JPH10111601A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of irregularities in an image and to stably form an image of high quality by specifying conditions for setting a control electrode plate. SOLUTION: This developing device is provided with a developing sleeve 41 having a resistance layer 412 of 1×10<3> -1×10<7> Ωm<2> on the outer periphery of a conductive substrate 411 to which an oscillating voltage is applied and the elastic control electrode 80 is in press-contact with the outer periphery of the developing sleeve 41. In other words, in a developing unit 4 (Y, M, C, K) having the control electrode 80 abutted on a developer D, in the gap between the developing sleeve 41 provided to face a photoreceptor drum 1 and the drum 1 the installed position of the whole of the control electrode 80 is in contact with a developer layer and further, the control electrode 80 is located on the side of the developing sleeve 41 of a tangent line M perpendicular to a centerline (p) passing through the centers of the drum 1 and the sleeve 41. Therefore, an electrode part 82 is away from a developing region to an upstream part, to prevent soiling on an electrode caused by a toner cloud.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying apparatus, and more particularly to a developing apparatus for non-contact development of an electrostatic latent image using a one-component developer mainly composed of non-magnetic toner particles. .

[0002]

2. Description of the Related Art Conventionally, as one of the developing methods used in an electrophotographic copying machine or the like, there is a developing device using a one-component developer composed of a non-magnetic toner. This developing device has a cylindrical developing sleeve which is rotatably supported with a roughened surface, holds a one-component developer (toner) on the surface of the developing sleeve, and transfers the same to the developing area with the image forming body. In the non-contact developing method, the developing is performed in a non-contact manner with the surface of the image forming body. One using such a developing method is proposed in, for example, Japanese Patent Application Laid-Open No. 7-160109.

In the one-component developing method, since a toner particle having an average particle size of about 10 μm is used, there is a problem that it is difficult to obtain a high-quality image which reproduces delicate lines, dots, differences in shading, and the like. In order to obtain such a high quality image, it is considered essential to make the toner particles finer. However, when the toner particles are particularly fine particles of 10 μm or less, the influence of the van der Waals force relative to the Coulomb force at the time of development becomes large, so that so-called fog in which the toner particles adhere to other portions of the image background. And it is difficult to prevent the problem by applying a DC bias to the developer conveying member. Agglomeration of the toner is also likely to occur, making charging control difficult.

[0004] Since the above-mentioned side effects are more conspicuous in making toner finer and clear images cannot be obtained, it has been difficult to actually make toner finer.

As a method for solving this problem, a plate-like member having an electrode portion in an upstream portion of a developing area is brought into contact with a developing sleeve,
A method of forming an oscillating electric field between the electrode portion and the developing sleeve, and between the developing sleeve and the photoreceptor so that the former is stronger, and forming a cloud of toner in the developer to perform development is disclosed in 5-346736, JP-A-6-16-1
No. 75485.

[0006]

However, the above-mentioned control electrode plate method has the following problems.

Problems such as image disturbance due to vibration of the control electrode plate, generation of vertical stripes by the control electrode plate, and non-uniform developability caused by charge application by the control electrode plate occur, causing deterioration in image quality. Since a high electric field is generated, the breakdown between the developing sleeve and the control electrode plate causes uneven development and lowers the image quality. Toner accumulates on the control electrode plate, thereby contaminating the image on the image forming body or accumulating toner. Since the dielectric constant increases by the thickness of the portion, the developability increases and an image having a uniform density cannot be obtained.

The present invention solves the above-mentioned problems of the control electrode plate method, does not cause image disturbance and uneven development, forms a uniform thin developer layer, and has high uniformity and high resolution and developability. An object of the present invention is to provide a non-contact one-component developing device capable of stably obtaining a high-quality image.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a developing apparatus in which a one-component developer layer is formed on an outer peripheral surface of a developing sleeve and which performs development under non-contact developing conditions. 1 × 10 ³ to 1 × 10 ⁷ Ωm ² on the outer peripheral surface of
The first aspect of the present invention is achieved by a developing device having a developing sleeve having the above-described resistance layer, and a control electrode plate having elasticity which is pressed against the outer peripheral surface of the developing sleeve.

Another object of the present invention is to provide a developing device in which a one-component developer layer is formed on the outer peripheral surface of a developing sleeve and which performs development under non-contact developing conditions. A developing sleeve having an elastic layer having a rubber hardness of 35 ° to 65 °, and a control electrode plate having elasticity pressed against the outer peripheral surface of the developing sleeve (second invention). Achieved by

Further, the object is to form a one-component developer layer on the outer peripheral surface of a developing sleeve and perform development under non-contact developing conditions in a developing device for applying an oscillating voltage to the outer peripheral surface of a conductive substrate. A developing sleeve having an elastic layer having a resistance value of 1 × 10 ³ to 1 × 10 ⁷ Ωm ² and a rubber hardness of 35 ° to 65 °, and a control electrode plate having elasticity to be pressed against the outer peripheral surface of the developing sleeve This is achieved by a developing device (third invention) having the following.

Still further, the above object is to provide a developing device for moving a one-component developer on the outer peripheral surface of a developing sleeve to an image forming body surface under an oscillating electric field, wherein a developer layer forming member abutting on the outer peripheral surface of the developing sleeve is provided. And a control electrode plate having elasticity that comes into contact with the outer peripheral surface of the developing sleeve, wherein the contact pressure of the control electrode plate is 0.03 to 0.3 times the contact pressure of the developer layer forming member. This is achieved by a developing device (fourth invention) characterized in that the number is three times as large.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing an example of a color image forming apparatus provided with a developing device using a non-magnetic one-component developer.

Reference numeral 1 denotes a drum-shaped image forming body, that is, a photosensitive drum. A transparent conductive layer and an organic photosensitive layer (OPC) are formed on the outer periphery of a cylindrical conductive substrate formed of a transparent member such as optical glass or transparent acrylic resin. Is applied.

