JPS5953540B2 - Toner knowledge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an electronic copying system that visualizes an electrostatic latent image using a powder developer containing at least a carrier and a toner, in which the toner concentration in the developer is adjusted to an appropriate level. The present invention relates to a method for controlling a region and an apparatus for carrying out the method.

In an electronic copying system that visualizes an electrostatic latent image using a powder developer consisting of two or more components, including carrier and toner, the toner concentration in the developer determines the quality of the resulting copied image. This is one of the important factors that influences

On the other hand, if development is repeated, the toner in the developer is consumed, so toner must be appropriately replenished into the developer in order to maintain the toner concentration in the developer at the normal value.

Conventionally, in order to maintain the toner concentration in the developer at a normal value, the toner concentration in the developer is detected using various methods, and toner is replenished to keep the detected toner concentration constant. For example, a method that replenishes an appropriate amount of toner when the detected toner density becomes lower than a certain value, or a method that quantitatively replenishes an amount of toner according to the average amount of toner consumed per copy. Several methods have been proposed or implemented.

However, it is not so easy to measure and detect the toner concentration in the developer with appropriate accuracy, and there are problems such as not being able to perform a sufficient function to maintain the toner concentration, and the device for detecting the toner concentration becoming complicated. There were flaws.

The object of the present invention is to eliminate the need for detecting the toner concentration in the developer, and to be able to easily implement it using a device with a simple structure.
Another object of the present invention is to provide a new toner concentration control method that can effectively maintain the toner concentration of the developer in an appropriate range, and an apparatus for implementing this method.

Hereinafter, the present invention will be described by way of examples with reference to the drawings.

FIG. 1 schematically shows an example of a toner density control device embodying the present invention together with a developing device incorporating this device.

That is, in FIG. 1, numeral 1 is a photoreceptor, numeral 2 is a developer tank, numeral 3 is a sleeve which is a developer holding body, and numeral 4 is a developer tank.
5 is a separation plate, 5 is a stirring blade, 6 is a developer guide member,
Reference numeral 7 indicates a toner collecting member, 8 a blade, 9 a toner replenishing device, T a toner, G a developer, and E a DC voltage power source.

A DC voltage power source E, a developer guide member 6 surrounded by a broken line,
The toner collection member 7, the blade 8, and the toner supply device 9 are
This constitutes a toner density control device according to the present invention.

The photoreceptor 1 is formed into a drum shape, an electrostatic latent image is formed on its peripheral surface, and the photoreceptor 1 rotates in the direction of the arrow.

The sleeve 3 is formed into a hollow cylinder made of a non-magnetic material, and is provided so that a part of its circumferential surface is close to the circumferential surface of the photoreceptor 1 at a fixed position, and rotates in the direction of the arrow to absorb the magnetic field of the built-in magnet. By this action, the developer G, which is a mixture of carrier and toner, is drawn up from the lower part of the developer tank 2, held on its circumferential surface, and conveyed. At this time, the doctor section 2a formed at the end of the developer tank 2 regulates the amount of developer G to be conveyed. A portion adjacent to the photoreceptor 1 and the sleeve 3 is referred to as a developing portion. Developer G held on the circumferential surface of the sleeve 3
forms a magnetic brush in the developing section by the magnetic force of the magnet, the tip of the magnetic brush contacts the circumferential surface of the photoreceptor 1,
If an electrostatic latent image is formed on the circumferential surface, toner is applied to the electrostatic latent image to make it a visible image. The developer G that has contributed to the development is further conveyed through the developing section, is released from the restraint by the magnet of the sleeve 3, and part of it rides on the developer guide member 6, and the rest is transferred to the sleeve 3 by the separation plate 4. The developer is separated from the peripheral surface, flows over the separation plate 4, and is collected into the developer tank 2 again.

Now, the developer guide member 6 whose one end extends upward from the sleeve 2 is tilted downwardly toward the toner collection member 7 formed in the shape of a roller, and the vicinity of the other end is arranged so that the developer guide member 6 extends upwardly from the sleeve 2. It is formed so as to be close to the lower right peripheral surface of the collecting member 7 in FIG.

Therefore, the developer G that has climbed onto the developer guide member 6 is
The developer flows over the developer guide member 6 toward the toner collection member 7 , then flows down the gap between the toner collection member 7 and the developer guide member 6 , and is collected into the developer tank 2 . Now, a constant potential is applied to the roller-shaped toner collection member 7 by a DC voltage power source E, and it rotates in the direction of the arrow.

