JPH09197785A - Toner transport device and image forming device - Google Patents

Abstract

(57) [Abstract] [Purpose] A toner conveying device capable of conveying toner containing a magnetic material in an upward direction as well, improving image stability and reliability of the image forming apparatus main body, and suppressing mechanical noise to a low level. (EN) Provided is an image forming apparatus which is advantageous in terms of space and cost. [Structure] An electrostatic latent image is formed on a photoconductor 10 charged by a primary charger (charging means) 11, and the electrostatic latent image is developed by a developing device (developing means) 12 to be visible as a toner image. An image is formed through a process of forming an image and transferring the toner image onto a transfer material by a transfer / separation charging device (transfer means) 14, and the image is not transferred at the time of transferring the toner image.
In the image forming apparatus in which the transfer residual toner remaining on 0 is conveyed to the developing device 12 by the toner conveying device and reused, the toner conveying device includes a toner conveying path in which a plurality of electromagnets are arranged in close proximity to each other. It is configured to include control means for performing traveling wave magnetizing and demagnetizing on a plurality of electromagnets.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner conveying device provided with a means for removing foreign matter such as paper powder and external additives contained in transfer residual toner remaining on a photosensitive member after toner image transfer, and the toner conveying device. The present invention relates to an image forming apparatus including a device.

[0002]

2. Description of the Related Art In an image forming apparatus, as a toner for developing a latent image on a photoconductor and visualizing it,
A toner containing a magnetic material may be used.

Further, as a toner conveying means in the developing device and the cleaning device, a means for mechanically conveying the toner using a screw in a conveying pipe has been widely used in the image forming apparatus.

Further, there is conventionally known a technique of reusing the transfer residual toner remaining on the photosensitive member after the toner image is transferred onto a transfer paper or the like. In this technology, the transfer residual toner on the photoconductor is scraped and collected by a cleaning device, and the scraped transfer residual toner is conveyed to a developing device and is agitated with fresh toner to re-transfer residual toner. To use. Although simplified, a method has been proposed in which the transfer residual toner is adhered and transferred to the developing device as the photosensitive member advances without providing a cleaning device.

Since such transfer residual toner can be reused without making the transfer residual toner waste, it does not produce pollutants, reduces the toner consumption rate, and eliminates the waste toner from the apparatus main body. It has the merit of being able to save the human labor required for collection and disposal.

However, the transfer residual toner contains paper powder released from the transfer paper, and when this is directly conveyed to the developing device and mixed into the fresh toner, the toner regulating member and the developing roller used in the developing device. Paper dust is caught in the small area of
For this reason, a phenomenon occurs in which the toner is not discharged and the image density is deteriorated at an early stage. Alternatively, streak-shaped image deterioration occurs due to the non-uniform difference in toner discharge. for that reason,
A means for removing the paper dust from the transfer residual toner has been devised, but as a means for removing the paper dust, it is generally known to remove the transfer dust by passing the transfer residual toner through a fine mesh member. There is.

Many toners used in the image forming apparatus are composed of a toner main component for visualizing the latent image on the photoconductor and an external additive for assisting the latent image. Here, the external additive is used for the purpose of imparting desired charging characteristics to the main component of the toner, preventing adhesion between toners and imparting desired cohesiveness to the toner, and making the photoconductor in a preferable state. It is mixed with the main component of the toner in order to obtain some effects such as having a cleaning action to maintain it. This external additive may show a charging characteristic having a polarity opposite to that of the main component of the toner, and due to the difference in the charging characteristic, the mixing ratio of the external additive in the transfer residual toner collected by the cleaning device is similar to that of the fresh toner. It may fluctuate in comparison. Therefore, when the transfer residual toner is returned to the developing device and reused, a phenomenon such as a decrease in image density or fog occurs.Therefore, in the image forming apparatus that reuses the transfer residual toner, the kind and the composition of the external additive are naturally used. There is a restriction that the ratio is regulated, or the transfer residual toner cannot be used depending on the image forming apparatus.

[0008]

By the way, in the toner conveying means using a screw, there is no problem when the conveying direction is horizontal or downward, and the conveying ability is high, but when the conveying direction is upward, the conveying ability is high. There is a problem of falling.
That is, when the transfer residual toner is conveyed upward, the toner is apt to adhere to the screw due to the influence of gravity, and the toner conveying ability is extremely lowered as the screw idles. As a result, the desired toner transportability cannot be obtained, and the toner sticks to the periphery of the screw, causing clogging of the toner, which shortens the life of the main body. There is also a problem that the toner is compressed in the gap between the conveying pipe and the screw, and it is easy to form an aggregate of toner called an aggregate that is not suitable for development.

On the other hand, in consideration of toner reuse, many problems occur with respect to toner components. That is, if the degree of freedom in the type and blending ratio of the external additive, which is a toner component, is lost, it becomes difficult to fully exhibit the function of the external additive, and the overall characteristics of the toner deteriorate. There are problems that the charging property of the toner deteriorates, the degree of cohesion changes due to the environment and changes with time, the toner adheres and adheres to the wall of the transfer pipe, and fusion such as filming occurs on the photoconductor. Occur. For this reason, there have been problems such as deterioration of image quality and shortening of the life of the image forming main body.

Further, the external additive kneaded into the toner main component so as to adhere to the surface of the toner main component also causes the toner main component due to friction between the toners in the developing device and the cleaning device and friction with each constituent member. The image was deteriorated as a harmful foreign substance.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a toner conveying device capable of conveying toner containing a magnetic material not only in the horizontal and downward directions but also in the upward direction.

Further, the object of the present invention is to improve the stability of the image and the reliability of the main body of the image forming apparatus, to suppress the mechanical noise to a low level, and in terms of space and cost. Another object is to provide an advantageous image forming apparatus.

