JPS63142376A - Developing device - Google Patents

Abstract

PURPOSE:To eliminate a decrease in image density and to perform development of high image quality in the beginning of the development and thereafter by applying a voltage higher than a prescribed voltage from a voltage applying means at the time of voltage application and then applying the prescribed voltage thereafter. CONSTITUTION:A developer 28 is conveyed by the rotation of a fur brush 30 at a position opposite to a developing roller 29 to coat the surface of the developing roller 29 with the electrostatically charged developer 28. At this time, the developer 28 which is supplied by a proper amount is charged electrostatically and further uniformly by the rotation of the fur brush 30 to the positive polarity by friction against the surface of the developing roller 29. Then, when the voltage is applied from a 2nd DC high voltage power source 46 to between the developing roller 29 and fur brush 30, the voltage is higher than the specific voltage to increase the supply amount of the developer 28 from the fur brush 30 and after the voltage application, the prescribed voltage is applied. Consequently, the supply ability for the developer 28 from the fur brush 30 is increased to eliminate a decrease in image density in the beginning of the development and thereafter.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a developing device for an image forming apparatus such as a copying machine or a printer to which electrophotography is applied.

BACKGROUND OF THE INVENTION Conventionally, developing methods using a soft developer are roughly divided into two types: methods using a two-component developer and methods using a one-component developer.

The method using a two-component developer uses a mixed developer of toner and carrier, so it requires a toner concentration control device to maintain a constant mixing ratio of toner and carrier, and has disadvantages such as periodic replacement due to carrier deterioration. have. Therefore, recently, in order to eliminate the above-mentioned drawbacks, a developing method using only a one-component developer without using a carrier has been proposed.

This developing method is disclosed, for example, in Japanese Patent Application Laid-Open No. 56-110963 and US Pat. No. 4,083,326, and the construction thereof is shown in FIGS. 9 and 10.

In Figure 9 (Japanese Unexamined Patent Publication No. 56-110963),
6 is a photoconductor, 7 is a developing roller made of a conductive urethane material that is in sliding contact with the photoconductor 6, 8 is a conductive fur brush that is in sliding contact with the developing roller 7, and 9 is a circuit for applying a voltage to the conductive fur brush 8 and the developing roller 7. A power supply 10 is a voltage divider for adjusting the voltage of the power supply 9, and a hopper 11 stores the toner 12. The toner 12 supplied from the hopper 11 to the fur brush 8 is frictionally charged by the fur brush 8, and then transferred from the fur brush 8 to the developing roller 7 by the voltage of the power source 9.
The electrostatic latent image is coated on the photoreceptor 6 and then developed by adhering to the electrostatic latent image on the photoreceptor 6. Further, when a predetermined developed density is not obtained as a result of development, the voltage divider 10 is used to adjust the density.

In FIG. 10 (U.S. Pat. No. 4,083,326), 13 is a developing roller, 14 is a toner, 15 is a hopper,
16 is the blade, 17 is the photoreceptor of the sheet test, 18.19
20 is a conductive fur brush in sliding contact with the developing roller 13;
A first power source 21 applies a voltage to the hopper 15 and the conductive fur brush 18, and a second power source 21 applies a voltage to the conductive fur brush 18 and the developing roller 7.

Also the second one? ! The voltage applied by the source 21 is the voltage applied by the first power source 2
The applied voltage is set to be higher than the applied voltage of 0, and lower than the voltage of the electrostatic latent image on the photoreceptor 17. The toner 14 triboelectrically charged by the fur brush 18 is supplied to the first and second power sources 20.
．． 21, it is supplied from the hopper 15 to the developing roller 13 via the conductive fur brush 18, and after being smoothed by the blade 16, it adheres to the electrostatic latent image on the photoreceptor 17 and is developed. . Next, the toner 14 on the developing roller 13 after development is scraped off with a conductive fur brush 19 to remove the development history on the developing roller.

Problems to be Solved by the Invention However, with this type of system, there is a problem in terms of the time it takes for the developer (toner) to reach a predetermined layer thickness on the developing roller, making it difficult to reproduce high-quality images. was making it difficult. That is, in the case of those shown in FIGS. 9 and 10, it took a long time to build up the toner to a predetermined layer thickness from a state where there was no toner on the developing roller. Therefore, a problem arises in which the image density is low, especially at the initial stage of development when the process speed is high. Therefore, it has been difficult to reproduce high-quality images.