In this image forming apparatus, in the photoconductor layer of the photosensitive drum, which is the image forming point of the exposure beam for image exposure, an appropriate contrast with respect to the light attenuation characteristic (photocarrier generation) of the photoconductor layer. What is necessary is that it has an exposure light amount of a wavelength that can provide the following. Therefore, the light transmittance of the transparent substrate of the photosensitive drum in the present invention does not need to be 100%,
There may be a characteristic that a certain amount of light is absorbed when the exposure beam is transmitted. As a material of the translucent substrate,
Fluorine, polyester used for soda glass, Pyrex glass, borosilicate glass, general optical members, etc.
Various translucent resins such as polycarbonate and polyethylene terephthalate can be used. Further, as the light-transmitting conductive layer, indium, tin oxide (ITO), tin oxide, lead oxide, indium oxide, copper iodide, Au, Ag,
A light-transmissive metal thin film made of Ni, Al, or the like is used. Examples of the film forming method include a vacuum deposition method, an active reaction deposition method, various sputtering methods, various CVD methods, a dip coating method, and a spray coating method. Used. As the photoconductor layer, an amorphous silicon (a-Si) alloy photosensitive layer, an amorphous selenium alloy photosensitive layer, or various organic photosensitive layers (OPC) can be used.

The photosensitive drum 1 has a flange at one end supported by a guide pin (not shown) provided on the process cartridge body 10, and a flange at the other end provided on a substrate of the image forming apparatus body. The outer peripheral gear is meshed with the drive gear by being externally fitted to the plurality of guide rollers, and the power is used to rotate the transparent conductive layer clockwise while grounding the transparent conductive layer.

Reference numeral 2 (Y, M, C, K) denotes a scorotron charger (hereinafter, referred to as a charger) which discharges the above-mentioned organic photoconductor layer of the photoconductor drum 1 from a grid maintained at a predetermined potential and discharges. A charging action is performed by corona discharge by a wire, and a uniform potential is applied to the photosensitive drum 1.

Reference numeral 3 (Y, M, C, K) denotes an F in which light emitting elements arranged in the axial direction of the photosensitive drum 1 are arranged in an array.
LISA, PLZT, LCS in which L, EL, PL, LED, light emitting element and element having optical shutter function are arranged in a line
And an exposure optical system composed of a selfoc lens as an equal-magnification imaging element. Image signals of each color read by a separate image reading device are sequentially taken out of the memory and sent to the respective exposure optical systems 3. Each is input as an electric signal.

Each of the above exposure optical systems 3 (Y, M, C, K)
Are mounted on a hexagonal column-shaped support member 11 having guide pins fixed to the substrate of the apparatus main body as guides, and are housed inside the substrate of the photosensitive drum 1.

4 (Y, M, C, K) is a non-magnetic one-component developer of yellow (Y), magenta (M), cyan (C) and K (black) (hereinafter referred to as developer). D
And developing sleeves 41 that rotate in the same direction while maintaining a predetermined gap with respect to the peripheral surface of the photosensitive drum 1.

Each of the developing units 4 (Y, M, C, K) is
Although the details will be described later, the charger 2 (Y, M, C,
K), the electrostatic latent image on the photosensitive drum 1 formed by image exposure by the exposure optical system 3 (Y, M, C, K) is reversely developed in a non-contact state by applying a developing bias voltage. .

Next, the process of the color image forming apparatus in the present apparatus will be described.

In the original image, an image read by an image sensor or an image edited by a computer is once converted into an image signal for each color of Y, M, C and K by an image reading apparatus separate from the present apparatus. Stored and stored in memory.

When the image recording is started, the drive gear is rotated by the start of the photoconductor driving motor to rotate the photoconductor drum 1 clockwise in the drawing, and at the same time, the photoconductor is charged by the charging action of the charger 2 (Y). The application of the potential to the drum 1 is started.

After the photosensitive drum 1 is applied with a potential,
The exposure optical system 3 (Y) starts exposure with an electric signal corresponding to a first color signal, that is, an image signal of yellow (Y), and the rotational scanning of the drum causes the yellow (Y) A) to form an electrostatic latent image corresponding to the image of FIG.

The latent image is reversely developed by the developing device 4 (Y) in a state where the developer D on the developing sleeve 41 is not in contact with the developing device 4 (Y), and a yellow (Y) toner image is formed in accordance with the rotation of the photosensitive drum 1. Is done.

Next, the photosensitive drum 1 is further provided with a potential on the yellow (Y) toner image by the charging action of the charger 2 (M), and the second color signal of the exposure optical system 3 (M). That is, exposure is performed by an electric signal corresponding to the image signal of magenta (M), and the magenta (M) is applied on the yellow (Y) toner image by non-contact reversal development by the developing device 4 (M). The toner images are sequentially superimposed and formed.

According to the same process, the toner image of cyan (C) corresponding to the third color signal is further charged by the charger 2 (C), the exposure optical system 3 (C) and the developing device 4 (C). 2 (K), exposure optical system 3 (K) and developing unit 4
By (K), a black (K) toner image corresponding to the fourth color signal is sequentially superposed, and a color toner image is formed on the peripheral surface within one rotation of the photosensitive drum 1.

The photosensitive drum 1 by each of these exposure optical systems
Exposure to the organic photosensitive layer is performed from the inside of the drum through the transparent substrate described above. Therefore, the exposure of the images corresponding to the second, third, and fourth color signals is performed without any influence from the previously formed toner image, and the first exposure is performed.
It is possible to form an electrostatic latent image equivalent to an image corresponding to the color signal. Each exposure optical system 3 (Y, M, C,
In order to stabilize the temperature in the photosensitive drum 1 and prevent the temperature from rising due to the heat generation of K), a material having good thermal conductivity is used for the support member 11, a heater is used at a low temperature, and a heat is used at a high temperature. By taking measures such as radiating heat to the outside through a pipe, it can be suppressed to a level that does not cause any trouble.

In the developing operation of each of the developing units 4 (Y, M, C, K), a developing bias to which a direct current or a further alternating current is applied is applied to the developing sleeve 41, and the developing sleeve 41 is accommodated in the developing unit. Non-contact development with the developer D is performed, and a direct current bias of the same polarity as the developer is applied to the photosensitive drum 1 that grounds the transparent conductive layer, thereby causing the developer to adhere to the exposed portion. Development is performed.

Thus, the color toner image formed on the peripheral surface of the photosensitive drum 1 is transferred from the paper feed cassette 20 in the transfer unit 5 and transferred to the transfer paper P fed in synchronization with the driving of the timing roller 21. Is done.

