JPS60147755A - Developing device - Google Patents

Abstract

PURPOSE:To reduce a developing device at its size by providing the device with a developer carrying body for carrying a developer to an image formation surface to develop the surface and plural developer feeding means for feeding plural developers to the developer carrying body. CONSTITUTION:A prescribed developer corresponding to each filter is fed from the developing device 20 to a toner image carrier 1 on which an electrostatic latent image is formed. The 1st sleeve 30 carries toner particles from respective feeding units 31-33 selectively to the image carrier 1, so that the toner particles are successively moved and adsorbed to the toner image carrier 1 by the electric force of the electrostatic latent image and the toner image of the prescribed pattern is formed and developed. Since plural feeding means for feeding plural developers to the developer carrier are arranged, the developing device can be reduced in size and the occupied area can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Industrial Application Field The present invention relates to a developing device, for example, a developing device suitable for electrophotographic copying machines, electrostatic recording devices, and the like.

2. Prior Art For example, in a scanning exposure type electrophotographic copying machine, when a copying original is placed on the original platen and a copy button is pressed, an exposure lamp illuminates the original while an optical system including a reflecting mirror etc. Drive in the direction. Reflected light corresponding to the density of the original is irradiated onto a uniformly charged toner image carrier (for example, a photosensitive drum) via the optical system, and an electrostatic latent image is formed on the toner image carrier. Ru. Further, a toner image corresponding to the density of the document on the photoreceptor drum is formed by the developer. On the other hand, a recording medium (for example, copy paper) is fed from the paper feeding device so as to match the position of the toner image on the toner image carrier, and comes into contact with the toner image carrier. Then, the toner image formed on the surface of the toner image carrier is transferred onto copy paper by the transfer electrode. During this time, the toner image carrier continues to rotate in a predetermined direction, and the toner image is gradually transferred onto the copy paper. Thereafter, the copy paper onto which the toner image has been transferred is separated from the toner image carrier, and the copy paper is sent to a roller fixing device. The roller fixing device includes two rollers, at least one of which is a heated roller, and heats and fixes an image formed by a developer onto copy paper. Thereafter, the copy paper is discharged out of the main body of the copying machine. After the visible toner image is transferred to copy paper, the toner image carrier is cleaned to remove excess toner powder, and this process is repeated every time recording is performed.

Although these copying machines produce monochromatic images, a color copying machine as shown in FIG. 1 has also been proposed which produces color copies.

The color copying machine shown in FIG. 1 is not so different in principle from a monochromatic copying machine. In the case of a monochromatic copying machine, an exposure lamp illuminates the original, and reflected light corresponding to the density of the original is irradiated onto the toner image carrier through an optical system including a reflecting mirror, and the light is reflected onto the toner image carrier. However, in the case of a color copying machine, a filter is installed to separate the light reflected from the document and extract a single color of light, and only the light that passes through the filter is used to carry the toner image. Irradiate the body. The color copying machine shown in No. 1 and 1 is equipped with a filter bag 2 that contains three types of filters of different colors. It will be done.

For example, first color separation is performed using a green filter, an electrostatic latent image is formed on the toner image carrier by the exposure device 12 using light passing through this filter, and a developing device containing magenta toner is stored in the developing device 3. Develop with container 3B. here,
A visible image is formed on the toner image carrier 1 using magenta toner. This visible image is conveyed from the paper feed box 8,
The image is transferred onto copy paper 7 wrapped around transfer drum 4 by transfer pole 10 .

After the toner image bearing member 1 is transferred, the charge is removed by the removing electrode 11, excess toner powder is removed by the cleaning device 5, and then the charge is charged again by the charging electrode 9. This time, image exposure is performed by the light passing through the blue filter, and development is performed by the developing device 3A containing yellow toner, and a visible yellow image is formed on the toner image carrier 1. The visible image is transferred to copy paper 7 in the process described above. Next, image exposure is performed by the light passing through the red filter, and a cyan visible image is formed on the toner image carrier 1 by the developing device 5 containing cyan toner. The image is also transferred to copy paper 7. The copy paper 7 is wound around the transfer drum 1 until the transfer of visible images of all colors is completed, and after the transfer is completed, the copy paper 7 is sent to the fixing device 6, and after being fixed, it is discharged outside the machine.

