JP2002072808A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of toner image quality due to paper powder contained in residual toner after transfer in an image forming device in which a toner image is formed on an image carrier by a developing device, residual toner after transfer stuck on the image carrier after the toner image is transferred on a transfer paper is removed by a cleaning device, the removed residual toner after transfer is returned to the developing device by a toner recycling device to reuse. SOLUTION: The residual toner after transfer removed from the image carriers 1 by the cleaning device 16 is transported through a toner guiding pipe 21 of the toner recycling device 26, a part of the residual toner after transfer TA is returned to the developing device 3 and other residual toner after transfer is discharged into a toner tank 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image bearing device which forms a toner image on the surface of an image carrier by a developing device, transfers the toner image to a transfer material by a transfer device, and transfers the toner image through a transfer position of the toner image. The present invention relates to an image forming apparatus for removing a transfer residual toner attached to a body surface by a cleaning device.

[0002]

2. Description of the Related Art An image forming apparatus of the above-mentioned type constituted as an electronic copying machine, a printer, a facsimile or a multifunction machine having at least two of these functions has been conventionally known. In such an image forming apparatus, it is provided that a toner recycling device is provided to return the transfer residual toner removed from the image carrier by the cleaning device to the developing device, and the toner is used again for forming a toner image in the developing device. In addition, it is possible to reduce the consumption of toner and to effectively use resources.

Incidentally, the transfer residual toner removed from the image carrier by the cleaning device contains paper dust. Therefore, when the above-described toner recycling device is provided, the paper dust is returned to the developing device together with the transfer residual toner. When a toner image is formed on the surface of the image bearing member with the toner containing such paper dust, for example, 1 m
An abnormal image having a length of about m adheres to the background portion of the surface of the image carrier, and the toner adhered to the paper powder, or the paper powder and the toner are both transferred to the background portion of the transfer material, and the appearance of the completed image is improved. May decrease. Such an abnormal image is also called a “beard image” because it resembles a beard.

[0004] Further, the toner may be aggregated with the paper powder contained in the transfer residual toner returned to the developing device as a nucleus, and a fine aggregate may be formed. When a toner image is formed on an image carrier with the toner containing such aggregates and the toner image is transferred to a transfer material, the toner image portion around the fine aggregates on the image carrier surface and the transfer material are transferred during the transfer. Does not adhere,
A small dot-like image in the toner image transferred to the transfer material,
A missing portion (a so-called white portion) of the surrounding image occurs, and the image quality deteriorates. An abnormal image including such a dot-like image and an image missing portion therearound is also called “firefly”.

As described above, in the conventional image forming apparatus, when the toner recycling apparatus is provided, the advantage that the consumption amount of the toner can be reduced is obtained, but the disadvantage that the abnormal image easily occurs is inevitable.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to effectively use toner by returning the transfer residual toner to the developing device and reusing it, and to solve the above-mentioned conventional disadvantages. It is an object of the present invention to provide an image forming apparatus capable of effectively suppressing.

[0007]

In order to achieve the above object, the present invention provides an image carrier, a developing device for forming a toner image on the surface of the image carrier, and transferring the toner image to a transfer material. A transfer device, a cleaning device for removing transfer residual toner adhering to the surface of the image carrier that has passed a transfer position where the toner image is transferred onto the transfer material, and a transfer residual removed from the image carrier by the cleaning device There is proposed an image forming apparatus comprising: a toner recycling device that returns a part of the toner to the developing device and conveys another transfer residual toner to a toner storage unit.

According to another aspect of the present invention, there is provided an image carrier, a developing device for forming a toner image on a surface of the image carrier, a transfer device for transferring the toner image to a transfer material, A cleaning device that removes transfer residual toner adhering to the surface of the image carrier that has passed the transfer position where the toner image is transferred onto the transfer material; and a transfer device that removes the entire transfer residual toner removed from the image carrier by the cleaning device. Return to the developing device, or transport the entirety of the transfer residual toner to the toner storage unit, or return a part of the transfer residual toner to the developing device, and transport another transfer residual toner to the toner storage unit. An image forming apparatus including a toner recycling device capable of selecting whether to perform the image forming process is proposed (claim 2).

Further, in the image forming apparatus according to the first or second aspect, it is advantageous that the ratio of the amount of the transfer residual toner sent to the developing device and the amount of the residual toner to be sent to the toner storage unit can be adjusted. ).

Further, in the image forming apparatus according to any one of claims 1 to 3, the toner image is sent to the developing device and the toner storage portion according to the image ratio of the toner image formed on the image carrier. It is advantageous that the ratio of the amount of the transfer residual toner can be automatically adjusted (claim 4).

Further, in the image forming apparatus according to any one of claims 1 to 4, the amount of the transfer residual toner to be sent to the developing device and the toner accommodating portion, respectively, according to the temperature in the image forming device. Advantageously, the proportion can be adjusted automatically (claim 5).

6. The image forming apparatus according to claim 1, wherein the toner recycling device includes a toner guide tube through which the transfer residual toner passes, and a toner that conveys the transfer residual toner in the toner guide tube. A transfer member, and the toner guide tube is provided with a part of the untransferred toner removed from the image carrier to the developing device, and when transferring another untransferred toner to the toner storage unit, It is advantageous that a toner discharge hole is formed for the transfer residual toner to be sent to the apparatus or the toner storage section from the toner guide tube (claim 6).

Further, in the image forming apparatus according to claim 6, when the circumferential direction of the toner guide tube perpendicular to the axial direction of the toner guide tube is set to the horizontal direction, the horizontal direction of the toner discharge hole is set. Is advantageously set to be smaller than the width of the transfer residual toner passing through the toner discharge hole in the horizontal direction (claim 7).

In the image forming apparatus according to the present invention, it is advantageous that the opening area of the toner discharge hole is set to 30 mm 2 or less (claim 8).

Further, in the image forming apparatus according to claim 7 or 8, it is advantageous that a plurality of the toner discharge holes are formed along the axial direction of the toner guide tube (claim 9).

Further, in the image forming apparatus according to any one of claims 7 to 9, the toner discharge hole is tapered so that the opening area thereof gradually increases radially outward of the toner guide tube. It is advantageous if it is formed in a shape (claim 10).

Further, in the image forming apparatus according to any one of claims 7 to 10, the toner discharge hole is formed in a rectangular shape, and two parallel sides thereof extend substantially in the axial direction of the toner guide tube. Advantageously (claim 11).

Further, in the image forming apparatus according to any one of claims 6 to 11, the toner guide tube is supported rotatably around its axis, and the toner guide tube is rotated around its axis. It is advantageous to provide a driving means for rotating the first and second motors (claim 12).

Further, in the image forming apparatus according to any one of claims 6 to 12, the toner guide tube is supported rotatably around its axis and a toner image formed on an image carrier. In order to adjust the position of the toner discharge hole in the rotation direction of the toner guide tube in accordance with the image ratio, it is advantageous to provide a drive control means for rotating the toner guide tube around its axis. Item 1
3).

Further, in the image forming apparatus according to any one of claims 6 to 13, the toner guide tube is rotatably supported around its axis and detects the temperature inside the image forming device. A temperature sensor, and drive control means for driving the toner guide tube to rotate around its axis in order to adjust the position of the toner discharge hole in the toner guide tube rotation direction based on the detection result of the temperature sensor. Is advantageous (claim 14).

Further, in order to achieve the above object, the present invention provides an image carrier, a developing device for forming a toner image on the surface of the image carrier, and a transfer device for transferring the toner image to a transfer material. A cleaning device for removing transfer residual toner adhering to the surface of the image carrier passing through the transfer position where the toner image is transferred onto the transfer material, and the entirety of the transfer residual toner removed from the image carrier by the cleaning device An image forming apparatus comprising: a toner recycling device that alternately executes a recycling mode in which the toner is transferred to the developing device and a non-recycling mode in which the entirety of the transfer residual toner is transported to the toner storage unit. ).