The transfer paper P to which the toner image has been transferred is separated from the outer peripheral surface of the photosensitive drum 1 by the removal of the charge in the charge remover 6, is conveyed by the conveying belt 22, and removes the toner by the fixing device 23. After welding, the sheet is discharged onto a sheet discharge tray 26 at the top of the apparatus via a sheet discharge roller 24 and a sheet discharge guide 25.

On the other hand, the photosensitive drum 1 from which the transfer paper P is separated
Is to remove and clean the residual toner on the photosensitive drum 1 in the cleaning device 7 and continue forming the toner image of the original image, or temporarily stop and start forming a toner image on a new original image. I do.

The photosensitive drum 1 and each charger 2 (Y,
M, C, K), each developing unit 4 (Y, M, C, K) and the cleaning device 7 are housed in the process cartridge main body 10 and integrated with each other without applying a load or impact to the image exposure means. It is configured so that it can be attached to and detached from the apparatus main body while leaving the support member 11 having the exposure optical system 3.
The configuration in which the support member 11 is left at the time of attachment / detachment is such that the lead wire for operating the heater, the heat pipe, the LED and the optical system 3 are fixed to the support member 11 regardless of the rotation of the photosensitive drum 1 and the attachment / detachment of the photosensitive drum 1. It has features that can be kept. It can also be used to determine the axis of the photosensitive drum 1.

FIG. 2A is a schematic sectional view of a developing device 4 containing a non-magnetic one-component developer according to an embodiment of the present invention, and FIG. It is sectional drawing.
The developing devices 4 (Y, M, C, K) have substantially the same configuration, but as shown in FIG. 1, the rotation of the developing sleeve 41 of the developing device 4 (Y) and the developing sleeve 41 of the developing device 4 (M). The direction is clockwise, and the developing device 4 (C) and the developing sleeve 4 of the developing device 4 (K)
The rotation direction of 1 is counterclockwise. Hereinafter, the developing device 4
(K) will be described as a representative.

FIG. 2 shows a state in which the exposure position on the photosensitive drum 1 by the exposure optical system 3 is provided in the developing casing 40 of the developing unit 4 on the upstream side of the developing sleeve 41.

In the drawing, reference numeral 41 denotes a developing sleeve which is a developer conveying member, which is made of a non-magnetic material such as aluminum and can be rotated in the direction of the arrow in the drawing. Reference numeral 42 denotes a regulating member that is provided on the upstream side of the developing region of the developing sleeve 41 that is rotated by the developer layer forming member of the developer D, and regulates the amount of the developer conveyed to the developing region. A supply member 44 supplies the newly stirred developer D. The supply member 43 also has a function of scraping off the developer D attached to the developing sleeve 41 after the development. Reference numeral 45 denotes a stirring screw for stirring the developer D to make the components uniform.

The supply member 44 is composed of a conductive sponge roller. The supply member 44 is brought into contact with the developing sleeve 41 to supply the developer D to the developing sleeve 41.

The developer layer forming member 42 has a leaf spring 421 whose one end is supported by a part of the developing casing 40.
And a blade 4 attached to the other end of the leaf spring 421.
22. The developer layer forming member 42 is a regulating blade that regulates the thickness of the developer layer.
In order to charge the developer D by rubbing the developer 1 with the developer D, an elastic blade type made of an elastic rubber such as urethane rubber or silicone rubber is preferable. The form in which the developer layer forming member 42 contacts the outer peripheral surface of the developing sleeve 41 may be either a counter type or a trail type (shown).

In this color image forming apparatus, an exposure optical system 3 (Y, M, C, K) using an LED or the like is arranged inside the photosensitive drum 1, and the exposure optical system 3 (Y, M, C, The image exposure position according to K) is provided on the upstream side of the developing sleeve 41 in the developing casing 40, and a center line connecting the center of the photosensitive drum 1 and the center of the developing sleeve 41 is defined as a center line p. Center line p
The distance between the upper photosensitive drum 10 and the developing sleeve 41 is closest, and the developing center Q is on this center line p. The distance on the photosensitive drum 1 from the developing center Q to the end face of the developing casing 40 on the upstream side is L ₁ , the distance of the photosensitive drum 1 from the developing center Q to the image exposure position is L ₂ , and the developing from the developing center Q is the width of the developing area is made w1, when T a reduction time potential of the organic photosensitive material coated on the photosensitive drum 1, a process speed i.e. the peripheral speed of the photosensitive drum 1 was set to v, L _1> L _2> The relationship is set as vT + w1.

In this embodiment, L ₁ and L ₂ are set between 3 and 30 mm. Also the process speed v
Is between 30 and 300 mm / sec. The potential reduction time T of the organic photoreceptor used in this embodiment can be easily obtained experimentally, but is 0.1 sec or less. The width w1 of the development area is usually between 1 and 2 mm.

Therefore, the process speed v is 30 to 300.
When the potential decrease time T is 0.1 sec at 0.1 mm / sec, vT + w1 = 4 to 32 mm, and the process speed v is 30 to 300 mm / sec and the potential decrease time T is 0.
When the 05Sec, by configuring to perform the image exposure at satisfying position of vT + w1 = 2.5~17mm next, L _2> 3~32mm or L _2> 2.5~17mm,
As shown in FIG. 2, the potential of the photoreceptor is sufficiently lowered, and the next development is performed on the previously developed toner image while the toner image is stably adhered to the photoreceptor drum 1.

Numeral 80 denotes an electrode portion 82 capable of applying a voltage on an insulating member 83 which is an insulating member made of an electrically insulating material and provided on the upstream side of the developing region so as to contact the layer of the developer D;
Further, a control electrode plate including a support member 81 coupled to support the insulating member 83 on the upstream side of the electrode portion 82 will be described in detail later. The electrode portion 82 is made of a conductive material such as a metal, and is linearly provided integrally on the distal end portion of the insulating member 83.

Reference numeral 401 denotes a support provided on the developing casing 40 for fixing the base of the supporting member 81 of the control electrode plate 80 to the developing casing 40. Reference numeral 88 denotes a pressing plate for fixing the supporting member 81 of the control electrode plate 80 to the supporting portion 401, and reference numeral 89 denotes a set screw for fixing the pressing plate 88 to the supporting portion 401.

