JPH0619296A - Developing device and image forming device - Google Patents

Abstract

PURPOSE:To eliminate an irregularity in thin film coating when blade line pressure is lowered. CONSTITUTION:The part T where a developer carrier 3 and an elastic blade 4 abut on each other is so positioned that the angle theta of the radius connecting the abutting part T and the center O of the developer carrier 3 to the radius obtained by drawing the horizontal line H passing the center O of the developer carrier 3 inside a developing container is within a range of 0 deg.<=theta<=40 deg. on the upstream side of the developer carrier 3 in its rotating direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The first invention is an electrophotographic copying machine,
The present invention relates to an image forming apparatus such as an electrostatic recording device and a magnetic recording device, and more particularly to a developing device that performs development using a dry non-magnetic one-component developer.

In particular, the second and fourth aspects of the invention relate to a developing device for forming a thin layer on a developer carrying member by means of a developer regulating member for developing.

A third aspect of the present invention relates to an image forming apparatus in which a dry non-magnetic one-component developer is used to form a thin layer on a developer carrying member by a developer regulating member for development.

The fifth invention also relates to a multi-color image forming apparatus such as a color laser printer or a color electrophotographic copying machine.

[0005]

[Prior art]

[First Conventional Example] Conventionally, various devices have been proposed and put into practical use as a dry one-component developing device using a non-magnetic one-component toner, but generally, the configuration is as shown in FIG. There is.

In other words, the elastic blade 100 and the supply stripping roller 101 are provided, and the supply stripping roller 101, which is a toner supply stripping means, is located upstream of the contact portion E between the elastic blade 100 and the developing sleeve 102 in the rotation direction A of the developing sleeve 102. Is arranged so as to contact the developing sleeve 102, and toner is supplied to the developing sleeve 102 and undeveloped toner on the developing sleeve 102 is stripped.

As for the position of the elastic blade 100, as shown in FIG. 5, the contact portion with the developing sleeve is generally above a horizontal line H passing through the center of the developing sleeve.

With such a structure, in order to form a thin layer of the toner 103 on the developing sleeve 102 with a uniform and proper coating amount, the contact pressure between the developing sleeve 102 and the elastic blade 100 (hereinafter, referred to as a blade line). Pressure))
It is necessary to set the drawing line pressure to about 60 g / cm.

However, if the blade linear pressure of this level is used for image development and the durability is increased, the toner is fused to the contact portion T between the elastic blade 100 and the developing sleeve 102 as the durability is advanced, and the developing sleeve is developed. The thin layer coating on 102 appears as coating streaks.

In order to solve such a problem in durability, it is effective to reduce the blade linear pressure, and by reducing the blade linear pressure to about 30 g / cm, there will be no problem in durability. You can [Second Conventional Example] As a dry magnetic one-component developing apparatus using dry magnetic one-component developing, various apparatuses have been proposed and put into practical use. As a method of regulating the developer, the amount of the developer is regulated mainly by arranging a rigid member with a minute gap from the developer carrying member in the rotational direction of the developer carrying member and upstream from the developing section. There is also a method and a method of arranging an elastic member regulating member so as to be in pressure contact with the developer carrying member on the upstream side of the developing unit in the rotational direction of the developer carrying member, but the latter method is used. A conventional example is shown in FIG.

In FIG. 13, 201 is a cylinder of a non-magnetic material such as aluminum, which is indicated by an arrow A by a motor (not shown).
Is rotated at a constant speed. That is, in the developing section P, the cylindrical body 201 is rotated in the same direction as the photosensitive drum (not shown) by a motor (not shown) or the like. Reference numeral 211 denotes a multi-pole magnet, which is arranged inside the developer carrying cylinder 201. 21
A developer container 2 contains a magnetic developer 209.

The cylindrical body 201 is in contact with the developer 209 in the developer container 212 in the lower region of the rotational movement, and is adapted to draw up the magnetic developer 209 along the upward movement path.

That is, the magnetic developer 209 is attracted to the cylindrical body 201 by the magnetic force of the multi-pole magnet 211, and is transferred in the rotating direction of the cylindrical body 201 by friction with the cylindrical body 201.

Reference numeral 202 denotes a developer layer regulating plate, which is a flexible elastic body such as rubber and is arranged upstream of the developing section P with respect to the rotational movement path of the cylindrical body 201. This elastic plate 202
Has one end side supported by the support member 221 and the other end surface pressed against the peripheral surface of the developer carrying cylinder 201.
A close contact portion is formed between both members.

The regulation plate 202 regulates the thick developer layer 291 sent from the container 212 into a thin layer. Further, the reason why the regulation plate 202 is in contact with the cylindrical body 201 on the belly surface is not only for forming a thin uniform developer layer, but also for making the pressure contact portion between the two longer in the rotation direction of the cylindrical body 201. This is because the contact distance between the cylindrical body 201 and the cylindrical body 201 is extended and the frictional electrification that occurs between the insulating developer 209 and the non-magnetic body cylinder 201 is made more reliable. [Third Conventional Example] As a dry non-magnetic one-component developing method using a dry non-magnetic one-component developer in a conventional image forming apparatus, various methods have been proposed and put into practical use. The configuration is shown in FIG.

That is, an elastic blade 312 as a developer regulating member and a developing sleeve 311 as a developer carrying member.
And a supply stripping roller 31 as a supply stripping member
3, the supply stripping roller 313 for supplying and separating the developer 320 is brought into contact with the developing sleeve 311 on the upstream side in the rotation direction of the developing sleeve 311 with respect to the contact portion between the elastic blade 312 and the developing sleeve 311. The developer 320 is supplied to the developing sleeve 311 and the undeveloped toner on the developing sleeve 311 is stripped off.

Further, the elastic blade 312 uniformly forms a thin layer of the developer 320 supplied onto the developing sleeve 311 by the supply stripping roller 313 at the contact portion with the developing sleeve 311, and at the same time, develops it. At that time, the developer is charged to a necessary charge amount. [Fourth Conventional Example] Conventionally, in a multi-color image forming apparatus,
A multi-color image is obtained by using multi-color developers, but each developer has a different charge amount due to differences in average particle size, external additives, and the like.

For example, magenta, cyan, yellow,
In a full-color copying machine using four color black developers, the charge amount of the developer is magenta when expressed by the charge amount per unit mass of toner (hereinafter referred to as tribo).
19 [μc / g], -16.5 [μc / g] for cyan, -0.5 [μc / g] for yellow, -15 [μ for black
c / g]. In this way, when the charge amount of the developer differs for each color, the development efficiency and transfer efficiency vary for each color, and as it is, the density differs for each color, and the color balance and gray balance are destroyed and faithful color reproduction is performed. Not done.

On the other hand, in the conventional full-color copying machine, the developing contrast potential and the transfer power are controlled for each color to achieve faithful color reproduction.

[0020]

[Problems to be Solved by the Invention]

[First Problem] In the case of the first invention, lowering the blade linear pressure has a drawback that coating unevenness is likely to occur in the thin layer coating on the developing sleeve 102.

In particular, the toner 103 is contained in the developing container 104.
When the developer is replenished or when the developing device is put in and out of the main body of the machine and is turned upside down or shaken, a toner pool (FIG. 2E) near the contact portion E between the developing sleeve 102 and the elastic blade 100 is formed. The amount of accumulated toner became larger than usual, and the increased amount of accumulated toner could not be sufficiently sheared by a low blade linear pressure, resulting in uneven coating of the thin layer. [Second Problem] In the second conventional example, when the fluidity of the developer 209 changes due to environmental changes, durability, etc., the amount of developer on the developer carrying member 201 changes accordingly.

If this variation exceeds the proper range of the amount of the developer on the developer carrying member 201 and the amount of the developer is excessive, unevenness of the thin developer layer or scattering of the developer is caused, resulting in insufficient amount of the developer. In the case of, there is a bad influence such as insufficient image density. [Third Problem] In the third conventional example, when the fluidity of the developer 320 changes due to an environmental change, the amount of the developer after passing the developer regulating elastic blade 312 on the developing sleeve 311 (hereinafter, The amount of coating will change).

For example, under high temperature and high humidity, the fluidity of the developer 320 increases, the coating amount becomes excessive, unevenness occurs in the thin developer layer on the developing sleeve 311, and the developer 320.
Occurs when the developing sleeve 311 rotates.

On the contrary, under low temperature and low humidity, the fluidity of the developer is lowered, and the coat amount becomes insufficient, resulting in a phenomenon that the image density becomes insufficient when the image is actually developed and an image is output.

This situation is shown in FIG. 1 in which the absolute humidity is represented by a mixing ratio on the horizontal axis and the coating amount at that time is represented on the vertical axis.
It becomes like 9. In this way, the amount of coat changes due to environmental changes, so it is not possible to maintain a stable image that does not change due to the environment. [Fourth Problem] Further, in the third conventional example, in order to uniformly form a thin layer of the developer 320 on the developing sleeve 311, the elastic blade 312 is pressed against the developing sleeve 311 with a certain contact pressure or more. Need to let.