[0013]

In order to achieve the above object, the invention according to claim 1 has a toner conveying device having a toner conveying path in which a plurality of electromagnets are arranged close to each other, and the toner conveying device is provided with respect to the plurality of electromagnets. It is characterized in that the toner is conveyed by executing the traveling wave-like magnetizing and demagnetizing control.

According to a second aspect of the invention, in the first aspect of the invention, the toner conveying device collects the transfer residual toner remaining on the photoconductor by the cleaning means and conveys it to the developing means for reuse. In the image forming apparatus, the transfer residual toner collected by the cleaning unit is used to be conveyed to the developing unit.

According to a third aspect of the present invention, in the second aspect of the present invention, the transfer residual toner is conveyed from the cleaning unit in an upward direction to the developing unit.

According to a fourth aspect of the present invention, in the second or third aspect of the present invention, a detection unit for detecting the amount of the transfer residual toner is provided, and the transfer residual toner carrying capacity is determined based on the detection result of the detection unit. It is characterized by adjusting.

According to a fifth aspect of the present invention, in the second, third or fourth aspect of the present invention, the main component forming a visible image and the external additive component attached to the main component are included. It is characterized in that the triboelectrification characteristics of the additive component have opposite polarities or that the external additive component conveys a toner which is not triboelectrically charged.

The invention according to claim 6 is the invention according to claims 2, 3, and 4.
Alternatively, in the invention described in the paragraph 5, there is provided a means for removing foreign matter in the transfer residual toner that is unsuitable for use in the developing means and collecting the foreign matter.

According to a seventh aspect of the invention, in the sixth aspect of the invention, the traveling-wave-like magnetization control executed for the plurality of electromagnets is 5 Hz or more and 500 Hz in which the magnetization and the demagnetization are repeated during the traveling wave. It is characterized by including the following vibrations.

According to an eighth aspect of the present invention, in the invention according to the sixth aspect, a means for removing foreign matters in the transfer residual toner and collecting the same is provided on a surface for attracting the toner of the plurality of electromagnets and conveying the toner. It is characterized in that it is configured to include an electrode provided on the electrode, an electrode arranged to face the electrode in close proximity to the electrode, and a voltage applying means for applying a voltage between both electrodes.

A ninth aspect of the present invention is characterized in that, in the eighth aspect of the invention, the distance between the electrodes is set to be narrow along the toner carrying direction.

According to a tenth aspect of the present invention, in the invention according to the eighth aspect, the voltage applied between the electrodes includes an AC component and has a maximum electric field strength of 1 kV / mm or more and 5 kV / mm.
It is characterized in that it is set to be less than or equal to mm.

According to an eleventh aspect of the present invention, an electrostatic latent image is formed on the photoconductor charged by the charging means, and the electrostatic latent image is developed by the developing means to be visualized as a toner image. An image is formed through the process of transferring the toner image onto the transfer material by the transfer means, and the transfer residual toner remaining on the photoconductor without being transferred during the toner image transfer is recovered by the cleaning means, and the recovered transfer residual toner In an image forming apparatus in which a toner transport device transports the toner to the developing means and reuses the toner, the toner transport device includes a toner transport path in which a plurality of electromagnets are arranged close to each other, and a traveling wave shape with respect to the plurality of electromagnets. It is characterized in that it is configured to include a control means for executing the magnetizing and demagnetizing control of the.

According to a twelfth aspect of the present invention, in the eleventh aspect of the present invention, a means for detecting the environment in which the image forming apparatus main body is placed and / or a means for detecting the image density on the transfer material are provided. At least one of the image densities is detected to estimate the case where the amount of transfer residual toner is large, and the toner carrying capacity of the toner carrying device is adjusted based on the estimated value.

Therefore, according to the toner conveying device of the present invention, the traveling wave-like magnetizing and demagnetizing control is performed on the plurality of electromagnets, so that the toner containing the magnetic material is directed not only in the horizontal and downward directions but also in the upward direction. Can also be transported to.

According to the image forming apparatus of the present invention,
When reusing the transfer residual toner collected from the photoconductor by the cleaning means, the toner conveying device is used not only for the purpose of conveying the transfer residual toner, but also for paper dust or fresh toner which is not suitable for use in the developing means later. Since it also has a toner selection function that reduces the amount of different external additives, it improves image stability and the reliability of the image forming apparatus main body, suppresses mechanical noise to a low level, and special toner selection. Since it is not necessary to provide any means, it is possible to obtain an image forming apparatus that is advantageous in terms of space and cost.

[0027]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<First Embodiment> FIG. 1 is a front sectional view showing a schematic configuration of an image forming apparatus according to the present invention, and FIG. 2 is a rear view of the image forming apparatus. The image forming apparatus is a copying machine.
Those using electrophotographic technology such as printers, facsimiles, and printing machines are included.

In FIGS. 1 and 2, reference numeral 1 denotes an image forming apparatus main body, a document table cover 2 and a platen glass 3 are installed on an upper portion of the image forming apparatus main body 1, and inside the image forming apparatus main body 1. An original illumination lamp 4 as an exposure system, a plurality of reflection mirrors 5, 6, 7, 9 and a lens 8, a photoconductor 10 as an image carrier, a primary charger 11 arranged around the photoconductor 10, a developing device. 12, a paper feed deck 13, a transfer separation charger 14, a conveyor belt 15, a cleaning device 20, a fixing device 16 arranged on the downstream side of the conveyor belt 15 (in the conveying direction of the transfer paper), and the like. . A paper discharge tray 17 is provided at the paper discharge side end of the image forming apparatus.

