JPH0786721B2 - Image forming device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine and a printer to which electrophotography is applied.

2. Description of the Related Art Conventionally, a developing method using a dry developer is roughly divided into a method using a two-component developer and a method using a one-component developer.

The method using a two-component developer uses a mixed developer of toner and carrier, and therefore requires a toner concentration control device that keeps the mixing ratio of toner and carrier constant, and has drawbacks such as periodic replacement due to carrier deterioration. have. Therefore, recently, a developing method using only a one-component developer which does not use a carrier has been proposed in order to eliminate the above-mentioned defects.

This developing method is disclosed, for example, in JP-A-54-43038, US Pat. No. 4,083,326, and the like.
The structure is shown in FIG. 10 and FIG.

In FIG. 9 (JP-A-54-43038), 1 is a developing roller, 2 is toner, 3 is a hopper, 4 is a blade, and 5 is a photoconductor. The developing roller 1 is made of a metallic material having an uneven surface, and the toner 2 is supplied from the hopper 3. Next, when the developing roller 1 rotates in the direction of the arrow, the toner 2 is charged to a predetermined polarity and coated on the surface of the developing roller 1 by the blade 4 that is in sliding contact with the surface of the developing roller 1. Next, the charged toner 2 is developed by flying when it faces the electrostatic latent image on the photoconductor 5.

In FIG. 10 (US Pat. No. 4,083,326), 13 is a developing roller, 14 is toner, 15 is a hopper, 16 is a blade, and 17 is a blade.
Is a sheet-shaped photosensitive member, 18 and 19 are conductive fur brushes that are in sliding contact with the developing roller 13, 20 is a first power source for applying a voltage to the hopper 15 and the conductive fur brush 18, and 21 is a conductive fur brush. A second power source for applying a voltage to 18 and the developing roller 7. Further, the voltage applied by the second power source 21 is made higher than the voltage applied by the first power source 20 and lower than the voltage of the electrostatic latent image on the photoconductor 17. The toner 14 frictionally charged by the fur brush 18 is supplied from the hopper 15 to the developing roller 13 via the conductive fur brush 18 by the potential difference between the first and second power supplies 20 and 21, and then smoothed by the blade 16. After that, it adheres to the electrostatic latent image on the photoconductor 17 and develops it.

Next, the toner 14 on the developing roller 13 after development is scraped off by the conductive fur brush 19 to remove the development history on the developing roller.

Problems to be Solved by the Invention However, in such a system, there is a problem in that the developer (toner) has a uniform charging property and a uniform layer thickness is formed on the developing roller, and high-quality image reproduction is possible. Was making it difficult.

That is, in the case shown in FIG. 9, the toner on the surface layer on the developing roller comes into contact with the blade and is triboelectrically charged,
The toner below the surface layer does not come into contact with the blade and is not frictionally charged. If the toner is blown off and developed in this state, there is a problem that the uncharged toner is scattered to contaminate the apparatus, or adheres to the non-image area to cause fog.

As shown in FIG. 10, the charged toner can be uniformly coated on the developing roller, and the problem of FIG. 9 is solved. However, two fur brushes supply toner and scrape off the toner. Becomes complicated. Also,
Since a voltage is applied between the hopper and the fur brush, and between the fur brush and the developing roller, there is a potential gradient.
The more strongly charged the toner is, the easier it is to transfer it.
For example, when toner that has not been used for development is scraped off and transferred again, the uniformity of toner charging is hindered, for example, only part of the toner is overcharged, which causes fog and toner lumps. However, there is a problem that the image density varies.

9 and 10 both use a blade to form a thin toner layer, the accuracy of the end face of the blade has a great influence on the formation of a uniform thin toner layer, and the end face of the blade is uneven. If so, there is a problem in that unevenness in the layer thickness of the developer and streaks occur, and a good image cannot be obtained.

The present invention solves the conventional problems and provides a high-quality image forming apparatus.

Means for Solving the Problems And technical means of the present invention for solving the above problems include a developer in a developing device for visualizing an electrostatic latent image formed on a latent image carrier. A carrier, a cylindrical elastic body that is in contact with or in the vicinity of the carrier, a layer thickness regulating unit that regulates the layer thickness of the developer on the downstream side of the cylindrical elastic body, and a casing that houses or holds the developing device constituent members. Set up. Further, the layer thickness regulating means is composed of a blade, and the straightness of the blade end portion is set to 0.15 mm or less.