In other words, this color copying machine separates the reflected light from the original using a filter to extract a single color of light, and then converts the electrostatic latent image formed by this single, dark-colored light into the color of that light. It is developed by a developing device containing toner colored in a color corresponding to the image, and then transferred onto copy paper.
We are making color copies□.

Although this color copying machine can perform color copying, it has the following problems.

(11. In order to copy to a certain extent natural colors on copy paper, a minimum of three developing units are required for the three complexions, and if black is prepared, the number becomes four, and in addition, four transfer drums are required. Due to their roles, the developing device and the transfer drum 4 must be installed on the circumferential surface of the toner image carrier 1. Therefore, the toner image carrier l of a color copying machine must be A space is required for arranging them near the circumferential surface of the photoreceptor 1, and the photoreceptor 1 of a color copying machine must necessarily be considerably larger than that of a monochromatic copying machine.

For this reason, it requires a large area in an office or other installation location, and is inevitably expensive due to the cost of materials. Mainly due to these two reasons, consumers are losing their desire to purchase color copying machines.

(2) Since the developing positions of the developing units 3A to 3C are different from each other, the developing conditions are likely to vary and change due to the influence of a decrease in the potential of the photoreceptor.

(3) While developing with a certain developer, it is necessary to hold another developing device in a non-contact state with respect to the photoreceptor, and a moving mechanism for this purpose is required.

(4) When copying in a single color other than the color of the developer, it is necessary to sequentially overlay the colored toner of each developer on the copy paper on the transfer roll (4 in Figure 1), but the timing of overlapping is must be taken, and misalignment is likely to occur.

3. OBJECTS OF THE INVENTION It is an object of the present invention to provide a developing device which is small in size, occupies a small area, and which is affected by changes in the potential of an image carrier and which facilitates image pulling operations and the like.

4. Structure of the Invention In other words, the present invention includes a developer transporting member (for example, a first sleeve described below) that transports developer to an image forming surface to perform development, and a plurality of developers on this developer 11i transporting member. This relates to a developing device characterized in that it has a plurality of developer supply means (for example, three second sleeves described later) that respectively supply the developer.

5. Examples Hereinafter, the present invention will be explained in detail with reference to examples shown in the drawings.

FIG. 2 schematically shows an electrophotographic copying machine based on an embodiment of the present invention.

In this copying machine, an original 16 covered with a platen cover 15 is placed on the glass surface of an original placing table 14 movably provided on the upper wall of the main body. Light 18 from a light source 17 is irradiated onto a document 16 through a slit 9 provided on the upper wall of the main body, and the reflected light is reflected by a light focusing element (trade name: CellHoc Lens Array) 1.
3 and a filter 12', the toner image carrier 1 is made of a photoreceptor drum. Therefore, when the original table 14 moves in the direction of the arrow, the photosensitive layer made of selenium, an organic photoconductive substance, etc. on the circumferential surface of the toner image carrier l is uniformly charged by the charger 9. Image exposure is performed sequentially through a filter in a pattern corresponding to the original image, and an electrostatic latent image is formed. A predetermined developer corresponding to the filter is supplied from the developing device 20 to the toner image carrier 1 on which the electrostatic latent image is formed. As will be described in detail later, this developing device 20 includes a first sleeve 30 disposed facing the image forming surface of the image carrier 1, and three developer supply devices disposed around the first sleeve 30. 31.32
．． 33, and each feeder has second sleeves 34, 35, and 36 built therein facing the first sleeve 3o. The first sleeve 30 also includes a cleaning device 3.
7 are placed opposite each other. The first sleeve 30 serves to selectively convey the toner particles from the respective feeders 31, 32, 33 onto the image carrier l, whereby the toner particles are sequentially transferred to the toner image carrier by the electric force of the electrostatic latent image. It moves onto the body 1 and is attracted to it, and an image of a predetermined batonin is formed thereon, and development is performed.

This process is repeated at least three times when forming a color image.

