JPH0369110B2 - - Google Patents

Description

[Detailed description of the invention]

1. Field of Industrial Application The present invention relates to a developing method for developing an electrostatic charge image on a photoreceptor using a developer containing a carrier and a toner. 2. Prior Art For example, in an electrophotographic copying machine, in order to improve the cleaning performance of residual toner on a photoreceptor drum, a material with a coefficient of friction of 100 to 100 is supplied to the surface of the photoreceptor.
A technique is known in which the residual toner is deposited as a very thin film of about 500 Å and the residual toner can be easily removed by this low friction film. For example, solids of zinc stearate are rubbed with a brush to adhere thereto, and then the brush is brought into contact with the surface of the photoreceptor drum, thereby forming a thin film of zinc stearate on the surface of the photoreceptor drum. . Alternatively, fine particles of zinc stearate are mixed into the toner, and the fine particles of zinc stearate are deposited on the photoreceptor together with the toner used for development to form a film. However, zinc in zinc stearate has the adverse effect of accelerating the crystallization of photoreceptors, particularly amorphous selenium, and deteriorates the characteristics of the photoreceptor. For this reason, it is necessary to control the amount of zinc stearate deposited on the photoreceptor so that it does not become excessive. Therefore, it has been proposed in JP-A-57-72173 and JP-A-57-97572 to supply copper or a copper alloy to the selenium layer, which has the effect of preventing crystallization of selenium. For example, zinc stearate pieces and copper pieces are sequentially rubbed off using a brush placed close to the photoreceptor drum, and particles of each substance are then deposited from the brush onto the surface of the photoreceptor. However, in this known technique, copper (or copper alloy) is supplied in the form of fine powder by a brush, and the fine powder comes into direct or excessive contact with the photoreceptor, so that copper (or copper alloy) is not deposited on the selenium layer. The diffusion rate increases and the selenium enters the surface area of the selenium layer in a relatively short time. As a result, due to the excessive amount of diffusion, the charging ability of the photoreceptor is rather reduced.
Therefore, it is difficult to control the supply rate and amount of copper or copper alloy, and the problem is that the charging ability is lowered rather than the crystallization prevention effect of selenium. Although methods for supplying copper or the like onto the photoreceptor have been proposed in addition to the methods described above, none of these methods allow the supply of copper or the like in an accurately controlled amount. 3. Purpose of the Invention The purpose of the present invention is to effectively prevent crystallization of a photoconductor while maintaining its cleanability,
The object of the present invention is to provide a method that does not cause deterioration of characteristics such as charging ability. 4 Structure of the Invention and its Effects That is, the present invention provides a method for developing an electrostatic image on a selenium photoreceptor using a developer containing a carrier and a toner. ) is mixed with the initial developer and the replenishment toner, respectively, and a powder of zinc stearate (cleaning accelerator) is mixed with the initial developer and/or the replenishment toner. This relates to a developing method. According to the method of the present invention, not only the initial developer but also the replenishment toner are mixed with a predetermined amount (i.e., a pre-controlled amount) of copper stearate crystallization prevention and cleaning aid, and this is (continuously or Since development is carried out while supplying the toner (intermittently), copper (in the form of a compound) can be supplied to the photoreceptor along with the toner in a controlled amount. For this,
The desired amount of anti-crystallization and cleaning aid is always present on the selenium photoreceptor, effectively eliminating the crystallization of the photoreceptor caused by the normal cleaning promoter of zinc stearate. Not only can this be prevented, but the total amount of copper diffusion into the photosensitive layer can be accurately controlled to sufficiently prevent deterioration of the charging ability of the photoreceptor due to excessive diffusion. Moreover, the usual cleaning accelerator of zinc stearate can be supplied in an appropriate amount from at least one of the initial developer and the replenishment toner, and the friction can be reduced by fatty acid residues, which are anti-crystallization and cleaning aids. Since this effect is also exhibited, the cleaning performance of the selenium photoreceptor can also be improved. In the method of the present invention, the powder of the crystallization prevention and cleaning aid is mixed in an amount of 0.05% by weight or less based on the total amount of toner and other additive components (excluding carrier in the case of initial developer). is desirable. That is, if the mixing amount exceeds 0.05% by weight, the amount supplied will be large and the charged potential of the photoreceptor will tend to decrease due to excessive diffusion. In this case, in order to sufficiently suppress a decrease in charging potential and prevent crystallization of the photoreceptor, it is particularly desirable that the content be 0.001 to 0.01% by weight (however, it is preferable not to include 0.01% by weight). 5 Examples Hereinafter, the present invention will be described in detail with reference to Examples. FIG. 1 shows an example of an ordinary type electrophotographic copying machine incorporating a photosensitive drum 9 having a photosensitive layer made of amorphous selenium or an amorphous selenium alloy.