Action The action of this technical means is as follows. That is, the rotation of the cylindrical elastic body causes relative movement between the developer and the developing device constituent member to uniformly tribocharge the developer, and the charged developer on the cylindrical elastic body is carried by the developer. It is transferred onto the body and coated thicker than a predetermined developer layer thickness. Next, excess developer is scraped off by the layer thickness regulating means to form a predetermined developer layer thickness on the developer carrying member. At this time, the layer thickness regulating means is composed of a blade, and the straightness of the end portion of the blade is precisely finished to 0.15 mm or less, so that unevenness in the layer thickness of the developer or uneven coating on the developer carrier such as generation of streaks is caused. Does not occur. Then, the developer is caused to fly by the electric field between the latent image holding member and the developer carrying member for development.

Therefore, the developer on the developer carrier in the developing section is uniformly charged and uniformly coated. Therefore, it is possible to perform high-quality development without toner scattering, fogging, and development density unevenness.

Further, the developer is stirred and triboelectrically charged by the cylindrical elastic body, so that the developer rises quickly and the change in development density due to humidity and the like can be reduced.

Examples Examples of the present invention will be described below.

1 to 5 show a first embodiment of the present invention, which is an example used in an electrophotographic copying machine.

In FIG. 1, reference numeral 22 denotes a latent image holding member, which is electrostatic recording paper, a photosensitive drum, or the like. In this embodiment, the latent image carrier 22 is a photosensitive drum, and a photoconductor 24 such as zinc oxide, selenium, or an organic photoconductive material is carried on the surface of an aluminum base 23. (Henceforth, the latent image carrier 22 will be referred to as the photosensitive drum 22.) 25 is a charger, which responds to the photoconductor 24 on the photosensitive drum 22 by the first high-voltage DC power supply 26, for example, minus in the case of zinc oxide. In the case of selenium, a positive corona is applied to charge the photoconductor 24 on the entire surface. An optical unit 27 projects a pattern light image on the photosensitive drum 22 to form an electrostatic latent image. 28 is a developer, which is a normal one-component insulating toner. The developer 28 may be magnetic toner or non-magnetic toner. Reference numeral 29 is a container having an outlet portion 30 at one end and a replenishing opening portion 31 at the other end and containing a developer 28 therein. Reference numeral 32 is a lid of the supply opening 31 of the casing 29. A sheet-shaped elastic member 33 is made of, for example, a sheet-shaped polyethylene terephthalate having a thickness of about 40 μm, and one end thereof is fixed to one surface 32 a of the lid 32. 34 is a developing roller which is a developer carrying member (henceforth,
Is referred to as a developing roller 34. ) For example, a metal roller made of stainless steel, aluminum or the like, a roller having a metal roller coated with a resin, or the like is preferably used.
As shown in FIG. 3A, the outer peripheral surfaces 34a, 34 of both ends of the developing roller 34 are
b is a smooth surface, and a rough surface having fine irregularities is formed on the central surface 34c. Further, the developing roller 34 is provided at the outlet portion 30 and is installed at a constant interval with respect to the photosensitive drum 22, and rotates counterclockwise, for example, as shown in FIG. The casing 29 is electrically insulated from the photosensitive drum 22 and the developing roller 34.

Reference numeral 35 denotes a fabric brush, which is a cylindrical elastic body, a roller made of sponge, or the like, and a layer of an elastic material 37 is formed on the outer peripheral surface of the mandrel 36. In this embodiment, the cylindrical elastic body 35 is a fur brush (henceforth, in this embodiment, the cylindrical elastic body 35 is referred to as a fur brush 35).
Is composed of conductive fur using rayon fibers containing carbon. Fur brush 35 is a body
In the developer 28 of 29, in sliding contact with the surface of the developing roller 34,
For example, the developer 28 is prevented from spilling by rotating it clockwise and at a peripheral speed of the developing roller 34 or higher. Further, as shown in FIG. 3B, the fibers of the fur brush 35 have a spiral shape in the direction in which the developer 28 moves from the outer peripheral portions on both ends of the fur brush 35 to the central portion during rotation. A scraping plate 38 is in sliding contact with the fur brush 35 to make the amount of the developer 28 in the fur brush 35 uniform. Further, in this embodiment, the scraping plate 38 is made of a conductive material, and the detecting means 43 is connected and used as the detecting plate. In this case, it goes without saying that the scraping plate 38 and the casing 29 are electrically insulated. In this way, by sharing the scraping plate and the detection plate, the structure of the device can be further simplified. FIG. 4 (d) is a diagram showing the detection means 43,
The ammeter M detects the current when the scraping plate 38 is grounded through a resistance R of about 10 KΩ. Further, the fur brush 35 stirs the developer 28,
The friction charging is performed by the friction between the developer and the developer, and the developer is also brought into close contact with or in sliding contact with the surface of the casing 29 and in sliding contact with the scraping plate to assist the friction charging of the developer.