Further, in the image forming apparatus according to the present invention, the toner recycling device includes a toner guide tube through which the transfer residual toner passes, and a toner conveying member that conveys the transfer residual toner in the toner guide tube. The toner guide tube has a first outlet for the transfer residual toner to be sent to the developing device and a second outlet for the transfer residual toner to be sent to the toner storage section. When executed, all the transfer residual toner is sent to the developing device from the first outlet, and when the non-recycle mode is executed, all the transfer residual toner is transferred from the second outlet to the toner. Advantageously, it is configured to be fed to the receiving part (claim 16).

Further, in the image forming apparatus according to claim 15 or 16, the toner recycling apparatus is configured to switch between the recycling mode and the non-recycling mode every time a predetermined number of image forming operations are performed. It is advantageous to have control means for controlling (claim 17).

Further, in the image forming apparatus according to the present invention, it is advantageous that the image forming apparatus further comprises an input means for inputting the predetermined number of times.

Further, in the image forming apparatus according to any one of claims 1 to 5 and 15 to 18, the toner recycling device is configured to control an amount of the transfer residual toner to be sent to the developing device and the toner storage unit, respectively. It is advantageous to have a regulating member operable to adjust the ratio of (claim 19).

20. The image forming apparatus according to claim 19, wherein the amount of the transfer residual toner sent to the developing device and the toner accommodating portion, respectively, according to an image ratio of the toner image formed on the image carrier. It is advantageous to provide a drive control means for driving the regulating member in order to adjust the ratio of the control member.

Further, in the image forming apparatus according to claim 19, a temperature sensor for detecting a temperature in the image forming apparatus, and based on a detection result of the temperature sensor,
It is advantageous to provide a drive control means for driving the regulating member in order to adjust the ratio of the amount of the transfer residual toner sent to the developing device and the toner storage portion, respectively.

Further, it is advantageous that the image forming apparatus according to any one of claims 1 to 21, further comprising an impact applying means for applying an impact to the transfer residual toner conveyed by the toner recycling device. Yes (Claim 2
2).

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic partial sectional view showing an example of the image forming apparatus. An image carrier 1 configured as a drum-shaped photoreceptor is arranged in the main body of the image forming apparatus shown here, and the image carrier 1 is rotated clockwise in FIG. 1 by a driving device (not shown). Driven. An image carrier formed of a belt that is wound around a plurality of rollers and driven to rotate can also be used.

When the image carrier 1 rotates as described above,
The surface of the image carrier 1 is charged to a predetermined polarity by the charging device 2. A laser writing unit (not shown), which is an example of an exposure device, is disposed in the main body of the image forming apparatus. The surface of the charged image carrier is exposed by a light-modulated laser beam L emitted from this unit. As a result, an electrostatic latent image is formed on the surface of the image carrier. In this example, a portion where the absolute value of the surface potential of the image carrier is reduced by irradiation with the laser beam L becomes an electrostatic latent image, and a surface portion of the image carrier not irradiated with the laser beam becomes a background portion.
As described above, in the image forming apparatus of the present embodiment, the charging device 2 and the laser writing unit constitute a latent image forming unit that forms an electrostatic latent image on the image carrier.

The electrostatic latent image is visualized as a toner image by the developing device 3. Developing device 3 exemplified here
A developing case 4, a developing roller 5 rotatably supported by the developing case 4 and driven to rotate counterclockwise;
Similarly, the developing case 4 includes a stirring blade 6 rotatably supported and rotatably supported by the developing case 4. The developing case 4 contains a powdery two-component developer D having a toner and a carrier. A developing device using a powdery one-component developer having no carrier, a developing device using a liquid developer having a toner and a carrier liquid, and the like can also be employed.

The developer D is agitated by the agitating blades 6 so that the toner and the carrier are frictionally charged to polarities opposite to each other, and a bias voltage having the same polarity as the charged polarity of the toner is applied to the developer D. The developer carried on the developing roller 5 and conveyed, and the amount of which is regulated by the regulating blade 7 is carried to a developing area between the developing roller 5 and the image carrier 1. In this development area, the toner in the developer is electrostatically transferred to the electrostatic latent image formed on the surface of the image carrier, and the electrostatic latent image is visualized as a toner image.

The developing device 3 has a toner container 8 integrally connected to the developing case 4, and the toner container 8 contains a powdered toner T. The toner T in the toner container is stirred by the rotating toner stirring member 18. When the toner remaining amount sensor (not shown) detects that the amount of toner T in the toner container 8 has decreased, toner is supplied from a toner storage unit (not shown) through a toner supply port (not shown). Supplied. When a toner concentration sensor (not shown) detects a decrease in the toner concentration of the developer D accommodated in the developing case 4, the toner supply roller 10 rotates, and the toner T in the toner container 8 is removed. Will be replenished.

On the other hand, the transfer device 11 faces the image carrier 1.
Is provided. The transfer device 11 illustrated here includes a transfer belt 14 that is wound around a pair of rollers 12 and 13 and is driven in the direction of arrow A, and a bias roller 15, and the transfer belt 14 and the image carrier 1 In the meantime, a transfer material fed from a paper supply unit (not shown), that is, a transfer paper P in the illustrated example, is fed as indicated by an arrow B. The transfer paper P comes into contact with the surface of the image carrier 1 while being carried and transported by the transfer belt 14. At this time, a voltage having a polarity opposite to the charge polarity of the toner on the surface of the image carrier is applied to the bias roller 15, and the toner image on the surface of the image carrier is electrostatically transferred onto the transfer paper P by the action. . The transfer paper P that has passed through the transfer position of the toner image in this manner and has left the image carrier 1 passes through a fixing device (not shown). At this time, the toner image on the transfer paper is subjected to the action of heat and pressure. The image is fixed on the transfer paper.

Instead of a transfer device of the type shown, a transfer device having a transfer means such as a transfer roller, a transfer brush, a transfer blade or a transfer charger, or a transfer device having such a transfer means and a transfer belt can be used.

When continuous paper feeding is performed, the next transfer paper is sequentially fed between the image carrier 1 and the transfer belt 14 in the same manner as described above, and the next toner formed on the image carrier 1 is transferred. The image is transferred onto the transfer paper.

The toner image formed on the image carrier is transferred onto the transfer paper P as described above. At this time, the transfer rate of the toner image is not 100%, and the transfer rate after the transfer of the toner image is not reached. Transfer residual toner adheres to the surface of the image carrier. Also, a very small amount of toner adheres to a background portion between the toner image formed on the surface of the image carrier and the next toner image. And passes through the transfer position of the toner image while being attached to the surface of the image carrier.

The transfer residual toner as described above is removed from the surface of the image carrier by the cleaning device 16. The cleaning device 16 illustrated as an example in FIG. 1 includes a cleaning case 17, a cleaning blade 19 having a base end fixed to the cleaning case 17, and a toner unloading device that discharges untransferred toner in the cleaning case out of the case 17. And a member 20. The cleaning blade 19 constitutes an example of a cleaning member for removing transfer residual toner on the surface of the image carrier, and the cleaning member comes into contact with the surface of the image carrier to scrape the transfer residual toner adhered to the surface of the image carrier. Remove and remove. The amount of the transfer residual toner removed from the surface of the image carrier by the cleaning device is, for example, about 15 to 25% of the amount of the toner supplied to the developing case 4 and used. Instead of the illustrated type of cleaning device, another type of cleaning device such as a cleaning device having a plurality of cleaning members or a magnetic brush cleaning device may be appropriately employed.

As described above, the illustrated image forming apparatus includes:
An image carrier 1, a latent image forming means for forming an electrostatic latent image on the surface of the image carrier, a developing device 3 for developing the electrostatic latent image to form a toner image on the surface of the image carrier, A transfer device 11 for transferring the toner image onto a transfer material; and a cleaning device 16 for removing transfer residual toner adhering to the surface of the image carrier that has passed a transfer position where the transfer device 11 forms a toner image on the transfer material. And a toner recycling apparatus 2 described below.
6.

The toner recycling device 26 illustrated in FIG.
Has a toner guide tube 21 extending above the developing device 3 from the cleaning device 16 and through which untransferred toner passes, and a toner conveying screw 22 disposed in the toner guide tube 21. A toner discharge hole 23 is formed in the upper portion of the toner guide tube. The toner conveying screw 22 is an example of a toner conveying member that conveys the transfer residual toner in the toner guide tube 21.