In this copying machine, in the upper part of the cabinet 41,
A glass document mounting table 43 on which the document 42 is placed and a platen cover 44 that covers the document 42 are provided. Below the document table 43, a first mirror unit 4 including a light source 45 and a first reflecting mirror 46 is installed.
An optical scanning table consisting of 7 is provided so as to be movable linearly in the horizontal direction of the drawing, and a second mirror unit 2 is provided to keep the optical path length between the document scanning point and the photoreceptor constant.
0 moves according to the speed of the first mirror unit,
The reflected light from the document table 43 side is made to enter the photosensitive drum 9 as an image carrier in a slit shape through the lens 21 and the reflecting mirror 8.
Around the drum 9, a corona charger 10, a developing device 11, a transfer section 52, a separation section 53, and a cleaning section 54 are arranged. paper 58
After the toner image is transferred from the drum 9, the fixing section 59
The image is fixed and the paper is ejected to the tray 35. Fixing part 5
9, a heating roller 2 with a built-in heater 22 is shown.
3 and the pressure roller 24 to perform a fixing operation. The developing device 11 in this copying machine is constructed as clearly shown in FIG. This developing device basically includes a rotary developing sleeve 2 with a built-in fixed magnet 1, a main stirrer 4 (with a stirring plate 8) for the developer 3, and is used for transporting and auxiliary stirring of the replenishing toner 10. A spiral screw 6 is provided inside a housing 7, respectively. The developing sleeve 2 is disposed close to the photosensitive drum 9, and moves the charged developer 3 (a mixture of toner and carrier) into the gap between the drum and the drum to electrostatically adsorb it onto the drum 9. It functions to develop an electrostatic latent image into a toner image. The thickness of the developer 3 on the sleeve 2 is determined by a fixed thickness regulating plate 15. The toner 10 is stored in a container 12 on the spiral screw 6, and is intermittently or continuously supplied into the developing device from the pocket 13 via a rotary supply roller 14 with a pocket 13 disposed at the bottom of the container 12. be done. What should be noted here is that when performing development using the developing device 11, the initial developer (containing a magnetic carrier and toner) is stored in the housing 7 only during the initial stage of development, and the toner that is newly supplied afterwards. 10 (replenishment toner) and the original components such as toner and silica, copper stearate powder is added to the photoreceptor 9 as a crystallization prevention agent and as a cleaning aid. 0.05% by weight or less, particularly 0.001 to 0.01% by weight (for example, 0.005% by weight) of the carrier (excluding carriers). Therefore, the anti-crystallization and cleaning aid is replenished not only at the initial stage of development but also thereafter. Moreover, zinc stearate powder is added to both the initial developer and the replenishment toner as a cleaning promoter for the photoreceptor, so that the cleaning performance of the photoreceptor can be maintained well. The amount of zinc stearate powder added is, for example, 0.3% by weight. By performing development in this manner, a controlled amount of copper stearate powder can be constantly supplied onto the photoreceptor 9 together with the toner, so that the desired amount of copper stearate is automatically deposited on the surface of the photoreceptor. This makes it possible to sufficiently prevent selenium crystallization. At the same time, since the amount of copper stearate supplied can be accurately determined in advance, excessive diffusion into the selenium layer does not occur, and it is possible to always maintain a high charging potential of the photoreceptor. In addition, since zinc stearate can be supplied from the replenishment toner and initial developer, the above-mentioned cleaning aid effect of copper stearate is combined to form a good low-friction film on the surface of the photoreceptor, and after development. The cleaning performance of residual toner on the photoreceptor can be improved. Since this feeding method is carried out simultaneously with the developing process, there is no need to install special equipment such as the copper strip-brush combination in the prior art, and for this reason, only the precise control of the feeding amount described above is required. First, the structure inside the copying machine can be simplified. FIG. 3 shows experimental results showing changes in characteristics depending on the amount of copper stearate mixed in the initial developer and replenishment toner. According to this, when the content of stearic acid is less than 0.001% by weight, crystallization of the photoreceptor tends to occur, and when it exceeds 0.01% by weight (there is no practical problem up to 0.05% by weight), the charging potential deteriorates considerably. It was found that it is more likely to occur, and therefore 0.001 ~
It will be appreciated that a setting of 0.01% by weight is particularly desirable. This will be explained below using a specific example. Electrophotocopy machine U- manufactured by Konishiroku Photo Industry Co., Ltd.
Samples 1 to 4 shown in Table 1 below were prepared by adding 0% by weight, 0.005% by weight, 0.05% by weight, and 0.1% by weight of copper stearate powder (Kanto Kagaku reagent) into the toner used in Bix3000. did. However, 0.3% by weight of zinc stearate powder (Kanto Kagaku reagent) was added to each sample as a cleaning accelerator.