Further, the peripheral speed of the fur brush 35 is set higher than that of the developing roller 34. Therefore, the developer 28 attached to the surface of the developing roller 34 can be scraped off after the developing process. 39 is a partition plate that prevents the uncharged developer 28 from reaching the vicinity of the developing roller 34 and the fur brush 35.
Is to prevent it from staying. In FIG. 3A, 40 is a bearing of the developing roller 34, and 41 is a bearing of the fur brush 35. Reference numeral 43 denotes a second DC high-voltage power supply which is a voltage applying means, and the circuit is opened at the time of development so that no voltage is applied between the developing roller 34 and the fur brush 35, and the developer is charged only during the period when no development is performed. A DC voltage of opposite polarity is applied between the developing roller 34 and the fur brush 35. 44 is a blade which is a layer thickness regulating means for regulating the layer thickness of the developer 28, and in this embodiment, a rubber blade made of an elastic material such as urethane rubber is used, but other rubber materials as the blade material, An elastic synthetic resin such as polyethylene terephthalate or an elastic metal such as phosphor bronze or spring steel may be used, or an elastic metal or a synthetic resin coated with a fluorine resin may be used. Since the accuracy of the end surface of the blade 44 has a great influence on the formation of a uniform thin layer of the developer 28, the straightness of the end portion of the blade 44 is precisely finished to 0.15 mm or less. Further, as shown in FIG. 2 (a), a developer or preventing member 55 is provided on the surface of the blade 44 which is in contact with the developing roller 34. The developer or preventing member 55 is made of an elastic material such as sponge or felt. Made of The blade 44 is provided in pressure contact with the surface of the developing roller 34 on the downstream side of the developer 28 portion of the housing 29 with respect to the rotation direction of the developing roller 34 and on the upstream side of the portion facing the photosensitive drum 22. . As shown in FIG. 2B, this pressure contact position is provided on the downstream side of the vertical line YY passing through the center of the developing roller 34, so that even if the developer 28 is deposited on the tip of the blade 44, Since the toner particles fall by gravity before they become large, it is possible to prevent the occurrence of spot-like fog on the image due to the toner lumps.

Further, the width of the blade 44 is set so as to contact the outer peripheral surfaces 34a and 34b at both ends of the developing roller 34 as shown in FIG. 3 (a). Reference numerals 45 and 46 denote developer sealing materials that prevent the developer 28 from leaking, and are made of, for example, an elastic material such as felt, sponge, or rubber. The developer sealing materials 45 and 46 are in contact with the outer peripheral surfaces 34a and 34b of both ends of the developing roller 34 and the both end surfaces of the blade 44, respectively. By using a conductive material for the fur brush 35, a slight difference in each part of the fur brush 35 causes a difference in the charge amount of the developer 28 during triboelectric charging, and therefore, even if the potentials in each part of the fur brush 35 differ. Has the function of neutralizing the voltage and making the potential uniform. Therefore, for the fur brush 35, it is better to use a conductive material having a specific resistance of about 10 ¹⁰ Ωcm or less, preferably 10 ³ Ωcm to 10 ⁷ Ωcm. Further, as the fur brush 35, not only the conductive rayon fiber as in this embodiment but also other conductive fibers may be used, and a fur brush manufactured by electrostatic flocking for uniform coating is used. It is also effective to use. Further, even if a conductive sponge, a conductive cloth, or a soft wire brush is used as the elastic material 37 of the cylindrical elastic body 35, the aforementioned triboelectric charging, coating, and other operations can be effectively performed. If the developer 28 is a one-component magnetic toner, a magnetic roller is used as the mandrel 36,
It is also effective to form a magnetic brush on the outer periphery thereof to form the cylindrical elastic body 35. It should be noted that the developer 28 in the housing is at least developed with respect to the moving direction of the developing roller 34.
It is configured so that it is not supplied between the developing roller 34 and the fur brush 35 on the downstream side of the facing position of the blade 44 and the upstream side of the facing position of the developing roller 34 and the fur brush 35.

