JPS5953542B2 - How to determine the degree of deterioration of developer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an apparatus for developing an electrostatic latent image formed on a photoreceptor through a predetermined process using a powder developer consisting of toner and carrier that are frictionally charged with each other. The present invention relates to a method for determining the degree of deterioration of developer in a developer.

When the developer deteriorates, image density decreases, background stains occur, and image quality deteriorates.

Therefore, when the developer deteriorates, it must be replaced with a new developer. Since the degree of deterioration of the developer is not uniform, conventionally, it has been determined whether it is time to replace the developer by looking at changes in the image caused by the deterioration of the developer.

Alternatively, the developer was replaced when the number of copies or usage period specified by the manufacturer was reached, regardless of whether the developer had deteriorated or not. On the other hand, when a defective image occurs, it cannot be determined whether the cause is due to deterioration of the developer or a failure of the copying machine itself, and it takes time to repair it. The degree of developer deterioration according to the present invention is determined by attaching the toner floating in the developing device to a collection plate provided in the developing device, and comparing the amount of the attached toner with a judgment table prepared in advance. .

What is deposited on the collection plate is either degraded toner or non-degraded toner. Deteriorated toner has a reduced amount of charge or is charged with a polarity opposite to the initial polarity, has weak adhesion to the carrier, or is repulsive, and tends to float or fall. Therefore, such deteriorated toner is deposited on a collection plate that is either uncharged or charged to the same polarity as the initial toner charge,
Compare this with the comparison table, and if the amount of adhesion is large, it is determined that developer replacement is necessary, and if it is small, it is determined that replacement is not necessary. On the other hand, toner that has not deteriorated retains a sufficient amount of charge with its initial polarity. Therefore, if the developer is disturbed to make the toner float, and then a potential of a polarity and magnitude that allows the toner to be captured is applied to the collection plate, the toner can be deposited on the collection plate. . When the amount of adhesion is large, it means that there is little deteriorated toner, so a decision is made to continue using it, and when the amount of adhesion is small, it is decided to replace the developer. According to the method according to the present invention, the degree of deterioration of the developer can be determined extremely easily, and the structure of the apparatus used is also simple.

Therefore, an object of the present invention is to provide a simple method for determining the degree of developer deterioration.

A further object of the present invention is to provide the above-mentioned method which appropriately determines when to replace the developer, prevents the occurrence of defective images due to the use of deteriorated developer, and prevents the replacement of developer that can still be used. be.

A further object of the present invention is to provide the above-mentioned method for determining, when a defective image occurs, whether the cause lies in the developer or in the main body of the copying machine.

Preferred embodiments of the invention will be described below with reference to the drawings.

FIG. 1 shows a magnetic brush developing device to which an example of the present invention is applied. A container 1 contains a certain amount of developer 2 consisting of toner and carrier. Impellers 3 and 4 are rotatably provided on the lower left side of the interior of the container 1 . A rotatable non-magnetic sleeve 5 is provided on the right side of the inside of the container 1, and a stationary magnet 6 is placed inside the sleeve 5.
is accommodated. A doctor plate 7 is placed at the right end of the container 1 at a certain distance from the sleeve 5 with its tip facing the sleeve 5. A photosensitive drum 8 is located at the upper right of the sleeve 5 at a certain distance from the sleeve 5. Above the sleeve 5, a toner collection plate 9 that is curved concentrically away from the sleeve 5 is arranged to cover the container 1.
It is attached to the lid 10 of. One end of a scraper 11 is provided in contact with the upper left of the sleeve 5, and the entire scraper 11 is tilted downward. The developer 2 in the container 1 is stirred by impellers 3 and 4, and the toner and carrier are frictionally charged and attracted to each other.

The developer 2 is attracted to the surface of the sleeve 5 by the magnetic attraction force of the magnet 6, forming a magnetic brush. This magnetic brush is conveyed upward as the sleeve 5 rotates in the direction of the arrow, and after its height is regulated by the doctor plate 7, it comes into contact with the surface of the photoreceptor drum 8 that has been rotated in the direction of the arrow. The electrostatic latent image formed on the surface of the photoreceptor is developed. If the developer used has deteriorated after development, the amount of charge on the toner may have decreased, or the toner may have been charged in the opposite direction to its initial polarity, resulting in weak adhesion between the toner and the carrier. As a result of the repulsion, the toner floats from above the sleeve 5 and adheres to the toner collection plate 9.

The toner that has not deteriorated is scraped off from the surface of the sleeve 5 by the scraper 11 while being adsorbed by the carrier.
It falls between the impellers 3 and 4 and is reused for development. Since the amount of toner that adheres to the collection plate 9 varies depending on the number of copies or the time period, a comparison table 12 as shown in FIG. Determine the degree of deterioration of the developer. For example, after 10,000 copies have been made, if there is no toner attached to the collection plate, the developer has not deteriorated and can be continued to be used as is. For example, the developer has deteriorated and should be replaced. Alternatively, a comparison table as shown in FIG. 2A is provided on the toner-adhering surface of the collection plate, and when the number of copies reaches 20,000, for example, the toner is removed by rubbing the 20,000th page on the comparison table with your finger. However, the degree of deterioration can be determined by comparing the comparison table shown on the lower side with the toner adhesion amount on the upper side (see FIG. 2B). The collection plate can be provided at position 13 as shown by the two-dot chain line in FIG.