When it is used for a long period of time under the pressure of the contact portion, the developer 320 is promoted to agglomerate or deteriorate, and the elastic blade 312 adheres the developer to the elastic blade 312. It has been difficult to stably maintain the initial image quality over a long period of time because it causes a phenomenon such as fusion. [Fifth Problem] In the fourth conventional example, in the method of controlling the development contrast potential and the transfer current for each color, the control is complicated and the stability of the image quality is deteriorated, or the cost of the apparatus is increased due to the complicated control. There were problems such as high price. [Object of the First Invention] The first invention is made to solve the above-mentioned first problem, and an object thereof is to eliminate uneven coating of a thin layer which occurs when the blade linear pressure is lowered. [Object of the second invention] The second invention is made in order to solve the second problem. Even when the fluidity of the developer is changed due to environmental change, durability, etc. An object of the present invention is to provide a developing device capable of stably obtaining a good image. [Aim of the Third Invention] The third invention is made in order to solve the above-mentioned third problem, and its object is to provide a developing device capable of outputting a stable image even if the environment changes. An object of the present invention is to provide an image forming apparatus provided with. [Aim of Fourth Invention] A fourth invention is made to solve the above-mentioned fourth problem. The purpose of the fourth invention is to set the contact pressure of the elastic blade to be much lower than the conventional pressure. A developing device is provided to maintain stable image quality for a long period of time. [Object of the Fifth Invention] The present invention has been made in view of the above problems, and an object of the present invention is to perform correction for a difference in charge amount of developers of respective colors by control of a simple configuration. To provide a multi-color image forming apparatus.

[0027]

[Means for Solving the Problems]

[First Invention] A first invention uses a dry non-magnetic one-component developer to develop an elastic blade for forming a thin layer of the developer on the developer carrier and a developer on the developer carrier. In a developing device equipped with a supply stripping roller for stripping the developer carrier from the developer carrier and further supplying the developer in the developing container onto the developer carrier, the position of the contact portion between the developer carrier and the elastic blade is The inclination angle θ of the radius line connecting the contact portion and the center of the developer carrier is the radius line drawn inside the developer container of the developer carrier which is a horizontal line passing through the center of the developer carrier. It is characterized in that it is arranged on the upstream side in the rotational direction of the body so that 0 ° ≦ θ ≦ 40 °. [Second invention] A second invention is to form a thin layer on a developer carrying member which carries a developer on the surface and conveys the developer by using a dry magnetic one-component developer and having a magnet inside the developer. In a developing device having a developer regulating member, a developer amount detecting means for detecting the amount of developer on the developer carrier in a non-contact manner in the vicinity of the upstream side in the rotational direction of the developing unit on the developer carrier. And a developer regulation amount adjusting means for variably adjusting the regulation amount of the developer by the developer regulation member so that the detected developer amount falls within an appropriate range.

The developer regulating member is a developer regulating blade which is in contact with the developer carrying member and has elasticity, and the developer regulating amount adjusting means is a contact pressure of the developer regulating blade to the developer carrying member. Is a blade contact pressure adjusting means for adjusting.

The developer regulating member is a developer regulating blade which is located upstream of the developing section in the direction of rotation of the developer carrying member and has a regulating portion tip which is separated from the surface of the developer carrying body. The developer regulation amount adjusting means is a means for adjusting the gap between the tip of the developer regulating blade and the surface of the developer carrying member.

The developer regulating amount adjusting means is a means for adjusting the magnetic pole position in the developer carrying member in the vicinity of the developer regulating member.

The developer carrying member is characterized in that it is a metal sleeve whose surface is mirror-finished. [Third Invention] A third invention is an image forming apparatus having a developing device having a developer regulating member for forming a thin layer of the developer on a developer carrier using a dry non-magnetic one-component developer, At least the surface of the developer regulating member that comes into contact with the developer carrying member is made of a conductive material, and when the developer carrying member is rotated, it is between the conductive surface of the developer regulating member and the developer carrying member. A bias is applied, and the output value of the temperature / humidity detection device provided in the main body is used to keep the amount of the developer after passing through the developer regulating member on the developer carrier always at an appropriate amount. The feature is that the applied bias is variably controlled. [Fourth Invention] A fourth invention relates to a developing device for forming a thin layer of a developer on a developer carrying member by means of a developer regulating member having elasticity using a dry non-magnetic one-component developer. The member is movable in the circumferential direction of the developer carrying member at a portion in contact with the developer carrying member, and the material is at least a surface having contact with the developer carrying member is a conductive material, and the developer is When the carrier is rotated, the developer regulating member moves and a bias is applied to the developer regulating member.

The developer regulating member is a rotating roller having elasticity and made of a conductive material.

The developer regulating member is characterized by comprising an endless belt stretched so as to come into pressure contact with the developer carrying member, and a driving means for the belt.

The bias is applied to the developer regulating member during the rotation of the developer carrying member so that the developer is applied from the developer carrying member side to the developer regulating member side in accordance with the charge polarity of the developer. It is characterized in that a bias that is attracted is applied. [Fifth Invention] The fifth invention corresponds to the image of each color in which a latent image of each color image of a plurality of color images is formed on an image carrier and the latent image is developed by a developing device of a plurality of colors. In an image forming apparatus that performs all latent images and obtains a multi-color image, a developer is attached to a developing device of each color so as to face a developer carrying member from a developer regulating portion to a developing portion of each developing device. A corona ion applying means for charging is provided, and the charge amount of the developer of each color before the developer of each color reaches the developing section is made uniform by varying the voltage applied to the corona ion applying means. It is characterized by controlling to.

Further, by variably controlling the voltage applied to the corona ion applying means, in addition to the charge amount of the developer which is different for each color before reaching the developing portion in the developing device of each color, the developer which varies depending on the environment The feature is that the charge amount is controlled so as to be uniform.

The developing method in the multi-color image forming apparatus is a moving support provided with a multi-color developing device of the developing apparatus each time a latent image of each color of the multi-color image is formed on the image carrier. Thus, the developing device for the color corresponding to the latent image is moved so as to be positioned at a position facing the latent image, and the latent image is developed for all the latent images corresponding to the image for each color. A developing system of moving a developing device is used, and a corona ion imparting means also serving as a developing device for each color is provided at a position facing the developer carrying member at a position where the developing devices for the plurality of colors perform development.

The corona ion applying means applies corona ions having the same polarity as the charging polarity of the developer.

[0038]

[Action]

[Operation of the First Invention] In the first invention, the radius of the contact portion between the developing sleeve and the elastic blade is smaller than the radius of the horizontal line passing through the center of the developing sleeve with respect to the inner radius of the developing container. By arranging such that the angle θ becomes 0 ° ≦ θ ≦ 40 ° on the upstream side of the developing sleeve in the rotation direction, the developing device was turned upside down or shaken when replenishing toner or when the developing device was taken in and out. Sometimes, the amount of toner accumulated in the toner accumulation area near the blade contact area is dropped downward by free fall due to gravity in order to reduce the amount of toner accumulation and prevent uneven coating of the thin layer. Is.

Further, since the amount of accumulated toner is always small due to free fall, it is possible to always coat a stable amount of thin layer coating on the developing sleeve. [Operation of Second Invention] The second invention is to detect the amount of the developer on the developer carrier in a non-contact manner in the vicinity of the upstream side in the rotation direction of the developing unit on the developer carrier. A detection unit is provided, and based on the detected amount, the developer regulation amount adjustment unit variably adjusts the developer regulation amount by the developer regulation member,
The amount of developer on the developer carrier is always controlled within an appropriate range. [Operation of Third Invention] The third invention of the developer regulating member is as follows.
At least the surface that contacts the developer carrying member is made of a conductive material, and a bias is applied between the conductive surface of the developer regulating member and the developer carrying member when the developer carrying member is rotated, and this application is performed. The bias is variably controlled by the output value of a temperature / humidity sensor provided in the main body of the image forming apparatus. With this, even if the environment fluctuates, it is controlled to stabilize the coating amount on the developer carrier,
A stable image can always be output. [Operation of Fourth Invention] In the fourth invention, at least the surface of the developer regulating member that is in contact with the developer carrying member is made of a conductive material, and a bias is provided between the developer regulating member and the developer carrying member. By applying the voltage, the contact pressure of the developer regulating member with respect to the developer carrying member can be set extremely low as compared with the conventional case.

Further, by moving the developer regulating member in the circumferential direction of the developer carrying member, the effect of the above bias can be maintained, and stable image quality can be continuously output for a long period of time. It became so. [Operation of the Fifth Aspect of the Invention] The fifth aspect of the present invention provides a corona ion for charging the developer to the developing device of each color so as to face the developer carrying member from the developer regulating portion to the developing portion of each developing device. A means is provided to make uniform the weight of the developer of each color before reaching the developing section for each color and for each environment by controlling the corona ion applying means.

[0041]

【Example】

[First Embodiment of the Invention] A first embodiment of the first invention will be described below with reference to FIG. 1 of the accompanying drawings.

FIG. 1 shows a dry type non-magnetic one-component developing device embodying the first aspect of the present invention, which is an example when the angle θ in FIG. 2 is 0 °. Hereinafter, the developing device will be described in detail.

The developing device comprises a developer supply container (hereinafter simply referred to as a container) 2, a developing sleeve 3 as a developer carrying member, an elastic blade 4 as a developer regulating means, and a supply as a developer supplying / separating means. It is provided with a stripping roller 5 and a toner feeding member 6 which is a developer feeding means. The developing sleeve 3 is disposed in the opening. The developing sleeve 3 is made of a non-magnetic material such as aluminum or stainless steel. The developing sleeve 3
Is rotatably supported and is rotationally driven in the direction of arrow B by a drive source (not shown).

A supply stripping roller 5 is disposed below the developing sleeve 3 so as to rotate in sliding contact at a sliding contact portion S. The supply stripping roller 5 rotates in the same direction as the developing sleeve 3 to supply the toner to the developing sleeve 3 and elastically contact the developing sleeve 3 to separate the toner on the developing sleeve 3.

