JPH02154280A - Developing device - Google Patents

Abstract

PURPOSE:To form a high-quality picture by providing ruggedness on the outer periphery and rocking an elastic roller for the supply of developer in the axial direction. CONSTITUTION:The elastic roller 30 which has ruggedness on its outer periphery and supplies a developer carrier 29 with the developer 28, is rocked in the axial direction. Therefore, the ruggedness on the surface of the elastic roller 30 accelerate the supply of the developer 28 to the developer carrier 29 and the supplied rugged developer on the developer carrier 29 is reduced by rocking the elastic roller 30 in the axial direction. Thereby, a layer thickness regulating means forms a developer layer in uniform thickness, and therefore a high-quality picture can thus be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a phantom image device in 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 dry developer are broadly divided into two types: methods using a two-component developer and methods using a one-component developer.

Since the method using a two-component developer uses a mixed developer of toner and carrier, a toner concentration control device is required to keep the mixing ratio of toner and carrier constant! However, it also has drawbacks such as the need for periodic replacement due to deterioration of the carrier. 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 (for example, US Pat. No. 4,083,326).

The conventional developing method using only this one-component developer is shown in FIG. 8, for example. In the figure, 13 is a developing roller, 14 is a toner, 15 is a hopper, 16 is a blade, 1
7 is a sheet-like photoreceptor; 18 and 19 are conductive fur brushes that come into sliding contact with the developing roller 13; 20 is a first power source that applies voltage between the hopper 15 and the conductive fur brush 18; and 21 is a conductive fur brush. This is a second power source that applies voltage between the fur brush 18 and the developing roller 13. Further, the voltage applied by the second power source 21 is configured to be higher than the voltage applied by the first power source 20 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 transferred to the hopper 1 due to the potential difference between the first power source 20 and the second power source 21.
5 to the developing roller 13 via the conductive fur brush 18, and then regulated by the blade 16, the 9th developing roller 13, which adheres to the electrostatic latent image of the phosphor 17 and develops it. The toner 14 on the developing roller 13 after standing is scraped off with one conductive fur brush.
18 history is removed.

Problems to be Solved by the Invention However, this type of system has the following problems.

That is, conventional fur brushes are thought to be made of electrostatic flocking or fabric. Of these, electrostatic flocking is effective in uniformly supplying toner, but has the problem of hair shedding.

For this reason, fur brushes made from woven fabric were used.

However, although woven fabrics do not have the problem of hair shedding, they are produced by winding woolen fabrics of a predetermined width on a shaft, so the seams of the woven fabrics are approximately 1.
A gap of 1.0 mm is generated, resulting in uneven toner supply. The reason for this is that when toner is supplied from the fur brush to the developing roller, the amount of toner supplied at the seam of the fur brush on the developing roller decreases, and the amount of toner supplied at areas other than the seam is significantly different. It becomes impossible to regulate uniformly. Therefore, it has been difficult to reproduce high-quality images.

In view of the above-mentioned conventional problems, the present invention provides a developing device that forms high-quality images.

Means for Solving the Problems The technical means of the present invention for solving the above problems are as follows:
an endless developer carrier; an elastic roller having an uneven surface at least on its outer peripheral surface for supplying developer to the developer carrier; and an elastic roller supplying developer in the direction of movement of the developer carrier. The device includes a layer thickness regulating means for regulating the developer on the developer carrier to a predetermined layer thickness on the downstream side of the position, and a means for swinging the elastic roller in the axial direction.

action The effect of this technical means is as follows.

In other words, the unevenness on the surface of the elastic roller increases the ability to supply the developer to the ring 1 agent carrier, and the unevenness in the supply of developer on the ring 1' agent carrier, which is not supplied, is reduced by using the elastic body. This can be reduced by swinging the roller in the axial direction.

Therefore, the layer thickness regulating means prevents the development RM on the developer carrier.
can be formed with a uniform layer thickness, making it possible to develop high-quality images.