In the image forming apparatus constructed as described above, the original document illumination lamp 4 illuminates an original document (not shown) placed on the platen glass 3, and each reflection mirror 5 is illuminated.
A document image is projected on the photoconductor 10 by using 6, 7 and the lens 8 and the reflection mirror 9. Here, the photoconductor 10 is rotationally driven in the direction of the arrow in the drawing and is uniformly charged in advance by the primary charger 11. By projecting the document image on the surface of the photoconductor 10, an electrostatic latent image corresponding to the document image is formed. The formed electrostatic latent image is developed with toner in the developing device 12 and visualized as a toner image.

On the other hand, the transfer paper is supplied from the paper feed deck 13 to the transfer portion between the photoconductor 10 and the transfer / separation charger 14 at an appropriate timing, and the transfer / separation charger 14 causes the transfer paper to appear on the transfer paper. The toner image on the toner image 10 is transferred, and the fixing device 1
6 is transported. Then, after the transfer sheet receives the transfer of the toner image in the fixing device 16, the transfer sheet is discharged to the outside of the apparatus main body 1 and stacked on the sheet discharge tray 17.

By the way, after the transfer of the toner image, the photoconductor 10
The transfer residual toner remaining on the upper side is collected by the cleaning device 20 and provided for development. As a means for reusing the transfer residual toner, an oblique transport path 21 is provided between the hopper 30 installed above the developing device 12 and the cleaning device 20, and the cleaning device 20 collects the toner from the photoconductor 10. The residual toner is transferred to the diagonal conveying path 21.
And is conveyed to the hopper 30. Fresh toner is stored in advance in the hopper 30.
The transfer residual toner is carried into the inside, and is agitated with the fresh toner to be reused, whereby the toner is regenerated.

FIG. 3 shows the photoconductor 10 and the cleaning device 20.
FIG. 4 is a detailed cross-sectional view of the path 21 and FIG.

As shown in FIG. 3, the cleaning device 20
A cleaning blade 40 for scraping off the transfer residual toner on the photoconductor 10 and a screw 41 for conveying the transfer residual toner to a foreign matter removing device are arranged inside the transfer blade, and the transfer residual toner scraped off the photoconductor 10 by the cleaning blade 40 is arranged inside the cleaning blade 40. Is sent to the oblique conveying path 21 by the screw 41.

By the way, conventionally, as a means for conveying powder such as toner, a means using a screw has been generally used, and also in the image forming apparatus according to the present invention,
The screw 41 is used to convey the transfer residual toner from the cleaning device 20 to the oblique conveying path 21, as described above.

On the other hand, the oblique feeding path 21 employs toner conveying means using an electromagnet. As shown in FIG. 4, the transfer residual toner conveyed by the screw 41 is temporarily accumulated in the toner reservoir 51 formed at the entrance of the oblique conveying path 21. An electromagnet unit 5 is provided above the toner reservoir 51.
2 are arranged. Since the transfer residual toner contains a magnetic material, the transfer residual toner moves upward in the oblique conveying path 21 by the magnetizing and demagnetizing control of the electromagnet unit 52, which will be described later, and the electromagnet unit 53 for folding back.
Thus, the hopper 30 is transported without backflow.
In the present embodiment, the slanted conveyance path 21 is installed so as to be inclined upward at 32 °.

By the way, the transfer residual toner contains components which are not contained in the fresh toner. When a transfer paper normally used as the transfer material is used, small paper dust in the transfer paper is collected on the cleaning device side. In addition, even if the components in the toner are different from the toner main component including the magnetic substance in the transfer efficiency, which is the ratio of remaining in the photoconductor, the unnecessary subcomponents increase more than necessary. However, this is particularly noticeable when the charging characteristics of the main component of the toner have opposite polarities.

However, the oblique conveying path 2 according to the present embodiment
In No. 1, since the toner conveying method using magnetic force is adopted, the toner powder and the toner sub-component not containing the magnetic substance can be dropped during the conveyance, and these foreign matters are collected by the conveying pipe 54 in the foreign matter collecting box. Recovered at 55.

FIG. 5 is a sectional view taken along the line AA in FIG. 4. As shown in FIG. 5, the electromagnet unit 52 has two rows of electromagnets, and the oblique conveying path 21 itself is not affected by the outside. It is shaped like a closed pipe.

FIG. 6 is a diagram showing the arrangement of the electromagnets in the electromagnet unit 52. As shown in the figure, the two rows of electromagnets are composed of five types of electromagnet groups, and these electromagnets have M1 to M5. The symbol is attached. Therefore, in the case of the electromagnet M1, all electromagnets M1 are electrically connected to magnetize and demagnetize at the same time. However, since the windings of the two rows of electromagnets are opposite to each other, they are arranged to magnetize the S pole and the N pole, respectively. The winding is constructed by winding an iron core having a diameter of 1 cm and an insulating coated copper wire having a core diameter of 0.3 mm 1500 times, and each electromagnet has 20 coils.
It is arranged with a distance of mm.

FIG. 7 schematically shows an electric circuit diagram for carrying the toner by magnetizing and demagnetizing the electromagnet. In the figure, reference numeral 80 denotes a central processing element (CPU), which receives a signal from the timer element 81 at predetermined time intervals and outputs a predetermined magnetized / demagnetized state. This output is passed through an amplifier (AMP) 82 to GN the electromagnet groups M1 to M5.
D Ground ON / OFF is executed.

FIG. 8 shows the central processing unit (CP) shown in FIG.
U) 80 schematically shows the magnetized and demagnetized states of the electromagnet groups M1 to M5. Mode for time axis is 5
There are different types, and in each mode, two electromagnet groups are always magnetized, and the remaining three electromagnet groups are demagnetized. The mode progresses from 1 to 2 and from 2 to 3 as time passes, but the magnetized / demagnetized state of the electromagnet group is changed while shifting the electromagnet group one by one. In mode 5, the electromagnet group M5 and the next electromagnet group M1 are magnetized. The process following the mode 5 returns to the mode 1 and the program for repeating the modes 1 to 5 is executed.