After the toner image thus formed is re-charged to match the toner polarity, it is conveyed from the paper feeder 21 by the paper feed roller 22 and is moved by the timing roller 23 so that it matches the image area on the toner image carrier l. The image is transferred onto the fed copy paper 24 by the transfer pole 25. The toner image on the toner image carrier l is separated from the transfer l, and the fixing device 27
sent to. At least one heated fixing roller 27A, 27B is provided in the fixing device 27, and the copy paper 24 is heated while passing between both rollers, and the toner image is fixed on the copy paper 24. After fixing, the transfer paper 24 is discharged onto the paper discharge tray 28 by the single feed roller 27C. On the other hand, the toner image carrier l, which has transferred the toner image onto the copy paper 24, continues to rotate in the direction of the arrow, and after being neutralized by the static eliminator 50, which was kept inactive during color image formation,
The toner adhering to the toner image carrier is removed by a cleaning blade 29A provided in the cleaning device 29, which is kept non-contact during color image formation. Then, again, the toner image carrier I and the charging electrode 9
The paper is charged with electricity, and the next copying process is carried out.

This copying machine repeats the above operations.

Of course, the developing device of the present invention can be used in a copying machine as shown in FIG. Also, regarding the transfer fixing method, EF
Any known method can be used, such as using paper, using an adhesive transfer method, or using a pressure fixing method.

The wax copying machine of this example is characterized in that the developing device 20 is constructed as shown in an enlarged view in FIG.

That is, the developing device 20 has a first developing device facing the photosensitive drum 1.
Developers are selectively supplied onto the sleeve 30 from respective supply devices 31 (for example, for yellow), 32 (for example, for magenta), and 33 (for example, for cyan) of -component or two-component developers. Inside each feeder is a rotating magnet 38.
．． 2nd sleeve 34.35.36 with built-in 39.40
;Developer thickness regulation plate 4142.43;Toner scraping blade 44.45.46;Toner supply screen: L-47
, 48, 49; Stirring plates 51, 52, 53 are arranged. Additionally, toner scraping blades 54, 55, 56, brushes or rollers 54', 55', 56', which are brought into selective contact with the first sleeve 30 and collect toner into each supply device during use, and brushes or rollers 54', 55', 56' , scraping #1i54”, s
s:56 is provided so as to be retractable. 1st sleeve 3
Also included is a brush or roller 57 and a scraping plate 57.
A cleaning device 37 having a cleaning member consisting of a combination of a blade 58 and a recovered toner conveying screw 59 is retractably provided. Instead of a toner collection device provided in each developing device, a cleaning device 37 can be provided for each toner. It is desirable that the cleaning device at this time has a recycling device. Further, the setting position may be set between each developing unit, but is not limited thereto, and may be set all at one place. Since three to four second sleeves are arranged relative to the first sleeve, the developer is likely to spill.

Therefore, in order to reliably collect the developer from the first sleeve into the developing device or the cleaning device, the brush or roller is preferably released and its operation is stopped later than the blade is released.

In this developing device 20, the first sleeve 3
0 to AC power supply 60 (e.g. 4KV or less, 5011z ~
50 K Ilz) and a DC power supply 61 (e.g. 500
A developing bias is applied between the photoreceptor drum 1 and the photoreceptor drum 1. At this time, the first sleeve 30 and the photoreceptor drum 1 are arranged at a certain interval (for example, 2000 μm or less), and the electrostatic latent particles formed on the photoreceptor drum 1 are sequentially formed on the photoreceptor drum 1 from the first sleeve 30 in a non-contact manner. Toner images are sequentially formed (or superimposed) on the image. Each second sleeve 34, 35, 36 has a DC power supply 62, 63, 64 (
(for example, 500 volts or less) are connected to each other, thereby transferring developer (specifically toner) particles from the second sleeve to the first sleeve in a charge-controlled manner. Here, it is preferable that the layer thickness of the developer on the second sleeve be made thinner than the gap between the first sleeve and the second sleeve. This is because it is transferred onto the first sleeve upon contact.

If the operation is performed in a contact manner (i.e., the state in which the developer on the second sleeve is in contact with the first sleeve), charge will easily leak through the first sleeve, making it difficult to control the charge on the developer. The non-contact method of toner transfer reduces the undesirable polarity of toner particles (especially the negative polarity component that occurs when positively charged in a negative component system), thereby preventing fogging and image roughness caused by development. It can be eliminated.