The present invention solves the conventional problems and provides a developing device for an image forming apparatus with high image quality.

Means for solving the problems and technical means of the present invention for solving the above problems are to apply a voltage between the developer carrier and charging means to charge the developer to the developer carrier. A voltage applying means for supplying the voltage is provided, and the voltage of the voltage applying means is applied at a predetermined voltage or higher when applying the voltage, and is applied at a predetermined voltage after the voltage is applied.

action The effect of this technical means is as follows.

That is, the voltage of the voltage application means between the developer carrier and the charging means is such that when applying the voltage, the voltage is applied to a predetermined voltage or higher to increase the amount of developer supplied from the charging means, and when the voltage is applied, After that time, by applying a predetermined voltage to increase the developer supply capacity from the charging means,
It is possible to eliminate a decrease in image density at the initial stage of development and after the initial stage of development. Therefore, high-quality development is possible.

Examples Examples of the present invention will be described below. 1 to 3 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 charge carrier, such as electrostatic recording paper or a photosensitive drum. In this embodiment, the charge carrier 22 is a photosensitive drum having a photoconductor 24 such as zinc oxide, selenium, or an organic photoconductive material supported on the surface of an aluminum base 23. (Thus, the charge holding body 22 is hereinafter referred to as the photosensitive drum 22.) The charge holding body 22 is hereinafter referred to as the photosensitive drum 22. In the case of negative or selenium, a positive corona is applied to charge the entire surface of the photoconductor 24.

Reference numeral 27 denotes an optical section that projects a patterned optical image onto the photosensitive drum 22 to form an electrostatic latent image. A developer 28 is a normal one-component insulating toner. Note that the developer 28 may be a magnetic toner or a non-magnetic toner.

29 is a developing roller which is a developer carrier, and the developing roller 2
9 is a metal roller made of stainless steel, aluminum, or the like, or a metal roller whose surface is coated with resin. Preferably, as shown in FIG.゛A rough surface with fine irregularities is formed on the surface 29e, and the photosensitive drum 22
For example, as shown in FIG. 1, it is rotated counterclockwise. 30 is developer 28
The cylindrical elastic body 30 is a fur brush, a roller made of sponge, etc., and a layer of elastic material 32 is formed on the outer peripheral surface of the core metal 31. In this embodiment, the cylindrical elastic body 30 is a fur brush, and the elastic material 32 is made of conductive fur using carbon-containing rayon fibers. Also fur brush 30
is in sliding contact with the surface of the developing roller 29 and rotated, for example, in a clockwise direction and at a circumferential speed higher than the circumferential speed of the developing roller 29 . Further, the fibers of the fur brush 30 have a spiral shape in the direction in which the developer 28 moves from the outer periphery of both ends of the fur brush 30 to the center when it rotates, as shown in FIG. Reference numeral 33 denotes a developer storage means, which is composed of a storage section 34 that stores the developer 28 and a first toner supply means 35 that supplies the developer to the developer carrier 29 . Further, the storage section 34 is formed by a part of the storage space 37 and has an opening 36 for replenishing the developer 28 at one end. Further, the toner supply means 35 is connected to the mandrel 3.
One end of a sheet-like elastic member 39 made of polyethylene terephthalate or the like having a thickness of approximately 30 μm is fixed to the outer circumferential surface of 8, and the core metal 38 is rotated or oscillated to supply the developer 28 to the developer carrier 29. It is something. In this embodiment, the mandrel 38 rotates clockwise. A partition plate 40 is provided between the first developer supply means 35 and the developer carrier 29, and is an opening through which the developer 28 flows in and out between the first toner supply means 35 and the developer carrier 29. Part 41f! ：I have it. Reference numeral 42 denotes a scraping plate, which is formed from a part of the fur brush 37 and slides into contact with the fur brush 30 to equalize the amount of the developer 28 in the fur brush 30 and scrape off the overcharged developer 28 in the fur brush 30. It is something to be dropped. 43 is a lid of the replenishment opening 36. As shown in FIG. 2, 44 is a bearing for the developing roller 29, and 45 is a bearing for the fur brush 30. Reference numeral 46 denotes a second DC high-voltage power source serving as a voltage applying means, which applies a voltage between the developing roller 29 and the fur brush 30. Note that the voltage of the voltage applying means 36 is set to a predetermined voltage or higher when applying the voltage to increase the amount of developer 28 supplied from the fur brush 30, and after the voltage is applied, the voltage is set to a predetermined voltage. By increasing the supply capacity of the developer 28 from the fur brush 30 by applying the voltage, the structure is designed to eliminate a decrease in image density at the initial stage of development and after the initial stage of development. 47 is the second DC high voltage 1!
Source 46 no 1! This is a detection means that detects the flow value and detects the presence or absence of the developer 28. A blade 48 is a layer thickness regulating means for regulating the layer thickness of the developer 28. In this embodiment, a rubber blade made of an elastic material such as urethane rubber is used. It may be made of an elastic synthetic resin such as polyethylene terephthalate, an elastic metal such as phosphor bronze or spring steel, or an elastic metal or synthetic resin coated with a fluororesin.

