JPH087491B2 - Development device - Google Patents

Description

The present invention relates to a developing device such as a copying machine or a printer using an electrophotographic method.

<Prior Art> As shown in FIG. 3, a conventional developing device includes a developing tank 2 arranged in the vicinity of the photoconductor 1 and a toner replenishing tank 4 for replenishing the developing tank 2 with magnetic toner 3. A partition plate 5 is provided between the developing tank 2 and the toner replenishing tank 4, and a toner replenishing port 6 that connects the developing tank 2 and the toner replenishing tank 4 is formed below the partition plate 5.

The developing tank 2 is internally provided with a developing roller 8 rotatably supported by a developing device main body 7 and a doctor 10 for regulating the amount of a developer (toner and carrier) 9 attached on the developing roller 8. There is. As shown in FIG. 4, the developing roller 8 has a sleeve 11 that rotates in the opposite direction to the rotation direction of the photosensitive member 1.
And a magnet body 12 arranged on the inner surface of the sleeve 11 and rotating in the opposite direction to the sleeve 11.

The toner replenishing tank 4 stirs the magnetic toner 3 and sends it to the developing tank 2 from the toner replenishing port 6 by a toner stirring roller 13
Is rotatably furnished.

In the above structure, the developer (toner and carrier) 9 in the developing tank 2 is conveyed by the rotation of the sleeve 11 of the developing roller 8 and the magnet body 12, and the amount of the developer 9 on the sleeve 11 is regulated by the doctor 10. Further, it is conveyed to the photoconductor 1 and developed.

Further, in JP-A-60-75854, JP-A-62-5279, JP-A-63-6572, JP-A-63-83753, JP-A-63-129366, etc. A two-component developing device using toner is disclosed.

<Problems to be Solved by the Invention> However, in the conventional developing device, the developer 9 including the magnetic toner 3 and the carrier is well stirred with the magnetic toner 3 and the developer 9 supplied from the toner supply tank 4. Not done. Moreover, when the pressure or fluidity of the developer 9 in the stirring chamber or the reflux passage changes according to deterioration of the developer 9, humidity, temperature, etc., and the toner concentration of the developer 9 becomes unstable, there is a problem. .

In the development of the printer, the reversal development method is mainly used, and after printing 200 sheets of the originals 14 and 15 shown in FIGS. 5 (a) and 5 (b) continuously, a solid black pattern (black-white ratio of the original When 100%) was printed, the originals 16 and 17 shown in FIGS. 6 (a) and 6 (b) were obtained, and white spots C partially occurred. The white spot C is generated in the non-image part of the document and not in the image part of the document.

In addition, the charge amount of the toner on the sleeve of the developing roller at the position corresponding to the non-image portion where the white spot C has occurred and the white spot C
When compared with the charge amount of the toner on the sleeve of the developing roller at the position corresponding to the image portion in which the occurrence of no image is generated, the former is lower. The reason for this is that the image part of the original and the non-developing part have different electrical effects when they come into contact with the photoconductor, and the developer on the sleeve of the non-image part is always high in potential of the photoconductor (usually 400 V or more). This is because the charge of the developer is discharged and the charge amount of the toner is reduced, the transfer amount of the toner to the photoconductor is reduced, and the image density of the solid black portion is reduced.

Therefore, in view of the above, an object of the present invention is to provide a developing device capable of eliminating the instability of the toner concentration of the developer and improving the chargeability of the developer on the sleeve of the developing roller.

<Means for Solving the Problems> The means for solving the problems according to claim 1 of the present invention has a developing roller 8 including a sleeve 11 and a magnet body 12 which are rotatably provided with each other, as shown in FIGS. Development tank 2,
The toner replenishing port 6 is separated from the developing tank 2 through the partition plate 5.
Toner replenishing tank 4 for replenishing magnetic toner 3 from developing tank 2 to developing tank 2
And a doctor 10 for regulating the amount of the developer 9 on the sleeve 11 is provided in the developing tank 2, and the toner supply port 6
A scraping member 20 for scraping off the developer 9 on the sleeve 11 is arranged between the doctor 10 and the doctor 10 and is supplied to the developer 9 scraped off by the scraping member 20. The magnetic toner 3 and the magnetic toner 3 are mixed and stirred so that the toner concentration of the developer 9 becomes constant.
The scraping member 20 is formed by being surrounded by 11 and
Further, the developer 9 regulated by the doctor 10 is guided to the stirring section 21, and an opening 23 through which the magnetic toner 3 passes is formed.