The free end of the elastic blade 4 is in contact with the developing sleeve 3 at the downstream side of the sliding contact portion S between the supply stripping roller 5 and the developing sleeve 3 in the rotating direction of the developing sleeve 3. The contact portion T regulates passage of the toner on the developing sleeve 3.

The elastic blade 4 is preferably made of a triboelectric material suitable for charging the toner to a desired polarity. For example, polyurethane, styrene, butadiene, or the like may be used to negatively charge a toner containing polyester as a constituent component. By using the above materials, the triboelectrification efficiency of the toner can be further increased.

A toner feeding member 6 is disposed in the container 2 behind the supply stripping roller 5 so as to rotate in the direction of arrow D, and toner 7 which is a one-component non-magnetic toner is supplied to the supply stripping roller. Supply to 5.

An indoor wall 8 is provided between the supply stripping roller 5 and the toner feeding member 6, and the toner stripped by the supply stripping roller 5 is conveyed by the toner feeding member 6. A flow path 9 is formed to guide the toner to a position where it merges with the toner.

The merged toner is conveyed again to the sliding contact portion S with the developing sleeve 3 by the supply stripping roller 5.

Below the developing sleeve 3, a seal member 11 for closing a gap with the container 2 is arranged. The seal member 11 is a flexible sheet such as Mylar (trade name manufactured by DuPont, the same applies to Mylar below).

Further, the developing sleeve 3 is provided with a power source 12 for applying a bias.

The developing method in this embodiment is, for example, the method described in Japanese Patent Publication No. 58-32375, that is, an alternating current in which a direct current is superposed is applied between the photosensitive drum / and the developing sleeve 3 so that the developing sleeve 3 is exposed. A so-called non-contact developing method is used in which thin layer toner is imagewise transferred to the electrostatic latent image on the photosensitive drum /.

Next, the operation of the developing device as described above will be described.

In FIG. 1, the toner feeding member 6 is indicated by an arrow D.
Is rotated in the direction to convey the toner 7 to the supply stripping roller 5, the supply stripping roller 5 rotates in the direction of arrow C, and the toner 7 transported on the supply stripping roller 5 is slidably contacted with the sliding contact portion S.
Supply to. Next, at the sliding contact portion S between the developing sleeve 3 and the supply stripping roller 5, the toner 7 on the supply stripping roller 5 is frictionally charged by being in sliding contact with the developing sleeve 3 and is supplied to the developing sleeve 3. To be done.

Further, when the toner 7 passes through the contact portion T between the elastic blade 4 and the developing sleeve 3, the toner 7 is brought into sliding contact with the surface of the developing sleeve 3 by the elastic blade 4 and is further subjected to frictional charging. In this way, the toner 7 can receive sufficient triboelectrification. The toner subjected to the sufficient triboelectric charge passes through the contact portion T to form a thin toner layer on the developing sleeve 3, and is carried on the developing sleeve 3 to the developing portion P facing the photosensitive drum /. In the developing section P, a part of the toner is consumed by the developing operation, and the other toner is collected from the lower part of the developing sleeve 3 as the developing sleeve 3 rotates. A seal member 11 is provided in the collecting portion to allow the toner not consumed in the development to pass into the container 2 and prevent the toner in the container 2 from leaking from the lower portion of the container 2. The collected toner on the developing sleeve 3 is supplied to the stripping roller 5 and the developing sleeve 3.
It is scraped off by elastic contact at the sliding contact portion S with. The scraped off toner is conveyed through the flow path 9 formed by the guide wall 8, merges with the toner conveyed by the toner feeding member 6, and again as described above, the sliding contact portion S.
Be transported to.

Next, an example of an experiment conducted under the following conditions will be described.

In this experimental example, the developing sleeve has a diameter of 3 mm.
The surface of a 2 mm aluminum sleeve was polished and mirror-finished to a surface roughness R _Z = 1.2 μm.
As the elastic blade, urethane having a thickness of 2 mm and a width of 20 mm and having a hardness of 73 ° was used.

As the non-magnetic toner used at this time, a powder having an average particle size of 8 μm, in which polyester was used as a binder resin, and silica was externally added as an external additive to impart fluidity to the toner.

A thin Mylar seal having a thickness of 50 μm was used as a seal member for preventing the toner from scattering from the container. The contact pressure of the elastic blade to the developing sleeve was set to about 30 g / cm in the experimental example.

23 mm in diameter for the supply stripping roller
The roller-shaped sponge roller was used. The developing sleeve was rotated at 280 / sec and the supply stripping roller was rotated at a relative speed of 875 mm / sec with respect to the developing sleeve.

In this experimental example, the thickness of the toner layer on the developing sleeve is made smaller than the length of the facing gap between the developing sleeve and the photosensitive drum, and as described above, the toner is moved from the developing sleeve to the photosensitive drum. Then, the method of performing development (so-called non-contact development or shampling development) was used.

In this experimental example, the dark potential in the reversal development on the photosensitive drum was -750V, and the bright potential was -120V.
Keeping the gap between the photosensitive drum and the developing sleeve to about 250 μm, the developing sleeve has a peak-to-peak voltage of 2000 V, 2
Development was performed by applying a developing bias in which a square wave AC voltage of 000 Hz and a DC voltage of -400 V were superimposed.

Next, the effect of this embodiment will be described. In the present invention, as described above, the contact portion T between the elastic blade 4 and the developing sleeve 3 is located below the horizontal line H passing through the center O of the developing sleeve 3, so that the toner pool near the blade contact portion T is retained. The amount of toner accumulated on the developing sleeve 3 is reduced by gravity drop, and even when the blade linear pressure is lowered, the developing sleeve 3
It is intended to facilitate the toner thin layer coating above. Table 1 shows this situation with experimental data.

Table 1 shows that when the blade linear pressure is set to about 30 g / cm and the angle θ in FIG. 2 is changed to the conventional position shown in FIG. 5 and −20 °, 0 °, 20 °, 40 °. The amount of toner M / S (mg / cm ² ) coated on the developing sleeve 3 and the state of coating when the toner is intentionally accumulated in a large amount in the toner reservoir by reversing the developing device are shown. is there.

When the position of the contact portion T is θ> 40 °, the toner reservoir and the supply stripping roller 5 are too close to each other due to the structure of the developing device, and the amount of toner accumulated in the toner reservoir is rather changed. Since it is larger than in the conventional position of the contact portion, θ ≦ 40 °.

As can be seen from this data, by setting the angle θ in FIG. 2 to 0 ° ≦ θ ≦ 40 °, a thin layer coating with a low blade linear pressure, which has been a coating unevenness in the past, can be obtained. It was possible to obtain a uniform coat.

In the first embodiment, the developing device is arranged laterally with respect to the photosensitive drum 1, but as shown in FIG. 3, the developing device may be arranged below the photosensitive drum 1.

As a result, the dry non-magnetic one-component development by the "elastic blade 4 + peeling supply roller 5" system is realized by implementing the present invention even for the developing device disposed below the photosensitive drum 1. It was done.

Further, the above-described development of the lower arrangement is indispensable in the slide type development in which a plurality of developing devices horizontally move under the photosensitive drum 1, and a multicolor color copying machine using the slide type development is used. Is an effective developing means.

In the first and second embodiments, the elastic blade 4
Is contacted in the counter direction with respect to the rotation direction of the developing sleeve, but it can also be contacted in the forward direction as shown in FIG. In this case, due to the durability at the conventional contact position, the toner is clogged in the toner accumulation portion, and the toner coating amount M / S on the developing sleeve 3 is increased. The toner can be prevented from being clogged, and the problem can be solved. [Embodiment of the Second Invention] Next, an embodiment of the second invention will be described.

FIG. 6 shows an embodiment of the present invention in which an elastic body regulating member (hereinafter referred to as an elastic blade) is used as the developer regulating member.

The developing device is provided below the developing sleeve 201 as a developer carrying member, an elastic blade 202 as a developer regulating member, end seal members 204 provided at both ends of the developing container 212, and the developing sleeve 201. And a lower seal member 205 provided.

A stirring rod 213 for stirring the toner is provided in the developer container 212 containing the developer (hereinafter referred to as toner) 209, and the developing sleeve 20 is provided.
A multi-pole magnet 211 is arranged inside the unit 1.

Further, the developer amount detecting means 206 for detecting the amount of toner on the developing sleeve 201 and the developing sleeve 20 of the elastic blade 202 as the developer regulating amount adjusting means.
Blade contact pressure adjusting means 207 for adjusting the contact pressure to the blade 1.
And a CPU which processes the output from the developer amount detecting means 206 and sends a signal to the drive portion of the blade contact pressure adjusting means 207.
And 208 are provided.

The developing sleeve 201 is made of a non-magnetic material such as aluminum or stainless steel, is rotatably supported, and is rotationally driven in the direction of arrow A by a drive source (not shown).

Further, with respect to the rotating direction of the developing sleeve 201, the elastic blade 202 is provided on the upstream side of the developing section P.
The free end of the developing sleeve 201 is disposed in contact with the developing sleeve 201 at the contact portion T, and at the contact portion T, the developing sleeve 2
The passage of the toner 209 on 01 is regulated.

For the elastic blade 202, it is preferable to use a friction charging series material suitable for charging the toner 209 to a desired polarity. For example, depending on the material,
To positively charge a toner containing polystyrene, magnetite, carbon, etc. as a composition component, to negatively charge ethylene propylene rubber, fluorine rubber, natural rubber, polychlorobutadiene, N, B, R, etc. If silicone rubber, polyurethane, styrene-butadiene rubber, or the like is used as the elastic blade 202, the triboelectric charging efficiency of the toner becomes higher.