The transfer residual toner scraped and removed from the surface of the image carrier by the cleaning blade 19 falls into the cleaning case 17, and the dropped transfer residual toner is moved by the rotating toner carrying member 20 to the toner guide tube 2.
1 is transported. At this time, the toner conveying screw 22 in the toner guide tube 21 is rotationally driven by a driving device (not shown), whereby the transfer residual toner TA sent into the toner guide tube 21 is removed. Inside the toner discharge hole 2
3 and fall into the toner container 8. The transfer residual toner that has fallen into the toner container 8 is mixed with the toner T in the toner container 8, and the mixed toner is supplied to the developing case 4 as described above so that the electrostatic latent image is visualized. Provided. Since the transfer residual toner is reused in the developing device 3 as described above, the amount of toner consumption can be reduced.

The untransferred toner TA removed from the image carrier 1 as described above is returned to the developing device 3. However, not all the untransferred toner TA is returned to the developing device 3; Only the toner is returned to the developing device 3 and reused, and the remaining transfer residual toner is discharged out of the toner guide tube from the outlet 24 at the end of the toner guide tube 21, and is transferred to the toner tank 2.
5 is housed in the toner housing section. The transfer residual toner stored in the toner tank 25 is finally discarded or regenerated. As described above, the toner recycling device 26 returns a part of the transfer residual toner removed from the image carrier 1 by the cleaning device 16 to the developing device 3 and transports another transfer residual toner to the toner storage unit. Eggplant

In order to reuse the transfer residual toner removed from the image carrier, it is conventionally known to provide a toner recycling device for returning the transfer residual toner to the developing device. At that time, the conventional toner recycling device is configured to return all the transfer residual toner removed from the image carrier to the developing device. By the toner including the transfer residual toner returned to the developing device by the toner recycling device,
When the electrostatic latent image formed on the image carrier is visualized, as described above, a large number of whisker images are generated on the background due to the paper dust contained in the transfer residual toner. And the problem that many fireflies occur in the toner image on the transfer material is unavoidable.

In order to clarify the causes of the above-mentioned drawbacks and their countermeasures, the present inventor has determined that the toner discharge hole 2 formed in the toner guide tube 21 of the toner recycling device 26 shown in FIG.
3, it was examined how the amount of paper dust in the developing device 3 increases when all the transfer residual toner is returned to the developing device 3 as in the conventional image forming apparatus. . As a result, the following facts were clarified.

First, paper powder is attached to the transfer paper P sent between the transfer belt 14 and the image carrier 1, and when the transfer paper P comes into contact with the surface of the image carrier 1, P
Part of the paper dust adheres to the surface of the image carrier 1. The remaining paper dust adheres to the transfer paper P and the transfer belt 14 and is carried away. The paper dust adhering to the transfer belt 14 is
The toner is removed from the transfer belt 14 by a cleaner not shown in FIG.

The paper dust adhering to the surface of the image carrier is removed by the cleaning device 16 together with the transfer residual toner.
Then, the paper dust is mixed with the transfer residual toner and transported by the toner recycling device 26.
In this case, all of the transfer residual toner is returned to the developing device 3 together with the paper dust. When a toner image is formed on the surface of the image carrier by the developing device 3, paper dust also adheres to the surface of the image carrier, and when the attached paper dust passes through the transfer position of the toner image, one of the paper dust is removed. The part is on the transfer paper or the transfer belt 14.
Moving up, the other paper dust remains attached to the surface of the image carrier 1. The paper dust remaining on the surface of the image carrier is removed from the surface of the image carrier by the cleaning device 16 together with the paper dust newly transferred from the transfer paper P to the surface of the image carrier.

As described above, the paper dust is supplied to the cleaning device 16 and the toner guide tube 21 of the toner recycling device 26.
The toner circulates through a recycled toner path composed of the toner container 8, the developing case 4, and the surface of the image carrier 1, during which some paper dust is taken off by the transfer paper and the transfer belt, and the image is transferred from the transfer paper P to the transfer paper P. New paper powder is always supplied to the carrier 1. Therefore, as the number of sheets passed, that is, the number of sheets of transfer paper passing through the transfer position of the toner image increases, the amount of paper dust passing through the recycled toner path gradually increases, and the amount of paper dust in the developing device 3 increases. Increase.

However, the amount of paper dust passing through the recycled toner path, that is, the amount of paper dust present in the developing device 3 is:
It has been found that the saturation does not increase any more, but increases when the number of passed sheets reaches a certain number. FIG. 2 is a graph for explaining this fact, in which the horizontal axis indicates the number of sheets passed, and the vertical axis indicates the amount (weight m) of paper powder passing through the recycled toner path while passing 1,000 sheets of transfer paper.
g), that is, the amount of circulating paper powder passing through the recycled toner path per 1000 sheets of transfer paper. For example, at one location of the toner guide tube 21, the toner guide tube 21
Considering the cross section, the amount of paper dust passing through the cross section while 1000 transfer papers P pass through the transfer position is the amount of circulating paper dust. When the number of sheets passed in FIG.
Has no paper dust. Also, “K” in FIG.
0 ”(the same applies to FIGS. 3 to 5 and FIG. 18). The solid line E in FIG. 2 shows the result when the recycled paper is used as the transfer paper P, and the chain line F shows the result when the transfer paper P made of high quality paper is used.

As can be seen from FIG. 2, since the amount of paper dust that migrates from each transfer paper to the surface of the image carrier varies depending on the type of transfer paper P, the above-mentioned amount of circulating paper dust also differs. In this case as well, the amount of circulating paper dust increases with an increase in the number of passed sheets. However, when the number of passed sheets reaches a certain number, the amount of circulating paper dust does not increase, and the amount of circulating paper dust saturates. The amount of paper dust present in the device 3 also saturates. When the amount of circulating paper dust increases and the amount of paper dust existing in the developing device 3 increases, as described above, an abnormal image, that is, a whisker image or fireflies is significantly generated. In the example shown in FIG. 2, the amount of circulating paper powder is 15 mg /
When the number of images exceeds K, the occurrence of abnormal images becomes remarkable, and this becomes very noticeable visually.

As described above, all of the untransferred toner collected by the cleaning device 16 is returned to the developing device 3, and the paper dust contained therein is circulated. Although the amount increases, the amount of circulating paper dust eventually saturates. The reason is considered as follows.

The rate at which the paper dust adhered to the surface of the image carrier 1 from the developing device 3 migrates to the transfer paper P or the transfer belt 14 and is taken away is very small. It passes through the transfer position of the toner image while being attached to the body. For example, 92% of the paper dust adhered to the image carrier from the developing device 3 remains adhered to the image carrier, and the other 8%.
% Adheres to the transfer paper P and the transfer belt 14 and is carried away. A certain small percentage of paper dust is carried away on transfer paper or the like. On the other hand, the amount of paper dust newly supplied from the transfer paper P to the image carrier is substantially constant. Therefore, as long as the number of sheets passed is small, the amount of paper dust newly attached to the image carrier 1 from the developing device 3 moves to the transfer paper P or the transfer belt 14 and is carried away. The ratio of the amount of paper powder newly supplied to the body 1 is large. Therefore, the amount of circulating paper dust gradually increases, and the amount of paper dust existing in the developing device 3 also increases. However, when the number of paper passing increases and the amount of circulating paper dust increases, the absolute amount of the paper dust transferred to the transfer paper P or the transfer belt 14 among the paper dust adhered to the image carrier 1 from the developing device 3 is determined. Since the amount increases, the amount of paper dust is balanced with the amount of paper dust newly transferred from the transfer paper P to the surface of the image carrier, and it is considered that the amount of circulating paper dust is saturated.

As described above, the toner recycling device 26
When all of the untransferred toner is returned to the developing device, the amount of paper dust in the developing device 3 is saturated,
Since the amount is considerably large, when a toner image is formed on the image carrier with the toner mixed with the paper dust, the occurrence of an abnormal image becomes remarkable. This is a drawback of a conventional image forming apparatus having a toner recycling device.