Example An embodiment of the developing device of the present invention will be described below.

1 to 7 show examples in which the phenomenon apparatus of the present invention is used in an electrophotographic copying machine. In the first section, 22 is a charge holding body such as electrostatic recording paper or a photosensitive drum. In this embodiment, a photosensitive drum is used as the charge holding body 22,
This has a photoconductor 24 such as zinc oxide, selenium, or an organic photoconductive material supported on the surface of an aluminum base 23 (hereinafter, the charge carrier 22 will be referred to as a photosensitive drum 22). First DC high voltage power supply 2 with charger
6 according to the photoconductor 24 on the photosensitive drum 22,
For example, in the case of zinc oxide, a negative corona is applied, and in the case of 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. 28
The developer is a common one-component insulating toner. Note that the developer 28 may be a magnetic toner or a non-magnetic toner.
1 is a developing roller as a developer carrier, and for example, a metal roller made of stainless steel or aluminum, a roller whose surface is coated with sugar beet, etc. are used. Preferably, as shown in FIG. 2, the outer circumferential surfaces 29a and 29b at both ends of the developing roller 29 are made smooth, and the center surface 29c is made smooth.
is formed on a rough surface with minute irregularities. Also, the developing roller 2
are installed at a constant distance from the photosensitive drum 22,
For example, as shown in FIG. 1, it rotates counterclockwise. 3
0 is a fur brush serving as an elastic roller that supplies the developer 28 to the developing roller 29, and has an uneven portion on at least its outer peripheral surface. This uneven portion improves the ability to supply the developer 28 to the developer roller 29.

In this embodiment, the elastic material 32 is used as the elastic roller.
The fur brush 30 is made of conductive fur made of carbon-containing rayon fibers, but a sponge or the like may also be used as the elastic material 32.The fur brush 30 is surrounded by two bodies 33, and the developing roller 29
The developing roller 29 rotates clockwise, for example, at a circumferential speed higher than the circumferential speed of the developing roller 29 . By setting the circumferential speed of the fur brush 30 in this manner, the amount of developer 28 supplied to the developing roller 29 is increased by 1 hour, improving the followability of the coating, and also reducing the spillage of the developer 28. Furthermore, after the development process, the developer 28 adhering to the surface of the developing roller 29 can be scraped off to erase the history on 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. As shown in FIG. 4, reference numeral 34 denotes a swinging means for swinging the fur brush 30 in the axial direction, for example, using a piezoelectric element such as a bimorph or mechanical movement (MC8). 35 is a storage part formed in a part of the housing 33 to store the developer 1128 before development, and the developer 2 is stored at one end.
It has eight replenishment openings 37. Reference numeral 36 denotes a supply blade, and one end of a sheet-like elastic member 39 made of polyethylene terephthalate or the like having a thickness of approximately 30 to 80 μm is fixed to the outer peripheral surface of a mandrel 38, and the mandrel 38 is rotated to supply the developer 28. It is supplied to the brush 30. In this embodiment, the mandrel 38 is rotating clockwise. 40 is a partition plate provided between the fur brush 30 and the supply blade 36, and this partition plate 40 is provided with an opening 41 through which the developer 28 flows in and out between the fur brush 30 and the supply blade 36. ing. Further, this opening 41 is provided at a position where the developer 28 from the sheet-like elastic member 39 is supplied to the outer circumference of the fur brush 30 in a tangential direction. By supplying the developer 28 in the tangential direction in this manner, the developer 28 does not become clogged in the fur brush 30.
is a scraping plate formed from a part of the casing 33, which makes sliding contact with the fur brush 30, makes the amount of developer 28 in the fur brush 30 uniform, and removes overcharged developer in the fur brush 30. This is to scrape off the agent 28. 43 is the base of the supply opening 37, and 44 is a developer reservoir provided on the fur brush 30 between the developer roller 29 and the supply blade 36. This developer reservoir 44 has a capacity that can supply a predetermined amount of developer 28 to the fur brush 30. Furthermore, a gap δ is provided between the end 44^ of the developer reservoir 44 on the side of the developing roller 29 and the outer peripheral surface of the fur brush 30, as shown in FIG.
The aperture t is smaller than '3λ. With this condition, the developer 28 supplied by the sheet-like elastic member 39 is divided into two parts, the storage section 35 and the developer reservoir 44, and is no longer directly supplied to the developing roller 29 via the gap δ.