The polarity of the potential is opposite to the charged polarity of the toner in the developer G. Therefore, when the developer G comes into contact with the toner collection member 7, a portion of the toner in the developer G adheres to the surface of the toner collection member 7, and is transported by the rotation of the toner collection member 7. On the circumferential surface of the roller-shaped toner collection member 7,
At the top, the edge of the blade 8 is in contact. The other end of the blade 8 is located above the toner replenishing device 9. Therefore, the toner that adheres to the toner collecting member 7 and is conveyed is removed by the blade 8 from the toner collecting member 7.
The toner is separated from the circumferential surface of the toner, flows over the blade 8, and is collected in the toner replenishing device 9.

The toner replenishing device 9 is configured to be able to replenish an arbitrary amount of toner T into the developer G in the developer tank 2 by rotating a replenishment roller 9a in the direction of the arrow. The stirring blade 5 is
The supplied toner T is stirred into the developer 2. Now,
The present invention can be carried out using the apparatus as follows.

The amount of toner that adheres to the surface of the toner collection member 7 within a predetermined time TO, that is, the amount of toner that is collected by the toner collection member 7 from the developer G that comes into contact with it within the predetermined time TO, is determined by the toner collection member 7. voltage V of opposite polarity to the toner applied to the toner, the contact area f with the developer G9, the rotational speed v of the toner collection member 7, and the toner concentration ρ1 in the developer G in contact with the toner collection member 7. It is a function.

That is, if this collected toner amount is F, then F:F(V.f.V
, ρ1) (1).

However, once you design the device as shown in Figure 1,
Since the above f is uniquely determined, the collected toner amount F=F(V
, ρ1, v). Furthermore, if the potential V to be applied is determined, the amount F of collected toner is determined by the toner collecting member 7.
, and the toner concentration ρ1 in the developer G. That is, Jre▲\r1)ノ~-' Also, if the rotation speed of the toner collection member 7 is determined, ▲↓\
▼) r1 ~ υ Therefore, if we consider equation (3) as the basis, the toner concentration ρ of the developer G in contact with the toner collection member 7 can be calculated as follows:
This means that the collected toner amount F can be adjusted by adjusting the variable amount V depending on the situation.

Therefore, when formula (3) is illustrated using V as a parameter, it becomes as shown in FIG. 3.

In the figure, a region from ρ1 to ρ2 indicates an appropriate range of toner density, and ρo indicates an optimum value of toner density. Therefore, the developing device and toner density control device are now operated without forming an electrostatic latent image on the photoreceptor 1.

At this time, the toner concentration in the developer G is set to the optimum concentration ρ. Keep it. Then, the developer G is transported to the sleeve 2, but since no electrostatic latent image is formed, no toner is consumed in the developer. Therefore, the toner concentration in the developer G that comes into contact with the toner collection member 7 is ρ. It is.
Therefore, the amount of toner collected by the toner collecting member 7 during the predetermined time TO is F(V, ρo). Therefore, the amount of toner replenished from the toner replenishing device 9 is adjusted to be equal to F(V, ρo) per time TO. Then, in this state, the toner concentration in the developer tank 2 is ρ. Needless to say, it will be maintained. Next, consider performing development in this state.

When development is performed, toner is consumed in the developing section. However, in the case of the device shown in FIG. 1, the toner is consumed near the tip of the magnetic brush. The toner concentration inside is still ρ. It is.
However, in the developer G flowing on the developer guide member 6,
Due to toner consumption during development, the toner density is ρ. −△ρ
has declined to Then, at this time, the amount of toner collected by the toner collecting member 7 within the time TO is F(V, ρ. - △
ρ), but as is clear from Figure 3, F(V, ρ
o −△ρ)〈F(V, ρ.). Then, within the time TO, F(V, ρo) toner is replenished and F(V
, ρo-△ρ) are collected, but the difference between these, F(V, ρo)-F(, ρo-Δρ)=ΔF, is the toner consumed in the developing section within the time TO. Quantity M
, the toner concentration in the developer tank 2 is ρ on average. should be maintained. of course,
The amount M of toner consumed within the time TO in the developing section is
Naturally, this varies depending on the type of manuscript.

At this time, it is difficult for the toner collecting member to completely collect the toner, so it is difficult to satisfy ΔF=M, and in this toner replenishment method, the toner concentration ρ1 gradually decreases. Generally speaking, it is considered that the amount of toner consumed in the developing section during time TO follows a normal distribution, and the deviation thereof is not considered to be very large. Therefore, if the average amount of toner M consumed within time TO is Mt, then
Let F1 be the amount of toner recovered from the developer G that has consumed the amount of toner M, and then ΔF, that is, F(V, ρo)−
Setting ΔF=Mt for F1 can be achieved by adjusting the variable amount V, the variable amount v, or both. In this way, the toner concentration in the developer tank 2 can be maintained at a substantially constant concentration. This is because the average Mt of the amount of toner consumed within the time TO is minute if the time TO is on the order of seconds, such as 5 seconds or 10 seconds, and the deviation △Mt from this average is smaller than that. The deviation from △F that accompanies this deviation in consumption is an even smaller amount than △F, and if we consider this to be δF, this deviation will cause the time TO The deviation that occurs in the concentration of the developer G flowing on the developer guide member 6 per second is the toner amount δ
It is an extremely small value corresponding to F−△Mt, and moreover, △
Since it is considered that the proportion where Mt is positive and the proportion where Mt is negative are equivalent, the overall toner concentration in the developer G in the developer tank 2 is the optimum concentration ρ. It is possible to maintain the toner concentration within an appropriate range by only producing a small deviation around the toner. However, when the dispersion in the distribution of the amount of consumed toner is large, the range of deviation may become larger than the appropriate range of toner concentration.