In the second aspect, the second stirring unit 24, which stirs the developer 9 regulated by the doctor 10 in a pressurized state and circulates it toward the stirring unit 21, is provided between the scraping member 20 and the doctor 10. It is formed by being surrounded by 10, the sleeve 11, and the partition plate 5, and is formed with the opening 23 of the scraping member 20 and the second stirring section.
24 is communicated with the second stirring section 24, and the developer 9 recirculated by the second agitating section 24 is mixed with the developer 9 scraped by the scraping member 20 so that the scraping member 20 is close to the toner supply port 6. It was arranged.

In the third aspect, the toner replenishing tank 4 is internally provided with the toner stirring roller 13 for feeding the magnetic toner 3 to the developing tank 2, and the magnetic toner 3 is conveyed to the toner stirring roller 13 toward the toner replenishing port 6 and refluxed. An urging portion 13a for pressing the developer 9 thus crushed and a crushing portion 13b for vibrating the magnetic toner 3 so as to crush the solid developer 9 pressed by the toner supply port 6 are provided. .

<Operation> In the problem solving means according to claim 1, the photosensitive member 1
The developed developer 9 that has not been transferred to is conveyed while being attached to the sleeve 11 and is scraped by the scraping portion 22 of the scraping member 20. The scraped developer 9 is stopped at the scraping section 22 and a flow is generated by the rotation of the magnet body 12.

The magnetic toner 3 sent out from the toner replenishing tank 4 to the toner replenishing port 6 is attracted by the magnetic force of the magnet body 12, and the developer 9 and the magnetic toner 3 are mixed and stirred by the flow to make the toner concentration uniform. It becomes a predetermined value. Stirrer
The developer 9 sufficiently agitated in 21 is rotated by the sleeve 11 and the magnet body 12, and the scraping portion 22 and the sleeve are rotated.
It is transported to the doctor 10 through the gap with 11. Here, the amount of the developer 9 adhered is regulated by the doctor 10 and the developer 9 is conveyed to the photoconductor 1. On the other hand, the developer 9 regulated and scraped off by the doctor 10 circulates toward the scraping member 20, passes through the opening 23 of the scraping member 20, and joins the flow of the developer in the stirring section 21. And stirred again.

Therefore, in the developer 9 using the magnetic toner 3, the magnet body 12 is rotated and the scraping member 20 is agitated by the stirring unit 21.
By forming the toner, the developer 9 and the magnetic toner 3 are sufficiently mixed and stirred, the magnetic toner 3 is uniformly mixed with the developer 9, the chargeability of the toner is improved, and the toner concentration of the developer 9 is increased. Stabilize.

The developer 9 regulated and scraped off by the doctor 10 according to claim 2, generates a flow indicated by the reflux B in the second stirring section 24, flows toward the scraping member 20, and then in the stirring section 21. It joins with reflux A of and is stirred again.

Then, the flow of the developer 9 (reflux B) is applied to the developing roller 8
Since the developer 9 is strongly conveyed by the magnetic force of and the rotation of the sleeve 11, the area of the second stirring section 24 is filled with the developer with almost no space formed in the upper part (there is no space). Therefore, since the volume of the developer does not easily change, the toner concentration is likely to be stable. Moreover, the developer is further scraped off by the doctor 10 to generate reflux, which is combined with the reflux generated in the stirring section 21, so that the stirring performance of the developer can be improved. Further, since the mounting position of the scraping member 20 is close to the toner supply port 6, the supplied toner can be sufficiently mixed and stirred.

In the third aspect, the urging portion 13a and the crushing portion 13b replenish the magnetic toner 3 toward the toner replenishing port 6 in a corrugated manner and replenish it every half circumference of the toner stirring roller 13. The crushing section 13b vibrates and crushes the magnetic toner 3 and the reflux A and the reflux B when the refluxed pressure developer 9 is solidified by merging the magnetic toner 3 and the reflux A and the reflux B. The toner 3 can be conveyed to the toner replenishing port 6, and the magnetic toner 3 can be pressed in a wave shape against the flow of the developer 9 that has merged and recirculated to promote mixing and stirring.

<Example> Hereinafter, an example of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view of a developing device showing an embodiment of the present invention, and FIG. It should be noted that the same components as those of the related art are denoted by the same reference numerals.