In addition, the gap δ is 0.5 to 3++m, and the opening width λ is 4
Good supply performance was obtained at ~8Il1m. As shown in FIG. 2, 45 is a bearing for the developing roller 29, and 46 is a bearing for the fur brush 30. Reference numeral 47 denotes a layer thickness regulating means for regulating the layer thickness of the developer 28. In this embodiment, a plate-shaped elastic blade made of urethane rubber is used, but other rubber materials, polyethylene terephthalate, etc. may be used as the elastic blade material. It may be made of elastic synthetic resin, elastic metal such as phosphor bronze, or spring steel, or it may be made of elastic metal or synthetic resin coated with fluororesin. Also, the accuracy of the end surface of the elastic blade 47 and the installation are subject to change. The position and method are such that the straightness of the edge 47^ of the elastic blade 47, which has a great influence on the formation of a uniform thin layer of the developer 28, is precisely finished to 0-15 mm or less, and the mounting position is the developer roller. 29
As shown in FIG. The edge 47A side of the edge 47A is pressed against the developing roller 29, and at least the flat surface 47B of the shaded area on the other end side is attached to a mounting member 63 provided on the casing 33 using, for example, a hot melt adhesive that can be bonded uniformly in a short time. It is done by gluing. Further, the adhesive surface end 47C on the side of the developing roller 29 is provided substantially parallel to the rotational axis X of the developing roller 29.

Reference numerals 64A and 64B are adjustment screws which are pressure adjustment mechanisms and are used to adjust the pressure of the elastic blade 47 against the developing roller 29 to a predetermined value. The pressure adjustment is done by the mounting member 63.
yJ wood-setting screw 64A64 installed between and the housing 33
B to the specified blade pressure, N M He, fixing screw 65
A.

65B fixes the mounting member 63 to the housing 33. Further, the width of the elastic blade 47 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 the second section and in FIG.

48 and 49 are outer circumferential surfaces 29a and 2 at both ends of the developing roller 29;
A first sealing material that surrounds 9b and blocks the developer 28 moving to both ends thereof, and is made of, for example, textile fabric or nonwoven fabric (felt).
It is made of elastic materials such as sponge, rubber, etc.

50 and 51 are the developing roller 29 and the first sealing material 48.4
9 and the elastic blade 47.
A sealing material made of an elastic material such as sponge or rubber. 52.53 is developer 2 moving to both ends
For example, 70~1 with an elastic sheet to further block 8
It is made of an elastic material such as 50 μm polyethylene terephthalate or metal. Further, the elastic sheets 52 and 53 have one end attached to the first sealing material 48° 49, and the other end attached to the blade edge 47 with respect to the rotational direction of the developing roller 29.
It protrudes downstream from A and is provided between the two developing rollers and the second sealing material 50,51.

Elastic blades 47 and 54 and 55 are connected to the developing roller 29.
The elastic blade 47 is a presser plate spring that improves the adhesion of the elastic blade 47.
The second sealing material 50.51 and the elastic sheet 52.
53 is pressed.