On the other hand, in the image forming apparatus of the present embodiment described above with reference to FIG.
As a result, only a part of the transfer residual toner removed from the image carrier 1 is returned to the developing device 3 so that other transfer residual toner is not reused. With this configuration, the developing device 3
Therefore, the amount of paper dust existing in the image can be greatly reduced, and the occurrence of an abnormal image can be effectively suppressed. In order to clarify such effects, experimental examples performed by the present inventors will be described.

In the image forming apparatus shown in FIG. 1, the cleaning device 16 moves the toner guide tube 2 per unit time.
When the weight of the transfer residual toner fed to the developing unit 1 is T1, and the weight of the transfer residual toner per unit time returned to the developing device 3 is T2, a value represented by T2 / T1 is called a recycling rate. I do. FIG. 3 shows an image forming operation using the image forming apparatus of the present embodiment shown in FIG. Are the results of experiments showing how the paper powder weight changes. Recycled paper was used as the transfer paper P.

The recycling rate of 100% in FIG.
It means that all the transfer residual toner is returned to the developing device 3,
This corresponds to a conventional image forming apparatus provided with a toner recycling device. A recycling rate of 0% means that all the transfer residual toner is discharged to the toner tank 25.
This corresponds to a conventional image forming apparatus without a toner recycling device. When the recycling rate is 100%, the saturation value of the amount of circulating paper dust is 25 mg / K sheets, which coincides with the saturation value of the amount of circulating paper dust indicated by the solid line E in FIG.

Here, as can be seen from FIG. 3, for example, the recycling rate is 90%, that is, one of all the transfer residual toners.
The transfer residual toner of 0% is discharged to the toner tank 25, and the transfer residual toner of 90% of the total transfer residual toner is developed.
When recycled and reused, the saturation value of the amount of circulating paper dust is about 10 mg / K sheets, which is much lower than the saturation value of 25 mg / K sheets when the recycling rate is 100%. are doing. When the recycle rate reaches 80%, the saturation value of the amount of circulating paper powder becomes about 6 mg / K, which is also rapidly decreasing. As described above, a small amount of the transfer residual toner of the entire transfer residual toner is not returned to the developing device 3 but is discharged to the toner tank 25, and the saturation value of the circulating paper dust amount can be greatly reduced. it can. FIG. 4 is an experimental result showing the relationship between the number of passed sheets and the amount of circulating paper dust when recycled paper is used as the transfer paper P and the recycling rate is set to 45%. As can be seen from this figure, when the number of passed sheets exceeds a certain value, the amount of circulating paper dust is saturated, and the saturated value is greatly reduced to about 1/15 of that in the case of the solid line E in FIG. I understand.

The above phenomenon is presumed to occur as follows.

It is assumed that the amount of paper dust in the recycled toner path is saturated, and the amount of circulating paper dust at this time is Wmg / K sheets. In this state, it is assumed that the amount of paper dust newly supplied from the transfer paper P to the image carrier 1 (weight of paper powder per 1,000 transfer papers) is 2 mg / K, and 8% of the amount of paper dust adhering to the transfer paper (the weight of paper dust per 1,000 sheets of transfer paper) adheres to the transfer paper P or the transfer belt 14 passing through the transfer position and is carried away, and another 92% of the paper dust is removed. Assume that it remains attached to the image carrier surface. Then, assuming that the recycling rate is y%, the amount of circulating paper powder W is Wmg /
K sheets = (2 mg / K sheets + 0.92 × Wmg / K sheets) × y
/ 100. Here, for example, if y = 100%, W = 25 mg / K sheets, which matches the saturation value (25 mg / K sheets) when the recycling rate is 100% in the graph shown in FIG. Also, y = 90%
, The Wmg / K sheet becomes about 10 mg / K sheet, which is also consistent with FIG.

As described above, a part of the transfer residual toner removed from the image carrier is returned to the developing device 3 for reuse, and another transfer residual toner is conveyed to the toner tank 25.
The amount of paper dust in the developing device 3 can be significantly reduced, thereby effectively suppressing a problem that an abnormal image is formed on the transfer paper P. As can be seen from the above description, by setting the recycling rate to, for example, 50%, the toner yield, that is, the toner for one toner bottle set in the toner storage unit, is compared with the case where the recycling rate is 0%. Can increase the number of copies that can be made by about 10%, and can reduce the saturation value of the amount of circulating paper dust to 1/10 or less as compared with the case where the recycling rate is 100%. In this way, both the effect of reducing the amount of toner consumption and the effect of reducing the occurrence of abnormal images can be achieved.

By the way, the image forming apparatus is configured to return the transfer residual toner to the developing device 3 at a certain recycling rate and to convey the other transfer residual toner to the toner tank 25, and to use the image forming apparatus exclusively in this mode. May be done,
Some users who use the image forming apparatus want to reduce the amount of toner consumption as much as possible even if the image quality of the image formed on the transfer paper P is somewhat poor. Others want to prioritize improving image quality. Alternatively, some people want to reduce the amount of toner consumption and also achieve a somewhat higher image quality.

Therefore, the toner guide tube 21 is supported so as to be rotatable around its axis, and as shown in FIG.
In addition to forming the above-described toner discharge hole 23 in the toner guide tube 21, an outlet 27 having a hole having a much larger opening area than the toner discharge hole 23 may be formed.

For an image forming apparatus of a user who wants to give top priority to reduction of toner consumption, as shown in FIG.
The toner guide tube 21 is rotated so that 7 faces substantially downward. As a result, the transfer residual toner TA transported in the toner guide tube 21 entirely falls downward through the large opening outlet 27 and is returned to the developing device 3. This allows
Since all the transfer residual toner TA is reused in the developing device 3, the toner consumption can be effectively reduced. However, in this case, an abnormal image is likely to occur.

As shown in FIG. 8, for the image forming apparatus of the user who wants to prioritize the improvement of the image quality, as shown in FIG. 8, the toner guide tube portion where neither the toner discharge hole 23 nor the outlet 27 is formed is directed downward. Then, the toner guide tube 21 is rotated. Thus, all the transfer residual toner TA conveyed through the toner guide tube 21 is discharged to the toner tank 25 shown in FIG. For this reason, the transfer residual toner is not used in the developing device 3 at all, so that a high quality image can be formed.
However, in this case, the amount of toner discharged to the toner tank 25 increases, and the amount of toner consumption increases.

For an image forming apparatus of a user who desires both improvement of image quality and reduction of toner consumption, as shown in FIG. 6, the toner discharging hole 23 is directed substantially downward. By rotating the guide tube 21, a part of the transfer residual toner may be returned to the developing device 3 as described above, and the other toner may be transported to the toner tank 25.

As described above, the entirety of the untransferred toner removed from the image carrier 1 by the cleaning device 16 is returned to the developing device 3, or the entirety of the untransferred toner is conveyed to the toner storage unit. The toner recycle device 26 is configured so that a part of the transfer residual toner can be returned to the developing device 3 and another transfer residual toner can be transported to the toner storage unit, thereby responding to various demands of users. be able to.

Further, as described above, the toner guide tube 21 is rotatably supported, and by rotating the toner guide tube 21 around the axis X, the toner discharge hole 2 is formed.
The amount of the transfer residual toner discharged from the printer 3 can be adjusted. Thus, by configuring the ratio of the amount of the transfer residual toner sent to the developing device and the toner storage unit to be adjustable, the transfer residual toner can be returned to the developing device 3 at a desired recycling rate. .

By the way, in the example shown in FIG. 1, the transfer residual toner discharged from the toner discharge hole 23 formed in the toner guide
1 is configured to drop the untransferred toner discharged from the outlet 24 into the toner tank 25. On the contrary, the untransferred toner discharged from the toner outlet 23 is transferred to the developing device 3, and The transfer residual toner discharged from the outlet 24 at the end opening of the toner guide tube 21 may be dropped into the developing device 3.

The point is that the toner recycling device has a toner guide tube through which the transfer residual toner passes, and a toner transport member that transports the transfer residual toner in the toner guide tube. When a part of the removed transfer residual toner is returned to the developing device and another transfer residual toner is conveyed to the toner storage unit, the transfer residual toner sent to the development device or the toner storage unit is transferred from the toner guide tube. That is, a falling toner discharge hole is formed. This makes it possible to distribute and transfer the transfer residual toner to the developing device 3 and the toner storage unit with a simple configuration.