Further, there is an advantage that the layer thickness of the developer on the first sleeve 30 can be easily made thinner than the distance between the first sleeve 30 and the photoreceptor drum l. As a result, the developer layer is uniformly formed on the first sleeve, and it is possible to employ a developing method in which the developer layer is sequentially developed while being in contact with the surface of the photoreceptor drum L, so there is no fog and a sufficient density is obtained. development is possible.

As explained above, in the developing device according to this example, the developer supply device 31 for each color is arranged around the common first sleeve 30.
．． 32 and 33 are arranged, and each of these is selectively operated to supply developer onto the first sleeve 30 for development, so compared to the conventional developing device shown in FIG. The area occupied by the developing section around the photosensitive drum 1 can be significantly reduced, and a compact device can be provided. .

Furthermore, since the development of each color can be performed at the same position after each image formation, the influence of potential changes on the photoreceptor drum 1 becomes equivalent during the development of each color, thus preventing changes in each development condition due to fluctuations in the photoreceptor. I can do it.

Also, during development, only a specific developer is applied to the photoreceptor drum.
Therefore, as with conventional color developing devices, other developing devices should be placed in a non-contact state with the photosensitive drum 1, or the developer layer should not be fed by the cutting plate. There is no consideration of such things.

Furthermore, when performing monochrome image overlapping, after image formation, development is performed with the first sleeve 30, and then image formation is performed again.
By carrying out development, toner images are superimposed on the photoreceptor drum 1, and this can be transferred onto the transfer paper all at once.

As described above, according to the apparatus shown in FIG. 2, there is no need to perform color overlapping using the transfer drum 4 as in the conventional apparatus shown in FIG.

In addition, in Fig. 3, a supply device for black toner is also shown (
If added (as a fourth to the above three feeders), this additional feeder can be used to obtain a black image.

Further, instead of the above-mentioned supply system using the supply devices 31 to 33, it is also possible to supply the developer of each color onto the first sleeve 3o using a nozzle, a fur brush (all not shown), etc. Although this was done in a non-contact manner, other known non-contact methods or an air brush method may be employed.

FIG. 4 shows an example in which magnetic force is used to convey the developer on the first sleeve 3o and is also used as a developing bias. In this case, a rotating magnet 65 is disposed inside the first sleeve 3o, and toner (especially magnetic toner) is conveyed by the rotation of both of them.

Next, this example will be explained in more detail.

As a carrier, fine ferrite particles are dispersed in the resin at 50% by weight based on the resin content, and the average particle size is 30 μm and the magnetization is 3.
0 emn / g and resistivity of 100 cm or more, made of magnetic particles that have been subjected to thermal spheroidization treatment.
As a toner, 100 parts by weight of styrene-acrylic resin (Himer UP 110 manufactured by Sanyo Chemical Co., Ltd.), yellow,
Non-magnetic particles with an average particle size of 10 pm, which were obtained by a pulverization granulation method and were made of 10 parts by weight of a magenta or cyan pigment and a small amount of a charge control agent, were used. Using the apparatus shown in FIG. 3, development was carried out under conditions such that the toner particle ratio of the developer to the carrier particles in the developer supply device was 20 wt %.

The pigments in each developer are yellow, magenta, and cyan pigments, and the average charge amount of the toner in each developer is approximately 15
It was μC/g.

In this case, the image carrier l is an amorphous silicon photoreceptor,
Its circumferential speed was 180 n+m/sec, image exposure was performed through a blue filter, the highest potential of the electrostatic image formed on the image carrier L was -500 V, and the outer diameter of the first sleeve 30 was 40 mm.
, the rotation speed is 85 rpm, the gap between the image carrier and the first sleeve is 0.3IIl111, the outer diameter of the second sleeves 34 to 36 is 30 mm%, the rotation speed is 10 Orpm, the magnet bodies 38 to 4
The magnetic flux density of the 0.65, N, and S magnetic poles is 900 Gauss, the rotation speed is 11000 rpm, and the thickness of the developer layer is 0.65. '5m
m, gap between the first sleeve and the second sleeve 0.7 mm
(i.e. 700 μm), the thickness of the donor layer on the first sleeve is 30ttm, and the bias voltage applied to the first sleeve has a DC voltage component of -250μ and an AC voltage component of 1.5Ktlz.
, 500 V, and the bias voltage applied to the second sleeve containing the yellow toner had a DC component of +600 V. That is, in this case, the toner layer on the first sleeve does not come into contact with the surface of the image carrier 1 or the developer layer on the second sleeve.

