JPS6385661A - Developer concentration adjusting device for image forming device - Google Patents

Abstract

PURPOSE:To improve picture quality and also improve the reliability of a device by providing a supply means which supplies toner and a consuming means which consumes toner forcibly according to the concentration of toner in a developer. CONSTITUTION:The toner concentration is displayed with the output voltage of a toner concentration detector 70 and detected. When the toner concentration decreases below a reference value rho0 and reaches a lower-limit value rho1, namely, an output voltage reaches an upper-limit voltage E1 and the output signals of a 1st and 2nd comparators 137a and 137b both reach H level, a control part 200 decides toner supply level and a control circuit 138 drives a toner cartridge 67 to increase the toner concentration. When the toner concentration is larger than rho1 and smaller than rho2, the 1st comparator 137a outputs L level and the 2nd comparator 137b outputs H level, so that the control circuit recognizes a proper state. Further, when the detection result reaches the upper-limit value rho2, namely, when the output voltage reaches a reduction voltage E2, the control circuit 138 decides toner consumption level and consumes a large amount of toner forcibly to reduce the toner concentration, thereby holding the developer stably all the time.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention is an image processing system that adjusts the toner concentration of a two-component developer in a developing device in a copying machine, a printer, etc. that uses an electrophotographic method. The present invention relates to an improvement of a developer S degree adjusting device included in a forming apparatus.

(Prior Art) Various types of developers have been developed for use in developing devices for image forming devices using electrophotography, such as copying machines and printers, and one of them is a magnetic carrier. A two-component developer consisting of a toner and a toner is often used. With such a developer, in order to maintain a constant image quality, it is necessary to keep the toner concentration in the developer constant. Therefore, the toner concentration in the developer is detected at any time, and the appropriate amount of toner is added. Toner must be replenished.

On the other hand, in recent years, residual toner removed by a cleaner, which was previously discarded, is collected and reused.
Many image forming apparatuses are in use that employ a toner recycling method that saves toner by supplying toner into the apparatus, reduces the frequency of toner cartridge replenishment, and reduces maintenance.

That is, in this device, toner is supplied from the toner cartridge through the first supply section, and toner in the cleaner collected from the photoreceptor is supplied through the second supply section. It is something that

However, in such a device, although the first replenishing section can control the supply of toner from the toner cartridge as appropriate depending on the toner concentration in the developer, the supply of toner from the cleaner cannot be controlled. Moreover, depending on the image, an abnormally large amount of residual toner may be collected, and as a result, excessive toner may be supplied to the developing device.

As a result, the toner concentration of the developer far exceeds the standard value, causing scattering and spillage of particles during development, staining the inside of the main body, and eventually causing deterioration of image quality due to image stains and fogging. I have a problem.

(Problems to be Solved by the Invention) Conventionally, the amount of recovered toner supplied from the cleaner could not be controlled, and the toner concentration in the developer increased due to excessive supply of toner, causing fogging on the image or problems occurring outside the device. There is a problem in that scattering and spillage of toner stains the inside of the main body, which in turn stains the image and degrades the image quality.

Therefore, the present invention is intended to eliminate the above-mentioned drawbacks.It is possible to always keep the toner concentration in the developer at an appropriate level regardless of the supply of excess toner, and to perform good development with the developing device, while at the same time allowing the toner to be removed from the developing device. Keeps the inside of the main unit clean without causing any scattering or spillage, which in turn prevents image stains.
It is an object of the present invention to provide a developer concentration adjusting device for an image forming apparatus that can improve image quality and reliability of the apparatus.

[Structure of the invention]

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a supply means for appropriately supplying toner into the developing device according to the toner concentration in the developer, and a supply means for appropriately supplying the toner within the developing device. A means of consumption for forced consumption is provided.

