JPH08123108A - Image forming device - Google Patents

Abstract

PURPOSE: To remove or reduce the increasing effect of image density at an edge part and to uniformize the image density all over the image area by controlling so that the surface potential of an electrostatic latent image at the edge part may be a value between the potential values of a non-image part and an image part. CONSTITUTION: This device is provided with a photoreceptor drum 14, a latent image forming means for forming the electrostatic latent image on the surface of the drum 14, and a developing roller 16 developing the electrostatic latent image with electrostatically charged toner 22. When the circumferential speed (x) of the drum 14 and the circumferential speed (y) of the roller 16 developing the electrostatic latent image with the electrostatically charged toner 22 are x<y in the same direction at a developing position, the latent image is formed so that the potential of the electrostatic latent image at the trailing edge of the image part on the drum 14 may be the value between the potential values of the non-image part and the image part; and when they are x>y, the latent image is formed so that the potential of the electrostatic latent image at the leading edge of the image part on the drum 14 may be the value between the potential values of the non-image part and the image part. That is, the photoreceptor is exposed with light having energy that the electrostatic potential at the end of the image becomes the value between the potential values of the non-image part and the image part. Therefore, a toner layer at the end of the image is prevented from being thickened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as an electrophotographic copying apparatus and an electrostatic recording apparatus.

[0002]

2. Description of the Related Art Electrophotographic developing methods for developing a latent image using toner are roughly classified into a two-component method in which carrier powder and toner are mixed and a one-component method in which carrier powder is not used.

Among the one-component systems, it is difficult to form a color with a magnetic toner containing magnetic powder, and a non-magnetic toner is required to obtain a color image, particularly a full-color image.

In the case of the electrophotographic system, development is carried out by adhering it to the latent image holding portion due to a potential difference, but among the one-component system, a latent image carrier (in the case of forming a latent image by light, an inorganic material In the case of a contact development method in which an organic photoconductor is used) and a developing roller on which a toner layer is formed are in contact, a toner transport member having toner on the surface comes into contact with the photoconductor to form an electrostatic image. Supply toner to the section. When an image is continuously formed in the rotation direction of the electrostatic image forming member by this developing method, there is a problem that a larger amount of toner than usual is supplied to the edge portion or the end portion of the image. (Edge effect). In this case, in the output image, the edge portion becomes higher than the desired density, and the desired image cannot be obtained. Particularly, in the case of a color image, there is a problem that the image reproducibility is poor.

[0005]

As described above as the prior art, the effect of increasing the image density at the edge portion which occurs when outputting a continuous image is eliminated or reduced, and the image density is uniform over the entire image area. An object is to provide a certain image forming apparatus.

[0006]

According to the first aspect of the present invention, a latent image carrier, latent image forming means for forming an electrostatic latent image on the surface of the latent image carrier, and charging the electrostatic latent image. In an image forming apparatus having a developing means for developing with
The image forming apparatus includes a control unit that controls the surface potential of the edge portion of the electrostatic latent image to be a value between the potential values of the non-image portion and the image portion.

In the second invention of the present application, the latent image carrier and the developing means move in the same direction at the developing position, and the peripheral speed x of the latent image carrier and the peripheral speed y of the developing means are large. Saga
When x <y, control means for controlling the electrostatic latent image potential at the rear end of the image portion on the latent image carrier so as to form a latent image so as to have a value between that of the potential of the non-image portion. The image forming apparatus according to the first aspect of the present invention is characterized by comprising:

According to a third aspect of the present invention, the latent image carrier and the developing means move in the same direction at the developing position, and the peripheral speed x of the latent image carrier and the peripheral speed y of the developing means are large. Saga
When x> y, control means for controlling the electrostatic latent image potential on the front end of the image portion on the latent image carrier to form a latent image so as to have a value between the potential of the non-image portion. The image forming apparatus according to the first invention of the present application is characterized in that it has.

