JPH06130778A - Electrifier - Google Patents

Abstract

PURPOSE:To eliminate the occurrence of the nonuniformity of the density of a recorded image and fogging and to record the image of high accuracy and high printing quality in a long period by obtaining arrangement for making the contract points where an electrifying member comes into contact with an electrostatic latent image carrier of two or more. CONSTITUTION:In a part of the electrostatic latent image carrier 101 and the electrifying member 102, as the electrifying member, for instance, two electrifying blades 118 are used. The electrifying blade 118 is supported by a guide 121 and the free end is arranged so that the loop or edge of the electrifying blade 118 is in contact with the electrostatic latent image carrier 101. A DC power source 122 is connected among the conductive layers 119 of two electrifying blades 118 and the conductive supporting body 101a of the electrostatic latent image carrier 101 and the same voltage is applied to two electrifying blades 118 from one DC power source 122. In other words, a bias voltage is applied between the conductive supporting body 101a of the electrostatic latent image carrier 101 and a toner carrier.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device for an electrophotographic recording method such as a printer or a copying machine.

[0002]

2. Description of the Related Art Conventionally, electrophotographic recording methods have been generally used in optical printers, copying machines, etc.
A method of forming an image by each recording process of exposure, development, transfer, fixing and cleaning is well known.

As a charging device for the electrostatic latent image carrier in this method, a corona charger is generally used. Since this corona charger requires a high voltage power source of 5 to 10 kv, the human body Besides being dangerous, this high voltage power supply is very expensive. Also, the corona charger is
In order to utilize the corona discharge phenomenon, ozone is generated, which significantly deteriorates the characteristics of the electrostatic latent image carrier,
It has an adverse effect on the human body. In order to prevent this adverse effect on the human body, an ozone absorption / decomposition filter is provided in the image forming apparatus to prevent the outflow of ozone to the outside of the image forming apparatus. There is also a problem in that it must be done frequently.

Therefore, in order to solve the above-mentioned problems of the corona charger, JP-A-01-179959, JP-A-01-204081, JP-A-02-64668, JP-A-03-62057, and JP-A-03-100673 are used. Etc.,
Using a charging brush, charging roller, charging blade, etc. as the charging member, contacting the charging member with the electrostatic latent image carrier and applying a constant voltage from a DC power supply to charge the electrostatic latent image carrier A device has been proposed. These contact type charging devices have the advantages that ozone is less likely to be generated and that the voltage of the power supply can be lowered.

[0005]

However, these contact type charging devices have the following problems.
FIG. 11 is a charge potential model diagram of the electrostatic latent image carrier for explaining this problem. FIG. 11A is a charging potential model of the recording portion (exposure portion) and the non-recording portion (non-exposure portion) in the pre-recording process before passing through the contact type charging device, and FIG.
This is a charging potential model after charging the electrostatic latent image carrier in the next recording process after passing through the contact type charging device.

As the charging device, it is necessary to charge the residual potential VR of the exposed portion of FIG. 11 (a) to the charging potential Vs by one charging. However, in these conventional contact type charging devices, V of FIG.
The electrostatic latent image carrier can be charged only to the charging potential indicated by 1. To this end, in the following recording process,
At the charging potential after charging the electrostatic latent image carrier, a difference (V2) is generated in the charging potential between the recording portion (exposed portion) and the non-recording portion (non-exposed portion) in the pre-recording process, and the charging potential To Vs
Cannot be made uniform. As a result, when the next recording process is performed to record an image with high precision and high print quality, for example, recording a halftone or a thin line of 1 dot, there is a problem that unevenness in the recorded image density or fog occurs. .