Any of the developing units 4 (Y, M, C, K)
Also, the developer layer formed on the developing sleeve 41 does not contact the surface of the photosensitive drum 1 and the blade 422 attached to the developing sleeve 41 and the developer layer forming member 42 so as to maintain a gap. , And the closest distance g ₀ between the developing sleeve 41 and the photosensitive drum 1 are adjusted.

The developing sleeve 41 has a DC power supply E _1.
AC bias voltage obtained by superposing an AC component on a DC component through the protective resistor R ₁ by the AC power source E ₂ is applied with. Furthermore, the electrode portion 82 a bias voltage of only DC components through the protective resistance R ₂ from the DC power source E ₃ is applied. Electrode part 8
2 is preferably applied with a DC voltage having the same polarity as the toner in the developer from the viewpoint of preventing toner adhesion.

In the above-described developing device 4 (Y, M, C, K), by applying an AC bias voltage to the developing sleeve 41, an alternating electric field (between the photosensitive drum 1 and the developing sleeve 41) is formed. Is referred to as a second oscillating electric field), and a first oscillating electric field is generated between the electrode portion 82 of the control electrode plate 80 and the developing sleeve 41.

In this case, since the electrode portion 82 is provided closer to the developing sleeve 41 than the photosensitive drum 1, the intensity of the first oscillating electric field is larger than the intensity of the second oscillating electric field.

The first oscillating electric field vibrates the developer D that has reached the vicinity of the electrode portion 82 in a direction perpendicular to the line of electric force, so that the developer D separates and flies from the outer peripheral surface of the developing sleeve 41. And a cloudy haze-like toner cloud can be sufficiently generated. This toner cloud is assisted by the second oscillating electric field to fly toward the latent image on the photosensitive drum 1, and uniform development is performed.

At this time, since the AC bias voltage is applied only to the developing sleeve 41, the first oscillating electric field and the second oscillating electric field have the same phase, and the developer D is moved from the first oscillating electric field to the second oscillating electric field. To the oscillating electric field.

The waveform of the AC component is not limited to a sine wave.
A rectangular wave or a triangular wave may be used. Also, although the frequency is related, as the voltage value is higher, the spikes of the developer D vibrate, and the developer D separates and flies more easily. On the other hand, dielectric breakdown such as fogging and lightning strike occurs. It is easy to occur. The generation of fog can be prevented by a DC component, and the dielectric breakdown can be prevented by coating the surface of the developing sleeve 41 with an insulating or semi-insulating material such as a resin or an oxide film.

The frequency of the AC component of the bias voltage applied to the developing sleeve 41 is preferably 100 Hz to 20 kHz, particularly preferably 1 kHz to 10 kHz.

In the color image forming apparatus provided with the developing device 4 (Y, M, C, K), reversal development is performed using a negatively charged OPC photosensitive member as a photosensitive member of the photosensitive drum 1, and the photosensitive member is exposed. Assuming that the body is charged to, for example, −850 V and the potential of the image portion maximum density portion is −50 V, an AC bias voltage in which an AC voltage is superimposed on a DC voltage of −750 V in the electrode portion 82 and −750 V in the developing sleeve 41 is applied. Preferably applied. Here, the zero peak voltage (V _0-P ) of the AC component applied to the developing sleeve 41 is the closest distance g between the photosensitive drum 1 and the developing sleeve 41 shown in FIG.
₀ (μm), the height h (μm) of the electrode portion 82 from the developing sleeve 41, and the volume average particle diameter D ₅₀ of the toner in the developer.
(Μm) and when the average charge amount of the toner is Q ₂ (μC / g), for one-component development, 500 · Q ₂ · D ₅₀ · g ₀ > V _{0 -P} > 3 · Q ₂ · D ₅₀ · H preferably 200 · Q ₂ · D ₅₀ · g ₀ > V _0-P > 5 · Q ₂
· D is preferably in the range of ₅₀ · h.

The developing device 4 (Y, M, Y) having a control electrode plate 80 provided opposite to the photosensitive drum 1 and in contact with the developer D in a gap between the developing sleeve 41 and the photosensitive drum 1.
(C, K) indicates that the installation position of the control electrode plate 80 as a whole is in contact with the developer layer and at the center line p passing through the centers of the photosensitive drum 1 and the developing sleeve 41 as shown in FIG. The control electrode plate 80 is positioned on the side of the developing sleeve 41 with respect to the vertical tangent line M.

The operation of the control electrode plate 80 only generates the toner cloud and sends it to the development area, but does not contribute to the development in the development area. If the electrode unit 82 is disposed so as to be on the photosensitive drum 10 side beyond the tangent line M, the toner cloud easily wraps around the electrode unit 82, and toner contamination on the electrode is likely to occur.

The toner stains on the electrodes not only accumulate and cause image stains and the like, but also increase the dielectric constant of the deposited portion, so that the effective gap between the developer layer and the image forming body is reduced. Is narrowed, so that the developability of the portion is increased, and the image appears as a vertical stripe.

By arranging the electrode portion 82 on the side of the developing sleeve 41 without exceeding the tangent line M, the electrode portion 82 is located farther upstream from the developing area, and the above-mentioned contamination of the electrode by the toner cloud does not occur.

When the developer D is a developing device 4 (Y, M, C, K) using a one-component developer composed of at least toner, a gap g ₂ (μ) between the tangent line M and the control electrode plate 80 is used.
m), the gap g ₁ (μm) between the developer D and the photosensitive drum 1
When the relationship between the relationship and d and g ₀ of g ₂ and g _{1 are, g 2 = (0~2) ×} g 1 d = (2~10) is preferably × g _0.

[0060] In the case of one-component developer D, since the developer layer for a toner alone is low, the relationship between g ₁ and _{g 0, g 1 = (0.7~0.95} ) × g ₀ is preferable (g ₁ increases in this case, so the developing bias voltage is set higher accordingly).

If g ₁ <0.7 g ₀ , the toner layer becomes thick and the charging of the toner becomes unstable, and the rotation of the developing sleeve 41 causes the toner to become unremovable on the peripheral surface of the photosensitive drum 10 and on the photosensitive drum 10. It comes into contact with the color toner and causes fogging, color mixing, and color smearing.