According to a fourth aspect of the present invention, when the latent image carrier and the developing means move in opposite directions at the developing position, the electrostatic latent image potential at the front end of the image part on the latent image carrier is changed to the non-image part. The image forming apparatus according to the first aspect of the present invention is characterized in that the image forming apparatus includes control means for controlling so as to form a latent image so as to have a value between the potential and the potential.

A fifth invention of the present application is an image forming apparatus having a photoconductor, an exposing means for forming an electrostatic latent image on the photoconductor surface, and a developing means for developing the electrostatic latent image.
The image forming apparatus according to the fifth aspect of the present invention is characterized in that the image forming apparatus includes the exposure unit that reduces the exposure energy per unit area of the edge portion of the electrostatic latent image.

In a sixth aspect of the present invention, the control means has means for determining a portion in the output image where an image is continuously formed in the rotational direction of the electrostatic latent image holding member. The image forming apparatus according to any one of the first to fifth aspects.

The present invention will be described below by way of example with reference to FIGS. 1 and 2 which are one-component non-magnetic electrophotographic image forming apparatuses. The outline of the present invention is that in an image forming apparatus, when an image is continuously formed in the rotation direction of the electrostatic image forming member (14 in FIG. 1), the electrostatic potentials of the edge portions of the image are non-image areas and image areas. The image forming apparatus includes a control unit that controls to form an electrostatic image so as to have a value between the potential values.

Further details will be described. First, the edge effect means that more toner than usual is supplied to the edge of the image, that is, the edge portion. The present invention provides an image forming apparatus having this edge effect removing function. The peripheral speed x of the electrostatic latent image carrier, that is, 14 photoconductors in this example, and the developing means for developing the electrostatic latent image with charged toner, that is, the peripheral speed y of 16 developing rollers in this example, are the same at the developing position. Direction and magnitude (1) x <y, the electrostatic latent image potential at the rear end of the image area on the latent image carrier is controlled so as to be a value between the potential of the non-image area. When an image is formed (2) x> y, the latent image is formed so that the electrostatic latent image potential on the front end of the image portion on the latent image carrier is a value between the potential of the non-image portion. . That is,
The photoconductor is exposed to light having energy such that the electrostatic potential at the edge of the image has a value between the potential values of the non-image portion and the image portion. This prevents the toner layer at the edge of the image from becoming thick. Usually, the area where the toner layer becomes thick (1 in FIG. 2) is 1/100 or less of the length L of the image. In this case, in the electrostatic latent image developing device of the present invention, the portion of the output image where the image is continuously formed in the rotation direction of the electrostatic image forming member is determined, the exposure energy is controlled, and the edge portion of the image is controlled. Has a function of reducing the exposure energy per unit area at the time of electrostatic image formation so that the electrostatic potential of is in a value between the potential values of the non-image area and the image area.

When the photoconductor and the developing roller move in opposite directions at the developing position, the same control as in (2) above is performed. Further, in the color filter printer shown in FIG. 3, the above process is performed for each color. As a result, an image having a desired color tone can be obtained.

When a latent image is formed by light, the electrostatic image forming member used in the present invention is a selenium alloy such as selenium, selenium histo, selenium tellurium or selenium histo-tellurium, C
Inorganic photoconductors such as dS, CdSe, CdSSe, ZnO or amorphous silicon, various types of organic photoconductors called OPCs (both single layer type and laminated type may be used), and have sufficient surface potential at the wavelength of the light source used. Anything that can form a latent image by reducing

Various types of OPC are known, and a single layer type photoreceptor is prepared by mixing a charge generating material, a charge transporting material and a binder resin. At this time, various crystal forms (α, β, γ, α, β, γ, etc.) of phthalocyanine-based pigments such as metal-free phthalocyanine, titanyl phthalocyanine, vanadyl phthalocyanine, and copper phthalocyanine aluminum chlorophthalocyanine are used as the charge generation material.
δ, ε, ζ, η, θ, ι, κ, λ, μ, ν, ξ, ο,
π, ρ, σ, τ, υ, φ, χ, ψ, ω, A, B, C, Y
Type, etc.), azo dyes and pigments such as monoazo, disazo, trisazo, tetrakisazo, perylene dyes and pigments such as perylene anhydride or perylene imide, perinone dyes and pigments, indigo dyes and pigments, quinacridone dyes and Pigment, anthraquinone,
Polycyclic quinone dyes and pigments such as dibromoanthanthrone, cyanine dyes and pigments, xanthene dyes and pigments, pyrylium, eutectic complexes consisting of thiapyrylium dyes and polycarbonate resins, azurenium dyes,
Examples thereof include squarylium dyes and charge transfer complexes of electron-donating substances and electron-accepting substances.