Reference numeral 52 denotes a developer leakage prevention sheet, which is made of an elastic material such as polyethylene terephthalate or urethane rubber having a thickness of 100 μm or less, is lightly contacted with the developing roller 34 as shown in FIG. Developing roller 34 and fur brush
It is attached so that it does not project downstream from the line connecting the centers of 35. Further, as shown in FIG. 3A, the developer sealing materials 45 and 46 are provided at both ends of the developing roller 34, and
As shown in FIG. 7C, the developer leakage prevention sheet 52 can be more reliably operated by overlapping a part of the developer sealing material 45, 46 on the upper portion of the developer leakage prevention sheet 52. Reference numeral 51 denotes a developer leakage prevention member which is made of metal such as stainless steel or aluminum and catches the developer leakage preventing sheet 52 so as not to drop downward even if it leaks from the gap of the developer leakage prevention sheet 52. In this case, since the leakage of the developer 28 is almost completely stopped by the developer leakage prevention sheet 52, the capacity of the developer leakage prevention member 51 may be small. Also, FIG. 4 (b)
As shown in, the upper portion of the downstream side wall of the developer leak prevention member 51 is bent to the downstream side, and the tip thereof is brought into contact with the fur brush 35 to scrape off the excess developer 28 adhering to the fur brush 35. The developer 28 can be returned into the container 29, and the developer 28 can be more reliably prevented from leaking. When the voltage applying means 53 is not used, it is also effective to form the developer leakage prevention member 51 integrally with the casing 29. Reference numeral 53 denotes a voltage applying means, which applies a voltage having a polarity opposite to that of the developer 28 between the fur brush 35 and the developer leak prevention member 51 to suck the developer 28 toward the fur brush 35 side. The leakage of the developer 28 can be prevented more reliably.

The operation of the developing device of the first embodiment configured as described above will be described.

Here, in order to make the operation easy to understand, the photoconductor 24 on the photosensitive drum 22 is zinc oxide, and the cylindrical elastic body 35 has a specific resistance of carbon containing an elastic material 37 on an aluminum mandrel 36 of about 10 ⁵ The surface roughness of the fur brush 35 and the developing roller 34, in which 3600 fibers / cm ² of rayon fibers of Ωcm are planted, is 5μ.
mRmax, the linear pressure of the blade 44 pressed against the developing roller 34 is 25
g / cm, developer or blocking member 55 is sponge, photosensitive drum
The gap between 22 and the developing roller 34 is 0.15 mm, the developer 28 is a normal positively charging non-magnetic one-component toner, the developer leakage prevention sheet 52 is a urethane rubber sheet having a thickness of 90 μm, and the developer leakage prevention is As the member 51, a stainless steel plate having a thickness of 0.3 mm was used, and a DC voltage of 100 V was applied by the voltage applying means 53 with the developer leakage prevention member 51 side being positive, and an experiment was conducted.

In FIG. 1, a high voltage of about -6 kV is applied to the charger 25 by the first high voltage DC power source 26 to negatively charge the entire surface of the photosensitive drum 22 to about -600 V by the negative corona. Next, by projecting a reflected image (pattern light image) of the original illuminated by a halogen lamp or the like by the optical unit 27 onto the negatively charged photosensitive drum 22, the portion corresponding to the non-image portion of the original on the photosensitive drum 22 is reflected light. Is discharged to a residual potential close to 0 V to form a positive electrostatic latent image. Meanwhile, the developer 28 in the casing 29 is supplied into the fur brush 35 by the rotation of the fur brush 35. Next, the excess developer 28 in the fur brush 35 is scraped off by the scraping plate 38 and supplied in an appropriate amount, and is positively charged by friction with the scraping plate 38 and the casing 29. Further, the developer 28 is conveyed to a position facing the developing roller 34 by the rotation of the fur brush 35, and the surface of the developing roller 34 is coated with the charged developer 28. At this time, the developer 28 supplied in an appropriate amount is more uniformly positively charged by the stirring action by the rotation of the fur brush 35 and the friction with the surface of the developing roller 34.

