JP2860995B2 - One-component contact development method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a developing method, and more particularly to a contact-type developing method.

[Prior Art] Conventional contact-type developing methods are disclosed in US Pat. No. 2,895,847, a contact developing method, an impression developing method as disclosed in US Pat. No. 3152012, and JP-A-57-114163. Such a feed developing method has been devised.

[Problems to be Solved by the Invention] However, in the above-described conventional technology, toner is attached to a non-image portion on a photoreceptor by van der Waals force and mirror image force, and a large amount of toner is discarded. Not only does it become high, but the contact state changes, especially in low temperature conditions due to environmental changes, causing the toner with a large amount of charge per unit weight to adhere to the non-image area and to have the same polarity as the toner in the image area. The image was transferred to the recording paper and the image was significantly deteriorated, so that a so-called background stain was generated.

Therefore, the present invention solves such a problem,
An object of the present invention is to provide a developing method which reduces unnecessary waste toner and has a low running cost. Still another object is to provide a developing method in which deterioration of an image due to environmental change is reduced. Still another object is to provide a contact-type developing method capable of obtaining a good image.

[Means for Solving the Problems] To achieve the above object, the one-component contact developing method according to claim 1 is arranged adjacent to a latent image carrier for forming an electrostatic latent image, and comprises an image forming body. A toner conveying member that conveys the one-component toner, and presses the toner conveying member against the latent image carrier to electrostatically adhere the toner on the toner conveying member to the latent image carrier to form the static toner. In a one-component contact developing method for visualizing an electrostatic latent image, the number average particle diameter of the toner is 5 to 10
μm, and the number of particles of 5 μm or less is 10% or less of the total number of particles.

The one-component contact developing method according to claim 2 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.

The one-component contact developing method according to claim 3, wherein the toner carrier includes at least a conductive support and an insulating layer, and the insulating layer is formed on the conductive support.

5. The one-component contact developing method according to claim 4, wherein the toner carrier includes at least a conductive support, an insulating layer, and conductive powder, wherein the insulating layer is formed on the conductive support, It is characterized by including at least one of the conductor powders inside or on the surface.

[Action] According to the above configuration of the present invention, the number average particle diameter is 5 to 10
A high-resolution image of 300 DPI or more can be obtained in μm, and has the same polarity as the toner adhered to the image portion by electrostatic force, van der Waalska (force inversely proportional to the 3rd to 4th power of the particle size), mirror image power ( Unnecessary adhesion of the toner to the photoconductor can be reduced by reducing the toner having a small particle size of 5 μm or less adhering to the non-image portion of the photoconductor by a force inversely proportional to the square of the particle size). In addition, the occurrence of background smear that deteriorates an image by transferring toner adhered to a non-image portion of the photoreceptor to recording paper is reduced. In particular, in the one-component contact developing method as in the present invention in which the toner carrier is pressed against the latent image carrier to electrostatically adhere the toner on the toner carrier to the latent image carrier, environmental changes, particularly in a low-temperature environment, Under this condition, the absolute humidity decreases, the electrical and mechanical properties of the toner carrier change, the toner is excessively charged, and the toner having a small particle diameter is relatively more charged to the same polarity (toner of the toner). The amount of charge per unit weight is inversely proportional to the square of the particle size), and the toner is conveyed to the toner carrier. In the present invention, this problem can be solved by making the toner having a fine particle diameter of 5 μm or less to be 10% or less of the total number of particles. In addition, by regulating the number of toners having a coarse particle diameter, the output image density can be stabilized.

 Hereinafter, the present invention will be described in detail with reference to examples.