When g ₁ > 0.95 g ₀ , the photosensitive drum 1
The developer layer is too far away from 0 to deteriorate the developability.

The developing devices 4 (Y, M, C, K) are both g ₀ ,
By setting the conditions of g ₁ , g ₂ , and d as described above, it becomes difficult for toner to adhere to the electrode portion 82 of the control electrode plate 80, and a change in the dielectric constant due to toner adhesion is suppressed. The occurrence of image unevenness can be prevented. In addition, since the control electrode plate 80 is set at a place where the gap between the photosensitive drum 1 and the developing sleeve 41 is wide, the degree of freedom of setting is increased, so that undulation and warpage are hardly generated.
It is possible to set the control electrode plate 80 stably. Therefore, an image free from white stripes and image unevenness can be stably obtained over a long period of time.

Incidentally, h is preferably h = (0.2 to 0.6) × g ₀ from the viewpoint of preventing discharge to the developing sleeve 41 and the photosensitive drum 1 and ensuring developability.

Next, the configuration of the control electrode plate 80 used in the developing devices 13a and 13b of the present invention will be described.

As shown in FIG. 3A, the control electrode plate 80 includes an insulating member 83 which is an insulating member made of glass epoxy ceramic or the like which supports the electrode portion 82, and a supporting member which supports the insulating member 83. It consists of 81. Insulating member 83
The support member 81 and the support member 81 are joined together by bonding a part of each with an adhesive or the like. FIG. 3B is a cross-sectional view showing specific dimensions of the control electrode plate 80.

The insulating member 83 is preferably made of the following material so as to be thin so that it can be installed in the space of the narrow developing area, and to maintain the overall linearity of the control electrode plate 80.

(Material of Insulating Member 83) As the insulating member 83, for example, polyester, polyimide, glass epoxy, ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-6-propylene copolymer, polytetrafluoroethylene Insulating resins such as ethylene fluoride, polyamide imide, polysulfone, triazine resin, polyethylene terephthalate, and polyurethane, or composite materials reinforced with glass fibers and the like, paper, paper phenol, varnish, and materials such as silicone rubber, Alumina (Al ₂ O ₃ ), single crystal sapphire (Al ₂ O ₃ ), forsterite (2MgO / SiO ₂ ), steatite
(MgO / SiO ₂ ) system, zircon (ZrO ₂ · SiO ₂ )
System, cordierite (2MgO.2Al ₂ O ₃ .5Si
O ₂₎ system, titania, silicon carbide (SiC) based, silicon nitride (Si ₃ N ₄₎ type, zirconia (ZrO ₂₎ system can be used each ceramic Cermet.

In order to impart appropriate elasticity to the insulating member 83, the ceramic may contain 5 to 20% by weight of a resin. In addition, in order to reduce the surface roughness of the surface on the side of the developing sleeve 41 and obtain good developer conveyance, it is desirable that the surface of the insulating member 83 is polished.

(Method for Forming Electrode Portion 82) Above Insulating Member 8
In addition to attaching an electrolytic copper foil, annealed electrolytic copper foil, beryllium copper foil or the like to the insulating member 83 by using an adhesive, a photo-etching method using a conventionally known photopolymer, an etching resist forming method by screen printing, or the like is used.
A necessary electrode part 82 is formed on the upper part. In addition, a method of printing the conductive ink by letterpress, stencil, intaglio, or planographic printing corresponding to the electrode portion 82 or a method of evaporating metal can be used.

FIG. 3C shows an example in which the downstream end of the electrode portion 82 and the downstream end of the insulating member 83 coincide with each other, and FIGS. 3D and 3E.
Shows an example in which an eaves member 84 made of an insulating material such as a glass epoxy plate is bonded to the tip of the insulating member 83 with an adhesive or the like, and an electrode portion 82 is formed between the insulating member 83 and the eaves member 84. FIG. 3F shows the eaves member 8.
4 shows an example in which an electrode portion 82 is formed on the lower surface of the tip.

The control electrode plate 80 is also provided in FIG.
As shown in (b), (c) and (d), an electrode portion 82 is formed by bonding a linear electrode having a circular or quadrangular cross section to the tip of the insulating member 83 using an adhesive or the like. Can be used. Further, as shown in FIG. 4 (e), a notch 83a may be provided at the end of the insulating member 83, and a linear electrode may be embedded therein to form the electrode portion 82.
Further, as shown in FIGS. 4F and 4G, an eave member 84 is provided at the tip of the insulating member 83, and a linear electrode is adhered to the lower surface of the tip of the eave member 84 to provide the electrode portion 82. It may be.

The material of the electrode portion including the linear electrode includes copper, copper-zinc, copper-cadmium, phosphor bronze, copper-beryllium, Corson alloy, aluminum, aluminum alloy, tantalum, tungsten, nickel, molybdenum, stainless steel Steel, gold, titanium, chrome, palladium,
A metal such as silver, a metal oxide such as copper oxide, a composite of glass coated with copper powder, graphite, nickel, silver, or the like, or a conductive material such as graphite or carbon fiber can be used. These materials are desirably insulated for preventing discharge, preventing rust, and imparting strength.

(Material of Support Member 81) The material of the support member 81 is preferably a thin metal plate having high linearity and elasticity. For example, a metal or an alloy used for the linear electrode can be used. Among them, it is particularly preferable to use a stainless steel thin plate from the viewpoint of cost and flexibility.

The thickness of the support member 81 depends on the material.
Considering the ease of connection with the insulating member 83, 0.05 m
m to 1 mm is preferred. If the thickness is less than 0.05 mm, wrinkles and distortions are liable to occur when joining with the insulating member 83.
If the thickness is more than 1 mm, the elasticity is lost and the control electrode plate 80
The degree of freedom of setting is reduced.

When the metal thin plate is used for the support member 81, it is preferable that the metal thin plate is insulated and coated with a fluorine-based resin or the like in order to prevent leakage of the bias voltage applied to the developing sleeve 41 and the photoconductor potential.

The length of the electrode portion 82 in the circumferential direction depends on the diameter of the developing sleeve 41 and the transport speed, but is 0.05 to 5 mm.
In particular, 0.1 to 1 mm is preferable. If it is less than 0.05 mm, a sufficient toner cloud cannot be generated,
Above m, the toner is charged by vibration and becomes excessively charged, so that the developing property is reduced.