According to the present invention, in the above-mentioned contact type charging device, the charging potential of the electrostatic latent image carrier cannot be made uniform to a desired potential by one charging, so that high precision in the next recording process, When printing an image with high print quality, such as halftone printing or fine printing of 1-dot thin line, the problem of density unevenness and fogging of the printed image is eliminated, and good high-definition, high-quality printing is achieved over a long period of time. An object of the present invention is to provide a charging device capable of stably recording a print quality image.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a contact type charging device used for forming an electrostatic latent image on an electrostatic latent image carrier, wherein a contact between the charging member and the electrostatic latent image carrier is Two or more pieces are arranged and a DC voltage is applied to this charging member.

[0009]

According to the present invention, in the contact type charging device,
By arranging the charging member and the electrostatic latent image carrier at two or more contact points, it is possible to charge to a desired potential by one charging, and the above-mentioned problems caused by the charging potential Can be solved.

[0010]

FIG. 2 is a schematic configuration diagram of an image forming apparatus using the charging device of the present invention. The electrostatic latent image carrier 101 formed in a drum shape is rotated at a constant peripheral speed in a direction indicated by an arrow A by a driving unit (not shown). This electrostatic latent image carrier 1
Reference numeral 01 denotes a photoconductive layer 101b provided on a conductive support 101a. In this embodiment, an organic photoconductor is used. However, a selenium photoconductor, a zinc oxide photoconductor, an amorphous silicon photoconductor, etc. Either can be used.

Next, the image forming process in this embodiment will be described in order. First, the electrostatic latent image carrier 101 is charged uniformly and uniformly by using the charging device 102 as a charging means provided so as to face the surface of the electrostatic latent image carrier 101. The charging device 102 will be described in detail later.

In the exposure process, the exposure device 103 as an exposure means irradiates the electrostatic latent image carrier 101 with light corresponding to an image signal to form an electrostatic latent image. As the exposure device 103, a combination of an LED array and a SELFOC lens (trade name) or a combination of a laser and an image forming optical system can be used.

A developing device 104 is provided in a state of being in close contact with the electrostatic latent image carrier 101 or at a minute space distance. The developing device 104 adsorbs the toner 106 on the toner carrier 105, and The image is conveyed in the direction B shown by the arrow in the figure, and is developed corresponding to the electrostatic latent image formed on the electrostatic latent image carrier 101. In this embodiment, the case of reversal development is shown, and the conductive support 101 of the electrostatic latent image carrier 101 is shown.
A bias voltage is applied between a and the toner carrier 105. With such a configuration, lines of electric force are generated in the space between the toner carrier 105 and the electrostatic latent image carrier 101 due to the electrostatic latent image formed on the electrostatic latent image carrier 101. For this reason,
The charged toner 106 on the toner carrier 105 adheres to the electrostatic latent image carrier 101 by electrostatic force and is developed to form a toner image. As the developing device 104, any known technology such as a two-component magnetic brush developing device, a one-component magnetic brush developing device, a one-component non-magnetic contact developing device, a one-component non-magnetic non-contact developing device can be used.

After that, the recording paper 108 accommodated in the paper cassette 107 is taken out from the paper cassette 107 by the paper feed roll 109, and the rotation of the paper feed roll 1 is stopped.
Then, the skew of the recording paper 108 is corrected.
Here, the paper feed roll 110 is activated and the recording paper 108 is fed to the transfer portion, and the transfer device 111 transfers the toner image formed on the electrostatic latent image carrier 101 to the recording paper 108.

After that, the recording paper 108 is fixed to a fixing device 114 composed of a pressure roll 112 and a heating roll 113.
Be transported to. The heat of the heating roller 113 melts the toner 106, and the toner 106 permeates between the fibers of the recording paper 108 due to the action of pressure, so that the toner 106 is fixed to the recording paper 108.
The fixed recording paper 108 is ejected to the outside of the apparatus by the paper ejection roll 115.

On the other hand, some toner may remain on the electrostatic latent image carrier 101 after transfer, but at that time, it is removed by the cleaner 116. In this way, the electrostatic latent image carrier 101 is repeatedly used.