Further, the blade 48 is provided in pressure contact with the surface of the developing roller 29 on the downstream side of the storage section 34 and upstream of the portion facing the photosensitive drum 22 with respect to the rotating direction of the developing roller 29 . Furthermore, the width of the blade 48 is set to such a length that it comes into contact with the outer circumferential surfaces 29a and 29b at both ends of the developing roller 29, as shown in FIG. '49.50 is a sealing material for preventing the developer 28 from leaking, and is made of, for example, felt or trousers material. Also, the sealing material 49.50 is the developing roller 2.
9 and both end surfaces of the blade 48. By using a conductive material, the fur brush 30 has the function of preventing overcharging of the frictionally charged developer 28 on the developing roller 29 and making the potential uniform. Therefore, the fur brush 30 has a specific resistance of about 1010 Ωcm or less, preferably 103 Ωcm.
It is better to use a conductive material with a conductivity of 107 to 107 Ωcm. In addition, the fur brush 30 may be made of not only conductive rayon fiber as in this embodiment, but also other conductive fibers or J fibers.Also, in order to make the coating uniform, it can be fabricated using electrostatic flocking. It is also effective to use a hair brush. Furthermore, it goes without saying that the above-described effects of frictional charging, coating, etc. can be effectively performed even if a conductive sponge, conductive cloth, or soft wire brush is used as the elastic material 32 of the cylindrical elastic body 30. Note that when the developer 28 is a one-component magnetic toner, it is also effective to use a magnetic roller as the mandrel 31 and form a magnetic brush on its outer periphery to form the cylindrical elastic body 30.

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

Here, in order to make the operation easier to understand, the photosensitive drum 22
The upper photoconductor 24 is made of zinc oxide, and the cylindrical elastic body 30 is made of rayon fibers containing carbon and having a specific resistance of about 105 Ωcm as an elastic material 32 on an aluminum core 31.
A fur brush with about 600 hairs/cm2 flocked, the surface roughness of the developing roller 29 is 5 μmRmax, the linear pressure of the blade 48 in pressure contact with the developing roller 29 is 25 g/cm, the gap between the photosensitive drum 22 and the developing roller 29 is 0.15 mm, As the developer 28, an ordinary positively charged non-magnetic one-component toner was used in the experiment.

In Figure @1, the charger 27 is connected to the first high-voltage DC power supply 26.
A high voltage of about -6 kV is applied, and the entire surface of the photosensitive drum 22 is negatively charged to about -600 cm by a negative corona. Next, if a reflected image (pattern light image) of the document irradiated by a halogen lamp or the like is projected by the optical section 27 onto the negatively charged photosensitive drum 22, the portion corresponding to the non-image area of the document on the photosensitive drum 22 will be exposed to the reflected light. The charge is removed to a residual potential close to OV, forming a positive electrostatic latent image.

