JPH0466984A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain a stable concentration for developing by automatically replenishing a fresh developer and a carrier whenever the images of the fixed number of sheets are formed, and discharging the replenished developer or the deteriorated developer of the same quantity as that of the carrier. CONSTITUTION:After stirring rollers 3a and 3b are rotated, toner from a toner replenishing roller 4 and the developer in a developing tank 1 are stirred and mixed, they are magnetically attracted to a developing roller 2, the napping of the toner is adjusted, and then, they are carried to a photosensitive body D to carry out electrostic development. Thereafter, a counting signal is outputted to a controller 10 whenever a counting counter C counts the number of sheets for forming the image. Therefore, a developer replenishment control means 11 inside the device 10 drives the developer replenishing roller 5b of a developer replenishing device 5 and the developer is replenished into the developing tank 1 by a fixed quantity. Simultaneously, a carrying means 12 drives the stirring rollers 3a and 3b and carries the deteriorated developer to a discharging port 7. Further, a deteriorated developer discharging control means 13 drives an opening/closing device 9 to obtain a closed state of the discharging port 7, and the deteriorated developer is discharged on a deteriorated recovering container 6 via a L-shaped barrel.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to electrophotographic image forming apparatuses such as electrostatic transfer copying machines and laser printers, and particularly relates to replacement of developer in the developing device. .

<Prior Art> In an image forming apparatus (copying machine) as an electrophotographic apparatus, the developer used to visualize the electrostatic latent image on the photoreceptor is generally a two-component mixture of toner and carrier. type developers are widely used.

The developing device for visualizing the electrostatic latent image is
It includes a developer tank for stirring the developer and a toner hopper for replenishing the developer tank with toner reduced by development.

Problems to be Solved by the Invention 〉 Generally, as the number of sheets on which images are formed (the number of copies) increases, toner adheres and accumulates on the carrier surface and the carrier deteriorates, and this carrier deterioration causes the toner charge amount to decrease and the image quality to increase. A decrease in formed density (copied image density) occurs. Therefore, when the so-called lifespan of the developer is exceeded, the developer must be replaced.

At this time, in conventional image forming apparatuses, the developer in the developer tank must be completely replaced manually, which takes time and requires the user to dispose of deteriorated developer. It becomes complicated and has poor workability.

Further, as described above, since the developer cannot be replaced until the developer reaches the end of its life, the density of the copied image is unstable. If you decide to replace the developer frequently to prevent the density from decreasing, the total number of developer replacements will increase.
The amount of developer required for replenishment is large, which is inefficient, and the usable toner in the developer is also discarded at the same time, resulting in high maintenance costs.

In view of the above, the present invention automatically replenishes new developer (carrier) every time the number of images formed increases by a certain number, and discharges deteriorated developer in an amount equivalent to the replenished developer. , stable image forming density can be obtained,
Moreover, it is an object of the present invention to provide an image forming apparatus that saves the trouble of replacing the developer due to its lifespan and reduces maintenance costs.

<Means for Solving the Problems> The means for solving the problems according to claim 1 of the present invention, as shown in Figs. 3a and 3b; and a counting counter C, which comprises: a developer replenishing device 5 for replenishing the developer into the developer tank 1 above the developer tank 1; A discharge port 7 for discharging deteriorated developer in the developer tank 1 is formed at a position separated from the developer replenishing device 5 of the developer tank 1, and an opening/closing device 9 for opening and closing the discharge port 7. are provided, and based on the counting signal from the counting counter C, the developer replenishing device 5, the stirring rollers 3a, 3b, and the opening/closing device 9
A control device IO is provided for controlling the driving of the developer tank 1, and the control device IO drives the developer replenishing device 5 to deposit a certain amount of developer into the developer tank 1 every time the counting counter C counts a certain number of sheets. a developer replenishment control means II for replenishing the developer; and a developer tank 1 by driving the stirring rollers 3a and 3b.
a deteriorated developer conveyance control means 12 for conveying the deteriorated developer inside to the discharge lower; and a deteriorated developer conveyance control means 12 that drives the opening/closing device 9 to open the discharge lower and discharge the deteriorated developer in an amount equivalent to the amount of developer replenishment. A degrading agent discharge control means 13 for discharging the deteriorating agent is provided.