Development using yellow toner was carried out under the above conditions.

To the other second sleeves, in order to prevent toner from adhering to the first sleeve, the same bias as that of the first sleeve was applied, a negative direct current component greater than -250V was applied, or the sleeves were kept in a floating state. Alternatively, the developer may not be conveyed onto the second sleeve, or the second sleeve may be moved farther from the first sleeve. Of course, developing devices that are not used for development do not need to be driven.

The toner after development was sequentially collected into the developing device by a cleaning member, and new toner was always supplied onto the first sleeve. At this time, other members of the developing device are released so as not to contact the first sleeve.

Example 1 Even after the development of odor yellow was completed, the first sleeve and the developing device were operated while the toner was collected from the first sleeve into the developing device. At this time, the first sleeve is applied with a bias of the same polarity as the toner polarity, or held in a floating state, or a bias of a polarity different from that of the toner is applied to the second sleeve that was supplying the toner. It is desirable to completely remove toner from the first sleeve by holding it in the proboscis state. It may be removed using the cleaning device 37.

Next, after being charged, imagewise exposure was performed through a green filter to form an electrostatic image in the same manner and developed.

For development, the second sleeve containing magenta toner is transferred from the first sleeve to the second sleeve containing magenta toner.
The toner was transferred to the sleeve under similar transfer conditions, and development was performed under similar development conditions.

At this time, only the cleaning member installed in the developing device containing magenta toner was in contact with the first roller.

After removing the toner from above the first sleeve in the same manner as above,
Next, after being charged, imagewise exposure was performed through a red filter to form an electrostatic image, which was developed with cyan toner.

After development, the toner was removed from the first sleeve in the same manner as above.

After forming a three-color toner image on the drum under the above conditions, a corona charger charged the toner and transferred it to plain paper using a corona transfer device, resulting in a clear color image. .

Toner remaining on the photoreceptor drum can be removed using a static eliminator 5 as necessary.
After the static electricity was removed using 0, the cleaning device 29 removed the static electricity.

The static eliminator and cleaning device were not operated during toner image formation.

Note that in Example 2 (same as Example 1), if the toner contains a magnetic substance, a magnet disposed inside the first sleeve as shown in FIG. 4 can be used for conveyance or as a developing bias. Of course, it may also be carried out using an apparatus as shown in FIG.

Using a single-component magnetic developer, toner was transferred from the second sleeve onto the first sleeve using the apparatus shown in FIG. 1st
A vibration bias similar to that in Example 1 was applied to the sleeve to perform development. Since the toner contained a magnetic substance, the magnet in the first sleeve was effective for conveying the toner and as a developing bias.

The toner after development was collected in a sequential light developer, and fresh toner was always supplied onto the first sleeve.

This step was carried out for each developing device, and the toner image was superimposed on the image carrier. Of course, the apparatus shown in FIG. 3 may also be used.

As carrier particles, the average particle size is 20 μm and the magnetization is 50 μm.
Using resin-coated spherical ferrite particles with a resistivity of elIln/g and a resistivity of 100 cm or more, and using non-magnetic color particles with an average particle size of 5 mm as toner particles, the developer supplying device was used with the apparatus shown in FIG. Development was carried out under conditions such that the ratio of toner particles in the developer was 10i1t% relative to the carrier particles. The average charge amount of toner is 30μ
C/g.

In this case, the conditions of the image carrier 1 and the first sleeve are the same as in Example 1, and the outer diameter of the second sleeve is also 30 mm, however, the rotation speed is 150 rpm, and the magnetic flux density of the magnetic pole facing the second sleeve of the magnet body. is 1200 Gauss, developer layer thickness is 0
．． 5mm, the gap between the first sleeve and the second sleeve is 0.
7 mm (i.e. 700 um), the thickness of the toner layer on the first sleeve is 40 μm, and the bias voltage applied to the first sleeve is a DC voltage component of -200V and an AC voltage component of 2KH.
The bias voltages applied to the second sleeves for yellow and magenta were 1500 V with a DC component of +100 V and an AC component of 3.5 KHz. In this example, the toner layer on the first sleeve does not contact the image carrier surface and the second sleeve surface.