Charge transport materials include hydrazone compounds, pyrazoline compounds, oxazole compounds, oxadiazole compounds, thiazole compounds, thiadiazole compounds, imino compounds, ketazine compounds, enamine compounds, amidine compounds, stilbene compounds, butadiene compounds, carbazole compounds and A polymer compound in which these are introduced into the main chain or side chain of the polymer can be mentioned. The thickness of this single-layer type photoreceptor is appropriately determined according to the performance required for the photoreceptor, but is usually 2 to 25 μm. The multi-layer type photoconductor has a layer structure of a charge generating material and a charge transport material separately. As the charge generating material, the above compounds are dispersed in a binder resin such as polypinyl butyral resin and phenoxy resin, and various coating methods such as spin coating, dip coating, pulling method, roller coating, doctor blade coating and spray coating, and vacuum deposition. Method, a sputtering method, a glow discharge method, for example, a plasma CVD method or the like can be appropriately selected and employed. The thickness of the charge generation layer is appropriately determined according to the performance required for the photoreceptor, but is usually 0.1 to 2 μm.
Is.

Further, in the case of the charge transport layer, when the charge transport material does not have film-forming properties, the following binder resin and charge transport material are dissolved or dispersed in a suitable solvent, and this solution is applied, It is made by drying.

The binder resin includes polycarbonate, polyester, polyester carbonate, polyvinyl chloride,
Examples of the compounds known as a binder resin for electrophotographic photoreceptors include acrylic resins, vinyl chloride-vinyl acetate copolymers, polyvinyl acetals, phenol resins, and polyarylates.

In this case, it is preferable to mix the polymer compound in an amount of 0.3 to 2 parts by weight with respect to 1 part by weight of the charge transport material. Examples of the solvent include aliphatic chlorine-based, aromatic hydrocarbon-based, aromatic chlorine-based, ether-based, ester-based, and ketone-based organic solvents.

As the coating method, for example, spin coating,
Various coating methods such as dip coating, pulling up method, roller coating, doctor blade coating, and spray coating can be used. The thickness of the charge transport layer is usually preferably 10 to 30 μm.

Such an organic or inorganic photoconductor is usually formed on a support of a conductive support, and may be any known conductive support for photoconductor which is usually used, such as aluminum, Examples include metal materials such as brass, iron, and stainless steel, and resins having conductivity. When the photoconductive layer is provided on the conductive support, an adhesive layer may be provided if necessary. The adhesive layer can be appropriately selected from known resins such as casein and nylon, and preferably has a thickness in the range of 0.1 to 5 μm. Further, the shape of the conductive support is not limited to the drum shape as shown in FIG. Other examples include flexible endless sheets.

As the developing method, there are a reversal developing method in which toner adheres to a portion where the potential is lowered due to light irradiation, and a normal developing method in which toner adheres to a portion where the potential is kept without being irradiated with light. is there. When the latent image forming means of the present invention is a photoconductor, the present invention is limited to the reversal development method in which the toner adheres to a portion where the potential is lowered by irradiation with the former light.

The surface potential is not limited to positive or negative, and may be selected depending on the photoconductor used. Also,
An ion deposition type latent image forming method in which a dielectric is used instead of a photoconductor and a potential difference is formed by ion flow can also be used. In this case, the developing method may be either reversal or regular.