Next, a first embodiment of the charging device 102 will be described in detail with reference to FIG. FIG. 1 shows a part of the electrostatic latent image carrier 101 and the charging device 102 of FIG. 2, and shows an example in which two charging blades 118 are used as charging members.

The charging blade 118 is composed of a conductive layer 119 and a resistance layer 120. The charging blade 118 is supported by a guide 121, and the open end of the charging blade 118 is arranged in contact with the antinode or edge of the charging blade 118 as shown in the electrostatic latent image carrier 101. A DC power supply 122 is connected between the conductive layer 119 of the two charging blades 118 and the conductive support 101a of the electrostatic latent image carrier 101, and one charging blade 118 is connected to the two charging blades 118. The same voltage is applied from the DC power supply 122. The polarity of the voltage applied to the conductive layer 119 of the DC power source 122 shows the case of a negative value because this is because the negative charge type electrostatic latent image carrier 101 is used, and the positive charge type electrostatic latent image carrier 101 is used. When the latent image carrier 101 is used, the polarity of the voltage applied to the conductive layer 119 of the DC power supply 122 is positive.

The conductive layer 119 has a volume resistance value of 10
Any material may be used as long as it is ⁴ Ω · cm or less,
For example, a springy thin metal plate such as SK steel, stainless steel, phosphor bronze, copper, nickel silver, beryllium copper, etc.
A thin plate having a thickness of 1000 μm or a volume resistance value of 10 ⁴ Ω · cm or less, and a rubber hardness of 90 ° or less in order to obtain a suitable contact width with the electrostatic latent image carrier 101 uniformly in the longitudinal direction of the contact surface ( It is a blade-shaped conductive rubber or the like according to JIS A).
For example, rubber materials such as butyl rubber, chloroprene rubber, urethane rubber, silicon rubber, nitrile rubber, styrene rubber, butadiene rubber, ethylene propylene rubber, carbon, graphite, ferrite, aluminum powder, copper powder, bronze powder, stainless steel powder, titanium oxide. , Conductive powders such as tin oxide, metal powders, those to which metal fibers are added, or polymer films of soft fat made of resins such as polyimide, polyamide, polyester, polystyrene, polycarbonate, and fluorine resin, carbon, graphite ,
It is preferable to add conductive powder such as ferrite, aluminum powder, copper powder, bronze powder, stainless steel powder, titanium oxide and tin oxide, metal powder and metal fiber.

In this embodiment, the resistance layer 120 has a thickness of 2
mm, short side 25 mm, long side 250 mm urethane rubber with conductive carbon added to give a volume resistance value of 10 ⁶ to 10
A conductive rubber blade having a resistance of ¹¹ Ω · cm and a rubber hardness of 60 ° (JIS A) was used. As the conductive layer 119, a stainless steel plate having a thickness of 100 μm is used.
9 and the resistance layer 120 were in contact with each other, so that the conductive layer 119 and the resistance layer 120 were electrically connected.
Also, the long side length (250 mm) of these charging members
Is determined by the length in the longitudinal direction of the photoconductive layer 101b of the electrostatic latent image carrier 101, and in the production of the electrostatic latent image carrier 101, the circumference of both ends in the longitudinal direction of the electrostatic latent image carrier 101 is determined. Since the photoconductive layer 101b is difficult to form on the upper side, the longitudinal direction of the photoconductive layer 101b of the electrostatic latent image carrier 101 is prevented so that the current of the DC power supply 122 to the electrostatic latent image carrier 101 does not leak. It is slightly shorter than the length.

The material of the resistance layer 120 of the charging blade 118 is, for example, butyl rubber, chloroprene rubber, urethane rubber, silicon rubber, nitrile rubber, styrene rubber,
Rubber, such as butadiene rubber, fluororubber, ethylene propylene rubber, etc., and polymer film of soft fat made of resin such as polyimide, polyamide, polyester, polystyrene, polycarbonate, fluorocarbon resin, carbon, graphite, ferrite, aluminum powder, copper Powder, bronze powder, stainless steel powder, conductive powder such as titanium oxide and tin oxide, metal powder, metal fiber, etc. are added to the resistance layer 120.
The volume resistance value of 10 ⁶ to 10 ¹¹ Ω · cm may be used. Further, the rubber hardness is 90 in order to make a suitable contact width with the electrostatic latent image carrier 101 uniform in the longitudinal direction of the contact surface.
Those of less than or equal to (JIS A) are preferable.