Further, in claim 2, as shown in FIG. 6.7, a counting counter is provided, which is a device comprising a developer wIl, a developing roller 2 and stirring rollers 3a and 3b rotatably installed in the developer tank I. In the image forming apparatus equipped with C, a second toner replenishing device 4 for replenishing toner into the developer tank L is provided above the developer tank L, and a carrier replenisher for replenishing carrier into the developer tank L. A device 20 is provided, and a discharge port 7 for discharging deteriorated developer in the developer tank I is formed at a position separated from the carrier replenishing device 20 of the developer tank L, and the discharge port 7 is opened and closed. An opening/closing device 9 is provided, and based on the counting signal from the counting counter C, the carrier replenishing device 20, stirring roller 3 a. 3b and the opening/closing device 9, and the control device IO drives the carrier replenishing device 20 to supply the carrier into the developing tank L every time the counting counter C counts a certain number of sheets. Carrier replenishment control means 2 for replenishing a certain amount of carrier
1, and the stirring roller 3a. 3b to transport the deteriorated developer in the developer tank l to the discharge port 7; and a deteriorated developer transport control means 12 for driving the opening/closing device 9 to open the discharge port 7 and replenish the developer. A deterioration agent discharge control means 13 is provided for discharging the same amount of deteriorated developer.

<Operation> In the above problem solving means, each time an image is formed on one sheet in the developing device A, the counting counter C counts the number of image formed sheets (the number of copies) and outputs a count signal to the control device IO.

Then, the developer replenishment control means 1 in the control device IO
Based on this, the carrier replenishment control means 2l drives the developer replenishing device 5 or the carrier replenishing device 20 to replenish a fixed amount of developer or carrier into the developer tank l. Further, the stirring roller 3 a.
3b is driven to convey the deteriorated developer to the discharge port 7,
The deteriorated developer discharge control means 13 drives the opening/closing device 9 to open the discharge port 7 and discharge a fixed amount of the deteriorated developer.

Therefore, each time a certain number of images are formed, new developer or carrier is automatically replenished, and deteriorated developer or carrier is discharged in an amount equivalent to the replenished developer or carrier. Developer tank! It is possible to obtain a stable developed image density, and the trouble of replacing the developer due to the life of the developer can be saved.

<Example> Embodiments of the present invention will be described below based on the drawings.

[First Embodiment] FIG. 1 is a functional block diagram of a control device of an image forming apparatus according to a first embodiment of the present invention, FIG. 2 is a front view of the developing section, and FIG. 3 is a perspective view thereof. FIG. 4 is an enlarged cross-sectional view showing the relationship between the discharge port and the opening/closing device, and FIG. 5 is a diagram showing changes in image forming density with respect to the number of images formed.

As shown in FIGS. 1 to 3, the image forming apparatus of this embodiment corresponds to claim 1, and includes a developing tank 1, a developing roller 2 and an agitating roller 3a rotatably installed in the developing tank 1, 3
The developing device A includes a developing device A, and a counting counter C that counts the number of sheets on which images are formed.

The developing device A is for visualizing the electrostatic latent image on the photoreceptor, and is disposed close to the photoreceptor as shown in FIG.

Said development t! A toner replenishment port 1a and a developer replenishment port 1b are formed in the upper part of l, and the developer replenishment port 1
b is arranged on the downstream side of the toner supply port 1a, that is, on the photoconductor side. The toner replenishing port 1a has a toner replenishing device 4 for replenishing toner in the developer tank I, and the developer replenishing port 1b has a developer replenishing device 5 for replenishing developer in the developer tank I. It is installed.

The toner replenishing device 4 includes a toner replenishing tank 4a and a toner replenishing roller 4b rotatably installed in a lower end opening of the toner replenishing tank 4a. a tank 5a, and a developer replenishment roller 5b rotatably supported at the lower end opening of the developer replenishment tank 5a.
It is composed of.