A case where a latent image is formed by a potential difference will be described with reference to FIG. In this case, the latent image carrier 14
The upper part is charged to a certain constant potential by using a corona discharge or a charging device 19 such as a charging roller or a charging brush, and the potential is changed by light or the like using the exposure means 20 to form a latent image. The smaller the diameter of the latent image holding member 14, the more easily the charging becomes non-uniform, and it is particularly remarkable at 20 mmφ or less. This is for the same reason as the abrupt change of the distance in the developing process. Such non-uniform charging causes deterioration of image quality such as increased image fog. Therefore, if the particle size distribution and charge amount distribution of the toner are as narrow as possible, this effect is less likely to occur. The material of the charging roller, charging brush, charging roller brush, etc. used at this time is
Any material can be used as long as it has conductivity and can charge the latent image holding member to a certain potential. For the roller, in addition to metal, conductive resin, elastomer, etc., for brushes, metal, carbon fiber, etc. In addition to a substance having conductivity itself, a substance obtained by combining a conductive filler with a resin or the like to form a fiber can be used. The roller does not have to have a single-layer structure, and a laminate of two layers or more may be used to obtain desired performance. The bias to be applied may be any of alternating current, direct current, and direct current superimposed on alternating current.

The developing roller 16 used here may be made of any material as long as it has conductivity and can apply a bias voltage to the toner. Examples include rigid metal bodies, electrically conductive resins, and electrically conductive elastomers with a low elastic modulus. These are also not used in a single layer structure, but are plated with a metal to modify the surface. It may also be coated or coated with a conductive paint. The bias to be applied may be any of alternating current, direct current, and direct current superimposed on alternating current.

In order to form a uniform toner layer on the developing roller 16, a blade or the like as the toner layer thickness regulating member 24 is required, but its shape, material, attachment site, etc. are applicable to the developing process. Anything is fine. For example, the material of the blade is a silicone-based resin or elastomer that tends to be positively charged by itself when the toner 22 is negatively charged, and a fluorine-based resin that is easily negatively charged by itself if the toner 22 is positively charged. Although the above resin or elastomer is recommended, its chargeability differs depending on the binder resin, pigment, CCA, etc. of the toner, so it is necessary to select the optimum material in the actual system.

Further, there are a method of cleaning the latent image holding member with a cleaning blade and a so-called cleanerless method of cleaning with the residual toner uniformizing member 18 and the like. A conductive fibrous substance is suitable for the cleaning brush, and in addition to a substance such as metal or carbon fiber which has conductivity itself, it is possible to use a fibrous substance obtained by compounding a conductive filler with resin or the like. it can. In addition to the brush-like shape, a brush-like roller in which the fibrous substance is radially fixed to the rotating shaft is also effective. The bias to be applied may be any of alternating current, direct current, and direct current superposed on alternating current, as long as the toner can be made uniform.

The toner image developed on the latent image carrier is printed on a paper 3
As the transfer means 17 for transferring to 1 or the like, there are a corona discharge method and a contact type transfer method using a roller, a brush or the like. When a bias is applied to the roller or brush, any of alternating current, direct current, and direct current superimposed on alternating current may be used.

The toner transferred onto the paper or the like is subject to heat, pressure,
Or it is fixed by chemical change. In the case of heat fixing, if a method capable of sufficiently applying heat necessary for fixing is used, in addition to a known heat roller, a heater (xenon lamp,
A method using a metal heater such as Nichrome or Kanthal) or a method of applying heat on demand to the toner portion may be used.

In the present invention, when the latent image carrier 14 is a photoconductor, the exposure energy per unit area of the image end portion is reduced. Therefore, as a method of realizing this, for example, when a laser is used as an exposure source, there are a method of reducing the laser scanning area and a method of reducing the exposure energy of the laser. The present invention may use either method. As the exposure source, any one of LED, LED array, phosphor head, EL, etc. may be used. In FIG.
An example of a method for controlling the exposure energy per unit area will be shown, but the present invention is not limited to this. The present invention is not limited to the one-component non-magnetic developing system, but can be applied to the two-component magnetic developing system and jumping system.