Further, below the developing sleeve 201,
A seal member 205 that closes the gap with the developing container 212 is provided. This seal member 205 is a Mylar (trade name manufactured by DuPont). The same applies to Mylar hereinafter.
Etc. is a flexible sheet.

In the vicinity of the upstream side of the developing sleeve 201 in the rotational direction of the developing portion P, a developer amount detecting means 206 is provided at a distance of about 1 mm from the developing sleeve 201 without contacting the developing sleeve 201. The elastic blade 202 detects the developer amount (toner amount) of the thin toner layer before development.

As shown in FIG. 7, the developer amount detecting means 206 is composed of an infrared light emitting diode 261 which is a light emitting element and a photodiode 262 which is a light receiving element. The amount of light reflected by the toner 209 on the sleeve 201 is detected by the photodiode 262.

Next, the operation of the developing device as described above will be described.

The developing sleeve 201 is in contact with the toner 209 in the container 212 in the lower region of the rotational movement, is attracted to the developing sleeve 201 by the magnetic force of the multi-pole magnet 211, and is moved along the upward movement path of the developing sleeve 201. It is designed to pump 209.

When the toner 209 pumped up passes through the contact portion T between the elastic blade 202 and the developing sleeve 201, the surface of the developing sleeve 201 and the elastic blade 202.
It is rubbed by and is subjected to triboelectrification.

In this way, the toner 209 can receive sufficient triboelectrification. The toner 209 that has received the sufficient frictional charge passes through the contact portion T and is formed as a thin toner layer on the developing sleeve 201, and the developing portion P facing the photosensitive drum (not shown) on the developing sleeve 201. Be carried to. In the developing section P, a part of the toner is consumed by the developing operation and the other toner is consumed in the developing sleeve 20.
It is collected from the lower portion of the developing sleeve 201 with the rotation of 1.

A seal member 205 is provided in this collecting portion, and a developing container 212 for the toner not consumed in the development is provided.
The toner 2 in the container 212 while allowing passage into the inside.
09 is prevented from leaking from the lower part of the container 212.

By the way, the developer amount detecting means 206 on the developing sleeve 201, which is a feature of the second aspect of the present invention, is such that the developing sleeve 20 is not rotated when the rotation of the developing sleeve 201 is stopped.
The amount of toner above 1 is detected.

In the present embodiment, the relationship between the toner amount per unit area on the developing sleeve 201 (mg / cm ² ) and the detection output (V) of the developer amount detecting means 206 is magnetite as a toner. As shown by the solid line in FIG. 8, the detection output monotonously decreases as the toner amount increases. Based on the detection output (V) of the developer amount detecting means 206, the CPU
208 is a drive unit of the blade contact pressure adjusting means 207,
A drive signal is sent so as to obtain a blade contact pressure in which the toner amount on the developing sleeve 201 is within an appropriate range.

The proper range of the toner amount on the developing sleeve 201 is 0.8 to 1.0 (mg / cm ² ) in terms of the toner amount per unit area on the developing sleeve 201 in this embodiment. As for the relationship between the contact pressure of the blade 202 and the amount of toner on the developing sleeve 201, the amount of toner on the developing sleeve 201 decreases as the contact pressure increases, regardless of the state of the toner. When it is determined by 206 that the amount of toner on the developing sleeve 201 is large, the blade contact pressure is increased by the blade contact pressure adjusting means 207, and when it is determined that the toner amount is small, the blade contact pressure is adjusted by the blade contact pressure adjusting means 207. To do.

Each time the adjustment is performed, the developer amount is detected, and the toner amount on the developing sleeve 201 is kept within an appropriate range by the flow shown in FIG. The contact pressure of the blade 202 is adjusted by the blade contact pressure adjusting means 207 moving the supporting portion 210 of the blade 202 in the direction of arrow C, as shown in FIG.

By performing the control as described above, the toner amount on the developing sleeve 201 can be made appropriate regardless of the environment of the toner 209 and the durability of the toner 209. A stable and good image can be obtained.

In the first embodiment, as an example of the method of regulating the developer, the elastic blade 202 is pressed against the developing sleeve 201, but a rigid member is used as the developing sleeve 2.
When it is arranged with a small gap from 01, it becomes as shown in FIG.

In this case, the rigid regulating member 203
As shown in FIG. 10, the regulating blade 203 is moved in the up-down direction (direction of arrow D in the figure) with respect to the support portion 231 of the regulating blade 203.
By changing the gap g between the developing sleeve 201 and the developing sleeve 201, the developer 2
The regulation amount of 09 is adjusted.

Further, as a means for adjusting the regulated amount of the developer,
As shown in FIG. 11, it is also possible to change the circumferential position of the multipolar magnet 211 inside the developing sleeve 201.

That is, the N ₁ pole, which is the magnetic pole closest to the abutting portion T of the elastic blade 202 on the developing sleeve 201, is moved to the standard position as indicated by arrow E in the figure. When the N ₁ pole is brought close to the contact portion T, the magnetic field at the contact portion T is strengthened,
The magnetic restraining force on the toner 209 becomes stronger, and the leakage amount of the toner 209 after passing through the contact portion becomes smaller.

On the contrary, when the N ₁ pole is moved away from the contact portion T, the magnetic restraining force on the toner 209 is weakened and the amount of toner passing through the contact portion T increases.

The position of the N ₁ pole is adjusted by adjusting the rotation amount of the motor 214 directly connected to the shaft of the multi-pole magnet 211 and arranged outside the developing container 212. The amount is the CPU2 of FIG.
It is controlled by 08.

As described above, by changing the N ₁ pole closest to the contact portion T of the elastic blade 202 to the developing sleeve 201 in the circumferential direction with respect to the contact portion T, the regulation amount of the developer can be adjusted. .

Although FIG. 11 shows an example in which the elastic blade 202 is used as the developer regulating means, the developer 20 is prevented by the rigid regulating member 203 as shown in FIG.
Even when 9 is regulated, the developer regulation amount can be adjusted by similarly changing the circumferential position of the N ₁ pole with respect to the regulation portion.

In the case of this embodiment, it is not necessary to consider the variation in the adjustment of the contact pressure and the gap g in the thrust direction of the developing sleeve 201 as in the case of the first and second embodiments, so that it is comparatively possible. The amount of developer can be adjusted accurately with a simple structure.

As the developing sleeve 201, a metal sleeve 15 whose surface is mirror-finished as shown in FIG. 12 can be used. In this case, the amount of reflected light of the developing sleeve 201 itself at the developer amount detection unit 206 increases as compared with the case of the first to third embodiments, so that the toner amount per unit area on the developing sleeve 201 and the developer amount. The relationship with the detection output of the detection means 206 is as shown by the dotted line in FIG. 8, and the detection accuracy increases as the inclination of the graph in FIG. 8 increases. [Third Embodiment of the Invention] Next, a first embodiment of the third invention will be described with reference to FIGS. 1 and 2 of the accompanying drawings.

FIG. 14 is a schematic structural view showing an image forming apparatus provided with an embodiment of the developing device of the present invention.

In FIG. 14, reference numeral 301 denotes a photosensitive drum which is a latent image carrier. The photosensitive drum 301 is rotatably arranged, and a corona discharger 302, which is a charger for uniformly charging the surface of the photosensitive drum 301, is arranged above the photosensitive drum 301.

The surface charged by the corona discharger 302 is irradiated with the exposure beam 303 on the downstream side of the corona discharger 302 in the rotation direction of the photosensitive drum 301, and the surface is exposed to form a latent image.

The latent image formed on the surface is developed by a developing device 307 arranged facing the photosensitive drum 301 at a position downstream of the exposure position in the rotation direction of the photosensitive drum 301, and the latent image is formed on the photosensitive drum. The image is transferred onto the transfer material 321 by the transfer charger 309 disposed below 301. The image transferred onto the transfer material 321 is fixed by the fixing device 322 and discharged.

On the other hand, the developing device 30 is provided in the image forming apparatus.
In order to detect the temperature and humidity of the environment in which the main body 7 is placed, a temperature and humidity detecting device 308 is installed above the developing device 307.

Next, referring to FIG. 15, the developing device 30 will be described.
7 will be described in more detail. The developing device 307 is
A developing sleeve 311 serving as a developer carrying member, a conductive blade 312 serving as a developer (hereinafter referred to as toner) regulating member, a toner supplying / peeling roller 313 serving as a toner supplying / separating means on the developing sleeve 311, and a developing device. End seal members 314 provided at both ends of the container and the developing sleeve 3
11, a lower seal member 315 provided below the device 11, and a bias power supply 316 that supplies a voltage to the developing sleeve 311.
And a bias power supply 317 for supplying a voltage to the conductive blade 312, and a CPU 318 for controlling the voltage output from the bias power supply 317 by the output of the temperature / humidity detection device 307.

The developing sleeve 311 is made of a non-magnetic material such as aluminum or stainless steel, is rotatably supported, and is rotationally driven in the direction of arrow B by a driving source (not shown).

Below the developing sleeve 311, a supply stripping roller 313 is disposed so as to rotate by sliding at a sliding portion S. The supply stripping roller 313 rotates in the same direction as the developing sleeve 311, supplies the toner to the developing sleeve 311, and makes elastic contact with the developing sleeve 311, thereby developing the developing sleeve 31.
The toner on 1 is peeled off.