Meanwhile, the developer 28 in the storage section 34 is transferred to the first supply means 3.
Excess developer 28 in the fur brush 30 supplied through the opening 41 by the scraping plate 42 is scraped off by the scraping plate 42, and is supplied to the amount a and removed by the scraping plate 42. It becomes positively charged due to friction with the cylinder body 37. Further, this developer 28 is conveyed by the rotation of the fur brush 30 to a position facing the developing roller 29, and the surface of the developing roller 29 is coated with the charged developer 28. At this time, the developer 28 supplied in an appropriate amount is further uniformly positively charged due to friction with the surface of the developing roller 29 due to the rotation of the fur brush 30. When the voltage is applied by the DC high-voltage power supply 46, the voltage is applied above a predetermined voltage, and the developer 28 from the fur brush 30 is applied.
By increasing the supply amount of the developer 28 from the fur brush 30 by increasing the supply amount of the developer 28 from the fur brush 30 by applying a voltage to a predetermined voltage after applying the voltage, the image density can be increased at the initial stage of development and after the initial stage of development. The decline can be eliminated. Further, the voltage applied by the second DC high voltage power supply 46 is 30
It is desirable that the voltage be about 250V, and in this embodiment, the voltage at the time of voltage application is 200V, and the voltage after voltage application is 100V. In addition, the second DC high voltage power supply 4
When the developer 28 is transferred from the fur brush 30 to the developing roller 29 by the electric field generated by 6, even if there is uncharged developer or developer charged with the opposite sign in the developer 28, the developer is not transferred. Only the normally charged developer 28 that is less likely to be charged contributes to development. Therefore, a good image can be obtained. In this developing state, the fur brush 30
There is an appropriate amount of developer 28 inside the fur brush 3.
Since the contact resistance between 0 and the developing roller 29 is high, the detection means 4
The current value of 8 is small. Next, the developing process is repeated, and when the developer 28 in the storage section 34 and the developer 28 in the fur brush 30 are used up, the contact resistance becomes lower and the current value of the detection means 48 becomes larger. Therefore, the detection means 48
The presence or absence of the developer 28 in the storage section 34 can be detected based on the current value. Further, the first supplying means 35 repeats the above-mentioned developing process, and even if the amount of the developer 28 in the storage section 34 decreases, the elastic member 39 of the sheet sample is still rotating clockwise, so as shown in FIG. The developer 28 can be constantly supplied into the fur brush 30 through the opening 41 by being displaced as shown. Therefore, even if the angle of inclination of the bottom surface of the storage section 34 is small, the developer 28 in the storage section 34 can be supplied to the fur brush 30 without any problem. Further, since the developer 28 is agitated within the storage section 34 by the elastic member 39 of the sheet sample, there is an effect that the height of the developer 28 within the storage section 34 is kept constant. Here, the developing roller 29 is coated by adjusting the voltage of the second DC high voltage power supply 46.
The layer thickness of the developer 28 on the surface is more than a predetermined thickness, and there is some variation. Next, as the developing roller 29 rotates, the charged developer 28 on the surface of the developing roller 29 passes through the blade 48 .
A part of the layer is scraped off and the thickness is regulated to a predetermined layer thickness, that is, about 40 μm (the layer thickness at this time is preferably about 110 Atm to 70 Atm). At this time, the developer 28 in contact with the blade 48 moves from the center of the developing roller 29 toward both ends, and moves from both ends of the fur brush 30 to the center due to the rotation of the spiral-shaped fur brush 30. do. Therefore, the developer 28 near both ends of the developing roller 29 and the fur brush 30 does not increase, and the height of the developer 28 in the storage section 34 is kept constant.

Furthermore, a sealing material 49 that is in contact with both end surfaces of the blade 48
．． 50 are outer circumferential surfaces 29a and 29 at both ends of the developing roller 29.
Since the sealing materials 49 and 50 are in contact with the smooth surface of the blade 48 and the developing roller 29, there is very little wear even when the developing roller 29 rotates, and there is no scattering or leakage of the developer 28. The joint surface that comes into contact with is a smooth surface, and no gap is generated in the joint portion. Therefore, there is no leakage of the developer 28 due to the force pushed in the axial direction of the developing roller 29.

That is, this developing device uses the developer 28 on the developing roller 29.
can be charged uniformly and the layer thickness can be made uniform,
Furthermore, it is possible to obtain high-quality images without scattering or leakage of the developer 28, and without fogging or density unevenness. Furthermore, since the circumferential speeds of the developing roller 29 and the photosensitive drum 22 are made the same, edge effects can be eliminated when developing a latent image. Further, in this developing device, 28 ft of developer in the fur brush 30 flies and adheres onto the developing roller 29 due to the voltage of the second DC high voltage power supply 46.
It takes 0.5 seconds for the film to rise to the specified layer thickness.
Since it can be done quickly at less than c, no extra waiting time is required.