As described above, the conductive layer 119 may be any one as long as it has a volume resistance value of 10 ⁴ Ω · cm or less, such as a metal foil such as an aluminum foil or a copper foil,
A conductive tape having a volume resistance value of 10 ⁴ Ω · cm or less is attached to the resistance layer 120, or various metals are plated, sputtered, thick film printed, or the like to form the conductive layer 11 on the resistance layer 120.
It may be formed as 9. As described above, any method may be used as long as the conductive layer 119 and the resistance layer 120 are electrically connected. Further, since the charging blade 118 has to be an elastic body in order to make pressure contact with the electrostatic latent image carrier 101, at least the conductive layer 119 or the resistance layer 12 is required.
Any one of 0 may be an elastic body.

Two or three such charging blades 118 are provided downstream of the cleaner 116 and upstream of the exposure device 103.
A comparison between a case in which one unit is provided and brought into contact with the electrostatic latent image carrier 101 and a case in which one charging blade 118 which is a conventional technique is used will be described with reference to FIG. FIG. 3 shows the charging blade 11.
Volume resistance value of the resistance layer 120 of No. 8 and this charging blade 1
The difference between the saturated charge potential when the electrostatic latent image carrier 101 is charged in 18 and the charge potential charged by one charge (FIG. 11).
The relationship with V2) shown in FIG. Charging blade 1 here
The applied voltage to 18 is -1.4 kV, and the desired charging potential (Vs) at this time is about -800 V.

In the case of using one charging blade 118 as in the prior art, by reducing the volume resistance value of the resistance layer 120 of the charging blade 118 (10 ¹⁰ Ω · cm or less), the difference in charging potential, that is, the charging potential. Although the unevenness can be reduced, the charging potential unevenness of about 100 V still occurs. However, by providing two charging blades 118 as in this embodiment, the difference in charging potential, that is, the uneven charging potential can be reduced to about 30 V, and the volume resistance value of the resistance layer 120 of the charging blade 118 can be reduced. The range can be set to 10 ¹¹ Ω · cm or less, which is one digit wider than that of the conventional technique. Further, by providing three charging blades 118, it is possible to further reduce the charging potential unevenness and to reduce the difference in charging potential to about 10V, as compared with the case where two charging blades 118 are provided. The range of the volume resistance value of the resistance layer 120 of the blade 118 can be set to be two orders of magnitude wider than that of the prior art.

As described above, the charging blade 118
By providing two or more of them, the difference in charging potential, that is, the unevenness of charging potential can be reduced. Therefore, in the next recording process, high-definition and high-quality image recording, for example, halftone or 1-dot thin line is performed. When the recording is performed, it becomes possible to eliminate the problem that unevenness in the recorded image density and fogging occur. In addition, various experiments have shown that when the difference in charging potential is about 70 V or more, the electrostatic latent image formed in the previous recording process causes unevenness in the recorded image density or fog. By providing two or more charging blades 118,
Since the difference between the charging potentials, that is, the unevenness of the charging potentials can be set to about 30 V or less, it is possible to perform good high-definition and high-quality image recording.

Next, a second embodiment of the charging device 102 will be shown. FIG. 4 shows a part of the electrostatic latent image carrier 101 and the charging device 1.
02 shows a second embodiment of No. 02, in which two charging blades 118 are supported by the same supporting member 130, and the open ends of the two charging blades 118 are electrostatic latent image carriers. As shown in 101, the antinodes or edges of the charging blade 118 are arranged in contact with each other. The two conductive layers 119 of the charging blade 118 and the electrostatic latent image carrier 10
One DC power supply 122 is connected to one conductive support 101a, and the same voltage is applied to the two charging blades 118. Even with this configuration,
As in the first embodiment, it is possible to reduce the charging potential unevenness, and it is possible to record an excellent image with high precision and high print quality.