When the developer D is conveyed onto the developing sleeve 41 on the control electrode plate 80, the developer D is placed between the insulating member 83 and the developing sleeve 41 as shown in FIGS. 5 (a) and 5 (b). As a result, the insulating member 83 is slightly curved and faces the developing sleeve 41 with a slight gap or little gap, that is, the insulating member 83 faces the developing sleeve 41 in a state where the insulating member 83 is in contact with or close to the developing sleeve 41. Become like

The electrode part 82 of the control electrode plate 80 and the insulating member 8
3 (see FIG. 3), the developing gap, which is the closest distance between the photosensitive drum 1 and the developing sleeve 41, is g.
_{Assuming 0} (mm), it is preferable that (1/10) g ₀ <t <(2/3) g ₀ .

When t> (2/3) g ₀ , the dielectric material, which is a photosensitive member, approaches the electrode portion 82, so that the electric field intensity is increased on the electrode portion 82 and a high bias voltage is applied to the electrode portion 82. In such a case, the latent image may be disturbed, or the multicolor toner on the photosensitive drum 1, which is an image forming body, may be peeled off during multicolor image formation.

At t <(1/10) g ₀ , since the electrode portion 82 is separated from the photosensitive drum 1, the electric field is weakened and a sufficient toner cloud is not formed. Further, the insulating member 83 becomes thinner, its rigidity becomes lower, and it becomes easier to crack.

The thickness of the control electrode plate 80 is measured with a micrometer (M320-25A, manufactured by Mitutoyo) in the direction of the rotation axis of the developing sleeve 41 of the control electrode plate 80, and the average value is measured. Of thickness t.

FIG. 6 is an explanatory diagram showing the relationship between the width of the electrode section 82 and the width of the developing area. In FIG. 6, W ₃ is the width of the electrode portion 82 (the length of the developing sleeve 41 in the axial direction), and W ₄
Is the width of the developing region on the developing sleeve 41 in the axial direction (the width of the developer D layer), W ₃ > W ₄ , and the terminal portion 82a for applying a DC voltage to the electrode portion 82 is also provided in the developing region. provided in a portion than the width W ₄ on the outside, to prevent the occurrence of unwanted toner cloud.

Further, the surface roughness Rz of the developing sleeve 41
₁ (μm) and the roughness Rz ₂ (μm) of the surface of the insulating member 83 facing the developing sleeve 41, when Rz ₂ ≧ Rz ₁ ,
The developer conveyed onto the developing sleeve 41 is an insulating member 83
, The amount of toner transported to the developing area is reduced, and the image density is reduced. Rz ₁ is 0.2 μm to 20 μ
The range of m and the range of Rz ₂ are preferably in the range of 0.02 μm to 5.0 μm, in order to obtain good transportability and high density images without image disturbance. The surface roughness Rz is JI
According to SB0601, Surftest manufactured by Mitutoyo
The measurement was performed using -402 with a reference length of 25 mm.

Next, the developer D will be described.

In general, as the average particle diameter of the toner particles decreases, the charge amount decreases qualitatively in proportion to the square of the particle diameter.
Since the influence of the adhesive force such as the Van der Waals force becomes relatively large, the electrostatic control of the toner particles becomes difficult, the toner particles are easily scattered, and the fog is easily generated. In the conventional developing method, when the average particle diameter is 10 μm or less, such a problem becomes conspicuous. In the developing device of the present invention, this point is solved by performing the toner development under the double oscillating electric field as described above.

When the volume average particle diameter D ₅₀ (μm) of the toner increases, as already mentioned, the roughness of the image becomes conspicuous. If D ₅₀ is used the toner following micronized 10 [mu] m, the resolution is remarkably improved, so give a clear high-quality images shading difference also faithfully reproduced. D ₅₀ is 20μm or more results in reduction in image quality, poor charging, scattering and the like easily occurs.

For the above reasons, the volume average particle diameter D _{50 of the} toner
Is 1 to 20 μm, preferably 4 μm <D ₅₀ <8 μm.

When D ₅₀ > 8 μm, the particle size is large and the resolving power is insufficient, and when D ₅₀ <4 μm, the cohesive force is large and triboelectric charging is likely to occur.

Here, the volume average particle diameter D used for the average particle diameter is
₅₀ is a coulter counter TA-II type (aperture 1
00 μm, manufactured by Coulter Corporation).

Here, the average charge amount Q ₁ of the non-magnetic toner is
A conductive plate of 2 cm × 5 cm is opposed to a developing device 4 (Y, M, C, K) having the above-described elastic blade 422 and having a developing sleeve 41 of 20 mm in diameter at a closest distance of 0.7 mm. Then, the charged developer is supplied to the developing sleeve 41, and the superposed voltage of DC and AC (for example, DC;
00V, AC; zero peak voltage 750V, frequency 8k
(Hz), the toner in the developer is developed on the conductive plate, the conductive plate on which the toner has been developed is connected to a Faraday gauge, and the toner is blown off by nitrogen gas. This is a value obtained by measuring the charge amount and weight of the toner.

Examples of binder resins for such toners include styrene resins, vinyl resins, ethyl resins, rosin-modified resins, acrylic resins, polyamide resins, epoxy resins, polyester resins, and styrene-acryl resins. And the like, or a mixed resin or the like. To these resins, a coloring component such as a color pigment, and if necessary, a charge controlling agent, a releasing agent such as a wax, etc. are added, and a toner such as a conventionally known pulverization granulation method, suspension polymerization method, emulsion polymerization method or the like is added. It can be made by a method equivalent to the manufacturing method.

As the one-component developer, a fluidizing agent such as colloidal silica is added to the non-magnetic toner, and the developer can be used as it is.

[Embodiments of the present invention]
4 uses a one-component developer, uses the color image forming apparatus shown in FIG. 1 provided with the developing device 4 (Y, M, C, K) shown in FIG. 2, and the photosensitive drum 1 is made of an acrylic resin. OPC is coated on a transparent substrate made of a material having a peripheral speed (process speed v) of 180 mm / sec. The maximum potential of the electrostatic latent image formed on the photosensitive drum 1 is -850 V
(Non-image portion potential), minimum potential is -50 V (image portion potential), outer diameter of developing sleeve 41 is 20 mm, rotational speed of developing sleeve 41 is 260 rpm, surface roughness R _z1 of developing sleeve 41 is 1.2 μm, developing sleeve is 41 DC potential -7
50 V, AC voltage V _{0-P of} developing sleeve 41 800 V,
The frequency is 8 kHz, the developing area width is 1.5 mm, L
₁ = 12 mm and L ₂ = 15 mm.