(Function) According to the present invention, when the toner concentration in the developer is low, the toner is supplied by the supplying means, while the toner 'a
When the degree of toner is high, the toner is forcibly consumed by the consumption means, and the toner concentration in the developing device is always maintained at an appropriate level, thereby improving image quality and reliability of the device.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 9. 1 and 2 are an external perspective view and a schematic explanatory diagram showing the internal configuration of an image forming unit device equipped with a laser printer 1, which is an image quality forming device of the present invention, and the laser printer 1 is a multi-cassette feeder. 2, and an envelope feeder 3 is attached to the rear end.

The rear portion of the upper surface of the printer main body 5 is raised one step higher, and a recessed portion 6 serving as a paper stamping portion is formed in the center of the upper surface. A paper tray 8 movably supported by a jogger 7 is attached to the recess 6, and
The operation panel display section 9 and the operation panel switch section 10 are on the right side of this recess 6, and the three IC card insertion slots 11 and 3 are on the left side.
... are arranged respectively.

Roughly speaking, on the front of the printer main body 5, there is a paper tray 12.
Further, a manual feed tray 13 is attached to the rear side.

Further, a drum-shaped photoreceptor 15 is provided as an image carrier approximately at the center of the printer main body 5, and
As shown in FIG. 3, around it are a charging device 16 which is a charging means, a laser optical system 17 which is an exposure means, a developing device 18 which is a developing means and performs reversal development, a transfer device @19, a peeling device 20, A cleaning device 21 and a static eliminator 22 as cleaning means are sequentially arranged. At both front ends of the charging device 16, charge cut shutters 135a and 135b are provided which are slid in the longitudinal direction of the charging device 16 by a control section 200, which will be described later, and are consumption means for shielding the charges generated by the charging device 16. There is.

Furthermore, an image support transport path 24 is formed inside the printer body 5 and extends forward through an image transfer section 23 between the photoreceptor 15 and the transfer device 19, and is housed at the bottom of the printer body 5. Paper P automatically fed from the paper feed cassette 25 and the paper feed cassettes 26 and 27 of the multi-cassette feeder 2 via the paper feed roller 28 and transfer roller 29, respectively, and paper P manually fed from the manual feed tray 13. , tj and envelopes A automatically fed from the envelope feeder 3 are guided to the image transfer section 23.

Further, a pair of aligning rollers 30 is arranged on the upstream side of the image transfer section 23 of the image support transport path 24, and a fixing device 31, a paper selector 32, and a pair of paper forming rollers 33 are arranged on the downstream side. There is.

A pair of paper stamping rollers 34 is provided at the end of the image support conveying path 24 to guide the paper P, envelope A, etc. that have been sorted by the paper selection selector 32 to the recess 6 serving as a paper stamping section. A branch conveyance path 35 is formed.

1, 40 is a lower cover, 41 is a front cover, 42 is an upper cover, 43 is a right cover, 44 is a left cover, 45 is a right cover opening/closing lever, and 4G is a lever for opening/closing the upper unit. Reference numerals 47, 48, and 49 shown in FIG. Further, the control unit 200 sends the detection results from the toner concentration detector 70 to the upper limit voltage generator 139a and the lower limit voltage generator 139b.
Compare with 1st. Second comparator 137a, 13
7b and this 1st. 2nd] comparator 137a,
The control circuit 138 selectively operates either the toner cartridge 67 or the shutters 135a and 135b, which will be described later, in response to an output signal from the toner cartridge 137b.

Further, as shown in FIG. 3, the photoreceptor 15, the cleaning device 21, and the developing device 18
The right cover 43 is mounted on a guide frame 51 that is slidably supported via a
These can be pulled out to the right side of the printer main body 5 by pulling out the guide frame 51 while listening to the above.

Further, the photoreceptor 15 and the cleaning device 21 are unitized, and are integrally connected to the guide frame 51.
Further, the developing device 18 is configured to be detachable independently.

The developing device 18 has a structure as shown in detail in FIG. 3.

