoming lighter, darker, or uneven in density, and to prevent deterioration in image quality.

Note that, in the above-described embodiment, the case where the development is performed using the two-component developer including the toner and the carrier has been described. However, the invention is not limited thereto. Also applicable to

[Effects of the Invention] As described above, according to the present invention, it is possible to accurately read the reference value for the developer concentration of the developing unit by the developer concentration detecting unit, and to correct the developer concentration in the developing unit. An image forming apparatus that can be controlled and can obtain a high-quality image can be provided.

[Brief description of the drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a block diagram showing a main part of the configuration, FIG. 2 is a flowchart for explaining the operation, and FIG. 3 is a diagram for explaining the operation. FIG. 4, FIG. 4 is an external perspective view of a laser printer to which the image forming apparatus of the present invention is applied, FIG. 5 is a schematic vertical sectional side view thereof, and FIG. , FIG. 7 is a schematic perspective view with the cover opened, FIG. 8 is a front view with the cover opened, FIG. 9 is a schematic cross-sectional view of the toner discharge section of the cleaning device, FIG.
FIG. 11 is a schematic front view of the toner return means, FIG. 11 is a schematic plan view of the toner return means, FIG. 12 is a configuration explanatory view of a driving source peripheral portion, and FIG. 13 is a line IX-IX in FIG. Sectional view along
FIG. 14 is a view for explaining a state in which a tray is attached to the guide frame, FIG. 15 is a view for explaining an attached state of the developing device, and FIG. 16 is a view for explaining an attached state of the cleaning device. FIG. 17 is a diagram showing the flow of the developer and the stirring blades in the developing device, FIG. 18 is a diagram showing the configuration of the stirring blades in the developing device, FIG. 19 is an external view of the developing device, and FIG. FIG. 21 is a diagram showing a seal material of a developing device, FIG. 21 is a diagram showing a configuration of a developing roller, FIG. 22 is a characteristic diagram of density and voltage value, and FIG. is there. 5 Printer main body, 9 Operation panel display section, 15 Photoconductor (image carrier), 18 Developing device (developing means), 21
Cleaning device (cleaner means), 67 toner cartridge (supply means), 68 toner return means (developer return means), 70 toner concentration detector (developer concentration detector), 99 rotary shutter , D: Developer, 300
... CPU, 302 ... memory.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yuji Rikima 70, Yanagicho, Sachi-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba Automatic Equipment Engineering Co., Ltd. (56) References JP-A-62-103659 (JP, A) JP-A 61-252570 (JP, A) JP-A 61-215574 (JP, A) JP-A 60-57361 (JP, A) JP-A 60-133480 (JP, A)

Claims (1)

(57) [Claims] An image forming means for forming an electrostatic latent image on an image carrier; and a developer accommodating portion which is detachably provided and accommodates a developer, wherein said image forming means is formed by said image forming means. Developing means for developing the electrostatic latent image on the image carrier by supplying a developer from the developer accommodating section; and a developing means provided in the developing means for controlling a concentration of the developer in the developer accommodating section. Density detecting means for detecting, new and old detecting means for detecting the old and new of the developing means, and referring to the detection result of the density detecting means when the new and old detecting means detects that the developing means is new. Setting means for setting the developer density detected at this time as a reference density; comparing the reference density set by the setting means with the density of the developer detected by the detection means; Detected Replenishing means for replenishing developer to the developer accommodating portion of the developing means when the density is lower than the reference density; and a recording medium for storing the developer image on the image carrier developed by the developing means. Transfer means for transferring the developer onto the recording medium; removing means for removing the developer remaining on the image carrier after being transferred onto the recording medium by the transfer means; Transport means for transporting the developer removed by the removing means to the developer accommodating portion of the developing means, while the setting operation of the reference density is performed by the setting means. An image forming apparatus, comprising: a prohibition unit that prohibits a developer conveyance operation of the conveyance unit.