The control electrode plate 80 has the structure and dimensions shown in FIG. 3B, and uses a glass epoxy plate having a thickness of 0.1 mm as the insulating member 83, and as shown in FIG.
Was formed by a laminate etching method using a copper pad having a circumferential width of 0.5 mm and a thickness of 0.02 mm. Further, a support member 81 made of a stainless steel plate having a thickness of 0.1 mm is attached to the insulating member 83 with an adhesive, and the control electrode plate 80 is attached to the developing casing 40 of the developing device 4 (Y, M, C, K). Fixed. The surface roughness of the insulating member 83 on the developing sleeve 41 side is Rz = 0.8 μm, the height h of the electrode part 82 is 0.25 mm, and the thickness of the formed toner layer is 1.5 to 1.5 μm of the average particle diameter of the toner. It is three times.

As a non-magnetic one-component developer, 100 parts by weight of a styrene-acrylic resin, 10 parts by weight of a color pigment, and 2 parts by weight of nigrosine are melted and kneaded, and then pulverized and classified.
Yellow (Y), magenta (M), cyan (C), and black (K) toners having a volume average particle size of 5.5 μm were obtained. Each of the toners, to which 2 parts by weight of colloidal silica was added as a fluidizing agent, was used as a developer. Charge amount Q ₁ is, Y; -14.0μC / g, M ;
−9.0 μC / g, C; −11.0 μC / g, K; −1
6.0 μC / g.

Embodiment 1 The developing device shown in FIG. 2 is a developing device in which a non-magnetic one-component developer layer is formed on the outer peripheral surface of a developing sleeve 41 and the developer is applied under non-contact developing conditions. 1 × 10 ⁴ to 1 × 10 ⁷ Ωm on the outer peripheral surface of the conductive substrate 411 to which a voltage is applied.
A developing sleeve 41 having ^two hard resistive layers 412;
The image forming apparatus further comprises: a developer layer forming member having elasticity in contact with the outer peripheral surface of the developing sleeve; and a control electrode plate having elasticity in contact with the outer peripheral surface of the developing sleeve. Item 1).

In order to form a uniform and stable developer thin layer having about 1.5 to 3 toner layers on the outer peripheral surface of the developing sleeve 41, the elastic blade 4 is used as the developer layer forming member 42.
The method of pressing the developing sleeve 22 against the developing sleeve 41 is suitable.
The elastic blade 422 is made of silicone rubber or urethane rubber having a rubber hardness of 50 ° (by a Shore A type hardness meter), and has a Young's modulus of 2 × 10 ⁴ kgf / mm ^2.
1 is adhered to the tip portion with an adhesive.

The amount of the developer adhered on the developing sleeve 41 depends on the pressing force of the elastic blade 422, and decreases as the pressing force increases, and becomes constant at about 1200 g / cm ² or more. Further, since the frictional force between the developer and the developing sleeve 41 is greatly affected by the surface roughness of the developing sleeve 41,
The amount of developer attached also depends on the surface roughness. However, when the surface roughness is about 1 μm Ra or more, the change in the amount of developer attached to the surface roughness becomes small.

In the control electrode developing method in which the control electrode plate 80 is provided in the developing area, a high AC voltage is applied between the developing sleeve 41 and the control electrode plate 80 to generate a toner cloud. Resistance layer 4 on sleeve 41 surface
Provision of 12 prevents occurrence of breakdown. The resistance layer 412 is provided with a hard resistance layer having a thickness of 0.3 to ³ mm and an electric resistance of 1 × 10 ³ to 1 × 10 ⁷ Ωm ² on the outer periphery of the conductive base 411 made of the above-described metal roller. is there. The electric resistance of the resistance layer 412 is adjusted by mixing an appropriate amount of conductive carbon.

Further, due to the resistance layer 412, the adhesive force between the developer and the developing sleeve 41 is reduced.

Embodiment 2 The developing device shown in FIG. 7 is a developing device which forms a non-magnetic one-component developer layer on the outer peripheral surface of a developing sleeve 41 and performs development under non-contact developing conditions. A developing sleeve 41 having an elastic layer 413 having a rubber hardness of 35 ° to 65 ° on the outer peripheral surface of the conductive substrate 411 to which the developer is applied, and a developer layer forming member 42 having elasticity pressed against the outer peripheral surface of the developing sleeve 41. And a control electrode plate 80 having an elasticity and pressed against the outer peripheral surface of the developing sleeve 41.

The developing sleeve 41 has a rubber layer having a thickness of 0.3 to 3 mm, for example, an elastic layer 413 made of any of NBR rubber, silicone rubber, urethane rubber, etc., on the outer peripheral surface of the conductive substrate 411. It is provided. The developer layer forming member pressed against the developing sleeve 41 is a leaf spring 423 such as an elastic stainless steel thin plate or an elastic resin plate. The rubber hardness of the elastic layer 413 is 3
5 ° to 65 ° is optimal. Further, by setting the thickness of the elastic layer 413 to the above-mentioned 0.3 to 3 mm, the influence of the deformation due to the pressing force of the leaf spring 423 is prevented.

Embodiment 3 In this embodiment, the developing device shown in FIG. 7 forms a non-magnetic one-component developer layer on the outer peripheral surface of a developing sleeve 41 and performs the developer under non-contact developing conditions. In the above, 1 × 10 ³
It has an electrical resistance of ~ 1 x 10 ⁷ Ωm ² and rubber hardness of 35 °
A developing sleeve 41 having an elastic layer of up to 65 °, a developer layer forming member 42 having elasticity in contact with the outer peripheral surface of the developing sleeve 41, and a control electrode having elasticity in pressing on the outer peripheral surface of the developing sleeve 41. And a plate 80.