[Table] Using these samples and a carrier for U-Bix3000, an initial loading developer with a toner concentration of 2% by weight was prepared, and the developer was loaded into a developing device and a continuous printing test was conducted at a room temperature of 40°C. . Note that the same sample as the toner in each initial developer was used as the replenishment toner. Table 2 shows the change in the photoreceptor surface potential V _B (initial setting value: 900 V) at the development position when a black original with a reflection density of 1.3 was exposed.

[Table] From this result, it can be seen that when copper stearate is within 0.1% by weight based on the weight of the toner, the surface potential of the photoreceptor is maintained sufficiently high. Image defects caused by surface crystallization of the photosensitive layer occurred in the form of poor reproduction of halftone images and poor reproduction of pencil originals (character skipping) after 10,000 copies were made using the toner of Sample 1. .
On the other hand, when a sample to which copper stearate was added according to the present invention was used, surface crystallization of the photoreceptor did not occur within the 20,000 copy test. Note that the embodiments described above can be modified in various ways based on the technical idea of the present invention. For example, it is desirable to mix the cleaning accelerator that is mainly added to the replenishment toner with both the initial developer and the replenishment toner. It can also be mixed and supplied. Further, the developing method is not limited to the one described above, and various changes may be made, and the configuration of the copying machine may also be changed, such as a pressure intermediate transfer method (adhesive transfer and fixing method using a silicone rubber intermediate transfer member). You can also use it as The carrier used does not have to be a magnetic carrier. 6 Effects of the Invention As described above, the present invention adds a predetermined amount of copper stearate, which is a crystallization prevention agent and a cleaning aid, to the initial developer and replenishment toner that are supplied only at the initial stage of development, and And/or Since zinc stearate, which is a cleaning accelerator, is added to the replenishment toner, the amount of each supply (especially crystallization prevention and cleaning aid) onto the photoreceptor can be precisely controlled, and the crystallization of the photoreceptor can be controlled. The cleaning performance of the photoreceptor can be improved without deteriorating its charging ability. Moreover, since this is achieved by the operation of the developing device, no additional structural members are required from a structural standpoint, and the structure is simplified.

[Brief explanation of drawings]

The drawings show embodiments of the present invention, in which Fig. 1 is a schematic sectional view of an electrophotographic copying machine, Fig. 2 is an enlarged sectional view of a developing device, and Fig. 3 shows characteristics depending on the amount of copper stearate mixed. It is a graph showing changes. In addition,
In the symbols shown in the drawings, 2...Developing sleeve, 3...Developer, 4...Main stirrer, 6...Spiral screw, 9...Photosensitive drum, 10...Replenishment toner, 11... ...developing device, 14...replenishment roller, 15...toner thickness regulating plate.

Claims (1)

[Claims] 1. When developing an electrostatic charge image on a selenium photoreceptor using a developer containing carrier and toner, copper stearate powder is mixed with the initial developer and replenishment toner, and zinc stearate is mixed with the powder of copper stearate. A developing method characterized in that the powder is mixed with the initial developer and/or replenishment toner.