Further, below the developing sleeve 311, a seal member 315 is arranged to close a gap with the developing container. The seal member 315 is a flexible sheet such as Mylar (trade name of DuPont, the same applies to Mylar below).

The developing sleeve 31 is more than the sliding portion S between the supply stripping roller 313 and the developing sleeve 311.
1, a conductive elastic blade 312 is provided on the downstream side in the rotation direction of 1.
The free end of the contact portion is arranged in contact with the developing sleeve 311 at the contact portion T. In the portion T, the developing sleeve 3
The passage of the toner on No. 11 is regulated by applying a bias between the developing sleeve 311 and the conductive elastic blade 312 so that the toner is attracted to the conductive elastic blade 312 side at the contact portion T.

The conductive elastic blade 312 may have any structure as long as it has elasticity and the surface contacting the developing sleeve 311 is conductive. In this embodiment, urethane rubber is used as the base material. Was used, and the one coated with nylon in which conductive fine powder was dispersed was used.

Further, the CPU 318 is the temperature / humidity detection device 3
The output voltage of the bias power supply 317 is calculated based on the temperature / humidity detection data of the environment where the main body of the developing device 307 is detected in 08 so that the coat amount of the toner on the developing sleeve 311 is always maintained appropriately. , A signal is sent to the bias power supply 317.

Next, the operation of the developing device as described above will be described.

In FIG. 15, the supply stripping roller 31
3 rotates in the direction of arrow C, and the toner 3 in the developing container 323
20 is supplied to the rubbing portion S. Next, the developing sleeve 31
In the rubbing portion S between 1 and the supply stripping roller 313,
The toner on the supply stripping roller 313 is the developing sleeve 3
By being rubbed with 11, the toner is subjected to triboelectrification and is supplied to the developing sleeve 311.

Further, when the toner 320 passes through the contact portion T between the conductive elastic blade 312 and the developing sleeve 311, the toner 320 is rubbed by the developing sleeve 311 and the elastic blade 312, and is further subjected to triboelectric charging. In this way, the toner can receive sufficient triboelectrification. The toner, which has been subjected to the sufficient triboelectrification, develops due to the potential difference of the bias applied between the developing sleeve 311 and the elastic blade 312 when passing through the contact portion T.
The coating amount of the thin toner layer on 11 changes.

The state of this change is shown in FIG.

The bias applied to the developing sleeve 311 at this time is -300 (V), and the horizontal axis in the figure is (the bias voltage value applied to the elastic blade 312)-(the bias applied to the developing sleeve 311). Voltage value), and the toner 320 is a negatively chargeable toner.

As described above, since the coating amount changes depending on the potential difference of the bias applied to the developing sleeve 311 and the elastic blade 312, the potential difference of the bias is changed according to the environment, as shown in FIG. It is possible to prevent the coat amount from varying depending on the environment.

Then, the toner formed on the developing sleeve 311 as a thin toner layer having an appropriate coating amount is carried to the developing section on the developing sleeve 311 facing the photosensitive drum 301.

In the developing section, a part of the toner is consumed by the developing operation, and the other toner is collected from the lower part of the developing sleeve 311 as the developing sleeve 311 rotates.
A seal member 315 is provided in this collecting portion to allow the toner not consumed in the development to pass into the developing container 323 and prevent the toner in the container from leaking from the lower part of the container.

The collected toner on the developing sleeve 311 is scraped off by elastic contact at the sliding portion S between the supply stripping roller 313 and the developing sleeve 311.

Next, the control of the coating amount of toner on the developing sleeve, which is a feature of the third invention, will be described.

First, the temperature / humidity detecting device 308 provided above the developing device 307 in the image forming apparatus detects the temperature / humidity of the environment in which the developing device 307 is placed. This temperature / humidity detection data is sent to the CPU 318, and the CPU 318 converts this data into a mixing ratio. The value of this mixing ratio determines the potential difference of the bias applied to the developing sleeve 311 and the conductive blade 312 so that the toner coating amount on the developing sleeve 311 is set to an appropriate amount.

This relationship is shown in FIG.
In this embodiment, an appropriate coating amount is 0.5% of colloidal silica added externally to improve fluidity to a toner having an average particle size of 8 μm in which about 5 parts of a pigment is mixed with 100 parts of a polyester resin as a toner. Since toner is used, the toner amount per unit area on the developing sleeve 311 is 0.5 to 0.5.
It was 6 (mg / cm ² ).

The CPU 318 stores the graph as shown in FIG. 17 as a table and stores it in the elastic blade 312.
The drive signal is sent so that the bias to be applied to the bias power supply 317 is output from the bias power supply 317. in this way,
Based on the temperature / humidity detection data, the CPU 318 controls the bias applied to the elastic blade 312 according to the environment so that the toner coating amount on the developing sleeve 311 is always an appropriate amount.

By performing the control as described above, the amount of toner coated on the developing sleeve 311 is appropriately maintained even when the environment changes, and a stable and good image can be output regardless of the environment. It became so.

In the first embodiment, the conductive elastic blade 312 is used.
Although only a DC voltage was used as a bias applied to the AC bias, a bias in which a DC voltage is superimposed on an AC voltage can also be used.

In this case, as the DC voltage, the first embodiment is used.
Similarly, the bias voltage value based on FIG. 17 is applied, and as the alternating voltage, in this embodiment, the frequency f = 1 KHz,
A peak-to-peak value V _pp = 1 kv was used.

In this way, by using the bias applied to the conductive elastic blades 12 as the bias applied with the DC voltage superimposed on the AC voltage, the same effect as that of the first embodiment is obtained, and the effect of the AC voltage is obtained. Elastic blade 312 by
The unevenness of the contact pressure of the developing sleeve 311 with respect to the developing sleeve 311 in the axial direction can be reduced, and a thin toner layer is formed more uniformly in the axial direction than in the embodiment, and a more uniform image is output over the entire image area. be able to. [Embodiment of Fourth Invention] Next, a first embodiment of the present invention will be described.

FIG. 20 shows an example in which a rotating roller is used as a developer (hereinafter referred to as toner) regulating member.

This developing device includes a developing sleeve 401 as a developer carrying member, a regulating roller 402 as a regulating member for the toner 407, and a supply stripping roller 403 as a means for supplying and stripping toner on the developing sleeve 401. I have it. End seal members 4 are provided at both ends of the developing container 408.
A lower seal member 04 is provided below the developing sleeve 401, and a scraper blade 406 for scraping off the toner adhering to the regulation roller 2 is provided.

The developing sleeve 401 is made of a non-magnetic material such as aluminum or stainless steel, is rotatably supported, and is rotationally driven in the direction of arrow B by a drive source (not shown).

Below the developing sleeve 401, a supply stripping roller 403, which is a supply stripping member, is rubbed at the sliding portion S.
It is arranged so that it can be rotated by sliding. The supply stripping roller 403 rotates in the same direction as the developing sleeve 401, supplies the toner 407 to the developing sleeve 401, and peels the toner on the developing sleeve 401 by elastically contacting the developing sleeve 401.

The lower seal member 405 below the developing sleeve 401, which closes the gap between the developing container 401 and the developing container 408, is a flexible sheet such as Mylar (trade name of DuPont, the same applies to Mylar below).

On the other hand, on the downstream side in the rotation direction of the developing sleeve 401 from the sliding portion S between the supply stripping roller 403 and the developing sleeve 401, the regulating roller 402 contacts the developing sleeve 401 at the contact portion T. Are arranged in close contact,
As shown in FIG. 20, the toner passing through the developing sleeve 401 at the portion T is biased between the developing sleeve 401 and the regulating roller 402 such that the toner 407 is attracted to the regulating roller 402 at the contact portion T. Is regulated by applying.

In the present embodiment, since the toner having the negative charging property is used, the developing sleeve 401 is provided with -300.
(V), -200 (V) voltage is applied to the regulation roller 402.

Any material can be used for the regulating roller 402 as long as it is a conductive material having elasticity. For example, in the present embodiment, conductive fine powder such as carbon black in silicon rubber is used. Was used.

By the way, when the developing sleeve 401 rotates while the regulating roller 402 remains stationary, the toner gradually adheres to the regulating roller 402 and accumulates in volume due to the bias as described above, and by extension, the developing sleeve 401 and the regulating roller 402. The potential difference between and is canceled by the electric charge of the toner, and the effect of the applied bias disappears.

In the fourth aspect of the present invention, in consideration of such a phenomenon, the regulating roller 402 is rotated in the direction of arrow A by a driving source (not shown) at a predetermined speed so that the portion where the toner is not always adhered is rotated. Abutting. Furthermore, the regulation roller 40
Although the toner adhering to 2 may be free fall only, it is desirable to completely scrape it off with a scraper blade 406 as shown in FIG.

Next, the operation of the developing device as described above will be described.

In FIG. 20, the supply stripping roller 40
3 rotates in the direction of arrow C, and toner 4 in the developing container 408
07 is supplied to the rubbing portion S. Next, developing sleeve 401
At the sliding portion S between the supply stripping roller 403 and the supply stripping roller 403, the developer on the supply stripping roller 403 is
By being rubbed with 01, it is triboelectrically charged and is supplied to the developing sleeve 401.

Further, the toner 407 is the regulating roller 402.
When passing through the contact portion T between the developing sleeve 401 and the developing sleeve 401,
The surface of the developing sleeve 401 is rubbed by the regulating roller 402, and is further subjected to triboelectric charging. In this way, the toner 402 can receive sufficient triboelectrification. When the toner subjected to the sufficient triboelectrification passes through the contact portion T, the bias between the developing sleeve 401 and the regulating roller 402 and the rotation of the regulating roller 402 cause an appropriate layer thickness on the developing sleeve 401. Is formed as a thin toner layer.