Next, when the negatively charged electrostatic latent image on the photosensitive drum 22 faces the positively charged developer 28 on the developing roller 29, the developer 28 flies away due to the electrostatic force of the electrostatic latent image on the photosensitive drum 22. Then, the latent image can be developed. After the development, the developer 28 adhering to the surface of the developing roller 29 is scraped off by the fur brush 3o to erase the history of the developing roller 29. Therefore, a high-quality image without ghosts can be obtained. Next, the developer 28 scraped off by the fur brush 30 is conveyed by the fur brush 30, and then scraped off by the scraping plate 42 to form the opening 41.
Since the developer is returned to the storage section 34 through the developer carrier, the developer on the developer carrier is not overcharged. Therefore, high-quality development is possible. Furthermore, this developing device can supply developer to the developing roller and scrape off the developer on the developing roller after development with one fur brush, making the 416 structure simple and compact. Since the structure is free from leakage and scattering, restrictions on the arrangement of the developing device can be expanded. Note 1. In this embodiment, an example was explained in which regular development (positive-positive development) in an electrophotographic copying machine was tested, 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.

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

FIG. 5 shows a second embodiment of the invention, in which members having the same functions as in the first embodiment of the invention are given the same numbers. In FIG. 5, the XJ thickness regulating member 48 is a rigid body made of metal such as stainless steel, coated with fluororesin, hard resin, ceramics, etc. It is in contact with. The peripheral speed of the fur brush 30 is set lower than the peripheral speed of the developing roller 29. A second DC high voltage power supply 46 is connected to an AC power source between the developing roller 29 and the fur brush 30.
A voltage obtained by superimposing a positive DC voltage on the voltage is applied to the fur brush 30 side. The other configurations are the same as the first embodiment. In this embodiment, the layer thickness regulating member 48 is formed by integrally forming the stainless steel of the front end plate 48 and a phosphor bronze plate of R351 for the spring.

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

In FIG. 5, by configuring the layer thickness regulating means 48 with a rigid body such as metal, a smoother surface can be obtained compared to rubber or the like, and by bringing this into contact with the developing roller 29, streaks and unevenness can be prevented. A thin, uniform layer of developer 28 is formed, free of blemishes. Furthermore, by making the peripheral speed of the fur brush 30 slower than the peripheral speed of the developing roller 29, the fur brush 30 is bent in one direction during the developing process due to the load of the developer 28 and the contact portion of the scraping plate 42. After that, it is bent in the opposite direction at the sliding contact portion with the developing roller 29. Therefore, the fur brush 30 is never bent in one direction. Therefore, the fibers of the fur brush 30 are prevented from collapsing, and the stirring action with the developer 28 is ensured, making it possible to obtain stable, high-quality images over a long period of time. Further, in the second DC high voltage power supply 46, by superimposing a DC voltage on the AC voltage, the surface of the developing roller 29 is coated with the developer 28 to a predetermined layer thickness or more, and the surface of the developing roller 29 after development is The developer 28 adhering to the top is moved back and forth between the fur brush 30 and the developing roller 29 by the AC voltage, the history of the developing roller 29 is erased, and the developer 28 is moved back and forth between the fur brush 30 and the developing roller 29.
This prevents agglomeration of the developer and high adhesion of the developer to the developing roller 29. Therefore, a high-quality image without ghosts can be obtained.

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

FIG. 6 shows a third embodiment of the invention, in which parts having the same functions as in the first embodiment of the invention are given the same numbers. In FIG. 6, the layer thickness regulating member 48 is a rigid body made of metal such as stainless steel, coated with fluorine resin, hard resin, ceramics, etc. It is mounted accurately away from the surface of the developing roller 29. The cylindrical elastic body 30 uses a conductive sponge as the elastic material 32, and is formed into a cylindrical roller around an aluminum core 31. In addition, the cylindrical elastic body 3
It is easy to understand that even if a conductive sponge is used as the zero elastic material 32, the effects of frictional charging, coating, etc. described in the first embodiment can be effectively performed. In this embodiment, the developing roller 29 and the cylindrical elastic body 30 face each other at a close position with a constant distance (this distance is preferably 0.1 to 0.5 mm) maintained.

Needless to say, even with such a gap, the charged developer 28 is transferred to the developing roller 29 as described in the first embodiment. A bias voltage applying means 52 applies a DC bias voltage between the photosensitive drum 22 and the developing roller 29.