[0032]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. Example 1 A laser beam printer of A4 size capable of outputting 8 images per minute was prototyped using a laminated type negatively charged organic photoreceptor formed on a flexible sheet as a latent image carrier. This was subjected to one-component non-magnetic contact development using black toner containing polyester as a binder resin. The latent image carrier is charged with a scorotron to −500 V, and L =
A 10 cm solid image was written with a laser having a wavelength of 780 nm. At the developing position, the developing roller and the photoconductor were moved in the same direction for the development. Since the peripheral speed of the developing roller is 1.2 times the peripheral speed of the photoconductor, the end of the image 5
Laser exposure was performed so that the exposure area ratio would be 1/2 so that the mm portion has an exposure energy per unit area of 1/2 of other solid images. A roller was used for transfer. Cleaning was performed using a cleaning blade.

The image density output by the above process was measured. As a result, the image density of the output image was 1.3 over the entire area, and a uniform black solid could be output. Comparative Example 1 In order to suppress the edge effect in Example 1, laser exposure was performed at an exposure area ratio such that the end 5 mm of the image had an exposure energy per unit area of 1/2 of other solid images. . Therefore, as a comparative example, exposure was performed so that the exposure energy was constant in all areas of the solid image. As a result, the image density at the end of the image of about 5 mm was 1.6, and the edge effect was observed.

Example 2 A single-layer type positive-charge organic photoreceptor made of phthalocyanine, perylene, a hydrazone derivative, and polycarbonate was used as a latent image carrier on an aluminum drum having a diameter of 19.95 mmφ, and 4 sheets per minute of A4 size. We have prototyped a laser beam printer that can output images.

A one-component non-magnetic contact development using a black toner containing a styrene-acrylic copolymer as a binder resin was carried out. Use a scorotron to charge the latent image carrier +
It was performed so as to be 500 V, and a solid image of L = 60 cm was written with an LED array having a wavelength of 650 nm. At the developing position, the developing roller and the photoconductor were moved in the same direction for the development. Since the peripheral speed of the developing roller is 0.8 times the peripheral speed of the photoconductor, the strobe time is set to 1 so that the front end 5 mm of the image has an exposure energy per unit area of 1/2 of other solid images. Then, the exposure was performed. A roller was used for transfer. Cleaning was performed using a cleaning blade.

As a result, the image density of the output image was 1.3 over the entire area, and a uniform black solid could be output. Comparative Example 2 In order to suppress the edge effect in Example 2, the strobe time is set to 1 so that the front end portion of the image of 5 mm has an exposure energy per unit area of 1/2 of other solid images.
Then, the exposure was performed. Therefore, as a comparative example, exposure was performed so that the exposure energy was constant in all areas of the solid image. As a result, the image density at the front end portion of the image of about 5 mm was 1.7, and the edge effect was observed.

Example 3 A prototype of a printer capable of outputting 30 sheets of A4 size image per minute by an ion deposition system in which a dielectric is used as a latent image carrier and a potential difference is formed by an ion flow is produced.

One-component non-magnetic development was carried out using a black toner containing polyester as a binder resin. The particle size distribution of the black toner was measured with a Coulter Multisizer (manufactured by Nikkaki Co., Ltd.), and the volume average particle size D _{50 was} 7.5 μm, and the volume distribution was 5.3 μm or less 12.2%, 9.8 μm or more, 10 ．
It was 1%.

The latent image carrier was charged by a scorotron to −500 V, and a half image with L = 60 cm was written with a phosphor head. At the developing position, the developing roller and the photoconductor were moved in opposite directions for development. Since the peripheral speed of the developing roller is 1.2 times the peripheral speed of the photoconductor, the amount of ion flow per unit area is controlled so that the surface potential of the end 5 mm of the image is 1/2 the surface potential of other half images. did. A roller was used for transfer. For cleaning, a so-called cleanerless system was adopted in which a conductive brush was used without using a cleaning blade.

As a result, the image density of the output image was 1.5 over the entire area, and a uniform half image could be output. Comparative Example 3 In order to suppress the edge effect in Example 3, the ion flow amount per unit area was controlled so that the surface potential of the end 5 mm was half the surface potential of other solid images.
Therefore, as a comparative example, the amount of ion flow is made constant in all regions of the half image. As a result, the image density at the front end of the image of about 5 mm was 1.8, and the edge effect was observed.