FIG. 9 is an operation flowchart showing a program executed by the central processing unit (CPU) 80. FIG.
As shown in FIG. 5, in mode 1, the electromagnet groups M1 and M2 are magnetized, and M3, M4, and M5 are demagnetized (step a).
1). Next, a timer routine for keeping the mode 1 state for a certain period of time is executed (step a2). Hereafter, the mode and the timer are executed (step a
3 to step a10), when the copying operation is completed, the photoconductor 1
The mode is repeated until the rotation of 0 is stopped (step a11). At the end of conveyance, the mode at the time of stop may be maintained, or all of them may be demagnetized, or the mode may be reversed from 5 to 1 and returned to the toner reservoir 51.

FIG. 10 is a diagram showing the toner transport state in each mode in the arrangement of the electromagnets shown in FIG. In mode 1, since the electromagnet groups M1 and M2 are magnetized and the other electromagnet groups M3 to M5 are demagnetized, the electromagnet group M1
And toner is attached only near M2. In mode 2, which is the next state, M1 is demagnetized, and M3 is magnetized instead, so that the toner near M1 moves to M3. Thus, according to the mode transition according to the modes 3, 4, and 5, one electromagnet group is demagnetized while one electromagnet group is magnetized, and the adjacent electromagnet group is magnetized,
In the figure, the toner can be moved from left to right, and the electromagnet unit 52 can be used as a toner conveying unit.

FIG. 11 is a diagram showing the effect of the electromagnet unit 52 as a toner carrying means. In FIG. 11, the horizontal axis indicates the inclination angle of the conveying means, the negative side indicates downward conveying,
The plus side indicates the upward transport direction. Further, the vertical axis represents the amount of toner that can be conveyed in a fixed time. A thin line shows a conventional screw conveying method, which is a toner conveying means using a screw and a pipe, and a thick line shows a conveying means according to the present invention.

In FIG. 11, parameters such as the screw shape, the pipe diameter, and the screw rotation speed in the prior art, and the electromagnet in the present invention are driven so that the two conveying capacities become equal at an inclination angle of 0 °. It is a figure which shows the result of adjusting the setting time of the timer performed in between. In the case where the inclination angle is negative and the downward direction, the toner drop action due to gravity is prevented by the screw conveyance which is the prior art in the screw conveyance which is a conventional technique, and therefore the conveyance means of the present invention is more advantageous. became.
Even in the upward direction where the inclination angle is plus, in the conventional technique, the transporting capacity is remarkably deteriorated around the inclination angle of 20 °. On the other hand, even in the present invention, although the capacity is gradually decreased, the result is higher than that of the prior art. It is considered that these differences are mainly due to the fact that the electromagnet transport of the present invention is originally configured to transport by a magnetic force that exceeds gravity, and the toner transport device including a magnetic material is used as the transport means that does not depend on the inclination angle of the electromagnet transport. It turns out that is effective.

By the way, when the transfer residual toner is regenerated and reused in the developing device, when the visible toner on the photoconductor is transferred to the transfer paper by the transfer charger, it depends on the transfer efficiency of the composition components in the toner. As described above, a phenomenon occurs in which the toner composition ratio in the transfer residual toner differs from that of the fresh toner. For example, the main component of the toner prepared by kneading 100 parts by weight of the polyester resin as the binder resin used in the present embodiment and 60 parts by weight of magnetite having magnetism has a negative charging characteristic.

However, in order to appropriately charge the main component of the toner and to set the degree of aggregation of the toner to a desired value, the toner is externally added around the main component of the toner in the form of "external addition". It is necessary to attach an additive. In the case of the present embodiment, it was necessary to add a small amount of strontium titanate and silica as a specific external additive. Unlike the toner used in this embodiment, strontium titanate has a property of being positively charged, and silica can be given a positive or negative charge by changing the composition of silica itself. Due to such charging characteristics, the toner is charged as negative as the main component of the toner. Therefore, due to the charging characteristics of the main component of the toner and strontium titanate, the transfer efficiency is greatly different, and the composition ratio in the transfer residual toner is different from that of the fresh toner. This means that when the transfer residual toner is sent to the subsequent developing device as it is and the toner is regenerated,
Since the composition ratio is different from that of fresh toner, not only the toner cannot be mixed well, but also the charging characteristics of the mixed toner are remarkably deteriorated to cause image deterioration such as image density reduction and fog. Therefore, when there is no toner selection, the composition ratio of fresh toner must be determined in consideration of the composition ratio of transfer residual toner.

Table 1 shows problems when the composition ratio of the toner is changed.

[0050]

[Table 1] First, the toner A is a case where strontium titanate, which is strongly positively charged, is eliminated. This strontium titanate penetrates into the minute gap between the cleaning blade of the cleaning device and the photoconductor and scratches impurities on the photoconductor. It is a substance that is effective as a polishing agent. Without this, impurities would accumulate on the photoconductor, causing a so-called photoconductor filming phenomenon and disturbing the image. Impurities are mainly nitrogen oxides produced during charging,
Combines with moisture in the atmosphere to create low resistance materials. When this low-resistance substance adheres to the photoconductor, the originally sharp latent image formed by image exposure after the primary charger escapes on the photoconductor with reduced resistance, so-called blurring of the output image occurs.

On the other hand, Toner B in Table 1 is a toner containing strontium titanate but containing no silica. Silica has a function of lowering the aggregation degree of the toner, and without it, the aggregation degree becomes extremely high, resulting in poor fluidity. Silica has a function of assisting the charging of the toner, but without this, the toner is not charged to a desired charge amount, the developing characteristics are deteriorated, and the image quality is deteriorated.

