JPH0261652A - Developing method - Google Patents

Abstract

PURPOSE:To reduce unnecessary waste toner by specifying the number averaged particle size of toner and specifying the ratio of the quantity of particles of less than the specific particle size. CONSTITUTION:The number averaged particle size of the toner is 50 - 10mum and the number of particles of <=5mum is <=10% of the total number of particles. Thus, the number averaged particle size is set to 5 - 10mum to obtain an image of high resolution and the number of toner of smaller particle size than <=5mum with large cohering force is decreased to reduce the unnecessary sticking of toner on a photosensitive body owing to van der Waals force (in inverse proportion to the value obtained by raising the particle size to 3rd or 4th power). Further, variation in mirror image force (in inverse proportion to the square of the particle size) of the toner to the photosensitive body is reduced and variance (where the electrostatic charging quantity of toner per unit weight is nearly in inverse proportion to the square of the particle size) in the electrostatic charging quantity distribution of the toner is suppressed by reducing the number of toner of fine particle size. Consequently, the unnecessary waste toner is reducible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a developing method, and more particularly to a contact type developing method.

[Prior Art] Conventional contact development methods include the contact development method disclosed in USP-2895847 and the contact development method disclosed in USP-3152.
An impression development method as disclosed in JP-A No. 012, a feed development method as disclosed in JP-A-57-114163, and the like have been devised.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, toner adheres to the non-image area on the photoconductor due to van der Waals force, etc., and a lot of toner is unnecessarily discarded, increasing the running cost of the device. Not only that, but also due to environmental changes, especially in low temperature conditions, the contact state changes, and toner with a small particle diameter with a large amount of charge per unit weight adheres to the non-image area. This causes the image to deteriorate significantly and cause so-called background smudges.

The present invention is intended to solve these problems, and its purpose is to provide a developing method that reduces unnecessary waste toner and has low running costs. Still another object is to provide a developing method that reduces image deterioration due to environmental changes. Still another object is to provide a contact type developing method that provides good images.

[Means for Solving the Problems] The developing method of the present invention includes a toner conveying body that is disposed adjacent to a latent image carrier that forms an electrostatic latent image and that conveys toner that is an image forming body. In a developing method in which an electrostatic latent image is visualized by pressing a toner conveying body against a latent image bearing body and electrostatically adhering the toner on the toner conveying body to the latent image bearing body, The number average particle diameter is 5 to 10 μm and 5 μm
It is characterized in that the number of particles of m or less is 10% or less of the total number of particles.

Further, the developing method of the present invention is characterized in that the number of particles having a particle diameter twice or more the number average particle diameter of the toner is 10% or less of the total number of particles.

Furthermore, the developing method of the present invention is characterized in that the toner conveying body includes at least a conductive support and an insulating layer, and the insulating layer is formed on the conductive support.

Further, in the developing method of the present invention, the toner transporting member includes at least a conductive support, an insulating layer, and a conductive powder, an insulating layer is formed on the conductive support, and at least one layer is formed inside or on the surface of the insulating layer. It is characterized by containing conductive powder.

[Function] According to the above configuration of the present invention, the number average particle diameter is 5 to 1.
A high-resolution image of 300 DPI or more can be obtained with 0 μm, and by reducing the number of toner particles with a small particle size of 5 μm or less, which has a large cohesive force, van der Waals force (3 to 4 of the particle size
It is possible to reduce unnecessary adhesion of toner to the photoconductor due to the force inversely proportional to the square of the particle size), and by reducing the number of toner particles with minute particle size, the mirror image force of the toner to the photoconductor (force inversely proportional to the square of the particle size) can be reduced. It is possible to reduce variations in the charge type distribution of toner (the amount of charge per unit weight of toner is inversely proportional to about the square of the particle size). Further, by regulating the number of toner particles having a coarse particle size, the output image density can be stabilized. Furthermore, in the contact development method that uses an elastic body as the toner transporting body, even if the electrical and mechanical properties of the toner transporting body change due to environmental changes, there are few toner particles with a small particle size, so van der Waals forces and mirror image Toner adhesion to non-image areas due to force can be reduced.

Hereinafter, the present invention will be explained in detail with reference to Examples.