Then, the developing sleeve 401 is carried to a developing unit which faces a photosensitive drum (not shown). Further, the toner attached to the regulation roller 402 at the contact portion T is
Scraper blade 40 provided in developing container 408
6 collects again in the developing container 408.

In the developing section, a part of the toner is consumed by the developing operation, and the other toner is collected from the lower portion of the developing sleeve 401 as the developing sleeve 401 rotates. A lower seal member 405 is provided in the collecting portion to allow passage of toner not consumed in the development into the developing container 408 and prevent the toner in the container 408 from leaking from the lower portion of the container. Collected developing sleeve 4
The toner on 01 is scraped off by elastic contact at a sliding portion S between the supply stripping roller 403 and the developing sleeve 401.

With the above-described structure, the contact pressure of the regulation roller 402 against the developing sleeve 401 can be set to be extremely lower than that of the conventional one, and a dry non-magnetic one which can maintain stable image quality for a long period of time. A component developing device can now be provided.

Although the regulating roller 402 is used as the developer regulating member in the first embodiment, the endless belt 411 may be pressed against the developing sleeve 401 as shown in FIG.

Here, the endless belt 411 is made of silicone rubber or urethane rubber in which conductive fine powder is dispersed, and is wound between the two driving rollers 410a and 410b. Is pressed against the developing sleeve 401 by the tension.

The drive rollers 410a and 410b are
At least one of the rollers is made of metal, and a bias is applied to the roller. In this embodiment, the drive roller 410a is made of metal.

In the first embodiment, the developer regulating roller 4
Most of the toner scraped off from No. 02 by the scrape blade 406 falls on the developing sleeve 401 and is immediately frictionally charged again, so that the toner may be excessively charged, but in the present embodiment, most of it is charged. Since the toner is dropped in the toner reservoir 409, it is possible to prevent the toner from being excessively charged.

In Embodiments 1 and 2, the bias applied to the developing sleeve 401 is only the DC voltage. However, the fourth invention can be applied to the developing method in which the DC voltage is superimposed on the AC voltage. .

In this case, it is desirable that the alternating voltage applied to the developing sleeve 401 has a frequency f of about 500 Hz or higher.

In this embodiment, the frequency f = 1 kHz and the peak-to-peak value V _pp = 1 KV are used, and the DC voltage is -300 in the developing sleeve 401 as in the first embodiment.
A voltage of -200 [V] was applied to [V], the regulation roller 402 or the endless belt 411.

As described above, since the AC voltage is applied at the contact portion between the developing sleeve 401 and the developer regulating members 402 and 411, the same effects as those described in the first and second embodiments can be obtained. Besides, due to the effect of the AC voltage, it is possible to reduce the axial unevenness of the contact pressure of the developer regulating members 402 and 411 with respect to the developing sleeve 401.
As compared with the above, a thin toner layer is formed more uniformly in the axial direction. [Embodiment of Fifth Invention] Next, an embodiment of the fifth invention will be described.

FIG. 22 is a schematic sectional view of a digital full-color copying machine using a non-magnetic one-component developing system as a developing system.

That is, the photoconductor drum 50 having the electrophotographic photoconductor provided on the surface thereof in the substantially central portion of the apparatus main body 550.
1 and the photoconductor drum 501 is rotated in the clockwise arrow X direction. Around the photosensitive drum 501, a primary charger 502 is obliquely above the photosensitive drum 501, a transfer device 505 is on the left side,
The cleaning device 506 is on the upper side, and the developing device 56 is on the lower right side.
0s are arranged respectively. In addition, the image forming apparatus main body 550
An optical system 510 is arranged in the upper part of.

Although the reading unit 510 may use any one, in the present embodiment, the reading unit 510 moves in the same direction at a speed half that of the first scanning mirror 511 and the first scanning mirror 511. Third scanning mirrors 512 and 51
3, an imaging lens 514 and a color CCD image sensor 515. The document illumination light source 516 is
Configured to move with the first scanning mirror 511,
The RGB color separation filter is incorporated in the CCD image sensor 515.

According to the reading unit 510, the reflected light image of the document 512 exposed and scanned by the first, second and third scanning mirrors 511, 512, 513 passes through the lens 514 and is color separated by the RGB color separation filter. An image is formed on the color CCD image sensor 515. The formed image is taken out as a signal of the color CCD image sensor 515 and is converted into a digital signal for each color of R, G, B by A / D conversion.

The R, G, B digital signals are then logarithmic.
The signal proportional to the light amount of R, G, B is corrected to Y (yellow).
-), M (magenta), C (cyan) density signals
And then B_kY, M, C signals in the (black) generator
Value should be gray originally B _kTo generate. like this
Y, M, C, B generated in_kThe signal is the writing unit 54.
Sent to 0.

In the writing section 540, each color Y, M, C,
A latent image of each color is formed on the photosensitive drum 501 via the semiconductor laser, the polygon mirror 517, and the lens reflection mirror 519 for each B _k .

On the left side of the image forming apparatus main body 550, a sheet feeding device 530 is arranged below the fixing device 520, and the transfer drum 505, the fixing device 520, and the sheet feeding device 53.
Between 0 and 0, transfer paper transport systems 525 and 53, respectively.
5 are provided.

The developing device 560 is a four-color developing device, that is, a magenta developing device 564M, a cyan developing device 564C, a yellow developing device 564Y, and a black developing device 564.
As shown in FIG. 22, the photoconductor drum 501 is arranged around the right side to the lower side of the photoconductor drum 501. 4 color developer 5
Each of 64M, 564C, 564Y, and 564B develops and visualizes a latent image by a developing device of a color corresponding to the latent image of each color separated on the photosensitive drum 501. repeat.

The developing devices for the respective colors of the developing device 560 include corona ion charging devices 564M, 564C, 564Y and 564 as corona ion applying means for charging the developer.
B is disposed at a position facing the developer bearing member of each developing device.

The transfer device 505 is typically equipped with a transfer drum 505b having a gripper 505a for holding the transfer paper P as a transfer material around the transfer drum 505b. The transfer device 505 uses the gripper 50 to fix the leading end of the transfer paper fed from the transfer paper cassette 531 or 532 of the paper supply device 530 through the transfer paper transport system.
It is gripped by 5a, and is rotated and transferred so as to transfer the toner images of the respective colors on the photosensitive drum 501. Transfer drum 505a
A transfer charger 505c is arranged inside the transfer area.

With the above arrangement, the primary charging device 502, the writing unit 540, the developing device 560, the transfer device 505, and the cleaning device 506 for each color separated by the color separation filter with respect to the photosensitive drum 501. The steps of charging, exposing, developing, transferring and cleaning are performed.

The transfer paper on which the toner images of the respective colors have been sequentially transferred as described above is released from the gripper 505a and separated from the transfer drum 505b by the separation claw 508.
Next, the transfer is performed by the fixing device 52 by the transfer paper transport system 525.
0, where the toner image on the transfer paper is fixed,
After that, the transfer paper is discharged to the toner 523.

Next, the developing device 560 will be described in detail. FIG. 23 shows a magenta developing unit 564 of the four-color developing units.
It is a schematic sectional drawing about M.

The developing device 564M includes a developing sleeve 581 as a developer carrying member, an elastic blade 582 as a developer layer thickness regulating means, and a toner stripping supply roller which is a stripping supply means of the toner T to the developing sleeve 581. 583, developing sleeve 581, elastic blade 58
2. A developing device main body 590 having a toner stripping supply roller 583 and the like and having toner inside
A side seal member 584 for closing a gap between the developing device main body 590 and both ends of the developing sleeve 581; a lower seal member 585 for closing a gap between the lower part of the developing sleeve 581 in the longitudinal direction and the developing device main body 590; Corona charger 5 for charging toner, which is provided so as to face the sleeve 581.
It is composed of 65M.

The developing sleeve 581 is made of a non-magnetic material such as aluminum or stainless steel and has a cylindrical shape. The developing sleeve 581 is rotatably supported by the developing device main body 590 so as to be partially exposed from the developing device main body 590, and is not shown. It is rotated in the direction of the arrow in FIG. The toner stripping supply roller 583 is provided below the developing sleeve 581 so that the developing roller main body 59 is brought into contact with the developing sleeve 581 at the sliding portion S.
0, and is rotated in the same direction as the developing sleeve 581 by a drive source (not shown) to peel off the residual toner T on the developing sleeve 581 after completion of the developing operation from the developing sleeve 581. It has a function of adhering the toner T in the developing device main body 590 to the outer peripheral surface of the developing sleeve 581 again.

The toner stripping supply roller 583 is
A cored bar made of a non-magnetic material such as aluminum or stainless steel is provided with an elastic layer made of an elastic member such as moltoprene, open-cell polyurethane, or single-cell polyurethane around the core. The outer surface of the elastic layer is made of a material. Has a small unevenness due to the characteristics of the developing sleeve 5 through the unevenness.
The toner is effectively peeled off and supplied to 81.