As described above, by adjusting the angular position of the toner discharge hole 23 by rotating the toner guide tube 21, the amount of the transfer residual toner discharged from the toner discharge hole 23, that is, the recycling rate is adjusted. Can be.
At this time, the opening area of the toner discharge hole 23 can be appropriately set. However, if the opening area of the toner discharge hole 23 is too large, the toner guide tube 2 is set at an angular position where a desired recycling rate can be obtained.
It is not easy to rotate 1. For this reason, it is preferable that the opening area of the toner discharge hole 23 is set as small as possible within a range where the transfer residual toner can pass therethrough. Hereinafter, the reason will be clarified.

FIG. 10 shows the toner discharge holes 23 shown in FIG.
FIG. 11 is a perspective view of a toner guide tube 21 having a toner discharge hole 123 having an opening area larger than the toner discharge hole 23 shown in FIG.
FIG. 13 is a perspective view of the toner guide tube 21 shown in FIG. 11 and 13, the illustration of the outlet 27 shown in FIGS. 6 to 8 is omitted (the same applies to FIGS. 9 and 12).

Here, assuming that the circumferential direction of the toner guide tube orthogonal to the direction of the axis X of the toner guide tube 21 is the horizontal direction, the toner discharge holes 23, 1 shown in FIGS.
The angle position of the toner discharge holes 23 and 123 when the center CL in the horizontal direction of the toner discharge nozzle 23 is located at the lowest position is set to 0 °, and the toner guide tube 21 is moved with reference to this position as shown in FIG.
In addition, it is assumed that the angular position of the center CL of the toner discharge holes 23 and 123 when rotated clockwise in FIG.

When the angular position of the toner discharge hole 123 is determined as shown in FIG. 11, since the opening area of the toner discharge hole 123 is large, its width h1 in the horizontal direction is transferred to the toner guide tube 21. The width becomes larger than the width H of the residual toner TA in the horizontal direction. Therefore, a large amount of the transfer residual toner TA in the toner guide tube 21 falls downward through the toner discharge hole 123. On the other hand, when the toner guide tube 21 having the toner discharge hole 123 is rotated to the plus side by an angle θ as shown in FIG. It falls on the discharge hole 123 and falls downward from here.
The other part is located off the toner discharge hole 123.
For this reason, the amount of the transfer residual toner TA that falls downward through the toner discharge hole 123 is significantly reduced as compared with the state of FIG.

On the other hand, since the opening area of the toner discharge hole 23 of the toner guide tube 21 shown in FIG. 6 is small, when the toner discharge hole 23 is at the position shown in FIG.
Is smaller than the horizontal width H of the untransferred toner TA in the toner guide tube 21, and the untransferred toner TA covers the entire toner discharge hole 23. Next, as shown in FIG. 9, when the toner guide tube 21 is rotated by an angle θ to the plus side, the opening area of the toner discharge hole 23 is small. Will remain covered. For this reason,
Even if the toner guide tube 21 is rotated from the angular position shown in FIG. 6 to the position shown in FIG. 9, the amount of the transfer residual toner TA discharged from the toner discharge hole 23 only slightly changes.

FIG. 5 shows a toner guide tube 21 having a toner discharge hole 23 having a diameter of 4 mm and a toner guide tube 21 having a rectangular toner discharge hole 123 having a size of 8 mm × 15 mm.
9 shows an experimental result of examining how the ratio of the transfer residual toner to the developing device 3 out of the total transfer residual toner, that is, the recycling rate, changes when the toner is rotated from the position of °. The solid line I is the experimental result of the toner guide tube having the toner discharge hole 123 having a large opening area, and the chain line J is the experimental result of the toner guide tube having the toner discharge hole 23 having a small opening area. Although the toner outlets 23 and 123 of the toner guide tube 21 used in this experiment are slightly different from those shown in FIGS. 6 and 11, the opening area of the toner outlet 23 is It is common that the opening area is smaller than the opening area.

As can be seen from the solid line I in FIG. 5, in the case of the toner guide tube 21 having the toner discharge hole 123 having a large opening area, the angle position is set to the position of 0 ° and the position of 180 °, thereby enabling the recycling. The recycling rate can be 100% or 0%, but when the toner guide tube 21 is rotated from the position of 10 ° to the position of 30 °, the recycling rate sharply decreases. Therefore, for example, when the recycling rate is to be set to 50%, the angular position of the toner guide tube 21 is set to 20%.
Even if it is set at a position near °, the recycling rate may not be exactly 50% due to variations in parts.

On the other hand, the toner discharge hole 2 having a small opening area
In the case of the toner guide tube 21 having 3 as shown in the chain line J in FIG. 5, when its angular position is rotated from the position of 0 ° to the position of 40 °, the recycling rate gradually increases,
The rate of change is very small. For this reason, even if there is some variation in parts, an accurate recycling rate can be set by adjusting the angular position of the toner guide tube 21. For example, when the recycling rate is set to 50%, the angular position of the toner guide tube 21 having the toner outlet 23 may be set to a position near 20 °.

As can be seen from the dashed line J in FIG. 5, in the case of the toner guide tube 21 having the toner discharge hole 23 having a small opening area, the angle position of the toner discharge hole 23 is set to the position of 0 °.
That is, the recycle rate is not maximum when it is positioned vertically downward, and is maximized when its angular position is approximately 40 °. This is because the toner conveying screw 22 (FIG. 1) in the toner guide tube 21 rotates in the direction of arrow K in FIG. 6, and the transfer residual toner TA is pushed in the direction K by the toner conveying screw 22. This is because the transfer residual toner TA is conveyed. As described above, the angular position of the toner discharge hole 23 at which the recycling rate is maximized depends on the rotation speed of the toner conveying screw 22, the pitch of the screw, the size of the toner discharge hole 23, the inner diameter of the toner guide tube 21, the transfer residual toner. Therefore, it is desirable to determine the angular position of the toner discharge hole 23 at which the recycling rate is maximized from the experimental results using the actual structure of the toner recycling device.

As described above, by setting the width h2 of the toner discharge hole 23 in the horizontal direction to be smaller than the width H of the transfer residual toner passing through the toner discharge hole 23, a desired recycling rate can be obtained. Can be determined. Further, when the opening area of the toner discharge hole 23 is set to 30 mm2 or less, preferably 3 mm2 or less, the above-described effect can be further ensured. This has been confirmed by a number of experiments.

When a plurality of toner discharge holes 23 formed as described above are formed along the direction of the axis X of the toner guide tube 21, the amount of transfer residual toner discharged from the toner discharge holes 23 becomes extremely large. The above-described effect can be further ensured while preventing the decrease.

Further, as shown in FIG. 14, the toner discharge hole 23 formed as described above may be formed so that the opening area thereof is constant outward in the radial direction of the toner guide tube 21. Good, but in the case of the toner discharge hole 23,
Transfer residual toner adheres and accumulates on the edge portion 23A,
As a result, the apparent diameter of the toner discharge hole 23 becomes small, and it becomes difficult for the transfer residual toner to pass therethrough, and the recycling rate may decrease with time. In contrast,
As shown in FIG. 15, the opening area of the toner discharge hole 23 is
When the toner discharge hole 23 is formed in a tapered shape so as to gradually increase toward the outside in the radial direction of the toner guide tube 21, the edge 23A of the toner discharge hole 23 on the inner side of the toner guide tube has an acute angle. As a result, the transfer residual toner hardly adheres here, and the recycling rate can always be maintained at a desired value.

Further, the shape of the toner discharge hole 23 formed as described above can be an appropriate shape such as a circle, an ellipse, an oval, or a rectangle. This toner discharge hole 23 is
As shown in FIG. 5, the width of the toner discharge hole 23 is reduced along the rotation direction K of the toner transport screw 22 (FIG. 1). Transfer residual toner accumulates in the portion 23B, which may lower the recycling rate.