56 is a means for preventing the developer 28 from spilling;
2 developing rollers and 3 fur brushes in the moving direction of 0
0 and below the developing roller 29. Further, the spill prevention means 56 is composed of a U-shaped leak prevention member 57 and a leak prevention sheet 58 whose one end is fixed to the leak prevention member 57 and the other end is in light contact with the surface of the developing roller 29. Note that one end of the leak prevention sheet 58 of the spill prevention means 56 may be provided on the casing 33, and the width of the leak prevention sheet 58 is set to a length such that it comes into contact with the outer circumferential surfaces 29a and 29b at both ends of the developing roller 29. , and both ends thereof are pressed against the developing roller 29 by sealing materials 48 and 49 provided at both ends of the developing roller 29, as shown in FIG. Furthermore, the end of the leak prevention sheet 58 on the side that lightly contacts the surface of the developing roller 29 is located on the upstream side of the line connecting the two developing rollers and the center 3 of the fur brush 30 with respect to the rotating direction of the fur brush 30. and fur brush 30
It is held between. Further, the leak prevention sheet 58 is made of an elastic material such as polyethylene terephthalate or urethane rubber, and in this embodiment, urethane rubber with good adhesion to the developing roller 29 (the thickness at this time is preferably about 50 to 200 μm) is used. ing. The leak prevention member 57 is made of metal such as stainless steel or aluminum, and even if the developer 28 leaks from the gap between the developing roller 29 and the leak prevention sheet 58, the receiver stops the developer from falling downward. In this case, since the leakage of the developer 28 is almost completely stopped by the leakage prevention sheet 58, the capacity of the leakage prevention member 57 may be small.

60 shown in the first section is a second DC high-voltage power supply for applying a voltage, which applies a voltage between the developing roller 29 and the fur brush 30 to charge the developer 28 on the surface of the developing roller 29. The layer thickness y! It is used to make four adjustments.

Further, although the applying means 60 uses a DC bias voltage in this embodiment, the voltage is DC! A combination of Act pressure and Act pressure can also be used. A detection means 61 detects the current value of the second DC high voltage power supply 60 and detects the presence or absence of the developer 28.

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 ΩC1 or less, preferably 103 ΩCI1 to 107 ΩcI.
It is better to use 11 conductive materials.

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 elastic roller 30.

The operation of the developing device of this embodiment configured as described above will be explained. Here, to make the operation easier to understand, the photoconductor 24 on the photosensitive drum 22 is made of zinc oxide, and the cylindrical elastic body 30 is made of an elastic material 3 on an aluminum core 31.
2 is a fur brush in which about 3,600 rayon fibers containing carbon and a specific resistance of about 105ΩC1 are flocked/Cm2, and the surface roughness of the developing roller 29 is 5 μm Rwax
, the linear pressure of the elastic blade 47 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*+a, and the developer 28 is a normal positively charged non-magnetic one-component toner. The following describes the contents of the experiment conducted using this method.

In FIG. 1, the charger 25 is connected to a first high-voltage DC power source 26.
A high voltage of approximately -6 kV is applied to the photosensitive drum 22 to negatively charge the entire surface of the photosensitive drum 22 to approximately -600V using a negative corona.The photosensitive drum 22, which is negatively charged in the 0th order, is irradiated with a halogen lamp or the like by the optical section 27 to reflect the original. When the image (pattern light image) is projected, the portion corresponding to the non-image portion of the document on the photosensitive drum 22 is neutralized by the reflected light to a residual potential close to OV, forming a positive electrostatic latent image.

During this time, the developer 28 in the storage section 35 is uniformly supplied to the developer reservoir 44 through the opening 41 by the sheet-like elastic member 39. The uniformly supplied developer 29 is supplied into the fur brush 30. be done. During this supply, since the gap δ is smaller than the opening width λ of the opening 41, the developing roller 2
The uncharged developer 28 does not adhere to the surface of the developer 9.

Next, the excess phenomenon agent 28 in the fur brush 30 is scraped off by a scraping plate 42 and an appropriate amount is supplied, and the zero-order fur brush 30 is positively charged due to friction with the scraping plate 42 and the housing 33. An electric field is generated between the developing roller 29 and the fur brush 30 by the charged developer 28 inside, and the charged developer 28 coats the surface of the developing roller 29. Also, at this time, by swinging the fur brush 30 in the axial direction, the developer 28 is removed by the winding seam of the fur brush 30.
supply unevenness is reduced.