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

When the charged developer 28 on the cylindrical elastic body 30 rotates and comes to a position facing the developing roller 29, it is coated on the developing roller 29 to a thickness greater than a predetermined thickness, as in the first embodiment, and a layer is formed. When facing the electrostatic latent image on the zero-order photosensitive drum 22 whose thickness is regulated to a predetermined thickness by the thickness regulating means 48, the bias voltage applying means 52 applies a DC bias between the photosensitive drum 22 and the developing roller 29. Apply voltage and develop. By applying a bias voltage, the developer 28 is blown away due to the synergistic effect of the electrostatic force caused by the electrostatic latent image and the electric field caused by the DC bias, so that more effective development can be achieved. It should be noted that the developing device having this configuration can be used with a bias voltage that is either an alternating current voltage or a direct current voltage with an alternating current voltage superimposed, and it is also possible to use no bias voltage applying means.

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

FIG. 7 shows a fourth embodiment of the present invention, in which parts having the same functions as in the third embodiment of the present invention are given the same numbers. In FIG. 7, the layer thickness regulating means 48 is a blade made of an elastic body or a rigid body. In this embodiment, an elastic blade is used, and its material is the same as that of the first embodiment.

This blade 48 has one end in pressure contact with the surface of the developing roller 29 downstream of the storage section 34 and upstream of the part facing the photosensitive drum 22 with respect to the rotating direction of the developing roller 29, and the other end thereof The one end portion is fixed to a rest 37 so that it is in a position where it acts to bite into the developing roller 29 side due to the frictional force received at the pressure contact portion when the developing roller 29 rotates. Therefore, there is an effect of preventing aggregation or solidification of the developer 28. Further, in this embodiment, the shape of the portion of the blade 48 in pressure contact with the developing roller 29 is a convex shape. Therefore, the facing distance between the developing roller 29 and the blade 48 after regulating the layer thickness is increased, and the charged developer 28 on the developing roller 29 does not fly to the blade 48. Therefore, more uniform coating can be achieved.

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

FIG. 8 shows a fifth embodiment of the present invention, in which parts having the same functions as in the third embodiment of the present invention are given the same numbers. In FIG. 8, layer thickness regulating means 48
is an elastic or rigid blade; in this embodiment, an elastic blade is used, and its material is the same as in the first embodiment. This blade 48 has one end located downstream of the storage section 34 with respect to the rotational direction of the developing roller 29.
The other end is brought into pressure contact with the surface of the developing roller 29 on the upstream side of the part facing the photosensitive drum 22, and one end of the mark escapes from the surface of the developing roller 29 due to the frictional force received at the pressed part when the developing roller 29 rotates. In this embodiment, the blade 48 is fixed to the blade 37 at a position where it acts
The shape of the pressure contact portion with the developing roller 29 is a convex portion.

Therefore, the developer 28 partially scraped off by the blade 48 changes its flow in the direction of the arrow along the wall surface of the convex portion of the blade 48 due to the force of the following developer 28, and falls toward the cylindrical elastic body 30. . As a result, the developer 28 flows back to the area where the developing roller 29 and the blade 48 face each other in the vicinity of the pressure contact area, so that more uniform coating can be achieved.

It goes without saying that the present invention is not limited to the five embodiments described above, but can be configured in many more configurations by combining various elements such as charging the developer, coating the developing roller, regulating the layer 7, etc. . Furthermore, since the present invention is well suited to non-magnetic component developers and has a non-contact structure with charge carriers, it is also advantageous for the formation of color images in which developers of multiple colors are layered and developed on charge carriers. be.

As described in detail, in the present invention, the voltage of the voltage applying means between the developer carrier and the charging means is applied at a voltage higher than a predetermined voltage when the voltage is applied, and the developer from the charging means is applied. By increasing the supply amount and applying a voltage at a predetermined voltage after voltage application to increase the ability to supply developer from the charging means, it is possible to eliminate image density reduction at the initial stage of development and after the initial stage of development. be able to. therefore,
High-quality development becomes possible.