On the other hand, as shown in FIG. 17, the toner discharge hole 23 is formed in a rectangular shape, and the two parallel sides 23C extend substantially in the direction of the axis X of the toner guide tube 21. When the toner discharge screw 23 is disposed, the width of the toner discharge hole 23 becomes constant in the rotation direction K of the toner conveying screw, so that it is difficult for the transfer residual toner to be deposited in the toner discharge hole 23. This makes it possible to always maintain the recycling rate at a desired value.

It is preferable to appropriately combine the components of the toner discharge hole 23 described above. In particular, the toner discharge hole 23 is made rectangular as described above, and its width (opening area) is set radially outward of the toner guide tube. When the toner discharge hole 23 is formed in a tapered shape so as to gradually increase toward, the accumulation of transfer residual toner in the toner discharge hole 23 can be more effectively prevented.

As described above, the toner guide tube 21 is rotatably supported around its axis X,
By rotating 1, the recycle rate can be set to a desired value. At that time, the toner guide tube 21
May be manually rotated to adjust the position of the toner discharge hole 23, or the toner guide tube 21 may be automatically rotated. For example, as shown in FIG. 1, a gear 28 is fixed to the outer peripheral surface of the toner guide tube 21, and an output gear 30 of a driving unit including a motor 29 supported by the image forming apparatus main body is meshed with the gear 28.
By the operation of the motor 29, the gears 30 and 28 are rotated, whereby the toner guide tube 21 is rotated around its axis X to adjust the angular position of the toner discharge hole 23,
A desired ratio of the transfer residual toner among all the transfer residual toners is returned to the developing device 3.

As described above, the toner guide tube 21 is rotatably supported around its axis X, and the driving means for rotating the toner guide tube around its axis X is provided. It is possible to set the recycling rate to a desired value.

In the image forming apparatuses having the above-described configurations, when the image ratio of the toner image formed on the image carrier 1 (the ratio of the area of the toner image to the total surface area of one transfer sheet) increases, the cleaning device 16, the amount of transfer residual toner removed from the image carrier increases, and the toner guide tube 21
Is increased, the amount of transfer residual toner conveyed is increased. In this case, the amount of the transfer residual toner that does not fall from the toner discharge hole 23 increases, and the amount of the transfer residual toner conveyed to the toner tank 25 increases. For this reason, the recycling rate becomes lower than a desired value set in advance. When the image ratio of the toner image decreases, the recycling rate increases, and in this case also, the recycling rate deviates from a target value.

Therefore, as is well known per se, the amount of untransferred toner is estimated by reading the image ratio of the original document by a control device (not shown), and when the image ratio is higher than a predetermined value. When the image ratio is lower than a predetermined value, the toner guide tube 21 is automatically rotated so that the amount of the transfer residual toner discharged from the toner discharge hole 23 increases. If the toner guide tube 21 is automatically rotated so that the amount of the remaining transfer toner decreases, the recycling rate can always be maintained at a desired constant value regardless of the image ratio.

Generally speaking, according to the image ratio of the toner image formed on the image carrier, the ratio of the amount of the transfer residual toner sent to the developing device and the toner transfer portion to the toner container can be automatically adjusted. Make up.

When the toner guide tube 21 rotatably supported around the axis X is used as in the example shown in FIG. 1, the toner ratio is determined by the image ratio of the toner image formed on the image carrier 1. In order to adjust the position of the toner discharge hole 23 in the rotation direction of the toner guide tube, a drive control means for rotating the toner guide tube 21 around the axis X may be provided. In the illustrated example, the motor 29 and a control device (not shown) constitute the above-described drive control means.

In each of the above-described configurations, when the temperature in the image forming apparatus, particularly, the temperature of the surface of the image carrier increases,
The agglomeration degree of the transfer residual toner removed from the image carrier increases, the amount of the transfer residual toner that does not fall from the toner discharge hole 23 increases, and the amount of the transfer residual toner returned to the developing device 3 decreases. Has been confirmed by experiments. Conversely, when the temperature in the image forming apparatus, particularly the temperature of the surface of the image carrier decreases, and the degree of cohesion of the transfer residual toner decreases, the recycling rate increases, and in any case, the recycling rate decreases from the target value. It shifts.

Then, the temperature in the image forming apparatus is detected, and
When the temperature becomes higher than the predetermined temperature, the toner guide tube 21 is automatically rotated in a direction in which the amount of the transfer residual toner discharged from the toner discharge hole 23 is increased, and conversely, the temperature in the image forming apparatus is reduced. Is lower than the predetermined temperature, the toner guide tube 21 is automatically rotated so that the amount of the transfer residual toner discharged from the toner discharge hole 23 decreases.
The recycling rate can always be maintained at a desired constant value without being affected by the temperature of the image forming apparatus. The temperature in the image forming apparatus is detected, the degree of aggregation of the transfer residual toner is predicted from the detected temperature, and the angular position of the toner discharge hole 23 of the toner guide tube 21 is adjusted accordingly.
Keep the recycling rate constant.

In general, the configuration is such that the ratio of the amount of the transfer residual toner sent to the developing device and the amount of the transfer residual toner sent to the toner storage unit can be automatically adjusted according to the temperature in the image forming apparatus.

When the toner guide tube 21 rotatably supported around the axis X is used as in the example shown in FIG. 1, the temperature in the image forming apparatus, particularly the temperature on the surface of the image carrier, is reduced. A temperature sensor 31 for detecting the temperature is provided, and based on the detection result of the temperature sensor 31, the toner guide tube 2 is adjusted to adjust the position of the toner discharge hole 23 in the rotation direction of the toner guide tube.
It is sufficient to provide drive control means for driving the rotation of the motor 1 around its axis X.

In the image forming apparatus described above, the toner recycling device 26 returns a part of the transfer residual toner to the developing device 3 and transfers the other transfer residual toner to the toner tank 2.
The toner recycle device 26 is used to transport the entire transfer residual toner removed from the image carrier 1 by the cleaning device 16 to the developing device 3.
, And a non-recycle mode in which the entirety of the untransferred toner is transported to the toner storage unit may be alternately executed.

As described above, the toner recycling device 26 of this example also has the toner guide tube 21 through which the transfer residual toner TA passes.
And a toner conveying member configured as a toner conveying screw 22 that conveys the transfer residual toner TA in the toner guide tube. The toner guide tube 21 is provided with an outlet for the transfer residual toner sent to the developing device 3. (Hereinafter, referred to as a first outlet) 27 (FIG. 7), and an outlet (hereinafter, referred to as a second outlet) of the transfer residual toner to be sent to the toner storage unit including the toner tank 25.
24 (FIG. 1).

When the recycle mode is executed, the angular position of the toner guide tube 21 is set so that the first outlet 27 faces substantially downward as shown in FIG. As a result, all the transfer residual toner T conveyed in the toner guide tube 21
A is sent from the first outlet 27 to the developing device 3. On the other hand, when the non-recycle mode is executed, FIG.
As shown in FIG. 8, the motor 29 shown in FIG.
The toner guide tube 2 is formed so that the toner guide tube portion where the toner outlet hole 23 and the first outlet 27 are not formed faces downward.
1 is rotated. As a result, all the transfer residual toner TA conveyed in the toner guide tube 21 is
From the second outlet 24 to the toner storage unit including the toner tank 25. The control unit (not shown) controls the toner recycle device 26 so that the mode is switched between the recycle mode and the non-recycle mode every time the image forming operation is performed a predetermined number of times, that is, every time a sheet is passed.

FIG. 18 is a graph for explaining the relationship between the number of sheets passed and the amount of circulating paper dust when the recycle mode and the non-recycle mode are alternately performed, and FIG. 19 is a flowchart thereof. In this example, when the image forming apparatus is shipped to the user, the image forming apparatus is set so that the first outlet 27 faces downward so that the recycling mode can be executed. Therefore, the first type shown in FIG.
In the step (I), the recycle mode is executed (S1 in FIG. 19). Thus, the amount of circulating paper dust gradually increases with an increase in the number of passed sheets. This recycle mode is stopped at the time of the specified number of sheets N1 before the occurrence of an abnormal image becomes noticeable, and at this time N1, the toner guide tube 21 is driven to rotate, and the second stage (II) is started. The mode is switched to the non-recycling mode (S2, S3 in FIG. 19).
By executing the non-recycle mode in this manner, the amount of circulating paper dust gradually decreases. In the example shown in FIG. 18, N2 is no longer present in the recycled toner path.
The non-cycle mode of the second stage (II) is continued until the number of sheets passed. When the number of passed sheets reaches the specified N2,
The process is switched to the third stage (III) (S4, S4 in FIG. 19).
5) At this stage, exactly the same recycle mode as in the first stage (I) is performed. Subsequently, in the fourth stage (IV), the same non-recycle mode as that in the second stage (II) is executed, and thereafter, such operation is repeated.