Further, the mounting direction of the two charging blades 118 is changed from the trailing direction as shown in FIG. 4 to the counter direction as shown in FIG.
6, even if the charging blade 118 is in the trailing direction and the other charging blade 118 is in the counter direction and is in contact with the electrostatic latent image carrier 101 as shown in FIG. Similar results are obtained. Figure 4,
As shown in FIGS. 5 and 6, the two charging blades 118
By supporting the same support member 130, it is possible to expect a smaller size and lower cost of the recording apparatus than the case where the two support members 121 as shown in FIG.

7 and 8 show a third embodiment of the present invention, and FIG. 8 shows a modification of FIG. As shown in FIGS. 7 and 8, the tip shape of the resistance layer 120 is stepped or U-shaped, and the contact point between the resistance layer 120 of the charging blade 118 and the electrostatic latent image carrier is two or more. Even if the tip shape of the resistance layer 120 is formed and a DC voltage is applied to the charging blade 118 from a DC power source, the charging potential unevenness can be reduced as in the first embodiment. It is possible to record excellent high-definition, high-quality print images. By making the tip shape of the resistance layer 120 as described above, the same supporting member 13 as described above is formed.
The size and cost of the recording apparatus can be expected to be smaller than the method of supporting the recording medium at 0. Further, the tip shape of the resistance layer 120 is not limited to the step shape and the U shape. For example, from the U shape to the C shape with the tip widened or the inverted C with the tip narrowed. Charging blade 11
Similar results can be obtained if the resistance layer 120 has a tip shape in which the number of contact points between the resistance layer 120 of No. 8 and the electrostatic latent image carrier 101 is two or more.

Next, a fourth embodiment of the present invention will be shown. The cleaning blade of the cleaner 116 in the image forming apparatus shown in FIG. 2 is replaced with a rubber blade that can be used for the resistance layer 120 of the charging blade 118 as shown in the first embodiment, and the electrostatic latent image carrier 101 is replaced. A case will be described in which the electrostatic latent image carrier 101 is electrically charged while removing the residual toner from the toner, and this and one charging blade 118 are used.

FIG. 9 is a view showing a part of the electrostatic latent image carrier 101 and the cleaner 116. The cleaning / charging blade 126 is supported by a metallic guide 127, and the edge of the open end is arranged in pressure contact with the electrostatic latent image carrier 101. A DC power supply 122 is connected between the guide 127 and the conductive support 101a of the electrostatic latent image carrier 101. A DC voltage is applied to the cleaning / charging blade 126 through the guide 127. With such a configuration, the cleaning / charging blade 126 removes (cleans) the residual toner 106 remaining on the electrostatic latent image carrier 101 after transfer from the electrostatic latent image carrier 101. The electrostatic latent image carrier 101 can be charged. One charging blade 118 as shown in the first embodiment is arranged upstream of the exposure device 103 and downstream of the cleaner 116, and the charging blade 118 is connected to the cleaning / charging blade 126 from the DC power source 122. Even if the same DC voltage as the voltage of the cleaning / charging blade 126 is applied to the conductive layer 119, it is possible to reduce the charging potential unevenness as in the first and second embodiments, and it is possible to obtain a high level. It is possible to record finely detailed and high print quality images.

Next, a fifth embodiment of the present invention will be shown. The first recovery blade is arranged so that the toner 106 collected by the cleaning blade of the cleaner 116 in FIG. 9 does not spill out from the cleaner 116.
Resistance layer 1 of the charging blade 118 as shown in the embodiment of
20 is used as a recovery blade 128 that also serves as a charging member, and the cleaning blade of the cleaner 116 shown in the fourth embodiment is used as the resistance layer 120 of the charging blade 118. The charging blade 126 is replaced with a rubber blade capable of cleaning and is used as a cleaning / charging blade 126 for charging the electrostatic latent image carrier 101 while removing (cleaning) it from the electrostatic latent image carrier 101.
Even if the same DC voltage is applied from the single DC power source 122 to the charging blade 126 for both cleaning and cleaning 28, the charging potential unevenness can be reduced as in the first to fourth embodiments, which is excellent. It is possible to record high quality images with high print quality.

By using the cleaning blade and the recovery blade as the charging blade as shown in the fourth and fifth embodiments, the method shown in the first to third embodiments can be used. Also, it is expected that the image forming apparatus will be smaller and the cost will be lower.

Next, a sixth embodiment of the charging device of the present invention will be described. FIG. 10 shows a case where two conductive rubber rolls 123 are used as the charging device 102.
24, a rubber resistance layer 125 is formed.

The conductive shafts 124 are metal shafts made of stainless steel, steel, aluminum or the like, and the two conductive shafts 124 and the conductive support 101a of the electrostatic latent image carrier 101 have the same DC power source. 122 is connected.

Examples of the material of the rubber resistance layer 125 include rubber materials such as butyl rubber, chloroprene rubber, urethane rubber, silicon rubber, nitrile rubber, styrene rubber, butadiene rubber, fluororubber, ethylene propylene rubber, carbon, graphite and ferrite. , Aluminum powder, copper powder, bronze powder, stainless powder, titanium oxide, tin oxide, and other conductive powders, metal powders, metal fibers, etc. are added, and the volume resistance value of the rubber resistance layer 125 is 10 ⁶ to 10 ¹¹ Ω.
・ It was set to cm. Further, in order to make a suitable contact width with the electrostatic latent image carrier 101 uniform in the longitudinal direction of the contact surface, a rubber hardness of 90 ° or less (JIS A) is suitable.

The conductive rubber roll 123 is driven by a drive system (not shown) in a direction C which is the same as the rotational direction A of the electrostatic latent image carrier 101 or the electrostatic latent image carrier 10.
It may be rotated in the same direction D as the rotation direction of 1, or may be fixed so as not to rotate. When the conductive rubber roll 123 is rotated in the tracing direction C, the peripheral speed of the electrostatic latent image carrier 101 and the peripheral speed of the conductive rubber roll 123 may be different or the same. Particularly, when the peripheral speed of the electrostatic latent image carrier 101 and the peripheral speed of the conductive rubber roll 123 are the same, it is particularly preferable because the conductive rubber roll 123 does not become a rotational load of the electrostatic latent image carrier 101.

Two such conductive rubber rolls 123
Even if is used as the charging member, it is possible to reduce the unevenness of the charging potential as in the first embodiment, and it is possible to record an excellent image with high precision and high print quality.

As described above, when two or more charging members 102 are used, the same voltage can be applied to the two or more charging members 102, so that only one DC power supply 122 is required. Since it is not necessary to provide a plurality of 122, the cost can be reduced.

Further, the charging blade 118 and the charging roller 1
Although the case of No. 23 has been described, the shape is not limited to these shapes, and a charging belt or the like may be used, and the volume resistance value of the portion in contact with the electrostatic latent image carrier 101 is 10 ⁶ to.
The contact point between the charging member 102 and the electrostatic latent image carrier 101 is 2 in the range of 10 ¹¹ Ω · cm.
The charging members 102 may be arranged in a number of more than one, and a DC voltage may be applied to the charging member 102 from the DC power supply 122.