Therefore, like toner C in Table 1,
For the quality of an image and the reliability of an image forming apparatus, it is necessary to add a certain amount of an external additive at the time of fresh toner. That is, the toner C is a toner that does not have various problems such as blurring of the output image and defective charging of the toner.

However, as described above, since the transfer efficiency of the main component in the toner and the transfer efficiency of the external additive are different, the composition ratio in the residual toner after transfer becomes large as shown in Table 2,
Further, the paper powder that constitutes the transfer paper is mixed.

[0054]

[Table 2] The conveying means such as screw conveying in the related art has no ability other than conveying and does not have the ability to remove foreign matter in the toner. Conversely, the toner may be compressed in the gap between the pipe and the screw, and may even form agglomerates larger than the normal toner particle size.

However, according to the present invention, the external additives that are not attracted to the magnet and the foreign materials such as paper dust are collected in the foreign material collection box 55 without being conveyed. Combines the ability to reduce powder.
Also, since the mechanical compression is extremely small, the above-mentioned agglomerates cannot be formed.

As described above, since the toner carrying device according to the present invention can carry out the sorting of the toner at the same time as carrying the toner, another toner screening using the carrying means and the mesh for removing the foreign matters in the toner as in the prior art. Toner can be mixed into the developing device 12 without using any means. Therefore, the configuration of the image forming apparatus that reuses toner can be simplified,
This is an advantageous means in terms of space and cost.

<Embodiment 2> Next, an embodiment of the present invention will be described with reference to FIGS.

In the first embodiment, the carrying means capable of carrying out the carrying of the toner and removing the foreign matter in the toner has been described, but in the present embodiment, the toner carrying means for improving the foreign matter removing effect will be explained.

FIG. 12 is an operation flowchart of the toner carrying means according to this embodiment.

The difference from the operation flowchart shown in FIG. 9 in the first embodiment is that there is demagnetization of all electromagnet groups in the magnetized state of the electromagnet groups according to the mode. In the figure, the magnetization and M of the electromagnet groups M1 and M2 in mode 1
After the demagnetization of M3, M4 and M5 (step b1), the timer 2 for a predetermined time is executed (step b2) to demagnetize all electromagnet groups (step b3).

Then, the timer 3 for a predetermined time is further executed (step b4). By performing this process (steps b1 to b4) a predetermined number of times (step b5), a magnetized state including vibration due to mode 1 and total demagnetization can be created.

In this embodiment, the timer 2 is 12 msec, the timer 3 is 8 msec, and the step b5 is repeated 10 times. Since execution of the mode (step b1), total demagnetization (step b3), and repeated branching (step b5) depend only on the execution speed of the CPU and its peripheral circuits, the time is several 100 μsec or less. It is a minute time in comparison. Therefore, the vibration is executed in about 20 msec. That is, vibration of about 50 Hz is applied to the electromagnet. Then, the vibration in one mode is about 50 Hz × 10 times, and after about 0.2 seconds, it shifts to the next mode. Thus, the vibration of mode 2 (step b6 to step b1
0), and the vibrations of mode 3, mode 4, and mode 5 are performed (steps 11 to 25), and this is repeated until the rotation of the photoconductor stops (step b26).
Incidentally, the toner conveying means by the electromagnet of the present invention has no mechanical moving member, and mechanical noise or vibration of the screw in the prior art does not occur. Therefore, as long as the power switch of the image forming apparatus main body is ON, it is possible to repeat the toner conveyance.

Vibration according to the mode of the present embodiment has the following meaning.

If the mode is experimentally stopped in the toner conveying process due to the mode change shown in the first embodiment and the magnetized state remains in a certain mode, the paper dust and the external additive are no longer contained in the foreign matter collection box. It turns out that it doesn't fall to 55.
That is, the foreign matter drops from the toner attracted to the electromagnet group when the toner is conveyed, that is, when the mode is changed.

Therefore, in consideration of the experience from this experiment, when a vibration which repeats the magnetization and the demagnetization is applied, the foreign matter in the transfer residual toner which is attracted to the electromagnet group and is now being transferred is effectively dropped. It became so. It is presumed that this is because the toner being transferred is agitated by the vibration of the magnetic force and the gravity and is in a state of being easily dropped. Moreover, in the present invention, it has been found that there is an advantageous condition for the frequency of this vibration. That is, a preferable frequency is 5 Hz or more and 500 Hz or less. When the frequency is less than 5 Hz, if the timer 3 after the complete demagnetization and the timer 2 after the execution of the mode are set to the same time, the toner drops remarkably due to gravity, and even useful toner may be discarded in the foreign matter collection box. On the other hand, 500H
At a frequency higher than z, the toner vibration could not catch up, and the toner agitation became insufficient.

Table 3 shows the effects obtained by this embodiment.

[0067]

[Table 3] In Comparative Example 1 shown in Table 3, although the paper powder and the external additive are effectively reduced from the composition ratio, there is a problem that even useful toner is discarded. In Comparative Example 2, the vibration frequency was too high, the vibration of the toner itself was weak, and the selection property was insufficient. Also in the first embodiment, the amounts of the paper powder and the external additive in the transfer residual toner are reduced, but it can be seen that the foreign substances are removed more effectively in the present embodiment.

On the other hand, FIG. 13 is an operation flowchart obtained by further improving the operation flowchart of the present embodiment shown in FIG.

The difference between the flowchart shown in FIG. 13 and that shown in FIG. 12 is that instead of demagnetizing all electromagnet groups, the next mode is executed to generate vibration. The timer 4 is 10 msec, and the timer 5 is 10 msec. With such a configuration, by repeating the modes 1 and 2 in steps c1 to c5 in the flowchart, the electromagnet groups M1 and M3 are alternately magnetized and demagnetized while the electromagnet groups M2 are magnetized according to FIG. Will be generated.