FIG. 1 is a diagram showing the relationship between the ambient temperature and the background optical density value of a developing method in an embodiment of the present invention, wherein the ambient temperature is 10 to 40 ° C. (relative humidity 30 to 80% RH). This value indicates the optical density value of the background portion (non-image portion where the toner should not be originally developed) when the density is changed to almost any value, and the number occupancy of the toner having a particle size of 5 μm or less is about 8%. In the developing method A of the present invention, even when the environmental temperature changes, the toner does not adhere to the background and the image is not deteriorated. On the other hand, in the developing method B in which the number occupancy of the toner having a particle diameter of 5 μm or less is about 15%. When the environmental temperature changes, the toner adheres to the background in the low-temperature part, and the background is stained with the toner to deteriorate the image. Further, the number occupancy of the toner having a particle diameter of 5 μm or less is reduced to about 40%. In the case of C, the tendency of image deterioration due to toner adhesion on the background at a low temperature is remarkable. Therefore, the ambient temperature is 10 ° C and the relative humidity is 40% RH.
As shown in FIG. 2, the relationship between the number occupancy of the toner having a particle diameter of 5 μm or less and the optical density value is shown in FIG. When the non-image portion which should not be developed and transferred was examined, the contrast of the image was reduced as the number of toner particles having a small particle size of 5 μm or less increased. %, The optical density in the background became 0.1 or more, and it was found that obvious background soiling occurred. Accordingly, by suppressing the number occupation ratio of the toner having a particle diameter of 5 μm or less to 10% or less, an image having a high contrast without background contamination can be obtained. FIG. 3 is a view showing the particle size distribution of the toner used in each of the developing methods shown in FIG. 1, and the symbols A, B, and
C is a toner corresponding to each developing method and having the same component. Toner A has a number average particle diameter of 9 μm and a particle diameter of 5 μm.
The number occupancy of the following toner is 8%, the number occupancy of the toner having a particle diameter of 18 μm or more is 2%, and the number average particle diameter of the toner B is 8%.
The number occupancy of toner having a particle diameter of 5 μm or less is 15%, the number occupancy of toner having a particle diameter of 16 μm or more is 2%, and the number occupancy of toner having a number average particle diameter of 6 μm and a particle diameter of 5 μm or less is 15%. Is 40% and the number occupancy of toner with a particle size of 12μm or more is
It is 20%, and it can be seen that the background stain becomes more remarkable as the particle size distribution becomes larger with toner having a fine particle size. In order to reduce the number occupancy of the toner having a fine particle diameter of 5 μm or less, it is possible to perform the classification with high accuracy or a large number of classifications. FIG. 4 is a graph showing the relationship between the particle size of the toner and the charge amount. The charge amount per unit weight of the toner is inversely proportional to the square of the particle size.
When the amount of fine toner of 5 μm or less increases, not only does the electrostatic cohesion of the toners increase, but also the mirror image force, which is the adhesion of the toner to the photosensitive member, increases. Therefore, the narrower the particle size distribution of the toner, the more stable the image density can be obtained. The optical density value was measured using a Macbeth densitometer (manufactured by Macbeth), and the particle size distribution was measured using a Coulter counter (manufactured by Nikkaki Co., Ltd.). Uses an organic photoreceptor coated with a photoconductive photosensitive layer on a conductive support, charges the photosensitive layer to a predetermined potential with a charger, and then emits it from a light source such as a laser. The resulting light is scanned using a rotating polygon mirror or the like, and is imaged on a photosensitive layer by an imaging optical system to obtain a potential contrast to form an electrostatic latent image on a latent image carrier. The toner, which is an image forming body, is charged and conveyed using a carrier, and a developing bias is applied between a support portion of the photoreceptor and the conductive support to reduce a potential contrast of an electrostatic latent image on the photoreceptor. The latent image is visualized by attaching toner according to the And configured to obtain a desired image to fix the toner to the recording sheet by the transfer by pressure and means, such as heating, the toner more deposited on the photosensitive member to electrostatically recording paper.

FIG. 5 is a schematic cross-sectional view of a toner carrier to which the developing method of the present invention can be applied. The conductive carrier 51 is formed in an endless belt or cylindrical shape using a conductive metal such as aluminum or stainless steel. An insulating layer 52 made of an elastic resin or a foaming resin having a rubber hardness of several tens of degrees is formed thereon, and the toner is developed by pressing the insulating layer 52 against a photoconductor, but the hardness and insulation resistance of the insulating layer 52 are reduced. Since it changes with environmental changes, it is necessary to use a toner that has a stable charge amount and a stable electrostatic adhesion. By applying the present invention, a stable output image density can be obtained.

FIG. 6 is a schematic cross-sectional view of a toner carrier to which the developing method of the present invention can be applied. The conductive carrier 61 is formed in an endless belt or cylindrical shape using a conductive metal such as aluminum or stainless steel. An insulating layer 62 made of an elastic resin or a foaming resin having a rubber hardness of several tens degrees is formed thereon and includes a plurality of conductive powders 63 inside or on the surface of the insulating layer 62. It has a role similar to the role and contributes to the charging and transport of the toner, but if the hardness and insulation resistance of the insulating layer 62 change with environmental changes, the electrostatic powder destruction and recharging by the conductive powder 63 occur, As described in the present development method, if a stable charge amount and a stable electrostatic adhesion force can be obtained, unnecessary toner waste and background contamination of the non-image area can be reduced. The insulation resistance of the insulation layers 52 and 62 is desirably 10 ⁶ Ω or more, and the toner material applicable to the toner carrier may be resin-based or wax-based, and may be applied to image formation using magnetic toner. It is possible to form an image with various kinds of toner.