As shown in the drawing, the developing device of the present invention includes a developing tank 2 having a developing roller 8 including a sleeve 11 and a magnet body 12 rotatably provided with each other, and a toner for replenishing the developing tank 2 with a magnetic toner 3. And a developing tank 2 provided with a replenishing tank 4.
A doctor 10 for regulating the amount of the developer 9 on the sleeve 11 is provided on the sleeve 11. The doctor 10 is provided between the toner replenishing port 6 from the toner replenishing tank 4 to the developing tank 2 and the doctor 10 in close proximity to the developing roller 8. A scraping member 20 for scraping off the developer 9 on the sleeve 11
And a stirring portion 21 for mixing and stirring the developer 9 scraped by the scraping member 20 and the replenished magnetic toner 3 to make the toner concentration of the developer 9 constant is formed. It is a thing.

A second stirring unit 24 is formed between the scraping member 20 and the doctor 10 to circulate the developer 9 regulated by the doctor 10 toward the stirring unit 21 while stirring the developer 9. The scraping member 20 is arranged in the vicinity of the toner replenishing port 6 so that the developer 9 returned by 24 is mixed with the developer 9 scraped by the scraping member 20.

Further, the toner replenishing tank 4 is internally provided with a toner stirring roller 13 for feeding the magnetic toner 3 to the developing tank 2, and the toner replenishing port 6 presses the magnetic toner 3 against the developer 9 to mix them. The crushing portion that crushes the developer 9 that has been pressed by the biasing portion 13a and the toner replenishing port 6 and is solidified.
13b and are provided.

The magnetic toner 3 is composed of a toner containing magnetic iron oxide, and the developer 9 is produced by mixing the magnetic toner 3 with a carrier using ferrite, iron powder or magnetic iron oxide granulation carrier.

The scraping member 20 is a flat plate having an L-shaped cross section, and includes a developing roller 8
The end bent at a right angle to the direction is the scraping part 22.
The end opposite to 22 is bent and attached to the developing device main body 7 below the toner supply port 6.

The scraping section 22 is located downstream of the toner supply port 6 in the rotational direction of the sleeve 11 and in front of the doctor 10. And
The distance d between the scraping portion 22 and the sleeve 11 is e ≦ d ≦ 1.0 mm, where e is the distance between the doctor 10 and the sleeve 11. In this embodiment, d = 0.7 ± 0.1 mm, e =
It is set to 0.3 ± 0.02 mm.

The stirring section 21 is an area surrounded by an opening 23 formed in the scraping member 20 so as to connect the toner supply port 6 and the developing roller 8 with each other, the scraping section 22, and the sleeve 11. .

The developer 9 scraped off from the sleeve 11 by the scraping unit 22 causes reflux A due to the rotation of the magnet body 12, as shown in FIG. The magnetic toner 3 and the developer 9 attracted by the magnetic force are mixed and stirred by this flow.

The second stirring unit 24, the doctor 10, the sleeve 11,
In the area surrounded by the partition plate 5, the developer 9 regulated by the doctor 10 is swept away by the developer 9 carried on the sleeve 11 by the magnetic force of the magnet body 12 and the rotation of the sleeve 11, and the scraping member. Giving reflux B towards 20.

In the toner replenishing roller 13, a supporting plate 26 is fixed to a roller shaft 25 rotatably supported by the developing device main body, the urging portion 13a is attached to one end of the supporting plate 26, and the urging portion 13a is attached.
The crushing portion 13b is attached to the other end on the opposite side.

The urging portion 13a is made of a resin plate attached in a direction orthogonal to the support plate 26, and conveys the toner 3 while elastically slidingly contacting the bottom surface of the toner replenishing tank 4.

The crushing portion 13b is composed of coil springs fixed to both ends of the roller shaft 25 and arranged in parallel with the roller shaft 25, and vibrates the toner 3 to prevent the toner 3 from solidifying.

The rotation speed of the sleeve 11 is 60 rpm, and the magnet body 12
Rotation speed is 500 rpm, and the distance between the photoconductor 1 and the sleeve 11 is 0.
It is set to 35 mm.

Other configurations are the same as those of the above-mentioned conventional technique, and thus detailed description will be omitted.

In the above configuration, the developer 9 magnetically adheres to the sleeve 11 of the developing roller 8 and becomes a spiked state,
It is conveyed by the rotation of 11 and the magnet body 12, the amount of adhesion is regulated by the doctor 10, and is conveyed to the photoreceptor 1 to be transferred and developed.

The developed developer 9 that has not transferred to the photoconductor 1 is conveyed while being attached to the sleeve 11, and is scraped off by the scraping unit 22. The scraped developer 9 is prevented from flowing to the scraping section 22, and the reflux A toward the opening 23 is generated by the rotation of the magnet body 12.