Example 4 Using the same organic photoconductor as in Example 1, as a latent image carrier, a prototype of a color type laser beam printer capable of outputting four A4 size color images per minute was produced. This printer is a so-called tandem type color printer in which toners of respective colors of yellow, magenta, cyan and black are sequentially developed and transferred to paper or the like each time. Therefore, each color has a latent image holding step, a developing step, and a transfer step. For each color, one-component non-magnetic development was performed using toner (yellow, magenta, cyan, black) containing polyester as a binder resin. The particle size distribution of each toner was measured with a Coulter Multisizer (manufactured by Nikkaki), and the following results were obtained. Yellow has a volume average particle diameter D ₅₀ = 7.8 μm and a volume distribution of 5.
5 μm or less 10.1%, 10.1 μm or more 9.8%. Magenta has a volume average particle diameter D _{50 of} 7.5 μm, volume distribution of 5.3 μm or less 12.2%, 9.8 μm or more 10.1.
%. 11.9%. Cyan has a volume average particle diameter D ₅₀ = 8.3 μ.
m, volume distribution 5.8 μm or less 8.7%, 10.8 μ
m or more 13.1%. Black has a volume average particle diameter D ₅₀ = 8.
1 μm, 5.7% or less in volume distribution 8.9%, 10.
5 μm or more 11.9%. The ratio of the average particle diameter D ₅₀ of each toner was 1.11 for the most different one (cyan / magenta).

The latent image holding member was charged by using a scorotron so as to have a voltage of -500 V, and development was carried out so that the developing roller and the photosensitive member moved in the same pair direction at the developing position. Since the peripheral speed of the developing roller was 1.5 times the peripheral speed of the photoconductor, a half image of L = 60 cm was written with the phosphor head. Exposure was performed by adjusting the end 5 mm portion of the image so that the exposure energy per unit area was 1/2 that of other half images. An elastic roller was used for transfer. Cleaning was performed using a cleaning blade.

The full-color image output in the above process was evaluated as follows. Width 10m on the short side of A4
A solid image is output in the order of yellow, cyan, magenta, black, red, green, and yellow at m and an interval of 10 mm. The reproducibility of each color and the image density at that time were measured. As a result, the image density was extremely good at 1.5 in the entire area. In addition, the image was of extremely high quality with good color reproducibility.

Comparative Example 4 Using the same organic photoconductor as in Example 1 as a latent image carrier, a color type laser beam printer capable of outputting four A4 size color images per minute was prototyped. This printer is a so-called tandem type color printer in which toners of respective colors of yellow, magenta, cyan and black are sequentially developed and transferred to paper or the like each time.

Therefore, each color has a latent image forming step, a developing step and a transfer step. In addition, for each color, the toner (yellow,
One component non-magnetic development using magenta, cyan, black) was performed in the same manner as in Example 4 except that the exposure energy was kept constant in all regions of the half image.
As a result, the image density at the end of the image of about 5 mm is 1.
8, the edge effect was observed, and the color reproducibility was poor.

Example 5 In the same process as in Example 4, a so-called cleanerless system was adopted in which a conductive brush was used only for cleaning without using a cleaning blade. When a full-color image similar to that in Example 4 was output by the above process, the image density was extremely good at 1.5 in the entire area. In addition, the image was of extremely high quality with good color reproducibility.

Comparative Example 5 In order to suppress the edge effect in Example 5, the exposure was performed by adjusting the exposure energy per unit area of the solid image of 5 mm at the end of 5 mm. I did it. Therefore, as a comparative example, exposure was performed so that the exposure energy was constant in all areas of the solid image. As a result, the image density at the end of the image of about 5 mm was 1.8, the edge effect was observed, and the color reproducibility was poor.