The elastic blade 582 is the developing sleeve 58.
1 above, the toner stripping supply roller 583 and the developing sleeve 581 with respect to the rotating direction of the developing sleeve 581.
Of the toner T supplied to the developing sleeve 581 by the toner stripping supply roller 583 by developing the layer thickness of the toner T provided on the developing sleeve 581 at the contact portion U by contacting the developing sleeve 581. While controlling to the thin layer required for work,
It has a function of frictionally charging the toner. It is preferable to use a triboelectrification series material suitable for charging the toner T to a desired polarity for the elastic blade 582. For example, in order to negatively charge the toner T containing polyester, nylon or polyurethane is used. If a material such as styrene, butadiene or the like is used, the charging effect of the toner can be further enhanced.

The lower seal member 585 is composed of a flexible sheet member such as Mylar (trade name of DuPont).

The operation of the developing device 560 will be described below. By the rotation of the toner stripping supply roller 583, the toner T in the developing device 590 is adhered and supplied onto the outer peripheral surface of the developing sleeve 581 by the rubbing portion S. And
The toner U on the developing sleeve 581 is triboelectrically charged by the elastic blade 582 by the contact portion T, and its thickness is regulated to a constant thin layer.

Thus, the thin layer toner T on the developing sleeve 581 that has been triboelectrically charged is conveyed to a position facing the corona charger 65M for toner charging as the developing sleeve 581 rotates. At that time, a negative corona is applied to the charger 565M by a high-voltage power source to develop the developing sleeve 58.
The negatively charged toner on 1 is charged.

Further, with the rotation of the developing sleeve 581, the toner T is moved to the facing portion of the photosensitive drum 501 and is used for the developing work. In this case, part of the toner T is supplied to the photosensitive drum 501 side and consumed, but the other part of the toner T passes through the lower seal member 585 as the developing sleeve 581 rotates and is moved again into the developing device 590 to slide. At the rubbing portion S, the toner is stripped off from the developing sleeve 581 by the toner stripping supply roller 583.

Further, the corona charger 56 for charging the toner is used.
The 5M control will be described with reference to FIG. Figure 24
Is an AC voltage of 10 kV _pp 4 on the wire of the corona charger.
FIG. 9 is a diagram showing a change in toner tribo value when a voltage in which a DC voltage is superimposed on 00 Hz is applied and the superimposed DC voltage is changed from 0 to −1.0 (Kv).

In the figure, the solid line shows the toner charge of −26 (μc / g) before the toner is charged by the corona charger.
, The dotted line shows the change at −11 (μc / g). For example, in order to align the tribo of toners having different tribos, a DC voltage to be superimposed on the toner of tribo-26 (μc / g) is set to −0. 35 (kv), for toner of Tribo-11 (μc / g), it is -1.
Set it to 0 (kv).

As described above, the change in the toner tribo value when the superimposed DC voltage as shown in FIG. 3 is changed for all the four color toners is obtained in advance, and all the toner siribo values are made uniform. To determine the DC voltage for each color toner and apply the DC voltage to the corona charger 565 during development so that the tribo of the toner of each color before being sent to the developing unit is evenly aligned. You can

As described above, the toner tribo can be uniformly aligned for each color by the simple control of the toner tribo, so that the complexity of controlling the contrast potential and the transfer current for each color as conventionally performed is not required. I was able to lose it.

In the first embodiment, the corona ion charging device, which is a corona ion applying means for toner charging, is only controlled so that the charge amounts of different developers are made uniform for each color. Thus, it is possible to control the amount of charge of the developer, which varies depending on the environment, to be uniform. Hereinafter, the control of the charge amount of the developer, which varies depending on the environment, will be described.

The charge amount of the developer changes depending on the hygroscopic property of the binder resin which is a component of the toner, and changes over the environment from low temperature and low humidity to high temperature and high humidity. The hygroscopic property of the binder resin has a correlation with the absolute water content in the air, but the charge amount of the developer that changes depending on the environment is shown in FIG.
For the DC voltage applied to the corona charger such as 4,
The relationship of changes in toner tribo is obtained in advance.

From such a relationship, over the entire environment,
A DC voltage that makes the toner tribo uniform is obtained for each environment as in the first embodiment. When an image is actually formed based on this potential value, the environment is detected by a temperature / humidity sensor 591 provided in the main body immediately before image formation as shown in FIG. A DC voltage value according to the detected environment is applied to the corona ion charger 565.

With the control as described above, only the corona ion charger is controlled without performing the complicated control of controlling the contrast potential and the transfer current for each color and for each environment, which has been conventionally performed. By making the tribo of the developer uniform, an image having good color balance and gray balance and good environmental stability can be obtained.

In Examples 1 and 2, as the developing method, a developing device fixed developing system in which four color developing devices are fixedly arranged around the photosensitive drum 501 is used, but as shown in FIG. Each time a latent image of the image is formed, a developing device of a color corresponding to the latent image is moved by a moving support provided with a developing device of a plurality of colors of the developing device to develop the latent image.
The present invention can be applied to a case where a developing device moving developing device is used for all latent images corresponding to the respective color images.

In this case, only one corona ion applying means for charging the developer is provided at the position where the developing devices for the plurality of colors develop, facing the developer carrying member. Since the constituent requirements can be satisfied, it is possible to achieve a simplified cost reduction of the structure of the device. The developing device 5100 will be described below.

The developing device 5100 comprises a rotating body 5102 as a moving support, a developing device 5104 for four colors, that is, a developing device 5104 for yellow, a developing device 5104M for magenta, a developing device 5104C for cyan and a developing device 514 for black.
Each time a latent image of each color separated is formed on the photoconductor drum 501, the rotator 5102 rotates so that the developing device 5104 of the color corresponding to the position of the latent image is provided. The process moves, and the latent image is developed and visualized repeatedly.

Further, a corona charger 5105 as a corona ion applying means for charging the developer is provided in the main body at a position where the developing device of each color of the developing device 5100 develops and at a position facing the developer carrier of each developing device. It is arranged inside.

In the third embodiment, an example in which the developing device is moved by rotation is shown. However, as shown in FIG. 27, even when the developing device moving system of horizontal movement is used, one corona ion applying means is used. All you have to do is to install it. The developing device has the following configuration.

The developing device 570 is the photosensitive drum 50.
On the movable support 572 that can move horizontally toward the lower part of 1, the developing device 574 for four colors, that is, the developing device 574Y for yellow,
The developing device includes a magenta developing unit 574M, a cyan developing unit 574C, and a black developing unit 574B. The moving support 572 moves horizontally every time a latent image of each color separated on the photosensitive drum 501 is formed. By doing so, the developing device 574 for the color corresponding to the position of the latent image is moved, and the development and visualization of the latent image are repeated.

Also in such a multi-color image forming apparatus, as shown in FIG. 22, the corona charger 75 for charging the toner is at the position where the developing devices for the respective colors perform the development and the position facing the developer carrying member. It is possible to eliminate the complication of the device and the high cost by providing it in the.

In Examples 1 to 4, the corona charger is used as the corona ion applying means, but a plate charger may be used as shown in FIG. In this case, it is possible to avoid development in which the wire is contaminated due to toner scattering, which is a problem in the corona charger, and uneven charging occurs, and uniform charging is always realized. The plate charger will be described below.

The plate charger 5111 is a dielectric 5120.
And at least two buried electrodes 5121 and 5122 and a bare electrode 5123.

Buried electrodes 5121 and 5122 are arranged at positions where a discharge is generated near a part of the surface of dielectric 5120 at a predetermined discharge start voltage when an AC voltage is applied between them. That is, when an AC voltage of a predetermined discharge start voltage or higher is applied between the embedded electrode 5120 and the embedded electrode 5122 by the AC power supply 5124, the bottom surface of the illustrated plate charger 111 (the electrode to which the AC voltage is applied) is thereby applied. Discharge occurs in a single region indicated by reference numeral 5125, centering on a portion facing in the vicinity of the electrodes on a surface (almost parallel to a line connecting 5121 and 5122), and
Negative ions are produced alternately.

The generated ions are the direct current bias power supply 512.
9 is pulled to the developing sleeve 581 by the electric field formed by the voltage applied between the bare electrode 5123 and the developing sleeve 581,
The toner is attached to the upper toner and charged.

Each voltage value has an AC voltage of 0.5 to 6 kV _pp , preferably 1 to 4 kV _pp , a bias voltage of 0.2 to 4 kV,
It is preferably 0.5 to 2 kV.

Further, as the corona ion applying means,
As shown in FIG. 29, the needle electrode 5130 is attached to the developing sleeve 5
Alternatively, the developing sleeve 581 may be disposed at a suitable interval in the longitudinal direction of the developing sleeve 581 (direction perpendicular to the paper surface).

[0196]

【The invention's effect】

[Effects of the first invention] The first invention is that by applying the present invention to dry non-magnetic one-component development, it is possible to eliminate coating unevenness which has been apt to occur when the blade linear pressure is lowered in the prior art. Since the contacting part between the elastic blade and the elastic blade is below the horizontal line passing through the center of the developing sleeve, the amount of toner accumulated in the toner reservoir can always be kept small and the amount of toner coating on the developing sleeve can be stabilized. You can [Effect of the Second Invention] According to the second invention, an optical system for detecting the amount of the developer on the developer carrier in a non-contact manner on the developer carrier in the vicinity of the upstream side in the rotation direction from the developing section. Based on the detected amount of the developer, the developer regulating amount adjusting means adjusts the regulated amount of the developer by the developer regulating member so that the amount of the developer on the developer carrier is always an appropriate amount. Therefore, even if the fluidity of the developer changes due to changes in the environment or durability, problems such as uneven developer thin layer, scattering of developer, insufficient image density, etc. can be avoided for a long time.
A stable and good image can be obtained in any environment. [Effect of the third invention] According to the third invention, the coat amount of the developer on the developer carrying member is always kept appropriate even if the environment is changed, and it is always stable in any environment. Good images can now be output. [Effect of Fourth Invention] According to the fourth invention, at least the surface of the development regulating member that comes into contact with the developer carrying member is made of a conductive material, and a bias is provided between the developer regulating member and the developer carrying member. By applying the voltage, the contact pressure of the developer regulating member with respect to the developer carrying member can be set extremely low as compared with the conventional case.