In the toner replenishing tank 4, the urging portion 13a and the crushing portion 13b are
The magnetic toner 3 is supplied to the toner replenishing port 6 by being pressed and conveyed in a wavy shape every half circumference of the toner stirring roller 13.
The crushing unit 13b crushes the magnetic toner 3 and the reflux A and the reflux B when the pressurized developer 9 that has been refluxed is solidified if it is solidified, and the urging unit 13a urges the magnetic toner 3 in the toner supply tank 4 Of the developer 9 conveyed to the toner replenishing port 6 and merged and recirculated.
The magnetic toner 3 is pressed in a wave shape against the flow of No. 1 to accelerate mixing and stirring.

The developer 9 after the developer 9 and the magnetic toner 3 are stirred and mixed in the toner supply port 6 is provided on the scraping member 20 by the magnetic force of the developing roller 8 and the transport force of the sleeve 11. It passes under the opened opening 23 and flows back toward the sleeve 11.

Then, the magnetic toner 3 sent to the toner supply port 6 by the toner stirring roller 13 of the toner supply tank 4 is
When the toner concentration of the developer 9 at 21 is low, the developer 9 and the magnetic toner 3 are agitated by the reflux A due to the magnetic force of the magnet body 12, and the toner concentration becomes a predetermined value uniformly.

The developer 9 sufficiently stirred by the stirring unit 21 is conveyed to the doctor 10 through the gap between the scraping unit 22 and the sleeve 11 by the rotation of the sleeve 11 and the magnet body 12. Here, a part of the developer 9 is the doctor 10 and the sleeve.
After passing through the gap with 11, the amount of adhesion is regulated and the toner is conveyed to the photoconductor 1. On the other hand, the developer 9 regulated and scraped off by the doctor 10 generates a flow indicated by reflux B, circulates toward the scraping member 20, and is stirred again by reflux A.

Then, the flow of the developer 9 (reflux B) is applied to the developing roller 8
Since the developer 9 is strongly conveyed by the magnetic force and the rotation of the sleeve 11, the area of the second agitator 24 forms almost no space in the upper part, and rather the developer 9 is filled and refluxed under pressure. ing. The developer (reflux B) that has circulated counterclockwise in the second agitating section 24 merges with the developer flow (reflux A) scraped by the scraping member 20 so as to face each other, and the toner supply port 6
Reflux to.

Therefore, in the developer 9 using the magnetic toner 3 and the carrier, the magnet body 12 is rotated, and the developer 9 is scraped from the sleeve 11 by the scraping member 20 to form the rotation of the magnet body 12 and the stirring portion 21. By doing so, the developer 9 and the magnetic toner 3 are sufficiently stirred, the magnetic toner 3 is uniformly mixed with the developer 9, and the mixed and stirred developer 9 is conveyed to the photoconductor 1. The charging property is improved, and the toner density of the developer 9 is stabilized. Therefore, it is possible to prevent the occurrence of white spots in the reversal development method.

In addition, the amount of toner in the toner supply tank 4, temperature,
It is possible to realize a developing device having a mechanism for automatically stabilizing the toner concentration that is extremely unlikely to be affected by the change in the fluidity of the magnetic toner or the developer due to the change in humidity, and eliminate the need for the stirring roller and the toner concentration sensor in the developing tank 2. It is possible to reduce the size and cost of the developing device.

Further, by forming the second agitating section 24, the space between the partition plate 5 and the doctor 10 is filled with the developer (there is no space), so that the volume of the developer does not easily change, so that the toner concentration is reduced. Easy to stabilize. Moreover, the developer is further scraped off by the doctor 10 to generate reflux, which is combined with the reflux generated in the stirring section 21, so that the stirring performance of the developer can be improved. Further, since the mounting position of the scraping member 20 is close to the toner supply port 6, the supplied toner can be sufficiently mixed and stirred.

Then, the toner stirring roller 13 has a biasing portion 13a and a crushing portion 13b
By providing and, it is possible to promote the mixing and stirring of the toner with the developer in the stirring section 21.

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

<Effects of the Invention> As is apparent from the above description, according to claim 1 of the present invention, the developer on the sleeve is located close to the developing roller between the doctor and the toner replenishing port from the toner replenishing tank to the developing tank. And a stirring unit for mixing and stirring the developer scraped by the scraping member and the replenished magnetic toner to keep the toner concentration of the developer constant. The scraping member is formed by being surrounded by a member and a sleeve. The scraping member has an opening for guiding the developer regulated by the doctor to the stirring unit and passing magnetic toner. The developer scraped off by the picking member, the developer regulated by the doctor and the developer and the magnetic toner are sufficiently agitated, and the magnetic toner is uniformly mixed with the developer to charge the toner. Improved In addition, the toner density of the developer becomes stable.