According to the above-described configuration, the recycle mode is executed, so that the toner consumption can be reduced. Further, the mode is switched to the non-recycle mode before the abnormal image becomes conspicuous. Generation can be effectively suppressed. In addition, since the transfer residual toner having a high content of paper dust is discharged to the toner tank 25, the efficiency of discharging the paper dust can be improved.

In the examples shown in FIGS. 18 and 19, by executing the non-recycle mode, the printer shifts to the recycle mode after all the paper dust is discharged from the recycle toner path. It can be suppressed effectively. The time required to discharge all the paper dust from the recycled toner path is determined by the length of the path.

Switching from the recycle mode to the non-recycle mode and vice versa are performed every predetermined number of image forming operations, that is, every time a predetermined number of sheets are passed. Depends on the paper quality. For this reason, it is preferable that the user can input and set the number of sheets passed for switching the mode, that is, the predetermined number of times of image formation. For example, by operating the operation unit of the image forming apparatus, the predetermined number of times can be input. By providing the input means for inputting the predetermined number of times, the user can freely set the predetermined number of times of switching between the recycle mode and the non-recycle mode according to the paper quality of the transfer paper used by the user.

In the embodiment described above, the transfer residual toner is transferred to the developing device 3 by the toner outlet holes 23 and 123 and the first outlet 27 formed in the toner guide tube 21.
20 or the conveyance to the toner tank 25 is controlled, but as shown schematically in FIG. 20, the toner guide tube 21 branches into a tube 21A communicating with the developing device 3 and a tube 21B communicating with the toner tank 25. By providing a regulating member 32 at the branch portion and operating the regulating member 32 at a position indicated by a solid line, a chain line, or a broken line, the entire transfer residual toner is sent to the developing device 3, or all the transfer residual toner is removed. The toner may be transported to the toner tank 25 or the transfer residual toner may be transported to the developing device 3 and the toner tank 25 at a predetermined ratio.

The toner recycling device 26 of the above example is
It has a regulating member 32 operable to adjust the ratio of the amount of the transfer residual toner sent to the developing device 3 and the toner accommodating portion. At this time, a driving unit for driving the regulating member 32; For example, if a motor (not shown) is provided, it is possible to automatically switch the regulating member 32 to each position shown by a solid line, a chain line, or a broken line in FIG.

Also, in the case of the example shown in FIG. 20, the ratio of the amount of the transfer residual toner sent to the developing device 3 and the toner storage unit is changed according to the image ratio of the toner image formed on the image carrier. A drive control unit (not shown) for driving the regulating member 32 is provided for adjustment, and a temperature sensor (not shown in FIG. 20) for detecting the temperature in the image forming apparatus and a detection result of the temperature sensor are provided. A drive control means (not shown) for driving the regulating member 32 is provided to adjust the ratio of the amount of the residual toner to be transferred to the developing device 3 and the toner storage portion based on the predetermined amount. Can be maintained.

Further, when the image forming apparatus having the above-described configurations is provided with an impact applying device for applying an impact to the transfer residual toner conveyed by the toner recycling device 26,
It is possible to prevent a problem that the transfer residual toner conveyed by the toner recycling device 26 is clogged halfway. FIG.
An example of the impact applying device 33 is shown in FIG. The impact applying device 33 illustrated here includes a swing member 35 swingably supported via a pin 34 with respect to the image forming apparatus main body, a cam 36 driven to rotate, and a rear end of the swing member 35. Cam 3
6 and a spring 37 for pressing against the
Can contact the outer peripheral surface of the toner guide tube 21. The rotation of the cam 36 causes the swinging member 35 to swing in the direction of the arrow, whereby the leading end of the swinging member 35 intermittently collides with the toner guide tube 21, thereby transferring the toner in the toner guide tube 21. The residual toner is impacted.

The provision of the impact applying device as described above has an advantage that even when the toner discharge hole 23 formed in the toner guide tube 21 is formed small, the problem that the toner discharge hole 23 is clogged with toner can be prevented. .

Although the preferred various configurations of the present invention have been described above, the present invention is not limited to these configurations and can be variously modified. For example, a filter for removing paper dust from the transfer residual toner sent to the developing device may be provided. The present invention is also applied to an image forming apparatus in which a transfer material to which a toner image is transferred from an image carrier is formed of an intermediate transfer member and the toner image transferred to the intermediate transfer member is transferred to a final transfer material. be able to.

[0108]

According to the first aspect of the present invention, a part of the transfer residual toner is returned to the developing device, and the other transfer residual toner is conveyed to the toner storage section. Generation of an image can be effectively suppressed.

According to the second aspect of the present invention, any one of a user who gives priority to improving the image quality of an image, a user who gives priority to reducing the toner consumption, and a user who requests both the improvement of the image quality and the reduction of the toner consumption And an image forming apparatus that can meet the needs of the user.

According to the third aspect of the present invention, the image forming operation can be performed by giving priority to any of the toner consumption and the improvement of the image quality.

According to the fourth aspect of the invention, the desired recycling rate can be maintained even when the image ratio of the toner image formed on the image carrier greatly changes.

According to the fifth aspect of the present invention, a desired recycling rate can be maintained even when the temperature in the image forming apparatus fluctuates greatly.

According to the sixth aspect of the present invention, it is possible to send the transfer residual toner to the developing device and the toner storage unit by the toner recycling device having a simple configuration.

According to the seventh to eleventh aspects of the present invention, it is possible to correctly maintain a desired recycling rate.

According to the twelfth aspect, the toner guide tube can be automatically rotated, and the handling of the toner recycling device can be facilitated.

According to the thirteenth aspect, it is possible to automatically maintain a desired recycling rate even when the image ratio of the toner image formed on the image carrier fluctuates greatly.

According to the fourteenth aspect, even when the temperature in the image forming apparatus fluctuates greatly, it is possible to automatically maintain a desired recycling rate.

According to the invention according to claims 15 to 18,
By alternately performing the recycle mode and the non-recycle mode, it is possible to reduce the toner consumption and to effectively suppress the occurrence of an abnormal image.

According to the nineteenth aspect, the configuration of the toner recycling device can be simplified.

According to the twentieth aspect, the desired recycling rate can be maintained even when the image ratio of the toner image formed on the image carrier fluctuates greatly.

According to the twenty-first aspect, a desired recycling rate can be maintained even when the temperature in the image forming apparatus greatly changes.

According to the twenty-second aspect, it is possible to prevent the occurrence of a clogging phenomenon of the transfer residual toner.

[Brief description of the drawings]

FIG. 1 is a schematic partial cross-sectional view illustrating an example of an image forming apparatus.

FIG. 2 is a diagram illustrating that the amount of circulating paper dust is saturated.

FIG. 3 is a diagram illustrating that the amount of circulating paper dust can be rapidly reduced by preventing a part of the transfer residual toner from returning to a developing device.

FIG. 4 is a view similar to FIG. 2 when the recycling rate is 45%.

FIG. 5 is a diagram illustrating a relationship between an angular position of a toner guide tube and a recycling rate.

FIG. 6 is an enlarged sectional view taken along the line VI-VI of FIG. 1, in which the illustration of a toner conveying screw is omitted.

FIG. 7 is a sectional view showing a state when the toner guide tube shown in FIG. 6 is rotated.

FIG. 8 is a sectional view when the toner guide tube shown in FIG. 6 is rotated to an angular position different from that in FIG. 7;

FIG. 9 shows the angular position of the toner discharge hole of the toner guide tube in FIG.
It is sectional drawing at the time of rotating from the state of FIG.