That is, this developing device 18 includes a developing mechanism section 55 and a developer stirring section 56.

The developing mechanism section 55 includes a developing device main body 570 and an opening section 58.
A developing roller 59 disposed opposite to the developing roller 59 and the developer fG magnetic brush' formed on the surface of the developing roller 59 are in sliding contact with the photoconductor 15, that is, the developer is provided upstream of the developing section 60. A doctor 61 that regulates the thickness of the magnetic brush D', and a scraper provided on the downstream side of the developing section 60 that peels off the developer magnetic brush D' formed on the surface of the developing roller 59 and guides it to the developer stirring section 56. 62. Further, the developer 1j2 stirring section 56 is a first developer accommodated in a developer accommodating section 63 formed behind the arrangement section of the developer 1 cola 59. It has a second developer 1j2, 6 bodies, and 65.

Further, the developing roller 59 includes a magnetic roll 59a having a plurality of magnetic pole parts (not shown), and a magnetic roll 59a having a plurality of magnetic pole parts (not shown).
The non-magnetic sleeve 59b is fitted onto the outside of the sleeve 59a and rotates clockwise as shown by the arrow in the figure.

Further, a toner receiving section 66 as a developer receiving section is formed at a position facing the developer stirring section 56 of the developing device main body 57, and is a first toner supplying section described later.
Toner car 1~ controlled by ll il1 section 200
The toner T supplied from the cartridge 67 and the toner T returned from the cleaning device 21 via a toner recovery path 68, which is a second toner supply section, are received.

Further, a toner concentration detector 7 serving as a detection means for detecting the toner concentration of the developer is provided at a position facing the scraper 62.
0 is provided, and a toner replenishment shaft 71 (see FIG. 5) incorporated in the toner cartridge 67 is driven as necessary based on the detection result from the toner concentration detector 70.

Further, the cleaning device 21 has a configuration as shown in FIG. That is, a cleaning plate r7 is housed in a cleaning device main body 75 which has an opening 76 in a portion facing the photoreceptor 151. This cleaning blade 77 is rotatable by a support shaft 78, and The blade holder 8 is always biased counterclockwise in the state shown in FIG. 3 by the plow 79 as a biasing body.
The upper end portion is held by 0, and the tip of the lower end portion is in pressure contact with the circumferential surface of the photoreceptor 15.

The cleaning blade 77 scrapes off the residual toner T that has adhered to the photoreceptor 15.

Further, a recovery blade 81 is installed at the lower end edge of the opening 76. and the cleaning blade 77
The toner T scraped off by the cleaning device main body 7
It is designed to be collected within 5 days.

Further, a toner collection auger 82 is disposed at the bottom of the cleaning device main body 75 to transfer the toner T in the cleaning device main body 75 to a toner discharge portion 83 projecting to the outside to deliver the toner T in the cleaning device main body 75 to the toner collection path 68.

A toner discharge port 84 is formed on the lower surface of the toner discharge portion 83, and this toner discharge port 84 can be doubly closed by a rotary shutter (not shown) and a slide shutter 85. ing.

On the other hand, as shown in FIGS. 4 and 5, the right cover 43
1 to 1 collected by the cleaning device 21 are inside the
A toner recovery path 68 for returning the toner T to the developing device 18 is installed.

This toner recovery path 68 is arranged from 1 to 1 as shown in detail in FIG.
The toner receiving section 90, a toner discharging section 91, and a toner transferring section 92 that transfers the toner received in the toner receiving section 90 to the toner discharging section 91). When the right cover 43 is closed, - F 1
- The toner receiving part 90 is located on the lower surface side of the toner discharge part 83 of the cleaning device 21 and faces the toner discharge port 84,
Further, the toner discharge portion 91 is located above the developer storage portion 63 of the developing device 18 and faces the toner receiving port 66 .