Therefore, the stirring roller and the toner concentration sensor in the developing tank can be eliminated, and the developing device can be downsized.
When the cost can be reduced, it has an excellent effect.

According to another aspect of the present invention, between the scraping member and the doctor, the second stirring unit for refluxing the developer regulated by the doctor in the direction of the stirring unit while stirring the developer in a pressurized state includes the doctor, the sleeve, and the partition plate. The developer formed by being surrounded by the second scraping member and the opening of the scraping member communicate with each other, and the developer refluxed by the second stirring unit is scraped off by the scraping member. Since the scraping member is disposed in the vicinity of the toner replenishing port so that the developer is mixed with the toner replenishing port, the developer is recirculated in a pressurized state by the conveying force of the developing roller in the second agitating section, and the volume of the developer is changed. It is difficult to stabilize the toner density. Moreover, the developer is further scraped off with a doctor to cause reflux, and this is combined with the reflux generated in the stirring section, so that the stirring performance of the developer can be improved. Further, since the scraping member is mounted at a position close to the toner replenishing port, the supplied toner can be sufficiently mixed and stirred.

According to a third aspect of the present invention, the toner replenishing tank is internally provided with a toner stirring roller for feeding the magnetic toner to the developer, and the magnetic toner is conveyed toward the toner replenishing port and pressed against the recirculated developer. Since a biasing portion and a crushing portion that vibrates the magnetic toner so as to crush the solidified developer pressed by the toner supply port are provided, the magnetic toner is pressed against the reflux generated in the stirring portion. Therefore, the mixing and stirring of the magnetic toner with the developer can be promoted.

[Brief description of drawings]

FIG. 1 is a sectional view of a developing device showing an embodiment of the present invention, FIG. 2 is an enlarged view of a main part of the same, FIG. 3 is a sectional view of a conventional developing device, and FIG. 4 is a developing roller and a photoconductor. 5 (a) and 5 (b) are diagrams showing the rotation direction, FIG. 5 (a) and FIG. 5 (b) are diagrams showing the pattern of the document to be printed, and FIGS. 6 (a) and 6 (b) are diagrams showing the pattern of the document subjected to reversal development. 2: developing tank, 3: magnetic toner, 4: toner replenishing tank, 8: developing roller, 9: developer, 10: doctor, 11: sleeve, 12: magnet body, 13: toner stirring roller, 20: scraping member , 21: stirring section, 24: second stirring section.

Front page continuation (72) Inventor Toshiyuki Kurosaka 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Co., Ltd. (56) Reference JP-A-61-261761 (JP, A) JP-A-62-55683 ( JP, A) JP 62-65066 (JP, A) JP 60-75854 (JP, A)

Claims (3)

[Claims] 1. A developing tank having a developing roller, which is composed of a sleeve and a magnet body provided rotatably with respect to each other, and
The developing tank is provided with a toner replenishing tank partitioned by a partition plate to replenish magnetic toner from the toner replenishing port to the developing tank, and the developing tank is provided with a doctor for regulating the amount of the developer on the sleeve. A scraping member for scraping off the developer on the sleeve is provided between the toner supply port and the doctor in the vicinity of the developing roller, and the developer scraped by the scraping member and the replenished magnetic toner are provided. Is formed by being surrounded by the scraping member and the sleeve for mixing and stirring the developer to make the toner concentration of the developer constant, and the scraping member is provided with the developer regulated by the doctor. A developing device, characterized in that an opening is formed which leads to the agitating portion and through which magnetic toner passes. 2. A second agitating portion between the scraping member and the doctor for circulating the developer regulated by the doctor in the direction of the agitating portion while agitating the developer regulated by the doctor, the sleeve, the partition plate and the doctor. The developer formed by being surrounded by the second scraping member and the opening of the scraping member communicated with each other, and the developer circulated by the second stirring unit was scraped off by the scraping member. 2. The developing device according to claim 1, wherein the scraping member is arranged in the vicinity of the toner supply port so as to be mixed with the toner supply port. 3. A toner replenishing tank is internally provided with a toner agitating roller for feeding magnetic toner to a developing tank, and the magnetic toner is conveyed to the toner agitating roller toward a toner replenishing port and pressed against the recirculated developer. The developing device according to claim 1, further comprising: a biasing portion and a crushing portion that applies vibration to the magnetic toner so as to crush the developer that has been pressed by the toner supply port and crushed.