Further, a voltage of about 0 to 250 V is applied from the second DC high voltage power supply 60 to adjust the layer thickness, and by applying this voltage, when the developer 28 is transferred from the fur brush 30 to the developing roller 29, For example, even if some of the developer 28 is uncharged or charged with the opposite sign, the uncharged developer 28 or the developer 28 charged with the opposite sign is not transported.
, only the normally charged developer 28 is selected and contributes to development.

Therefore, the developing roller 29 is coated with the developer 28 that is uniformly charged and has less uneven supply, and a high-quality image can be obtained. Here, the layer thickness of the developer 28 on the coated surface of the developing roller 29 is greater 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 an elastic blade 47, where part of it is scraped off to a predetermined layer thickness, that is, about 40 μm (at this time). Layer thickness is 10~
(preferably about 70 μm). The end face of the elastic blade 17 is finished with a straightness of 0.15 mm or less, and as shown in FIG. 47B, the developer 2 on the developer roller 29 is pressed against the developer roller 29.
The layer thickness and charge amount of No. 8 become uniform. Also, the developing roller 2
The linear pressure of the elastic blade 47 in the axial direction of the elastic blade 47 can be kept constant by bonding the flat surface 47B of the elastic blade 47 on the pressure contact side to the mounting member 63 as shown in FIG. Furthermore, the elastic blade 4 is adjusted using adjustment screws 64A and 64B.
Since the linear pressure 7 can be finely adjusted, the layer thickness and charge amount of the developer 28 become more uniform. As a result, a high-quality image without density unevenness can be obtained.

Next, the position of the elastic blade 47 will be explained in more detail based on FIG. 6. Developing roller 29 and elastic blade 4
The surface 47B including at least the downstream edge 47A of the elastic blade 47 is a nip surface that occurs when the edge 47A of the elastic blade 47 does not come into contact with the surface of the developing roller 29, as shown in FIG. is located.

Next, the developer 28 that has come into contact with the elastic blade 47 falls onto the fur brush 30 while moving from the center of the developing roller 29 toward both ends. By rotating the spiral fur brush 30, the fur brush 30 moves from both ends to the center. 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 35 is kept constant.

Furthermore, the first sealing material 48, 49 and the second sealing material 5
0.51 and the elastic sheets 52 and 53 surround the outer circumferential surfaces 29a and 29b at both ends of the developing roller, so there is no scattering or leakage of the developer 28 moving to both ends of the developing roller 29. This developing device is capable of uniformly charging the developer 28 on the developing roller 29 and making the layer thickness uniform.Furthermore, the developer 28 is free from scattering or leaking, and is high quality with no fogging or density unevenness. You can get a good image.

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 is blown away by the electrostatic force of the electrostatic latent image on the photosensitive drum 22. The latent image can then be developed. The surplus developer 28 that has not been used for the development is carried further downstream while remaining attached to the developing roller 29 and passes through the leak prevention sheet 58. At this time, the leak prevention sheet 58 is attached to the developing roller 29. Because of the rolling contact, the developer 28 is transported directly into the housing 33 by electrostatic adhesion, and once it passes through the leak prevention sheet 58, it will not leak out again.

The developer 28 adhering to the surface of the developing roller 29 is scraped off by the fur brush 30 to erase it from the history of the developing roller 29. Therefore, a high-quality image without ghosts can be obtained.

The developer 28 scraped off by the fur brush 30 is transported by the fur brush 30, and then scraped off by the scraping plate 42 and returned to the storage section 35 through the opening 41.
The developer 28 on the developer roller 29 is not overcharged, thus enabling high quality image development.