At this time, no voltage is applied between the developing roller 34 and the fur brush 35, and since the casing 29 is electrically insulated from the photosensitive drum 22 and the developing roller 34, a voltage is applied between them. It does not happen that the developer 28 is more easily transferred than the strongly charged developer 28. Therefore,
For example, when the developer 28 not used for development is scraped off and transferred again, only a part of the developer 28 is not overcharged and the developer 28 is uniformly charged. Therefore, a good image can be obtained. According to the experiment, when the developing roller 34 is directly applied with −200V and the fur brush 35 is applied with −120V as viewed from the ground side and the casing 29 is grounded, fog and toner lumps are generated due to uneven charging. After seeing and conducting further tests,
Due to a part of the developer 28 being overcharged, there was a problem that the image density measured with a densitometer decreased from 1.2 to 0.8 on about 150 sheets. On the other hand, when no voltage is applied between the developing roller 34 and the fur brush 35 as in this embodiment, and the case 29 is electrically insulated from the photosensitive drum 22 and the developing roller 34, the developer 28 The charge amount was made uniform to 3 to 6 μC / g, a good image was obtained even in the continuous test, and no decrease in image density was observed.

In this developing state, there is an appropriate amount of the developer 28 in the fur brush 35, and therefore the contact resistance between the fur brush 35 and the developing roller 34 is high, so that the current value of the detecting means 43 is small. Next, when the developing step is repeated and the developer 28 in the housing 29 and the developer 28 in the fur brush 35 are used up, the contact resistance decreases and the current value of the detecting means 43 increases. Therefore, depending on the current value of the detection means 43, the developer in the container 29
The presence or absence of 28 can be detected. Further, the elastic member 33 repeats the developing process, and when the amount of the developer 28 in the casing 29 becomes small, the elastic member 33 is displaced by its own restoring force as shown in FIG. Bias in the direction. Therefore, even if the inclination angle of the bottom surface of the casing 29 is reduced, the developer 28 of the casing 29 can be supplied to the fur brush 35 without any trouble. Therefore, the amount of the developer 28 in the casing 29 can be increased, and the developer 28 can be supplied with a simple and inexpensive structure. In this embodiment, the elastic member 33
Although the lid 32 is provided on the lid 32, it is obvious that the same effect can be obtained by providing the lid 29 on the bottom surface side.

The layer thickness of the developer 28 on the surface of the developing roller 34 coated here is a predetermined thickness or more, and there is some variation. Then, the developer 28 charged on the surface of the developing roller 34 is rotated by the blade 44 by the rotation of the developing roller 34.
Part of it is scraped off by the blade 44 as it passes through a predetermined layer thickness of about 40 μm (at this time, the layer thickness is 10 μm).
m to 70 μm is desirable). Blade 44
As described above, since the end surface of is finished to have a straightness of 0.15 mm or less, uneven coating of the developing roller 34 such as uneven layer thickness of the developer 28 and generation of streaks does not occur. Further, the developer, that is, the prevention member 55 prevents more than necessary developer 28 from being pushed into the abutting portion of the blade 44, so that a stable thin layer of the developer 28 can always be obtained. At this time, the developer 28 contacting the blade 44 moves from the central portion of the developing roller 34 toward both end portions, and also moves from the both end portions of the fur brush 35 to the central portion by the rotation of the fur brush 35 having the spiral shape. To do. Therefore, there is an effect that the developer 28 in the vicinity of both ends of the developing roller 34 and the fur brush 35 does not increase, and the height of the developer 28 in the casing 29 becomes constant. Further, the developer sealing material 4 that is in contact with both end surfaces of the blade 44
Since 5,46 are in contact with the smooth surfaces of the outer peripheral surfaces 34a, 34b of both ends of the developing roller 34, the abrasion is very small even when the developing roller 34 rotates. Further, the developer sealing materials 45 and 46 are the blades 44.
And the joint surface that comes into contact with the developing roller 34 is a smooth surface,
No gap is generated in the joint portion. Therefore,
There is no leakage of the developer 28 due to the component force of being pushed in the axial direction of the developing roller 34. In addition, the developer reservoir inside the casing 29 is arranged in the developing roller 34 with respect to the moving direction of the developing roller 34.
Since it is not provided on the upstream side of the facing position of the fur brush 35, the developer 28 does not leak or scatter.