By doing so, it is possible to further reduce the amount of useful toner to be discarded in the foreign matter collection box, as compared with the case of carrying according to the operation flowchart shown in FIG.

<Third Embodiment> Next, a third embodiment of the present invention will be described with reference to FIGS.

FIG. 14 is a detailed cross-sectional view of the diagonal conveying path 21 in this embodiment. In the present embodiment,
The transfer residual toner is generated by the screw 4 in the cleaning device 20.
Toner reservoir 5 formed from 1 to the entrance of the oblique transport path 21
It is temporarily stored in 1. An electromagnet unit 52 is arranged above the toner reservoir 51, and the transfer residual toner is conveyed to the hopper 30 by the electromagnet unit 53 for folding. The above is the same configuration as in the first embodiment.

Thus, in this embodiment, the diagonal conveying path 2
An electrode plate 60 is attached inside the electrode 1, and the electrode plate 60 is electrically grounded. Further, a metal roller 61 is disposed in proximity to the electrode plate 60 so as to electrically face the electrode plate 60, and an applied voltage from a high voltage power source 62 is applied to the metal roller 61. The metal roller 61 receives a driving force from a gear 63 and is rotationally driven in a direction of an arrow shown in the drawing, and is connected to a high voltage power source 62 via a contactor 64.

As described above, in the present embodiment, the structure in which the electric field acts between the electrode plate 60 and the metal roller 61 is adopted in the oblique conveying path 21, and the transfer between the electrode plate 60 and the metal roller 61 is performed. The residual toner is conveyed by the traveling wave control of the electromagnet.

By the way, the distance between the electrode plate 60 and the metal roller 61 is not a constant distance, but the toner reservoir 51 for starting voltage application.
The distance D1 in the vicinity is 3 mm, and the transfer residual toner is in the hopper 30.
The distance D2 just before being mixed in is set to 1.5 mm, and a relationship of D1> D2 is established between the distances D1 and D2. This is because in the vicinity of the start of toner conveyance (that is, in the vicinity of D1), the proportion of paper powder contained in the toner is large, and the electric attractive force is hard to work.
This is because the effect of separating the paper dust by the vibration of the mode used in step 1 mainly works. Further, in the vicinity of the hopper 30 (that is, near D2), the paper powder in the toner is considerably reduced as compared with the vicinity of D1, the toner amount itself during transportation is also reduced, and the external additive can be removed mainly by the electric field. Is. Therefore,
It is most effective to remove the foreign matter by applying the maximum electric field strength to the toner with less paper dust. The removed paper dust and the external additive are separated from the metal roller 61 by the blade 65 and collected in the foreign matter collection box 55.

FIG. 15 is a sectional view taken along line BB of FIG.
As shown in the figure, an electrode plate 60 is attached inside the transport pipe 54 that is in contact with the two rows of electromagnets, and the toner being transported is nipped between the metal rollers 61 to which a voltage is applied. External additives having different charging characteristics are attracted to the metal roller 61 and scraped off from the metal roller 61 by the blade 65.

FIG. 16 is a diagram showing a voltage waveform generated by the high voltage power supply 62. A circuit is built in the high-voltage power supply 62 so that the alternating current component is superimposed on the direct current component, and as shown in the figure, the direct current component of Vdc = -2 kV and the rectangular wave alternating current component of amplitude 4 kV and frequency 500 Hz are combined. -4 kV is applied to the metal roller 61 as the maximum applied voltage. As described above, since the distance between the electrode plate 60 and the metal roller 61 is set to D2 = 1.5 mm in the vicinity of the hopper 30, 2.67 kV / mm is applied as the maximum electric field strength. The reason why the AC component is superposed is that the external additive can be efficiently attracted because the AC component is better used for microscopic toner agitation.

Table 4 shows the electrode plate 60 and the metal roller 6
A comparative example of the toner selection ability by changing the maximum electric field strength applied during 1 will be shown.

[0079]

[Table 4] In Comparative Example 3 shown in Table 4, the maximum electric field strength is weak and the electric attraction to the metal roller 61 is weak. Therefore, the further decrease in the ratio of each external additive in Example 2 shown in Table 3, particularly the decrease in strontium titanate, is a slight amount. On the other hand, in Comparative Example 4, a voltage leak occurs between the electrode plate 60 and the metal roller 61 especially when the humidity exceeds 50%, so that it may be impossible to select the external additive by the electric field. As described above, the maximum electric field strength has an appropriate range, and in the present invention, the appropriate range is 1 kV / mm or more 5
It was found to be kV / mm or less.

FIG. 17 is a diagram showing the distribution of the charge amount of the toner showing the effect of this embodiment.

In FIG. 17, the horizontal axis represents the charge amount and the vertical axis represents the counter number. In the figure, the distribution represented by the thin line is the charge amount of fresh toner, and the charging characteristic is negative, so there is a peak on the negative side, and the number of counters on the positive side is small.

However, in the toner obtained by removing the paper dust from the transfer residual toner by the paper dust separating means, the distribution is broad and has a non-negligible spread on the plus side as shown by the dotted line. However, it can be seen that, by providing the external additive removing means by the electric field of the present embodiment, a charge distribution close to that of fresh toner is exhibited as shown by the thick line in the figure.
As described above, the toner selection of the present invention can be said to be an effective means for ensuring the longevity of the optimum image and ensuring the reliability of the image forming apparatus main body in the image forming apparatus that reuses the transfer residual toner.

In the present embodiment, the toner that is negatively charged has been described, but naturally, the toner that is positively charged is still an effective means.

<Fourth Embodiment> Next, a fourth embodiment of the present invention will be described.