Further, by moving the developer regulating member in the circumferential direction of the developer carrying member, the effect of the above bias can be maintained and stable image quality can be continuously output for a long period of time. Became. [Effect of the Fifth Invention] According to the fifth invention, the charge amount of the developer of each color is different for each color, but the toner charging device is not controlled for each color but the development contrast potential and the transfer current are controlled. Since the simple control is performed by controlling only the voltage applied to the corona ion applying means, it is possible to provide a stable multi-color image forming apparatus with no control complexity.

[0198]

[Table 1] (Blade line pressure 30g / cm)

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a dry non-magnetic single-component developing device embodying the first aspect of the invention.

FIG. 2 is a diagram showing a blade contact position of the developing device of the present invention.

FIG. 3 is a sectional view of a second embodiment of the first invention.

FIG. 4 is a sectional view showing a third embodiment of the first invention.

FIG. 5 is a sectional view of a conventional dry non-magnetic single-component developing device.

FIG. 6 is a sectional view of a dry magnetic one-component developing device according to the first embodiment of the present invention.

FIG. 7 is a configuration diagram of a developer amount detection unit.

FIG. 8 is a diagram showing the relationship between the amount of developer per unit area and the detection output of the developer detection means.

FIG. 9 is a flowchart of blade contact pressure adjustment.

FIG. 10 is a sectional view of a second embodiment of the second invention.

FIG. 11 is a side view of the third embodiment of the second invention.

FIG. 12 is a sectional view of a fourth embodiment of the second invention.

FIG. 13 is a sectional view of a conventional dry non-magnetic one-component developing device.

FIG. 14 is a schematic configuration diagram showing an image forming apparatus provided with an embodiment of the present invention.

FIG. 15 is a sectional view of the dry type non-magnetic single-component developing device according to the first embodiment of the present invention.

FIG. 16 is a diagram showing a relationship between a potential difference of a bias applied to a developer carrying member and a conductive regulating member and a coating amount of the developer on the developer carrying member.

FIG. 17 is a diagram showing a relationship between a mixing ratio in an environment for always keeping an appropriate amount of a coat on a developer carrying member and a potential difference of a bias applied between the developer carrying member and the conductive regulating member. .

FIG. 18 is a sectional view of a conventional dry non-magnetic single-component developing device.

FIG. 19 is a diagram showing a relationship between a mixing ratio and a coating amount on a developer carrying member in a conventional configuration.

FIG. 20 is a cross-sectional view of a dry type non-magnetic single-component developing device embodying the present invention.

FIG. 21 is a sectional view of the second embodiment of the fourth invention.

FIG. 22 is a configuration diagram of an image forming apparatus according to an embodiment of the fifth invention.

23 is a schematic cross-sectional view of one developing device in FIG.

FIG. 24 is a graph showing the relationship between the charge amount of the developer and the DC bias.

FIG. 25 is a configuration diagram of a second embodiment of the fifth invention.

FIG. 26 is a configuration diagram of a third embodiment of the fifth invention.

FIG. 27 is a configuration diagram of a fourth embodiment of the fifth invention.

FIG. 28 is a configuration diagram showing another example of the charging system.

FIG. 29 is a configuration diagram showing still another charging method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 3 Developing sleeve 4 Elastic blade 5 Supply stripping roller 6 Toner feeding member 201 Developing sleeve 202 Elastic blade 203 Regulation blade 206 Developer amount detecting means 207 Blade contact pressure adjusting means 209 Developer (toner) 211 Multipolar magnet 214 Motor for adjusting magnetic pole position 215 Mirror surface metal sleeve 307 Developing device 308 Temperature / humidity detecting device 311 Developing sleeve 312 Conductive elastic blade 317 Bias power source 318 CPU 401 Developing sleeve 402 Control roller 406 Scraper blade 410a, 410b Driving roller 411 Endless belt 501 Photosensitive Body drum 560 Developing device 564M, C, Y, B Magenta, cyan, yellow, black developing device 565M, C, Y, B Corona ion charger

Claims (15)

[Claims] 1. An elastic blade for forming a thin layer of a developer on a developer carrying member using a dry non-magnetic one-component developer and the developer on the developer carrying member are stripped from the developer carrying member. In a developing device further including a supply stripping roller for supplying the developer in the developing container onto the developer carrier, the position of the contact portion between the developer carrier and the elastic blade is The inclination angle θ of the radial line connecting the contact portion and the center of the developer carrier is the upstream side in the rotation direction of the developer carrier with respect to the radial line drawn inside the developer container of the developer carrier of the horizontal line passing through the center. And a developing device arranged such that 0 ° ≦ θ ≦ 40 °. 2. A developer regulating member for forming a thin layer on a developer carrying member for carrying and carrying the developer on the surface by using a dry magnetic one-component developer and having a magnet inside the developer. In the developing device having, in the vicinity of the upstream side in the rotation direction from the developing unit on the developer carrying member, a developer amount detecting means for non-contactly detecting the developer amount on the developer carrying member is provided, and further, A developing device, comprising: a developer regulation amount adjusting means for variably adjusting a regulation amount of the developer regulated by the developer regulating member so that the detected developer amount falls within an appropriate range. 3. The developer regulating member is a developer regulating blade which is in contact with the developer carrying member and has elasticity, and the developer regulating amount adjusting means is provided with respect to the developer carrying body of the developer regulating blade. The developing device according to claim 2, which is a blade contact pressure adjusting unit that adjusts a contact pressure. 4. The developer regulating member is a developer regulating blade which is located upstream of the developing section in the rotation direction of the developer carrying body and has a regulating section tip which is separated from the surface of the developer carrying body. The developing device according to claim 2, wherein the developer regulation amount adjusting means is means for adjusting a gap between the tip of the developer regulation blade and the surface of the developer carrying member. 5. The developing device according to claim 2, wherein the developer regulation amount adjusting means is means for adjusting a magnetic pole position in the developer carrying member in the vicinity of the developer regulating member. 6. The developing device according to claim 2, wherein the developer carrier is a metal sleeve whose surface is mirror-finished. 7. An image forming apparatus having a developing device having a developer regulating member for forming a thin layer of the developer on a developer carrier by using a dry non-magnetic one-component developer, wherein the developer regulating member is provided. Is made of a conductive material at least on the surface in contact with the developer carrier, and a bias is applied between the conductive surface of the developer regulating member and the developer carrier when the developer carrier rotates. At the same time, the applied bias is variably controlled by the output value of the temperature / humidity detection device provided in the main body so that the amount of the developer after passing the developer regulating member on the developer carrier is always kept at an appropriate amount. An image forming apparatus comprising: 8. A developing device in which a dry non-magnetic one-component developer is used to form a thin layer of a developer on a developer carrying member by a developer regulating member having elasticity, wherein the developer regulating member is It is movable in the circumferential direction of the developer carrying member at the portion contacting with the developer carrying member, and the material is at least a surface in contact with the developer carrying member is a conductive material, and when the developer carrying member is rotated, A developing device, wherein the developer regulating member moves and a bias is applied to the developer regulating member. 9. The developing device according to claim 8, wherein the developer regulating member is a rotating roller having elasticity and made of a conductive material. 10. The developing device according to claim 8, wherein the developer regulating member is composed of an endless belt stretched so as to come into pressure contact with the developer carrying member, and a driving means thereof. 11. The developing device according to claim 8,
The bias is applied to the developer regulating member during rotation of the developer carrying member, and the developer is attracted from the developer carrying member side to the developer regulating member side according to the charging polarity of the developer. A developing device characterized in that such a bias is applied. 12. A latent image of each color image of a plurality of color images is formed on an image carrier, and the latent image is developed by a developing device of a plurality of colors for all latent images corresponding to the images of the respective colors. In an image forming apparatus for performing a multi-color image, the developing device for each color is provided with a corona ion for charging the developer, facing the developer carrying member from the developer regulating portion to the developing portion of each developing device. It is possible to dispose an applying unit and control the charge amount of the developer of each color before reaching the developing unit to be uniform by changing the voltage applied to the corona ion applying unit. A characteristic image forming apparatus. 13. The image forming apparatus according to claim 12, wherein the voltage applied to the corona ion imparting means is variably controlled to change the charge amount of the developer for each color before reaching the developing unit in the developing unit for each color. In addition to the above, the image forming apparatus is characterized in that the charge amount of the developer, which varies depending on the environment, is controlled to be uniform. 14. The developing method in the multi-color image forming apparatus is such that a multi-color developing device of the developing apparatus is provided every time a latent image of each color image of the multi-color image is formed on the image carrier. By the support, the developing device of the color corresponding to the latent image is moved so as to be located at a position facing the latent image, and the latent image is developed by all the latent images corresponding to the images of the respective colors. 14. A corona ion imparting means also serving as a developing device for each color is provided at a position facing the developer carrying member at a position where the developing device for a plurality of colors develops by using the developing device moving developing method. The multi-color image forming apparatus described in 1. 15. The corona ion applying means applies corona ions having the same polarity as the charging polarity of the developer.
2. The multi-color image forming apparatus described in 2, 13, or 14.