Further, as shown in FIG. 3, on the side wall of the developer tank l, that is, at a position away from the developer replenishing device 5 and where the developer can overflow, the deteriorated developer in the developer tank l is transferred to the deteriorated developer recovery container 6. A discharge lower is formed for discharging the developer, and the discharge lower and the deteriorated developer recovery container 6 are connected to each other via an L-shaped portion 8 . As shown in FIG. 4, an opening/closing device 9 for opening and closing the discharge lower is provided at the connection between the discharge lower and the L-shaped portion 8.

This opening/closing device 9 includes a shutter 9a and a shutter 9a.
It is composed of moving means 9b such as a solenoid for moving a in the X and Y directions.

The developing roller 2 and stirring rollers 3a and 3b are arranged in order from the photoreceptor side, as shown in FIG. 2, and their rotation direction is counterclockwise. As shown in FIG. 1, the image forming apparatus of this embodiment controls the driving of the developer replenishing device 5, stirring rollers 3a, 3b, and opening/closing device 9 based on the count signal from the count counter C. A control device IO is provided. The control device 10 is a general one-chip microcomputer with data RAM
, has a program ROM and a CPU, and performs control based on the program stored in the ROM in advance.

That is, the control device 10 drives the developer replenishing roller 5b of the developer replenishing device 5 every time the counting counter C counts a predetermined number of sheets (1,000 sheets) to deposit a predetermined amount (20 g) into the developer tank l. a developer replenishment control means 11 for replenishing the developer; a conveyance means 12 for driving the stirring rollers 3a and 3b to convey the developer in the developer tank l to the discharge lower; and the opening/closing device 9. A deteriorating agent discharge control means 13 is provided for moving the glosser 9a by means of a moving means 9b to open the discharge lower and discharge an amount of deteriorated developer equivalent to the amount of developer replenishment.

In FIG. 1, 14 is used to store the time required to replenish a certain amount of developer into the developer tank 1 and to stop replenishing the developer when the developer replenishment time reaches that time. The first timer 15 is used to store the time required to discharge the degraded developer in an amount equivalent to the developer replenishment amount, and to stop discharging the degraded developer when the degraded developer discharge time reaches that time. This is the second timer.

In the above configuration, a developer mixed with 100 parts by weight of carrier and 4 parts by weight of toner is stored in the developer tank 1 of the developing device A, and the developer tank 1 is further equipped with a toner replenishing device 4 and a developer replenishing device 5. .

In this state, the stirring rollers 3a and 3b are rotated to mix the toner supplied from the toner replenishing device 4 with the developer 1.
1! After stirring and mixing the toner and the developer in 1, the toner is magnetically attracted to the developing roller 2, and after the toner is arranged into spikes, it is conveyed to a photoreceptor and subjected to electrostatic development.

After that, the counting counter C indicates the number of images to be formed (the number of copies)
Every time it is counted, a count signal is output to the control device IO. Then, the developer replenishment control means 1 in the control device IO
Based on this, the developer replenishing roller 5a of the developer replenishing device 5 is driven to replenish a certain amount of developer into the developer tank l. At the same time, the conveying means 12 moves the stirring roller 3 a
, 3b are driven to convey the deteriorated developer to the discharge lower. Further, the deterioration degree image side discharge control means 13 drives the opening/closing device 9 to open the discharge lower and discharges the degraded developer into the degraded developer recovery container 6 via the L-shaped portion 8 .

When a certain amount of developer is replenished from the developer replenishment device 5, the developer replenishment control means It stops the replenishment of the developer from the developer replenishment device 5, and the same amount of developer is supplied from the discharge lower. When the deteriorated developer is discharged, the conveying means 12
closes the discharge lower.

Note that the stirring roller 3a used for conveying the deteriorated developer
, 3b may be stopped at any time after the discharge lower is closed.