Next, when the negatively charged electrostatic latent image on the photosensitive drum 22 faces the positively charged developer 28 on the developing roller 34,
The developer 28 can fly by the electrostatic force of the electrostatic latent image on the photosensitive drum 22 to develop the latent image. At this time, since the photosensitive drum 22 and the developing roller 34 are moved in the forward direction at the developing position and the peripheral speeds of the photosensitive drum 22 and the developing roller 34 are made substantially equal, the reproducibility of a solid image is very good. Then, the excess developer 28 that has not been used for development is carried to the downstream side while being attached to the developing roller 34 and passes through the developer leak prevention sheet 52. Since it is only in light contact with the
Once it is carried into the sheet 29 and once passes through the developer leakage prevention sheet 52, it will not be leaked out again. In addition, since the developer leakage prevention member 51 side is made positive by the voltage applying means 53 and a direct current voltage of 100 V is applied, the developer 28
Is sucked to the fur brush side, and the leak prevention effect is further enhanced. Further, as described above, even if a very small amount of the developer 28 leaks, the developer leak preventing member 51 does not contaminate the inside of the developing device or the equipment below. After the development, the developer 28 adhering to the surface of the developing roller 34 is scraped off by the fur brush 35, and is developed between the developing roller 34 and the fur brush 35 by the second DC high-voltage power source 42 only during the non-developing period. Apply a voltage of the opposite polarity to that of the time (the applied voltage at this time is 30V to 250V
The degree is desirable, and 100 V is applied in this embodiment. ) The excess developer on the developing roller 34 is attracted to the fur brush 35 side by the electric field to erase the development history on the developing roller 34. Therefore, a high-quality image without ghost can be obtained. That is, this developing device can uniformly charge the developer 28 on the developing roller 34 and can make the layer thickness uniform, and further, there is no scattering or leakage of the developer 28, and there is no fog or density unevenness. High-quality images can be obtained. Further, since the developing device is agitated and frictionally charged by the rotation of the fur brush 35, the rise time until the developer 28 is charged to a predetermined charge amount is short and the predetermined charge amount is reached within 1 second. It does not require extra waiting time.

Further, the present developing device has a simple structure and a small size as described above, and in addition, since the toner leakage and scattering does not occur, restrictions on the arrangement of the developing device can be reduced.

In this embodiment, an example of an experiment on normal development (positive-positive development) in an electrophotographic copying machine was described, but it goes without saying that the present invention is also applicable to reversal development (negative-positive development) in a laser printer or the like. Yes.

Next, a second embodiment of the present invention will be described.

FIG. 6 shows a second embodiment of the present invention, in which members having the same functions as those of the first embodiment of the present invention are designated by the same reference numerals. In FIG. 6, as in the first embodiment, the layer thickness regulating member 44 is an elastic blade, but in this embodiment no force is applied to the blade and the free end of the blade is the surface of the developing roller 34. It comes in contact with. The cylindrical elastic body 35 is a fur brush (henceforth, in this embodiment also, the cylindrical elastic body 35 will be referred to as a fur brush.
Called 35. As shown in FIGS. 7 (a) and 7 (b), the fur brush 35 is partially bristled only at both ends 35a, 35b. Further, the peripheral speed of the fur brush 35 is lower than that of the developing roller 34. Reference numeral 49 is a sheet-shaped swing member, which is formed of an elastic member such as resin, leaf spring, or rubber. In this embodiment, polyethylene terephthalate having a thickness of about 70 μm is used, and as shown in FIG.
The a and 49b are formed to be partly long, and both ends 49a and 49b thereof are in contact with the outer peripheral surfaces 37a and 37b of the fur brush 35 at both ends. The other end 49c is fixed to the inner surface of the casing 29 as shown in FIG. The other structure is the same as that of the first embodiment.

Next, the operation of the second embodiment of the present invention will be described.

The layer thickness control unit 44 is an elastic blade, and as described above, the free end of the blade is in contact with the surface of the developing roller 34, so that the developer 28 on the developing roller 34 is not subjected to an excessive force. A uniform thin layer of the developer 28 having no stripes or unevenness is formed. Therefore, a high-quality image can be obtained. Further, by setting the peripheral speed of the fur brush 35 lower than that of the developing roller 34, the fur brush 35 in the developing step or the like is bent in one direction by the load of the developer 28 and the contact portion of the scraping plate 38. Then, it is bent in the opposite direction at the sliding contact portion with the developing roller 34. Therefore, the fur brush 35 is not always bent in only one direction, so that the fibers of the fur brush 35 do not fall and the stirring action with the developer 28 is ensured, and a stable high-quality image for a long period of time is obtained. Can be obtained. Further, by making the peripheral speed of the fur brush 35 substantially the same as the peripheral speed of the developing roller 34, it is possible to combine the effects described in the first embodiment and the effects described in the second embodiment of the present invention. It is possible. Further, as the fur brush 35 rotates, the swing member 49 has one end 49c as a fulcrum, and the other ends 49a, 49b at both end outer peripheral surfaces 35a, 35b of the fur brush 35.
It comes into contact with and vibrates constantly due to its own restoring force. Therefore, even if the inclination angle of the bottom surface of the housing 29 is reduced,
The 29 developers 28 can be supplied to the fur brush 35 without any trouble. Therefore, the amount of the developer 28 in the casing 29 can be increased, and the developer 28 can be supplied with a simple and inexpensive structure.