[Example] Fig. 1 is a diagram showing the relationship between the environmental temperature and the background optical density value in the developing method in the example of the present invention, and shows the relationship between the environmental temperature and the background optical density value. It shows the optical density value of the background area (non-image area where toner should not originally be developed) when the particle size is changed to an almost arbitrary value of 5.
In developing method A of the present invention, in which the number occupancy rate of toner particles of 5 μm or less is approximately 8%, there is no toner adhesion to the background area and no image deterioration even if the environmental temperature changes. In developing method B, in which the toner number occupancy is approximately 15%, when the environmental temperature changes, toner adheres to the background area, especially in low-temperature areas, and the background area is smeared with toner, resulting in image deterioration.
Furthermore, the number occupancy rate of toner with a particle size of 5 μm or less has been increased to approximately 40%.
In developing method C, there is a remarkable tendency for image deterioration due to toner adhesion in the background area at low temperatures. Therefore, the environmental temperature is 10°
C The relationship between the number occupancy of toner with a particle size of 5 μm or less and the optical density value at a relative humidity of 40% RH is shown in Figure 2 in the solid image area (the area where the toner is developed and transferred solidly to form a solid image). When investigating the background area (non-image area where toner should not be developed and transferred), it was found that as the amount of toner particles with a particle size of 5 μm or less increases, the contrast of the image decreases. It has been found that when the number occupancy exceeds 10%, the background optical temperature becomes 0.1 or more, causing visible background stains. Therefore, the number occupancy of toner with a particle size of 5 μm or less is reduced to 1
By keeping it below 0%, a high-contrast image without background stains can be obtained. Moreover, FIG. 3 is a diagram showing the particle size distribution of toner used in each developing method shown in FIG. 1, and the symbols A, B, and C attached to each toner correspond to each developing method and are the same. Among the toner components, toner A has a number average particle size of 9 μm, the number share of toner with a particle size of 5 μm or less is 8%, the number share of toner with a particle size of 18 μm or more is 2%, and toner B has a number average particle size of 2%. Particle size is 8μm and particle size is 5μm
The number occupancy of the following toners is 15%, and the number occupancy of toner with a particle size of 16 μm or more is 2%, and toner C has a number average particle size of 6 μm and the number occupancy of toner with a particle size of 5 μm or less is 40.
%, the number occupancy of toner with a particle size of 12 μm or more is 20%, and it can be seen that the more toner with a fine particle size increases in the particle size distribution, the more the background smudge becomes more severe. In order to reduce the number occupancy of toner having a fine particle size of 5 μm or less, highly accurate classification or multiple classifications can be used. Furthermore, FIG. 4 is a diagram showing the relationship between the particle size of toner and the amount of charge, and the amount of charge per unit weight of toner is inversely proportional to the square of the particle size, and is 5 μm.
When the following minute toners increase, not only the electrostatic cohesive force between the toners increases, but also the mirror image force, which is the adhesion force of the toner to the photosensitive material. Therefore, the narrower the toner particle size distribution, the more stable the image temperature can be obtained. A Macbeth densitometer (manufactured by Macbeth Co., Ltd.) was used to measure the optical density value, and a Coulter Counter (manufactured by Nikkaki Co., Ltd.) was used to measure the particle size distribution.
For image formation, the latent image carrier is an organic photoreceptor in which a photoconductive layer is coated on a conductive support, and the photosensitive layer is brought to a predetermined potential with a charger. After being charged so that forming a latent image, while the developing device charges and transports toner, which is an image forming body, using a toner transporting body to be described later;
A developing bias is applied between the supporting part of the photoreceptor and the conductive support, toner is applied according to the potential contrast of the electrostatic latent image on the photoreceptor to make the latent image visible, and then the latent image is developed by a transfer device. The toner adhered to the photoreceptor is electrostatically transferred to the recording paper, and the toner is fixed on the recording paper by means such as pressure or heating to obtain a desired image.

FIG. 5 is a cross-sectional schematic view of a toner conveying body to which the developing method of the present invention can be applied, and the conductive support 51 is formed into an endless belt shape or a cylindrical shape using a conductive metal such as aluminum or stainless steel. An insulating layer 52 made of an elastic resin or a foamed resin with a rubber hardness of several tens of degrees is formed on the insulating layer 5.
2 is pressed against the photoconductor to develop the toner, but the insulating layer 5
Since the hardness and insulation resistance of 2 change with environmental changes, a toner with stable charge 1 and stable electrostatic adhesion is required, and by applying the present invention, stable output image density can be obtained. It will be done.