[Brief explanation of the drawing]

1 is a sectional view of an image forming apparatus according to a first embodiment of the present invention, FIGS. 2 and 3 are configuration diagrams of each part of an image forming apparatus according to a first embodiment of the present invention, The figure is another cross-sectional view of the image forming apparatus according to the first embodiment of the present invention, FIG. 5 is a cross-sectional view of the image forming apparatus according to the second embodiment of the present invention, and FIG. 7 is a sectional view of an image forming apparatus in a fourth embodiment of the present invention; FIG. 8 is a sectional view of an image forming apparatus in a fifth embodiment of the present invention; 9 and 10 are sectional views of main parts of a conventional image forming apparatus, respectively. 22... Charge carrier, 28... Developer, 29...
Toner carrier, 30... Charging means, 46... Voltage applying means Agent's name Patent attorney Toshio Nakao Haka1 person n-Mitsube β-Henjin Publishing, '9-s Mika Roller Sword- Far Plan 33-Tosu-nlS:4-1Minor-5-II 36-Replenishment Opening A-Voltage Application Means Concave Thickness III + jMore 232 Fig. 6 Fig. 7 Fig. 8 Fig. 9

Claims (18)

[Claims] (1) A device for developing an electrostatic latent image on a charge carrier, which applies a voltage between a developer carrier, a means for charging the developer, and a means for charging the developer carrier. a voltage applying means for supplying the developer to the developer carrier, and applying a voltage of the voltage applying means to a predetermined voltage or higher when applying the voltage;
A developing device characterized in that a predetermined voltage is applied after the voltage is applied. (2) The charging means rotates the cylindrical elastic body to cause relative movement between the developer and the components of the developing device, and the friction between the developer and the components of the developing device causes the developer to 2. The developing device according to claim 1, wherein the developing device triboelectrically charges the developing device. (3) A patent that provides a layer thickness regulating means for regulating the developer on the developer carrying means to a predetermined layer thickness on the downstream side of the developer supply position from the charging means in the moving direction of the developer carrying means. A developing device according to claim 1. (4) The developing device according to claim 1, wherein the voltage applying means is a voltage obtained by superimposing a DC voltage on an AC voltage. (5) The developing device according to claim 2, further comprising a scraping plate that comes into sliding contact with the cylindrical elastic body, scrapes off excess developer on the elastic body, and makes the developer on the elastic body uniform. . (6) Claim 2, wherein the developer carrying means and the cylindrical elastic body are made of a conductive material and brought into contact with each other, and a detecting means for detecting the current value of the voltage applying means provided therebetween is provided. The developing device described. (7) The developer carrying means and the cylindrical elastic body are brought into contact, and at the contact position, the developer carrying means and the cylindrical elastic body are moved in the forward direction, and the peripheral speed of the cylindrical elastic body is adjusted to carry the developer. The developing device according to claim 2, wherein the developing device has a peripheral speed faster than the circumferential speed of the means. (8) The developer carrying means and the cylindrical elastic body are brought into contact with each other, and at the contact position, the developer carrying means and the cylindrical elastic body are moved in the forward direction, and the circumferential speed of the developer carrying means is controlled by the cylindrical elastic body. The developing device according to claim 2, wherein the developing device is faster than the circumferential speed of the body. (9) The developing device according to claim 2, wherein the cylindrical elastic body is a fur brush. (10) The developing device according to claim 2, wherein the cylindrical elastic body is a roller made of sponge. (11) The developing device according to claim 9, wherein the fur brush is conductive. (12) The developing device according to claim 10, wherein the roller made of sponge is electrically conductive. (13) The developing device according to claim 3, wherein the layer thickness regulating means is an elastic blade. (14) The developing device according to claim 3, wherein the layer thickness regulating means is a rigid blade. (15) One end of the blade is used as a fulcrum, and the other end is brought into pressure contact with the surface of the developer carrying means, and the fulcrum is caused to bite into the developer carrying means side by the frictional force received at the pressure contact portion when the developer carrying means moves. 15. The developing device according to claim 13 or 14, wherein the developing device is provided at a position where it acts and the pressure contact portion at the other end has a convex shape. (16) One end of the blade is used as a fulcrum, and the other end is brought into pressure contact with the surface of the developer carrying means, and the fulcrum is caused to escape from the surface of the developer carrying means by the frictional force received at the pressure contact portion when the developer carrying means moves. 15. The developing device according to claim 13 or 14, wherein the developing device is provided at a position where it acts and the pressure contact portion at the other end has a convex shape. (17) The developing device according to claim 1, wherein the developer on the developer carrying means and the charge carrier are not in contact with each other. (18) The developing device according to claim 1, further comprising means for applying a DC electric field between the developer carrying means and the charge carrier.