Next, a third embodiment of the present invention will be described.

FIG. 8 shows a third embodiment of the present invention, in which parts having the same functions as those of the first embodiment of the present invention are designated by the same reference numerals. In FIG. 8, the layer thickness regulating means 44 is fixed by a rigid blade with a predetermined layer thickness of the developer 28 accurately kept from the surface of the developing roller 34, and thereby uniform and free from streaks and unevenness. A thin layer of developer 28 is formed. Further, even if the layer thickness regulating means 44 is a rigid blade, the fact that the developer, that is, the prevention member 55 is provided and the effect of the developer, that is, the prevention member 55 is the first embodiment of the present invention. Obviously, it is similar to that explained in. The cylindrical elastic body 35 uses a conductive sponge as the elastic material 37 and is formed into a cylindrical roller around the aluminum mandrel 36. Note that it is easy to understand that even when a conductive sponge is used as the elastic material 37 of the cylindrical elastic body 35, the effects of the triboelectrification, coating, etc. described in the first embodiment are effectively performed. In this embodiment, the developing roller 34 and the cylindrical elastic body 35 are opposed to each other at a close position with a constant space (this space is preferably 0.1 to 0.5 mm). Needless to say, the developer 28 charged as described in the first embodiment is transferred to the developing roller 34 even if there is such an interval. Reference numeral 48 is a bias voltage applying means for applying a DC bias voltage between the photosensitive drum 22 and the developing roller 34.

Next, the operation of the third embodiment of the present invention will be described.

When the charged developer 28 on the cylindrical elastic body 35 rotates to a position facing the developing roller 34, it is coated on the developing roller 34 in a thickness larger than a predetermined thickness as in the first embodiment. It is regulated to a predetermined thickness by the thickness regulation means 44.
Next, when facing the electrostatic latent image on the photosensitive drum 22, a bias voltage applying means 48 applies a DC bias voltage between the photosensitive drum 22 and the developing roller 34 to develop the image. By applying the bias voltage, the developer 28 flies due to the synergistic action of the electrostatic force due to the electrostatic latent image and the electric field due to the DC bias, so that the development can be performed more effectively. The developing device having this configuration may be an AC voltage or a DC voltage superposed with an AC voltage, and the bias voltage applying means may not be used.

It goes without saying that the present invention is not limited to the above-described three embodiments, and a larger number of configurations can be made by combining the respective elements such as charging of the developer, coating on the developing roller, and regulation of the layer thickness. . The present invention is also non-magnetic 1
Since it is well adapted to the component developers and is not in contact with the latent image carrier, it is also advantageous for forming a color image in which developers of a plurality of colors are superposed and developed on the latent image carrier.

EFFECTS OF THE INVENTION According to the present invention, since the developer in the developing section is uniformly charged and is formed to have a uniform layer thickness, it is possible to form a high-quality image without toner scattering, fog, and development density unevenness.
Especially when coating the developer, a thin layer without unevenness and streaks is formed due to the accuracy of the end surface of the blade, and toner particles are not generated by the developer, that is, the prevention member, and therefore spotted fog is not generated on the image. A high quality image can be obtained. In addition, since the developer does not spill from the developing device, it does not contaminate other developing devices and devices inside.

Furthermore, the present invention is capable of non-contact flight development of a non-magnetic one-component developer by a DC electric field, and has a simple structure.
Since there are few restrictions on the arrangement of the developing device, it is advantageous in forming a color image in which developers of a plurality of colors are superposed and developed on the latent image carrier, and its practical effects are great.