In this developing state, an appropriate amount of developer 2 is in the fur brush 30.
8, so the fur brush 30 and the developing roller 29
Since the contact resistance is high, the current value of the detection means 61 is small.The zero-order development process is repeated, and when the developer 28 in the storage section 35 and the developer 28 in the fur brush 30 run out,
The contact resistance described above becomes lower and the current value of the detection means 61 becomes larger. Therefore, the presence or absence of the developer 28 in the storage section 35 can be detected based on the current value of the detection means 61. Furthermore, even if the amount of developer 29 decreases, the sheet-like elastic part 'N39 rotates clockwise and is displaced as shown in FIG. It can be fed into the fur brush 30. Therefore, even if the bottom surface of the storage section 35 is made horizontal, the developer 28 in the storage section 35 can be supplied to the fur brush 30 up to if& without any problem. Furthermore, since the developer 28 is stirred within the storage section 35 by a sheet-like elastic member 39, there is an effect that the height of the developer 28 within the storage section 35 is kept constant.

Note that since the circumferential speeds of the developing roller 29 and the photosensitive drum 22 are the same, it is possible to eliminate edge effects when developing a latent image.

This developing device improves the supply of developer to the developer carrier with the uneven portions on the surface of the elastic roller, and eliminates uneven supply of the developer on the developer carrier. By being reduced by swinging in the axial direction, it is possible to form a uniform layer thickness of the developer on the developer carrier by the layer thickness regulating means. Therefore, high-quality development is possible. Further, since one fur brush can supply the developer to the developing roller and scrape off the developer on the developing roller after development, the configuration can be simplified and the device can be made smaller. In addition, restrictions on the arrangement of the slick developing device, which is configured to prevent developer from leaking or scattering, can be expanded.

In this example, the regular expression (
We have explained an example of experimenting with m (positive-positive development), but inverse development @ (negative
It goes without saying that the present invention is also applicable to positive development (positive development), and the present invention is not limited to this embodiment, but also includes the supply of developer to the developer reservoir, charging of developer, coating on the developing roller, regulation of layer thickness, etc. , it goes without saying that many more configurations are possible by combining each element.Furthermore, the present invention is well suited to non-magnetic-component developers,
Furthermore, by configuring the charge carrier and the developer carrier to be in non-contact manner, it is also possible to form a color image by superimposing developers of a plurality of colors on the charge carrier.

As described in detail, in the present invention, the uneven portions on the surface of the elastic roller improve the supply of the developer to the developer carrier, and the unevenness of the developer on the supplied developer carrier is improved. Supply unevenness is reduced by swinging the elastic roller in the axial direction.
Next, the layer thickness regulating means allows the developer layer on the developer carrier to be formed with a uniform layer thickness, and as a result, high-quality image development becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of essential parts of a developing device according to an embodiment of the present invention, FIG. 2 is a perspective view showing the structure of the swinging means 34, etc. of a fur brush 30 in the same embodiment, and FIG. 3 is a sectional view of the fur brush 30 in the same embodiment. A perspective view of a single unit, FIG. 4 is a case 33 in an example of a dynamic bag.
5 and 6 are enlarged cross-sectional views showing the vicinity of the developing roller 29 and elastic roller 30 in the same embodiment, and FIG. 7 is a cross-sectional view of essential parts of the developing device in the same embodiment. FIG. 8 is a sectional view of a main part of a modern device using a conventional one-component developer. 28...Developer, 29...Developer roller (developer carrier) 30...Fur brush (elastic roller), 34...
... Swinging means, 47... Layer thickness regulating means. Name of agent Patent attorney Shigetaka Awano No. 2 Figure 34-°-Kanko Sθ, i81 No. 1 IP-Collar 230
--Fur brush (bullet 8I wood roller) 47-eyebrow thickness ■
Child actor 44 figure ζ°56 figure 7A, 30 Ka8 figure/7

Claims (1)

[Claims] An endless developer carrier, an elastic roller having an uneven portion on at least the outer peripheral surface and supplying developer to the developer carrier, and a developer on the elastic roller in the moving direction of the developer carrier. A developing device comprising: a layer thickness regulating means for regulating a developer on a developer carrier to a predetermined layer thickness downstream from a supply position; and a means for swinging the elastic roller in an axial direction.