With this configuration, a single layer of red toner was formed on the first sleeve.

In this example, only the toner is transferred from the two-component developer on the second sleeve onto the first sleeve, but the same process can be performed with a -component developer. At this time, toner is simultaneously transferred from the second sleeve of the developing device containing yellow and magenta toner to the first sleeve, and the toner is superimposed on the first sleeve to form the desired color. This toner is used to develop the latent image on the image carrier.

Since the toner on the first sleeve after development was mixed, it was collected by a cleaning device without being returned to the original developing device. In Examples 1 to 3, it was collected in the developing device, but
It may be collected in a cleaning device as in Example 4.

Further, in this example 4, since the toner is vibrated during development, the color toners are mixed, and good color development is obtained.

Any color can be created by changing the bias conditions applied to the second sleeve of each developer by superimposing it on the first sleeve without superimposing it on the photoreceptor layer. For example, black can be created by applying a bias to the second sleeves for yellow, magenta, and cyan. Of course, black is a frequently used color, and a second sleeve containing black toner may be provided separately.

In this apparatus, it is preferable that the image carrier 1 and the movement of the first sleeve and the developer are set in the same direction in the development area, but the invention is not limited thereto.

Similarly, the moving directions of the first sleeve and the second sleeve are not limited to this.

According to this device, color balance can be adjusted using a simple method. For example, ■ change the photoreceptor potential, ■ change the exposure amount, and ■ change the developing bias of the first sleeve (in this case, this includes changing the voltage of the AC component, changing the frequency, and changing the DC component). ), (1) changing the speed of the first sleeve and the second sleeve, and (2) changing the developing bias of the second sleeve, the amount of developer formed on the first sleeve can be changed. The effect will be further improved if not only a DC voltage but also an AC component is applied to the second sleeve.

By performing the above operations for each developing device and each electrostatic latent image, color balance can be adjusted.

In addition, although the above example shows the case of positive development,
The present invention can also be used for so-called reversal development, which develops an electrostatic latent image formed by an exposure system such as a laser, LED, or LCD, by changing the toner polarity and the DC component of the bias of the first and second sleeves. For example, it can be implemented similarly. Forming a developer layer on the first sleeve by generating a DC component in order to move the developer having the same polarity as the charged polarity of the photoreceptor from the second sleeve to the first sleeve,
Development may be carried out using the reversal development method and conditions disclosed in Japanese Patent Application No. 128895/1982.

Furthermore, the present invention can be similarly applied to an image forming method in which an insulating layer is provided on the surface of a photoreceptor, and an image forming method in which an image is formed on a dielectric layer using a screen photoreceptor or an electrostatic recording head. Furthermore, the present invention can similarly develop a magnetic latent image, even if the developer on the first sleeve is magnetic.

In this case, the first sleeve preferably does not contain a magnet, at least in the development area.

610 Effects of the Invention As described above, the present invention is provided with a plurality of supply means for supplying a plurality of developers to the developer conveying body, so that the developing device can be made smaller in order to obtain images of two or more colors or a single color. , and the area it occupies can be reduced. Furthermore, since development can be carried out at a fixed position between the conveying member and the image forming surface, the degree to which each development is affected by changes in the potential of the image carrier is greatly reduced. For this reason, it is preferably used in a color copying machine using a conventional transfer drum, but it also simplifies the operation and structure by omitting the transfer drum, since development such as overlapping can be easily performed.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a conventional color copying machine. 2 to 4 show embodiments of the present invention. FIG. 2 is a general sectional view of an electrophotographic copying machine, and FIGS. 3 and 4 are cross sections of two sides of a developing device. It is a diagram. In addition, in the symbols shown in the drawings, 1.-11111 photosensitive drum (image carrier) 20.--
--Developing device 30 ---First sleeve 31.32.33 --Developer supply device 34.3
5.36...Second sleeve 37'---Cleaning device 38.39.40.65---
It is a magnet. Agent: Patent attorney Hiroshi Aisaka (and 1 other person) Figure 3 Figure 4

Claims (1)

[Claims] 1. The image forming apparatus is characterized by having a developer conveying body that conveys developer to an image forming surface to perform development, and a plurality of developer supply means that respectively supply a plurality of developers onto the developer conveying body. Developing device.