The toner receiving section 90 has a toner receiving port 94 opposite to the toner discharging port 84 of the cleaning device 21, and the slide shirt 90 is configured by pushing in a slide shutter 85 provided at the toner discharging port 83 of the cleaning device 21. A rotary shutter opening/closing gear 97 that rotates the rotary shutter by meshing with a gear 96 integrated with the rotary shutter opening/closing portion 95 and the rotary shutter is disposed.

Further, the toner discharge section 91 has a cartridge mounting section 98 for mounting the toner cartridge 67 on the upper surface, and a toner discharge port 100 that is opened and closed by a rotary shutter 99 is formed on the lower surface side.

A slide shutter 101 for opening and closing the toner discharge port 100 is provided on the car 1 helicopter mounting portion 98 . The slide shutter 101 has an opening 102 for releasing toner and an engaging protrusion 103 protruding from three openings of the opening 102, and the toner cartridge 67 is mounted in the cartridge mounting portion 98. Then, the engagement protrusion 103 engages with an engagement recess (not shown) formed on the lower surface side of the slide shutter 104 of the toner cartridge 67.

Further, an opening (not shown) for supplying toner is formed in the engagement recess, and is in communication with the opening 102, and the slide shutter 101 is in communication with the opening 102.
is a control circuit 138 that includes a rack and pinion (not shown)
The opening 10 is automatically closed by an opening/closing mechanism controlled by
2 slides to a position opposite to the discharge port 100.

Further, the rotary shutter 99 is configured to rotate and open the toner discharge port 100 by driving a gear 110 via a drive system (not shown).

Further, the toner transfer section 92 includes a communication tube 111 that communicates the toner receiving section 90 and the toner discharge section 91, and a spiral member 112 that is housed in the communication tube 111 and that transfers the toner T as it rotates. 9,
The spiral member 112 is configured to rotate as a gear 113 is driven by a drive system (not shown).

In addition, as shown in FIGS. 4 and 5, the right cover 4
3 is a drive device (not shown) for the toner recovery path 68, a J drive device (not shown) that drives the toner replenishment 1/71 of the toner cartridge 67, and a toner replenishment 4@71 and the drive device as the right side cover 42 is opened and closed. A clutch mechanism 121 for connecting and disconnecting from the drive shaft 120, a guide member 122, a safety switch operating claw 123, a cover locking claw 124, a guide member 125 for positioning the photoreceptor 15 and the developing device 18, etc. are attached. There is.

Note that 130 shown in FIG. 4 is a slide shutter that opens and closes the toner receiving port 66 of the developing device 18, and when the right side cover 43 is closed, it is pushed by the toner discharge section 91 and slides to open the toner receiving port 66. It looks like this.

Further, 131 is a handle for pulling out the slide rail 51 on which the unit device of the developing device 18, the photoreceptor 15, and the cleaning device 21 is removably mounted.

In the image forming operation, the photoreceptor 15 is driven and uniformly charged by the charging device 16. Then, the laser optical system 17 exposes the photoreceptor 15 to light corresponding to an image signal. is performed to form an electrostatic latent image. Next, this electrostatic latent image on the photoreceptor 150 is developed by a developing device 18 using a two-component developer consisting of toner T and curer C, and is sent to the image transfer section 23 side as a toner image.

Here, developer particles stand on the surface of the non-magnetic sleeve 59b due to lines of magnetic force generated from each magnetic pole portion and are attracted in a brush shape to form a developer magnetic brush D'. The developing section 60 is rotated by the rotation of the sleeve 59b.
The toner a in the magnetic brush D' adheres to the electrostatic latent image on the photoreceptor 15 and develops it.

On the other hand, in synchronization with this developer image forming operation, paper feed force Sera 1 to
The paper P1 selectively taken out from 25.26.27 or the paper P fed by hand, or the envelope A fed from the envelope feeder 3 (3j), is fed through a pair of aligning rollers 30 and The toner image formed on the photoreceptor 15 is transferred to the paper P or envelope A by the movement of the transfer device 19.Then, the paper P or envelope A is peeled off from the photoreceptor 15 by the peeler 20. The toner image is then sent to the fixing device 31 through the image support transport path 24. After the toner image is melted and fixed onto the paper P or envelope A, the ejection direction is sorted by the paper selector 32 and the upper part is printed. Paper tray 8 or paper tray 1 in the front
2 is discharged on top.