The developing sleeve 41 has a rubber layer having a thickness of 0.3 to 3 mm, for example, an elastic layer 413 made of any one of NBR rubber, silicone rubber, urethane rubber, etc., on the outer peripheral surface of the conductive substrate 411. It is provided. The rubber hardness of the elastic layer 413 is optimally 35 ° to 65 °, and the electric resistance value is optimally 1 × 10 ³ to 1 × 10 ⁷ Ωm ² . The elastic layer 413 is formed on the conductive base 41 made of the above-described metal roller.
0.3 outer thickness, rubber hardness 35 ° -6
It has a characteristic of 5 ° and an electric resistance value of 1 × 10 ⁴ to 1 × 10 ⁷ Ωm ² . The electric resistance of the elastic layer 413 is adjusted by mixing an appropriate amount of conductive carbon.

Embodiment 4 In this embodiment, the developing device shown in FIG. 8 is a developing device for moving a non-magnetic one-component developer on the outer peripheral surface of a developing sleeve 41 to an image forming body surface under an oscillating electric field. A developer layer forming member 42 abutting on the outer peripheral surface of the developing sleeve 41;
A control electrode plate 80 having elasticity that abuts on an outer peripheral surface of the developing sleeve 41; and a contact pressure F1 of the control electrode plate 80 is set to 0.about.0 of a contact pressure F2 of the developer layer forming member 42. 03 to 0.3 times (F1 <F2).

It is necessary to apply an appropriate pressure to the contact pressure F1 of the control electrode plate 80 in order to prevent disturbance of the developer layer. If the contact pressure F1 of the control electrode plate 80 is weak (F1
Small), the control electrode plate 80 vibrates due to the first vibration voltage applied between the developing sleeve 41 and the control electrode plate 80, and development unevenness occurs. Further, when the contact pressure F1 of the control electrode plate 80 is strong (F1 is large), the developer layer on the developer sleeve 41 is disturbed, or charge is applied to the toner by unnecessary frictional charging, thereby deteriorating the developing characteristics. . Contact pressure F1 of the control electrode plate 80 is set in the range of ^{30g / cm 2 ~300g / cm 2} .

[0108]

According to the present invention, the problem of the control electrode developing method is solved. By setting the setting conditions of the control electrode plate as described above, toner is less likely to adhere to the electrode portion of the control electrode plate. In addition, since the influence of the control electrode plate in the developing region is appropriately suppressed, it is possible to prevent the occurrence of image unevenness. Therefore, it is possible to provide a developing device for non-contact development using a non-magnetic one-component developer which can stably obtain a high-quality image with high resolution and developability without vertical stripes and uneven development.

Further, the developing device is provided with a plurality of sets of charging means, image exposing means and developing means for the image forming body, and repeats charging, image exposing and developing during one rotation of the image forming body. A color image forming apparatus for transferring a toner image onto a transfer material at a time after forming a toner image on the image forming body by superimposing the toner image on the image forming body. No vertical streaks, uneven development, etc.
A color image forming apparatus capable of stably obtaining a high-quality image with high resolution and developability can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an example of a color image forming apparatus including a developing device using a non-magnetic one-component developer.

FIG. 2 is a schematic cross-sectional view of a developing device accommodating a non-magnetic one-component developer according to an embodiment of the present invention and an enlarged cross-sectional view of a main part of the developing device.

FIG. 3 is a sectional view showing various shapes of a control electrode plate.

FIG. 4 is a sectional view showing other various shapes of the control electrode plate.

FIG. 5 is a cross-sectional view showing a state in which a control electrode plate is installed on a developing sleeve.

FIG. 6 is a plan view showing the relationship between the width of a control electrode plate and the width of a developing sleeve.

FIG. 7 is a schematic sectional view of a developing device containing a non-magnetic one-component developer according to another embodiment of the present invention.

FIG. 8 is a cross-sectional view of a developer layer forming member and a control electrode plate that are in contact with a developing sleeve.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photosensitive drum (image forming body) 2 (Y, M, C, K) Scotron charger (charger) 3 (Y, M, C, K) Exposure optical system (exposure means) 4 (Y, M, C) , K) Developing device (developing device) 41 Developing sleeve 411 Conductive substrate 412 Resistive layer (coating layer) 413 Elastic layer (rubber layer) 42 Developer layer forming members 421, 423 Leaf spring 422 Elastic body blade (regulating blade) 80 Control electrode plate 81 Support member 82 Electrode part 83 Insulating member D Non-magnetic one-component developer E ₁ , E ₃ DC power supply E ₂ AC power supply F1, F2 Contact pressure

Claims (6)

[Claims] 1. A developing device in which a one-component developer layer is formed on an outer peripheral surface of a developing sleeve and develops under a non-contact developing condition. ^Three
A developing device, comprising: a developing sleeve having a resistance layer of about 1 × 10 ⁷ Ωm ² ; and an elastic control electrode plate pressed against the outer peripheral surface of the developing sleeve. 2. A developing device for forming a one-component developer layer on an outer peripheral surface of a developing sleeve and performing development under non-contact developing conditions, wherein a rubber hardness of 3 is formed on an outer peripheral surface of a conductive substrate to which an oscillating voltage is applied.
A developing device, comprising: a developing sleeve having an elastic layer of 5 ° to 65 °; and a control electrode plate having elasticity that is pressed against an outer peripheral surface of the developing sleeve. 3. A developing device in which a one-component developer layer is formed on an outer peripheral surface of a developing sleeve and develops under a non-contact developing condition. ^Three
抵抗 1 × 10 ⁷ Ωm ² and rubber hardness 35 ° -65
A developing device, comprising: a developing sleeve having an elastic layer having an angle of °°; and a control electrode plate having elasticity which is pressed against an outer peripheral surface of the developing sleeve. 4. A developing device for moving a one-component developer on an outer peripheral surface of a developing sleeve to an image forming body surface under an oscillating electric field, wherein: a developer layer forming member contacting an outer peripheral surface of the developing sleeve; And a control electrode plate having elasticity in contact with the outer peripheral surface of the member. The contact pressure of the control electrode plate is set to 0.03 to 0.3 times the contact pressure of the developer layer forming member. A developing device. 5. The contact pressure of the control electrode plate is 30 to 30.
The developing device according to claim 4, characterized in that the 0 g / cm ^2. 6. The developing device according to claim 4, wherein the developing sleeve is a roller having an elastic layer.