In that case, the toner collection efficiency by the toner collection member 7 may be increased so that the amount of consumed toner becomes a very small amount with respect to the amount of collected toner. According to the apparatus diagram shown in FIG. 1, this can be achieved by increasing the absolute value V1 of the voltage applied to the donor recovery member 7 and increasing the rotational speed v. In this way, by increasing V, v, or both, the toner collecting ability of the toner collecting member 7 becomes nearly 100%, and even if the toner consumption amount M in the developing section fluctuates, the toner recovery amount F1 and the toner consumption amount M
The sum of these values is approximately constant. Therefore, the amount of toner to be replenished can be determined based on the relationship F1+M=F, and the toner concentration ρ1 in the developing device can be kept constant. FIG. 2 shows an embodiment in which the present invention is implemented in a cascade development system.

There seems to be no risk of confusion, so to avoid complications,
For equipment having the same role, the same symbols as in Figure 1 are used. In this embodiment, the developer G is distributed in pockets 10-1, 10-2, . . . of the conveyor belt 10.
. . 101 . Visualize.

The toner collecting member 7 is provided close to the lower end of the electrode plate 11, and the electrode plate 11 and the portion of the lower part of the developer tank 2 on the side of the photoreceptor 1 along the toner collecting member 7 are arranged as shown in FIG. It plays the role of the developer guide member 6 in . How to control the toner density is exactly the same as described with reference to FIG. As described above, according to the present invention,
It is possible to provide a toner concentration control method that can accurately and stably maintain the toner concentration within an appropriate range without detecting the toner concentration, and a toner concentration control device with a simple structure for implementing this method.

The toner density control according to the present invention may be performed constantly during the copying operation, or may be performed at the same timing as the development process each time development is performed.

In the case of timing the development process, the voltage application to the toner collecting member may be intermittent at the above-mentioned timing. The shape of the toner collecting member may be belt-like, and the method of keeping the toner collecting member at a constant potential may be using a DC voltage power source as in the above embodiment, but the circumferential surface of the toner collecting member may be formed of a dielectric, This may be carried out by applying an electric charge to the circumferential surface by corona discharge.

[Brief explanation of the drawing]

FIG. 1 is a side view schematically showing one embodiment of the invention, FIG. 2 is a side view schematically showing another embodiment of the invention, and FIG.
The figure is a diagram for explaining part of the principle of the present invention. 1...Photoreceptor, 3...Sleeve, 6...
... Developer guide member, 7 ... Toner collection member, 9 ... Toner supply device.

Claims (1)

[Claims] 1. In an electronic copying method that visualizes an electrostatic latent image using a powder developer containing at least a carrier and a toner,
A toner collecting member formed in the form of a belt or roller is maintained at a constant potential of opposite polarity to the toner, and while rotating, its surface is brought into contact with the flow of the developer that has contributed to the development, and the above-mentioned development is performed. An amount of toner equal to the amount F of toner collected by the toner collecting member within a predetermined time To, which is not long, when the toner in the developer is attached to the surface and collected, and the toner concentration in the developer is at an optimal value. is newly replenished into the developer every predetermined time To, and the average amount of toner consumed in the developing section within the predetermined time To is set as Mt, and after the amount Mt is consumed, the above is added to the developer. The amount of toner collected by the toner collecting member within the predetermined time To is F_1, and for Mt and F_1, F=Mt+
A toner density control method characterized in that the toner density is controlled to be F_1. 2. In an electronic copying method that visualizes an electrostatic latent image using a powder developer containing at least a carrier and a toner,
means for flowing or guiding all or part of the developer that has passed through the developing section to a predetermined position; a toner collecting member that moves and collects the toner in the developer by adhering it to the surface using a constant potential having a polarity opposite to that of the applied toner; and means for maintaining the toner collecting member at a constant potential having a polarity opposite to that of the toner. A toner concentration control device comprising: a member for scraping off toner from the toner collecting member and collecting it into a toner replenishing device; and a toner replenishing device for continuously or intermittently replenishing a developer with an arbitrary amount of toner.