The toner conveying device according to the present invention employs a structure in which the transfer residual toner in the toner reservoir 51 is attracted by the electromagnet unit 52 and conveyed. The amount of residual toner sent from the cleaning device 20 varies depending on the image density and the difference in transfer efficiency due to the environment, and is not limited to a constant amount. Therefore, the toner sump 51 may overflow with the transfer residual toner, and the transfer residual toner may be discarded in the foreign matter collection box 55 without being conveyed, which is uneconomical.

Therefore, in the present embodiment, as shown in FIG. 14, a toner detection sensor 70 for detecting the amount of toner in the toner reservoir 51 is provided near the toner reservoir 51. The toner detection sensor 70 uses a piezo-piezoelectric element, and it is possible to determine the presence / absence of toner around the piezo-electric element. A wiper 71 is provided near the toner detection sensor 70.
The wiper 71 rotates with the rotation of the metal roller 61 to scrape the toner around the toner detection sensor 70, and cleans the periphery of the toner detection sensor 70 at regular intervals. Here, the wiper 71 is made of a resin having a high insulating property, so that the high pressure does not leak to the toner detection sensor 70.

In this embodiment, FIG. 13 of the second embodiment is used.
Although the same flow chart as the operation flow chart shown in is executed, two repetition numbers are prepared. That is, when the toner detection sensor 70 does not detect the toner in the toner reservoir 51, the normal number of times is repeated 10 times. However, the toner detection sensor 70 detects the toner and the transfer residual toner in the toner reservoir 51 remains. If the number is large, the number of repetitions is set to 5. By doing this,
The operation cycle (steps c1 to c25) of the flowchart is switched to the two-stage execution speed. When there is a large amount of transfer residual toner, the traveling wave-shaped magnetizing and demagnetizing control of the electromagnet is performed quickly, so that the toner transport speed can be increased.

By the way, when the composition ratio of the transfer residual toner having a high image density and the transfer residual toner having a low image density was examined, the results shown in Table 5 were found.

[0089]

[Table 5] That is, it was found that the residual toner having a high image density had a smaller content of foreign substances such as paper powder and external additives than the toner having a normal density. This is because when the image density is high, the efficiency of transfer onto the transfer paper is reduced, and the transfer residual toner collected by the cleaning device is increased, so that a lot of toner closer to fresh toner is collected. Although it is known that if the number of times of repetition is decreased, the speed is increased, but the ability to remove foreign matter is inferior. It will be good.

As described above, in the present embodiment, the amount of transfer residual toner is detected, and the toner conveying speed is switched based on the detection result, so that wasteful transfer residual toner is prevented.

<Fifth Embodiment> Next, a fifth embodiment of the present invention will be described.

In the fourth embodiment, the toner amount in the toner reservoir 51 is directly detected, but in the present embodiment, a method of indirectly estimating the transfer residual toner amount is adopted.

As shown in FIG. 1, a potential sensor 18 for reading the charging characteristics of the primary charger 11 and the exposure state of the exposure system such as the document illumination lamp 4 is attached near the photoreceptor 10 of the image forming apparatus main body 1. ing. This potential sensor 18
Especially when the power of the image forming apparatus main body 1 is turned on, the primary charger 11
In order to modulate the voltage applied to the photosensitive member 10 to form an optimum charged state or to turn on the document illumination lamp 4 to form an optimum white background potential on the photosensitive member 10. It is something to read. Therefore, when the document is placed on the platen glass 3 and an image is projected on the photoconductor 10 by the exposure system, the potential sensor 18 can read the reflected light amount of the document. That is, the document density can be detected.

Further, the image forming apparatus main body 1 is provided with a humidity sensor (not shown) for reading the environment in which the image forming apparatus main body 1 is placed, at a position where it is easy to contact the outside air,
By reading the humidity of the outside air with the humidity sensor, the water content of the transfer paper can be estimated. The water content is an important parameter that affects the efficiency of toner transfer from the photoconductor 10 to the transfer paper. That is, when the humidity is high and the water content of the transfer paper is high, the efficiency of transfer using toner deteriorates. It has been known that if the efficiency of toner utilization deteriorates, as described in the fourth embodiment, the composition ratio of substances unsuitable for development in the residual toner decreases.

Therefore, in this embodiment, as shown in Table 6, the image density is divided into three stages and the humidity is divided into three stages, and three levels can be selected from nine combinations thereof. Here, the level refers to the amount of transfer residual toner, which means that level 1 is small, level 2 is medium, and level 3 is large. Then, by changing the number of repetitions in the operation flowchart as shown in the fourth embodiment, it becomes possible to adjust the toner transport speed by the traveling wave-like magnetizing / demagnetizing applied to the electromagnet.

[0096]

[Table 6] (Note) Level 1: Number of repetitions 20 times Level 2: Number of repetitions 10 times Level 3: Number of repetitions 5 times As described above, in the present embodiment, the humidity and the image density at which the image forming apparatus main body 1 is placed are detected. As a result, the amount of transfer residual toner is estimated, and the toner conveying speed is switched based on the estimation result, thereby preventing wasteful waste of toner.

In addition, not only the humidity sensor detects the humidity in which the image forming apparatus main body of the present embodiment is placed,
A method of inferring humidity from a temperature sensor may be used, for example,
The configuration may be such that the humidity is determined to be high when the temperature is high.

Further, in the present embodiment, not only the humidity and the image density are judged simultaneously, but at least one of them may be detected and the toner carrying speed may be modulated based on the result.

[0099]

As is apparent from the above description, according to the present invention, traveling wave magnetizing and degaussing control is performed on a plurality of electromagnets so that the toner containing the magnetic material is not only horizontally and downwards, It is possible to provide a toner transport device that is capable of transporting in the upward direction.