Example 6 With the same process and toner as in Example 5, the latent image holding member is not charged by corona charging using a scorotron, but the conductive elastic roller is brought into contact with the latent image holding member while rotating. A roller charging method was used in which a DC bias voltage was applied to the roller to charge the latent image holder. The bias voltage was adjusted so that the surface potential of the latent image carrier was −500V for each color. When a full-color image similar to that in the fourth embodiment is output by the above process, the image density is 1.
It was 5 which was extremely good. In addition, the image was of extremely high quality with good color reproducibility.

Comparative Example 6 In order to suppress the edge effect in Example 6, the exposure was adjusted by adjusting the exposure energy per unit area of the 5 mm end portion of the image to be half that of other solid images. I did it. Therefore, as a comparative example, exposure was performed so that the exposure energy was constant in all areas of the solid image. As a result, the image density at the end of the image of about 5 mm was 1.8, the edge effect was observed, and the color reproducibility was poor.

[0050]

As described above, the effect of increasing the image density of the edge portion which occurs when outputting continuous images can be eliminated or reduced, and the screen density can be made uniform over the entire image area.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an image forming apparatus according to the present invention.

FIG. 2 is a partially enlarged view when viewed from A in FIG.

FIG. 3 is a schematic view of a color image forming apparatus according to the present invention.

FIG. 4 is a block diagram showing an example of control means according to the present invention.

[Explanation of symbols]

1, 14 Electrostatic latent image holding member (photosensitive drum) 2, 22 ··· Toner 2 ′, 22 ′ · · Transfer residual toner 3, 15 · · Developing device 4, 16 · · Toner alone (developing roller) 5 , 17 ・ ・ Transfer device (transfer means) 6 ・ Recorded material 7 ・ Cleaner 8 ・ Electrification removal lamp 9 ・ Charging device 10, 20 ・ ・ Light beam (exposure means) 11, 21 ・ ・ Toner supply body ( Toner supply roller) 12, 23 ··· Toner stirrer 13, 24 · · Toner layer pressure regulating member 25 · · Power supply 26 · · Transfer belt 27 · ·
Paper dust removing means 27a / paper dust removing roller 27b /
Opposing roller 28 ... Belt charger 29 ...
Belt cleaner 30 ... Supply roller 31 ...
Paper feed

Claims (6)

[Claims] 1. An image forming apparatus having a latent image carrier, a latent image forming unit for forming an electrostatic latent image on the surface of the latent image carrier, and a developing unit for developing the electrostatic latent image with charged toner. 2. The image forming apparatus according to claim 1, further comprising control means for controlling the surface potential of the edge portion of the electrostatic latent image to be a value between the potential values of the non-image portion and the image portion. 2. The latent image carrier and the developing means move in the same direction at the developing position, and the peripheral speed x of the latent image carrier and the peripheral speed y of the developing means are such that x <. When y, it has a control means for controlling the electrostatic latent image potential at the rear end of the image portion on the latent image carrier so as to form a latent image so as to have a value between that of the potential of the non-image portion. The image forming apparatus according to claim 1, wherein: 3. The latent image carrier and the developing means move in the same direction at the developing position, and the peripheral speed x of the latent image carrier and the peripheral speed y of the developing means are greater than x>. When y, it has a control means for controlling the electrostatic latent image potential on the front end of the image portion on the latent image holding member so as to form a latent image so as to have a value between that of the potential of the non-image portion. The image forming apparatus according to claim 1, wherein: 4. When the latent image carrier and the developing means move in opposite directions at the developing position, the electrostatic latent image potential on the front end of the image area on the latent image carrier is set between the potential of the non-image area. An image forming apparatus comprising: a control unit that controls to form a latent image so that the value becomes. 5. An image forming apparatus having a photoconductor, an exposing unit for forming an electrostatic latent image on the surface of the photoconductor, and a developing unit for developing the electrostatic latent image. An image forming apparatus comprising: a control unit that reduces exposure energy per unit area to an edge portion. 6. The control unit according to claim 1, wherein the control unit has a unit that determines a portion of the output image that continuously forms an image in the rotation direction of the electrostatic latent image holding member. Image forming device.