Here, the developer replenishment timing is set every 1000 copies, and the developer replenishment amount at this time is 20g.The change in Macbeth reflection density with respect to the number of copies (aging) and when the developer is not replaced using the conventional method. Figure 5 shows the changes in Macbeth reflection density. In FIG. 5, ■ indicates the change in the Macbeth reflection density of the image forming apparatus of this embodiment, and conventionally shows the change in the Macbeth reflection density according to the conventional method. As is clear from the figure, whereas in the conventional case there is a decrease in Macbeth reflection density due to aging,
In case (2), no decrease in Macbeth density due to aging is observed, and it can be seen that the image forming density (copied image density) is stable.

In this way, if configured as in this embodiment, new developer is automatically replenished every time a fixed number of images are formed.
Since the same amount of deteriorated developer as the replenished developer can be discharged, the deteriorated developer does not increase in the developer tank, and a stable development density can be obtained. It saves the trouble of replacing the parts, and the maintenance costs are also low.

[Second Embodiment] FIG. 6 is a functional block diagram of a control device related to an image forming apparatus according to a second embodiment of the present invention, FIG. 7 is a front view of the developing section thereof, and FIG. 8 is a graph showing the number of images to be formed. FIG. 3 is a diagram showing changes in formation concentration.

The image forming apparatus of this embodiment corresponds to claim 2, and as shown in FIG. 7, so that it can be applied as a two-component developing section,
A carrier replenishment port 1c is provided at a position corresponding to the developer replenishment port of the previous embodiment, and a carrier replenishment device 20 is attached to the carrier replenishment port 1c.

The carrier replenishing device 20 includes a carrier replenishing tank 20a and a carrier replenishing roller 20b rotatably supported at the lower end opening of the carrier replenishing tank 20a.

As shown in FIG. 6, the control device IO is provided with a carrier replenishment control means 21 in place of the developer replenishment control means 11 of the previous embodiment. The carrier supply control means 2
1 has a function of driving the carrier replenishing roller 20b of the carrier replenishing device 20 to replenish a predetermined amount of carrier into the developer tlFl every time the counting counter C counts a predetermined number of sheets. It is controlled by a timer signal from one timer 22. That is, the first timer 22 stores the time required to replenish a certain amount of carrier into the developer tank l, and stops replenishing the carrier when the time reaches that time.

As shown in Figure 7, the discharge lower is a developer tank! It is formed at a position on the rear wall where the developer can overflow, and in the figure, numeral 23 is a toner concentration sensor, and the other configurations are the same as in the first embodiment.

With the above configuration, each time a certain number of images are formed, new carrier is automatically replenished and the same amount of developer as the replenished carrier can be discharged, so the amount of deteriorated carrier increases in the developer tank. This prevents the image forming density from decreasing.

Here, the carrier replenishment timing is set every 1,000 copies, and the amount of carrier replenishment at this time is 20g, and the change in Maches reflection density with respect to the number of copies (knee zinc) and the developer in the conventional method are not replaced. Figure 8 shows the change in Macbeth reflection density at that time. In Figure 8, ■
2 shows the change in the Macbeth reflection density of the image forming apparatus of this embodiment, and 2 shows the change in the Macbeth reflection density of the conventional method. As is clear from the figure, in the conventional case there is a decrease in Macbeth reflection density due to aging, but in the case of this example, no decrease in Macbeth density due to aging is observed, and the image forming density (copy image density ) is found to be stable.

It should be noted that the present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

For example, as for the means for opening and closing the discharge lower by moving the gloss as the opening/closing device 9, other than a solenoid, a stepper motor capable of forward and reverse rotation may be used, as long as it is capable of opening and closing the discharge lower.

Further, the opening/closing device 9 may use a roller instead of a shutter.