[Brief description of drawings]

FIG. 1 is a sectional view of an image forming apparatus according to the first embodiment of the present invention, and FIGS. 2, 3, and 4 are respective structures of respective portions of the image forming apparatus according to the first embodiment of the present invention. FIG. 5 is another sectional view of the image forming apparatus according to the first embodiment of the present invention, FIG. 6 is a sectional view of the image forming apparatus according to the second embodiment of the present invention, and FIG. 7 is the present invention. Of the image forming apparatus in the second embodiment of the present invention, FIG. 8 is a sectional view of the image forming apparatus in the third embodiment of the present invention, FIG.
FIG. 10 is a cross-sectional view of essential parts of a conventional image forming apparatus. 22 ... Photosensitive drum, 28 ... Developer, 29 ... Body, 33
...... Elastic member, 34 …… Developing roller, 35 …… Fur brush, 38 …… Scraping plate, 39 …… Partition plate, 42 …… DC high-voltage power supply, 43 …… Detecting means, 44 …… Blade, 47… … Pressing spring, 48 …… Bias voltage applying means, 49 …… Swinging member,
51: developer leak prevention member, 52: developer leak prevention sheet, 53: voltage applying means, 55: developer clogging prevention member

Claims (15)

[Claims] 1. An image forming apparatus comprising: a latent image holding member for holding an electrostatic latent image; and a developing device for visualizing the electrostatic latent image formed on the electrostatic holding member. Includes a developer carrying member, a means for charging the developer, and a layer thickness regulating means for pressing the developer carrying body to regulate the charged developer on the developer carrying body to a predetermined layer thickness. In the non-magnetic one-component developing device, the layer thickness regulating means is an elastic blade made of an elastic body, one end of the elastic blade is fixed to the developing device, the other end is a free end. By the elastic force of the elastic blade, the straightness of the edge is 0.15 while pressing the developer carrier in a surface contact state including the edge of the edge.
mm or less, further, the positional relationship between the fixed end and the free end of the elastic blade, the free end portion of the blade, in the direction away from the developer carrier by the frictional force received from the developer carrier. An image forming apparatus having a positional relationship such that a moment is received around the fixed end portion. 2. The image forming apparatus according to claim 1, wherein the contact or closest position between the elastic blade and the developer carrying member is provided on the downstream side of a vertical line passing through the center of the developer carrying member. . 3. A developer spill prevention means for preventing developer spillage, which is provided upstream of a position where a developer carrier and a developer charging means face each other and below the developer carrier. The image forming apparatus according to item 1 above. 4. A developer spill prevention means is fixed to a U-shaped developer leakage prevention member and a side wall on the downstream side of the developer leakage prevention member as viewed from the developer carrier, and is attached to the downstream side. The image forming apparatus according to claim 3, comprising a developer leakage prevention sheet that is in contact with the developer bearing member. 5. A U-shaped developer leakage preventing member has a side wall which is located on the downstream side of the developer carrying member and is bent toward the downstream side.
The image forming apparatus according to claim 3 or 4, wherein the front end is brought into contact with the developer charging means. 6. A developer seal material made of an elastic material is provided at both ends of the developer carrier, and a part of the developer seal material is superposed on an upper portion of the developer leakage prevention sheet abutting against the developer carrier. The image forming apparatus according to claim 3 or 4. 7. A means for charging a developer rotates a cylindrical elastic body to cause a relative motion between the developer and a developing device constituting member, so that the developer and the developing device constituting member are separated from each other. The image forming apparatus according to claim 1, wherein the developer is triboelectrically charged by the friction of. 8. A patent provided with a scraping plate which is in sliding contact with a cylindrical elastic body to scrape off excess developer on the cylindrical elastic body to make the developer on the cylindrical elastic body uniform. The image forming apparatus according to claim 7. 9. The image forming apparatus according to claim 7, wherein the cylindrical elastic member is a roller made of a fur brush or a sponge. 10. A fur brush or sponge roller having a specific resistance of 10 ¹⁰ Ωcm or less.
The image forming apparatus according to the item. 11. A developer carrying member and a cylindrical elastic member are brought into contact with each other, and at the contact position, the developer carrying member and the cylindrical elastic member are moved in the forward direction and the cylindrical elastic member is moved. 2. The image forming apparatus according to claim 1, wherein the peripheral speed of the developer is higher than the peripheral speed of the developer carrying member. 12. An uncharged developer reaches a developing portion by providing a partition plate which is in contact with or close to the cylindrical elastic body at an upstream side of a facing portion between the cylindrical elastic body and a developer carrying member. The image forming apparatus according to claim 1, wherein the image forming apparatus is not provided. 13. The image forming apparatus according to claim 1, wherein the developer on the developer carrying member and the latent image holding member are not in contact with each other. 14. The method according to claim 1, wherein the developer carrying member and the latent image holding member are moved in the forward direction at the developing position, and the peripheral speeds of the developer carrying member and the latent image holding member are substantially equal to each other. Image forming device. 15. The image forming apparatus according to claim 1, further comprising means for applying a DC electric field between the developer carrying member and the latent image holding member.