Note that after the toner image is transferred onto the paper P or the envelope A, the residual toner remaining on the photoreceptor 15 is cleaned by the cleaning device 21, and the next copying operation is ready.

On the other hand, the residual toner collected in the cleaning device 21 by the cleaning blade 77 is removed by a toner collection auger 82.
The toner is transferred to the toner discharging section 83 from the toner discharging port 84, through the toner receiving section 90, and then transferred in the direction of the arrow by the toner recovery path 68. The toner is collected from the discharge port 100 into the developing device 18 via the toner receiving port 66 .

While the image forming process is being performed in this manner, the toner concentration of the developer is constantly detected by the toner density detector 70 in the current aI device 18, and the detection results are sequentially displayed at 1t.
It is input to the III control section 200. As a result, the control section 20
0, when the toner concentration of the developer is low beyond the standard range, the toner supply shaft 71 in the toner cartridge 67 is driven and the slide shutter 101 is slid so that the opening 102 communicates with the discharge port 100. , toner intake port 6
An appropriate amount of toner in the toner cartridge 67 is supplied into the developing device 18 through the toner cartridge 67.

On the other hand, if the toner concentration of the developer is higher than the reference range, the control section controls the charge cut shutter 135a,
135b to the position indicated by the solid line in FIG. 7 in the direction of the arrow N and the direction of the arrow Z, the charges released at both ends of the charging device 16 are blocked, and an electrostatic latent image is formed on the photoreceptor 15 as shown in FIG. A charged area where the toner is formed and uncharged areas M and N where the entire surface is developed in the developing device 18 are formed.

Specifically, as shown in FIG. 8, the toner concentration is displayed and detected by the output voltage of the toner temperature detector 70. Then, the toner concentration decreases from the reference value ρ0 (%), the lower limit value ρ1 (%), that is, the output voltage reaches the upper limit voltage E1 (V), and the output signals of the first and second comparators 137a and 137b both become HI level. When the controller 200
t, the toner supply level is determined as shown in Table 1, and the control circuit 138 drives the toner cartridge 67 to supply toner into the developing device 18 and increase the toner density. Further, while the toner concentration ρ is within the reference range of ρ1 to ρ<ρ2, the first comparator 137a is at the Lφ level and the second
The comparator 137b becomes HI level, and the control circuit 138 recognizes that the toner receiving port is appropriate. Furthermore, a large amount of toner is collected by the cleaning device 21,
These are supplied to the developing device, and when the detection result by the toner concentration detector 70 reaches the upper limit value ρ2 [%], that is, the output voltage reaches the reduced voltage E2 (V), the first and second comparators 13
The output signals of 7a and 137b are both at the Lφ level, and the control circuit 138 determines that the toner consumption level is reached.
A charge cut shutter 135a,
135b is driven to form uncharged areas M and N on the photoreceptor 15, and this uncharged area is completely developed in the developing device 18, thereby forcing the toner in the developing device 18 to become multi-layered. to reduce toner density.

[Table 1] With this shift, when the toner concentration in the developer decreases, the toner concentration detector 70 detects this and the toner cartridge 67 is driven to immediately supply toner. However, while the toner temperature can be corrected to the standard range,
If the toner concentration is increased, this is detected and the charge cut shutter is activated at 1:55a, 135.
b is driven to forcibly form a toner adhering area on the photoreceptor 15 and consume a large amount of toner, thereby immediately correcting the toner temperature to the reference range. 1- A toner recycling method is adopted to save toner. Even if the image density is too low, or conversely, the image density is too high, it will not cause fogging on the image, and you can obtain good images, and the inside of the device will not be contaminated. Its reliability can be improved.