Although the embodiments have been described above, the present invention is not limited to the above-described embodiments, and can be widely applied as a developing method of electrophotography, particularly a full-color printer requiring high resolution and high gradation. It is effective if applied to a contact-type one-component developing method such as a copier, a copier, a video printer for recording a television image, a monochrome copier using a one-component toner, a page printer, and a facsimile.

[Effects of the Invention] As described above, according to the present invention, temperature environment changes,
Particularly, in a low-temperature environment, even if the electrical and mechanical properties of the toner carrier itself change and the toner is excessively charged, it is possible to prevent the toner of the same polarity as the image portion from adhering to the non-image portion. Background dirt and unnecessary waste toner caused by the adhesion of the unnecessary toner to the image portion can be reduced.

Further, by setting the number average particle diameter to 5 to 10 μm, a high-resolution image can be obtained. By setting the number occupancy of toner having a particle diameter of 5 μm or less to 10% or less, electrostatic aggregation of the toner is reduced. Reduces unnecessary adhesion of toner to photoreceptor due to Van der Waals force, reduces dispersion of toner's mirror image on photoreceptor, and suppresses variation in toner charge distribution, changes environment with stable image density Even in this case, it is possible to provide a developing method in which background stains and unnecessary waste toner are reduced.

Further, by setting the number occupancy of the coarse toner having a number average particle diameter of twice or more to 10% or less, it is possible to provide a developing method capable of obtaining an output image density that is uniform and is not easily affected by environmental changes.

Furthermore, in the contact development method using an elastic insulating layer for the toner carrier, van der Waals is used because the toner having a small particle size is small even if the electrical and mechanical properties of the toner carrier change with environmental changes. Since the adhesion image of the uncharged toner is reduced by the force, unnecessary waste toner can be reduced, and a developing method with low running cost can be provided.

Furthermore, in the contact development method using a toner carrier containing a conductive powder in an insulating layer having elasticity, not only the above-described effect, but also a variation in a mirror image force, which is one of the forces that the toner adheres to the photoreceptor and the conductive powder. Provided is a high-quality developing method that can prevent the occurrence of background contamination without developing a small amount of toner having an unusually high charge even when the environment changes in a background portion and less toner adhesion to a non-image portion. be able to.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the ambient temperature and the background optical density of the developing method according to the embodiment of the present invention, and FIG. FIG. 3 is a diagram showing a relationship between optical density values, FIG. 3 is a diagram showing a particle size distribution of toner used in each of the developing methods in FIG. 1, FIG. FIG. 5 is a schematic cross-sectional view of a toner conveying body to which the developing method of the present invention can be applied, and FIG. 6 is a schematic cross-sectional view of another toner conveying body to which the developing method of the present invention can be applied. 51,61: conductive support 52,62: insulating layer 63: conductor powder

Continuation of front page (56) References JP-A-58-95748 (JP, A) JP-A-61-281251 (JP, A) JP-A-63-73271 (JP, A) JP-A-63-101857 (JP) JP-A-60-115964 (JP, A) JP-A-1-297657 (JP, A) JP-A-53-26135 (JP, A) JP-A-62-284364 (JP, A) (58) Field surveyed (Int.Cl. ⁶ , DB name) G03G 15/08 G03G 9/08

Claims (4)

(57) [Claims] An image forming apparatus is provided with a toner transporter disposed adjacent to a latent image carrier for forming an electrostatic latent image and transporting a one-component toner as an image forming body. A one-component contact developing method in which the toner on the toner carrier is electrostatically adhered to the latent image carrier by pressing to develop the electrostatic latent image, wherein the number average particle diameter of the toner is 5 A single-component contact developing method, wherein the number of particles having a particle size of 5 to 10 μm is 10% or less of the total number of particles. 2. The one-component contact developing method according to claim 1, wherein the number of particles having a particle diameter of at least twice the number average particle diameter of the toner is 10% or less of the total number of particles. 3. The one component according to claim 1, wherein the toner carrier includes at least a conductive support and an insulating layer, and the insulating layer is formed on the conductive support. Contact development method. 4. The toner carrier includes at least a conductive support, an insulating layer, and a conductive powder, wherein the insulating layer is formed on the conductive support, and at least one of the conductive layers is provided inside or on the surface of the insulating layer. The one-component contact developing method according to claim 1, wherein the conductive powder comprises: