JPH04254871A - Contact electrification device - Google Patents

Abstract

PURPOSE:To stably retain an abutting condition of an electrification blade 2 to an image carrier 1 for a long time, and applying voltage to an electrification blade part of an abutting part with the image carrier body 1 without a problem, etc., of voltage drop, even if abutting pressure to the image carrier 1 due to the elasticity of the electrification blade 2 itself is lowered with the passage of time due to the permanent deformation of the electrification blade 2, in a contact electrification device in which the image carrier 1 is electrified by abutting the electrification blade (bladelike conductive member) 2 to the image carrier body (body to be electrified) 1. CONSTITUTION:A member 9, pressing an electrification blade part to an image carrier 1, is arranged on the back surface of an abutting part to the image carrier 1 of the electrification blade 2. Also voltage to the electrification blade 2 is applied to the said member with the said member 9 made conductive.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact charging device in which a conductive member is brought into contact with an object to be charged, and a voltage is applied to the conductive member to charge (including neutralize) the object to be charged. In particular, the present invention relates to an improvement in a contact charging device using a blade-shaped member as a conductive member.

0002

[Prior Art] A contact charging device applies a voltage (for example, several hundreds of volts to
By applying a DC voltage of about 2 KV or a superimposed voltage of DC voltage and AC voltage, etc., discharge occurs in the gap between the charging member and the object to be charged, thereby obtaining the required charging potential.

Compared to a corona discharger, which is a non-contact type charging device, it has advantages such as lower voltage of the power supply, hardly any ozone is generated during the charging process, and the device configuration is simple. It is attracting attention as a means for charging an image bearing member such as a photoreceptor or dielectric material in an electrostatic recording device or an electrostatic recording device, and other objects to be charged.

[0004] The conductive member used as the charging member is a roller type.
It can be of any suitable shape or form, such as a blade type, rod type, block type, or brush type.
No. 53, No. 56-194349, No. 56-16516
Publication No. 6, etc.). The present invention particularly relates to an improvement in a contact charging device using a blade-shaped conductive member (hereinafter referred to as a charging blade).

FIGS. 5A, 5B, and 5C each show a schematic structure of an example of a contact charging device using a charging blade. In (A), 1 is a charged body, which in this example is an image carrier such as a drum-shaped electrophotographic photoreceptor that is rotationally driven in the direction of arrow a. 2 is a charging blade as a contact charging member. The charging blade 2 of this example has a blade-shaped conductive member 2a as a base, and the part surface of the member 2a that has an electrostatic influence on the image carrier 1 is selected from one or more types having a higher electrical resistance value than the conductive member 2a. It is coated with a resistance layer 2b.

Generally, as a material for the charging blade 2, the conductive member 2a is made of epichlorohydrin rubber or EP.
Use DM with conductive powder such as carbon black and metal oxides (zinc oxide, titanium oxide, etc.) dispersed therein, and PTFE dispersed paint (resin is urethane resin) for the resistance layer 2b.
It uses carbon dispersed in it.

The base side surface of the conductive member 2a of the charging blade 2 is adhered to the blade support member 3 with an adhesive 4 to support the charging blade 2 on the support member 3.
The support member 3 is fixedly supported by the immovable member 5 with its tip end in contact with the image carrier 1. Charged blade 2
In this example, the blade is disposed on the surface of the image carrier 1 with its tip facing in a counter direction with respect to the rotation of the image carrier 1 and pressed against the elasticity of the blade. In addition, for charging stability, the arrangement angle of the charging blade 2 with respect to the image carrier 1, that is, the angle θ between the charging blade 2 and the tangent OO at the contact point between the surface of the image carrier 1 and the charging blade 2, is approximately It is set at about 20°.

In this example, the voltage is applied to the charging blade 2 by using the blade support member 3 as a conductive member such as metal;
A conductive adhesive is used as the bonding adhesive 4 between the member 3 and the conductive member 2a of the charging blade 2, and by applying a voltage from the power source 6 to the conductive blade support member 3, the support member 3 and the conductive member 2a are connected. A voltage is applied to the conductive member 2a of the charging blade 2 via the adhesive 4, and the surface of the image carrier 1 is charged in a contact manner.

[0009] The voltage applied to the charging member in contact charging can be made uniform by applying an oscillating voltage in which an AC voltage is superimposed on a DC voltage corresponding to the charging potential. Here, the waveform of the AC voltage is a sine wave.
Square waves, triangular waves, etc. can be used as appropriate. Further, the AC voltage includes, for example, a rectangular wave voltage formed by periodically turning on and off a DC power source. In this way, the AC voltage is a voltage whose voltage value changes periodically. For example, as disclosed in Japanese Patent Application No. 61-298419, an alternating electric field having a peak-to-peak voltage that is more than twice the charging start voltage of the charged object when a DC voltage is applied to the charging member is applied to the charging member. By forming it between the charged body and the charged body, the charged body can be uniformly charged.

In the charging blade 2, the conductive member 2a may be brought into direct contact with the surface of the image carrier as the object to be charged without providing the resistive layer 2b, but in this case, a pinhole portion is formed in the image carrier. (Surface defects of the charged object), spark discharge is likely to occur between the conductive member under voltage application and the pinhole portion of the image carrier, and if such discharge occurs, the image carrier It is easy to see a so-called "charge drop" phenomenon in which the body surface is no longer charged with charge not only in the pinhole area but also over the entire charging area with the contact charging member including the pinhole area. In order to prevent this, in this example,
As proposed in the above publication, the conductive member 2a is provided with the resistance layer 2b as described above.

For adhesion between the blade-shaped support member 3 and the conductive member 2a of the charging blade 2, stronger adhesive strength can be obtained by using an insulating adhesive rather than the conductive adhesive 4. It is also a good idea to use double-sided adhesive tape. Figure 5(B) shows parts 3 and 2 using insulating adhesive or double-sided adhesive tape 4A.
A is glued. In this case, in order to establish continuity between the blade support member 3 that applies voltage and the conductive member 2a of the charging blade 2, a conductive paint 7 such as silver paste is applied to the boundary between the two 3 and 2a. 2a is made conductive. In this case, if the conductive portion 7 is made very small in order to reduce the cost of materials such as the conductive paint 7 and the amount of coating, it is possible to reduce the conductive portion 7 between the supporting member 3 side of the charging blade 2 and the tip portion that contacts the image carrier 1. Easy to cause voltage drop. Particularly under low humidity, the voltage drop is large. Charging by the charging blade 2 is performed by a discharge phenomenon in the vicinity of the contact area (between the minute gap) between the tip of the charging blade 2 and the image carrier 1, so a voltage drop at the tip of the charging blade causes charging failures. Therefore, it must be avoided. To avoid this voltage drop, ■. (2) Setting the voltage applied to the support member 3 by the power source 6 to a high level in advance in consideration of the voltage drop; Charging can be achieved by bringing the conductive member 8 into contact with the tip of the charging blade 2 as shown in (C) in FIG. Measures may be taken to avoid a voltage drop at the tip of the blade 2.

0012

[Problem to be Solved by the Invention] The contact pressure of the charging blade 2 against the image carrier 1, which is brought into pressure contact with the image carrier 1 as a charged member against elasticity, is such that the charging blade 2 is permanently deformed due to its material. Due to its large size, it deteriorates over time and the charged blade 2
The state of contact between the charging blade 2 and the image carrier 1 may become unstable, and therefore the charging in the vicinity of the contact portion of the charging blade 2 with the image carrier 1 may become unstable.

An object of the present invention is to stabilize the contact of the charging blade with the object to be charged over a long period of time, and therefore to stabilize the charging over a long period of time.

[0014]

[Means for Solving the Problems] The present invention is a contact charging device characterized by the following configuration. (1) In a contact charging device that performs charging by bringing a blade-shaped conductive member into contact with a charged object, the portion of the conductive member to be charged is placed on the back side of the part of the blade-shaped conductive member that contacts the charged object. A contact charging device characterized by disposing a member that presses against a body. (2) The contact charging device according to (1), wherein the member that presses the conductive member portion against the object to be charged is a weight, and the pressing is performed by the weight of the weight. (3) The contact charging device according to (1), wherein the member that presses the conductive member portion against the object to be charged is an elastic body, and the pressing is performed by the elastic force of the elastic body. (4) The member that presses the conductive member portion against the charged object is a member or magnetic body that has a magnetic force that generates magnetic attraction with the charged object, and the pressing is performed by the magnetic attraction force. The contact charging device according to feature (1). (5) The member that presses the conductive member portion against the object to be charged is conductive, and a voltage with respect to the blade-shaped conductive member is applied to the conductive pressing member (1) to (4). The contact charging device according to any one of the above. (6) A contact charging device using a blade-shaped conductive member is included in the process cartridge that is attached to and removed from the image forming apparatus main body, and presses or supplies voltage to the blade-shaped conductive member, or presses and supplies voltage to the blade-shaped conductive member. a blade-shaped conductive member on the process cartridge side and the operating member on the image forming apparatus main body side come into mutual contact when the process cartridge is installed in the image forming apparatus main body side. (1) The housing of the process cartridge is provided with a window that allows for
The contact charging device according to any one of (5) to (5).

[0015]

[Function] Even if the contact pressure of the blade-shaped conductive member itself as a charging member against the charged object decreases over time due to permanent deformation of the member, the contact pressure of the blade-shaped conductive member against the charged object remains unchanged. Due to the action of the pressing member, a contact pressure higher than the required minimum pressure is always ensured, and the state of contact of the blade-shaped conductive member as a charging member with the charged object is stabilized over a long period of time.
In other words, the charging process is stabilized over the long term.

By making the pressing member conductive and applying a voltage to the member, a bias can be directly applied to the part of the blade-shaped conductive member that comes into contact with the charged object, thereby reducing voltage drop, etc. You can avoid problems.

[0017]

[Example] <Example 1> (Fig. 1) 1 is an image bearing member such as a drum-shaped electrophotographic photoreceptor as a charged member, and arrow a
It is driven to rotate at a predetermined circumferential speed in the direction.

Reference numeral 2 denotes a charging blade, and this embodiment has a two-layer structure consisting of a conductive layer 2a and a resistance layer 2b.
is made by appropriately dispersing conductive powder of carbon black in epichlorohydrin rubber to give a volume resistivity of 1 x 106 Ωcm, and has a thickness of 1.5 mm and a hardness of JIS-A 60°.The resistance layer 2b is made of a PTFE dispersed paint ( The resin is urethane resin) with carbon appropriately dispersed to increase the surface resistivity to 1 x 10.
It was 9Ω/□ and had a coating thickness of 30 μm.

The charging blade 2 is integrally attached and supported on its base side to the blade support 3 using an insulating double-sided tape 4A with a strong adhesive strength.
The blade support 3 is fixedly supported by the immovable member 5 with its tip facing the counter direction with respect to the rotation of the image carrier and in contact with the image carrier 1 against the elasticity of the blade. In this case, the free length l (distance between d and c) of the charging blade 2 is 6 mm, and the angle θ between the charging blade 2 and the tangent 0-0 at the contact point between the charging blade 2 and the image carrier 1 is 18
The contact pressure of the tip of the charging blade 2 against the surface of the image carrier due to the elasticity of the blade itself was set to a linear pressure of 10 g/cm.

Reference numeral 9 denotes a member (pressing member) that presses the charging blade portion against the image carrier 1, which is disposed on the back side of the contact portion of the charging blade 2 with respect to the image carrier 1. The member 9 of this embodiment is a horizontally elongated bar member made of metal and serves as a weight, and has an electrically conductive portion with the conductive layer 2a of the charging blade on the longitudinal side of the back surface of the contact portion of the charging blade 2. They are placed in contact with each other. The weight W of the member 9 adds the contact pressure of the charging member 2 to the image carrier 1 . In this embodiment, the additional contact pressure due to the weight W of this member 9 is a linear pressure of 10 g.
/cm. Therefore, in this embodiment, the initial setting value of the contact pressure of the tip of the charging blade 2 with respect to the image carrier 1 is the above-mentioned linear pressure of 10 g/cm due to the elasticity of the charging blade 2 itself.
and the linear pressure of 10 g/cm due to the weight W of member 9, 20
g/cm.

Further, in this embodiment, the voltage applied to the charging blade 2 is applied to the member 9 from the power supply 6 on the main body side of the image forming apparatus (in this embodiment, a DC voltage).

Therefore, even if the contact pressure of the charging blade 2 against the image carrier 1 due to the blade's own elasticity decreases over time due to permanent deformation of the blade, the line which is the contact pressure due to the weight W of the member 9 A pressure of 10 g/cm is always maintained as the minimum pressure. The minimum pressure necessary for stable contact between the charging blade 2 and the image carrier 1 is about 5 g/cm of linear pressure, so even if the contact pressure decreases over time due to permanent deformation of the charging blade 2 itself, the member 9 The weight W ensures a contact pressure greater than the above-mentioned minimum required pressure. Therefore, charged blade 2
The state of contact with the image carrier 1 is stabilized over the long term, that is, the charging process is stabilized over the long term.

The weight (self-weight) of the member 9 that can maintain the above-mentioned linear pressure is determined in accordance with the length of the charging blade 2. Since the member 9 uses its weight to smooth out the undulations at the tip of the blade into a uniform plane and brings it into close contact with the image carrier 1, it also serves to prevent charging failures that would occur if the tip of the blade had undulations.

Furthermore, by making this member 9 conductive and applying a voltage to the member, a bias can be directly applied to the tip of the charging blade 2, and the voltage as explained in FIG. In order to efficiently apply voltage to the charging blade 2 without any problem of voltage drop, it is necessary to set the applied voltage value by the power supply 6 to a high value in advance in consideration of the voltage drop as described in (2) above in order to avoid voltage drop. It is possible to eliminate problems such as increasing the size of the transformer and increasing costs. Also, as in the above (■), the conductive member 8 extends to the tip of the charging blade 2.
((C) in Figure 5) to make contact conductive, conductive paint (7)
) can eliminate the problem of increased process costs and material costs associated with coating treatments. Charged blade 2
When the main objective is to stabilize the contact of the charging blade 2 with the image carrier 1, the member 9 is an insulating weight member, and its weight stabilizes the contact of the charging blade 2 with the image carrier 1. The voltage applied to 2 is shown in (A) and (B) in FIG.
) and (C).

The contact conditions and constituent materials of the charging blade 2 with respect to the image carrier 1 are not limited to those mentioned above.
For example, the contact angle θ, which is the contact condition, is 30
It is preferable that the angle is less than 100°, but various angles can be set. As for the material, if the above resistance values can be satisfied in each layer 2a and 2b, the conductive layer 2a can be made of EPDM or metal oxide (
Zinc oxide, titanium oxide, etc.) may be dispersed in the resistive layer 2b, or fluororesin powder such as PTFE and conductive powder (e.g. carbon black, zinc oxide, titanium oxide, etc.) may be dispersed in the urethane elastomer to control the resistance value. A material made by dispersing metal oxide) may be used, or other materials may be used. Furthermore, in this example, a charging blade 2 with a two-layer configuration was used, but if a resistance value that satisfies both charging performance and leakage property can be managed, charging blades with any configuration, from a single-layer blade with only the conductive layer 2a to a multilayer blade, may be used. Can be used.

<Embodiment 2> (FIG. 2) This embodiment is a process cartridge 10 of an image forming apparatus incorporating a contact charging device according to the present invention.

The process cartridge 10 of this embodiment includes, in a cartridge housing 11, a rotating drum type image carrier 1, a charging blade 2 for uniformly charging the image carrier, a developing device 12, and a charging blade. It has four built-in process devices including a cleaning device 13 that cleans one surface. In the developing device 12, 12a is a developing sleeve that rotates in the direction of arrow b to convey toner, and 12b is an elastic blade that regulates the thickness of the toner coat on the developing sleeve 12a. In the cleaning device 13, 1
3a is a cleaning blade for scraping adhered contaminants such as untransferred toner from the surface of the image carrier 1, and 13b is a pick sheet for collecting the scraped untransferred toner. Reference numeral 11a designates an image exposure window hole formed in the upper surface of the cartridge housing 11.

In this embodiment, the charging blade 2 is a single layer consisting of only a conductive layer adjusted to a predetermined resistance value, and its base side is adhered to and held by the blade support member 3. 3 is firmly fixed and supported on the inner surface of the cartridge housing 11. The tip of the charging blade 2 is brought into contact with the image carrier 1 against elasticity, and
A thin conductive metal plate 14, such as an iron plate with good flatness, is adhered along the length of the blade to the back side of the contact portion of the blade 2 against the image carrier 1 with a conductive paint. By compressing each pressure spring 15 between at least two longitudinal ends of the thin conductive metal plate 14 and the inner surface of the cartridge housing 11, each longitudinal part of the tip of the charging blade 2 is compressed by the spring 15. The image carrier is pressed against the surface of the image carrier by an elastic force F (contraction reaction force).

The process cartridge 10 is removably attached to the main body of the image forming apparatus (not shown), and when installed in the main body of the apparatus, it is mechanically and electrically connected to the main body of the apparatus, and the process cartridge 10 is connected to the main body of the image forming apparatus (not shown). The image carrier 1 and the developing sleeve 12a are rotationally driven by the drive source or power source on the main body side.
It becomes possible to apply voltage to the charging blade 2 and the developing sleeve 12a.

When the process cartridge 10 is installed in the image forming apparatus, voltage is applied to the charging blade 2 through a power receiving electrode (not shown) on the side of the cartridge 10 that is electrically connected to the conductive pressure spring 15. , a power supply electrode (not shown) on the device main body side that is connected to the power source 6 on the device main body side
are coupled in correspondence, and the output voltage from the power source 6 is applied to both electrodes → conductive pressure spring 15 → conductive thin metal plate 1
4->It becomes possible to apply electricity to the charging blade 2 via the conductive paint.

The rotationally driven image carrier 1 is uniformly charged to a predetermined polarity and potential by a charging blade 2 to which a voltage (in this example, a superimposed voltage of DC and AC) is applied from a power source 6. The image carrier 1 is exposed to image information light L (laser scanning exposure, image forming exposure of a document image, etc.) from an image exposure means (not shown) on the apparatus main body side to the charged surface through the image exposure window 11a. An electrostatic latent image corresponding to image exposure is formed on the surface. The latent image is visualized as a toner image in the developing device 12, and the toner image is transferred on the device main body side to a transfer material P fed at a predetermined timing from a paper feeding means (not shown) on the device main body side. The images are sequentially transferred by means 16. The transfer material P on which the image has been transferred is separated from the image carrier 1 and outputted via an image fixing device (not shown). After the image has been transferred, the surface of the image carrier 1 is wiped off by a cleaning device 13 to remove residual toner, etc., to make it a clean surface, and the surface is repeatedly used for image formation.

Even if the contact force of the charging blade 2 against the image carrier 1 due to the elastic force F of the pressure spring 15 decreases over time due to permanent deformation of the charging blade 2, the contact pressure above the predetermined required minimum pressure is maintained. The elastic force of the spring 5 is set so that As a result, as in the case of the first embodiment, the contact state of the charging blade 2 with the image carrier 1 is stabilized over a long period of time;
In other words, the charging process is stabilized over the long term.

Furthermore, by applying a bias voltage directly to the tip of the charging blade 2 via the pressure spring 15 and the thin conductive metal plate 14, the pressure member 9 in the first embodiment is
Similar effects such as voltage drop prevention can be obtained by making conductive and applying a bias voltage to it.

<Embodiment 3> (FIG. 3) This embodiment is a modification of the process cartridge of Embodiment 2 described above. FIG. 3A is a state diagram of the main parts when the process cartridge is removed from the image forming apparatus main body, and FIG. 3B is a state diagram of the main parts when the process cartridge is installed in the apparatus main body.

In this embodiment, the charging blade 2 is a single-layer blade, and a conductive foam 17 is brought into contact with the back side of the part of the charging blade 2 that contacts the image carrier 1 along the length of the blade. When the cartridge 10 is removed from the main body of the apparatus, the foam 17 is under no load and its upper end is exposed to the outside of the cartridge housing 11 through the hole 18 made in the wall of the cartridge housing 11 as shown in (A). protrudes to. In this state, the charging blade 2
The tip of the blade is in contact with the image carrier 1 due to its own elasticity and is not pressed by the foam 17.

When the process cartridge 10 in this state is installed in the image forming apparatus main body, the upper end surface of the conductive foam 17 is connected to the electrode 20 provided on the lower surface of the mold member 19 on the apparatus main body side, as shown in FIG. The electrodes 20 come into contact with each other and are compressed between the electrode 20 and the tip of the charging blade 2 against elasticity. The compressive reaction force G causes the tip of the charging blade 2 to be pressed against the image carrier 1 .

The contact force of the charging blade 2 against the image carrier 1 due to the compression pressure G of the foam 17 is
The compression reaction force of the foam 17 is set so that even if the contact pressure due to the elasticity of the blade decreases over time due to permanent deformation of the blade, a contact pressure equal to or higher than a predetermined minimum pressure is ensured. As a result, as in the first and second embodiments, the contact state of the charging blade 2 with the image carrier 1 is stabilized over the long term, that is, the charging process is stabilized over the long term.

When the process cartridge 10 is removed from the main body of the apparatus, the foam 17 is separated from the electrode 20 and is unloaded, and the compression is released.

Furthermore, by making the foam 17 conductive and applying the voltage of the power source 6 (DC voltage in this embodiment) to the electrode 20 on the device main body side that compresses the foam, the tip of the charging blade 2 is Since the bias voltage is directly applied, Example 1
Similarly to the case where the pressing member 9 and the pressing spring 15 are made conductive and a bias voltage is applied thereto as in the example 2 and 2, effects such as voltage drop prevention can be obtained.

In this embodiment, a conductive foam 17 as a pressing member at the tip of the charging blade and an electrode 2 on the device main body side are used.
Since the foam body 17 is compressed and power is supplied to the foam body through direct contact with the foam body 17, there is no need to provide any other extra electrode members, so the cost can be reduced by reducing the number of parts.

The compressed foam 17 applies pressure and voltage to the tip of the charging blade 2 to the image carrier 1, thereby simultaneously achieving stable contact of the charging blade 2 and efficient voltage supply. Therefore, it is possible to always exhibit stable charging ability at low cost.

Furthermore, in this embodiment, the charging blade 2
The pressure and voltage supply section at the tip is not limited to the conductive foam 17, and may be a pressure spring made of a rubber elastic body or metal with low hardness as long as it is conductive.

The electrically conductive foam 17 uniformly contacts each longitudinal part of the back surface of the charging blade 2, so that the charging blade 2
The aim is to stabilize the contact uniformly along the length of the electrode 20, but it is sufficient that the electrode 20 on the main body side of the image forming apparatus has a contact point with the conductive foam 17 at least in a certain portion.

Further, the conductive foam 17 does not necessarily protrude outward from the housing 11 of the process cartridge 10, but when the process cartridge 10 is installed in the image forming apparatus main body, the electrode portion 20 on the main body side protrudes. The conductive foam 17 inside the process cartridge may be pressurized through the window hole 11a on the cartridge housing 11 side.

<Embodiment 4> (FIG. 4) In this embodiment, an elongated magnetic plate 21 was brought into contact with the back side of the contact portion of the charging blade 2 against the image carrier 1 along the length of the blade. The charging blade 2 has a two-layer structure including a conductive layer 2a and a resistive layer 2b.

The image carrier 1 consists of a base layer 1a and a photosensitive layer 1b or dielectric layer formed on the outer surface of the base layer 1a, and the base layer 1a is made of a magnetic material.

A magnetic attractive force H acts between the elongated magnet plate 21 on the back side of the tip side of the charging blade 2 and the magnetic base layer 1a of the image carrier 1, and the magnetic attractive force acts on the charging blade. 2 is pressed against the image carrier 1.

The contact force of the charging blade 2 against the image carrier 1 due to the magnetic force of the elongated magnet plate 21 remains above the predetermined minimum pressure even if the contact pressure due to the elasticity of the charging blade 2 decreases over time due to permanent deformation of the blade. The magnetic force of the magnet 21 is set so that the contact pressure is ensured. As a result, as in Examples 1 to 3, the contact state of the charging blade 2 with the image carrier 1 is stabilized over the long term, that is, the charging process is stabilized over the long term. The thin plate magnet 21 may be made of a magnetic material, and the base layer of the image carrier 1 may be magnetized.

Furthermore, by making the plate 21 conductive and applying voltage from the power source 6 to the plate 21, a bias can be applied directly to the tip of the charging member 2, which is different from the case of Examples 1 to 3 above. Similarly, effects such as voltage drop prevention can be obtained.

[0050]

As described above, according to the present invention, in a contact charging device using a blade-shaped conductive member as a charging member, the state of contact of the blade-shaped conductive member with the object to be charged can be stabilized over a long period of time. It is possible to maintain the long-term stability of the charging process by keeping the electrification temperature constant.

[Brief explanation of the drawing]

[Figure 1] Schematic configuration diagram of main parts of the first embodiment device

[Figure 2] Schematic configuration diagram of the second embodiment device (process cartridge)

FIG. 3 is a schematic configuration diagram of the main parts of the third embodiment apparatus (process cartridge), in which (A) shows the state when the process cartridge is removed from the image forming apparatus, and (B) shows the state when it is installed. It shows the state when

[Figure 4] Schematic configuration diagram of main parts of the fourth embodiment device

[Figure 5]
(A), (B), and (C) are schematic configuration diagrams of conventional devices, respectively.

[Explanation of symbols]

1 Image carrier as a charged object 2. Charged blade 2a Conductive layer 2b Resistance layer 6 Voltage application power supply 9 Pressing member (conductive weight)

Claims (6)

[Claims] 1. A contact charging device in which a blade-shaped conductive member is brought into contact with a charged object to perform charging, in which a portion of the conductive member is placed on the back side of a portion of the blade-shaped conductive member that contacts the charged object. A contact charging device characterized in that a member that presses against a charged object is provided. 2. The contact charging device according to claim 1, wherein the member for pressing the conductive member portion against the object to be charged is a weight, and the pressing is performed by the weight of the weight. 3. The contact charging device according to claim 1, wherein the member that presses the conductive member portion against the object to be charged is an elastic body, and the pressing is performed by the elastic force of the elastic body. 4. The member that presses the conductive member portion against the charged object is a member or a magnetic body that has a magnetic force that generates magnetic attraction with the charged object, and the pressing is performed by the magnetic attraction force. The contact charging device according to claim 1, characterized in that: 5. The member for pressing the conductive member portion against the object to be charged is conductive, and a voltage for the blade-shaped conductive member is applied to the conductive pressing member. 4. The contact charging device according to any one of 4. 6. A contact charging device using a blade-shaped conductive member is included in a process cartridge that is attached to and detached from the main body of the image forming apparatus, and the contact charging device uses a blade-shaped conductive member by pressing, applying voltage, or pressing the blade-shaped conductive member. An action member for supplying voltage is provided on the image forming apparatus main body, and when the process cartridge is installed in the image forming apparatus main body, the blade-shaped conductive member on the process cartridge side and the action member on the image forming apparatus main body are connected. 6. The contact charging device according to claim 1, wherein a window portion is provided in the housing of the process cartridge to enable mutual contact.