FIG. 6 is a cross-sectional schematic view of a toner conveying body to which the developing method of the present invention can be applied, and the conductive support 61 is formed into an endless belt shape or a cylindrical shape using a conductive metal such as aluminum or stainless steel. An insulating layer 62 made of an elastic resin or a foamed resin with a rubber hardness of several tens of degrees is formed on the insulating layer 62.
includes a plurality of conductor powders 63 inside or on the surface of the conductor powder 6
3 has a role similar to that of a carrier in a two-component development method and contributes to toner charging and transport, but when the hardness and insulation resistance of the insulating layer 62 change due to environmental changes, an electrostatic latent image due to the conductive powder 63 is generated. However, if a stable amount of charge and stable electrostatic adhesion can be obtained as described in this development method, unnecessary toner waste and background smearing in non-image areas can be reduced. can. The insulation resistance of the insulating layers 52 and 62 is preferably 106Ω or more, and the material of the toner that can be used for the toner transport body can be resin-based or wax-based, and it can also be applied to image formation using magnetic toner. Therefore, it is possible to form images using a variety of toners.

Although the embodiments have been described above, the present invention is not limited to the above embodiments, and can be widely applied as a developing method for electrophotography, especially for full-color printers that require high resolution and high gradation. It is effective when applied to contact type one-component development methods, such as monochrome copying machines, page printers, and facsimile machines that use component toners, copying machines, and video printers that record television images.

[Effects of the Invention] As described above, according to the above configuration of the present invention, a high resolution image can be obtained by setting the number average particle diameter to 5 to 10 μm, and the number occupancy rate of toner with a particle size of 5 μm or less can be obtained. 1
By setting the value to 0% or less, electrostatic aggregation of the toner is reduced, unnecessary adhesion of the toner to the photoreceptor due to van der Waals force is reduced, variation in the image force of the toner to the photoreceptor is reduced, and toner It is possible to provide a developing method that suppresses variations in the charge amount distribution, maintains stable image density, and reduces background smudges in the background and unnecessary waste toner even when the environment changes.

Further, by controlling the number occupancy of coarse toner particles having a number average particle diameter of twice or more to 10% or less, it is possible to provide a developing method that provides an output image density that is uniform and less susceptible to environmental changes.

Furthermore, in the contact development method that uses an elastic insulating layer for the toner transport body, even if the electrical and mechanical properties of the toner transport body change due to environmental changes, there are few toner particles with small particle sizes, so the van der Waals Since the adhesion of uncharged toner due to force is reduced, it is possible to reduce unnecessary waste toner and provide a developing method with low running costs.

Furthermore, in the contact development method, which uses a toner transport body containing conductive powder in an elastic insulating layer, in addition to the above-mentioned effects, variations in image force, which is one of the forces that cause toner to adhere to the photoreceptor or conductive powder, are To provide a high-quality developing method that prevents background smearing by preventing toner that is small and has an abnormally high electric charge from being developed in the background area even when the environment changes, and that causes less toner adhesion to non-image areas. be able to.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the environmental temperature and background optical density of the developing method in the example of the present invention, and Figure 2 is the number share of toner with a particle size of 5 μm or less in the developing method in the example of the present invention. FIG. 3 is a diagram showing the particle size distribution of the toner used in each developing method shown in FIG. 1. FIG. 4 is a diagram showing the relationship between the toner particle size and the amount of charge. FIG. 5 is a cross-sectional schematic diagram of a toner conveying body to which the developing method of the present invention can be applied;
FIG. 6 is a cross-sectional schematic diagram of another toner conveying body to which the developing method of the present invention can be applied. Fig. 1 51.61: Conductive support 52.62: Insulating layer conductor Powder stand -, n to □ t size - 4 items 6Hc] Fig. 2 Fig. 3 Fig. 4 Fig. 5 X6 diagram

Claims (4)

[Claims] (1) A toner conveying body is disposed adjacent to a latent image carrier that forms an electrostatic latent image and conveys toner as an image forming body, and the toner conveying body is pressed against the latent image carrier. In the developing method in which the toner on the toner conveying member is electrostatically adhered to the latent image carrier to visualize the electrostatic latent image, the toner has a number average particle diameter of 5 to 5. A developing method characterized in that the number of particles of 10 μm and 5 μm or less is 10% or less of the total number of particles. (2) The developing method according to claim 1, wherein the number of particles having a particle size twice or more the number average particle size of the toner is 10% or less of the total number of particles. (3) The developing method according to claim 1 or 2, wherein the toner transport body includes at least a conductive support and an insulating layer, and the insulating layer is formed on the conductive support. (4) The toner conveying body includes at least a conductive support, an insulating layer, and a conductive powder, the insulating layer is formed on the conductive support, and at least one layer is formed inside or on the surface of the insulating layer. Claim 1 characterized in that it contains the conductor powder.
Or the developing method described in 2.