Further, in the image forming apparatus which conveys and reuses the transfer residual toner collected from the photosensitive member by the cleaning means, the toner conveying device is used not only for the purpose of conveying the transfer residual toner but also for the developing means later. Since it also has a toner selection function that reduces the amount of paper powder that is not suitable for use and external additives that differ from fresh toner, it not only improves image stability and the reliability of the image forming apparatus itself, but also reduces mechanical noise. It is possible to obtain an image forming apparatus that is small in size and does not need to be provided with a dedicated toner selection unit, which is advantageous in terms of space and cost.

[Brief description of drawings]

FIG. 1 is a front sectional view of an image forming apparatus according to the present invention.

FIG. 2 is a rear view of the image forming apparatus according to the present invention.

FIG. 3 is a plan view showing a positional relationship between a photoconductor, a cleaning device, and an oblique transport path.

FIG. 4 is a sectional view of an oblique conveyance path.

FIG. 5 is a sectional view taken along line AA of FIG. 4;

FIG. 6 is a diagram showing an arrangement of electromagnets in the electromagnet unit.

FIG. 7 is a configuration diagram of an electric circuit that executes magnetizing and demagnetizing control of an electromagnet.

FIG. 8 is a diagram showing a magnetized state and a demagnetized state of the electromagnet.

FIG. 9 is a flowchart showing a control operation executed in the first embodiment of the present invention.

FIG. 10 is a diagram showing a toner conveyance state in the electromagnet.

FIG. 11 is a correlation diagram between the tilt angle and the carrying capacity of the carrying means for explaining the effect of the first embodiment.

FIG. 12 is a flowchart showing a control operation executed in the second embodiment of the present invention.

FIG. 13 is a flowchart showing an improved control operation executed in the second embodiment of the present invention.

FIG. 14 is a sectional view of an oblique conveyance path according to a third embodiment of the present invention.

FIG. 15 is a sectional view taken along line BB of FIG. 14;

FIG. 16 is a diagram showing a voltage waveform of a high voltage power supply.

FIG. 17 is a diagram showing a toner charge amount distribution showing the effect of the third embodiment of the present invention.

[Explanation of symbols]

 10 Photoconductor 11 Primary Charger (Charging Means) 12 Developing Device (Developing Means) 14 Transfer Separating Charger (Transfer Means) 18 Potential Sensor 20 Cleaning Device (Cleaning Means) 21 Diagonal Conveying Path (Toner Conveying Path) 30 Hopper 40 Cleaning Blade 41 Conveying screw 51 Toner reservoir 52 Electromagnetic unit 54 Conveying pipe 55 Foreign matter collecting box 60 Electrode plate (electrode) 61 Metal roller (electrode) 62 High voltage power supply 65 Blade 70 Toner detection sensor 71 Wiper 80 CPU (control means)

Claims (12)

[Claims] 1. A toner having a toner conveying path in which a plurality of electromagnets are arranged in proximity to each other, and the toner is conveyed by executing traveling wave-like magnetizing and demagnetizing control on the plurality of electromagnets. Transport device. 2. An image forming apparatus in which a transfer residual toner remaining on a photoconductor is collected by a cleaning unit and conveyed to a developing unit for reuse, and the developing unit of the transfer residual toner collected by the cleaning unit is used. The toner transport device according to claim 1, wherein the toner transport device is used for transporting to toner. 3. The toner carrying device according to claim 2, wherein the untransferred toner is carried from the cleaning means in an upward direction to the developing means. 4. The toner according to claim 2, further comprising a detection unit that detects the amount of the transfer residual toner, and adjusts the transfer residual toner carrying capacity based on the detection result of the detection unit. Transport device. 5. A main component that forms a visible image and an external additive component that adheres to the main component, and the triboelectric charging characteristics of the main component and the external additive component have opposite polarities or the external additive component. The toner conveys toner which is not triboelectrically charged.
Or the toner conveying device according to item 4. 6. The toner conveying device according to claim 2, further comprising means for removing foreign matter in the transfer residual toner that is unsuitable for use in the developing means and collecting the foreign matter. 7. The traveling-wave-shaped magnetizing control executed for the plurality of electromagnets includes a vibration of 5 Hz or more and 500 Hz or less in which the magnetizing and demagnetizing are repeated during the traveling wave. Toner transport device. 8. A means for removing foreign matter in the transfer residual toner and collecting the foreign matter is opposed to an electrode provided on a surface of the plurality of electromagnets for attracting the toner and conveying the toner, in close proximity to the electrode. 7. The toner carrying device according to claim 6, wherein the toner carrying device is configured to include electrodes arranged and voltage applying means for applying a voltage between both electrodes. 9. The toner transport device according to claim 8, wherein the distance between the electrodes is set to be narrow along the toner transport direction. 10. The voltage applied between the electrodes includes an AC component and has a maximum electric field strength of 1 kV / mm or more and 5 kV.
9. The toner transport device according to claim 8, wherein the toner transport device is set to be equal to or less than / mm. 11. An electrostatic latent image is formed on a photoconductor charged by a charging unit, the electrostatic latent image is developed by a developing unit to be visualized as a toner image, and the toner image is transferred by a transfer unit. An image is formed through a process of transferring it onto a transfer material, and the transfer residual toner remaining on the photoconductor without being transferred at the time of transferring the toner image is collected by a cleaning unit,
An image forming apparatus that conveys the collected residual toner after transfer to a developing device by a toner conveying device and reuses the toner, wherein the toner conveying device includes a toner conveying path in which a plurality of electromagnets are arranged in proximity to each other, An image forming apparatus including a control unit that executes traveling wave magnetizing and demagnetizing control on the electromagnet. 12. A transfer residual toner is provided by detecting the environment in which the main body of the image forming apparatus is placed and / or detecting the image density on the transfer material, and detecting at least one of the environment and the image density. The image forming apparatus according to claim 11, wherein a case where the amount is large is estimated, and the toner carrying capacity of the toner carrying device is adjusted based on the estimated value.