<Effects of the Invention> As is clear from the above description, according to the present invention, a developer replenishment device or a carrier replenishment device is attached to the upper part of the developer tank, and a discharge port is provided at a position away from the developer replenishment device of the developer tank. is formed, an opening/closing device is provided for opening and closing the discharge port, and a control device is provided for controlling the drive of the developer replenishing device or the carrier replenishing device, the stirring roller, and the opening/closing device based on the count signal from the counting counter. Since the control device includes a developer replenishment control means or a carrier replenishment control means, a deteriorated developer transport control means, and a deterioration agent discharge control means, each time a certain number of images are formed,
New developer or carrier is automatically replenished, and deteriorated developer in an amount equivalent to the replenished developer or carrier is discharged.

Therefore, deteriorated developer does not accumulate in the developer tank, and a stable developed image formation density can be obtained.

Further, there is an excellent effect that the trouble of replacing the developer due to the life of the developer can be saved, and maintenance costs can be reduced.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a functional block diagram of a control device related to an image forming apparatus according to a first embodiment of the present invention, FIG. 2 is a front view showing the developing section thereof, and FIG. 3 is a perspective view thereof. 4 is an enlarged cross-sectional view showing the relationship between the discharge port and the opening/closing device, FIG. 5 is a diagram showing the change in image density with respect to the number of images formed, and FIG. 6 is an image of the second embodiment of the present invention. FIG. 7 is a functional block diagram of a control device related to the forming apparatus, FIG. 7 is a front view of the developing section thereof, and FIG. 8 is a diagram showing changes in image forming density with respect to the number of sheets on which images are formed. Figure 7 A: Developing device, C: Counter, D: Photoreceptor, 1.
Developing tank, 2: developing roller, 3 a, 3 b: stirring roller, 4 toner replenishing device, 52 developer replenishing device, 7. Discharge port, 9/opening/closing device, 10: control device, 11 developer replenishment control means, 12: deteriorated developer transport control means, 13: deteriorated agent discharge control means, 20. carrier supply device, 21
- Carrier supply control means. Figure 188 Applicant Sharp Corporation

Claims (1)

[Scope of Claims] 1. Image formation comprising a developing device including a developing tank, a developing roller and an agitation roller rotatably installed in the developing tank, and a counter for counting the number of sheets on which images are formed. In the apparatus, a developer replenishment device for replenishing developer into the developer tank is installed on the upper part of the developer tank, and a developer replenishment device for replenishing the developer in the developer tank is installed at a position separated from the developer replenishment device of the developer tank. a discharge port is formed for discharging the developer, an opening/closing device is provided to open and close the discharge port, and a control unit controls driving of the developer replenishing device, the stirring roller, and the opening/closing device based on a count signal from the counting counter. A device is provided, and the control device includes a developer replenishment control means for driving the developer replenishment device to replenish a predetermined amount of developer into the developer tank every time the counting counter counts a predetermined number of sheets. , a deteriorated developer transport control means for driving the stirring roller to transport the deteriorated developer in the developer tank to the discharge port; and driving the opening/closing device to open the discharge port and adjust the amount of developer replenishment. An image forming apparatus comprising a deteriorated developer discharge control means for discharging an equivalent amount of deteriorated developer. 2. An image forming apparatus comprising a developing tank, a developing device including a developing roller and an agitation roller rotatably installed in the developing tank, and a counter for counting the number of images formed, the developing tank A toner replenishment device for replenishing toner into the developer tank and a carrier replenishment device for replenishing carrier into the developer tank are provided on the upper part of the developer tank, and at a position separated from the carrier replenishment device of the developer tank, A discharge port is formed for discharging deteriorated developer in the developer tank, and an opening/closing device is provided to open and close the discharge port, and the carrier replenishing device, stirring roller, and opening/closing device are provided based on the count signal from the counting counter. A control device is provided for controlling the drive of the developer tank, and the control device is configured to perform carrier replenishment for replenishing a predetermined amount of carrier into the developing tank by driving the carrier replenishment device every time the counting counter counts a predetermined number of sheets. a control means; a deteriorated developer transport control means for driving the agitation roller to transport the deteriorated developer in the developer tank to the discharge port; and driving the opening/closing device to open the discharge port and release the developer. An image forming apparatus comprising: a deterioration agent discharge control means for discharging an amount of deteriorated developer equivalent to a replenishment amount.