FIG. 10 is a perspective view of the toner guide tube shown in FIG.

FIG. 11 is a sectional view of a toner guide tube having a toner discharge hole having a large opening area.

FIG. 12 is a sectional view when the toner guide tube shown in FIG. 11 is rotated.

FIG. 13 is a perspective view of the toner guide tube shown in FIG.

FIG. 14 is an enlarged sectional view showing a toner discharge hole.

FIG. 15 is an enlarged cross-sectional view illustrating a toner discharge hole according to another embodiment.

FIG. 16 is a cutaway perspective view of a toner guide tube having a circular toner discharge hole.

FIG. 17 is a cutaway perspective view of a toner guide tube having a rectangular toner discharge hole.

FIG. 18 is a diagram illustrating a relationship between the number of passed sheets and the amount of circulating paper dust when a recycle mode and a non-recycle mode are executed.

FIG. 19 is a flowchart when a recycle mode and a non-recycle mode are executed.

FIG. 20 is a schematic sectional explanatory view showing an example in which the transfer direction of the transfer residual toner is switched by a regulating member.

FIG. 21 is a view showing an impact applying device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier 3 Developing device 11 Transfer device 16 Cleaning device 21 Toner guide tube 23 Toner discharge hole 23c Side 24 Outlet 26 Toner recycling device 27 Outlet 31 Temperature sensor 32 Restriction member 33 Impact applying device H width h2 width TA Transfer remaining toner X Axis

Continued on the front page F term (reference) 2H027 DA13 DA45 DE07 FA30 FB07 FB19 2H034 BF00 CA02 CA04 CB01 2H077 AA12 AA37 AC16 DA18 DA47 DB25 GA02 GA03

Claims (22)

[Claims] An image carrier, a developing device for forming a toner image on the surface of the image carrier, a transfer device for transferring the toner image to a transfer material, and a transfer position where the toner image is transferred to the transfer material A cleaning device for removing transfer residual toner adhering to the surface of the image carrier that has passed through, and returning a part of the transfer residual toner removed from the image carrier by the cleaning device to the developing device; An image forming apparatus comprising: a toner recycling device that conveys residual toner to a toner storage unit. 2. An image bearing member, a developing device for forming a toner image on a surface of the image bearing member, a transfer device for transferring the toner image to a transfer material, and a transfer position where the toner image is transferred to the transfer material A cleaning device for removing transfer residual toner adhering to the surface of the image carrier that has passed through, and returning the entire transfer residual toner removed from the image carrier by the cleaning device to the developing device, or A toner recycling device capable of selecting whether to transport the entire toner to the toner storage unit or to return a part of the transfer residual toner to the developing device and transport another transfer residual toner to the toner storage unit. An image forming apparatus comprising: 3. The image forming apparatus according to claim 1, wherein a ratio of an amount of the transfer residual toner sent to each of the developing device and the toner storage unit is adjustable. 4. The apparatus according to claim 1, wherein the ratio of the amount of the transfer residual toner sent to the developing device and the amount of the transfer residual toner sent to the toner storage unit can be automatically adjusted according to the image ratio of the toner image formed on the image carrier. An image forming apparatus according to any one of claims 1 to 3. 5. The image forming apparatus according to claim 1, wherein the ratio of the amount of the transfer residual toner sent to the developing device and the amount of the transfer residual toner sent to the toner storage unit can be automatically adjusted according to the temperature in the image forming device. An image forming apparatus according to claim 1. 6. The toner recycling device includes a toner guide tube through which the transfer residual toner passes, and a toner transport member that transports the transfer residual toner in the toner guide tube, wherein the toner guide tube includes an image carrier. When a part of the transfer residual toner removed from the toner is returned to the developing device and another transfer residual toner is conveyed to the toner storage unit, the transfer residual toner sent to the developing device or the toner storage unit is transferred to the toner guide tube. The image forming apparatus according to any one of claims 1 to 5, wherein a toner discharge hole that falls from the toner discharge hole is formed. 7. When the circumferential direction of the toner guide tube orthogonal to the axial direction of the toner guide tube is defined as a lateral direction,
7. The image forming apparatus according to claim 6, wherein the width of the toner discharge hole in the horizontal direction is set smaller than the width of the transfer residual toner passing through the toner discharge hole in the horizontal direction. 8. An opening area of the toner discharge hole is 30 mm.
The image forming apparatus according to claim 7, wherein the number is set to 2 or less. 9. The image forming apparatus according to claim 7, wherein a plurality of the toner discharge holes are formed along an axial direction of the toner guide tube. 10. The toner discharge hole according to claim 7, wherein the toner discharge hole is formed in a tapered shape such that an opening area thereof gradually increases outward in a radial direction of the toner guide tube. Image forming device. 11. The toner discharge hole is formed in a rectangular shape.
The image forming apparatus according to any one of claims 7 to 10, wherein the two parallel sides extend substantially in the axial direction of the toner guide tube. 12. The toner guide tube according to claim 6, wherein said toner guide tube is rotatably supported around its axis, and said toner guide tube is provided with driving means for rotating said toner guide tube around its axis. An image forming apparatus according to any one of the above. 13. A toner guide tube rotating direction of the toner discharge hole according to an image ratio of a toner image formed on an image carrier, wherein the toner guide tube is rotatably supported around its axis. The image forming apparatus according to any one of claims 6 to 12, further comprising a drive control unit configured to rotationally drive the toner guide tube around its axis to adjust the position. 14. A toner sensor, wherein the toner guide tube is rotatably supported around its axis, and a temperature sensor for detecting a temperature in the image forming apparatus, and the toner discharge is performed based on a detection result of the temperature sensor. 7. A drive control means for rotating the toner guide tube around its axis so as to adjust the position of the hole in the toner guide tube rotation direction.
14. The image forming apparatus according to any one of claims 13 to 13. 15. An image carrier, a developing device for forming a toner image on the surface of the image carrier, a transfer device for transferring the toner image to a transfer material, and a transfer position where the toner image is transferred to the transfer material A cleaning device for removing transfer residual toner adhering to the surface of the image carrier that has passed through, a recycling mode for returning the entire transfer residual toner removed from the image carrier by the cleaning device to the developing device, An image forming apparatus comprising: a toner recycling device that alternately executes a non-recycle mode in which the entire toner is transported to a toner storage unit. 16. The toner recycling device has a toner guide tube through which the transfer residual toner passes, and a toner transport member that transports the transfer residual toner in the toner guide tube, wherein the toner guide tube is connected to the developing device. A first outlet for the transfer residual toner to be sent and a second outlet for the transfer residual toner to be sent to the toner storage section, and when the recycle mode is executed, all the transfer residual toner is 16. The image according to claim 15, wherein the image is sent from the first outlet to the developing device, and when the non-recycle mode is executed, all the transfer residual toner is sent from the second outlet to the toner storage unit. 17. Forming equipment. 17. A control unit for controlling a toner recycling apparatus such that the recycle mode and the non-recycle mode are switched every time a predetermined number of image forming operations are performed. An image forming apparatus according to claim 1. 18. The image forming apparatus according to claim 17, further comprising an input unit for inputting the predetermined number. 19. The toner recycling device according to claim 1, further comprising a regulating member operable to adjust a ratio of an amount of the transfer residual toner to be sent to the developing device and the toner storage unit. And the image forming apparatus according to any one of 15 to 18. 20. The regulating member is actuated to adjust the ratio of the amount of transfer residual toner sent to the developing device and the toner storage unit according to the image ratio of the toner image formed on the image carrier. 20. The image forming apparatus according to claim 19, further comprising a drive control unit that performs the control. 21. A temperature sensor for detecting a temperature inside the image forming apparatus, and a ratio of an amount of the transfer residual toner sent to each of the developing device and the toner storage unit is adjusted based on a detection result of the temperature sensor. 21. The image forming apparatus according to claim 19, further comprising a drive control unit for driving said regulating member. 22. The image forming apparatus according to claim 1, further comprising an impact applying device for applying an impact to the transfer residual toner conveyed by the toner recycling device.