The arrangement method can be changed variously. For example, in FIGS. 1, 4, 5, and 6, the charging blade 118
Is shown as a two-layer structure of the conductive layer 119 and the resistance layer 120.
Cleaning and charging blade 11 as shown in FIG.
As in the case of the resistance layer 120 only, the charging blade 118 is composed only of the resistance layer 120, and a conductor such as a metal is used as the guide 121.
20 may be electrically connected, and a DC power source 122 may be connected between the guide 121 and the conductive support 101a of the electrostatic latent image carrier 101.

Further, as the constitution of the charging blade 118, the two-layer structure of the conductive layer 119 and the resistance layer 120 and the one-layer structure of only the resistance layer 120 have been described. However, a low resistance layer is provided between the conductive layer 119 and the resistance layer 120. It goes without saying that a charging blade or charging roll having a three-layer or four-layer structure provided with an intermediate layer such as an elastic layer, a conductive elastic layer or a resin layer can also be used.
That is, the charging member 102 has a volume resistance value in the range of 10 ⁶ to 10 ¹¹ Ω · cm in the portion in contact with the electrostatic latent image carrier 101, and the charging member 102 and the electrostatic latent image carrier 10 are included.
The same result can be obtained by arranging two or more contact points with 1 and applying a DC voltage from the DC power supply 122 to the charging member 102.

Further, the cleaner 116 in FIG. 2 is removed, and the developing device 104 is a two-component magnetic brush developing device for contacting the electrostatic latent image carrier 101, or a one-component non-magnetic contact developing device for cleaner-less image formation. The method can also be used for devices.

In the embodiment, the reversal development is explained, but
It goes without saying that this method can be used even in the regular development method.

Further, the method of applying only the DC voltage to the charging member 102 has been described, but the method of applying the voltage in which the alternating current is superimposed on the direct current to the charging member 102 can also be used.

[0045]

As described above, according to the present invention,
In the contact type charging device, the volume resistance value of the portion in contact with the electrostatic latent image carrier is in the range of 10 ⁶ to 10 ¹¹ Ω · cm. Are arranged so that there are two or more contacts, and a DC voltage is applied to this charging member from a DC power source, so that the electrostatic latent image carrier is charged to a desired charging potential in one charging process. Therefore, in the next recording process, when an image recording with high fineness and high print quality, for example, recording of a halftone or a thin line of 1 dot, is attempted, unevenness in recorded image density or fog occurs. It is possible to eliminate the above problem, and it is possible to stably record a good fine image with high print quality for a long period of time.

When two or more charging members are provided,
In order to apply the same DC voltage from one DC power supply to these two or more charging members, a plurality of DC power supplies are not required, and not only two or more charging members are simply provided but also the same indicating member. It is also expected that the image forming apparatus can be downsized and the cost can be reduced by supporting the same with the charging blade, using the cleaning blade and the recovery blade also as the charging blade, and making the tip shape of the charging member into two or more divided shapes. .

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an image forming apparatus using the charging device of the present invention.

FIG. 3 is a diagram showing a relationship between a charging potential difference V2 and a volume resistance value.

FIG. 4 is a diagram showing a second embodiment of the present invention.

FIG. 5 is a diagram showing a modification of the second embodiment.

FIG. 6 is a diagram showing another modification of the second embodiment.

FIG. 7 is a diagram showing a third embodiment of the present invention.

FIG. 8 is a diagram showing a modification of the third embodiment.

FIG. 9 is an explanatory diagram of the fourth and fifth embodiments of the present invention.

FIG. 10 is a diagram showing a sixth embodiment of the present invention.

FIG. 11 is a charging potential model diagram of the electrostatic latent image carrier.

[Explanation of symbols]

 101 Electrostatic Latent Image Carrier 102 Charging Device 118 Charging Blade 119 Conductive Layer 120 Resistance Layer 121 Guide 122 DC Power Supply

Claims (1)

[Claims] 1. A charging device comprising a charging member provided in contact with an electrostatic latent image bearing member carrying an electrostatic latent image, wherein a contact point between the charging member and the electrostatic latent image bearing member. The charging device is characterized in that the charging member is arranged so that the number of the charging members is two or more.