Note that this invention is not limited to the above-mentioned embodiments, and can be modified in various ways. For example, the development method using development@neck may be a regular development method. In this case, a shutter may be installed in the exposure device as a consumption means during exposure. leaving a charged area on the photoreceptor,
By developing this area over the entire surface, multiple toners may be consumed. Further, the consumption means is not limited to the shutter, but as in another embodiment shown in FIG. Both ends M, N/! of the photoreceptor 15 charged over the entire length in the longitudinal direction by the charging device 16 may be exposed to light, and the developer may be attached thereto to forcibly consume the toner. ,.

(Effects of the Invention) As explained above, according to the present invention, by controlling the toner supply means and the toner consumption means according to the toner concentration of the developer, it is possible to immediately set the concentration from 1 to 1 to an appropriate value. Since the toner recovery path can be easily adjusted, even if a toner recycling method is adopted that saves toner and improves its efficiency, there will be problems such as blurring due to a decrease in toner concentration or fogging due to an increase in toner concentration. In addition, the inside of the device can be kept clean without scattering or spilling of excess toner, and as a result, image quality and reliability of the device can be improved.

[Brief explanation of the drawing]

1 to 9 show an embodiment of the present invention. FIG. 1 is an external perspective view of the image forming unit, FIG. 2 is a schematic explanatory diagram showing the inside of the image forming unit, and FIG. The figure is a schematic explanatory diagram 81 showing the image forming means around the photoreceptor,
FIG. 4 is a schematic perspective view showing the right cover in an open state;
Figure 5 is a schematic front view showing the left cover in the open state;
FIG. 6 is a schematic explanatory diagram showing the toner recovery path, FIG. 7 is a schematic perspective view showing the charging device and charge cut shutter, and FIG. 8 is a graph showing the output voltage of the toner concentration detector with respect to the toner concentration. Figure 9 is its block diagram,
FIG. 10 is a perspective view of main parts showing another embodiment. 1... Ray tatami printer, 5... Main body, 15...
Photosensitive drum, 16... Charging device, 18... Developing device, 21... Cleaning device, 68... Toner recovery path, 70... Toner) Opening degree detector, 135a, 135b... Charge cutter V ivy, 200...control unit.

Claims (1)

[Scope of Claims] 1. Development in which an electrostatic latent image is formed on an image carrier using a charging means and an exposure means, and a two-component developer consisting of toner and carrier in a housing is attached to the electrostatic latent image. A detection means for detecting the toner concentration of the two-component developer in the housing, in which the toner remaining on the image carrier is removed by a cleaner after the development is completed using the means;
a supply means connected to the casing for supplying toner into the casing; a consuming means for forcibly consuming the toner within the casing; 1. A developer concentration adjusting device for an image forming apparatus, comprising a control means for controlling the developer concentration. 2. The supply means has a first supply section that supplies the developer in the toner cartridge and a second supply section that supplies the developer collected from the cleaner, and the control device controls the first supply section. 2. A developer concentration adjusting device in an image forming apparatus according to claim 1, wherein the developer concentration adjusting device controls a developer concentration in an image forming apparatus. 3. The image forming apparatus according to claim 1 or 2, wherein the consumption means is provided in front of the developing roller and forcibly forms a toner adhering portion on the image carrier. developer concentration adjustment device. 4. Developer concentration in the image forming apparatus according to claim 3, wherein the consumption means is a charge cut shutter that is provided in front of the charging means and moves so as to regulate the charging width of the image carrier. Adjustment device. 5. A developer concentration adjusting device in an image forming apparatus according to claim 3, wherein the consuming means is a static eliminator that neutralizes a part of the image carrier. 6. A developer concentration adjusting device in an image forming apparatus according to claim 5, wherein the static eliminating device is an irradiation lamp.