In addition, since deteriorated toner may be charged opposite to the initial charge polarity of the toner, a voltage with the same polarity as the initial charge polarity of the toner is applied to the collection plate to actively remove the deteriorated toner. Can be adsorbed. Furthermore, if the floating toner is carried by the air flow, the collection plate can be provided at any position. FIG. 3 shows a magnetic brush developing device in which a deteriorated toner collecting plate is provided below the developing device.

The collection plate 14 is placed in a holder 15 provided below the non-magnetic sleeve 5, and the left side wall of the holder 15 also serves as a doctor plate 7 for regulating the thickness of the magnetic brush. If the developer 2 in the container 1 has deteriorated,
The deteriorated toner in the magnetic brush on the surface of the sleeve 5 that has passed through the doctor plate 7 is released from the electrostatic restraint with the carrier, falls under its own weight, and adheres to the collection plate 14 .

The degree of deterioration is determined by comparing the amount of adhesion with the comparison table in the same manner as above. FIG. 4 shows a magnetic brush developing device equipped with a disturbance member for actively suspending deteriorated toner.

On the surface of the Stareper 11 where the developer flows down after development,
Two triangular pieces 16 and 17 are provided as disturbance members, and a holder 18 is provided on the left side thereof, suspended from the lid 10 of the container 1. The toner collection plate 19 is placed on the holder 18. The developer on the sleeve 5 that has completed development is scraped off by the scraper 11, and while flowing down the scraper, it is disturbed by the disturbance members 16 and 17.
It becomes easier to float.

The floating degraded toner adheres to the collecting plate 19, and the non-degraded toner falls from the scraper 11 together with the carrier and is reused in the container 1. Providing a disturbance member in the developer flow path to actively adhere degraded toner in this way
The degree of developer deterioration can be determined in a short time.

That is, after cleaning the surface of the toner collecting plate, the developing device is driven for a short fixed period of time, or a fixed number of copies are made, and the state of adhesion is inspected. If toner is attached, the developer has deteriorated and the developer should be replaced; if no toner is attached, the developer has not deteriorated and should be continued to be used. All of the examples shown above are methods for attaching deteriorated toner to a collection plate, but in the same way, deteriorated toner that has not been removed is attached to a collection plate and the degree of deterioration of the developer is determined from this. be able to. Toner that has not deteriorated sufficiently retains its initial charge and is reliably attracted to the carrier. Therefore, it is possible to cause only this toner to adhere to the collection plate by disturbing the toner and making it float, and by applying to the collection plate a potential of the polarity and magnitude necessary to separate the toner from the carrier. If more non-degraded toner adheres to the collection plate, it means that there is less deteriorated toner, so it is necessary to determine whether to continue using the developer and check the adhesion.
If there is less toner, it means that there is a lot of deteriorated toner, so it is determined that the developer needs to be replaced. The judgment at this time is
Compare with the comparison table in the same way. Furthermore, by using two collection plates and applying voltages of predetermined polarity and magnitude to each plate, degraded toner and non-degraded toner can be deposited separately, allowing more precise determination of the degree of degradation. . The method according to the present invention is preferably applied to a developing device in which developer concentration is controlled to some extent.

This is because if the developer concentration becomes extremely high, the amount of charge on the toner particles decreases, which may lead to incorrect determination. The method according to the invention can also be applied not only to magnetic brush development devices, but also to all development devices that use a powder developer consisting of carrier and toner.

The material of the collection plate used in the method of this invention may be a conductor or an insulator coated with a conductor when a voltage is applied, or any other material that has the property to which toner can adhere. It can also be used.

Further, the toner collecting plate can be formed in a cylindrical shape.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a magnetic brush developing device to which an embodiment of the present invention is applied, FIG. 2 is a plan view of a comparison table for determining the degree of deterioration used in the method of the present invention, and FIG. The figure shows an example of a comparison table provided on the toner collection plate, FIG. 2B shows how to use the same, and FIGS. 3 and 4 show a magnetic brush developing device to which different embodiments of the present invention are applied. FIG. 9, 14, 19: Collection plate, 12: Deterioration degree determination comparison table, 1
6, 17: Disturbing member.

Claims (1)

[Claims] 1. In a developing device that develops an electrostatic latent image formed on a photoreceptor with a powder developer consisting of toner and carrier, and in which the concentration of the developer is controlled, the toner floating in the developing device is A method of determining the degree of deterioration of developer by applying electrostatic force to the surface of a collecting member provided in the device and comparing the amount of the adhered agent with a deterioration degree determination table.